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8f0m3v | Why do graphics improve over time on the same generation of gaming consoles? | Technology | explainlikeimfive | {
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"A short version is rhat developers learn how to better utilize the architecture of the console. Meaning they can squeeze more performance and thus create better visuals.",
"Imagine I told you that you would be using Excel 2019 for the next 7 years. At first, all the new stuff is a bit confusing and you make stuff, but it looks only passable. Over time, you figure out the shortcuts and all of the extra tools that are built in. Your stuff gets better at using the program, despite nothing else changing. Programmers do the same thing. At first, they have lots of power... so they can get stuff to work, but they are just muddling through. As they get more experience, they know how to optimize performance or the engines that they are using get upgrades. As a result, they use the power more efficiently to give a better overall visual."
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8f28gp | Will internet bandwidth ever be as ubiquitous and cheap as electricity is? | Technology | explainlikeimfive | {
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"That depends more on how you compare quantities than anything else. By some comparisons we're already there. The technology is already there, but sometimes artificial scarcity is more profitable. It's more a politics/economics issue. People won't pay more for internet unless they're unsatisfied with what they have.",
"For large parts of the population this is already the case and have been the case for years. The major difference between power and communications is that it does not matter where the power comes from but it matter who you communicate with. So in a remote area it is much easier to build a power plant then to have to route communications channels from all over the world. The opposite is true in densely populated locations where it is hard to build big power plants and keep them running while communications lines are much easier to install. Another big factor is how the industries are regulated. A few countries in the world are not regulating Internet like other utilities and have a general high level of corruption. So companies are able to create big unregulated monopolies which drives the price up considerably."
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8f8kpm | How do glass fibre optic cables bend without breaking or shattering? | Technology | explainlikeimfive | {
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"Glass is bendable, the thinner it is the more bendable it is. Glass fibers are very thin, and protected in plastic cables that make it hard to bend then too sharply."
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8f9nzf | In a time where phones charge in less than an hour, why do electric toothbrushes still take 12+ hours to charge? | Technology | explainlikeimfive | {
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"There usually isn't much demand for a fast charging toothbrush as they are expected to sit idle for long periods of time. A slow, gentle charging cycle saves cost and extends the life of the battery.",
"Inductive magnetic charging. Toothbrushes operate in wet environments. There are no exposed metal contacts like there are for a phone. Toothbrushes use concentric core inductive charging (through the plastic) and this process is less efficient. Ever see a wireless charging phone? They charge slower wirelessly than then charge when plugged in.",
"A fast charging phone is a $300+ device that is expected to be mobile & run all day long under its own power. Fast charging is a selling point for phones. You add the feature because people are willing to pay extra money for it. An electric toothbrush is worth less than $30, gets 10-15 minutes per day of use and sits on its charging station the other 23.75 hours of the day. Nobody gives a shit about fast charging so you use the cheapest thing that will work reliably.",
"Because of quality and battery types. Your phone battery is a special battery called a li-polymer ion battery, shortened Lipo. It’s the same kind of battery they use in RC planes and other places where you can draw and give a lot of power fast. Some cases you can pull over 50 amps with these types of batteries. Lipo batteries can handle a large amp charge of over 2 amps. Where many standard lithium ion batteries can only handle maybe .5 to 1 amp of charge. Else the battery will become too hot and risk exploding. This is the case of standard lithium ion batteries. They can carry a large charge, but becomes risky at high amps. Therefore they’re good for things like toothbrushes, remote controls and such. Where things that need a lot of power right now, you can use lipo batteries. I am by far no expert here, but this is what I remember the difference was from my RC days."
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8fe0bi | How do video game discs work? | This may be a stupid question, but how do video game discs work? I understand that CDs for movies and songs just play as they spin in a certain direction, but where does the information from a disc for a video game come from? Thanks! | Technology | explainlikeimfive | {
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"I believe all the data simply gets loaded from the disk and stored in the memory of the system, it doesn't have to look for every bit on the disk during the game. It's why you often have to install a game first, while you can just play music directly.",
"Basically the same but are compressed well enough and CDs can hold so much information that it can also include rendering instructions, music, videos, images, etc..."
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8fep1s | What is the purpose of the propeller on current hologram projectors? | Many hologram projectors have a spinning plastic beam that projects the image. Wouldn't make more sense to have a screen, grid, or lens (as conventional projectors have) for the holographic object to project from? Nothing I can find on H-projectors explains this aspect of the machine. | Technology | explainlikeimfive | {
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"> Wouldn't make more sense to have a screen, grid, or lens (as conventional projectors have) for the holographic object to project from? In no case does an image \"project from\" the device. A spinning arm tries to fulfill the goal of having an image in an area where there doesn't appear to be a screen. When the arm is in an area it flashes some light, and after it moves out of the way it allows the viewer to see what is behind it. The result is that you can see an image seemingly floating in thin air because most of the time the arm isn't in any given location, but while it is the light it outputs is very bright. Our eyes tend to blend the flickering light into the perception of it being solid and steady. Technically speaking this display is not a hologram because it lacks the aspect of a third dimension. It is no different from a flat screen that is transparent.",
"Can you show us an example of such a gizmo? I've seen lots of so\\-called hologram setups but I'm not familiar with one that spins."
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8fghf6 | Why does animation for movies cost so much? | Technology | explainlikeimfive | {
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"Because 3-D animation is exceeding painstaking. I had a roommate in college who did animation and he made a Pixar style short for his final project late in college. The four minute short took his team about half the semester just to make the models and plan out the actions, and the last few weeks of a semester he’d be at the lab working like 14 hours a day 6 days a week.",
"because the animators don't just draw flat or even basic models for the characters or the background. for Moana, they created a whole new physics model to make realistic water waves, splashes against rocks, canoe etc. here's a zoomed in screen cap of Incredibles. URL_0 those individual cotton fibers don't animate themselves. a team of computer programmer animators had to create a way to model cotton cloth to look realistic",
"Man hours, expensive computers and servers. The majority comes from staff salaries and they are generally well paid. Had some friends working on happy feet. They were a team of hundreds of artists and engineers working for several years.",
"Look up the movie Redline. While a lot of the drawing nowadays is done with heavy aid from computers, it still takes so much time. It's why you see so many reused frames in cartoons/anime. That shit takes time and money. Animating a simple walk cycle is difficult as shit. Redrawing backgrounds all the time is ridiculous (which is where speedlines come from). If you've ever wondered why in animation lip flaps look weird, it's because actually animating a character talking and having their lip movements match up would be incredibly time-consuming (voice acting would need to be finalized firsthand)."
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8fh51m | How does a player piano work? | Technology | explainlikeimfive | {
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"Player pianos are played by feeding a paper roll of \"music\" through the center of the piano. The roll has dashes punched out to indicate what music notes are to be played and when. As the roller pulls the paper through the piano the gaps trigger strings inside the piano to release, causing the hammer for a specific piano string to strike that string, producing sound."
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8fi2ih | How does split screen in video games take more processing power? | Technology | explainlikeimfive | {
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"The game is processing two instances of itself on one graphics interface. It's constantly updating the visual range of each player to their movements and changing the picture to match, but twice. Or four times. However many players there are. It's like running the graphics of the game multiple times at once."
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8fi7gr | How does each pixel inside an LCD or similar display know what color to display, and when to change colors so that the entire screen updates at the same time? | Technology | explainlikeimfive | {
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"I can't give you a proper ELI5 answer (hopefully that comes along, because I'm curious as well) but to get a good idea of what's happening on the screen I recommend you watch [this video]( URL_0 ) of both a CRT and an LCD, close up and in slow motion. One thing to keep in mind is that the entire screen doesn't update at the same time. Each pixel is updated individually, one at a time, in lines from left to right, top to bottom. (That's for a progressive scan TV in landscape orientation.) This happens incredibly fast. In a 1080p, 60Hz TV there are 2,073,600 pixels drawn each 1/60th of a second. But how a TV manages to do that is beyond me.",
"The entire screen does not update at the same time. It does so very quickly; it is too fast for your brain to notice the time difference. You can imagine each pixel as a sophisticated light bulb, Instead of a mechanical switch where a person needs to flip it up or down to turn the light bulb on or of, these sophisticated switches are controlled by electronic ones. These fancy switches are \"on\", if there is some electrical voltage applied across its terminals \\(and let's call this state \"1\"\\). The switch is off, if no voltage is applied \\(call it state\"0\"\\). Now, you can draw anything on a black and white LCD. Here is a line: 00011111111111111000 on a 1x20 LCD. Now, your questions is reduced to \"how do I calculate the value of every switch on my LCD, so it displays what I need it to\". For that, search for \"ELI5: How do computers work?\".",
"Behind each pixel is a transistor. The transistor has connection to a specific row and column electrode. For a 1920x1080 display, there are 1920 columns and 1080 rows. Actually, there are 3 times that because each pixel is made of three sub-pixels, one each for red, green, blue. Each sub-pixel has a color filter over it. At any given instant, only one combination of row and column is selected and the transistor for that pixel turns on. When that happens, the analog value on the column is stored in a capacitor. That capacitor is the pixel itself. That voltage is stored in this \"memory\" capacitor until the next refresh. It does not all update at once. The voltage alters the degree of polarization of the back light which passes through the pixel. That would be invisible by itself. On both sides of the panel is a polarizer, like polarized sunglasses use. They are crossed so that no light will pass unless the liquid crystal changes the polarization. All the circuits are transparent or so small you can't see them."
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8fiwo4 | why are loading bars and remaining times so inacurrate? | Technology | explainlikeimfive | {
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"Let's say the progress bar is for loading a game level before playing it. There of course the copying of data into memory that takes the biggest amount of time but also things like unpacking compressed files, executing code to prepare the game session, maybe connect to an online server for a multiplayer session and download the names and characters of the other players. All these things are difficult to measure exactly: 1. Loading data from a hard drive or SSD becomes faster and slower depending on how efficient the data is located on the device and how bury the operating system is with other things. 2. Decompressing files is hard to predict unless you already know the content of it in advance but then why would you need to unpack it? 3. If there substantial code to be executed during \"loading\" (or better \"preparation)\" it's impossible to tell how long that will take. It's even impossible to reliable tell if will end at all. This is known as the Halting Problem in computer science, if you want to read more about it. 4. Anything involving networks is impossible to predict. Connection speeds may vary. The connection may get lost and the whole thing needs to be retried. All these things combined make it very difficult to give an exact estimate for the complete process and when one of the steps goes very quickly, that's when the bar \"jumps\" but when for example the networking part is super slow, that's when it's not moving for a long time. The same applies to other complex processes in software. Installing an application is similarly complex, even just copying files round depends on many factors so it can show this effect."
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8fjlqw | How does an image get "burnt" into a screen? | Technology | explainlikeimfive | {
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"In the days of CRTs, an image was displayed by firing a \"cathode ray\" (basically, electrons) at a screen coated in phosphor, causing it to glow. But over time, the phosphor would deplete -- it would almost literally \"burn\" away. If you had a static image on screen for a very long time, the phosphor in the brightest areas of that image would deplete faster, leaving you with a shadowy \"ghost\" image that you would see whenever the screen was switched on. These days the technology has changed and modern screens are much less susceptible to burn-in. Although we no longer fire electrons at a glass screen, burn-in can still happen, especially with OLED screens. The tiny individual LEDs that make up each pixel become less efficient over time: they start to dim. LEDs that are used most often dim faster than those that aren't, and so eventually you end up with a similar effect to CRT burn-in. You're most likely to see this on phone displays where things like navigation bars are."
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8fjv50 | Why CAN'T we have the characters '\', '/', ':', '*', '?', ' < ', ' > ', '|' in a file's name in Windows? | Technology | explainlikeimfive | {
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"Each of them has a special meaning on the command line, so if they showed up in filenames they would lead to ambiguity. \\ is the path element separator on Windows and / is both the path separator on Unix-style systems and the normal command switch character. : is the character that indicates a drive name as well as being the path separator for old (pre-OS X) Macintosh systems. ? and * are characters used as wildcards (aka globs) when specifying files. < and > are used to redirect input and output to files. | is used to send the input of one command to the output of another command.",
"None of these are really five-year-old explanations. Here’s my stab: Suppose you named your dog “dessert.” After that, whenever you ask your parents “Can I have dessert?” they wouldn’t know whether to bring you sweets or the dog. Similarly confusing dog names might be: the trash, the car, etc. Special characters are like that, they have another meaning already and so if you use them as a name the operating system (your parents) gets confused. Windows takes the approach of not letting you use them as names. Linux requires you to be more specific about what you’re referring to - think of this as it making you say “Can you bring me my dog, dessert?.”",
"Because allowing that would make it too easy to really screw up. Other OSs like Linux are a lot more permissive when it comes to what characters you can use in filenames, but that comes at the cost of really simple shell scripts not really working the way you think they will if somebody actually goes all out an uses them. That is okay, though Linux people are all for giving their users the ability to shoot themselves in their own feet if they want to. Microsoft has a very different philosophy, they assume that idiots will use their OS and do everything in their power to idiot-proof it so that users and developers can't hurt themselves too much. With that comes a ton of restrictions like allowed characters in filenames that might not be strictly needed but make live a lot easier for everyone. Some characters like \"*\" and \"?\" are wildcards that mean any characters or any character. Allowing you to use them in filenames would open up the question of if you mean them literally or in their wildcard form when referring to a filename with them in it. Other characters are used in commandline to redirect output like > < |: and might be misinterpreted in that context. \"\\\" is separates folders in windows and so on. There are also a bunch of words that you are not allowed to name a file because they were used for something special all the way back in the days of Microsoft DOS like \"PRN\" and \"LPT1\" which used to have to do withe printers and others like \"CON\", \"AUX\", \"NUL\" and \"COM1\" and so on. In theory you could probably do away with these restrictions, but Microsoft feels it is better to be safe than sorry so even today you are not allowed to use any of these out of fear that it might break something because programmers simply assume that you would not be able to use them. These assumptions can lead to all sorts of interesting effects when you mount a file-system from for example Linux in Windows where the rules are more lax and have to realize that the Windows OS is able to see these files but won't allow you to actually interact with them because it insists files like that couldn't possibly exist.",
"It has to do with coding/parsing. For example your computer uses \"/\" as a directory designation so C:/my documents/pictures it would recognize as 3 different levels of folder. If you were to name an image file \"apples/bananas.jpeg\" and your computer went to look up that file when you click on it it would instead see \"bananas.jpeg\" in the \"apples\" folder. Each symbol has its own meaning and effect."
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8fjwai | How does power steering work? | Technology | explainlikeimfive | {
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"Power steering adds \"power\" to the steering mechanism of the car. You turn the steering wheel, and there's a sensor that detects how much. If the system is hydraulic, then power is transferred from the engine, via hydraulic pressurized steering fluid, to the steering mechanism. If the system is electrical, then the electricity drives some actuators. The system is designed to make it easier to turn the wheels, even if they are big and heavy.",
"In the olden days, if you wanted to turn your wheels, you, yourself, physically had to turn your wheels with the steering wheel. This requires a bit of strength to pull off. If you've ever wondered why NASCAR historically is a male dominated sport, there's one reason. Power steering uses hydraulic power or an electric motor to do the turning of the wheels for you. Your steering wheel functions as a controller letting the motor know how far to turn the wheels. It results in a less strenuous driving experience."
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8fpr62 | How does a new computer know the date when you turn it on, even if not connected to the internet? | Technology | explainlikeimfive | {
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"There is a small battery on the motherboard which runs a variety of things including a clock. If your computer forgets the time when it turns off this battery is likely dead. They typically last 3 to 5 years.",
"They are pre set in the factory. The onboard battery keeps the setting. Depending on where tho board was made and where you are will determine how accurate it remains"
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8frrpg | Rain-sensing variable-periodicity windshield wipers - how? | Was driving a 2012 Mercedes C350 today. Had wiper setting a the first tick intermittent (lowest). They don’t run at all when there’s no rain but speed up greatly the heavier it got without changing the wiper setting on the switchgear stalk. Doesn’t seem like it’d be measuring flow or humidity. How is rainfall rate detected or measured for this purpose? | Technology | explainlikeimfive | {
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"It is a sensor in the windshield. It detects the amount of liquid and adjusts automatically. I work for Mercedes and this question gets asked a lot haha.",
"When the rain hits the windshield, a little camera in the glass goes \"oh no, glass is wet!\" and tells the wipers to get their shit together and push the water away. The more often the camera goes \"ah! wet!\", the faster the wipers go.",
"An invisible infrared light is traveling inside the windshield glass. It goes from the top down to the bottom, where a sensor measures how much of the light reaches the bottom. When the windshield is dry, the light bounces back and forth inside the glass, and most of the light reaches the sensor. When the surface is wet the light doesn’t bounce back and forth - some light escapes when it hits an area where the outside is wet. So the sensor at the bottom can tell less light reaches it, and thus your windshield must be wet. Fun fact: light bouncing back and forth along the inside of glass is exactly how fiber optic cables work. They’re not electricity, it’s light being pulled inside. Same concept."
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8fs4zq | How do speech to text programs work? How do these programs pronounce words that aren't real? | Technology | explainlikeimfive | {
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"Basically, certain phonemes produce certain waveforms which can be recognized by speech to text engines. These are then refined by cross referencing dictionaries. So, if you say \"enough\" into a speech to text interface, it is read as \"EE-nuff\" which can be cross referenced to a dictionary to provide the correct spelling. For text to speech, the process is reversed."
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8fs65r | Why do cables that carry a digital signal (HDMI, Ethernet etc.) lose efficiency the longer they get? Shouldn't a digital signal be constant, regardless of length? | Technology | explainlikeimfive | {
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"Two reasons: resistance and capacitance. Resistance causes the signal to get smaller (lower amplitude) the further it travels. Capacitance causes the originally 'square' digital impulses to get rounded off to a more sinusoidal shape, which makes it much harder for the receiver to properly discriminate 'ones' from 'zeros'. This is especially a problem at the very high frequencies used in video and high-speed LANs."
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8fs85i | In historical movies you often see people being carried in litters. Why was this done when wheeled conveyances were available? | Technology | explainlikeimfive | {
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"Wheeled conveyances only provide a smooth ride on nice,. smooth terrain that doesn't have any obstacles. Even then, without pneumatic tires and any sort of suspension system, the ride is probably pretty bumpy. A bunch of servants carrying you by hand can better deal with uneven terrain and obstacles.",
"Litters were used to transport thousands during both world wars and up and through today. Wheels have trouble with bombed out infrastructure and unprepared surfaces. Thousands of litters were produced \\(particularly in Britain\\) in anticipation of massive casualties that never took place on the scale imagined. So there's an enormous surplus of litters \\(particularly in Britain\\) to the point where some places [made fences out of them after the war]( URL_0 )",
"Rome forbid the circulation of wheeled vehicles during a major part of the day to avoid insane traffic jams (imagine New York City without traffic lights)((or with, if you've tried driving there)). Litters could go anywhere, any time.",
"One of the things we take for granted in modern life is the presence of good roads. We think the road is crappy when it is just gravel or dirt. But even our worst roads, in the developed world, are much better than the average road in the old days. In a wheeled vehicle you had a very rough ride indeed.",
"Many different cultures have had litters of some kind, and their reasons may vary. In some, for example, important rulers were carried through the streets in what were effectively thrones carried by servants. It was a status symbol, showing that the person in the litter (a) was important enough to sit on a throne and (b) was rich enough to have servants (or slaves) employed purely to convey him from A to B. In others, roads were simply in far too poor a condition to take wheeled carriages. In Europe, litters were common at certain periods and in the big cities had some advantages over wheeled carriages. Litters could be taken inside a house, so ladies in particular could go from one house to another without ever having to set foot anywhere outside. In some cities, such as London, traffic congestion was a problem even in the 18th century: litters were less likely to get stuck in traffic, and they could also go down very narrow streets that wheeled carriages could not."
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8fx54i | Different voltage / current but same power, what is the difference? | Technology | explainlikeimfive | {
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"5 volt is common because it's the USB/Thunderbolt voltage. The connection can be used for both power and data so it became popular for cell phones. Since the connection is common, many other electronics became powered by USB. Some electronic components require higher voltages. For example, light emitting diodes (LEDs) require a voltage level above a certain value to begin emitting light. Certain LED modules will stack 2 x 2 LEDs in series so they need 4 times the voltage of a single LED. This is why you often see LEDs powered by 12 volt or 20 volt power adapters. Other components like computer case fans won't start spinning unless you give it a high enough voltage to overcome the friction within the motor. For components like laptops, it is easier (usually less electricly noisy) to lower the voltage than it is to increase it. Therefore, you would supply the largest voltage required for any component in the laptop first and convert it lower when necessary. This is why laptops can have power adapters in the 18-20~ volt range."
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8fxb3s | How do countries get rid of nuclear warheads when they decide they no longer want/need them? | Technology | explainlikeimfive | {
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"They take them apart and mix the plutonium with a ceramic forming a fuel pellet. These pellets are then shipped to the correct type of nuclear reactor and used as nuclear fuel. A lot of Soviet and American warheads dismantled due to treaties ended up as fuel in Canadian nuclear reactors as the two powers didn't trust each other.",
"Nukes are essentially just uranium or plutonium surrounded in metal, and that metal is surrounded with TNT (depending on which material you picked earlier). So its very possible to simply disassemble them. You could salvage the materials for other things. I am pretty sure you can still use them for nuclear fission. Edit: especially = essentially",
"Generally, you would remove the payload and then repurpose the material inside because it’s still nuclear material. If it’s waste, than the gold standard these days is to encase it in glass and then stainless steel and then bury it, however depending on the government getting rid of it the disposal method could go anywhere from putting it in a holding tank to dropping it in the middle of the ocean.",
"It's a pretty straightforward process. The warhead is dismantled and anything reusable is recycled. The non-nuclear components (the casing, electronics...etc) can be recycled. The actual core of uranium and/or plutonium is diluted and can be used as fuel in nuclear reactors. The fusion fuel (in the case of boosted fission or thermonuclear warheads) is disposed of as hazardous waste. Anything that's been irradiated can be stored as nuclear waste.",
"The really explodey bits inside can be separated from the less explodey bits that are needed to make the warhead super explodey in the first place. The really explodey bits can then be used in other safer ways, like to charge your iPad!",
"You re-use them - those elements are rare and useful. Nuclear weapon payloads are very highly-refined Plutonium (Pu) or Uranium (U), depending on the design of the weapon. By refined, I mean the specific type (isotope) of that element is there in far larger abundance than in nature - so much that it can chain-react and go nuclear, as designed. A fair bit of efforts goes into separating the useful 'weaponisable' type of each element from the 'useless' (and more common) types. When you're talking power, Uranium reactors run on a far lower concentration of the type (isotope) that's used for weaponry. In this case you have to reduce the concentration of the Uranium-235, usually by mixing it with raw-mined low-concentration 'natural' Uranium, or with already-spent 'depleted' Uranium. In contrast, Plutonium reactors use highly-refined fuel, much the same way Plutonium-fuelled nuclear weapons do. In that case you can use the same fuel in each, and it's just a matter of physically changing it to the shape of a fuel rod. FYI, Uranium is the more common payload... and there is the added step of getting the payload out of the rocket, but that's comparatively trivial.",
"Give them to Russia in exchange for their agreeing to respect your territorial integri- Oh.",
"Lots of good answers so just to add a little tidbit on the topic [Project Plowshare]( URL_0 ) was a US program that looked into exactly this in the 1960's (named after the bible quote to beat down your swords into plowshares). Since at the time the US and USSR had collective nuclear stockpiles in the 10's of thousands of bombs (remember that only 2 have ever been used in warfare) so they were looking for ways to use them for productive rather than destructive purposes. These include: using nukes to create open-pit mines, manufacturing of high atomic number chemical elements, and removal of the enriched uranium for use in nuclear power.",
"This doesn't specifically answer your question about nuclear weapons, but on a related note, at the Blue Grass Army Depot in Kentucky, they're almost done completing the Blue Grass Chemical Agent Destruction Pilot Plant. This facility is going to dismantle all of the chemical weapons the US has stored there over the last century. Things like mustard gas, VX and other nerve agents. There's another facility like it in Pueblo, Colorado. You can Google both, and find a decent amount of public information on it, including videos on how the process works. My limited understanding is that they send these missiles and canisters through an assembly line with various chemical and heat processes and at the end are left with basically scrap metal and non-potable water. I did some minor construction work there so we were only given a very basic orientation on what was going on. Again, pretty much all public information. But I remember our instructor telling us that the old alternative for disposing of this stuff was to basically take it to a remote desert or cave or something and just blow it up.",
"The UK has begun dismantling some of its warheads, but hasn't come up with a final disposal plan. A 2016 government report laid out three proposals: 1) Convert the plutonium to a stable ceramic and send it for deep disposal (in a repository which hasn't even been planned let alone built); 2) Convert it to fuel and use it in the UK's own nuclear reactors, or; 3) Make fuel and sell it abroad. The committee couldn't decide which was the safest and most economically feasible route, but did point out the energy security benefits of the second option. However, this doesn't seem very likely because of the ongoing scandal of the UK's reprocessing operations which are costing a fortune even as they are being scaled back. The UK was a pioneer in separating plutonium on an industrial scale because its first Magnox reactors used fuel that couldn't be stored for long periods of time after removal from the reactor. Even after the UK stopped extracting plutonium for warheads, Magnox had to be reprocessed - and plutonium recovered - come what may. The result was an enormous pile of plutonium that needed a home. So, in the 1970s, a decision was made by British Nuclear Fuels that the UK would recover plutonium by reprocessing spent fuel, not just from UK reactors, but from all over the World. The plutonium would then be mixed with low enriched uranium to make mixed oxide fuel (MOX) which would then be resold. That kind of made sense when uranium was expensive and resources thought to be limited. But as it turned out, nuclear power stopped expanding and uranium remained cheap. So the UK is getting out of the reprocessing industry - but we still have a lot of plutonium - not all of it ours. And I mean a lot - at least 140 *tonnes* of civilian plutonium - plus the classified amount of military plutonium used in our nuclear weapons programme (you need 10-15kg for a bomb). The MOX plant at Sellafield was completed in 1997, but it was announced in 2011 that it would be closing. Although it had a capacity of 120 tonnes of MOX per year, it had only managed 5 tonnes in the first five years. The shut down of the Japanese nuclear fleet following the disaster at Fukushima, and the ending of Germany's nuclear programme ended two major markets for MOX. Only one of the UK reactors, Sizewell B could accept the fuel - and it would need modification to do so. So £1.2 billion down the drain and we still have 140 tonnes of plutonium to deal with. This is all on top of the £150 billion or so that Sellafield will cost to clean up over the next century. If you're interested in the awe-inspiring (and slightly terrifying) operation at Sellafield, both routine reprocessing and the clean-up operation; BBC4 made a programme called Britain's Nuclear Secrets: Inside Sellafield - there's a copy here: URL_0",
"The uranium is used for fuel in civilian reactors. \"During the 20-year Megatons to Megawatts program, as much as 10 percent of the electricity produced in the United States was generated by fuel fabricated using Low enriched uranium from Russian Highly enriched uranium\" URL_0"
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8fze16 | How can my 4K TV show me clearer images than what my eyes can see in real life if it’s still my eyes seeing the images? | I have fairly bad eyesight if that makes any difference. | Technology | explainlikeimfive | {
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"> I have fairly bad eyesight if that makes any difference. This makes a lot of difference. If you look at say, a landcsape, your eyes and lenses are doing real work trying to focus on all the different things. Bad eyes may not ever be capable of focusing on certain distances. If you look at a *photograph* of the same landscape, the camera already did all the work to focus the image and your eyes only need to focus on the photo which is very close to you. The TV screen is more like a photograph. Your eye only need to see as far as the TV. There si no real depth in the image, it's a flat picture.",
"The tv is near you, so when an image simulates a 20 yard distance, you're seeing an image that looks like it has a depth that would normally be blurry for you, but since the tv is so near you see it accurately."
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8fze2y | what is the difference between REST & SOAP web services? | Technology | explainlikeimfive | {
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"A SOAP web service has a very structured request and response. Data types, required fields, etc., are all defined in a WSDL that you can consume with your application to automatically build the entire request structure. All of it goes over HTTP POST methods. The entire web service has a single endpoint that covers many methods. A RESTful web service is a more open concept that uses the raw HTTP data fields in the request to pass parameters. It also uses the HTTP methods (GET, POST, PUT, DELETE) to handle things differently. The URL is also part of your parameters, as that handles part of the function routing. (i.e., URL_0 would be expected to do stuff about inventory 12345, but URL_1 would be doing stuff about Customer 12345). The URL can also contain mandatory variables, such as those key ID fields."
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8fzg1t | How do camera polarization filters work? | Technology | explainlikeimfive | {
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"Light normally travels straight ahead in waves that vibrate up/down, side to side and any direction in between. In polarized light the wave is vibrating in only one direction. One way light becomes polarized when it reflects off a surface, especially like water or glass. A polarizing filter will only let light vibrating in one direction through. Imagine the filter as a picket fence with up and down slats. Only things that are vibrating up and down will get through. All light vibrating side to side will bounce back. Polarizing filters attach to the lens and are able to to be rotated to get the polarization in the right direction. The next time you are in a store that sells sunglasses take two pair of polarized glasses and line up the lenses. Twist one lens so that it is perpendicular to the other and no light will get through. The first lens stops all light but the waves vibrating in one direction the second lens stops all the remaining light that vibrating against that lens's polarization."
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8g0dvi | Why is video conferencing still iffy 15 years after Skype launched, even though internet speeds and processing power have gone up dramatically? | Technology | explainlikeimfive | {
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"As technology get's better we also require higher quality video. So yes the transportation of information has gotten better, but we are also asking more of the transportation network. Additionally video is really hard to do correctly. The way the internet works is by this idea of 'packets', it's sorta like a chunk of data that get's sent and then reassembled with all the other data on the other side. If it's a regular file that just counts from 1-100 (really any file that's not real time) you can send numbers in any order (8, 92, 4, 6, 23) and then just rearrange them at the end as long as you have all 100 numbers. This also allows you to \"drop\" a packet. So if you dropped a 25 and 46 during your transmission you can just resend at the end and finalize assembling. However with calling and especially video calling, you can't just reorder those packets willy-nilly. Every single packet sent needs to be sent in order, otherwise you could get \"hey you how are?\" instead of \"hey how are you?\". Additionally you can't stop the whole process when you lose a packet to resend it, as that would just continuously add to the time delay. Instead of the 1 or 2 second delay you have now, the longer the call the longer the delay, an hour long call would end with a 5 minute delay. So how do they overcome all these challenges? Well they interpolate some information. If a packet full of video is dropped they can estimate what the picture should look like based off of what it used to look like. If a group of five pixels is currently blue, but you don't know what they should look like 1 second from now, you can estimate they will probably also look blue. That's the choppiness you see. The robot voice is pretty similar, if you have part of the audio like the basic words, but not the intonation you can just set the intonation to be equal to what is was during your last good packet. This manifests as a 'robot' voice because it's pretty monotone. The ability to estimate this stuff on the fly is actually very impressive even though it does look pretty crappy when you have it happen to you.",
"It's because video conferencing isn't device to device, but rather device-server-device. Therefore, the weakest link is server capacity. Right now, video conferencing requires that the device send the video stream to a server, then the server send that video stream to the receiving device. The reason is because of a patent troll called VirtnetX. Basically, VirtnetX's patent (which they didn't invent, but bought) allowed for devices to send a video stream directly to another device, only utilizing a server to handle establishing a connection. When Apple invented Facetime, they intended for it to be an open protocol for any device to be able to facetime another device, regardless of platforms. That requires a direct device-device connection. VirtnetX claims that it violates their patents, so Apple was forced to route Facetime through a server. That limits the amount of devices that can use Facetime, so Apple only made facetime for apple devices. Their servers can't handle all the traffic to every devices in the world. So why is video quality still so bad for conferencing? It's because of server capacities."
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8g5e1d | If a computer hash is procedurally generated, and will always result in the same output given the same input, why is it considered irreversible? | Note that I have password storage in mind as I ask this. | Technology | explainlikeimfive | {
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"An apple is red. A fire truck is red. The thing I'm thinking of is red. Was it an apple or a fire truck? Or was it a fire hydrant or a rose?",
"Its destructive math that loses some of the information to create the output if I take a message 1234 and do (12)^2 + (34)^3 = 39,448 you could solve back out what the message was, you'd have a limited number of combinations If I then take the remainder of (12)^2 + (34)^3 divided by 12345 then you have 2,413 which has a lot of possible inputs that can give you that final value, but only one(or possibly a few) will be useful values and only one will be the original You cannot write an algorithm that solves the input value from the output value as a single output value maps to an infinite number of inputs.",
"It's irreversible because it's destructive, information is lost in the process. The only way to reverse a hash is to plug the hash into a database and hope that someone has entered one, and only one input string associated with it. Hashes are of a constant data size regardless of the length of the input. For example, the length of an MD5 hash is 128 bits, the length of SHA-1 is 160 bits, and the length of SHA-2 is one of 224, 256, 384, or 512 bits depending on the particular algorithm used. For any given input, the MD5 hash of that input will always be 128 bits in length. A 5 byte text document and 1 gigabyte video both have 128 bit MD5 hashes. This is a one to one forward relationship. However, hash algorithms usually have no input constraints, the range of possible inputs is infinite. Thus, while any one input will have exactly one hash associated with it, there are an infinite number of inputs which will have that same hash. When two different inputs have the same hash, this is called a hash collision and programmers need to be mindful that this does occur."
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8g5rc6 | what is the benefit of rearranging software UI when everyone is already used to where everything is? | Technology | explainlikeimfive | {
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"There is always room for improvement. You might find out moving this over here, may save the user time. You might make your software feel more natural and easier to use, without a need of a manual.",
"You make an assumption that everyone of your target users is already using the program - and that not true. If you want to grow a business you generally are going to want to increase the number of users. Part of UI is helping new users “intuitively” know how to use new software by knowing who different user types are and how they will use the software (user personas), what other software packages they typically use, and what they expect to happen as they start navigating."
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8g5t9c | Why do phones, for instance, require a brick to be plugged into a wall but a lamp can be plugged straight in? | Technology | explainlikeimfive | {
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"The power that comes from your wall circuit is an alternating current. Lamps use this type of current without any conversion \\- it simply runs the lamp. Phones, laptops and other devices use direct current, and the block is required to change alternating current to direct current.",
"The other comment is correct. Electric current from the power company's lines is AC \\(alternating current\\) which is used as is by lamps and other types of appliances such as motors, heating, etc. Electronics require DC \\(direct current\\) so they have a \"brick\" with the components to convert the current. All electronic devices use DC, but some devices, instead of a \"brick\" they have the power cord leading into the device and the rectifier component is inside the device itself \\(e.g. TVs, desktop computers\\). See also [ URL_0 ]( URL_0 )",
"Everyone is correct with the fact lamps will utilise alternating current as a phone charger require DC to charge it. The other important factor is that your phone battery takes a voltage of 5 volts typically. As the power you get from the wall is 120v/240v depending on where you live, the transformer (brick) has to lower that voltage down before it can be utilised for your phone. Wireless chargers actually ustilise the AC voltage to create an alternating magnetic field, the phone has a set of coils that will energise from this field, the phone will then convert the voltage into DC to charge the battery.",
"incandescent light bulbs are very simple electronics. they only need current running through them to work. it doesn't matter if it's ac or dc. same with toasters or electric heaters. electic motors can run on ac so fans and blow driers can plug right into the wall. most other electronics run on dc so there is a method of changing the ac to dc. with a large appliance there is plenty of room to house the rectifier inside so all you have externally is the cord. smaller devices, and depending on the design, need the rectifier, and usually also a transformer (to go from the roughly 120 or 240v from the wall socket to the 5v your typical cell phone needs, for example) in a separate box. also, you can't charge a battery using ac so you'll need to change it to dc."
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8gd4sg | how is that even older MMOs, like WoW, can handle so many players, while modern games like Fortnite or PUBG struggle with just 100 players | Technology | explainlikeimfive | {
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"An MMO doesn't need to track players as frequently or precisely as with an FPS. This is because aiming isn't really a part of MMO play, meaning the relevant information is just if another player is in range of an ability or not. If the player is actually a foot to one side or the other doesn't matter in an MMO but is critical for the FPS. Another point to be made is that while a large MMO might have thousands of players on the same server, their information isn't being shared with everyone else playing on the server. Players which are a great distance apart simply won't ever have information exchanged about their actions which reduces load on the server.",
"Good answers already, but one thing to consider is what was important when these games were released. Older MMOs were devised in the early 2000s. Speeds were low, power was low compared to today. That means making these communications to track players and such needed to be ultra optimized to run on crappy hardware and with transmitting a minimal amount of data. Did you know you could play WoW good enough on dial up until the around 2011 or so? Seriously. Thats how different this game was made when it was released in 2004 (but started being made much before that). Plus the server hardware, and all of the points in between were terrible compared to today's options. Just think how little a new game has to worry about their user having a good internet connection or being able to support them with servers, if you need more space, you can buy it in seconds and have a new server up, in WoW that was *never* a possibility, it all had to work perfect as is, or there is no game. Tricks and optimizations were used very commonly in the past, in ways that today's games (although today's games are generally FAR more complicated) don't even have a need to consider finding these solutions"
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8ge0zh | How do telecoms and/or ISPs deal with massive, short bursts of traffic that come with arenas and stadiums that host 20-100,000 people at a time? | Technology | explainlikeimfive | {
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"They have mobile antennas on trailers they setup near events where they think the current signal will be overwhelmed.",
"At large events in Seattle area, the 4g bandwidth is fucked... LPT switch to 3g or analog on your phone To make calls etc when the network is busy...everyone eats up the cell towers 4g... but no one is on 3g... only way to make a call at seafair",
"What /u/SantasDead said. Also, atleast for newer projects. The buildings are set up with large fiber connections, wify and all that with some \"future proffing\" in mind, so they can handle the load 10 years into the future without having to spend millions later on upgrading. Or atleast, their is plans on the table on how to deal with it down the line.",
"Most stadiums have hardwired antennas built into the ceiling in a dozen or so places around the facility. They have the same capacity as a cell phone tower, but are more like flat plates, or bars, which can be mounted against a flat surface like a wall or ceiling. There are plenty of storage closets, and hallways with drop ceilings, so they hide the antennas and the associated gear out of view. It all runs to a central switching room, which is usually about 10'x10', all concrete. This room has all of the switching gear (and usually a heavy duty Halon fire suppression system in it.) used for routing all the calls. They are mounted in metal racks like you would mount computer servers in. Then they all are connected to a fiber optic line and go off to somewhere else in cell phone land, I don't know where."
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8ge1g8 | What's actually happening within a standard computer as it's booting up? | Technology | explainlikeimfive | {
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"### First Stage Boot Loader (Your Motherboard's Firmware) 1. Power comes on. Motherboard chip is physically programmed to go to a known location where it expects to find a boot loader. 2. The motherboard chip executes the boot loader, which tells it put some instructions into memory for the CPU. The instructions say look at the very beginning of Drive 1, Drive 2, DVD-drive, and USB port in that exact order. 2. Motherboard chip tells CPU to go execute those instructions that it just loaded into memory. 3. CPU reads instructions (which say go look at the beginning of Drive 1) and so it goes and looks at the beginning of Drive 1 4. If it finds a program at the beginning of drive 1 (ie. a Master Boot Record), it reads the MBR and does whatever the MBR says 5. If it doesn't find an MBR, it goes to the next instruction from step 2, which was look at the beginning of drive 2. This repeats until an MBR is found or there's no more instructions and the computer craps out 6. Once an MBR is found, it (the MBR) tells the CPU to load some more stuff into memory and then tells the CPU to execute that stuff. This stuff is the second-stage boot loader. ### Second-Stage Bootloader (GRUB, BOOTMGR, etc.) 1. The second-stage boot loader starts loading the kernel, where the device drivers live 2. It then figures out what operating system to load or may even hand off to another boot loader (like a dual-boot linux/windows machine) 3. It checks to see if the operating system told it to install some stuff before you shut it down last time, and if it did, will do those installs 4. It then loads the preliminary instructions for the operating system into memory. 5. It hands off to the OS by telling the CPU to go execute the operating system instructions it just loaded ### The Operating System (Ubuntu, Windows, OSX) 1. The operating system makes sure all the drivers loaded up 2. The OS checks itself to make sure everything is okay and that all the updates went through fine. It may end up needing to do more updates and will just restart your computer again, in which case start over from the top 3. Your OS loads things that it needs to work. This is usually the process manager, permissions stuff, watchdogs, and base services (like display service, time service, disk services, etc) 3. The OS starts to load services, that you, the user have set for your startup. This includes establishing your wireless connection, your anti virus, RealPlayer, chat service, Steam, etc. 4. The OS presents you with the loaded system (usually a login screen)",
"Really... lots. The power supply is attached to the motherboard by a cable that has some twenty-odd sockets. Connect two of those, and the power supply starts feeding appropriate voltage on all the necessary wires. This kicks off all the hardwares which also boot up (hard drives, gpus, they all have a tiny bios/firmware of their own, run basic diagnostics and load the embedded code which handles their interfaces). The motherboard also has embedded firmware, it boots up, performs some basic diagnostics and then loads the bios configuration. Meanwhile, the CPU also has its own little world it lives in, when fed sufficient voltage, the embedded codes will kick in, it will boot up and start chugging away at the tasks that motherboard throws at it. Hopefully, the bios configuration is not corrupted and will tell it where to look for the operating system proper. This is basically a hardware ID and some metadata that will hopefully match a healthy partition on a healthy attached hard drive. The hard drive will tell the motherboard about the available partitions, it has its own boot sector and partition table to describe the layout, and that partition must be marked as bootable or else it will not behave properly. Whew, okay, so the operating system is discovered. There is an entry point, from where everything begins. First load the kernel, which is like the very most basic functionality, way more basic than displaying a picture on screen (think reading files, launching executables, this sort of stuff). Check integrity, self-diagnose, then go on discovering the variois OS modules and drivers, finding the configuration, loading what configuration requires. Only then the command line UI becomes available. If you have a graphical interface and configured to use it, it will kick in almost immediately (unless your computer is very slow). Ye, lots of stuff.",
"Good question! Interestingly, almost all of your hardware is designed to wake up in a known state (usually everything at 0), instantaneously. That's actually the only time this happen, and that's why powering off, then on again, can clear-out issues so frequently. Not to be confused with rebooting! As the later needs to keep some \"state\", for instance to remember you wanted to bootback up. Then hardware/mechanical parts need to be put into a known state (your hard drive comes up to speed, your screen wakes up, your keyboard and mouse power on) and some components need to synchronize with each other (they start with a really low clock frequency like 50Mhz, then communicate and agree on the highest one they can talk to each other). Then finally, processor and memory are awake and can start to do smart things, like obey the BIOS instructions that dictate to look at USB drive, or SATA disk to find the bootloader in the first sector (address 0). Unless you press the magic key to go into BIOS configuration, in which case it runs a really basic display code (640x480 pixels with only terminal text and color) and basic keyboard support and cpu may still run at 50MHz. That bootloader is in two stage, a mini-OS that fit in ~2MB and mostly search for the true bootloader in a partition on your disk. This second stage is almost a true OS, it can do recovery, test the memory, talk to most devices (keyboard, mouse, screen), display some fancy graphics, decrypt partitions, etc. But is usually only there to ask you for your encryption password (if any) and/or which OS you want to boot on (if more than one). It then copy the OS into memory, and let the CPU go wild on it. OS is there to last, it setup its cosy place in memory, configure the CPU so that only OS code has all the privilege, run all the configuration of each device (in parallel for great OS, one after an other for crappy OS). This is the part that takes most time as it needs to read a lot of instructions to check everything, and hardware manufacturers are known to write the shittyest software ever, as long as it does the job eventually. (To be fair, drivers are a pain to debug/benchmark because they are in the OS, not nicely in the userland). Then the OS start the first userland program. On Linux it is init/systemd and will be in charge of launching then 50 different apps that starts at login. (Probably the other majority of the time is spent there) Then things are good to go. Most apps are a little slow right after startup as they need to read their configuration on disk or on the internet, instead of in memory cache. But then, everything works... for a while."
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8gfnlp | What exactly is the purpose behind the Lorem Ipsum Text? | I know it's used in the printing industry but how and why I have no idea | Technology | explainlikeimfive | {
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"[It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content here, content here', making it look like readable English. Many desktop publishing packages and web page editors now use Lorem Ipsum as their default model text, and a search for 'lorem ipsum' will uncover many web sites still in their infancy. Various versions have evolved over the years, sometimes by accident, sometimes on purpose (injected humour and the like)]( URL_0 )",
"It's just a placeholder. It looks like a proper piece of writing, while just hitting a bunch of random keys doesnt. That means you can get an idea about how actual text is going to look in your layout without having to find/write something.",
"It also is helpful when trying to determine the (very rough) word count. I am a magazine art director and my editors often request a word count if the article is not written yet.",
"One small thing to add might be the fact, that with something so known as placeholder text, its way easier to look for placeholder text - very often if you think \"okay, lets find some random text to use as placeholder\", you might spend more than enough time thinking what to use, then how to find it properly formatted, and so on... but with Lorem Ipsum as an option, it takes you less than 10seconds to find perfectly formatted text to drop wherever you need it. Even though this is not *really* an answer, more of a \"side-effect\" of Lorem Ipsum being a thing. Its nice to have some \"unified system/text to use\"."
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8gfoeq | Different between internet and world wide web? | Technology | explainlikeimfive | {
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"The Internet is the physical and logical connections connecting computers to a world wide communications network. The world wide web is run on the Internet. Web pages are part of the world wide web. Without the Internet the web would not work, but the Internet works just fine without the web. While the beginnings of the Internet started in the late 60's, the web was created in 1989/1990.",
"A simple example: The web is when you pull up a browser, go to a website and surf around. The internet is the network that makes that possible. When you use your phone and you're using an app (gmail, calendar, messenger, facebook), you're not on the web, but communicating through the internet.",
"The WorldWideWeb is part of the internet. The Internet existed long before the web came along. A large number of different service run over the internet like email and FTP. When the web was first invented [the inventor posted the announcement onto the USNET]( URL_0 ) which was part of the Internet and made the first webbrowser/client available for download via FTP (also running over the internet). Over the years since then the web has eaten many of the other parts of the internet so that the two have almost become synonymously to endusers, but the web is still only part of the net."
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8gfxhd | Why does changing screen resolution (more specifically, a custom resolution) will harm your computer? | Messing with the Intel's Graphic control software, and I found this message when I clicked on "Custom resolution". URL_0 Transcript: > "Warning: Altering resolutions may (i) reduce system stability and useful life of the system and chipset; (ii) cause the chipset and other system components to fail; (iii) cause reductions in system performance; (iv) cause additional heat or other damage; and (v) affect system data integrity. Intel has not tested, and does not warranty, the operation of the chipset beyond its specifications. Would you like to continue?" | Technology | explainlikeimfive | {
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"It isn't something to worry about these days. Even back in the CRT age it was extremely unlikely any damage would occur. Now it's mostly justn a cover your ass text they use. If you can't support a resolution these days it just doesn't show.",
"The key statement is “Intel has not tested, and does not warranty” the custom resolution. In practice, it’s highly unexpected for there to be long term damage to the computer, but unexpected things happen all the time in computing. Intel doesn’t want to take responsibility for a setting they don’t list on the hardware specs and which they haven’t proven to work in their labs. So what could theoretically happen? Among other things, * Unexpected voltage or temperature concerns causing shutdown or heat damage * Corner case hardware bugs that could cause graphics card or driver crashes or performance loss * Corner case software bugs which could result in driver or system crashes (“the device has stopped working” messages or blue screen of death) The above are a few things which Intel would have thoroughly tested for on standard resolutions before releasing the chip. But a custom resolution can’t be anticipated, so they have to add a legal notice that the user takes responsibility for what could happen next."
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8gkw26 | Why do movie companies add noise to movies when TV companies try to remove it? | Technology | explainlikeimfive | {
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"Noise requires more bandwidth to transmit faithfully, and TV is heavily encoded to fit into a pretty small band. Movies don't need as much compression, as they are sent in very high bandwidth channels like FedEx. Noise, on the good side, prevents objects from looking \"shiny\" and makes small movement more obvious. This helps you see facial expressions, the \"acting\" part of the images."
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8gkwke | Datamining a game | Technology | explainlikeimfive | {
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"Most games are developed using the same game engines such as Unreal Engine 4. These engines have identical ways to store files, render art assets or calculate physics. If you know how the game engine works, you can open the game files and find new files, assets, data and so on.",
"The process is pretty simple from what I understand. You go into the game's data folder and look through the resources (splash images, icons, sound files, text, etc). For example, if you go to the folder where a game stores hero icon images and you see a new file there, you can deduce that there will probably be a new hero released soon."
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8glq1u | Why cant movies and tv shows be on multiple streaming services like music is? | Technology | explainlikeimfive | {
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"Licensing. The streaming service has paid a chunk of money to be the exclusive platform for the movie. You can have exclusive deals with a music provider, but In general, music is “get as many outlets to play my shit for the exposure”.",
"They can be if the owner of the copyright chooses to sell it to multiple streaming services like the owners of copyright on songs do with their streaming services. But most streaming services for video negotiate to have exclusive streaming rights.",
"They can, many are, some have exclusivity deals. At one point It's Always Sunny for example was on Hulu, Netflix, and Amazon at the same time. Now it's not on Amazon certainly and unsure about the others."
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8gmb9k | How do things like radio or wifi transmit different types of data if they are always on the same frequency? | I know this essentially works with electromagnetic radiation, but how in the world does that transmit data or fluctuations? How does your router or the cell tower or the radio tower take data from someplace up in the sky, convert it into electromagnetic radiation, and make it readable for your phone? (details are welcome here) | Technology | explainlikeimfive | {
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"In very simple terms, in much the same way a DVD can hold music, or video, or a game, or software, the information is coded and formatted based on how and what is being transmitted (and how far). Different technologies use different parts of the electromagnetic spectrum with differing communication protocols",
"What it does is basically take a carrier frequency, like 2.4GHZ (short for 2.4 billion hertz, or cycles per second) and then sends quick, short lived, high energy pulses really close together. This emulates the shape of a square, if you were to look at the waves. The square in this case is binary \"1\". So any station will also broadcast a weak \"constant on\" littler square wave, which tells all listening devices that there's a device transmitting, and how strong it is etc etc. It's also the binary \"0\". There's a standardized duty cycle (how long or short the square wave 1's and their corresponding 0's are) too. This allows all devices using the same technology to share the same duty cycle within that frequency, and they all know how to receive the data the same. SO. The frequency is used to make 1's and 0's out of square waves and the weaker \"constant on\" signal. That's just the binary part. The data is organized by a predictable (standardized) set of patterns where every device knows who's sending and how to respond. Anyway, the frequency part is only important to shape the square waves. Because, you see, in nature, you can't get real square waves. You only get sine waves, which are curved. So what we do to make a square is we take a bunch of really skinny tall sine waves and pack them together. The higher the frequency, the more of these little waves we can pack together, the shorter we can make the duty cycle (which means more data per second) without losing the square shape. I hope this helps i gotta go my ice cream is melting Post ice cream edit: the antenna in your phone is printed on the circuit board. It's naturally 'resonant' with the chosen frequencies. Also your phone can change the inductance and capacitance of the antenna to pick up slightly higher and slightly lower than resonant frequencies. Anything can be an antenna, almost. But only well designed ones will pick up a signal well. Look up impedance and resonance, too. If it helps you, think of EM waves like you would think of sound. They have all the exact same basic principles. People have even used sound to transmit data, and have made antennas that work on sound waves. This all is a HUGE subject that few can really explain in a short amount of time. Good luck! Big feckin rabbit hole."
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8godmk | why does 2001: A Space Odyssey look and sound like a movie from the 90s and not the 60s? | Technology | explainlikeimfive | {
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"Because Kubrick did a really good job. He relied on effects that could be done well given the technology, and left out ones that couldn't. If you were to try and make the same exact movie today, without adding any more effects or content, there's not many parts that could be done much better.",
"The miniature effects for the space craft are all very slow, which gives them weight and believability. These effects were ground breaking and it wasn’t until Star Wars 8 years later that broke new ground in the addition of speed and action, that subsequently made visual effects much more accessible. You may like the look and feel of Silent Running (1972) as well, the effects are great for the time. That said I think it looks like a 60’s movie because of the fashions within from dress to hair. Also a lot of the occupations are stereotypical for the decade. For example the service industry jobs within from waiters to air hosts are all female. All of the executive and scientific roles are male. That’s not a slight on it all, I love the movie and expect to see cultural trends from the period it was made in. There is also no electronic/synthesized music, which was very popular for 90’s sci-fi. The orchestral soundtrack for sci-fi is mostly only seen in pre synth times and Star Wars movies as Lucas rightly prefers John Williams’ approach to action. I could ramble on about this all day, as it’s such a good cinematic experience, but I’ll stop here. Great question.",
"I think everyone is missing the point slightly, it’s not just the director’s style or the quality of thee special effects, it’s also the color and sound quality of the movie itself. Music and movies from the 60s usually have a distinctive sound due to the quality of the microphones but 2001 doesn’t share that. Can anyone explain what I’m referring to because I think that’s a big part of the answer to the main question.",
"I disagree with the premise of the question. I think it looks as 60's as John Lennon in a Nehru collar. 90's movies were more flashy.",
"What others have said about Kubrick, his brilliance, and his approach to effects is a part of it, but I will venture a different explanation: It is a sci-fi movie addressing some major philosophical ideas, co-written by another genius, Arthur C. Clarke, who was all about ideas. In essence, the movie is about something worthwhile to think about, and it has thousands of littler ideas abundantly sprinkled everywhere. The effects service the storytelling and the interesting ideas in the story, not the other way around. It is not about the effects. Almost every sci fi movie made in the last 20 years uses some very lightweight plot, often without addressing anything interesting, exclusively to justify a lot of action. The effects are wonderful, but the movie doesn't make you grow. 2001 makes you think, makes you grow, and fills you with the wonder of a limitless universe. You don't need to pay a lot of attention to the effects, because your mind is occupied with something much more interesting.",
"The New Yorker answered almost exactly this question in an article a few weeks ago: “By rendering a not-too-distant future, Kubrick set himself up for a test: thirty-three years later, his audiences would still be around to grade his predictions. Part of his genius was that he understood how to rig the results. Many elements from his set designs were contributions from major brands—Whirlpool, Macy’s, DuPont, Parker Pens, Nikon—which quickly cashed in on their big-screen exposure. If 2001 the year looked like ‘2001’ the movie, it was partly because the film’s imaginary design trends were made real.” - [“2001: A Space Odyssey”: What It Means, and How It Was Made]( URL_0 )",
"If there were any similarities I would say it is because Kubrick was such an influence on just about every director.",
"90's? I still haven't seen a film that can surpass it' brilliance.",
"Has any body seen the sequel\" 2010 : the year we make contact.\"?",
"If I were to watch 2001 followed by any number of 90s movies I would in no way at all think it was made around the same time. 90s movies have their own distinct feel, as do 80s movies, and 2001 doesn't fit into it.",
"Stanley Kubrick is probably the closest thing film has to Leonardo Da Vinci or Archimedes. The way he made films was impossible to replicate and he would often talk to Steven Spielberg and say how he wanted to re-invent the form of cinema itself. He basically had a level of obsession and intricate precision with everything he did that was on another level that hasn't been seen since he died. He created 2001 in a time where having personal computers weren't a thing, let alone CGI. He pioneered visual effects with the help of people like Douglas Trumball and Phil Tippet who helped create some of the best miniature models of all time. And he would often consult other people like Arthur C. Clarke and talk to engineers at NASA on space shuttle designs. He built entire sets that relied on precise mathematical calculations including [a giant centrifuge set that was built on a rotating wheel]( URL_0 ) so the actors would run around in it while it was being rotated and they had to hit their marks at the right time so when the camera panned it would look like they were in artificial gravity. Stanley Kubrick also understood cameras and lenses on a profound level because he started his career as a stills photographer for Look magazine. So he had the technical skills that were on par with any DP/Cinematographer. He would often make the actors do real takes before shooting and he would test different lenses on his viewfinder so he knew which lenses were going to be used on each scene. Also he basically wrote the entire film himself, it was based on an Arthur C. Clarke story but the original story is so different that Stanley Kubrick re-wrote the entire film and did it his way. Another feat in of itself. Everything you see in 2001 is incredibly and painstakingly crafted in a way you cannot even imagine. Every frame and image has been chosen and planned out. Its a stunningly timeless film that is so modern and predicted so many things before its time. There's never going to be another film like it ever.",
"By coincidence, I actually watched the film yesterday, and thinking about it, it's held up so well because all the effects he used were processes that were still in use up until the 90s when CGI took over, and even now there are things that we still use today. They were processes that got a lot more commonplace during the 80s and 90s after Star Wars made them more mainstream and in doing so lowered the bar for entry, but it was all there back in 1968 when Kubrick made Odyssey. You had miniature work and model building, you had in-camera effects, you had matt paintings, and you had optical compositing. Those same effects are ones you can see in Star Wars, Blade Runner, and through into films like The Fifth Element, which used a combination of them with CGI. The only thing that really dated the film for me were the weird futurism furnishings in the Hilton space station - the strange, blobby, pink chairs that were very much a 60s fashion trend were particularly jarring for a film supposedly set in the early 21st century.",
"Kubrick was a master film maker and pushed film making and traditional effects beyond their limits for his time. A true pioneer.",
"In some sense, it's because \"2001\" *invented* what movies would look like in the future. The work has inspired every generation of filmmakers since.",
"Because Kubrick was truly ahead of his time. If only he had access to the tech we have today..",
"It’s so well made and stylish that it dates really well. Agree on fashion etc, but still. It’s just so good to look at.",
"Oddly enough, the most impressive effects are the apes at the beginning. Why bother with movies having CGI apes when you had that shit in the 60's?",
"Because you're too young to know the difference, apparently. Or haven't seen a lot of movies. Seriously, this is a crazy question. 2001 is perhaps the most \"60s-looking\" movie of all time.",
"The movie aged wonderfully but this is a huge exaggeration. As someone mentioned earlier, no one in their right mind would think this came out the same decade as Jurassic Park. The actors' mannerisms and speech alone stick out itself.",
"I’m not 100% on this as it’s partially a personal preference but Kubrick filmed 2001 on 70mm film. The film grain is much more fine and allowed for 6 track audio. Typically, movies of that time were filmed on 35mm with less audio tracks.",
"This is a really interesting question because to be honest, I don't understand it. 2001 has amazing and innovative effects for its time but it doesn't have that much aesthetically in common with '90s films. think OP just doesn't know what movies from the '60s look like."
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8gonvt | Video game designers, why do the computers never move at the same speed as you? It always feels like they’re a tad slower, forcing you to wait for them in campaign-style games? | Technology | explainlikeimfive | {
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"Yes. They kinda sprint and kinda not, so your walking speed is lower but your sprinting speed is higher. I wish someone could explain this.",
"I actually remember reading about this I think around the time half life 2 was released. iirc it's about player agency, making the player feel like they're still doing something even if all they're doing is following an npc. Something about it feeling unnatural to move at the same speed as the npcs.",
"Short answer: Pathing is slow and a pain in the ass. Long answer: It's a lot easier. You simply make the NPC you're supposed to follow uncollidable and set their speed so they move with a purpose but slow enough that the player can catch up. You set them to walk an exact path, one that doesn't have to calculate in real time, boom, npc escort in 10 lines of code. What devs are moving towards is a lot better which is NPC locking where you hit a button and your character matches speed with the NPC and you walk beside them. This, however, requires either some really careful game design where you don't hit anything along the way or a dynamic pathing system which tend to be *really* calculation heavy i.e. will kill the frame rate if it gets confused, and, spoiler, it will get confused. Because it's not \"game breakingly awful\" in a classic sense, that's what gets used, because it's easy, not very buggy and you can just copy paste code."
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8gqbnr | Why do downloads always slow down towards the end? | Technology | explainlikeimfive | {
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"A lot of progress bars are actually not following the progress of the download and are really just moving forward at a specified speed and when they reach just about the end they stop until the download actually finishes, it's a lot easier on the developers to have something like that instead of something that is actually tracking how much of the download is complete and what is left, etc. As for the ones where it isn't like that it's more of a watching water boil type of affect or coincidence maybe. I don't think there is a single answer for all occurrences of this but that's my best take on it."
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8gsy35 | If I took 2 identical samples of "uneducated" neural networks and learned them with identical data would the output be identical? Why? | Technology | explainlikeimfive | {
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"Keep in mind, assuming nothing goes wrong, computers are deterministic systems. A machine running the exact same software with the exact same inputs will give the exact same result. If all of your inputs are the same you should get the same result. You need to remember that the random numbers are an input too. Training a neural network involves creating random mutations, which requires a random number generator. The most common way of generating random numbers on computers is to use the current time as the seed for a psudorandom number generator, resulting in a different result each time it is run. If you make sure to use the same seed on both systems, ensuring that the random numbers are generated identically, the trainings should result in identical neural networks.",
"It depends on how you set up your neural network. In general, yes. The learning process for a neural network is deterministic, so using the same set of data would yield the exact same output. However, certain common methods often used with neural networks - re-ordering inputs and dropout come to mind immediately - use probabilities. Using such techniques, you'd have differences being the networks. That being said, the difference wouldn't be significant because large numbers of random numbers tend to have a very predictable distribution."
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8gvrl1 | How does wikipedia work..change..and update? | Technology | explainlikeimfive | {
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"Fundamentally, it's the same as Reddit or Facebook or any other website. When you submit content - be it an article, a post or a like - a record gets made in a database. The next time somebody views that page, the server reads that information from the database and builds a new page out of it. What makes Wikipedia unique is that (almost) anybody can edit (almost) anything and the system is set up to keep a history of it.",
"Wikipedia also has a well-established set of standards, which many users follow and help enforce. So it’s crowdsourced self-policing."
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8gy0w6 | How did we get metal to think? How does it know what the 1's and 0's are? Is it at it's core mechanical? | Technology | explainlikeimfive | {
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"You might be referring to [this quote]( URL_1 ) about computers \"thinking\". [Here is a really good video] ( URL_0 ) where people build a computer out of domino pieces. You can clearly see that those dominoes perform calculation, but they do not \"think\", it just happens because of the way they are arranged. Metal does not think either. A computer does not think. A transistor puts out electricity (1 or 0) depending if you give it electricity or not. After all, it does not know what is 1 or 0. It is all just a bunch of transistors that electricity goes through, which in turn do calculations. A computer doesn't think \"what is answer to 2 + 2\", you just put electricity into it and it gives out the result. Computer seems to think, because programs on the screen somethings say such things. \"Waiting to download...\", \"Processing...\" etc. Those are just abstractions which are created so humans would have some analogy what the computer is doing. All in all it is just tiny transistors that do not think. The computer does millions or even billions of similar calculations (like in the domino video) per second, sometimes the binary numbers represent data, like color, letter, internet address, sometimes instruction, sometimes something else.",
"It does not know what 1's and 0's are. We give meaning to a different combinations of them and we found out that were able to \"easily\" put the \"language\" of 1's and 0's to mechanical use. The CPU itself doesn't really know you typed \"a\". It sees \"01100001\".",
"> How did we get metal to think? By: * building an electrical component (transistor) where a voltage on one line can act as a very fast switch on a different line. * finding a super-miniuaturized production process for these components. * wiring them together in increasingly complex systems to store numbers, do calculations on those numbers and come up with calculations we can interpret as \"thinking\". > How does it know what the 1's and 0's are? It doesn't. Even the 0 and 1 are human interpretation of electrical charges and voltages. > Is it at it's core mechanical? No, it is at its core electrical.",
"You've gotten plenty of good responses to this but I want to try my hand at it anyway. Ground zero: We have things called transistors. These are basically just switches with 3 \"legs\". Two of the legs are the ends of a switch. The third leg controls whether those legs are connected. If I put voltage on the control leg, I connect the other two legs. If I take the voltage away, the two legs are no longer connected. If voltage is present we can say it's a \"1\", otherwise we can say it's a \"0\". We build these transistors out of that special rock Silicon because it's a semi conductor. It's not the only one but it's been the best one so far for various reasons. (Cheap, abundant, performs well enough, etc.)This is close enough to true for us to move on :) Next level: Putting these switches (transistors) together in special ways we can create slightly smarter switches called logic gates. These smarter switches can be made with multiple inputs that have to be in just the right pattern to turn the switch on. There's \"AND\" gates, and \"OR\" gates, and \"NAND\" gates, and \"NOR\" gates. (One fish, two fish, red fish, blue fish... sorry). AND gates require both inputs to be 1 to turn on. OR gates only require either input to be 1 to turn on. Putting these gates together in special ways we can make things like adders, multipliers, comparators, etc. The general theme here is that we started at almost nothing and build tools (transistors) that let us build other tools (logic gates) that let us build other tools (adders, multipliers, etc.) and so on. You've heard the term \"abstraction\" a lot in this thread which is exactly what's happening. \"Abstraction\" is basically building the tools of one level using all the expertise required for that (like transistors) and passing those off to someone else to work on the next set of tools (logic gates). That next guy doesn't have to worry about complicated things like transistor biasing, current requirements, electron tunneling, gate width, element doping, substrate separation rules, etc. All that next level guy has to worry about is that transistors act like switches! THAT is abstraction! And this idea works its way all the way up the chain. Eventually we get to processors, memory, programming languages, and pixels on a string. It all comes down to flipping switches in an impossibly fast and complicated manner."
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8gyih5 | how did "hunter" followed by a few numbers become a stereotypical bad password? | Technology | explainlikeimfive | {
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"dyflmib",
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"It came from an old meme about an IRC chat conversation where someone revealed their password as 'hunter2' URL_0 It's not necessarily a stereotypically bad password - it is a bad password though - but it gets used a lot when someone is guessing someone else's password so it just evolved to become the \"standard joke password\" as a meme.",
"[This classic tale]( URL_0 ) from URL_1 . In short, some guy trolls another person in a chat room, saying that if he typed his password it will appear as stars. He did, and of course it appeared normally. His password was hunter2."
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8gzpcb | How binary 1's and 0's translate into complex output? | Technology | explainlikeimfive | {
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"text": [
"01000010 01100101 01100011 01100001 01110101 01110011 01100101 00100000 01111001 01101111 01110101 00100000 01100011 01100001 01101110 00100000 01101011 01100101 01100101 01110000 00100000 01100001 01100100 01100100 01101001 01101110 01100111 00100000 01101111 01101110 01100101 01110011 00100000 01100001 01101110 01100100 00100000 01111010 01100101 01110010 01101111 01100101 01110011 00100000 01110100 01101111 00100000 01101101 01100001 01101011 01100101 00100000 01110100 01101000 01100101 00100000 01100100 01100001 01110100 01100001 00100000 01111001 01101111 01110101 00100000 01110111 01100001 01101110 01110100 00101110 00100000 The above translates to \"Because you can keep adding ones and zeroes to make the data that you want\". Essentially a long enough string of ones and zeros can be made to represent any data. So with a long enough string of them, you can represent each pixel on your screen and the color it's supposed to be. This creates the image on your monitor.",
"Have you ever seen those massive record-breaking domino shows? Those dominos are either standing or fallen, only 2 states. But if you put thousands of them you can make them show pictures/patterns. Computers have many orders of magnitude more bits. But the basic theory is just that."
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8h0ns8 | Why does every website want permission to give me notifications? | Why does every pseudo-news website want to have notifications turned on and how do these work? Will I get a notification if my browser is closed? Will I get a notification if I'm on another website? And what the hell are they even trying to notify me of? | Technology | explainlikeimfive | {
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"Chrome has a notification API, and other browsers may have adopted it also. The intent was to make web apps more like native apps. Chrome has a background process that runs even if you close the browser that will show notifications, so yes you will see these notifications if you're on a different website or if your browser is closed. The websites want to send you notifications because it's a way to get you back to their site. News sites will probably use it to notify you of new stories. I believe you can disable this background process by going into Chrome's settings, expanding the Advanced settings (bottom of page), then going to the System section and turning off \"Continue running background apps when Chrome is closed\".",
"If they can give you push notifications, you're much more likely to come back to the site when you see a notice. The more you come back to the site, the more ads they can show you. The more ads they show you, the more money they make.",
"Ever see an infomercial with \"but wait, there's more!\". It's the same sort idea or whenever you click out of an (usually) false advertisement, you'll get a popup with \"do you really want to give up your chance to win the latest iPhone for free?!\". It's the same type of deal. Originally, it was meant to be used logically - say on Reddit, you would get notified someone replied to you, like you would on say Skype. But a lot of sites just use it to grab your attention for more clicks/views and of course, because they advertise to you, they make money from it."
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8h25ma | Why is pointing a laser at an aircraft such a big deal? | Technology | explainlikeimfive | {
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"You can hit the cockpit windows and blind pilots. Go get one of those green lasers in your eyes and try to land an aircraft.",
"If you get hit in the eye with the laser, it can temporarily blind you. Not an optimal thing to happen to the pilot while attempting to land.",
"When lasers travel a far distance, they spread out a bit. When you point a laser at a plane, the beam spreads out so that when it hits the cockpit window, it lights up the entire cockpit with a bright green flash. When people say that it blinds pilots, they don't mean that it's literally causing permanent eye damage to them. But it's nighttime; the pilots' eyes are adjusted to the darkness, and suddenly there's a blindingly bright green flash. It dazzles their eyes, just like the flash from a camera does to you in a dark room. It takes a few seconds for their eyes to re-adjust to the darkness, which can be dangerous if they're trying to land."
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8h7bwb | How can two equal virtual adresses refer to two different physiqal adresses? | As I've understood, the virtual adress is built up by a page number and a offset. What I don't understand is how the page table could convert this into two different physiqal adresses when the page number and the offset is the same for both adresses. | Technology | explainlikeimfive | {
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"text": [
"Each process has its own page table, so the virtual-to-physical mappings can be totally different for every process. For example: process 1 can access virtual page 100, and its page table maps that to physical page 1. We then switch to process 2, which accesses virtual page 100, and its page table maps that to physical page 8."
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8h7phw | How did people with bad vision deal with their vision before glasses? | Technology | explainlikeimfive | {
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"dyhnazs",
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"text": [
"They didn't. They did work that didn't require them to have very good vision. There was nothing there could possibly do about it before corrective lenses.",
"My dad told me he had no idea people could see the leaves on a tree until he got classes in college. This was in the 1930s. He grew up poor."
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8h7vcn | How do graphing calculators (like Desmos or GeoGebra) work? | What method/algorithm is used to solve complex transcendental equations? What exactly goes on inside the ALU when an equation is being plotted? | Technology | explainlikeimfive | {
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"There are definitely lots of ways of accomplishing this, but I'll describe a simple method. Suppose for the sake of the argument that we have an equation that looks like this: y = f(x). For any particular x, we can run it through the equation to get the corresponding value, y. The main idea is to do this for all the x values the user cares about (usually all the points inside the graphing window). That will give you a set of 2D points which can be transformed and plotted by the rendering part of the calculator by connecting the dots. It's actually very similar to how children are taught to graph functions by hand. There are a few technicalities that are important to address, though. For one, most common functions are continuous, while the set of generated points must be discrete. To get around this, you can sample the function at any resolution you'd like. To look continuous, you'll have to have many samples over the range of the window (e.g. perhaps 1000 or more, but that ultimately depends on how chaotic the function is.) You'll also have to deal with holes in the graph. You'll see that some calculators, like the TIs will draw a vertical line where a value switches from -infinity to +infinity (e.g. in the graph of tan(x)), even though there is actually a discontinuity at that point. The vertical lines are their solution to the problem. Another would be to leave the cell blank, but that's very difficult to do for arbitrary equations. There's also the issue of how f(x) is actually calculated. Doing so requires building a model (usually a tree) inside the computer of the operations that need to be performed in the correct sequence. For transcendentals, the values are usually approximated with polynomials that can be evaluated efficiently, and other operations are usually implemented directly. (E.g. when the user writes 'x + 3', the CPU will execute the same instructions.) So to summarize there are a few major steps: 1) Build an internal model of the function you want to evaluate. 2) Decide on a window range. (-10 to +10, for example) 3) Evaluate the function N times for all x values within the window (usually evenly-spaced) to build a table of (x, y) pairs. 4) Draw the equation by plotting the points and connecting the dots. I've glossed over some of the details, but that should be enough to answer your question. Cheers! :-)"
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8h837n | Why has Twitter had the shittiest possible video playback system ever for so long? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Because it wasn't designed to do streaming they added streaming as a secondary service not primal service. Is like asking why this sandwich can hold the soup very well."
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8h8vmh | How is it that we can tell the difference between watching a recording of a completely still scene, and looking at an actual still image? | Or can we? It feels like there is something lively looking,maybe a slight flicker of the light, in still video footage whereas actual still images lack this. | Technology | explainlikeimfive | {
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"text": [
"If you take multiple pictures of the same scene they will be slightly different. There is away noise in a image senor the captured images will not be the same. So a video will not be a stream of identical images but almost identical images. It is also likely that the video compression algorithms result in that the noise result in a bit different compression for a larger area. So the result is that the videos changes a bit over time but the still image is identical all the time"
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8h94bw | What causes cars to go out of control when turning? | I've seen videos where people turn a car one way, then when they steer the other they crash because it turns too far. Why does this happen? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"They exceeded the grip of the tires Tires have three levels of friction. Static friction when the car is sitting still is the strongest. Rolling friction is when the tires are rolling on the road and is slightly weaker than static friction. Sliding friction happens when the tires loses grip and is now sliding rather than rolling, it is significantly weaker than rolling friction which makes it very difficult to recover from a slide If you turn too hard and your front wheels don't have enough traction then they'll start to slide and you'll understeer and fail to make the corner If you turn too hard and your rear wheels don't have enough traction then they'll break free and you'll oversteer which often results in a spin. The traction on the rear wheels is what keeps the car moving in a straight line, once you lose that traction then the rear end will just slide around. If you begin to over steer then the rear end will be rotating around to one side, if you over correct then it will come around too quickly for the tires to start rolling and switch over to rolling friction so it will continue to slide the other way and you'll keep swinging it back and forth and crash. Once you lose traction it becomes quite difficult to regain it."
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8hac2t | Why do rocket engines always go over 100%? | If the standard is say 104%, than why isn’t that 100%? | Technology | explainlikeimfive | {
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"> If the standard is say 104%, than why isn’t that 100%? The engines were designed for a given output originally which becomes \"100%\". Afterwards there are tweaks and optimizations made which allow it to go over that output, but instead of redefining that output as \"100%\" they just say what its output is compared to the baseline specifications of the rocket engine. Unless you are familiar with what specific tweaks were made to that engine you wouldn't know how much thrust the adjusted 100% would equate to.",
"The reference for 100% is max power at sea level. For shortperiods of time at altitude this can be safely exceeded. However, testing and quanification isn't done under those conditions."
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8hb4fg | What is bandwidth and how does it work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"To ELI5: You know how the road outside your house is smaller and slower than the interstate? That's the bandwidth of the road: the number of cars it can hold every second. Internet has the same thing, but for cat pictures.",
"The term comes from radio frequencies. You'll often hear of the \"AM band\" or \"FM band\", or \"shortwave band\" or whatever. These are blocks of frequencies in the radio spectrum allocated to that particular kind of radio. Within each radio band, each radio station is allocated a band of frequencies that it can use. For an AM radio station in the U.S., that band is 10 kHz. For example, take KGO which is assigned the frequency 810 kHz. In fact, KGO is allowed to use all the frequencies from 805 to 815, thus their bandwidth — literally the width of their band — is 10 kHz. For FM, it's 200 kHz. Analog TV stations were 6 MHz (I dunno what they are now.) Smaller bands mean you can pack the stations closer together frequency-wise, and have more of them sharing the same band. But smaller bands also reduce the quality of a signal. The 10 kHz bandwidth that an AM radio station gets means that its audio is limited to a peak of 5 kHz, which is why their music quality isn't so hot. An FM radio station can broadcast much higher quality music because it has more bandwidth. The same principal applies to signals sent down a wire or fiber-optic line. The simple fact is, any physical connection can only transmit data up to a certain upper frequency. Suppose the wire is good for signals up to 10 MHz. The amount of digital data you can send down this wire is a function of how it's encoded, but for the sake of argument, let's suppose that it's 10 megabits/second. If that's a dedicated line, then the computer that's using it now has 10 MB/s bandwidth at its disposal. But say the line is shared among several users. The ISP that owns the line might limit all the users to 1 MB/s bandwidth so that up to ten of them can be using the network at the same time.",
"Similar to pipe analogy but less abstract: Think of drinking as hard as you can through a coffee straw, then imagine it with a soft drink straw. You get more liquid. Imagine the liquid as internet. 1 Mbps is a needle. 12 Mbps is the coffee straw. 75+ Mbps is the soft drink straw. “Gigabit” internet is a garden hose. Most homes only need a drinking straw"
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8hbsrf | How do noise cancelling headphones work ? | Technology | explainlikeimfive | {
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"text": [
"A sound wave is the compression and decompression of the air around you at certain frequencies. Noise cancellation works by detecting this and decompressing the compressed air or compressing the decompressed air so that your ear drums aren't feeling the effect of outside noise and the pressure changes around your ear and are only hearing what the headphone wants you to hear. When you think about it as a sine wave then it is just producing the mirror image wave of the sound it wants to cancel out. When you add both waves together they null each other out. Edit: Added a word.",
"The headphones are listening for sound waves from the outside of the headset, and then on the inside of the headset it sends out equal but opposite sound waves (from what's coming from the outside) to cancel them out so you don't hear them.",
"Can noise cancelling headphones still give you hearing loss from outside noise (not what you intended on listening to)? Or just the sound wave really just cancel out? It sounds to my tiny brain that you now just have 2 different sound waves hitting your ear drum.",
"When two waves are travelling in the same area, they make a resulting wave which is equal to the two waves added together. Noise cancelling headphones try to replicate the sound entering your ear by the surrounding area, but in a special way, essentially \"reversing\" the wave. Pretty much, it outputs sound so that when the ambient noise wave gets added with the noise cancelling wave, they cancel each other out. Then it plays your music on top of that. URL_0"
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8hbzqi | How do thoae scammy top-down games make any money | I'm talking about those games that trick stupid straight guys with lots of anime breasts and claims that you can "raise your own dragon" but is actually just a really bad remake of Age of Empires \- how do they make any profit? Like surely whatever they earn pushing paywall purchases must be negated by how much they need to spend to host and run the games, as well as paying people to keep it working etc? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Cracked had an interesting article about this topic awhile back. It’s a comedy site, but the article is pretty well-sourced with hyperlinks. URL_0"
],
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"http://www.cracked.com/article_18461_5-creepy-ways-video-games-are-trying-to-get-you-addicted.html"
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8hc8wa | Why weren't army uniforms using camo earlier? | So, as far as I know most current uniforms use camo patterns made of greens/browns (or if they are single-colored, it's one of these colors) as to blend in with the surrounding soil or vegetation. But why wren't army uniforms camo earlier? Everytime I see old-school uniforms in period pieces, soldiers wear bright colors clearly indicating which side they are on. Only reconstitutions from WWI onwards use green/brown uniforms. So: -Did old uniforms really use bright easy to spot colors, or is that just a convention of period pieces? -If they really weren't using any kind of camo, what was preventing them? Seems like if would have been even more useful back when infantry was the bulk of armies. | Technology | explainlikeimfive | {
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"text": [
"In the 1700's, getting shot by other people on your \"team\" was a big problem, and color coding uniforms helps with that. You had to be quite close to shoot someone, because the firearms of the period were not excellent. By WWI and WWII, firearms were excellent. Also, at that time, armies had radios. This allowed more complex communication that the bugle calls of earlier periods. This led to better maneuver, and less \"friendly fire\".",
"Because older weapons were so inaccurate at long range, camouflage was not as much of a concern. It would be hard to hit someone even if you could clearly see him. So the conventional form of warfare was to group soldiers together in large formations. These formations were the elements used on the battlefield, and their massed fire, or a massed bayonet charge, would do serious damage all at once, so that the enemy lines might break and flee. Because of the importance of formations, an effective army needed to be well-drilled. They learned how to maneuver in formation, and communicated via drum and bugle. Flags and uniforms helped them identify their allies. While you might think it would be useful to have camouflage, if you couldn't identify other formations at a distance, it would be impossible to coordinate movement on the battlefield. You could be firing at the wrong people, even. The development of accurate rifles made large formations less necessary and situationally allowed for other tactics, which were developed throughout the 19th century. But it was the development of better artillery, and of automatic weapons, that made their use suicidal--the experience of World War I clearly showed these tactics were obsolete.",
"It's my understanding the style of fighting changed. Back in the day, you simply stood across from opposing forces and fired away. This is part of why being 'on the front lines' meant certain death and why it's such a scary place to be. Eventually, warfare evolved to involve more sneaky tactics, this camo became warranted. IIRC in the American revolutionary war, the tactic of hiding and ambushing and general guerrilla warfare was considered tasteless and unclassy. Disclaimer: I am an American and this and we is colored by my personal understanding of warfare throughout history, and I am also drunk, which probably affects my answer, grammar, and spelling. Not all warfare throughout the world followed this trajectory.",
"> Did old uniforms really use bright easy to spot colors, or is that just a convention of period pieces? They really used bright colors. War used to be very, **very** different than it is today. Before guns, most battles were fought by both armies lining up and charging at one-another. Swords, spears, clubs, maces, etc. were used in close-quarters combat. Bows and crossbows would have been used at longer ranges, but mainly for firing in large \"waves\", and not typically aiming at individual targets (it did happen, but only once the armies were engaged). So there was zero need to be stealthy, and every need to be able to stand out as being on the same side as your allies in close-quarters combat. Even during the US civil war when muskets were becoming more common, they were *super* inaccurate, and the prevailing tactic was to line up and fire all the muskets simultaneously (just like a volley of arrows) and hope to hit someone. It was only with the advent of *accurate* long-range weapons, and the obsolescence of of traditional \"a line of our guys charging at a line of their guys\" style of combat, that trying to make your troops harder to see had any real tactical value. ***** If you're interested in learning about the evolution of combat in WWI, I highly recommend listening to the \"Blueprint for Armageddon\" series of episodes of the *Hardcore History* podcast. Be warned, though, it's **long**, so be prepared for about a dozen hours of listening. But I think it's still **highly** worth it."
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8hcbaq | How does Reddit make and keep up millions of web pages? | Technology | explainlikeimfive | {
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"The trick is that there are no webpages to keep track of! There's raw data stored in various databases. When you request a user's profile (for example), reddit's servers fetch data from the database and create a page to display to you. They also cache the data behind the page so they don't have to fetch it all from the database as often. But the page that you see isn't stored anywhere. It's re-created every time it's viewed, from backing data applied to a page template that's the same for everyone.",
"Web pages are generated dynamically (when you request them) nowadays. The web server has a database that contains all the profiles and preferences, and all the texts of the posts, and just puts together a web page for you, when you visit. It's pretty simple (for a computer) to put together the menu with your subscribed reddits at the top, followed by the flair of the subreddit, followed by the posts sorted by \"hot\" or \"new\" in order. The web server gets all the pieces from the database and just puts them together like legos, complete with all the HTML code that's necessary to correctly display the page on your browser. If you think of it, it's much like an MMO game, where all the items and characters are in a database, and the world server just sends you the data encrypted so that your game program can put it together and display it for you in all its glory.",
"Each one is mostly text, so the storage would be relatively minimal. As for how they can keep track of/create that many URLs, there are a surpringly large number of possible combinations if you account for upper case, lower case, and numbers.",
"People don't maintain each page, servers do. In the simplest terms you have two servers, a web server and a database server. The web server displays the information you see and the database server stores the information. So whenever you view a page, the web server displays the template that encapsulates the information, and the database server provides that template with the information you see. The glue that binds them together is computer code. When you enter an article and press \"save\", the code gathers that information, like sub is \"/r/explainlikeimfive\", title is \"How does Reddit make and keep up millions of web pages?\", date/time posted is 5/5/2018 8:30pm, article was posted by LetMeSeeWhatThisIs\", etc.. then passes it to the database to be stored. When I come to the page, I'm asking the web server to show me info for this subreddit, so the computer code then queries the database and says \"Hey, show me all the entries you have stored for sub \"/r/explainlikeimfive\" with the title being \"How does Reddit make and keep up millions of web pages\"?, show me who posted what and sort them by most popular. Once it gets this info from the database, it then calls up a template, and loads the data into it for display."
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8hdn1u | The reason why Personal Hotspots on mobile phone can only share mobile data connection and cannot share wifi connectivity where the mobile is connected | Technology | explainlikeimfive | {
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"Because phones have one WiFi ‘device’ for want of a better word. It can either connect to a network, or create a network but not at the same Time. With computers, you could do what you ask, but only by addicting a second, additional WiFi interface.",
"They can now. My LG v30 has an option when tethering to share the WiFi connection instead of mobile.",
"They absolutely can - on paper. It's not a feature you see because what would be the point? If you're connected to WiFi, the other device can be too; mobile data (and hotspots) is generally used only when there is no WiFi. The only reason I can conceive if is to create a relay to extend the range of your router but that's very niche and probably not worth the added development cost; you can get a serviceable bridge for like £20 anyway."
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8he4px | How NASA predict outer and inner planets properties while they never went inside? | For example, assuming the information they can obtain is colors based on the telescope, how did they know that Venus was filled with Sulfur while the same color may indicate new substance inside other planets? | Technology | explainlikeimfive | {
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"Each element has its unique set of emitted and absorbed wavelengths. Scientists use these patterns like fingerprints to identify the material which is emitting or absorbing light.",
"We know that Jupiter, the biggest, is an enormously massive planet because of its orbital mechanics, the number of its moons, and the way it perturbs the orbits of the asteroid belt. We can know its volume from observation. Mass/Volume=Density so we know that Jupiter's Volume is so big compared to its Mass that its Density is so low that it must be made of gas and have little or no solid surface beneath those opaque cloud tops we can observe. An entirely different tool called spectrography can identify what elements and compounds the clouds are made of. Others have covered this. Mercury, the smallest, is tiny but extremely dense, close to that of iron, spectroscopy confirms this. Seismic studies of the earth show that it has a dense nickel-iron core covered by a rocky mantle and crust. Mercury appears to be just a naked nickel-iron core. It is possible that its rocky shell was blasted off in a collision. And so it goes for all of the planets and other celestial bodies including stars."
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8hewo2 | Why is Graphene not used to solve / better practically applicable aspects of life ? | Technology | explainlikeimfive | {
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"Because it is an emergent tech. We are still working out how to produce it in volume cheaply enough. Producing it in more than micrograms at a time is still difficult. Once that is achieved it will start popping up in a lot of places.",
"From what I know about it, it is VERY expensive and difficult to make. I’m sure like everything else, we will learn better, cheaper and quicker ways to make it so it will slowly become more ubiquitous over the coming decades.",
"It's expensive to produce in the quality that would make it useful, which makes it too expensive to use in Mass market consumer products. Right now the process involves a lot of time and human hand, so it is costly.",
"Graphene is absolutely used in every application where it is cost effective. That just turns out to be almost nothing other than research into how to make graphene cheaper. It's also why do don't make more things out of diamonds."
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8hfgz9 | What is the difference between Information Technology, Information Systems, and Computer Science? | I'm currently looking into studying Computer Studies and IT, IS, and ComSci are offered at my preferred university. I cannot seem to get a satisfactory answer asking around about it, so I came here. P.S. One thing of note is that a lot of the people that I've queried either believe that IT and IS are the same, while others regard them as *very* different fields. | Technology | explainlikeimfive | {
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"Cs - writing code and algorithms IT - maintaining hardware and networks Is - design and maintaining data systems - how to collect and process data"
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8hg4xt | How can a scratched DVD sometimes work when just 1 wrong letter can crash computer codes? | At least in my understanding, even the smallest scratch on a CD or DVD should destroy some bits of information. How can a scratched dvd can be still be used when one small fault like a misplaced semicolon or curly bracket in a computer code makes it unusable? | Technology | explainlikeimfive | {
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"Error correction routines. Essentially, they assume the disc will be scratched eventually and structure the data such that minor issues can be accounted for and dealt with.",
"Error correction can be a beautiful thing. If you have enough information around the error it's sometimes possible to correct it. Like filling in a missing word in a sentence. However in a programming language one misplaced bracket doesn't really have the same context for a program to find the error on its own.",
"To add to what everyone else has said about error correction, if a scratch is bad enough that error correction cannot recover the data, on an audio CD or DVD it may just show up as a glitch in the sound or video that can be played right through. A CD-ROM storing sofrware, like a PC game or old installation disk, can in a sense be less resilient to scratches because an unrecoverable error that affects just a few bytes in a critical computer software code can render said software completely unusable.",
"CD or DVD are encoded with an error correcting scheme that allow to recover errors, no matter where it is (there is no sensitive spot). The simplest example is to repeat 3 times: PPPoootttaaatttooo... Notice that this scheme has two major flaws: * It takes 3 times as much space * It fail if you have two consecutive errors (errors need to be sprinkled which is not typically what happen with a scratch) It helps if you interleave differently the 3 copies: Potato.Potato.Potato. Now you can scratch up to 7 consecutive letters and still decode perfectly. But it might require you to read the entire CD to do so, which slow down the reading speed. CD and DVD uses Reed-Solomon codes with a custom Interleaving Scheme (even QR Code use those!) which allows you to choose the trade-off between correction capabilities and waste of space and throughput. On CD you have a guaranteed correction for bursts up to 3500 bits in sequence (2.4mm long scratch). If this is stereo sound, they can compensate a loss for one ear by using the sound for the other ear. So they interleave those carefully (aka. put them far apart) so that a scratch will not usually corrupt both ears.",
"Let's say you have two people, a person playing a song and a person telling you how to perform some complex task. A horn goes off in the middle of their song/instruction \\-\\- they don't pause or repeat themselves, just keep on like nothing happened. How likely are you to care about the one or two measures of the song you missed, versus how likely you are to have missed a critical instruction that will ensure you screw up the task? That's the difference between corrupting a song and corrupting a program.",
"Without getting technical, the DVD is coded very cleverly. It is coded so that if it is scratched somewhere, the computer knows that there is a scratch, or \"that there is a wrong letter\". Then there are algorithms and coding schemes that can replaces the wrong letter with the correct one. Sometimes the disc will be so scratched up that the computer can't recover the data, and the computer knows this, so it will just complain rather than try to process the corrupted code. The processor then happily cranks away given the correct letter in the computer code.",
"Might be wrong here, but if I were inventing the DVD protocol, I’d put some redundancy on it. Most of the disk isn’t used anyways, so I’d rewrite the data, or make it to where I can recalculate lost data",
"A couple of other takes. The lasers and lenses will be focused below the surface of the disk. Just like if you take a photo very close to a chain link fend each you can focus past and the links will disappear the dvd will do the same with a surface scratch. Additionally you have error correction bits on the data bytes. So if only a couple of bits are dead then they can actually figure out what they should have been. And the way most video works are key frames and delta frames. They don’t store every bit for every frame of video. They store key frames ever so often and then track changes to it. If a key frame is lost you might get a visible glitch for a second. If you get bits corrupted in one of the delta frames, no biggie. Just skip it and show the next. This will result in stuff moving slightly further than intended. Note that the second two occur with both digital video signals (I.e. cable) as well as video streaming. Both of those can lose data in transit which isn’t a lot different than a scratched disk.",
"Adding extra data on the DVD so that if you get a scratch it won't matter to the side that decodes it. EEEExxxxppppllllaaaaiiiinnnn iiiitttt lllliiiikkkkeeee IIII''''mmmm ffffiiiivvvveeee.",
"In addition to the error correction mentioned over and over again, it depends on where the scratch is. The data is below the surface of the shiney side, so a minor scratch in the surface may not obscure the data.",
"Video and sound can easily survive lots of changes to the data. (\"1 bit off? That's OK. It just means that one pixel that is on a screen with thousands of pixels and only visible for 1/30th of a second is a slightly different shade of green.) Most of the bits make up the data rather than the instructions regarding the data. In a computer program, changing a few bits might completely change the instructions that the computer is trying to follow. Resulting in an error and a crash. (Maybe cause an infinite loop due to a response never getting sent, or maybe a crash due to an unhandled error.) In the case of a missing semicolon or curly bracket, you have a program that is reading the text you wrote (a compiler or interpreter) and trying to turn it into instructions for the CPU. It gets really messy to try to correct that without screwing other stuff up or getting something wrong. So instead it's better to just throw an error.",
"There is a protective layer over the data layer - that is typically what gets scratched first.",
"Each group of 8 bits (a byte) is encoded into 14 bits (a word). There are a lot more possible 14 bit combinations than 8 bit combinations, and not all are used. The encoding method makes sure that only certain 14-bit combinations are selected to be different enough so that if one of the 14 bits is wrong, it is still the closest possible to the correct one, so you can get back the original word and find the 8 bits it came from. Another technique to prevent the scratch from ruining things is to mix up the 14-bit words a little bit. Rather than just write the 14 bits in a row, write all the first bits of 33 words. Then write the second bits, and so on. This way, a scratch may ruin only one bit from a few words, rather than all the bits in the same word. Still, some scratches can ruin the disk beyond what the encoding can handle. Make sure to clean the disk from the center out, across the tracks, and not along the tracks.",
"Hey! Computer nerd here! So here's some basics on error correction. The simplest form is \"mirroring\". You keep one copy of the data on one side of the disc, and another copy elsewhere on the disc. If one gets scratched, you still have the other. The problem with that is that you need double the storage in order to have a perfect mirror, so enter \"parity\". You'll first need to understand Exclusive Or (XOR). a XOR b returns 1 if the numbers are different, and 0 if the numbers are the same. So the full table is: - 0 XOR 0 = 0 - 0 XOR 1 = 1 - 1 XOR 0 = 1 - 1 XOR 1 = 0 You can also do this on sequences of numbers. So XOR(0110) = (0 XOR 1) XOR (1 XOR 0) = 1 XOR 1 = 0. This is how you produce a \"parity bit\" for error correction. So to store 0110 with a parity bit, you would store 0110-P0. Now, let's say you've got a disc that stored 1011-P1. It gets scratched, and you lose a number. So now you have 10?1-P1. Now, all you need to do is XOR the remaining numbers together and you will find your lost bit. XOR(1011)=1. Yay! CDs and DVDs are actually much more complicated than that, but that's the basics of error correction."
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8hh02c | why is reddit's video hosting so much worse than gfycat and imgur? | Technology | explainlikeimfive | {
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"It's not that they cant, they just don't want to. Reddit doesn't run as many ads as imgur or gifycat so it doesn't have as much money per user to spend on big hard drives and fast internet to server better gifs and videos. Reddits idea is to just have people link to other content so they can put all the work on other sites."
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8hix48 | Why do some old games have 999 limits on things instead of the 16-bit or 8-bit integer limits? | Technology | explainlikeimfive | {
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"It has to do with the space allocated for the display on the screen for these items. For example if the size of the screen was limited to 20 characters it would be designed like this: Lives: 3 Items: __1 Time: 300 Pick up 998 items and you have: Lives: 3 Items: 999 Time: 231 Pick up another item and you have: Lives: 3 Items: 1000 Time: 23 The time is now 23 instead of the expected 230. To overcome this wrapping the number of items was limited to 999.",
"Aside from what the others have said, it's also worth noting that a lot of games do it out of tradition too. For example, Final Fantasy 7 has damage limits of 9999, despite using 32-bit integers and not having any UI-related problems with showing high damage numbers."
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8hmvpj | Why has there been a shortage of NAND chips in the last two years? | Technology | explainlikeimfive | {
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"This subject is controversial. Companies are being sued over RAM pricing... they’re accused of either mis-representing the amount available or intentionally failing to produce as much as people want, to keep prices high. NAND supply could be affected by similar factors, or it could be technical and market factors. There’s continuing/growing demand for cheap, power efficient storage but the newest 3D NAND tech has been tricky to produce. Meanwhile, phones are being sold with a larger amount of NAND storage. At the same time, desktop/laptop computers are moving away from spinning HDDs for storage, increasing NAND flash use for those devices. This holds true even when storage sizes aren’t increasing.",
"There are two popular technologies for NAND flash memory. The price of 2D NAND has been pushed so low that almost nobody can make money manufacturing the parts. Try to buy a 512MB SD card and Amazon will offer you a 2GB one that's cheaper. Higher densities of 3D NAND make that technology more profitable, and it keeps 2D NAND manufacturers from raising prices. So, everybody did what seemed like the right thing for them, they closed their 2D plant and invested money in a 3D plant. Alas, 3D is much harder to make and many 3D plants have low yield rates. There is simply not enough capacity. Nobody wants to open up their old 2D plant, because that's not very profitable either. Everybody is mad because they have suppliers that promised them xGB parts for $y and now can only deliver 1/2 of what you order.",
"I have been pretty heavily invested in Micron for the past 18 months and it has be very profitable. I will do my best to explain the current situation with memory. A few years ago there were about 10-15 memory makers producing DRAM and NAND. Micron, Samsung, and Skhynix are pretty much the only companies that make BOTH types of memory. The memory producers, in the past, simply over produced memory chips leading to cannibalization of profit margins. The weaker companies could not survive and were simply bought by what is now the big three. Micron, Samsung, and Skhynix. Toshiba, Nanya, and Western Digital still make NAND. Furthermore, in the past, DRAM and FLASH were almost exclusively limited to PC and Phones. The past 3 years have seen an unprecedented demand for memory in data centers. Compounding the memory \"tightness\" is demand from Smartphones, AI applications, the Internet of Things, autonomous vehicles, etc. The remaining companies no longer wish to completely decimate profit margins from over production and are, what appears to be, implementing a much more disciplined approach to production. Even FURTHER compounding this shortage is the fact that entry into this industry is INSANELY costly. New memory fabs cost about 5 BILLION dollars and the memory makers can't simply switch over production overnight. They have to carefully consider where to allocate capital and production. Making these highly specialized chips is also VERY hard and any problems in the process leads to the complete ruin of the chips. Micron has had a few problems with this recently and this only makes the supply that much more limited. TLDR: Supply and Demand with the suppliers not wanting to gut their profit margins and making further memory yields very difficult.",
"NAND has not been in short supply since mid 2017. NAND prices falling. DRAM holding pricing or rising. DRAM most definitely has been in short supply and demand driven (increased use in data center, gaming, mobile, SSD). Currently, NAND pricing expected to fall about 30+% in 2018 (no supply problems), however NAND manufacturers simultaneously lowering their manufacturing costs per bits sold faster, so still making lots of $$. Why? They are shrinking node sizes and offering more bits of memory on same size wafers through 3D NAND layering and stacking. Costs of Gb or gb much lower as a result and you will soon see greater transition away from Hard Disk Drives as SSD now cost competitive with HDD. The problem with this though is with each new level of stacking, space in the FAB's is lost for more machines and clean space needed DRAM another story. Only 3 manufacturers (of any real magnitude) left in the biz and they are reaching point where shrinking more bits into same die no longer reaping cost benefits. Finally, the big 3 (Samsung, Hynix and Micron) are hesitant to spend huge amounts of cash (5+ $billion for a FAB and 2 yrs to bring it on line) only to shoot themselves in foot by flooding market with too much supply, lowers average selling prices and lose money....like past cycless)",
"As 3D NAND margin is just too good to pass away, companies tend to risk developing it rather than building supply on 2D NAND. But 2D NAND transition to 3D NAND leads to more complex and longer processing time to create. This leads to lower supply, with higher demand from Data Center and Consumer SSDs."
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8hmx5w | How do computers work physically? | Technology | explainlikeimfive | {
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"It does a bunch of math. All that needs to happen is turn tiny chips on or off (way oversimplifying) to make the binary codes of everything digital like the instructions for each letter or videos.",
"Physically: think of light switches, 1 being on, 0 being off this is binary. Electricity is used to flip the switches. A clock is consistently running that with every tick turns the switch on or off. Now think of tons of these switches, this is where the memory or current application state is held. Applications interpret these light switch positions to display something to the user."
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8hopil | How do medical examiners know when things were done to a person's body before being killed or after? | Technology | explainlikeimfive | {
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"1) How much bleeding occurred from the wound. 2) If healing has started, or how much of it has happened. 3) Dead bone, muscle, etc react differently than living so breaking and tearing patterns can be different.",
"A living body and a dead body react in different ways to trauma - things like bleeding, healing, scarring, etc. A live body will bleed out of an open wound and attempt to scab over and repair the damage if given some time. A dead body won't do any of that - blood may drip out due to gravity depending on where the injury is, but nothing else will happen to the wound. So medical examiners in many cases can determine when the damage happened based on stuff like that.",
"Additionally, death by drowning or by smoke inhalation can be determined by the presence or absence of water or smoke damage, respectively, in the lungs. If a body is dumped in the water after death the lungs won't fill with water as if the person were alive and inhaled the water. Smoke damage works the same way. If a person died from the smoke instead of being placed at the scene of the fire after death the lungs will show that the smoke was inhaled. A dead body's lungs wouldn't be filled with smoke residue."
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8hopvv | What kind of service or "package" does a Tier 3/Last Mile ISP get from a Tier 1/Infrastructure ISP | Does the Tier 3 have a data cap? Or do they get a & #37; of the Tier 1's bandwidth or utilization? | Technology | explainlikeimfive | {
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"Tier 3 providers buy per gigabyte from Tier 1 ISPs and use the Tier 1 ISPs infrastructure. Tier 1's are forced by law to allow a minimum amount of Tier 3's so there aren't as many monopolies (we saw how that turned out). They generally turn it around and sell it at an upcharge and pocket the difference to keep themselves running. It's cheaper because the Tier 3 is guaranteeing they'll buy so many lines from the Tier 1, even if they aren't being used. Bulk discount and all that. They usually were put on the \"back burner\" of traffic priorities and got slower speeds because of it. I don't know if they have caps or not, since the ISP I work for doesn't implement caps."
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8hozgy | What does a computer do when it "extracts" a zip or rar file? Where is it getting that extra data from? | Technology | explainlikeimfive | {
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"It's extracting the compressed data from within the zip file. Compression attempts to store the same data in less space through clever math. As an extremely basic example, say you wanted to compress this string of characters: \"aaaaabbbbbcccccdddddeeeee\". Originally, the string is 25 characters long, but you could compress it to 10 by turning it into \"a5b5c5d5e5\". A program that knows about this type of compression knows that \"a5\" decompresses into \"aaaaa\", but the program that originally created the file doesn't know what these 5s are about. The computer needs to decompress or extract the string before that program is able to use it.",
"A zip file is data that has been compressed using an algorithm. You can think of compression like this: Let's say I have a string of letters: \"AAAABBB\". That's a total of 7 characters worth of space. However, I could instead notate it as \"4A3B\" to tell someone that there's 4 of the letter A followed by 3 of the letter B. In this way I have got across the same information in less space. It turns out a lot of data we use has redundant information that can be compressed using tricks like that. (Obviously it is more complicated in reality but you get the idea) Compression algorithms use these tricks to make the data smaller, and include instructions on how to get back the original data later. In effect, you can convey the same information using less space, at the cost of having to rebuild the data later. This is what \"extracting\" a zip file is; you are rebuilding the original data by reversing the effects of the zip compression.",
"It's basically generating the extra data by using special mathematical formulas. As an example, there is a compression algorithm called RLE (Run Length Encoding) which takes two numbers and repeats the second number by the first number. If the data in the file was \"05 07\" it would generate five 07's, like \"07 07 07 07 07\". So that took 2 bytes and expanded it to 5 bytes. ZIP/RAR/etc use vastly more complicated algorithms, but the principle is basically the same. They identify patterns in the data and use math to reduce those patterns to smaller inputs to an algorithm that can reverse the process.",
"The zip file builds itself on repeated patterns. So imagine that the input is this sentence. The zipper will see the word 'the' and go \"Well, that's used a lot, let us represent 'the' by some tiny code.\" It builds up this codebook as it runs through the file. Here, it would already start to add \"build\" into its codebook. Ooo, and now we add the word \"codebook\" because we've seen it a few times. And the words \"word\" and \"and\" etc. Some times, there might be no repetition at all to find, and you end up with a zipped file that is larger than the original file was. If you want to get dirty, google \"Lempel-Ziv\"."
],
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10,
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8hp55n | what is pre warping in virtual reality and how does it work to send images in less then 20ms | Technology | explainlikeimfive | {
"a_id": [
"dym21g1"
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"text": [
"The lenses inside a VR headset make it possible to focus on a screen that's inches from your eyes, but they distort the image. To fix this, the image generated by the pc must be distorted in exactly the opposite way. This is done by the VR runtime. (Oculus or Steam VR) Games generally render to a flat rectangular viewport, but when that view gets distorted ready for the VR display, many of the pixels are effectively thrown away because bits of the image get squished (edges) while other bits get expanded (centre). In fact to get the centre at maximum quality, the entire view has to be rendered at that higher resolution, so loads gets thrown away. Prewarping means getting the game itself to render itself distorted in the first place. That way it only needs to draw the pixels you end up seeing, and so is faster and and smoother. However, this has drawbacks because it breaks other tricks used by the VR system to keep a smooth update. Smooth and fast updates are critical for VR otherwise you feel very sick."
],
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6
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|
8hp7t6 | Why are the MDR and MAR necessary? | From my limited understanding of computing, it looks like the MAR has no purpose. The PC sends the address of the new instruction address to the MAR, and the MAR sends it to the RAM. Why can't the PC be directly attached to the address bus and send it to the RAM itself? Same goes for the MDR - why can't the RAM send the instructions to the instruction register directly? | Technology | explainlikeimfive | {
"a_id": [
"dylj1qb"
],
"text": [
"It used to work like that, back with CPUs were slow and synchronous. I a modern CPU, you can latch data into MAR and then let those lines float while you do something else. The memory can slowly herd some bits into MDR, latch them there, and then use its data bus for some other DMA device, like your video card. When the CPU needs the data from memory, it can get it from the super fast MDR registers instead of some bus that runs all over your mobo."
],
"score": [
3
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"text_urls": [
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8hsc62 | How do electromagnetic doors with RFID readers work, and what happens in the case of a power outage or fire? | Technology | explainlikeimfive | {
"a_id": [
"dym5uvs"
],
"text": [
"The RFID reader is connected to a computer that determines whether or not a specific RFID card is allowed to open the door. If it is, then the door is unlocked temporarily. > what happens in the case of a power outage or fire? Depends on the door. In almost all circumstances, the doors are \"fail safe\". Power is necessary to cause the door to remain locked, and, for safety reasons, a power outage or fire will cause the doors to unlock. A super secure government building might have some doors for highly sensitive areas that are \"fail secure\", meaning that the doors are locked by default, and power to the mechanism is needed to unlock them. Thus a power outage will cause those doors to remain locked until power is restored."
],
"score": [
6
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"text_urls": [
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|
8hsjtv | How does Google Maps know about current traffic congestions and jams? | Technology | explainlikeimfive | {
"a_id": [
"dym7ub9",
"dym78yw"
],
"text": [
"Google actually put out a statement a while back asking drivers to run google maps or Apple maps (whichever of the major gps apps you have on your phone), saying the more drivers have the app running while they are driving, the more accurately they would be able to display traffic data. Like someone else commented, they collect data from a ton of phones all the time, and your gps tracks location and speed. So if more people are running their gps, the easier it would be for google to see backups and traffic jams faster and more accurately.",
"Two ways. It can source public data feeds put out my muni authorities, state government etc, where they exist. And, now that everyone has a smartphone, they can read the location speed and acceleration from thousands of cellphones at once. If they see that five hundred Android phones on Highway X just slowed from 100km/h to 40, that's gonna be a jam."
],
"score": [
7,
4
],
"text_urls": [
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|
8htf8s | How do radio waves transmit song names? | Okay, so this may seem like a stupid question but, how do radios know what song name, artist and station name I am listening to? I am in a Volvo that displays the song name and it got me wondering, how is that transmitted over radio waves without disrupting the music? | Technology | explainlikeimfive | {
"a_id": [
"dymx40i",
"dymkeqz"
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"text": [
"Radio is pretty simple, one radio station you listen to actually sends out 3 signals that your radio puts together to show you the information. The first channel contains the sound of the left and right audio channel (L+R). It's like that so shitty old radios do work without problems. The second channel transmits the differential Signal of the left and right audio (L-R). And the third channel contains a digital signal just like your mobile phone. It contains all the random information that your car radios display shows (song name, radio station, genre of the music played, ...). Older Radios just receive the L+R channel. That works just fine but you have the sound for the right and left speaker playing out of both. Now engineers had to think of a way to add stereo functionality without breaking old radios, if they'd just send the Left and Right Audio signal old radios would only receive half of the signal and for some songs that could sound really shitty. But to keep old Radios running and enable Stereo sound the transmission got a bit more complicated. You get the L+R sound and the L-R Sound and newer Radios add and subtract those signals: (L+R) - (L-R) = L + R - L + R = 2 * R (L+R) + (L-R) = L + R + L - R = 2 * L This simple math operation allows a modern radio to generate the sound signal for the left and right speaker (L and R) without causing problems with older devices. In addition to that newer radios receive the third digital transmission that transfers a small amount of data. Again old radios just ignore that. Here's how the different channels are distributed over the electromagnetic spectrum: URL_0",
"Some radio stations transmit sub-audible tones alongside the music. The radio is designed to read the data these tones carry. The tones are outside the range of human hearing."
],
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3
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"text_urls": [
[
"https://de.wikipedia.org/wiki/UKW-Rundfunk#/media/File:UKW-Rundfunk-Basisband.svg"
],
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} | [
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8hunry | how the hell does a data breach the size of the Equifax breach even occur? How does it get so big without someone in their security noticing or stopping it before it reaches that point? | Technology | explainlikeimfive | {
"a_id": [
"dymq1ud"
],
"text": [
"If you knew a way to sneak into the cinema for free, you tell your friends. They tell their friends and at some point someone gets caught. They then replay the security footage and realise how often it was happening"
],
"score": [
9
],
"text_urls": [
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|
8hv4w4 | How exactly does recording and playing back sound work? | Technology | explainlikeimfive | {
"a_id": [
"dymrvjj"
],
"text": [
"Sound is pressure waves in the air. You use a microphone that contains a gadget (there's a few different types) that converts those pressure changes to electric current. Now typically this is very little current because sound does not contain all that much energy to begin with, so you send it through an amplifier. At this point you record the shape of that electric wave which corresponds to the shape of the sound waves. For replay you send it back to speakers which uses an electromagnet that moves a piece of metal attached to a cone of some soft and light material, to push the air back into the same shape of pressure waves that were the original sound."
],
"score": [
5
],
"text_urls": [
[]
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} | [
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"url"
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|
8hyuz4 | If you're not supposed to mix conventional and synthetic motor oil, how do they separate it when you recycle it? | I change my own oil. I bring the old stuff down to my townships recycled oil tank. Sometimes I use synthetic and sometimes not but it all goes into the same tank. (There's only one) | Technology | explainlikeimfive | {
"a_id": [
"dynkoqd"
],
"text": [
"The only reason you don't mix them is because then you're not really getting the benefits from the synthetic (and so you're wasting money). URL_0 URL_2 URL_1 There's nothing dangerous about mixing the two. That's a myth. Many synthetic oils are a mix of conventional oils anyway"
],
"score": [
15
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"text_urls": [
[
"https://blog.amsoil.com/can-i-mix-synthetic-and-conventional-oil/",
"http://www.pennzoil.com/en_us/education/know-your-oil/why-synthetic-oil.html#iframe=L3NvcHVzL3Blbm56b2lsLzIwMTZuZXdzbGV0dGVyLz9sb2NhbGU9ZW5fdXM=",
"https://www.thoughtco.com/mixing-regular-and-synthetic-oil-p2-607586"
]
]
} | [
"url"
] | [
"url"
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8hz6yd | What are Spotify's operating costs that report a Q1 loss of $49 million? Where does it all go? | Technology | explainlikeimfive | {
"a_id": [
"dynmog2"
],
"text": [
"- The fees they have to pay the record labels/artists for the music they use. - The development cost for the Spotify client application on many different platforms (Web, Windows, Mac, Linux, Android, iOS, Game consoles, and more). - The development cost for the Spotify server application as well, in order to serve everything - The deployment cost of the Spotify server infrastructure. - Various business costs, ranging across everything from marketing to HR."
],
"score": [
16
],
"text_urls": [
[]
]
} | [
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"url"
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|
8i0a5t | How do we go from bits of information (1's and 0's) to a line of text? | Technology | explainlikeimfive | {
"a_id": [
"dynwnds",
"dynwtaz",
"dynwtyk"
],
"text": [
"> what the very first 10 or 20 one's and zeros are? Strongly depends on what file format you're dealing with. The first 20 bits of data of a .txt file are the first 2.5 characters of the text. it is the responsibility of the program reading the file to parse the file and make sense of the information within.",
"You design a system that expects a certain number of bits (eg - 8) to define a unit of information. Those bits are just a number. That number is used to represents a text character according to some established code (eg - [ASCII code]( URL_0 )). it's pretty much the same with everything else a computer does - you figure out a way to describe it in numbers & then use the binary to represent a bunch of those numbers.",
"A Word document, that holds text, isn't a bitmap. It's not an image. Items such as the background being white are generally a property of the installation of Word, or even of Windows, rather than of each document. So the contents of a Word document file are really just text and formatting information. The layout that a particular program uses for its files is known as the file format. It's how Excel knows that the bits and bytes in a .XLS file can make a spreadsheet, and how Word knows what the contents of a .DOCX file represent. In recent versions of Microsoft Office, the document files are actually ZIP files. Rename a .docx to .zip for example and you can see all the various components of the file in order to understand more about what it contains. Similarly, an Adobe Illustrator file \\(which ends with .ai\\) is usually a PDF file. Again, if you have a .AI file and you don't have Illustrator, you can open the file with any PDF reader if you rename it. One more interesting thing. Every program file \\(ie, an executable file\\) in MS\\-DOS that had a .EXE extension generally started with the letters MZ to indicate that it's an executable file. MZ were simply the initials of the name of the person who invented that file format. Mark Zbigowski."
],
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3,
3,
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[],
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"https://www.asciitable.com/"
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|
8i2ig0 | How do natural channels get footage of inside an animal nest or ant colony? | Technology | explainlikeimfive | {
"a_id": [
"dyoj5wr"
],
"text": [
"Generally it's because of really expensive and powerful cameras. Often they use motion-sensor cameras that only record the time around when they sense motion, and so they can be placed in things like nests when they are unoccupied then conserve battery power and record when there's motion within the nest. Things like ant colonies can be seen with extremely tiny cameras if they're travelling through, or cameras with huge zoom and focus ability if it's just a look inside the colony. Many shots of nature, especially animals, rely on powerful zoom from a very long distance in order not to disturb the animals, or on hidden cameras that are motion-triggered and can turn on and record remotely."
],
"score": [
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|
8i2w04 | How does Apple know if an iPhone screen has been opened by another company/person? | Or iPad, whatever. They can always tell if someone other than an Apple employee has opened the screen! | Technology | explainlikeimfive | {
"a_id": [
"dyoid2e"
],
"text": [
"Well apple does not remove iPad screens. So any signs of a new display is a dead giveaway the device is not serviceable. Third party displays are noticeably different, in quality, the colors, the reflective quality. All those are easy ways to identify an iPad with a services screen. The iPad itself was never designed to be serviceable. iPhone displays are very much the same. The quality of third party displays are quite noticeably different than Apple displays. Once the device is open, usually third party displays have a stamp that says okay on them which is something Apple doesn’t do. Also, many repair shops do not have the right replacement cowlings and screws for iPhones. If you see a phone missing those components it usually is a sign to look for more clues to the device being serviced."
],
"score": [
7
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8i2wxn | What is the black magic behind air fryers? | Technology | explainlikeimfive | {
"a_id": [
"dyoifnc",
"dyoigv5"
],
"text": [
"They are just little convection ovens. You can get the same results with a traditional convection oven you just have to wait for it to heat up and you waste a lot of heat. Note: Convection ovens are just regular ovens like you have at home except with a fan inside to help circulate the air.",
"An air frier works by coating your food in a thin layer of oil and the circling hot sir through it causing it to start the chemical reaction and get crispy. In a normal fryer we fully submerge our food in Oil in an air fryer its just a thin coat which means equal crunch, a lot less oil (80-90% less)"
],
"score": [
9,
6
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|
8i337b | Why is the sound / EQ levels on some videos so low, when volume is maxed on the device? | On my laptop, many videos are nearly impossible to hear without an external speaker. However, i know the sound can get much louder, because some music or videos are significantly louder. Sometimes, the video is maxed, my laptop is maxed, but the eq is still barely registering, and the levels are like 5% of max. So why cant i just keep turning up the volume until the EQ is at max? What is telling my computer that this is as loud as it gets, when its clearly capable of getting louder? | Technology | explainlikeimfive | {
"a_id": [
"dyoul8m"
],
"text": [
"Imagine the volume slider as a \"multiplier\" on the original sound source. In a gross oversimplification, let's assume that the slider is a direct multiplier on the sound level, so that max setting is 100% sound--the exact sound level of the original--50% is half the sound of the original, and a zero setting is obviously 0% (no sound). In this scenario, you'll notice that the volume control depends greatly on the sound level in the original audio. If you're playing audio file 1 with sound level 80, and an audio file 2 with sound level 40, file 2 will always be half as loud as file 1, no matter what your sound setting, because the original sound level in each file is just being multiplied by an amount set by the volume slider. (technically, sound levels scale logarithmically, but let's ignore that for now). So now that we've established how the volume slider works, the main part of the question is, *why* is it like that? Clearly, the physical speakers on the laptop are capable of creating larger sounds. However, whenever you play sounds louder than their original value (amplification), you run the risk of distorting them. Have you ever heard a video or sound file which sounded kind of \"boomy\" or \"fuzzy\"? That's typically the result of overwhelming amplification. Since this is generally viewed as undesirable, the computer generally doesn't let you do this, and limits you to playing sound files no louder than the original volume. Depending on your specific computer model and driver software, it might be possible--some systems have max slider at something greater than 100%, but this results in reduced sound quality."
],
"score": [
3
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"text_urls": [
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} | [
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8i499c | The lighting in Childish Gambino's "This Is America" on SNL | Technology | explainlikeimfive | {
"a_id": [
"dyp75y9"
],
"text": [
"I found a good explanation here: URL_0 Sounds like it's a TV-only effect because the TV is capturing about 32 still frames per second. Apparently the live audience would have seen something different. It's similar to how you can see a choppy rotation of propeller blades on TV but in real life it looks smooth. I guess they time the laser patterns to take into account the TV frame rate to simulate those cool patterns we saw."
],
"score": [
4
],
"text_urls": [
[
"https://www.reddit.com/r/lightingdesign/comments/8hfuei/snl_donald_glover_childish_gambino/"
]
]
} | [
"url"
] | [
"url"
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|
8i57tw | why does the radar on big boats spin? | A lot of big boats have some spinning thing at the top. I believe it’s the radar, but why is it spinning? Only seen them on boats. | Technology | explainlikeimfive | {
"a_id": [
"dyoy9nk"
],
"text": [
"A radar not omni-directional. Just like a satellite TV dish it must be pointed in the direction of the signal in order to receive it. So in order for the ship to know what's going on around it it has to point in all directions. It spins 360° and scans all the signals around it."
],
"score": [
5
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"text_urls": [
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} | [
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8i6l2j | In gaming, why does it often take as long to go back to menu screen as to load the actual levels? | This always bugs me, even games with seemingly basic main menu graphics can often take quite long to load. I don't refer to the initial startup of the game, when I assume some general assets may need to be loaded, but when going back from a level to the main menu. | Technology | explainlikeimfive | {
"a_id": [
"dypb8xg",
"dyp9agx",
"dyp9zzx"
],
"text": [
"Depending on the game, it may be saving your progress or doing other tasks to properly *stop* gameplay. These may either be handled before beginning to load the main menu, or simply take up a lot of resources (processing power, disk access) that would otherwise be needed to load the menu.",
"> I don't refer to the initial startup of the game But that is essentially what's happening. When you start the game (load the level, as you put it), all the resources being used are released so that the game engine itself can use them. When you exit the game to go back to the menus, all that stuff has to be reloaded into the device's memory.",
"Memory real estate is a real thing. For something complex like a first person shooter, all the textures that are needed are definitely not insignificant. If you leave the menu loaded while you're in a match, that just lowers the amount of memory you can use per object (meaning you have to use lower detail models), or it increases the minimum requirements of your game, lowering your target audience. By releasing the objects used on the main menu, you are sacrificing the time you need to load them back later in order to maximize memory efficiency while in a match."
],
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3,
3
],
"text_urls": [
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8i8tbj | How do heatseeker missiles work | Technology | explainlikeimfive | {
"a_id": [
"dypu4sj"
],
"text": [
"Heat seekers have an infrared camera at the front that looks for the hottest ~~girls in your area~~ points in front of it and steer the missile towards that direction. in order to steer the missile the fins of the missile have some tabs that act like the rudder and elevator of an airplane. the on board computer of the heat seeker will try to calculate where the target is moving and it will try to adjust accordingly based on movements. that is the reason military aircraft are fitted with flares, the flares create really hot spots that can confuse the computer, older computer models will even lock on the sun."
],
"score": [
31
],
"text_urls": [
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} | [
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|
8icka8 | Why can automatic transmission cars be "bumped" into neutral without pressing the release on the gear shifter? Is it for safety, or something else? | Technology | explainlikeimfive | {
"a_id": [
"dyqr872"
],
"text": [
"The button is a safety feature I believe to prevent you from bumping the shifter into another selection when it would be either dangerous or damaging to the vehicle to do so. You need to push it to go in or out of P for example because you don’t want to accidentally go into P while moving or out of P when parked. When in N the drivetrain is not connected to the engine so you aren’t going to damage the vehicle or be in any danger by going into that accidentally once you’re out of P."
],
"score": [
4
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"text_urls": [
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} | [
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|
8icxvj | Why when installing programs on my PC they can take/reserve more then twice the amount of space then their folder actually is after the installation? | Technology | explainlikeimfive | {
"a_id": [
"dyqsnd4"
],
"text": [
"It's sort of like when you order a toy, and it arrives in a big box full of packing foam panels. You have to open the box, take out the foam, and then you get your toy. Once you have the toy, you can throw out the foam and cardboard box. Many programs are compressed to save space while in a state meant for shipping, aka transfer (downloading, on a disk). When installing, you need to \"unpack\" or decompress the program. Those temporary files, (like the packing foam), are then deleted once the program has been installed. Maybe someone else has a more concise explanation, but that's how i have always thought of it."
],
"score": [
9
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"text_urls": [
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} | [
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|
8id8mw | How does a computer keep time, when not getting it from the internet? | I did a search for this and the answer came back from an askscience post - but I didn't understand. so time is kept on a watch/clock using physical measurements as I understand it - the turn ratio of the cog is carefully measure to move the hands at the correct velocity? but how does a computer do it? | Technology | explainlikeimfive | {
"a_id": [
"dyqtxld",
"dyqub0e",
"dyqzgmf",
"dyqu2o8"
],
"text": [
"There is a small battery on the motherboard which provides just enough power for the clock to keep up. It's called the CMOS",
"> so time is kept on a watch/clock using physical measurements as I understand it - the turn ratio of the cog is carefully measure to move the hands at the correct velocity? This is correct for mechanical clocks and watches. However, most budget clocks/watches now use electronic components to produce an oscillating signal, often regulated by a quartz crystal. This signal can then be used to keep time by counting the number of oscillations - 1 second being a particular number of cycles. Computers use this method, powered by the small battery on the motherboard as mentioned.",
"The computer contains a clock on a chip. There are various ways of doing it. In a quartz clock, for example, if you apply a current to the crystal it vibrates 32768 times per second. Count those, and you can keep time.",
"Instead of mechanical gears, the computer used a quartz crystal. A battery on the motherboard supplies electrical power to this crystal which will vibrate at a very precise frequency. There is a detector which records each vibration and counts upwards, which gives you the time. When you connect to the internet, the counter in your computer is synced to the time server’s counter and after you disconnect the clock in your computer keeps counting away."
],
"score": [
18,
18,
4,
3
],
"text_urls": [
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8idaam | How do news sites get their new articles, which are just minutes old, to the top of search engine results? | Technology | explainlikeimfive | {
"a_id": [
"dyquch1",
"dyrfvea",
"dyr4k9i"
],
"text": [
"They don't get them there, search engines are programmed to find news articles with frequent crawls, and put them there.",
"More popular sites get crawled more often. In the case of breaking news, it's possible that as soon as Google finds out about it, it crawls the major news sites immediately.",
"Search Engine Optimization or SEO. There're entire companies based on the concept of SEO and even ASO (App Store Optimization). As for exactly how it works, the methods are company secrets and even then, *real* ways to optimize for SEO are only known by Google as well."
],
"score": [
7,
3,
3
],
"text_urls": [
[],
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} | [
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|
8ie2mh | How plausible(or implausible) is time-travel? | Technology | explainlikeimfive | {
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"Travelling to the past is completely implausible. Travelling to the future is completely plausible, but completely impractical. It would require you to get into a spaceship and accelerate to close to the speed of light, fly away for many light years, and then fly back. Time dilation would mean that you would have experienced a slower passage of time than everyone back on Earth, so it'll feel like a few days/months to you, buy years would have passed on Earth. Of course, we don't have spaceships that can reach those speeds, and there's no indication that we'll create that kind of technology in the foreseeable future, since there's no way to store enough fuel on a ship to get it up to those kinds of speeds.",
"Well with using time dilation ( in which time runs faster for everyone relative to you) its possible to \"travel\" to the future. Getting to a point where it can be used is hugely difficult As for travelling into the past, im jot aware of any mechanism a 3 dimensional being can do so, but im also no expert so i wouldn't say for sure that you can't. But its much less plausible."
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8iezp5 | how is a phone call traced? | Technology | explainlikeimfive | {
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"It doesn't happen like in the shows or movies. It doesn't take a minimum of 60seconds to trace or they lose it. LE sends the request to the phone companies and they just hand it over.",
"A request is made to the phone company, by law enforcement, and the phone company's routing data is delivered. It's not a matter of fast typing, like on TV, but it's not as useful as you might hope.",
"Your phone is connected to several cell towers at a time. Every now and then your phone and the towers ping eachother. What that means is they send a message (which basically says \"reply immediately\"), and they one back from the other party. They can then measure the time between sending and receiving the messages to determine how far away your phone is from the tower. When your phone is connected to several towers, the phone company can do some maths to figure where your phone is, based on how far away it is from the different towers, and knowing where those towers are located."
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8if1wx | How Football Manager pc-games simulates matches and results | I can't find out how Football Manager video games simulate matches. I'd love to know how the simulations happens, what heuretics are used and anything else you might know. Edit: Please let me know if this is better suited in maths or engineering . | Technology | explainlikeimfive | {
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"Computers can do wonders when it comes to math. You probably already know about how programming works, judging by your edit, so Ill skip a bit. As you can guess, the exact algorithm of how this particular game works is unknown, but it all comes down to list of formulas, variables and all kinds of mathematical stuff. While Im not familiar with this game in particular, its almost all the same in all other games. Lets imagine a random simple game where you hero attacks an enemy, with a chance of missing. To determine if hero hits its target or not, game uses a simple formula \"Attack success chance = Hero accuracy minus Enemy Dodge.\" If hero attack is higher than dodge of an enemy - then their attack will hit, and vice versa. And now, imagine that this formula gets complicated, really complicated. It uses very complicated algorithms and tons of variables to accurately determine needed result. And such games as simulators will use a tons of such complicated formulas, using their results to determine the outcome of particular situations. Like \"will the soccer ball hit player number 2 or not.\" Game will use this data to simulate a real soccer match depending on the results of the calculations. This is my first ELI5 answer, I hope I was informative."
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8ifeqr | Why was/is there a need of the hexadecimal system in programming? | I understand the need of the binary system. The Computer can only understand 1s and 0s but we want to use other numbers, too. So we invented a system to convert the two back and forth. Any Number can be represented in binary. So why was there a need for hexadecimal? What can the hexadecimal system do that binary cannot? Is it still used today other than in color codes? | Technology | explainlikeimfive | {
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"Binary numbers get very long quickly making it hard for people to deal with. Converting the binary to decimal is a bit of a pain but converting to hex is easy. Each 4 bits of a binary number converts to one hex digit. This makes the numbers easy to convert and easy for people to remember.",
"Hexadecimal allows you to represent a large chunk of binary numbers with a single character. If you want to represent the numbers 0 through 15 in binary, you need 4 digits (0000 = 0 - > 1111 = 15). If you want to represent the same thing in hexidecimal, you just need one character between 0 and F (0 = 0, A = 10, F = 15). The reason why you use hexidecimal instead of just converting into Base 10 is so that you can quickly convert between it and binary. If you want to represent the number 11010110 in Base 10, you need to do all the fancy conversion. However, if you want to represent it in hexidecimal, you know that the section 0110 is 6, and 1101 = C, so you have 0xC6 (the 0x is prepended to denote that you are using Hexidecimal for the occasions that there are no A-F characters in the result).",
"Computer engineer here, Hexadecimal is a very, very easy way to organise binary strings. A single hexadecimal character has 16 possible symbols (0-0,A-F); this is precisely the same number of symbols as 4 bits. Ergo, a string of 4 bits can be reduced to a single hexadecimal character. This makes it much easier to read. 0 = 0000 1 = 0001 2 = 0010 3 = 0011 4 = 0100 5 = 0101 6 = 0110 7 = 0111 8 = 1000 9 = 1001 A = 1010 B = 1011 C = 1100 D = 1101 E = 1110 F = 1111 The hex string 4E5F = 0100 1110 0101 1111. This can be verified simply by looking at the substitutions above. What is the decimal number 4673 in binary? Go ahead, take your time. Hexadecimal is heavily used in real programming (I'm talking assembly and C motherfucker, not that lazy interpreted shit) because it makes it very easy to visualise the flow of memory and manipulating of data. For example, some particularly fast arithmetic operations require memory to be aligned on 16 byte boundaries; This can easily be determined by looking at the last character of memory address of the data in question; if it ends in a 0, it is aligned on a 16 byte boundary. If it ends on anything else, it is not aligned. 0000, 0010, 0020, 0030, 0040, 0050, 0060, 0070, 0080, 0090, 00A0, 00B0, 00C0, 00D0, 00E0, 00F0, 0100, etc... Now try doing that with decimal 0000, 0016, 0032, 0048, 0064, 0080, 0096, 0112, 0128, 0144, 0160, 0176, 0192, 0208, 0224, 0240, 0256 Is the address 476402 16 byte aligned? You tell me I can tell that the hexadecimal string 6E2B will fit in a 16 bit register simply by looking at it. The decimal number 68,235 will fit in a 5 decade register, but those haven't been used in... decades :D. Will it fit in a 16 bit register? You tell me."
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8ig56n | How did ancient people discover how to refine stuff such as grapes into wine or cooking made food taste better? | Technology | explainlikeimfive | {
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"Food was rare back in the days which meant that throwing it away could have terrible consequences as long as it was still somewhat edible. Cooking possibly couldve happened by someone accidentally dropping food into a fire and because they wouldnt want to throw it away they ate it. Wine was probably similsr by forgetting about some grapes and they started fermenting. A lot of things happened most likely by accident because food was scarce and hard to come by...",
"I always wondered about cooking, and the best theory I've heard so far is it came about from people walking through the ashes of forest fires and picking up the animals they found teaching them \"hey this tastes better and we get sick less often. Maybe we should be putting meat in fire\"",
"Cooking is something that may have caused humans to evolve differently from other animals. We are tens of thousands of years removed from our primative ancestors. While this may seem like a long time nowadays based on technology progress, it is actually a very short time scale for evolution to happen. Therefore, our bodies have not changed much from our ancient ancestors. Our bodies are not well-designed for raw foods. In contrast to other animals, humans have very small jaws compared to head size. We cannot chew as much as other plant eating animals. Many plant eating animals spend a great deal of their day chewing up their food to aid in digesting it. Since humans are omnivores, we also eat meat. But our small jaws doesnt allow for large muscles to tear and rip apart raw meat. Have you ever tried to eat too-raw meat? It ends up extremely fiber-y and tough to chew. So how have we managed to survive while still powering our extremely energy-draining large brains? Cooking. Cooking breaks down food so that it is easier to eat. Easier to eat means less time spent eating and more calories that can be digested from the meal. It's not that humans discovered cooking but cooking is what allowed us to evolve into humans. Therefore it is hard to pinpoint how exactly we discovered how to cook. Fermentation is a form of cooking but using bacteria, yeast, and/or mold to break down foods before we eat it. Fermentation was necessary because there really wasn't many ways to store food, especially in regions where food rots easily. Fermenting foods use a \"good\" edible rot that prevents \"bad\" or poisonous rot from living on the food. This way, fermented food can keep longer and we also get the benefit that it is partially digested (more nutritious) and free from poisonous rot. How did we discover it? Foods pick up the spores of these microbes from the air. Sometimes we are lucky to have good rot taking over the food. Someone may have decided to try older stored food only to realize it was edible and may have tasted better.",
"That’s not nearly as weird as how humans figured out how to eat cassava root. Cassava contains cyanide. If you don’t peel it and process it in a particular way then it will kill you.",
"I've heard for asian cuisine, a lot of the \"unusual\" stuff was discovered by Daoists?/Taoists?. In search of food that will extend their lives/immortality - they apparently tried everything edible and not edible. For example, in the days before deep understanding of chemistry and proteins, how did anyone figure that mixing salt with soy beans and wheat and letting it ferment for a few weeks - then eating the resulting smelly product (soy paste/soy sauce) would actually taste good/not kill you?",
"The one that really blows my mind is Aloe Vera. Who was the brave person who got a really bad sunburn and thought \"You know what would feel good on this burn? If I took that tough, prickly plant and rubbed it all over me!\" ??",
"> Did they really just taste test and if they died they died? It was more like, \"I'm starving to death, it can't hurt to give this a try.\" Food was often scarce, hunger and starvation lurked around every corner. Caution would give way to desperation, kind of a trial and error at gunpoint. Also, this happened over thousands of very, plenty of time for all sorts of happy accident. I saved up a bunch of grapes for later, whoops, looks like they went bad, hey, we can still eat them and wow! I'm just going to set my chunk of raw meat here by the fire, whoops, it is all burn now, but hey, it tastes even better, has fewer parasites, and won't go bad as quickly.",
"With something like wine (or anything which involves a multistep process) this would likely have happened gradually, in stages, with each stage being possibly discovered by accident, or after a period of deliberate trial and error, and refined over time. So eg you collect grapes when they are in season and store them in a container. The bottom of that container will get filled with grape juice. Which might start to naturally ferment. You might notice that this tastes good, and has pleasant effects, if it's left for a certain length of time, but turns sour (or worse) if you leave it too long. So people start deliberately making it by leaving the juice for the right length of time. Then it might be noticed that if it's made in a certain type of container it tastes better than in another. Or if it's made in a cool cave it tastes better (or worse) than if made out in the open. Or you get a different flavour if you pick the grapes sooner rather than later. And so on and so on, with lots of different variations competing with each other in a kind of Darwinian process.",
"Not every discovery had to come from random dumb luck. Ancient people had the same compactly to reason as we do today and they could think things through and experiment intelligencetly.",
"waste not want not.. unused food, stored food. grapes in a barrel the magical liquid on the bottom made your tummy warm. left over porridge baked to dry it turned into a flat bread",
"The real ELI5 is they didn't waste their time watching TV or playing video games or browsing the internet. Our ancestors couldn't just go to 7-11 and get a 6 pack. Therefore, they spent a lot of time thinking about ways to improve their lives."
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8ihcm3 | How does the cell phone emergency alert work (in Canada)? | We recently had a test of the emergency alert system. Many people got it, many people didn't. How hard can it be? | Technology | explainlikeimfive | {
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"The phone system is based on one to one communication. When you dial a phone number a circuit is opened between you and one other person. Over the years this has gotten a little bit more complicated, you can have three or four people on a single circuit. BUT, the phone system was never designed for broadcast. That is, sending a single message to *everyone*. This is why historically Canada has used radio and broadcast TV to distribute these alerts, because these are broadcast mediums. Sending these alerts over the phone would require calling everyone one by one. SMS text message is not much better. It would be a lot faster, but it would require that the one message be sent out for every single person who needs to receive it. The emergency alert system that is being rolled out now is a new technology, and it's a technology that needs to be supported both at the network level and on the phone. That means its possible that some geographical regions do not receive the alerts because they are not serviced by new enough networks (**I don't have any knowledge that this is the case anywhere in Canada right now, I certainly hope not but it's a possibility***). Other people will have the message delivered by the network, but their phone won't do anything because the phone doesn't know what to do with it (like sending a photo to someone who can't receive MMS, they might just get nothing). These aren't the problems the test is trying to solve. It's easy to figure out before the test which cell towers are too old, and the government of canada isn't in the business of buying people new cell phones. On a larger scale, it's possible for network failures to cause some areas, even areas as large as all of Quebec to not get the alerts, and this is exactly the reason these tests are run. It's just an incredibly hard task to tell every single person in the country the same thing at the same time. I don't have any information about what happened in Quebec, but these types of problems can be caused by the simplest of typos that go unnoticed. The alert is dispatched from one location and has to reach *everyone* and the alert passes through so many different computers along the way that it's amazing when a test of this scale actually works right the first time."
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