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aeoob9 | How does comparable gpu's have completely different power needs? | I don't know if it's the right subreddit, but I wanna ask: how does nvidia geforce gt 1030 need 30W, and gtx 560 needs 150W, while they have basically the same performance? (In benchmarks gt1030 has 140th place, while gtx560 has 141th) | Technology | explainlikeimfive | {
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"More modern manufacturing process, using smaller transistors that leak less heat during operation, and improvements to the arrangement of those transistors that results in a more efficient architecture."
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aepuae | Why does 30fps look and feel so much worse on pc than it does on consoles like the ps4? | Technology | explainlikeimfive | {
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"Cap a PC game to 30 FPS and you will find it feels better than the same PC game that has a constantly fluctuating FPS between 30 and 60. When the frame rate fluctuates the amount of time it takes for each frame to draw varies from one frame to another. This is much more difficult to get used to than dealing with a lower but consistent frame rate Not all game have a frame cap. You can use Riva Tuner to set a custom FPS cap, you can get it with MSI Afterburner. MSI hardware is not required.",
"If a PC game is running at 30FPS, it is likely struggling to keep up with the demands of the current graphic settings and thus it's less an issue of frame rate and more an issue of frame rate consistency. Additionally, if you're at such a low frame rate you may be for example, turning off V-Sync (which ensures entire frames are \"written\" to the screen all at once versus line by line) as it is computationally expensive. Console hardware is locked-in, and thus developers make their games for a very specific set of hardware. There's billions of combinations of PC parts, so developers make their games with more agressive demands typically which means a low end computer will struggle and a higher end computer will likely be able to maintain a higher frame rate with better settings."
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aern8g | How do people get away with filming pranks without their consent? | Movies like Borat and shows like The Eric Andre Show always make me laugh due to the raw reactions of the people they end up pranking. How is it that they get away with pulling off these stunts? Do they go through the pain of making every single person sign a film consent waiver, or do they continue to do it in secret? | Technology | explainlikeimfive | {
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"a common variation of your question is why doesn't snoop or the people on drugs inc get arrested. What you see on tv or on some youtube video is not always real. URL_0 If it's shown on TV, everyone there is a aware that they are on a show, and have signed waivers. They might not be fully aware of what their role on the show might be, and that's part of the \"surprise\" plus of course acting. So they could be told \"walk down this street, ring the doorbell on the 5th house\" when really somoene is hiding in the bushes at 3rd house to scare them.",
"For a show like Impractical Jokers, they film a lot more stuff that doesn't make it into an episode because the people involved don't sign the waivers afterwards. That is just part of the process. Not everyone will agree to have their face shown on TV.",
"In most states, it is legal to film people in public places, though my understanding is that you generally need to get their permission to use it for business purposes. So you just film them, then offer to pay then to let you use it in your show if it was entertaining."
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aes1vu | Why can't cell phone batteries be charged by kinetic energy (like the Seiko kinetic watches from several years ago)? | Technology | explainlikeimfive | {
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"It is just way too much energy needed. That Seiko watch uses about 0.9 microwatts and a modern smart phone consumes about 2.5 watts. That is like 2.7 million times more energy, it isn't even close.",
"Watch need little energy. Cell phone need big energy. 3,000 mA is a hell of a lot of movement.",
"Two words: power consumption. Regular watches consume so little power that kinetic or solar chargers actually make very little sense, it's more like a technology demonstration than an actual feature. A quartz watch can last 8-10 years on a single non-rechargeable battery, while a rechargeable battery degrades much faster than that. Smart watches, otoh, eat batteries for breakfast, a kinetic or solar charger won't be able to sustain their appetites. Perhaps kinetic or solar chargers could work for 'moderately' smart watches like Pebble or older b & w Suunto Ambits."
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aes37j | How do different types of brain scans work and what is the difference between them? | EEGs are pretty straight forward but what purpose do MEGs, CT scans, CAT scans, MRIs, and PET scans serve, how does each imaging machine work, and what is the difference between them? | Technology | explainlikeimfive | {
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"MEG scans work by mapping the magnetic fields produced by the electrical currents in the brain. It can measure brain activity in specific regions in real time. CT and CAT scans are the same thing, CT scan is just the more modern, commonly used term. This machine uses x-rays just like a regular x-ray machine but it takes them in \"slices\" to produce a 3d image of the body part in question (not just the brain). MRIs use powerful magnets and radio waves to make 3d images of the body (again, not just the brain). A powerful magnet aligns all the water molecules in your body in the same direction. Radio pulses disturb the alignment, and detectors measure the rate at which the molecules revert to the aligned state. Different tissues have different amounts of water so they align at different rates, and this translates into images. a PET scan works by injecting the patient with a small amount of a radioactive tracer chemical. When radioactive things break down (decay into lighter elements) they emit positrons. When positrons hit a electron (it's negative) they annihilate and give off some gamma rays. The PET scanner can detect these rays and form an image."
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aes6b2 | In videogames, why is it so difficult to program objects to not go through other objects? | For instance, characters going through the landscape, capes and other articles of clothing going through the character, etc. | Technology | explainlikeimfive | {
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"It is a huge amount of math to calculate the actual shape of objects down to the polygons of their models. Instead game engines \"cheat\" by only calculating a simplistic model of the objects, where a character for example will have a single origin point and a \"collision box\" around it to prevent passing through walls or other obstacles. That way math can be done on a simple square or circle rather than hundreds of thousands of polygons defining a constantly changing 3D region of space.",
"Basically, shapes are complex, and too much maths. Easy solution? Cubes/squares and spheres/circles.",
"It's not that it's difficult to program it's that you computer is putting a lot of effort into trying to simulate reality in games. So game designers have to fudge and fake a lot of things. Clothing, grass, trash, and other things that might blow in the wind or be part of scenery, are just pictures or simple models that have no code given to them for collisions with other objects because if they all did your CPU would be overwhelmed. As for your character falling through the ground, that's usually the case of a rounding error in the code, games are complex and not everything runs perfect all the time.",
"Computers store information about objects as a series of points in space, usually corresponding to triangles. So I give you the coordinates for the three points that correspond to the corners of a triangle. Then I given you a random point and ask you if that point is *inside* the triangle. Now, you'd probably draw the triangle and the point and just \"see\" whether it is inside or not. But computers have no perception or conception of this. They just have raw data. If you weren't allowed to draw the triangle, how would you, based only on the coordinates of those four points, answer the question? It's a bit trickier than it looks because you have to mathematically define what it means to be \"inside\" a shape. And once you've figured this out, you've answered the simplest scenario: a single point inside the simplest of 2D polygons. But objects in computer programs consist of thousands, if not millions of these 2D polygons all oriented differently in 3D space and all of a sudden you're checking millions of points. This is next to impossible to do in real-time, so instead you take a complex shape and given it what is called a bounding box. A simpler 3D shape (such as a cube or cylinder) and then you treat that simpler shape as the physical boundary of your object. If you're \"inside\" that shape, the program treats you as being \"inside\" the bound object. This saves time on processing but sometimes results in odd kinds of collisions in the game. It's a deliberate trade-off.",
"the short answer is - computers have trouble with fractions. the more correct answer is - collision logic becomes complicated if you have realistic physics (acceleration and inertia) and are limited by how often you can calculate new positions. basic collision detection is actually not that difficult - just make sure that the set of data representing one object doesn't reach values that would let it intersect with another object. picture a number line. say there is a wall at 9 and a car at 2. the code for collision detection is essentially this: \"when you press a button, move the car forward by 1 number unless that number is greater than 8.\" pretty simple if you finished primary school. problems start to arise when you use fractions like the number 4/3. computers only store approximations of numbers like 1.3333....(repeating). the more you use approximations the less accurate your results are. also the logic of collision becomes more difficult with acceleration. what if the car is actually a rocket that has a velocity of 5 when you press a button? in the previous example with the wall at 9 you would move the rocket to the number 7, then in the next frame to the number 12. hold on! that's too far! okay so don't move it if the number is greater that 8. but then the rocket is stuck at the number 7 and would appear to stop before the wall. that doesn't look right either. ok so have the rocket move only as far as the distance to the wall if the number is greater than the wall. Now expand that logic to 3 dimensions. now expand that logic to complex shapes. now add multiple sources of acceleration and rotation. add in the fact that computers use a different number system than humans and its starting to get very complicated very fast. not to mention that even though we got the rocket to stop at the right place, it occured \"in between frames\" which is another whole problem. now say that rocket is actually a bouncing ball that bounces off the wall. you can't have it move 2 steps and then bounce in the next frame and move 5 steps again. that would look weird, like it is slowing down and speeding up in mid air. also remember that not all programmers are math geniuses. (Edit - And I don't mean I am a math genius, I still struggle with calculus.)"
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aeupeg | How does DDOSing work? | Technology | explainlikeimfive | {
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"Think of the internet like the roads going everywhere. On a normal day traffic. Moves fine and people to to places on time and without issue. Now think of getting thousands or millions of people to all visit the local coffee shop at the same time.... Your going to get a traffic jam, and the coffee shop is going to struggle to get anything done trying to deal with everyone at once.",
"It's a distributed denial of service attack, so it helps to know what a denial of service attack is. A denial of service attack is when a particular web server gets spammed with requests so it takes up the entire load that the server can take on (so service gets denied to legit consumers). A *distributed* denial of service attack is when that attack comes from a distributed location, as opposed to one location. Two major advantages to this. 1. Each computer uses less of it's energy to contribute to the attack, so harder to detect. 2. Attacks can be MUCH more severe because there's more computing power than just one computer behind them. How do these distributed attack locations work? Attackers will infect millions of computers with code that will execute the attack. Well, a tiny portion of the whole attack so each computer doesn't detect it. Your computer is probably a member of one of these *botnets*."
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aeuvwz | How do phone systems experiencing mass calls at once (such as on radio shows) select calls to connect through? | Technology | explainlikeimfive | {
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"It is usually the first call that reaches the phone switch which gets routed through. However some systems allow calls to get priority in certain conditions. This all depends on the configuration. If there are multiple phone lines then there may be multiple people routed through, one on each line. Different phone switches have different configurations as to which line gets which call. And the people answering will also be able to randomize which lines they pick up. So it is very hard to know which calls connect through. There might be some tricks to help you get through more often however this require intimate knowledge of how the phone switches is configured.",
"I manage the pbx system for my company. It depends really. Some systems may ring all phones in certain group (I.e. Ring all in office x if office x chosen). In the case of radio shows where it should be first in first served but they want to get through to next people you would have a queue. It's just like a queue in real life and when someone is available to answer the next oldest caller is selected and answered. You can also have much more complex systems where during high call volumes it will route to different groups and queues or even tell the caller to hang up and they will be called automatically when someone is available."
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aevb5o | How do fuel pumps automatically stop filling up gas when filling up? | Technology | explainlikeimfive | {
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"Found on google.... & #x200B; Near the tip of the nozzle is a small hole, and a small pipe leads back from the hole into the handle. Suction is applied to this pipe using a **venturi**. When the tank is not full, air is being drawn through the hole by the vacuum, and the air flows easily. When [gasoline]( URL_0 ) in the tank rises high enough to block the hole, a mechanical linkage in the handle senses the change in suction and flips the nozzle off.",
"There is a second tube that is sucking out the fumes as they come up the inlet pipe. There is a membrane inside the handle, underneath the round cap with the logo on it. This membrane when pulled up stops the fuel supply. When the tank is filled up, it can’t pull the fuel vapours anymore so instead it pulls on the membrane which cuts off the fuel supply. Edit: as mentioned in the comments below. It’s any gas, not just fuel vapours so air is included.",
"What I want to know, is how much reserve gas is left when I get down to empty. Specially on this car I now own that has a computer that gives me an estimated range. Online specs say the tank is 12.39 gallons. But even when I got to zero and drove another while, when I finally got gas, it only lets me put in a little over 11 gallons. So is there always a gallon of reserve?",
"LPT--you should not keep goosing the gas nozzle in an effort to fill the tank to the brim. Fill the tank until it clicks off, then either stop there, or fill again one time only. There is an activated charcoal filter near the top of the tank's filler neck, and if you keep pumping long enough the filter can get soaked with fuel. This can cause problems with the car's computer, fuel control system, etc., and throw a code at you.",
"So the pump nozzle you put in the fuel tank when your filling up is in actual fact, two nozzles. Underneath the main large one which the fuel comes out of is a second very small nozzle. However that one is sucking in air as you pump. The reason for this second small nozzle is twofold. Firstly it lets the pump know when the tank is full and to stop the fuel flow so fuel does not flow out your tank causing a spillage everywhere and potentially a serious accident. It does this by sucking in air and fumes from inside the tank as you pump. However as soon as this suction gets cut off by coming into contact with the fuel, the pump knows to immediately cut the fuel flow. Think of it like sucking air through a straw and slowly dipping the other end of the straw into some water. As soon as you do so you will need to apply a lot more suction to get the liquid to travel up the straw. This is what the pump detects which tells it to turn the fuel flow off. The second reason for this suction nozzle is also to capture fumes. Pumping such high amounts of fuel would normally involve really high amounts of hazardous fumes which are really quite combustible! However because this suction nozzle is sucking them up, it's not so bad. These fumes are actually quite bad for the environment as well, so rather than just vent them to the atmosphere, they are stored in the empty space of the fuel tank that feeds all the pumps for the service station. When a fuel truck comes to refill the service stations tanks, it takes the fumes away where they are processed into usable fuel again (They used to just be burnt but the days of that have come to an end in a lot of countries).",
"Gas pump jock here. In the olden days the flow of gas onto the nozzle tripped a mechanical lever, stopping the flow, often resulting in spillage of gas on the side of the car and onto the ground. Normal procedure in 'Full Service' mode was to wipe the side of the car with a wet towel to preserve the paint. Many cars developed a permanent stain below the gas cap. Many owners used to pump their own gas and listen for the sound of gas welling up to shut off the flow before it spilled over. Those were days of yar , surprised I survived them without being burned alive.",
"And why does the pump always stop mine before my car is full? Is this a computer/reading error in my car?",
"Er... and why this does not happen with the Citroën 2CV?"
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aew1y0 | Can a company disassemble commercial products to "get ideas" for their own? Assuming no, how then do new technology companies get started if they have to re-invent everything? Why do "innovations" (touch screens, for example) seem to appear everywhere at roughly the same time? | Technology | explainlikeimfive | {
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"If something is patented, the people patenting the object has to explain how it works, so all you'd need to do is read the patent to figure out how it works, you don't have to disassemble it. As long as the product isn't illegally similar to a patented product, you can do basically whatever you want to do.",
"Of course you can take things apart. It's often easier to just read the patent filing. If you see an idea you like, you may not be able to use it if there are patent protections. The reason an innovation appears in many products at the same time is that a supplier invented it. They make a better, battery let's say, and sell it to many companies that make many gadgets. To consumers, it seems like a bunch of gadgets got better battery performance all at once, but it's really because they buy from the same supplier. Almost nobody makes all the parts of their gadget, that would be much too expensive.",
"I used to work for a major automotive company. We would acquire a competitor vehicle, put the suspension on a rig that measured the motion of the suspension throughout its range of motion. Then we measured all the pivot points, and disassembled it and measured things like bushing and shock absorber stiffness. We also had other people who could take apart any subsystem and put it on a big board. Anything that could be copied to improve our products was."
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aew5s9 | How does silicon turn into a CPU that can calculate things? | Technology | explainlikeimfive | {
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"That silicon (along with some other stuff) is shaped into transistors. Transistors are essentially switches with no moving parts that run entirely on electricity. By organizing switches in complicated patterns you can construct engines capable of handling logical statements and doing arithmetic. You can google things like [logic gates]( URL_0 ) and [adders]( URL_1 ) to see (relatively) simple examples of this. You could theoretically accomplish the same things with comparatively giant mechanical switches (in fact, this is how some of the very earliest computers worked)."
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aewacg | How can most cell carriers all claim to have "The most reliable 4G network"? | Technology | explainlikeimfive | {
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"“Reliable” could also mean different things. Maybe it means coverage area, or speed, or it rarely has issues. That’s why they pick a vague term.",
"Because they all have different sources for their data. If you watch television commercials, you'll note that there's generally some text at the bottom of the screen when they make that claim. \"For September-October 2018 in tests by (whomever) in (whatever regions).\"",
"By picking the right stat to call \"reliability.\" Does reliability mean having enough signal to make a call in the most places most people spend their time? Does reliability mean having the fewest dropped calls while in a coverage area? Does reliability mean having a functional data connection in the largest physical area? And so forth. It's kind of like claiming a network has \"99% the coverage of [competitor]\" - measured how? By land area or by population?"
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aex4p7 | on the fundamental level, how is the passage of time programmed in to a computer? | Without a mechanical spring as is used in an wind-up clock how does a collection of on-off switches know how long a second is? | Technology | explainlikeimfive | {
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"There's basically a miniature Quartz clock in the computer that still runs while the computer is powered down via a battery, and then when you connect to the internet it'll use the internet to sync its clock unless you've turned that off."
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aeyc2l | how a pedometer/step counter works? | I had one as a kid and assume it added 1 step every time it felt the jolt of the step. Now I have a Fitbit, I can’t imagine this is still true. Bonus: if you know how a Fitbit works, eli5 please, how does a green light know my heart rate, how many steps etc etc Bonus Bonus: I’m now even wondering how the scales (Fitbit again, but honestly this is not an ad!) know my body fat %! | Technology | explainlikeimfive | {
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"In the old days, pedometers had a little ball that bounced up and down with each step. Nowadays they use piezo-electric crystals. Those are crystals that have a tiny electric charge when they are under stress. As you move, the stress changes, and that change can be detected in the charge. Fitbit themselves have a lot of information in their [help articles]( URL_0 ): the LED reflects on your arm. When your heart beats, the surface of your arm changes a little, and changes the reflection of the LED. That again is detected. Finally, most scales that measure body fat % send an electromagnetic (EM) wave from one foot to the other. Since the EM wave travels at different speeds through fat, muscle and bone, they can roughly estimate your body composition by the time it takes for the signal to travel through your body. In itself it's not very accurate, but it's useful to see the improvement."
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aeyqf5 | High impedance headphones | Please can someone explain to me why a high impedance headphone is good, but you don't seem to see 300 ohm speakers? | Technology | explainlikeimfive | {
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"High impedance in headphones or speakers is neither good nor bad. It's just that there are various ways to make headphones, and some result in a higher impedance than others. Headphone impedance does have implications for the circuitry they connect to. In the pre WWII era, magnetic headphones with 2000 ohm impedance were the most common. The impedance level was perfect for interfacing to vacuum tubes without requiring an output transformer. Loudspeakers, too, were usually 2000 ohms in the early days of radio. Solid state electronics tend to operate at lower voltage than vacuum tubes, which implies lower impedance. By the same reasoning as above, low impedance headphones and speakers interface directly to solid state amps without an output transformer. As MrRonObvious points out, there's an additional concern when driving headphones with power amps intended to drive loudspeakers. Headphones, going right on your ear, need to generate less acoustic power than a loudspeaker filling a room with sound. Using a higher impedance headphone on a powerful amp limits the power, so you don't overdrive the headphones."
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af0l07 | Why do batteries die faster in the cold? | Technology | explainlikeimfive | {
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"They don't die faster in the cold, they last longer. But the chemical reaction that generates the electricity can slow down in the cold which can cause your electrinics to shut down from low power. Once the batteries warm up though they will work again."
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af14fz | Extracting metals in the ancient civilsation | I was wondering how the people could, in the era of the ancient civilisation, extract metals like steel, gold and silver? And they could distinguish the different types of metals they were extracting? I mean what were the signs they were looking at when they wanted to dig it from the ground? | Technology | explainlikeimfive | {
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"They looked for shiny things at first, native gold and copper are both pretty shiny. Eventually people learned that green rocks sometimes have copper in them. Then they got lucky and found a deposit of copper with some tin mixed in and invented bronze, or a copper and zinc deposit and invented brass. Lead ore is very heavy and very shiny. Iron ore looks kinda rusty. Silver and Gold ore are also very shiny. Before geology was formally defined it was mostly trial and error."
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af3cgi | Why does 5ghz Wi-Fi penetrate less than 2.4ghz? | Not sure if penetrate is the right word. Basically high frequency electromagnetic waves penetrate more than low frequencies. You can see this with how x-ray machines work ( high frequency x-rays travel through flesh that visible light bounces of). But on the other hand 5ghz wifi has more problems with obstructions than 2.4ghz. So which is it? Does higher or lower frequency penetrate more? Or is there some lowest penetrating frequency? | Technology | explainlikeimfive | {
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"There are two different factors at play here. Both are very important and could easily be compared to am\\fm radio. It's about wavelength. In the case of 2.4 vs 5 gig Hz it's more than twice the wavelength difference. How does wavelength impact the way the energy travels? 1 the lower the wavelength the farther the energy will travel (so 2.4 gig is better there) 2 the higher the wavelength the less interruptions it will encounter as it moves thru objects (walls Windows doors clouds etc) (so 5 gig is \"slightly\" better there) The biggest improvement is the increase in bandwidth by it is offset by slightly shorter range. But both are up in the gig spectrum meaning they are not going to travel very very far unless you have a really powerful amplifier connected to your wireless router. (Which would be very dangerous for other reasons)",
"Hi. Your question is *« why do 5ghz wifi penetrate less than 2.4ghz? »*. We cannot answer this question without wondering about the material it should penetrate. In a perfect void, an electromagnetic waves (let's say photons) goes as far as it wants to. With visible light (\"one frequency range\"), for example, walls are not penetrated but glass is: it's not only a property of the wave, but also a property of the material it goes through. So when you say *« high frequency waves penetrate more than low frequencies »*, that's false in general: it depends on what is penetrated (glass, wall, human flesh). So why do 5GHz has more problem with obstructions than 2.4GHz ? Well, it's just 5GHz waves interact more with a specific set of materials that happen to be the one we construct our houses with: [This document]( URL_1 ), for example, gives the following chart of the coefficient of \"penetration\": URL_0 Why is it the case? It's because of [**Skin Effect**]( URL_2 ): it's the effect that tells how deep electromagnetic waves can penetrate one material. It decreases with increasing frequency."
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"https://imgur.com/a/j7NFqUS",
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"https://en.wikipedia.org/wiki/Skin_effect"
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af5be5 | Why is it that a screenshot in a game is so easy to take but rendering the same image in a 3d software like blender takes so long? | For example, in the witcher 3 you can easily take a screenshot. Recreate the entire scene in blender, and suddenly it takes so much power to process. What kind of optimization do games use to do this? | Technology | explainlikeimfive | {
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"Games use a completely different technique than programs such as Blender to create 3D graphics. Games have to run significantly faster to provide fluid motion and so use many tricks to essentially \"fake\" many effects that make a scene seem realistic. They do this through rasterization, the process of transforming triangles into screen coordinates and using \"shaders\" to calculate the colour of each pixel. As you only see one triangle at a time, things such as lighting have to be manually simulated. Blender (and other 3D modelling software) instead prioritise complete accuracy and so as a trade-off take significantly longer for the small increase in realism. They use ray tracing, where for each pixel a ray of light is sent out from the virtual camera. Each time it intersects the geometry the final colour is updated. Since this is a much more realistic model of how vision works in the real world, things like shadows and reflections are an automatic by-product.",
"Building a sculpture takes a lot of work, let alone making it move and respond to commands. Taking a picture of it is as simple as clicking a button. Screenshots save the state of the game the moment you pressed it and turns it into an image that consists of pixels rather than 3d models, same as capturing moments with a camera."
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af5o5l | Are file read & write permissions actually secure? Can't anyone just create a livecd that just "forces" writing to a certain file in the main drive? (for example, the file that contains the root password [or the hash of the password]) | Technology | explainlikeimfive | {
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"Security ends when attacker has physical access to the device, more or less. In many cases however, attacker lacks this access. Say, you download a virus that tries to do stuff. Or maybe you connect to a remote server and try to mess the server up. In either case, attacker has to ask operating system for all disk writes, and OS, assuming there are no security flaws, will enforce those permissions. But yeah, if you give your server to an attacker, the can just do whatever. There's a slight caveat in that cryptography can be used to protect the system, but for the server to be able to run at all, someone at some point has to enter that encryption key into the server, and thus attacker can get it if they can start the server at all. If the server never runs, then it can be protected even if attacker has access to it, but computer that's never used is pretty much indistinguishable from a rock anyway.",
"No they are not, there only as good as physical security of the machine. For example with access to the harddisk I can replace the .exe that runs the \"login page\" on windows and replace it with cmd.exe and i would be in a above admin permission account and could access everything or worse acces encrypted keys for folders that are protected. & #x200B; This is why on secure servers one common thing is to have a USB disk that holds a decryption key, that is required only for boot. Then the USB disk is secured offsite. If the server is rebooted or someone steals the disks they have nothing but gibberish without that key so booting a live cd will get you nothing the os wont even boot. & #x200B; Be it encrypted harddisk, locked the pc in a safe (see datacenter) or just disabling all non essential interfaces, it boils down to physical and who you trust with it. For more info, go look up kevin mitnick's books on his early exploits most involving physical security failures from very large companys. [ URL_0 ]( URL_0 )"
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af7ufz | how can smartphones manipulate every single pixel on the screen through a thin ribbon cable with a few electricaö connections? | Technology | explainlikeimfive | {
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"There isn't a single wire for every pixel on the screen. The graphics system will send information about what is on screen in small batches and the display processor takes this and controls what's actually on screen. To greatly simplify the process, the graphics system may only send a single pixel at a time but it sends one million of these per frame that needs to be drawn. The information is sent left to right, top to bottom. If you have a really fast camera you can actually watch the screen change, pixel by pixel.",
"ELI5: The ribbon cable does not directly control the pixels on the screen. ELI5+:The ribbon cable transmits data frame by frame, one bit/byte of data at a time depending on whether it is parallel or serial, which are stored in memory on a display driver chip. This chip does nothing but read frames of data from the memory, and uses some fancy electronics to display it to the screen. Beyond the ELI5, here is an incredibly simple version of a display driver chip that displays data to an 8x8 screen: URL_1 And an image showing it hooked up: URL_0 The port labeled MOSI in the white box is where the data comes from the processor. The display driver chip (labeled MAX7219) then displays it to the screen, so the processor doesn't have to do all the work.",
"I haven't seen a good accurate reply on here. Screens don't update every pixel all at once, they will scan through each line of pixels from top to bottom like an old tube television. They do this through a process called multiplexing. Since you need 2 wires to complete an electric circuit, a voltage and a ground, you are able to disconnect either one to turn off the pixel. Multiplexing is the process of manipulating the ground connections to select a row of pixels to be updated. To give an example of the multiplexing process let's use a 5x5 grid of pixels, each pixel can either be on or off. First you will need to split this grid into rows and columns. You will make have five horizontal rows, each one having 5 pixels. And 5 vertical columns, each one also containing 5 pixels. Next you connect all of the pixels in a row to a ground line, and each of the pixels in a column to a voltage line, so that the voltage and ground lines run perpendicular to eachother. What you will end up with is 5 voltage lines and 5 ground lines, a total of 10 wires. Lets say that you wanted to only light up the pixels around the edge of the screen. Great, so you see that the first row of pixels needs to be lit, so you connect all of the voltage lines and only the first ground line. The first line lights up just how you want, perfect. So you move on to the second row. Great, you see that the first and last pixels need to be lit on this row. You see that the voltage lines for the first and last pixel are already connected, so you connect the second ground line. But here's the problem, every pixel in this row is now lit up, not just the end pixels. So you try disconnecting the middle 3 voltage lines, only to find out that those pixels also turn off on the first row, so that won't work. You will need to find a different solution. This solution is multiplexing. As it turns out, you don't need to keep the pixels turned on all of the time, Human eyes can only detect a change so quickly. So you will 'scan' through the image you are trying to create. To do this you start with the first row. Just like before you connect all 5 voltage lines and the first ground line, the correct pixels now light up. Perfect, now you move onto the second row. This time you disconnect the first ground line, turning off the previous line. Now you can disconnect the middle three voltage wires and connect the second ground line. Only the outer two pixels light up, and you can move onto the third row. You disconnect the second ground line, update the voltage lines to what they need to be, and connect the third ground line. Keep doing this process of cycling through the ground lines until you reach the end, and voila you've slowly updated the pixels to what the need to be. The only issue is that a human cant do this fast enough by hand, but if you swap out the human for a dedicated chip, it becomes possible. On the little flat flex cable that connects the display, there will be one or more of these little chips that does this multiplexing process. This chip will accept binary inputs from just a couple of connections, interpret which line to update, and output the correct signals extremely quickly. On modern displays with color and brightness, it's the same theory but more wires. Instead of 1 voltage per pixel you will have 3, one for red green and blue. And by varying the voltage, you can adjust the brightness of the pixel."
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af84dy | If dial up and DSL uses the phone line for internet, how come DSL is much faster than dial up? | Also, how does a telephone DSL filter work to remove the DSL noise? | Technology | explainlikeimfive | {
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"text": [
"This is a really good question. You're right, they both use the same physical bits of copper and you can use both the send digital data like an internet connection. What makes them different? The biggest difference is what frequencies they use. As you might know, sound is made up of waves of pressure in the air. How often these waves happen is called the frequency. Plain old telephone service (POTS) directly translates these pressure waves in the air into electrical waves on the phone wire. For voice frequencies you're looking at between 300 Hz and 4,000 Hz. But, the copper wire can handle a much wider range of frequencies than just that. DSL uses frequencies from 25,000 Hz up to 1.5 million Hz. This is a much wider range of frequencies and you can fit a lot more information in that space. A telephone DSL filter removes those high frequencies that the DSL connection uses and leaves only the voice frequencies."
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af8p63 | How can telescopes photograph the galaxy they’re inside? | Technology | explainlikeimfive | {
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"text": [
"If you have seen a photograph of the Milky Way from outside then it have almost certainly been an artists rendering based on scientific data. This is similar to how you can draw a floor plan from measuring the distances to everything inside and then make drawing of your house from the outside. However it is not an actual photograph even though it is almost as accurate as one. What we can do is that we can from inside the Milky Way measure where different stars and clouds are in relation to us and then from there draw a diagram of how the structure of our galaxy is. You can even conduct your own radio astronomy observations for a few hundred dollars worth of equipment to find out for yourself how the galaxy is structured and you can using that data to draw an illustration from any angle you want."
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afarvx | How do computers start themselves during a reboot after they shutdown? | Technology | explainlikeimfive | {
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"text": [
"There is something called ACPI which is an open standard for operations systems (windows, Mac os etc.) to communicate with the motherboard for a variety of purposes including but not limited to power management. There are many different kinds of reboots and restarts but the most full one involves having the os use ACPI to tell the motherboard to do the reboot in this case the motherboard will turn the OS and most components all the way off but stop short of turning itself off and then the motherboard will turn everything back on as if it was normal."
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afavsp | How come radio waves can be used to transmit very high quality data for TV/internet but the radios used by police departments and air traffic control tend to be garbled and staticky? | Technology | explainlikeimfive | {
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"text": [
"\"Radio connections\" can be of two types: analog or digital. In an analog connection, radio waves are converted to electricity by an amplifier and this turns directly into mechanical forces on a speaker. Any distortion in the radio waves during travel is represented faithfully to the speaker and you hear scratching. In digital connection, sound waves are translated into a sequence of packets which are transmitted in their encoded form to the other \"radio\" which then receives each packet and translates it back into sound. The use of \"packets\" in networking protocols allows for error checking and confirmation. Packets often contain a checksum which is the result of a mathematical operation on the packet's contents. If the receiver computes the checksum of a received packet and it is wrong, it can request the packet again from the sender. The result is a perfect recreation within the receiver, of the sound data stream sent generated by the sender. It's the same reason there isn't \"static\" in a Netflix video stream. Back in the previous millennium, TV was sent over analog radio signal and distortion of the image was quite common.",
"It basically boils do to that TV uses larger, higher bandwidth channels that can transmit a lot of information, while police radio etc. use narrower channels that don't carry as much data. Why is it like this? The radio spectrum is a crouded place. The FCC has allocated TV channels the large amount of space they need for their purposes, but for the sake of example let's say a local police department may only be allocated 24 kHz of radio bandwidth. With that space they can choose to either have one 24 kHz channel or split it into two 12 kHz channels. Obviously the bigger channel will allow more data through it and with that better voice quality. But if the department needs to have two channels, they'll be forced to essentially squeeze 24 kHz worth of information through a 12 kHz pipe. This is where the lower audio quality come from, basically cutting off the information you don't need in order to make it fit. This is called audio compression. It should also be noted that compression algorithms are designed with this, and the audio quality on modern radios is actually quite good, better than the typical \"radio\" sound effect used in movies and TV. There's other factors in play related to analog vs digital, AM vs FM vs FSK vs CPM, etc., but that's essentially a broad strokes explanation of the lower audio quality."
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afbkjb | what happens inside a dishwasher when it is completely silent but still has 45 minutes left on the timer? | Technology | explainlikeimfive | {
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"text": [
"Probably the dry cycle. It has a heating element that is turned on to basically bake the inside of the washer to dry and sterilize the dishes. Takes awhile. You can probably see steam coming out at this point.",
"Well you see, inside that big box there is a lot of wet things, so we need to make them dry! The box magically makes big gusts of air that is warm like mummy's hairdryer and pushes it all around the dishes, so that when we open up the door, everything inside is nice and dry! It takes such a long time because the warm air has to be gentle so it doesn't break everything inside."
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afclls | Why does turning it off and on again solve almost any issue on electronic devices? | Technology | explainlikeimfive | {
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"text": [
"Well, essentially with most issues on a device, turning the device on and off again will discharge all the circuits and clear the Ram, clearing up any tangles or knots. This is usually the first thing you do when troubleshooting because it's the easiest thing to check first. Then you get more and more advanced as you go on",
"It certainly doesn't solve \"almost any issue\", however it can remedy a lot of common niggles. There are, I think, two main reasons. 1. Turning the device off and on again resets the hardware to a definite known state. Sometimes during operation, unexpected states can cause odd behaviours. It can be difficult to get things back into known and expected states while they are still in use by the software. 2. Operating system files cannot be modified, and states of deadlock or undesired indefinite waiting loops can't be caught or stopped while the software is running. A reboot is the only way to stop and restart the operating system."
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afd9z4 | How does Google calculate busy times (that bar chart) for businesses? | Technology | explainlikeimfive | {
"a_id": [
"edxma6k"
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"text": [
"Google has access to location data for people using web browsers or apps that utilize a google service that permits them location data. So if you use google maps to look at a restaurant near you, and you’ve allowed them to access your location while not using the app, they can track how many people are at the business at given times. Obviously there’s a margin of error, but generally it’s pretty accurate. TL;DR- google sees where you and everyone else using one of their services is and judges how many people are there at a time"
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afdgdt | Why can't SPAM emails be completely identified and then simply prevented from reaching a user, instead of being routed to a junk folder? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"There's nothing that clearly identifies something as spam. It's mostly a guessing game based on the origin of the email and another details about the email itself. They send potential spam to a junk folder so you will have some recourse if there are false positives and they identify something as spam you were actually expecting. If you've ever had a service that you sign up for say something like \"check your junk mail if you do not receive an email from us,\" that's why. Your mail service may think it's spam if they are sending emails to a large number of recipients.",
"For the record what reaches your junk folder is a tiny percentage of the email that would otherwise be outright blocked by your SPAM filter. The Junkmail folder is the stuff that the filter identifies as 'maybe it could be legit? but not sure' As an email admin I can tell you that > 85% of the email that comes to my organization is SPAM and it just gets rejected by the SPAM filter software. Identifying SPAM is a lot harder than it sounds. If you filter by word you can block legit messages. If you filter by source, then you have to identify all the sources of SPAM and they change constantly. SPAMmers are really good at knowing how to get around SPAM filters, that's a requirement of what they do."
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afdo7t | How can companies figure out you rooted your phone even if you factory reset it? | Some of you might know that if you root your phone, it automatically voids your warranty (or so the warnings say). Let's say you factory reset it at some point and after you factory reset it, something breaks and you need to repair it. How do companies know that you rooted your phone before? | Technology | explainlikeimfive | {
"a_id": [
"edxtbg9",
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"text": [
"Certain companies (Samsung for example) have a physical hardware “switch” (called KNOX on Samsung) which is activated once the phone is rooted. This changes the KNOX value from “0” to “1” and it never changes back. Companies use this value which can be checked through settings to determine whether the device has been previously rooted before.",
"The warnings may say warranty is void if you root, but US law says that's only allowed for damage that could plausibly be caused by rooting (e.g. overheating, battery life, etc.). If your screen breaks, it's covered by your warranty even if you rooted it."
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afe5we | why wont disks from one video game console work on another video game console? | Technology | explainlikeimfive | {
"a_id": [
"edxviop"
],
"text": [
"Consoles are very protective of their software and games. But it's very much like a German and a Britt trying to talk. They might understand one or two words, but the whole conversation will not work. And therefore they won't do anything."
],
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aff5jy | Historically, Why did some civilizations seem to get stuck in the hunter/gatherer stage while others excelled in so many tangible ways? | Technology | explainlikeimfive | {
"a_id": [
"edy5ku1"
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"text": [
"Appropriate beasts of burden seem to have been a big factor. Notice that south america didn't have animals like oxen to till fields or pull carts (also, they had yet to develop the wheel) leaving all manual labour powered by human hands. Things like the shape of continents can influence agriculture and trade in ways that are hard to notice at first. plants are adapted to particular latitude & climate, it's easier to move crops east-west than north-south, leading to eurasia having more plentiful variety of crops than the americas without developing from hunter/gatherer into agriculturual communities, people don't have time to invent writing, metallurgy, etc. The Australian aboriginals, Pacific Island cultures, etc had some very smart inventions & tools for their region, but didn't develop the huge agriculture of the middle east and the following explosion of population & innovation. Then there's the factor of more advanced cultures bumping into less advanced ones and giving them all smallpox, pillaging, shooting, and otherwise mucking up whatever development they might have made had they been left alone."
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afgwhz | How do public and private IP addresses work? | Technology | explainlikeimfive | {
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"text": [
"Exactly! Your \"public IP\" could be compared to the physical address of your house (\"123 Example Road, Exampleville, Examplecountry\" for example). Your \"private IP\" would then be what you call each room in your house (\"James Harden Jr.'s Bedroom\" for example). There won't be a duplicate for your house's address, but there could be many duplicates for the name of your room (pretty much everyone has a kitchen). Every room in your house \"shared\" your house's address, and so if you want to get a package sent to you that is what you give out. The specifics of how your router and modem (the devices that take care of all of this IP business) handle public and private IPs is a much more complicated topic which sort of goes outside of the ELI5 range.",
"Yes much. Your ISP likely assigns a single IP in address to your modem, which creates a local private network wity any amount of clients",
"Depends of the setup of your home network. Usually there's a device called \"router\", which has a public IP assigned to it, and which gives private IPs to every other device in the network (or they may have them set up beforehand). It also \"routes\" (hence the name) the network traffic from the inside of home network to the external world, and in the opposite direction (usually according to some predefined rules).",
"The Public IP will be the address of your house, and the private IP will be the \"addresses\" of each room on your house. People doesn't need to know where is your room to send you a package, they will send it to your public address and the owner of the house, let's say your mum will take the package and take it to your room. (your mum will be the router).",
"In a typical home environment, yes. As others have said, your router has a public IP address facing the world and a private IP block on the side that connects to your home network. Your router does something called \"Network address translation\". It basically takes the traffic that is going in and out of it and replacing the private IPs with the single public IP in the data packets before sending it on its way. When the data packets come back, the router knows what computer on the inside is talking to what computer on the outside and so it can replace the public IP back with the private IP and send it out to the home network side. & #x200B;"
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afieea | What is a data center? | What is a data center? | Technology | explainlikeimfive | {
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"text": [
"A (usually) large building built to hold lots of computers and storage. It'll have communications so people can access the computers, uninterruptible power, air conditioning, fire suppression systems (which aren't water based), a lot of security and IT staff. Often they'll be anonymous warehouses on industrial estates (as it's cheap land) with no signage (for security reasons)."
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afii7a | How is data actually transferred through cables? How are the 1s and 0s moved from one end to the other? | Technology | explainlikeimfive | {
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"text": [
"You know how when you touch a live wire you get shocked, but when there's no electricity running through the wire you don't get shocked? Shocked=1. Not shocked=0. Computers just do that really fast. There's fancier ways of doing it using different voltages, light, etc, but that's the basic idea",
"As texasslapshot said, 1 = on and 0 = off. To expand a little this is done with either light pulses (in the case of fiber optics) or electrical signals (in the case of copper core wires, like ethernet cables). At the beginning of each frame (chunks of data) there is a series of alternating signals (10101010101010) to establish a tact of how fast the signals come, so that the receiving end can establish whether two identical signals following one another (11 or 00) are actually two separate signals, rather than the same signal for a longer period of time.",
"1 = on; 0 = off. Light pulses are sent through the reflective fiber optics cables, and the device reads the on/off as binary data.",
"There are numerous ways '1' and '0' can be physically represented in a cable. One of the most basic methods is by high and low voltages. E.g. to send '1' transmitter puts batterie's positive pole to the cable, but negative pole for '0'. Receiver has a voltmeter so he knows if voltage on the cable is high or low.",
"You know when you throw a rock in a pond and waves expand outward? Turns out electicity+magnetism behave somewhat similarly. If you hit them with energy, they'll wave, and the waves propagate outward. Now imagine a very long, very narrow canal of water with a wave machine at one end and a guy observing waves coming out the mouth of the canal at the other. As you can imagine, there are lot's of ways to change the wave machine, the the fellow at the far-away mouth of the canal would be able to observe. Bigger vs. smaller waves (this is AM radio), faster vs. slower waves (this is FM radio). If you want to make it \"digital\" (i.e. represent just 1s and 0s), you pick two states and only vary between those. If decide to go with fast vs. slow waves (this is called frequency-shift-keying aka FSK), the guy at the end of the canal watches waves and if they're fast, he writes down a 1, if they're slow he writes down a 0. Now, what if he could faithfully differentiate between 4 different state rather than just 2 -- say, slow, medium-slow, medium-fast, and fast? This would allow the wave machine to send him more information in the same amount of time. We just assign 2 bits to each state now -- slow=00, medium-slow=01, medium-fast=10, fast=11. What's the limit on adding states? Well, if the wind is blowing, and it get's difficult to tell the difference between two speeds as they get closer together, we start getting read errors or \"bit errors\". There's also a physical upper limit on how fast the wave machine can move the water, and a lower limit on how slow it can go before the waves stop reaching the observer. So each state has to operate within this fixed window. There's lot's of other tricks that come from complex (as in sqrt(-1)) math, to get more bits through the canal in a reliable way, but that's the gist of it.",
"Its basically like a telegraph. The dots and dashes or 1s and 0s are translated into coded pulses of energy like electricity or light that move through the cables to be decodeed by the recipient",
"There are many approaches. Short cables that don't transmit very fast, often work on TTL Transistor-transistor logic (TTL), where by a 0 (low) is ground and 1 (high) is either 5v or 3.3v. Things change when distances are longer, or transmission speeds are faster. This is because there is an electrical \"noise\" present. This noise is a random signal that is induced on the wire from multiple things, including the environment and the AC power in your house. The signal is only detectable if the \"average\" high/low signal voltage is reliably noticeable as different in the presence of the noise. This is why we asses the quality of a signal via a 'signal to noise ratio' (SNR). There are a number of things we often do to address this problem: - Transmit with higher voltages (so the noise is smaller relative to the signal). eg: Com port's do this using 15v signals or phone lines at 48v. - Protect the cable from noise via shielding (USB cable) or twisted pair cables (network cable). - Include a bit of extra data to allow for 'error detection' and just resend any lost data. If your'e only loosing 0.1% of your data, it's better to resend it than slow down the signal. - Similar to using extra information for error detection, we can send extra info for 'error correction' letting us fix up small errors. Fixing errors on high speed transmission with extra data, allows more throughput than slowing down the signal to make it reliable. This is the basis is of a \"transmition Control Protocol\" TCP. - Transmit information slower so that we can better affect the high/low average in the presence of noise. eg: railways do this to send signals along the tracks for hundreds of kilometers.",
"There's a few different algorithms to transfer data, there's Return to Zero Code, Non return to zero code, Manchester Code, Differential Manchsester, and in general current is sent through a wire and different currents equal ones or zeros, i.e. In ~~Differential~~ ( < - got those mixed up. My bad) Manchester Code a switch from low current to high current is a 0 and switch from Hugh to low a 1. In a NRZ code there's a high current and a low current and a high equals 1 a low equals 0. In Fibre optic the same is done with light pulses Edit: Thanks for the Silver kind Stranger. It's my first one",
"Lots of people are saying light on, light off, but this is not what actually happens now. This is correct for extremely old systems, but it is so out of date as to be misleading. Simplest way Light goes on, light turns off. Light on means a 1, light off means a zero, now you just write them down. The problem with this is how long do you wait if the light is on to count it as two 1s in a row? You have to share a clock and only count when the clock ticks, so you both know when the 1 or 0 has been counted so you can move on to the next number. This adds a problem, suppose your clock is a little slow, maybe a low battery. At first you won't notice but after a while you'll get out of sync with your friend, so they sent 1 digit but you read 2. Now you have a double of one of the numbers in your list, so you can have some issues. Simple+ Now we add a few other things. We can break the numbers into groups, let's call them bytes. A byte is 8 bits, 8 1s or 0s. So 00000000 is one byte, 11111111 is another byte, and any mix of those is a byte, like 10010110. After we send a byte through we can do something to get in sync with our friend on the other end, so we may send a specific signal, or maybe do something else to confirm we are done with that set and on to another. One trick is to add up all the numbers we just sent and check if there are an even or odd number of 1s. If it is odd, send a 1. If it is even, send a 0. Now we can pretty often check if we have misread something, though this still has issues. Maybe we need something more complex. A little complex Let's talk about carrier waves. You know how if you are dancing it is much easier with a beat? We can do the same thing here, but we do it with something else very regular and predictable, a sine wave. This is a sound that is very simple and only has one frequency in it, just up and down like a clock. So we don't turn the light on or off now, we turn it up and down. What we should see on the other end is a light going up and down in brightness evenly at a constant rate. This means we have a base tone to hear and we can then add stuff on top. Say we agree we are going to use a middle C sound, the centre key on the piano, as the base sound. We can then add anything we like on top of it and we can then use the base sound as a shared clock and the higher notes as the extra sound. With a little bit of extra thinking we can subtract out that base sound and hear just the top sounds. Now if our clocks are different we don't need to worry, the signal itself is making our clocks the same. Things like this are really complex, but the details are fascinating and if you can understand how these things work you get an idea of the kinds of problems that can occur."
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afizq0 | How A.I. is possible | I searched subreddits, and there's a few questions similar to this. None of them have gained any momentum. So... Is A.I. built the same as a computer chip? Is it just code that defines it? What kind of code? ELI5 though.. Because im not smart.. Thanks. Edit: Thanks for the answers!! One last question. I read a lot about medical research using "AI" and how it can detect things like Alzheimer's super early. If AI doesn't exist what are they using and how can they get away with calling it AI? | Technology | explainlikeimfive | {
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"In the interest of sticking to the spirit of ELI5, I'm gonna gloss over some really interesting and complicated things. If anyone has questions or wants greater detail, feel free to ask. *** Since it's kind of an inherent property of computers that any computer can run any software, the development of AI is a programming exercise rather than an engineering one. In order to understand what kind of programs may be AI, we first need to ask what AI *is*. In the perception of the general public there are essentially two categories of AI, one of which exists and one of which does not. The latter is the kind of AI you see in science fiction movies like *Terminator*, *Eagle Eye* and *Blade Runner*. We call this *artificial general intelligence*; AI which can perform general intelligent action (like humans and other animals do) or perhaps even experience a kind of consciousness. The former is the kind of AI you see in software, websites and other applications such as self-driving cars, virtual assistants and those face-changing cellphone apps. We call this *applied artificial intelligence*; AI for studying specific datasets, solving specific problems or performing specific tasks. In general, you can expect that the continued development of applied AI will lead to the eventual emergence of AGI. The distinguishing mark of the kinds of problems we use applied AI to solve is that they are problems which previously we would call on a human (or at least an animal) to solve. For a long time, human drivers, living assistants and human artists are how we would accomplish solutions to the problem examples I mentioned above. Meanwhile, the natural strength of computers is in calculation alone. While humans could do all sorts of things computers could not, computers could perform calculation much more quickly and accurately than humans can. Thus, there was division between man and machine. I hope all that context wasn't too boring because I'm about to get to an important point. Now that we understand what AI is, we can rephrase OP's question in a way which gives us insight into the answer. Instead of \"how is AI possible\", we ask this: **how can we make computers good at doing the things that people can do?** And the answer, of course, is in finding ways to mathematically describe the problems that humans solve by means such as instinct and practice. If we can come up with a way to describe human problems with numbers then we can use the computational strength of machines to solve those problems. Thus the endeavour of AI programmers is all about collecting, understanding, framing and processing data. It's about forgetting how a human sees a problem for long enough to boil it down to sheer numbers that a machine can work with and then returning to a human frame of mind so that the meaning behind those numbers is not lost. This leaves the question of how, exactly, it is done and I suppose the best way to answer is with a simple example. For those who want to **TL;DR** past the bulk of this comment, here's where to jump in. Imagine you want to write a program for telling red things apart from blue things. First, you're going to need to collect some pictures of red things and blue things and then you're going to label each of them with the correct colour. You feed this information to the computer. Now, digital images are stored as lists of numbers. Each pixel has a value for how red (R), how green (G) and how blue (B) it should be displayed. The computer can see that the images labelled \"red\" tend to have pixels with high values for R and low values for B while the images labelled \"blue\" tend to have pixels with high values for B and low values for R. It can also see that the value of G just doesn't seem to matter much. At this stage, the program has a rudimentary understanding of the labels \"red\" and \"blue\" as they relate to the pixel content of an image. Now you can show it a new image and ask it whether the image belongs to the \"red\" set or the \"blue\" set and the computer will look at the pixels, do some math, and tell you whether the image has high R values or high B values. The more images you use to train the computer with, the better it will understand the difference and the better a job it can do of telling red and blue apart in new images. *** Hopefully this helps. Chances are I've missed out something important so please feel free to ask me questions or for greater detail on any point. It's really an interesting topic and it's certainly the direction of the future.",
"First, it's important to understand that AI is a lot of different things all wrapped up under one category. Most of what we call AI is just software (or code as you put it). There is hardware that will accelerate the kinds of calculations that this code requires but the chip itself would not be considered the AI. Two common approaches to AI are neural networks and genetic algorithms. Neural networks are an attempt to recreate the way the brain works by having multiple nodes between the input and the output and the program will build connections between those nodes. The connection and strength of that connection will determine what the output is. This is a loose approximation of what the brain does when it learns. Genetic algorithms are a way for a system to get better over time. You start with a population of individual programs that are basically random in their configuration and then you test them on whatever task you are attempting to perform. Most of them will be awful because they're just acting randomly but 1 or 2 might be slightly better than random. You take the best examples from the first generation and slightly mutate their configuration until you have a second population. Then you test them and hopefully some of these mutations were beneficial and you have 1 or 2 that are better than the best from the 1st generation. Keep doing this over and over and eventually you might end up with a program that can do the task you want without ever directly programming it how to do that task.",
"The most important thing is that AI is a misleading name. It would be FAR more accurate but a lot less sexy to call it \"Improved Pattern Recognition\".",
"“AI is whatever hasn’t been done yet” stated Larry Tesler in 1980. AI has been coupled with different technologies during the years. Currently, we are facing the problem with a set of techniques implemented in software. One of the most hyped and, since 2010, common technique is deep learning, which for sake of simplicity we will refer to as neural networks. A neural network is a set of connected nodes, called neurons, which takes a numerical (multidimensional) vector input and outputs one or more values. Each node basically applies a mathematical transformation (e.g. multiplication) to the input with respect to a weight (multiplication factor) and see whether the result activated or not the considered neuron, propagating the result to the next node. Why deep learning? Because we are facing problems by creating very deep neural networks and training them on known data (a lot of data) to predict values when fed with unseen data. The learning process consists in adjusting the aforementioned weights (factors) to obtain the known result given the known input. The are plenty of operations that a node can perform, defining different network architectures. There are evidences that some architectures work better on certain problems and worse on others. So right now, imo, AI is a architecture definition + data collection problem.",
"To (more or less) quote a student who took a course on ML/AI: \"I'm disappointed. It's just a bunch of maths and statistics. Nothing special. I dunno... I expected more... magic\".",
"Nowadays AI is a marketing name for machine learning. Simply put, it's a class of algorithms that can create a function from inputs and outputs of this function.",
"I would focus on trying to understand machine learning first, which is having a real impact on the world. General AI isn't a thing yet and while it may be possible some day, ML is changing our social and economic landscape every day.",
"There are different kinds of AI. “Expert Systems” have been around a while and they’re usually pieces of software that use “if-this-then-that” logic. Machine learning is another popular AI technique. If you wanted to make an app that could tell the difference between a picture of a cat, or a dog, you would input thousands of examples labeled “cat” or “dog”. Then, the software’s core processing routing (“the algorithm”) would “learn” to tell the difference. A popular “learning” algorithm is a neural network. Think of it as layer upon layer of simple software image filters. The top layer might recognize edges in the image, the the next layer might recognize the difference between edges that are cat-like vs edges that are dog-like, and at the end of the process, after the image has been filtered through all of these layers, the computer gives a “score” of how likely it is the image is a cat or a dog. It might be clear now that the better the example images you use, the better your software (“the model”) is. Gathering high-quality examples is one of the hardest parts of AI! Now, when you give the software a new image it’s never seen before, it can filter it through the neural network and get a score. For instance, it’s 90% likely that this is a picture of a cat. The software can be written in one of many languages. Printing the software routines onto a chip doesn’t really change the way the software works other than it makes it faster."
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afjlag | How to the astronauts and everyone on the International Space station have oxygen? | Technology | explainlikeimfive | {
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"Electrolysis of water (H2O) is the main method to generate oxygen aboard the ISS. Water is split into oxygen (O2) and hydrogen (H2). The oxygen is vented into the breathable cabin air system, known as theOxygen Generation System, while the explosive hydrogen is vented externally."
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afjvqa | Why are my passwords secure with a password manager, and not just a huge target with everything in on place? | Technology | explainlikeimfive | {
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"Password managers keep your passwords encrypted, so they wouldn't be accessible to anybody who \"broke in\". They also encourage you to use unique, random alpha numeric passwords for each account, so if somebody breaks into one of your accounts, your others aren't compromised. And your master password for you manager should really be a master pass phrase, a longer sequence like a memorable sentence. The more characters involved, the harder it is to break. The combination of techniques make it an extremely hard target for would be hackers."
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aflwr8 | Why do bunker freezers still work in grocery stores even though they have no lids to trap cold air inside? | Technology | explainlikeimfive | {
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"1. Cold air sinks while warm air rises, so unless there's a strong breeze it's not really going anywhere. 2. Some of them generate an artificial recirculating cold breeze (an \"air curtain\") to further limit unwanted air flow."
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aflyuj | How does a black and white photo decide which colour to show as white and which to show as black? | Technology | explainlikeimfive | {
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"It's simply based on brightness — the total amount of light reflected. Most colors show as various degrees of gray, depending only on how light or dark they are."
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afm4zr | If cables transfer data in "1/0" by being "on/off" with electricity, what's the difference between cables? Like what happens in an HDMI that doesn't happen in an aux cord? | Technology | explainlikeimfive | {
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"That's how digital cables work. By chance you've actually picked a digital (HDMI) and an analogue (AUX) cable in your question. An analogue cable transmits data in a continuous flow where it changes the voltage over time. A digital cable, like you described, sends pulses of electricity to represent distinct ons and offs. But I assume your question is asking how do different types of digital cable differ to each other? And the answer is mostly in how they format the data in order to represent it in ons and offs - different methods are referred to as protocols. A standard HDMI cable for example has 19 pins. Each one is used to send different information through the wire so that on the other end they can collectively be understood."
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afmqvr | How come in many cases, when a program crashes, it will not close even after clicking "end process" when prompted. However, it closes instantly when ended through task manager. | I never quite understood this. When a program crashes and the PC prompts the user whether they would like to terminate the program or wait for it to respond, it often times will not close even when the option is selected. However, when using task manager to end the process, it closes instantly. | Technology | explainlikeimfive | {
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"Programs are managed by the operating system. Clicking the red x or using the prompt asks the program to close itself, but the program is stuck and cannot respond to the request. Using the task manager tells the operating system to just kill the process."
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afn9xl | What is the difference between 3G, 4G, LTE, and the new supposed 5G besides the fact that they are faster? Why are the called what they are called and why has it taken so long to get to what is classified as 5G? | Technology | explainlikeimfive | {
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"From the customer's perspective, it's simply speed and capacity. A higher generation technology can provide more speed to more people at the same time. 5G is a little special because it uses really high frequency radio waves that don't penetrate buildings well. So, we're going to need a lot more cell towers and it won't work very well deep inside buildings. G means generation. There have been 5 generations of mobile data technology. In each generation there have been multiple standards that are all considered to be the same generation. For example, CDMA and HSPA were both 3rd generation (3G) technologies. LTE is an example of a 4th gen technology."
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afnhkj | How do emergency flotation devices inflate quickly? | I'm talking about those vests in airplanes where you pull a cord and also this post that's been floating around URL_0 What makes it expand so fast? | Technology | explainlikeimfive | {
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"Generally they have a CO2 cartridge that releases into the vest for quick inflation. There’s a tube you can use to blow it up if that fails."
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afovgd | How is (or has) technology improving so quickly, when computer science/math is one of the hardest subjects? | Technology | explainlikeimfive | {
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"Not everyone considers math and science hard topics. Those people are the ones doing the advancing.",
"I think computer science and math are easy. They follow logical rules and patterns, so as long as you know the patterns and can recognize them, you're all set. Now, if you try to have me write an argumentative essay that emotionally affects the reader, that essay would be a disaster because I'm horrible with emotions and writing. Everyone has their strengths and weaknesses.",
"A lot of the recent improvements are improvements on existing technology or existing processes. Which is not to say they’re not as impressive as inventing it the first time, but it’s (relatively) easier. Getting something seemingly simple, like going from the LEDs from 30 years ago in to a product that can replace old lightbulbs took a lot of R & D and work. And it doesn’t seem that impressive. It’s a light bulb, we’ve had those for decades. Once the first product was made, though, going from that in to something more impressive is easier. Now you can have customizable lighting that changes and you can control from your cell phone. That’s impressive and seems to have come quickly...largely because a lot of leg work on the “simple” LED bulb was done."
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afpp72 | Why do washers have temperature settings such as "hot cold" or "cold cold"? | Technology | explainlikeimfive | {
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"It's just missing punctuation. \"Hot, cold\" means \"hot wash, cold rinse.\" And so on for the other combinations."
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afqwa4 | How are older movies remastered into HD if they were shot with old cameras that didn’t shoot in HD? | Technology | explainlikeimfive | {
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"text": [
"HD is merely a resolution standard. Film has traditionally been scanned to digital at 4,000 pixels wide and HD is only 1900 wide so there is plenty of room for remastering."
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afrggb | How can a microSD card the size of your thumbnail hold 1TB of data? | Technology | explainlikeimfive | {
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"Transistors store data. Transistors can fit into a 3d-space and can be stacked. Right now transistors are usually ~20nanometers. Human hair is 100000nm. For a 1TB microSD the transistor would need to be ~5nm. Theoretically, a transistor could be as small as a single molecule. You need ridiculously precise manufacturing techniques for these small sizes. At the molecular scale current physics has become a problem. Electrons can only move so fast, and heat waste becomes an issue. Quantum physics comes into play and photon-based computing (rather than electrons) is needed."
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afrr6x | why does a radio start at 87.7 and end at 107.9? | Technology | explainlikeimfive | {
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"Those are the radio station frequencies that are \"allocated\" (given) to radio stations that are designed for broadcasting consumer-based media (music, talk shows, etc.). There are a ton of other frequencies but a lot of them are reserved for other use (for instance, there are international frequencies for emergency messages at sea). You can see just how many other types of messages and frequencies are used if you look at this crazy chart - URL_0",
"Great minds think alike. Yarr! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why does the radio only go from 88.1-107.9? ]( URL_4 ) ^(_7 comments_) 1. [ELI5:How does FM radio work? Why does it only range from 87.7-107.9, and why is it only odd numbers? ]( URL_1 ) ^(_3 comments_) 1. [ELI5: Why do FM radio stations seem to always be in the 80-100 range? Why do we never hear of FM stations like 30.5 FM? ]( URL_0 ) ^(_3 comments_) 1. [ELI5: why are all the FM stations ending with odd number always? ]( URL_3 ) ^(_3 comments_) 1. [ELI5: Why do current FM radio station channels only range from ~80 - ~105? ]( URL_2 ) ^(_7 comments_)",
"So, those numbers are frequencies you can tune the radio to receive, in megahertz. Ok. Well, in America, the FCC has decided that 87.8 MHz and 108.0 MHz define the lower and upper limits of the FM band, meaning that any FM radio station that wants a license to broadcast has to transmit on on one of those frequencies. There are other regulations that go along with it, such as you can only transmit on odd decimal frequencies (101.1, not 101.0 or 101.2), but that's the gist of it. The AM band works on a different principal, and is numbered in kilohertz instead of megahertz, between 535 KHz and 1605 KHz. The regulations are different for the AM band than for FM."
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"https://np.reddit.com/r/explainlikeimfive/comments/4cgtw7/eli5how_does_fm_radio_work_why_does_it_only_range/",
"https://np.reddit.com/r/explainlikeimfive/comments/60e3sh/eli5_why_do_current_fm_radio_station_channels/",
"https://np.reddit.com/r/explainlikeimfive/comments/4au3lf/eli5_why_are_all_the_fm_stations_ending_with_odd/",
"https://np.reddit.com/r/explainlikeimfive/comments/1nxewn/eli5_why_does_the_radio_only_go_from_8811079/"
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afw4rj | How did old video games fit into such small spaces on cartridges? | Technology | explainlikeimfive | {
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"Majority of the game's code were shared among all games (libraries etc...) which was directly in the console. The cartridge contained just a small piece of code for that very game",
"It's all about detail of the game and what's needed to be stored. Super Mario only had like 5 colors or something rediculous and Ocarina of time looks like garbage compared to modern games. The more detail you give a character and environment, the more it takes to process those details and storage to house them. Link in OOT was little more than a few very noticeable polygons as was the entire world. Super Mario was literally stacked pixels with no rounded corners. Those things are easy to store and render, hence the low storage requirements and small processors."
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ag0ot3 | Why can’t sound engineers create a consistent volume level throughout an entire movie or TV show, it’s either too quiet or way too fucking loud at different times? | Technology | explainlikeimfive | {
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"They can, it is just bad. Part of what makes a show or movie better is to have dynamic range in the sound. It makes things more like real life and most of the population enjoys the movie more.",
"1) They mix for a listening environment that you probably aren't experiencing. 2) They mix to intentionally have intimate moments and dynamic moments for the sake of immersion in the show/movie 3) Converting from a sound mix made for a giant theater with 30 speakers down to a 2-speaker presentation, or even a 5.1 presentation takes a lot of work that has to deal with issue 1.",
"I get it for people who have a home theatre/surround sound. But watching on a regular TV, I constantly have to blast up the volume of a show just to hear dialogue, then crank it way down every time there's a loud sound effect or music playing so it doesn't piss of neighbors. I live in an apartment building and tend to watch stuff later at night so it's quite a pain.",
"Imo a better question would be why isn't there a separate track for SFX and dialogue so you could adjust both independently like many video games let you do."
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ag3gz8 | Where do domain names originate from and how are they made? | Technology | explainlikeimfive | {
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"Domain names and DNS services is quite an interesting topic for computer networks. You will find that there is a central controller who maintains the domain names they are responsible for. For example there is ICANN for America and the .com domains. URL_1 Other places and other top level domains will be controlled by a different governing body. So it means there is no one body that controlls all the top level domains but a collection who are responsible for their own domains. We then have registrars like GoDaddy and who ever else who will interface with the public and sell you your own domain under a top level domain. URL_2 / my URL_0 Depending on what you choose the registrar will put an application in to the top level domain controller to say this domain is registered to X."
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ag4eqn | How do bullet proof vest stop bullets, but can't stop a knife thrust? | Technology | explainlikeimfive | {
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"Bullet resistant soft armor is made of very tightly woven, very strong synthetic fibers. Usually a combination of things like Kevlar and ballistic nylon. Those fibers stretch, but don't break when a bullet hits them. This causes the armor to spread out the impact across a larger area of the body, making it less likely to cause serious or fatal injuries. Bullets are fairly blunt objects though, and when they hit something hard they tend to flatten out and get even blunter. So they engage many fibers at once that all work together to slow them down. A knife is sharp and very hard. It can engage and break a few fibers, while the point slides between the rest. So soft armor vests generally aren't rated against puncture threats like a knife or spike. For those you need hard materials like metal mesh or hard polymer/ceramic plates."
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ag4mf4 | How does the touch screen on a touch pad works? | Technology | explainlikeimfive | {
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"Please use the search function as stated in the rules. This question is frequently asked and answered."
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ag7r9k | How was wire made in medieval times? | Thin metal wire for making the links of chain mail and nails? | Technology | explainlikeimfive | {
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"You pull a strip cut from a sheet, or a hammered out, thick piece of wire, through a slightly conical hole in a thick metal plate. You keep doing this with progressively smaller holes until you have wire of the desired thickness. It's just as finicky and time-consuming as it sounds. Nails were not made from wire, they were simply forged from thin bar or round stock.",
"You do it a lot lik you do today. You pull it trough holes that decreases in size a small amount util the dimension are correct. search for \"wire drawing bench\" and look at videos how you can do it by hand today. Nice small winches with gearing like that did not exist by you could do similar things in wood. Large humans size hamster wheels to lift thing as crane existed back then and was used to lift rocks when you build churches and other large stone buildings. So you could get some mechanical aid or just pull by hand Here is a medieval painting of it being done by hand with large pliers as help URL_0 Making wire in similar way but with stone beads was done in Egypt by the 2nd Dynasty 2800 BCE for jewellery. This is in the bronze age so wires of iron for armour is a lot later. Making nails out of wire is a recent invention and large scale manufacturing if nails from wire is in the mid 19th century. It is not drawing the wire but the stamping that reshape a wire to a nail that is hard. So nails before the was forged by hand by a smith and not from a wire but a larger piece of metal that you shape in the forge. Nails expensive so most wood construction in medieval and later tried do avoid using them. Is is when the production is automated in the late 19th century the become cheep and common in construction."
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agd0if | How do noise canceling headphones work? | I thought it was the fit of the ear piece, however these headphones have a switch that turns noise canceling on and off. How do thy do it? | Technology | explainlikeimfive | {
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"Active Noice Cancelling ( ANC ) Headphones have microphones to detect noise ( car / train / whatever ) Any sound is a soundwave The ANC Headphones detect the waves, calculate what part of them would reach your ear, and send their own soundwaves. Both soundwaves cancel each other out, resulting in silcence Obv a very simplified explanation, but this is how it works"
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age0yq | What is data? | Technology | explainlikeimfive | {
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"Data is portrayed by actor Brent Spiner. Data was found by Starfleet in 2338 as the sole survivor on Omicron Theta in the rubble of a colony left after an attack from the Crystalline Entity.",
"Data is any bit of information. For example: You have a sensor at the door that can tell you gender/height/age. Each bit of information is a data point. You can imagine what a clothing store vs a restaurant would value within those 3 things, but regardless it is data. Other things can also be data: time/temperature/wind In large websites: Username/Password/Login Time/"
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aghev5 | Why do loading screens hang at 99%? | Technology | explainlikeimfive | {
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"There's no universal standard for loading. But here's how it *might* work for many programs. To draw an analogy, for most loading screens imagine it like this: You have a bunch of lego bricks. When you're told to build something out of them, your job is to draw the curtain, build the thing with the lego bricks, and then open the curtain to show the audience. Along the way you're meant to call out how far along the building process you are. Let's pretend you're building something that has about 100 pieces. Your first piece is a 2x2 brick, and your second piece is a 2x4 brick. Even though the second piece is twice the size, it's still just 'two bricks' and so you say you're 2% done. When you're finished, you do one final check that you built it correctly. Then you go over to the curtain to unveil your finished product. That process of double checking that it's correct, and 'unveiling' it, is the 99% step."
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agi09b | How do elevator algorithms work? | How do elevator algorithms work? As in, how does it determine how to get everyone to their desired floor in the most efficient and fastest way? Say, for example, if I wanted to go down from the 30th floor, but someone on the 20th floor pressed down before me. Would the elevator first go up to floor 30 and then pick up 20 on the way down? Or the other way around? | Technology | explainlikeimfive | {
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"There's a lot of ways you *could* design an elevator to optimally get everyone where they want to be in the most efficient method but generally they prefer simplicity & the sense of \"fairness\" over complicated solutions. An elevator going down will go down until it gets to the lowest floor that somebody wants to go to. It might go down a few more if somebody wants to head up. When it's done, it'll go up until it hits the top, possibly going up a few more to get somebody who wants to be on the trip down. With multiple elevators & express elevators, things can get more complicated but they try to keep everything simple. You might see an elevator return to the lobby by default from 8a to 10am because you know people are coming into the building or something like that but it really isn't a problem worth trying to optimize.",
"From my experience+reasoning, a simple design: The elevator have 3 states- idle (no orders. Just wait at the closest floor), and going up or down. When idle, go to the first button pressed. When going down, listen to any down-button press. If it's below your target floor, ignore it. If it's above your current floor, or you can't decelerate until that floor, also ignore it. Otherwise, set it as the new target floor and return the previous target back to the unhandled pool (if there is another parallel elevator, it might take the call). If you're going down and there are no calls down below you, switch to idle. Works the same for the up-state. In your example, it would get you on it's way down. I've heard of a race going down by stairs vs the elevator. The person running down the stairs pressed the button on each floor on the way down, forcing the elevator to slow and stop, so it couldn't speed down. Edit: some elevators have priority systems that allow a key-holder to make the elevator ignore all other buttons, that rest at specific floors, prioritize one type of requests depending on the time of day (always go directly to floor level when going down at the morning, allowing more people easy access to the upper floors when they get to work), \"Shabbat control\" (ignore all buttons, and take specified route. Used by highly religious Jews who can't press buttons on Saturday), \"fire control\" (go directly down and open doors, unless a firefighter key is used) and many more special cases."
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agjhc0 | Can you use a GPU as a CPU? Why/why not? If not, what's the difference between them that makes it impossible? | Technology | explainlikeimfive | {
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"While a GPU can do all the operations a CPU can (which mean that you could, *in theory* use it like a CPU), the architecture isn't optimized for it would make it very inefficient. While CPUs and GPUs are basically the same thing (processors), both have different goals: the CPU is optimized for latency, and the GPU is optimized for throughput. (The goal of the CPU is to do any sequence of operations in the smallest possible amount for time, while the goal of the GPU is to do the maximum amount of work per amount of time). To do this they both use different architectures/layouts: the CPU has a few, very big, fast cores and the GPU has hundreds/thousands of tiny, slow \"cores\". So to make an analogy: * The CPU is a supercar: two seats, 200mph top speed. * The GPU is an articulated bus: 400 seats, 30mph top speed. If you wanna do *one* (or two) things really fast, the CPU wins. If you want to do the same thing over and over and over again a billion time (and don't care how long it takes to do it just once), the GPU wins. ************************ How does this look like on the chip then? To really understand this, you need to know that in a CPU, the circuit that does the actual computation (let's call it the ALU) is incredibly fast and the most important thing for CPU speed isn't to make it faster, but to keep it fed with work to do and data to work on. For this reason CPUs have a ton of extra circuits whose job is to keep the ALU busy (caches, predictors, schedulers, buffers, ...). GPUs don't do that as much. GPUs are designed to process pixels or triangles, and there are millions of them on a screen. The repetitive nature of the work done on a GPU means that most cores will work on the same kind of thing at the same time, and the circuit that feed them with instructions and data can be shared across cores. And since you don't care how long it takes for a single pixel to be computed, but rather how long it takes for the whole screen, each GPU core can afford to compute several pixels in parallel to amortize wait times (if the computation for a pixel has to wait for data from memory, the core can just switch to some other pixel). The resulting architecture is very different: instead of having big cores with their own ALU and a huge control circuit to make the ALU happy, The GPU has groups of cores that share the same control circuit. This means that they can have a lot more ALU (because they don't need as much control stuff), but that cores aren't all independent. Cores withing a group have to work on the same thing, which is fine when doing graphics but can lead to atrocious performance when trying to do one single thing.",
"A CPU is a single superman doing superman work. A GPU is a collection of small tiny elves doing a large quantity of small tasks. In short, you cannot expect superman to assemble a million toys per second, and you cannot expect a million tiny elves to do superman's work. edit: typo expect/except",
"CPU is better at tasks that require decisions and branch, GPU is better at repetitive tasks that take input since it's built to handle millions of pixels having their lighting shaded for example (based on the angle of the light and surface and other material properties). Because the formulas (or series of) are more of a todo list and all the same, they can be executed in parallel, which makes the GPU so fast. You can kind of see why decision based code (if, else) would interrupt this. If you've ever written a shader this is why using conditionals (if, else) isn't advised, though modern gpus are getting better at this. Both can do eachothers job, but they are slower. Old school Runescape is a good example of a game that does its graphics on the CPU (aka a software engine).",
"A GPU is made to do simple, repetitive tasks really well, really fast. A CPU is made to do as wide a range of tasks as possible, with the understanding that it's not as fast as it could otherwise be. So yeah, you could technically use one as the other, but you're not using the right tool for the job. This obviously simplifies things, and leaves out a lot of nuance and exceptions and edge cases, but should give you a super clear overview",
"A CPU and a GPU are both just beefy microcontrollers (oversimplified) so in theory you could write an operating system that runs only on your GPU, but it would not be really practical because a GPU is a completely different architecture than a CPU so software support would be more than lacking",
"There are two main differences between CPU and GPU design. First is the one many others have mentioned - GPUs are crazy parallel, doing millions of computations at once, while CPUs can only really do small amount of tasks at once (but get individual tasks done faster). GPUs are designed this way because graphical rendering is a textbook example of a problem that can be very nicely solved by parallel computing. The second difference is speculative execution. Executing an instruction on a modern computer is a surprisingly complicated, multi-step process. Because each step is done by a different part of the processor, multiple instructions, each at different stage of execution, are being executed simultaneously. This is called the \"instruction pipeline\". You can think of it as an assembly line, where many products are being created simultaneously. Modern CPUs and GPUs both have long pipelines. For good performance, we want to keep the pipeline full, which is an easy task if the instructions are just a list we can sequentially execute, however, unfortunately, that is not the case, because most programs contain a LOT of branching. When we hit a branching instruction, we have to wait until it is fully executed before we can load the next instruction (because that's how branching instructions work - they tell us which instruction is next). Modern CPUs (but not GPUs!) try to make educated guesses based on past results and start executing instructions that are likely to be needed (this is speculative execution). If it turns out the guess was right, hurray! If it was wrong, it needs to do an undo, but if the predictions are good enough, it's a performance gain in the long run. Branch predictors are huge chunks of hardware, and by choosing to install one, you are leaving less space for the rest of the processor, sacrificing raw performance. For CPUs, this is worth it. For GPUs, it's not, because the computations they need to do usually consist of simple number-crunching without much conditional logic.",
"CPU is general purpose. It knows to do a lot of different stuff - math operations, logic operations, memory operations, jumping back and forth in the code, etc. GPU on the other hand knows how to do a smaller subset of operations (mostly math operations), but it can do them really quickly. GPU cores are a lot simpler than CPU cores, which means it can contain a lot of them - while a CPU normally has between 1 and 16 cores, a GPU can have hundreds or even thousands of cores, all of them making calculations at the same time.",
"CPU: an excavator that can dig a deep hole easily and quickly. GPU: an army of men with spoons on a field. Hope this helps. Dunno, maybe they should be given shovels.",
"Imagine that you're doing some shopping. You're waiting to purchase your groceries. One store has a CPU as a store clerk, and the other a GPU as a store clerk. & #x200B; The CPU store clerk is a super robot from the future who is inhumanly fast. It has 4 arms that simultaneously grab and scan your items, take your money, and bag your groceries before you can even blink. The only problem is that there is only two store clerks and its rush hour in a Costco before a big holiday. You wait 15 minutes to be served but your order takes 20 seconds to process and you leave for Best Buy. & #x200B; The GPU store clerk is a big fat lazy employee. The cash register is so old and slow that you're not even sure if it is digital. It looks like its the employees first or second day because they clearly don't know what they are doing and they don't even bag your groceries so you have to do it yourself. There was nobody waiting in the line before you, it takes 5 minutes to process your order. & #x200B; It took 3 times longer with the super robot. This is only because GPU store has more than two store clerks, in fact they have 2816 store clerks, even if they were all slow and lazy they are greater in number to a large degree. & #x200B;",
"A modern GPU might be capable of performing many of the functions a CPU handles but probably not. GPUs are designed to perform a few tasks very well and at a very large scale. CPUs on the other hand are designed to perform a variety of tasks reasonably well but not generally at a large scale. To use a metaphor, imagine a CPU is a pair of scissors and a GPU is a three-hole-punch. Both scissors and a three-hole-punch cut paper but they do it very differently and the three-hole-punch can really only cut small circles out of paper while a pair of scissors can be used to cut any shape. You could use a three-hole-punch to cut paper in other ways by making a series of punches but it would be very difficult and tedious, and there would be a lot of cuts that are impossible. On the other hand you could use a pair of scissors to cut just about every shape imaginable including little holes that a three-hole-punch would make however it wouldn't be very good at those. If you had to put 3 holes in 1000 sheets of paper, the three-hole-punch could do it in about 5 minutes where as you'd probably spend a week doing it with scissors. The same is true of rendering graphics, a GPU can draw all the pixels in a 1080p display 30-60 times a second where as a CPU would struggle to do even a few frames a second."
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agm1he | What is actually happening when you tick the 'I'm a human' box on a captcha? How does it know I'm not a bot? | Technology | explainlikeimfive | {
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"It uses a lot of information actually. First, it can detect your mouse movements as you go to click the button. If your mouse pointer immediately snaps to the button after the page is loaded then that doesn't seem much like a human. However, if you spend some time reading the page and slowly scroll down to eventually click on the button that is much more like a human. Additionally, it uses information about your browser. What page led you to the page that you are currently viewing? Are there other cookies on your machine that look like normal web browsing traffic? Is your IP address in a range of suspect ones? If the CAPTCHA is uncertain about whether you are a human it will give you a test by having you click on pictures. But, most of the time this is unnecessary. Is it possible to fool this system? Probably. But, it's a constant competition between the developers of the CAPTCHA and people who are trying to fool it.",
"Google won't say exactly how it figures it out for security reasons. However, they have said that it tracks the motion of your cursor and looks for \"human-like\" movement. A bot might move in a straight line to the button to click it, or even call some Javascript to click it without moving the mouse. Humans tend to wiggle around more. If it can't quite decide from your mouse movement whether you are human, it presents you with further challenges, like the photo ones where you have to pick all the squares that include traffic lights or something like that."
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agmpj9 | How does my iPhone X know where I’m parked? | It also knows where my house is, but I can understand that a little bit easier. It could just analyze where I go back to every day. But how the hell does it know how many feet away my car is, and on what street? It’s pretty rad, so I’m not complaining, it just strikes me as strange because I never “told” my phone I was parking. It adjusts daily based on where I choose to park too so it’s not like it’s just adjusting to trends over time. | Technology | explainlikeimfive | {
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"I believe it uses the accelerometer and gyroscope (and bluetooth if your car uses it, as well as CarPlay) to know you're driving. Then, when it detects you've stopped driving, it marks the GPS location as your parking spot. This is also how the Do Not Disturb while driving feature works.",
"I imagine it would be one of two things obviously both GPS but one would be simpler and that is if you connect your phone to the car and then remember where it was when you disconnected. the other one could be to do with speed similar to how Pokémon go changes the way it worked if your going to fast to be walking your driving and in Pokémon's case none appear because... Well your driving and in this case just remember where you were last time you was too fast to be walking. By the way these are just my opinion on what I think might be happening."
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agmtxx | What network did 70’s and 80’s car phones connect to? | How did car phones call people back in the day when there weren’t cell towers all over the place? What were they connecting to? I’ve heard there were car phones as far back as the 1960’s. How could they get on a network to call people that were on landlines? | Technology | explainlikeimfive | {
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"There were cell towers, there were just fewer of them and they weren't available in as many geographic areas. To make up for the sparse distribution of cell towers, old cell phones had far more powerful radio transmitters (about as powerful as CB radios) so that they could broadcast over a much farther range in order to connect with a tower.",
"The car phones started out as WWII radio sets. The army had made radios that could be hooked up to phone lines allowing a field unit talking on a radio to be patched through to head quarters for efficient communications. After the war this same technology were made available to civilians. Phone operators would get radios installed that they could patch through their plug board to connect with the rest of the phone system. People would then get radios installed in their cars similar to modern walkie talkies that they could use to communicate with the operators and then make outgoing phone calls. There were improvements to the system over time but it would still be recognizable to anyone working with standard VHF radios today."
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agnown | How does a spot vision screener work? | Technology | explainlikeimfive | {
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"I think you're referring to the \"autorefractor\". It shines infrared light into the eye (invisible, so the eye doesn't respond and close the iris) and measures the reflection off the back of the retina. From there, the device adjusts the lenses inside itself until the the reflection off the retina is \"clear\". This gives you a pretty good idea on where to start with regular vision testing. It's also the only way to test the vision of babies and young children who can't answer \"Which is better? 1 or 2? 1.....or.....2?\"."
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agpg16 | How is a person kept alive during a heart transplant, where the old heart is out, but the new heart isn’t in yet? | Technology | explainlikeimfive | {
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"Your heart is just a pump that moves blood around your body. Surgeons have a machine with a pump called a \"Heart Lung Bypass\" that they install to keep blood moving around while they work.",
"While the old heart is being removed the patient is connected to a heart-lung bypass machine which takes the job of your lungs and heart by artificially pumping blood and oxygen into your blood while the donor heart is put in. Then once it's attached they disconnect the machine and restart your new heart.",
"They use a machine to bypass the heart’s function. It’s kind of like having your life continue on outside of your body until the new heart is put in.",
"The patient gets connected to a robo-heart that pumps the blood for them. Once everything new is in place, they disconnect the robo-heart, connect the replacement one, and start everything up",
"The patient is connected to a cardiopulmonary bypass (CBP) machine. The CBP circuit consists of six major parts: 1. Venous cannula. Essentially big straws that your heart surgeon inserts into your vena cava (the large veins that return your body’s blood to the heart). Common sites include the superior vena cava, inferior vena cava, or right atrium. The surgeon may use one or two, and will select the location based on your individual anatomy, the operation to be performed, and his personal preferences. The venous cannula are connected to plastic tubing and blood just drains by gravity into the: 2. Venous reservoir. A big clear plastic bucket that collects blood. Nothing fancy. From there it goes to the: 3. Membrane oxygenator. Where the magic happens Here the blood passes through a porous material where carbon dioxide diffuses out and oxygen diffuses in. This is the point where the perfusionist (a highly trained technician running the CBP system) will add some anesthetic to keep you unconscious, and can also monitor and adjust the acidity of your blood. Basically old venous blood becomes fresh arterial blood! From here we go to the: 4. Pump! An impeller type device (big spinny thing) that pumps the blood. Fun fact! In case of a power failure, there is a manual hand pump. Backbreaking work! But literally keeping you alive! Pump speeds are adjusted to maintain blood pressure near normal conditions. The pump pumps the blood to the: 5. Filter. Filters out any clots that may have formed in the circuit. Your blood must be fully heparinized (prevented from clotting) before going onto bypass or you will clot off the circuit immediately and die. The filter prevents microscopic clots from entering your bloodstream and causing a stroke. Finally the blood exit the machine, goes back up via another set of plastic tubing to the: 6. Arterial cannula. Typically placed in the aorta right as it comes out of the heart, but in certain rare cases may also be in the femoral artery, abdominal aorta, or any big artery. Gets the blood to the brain and rest of the body. Once everything is setup and the patient is stable on the CBP circuit, the blood completely bypasses the heart and lungs. The lungs are deflated and collapsed, and the heart is an empty, stationary meat sack. Surgery can commence."
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agpnvr | How do some video games have a "Playable" state during the download? | How do some of the games ive downloaded have a playable state like 75% through the download yet it still has to download the rest? | Technology | explainlikeimfive | {
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"This is a little overly simplified, but gets the concept across. Let's say that you're playing a single-player game that's linear. The actual game engine is relatively small - most of your assets that take up a bunch of space are things like textures, music, video, and other files of that type. So for the first two hours of the game, you spend it in one area. That means that you only need the environment and character assets for things in that area (along with the game engine) and you can play that section. So it downloads all of the character models and music and other stuff it might need for that time, and while you're playing, it can download all of the other characters and music and textures.",
"I know in particular for World of Warcraft, they save the final 25% or so of downloads for stuff like HD textures and models, HD sound effects, etc. Large but ultimately inessential files. Also, check out this cool gif on how open world games are rendered: URL_0"
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agraji | How does my laptop detect when it's shut? | Basically the title; how does a laptop know to enter sleep when closed? | Technology | explainlikeimfive | {
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"This depends on the laptop. Macs use magnets and Hall effect sensors; some use a conductive latch. Some have a pressure switch near the hinge or on the outer edge.",
"There’s a switch connected to the lid closure hinge or latch. Basically, it detects it the same way your car knows to turn on the interior lights when a car door is opened."
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agrwyd | (Cellphones) What is blue light, what is the purpose of a blue light filter, and should certain media be viewed without a filter? | Technology | explainlikeimfive | {
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"Blue light is said to reduce melatonin (the sleepy drug) in the brain, so 'blue light filters' on screens actually reduce the amount of blue light being emitted so you can hopefully sleep easier.",
"The premise is that since blue is one of the spectrum of light we can see, we have a natural reaction to it, that reaction being wakefulness. This idea goes on to say that if you're looking at your phone and viewing that blue light you will have difficulty going to sleep because the blue light is encouraging you to be awake. Filtering this light is said to make it easier to fall asleep, and is recommended when using your phone in the evening. I have not seen the evidence verifying all these claims, and I would caution blindly following it because almost every single instance you see of it being shown is a product someone wants you to buy, and are thus biased. If you have problems sleeping then look into it, if not then maybe not."
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agrz7z | What causes significant explosions to produce the iconic mushroom shape cloud to form? | Technology | explainlikeimfive | {
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"The explosion creates a region of low density hot gas. This rises. Typically, given it is a big explosion, there's smoke/debris which are then pulled upwards with the smoke. The stem. Once the gas reaches an elevation where the air has the same density as itself, it stops ascending and spreads outwards, with the debris it contains. The cap.",
"Several of the answers here are saying that the mushroom top is formed when the rising hot air stops ascending and spreads out, so I wanted to say that's wrong. The mushroom top is also rising, it's made up of the initial bubble of hot air created by the explosion, flattened a bit and vortexing around the sides as it rises. Another thing I'll mention is that part of why the stem forms like that is because the explosion heats *the ground*, so that fresh air sucked into the vacuum caused by rising hot air will itself get heated by the ground, also rise, suck in fresh air from the sides, which also rises, and so forth until you get a nice column of rising air *beneath* the initial bubble. [These time series photos from a nuclear test show the mushroom head forming out of the initial fireball and rising as-is.]( URL_0 )",
"Watching videos of nuclear blasts, one can see that the initial fireball expands rapidly, and also rises upward, billowing out from its top and being sucked in at its bottom, a churning shape not unlike a smoke ring, which leaves a column of incandescent debris behind as it rises, and sometimes continues upward for quite a distance before it seems to slow down."
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agsc8g | Why do the advertisements before videos play perfectly fine while the actual video buffers/bad quality/refuses to play? | Technology | explainlikeimfive | {
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"The ads fit in a single buffer and are supplied from the ad server. Everyone gets the same 20 ads in an area, so the local server cache always has them loaded."
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agszqo | When you push your finger on a normal, non touchscreen computer screen, why does it make a bright and rainbow-ish color? | Technology | explainlikeimfive | {
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"You're deforming the panel and changing the thickness of the liquid crystal layer. That thickness is important to the panel operation.",
"These kinds of screens are LCD, or Liquid Crystal Display screens, which use a thin layer of crystals to filter light from a backlight. When you press on this, you move the crystals, compressing them, and allowing more light to pass through."
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agt81f | Why is to dangerous to connect to an insecure network and how would they access my information? | Technology | explainlikeimfive | {
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"Dangerous is an exaggeration, an insecure network means that anyone within range can see or manipulate your internet traffic. Depending on the type of traffic it may or may not be secured in other ways. For instance most websites use HTTPS and these would be fine. Other apps like e-mail may not be secured and completely readable. A secure wireless network in a coffee shop where everyone knows the password is basically the same as an insecure network. From a security stand point you are better off using an insecure wireless network to connect to an HTTPS website, then a secure one to connect to an HTTP website. tl;dr Security is a multi-faceted thing, and secure wireless networks are better than unsecured ones.",
"The default assumption for a network is for it to be unencrypted. To make an analogy to people talking, imagine you are talking to your friend, Alice, who is standing across the street. An insecure, unencrypted network is just equivalent to yelling the conversation at the top of your lungs. Anything you try to say to her will be picked up by other people standing nearby. Encryption is sort of like you and Alice came up with a secret code language, so that all the bystanders don't understand what you are talking about. In fact, there are usually multiple layers of encryption on our communications. For example, if Alice is actually just passing messages along to Billy and Cadence for us, we might decide that we aren't sure if we really trust Alice, so we might also come up with another layer of secret code languages to talk with each of them. In this case, it doesn't *really* matter if people snoop in on our conversation with Alice, but we like to have a secret code language to talk to Alice anyway, just in case our secret code language for Billy is really easy to figure out, or something like that.",
"Just Imagine you sending a Letter to someone else. The delivery guy is the Person of trust Here. If you send a unsecured letter he can open it, read anything inside, close it again without you noticing. But if you seal your letter you can check for the letters integrity and would notice if it get manipulated. But in a Standard scenario your delivery guy isn't the bad guy, normally it's someone who attacks him steals your letter and then masks himself as the real delivery guy. So never send unsealed letters or packages over the Internet."
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agwpe2 | Why do Netflix and Hulu use long, weird URL's for their shows and movies instead of something simple like " URL_0 "? | Technology | explainlikeimfive | {
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"They actually use a pretty simple URL. For example Brooklyn 99 is just URL_0 , and a specific episode for example is URL_1 . Whatever appears after the '?' is just metadata that Netflix adds to the URL for their own use. Why would they use a number and not a name? The name might not be unique (for example there are two TV shows named The Office - the UK and the US versions), so it's a lot easier to keep a numerical code. They also don't want users to try guessing the URLs - they much rather have users access the shows through the web interface.",
"Also note that simple URLs are common where search engine optimization is important, like news articles or product listings. Sites like hulu or netflix don't nearly rely as much on external traffic so there is no need to use the simple keywords.",
"As u/Schnutzel says - Netflix will have a *ton* of content that shares similar or identical names. It's far easier to use a catalogue numbering system (such as [ISBN]( URL_0 )) to keep track of individual titles. That way, Brooklyn 99 will always be [70281562], even if a completely different Brooklyn 99 is added to the catalogue at some point in the future.",
"They have no need for SEO. That's the only reason a name would be better than a number. So, they use the more precise and better URL. Why would they use a name? Who would that benefit?",
"Any time you're using a database you consider giving a unique identifier to any entry. It's mostly to allow easier management if something changes. It will allow a more standardised value (length and type etc)",
"The same reason as to why Youtube URLs are super complicated. There's a ton of content on both platforms, and some may have similar names, so numbers are used to differentiate."
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agxlwp | Why haven’t scientists been able to make humans immortal yet? | To clarify, I’m not having a dig at them. I’m just curious, what are the specific problems they need to overcome or solve? I suppose to a greater extent, I’m asking why life currently can’t be permanent? Thanks. | Technology | explainlikeimfive | {
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"Scientists have been able to make humans immortal. Sadly only at the cellular level, in the form of cancer, releasing toxins that causes the brain to stop functioning. Still, one of those cancers have been alive for the better part of a century on top of the lifetime of the person it's from, helped make vaccines for polio and figure out cloning, all sorts of stuff. So yeah, that's pretty much all that's stopping us. We need to not only find the cure for cancer, but a way to make cancer not be cancer and/or not happen in the first place despite doing stuff that should definitely cause cancer.",
"EDIT: Read /u/Eeros's post below mine. In order for humans to be immortal we would have to figure out how to keep our cells dividing and replacing old cells in a healthy way. Most cells have a built-in limit to how much they can divide before they permanently die. Right now we kind of understand this system and have very basic ways to affect that. However, if you remove a cell's built-in mechanism for self-control in reproduction you run a much higher risk of cancer. Cancer is what happens when a cell reproduces too much with no control."
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agxted | What is actually involved in the process of "hacking" into something, and how is it different to that poorly portrayed in movies? | Technology | explainlikeimfive | {
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"98% of the time it means tricking somebody into giving you their password. 2% of the time it means writing software that tricks a computer into giving you information you shouldn't have. 0% of the time it means doing that in real time by furiously typing in green text on a black background.",
"Hacking isn't some repeatable process like fixing a flat tire on your car. It's a creative process where your looking for flaws in the designs of systems. You can kind of think of about it like trying to sneak into someones place of residence. At first it's easy you can just go through a window and take stuff, then they put bars, so you pick the lock, then they get say sentries, so you climb down the chimney. Then they build a castle, so you build a battering ram, then they build a moat, etc... The exploiting of flaws or limitations is maybe the only common thread but technical they can be flaws at any level, that give you an in. Some different kinds of examples: 1. Flaws in the application allow you to send tricky text to the application that breaks it. For instance some simple websites can be hacked by putting a password as something like \\[' OR 1=1\\] without brackets. This is SQL injection. 2. Flaws in programs that the system depends on. For instance most applications don't write there own encryption software, they use libraries. A few years ago a common library had a problem where you could get the encryption keys from it by sending specific requests. There is a fairly accurate depiction of [what the problem was on xkcd]( URL_0 ). 3. Flaws in the underlying hardware that the software runs on. Modern computers / operating systems allow you to run multiple programs at the same time on the same computer. This is true both on your desktop and the servers you communicate with. Each program shouldn't be able to see or manipulate what other programs are doing. This is suppose to be enforced by the CPU, but recent vulnerabilities such as SPECTRE and MELTDOWN mean that certain things the CPU does to make your computer faster means you can steal other processes data. Another example called ROWHAMMER was a flaw in the way system memory was designed. You could write a program that wrote certain things to memory you could cause electrical interference in a predictable way and change other programs in memory. 4. Flaws in how systems communicate with each other. If a large company has multiple data centers they need to send data between them. About five years ago, there was reports that the NSA was intercepting the traffic and listening in on these connections because while private circuits, they were not properly encrypted. Another example is that at a coffee shop, someone can setup a WiFi connection that looks like the coffee shops, and then act as a man in the middle for all your traffic. If you send an e-mail to transfer money to greg, I can change that e-mail to say transfer it to myself, without you noticing. When the e-mail comes back to confirm, I can intercept it and change it back so you don't notice a problem. This is a man in the middle attack. So all in all, hacking and security is very much a giant arms race with many fronts and many tactics. It doesn't just fit in a box. Each time one side finds either a new solution, either a new attack or defense, the other side has an incentive to beat it and up there game. It's a wondrous time to be alive.",
"Hacking is just the process of getting access to parts of a computer system that you're not supposed to have access to. This is done by exploiting security vulnerabilities. Even the best written software will have bugs in it and some of these bugs will have the effect of giving someone access to things they aren't supposed to have. The biggest bug is the user. If they can be tricked into giving someone else access then there's no need for fancy software.",
"Could be a lot of things, like meticulously watching for certain packets or patterns of packets (information, essentially) to cross a connection. Could be brute forcing a password (having software methodically try every possible password - this is the idea behind minimum password lengths, to make it take exponentially longer with each additional character, as well as requirements for capitals and special characters, to increase the exponent part of how exponentially longer it takes). Could be legally or illegally gaining physical access to a place in order to find sticky notes with passwords conveniently just written down because the password requirements were too ridiculous for humans to track and you realize that better than their Network admins do. Could be leaving USB flashdrives places where they'll be found, plugged in, and will run tools that compromise that machine from the inside out. Could be just calling someone and asking for their password on the false ascertain you need it for what sounds to them like a legitimate reason. Like the other guy said, it's never furiously typing away at a keyboard on real time - that's called being unprepared."
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agxz2j | How did Google create all the 3d objects in Google Earth? | Technology | explainlikeimfive | {
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"They use a technique called [photogammetry]( URL_0 ) with photos from aircraft. It takes multiple photos from different viewpoints, identifies points of common features (such as the corner of a building), and knowing the camera position and direction when the photos were taken, algorithms can determine where in 3D space where the point is. It's the same thing our brains do with our own eyes."
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ah15b5 | Why is it a bad thing if companies and apps collect my data? | It seems like everyone is warning you about apps that collect much data if you use them. But to me the “worst“ thing that could happen is that I get customized ads (which I think is a cool thing). What's the big deal if you ain't got anything to hide? I'm living in Germany and I'm wondering if this is a typical german problem. | Technology | explainlikeimfive | {
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"> What's the big deal if you ain't got anything to hide? Your phone knows where it is every second of the day. It knows when you're driving, when you're working, when you're sleeping, etc. It knows when you're goofing off instead of working, and if you have a voice assistant turned on it listens to everything that is happening around it all the time. If you're fine with a full 24 hour record of your life being sold to anyone who can pay, then it isn't a problem.",
"What do you mean nothing to hide? Could you give me your passwords then? How about all messages you ever sent to anyone? Maybe your photos as well and credit carf number. You have lots of things to hide. Also you might have seen lots of news about big data leaks. You can't really know if the company actually protects the data well, or anonymize it enough.",
"I can't speak for Germany, but in the United States, we have a right to privacy, and the appropriation and use of personal information is an abuse or outright violation of that right. You have a lot more to hide than you give yourself credit for. A couple facts about you might be harmless, but en masse, a detailed profile can put you at real social, legal, or physical harm. History has demonstrated, time and again, that people with this sort of power will ultimately abuse it. People are being harassed for personal, religious, or political beliefs. In some countries, like China, thought crime is a thing. Even in the US, we've had the Red Scare, which wasn't that long ago, where people were brought before government tribunals for their political views. People lose their jobs, get kicked out of school, or ostracized from their societies. Kids these days take revealing pictures of themselves, and leaks happen, or the recipients just dump this stuff on the internet, which never forgets. That's an embarrassment no one wants to be remembered for FOREVER. You want a potential employer searching you and the first thing that comes up is the worst thing about you? There was a recent scandal that a comedian said something a decade ago, and he's being held accountable for it now, like it just happened. This is very common, that digital history does not age, is not forgotten, and forever relevant. You can never move on. You have a lot to hide. You can request a copy of everything Google knows about you, and as one US senator said of her request, she found Google knew her \"deepest, darkest secrets.\" Utterly terrifying. You are being abused as we speak, and the problem is so systemic it's difficult to even comprehend just how bad it is. You are a product - to many people. People are getting very rich selling you like a head of cattle. There are so many opportunities you've lost out on and you'll never even know. Insurance for you may be higher because they know something about you that you may not know they know; ever do a genetic test? Great, you know something vague about your genealogy, but now someone knows what genetic conditions you're predisposed to that even you don't know. How many jobs have you been declined because of this misappropriation of information? How many benefits have you been denied? Etc... What you can do is get political and assert a right to privacy, a right to not be traced, tracked, aggregated, sold, or found. A right to be forgotten. Demand oversight and consequences. Demand transparency. Demand a cut! If people are going to sell you like a whore, you'd think you deserve a little something for making them richer. The other things you can do is opt out of data aggregators, not use \"free\" software that exist purely to extract information, and not use social media - largely regarded as mentally toxic anyway, and exist as data aggregators. You're not even American and our government probably has an astoundingly detailed profile on you because of Facebook alone. Our government is a big consumer of aggregated data about people, since people world-wide use these international services without a single thought.",
"One thing that no one has mentioned is that these companies are turning around and selling that information. So not only are they completely invading your privacy, theyre making money for it. Are they giving you a cut?",
"If you don't mind your life being prodded and mined for statistical data, being socially engineered or just them knowing every preference you have for everything and anything (and I mean anything), then it is really no big deal.",
"The worst would probably be someone at the company deciding that monetizing data wasn't valuable enough, and they threaten you with releasing your location and/or browser history to the people you regularly interact with unless you subscribe to their new, expensive \"data protection plan\"."
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ah1ql5 | How does a USB or another small storage device keep so much data on it? | Technology | explainlikeimfive | {
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"**First things first - Binary** So we know electronics run on electricity (we need to plug them in or give them batteries, after all, and it's in the name). If you compare electricity to water flowing through a pipe, voltage is like the water's pressure and current is like the flow rate (how much water is moving through the pipe). Obviously that can't represent something as complex as text or photos or music, so we'll make some kind of code. If you had water coming out of your faucet, and I wanted to send you a message by varying the pressure and volume, it'd be pretty difficult for you to tell the difference between small changes right? Also what if there was a problem with the water supply from the city and we lost a little bit of pressure? We wouldn't be able to get to our full range. But if I said, \"Faucet On = 1\" and \"Faucet Off = 0\", you'd be able to tell pretty easily if water is flowing or not. We could then make patterns, and say 010100 = the letter A, or 101100111 = the color blue. & #x200B; **Storage** Ok so we have our code and I'm going to send 3 messages with the faucet and tell you to write them down. In this situation I'm like the PC and you're the USB stick, and our messages are files. Also, you know I'm going to ask you later what I told you to write down, so you'll probably want a way to organize the information I'm giving you so you can read it back to me exactly. & #x200B; So you take your sheet of paper and you draw a grid, like graph paper. You put a small number on each cell, 1, 2, 3, 4. As I turn the water on and off, you mark a 1 in the first grid cell, a 0 in the next, so on and so forth. When I'm done with the first message you make a note that we ended on cell 56, then continue on to the next one and so on. When I ask you for file #2, you look at your notes and jump to cell 57, and read me back the 1's and 0s' & #x200B; **Flash Memory** USB sticks use something called flash memory, it's a chip made from silicone that represents our sheet of paper with the grid lines. Each grid cell can either be filled with a small amount of electricity or not. Flash memory was kind of revolutionary because we don't need a battery or power source to keep that electricity in the cell, that's why you can unplug your usb stick and it's fine, it just holds all of the electrons in place. Using the water analogy, it'd be like if each cell was a small cup and you put a lid on each one that had water. & #x200B; **Size** If you want to store more information in our first scenario, you can either get more pieces of paper, but that will get heavy pretty quickly. So you decide to just draw you grid lines smaller and smaller to fit more cells onto the same sheet. Eventually you probably can't draw lines any closer together, your pen is just too thick, so you need a smaller pen. We've improve this process for computers over the years and can now \"draw\" these grid lines on the silicone chip RIDICULOUSLY small. We're talking **nanometers**. For perspective, if a nanometer is an inch, the width of a human hair is a mile. We do this with super fancy equiptment and processes to pack a tonnnne of those little cells in there.",
"there isn't any kind of special answer to this. Data is stored in binary format. Inside the chip are tiny \"floating gates\". These tiny gates can hold an electrical charge. They can be flipped on or off, for ones and zeros. The reason we can pack so much data into USB chip is because we can make these gates very very small. I think its interesting, that we are still not even close to the data storage of DNA. DNA stores almost a gigabyte in an area smaller then the tip of a pencil."
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ah2wkl | How does ejecting a storage device or disconnecting an electronic while it is in use cause damage to the data/equipment? | Technology | explainlikeimfive | {
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"Your computer tries to appear \"fast\" to you. You click the \"save\" button, and Windows says \"Ok\" right away, but in fact it may take a few seconds to actually put the data on the storage device. The actual writing of the data on the storage device is sometimes delayed until the next available \"opportunity\" to write, when the device isn't busy and Windows isn't busy. So if you click \"save\" and unplug the flash drive right away, the actual file MAY be half-saved, which would corrupt it. Most of the time you can unplug the flash drive right away, nothing much happens, but SOMETIMES Windows is busy and only pretends to save, and doesn't actually save right away.",
"There's no guarantee that it can or will cause damage, but there's no promise it won't. It's the \"contractual agreement\" of the USB protocol. If you violate that agreement, all bets are off. The most sensitive to sudden removal is a storage device mid-write. Typically your storage device is an SSD, which has to wipe an entire block before it's written to. A sudden power loss can damage that whole block, and consequently lose the data that was supposed to be there. If this happens to a critical block, the device may no longer know how to identify itself to the computer - effectively bricking the device. You need advanced software tools to go back in there and manually set those critical values (speaking from experience rescuing a thumb drive), and it's a huge pain in the ass, if it's even possible, because the damage could interrupt the initial handshake between that device and the computer, so your computer doesn't even recognize a drive is plugged into it in the first place. Also, as per USB, the computer is under no obligation to write any data to the device until you unmount it. This is for performance - the computer will cache all reads and writes locally, so it's very fast, and write once on dismount, which also reduces write-wear on the device. If you just yank it out, you didn't save any data and that local cache is disregarded. I think at this point the major operating systems don't do that, but there's no guarantee."
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ah3enz | Why are disks the best format for playing video games on consoles or PC's? | Why were cartridges phased out and/or why aren't things like flash drives acceptable for large games? | Technology | explainlikeimfive | {
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"text": [
"IIRC its cost. Disks are much cheaper than cartridges, so if a company can use them they likely will.",
"Back in the 90s cartridges lost out because they just couldn't store anywhere near the same amount of data and were more expensive. N64 carts topped out at 64MB, but a PS1 CD could store 650MB, and a fraction of the cost to produce. CDs had their downsides (load times), but that extra space allowed developers to do so much more. It's the main reason Final Fantasy ditched Nintendo for Sony. These days flash based cartridges can exceed the capacity of a Blu-ray no problem. But the cost is still an issue, a Blu-ray disc is a *lot* cheaper to produce than something like an SD card. So cartridges are feasible if there's a good reason to use one, such as for a portable console like the Switch. But otherwise it just makes more sense to use discs. Or maybe even just make it download only."
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ah44jo | Why does bluetooth have a delay when switching songs but turning off bluetooth instantly stops the music? | Technology | explainlikeimfive | {
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"When you transmit audio via bluetooth, there's a small time lag that your bluetooth device buffers. So whatever you're hearing at the moment is being pulled from local memory on your headphones - and that local memory is being filled at the other end from the received wireless transmissions. When you start a new song, you need to fill that buffer first. However, when you turn off the music, there's no lag on the controls so you shut off the headphones immediately."
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ah4epn | Does streaming a YouTube video use the same amount of data regardless of whether it’s actually a moving image? For example, sometimes I just listen to a piece of music and the “video” is just a picture of the album cover. Does this use less data because it’s not a moving image? | And as a related follow up question - if I watch a video and then use the slider to return to the beginning and watch again, do I use twice the data? Or do you only use the data the first time and then you can repeat it as many times as you want? | Technology | explainlikeimfive | {
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"Oh man I hope I can explain well enough. Music with just an album cover image should use less data if it's a static image. Less refresh and painting of images on screen means less data is needed. Rewatching/listening to it immediately could potentially save a little data if it's cached and rewound in the browser window but if you refresh the page to reload it, it might use more data, but I'm not sure how YouTube handles that content in either instance. On a lot of YouTube apps, there's an option for \"Stats for nerds\" and it'll show you you real-time bandwidth usage.",
"YouTube uses a variable bit rate like many streaming video codes which means a static image reduces the amount of data for the video portion of the stream. I believe the audio bit rate is tied to a fraction of the video though, so a higher resolution static image means a larger bit rate range is available and the audio will be higher quality.",
"I'll try and paint a real-life example for you. If someone moves, I have to process that movement, and if they keep moving, I have to continue processing that movement (where they go, how fast, etc.) That takes up brain power. However, if someone isn't moving, I can just remember they aren't moving and not process their movement until they start moving again. Essentially, in the simplest terms, that's video compression. Modern videos use compression to smartly decide when they actually need to change the picture and when they don't. Therefore, you don't use more data when it's a still image (as there is a inherently less data from no change). As for your second question, you don't use twice the data. Have you ever noticed how the video bar has three colors: red, grey, and darker gray? Well we know that red shows the progress of viewing our video, but the lighter grey shows how much of the video your computer personally has. When YouTube sends the video to you via the internet, your computer, phone, etc. keeps it on hand for a bit just for the exact reason of scrubbing backwards in a video."
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ah51lh | Up until torrent came along, there was constant innovation in the P2P arena. Why has it stopped since? | Technology | explainlikeimfive | {
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"It hasn't BitTorrent is the king protocol in P2P because no one has come up with something better yet. But there's been a lot of development that leverages BitTorrent to do other things. Kodi and streaming via BitTorrent for instance. There's also been tons of development in the Streaming industry, which has really taken a bite out of P2P because Netflix is cheap, legal, and easy to use. More so than even downloading torrents, despite the limited catalogue. A lot of development related to P2P these days is related to privacy and obfuscation like VPNs. VPNs are being used to hide your identity, but also to mask your location for the purposes of getting around geo-blocking content.",
"If innovation were truly constant wouldn’t it cease to be innovative?"
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ah7jx9 | How do electronics measure the amount of electricity left stored in the battery? | Technology | explainlikeimfive | {
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"text": [
"A lot of it is sophisticated, depending upon the battery...but for simple designs (such as lead acid car batteries) it is entirely based upon voltage. They are nominal 12 volts. Full charged they are actually a bit overcharged and about 14 volts. Once they start dropping down to 9-10 they are starting to get unlikely to turn your car over. If you look at current capacity vs. voltage the top end charge (12.6+ volts) drops quickly, it's not main energy storage. Then it holds pretty steady and slowly drops until you hit the point where storage is expended and voltage drops massively. Just dives off. That's why you can have a battery die, wait 1 minute, and try to restart it and the battery seems to have some life. The software behind the percentage tracks the high/low/dropoff and gives you a percentage based upon those analytics."
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ah7tlu | how do people do a freedom of information request for secret documents that are unknown to the public before the request? | Technology | explainlikeimfive | {
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"Generally, they have some idea that the documentation should exist. So, say, if a reporter was doing a story on a polluted \"superfund\" site, he might submit a FOIA request to the EPA for files relating to that site. Obviously, if you already had more details, you'll narrow down your results a bit (ex: the reporter knew that the EPA contracted with Acme Co. to clean up the property, he might say that he wanted files relating to that contract). Most FOIA requests aren't for anything secret - people file pretty mundane requests all the time. Here is an article that might interest you: URL_0",
"Usually it's a fishing trip that gets lucky. Ask for general documentation about \\[topic\\], and see if there's anything interesting in the stuff you get back. & #x200B; If you've got a real hunch, or some specific knowledge, then you can start narrowing it down to zero in on the hidden stuff you think ought to be there."
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"https://www.cjr.org/analysis/foia-request-how-to-study.php"
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ah8zju | Why does Alexa respond to me saying a word that sounds similar to Alexa, but does not respond to any commercial that uses “Alexa” in its commercial? | Technology | explainlikeimfive | {
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"text": [
"Amazon [mutes certain frequency ranges to prevent Alexa from responding to its own commercials]( URL_0 ). For third-party ads, like [this one]( URL_1 ), they pretty much need to blacklist certain audio clips.",
"Originally it did have this problem. They have created a special tone that they play on the commercials that makes it not listen.",
"Commericals, at least official ones, edit the audio to (for the most part) alleviate the risk. Unfortunately, Alexa is so popular that it is featured in TV and movies, which does NOT often (if ever) do a good job of obscuring the command. While my Echos don't generally understand the rest of what is asked, the wake up word gets triggered often, followed by a jarring \"sorry I didn't get that\". Did you hear about the little girl who got Alexa to order a crazy expensive doll house by asking for it, and then the dozens of news shows that said, on air, what she said to trigger it? A lot of pissed off people that day."
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"https://www.theverge.com/2018/2/2/16965484/amazon-alexa-super-bowl-ad-activate-frequency-commercial-echo",
"https://www.nytimes.com/2017/04/12/business/burger-king-tv-ad-google-home.html"
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ah9zaq | Why is is so hard for goverments/groups to shut down The Pirate Bay completely while they managed to shutdown KickAssTorrents in 1 hit completely? | Technology | explainlikeimfive | {
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"Imagine a bully at school. It's the same one each day, taking the lunch money of the same handful of kids. You take note that kids seem bullied, and it's very easy to identify who the bully is, after all you only have to talk to a handful of kids to get something of note, plus everyone is pointing the same direction. You do something about it. Now you shut down KickAssTorrents. But imagine that you have a school, a very very large school, and there's *hundreds* of bullies. They're all called Marc. So every time you get someone to tell you who bullies them, it's 'Marc'. They also all look very similar, so you never know who did it today. You never know who is actually to blame. Worse yet, some of these Marcs live in other states, and due to bureaucracy you can't even get a hold of their parents! And every time you finally shut someone down, a new Marc transfers over to your school! :o That... is basically Pirate Bay.",
"The owner of KickAss's name got leaked, he was then arrested and forced to take the site down.",
"because the piratebay is managed in an much more decentralized fashion. take down the person behind the site, and you take down the site. if there isn't an single person behind the site but an group that suddenly becomes insanely hard.",
"piratebay has infinite alter egos. its hard to shut down all of them. on a side note, kat's owner got arrested and it got shut down.",
"TPB doesn't host any of the content it serves, not even the .torrent files, so the whole site can be packaged down to a reasonable sized .zip file and redeployed on a new host under new domain whenever the old one gets shut down. Therefore I don't think they even try very hard.",
"The big thing is that they actually found the owner of KAT. But TPB also is set up in a way that they can bounce back very quickly after being shut down, because they have duplicate servers in several countries. Since these sites don't actually host the content, they don't need to be massive servers. It's very easy to copy the website and put it up in a different datacenter if they ever have to move.",
"What do you mean? KAT is alive and well :)",
"Does anyone else think we should be allowed to freely share information over the internet as we please? The freedom in being able to share even copyrighted information is much more valuable to me than the potential customers lost to corporation's. I belive people that are able to afford the services, games and software that they want to make use of will for the most part buy these from legal channels. When I was younger and could not afford games I would pirate them. If I was not able to do this, I would have not been able to experience anything gaming related growing up. Today even with the knowledge and ability to pirate software as safely as possible, I choose to buy my games and other software as now I am able to afford them. A computer is essentially a device capable of reproducing information as put together by hand manufacturers to reproduce a copy of what they have built. In the future if people own 3D printers capable of producing electronics, cars etc provided the necessary materials are present. I would want people to be free to use their machines to produce cars, electronics, all of which could be exact copies as manufactured by corporations. I see a future in which information, and the right to use it will be open and accessible to everyone living in our societies.",
"can anyone tell me what happened to URL_0 ? that used to be my Google for torrents. 1 search for all the sites but no actual torrent downloads from them. then it was gone",
"I believe that we don't have the right to piracy, but I do believe we have the right to privacy that enables us to pirate. It's a tough ethical question of our time."
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ahb42q | What does having an extra exhaust pipe (2 in total) do for a car’s performance? | Technology | explainlikeimfive | {
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"text": [
"In most modern cars, engines come in what is called either an \"inline\" package or a \"v\" package, and this has to do with how many banks of cylinders there are, one bank or two. Each cylinder is going to have an intake and exhaust port, which lets fuel and air (the \"charge\") in and the exhaust gasses out. These exhaust ports are plumbed together, each their own pipe into a single pipe, by what is called a \"header\". This piece of exhaust plumbing is a single piece that bolts up against the engine along the exhaust ports. You need one per bank. That means an inline engine package is going to have one header, and a v package is going to have 2. Now, for the inline package, it makes the most sense to continue piping this one exhaust line past the O2 sensor, part of the feedback loop that tells the computer how much fuel to add to the charge, past the catalytic converter, that uses a honey comb of platinum to convert some of the smog producing oxides into carbon dioxide and water when it gets hot and these gasses come into contact, through the muffler, because if you think your tiny little lawn mower engine is loud... and out the back, away from the passengers and windows so exhaust gasses can't accidentally vent back into the car. The only reason you'd see two tail pipes in this arrangement is for aesthetics. A v package has the same need x2, so it would make sense to see two tailpipes. But of course, it's not that simple. For low end, economically priced vehicles, the two headers would be combined into a single line out the back - this saves on material cost. This configuration is called a \"Y pipe\". Enter \"exhaust scavenging\". You see, when that exhaust port opens and the piston pushes the exhaust gasses out, those gasses are still at ~100 psi, and they travel down the pipe as a pulse. Behind the pulse, the gasses actually pull a little, tiny vacuum. THIS IS A PHENOMENAL THING, because once that pulse gets past the header, that vacuum will actually help clear the next cylinder that exhausts in that bank, because that tiny vacuum will help to pull the next pulse out. This means the cylinder is clearer of exhaust gasses than if the piston just squeezed it all out, meaning that cylinder has more volume available for the next cycle. It's all about fuel and thermal efficiency. And this applies to our inline package as well as the banks of the v package. But hey! If we can scavenge the other cylinders of our own bank, why can't we scavenge the cylinders of the other bank, too? Enter the \"H pipe\" and the \"X pipe\". The H pipe is two exhaust lines with a pipe that comes across and connects them. This improves scavenging and thus efficiency. It's an older design, but it is still common to see because it's most efficient at low RPM, which helps with your engine producing torque at low RPM, and that's important because most of your driving experience is at low RPM. The X pipe is two exhaust lines where they cut into the tubing about half way and welded the two lines together. The lines effectively become one and then split again, as opposed to the H pipe which is more like a bridge. This also has a scavenging effect, but at higher RPM, which makes it popular on sports cars. You can also buy aftermarket scavenging exhaust systems tuned for whatever you would like. Efficiency increases the closer to the headers the cross connection gets, but there are transmissions and driveshafts in the way, and that needs to be taken into account. And the diameter of the pipe is important, too - a large diameter pipe makes for big, slow pulses of gas, which isn't good for scavenging, whereas small diameter pipes make for small, but long, fast pulses, which increases scavenging efficiency, but there is a bottom end to that where there is too much gas and not enough room. Supercharged and turbocharged engines are dealing with so much volume of charge gasses and exhaust gasses that scavenging goes right out the door - just bolt on the biggest pipes you can afford, scavenging isn't going to help you here. This is why diesels have gigantic, straight pipes - they're all turbocharged these days. And in the end, you'll see H pipes and Y pipes and whatever you call those single pipes from inline packages come to the end of the exhaust. A lot of aesthetics are applied here. I've seen H pipes feed into a single muffler, and that single muffler exit two pipes. There's no need for that but for looks. I've seen a single pipe split into a Y after the muffler so it can exit out two pipes. And it's actually very common that cars will have a fake exhaust tip.",
"On normal cars with small engines, nothing except the look. The reason you'd NEED it on bigger sized engines is because they take in more air, use it to combust the fuel then they need to expell the air and pressure from the explosion. If the air isn't exhausted out fast enough then you restrict the efficiency of the engine and so the power is lower than what it could be",
"Nothing at all for four cylinder or less engines unless extremely poorly made. For more cylinders than that there would be a marginal gain in performance entirely offset by the added weight. Mind you, I still have two exhaust pipes just because I like how it looks."
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ahbbml | Why do some pictures taken on my phone take up more storage space than others? | Technology | explainlikeimfive | {
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"text": [
"The phone is compressing the data to help save space, but some images are more compressable than others. Lets say you accidentally take a picture of the inside of your pocket. It's a 1000x1000 pixel image, and they're all black. Instead of saving \"black pixel\" one million times, you can save this image as \"black x 1,000,000\" and save a whole lot of space. Images with a lot of colors and details are hard to compress and will take up more space than images with few details that can get heavy compression."
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ahd3qq | Cinema aspect ratios | I understood the original need to switch from 4:3 to 16:9 to give that cinematic feel that you are watching this through a human-like field of view. But now that 16:9 is pretty much standard on HD Display's, the industry seems to keep going *wider.* Is there an actual reason for this? Or is it an arbitrary artistic choice? No matter if you are buying the latest and greatest HDTV, you can't escape those darn black bars... | Technology | explainlikeimfive | {
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"Movies have (almost) always been filmed in more (larger) widescreen formats, of which there are a variety, such as 1.85:1, 2.35:1, and 2.39:1. The person making the movie will decide what aspect ratio to film it in, for both aesthetic purposes, and their equipment. You could probably have a crazy field day of arguments discussing with people who make movies exactly what aspect ratio they prefer and why. TV, meaning HDTV, is filmed in 16:9 (aka 1.77:1). As you can see, these aren't the same. Which means most movies will need to be fit to a different aspect ratio when shown on a TV. Occasionally, you will see a TV show (generally a high drama) that may play with their aspect ratio in some scenes to give it a more cinematic feel and quality. The impact of this is debatable. The movie industry isn't going wider--its always been wider. Now your next question will be \"well why aren't HDTV's made in these bigger aspect ratios?\" ... well thats a really complicated question, and in short, 16:9 became a good compromise aspect ratio that was agreed upon, and it was decided this was going to be the HDTV standards, and for movies, they would continue to use black bars and such to adjust the aspect ratio",
"16:9 is the gemoetric mean of 4:3 (1.33:1) and 2.35:1. 4:3 (1.33:1) was the standard of TV and 2.35:1 was the most common movie aspect ratio.That mean that 16:9 is the aspect ratio where when you need to show both you get the least amount of unused screen on top or on the sides. Development of new higher resolution/better TV standard have happen almost all the time since the first TV was broadcastst back in the 1930s. In the 1980 16:9 was suggested for the reasons described above before that 5:3 was the main candidate. There was limited deployment of analog HD TV system back then but no one was that common. When it was clear the digital tv would solve part of the problem of HDTV it was 16:9 that was choose. So in the 1990 widescreen analog PAL t in 16:9 started to be common on the market, It was not HD the same signal but the stretched out to 16:9. The HD standards that followed used the same aspect ration. It was also the only standard widescreen resolution that DVD supported. So the aspect ratio was to minimize black bars both for movies and 4:3 tv that was common when widescreen was introduced."
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ahdayc | What is the highest possible resolution of an image? | Technology | explainlikeimfive | {
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"There are multiple definitions of resolution. Pixel count is just one. Subatomic particles can't be imaged with visible light because they are smaller than the wavelengths of light. Even so , the smallest thing you could photograph is a measure of how much magnification your lens has, not the image resolution.",
"Hypothetically, the smallest meaningful distance in the universe is the Planck length. This is 0.000000000000000000000000000000001616229 centimeters long. This would, ultimately, be the smallest element you could capture. Multiply that by however large your picture is.",
"The fundamental limit to resolution comes from the uncertainty principle and is proportional to the wavelength of light, though currently diffraction usually comes into play first. Diffraction is proportional to the wavelength of light but inversely proportional to the aperture size (how big of a hole there is letting light through), meaning a camera with a large aperture can capture more detail than one with a small aperture. This assumes that the optics are good enough to reach that limit, and that the sensor has enough pixels per unit area to actually record data up to the limit. You can see diffraction effects on DSLRs if you bump the f-stop up past around f/20 (which is a small opening), but even very expensive cameras aren't currently able to reach the diffraction limit with a large aperture.",
"A single .jpg image is limited to a resolution of 65535x65535. Pngs are capable of being around 4 billion pixels either dimension. Of course, this is only accounting for a single image, you could easily write a program to stitch multiple images together, in which case it becomes a question of storage. I'd say, a lot",
"Easy, it's the square root of the largest file size allowed by your operating system. Assuming no data compression, of course. Whether you're allowed to make the smaller file or not isn't the point, it's whether you can load it into memory. Which could theoretically be subverted if you only display a portion of the image at a time. Similar to how Legend of Zelda had that huge overworld but only showed the part you currently were at."
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ahg4nz | How can search engines query search results in just a matter of seconds from all over the internet? | Technology | explainlikeimfive | {
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"text": [
"Search engines use bots that constantly crawl web pages all over the Internet for content and keywords. This creates an index which is much smaller in size than the web pages themselves. What the search engine is actually searching is the index these crawler bots created this is quick because the engine and the index are closely connected. The engine will then provide you links to web pages it found where the content matches what you searched for.",
"It doesn't. The search engine has already searched the internet and just needs to search for the words you are looking for in its database. It does this with an index, which is a way to structure the possible search terms so that it is super fast to find. Once it finds the word, it will already have connected that word with a list of sites that match. To give an idea, a B-Tree, one algorithm for creating an index in a databse, will only take ln(n) longer to search for something when the index is n times larger. This means it will only take, on average, ~33 times longer to search an index of 10,000,000,000 words than it would to search an index of 2 words, or only 10 times longer than an index with only 10 words. Even once you take into account the extra work it takes to turn your search query into a result, this gives an idea of why results can be provided so quickly. Especially if you are Google or Microsoft who spend billions of dollars on computer servers and engineers finding ways to cut that search time down to as short as possible. Edit: ln(10,000,000,000) / ln(2) = ~33, not 23."
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ahj4lt | Why is there no TV equivalent to pirate radio? | Technology | explainlikeimfive | {
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"text": [
"Here’s a pretty good example from decades ago. (Not a true “pirate TV station”, but an impressive feat for its time. URL_0",
"There have been, just not as long lasting nor easy to create. According to Wikipedia, it wasn’t until early 2000s that the equipment became easily available: “Pirate Television stations are not as abundant in the United States or UK as pirate radio stations are. Only since 2004 has the technology for pirate television stations become easier to obtain and construct, due to advances in technologies and the availability of equipment.” Have a read up on the Wikipedia example, it has some nice examples."
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"https://en.m.wikipedia.org/wiki/Max_Headroom_broadcast_signal_intrusion"
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ahjbj4 | How do they generate unique MAC addresses? | How do companies that make computer components generate unique MAC addresses? How do they make sure no other company is making a component with the same MAC address somewhere across the world? | Technology | explainlikeimfive | {
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"eef23bq",
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"text": [
"The first six characters of a MAC address are assigned to a manufacturer. Allocation is controlled by IEEE. After that it's up to the manufacturer to make sure they don't make duplicate devices. In case you are curious: URL_0",
"Sometimes there are duplicate MACs. As long as they are on different LANs there isn't a problem, so sometimes they distribute to different countries or very different parts of the US, but big corporations could buy both in a big order."
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ahk7zz | Why did early color TV programming look so artificial like the color was added in later? | URL_1 This is from the early 1960s and President Kennedy's skin color looked unnatural, as everyone else's. To me, the quality is like early 1900s colorized pictures from National Geographic that was added later by hand. Most of the JFK footage is black and white and there are some color films but they still look off URL_0 | Technology | explainlikeimfive | {
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"text": [
"Film ages, and with age, fades. I see it when I look at old still pictures of family from those days."
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ahlxwn | How much computing power do we need to simulate a brain? | Why was a Pentium not enough? Now we have computer clusters like the supercomputer to compute and it is still not enough? How can i imagine the computing power needed for simulating our brain? | Technology | explainlikeimfive | {
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"text": [
"The answer is that we simply don't know. We don't know how much computing power the human brain has to begin with. Then, we would certainly need orders of magnitude more power than that in order to inefficiently simulate the brain.",
"A human brain is made up of ~100 billion neurons that all operate in parallell all the time. Each neuron have on average 7,000 synaptic connections to other neurons that result in 700 000 billion synaptic connection The CPU with highest clock today have 5 Ghz or 5 billion cycles per second. If it could simulate a synaptic connection in one cycle it would operate at a speed of 1/140 000 of a brain. So it would need 38 hours to dedicate a single cycle to each synaptic connection. So if only one simulation step would be necessary per second and you could do that in one cycle you would need 140 000 CPU cores for the simulation. The latest intel desktop CPUs have 6 cores so you would need 23 000 of them. In reality it you need multiple simulation steps per second to simulate the brain and the time to simulate a synaptic connection and get and distribute and calculate what happen take a lot longer then one second. The fastest supercomputer [Summit]( URL_0 ) haver a theoretical performance of 200 petaflops and benchmark of 143 petaFLOPS. A petaFLOPS is quadrillion (one thousand trillion) floating point calculations per second. Some estimation is that a human brain could be compared to 1000 petaFLOPS so perhaps we are close to simulate a human brain. That is we would have the computing possibility but you also need a model of the brain to simulate. The Summit computer have 9216 CPUS with 22 cores each and 27648 Nvidia Tesla V100 GPUs that each can have the performance of 100 CPUs for floting point operation. A benchmark from NVIDIA for deep learning resulted in 47x the speed of a Intel Xeon CPU with 14 cores at 2.6GHz. That would be a bit like 50 of the latest intel desktop CPU. Almost all performance is int the GPU cards so lets ignore the CPU and you might convert it to 27648*50=1.3 million latest desktop CPUS for 1/5 of the speed you need so we talk abut 7 millions of the latest desktop CPUs to simulate a brain. So 700 000 billion synaptic connection and 7 millions CPU result in that a CPU can simulate 100 millions synaptic connection in real time."
],
"score": [
10,
7
],
"text_urls": [
[],
[
"https://en.wikipedia.org/wiki/Summit_(supercomputer\\)"
]
]
} | [
"url"
] | [
"url"
] |
ahm4gi | When Copying a File from one HDD to another, why is the copying Speed decreasing over time? | Whenever i copy a big File from HDD 1 to HDD 2 on my computer (for example a downloaded Movie), i have a Copy Speed of 300-200 MB/S, but after a few seconds it decreases to 100-50 MB/S...why is that so? & #x200B; & #x200B; | Technology | explainlikeimfive | {
"a_id": [
"eefruq9"
],
"text": [
"Hard drives have a buffer of faster memory. This is so that if you are transferring smaller files it can do it quite fast. Once the buffer gets filled (as it does with large transfers) then the write speed has to drop to the slower platter write speed."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
ahm6ci | How does a cellphone receive texts while it was turned off, once you turn it on? | Technology | explainlikeimfive | {
"a_id": [
"eefsn4l",
"eefsjy4"
],
"text": [
"It doesn't receive them while turned off. The network knows which texts have been delivered and which ones have not (because your phone is off or you're out of coverage etc), the ones not delivered it keeps trying to deliver. Once you turn it on and the network realises your phone is connected it delivers all the texts that it knows have not been delivered so far.",
"It’s stored in a buffer at the mobile phones company’s servers until it can be delivered to the phone. However I believe they “expire” after about 1-7 days (varies by carries) if not delivered and are then lost. Basically, you mobile provider hold the message for a day trying to deliver it to you."
],
"score": [
22,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
ahn5xc | Iphone lightning cables are sold at lots of gas stations which will sporadically decide to charge the devices or not. Either apple's special chip-cable, or selling blatantly bunk cables should be fraud, no? | Technology | explainlikeimfive | {
"a_id": [
"eeg2cng"
],
"text": [
"This either cables are lower quality. Smaller wire will have more voltage drop under load, which is which the iPhone thinks it’s charging initially, then rejects the cable. There’s just not enough juice. On the other hand, go to eBay. You can get plenty of OEM cables and chargers there for cheap cheap CHEAP"
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
ahn6vx | How does a signal from a cellphone know where to go? | So if I'm in let's say, Hawaii and my buddy is in Toronto and I send him a text message how does my signal get to him? | Technology | explainlikeimfive | {
"a_id": [
"eeg35zl"
],
"text": [
"The signal from your cell phone initially goes everywhere. That is, it radiates out in a sphere. It should pretty quickly find a cell tower. From there it's up to your cell phone provider to look up your buddy's phone number and hand off the message to your buddy's cell phone provider. Then your buddy's cell phone provider sends that message to the closest cell phone tower to your buddy. The tower broadcasts the message in all directions and your buddy's phone picks it up out of the air."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
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