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dx4l1f | What exactly are the crystals in an LCD an what happens to them when the screen is turned off? | Technology | explainlikeimfive | {
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"Hey, i'm gonna try to explain this :) To understand how it works, you need to know light is like a wave, which vibrates in a fixed direction in space, it's called polarization. So when lights travel in a said direction, it can be polarized in any direction through the 360° around it's line of propagation. Crystals in LCD screens are in a phase between solid and liquid matter. It's like a liquid matter, but that keeps the organization of its molecules in a very specific order. Imagine all the molecules are facing the same direction. That gives them the property to change (or not) the polarization of the light passing through it, depending of their excitation. So there is green, red and blue crystals in your screen, and the combination of the three make one pixel. The system of light emission emits light when your screen is ON, and it goes through 3 steps before exiting the screen and going to your eyes: 1. A horizontal polarizer, which force the incoming light to be horizontaly polarized 2. The colored crystal 3. A vertical polarizer, which only let through the light if its polarized verticaly. If the crystal is switched ON : the property of the specific liquid crystal changes the polarization of light to be vertical, so the light going through the crystal can exit the screen. It also has changed the color of the light depending of which crystal (blue, red or green) it was. If the crystal is switched OFF : there is an electricity current flow through the crystal and its property to change polarization is disabled. Therefore, the light passing through the crystal is still horizontaly polarized, and doesnt go through the vertical polarizer. When your screen is switched OFF, there is no electric current going through the crystals, so you can say they are all switched ON. But as there is no light emitted from the back of your screen, no light is exiting. If you want to know more : [ URL_0 ]( URL_0 ) EDIT : forgot the mention what happened when you shut down your screen.",
"Imagine that there's a picket fence covering the display. Light passes between the pickets. Not as much as when the fence isn't there, but a good amount. Now think of the crystals as another picket fence in front of the one I just described. When they're lined up, the same amount of light passes through. But when the crystals are activated, that flips the direction of the pickets 90°. Now there are no gaps in the pair of fences for light to get through."
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dxbzti | What is the creaking/cracking noise TVs make after they’ve been turned off (put on standby) | Technology | explainlikeimfive | {
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"Most likely the body the of TV cooling off. The motherboard, backlighting and power supply in TVs generate a decent bit of heat. As I'm sure you know things expand and shrink with heat and cold respectively. My conclusion would be that the plastic body of the TV is just cooling off and shrinking back to it's resting form."
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dxdw3e | How do recommendation engines work? | By recommendation engines, I mean the systems that Netflix, Hulu, and Amazon employ. For example say on Netflix you finish a series on Star Trek. Netflix then presents you with the you may enjoy Black Mirror, Stranger, things etc. How is it able to compute that? Is it doing so via some machine learning clustering algorithm? One thing I could of was that these systems are also calculating what others watch and clusters tv shows/movies based on that. It could also calculate based off the keywords in the tv show/movie We can recommend tv shows to each because we have an understanding(via a cognitive architecture) of what science fiction is, etc but machines don't have this . | Technology | explainlikeimfive | {
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"These are big money makers, so the exact mechanics are secret. But as to how it knows which movie are SF or rom coms - the movies all have meta data, bits of additional information, this includes genre, actors, director, themes etc. That helps the computer know things like that. Many modern algorithms also collect additional data from users, so do simple machine learning - like it may recognise that SF fans also like big bang theory, or British bake off watchers also like rom coms.",
"The algorithms are based on a few things. Genre is key, obviously if you watch lots of comedy they'll recommend comedy. But they can also do statsitcis a bit like network meta analysis. Basically, you watched \"Friends\" and \"HIMYM\" it finds another user who watched both and sees what else they watched, calculating that you'd like it too (even better if any of you rate it). But it does that not just against 1 other user, but thousands. So 72% of people who watched Friends watched HIMYM and 60% of those liked Brooklyn 99. So your chance of liking Brooklyn 99 is estimated at 60%. That's a simplification. They can perform millions of complex analysis along these principles. It can group you with most similar users based on not just what you watch but age, gender, location, viewing habbits etc. I visualise it like a huge empty 3D box. Everyone has a unique position in that box and the people you're closets two are the most similar to you (a bit like PCA if you know your stats)."
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dxh1b1 | Why does division of floating point numbers take a lot more time than multiplication of floats in computers? | While working on a programming related project, I was told that code should always be optimized to multiply instead of divide floating-point numbers to achieve the same result, and it could take upwards of 6 times the time just to divide than multiply. For example, 5 \* 0.5 and 5 / 2 would give the same number, but the time it takes would be 6 times more to divide. Can anybody explain why floats work like this is in layman's terms? | Technology | explainlikeimfive | {
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"Divide is a much more difficult operation, the best algorithms like [Euclidean Division]( URL_0 ) take many times more steps than multiplication algorithms like the lattice."
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dxifbr | How Neural Network works | I'm trying to understand the core of the NN, but getting confused with mathematics and how it learns. | Technology | explainlikeimfive | {
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"A simple type of neural network is the *feedforward neural network.* In this model, one creates a computational model that takes data (input layer), performs some math on that data, and then passes the result to another set of \"neurons\" (a \"hidden\" layer). Those do more math and pass the results to either another hidden layer or an output layer (where the previous results are mathematically translated into something useful, like a probability). At the end, the math that underlies each layer can be analyzed (in a feedforward network, by calculating partial derivatives) to quantify how much each individual operation is *wrong* for a set of training data (i.e. data where the desired outcome is known); the numerical value is then used to adjust the math done at the appropriate stages in the network so that those operations produce more correct results -- this is the \"learning\". For more complicated networks, the process varies (potentially a good bit), but this is a decent introduction.",
"I'm going to attempt to actually ELI5. Sometimes relationships between inputs and outputs can be hard to define and have complicated relationships. Suppose I grow oranges and have 3 different types of orange trees. Tree 1 produces about b1 trees per season, tree 2 b2, etc. My total oranges depends on how many trees I plant: b1*T1 + b2*T2 + b3*T3 + random error. But maybe fertilizer and water and weather also effects how many oranges I grow. And those relationships aren't so easy to describe, and aren't linear, and might vary by tree type. We might be able to figure it out, but of we go from 3 variables to 300, it becomes impossible to figure out a relationship between everything. A basic neural network splits up this problem into many smaller relationships (neurons), and does this in layers. Layer 1 takes the inputs and forms linear combinations of variables, like the first tree example. But then we apply a nonlinear function that lets that straight line bend a little. And instead of doing this once, we do it a few times, and let the relationship be a bit different in each one. Those neurons in the first layer then get used as variables in the next layer. So sort of like saying that 2*(3+5) can be broken up into pieces: 3+5, then multiply by 2. That's what happening to each neuron, we split a very complicated relationship into a lot of smaller combinations. We still won't perfectly describe the relationships, but by allowing it to bend (from the non-linear function) in a lot of different ways, we can get really close to the real data. The tough part is how to optimize all of the coefficients. We need a way to measure the accuracy of our predictions, then make use of computing power and some advanced math techniques to find the best coefficients for every neuron at the same time."
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dxm9p0 | Sometimes i don't touch my phone screen, like hover really close to it, but it still registers as a touch, why? | Technology | explainlikeimfive | {
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"To answer this question, we have to understand how touch screens work. 99% of touch screens you encounter use a *capacitive* system. There's also a *resistive* system, but those have many disadvantages, like only being able to register one touch at a time. So, the way a capacitive screen works is pretty straightforward. There is a layer of glass in front of the actual LCD, which is the touch sensor. On this glass there's two more layers of transparent, electrically conductive ink. One layer has lines going horizontal, and the other goes vertical. They layer into a grid. Now, these lines are given an electrical charge. Where the lines intersect, electrons build up. These intersections function like lots and lots of tiny capacitors. They store a small amount of electric charge, and the electronics controlling the sensor can detect how much charge is being stored at these points. When you touch the screen, your finger influences the amount of charge that can be stored in these cells. The free electrons drain away from the screen and into your body. The control electronics register this loss of charge and report to the operating system that there is a touch at this particular X and Y coordinate. As to why it will register your finger very close to the screen, but not touching, it doesn't really know the difference. Electric charge can transfer through air. You can easily build a capacitor with two metal plates and just empty air in between. It is a very bad capacitor, and it can't store much charge, but it does work. The way capacitive sensors work is by your body creating a capacitor with the sensor. The device can measure the *change* produced by this. Since it's only detecting slight changes in the capacitors on the glass, the small amount of capacitance added by holding your finger very close to the glass is enough to trip the sensor. And that's why you have to hold your finger so very close to the screen, the air doesn't provide for a very good capacitor, so you have to make the distance very small to get a measurable change.",
"The capacitance of your fingers drains charge from the inside of the screen that is detected as a touch. An actual touch is not necessary on modern screens but you have to be very close."
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dxmbcq | 5: Why is it so hard to replace plastics with another material with similar properties? | Technology | explainlikeimfive | {
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"Cost: plastic is extremely cheap to produce (also to recycle), currently nothing as cheap exists so companies will keep using what makes them the most money. Properties: there actually aren't many materials with similar properties: - recycled/compostable plastics aren't as maleable and mess up the recycling of normal plastics. - paper, well just see the outrage of paper straws - metal costs too much and is heavy - the cutting edge \"plastic killers\" don't currently work on large scale due to lack of technology/knowledge in how to scale (eg. Nanostructures) In actuality plastics are probably the most important, useful and revolutionary material technology in history. It would also be the most environmentally friendly material if we would be able to close the loop and recycle most of it. Problems only arise when it ends up in nature, which I personally believe to just be due to severe incompetence on parts of government, companies and to some extent people. AFAIK \"fact\" to take forward: Producing paper straws rather than plastic ones is often a net loss in terms of GHG emissions, habitat loss and chemical intensity. Use this to always think about the whole life-cycle of products and on the many different ways the environment can be hurt.",
"Plastics are incredible. There isn't one single material capable of having the wide range of material properties plastics can have. They can be cheap, durable, lend themselves well to manufacturing methods such as blow moulding, rotation moulding, injection moulding etc. In the case of thermoplastic elastomers they can be reused (in some capacity anyway). There are food grade plastics, plastics capable of withstanding pretty impressive temperatures (the inner side of many cooking pans are coated with a thin layer of PTFE, better known as Teflon, for non-sticking purposes). They have favourable mechanical properties in that some can act as living hinges in many products (think the lid of a tictac box), meaning no bearings and with that no additional manufacturing processes are required. Sure there are materials with similar properties to _some_ plastic types but you'll be hard pressed to find one which can mimic most let alone all plastic types.",
"\"Plastics\" is not a single thing, it is a group of things defined by properties. Specifically the ability to be easily molded into various shapes while being durable. If you find something that has the properties of plastic, it's plastic. Fwiw, we already do have plastics that will biodegrade. Made from corn. Not economically practical and cannot replace everything we use plastic for.",
"There are two parts to this question: first plastics are largely defined by their properties and composition. If something had all the same propertied then it likely is another plastic. Secondly for different individual properties (malleable, non biodegradable, non reactive to most things, etc.) there are plenty of alternatives. None are as cheap. There are also minor issues like paper products breakdown faster, metal things are heavier, etc. that add up to issues over time but the big simple one is that plastic is very very cheap. Its a considerable investment in both short and long term to switch to something else (certainly one worth making but people don’t like to spend money)."
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dxpio3 | How is computer data "compressed" with programs like Winrar? What is there to be compressed, and what happens when it's decompressed? | Technology | explainlikeimfive | {
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"There are a lot of repetitive things on computer files. And one of the things that compression programs do is make a variable to replace all the duplicate parts of code. Something like x = the word \"the\" so every time the word \"the\" is in a document the program can store the variable x instead. That's two characters shorter. That's a simple example but imagine instead of the word \"the\" the program stored other file specific pieces of code. The file can get a lot smaller by reducing all the duplicate data."
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dxqk1x | Why don’t we switch games from DVDs to UBSs so there is no download? | Technology | explainlikeimfive | {
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"Cost. It costs pennies to mass produce a dvd/Blu-ray, but much more to produce USB storage. Add the increasing prevalence of faster broadband around the world making the need for physical storage media redundant, and putting games onto physical media is slowly being phased out. Introducing a more expensive option seems like a backwards step.",
"Producing a disk is way cheaper than a flash drive. When games moved to discs from cartridges the loading times were a manageable compromise because discs could store a lot more than a cartridge and flash memory was still very expensive at the time. While a publisher could certainly sell a game on a flash drive it would probably still need to install itself on your system, and I don't think there would be enough of an advantage to justify the higher cost of publishing games that way.",
"Do you mean \"USB\"? But you'd run into many similar problems with USB storage as you do with DVD, and some that make it inferior. First, there is the issue of space. Blu-Ray holds a very large amount of data, about 50GB, which is enough to hold *most* games on a single disc, and while USB and SD cards can far exceed this range, it doesn't make sense for anything that can't fit on one or two discs. Secondly, the issue of games needing a download after putting in the disk is caused by game companies releasing the disc as a glorified installer, then continuing development of the game after printing the discs. This practice would continue even if the game were loaded on a USB stick, instead of a physical disc. As for how it gets worse, the USB devices would be more susceptible to damage by electrical or magnetic interference than a disc would be, leading to a higher prevalence of errors, corruption, or deletion of data, which would not be an issue on the disc."
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dxqz85 | In the 2000s, you could tell that a cell phone was about to receive a call/message because it would cause interference to audio devices (TV, stereo etc) a few seconds before the message arrived. When did this interference stop happening and why? | Technology | explainlikeimfive | {
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"Old 2G phones worked by each phone sending short bursts of signal, and then not transmitting for a time to allow other phones to talk. When the phone receives a text or sets up a telephone call, it sends these bursts 216 times a second. The bursts of signal are picked up by wires in a sound system. Each burst produces a 'click', somehow, in the sound system. It is this string of 216 'clicks' per second that you hear as this buzz. Once the call is made and the phone starts ringing, it sends the bursts much faster. This is still picked up as a string of clicks, but now it is too fast, too high a 'frequency', for the sound system to amplify and for you to hear. Now the phones use other ways to allow many phones to talk at the same time. These systems don't send bursts of signal, and so you don't hear whatever gets picked up by the sound system.",
"Today's 4G phones operate at much higher frequencies than the old phones, the higher frequencies interact less with typical electronics. **And** as soon as electronics manufacturers realised everyone had a phone and were constantly using it, they started putting countermeasure in place: frequency filters that filter the frequencies phones operate at, and lead lengths that don't resonate with phone frequencies. **Finally** modern transceivers are much, much better than what we had 20 years ago, allowing them to operate at much lower power, meaning less interference.",
"It stopped happening? My phone’s ~5 years old and still does it. I suspect the change you’ve observed is more likely because people use analog audio transmission a lot less. DVB-T, HDMI and Bluetooth aren’t susceptible to this kind of interference.",
"I was listening to a podcast today that was recorded in 2008. They were recording live and I heard that familiar sound that you’re talking about. I thought, “hmm I haven’t heard that for a while”. Thanks for asking this.",
"Wire shielding too. Old wires had little reason to be so heavily shielded. Also analog and crt tvs were a thing which the cell signals heavily interfered with. The new modern digital tech requires again shielded wires due to encoding needs which protects the wires from the cell signals throwing electrons inside the wire. And even if they do, the decoder will see it as gibberish and ignore.",
"It’s less noticeable for several reasons, but it didn’t go away. The higher frequency and shorter bursts of information are mostly to blame for how less common it is to notice audio interference. If I put my iPhone XS Max beside my computer’s mini soundbar it causes the speaker to crackle. So it hasn’t gone away completely. It’s a lot more faint than the interference used to be years ago.",
"Handshake protocols between digital signals. The first transmission is from the satellite containing a code the 'sleeping' phone recognizes. The phone 'wakes up', says, I'm here. The sat says, now that have I your attention, get ready for a call. Okay ready. Okay sending... ring ring"
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dxtgd5 | 2012 Laptop vs 2019 Laptop with Same Specs | Why does a newer laptop with specs similar to an older laptop have significantly higher Geekbench scores? For example, 2012 laptop has the following specs: 2.6 ghz, 16gb ram, two cores i7. 2019 laptop has the following specs: 2.6 ghz, 16gb ram, 6 cores i9. Are the multiple cores really that influential on Geekbench scores? | Technology | explainlikeimfive | {
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"This car from 1950 is much slower than this car from 2019. Why? They both have a 3 litre engine, 4 wheels, a 5 speed gearbox and a windscreen.",
"Basically: 1. The RAM is substantially faster 2. The CPU has more cores, more threads, and can do much more with each thread (the concept is called Instructions-Per-Clock)",
"TLDR yes. When you add cores it increases the work a cpu can do at once, the main limitation is how software is programmed. Good software can scale well with more cores. Alternatively even with the same core clock (2.6ghz) there is turbo boost which increases the clock speed depending on the work load, as well as improvements on a cpu level to preform tasks more time efficiently. Edit I forgot to mention ram like someone pointed out. Ram and hard drive speed can also drastically improve performance. A program can’t start until read from the hard drive or ssd so the faster that is the better, and the cpu can only do it’s job to it’s full extent if the ram is fast enough to keep up.",
"You can't compare CPUs this way. The CPU should have a longer name than just i7 or i9 (I have an i7-7500U for example). Those are compared with benchmarking tests which are an actual estimation of speed. The frequency doesn't really tell you how fast it is... pretty misleading statistic nowadays. Multiple cores will make some stuff go faster as well... In general you should also consider the type of storage (HDD or SSD) and any other important components (GPU, monitor, etc.)"
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dxzyre | How does a computer know whether a set of binary should be a number or a letter? | How does a computer when reading a file know if "01100001" is an "a" or just 97? | Technology | explainlikeimfive | {
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"The program that reads the file is programmed that way. From the CPU's standpoint, there's no difference. The difference is what type of variable the program uses to store the data - for example if the type is \"Integer\" then the data is treated as a number, and if it is \"Character\" then it is treated as text. In more low-level languages such as C there actually isn't much of a difference. For example, a \"char\" in C can be both a number and a character. You can write something like this: char x = 'a'; char y = x + 1; printf(\"%c\", y); The first line defines a character variable x with the value `'a'`. The second line defines another character variable y with the value of `x+1` which is the succeeding letter, i.e. `'b'`. The third line prints the value of y, so it prints `b`. Notice the `%c` there? This tells the printf function to treat the value of y as a character. On the other hand, I could do something like this: char x = 'a'; int y = x; printf(\"%d\", y); This time, the second line \"converts\" the value of x into a number, which is 97, so this code print `97`. In reality no conversion is really done, since both 97 and 'a' are stored using the same bits. This time, `%d` is used to tell printf to treat the value of y as a number.",
"Computers do what programmers tell them to do. If the programmer specifies that some blob of binary data should be interpreted as ASCII text, it will interpret the data as text. If the programmer says the data should be interpreted as a number, it will do so and will happily perform computations with it. If the programmer gets it wrong, the program will just give nonsensical output. That's kind of similar to what happens when you open a non-text file in notepad, for example. The computer is \"interpreting\" the file the wrong way so you just get gibberish."
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dy2nlf | Why do phones have a time limit to how long they can stay underwater for? What happens to the phone after the time limit? | Technology | explainlikeimfive | {
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"Phones that are water resistant are designed to have as small cracks between components as they can make. But there is still some small cracks where water can seep through. But as they are small this takes time. How fast the water enters the phone depends on the water pressure or if in air the humidity. The deeper you go the higher the pressure and the more water enters the phone. This water can damage components causing shortcircuits and corrode things over time. This is why even though a phone can resist water splashes or short underwater events it might get damaged by being left out in the rain.",
"Water consists of tiny charged molecules. Splash water can be handled just fine, it tends to get wiped a lot quicker too. What happens when the phone is under water is the water having no way to escape but into your phone, since there is lower pressure than in the water surrounding it (which increases with water depth). Those tiny molecules then start to slowly „rinse“ into your phone, potentially causing rust and damage to the circuit."
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dy37sd | Why is it that most electronics and other appliances (i.e: televisions, smartphones, keyyboards) are colored in black? | Is there a practical reason as to why everyday electronics are painted with black? | Technology | explainlikeimfive | {
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"Black is a color which matches any other color, followed by white and gray. A black box would not be out of place in a red, green or blue room. However if you put a green box in a red room it does not look great. Therefore if you want to make something without color options make it black.",
"Electronics are subject to trends just like anything else. Back in the 70s most electronics had fake wood paneling. In the 80s aluminum and stainless steel were all the rage. For a small period of time in the early 90s, white electronics were fairly popular, then matte black in the late 90s, and now gloss black today. As far as I know, there's no practical reason, it's just what people like at the time."
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dy3my8 | Why does it seem that pirated streaming services are hardly ever taken down? | Technology | explainlikeimfive | {
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"Because many of them rely on torrenting P2P, so they don’t actually host any content. You’re actually streaming from other people who are also streaming, and as such there is no server to “take down” hosting the pirated materials."
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dy67z6 | Why are you required to wear specialized eyewear when welding, and in what way the light emitted differs from another light source? | Technology | explainlikeimfive | {
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"The brightness of the arc form an arc welder is bright enough to cause damage to your retina if you looked directly at it. How it differs from other light sources, is intensity. Like the sun, the brightness is so intense that direct exposure will damage your vision. In fact, arc welders are brighter than the light from the sun entering your eye (of course it's travelling much shorter distance, and not through miles of atmosphere). Exposure to the brightness of the weld area leads to a condition called arc eye in which ultraviolet light causes inflammation of the cornea and can burn the retinas of the eyes. Welding goggles and helmets with dark face plates—much darker than those in sunglasses or oxy-fuel goggles—are worn to prevent this exposure.",
"Welding arcs give off radiation over a broad range of wavelengths. The UV C and UV B are absorbed in the cornea of the eye while UV A passes through the cornea and is absorbed in the lens of the eye. Ultra violet light can produce an injury to the surface of the eye, also called arc flash or flashburn. I've had flashburn numerous times and it can be extremely painful for the eyes until it goes away.",
"As a welder I can tell you that the arc and puddle are so bright, you can't see anything with out filter. Now you instagram welders can come boast all uou want, but I can't, maybe I'm just weak and a coward because I wear my PPE. But biggest issue is the UV radiation, how much you get depends on what and how you weld. TIG aluminium being the worst thing for you. Welder's eye is basically a sunburn, but on your eyes, it can even burn inside your eyes. It can cause harmful mutations. (which is why you should wear your PPE american instagram welders). Other thing is Infrared radiation. It will burn you a lot. Rod welding is kinda like old school lime light, little UV, but really bright white light and lots of infrared. Imagine looking at a camera flash, but it is constant, or magnesium flare. While TIG, And Mig/mag cause this electric blue light, heavy in UV. Even reflections are really harmful to you, so the fact you can't see the arc, doesn't mean your are protected from it. Oxyacetylene mean while is a bright gas flame. No UV. But powerful white light and lots of infrared. Imagine looking at a bright gas torch. For this you only need gas googles, DIN3, basically powerful sunglasses.",
"The quality and color of the light varies depending on the materials being welded and type of welding. However, almost all forms are so bright that they'd damage the eye and more practically so bright that they you can't actually see the weld area because all you see is a glowing orb around the work area."
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dy6isv | Why do (US) phone calls coming from your saved contacts sometimes appear Unknown, unsaved or a completely different number altogether? | Technology | explainlikeimfive | {
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"This sounds like a bug. I would make sure your contacts, images, music, etc. Is backed up and do a factory reset on your phone. If it continues to happen after that contact your provider."
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dy7fos | How does a website know I mistyped my card number before I even click “place order”? | Technology | explainlikeimfive | {
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"Part of the card number identifies the type of card so it can tell immediately if you have tried to put a debit card instead of a credit card (or vice versa) or if that part of the number doesn't match any type of card.",
"Credit card numbers are not random. They have information that identifies the type of card and even a \"check\" digit that helps ensure that the rest of the digits were received correctly. \"Good\" payment pages will include some code that will check/validate the card number before it's even transmitted to the server to not waste the time processing a bad number. & #x200B; [ URL_0 ]( URL_0 )",
"There are calculations that can be done to determine if it's valid before you submit. There is a pattern that they all follow - without going into too much depth. Similar to how it knows an email address needs to have characters followed by \"@something.something\" which all emails follow. Anything that doesn't follow that pattern at least is invalid.",
"* the first one or two numbers identify the type of card (Visa, MC, Amex, etc), it is obvious if you don't have a valid value for those * the next few digits identify the bank (Chase, Citibank, BoA), and again only certain values are valid * most cards have 16 digits, but Amex only has 15 and Diner's Club and Carte Blanche have 14 * the last digit of the card is a usually checksum, a digit computed from the other numbers, if you get a digit wrong, the checksum won't match up...this is probably the most common way bad numbers are rejected",
"There are two quick and easy ways. The first digit usually indicates what kind of card it is: Visas always start with \"4\". If you have indicated you are entering a Visa, but the first number is a \"3\", they know you've made a mistake. The other way is the last number is a check digit. You can look up the exact formula, but the idea is you take the first number, multiply by the second number, take the rightmost digit from that and add the 3rd digit, and so on down the line. If the last digit doesn't make what the formula says it should be, you have a problem."
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dyb2xd | How do stenographers catch every word in court? | Technology | explainlikeimfive | {
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"My mom was a stenographer so I can help 1. The minimum speed for a license is 300 words per minute with less that one error per minute The average decent types can type at 60 words per minute with multiple errors. A really good QWERTY typist can hit 100 words per minute. So they are typing faster than people can talk. 2. They use a different keyboard. The way o understand it, you type by syllable’s. So the word STENOGRAPHER can be typed in 4 actions rather than 12 actions. They can also set macros for common words. If it was a law suit involving acetaminophen, they could make a shortcut to type it quickly. They can do this for names or other things. 3. They can ask for clarification during a trial. They don’t often need to. Also, it’s not shown in tv shows cause it’s not fun to watch even if accurate. Edit: for those who want to learn stenography to type faster for work, it’s not that easy. The layout is not the same and the way you type syllable’s is not easy to understand. The words “understand”would look like thrqu*gthy ( completely made up but the output look like gibberish before it’s converted to English. Also there are keyboards designed to help you type faster. DVORAK is what I’ve heard of. It tries to be easier but spacing out letters efficiently. Again to do this you’d have to learn a new keyboard so it’s worth it in the long rub but I never wanted to learn 4. They can mark words they don’t know how to spell to go back and look it up later Edit2: why is this the technique used for court reporting? It’s more cost efficient to store transcripts and share them this way. Also, text is easy to look up. If a lawyer wants to clarify what was said earlier during trial, it’s provides an easy way to look up the answer that is faster than a voice recording because you can read faster than people talk or the amount of time it would take to play back. Also there is a big push in the industry to switch to voice typing. It still involves a court reporter but they would repeat the testimony, or closed captioning for tv. Also for those interested, court reporting is a good career. It makes good many, you can hear interesting stories, if you transcribe depositions you can make extra money. Also, if you’re single you can always try to meet a lawyer or judge!",
"They have special keyboards and a shorthand way of typing it so they can type it all out as it is said and then \"translate\" it back into normal writing afterwards. Top stenographers can type at several hundred words per minute. URL_0",
"They use a special machine with a unique keyboard that allows them to type the rough phonetic spelling of the words they're hearing, which allows them to type much faster than your typical keyboard. They type up their record after the day in court, in regular English, so that anyone can read it. Also, court reporters can and do speak up when they missed something. Unless it's something they can refer to later (like an uncommon or foreign name that they might not be sure about), they will ask the speakers to repeat themselves or speak up if needed.",
"In addition to what everyone else is talking about with the special keyboards, they also rely on audio recordings of the proceedings. They will run through and edit their final product and check the audio for verification.",
"In my divorce papers it was supposed to refer to a person, Keith Moore. But the stenographer wrote “keep more.” You might jump to that conclusion in a divorce hearing.",
"Serious question: why still have stenographers? Can’t recorders work just fine and then someone transcribes later?",
"Stenographers use a special short hand that allows them to type out everything that is said really quick. If you look at a stenography keyboard, it looks nothing like a qwerty keyboard.",
"Stenographers can “stroke” entire WORDS at the same time by pressing multiple keys at once. It’s not placing each finger on one key at a time, it’s placing 4,5,6, all 10 of your fingers on the keyboard and pressing down at once. For example, to write the word “standing,” I’d press the following keys at the same time: STAPBGD. S with my left pinky, T with my left ring, a with my left thumb, PB with my right middle, G with my right ring, and D with my right pinky. Pressing the P and B letters on the right side at the same time create the N sound. The G at the end of “standing” can get “tucked in” to the word to avoid using a second stroke to add G to the word. “Ladies and gentlemen of the jury” takes 1 press of these keys at the exact same time: HRAIPBLG. That’s called a brief, because making the sound layj isn’t a real word. H+R for the L, A+I for the long A, PBLG for the J. “LAIJ”. It’s incredibly intricate and time consuming to learn. It’s not something you can teach yourself. To learn shorthand reporting, students can enroll in an online program or go to a brick and mortar school. Source: a 150wpm stenography student EDIT: In a courtroom or a deposition, stenographers can write in “realtime,” meaning the lawyers can have iPads in front of them and see the English words people are saying at the same time they’re spoken. CART stands for Communication Access Realtime Translation, essentially a speech-to-text service. It serves a huge audience including the deaf community, people who are hard of hearing, and people with leaning needs, such as a student with a learning disability that benefits from seeing a teacher’s words instead of just hearing them.",
"I worked in that industry for eight an a half years, from 1998 to 2006, and people still have weird ideas about it. Keyboard reporters used a special keyboard that took a lot of work to learn. It had to be able to keep up with some guy's 200 or 300 word a minute yapping and blabbering and I have yet to hear of a normal keyboard typist who can get even to 120 words a minute. The certification test was mandatory and the criteria were tough: pass was 99.6% and everything less was fail. With more demand for transcripts, especially from administrative tribunals that offer a lot more work than court, as well as a wide variety of other people including one psychologist wanting transcripts of her discussions with a student, reporting switched to an audio recording model. At first the mask that the reporter whispered into to avoid disturbing the room, was what you typed, while the live mikes on the table were for backup. Those also had to be certified reporters and wanted too much money for the nineteenth-century-style robber-barons who ran court reporting companies here in Toronto. Instead the live mikes were quietly made a much better source and reporters were suddenly making less than minimum wage while the company made damned sure they could never get a job again if they left. Happened to me! Anyway, to answer your question, it's not the \"stenographer\" who could find her own butt with a flashlight, but the much more paid typists who worked our asses off in order to get the transcript right. We used a foot pedal that when released would slightly rewind the tape as adjustable, as well as a variety of macros to smooth typing. There were still problems with bad sound quality, similarity of voices (one eloquent pair, Counsel and client, talked almost exactly the same way and nearly took turns answering questions at the same length so like holy shit); every accent on earth (Jesus that Austrian guy nearly killed me dead with his accent); crossovers (two people talking over each other because in some proceedings Counsel could bicker like children and not let each other finish and we'd have to intersperse what they were saying). If listening to it again failed you took off your headset and listened to it on speaker while using your hand to control the play and rewind. If that failed you took the cassette to another typists's desk and that typist gave it a listen. There was even one case when there were like four of us trying to figure out that no, it wasn't \"ditchyboob\" but \"DJ booth\" and only when I went to the chief proofreader did he listen and tell me just put questions marks and he'd sort it out on proofreading. It was rare for any transcript not to have a couple of ??? here and there and the proofreaders could generally puzzle those out and if it were impossible the chief would authorize an ellipsis (…) instead. At other companies they used an inaudible marker but we were strictly told not to do that. Hope that helps."
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dyf223 | how do traffic lights work? | Is there someone nearby watching the traffic or is it a computer and if so, how does the computer know when to do what lights? | Technology | explainlikeimfive | {
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"THere is a timer mechanism and an induction loop (magnetism based) mechanism. Your car is huge metal block of steel, which has iron, and iron is magnetic. In the road there are bundles of wiring (if you go to an intersection and look closely at the stop line you can see lines in the road which are where these wires are placed). The wire has electrical current passing through and a computer is always monitoring how strong this current is. When your car passes over it, your car will cause this current to decrease through electromagnetism, and thus the computer knows a car is waiting. If the traffic light has been red for a while, I think it instantly changes your light to green, so overriding the timer mechanism. But if the light has only been red for a short period, then the timing mechanism will continue to the end.",
"Most of the time the lights are controlled by a small computer in a cabinet near the lights The lights are switched by timers, which can vary the duration depending upon time of day (rush hour versus middle of the night). Also, depending upon where you live and how many lights they have (and how much money they have) the traffic signal computers may communicate to a centralized computer, so all the lights are synchronized on a busy street. They can also use cameras focused on a turn lane or sensors under the pavement to watch for cars. The cameras/sensors can usually change the timers a little bit to make traffic flow better. However, during special events, police or traffic technicians can actually control the intersection manually with a special box called a pickle.",
"Red light = stop Yellow = caution Green = go Flashing red = stop, proceed when safe Flashing yellow = proceed with caution",
"How do cops and ambulances turn the lights green?"
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dyheyc | Normal Form in Databases? | I’m trying to piece together from my notes, and I’ve been looking at it too long too make sense at this point. What is the difference is 1, 2, 3. 4 normal form? | Technology | explainlikeimfive | {
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"So: Let's get the fundamental idea out of the way. In a database, you'd like to store data in one place, and one place only. You don't want to have it so that a single piece of information appears in multiple places in the database, nor do you want your database to be unable to process requests that \"don't fit\" in to the database: like being unable to store the information about four children, because you assumed that each parent only has three at most. The aim of the game is that each data appears once, and that the data you're storing is connected in a somewhat logical fashion. So, What are the normal forms? ***1NF*** This is essentially just a sanity check: does your database make any sort of sense fundamentally? A database in 1NF will follow the following 4 rules: 1. Each column only stores 1 value. You f.i won't have a column storing a phone number *and* address: you'd have two columns - one storing phone numbers, and one storing addresses. 2. Each column only deals with a single domain of data. If your column is named \"Phone numbers\" you would expect every single row in that column to be a phone number. If your \"phone numbers\" column has a row that has \"123, Street Avenue Rd\" then you have a problem. This is a pretty common sense rule: Columns store what they say they are storing. 3. Columns in a table have unique names. This is also pretty common sense, if two columns in a table are named \"phone numbers\" how will the database system know which one you're asking for? 4. The order of the data entered does not matter. It doesn't matter if entry \"12\" appears before entry \"9\", or if \"John Smith\" is before or after \"Samantha White\". Your database either does not care, or has a column specifically specifying what the order should be (like Date of birth or Alphabetical). You can sort afterwards as you need the data. So, that's all fairly understandable. ***2NF*** The second normal form essentially makes sure that data in a table is identified with the *entire* primary key. A database in 2NF if: 1. it is in 1NF 2. It does not contain any partial dependencies. Partial dependencies are when some columns are identified by *part* of a composite primary key, but not *all* of it. Let's for instance take a simple example I nicked from the internet. You're storing some information about student grades. |Student Id|Subject ID|Student Name|Grade| :--|:--|:--|:--| |1|40|John|70| |1|45|John|80| |2|40|AAron|60| |3|29|Lisa|80| You have a composite primary key from (student id, subject id). In order to uniquely identify a grade you must specify a student, and a subject - since students can be in many subjects and subjects can be attended by many students. However, notice \"name\" here, which identifies the name of the student. That doesn't depend on the subject, only the student ID. This is partial dependency: a column (student name) is uniquely identified by part of the primary key (The student ID). This column will be the same no matter what subject this student is learning. The solution here is simply dropping the \"name\" column and adding it to the \"Students\" table, where it presumably only depends on the student ID: as so. Table Grades |Student Id|Subject ID|Grade| :--|:--|:--|:--| |1|40|70| |1|45|80| |2|40|60| |3|29|80| Table Students |Student Id|Name|DOB| :--|:--|:--|:--| |1|John|12-5-1997| |2|AAron|30-1-1998| |3|Lisa|20-10-1997| ***3NF*** A table is in 3NF if 1. It is in 2NF 2. It doesn't have transitive dependency. Transitive dependency is when a column is dependent on a different column that *isn't* a primary key. If a column is dependent on some information in the database, it *must* be dependent on a primary key. ***BCNF*** This is a bit tricky, but is essentially a stronger version of 3. a BCNF database follows: 1. It is in 3NF 2. for any dependency A → B, A should be a super key. What it essentially says is that if B depends on A, then A is a super-key. A super-key is any value or set of values that can be used to uniquely identify a row. It's fairly rare that a 3NF table is not of BCNF, but I suggest you try to look further in to it on your own. ***4NF*** A database is in 4NF if * it is in BCNF * There are no multi value dependencies. A multi value dependency is essentially where two independent columns both depend on the same primary key. Imagine a table that includes kids and pets of someone. |Id|Name|Kid|Pet| :--|:--|:--|:--| |1|John|Jennifer|Sparkles| |1|John|Billy|Sparkles| |2|AAron|null|Minny| |2|AAron|null|Blubbers| |2|AAron|null|Doggo| |3|Lisa|Sarah|Cuddles| |3|Lisa|Sarah|Junebug| |3|Lisa|Joey|Cuddles| |3|Lisa|Joey|Junebug| Notice how we're just splurging unwanted rows, because we are trying to include each kid/pet combination for each employee. Lisa has two kids and two pets, but gets four rows because we must list each kid and each pet. A better solution would be having a \"kids\" table and \"Pets\" table, so that kids and pets can independently depend on the person in question instead of having to try and share a single dependency."
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dyhzb7 | how serial number generators are made | Technology | explainlikeimfive | {
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"There is no \"that\" way, how a serial number generator is made. This ranges from a simple term (equotation) to completly random strings, which are checked against a database. **This here describes the Serial-Generator, which might be used by software-companies on legal ways. The \"hacks\" are described deeper below** For instance, assume you want to register you product and you are forced to have an online-connection: You can assume, that your inserted serial number is checked against a storage (usually a database), which contains all generated serial numbers to that point (this is very generic, it can go down way deeper, to include version number, Names...) Another possibility is, that a generator is fed with you information (first + lastname, possibly e-mail adress), which ends up as part for the new calculation, so your serial number really just works for your credentials. This is, why some generators (you would possibly never ever download or use) require you to insert your name. The older serial numbers (like windows XP in the early phases) are just made of a term, which ... well ... is giving a \\*seed\\* for a serial. As an example (don't take this too literally): assume, a valid serial would contain 5x5 blocks of alphanumeric characters. It is only valid though, if there is at least 2 numbers in the 1st group, or 3 numbers when there is an Y in the 2nd position. This would be checked against a regular expression. It really comes down to the key, the provider, the method they are settling on and the time, when a serial was required. To make it more secure and protect against Serial-Generators, new methods were invoked to protect against that. If you are refering to the \"hacks\", which people come up with, to generate a serial-number for your software, it is basically the same, with the additional step to get behind the logic, when a serial is actually valid - and when not. You can approach that on different ways: * Bruteforce to get the seed (logic) behind that and build around this * reverse-engineer the code * Trial and error... Some of these generators require you to do additional stuff like inject another \\*.exe file or adjust the Auth-files. The validation can take please either server-side (the server checks against its storage, if your key is available) or client-side, which simply checks if the hash is viable. The client-side validation is usually easier to get around, since **the logic to check against has to be somewhere on your machine**"
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dymafh | How are Dentists able to fill cavities that are between your teeth with little space to perform the operation? | Technology | explainlikeimfive | {
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"* Small precise tools designed specifically for that procedure * Mildly elastic nature of one's teeth being able to move slightly in place without breaking, offering a little more space * Magnifying mirrors to see the area better * Drilling out the bad portion of the tooth itself creates some room to work in Just some of the ways, others will likely be able to offer first-hand information.",
"[This page from Garrison Dental gives a decent idea of how it works.]( URL_0 ) Essentially, we drill down from the top of the tooth to access the decay that is in between. We refer to that process as “dropping a box”. Once we have cut the tooth (prepared it) adequately, we need to use a metal band in between the cut tooth and the tooth next door to hold the filling material in place while contouring it correctly. There are many different systems for that available but they all function is the same general manner. All of our instruments are designed to work in very small spaces, sometimes measuring only a few mm in any dimension. We use magnification glasses called [loupes]( URL_1 ) that help us see into those tiny spaces."
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dyw5bx | How does free WiFi work is large public places? How are they able to get it to stretch across whole airports, malls, etc, when my WiFi barely stretches across my house? | Technology | explainlikeimfive | {
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"A facility the size of an airport with have dozens if not well over a hundred Wireless Access Points (antennas) all managed by a centralized controller. Enterprise Grade wifi gear is also significantly more powerful and reliable than what you have in house, and also significantly more expensive.",
"I work at a small university, and we have around 500 individual access points around campus, while you only have one. Most of our academic buildings have an access point in every single classroom, and two in larger lecture halls, as well as access points in office areas, lounges, and other spaces. All of those access points are managed and controlled by a central piece of hardware, the controller. Normally, your device would decide which access point to connect to as you move around, usually trying to stay connected to the current access point for as long as possible. But our controller makes that decision for you in order to put you on the access point that's best for you, and balance the wireless clients to give everyone the best connection possible. Each access point can also each handle a lot more connections than your home wireless router probably can.",
"Multiple routers and the phone thinks they are the same because they project themselves as if they are. It’s also called a mesh network"
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dyxi1g | How does a motherboard work and what does it do for the computer? | I get just about everything else - CPU, GPU, RAM, etc. But for some reason I can't figure out what motherboards really do or how they work. | Technology | explainlikeimfive | {
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"The primary function is to connect part together. The CPU has a lot of pins that are used to communicate with different parts. Some are for communication the RAM some are PCI-E lanes to the graphic card. Because the CPU is small and you need a cooler mounted on the side you need something on the outer side that connects the wires to the socket that you put the RAM and Graphis cards in. That is the primary function of the motherboard, provides an electrical connection between the different parts. But there is more part on the motherboard. There are other types of communication that the CPU does not understand by itself. You have sound, USB, network, hard drive connectors. In the past, they were separate cards like the graphics card is today but when the chip that handles them and communicates with the CPU got cheaper and smaller they got integrated on the motherboard. Multiple functions can be integrated into a single chip. It cost less of stuff is mounted on the motherboard compared to on separate boards but you lose flexibility. So you integrate stuff that the cheep variant is good enough for almost everyone but the expensive part where there are differences in need like the CPU, GPU and RAM are separate on a desktop. If you look at it from the CPU point of view there is no difference if the chips are on a separate board that you can remove or directly soldered to the motherboard. On laptops the CPU, GPU and today even RAM might be soldered onto the board. So you trade flexibility for space and lower cost. The next main part is power. The computer power supply output 12V, 5V, and 3.3V but the CPU operates today at around 1.5V. So the component you need to convert the voltage is mounted on the motherboard. They converted 12V to the appropriate voltage. That makes a power supply a standard component that needs no change when the CPU or other part requires a voltage change. So a motherboard is a way to interconnect components, provide a place to put all cheap and useful functions you like that is not in the CPU like USB and convert and provide power at the correct voltage to all parts.",
"The mobo networks the rest. You can't just glue a GPU to a graphics card and expect it to work. The mobo handles input/output for everything from USB to fans to graphics (if your CPU supports integrated graphics)."
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dyz1dd | How do targeted ads from things you've searched on a computer get to your phone? How does the tracking process work? | For example yesterday I found myself in a website I'd never been to that sells furniture. I also visited some other furniture sites. Today on my phone all the ads on my apps are for furniture I viewed it the site I'd never heard of before yesterday. How does that work? | Technology | explainlikeimfive | {
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"Is your email attached to both devices? Do you have similar accounts between the two? That's how they do it. It's just spamming the devices attached to your accounts.",
"Have you ever logged in to the same account of any site on both devices? That in conjunction with cookies that advertisement networks like AdSense use result in that they know both are used by you. If it is an android device you almost certainly have a google account you are logged in with. If log in to google on your computer like to Gmail it is quite clear that the one used the browser and phone is the same individual. If you use chrome on both signed in on your account there is a clear connection."
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dz24kc | why helicopter pilots can't escape in case of danger as they do in jet and save themselves? | Technology | explainlikeimfive | {
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"They can't eject straight up or else they'd be torn up by the rotors, and helicopters usually fly much lower than airplanes, so ejecting sideways likely wouldn't give them enough altitude for their parachute to slow them much before they hit the ground.",
"Another reason others haven't mentioned yet is that it's [possible to land a helicopter without power]( URL_1 ) because of [autorotation]( URL_0 ). This means that if the engine fails, it's possible to survive without ejecting.",
"Look up the Kamov KA-50 it has ejector seats in them. The rotor blade get discharge and is blown off first before the ejecting seats follow it.",
"On a jet the engine is behind the craft so they can escape by ejecting high above the craft. On a helicopter there are two sets of blades on above and one at the back. Bailing out of a helicopter is possible, just difficult due to that. As you can get killed by the blades trying to escape.",
"There are some helicopters with ejection seats, but it is not a common feature. the problem is that you don't want to launch the pilot into the rotor, so you either have to launch them into another direction or first jettison the blades. In either case this takes extra time and altitude. With jet planes we nowadays have ejection seats that can successfully eject and parachute a pilot when the plane is already (or still) touching the ground. With a helicopter that would be difficult as the extra steps of first removing the blades or first shooting them sideways takes up time in which they will continue to crash downwards. Also adding extra parts like blades the explode away from the helicopter always adds something that can go wrong (like blades that explode away when you don't want them to). The extra cost and complexity usually isn't worth the limited benefit."
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dz3jfu | Why are phone batteries rated with mAh (milliamper hours), but car batteries with KW (kilowatts)? | Technology | explainlikeimfive | {
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"First, a correction. Car batteries don't us kW, which is a measure of power. For an electric car, batteries are typically measured kWh (kilowatt-hours). This is a measure of energy (power x time). Essentially how much \"fuel\" it has. You are correct in noticing that mAh are not really a measure of the same thing. Current x time is not energy, it's charge. However, it is ultimately used the same way, since all lithium ion batteries have the same voltage, and charge x voltage = energy. As electronics designers take the standard voltage for granted, it's natural they think in terms of current only, hence that unit being used for specs. With an electric car, there is no standard voltage. It is necessary to stack many batteries in series to get much higher voltage, and there is no one standard configuration. So it is more logical to talk about energy when comparing them.",
"You will see two different ratings on car batteries, amp-hours and cranking amps. Cranking amps is what you can expect for a peak, right now availability to start your car. Amp-hours is more of a duration and rather misleading in my opinion. Theoretically, a 100 amp-hour battery could supply 50 amps for 2 hours, or 1 amp for 100 hours. Same ambiguity for the cell phone battery, other than its load is probably more consistent. I assume there is an industry standard somewhere explaining this if anyone wants to quote it."
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dz535q | Why does toggling the power off and on for your internet modem fix connection issues? | Technology | explainlikeimfive | {
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"The same reason that it can fix a bunch of computer issues: turning a device off dumps everything that is in memory currently. Turning it back on loads to a known stable state. This won't help the issue if, say, someone broke a carrier line going from your house to your ISP, but if the issue is that the router captured a malformed packet and can't figure out what to do with it, it'll dump that packet and all other operating data and then reload all of the base state that gets pulled when booting from power-on."
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dz73bf | What's Dijkstra's Algorithm used for in Computer Science? | Technology | explainlikeimfive | {
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"Lots of things. It's also known as 'Shortest Path First'. I can be used for networking to find the shortest route(least number of router stops when sending a message). It can be used in databases to slowly optimize the location of data based on where it is needed most. It can be used by robots to determine the shortest path to an objective, or an AI to figure out the optimal path by giving certain obstacles a distance value. It can be used by game AI to create a map of the shortest path to ending the game or winning based on what is considered a 'path', a path can be a set of moves, and choose to play those moves; a version of this is A\\* or minimax."
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dz7qoy | Why are tech companies concerned with the thoughts, actions, and beliefs of their users? | If you go to a store, restaurant, or hire someone for home repair, they do not consider whether your beliefs are hateful, whether you use harassing language against women or minorities, or whether you believe in fake news or conspiracy theories. However, if you sign up for an account on a web site, tech companies seem to be interested in such things, rather than simply delivering a service. You don't find that in any other industry (except perhaps psychology and psychiatry). Why is that? | Technology | explainlikeimfive | {
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"It's pretty much the same in real stores, they just don't tell you, as they have the right to deny service, and that doesn't require an agreement. It depends on the online service, but in the case of social media, it's primarily to be able to deny you service if you start spouting hate speech. If you go into a retail store and spout hate speech, they'll deny you service. You'll most likely be escorted off premises, or the police will be called to remove you, as you'd be causing a public disturbance. Remember, your account online is part of someone else's user experience on that site. The company will want a certain standard of user experience, and hate speech might not fall into that. The agreement you make ensures that your account can be suspended if you breach the terms of the agreement, giving you no leg to stand on, reducing the amount of contended cases, saving the company time and money.",
"Because the law regarding who is responsible for the content on most internet platforms has been deliberately muddled. Content creators are generally responsible and hosts for user content generally are not. However companies have a vested interest in keeping the lines blurry so they can dodge back and forth across the lines seeking a better legal position on any given issue. Meanwhile everyone gets fucked by technocrats with no significant oversight doing whatever they want since no systems exist to constrain them. The only real force that has any impact is the market and as long as they blow enough free sunshine up users asses they can whatever they want. See Google, Facebook and Amazon",
"Probably because many of them get a lot of their revenue (or all of their revenue) from ads. They are trying to figure out how to target ads to you that are likely to result in click-throughs and purchases, since that's how they make their money. They want to know everything about you so that they can try to correlate the type of person you are to the ads that might be successful with you. They are also (sometimes) trying to ensure that the overall experience for their user base is positive. People who spread hate on their social media platform might drive away other users either partially or entirely. They make money off of having lots of users come back many many times, for hours each day. It's in their best interest to not have shitheads and trolls drive off their revenue base.",
"Everyone else has said it here but it's two things: data farming for enormous profit and covering their asses if you start spouting hate speech.",
"In both cases, the company doesn't want you to make the other customers uncomfortable and drive them away. The difference is that people tend to express those beliefs more openly on social media. The store or restaurant doesn't care if a customer is a racist only because the customer isn't actively doing racist stuff in the store. If I went to store and started following other customers around ranting about conspiracy theories or harassing them about their race or gender, I'd probably get kicked out.",
"If you look back at the middle ages, the person who ruled a kingdom was the guy who could muster the biggest, most effective army. That's your king/queen. Then something strange happened where businessmen got together and said that every landowner could rule themselves collectively. That brings us modern western democracy (with a couple of changes, such as women, POC and non-landowners having a political stake). They still did it by raising a bigger, more effective army though. We're at the point now where it's looking like traditional war is going to be rare as it's an existential threat to everyone involved. This means that wars are going to be fought with information as it's pretty easy to cancel someone, even on dubious claims (see Garrison Keillor). This presents an opportunity to decide who does and does not get to lead for people who control the flow of information. Basically Facebook, Google, et al. seem to be setting up a system in which only candidates that they choose are allowed into the public debate, which presents an interesting challenge to our Republic. Both Warren and Gabbard have fallen prey to this, though Warren seems to have backed off of her attacks against tech monopolies after having her internet outreach shut down for a couple of days."
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dz89it | how online gaming processes fast paced decision making accurately. | How could servers that serve clients across the world share packets and make decisions in speed intensive games (ex:when two players aim and shoot at the same time) and still be accurate up to the millisecond? | Technology | explainlikeimfive | {
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"It's not up to the millisecond, there's a lot of delay involved and servers rarely run higher than 60Hz. Human reaction time is around 150-300ms so as long as the total delay is less than that isn't really much of an issue. On the how, a lot of servers just do what they're told to do at the time without caring about latency of the player. Player says jump, 20ms later the server gets told to jump, the player jumps. Usually, the games are also run on the server and your server-character get simplified versions of the inputs you provide. Where you'd look around, run about, use abilties etc. the server doesn't need to know every detail so your client can just send the important stuff like your position, whether you hit someone, what ability you used. There are some more complicated ways of handling the inputs and servers, Overwatch uses a 'prefer-the-shooter' model that processes hits on your client as a priority while things like positioning and abilities are triggered on the server. This is done to make shooting feel more precise. I think CS:GO uses an entirely server-based decision system where all the inputs are sent to the server and it just acts on the first one it gets. Some games might take a time-stamp of the packet and use that to determine who shot first. Best way I can explain it would be to just imagine that your Kb/M or controller is just connected with a really long wire to the server in a lot of cases."
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dze6s9 | What's the difference between Blu-ray and regular CDs? | Technology | explainlikeimfive | {
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"text": [
"CDs and DVDs use a red laser to read data, and Blu-ray uses a blue laser. Since the blue laser has a shorter wavelength you can fit way more onto a Blu-ray disc than on a CD or a DVD, which means clearer sound, sharper video, and more bonus material for movies."
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dze9j2 | How does colorization of old black and white footage work? Do certain gray tones translate to color or does someone have to edit everything manually? | Technology | explainlikeimfive | {
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"text": [
"There’s been attempts at using AI and procedural calculations, as yes, different colors translate to different shades of grey based on the film used - but most all are done by hand. Early on each frame was colored entirely by hand but newer techniques use object detection and similar calculations to how video compression, up scaling and motion interpolation works to detect “movement” to keep the colors moving frame to frame automatically. Basically it tries to find an “object”, then it tries to detect where the edges of that object is on each frame to move a shape. Chances are it uses the techniques used for color broadcast TV to add chroma data to a black and white image - which is why it usually doesn’t look much different than if it were recorded in color in the first place. Some film is high enough quality to be re-scanned in 4K and I bet that would take a LOT of work to colorize."
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dzexlq | When there are multiple bluetooth speakers/headphones/devices in use in an area, how do they keep from intercepting and playing back neighbouring bluetooth signals? | Technology | explainlikeimfive | {
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"text": [
"When you first set up a Bluetooth device to connect to your phone/laptop, the connection is “paired.” Pairing establishes specific codes and both Bluetooth devices and computers/phones thereafter recognize properly paired devices. PC and phone should be set to only connect to properly paired devices.",
"Bluetooth is a digital system that sets up a complicated \"conversation\" between devices. Just like when you're having a private conversation with someone you can ignore background noise and other people talking, Bluetooth can recognize what devices it is trying to talk to and ignore others. It is not a \"broadcast\" system like TV is, or like someone giving a talk on a stage, even though both use radio/sound waves respectively. More specifically, here are some ways that Bluetooth separates out different devices: * Frequency hopping: Bluetooth isn't tuned to a single frequency (like a TV or a radio), but instead jumps around a whole bunch of frequencies according to a particular pattern, automatically. This pattern is agreed between devices that are talking to each other. Other devices are likely to be talking on other frequencies at any given time, and thus won't be \"heard\" and won't interfere. A particular pattern makes up what is called a \"piconet\" and several devices in this network can talk to each other (e.g. one computer and several Bluetooth devices connected to it at the same time). * Addresses: Each Bluetooth device in existence has a unique address, like a phone number. Devices search for other devices and then establish communications using their specific address. This is how your speakers know to connect to your computer when you turn them on, so the computer can send them audio (or vice versa: when you first pair them, the computer probably showed you a list of devices and you selected one, at which point the computer \"dialed\" the speakers). Once they are connected they don't have to use the addresses any more (much like you use a phone number to make a call, but you don't need it any more once the call is ongoing); however, they still use some identifying information in every communication related to the addresses to ensure that they don't get confused by some other Bluetooth connection going on at the same time between other devices. * Encryption: For security, after you initially connect a pair of devices, they agree on a specific encryption key between them. This key is used to encrypt all further communications. If another device tries to snoop in or modify the communications, it can't, because they are encrypted. Other devices won't have a key or will have the wrong key. Devices ignore any data that isn't properly encrypted and authenticated using the encryption key they expect."
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dzg4m2 | How are computers able to turn back on after when restarting? Eg: Once the computer is shut down how does it know that it is supposed to turn back on? | Technology | explainlikeimfive | {
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"There's a small battery inside your computer that runs a separate mini computer 24/7. This mini computer is what turns the main computer back on during a restart. It also contains the system clock, which is why you can turn off your computer, wait an hour, turn it back on, and still have it know what time it is.",
"Your computer/laptop doesn’t actually fully shut down when you send a restart signal. It draws minimal power (over a 5V line) that keeps the BIOS active during restart, then basically powers down all the other components and powers them up again. The operating system does this by sending signals to the motherboard through the Advanced Configuration and Power Interface (ACPI)."
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dzijzk | why do apps update regularly but nothing seems to change? | Technology | explainlikeimfive | {
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"text": [
"Most of them are just minor reconfigurations, or getting rid of glitches nobody knows about.",
"It usually has to do with small bugs faced by a minority of of users, updates of libraries used by the app or improvements for a given model of phone",
"Because most of the updates are internal fixes which are unnoticeable, unless you happened to experience the specific bug they were fixing."
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dzj3fp | Why is there a considerable time delay in sending and receiving emails but none in messaging apps like Whatsapp or Insta ? | Technology | explainlikeimfive | {
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"text": [
"Email protocols are as old the internet, and go through many servers before they arrive at their destination. Whatsapp for instance uses the XMPP protocol which address some of the issue faced with email. But it wasn't meant to replace email as such, it was meant to replace IRC (internet relay chat). So because they are 'quite recent' they've been designed to work for shorter messages. Email has matured and now included other protocols such as IMAP, POP3, SMTP, etc. The software that runs email servers is highly configureable and stupidly complex. Most, but the best setups are probably not setup optimally to be honest. Insta probably works on the same protocol as Whatsapp or even websockets. Some protocols are even peer to peer so no middle man to slow it down either.",
"* Messages on WhatsApp or Instagram are between two users on the same service. * One company controls the process from end to end. * A message moves from the client (the software on someone's phone) to the central server and then straight back to the other person's client. * Email is more like mailing something to another country. * Yes both the US and Pakistan have some version of a mail service, and yes they have an agreement that says they will each deliver mail from the other to their citizens, but the rules about what kinds of things can be mailed and how the mail moves once it gets to the other country is different and not necessarily streamlined. * Email works because a bunch of people got together and decided how it should work and then a lot of other people decided to follow those rules. * The rules basically say, if your email server sends my email server a message that's formatted this specific way, then I'll try my best to get the message to the user I think you're sending it to. * But each server in this scenario is controlled by a different company. * And each company has different rules about what kind of attachments they'll send. * And each company has their own way of checking if the email is SPAM or not."
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dzkcpo | Voyager 1 is nearly 12 billion miles from earth and is still able to communicate and transmit data to Earth. So how it's possible to lose cell connection by simply standing in the wrong part of a house it staggering. | Technology | explainlikeimfive | {
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"text": [
"There are antennas that are 70 meters in diameter listening for Voyager. There’s also not a bunch of buildings to block the signal. And there’s not 5000 other voyager probes competing for the same chunk of signal space."
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dzkd85 | How does torrenting work? What's the difference between downloading a file with torrent and downloading a file with the web browser? | I have no background on I.T. Just really curious on how torrents work and its difference on downloads in web browsers like chrome, firefox, etc. | Technology | explainlikeimfive | {
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"In the simplest sense instead of simply downloading the file in its entirety from a central server, torrents download bits and pieces of the file from other people who are after that torrent. In a normal download you go to f.i URL_0 , and go \"Hello. I want the video 'How to bake a cake', please\". Youtube promptly responds \"Here you go, this is the video 'How to bake a cake'\". When you download a torrent link instead, you're essentially downloading a key that tells you how to find other people who have the file. You then go down the list you got and approach those other torrenters. \"Hello, I'm looking for the video 'how to bake a cake'. Do you have it?\" To which the response might be \"Yes, I have some of it. I have pieces #12-29, and #32: you can have those!\". You then go to the next person and go \"Hello, I'm looking for 'how to bake a cake, and I already have pieces #13-29 and #32. Do you have the rest?\" To which the response might be \"Yes! I have #1-13 and #30-31. I'll give you those pieces if you give me #16-24!\" And so on and so forth. When you're torrenting you're connecting to all the other people who are also torrenting, and you share the bits and pieces of the file between yourselves until you have the complete file you're looking for.",
"Torrent is a Peer-to-peer download technology. Basically, person A creates a torrent of one of their files and publishes a .torrent file that can be used to download that file at their computer. Person B else opens the file with a client, the client connects to the person A's computer, and ask for the file. Person A's computer start sending the file by pieces. Person C also opens the torrent file, and start downloading pieces from both A and B, while sending said pieces to other people.",
"its the difference between downloading the file from a central location(a web server), and downloading it from every other person that has the file you want. the main thnig with torrents is there generally there is not a central location istend you use somethnig called P2P(Peer-to-peer). you also need ot accpet that files shared thru p2p are broken down inot a number of pieces for ease of transmision. the way to picture is would be: i have a document 20 ppl want a copy off.Instead of having everyone getting their copy at once which woul be painfully slow since you have 20 ppl wanting ot read and copy the file at the same time, you split the files into a number of parts each person can take turns reading. Eventually more and more ppl will have a full copy of the file and once they do they can take part of the sharing process, spedding it up for everyone URL_0 the end of it everyone will have their copy.",
"A torrent can be from a bunch of different people. For example you download a 90 minute movie and every 1 minute of the money is a chunk you might get each 1 minute chunk from a different person. And, while you are doing that you might also be uploading chunks of the movie you already have downloaded. With a torrent you basically go \"hey, does anyone have this part of my movie?\" And someone else goes \"I got you fam\" A normal download would just be downloading the entire film in one big chunk from a single source.",
"Software developer here, Torrents are neat, they use a computer algorithm called \"fountain codes\". What they let you do is pick and combine several bytes from the file and send it out to all the clients. You can reverse the process and determine where in the file those bytes go. You can do this with any byte combination in the file and thus have an endless, infinite stream of data. You spew bytes like a fountain. The algorithm can be very deterministic about what bytes it sends, but picking bytes at random is just fine, most of the time. You will get the whole file eventually. What makes fountain codes absolutely awesome is that as soon as you get any amount of file data at all, now you, too, can participate in uploading data to all other clients. Now everyone who is downloading the file is helping to upload the file. This is especially useful when people are joining the download pool at all times. It's hard to download a single file from one source at full speed, but you can download at full speed, using all your available bandwidth, if you have enough trickling streams from a whole bunch of your peers. That's why staying on the torrent and contributing after you've fully downloaded the file helps everyone else. The original source can even go offline, and so long as one peer has the whole file, everyone will get it. In the traditional model, it's one client at a time to one server, and each person will be served in full, in turn. If there are a dozen users all downloading the same file, it'll be uploaded from the server a dozen times in sequence, and you will wait your turn."
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dzoa1v | What is a webhook? | Technology | explainlikeimfive | {
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"text": [
"Webhooks are one way that apps can send automated messages or information to other apps. They're a simple way your online accounts can \"speak\" to each other and get notified automatically when something new happens. There are two ways your apps can communicate with each other to share information: polling and webhooks. Polling is like knocking on your friend’s door and asking if they have any sugar. Webhooks are like someone tossing a bag of sugar at your house whenever they buy some. [Source, you saucy kitten]( URL_0 )"
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dzp8hk | What is actually changing when Windows does an update, And why does it take so long? | I've just sat through a windows update that took around 40 minutes to install. What has actually been changed in my PC? Also, a couple of supplementary questions, why does it take so long and why did my PC have to re-start 3 or 4 times during the process? | Technology | explainlikeimfive | {
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"text": [
"It depends entirely on the specific update. If it's just some virus definition update for Windows Defender it probably doesn't need to reboot and can happen in the background without you knowing. If it's more integral to the operating system, it may be replacing core system files that can't be replaced while the system is fully running. A 40 minute install time is pretty unusual and is more common with large updates (like Service Packs and such). I'd imagine the system is creating a restore point (in case anything goes wrong), maybe downloading some parts it might be missing (if it didn't finish before the update was initiated), unpacking and verifying the contents of the update, finally installing the actual update, then verifying the installation went properly. The multiple restarts are usually updates that need to replace critical system files that can't be replaced while Windows is fully running. Windows will instead place some special instructions to run very early in the boot process to replace those files and then restart the system, as it boots it will immediately start replacing those files. This can be triggered multiple times for one or more updates that need to do this."
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dzpo0c | Why are screens flickering when you're trying to take a photo of them? | Technology | explainlikeimfive | {
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"The screens are flickering all the time. 50 or 60 or more times per second, that’s how you see movement on the screen. Our eyes however can’t see this; we can see a flicker of a few times to 10/12 times per second (and we see them as individual images in those cases) , but going beyond 24 per second, our eyes and brains can’t process them individually and we interpret that as motion. Cameras, like ones on your phone, can actually capture the moments between the image changes; so you see parts of different images being replaced by new ones, and parts remaining the same, so you get “streaks”",
"[the Slo-Mo Guys did a video that will help understand it better than if I try to use words]( URL_0 )",
"It depends on the type of screen, different types of screens can flicker for different reasons. CRT monitors shoots a scanning electron beam that causes phosphor in the screen to glow for a couple of milliseconds. Each frame at for example 60Hz is 16.7ms meaning the screen is mainly dark with a flickering bright image a few ms each frame. Persistence varies from model to model. 60hz (60 repetitions per second) seems to be around the frequency where some people see flicker and some don't. At 85 or 100hz, most or all people see a stable image on CRT. A camera however, can record flicker endlessly fast (to the technical limits at least) depending on frame rate and shutter speed. There can also be resonance patterns in the flicker. A 60fps video properly timed could record a 60hz CRT as simply being black. Or perfectly stable and flicker-free. When it comes to LCD panels, they can behave completely differently. Some are designed to emulate CRT behaviour for motion resolution (strobing), this is common in gaming monitors (usually optional feature) and some TV models game modes. These will act just like a CRT. Normally, LCD monitors display images by holding the image perfectly solid, until the next frame arrives. These will look perfectly solid to a camera. However, a LCD monitor produces it's image by combining two components; a backlight (basically some type of lamps or leds), and while the LCD panel can be perfectly solid,the backlight that shines trough the LCD often uses a technique called PWM to control luminance. Instead of actually lowering the luminance, it instead flickers fast. Humans generally can't detect very fast flicker, and instead views an on/off flicker as reduced luminance. This flicker of the backlight itself can also produce flicker in a camera,again depending on above mentioned parameters.",
"I think it might have something to do with the refresh rate of the screen being out of sync with your camera display's refresh rate or frame rate if you're taking a video."
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dzr3v8 | How do graphic card updates work? How do they increase effeciency? | Technology | explainlikeimfive | {
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"Among other reasons, sometimes new games expose bugs or limitations in the existing drivers, which the GPU manufacturer more or less has to fix to get the job done right.",
"Turn off your PC, open the case, carfully remove all power cords that are connected to the GC, remove the screws that connect the GC with the case, carefully replace the old GC with a newer model, screw the GC to the case, reconnect the power cords, close the case, reboot PC, install actual GC-drivers. Newer GPUs take work from the CPUs by being faster in calculating graphics. Edit: I forgot the screws.",
"It's a combination of things. It can bring general improvements for the card if they are able to get new features in. It can resolve current bugs. They can bring drivers for new types of cards, they can bring security fixes. It can bring extra settings for specific games. It fully depends on which update. Everything should be visible in a changelog."
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dzs3hn | Why are certain neighborhoods limited to specific ISPs? | In my search of ISPs, I discovered that my community is limited to only 3 different providers. Why is that? Do companies “own” specific areas? | Technology | explainlikeimfive | {
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"Sometimes it's as simple as the company not having the infrastructure to serve you yet. For instance, your neighborhood may have cable lines owned by Comcast, but fiber optic cables for AT & T have not been installed yet.",
"In some (many?) cases, an ISP company has made arrangements with a local government to partition some areas for their exclusive use. This was probably presented as necessary for them to invest in the infrastructure therein. There may also have been contributions to the city government and / or people within that government, like a city council or board of supervisors. Sometimes these decisions are made by a city manager who has been compensated for this difficult decision by the successful ISP. When researching this process, it's best to hold your nose, as the stench may otherwise overwhelm you. Cynical? Who, me?"
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dzyd65 | How are films distributed to cinemas all over the world? I’m pretty sure they don’t use film reels anymore, so what do they use? | Technology | explainlikeimfive | {
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"The theater I work at gets sata hard drives from the distribution company that all the studios work with. There is only two companies in the US that we get flims from that I know of. Those hard drives can have multiple versions of the movie on them ranging from your standard 2D to 3D and also 5.1 sound and 7.1 sound. I've seen one hard drive for a kids movie contain 10 versions the movie. I've seen some movies take 200 GBs of hard drive space. Just a little bit of info from my experience working at a theater.",
"**TLDR** VERY large digital files A **Digital Cinema Package** (**DCP**) is a collection of digital files used to store and convey [digital cinema]( URL_9 ) (DC) audio, image, and [data streams]( URL_4 ). The term was popularized by Digital Cinema Initiatives, LLC in its original recommendation[\\[1\\]]( URL_2 ) for packaging DC contents. However, the industry tends to apply the term to the structure more formally known as the Composition. (\"You PLAY a Composition, You do NOT play a Digital Cinema Package\".[\\[2\\]]( URL_10 )) A DCP is a “packing crate” for Compositions,[\\[3\\]]( URL_0 ) a hierarchical file structure that represents a title version. The DCP may carry a partial Composition (e.g. not a complete set of files), a single complete Composition, or multiple and complete Compositions.[\\[3\\]]( URL_0 ) The Composition consists of a Composition Playlist (in XML format) that defines the playback sequence of a set of Track Files. Track Files carry the [essence]( URL_6 ), which is wrapped using [Material eXchange Format]( URL_3 ) (MXF). Two track files at a minimum must be present in every Composition (see [SMPTE]( URL_7 ) ST429-2 D-Cinema Packaging - DCP Constraints, or Cinepedia[\\[4\\]]( URL_1 )): a track file carrying picture essence, and a track file carrying audio essence. The Composition, consisting of a Composition Playlist and associated track files, are distributed as a Digital Cinema Package (DCP). It must be underscored that a Composition is a complete representation of a title version, while the DCP need not carry a full Composition. However, as already noted, it is commonplace in the industry to discuss the title in terms of a DCP, as that is the deliverable to the cinema. **The Picture Track File essence is compressed using** [**JPEG 2000**]( URL_8 ) **and the Audio Track File carries a 24-bit linear** [**PCM**]( URL_5 ) **uncompressed multichannel WAV file.**",
"I manage a cinema in Australia. Movies - DCP (Digital Cinema Package) on a hard drive. Usually a CRU - a specific drive housing that fits into a dock on the server, but smaller distributors often send them on a typical USB drive that you can buy at OfficeWorks. Trailers - DCP on a USB stick, and increasingly becoming available either from cloud storage services, or automatic digital delivery systems. Both of these, you copy onto a server, which you can then use to make up a playlist. For example, opening tags, ads, trailers, movie. You can also attach automation cues at various points on the playlist, for curtains, masking, lights, etc. From there, you schedule the playlist to play over the course of the week at the correct times. Then you can pretty much just sit back and let them do their thing. Film is still a thing in a few rare circumstances. Mainly with older movies at cinemas who care about the format, but occasionally new releases too, in the right circumstances. Joker received a 70mm release here, Once Upon A Time In Hollywood received a 35mm release here, etc. I’m pretty passionate about film, so I run film using traditional techniques in private theatre in my spare time, and am in the process of reinstalling film projection equipment at my cinema. Happy to answer any further questions about any of it. Talking about this stuff makes me happy.",
"Most of the Cinemas get their movies Digitally over the internet but in some cases a Modern storage device is used to distribute the movie but in case of IMAX special releases they actually ship the film reels to the location.",
"I was a booth manager at a theater for some time. Cinemark would transport film reels by ground Thursday night to be 'built up' for showings the following day. When I was leaving, they were transitioning to digital. At the time, they sent flashdrives with the movie loaded and some trailers. Plug it in an set the timer.",
"Basically, an external USB drive containing files in a proprietary format that the devices in the cinema can read.",
"I own a drive-in theatre here in Tennessee. While its a \"drive-in\", what we have in the projection booth is identical to our indoor counterparts with the exception of the sound processors. We converted from 35mm to digital projection in March of 2013. We have two screens, and our projection booths are identically equipped with Barco DP2K-23B projectors, GDC SX2000AR servers, and USL JSD-60 sound processors. These 3 components are the heart of our projection systems. Our GDC servers have a removable CRU sled drive slot that we previously used to ingest the movies from the studios. The hard drives for the movies would come in on a CRU removable hard drive (shipped either by UPS or FedEx) and the content on the hard drives are encrypted. We would take the hard drive, insert it into the projection server CRU slot and copy the DCP package for the movie onto the projection server. The way our system is setup, we have an IMB (Internal Media Block) that is installed in the side of the projector that \"decrypts\" the movie files \"on the fly\". The movie files as they are stored on the hard drives are encrypted. The movie files as they reside on the server are encrypted. The digital pathway between the server and projector is encrypted. The actual \"decryption\" takes place inside the projector in real time as the movie is being played. There is no way for us to watch the movie on a video monitor. The only way we can watch a movie is out the front of the projector on the screen. The \"decryption keys\" for the movies are sent out by the studios usually 2-3 days before we are scheduled to play the movie. The decryption keys are written specifically for our theatre. They are coded in such a way that they are only specific to our server and IMB with its own unique serial number. They are also time coded and date coded as well. A typical key will be coded for the specific movie file, in the specific format compatible with our specific hardware ( Closed Captioned, Open Captioned, 5.1 stereo sound, 7.1 stereo sound, Dolby ATMOS, 3D, Laser, etc.), and the decryption key will only be valid for X number of days, beginning at a specified time of day and ending at a specified time of day. With all of that being said, we no longer use removable CRU sled drives at our theatre. In May of 2018, we installed a DCDC satellite delivery system. Now all of our movie files, trailers, etc. come in via satellite and are stored on a big mass storage NAS which currently sits in our Screen 2 projection room. The satellite downloads all of our media content and stores it on a Kencast server. The Kencast server is tied in to our \"Projection Media Network\" which is accessible to both projection rooms. It is my understanding that the satellite downloads EVERYTHING available from the studios in current release, but only the film titles we have currently booked are visible to us on our end. When we book a title, we will receive an email from the studios a day or two later that lets us know that the title has been published to our satellite server and is available to ingest on to our projection servers. I simply go to the projection server and using the touch screen monitor on the rack, I navigate the ingest point to the DCDC server and copy the files on to the specific projection server. Once that's completed (takes about 10-15 minutes), I check my email and download the decryption keys on to a thumbdrive and copy them on to the projection server and IMB. The projection server IS the playback device. When I build a show, I choose which policy trailers to use, which movie trailers to use, and arrange the order of the content how I want it to play. Once I build the playlist and insert our automation cues, I schedule the playlist to start at a specified time on the specific days we are playing it. If we try to run the playlist anytime outside of the active window of the decryption keys, the only thing that will play is the policy trailers and movie preview trailers."
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dzznai | Does keeping my phone plugged in hurt the battery, and what is the best charging practice to keep my battery at maximum efficiency? | Technology | explainlikeimfive | {
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"A lithium battery is happiest when it's cool and between 20% and 80% state of charge. So ideally you would slow-charge it to keep the temperature down, unplug it at 80% and plug it back in before it gets too low. Leaving it plugged in isn't great because it means you're charging it to 100%, but it's not really any worse than charging it to 100% and then unplugging it. All phones will stop charging automatically once they reach 100%, whether it's plugged in or not.",
"It's pretty easy: * Don't let it run out, that's really bad for it. * Avoid using fast charging unless you need it * Keep it cool, so for instance don't leave it in a hot car or in bright sunlight. Other than that, there's little you can do for a phone battery because unlike laptops they're in constant use and these days mostly non-removable. So if you're not plugging it in, then you're running from the battery, and that causes wear."
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e03nx2 | Why do tires always look like they’re going backwards in videos of cars? | Technology | explainlikeimfive | {
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"The visual phenomenon of wheels going backwards in video has to do with the rotation of the wheel vs the frame rate of the video. The video is taken in frames per second, so there is not a continuous stream of video, and therefore the wheel will have moved ever time a frame is captured. If the rotation of the wheel is just right, it will have moved enough that the wheel will appear to go backwards. The same happens with propellers on airplanes and rotors on helicopters.",
"So video is basically just a bunch of photos taken at really high speed. How many pictures a video camera can take per second is called it's frame rate. If the tyre does a full rotation 25 times a second whilst being filmed at 25fps then by rights it should look like it's standing still because it's returning to its original position in time for the next frame. But what if we slow it down just a tiny bit? It means that the wheel falls shy of its original position in every frame giving the illusion of a wheel rotating backwards.",
"First off, they don't ALWAYS look like they're going backwards, but it does appear that way occasionally. The reason this occurs is due to the shutter speed of the camera vs the rotational speed of the wheel. Most wheels have a repeating pattern for their spoke layout, meaning it looks basically the same whether the wheel is at the start of its rotation, or only partially rotated around. So, as the shutter of the camera snaps image after image, if the speed of the wheel is such that each subsequent image is only a parital rotation, it can appear as though the wheel is a quarter turn backwards, instead of the actuality that it rotated 3/4ths of the way around. Our eyes naturally assume motion, when presented with two back to back images that support this motion, and our brain takes the most obvious choice in how that motion occurred For example, if we see an image of a ball in a pitcher's hand as he's throwing it, and then the next image the ball is a few feet away from his hand, our brain draws a conclusion that the ball traveled from the hand directly to its current position, and NOT that in that span of time the ball circled the stadium and then ended up in that position. Similarly our brains make the assumption that the wheel moved 1/4 turn backwards, instead of 3/4 turn forward because that's the shortest \"distance\"."
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e05hdg | how is time measured electronically? Like if a circuit board times five seconds how does that physically work | Technology | explainlikeimfive | {
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"If it is still the same as when I learned it (years ago), there is a crystal in the circuit board that has electricity pass through it. The energy causes the crystal to vibrate. Because it is known how fast it vibrates per second, any application in the OS (and the OS itself) is able to tell the time. Additionally, most internet-connected devices check in periodically with an official time keeper. This allows the OS to adjust for minor errors in the time caused by brownouts, power surges, or other issues that could affect the vibration rate of the timekeeping crystal.",
"Step 1: Get a crystal that, when you jolt it with electricity, starts bending and vibrating, causing measurable changes e. g. in resistance/capacitance. This is called the piezoelectric effect btw. Step 2: Make a circuit that counts those oscillations. Also make that circuit periodically re-jolt the crystal to keep it vibrating. Step 3: Callibrate the crystal so that it vibrates exactly X times per second. Now, when you count X oscillations on your circuit, a second has passed.",
"Clocks are built out of oscillating circuits. You could build an analog circuit that oscillates, but they're very fickle and inaccurate. They're prone to generating irregular signals and speeds, and they're hard to keep in tune. 555 IC timers are like this. You can tune the circuit with a resistor, but the speed is subject to the temperature of the room. Enter the quartz resonator. Quartz is an interesting material. You squeeze it, and it generates electricity, you zap it with electricity, and it changes shape. So if you make a pair of thin films out of quartz, you can make an oscillator, and it's timing is a matter of geometry, I believe. They're far more stable than an analog circuit, and they're what we use in modern computers, radios, clocks, etc. They do drift due to temperature, and for scientific purposes or high end commercial purposes, you can get a quartz clock that is wrapped in an insulator and heating element, so that it can be kept within some tolerance. They even wrap the \"oven\" in yet another oven, for even better thermal control. These are called XOXO and XOCO quartz references. These things resonate at extremely high frequencies, and electrical engineers and physicists figure out how to generate the frequency they want turn that into a counting circuit that translates that signal into units of time. Enter the atomic clock. Certain isotopes resonate at very specific frequencies. Again, temperature is important. Rubidium and Cesium are common. The oscillations of these elements are picked up by an amplifier, and that signal is counted. You'll use a reference to generate a signal that synchronize a number of circuits. You'll see this in radio, where multiple transmitters or multiple receivers work in tandem - they have to be synchronized. The signal will go down coax or fiber optics, but the faster your oscillations, the more sensitive you are to distance. If you were to try to sync two atomic clocks across the country, the length of the cable changes with the day/night cycle, as that side of the planet heats and expands or cools and contracts, making the signal take longer or shorter to get there. And then when you're talking about clocks like this, relativity gets involved, which is way above my pay grade. A clock on the top of a mountain is going to measure time different than a clock on the bottom of the mountain. You have to account for relativity in satellites, or GPS won't work."
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e066ny | How do games display a millisecond counter if the max frame rate of a normal display is 60? | There’s simply not enough frames to display the millisecond digit but lots of timers do it anyways. Are numbers skipped? Are numbers blurred together? Is this hard coded by programmers or is it coded to just output milliseconds and whatever numbers happen to align with the refresh rate is whatever shows up? | Technology | explainlikeimfive | {
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"The clocks can count in milliseconds, the screen can't show it. So what you see is typically the time the frame started to draw.",
"The timer keeps count, but the display only updates 60 times per second. The time itself is kept as accurately as the computer is capable of.",
"Are you asking about the decimal points of a frame? As in 55.3 frames a second as one example? If so there's a very simple explanation for it. The game is not measuring anything about your display at all. It's measuring what your GPU is doing. GPUs are incapable of outputting frames at even numbers. That's not how they work. They're immensely complex hardware and draw an image as fast as they can. This will never be a round number. As to this question: > Are numbers skipped? No. Frames are merged together. The display will simply draw what's in the GPU's framebuffer at specific intervals, and because the GPU does not render images at fixed intervals you'll get half of a new frame and half of an old frame stuck together. This is what tearing is, if you've ever played games with VSync off. That's what that decimal point is in visual terms. You're actually seeing the GPU render at uneven intervals. There are ways to avoid this tearing that is caused by how the GPU works. One of them is to stall the GPU and let the display be able to poll the GPU framebuffer when the framebuffer has a single contiguous frame, but this slows the GPU down and introduces latency. This is called VSync, short for vertical synchronization. It's an option you can flip in every modern PC game, and on console games it's most of the time forced on, though there are certain console games that dynamically turn it off. I know Mass Effect Andromeda for a fact does this. Another way to avoid tearing is by having a display that is able to draw images at uneven intervals, meaning a display that can change its refresh rate dynamically, so that it can synchronize exactly with how often the GPU draws images. These are called Freesync, G-Sync, or Adaptive Sync displays, and they're relatively new to gaming. They fix the issue of tearing without having to stall the GPU and introduce latency and performance hits."
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e07g7h | Why is the black of a TV not on a channel or in between programmes not as dark as a TV turned off? | Technology | explainlikeimfive | {
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"Depends on what type of screen you have but many modern TVs have a backlight. The screen then blocks the light to produce a dark area most would consider to be black. The blockage is not 100% effective, so it is brighter than when the backlight is off."
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e07zxe | How does active noise cancelling work? | Technology | explainlikeimfive | {
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"Noise cancelling headphones have a built-in microphone. This microphone catches the sounds that surround you, inverts them and plays the inverted sounds into your ears. The inverted sounds are the exact opposites of the surrounding sounds, and opposites cancel each other."
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e089ns | how do lots of people in the same area’s Bluetooth devices work without interference? | Technology | explainlikeimfive | {
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"One technique is by dividing the bit of the radio spectrum into channels, much like channels on a television. But there's only about a dozen channels, which isn't enough for 'lots of people'. So as well as channels, a technique called CDMA is used. Basically, you have a shared, randomly generated signal between a pair of devices. If you like, you can think of it as being like a voice. You then use that to generate the actual signal that you broadcast. What this means is, you can listen out for the shared signal, and use it to find out what was sent. This is a bit like talking to someone in a crowded room, and picking out the voices you want to listen to, but far more mathematical. If the room is too crowded, you simply won't be able to hear your friend over the noise. Bluetooth can similarly be overrun by noise, but you'd need a lot of bluetooth devices in a relatively small space."
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e0a1gy | Why does putting the air conditioner on 25°C in a cooling mode feel different from the same 25°C in heating mode? | Technology | explainlikeimfive | {
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"The unit isn't putting out air at 25 C. If it's in cooling mode, it's putting out very cold air until the ambient temperature reaches 25 C. If it's in heating mode, it's putting out very warm air until the ambient temperature hits 25 C.",
"In cooling mode, the thermostat will wait until the temperature goes over 25°C and then turn on the AC until it falls back under 25°C. This produces a 'spike' of cold air when the AC is on, followed by the temperature slowly drifting up toward warm. In heating mode, the thermostat will wait until the temperature goes under 25°C, then turn on the heater until it is back over 25°C. This produces a 'spike' of hot (and dry!) air when the heater comes on, followed by the temperature slowly dropping back down toward cold. Naturally, these feel different from one another.",
"Humidity is also important. Air can hold a certain amount of water. The closer it is to capacity, the less additional water it can absorb and the more humid it feels. The farther from full capacity it is, the more water it will absorb and the drier the air feels. Hot air can hold more water than cold air, and the A/C doesn’t change the amount of water in the air, it just adjusts the temperature. So if you start with cold air, there will be very little water in it, because it can’t hold much, but because it can’t hold much, that little bit of water gets it most of the way to full, so it doesn’t feel very dry. If you heat that air up, there is now a lot more room for water in the air, but it is still only holding that little bit of water, so now it’s going to feel very dry. If you start with hot air, it has more room for water, so it will be holding a good amount of water. Cool it down, and now it has less room for water, but is still holding that larger amount, so it feels more humid. If you’re heating the air to 25C, the end result is going to feel drier than if you’re cooling the air to 25C, because the amount of water in the air to start with is likely to be different depending on which direction you’re coming from temperature-wise.",
"Don’t forget: you perceive the average radiant temperature of your surroundings. In summer with HVAC at 25C, the walls might be 28C so you feel warm. In winter with the HVAC set at 25C, the walls could be 18C, so you feel chilled. Also, HVAC is always playing catch up- if the unit is on in summer, the air is warmer than 25, if it’s in in winter the the air is cooler than 25.",
"Top tip: if the day is t too hot but it’s really humid, some air cons have a ‘dry’ mode. Use this to remove the moisture front he air and the air will ‘feel’ cooler whilst using less energy",
"Humidity. If you heat to 25, chances are it is colder outside and dryer, so the humidity is lower and it feels colder. If you cool to 25, the opposite is in effect.",
"Mean radiant temperature also plays a part, a heated room will have colder walls and you will feel less radiant heat from them. A cooled room will have warmer walls radiating more heat towards you.",
"This actually has more to do with the humidity of the air. When your unit is cooling mode, the air’s humidity is reduced. With the reduction in humidity it is easier for our bodies to evaporate sweat, carrying off some of your heat. Heating increasing the humidity of the air, which will slow down the rate of sweat evaporation, making you feel warmer. Most people like a humidity of 40-60%.",
"Moisture/humidity. Key factor to get to the standard \"comfort zone\" in heating and air design. Combine latent temp with actual temp at the standard levels and as long as the unit is properly sized and removing the moisture during summer you feel comfortable. In winter the heat is dominate with less moisture so often it \"feels\" different to different people. The standard is pretty close for most people though. If you add a humidifier to your system you can control the psychometrics and feel more or less the same year round indoors if you wanted to go that far."
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e0g57f | Keeping in mind the advancements in phone cameras and handheld cameras, why are cameras used in television studios still so bulky? | I was watching the US impeachment hearings and noticed the press videographers carrying bulky cameras, which prompted this question. | Technology | explainlikeimfive | {
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"I’m a feature film camera man and advances have made our camera bodies pretty small (see the Alexa mini). However, by the time you add all the accessories we need it gets pretty big and heavy. These accessories include batteries, wireless video transmitter, wireless focus motors, extra focusing monitor, cage to attach all that stuff, focusing range finder, viewfinder, tripod plate, lens, matte box and filters... the list goes on. In the end a 7 pound camera body ends up being 40-50 pounds with accessories.",
"Great minds think alike. I've searched tha seven seas fer an answer. Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why do television camera crews use very large cameras to film, but my go pro cam shoots HD and is smaller than my fist? ]( URL_0 ) ^(_7 comments_) 1. [ELI5: Why television and media cameras are so big, despite the same level of picture detail being achievable on much smaller devices? ]( URL_1 ) ^(_71 comments_) 1. [ELI5:Why do TV news camera people carry around gigantic shoulder mounted cameras when there are so many smaller options? ]( URL_2 ) ^(_33 comments_) 1. [ELI5: What do those massive shoulder mounted TV cameras do that a nice handheld video camera cannot? ]( URL_4 ) ^(_21 comments_) 1. [ELI5: Why are tv cameras so big while the GoPro can shoot 4k in the size of your hands? ]( URL_3 ) ^(_3 comments_)",
"The main reasons are that high quality lenses are still large and broadcast quality cameras need room for all the accessories to attach to like viewfinder etc.",
"They are getting smaller. I work at a small TV station, and we switched out a lot of our bulky ENG (electronic news gathering) cameras to the Sony FS5 and FS7. Which are about half the size with many of the same features. They also have a 35mm full frame sensor, which makes them useful for shooting other types of content. There's a couple of reasons you'd still want to use the big cameras though. They're better balanced for handheld. It's easier to keep a steady shot. They do make shoulder mounts for the smaller cameras, but I find they're actually a bit more difficult to use. They're very front heavy, so it's harder to keep a steady shot. ENG cameras also typically have more inputs, outputs, and mounts for accessories. A popular one is the Dejero EnGo, which clips to the battery slot and allows a single camera to broadcast live wherever there's a cell signal. Which completely eliminates the need to roll a microwave truck for live news hits. With the small cameras, you'd need to lug around a separate lunch box sized unit. They have three monochromatic sensors inside, which in theory should give you better chroma and luminance signals. Though I'd argue this isn't as big a deal in the digital age. EFP cameras (which resemble ENG but are wired) can be remotely controlled from a broadcast truck or control room. Most of the small cameras lack that feature. Lastly cost. Broadcast cameras are very expensive so TV stations will keep them for several years. This is one of the big reasons why so few stations are broadcasting in 4K."
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e0jh3p | Why skyhooks isn't a thing | Technology | explainlikeimfive | {
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"Like many space technologies, the skyhook is a solved physics problem and is now a material science problem. Space elevators are in the exact same boat, we simply don't have a material with high enough tensile strength to withstand the forces involved. You want the end of your skyhook to get you into LEO which requires moving at 8km/s. If you use a 200km skyhook to get you there then you'll be experiencing ~32 Gs of force. A 1 mm^2 carbon nanotube cable can support ~6400 kilogram-force which means if you want to get a 200 kg payload to orbit you'll need a 1 mm^2 cable because its force will be 32x its mass. Bad news, your cable also weights 140 kg so it can't achieve that, you are restricted to only about 100kg. As you start trying to lift larger payloads you need a thicker cable to withstand the forces but the mass of the cable ends up exceeding the strength of the cable fairly quickly. We don't currently have a material with the necessary tensile strength/kg to construct space elevators, orbital tethers, or many other dream techs",
"It is definitely a real thing that we could build in theory, the physics check out. The problem is that unlike a space elevator (for which we do not yet have the materials to build one) it won't get you into space by itself. It will only be part of the equation you still need some fast rocket or hypersonic plane to get your cargo into the upper atmosphere and up to hypersonic (but not quite orbital) speeds to rendezvous with the tip of the skyhook. It also needs to either be boosted up periodically. Either with rockets (in which case you don't really gain much of an advantage) or by dropping down cargo from space to earth. It would also take a lot of effort to work out all the details. Hooking a cargo at high altitude while both the hook and the cargo fly by at extremely high speeds is not exactly easy and has to be gotten right every time or you destroy the hook and the cargo you are trying to hook. Also it takes quite a bit of effort to construct such a thing in the first place. Much more than anything else we have build or put into space before. It would not be cheap or easy at all. The potential return of the initial investment could be big as it would make going into space cheaper but there is quite the hump there that one would need to get over. This can only really work if you have the need to put lots of stuff into space and have the money to put a big infrastructure into space first and build it at the same time as lot of other infrastructure on earth and out is space to keep it going and justify the cost of setting one up. It would be like a bridge to nowhere at this point. Not enough traffic to justify the cost of building it.",
"Because all these amazing ideas that Kurzgesagt have highlighted would involve costs that require several countries working together. Nobody is that committed to looking to the future, when you're more likely to get votes if you spend money solving short term problems in your own country.",
"Because you don't get free energy. The skyhook itself needs to be lifted from Earth. As a payload. With rockets. Then every launch lowers its orbit so you need to boost it. With propellant. Which has to be lifted from Earth as payload. With rockets. Now, you can catch incoming vessels and slow them down to gain the energy, but there aren't any incoming vessels. And even if they were, you have literally seconds to catch the end of the hook at orbital speeds and if you miss it - off you go into the open space and there is nothing that can stop you. The craft is lost into the darkness unless it carried enough propellant to slow itself down, just as a precaution. In which case, what do you need the skyhook for, anyway? Edit: on the other hand there is a solution to make it better. Bring propellant from other places with lower gravity well. For example, get propellant from Moon, move it to skyhook (at very little cost compared to getting it from Earth) and then use Moon propellant to lift Earth objects. It would increase the efficiency (especially when the Skyhook itself can use propulsion methods more efficient than rockets as it can exchange huge thrust for long action time). You are still using the same energy to lift the payload from Earth, but you are not using it to lift propellant and all the heavy rocket engines from Earth.",
"Good question. Let’s start from the top. Kareem Abdul-Jabbar truly popularized the skyhook and became its poster boy, but he wasn’t its inventor. That honor belongs to George Mikan, Hall of Fame center for the Minneapolis Lakers in the 1950s. Mikan may have been the first truly dominant big man in league history. Through his first three seasons in the league, Mikan averaged 28.0 points per game. He was a pioneer of the game. He was known for his finishing around the rim (the Mikan Drill is named after him), especially his hook shot. [They made a statue of it!]( URL_0 ) Mikan’s contributions to the game of basketball are widespread. However, Kareem did not watch him play. He did watch Cliff Hagan, though. Hagan was also a Hall of Famer. He scored 25 PPG in the 1960 season for the St. Louis Hawks. (Random fact: Hagan helped lead the Hawks to the NBA Finals, where they lost in seven games to Bill Russell’s Boston Celtics. In the final game, Russell scored 22 points and recorded 35 rebounds, while Hagan scored 19 on 7-17 shooting from the field.) Like Mikan, the hook shot was a significant part of Hagan’s offensive game. Kareem saw this which confirmed that the hook shot could be used at the NBA level. In eighth grade, Kareem faced off against older, stronger, and equally tall defenders. He needed to beat them with his skills — dunking all over them wouldn’t work. So, Kareem was forced to learn the hook shot early on. He says it was the only shot he could actually shoot over these large defenders. In college, Kareem played for the UCLA Bruins. During his collegiate career, the NCAA infamously banned dunking. Once again, Kareem was forced to utilize his crafty hook shot around the rim. And he did. He broke scoring records and won three national championships in his three seasons at UCLA. Kareem lost just two games in his college career. Banning dunking didn’t stop him from dominating — it just helped him master his hook shot. We all know what happened in the NBA. Kareem’s signature hook shot, the “skyhook” because of the extremely high point from which he released the ball, helped him set the all-time NBA scoring record, win six MVP awards, and six NBA titles. He is regarded by many as the third greatest NBA player of all-time, behind Michael Jordan and LeBron James. So, back to the question. Why isn’t the skyhook used today? One possible reason is that it isn’t flashy. Assistant coach Mark Bryant once said, “You aren’t going to get any commercials shooting the skyhook. Only [Kareem] got commercials shooting the skyhook.” Big men these days aren’t posting up nearly as much as they did in past eras. Shooting jump shots is a much bigger staple of the modern game because jumpers tend to be more efficient. Of course, the skyhook is very efficient when Kareem is using it. He would still dominate in today’s league, especially with the extra spacing, but that leads us to the second point. It’s hard to master — not everybody is Kareem. Kareem spent many, many years working on the skyhook before he mastered it. A player today would have to put a similarly large amount of time into perfecting the move before they could reasonably use it in a professional basketball setting. But most of these players don’t *need* to. They’re bigger and stronger than everybody they face before the NBA. Why waste your time on learning a fancy hook shot when you can just exert your physical superiority? Kareem happened to need it in youth leagues and in college, dunking was literally banned! While the skyhook is unlikely to return to the league unless a player wants to pick it up from a young age (imagine that in the AAU), players who learn to thrive on more than athletic dominance will continue to find success in the NBA. We already discussed Kareem, but look at Luka Doncic. He dominated the second most competitive basketball league in the world as a teenager despite facing stronger, bigger, more athletic, and more experienced players. He was literally a boy among men, yet he thrived. Don’t get me wrong, Doncic isn’t some unathletic scrub, but he isn’t LeBron or Giannis. Playing against better competition forced him to hone his fundamental skills, and now he’s playing like a top-5 NBA player despite being just 20-years-old. Meanwhile, many great college athletes are just physically superior to their fellow teenagers. Of course they’re gonna look good. That isn’t indicative of how good they’ll be in the NBA when facing off against equal talent.",
"I don’t think there’s enough material leaving orbit on a daily basis to justify something like that. If we had orbital habitats or construction yards, sure.",
"We know the theory, we have the materials (though some practical problems would have to be solved to make a 250km, or longer, long nanotube cable. At least it's far more feasible than the 5000km cable needed for a space elevator). However, a skyhook is like a bridge. We need somewhere to go for it to be useful. The day we get a city (not just an outpost) on the moon or mars is the day we'll get a skyhook.",
"Economics. While the end result would entail a system that can get cheap space access, there would be an immense amount of R & D to develop, test, and commercialize such a system. Likely one could just do rough math and see that the higher cost of proven chemical rocket systems is still much worth the decade(s) of R & D, especially when commercial entities fill a purpose of providing a profitable service to solve a problem within a much shorter time frame, and particularly more so when cost for efficiency improvements in chemical rockets are known and cheaper than a whole sale reconfiguration of launch technology."
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e0ji72 | Why are some batteries rechargeable, and some are only single use? | Also, what would happen if someone tried putting a single use battery onto a charging station? | Technology | explainlikeimfive | {
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"Basically, think of a battery like a balloon: it contains a bunch of air, which is like the energy in a battery, that wants to get out. With a regular battery, it is sealed completely closed and the only way to get the air out is by popping it. With a rechargable battery, it's like instead you untie the baloon, let the air out, and blow it back up. Doing it the first way is single use, but it's cheaper to mass produce them this way and they don't lose air over time if you leave them for a few weeks. Putting a battery in a recharging station will do the same thing as blowing up a balloon with a hole in it: the energy will immediately escape and it won't retain any.",
"Lot of people have explained *how*. The *why* is that primary (non-rechargeable) cells store a lot more energy per unit mass and self-discharge at a much lower rate. A remote control with a couple of alkaline AA's will run for a decade or more while the same remote with rechargeables will self-discharge within a year. Primaries are better where it needs to stand a really long time between uses, where there are short bursts of very high demand, and where the battery cannot be easily accessed to recharge or replace. Rechargeables are better where it can be conveniently recharged, where the demand is fairly constant and where the consequences of a dead battery are fairly small.",
"It has to do with the reversibility of reactions. A convention for electricity is current, a measure of charge flow per time, most commonly, and as in batteries, propirtiinal to electron flow. Electrons flow because the reaction in the batteries make it favorable to do so, to simplify a bit, because it's going to want to go in a certain direction according to the changes in charge distribution as the cell/battery undergoes the chemical reaction. Normal batteries have a non-reversible reaction where this electron flow can't be reversed despite a large applied in the opposite direction by a conventional outlet. Electrons in reversible batteries, however, will move in the opposite direction to restore \"charged\" status and made useable again.",
"It comes down to price, and savings. If I'm manufacturing something that could conceivably be single- or limited-use (say, a flashlight, or a vape pen), I can leave out the components (that probably cost me a few pennies to < a dollar a unit) that allow for a recharge, even thought the battery unit is the same as in the rechargeable versions. That saves me money, and I can still sell the unit for close to the same price as the non-rechargeable type. Yay money!! Alternately, I can take batteries manufactured that have some kind of shortfall (don't test out to hold a charge as long, or charge as quickly as I'd like, for example), and use them in a disposable version of a product, instead of them going to waste. Waste not, want not! As for the charging station question. It should work fine, if the battery has been through limited cycles. See this [article about doing it]( URL_0 ) with alkaline batteries. There are some caveats about build-up in gasses in the batteries, so be careful--another reason why some batteries are disposable--it may have some risk in trying to recharge it."
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e0jm3c | With all the technology, why can’t they make a vacuum quiet? | Technology | explainlikeimfive | {
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"Actually, they can. The problem is that first this costs money (you'd have for instance to make a bigger vacuum to add material to dampen vibrations and noise), and second people think silent vacuums aren't powerful. There's also such a thing as a central vacuum where you install a big vacuum motor in the basement and run vacuum lines around the entire building. This is of course not easy to install, but it would reduce the amount of noise upstairs by a huge amount.",
"They can and have made quiet vacuums. When they were put on the market people people were unsure of whether or not they were working so they are purposefully made loud. URL_0",
"IMO, consumers don’t like things that are quiet but “shouldn’t” be. For example, BMW has models of cars so quiet, they produce artificial sound through the speakers.",
"They can. But you don't really want a quiet vacuum, you want a quiet vacuum that costs and performs exactly like a regular one. That's what most product features come down to, what consumers choose to spend their money on. If it was a choice between a $300 and a $600 vacuum, is $300 worth slightly less noise a few hours a month? For most customers, the answer is no, so manufacturers aren't building quiet vacuums no one will buy."
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e0kpps | how do phones take your voice and make it come out of another phone? | Technology | explainlikeimfive | {
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"With modern technology, it goes like this: Your voice moves a diaphram/magnet in the microphone of your phone (or a similar technology). That magnet is inside of a coil of wire, and the moving magnet induces a small electrical current in the coil. That signal is amplified and turned into a voltage by circuits in the phone. That [voltage waveform]( URL_1 ) of your voice is then sampled (measured) many times per second, turning it into a stream of numbers that represents the same thing. Those numbers are stored in binary (1s and 0s) because that's what digital computer circuits can easily manipulate. Now the phone needs to send that stream of binary numbers somewhere, like a cell tower. It initiates a call over radio (light that is so deep red that our eyes can't see it). The radio signals are [modulated]( URL_0 ) to carry information that the cell tower can decode. After the connection between the cell tower and your phone is set up, the phone sends that stream of binary numbers to the tower. Of course, it also sends other information first, most notably what number the call is supposed to go to and who it is from. The cell tower has information about where to forward that data, usually over a land link (wires) to a central switch, which then forwards it on to another switch, etc. etc. until it gets to a cell tower near the recipient's phone. All of this data communication is similar to that between your phone and the tower, except it isn't using radio. The voltage signals are sent using various encoding schemes using regular wires or optical fiber links. If optical fiber links, the signals must again be converted to light, but not radio. Eventually the data gets to the cell tower nearest the recipient and the process goes in reverse, with that stream of numbers getting to the recipient's phone and turned back into a voltage/current to excite a speaker in the phone, turning it into sound. Of course, all of this happens very very fast. Computers are good at that.",
"The process revolves around the idea of digital modulation, whereby the levels of sound are measured and translated into digital electrical signals (encoding). This signal is then passed and relayed across various forms of media to the intended destination which then translates the signal back (decoding). The corresponding sound waves are then recreated based on the levels originally provided (more or less) and you hear the caller's voice."
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e0n0xr | When you install a new browser it asks whether you want to transfer data from other browsers on the computer. If its that easy to retrieve data for all my accounts on a browser why stealing data is not as common as transfering files? | Technology | explainlikeimfive | {
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"Because websites displayed *inside* your browser do not have permission to access all your files. The browser won't do it.",
"All that transfer is doing is reading bookmarks, browsing history, cookies, saved form data (including usernames/passwords), etc. It's not transferring the data they're related to (i.e. it will save your banking username/password, but not the data stored on your bank's server). Also, files stored on your own computer are relatively safe (unless you download malware). Things that can be retrieved via the network are at risk, especially if they're in the databases for well-known companies and are unsecured (passwords not encrypted, etc.). Things on your PC that don't go over the network are generally secure. E.g. Windows is now allowing you to sign in with a 4 digit PIN instead of a long complicated password. While this seems insecure at first, it's actually more secure because that PIN is specific to your device and is never transferred over the internet whereas the password was transferred (albeit encrypted). Does that answer your question? Edit: 4 or 6 digit PIN, I can't remember the length.",
"A new browser you just installed is running under your user account, which means it has exactly the same permissions as you do. If you can access a particular file on your computer (including another browser's data files), so does the browser. Which is why a malware application running under your account will be able to steal everything you can access. A website, on the other hand, is running in a sandboxed environment inside a browser. It will only be able to access what browser allows it to access, which does not includes your file system. Besides, I am not sure you can actually import sensitive information from other browsers. Bookmarks, sure. Passwords? I have Edge and Chrome installed on my PC. Edge did NOT manage to import my passwords from Chrome which is expected, since they are supposed to be encrypted. Chrome only proposed to import bookmarks from Edge."
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e0tc4v | Why do podcasters use headphones? | Technology | explainlikeimfive | {
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"When you are working in an environment where you’re being recorded, you typically want to hear the entire program (Sfx, background music, reverb) Having speakers to do this is problematic, as they’d need to be in the same space as the folks being recorded - and feedback loops between mics and speakers becomes an issue. The easiest solution to that problem is to isolate the output - by using headphones. The talent can hear what’s going on, and all is well. Additionally they might also have a talk back circuit to hear producers or directors in the control room.",
"Many podcasters want to listen to themselves and their guests through the recording system to make sure their levels are good. Doing so with speakers could cause feedback which sounds terrible. Headphones are the easy answer."
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e0tllm | Why, on some screens, do images appear dark and inverted when looked at from a certain angle? | Technology | explainlikeimfive | {
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"All screens do is reflect light, so it will reflect light in a sudden angle. Also computer monitors have reflectors that make the light reflect in all directions to improve viewing angles.",
"The screens you are talking about are called TN panels. TN (Twisted Nematic) panels is a type of LCD display that 'twists' liquid crystals using electricity. This twisting changes the color of the pixels that goes into your eye. Now, if you look at a high angle to the side, you will see the other sides of the twisted liquid crystals, so you will see inverted colors."
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e0vahw | what happens if I plug a charger into my phone that's already wirelessly charging | Technology | explainlikeimfive | {
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"The wired charger takes over. The power FET inside the phone prioritises the more effective charging method (wired, of course) and connects only to that source.",
"It will continue to charge as you want it to. But you might also implode the universe so maybe just use one or the other."
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e0wyg7 | Why is upload slower than dowload? | Technology | explainlikeimfive | {
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"Your money buys you a fixed amount of speed, which can be allocated to either upload or download. Most consumers download way more than they upload so most consumer internet is simply configured to allocate most of the speed you are buying to downloads. Business grade internet OTOH is usually available in a variety of configurations. A lot of business choose to split the speed they are paying for evenly between upload and download. This gives them uploads that are just as fast as their downloads."
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e0zq0i | when a barcode or QR code is scanned,we get some numerical information like a multiple digit number or a few words. Isn't it more convenient and easy to write that info instead of making a bar code and then scan it to get the orignal?? | Technology | explainlikeimfive | {
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"Barcodes are a font. Instead of seeing abcdABCD you see the bars. It's difficult for a human to read the bars, but extremely easy for a computer to read the bars, and that's what the font was designed for - input data into computers or cell phones. Typically the barcode is used like this: someone types some information in a computer and prints out a barcode. Someone ELSE uses a scanner or phone to read the information. Shipping labels, links to websites, electronic payment, all of these are SOMEONE ELSE using the barcode that you \"wrote\". So, no, the convenience is in making it easy for someone else's device to interact with whatever label the barcode is placed on.",
"To add, barcode or qr code have fixed width or dots placement area so it is very hard for computer to make an error as opposed to sentences of alpha numeric."
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e13lcy | What is a protobuf? | Technology | explainlikeimfive | {
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"It's a standard and set of tools developed by Google for data serialization. Serialization is the process of taking structured data in a programming language and translating it into binary data that can be sent over a channel that wouldn't understand the structure, e.g. a network connection that only understands how to send a sequence of bits. Protobufs in particular were meant to be a cross-language standard. Many languages have ways of taking some structure, encoding it, and then decoding it into the same structure, but this gets very hairy when you try to cross languages. Protobufs were developed to be a kind of least denominator between some of the most commonly used programming languages (at least at Google), such that sending from Python to Java to C to C++ to Go would all work fine. The actual code content of protobufs are .proto files, which define the structure of the data, and a compiler from .proto files into various languages. So in a proto I could define message Point { required int32 x = 1; required int32 y = 2; optional string label = 3; } And then run this through the protobuf compiler. This will, in C++, create a Point class which demands that the x and y values always be set, allows you to set label, and has a method for telling the object to output a series of bits representing its structure. It also has a method for taking a series of bits and creating a new Point object. It will do similar things in the other languages. So, you could serialize this in C++, send it to a Python program, and then Python would deserialize into something that, while it might have a completely different internal representation, also has the same two numbers and a string."
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e158rr | How can apps like Google Maps or Waze be so consistently accurate with their predictions for ETA? | I know they have satellites and data and whatnot, but I’m constantly surprised at how they’re able to predict with such high accuracy. | Technology | explainlikeimfive | {
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"they draw upon their large userbases to make this assumption: \"anywhere with any traffic will have at least a couple of our users caught in the traffic\". They can also take advantage of the fact that you can break down segments of a journey and make time measurements on individual segments of road. let's say you want to get from A to B to C to D. First step is to get other users data from users who's route included A to B recently. for example, a van driver 5 minutes ago made a route X-A-B-Y, passing along A-B. This prediction on it's own might not be much use, because the van driver made a stop to drop off a delivery and got caught in a traffic light. Not to worry, since 10 other users had journeys including the segment A-B. The algorithm can average/filter out all the results for segment A-B to get an average route time, taking into account traffic jams and things that will definitely slow you down, and rejecting disturbances that won't affect you. Bear in mind as well, this data will be going back in time for years, so it will build up data relevant to the time of day, day of the week, etc.. for example if you travel at 3am, the data will show that historically, cars travelling at 3am travel A-B really quickly, so it will compensate for that in the ETA. Now all it has to do is break down your route into individual segments and repeat this method across the whole route, allowing it to build a very good estimate of time. All this depends on having a large userbase, say 10-20% of drivers have google gathering location data, having accurate and quickly delivered location data. They need to be able to break down the route into small segments, typically lasting from junction to junction, and be sure that a given vehicle actually took this route. it needs also to be time-accurate since traffic data is so rapidly shifting. They also need lots of storage and computation power. typically for something like this, the servers will spend most of their time providing live estimates to users, and during the quiet hours at night the servers will revise the days data to get their data for the day into an easily useable form for future predictions.",
"They use two things. First is using the speed limit of the roads on your route to determine a total travel time. Second is taking in to account the speed at which other users of the apps are moving on roads on your route to determine what the average flow of traffic is."
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e16lss | How come you can still make emergency calls when there is no signal? | Technology | explainlikeimfive | {
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"There is a signal if you can make emergency calls. It may not be your carrier's signal, so you can't check strength or make normal calls, but if you can make an emergency call there's a signal (there's few if any spots in the US where there's zero carrier signal)",
"All carriers have to accept the call to the emergency number from all cellphones that can talk to there network. So if you are in a location where your cellular provider does not have coverage som other do you can make emergency calls. They should be able to do that anywhere in the world, there is not even a need for sim cards. Even if the phone is locked with a pin code or any other access control you should be able to call the emergency number from it without unlocking it. There have been multiple incompatible phone standards for 3g and older standards but for 4G and later there is only one. The same standard can use different frequencies in different parts of the world and all phones cant use all frequencies. So if your phone physically is capable of communicating with the network another cellular provider anywhere you should be able to make an emergency call.",
"When your phone shows that you have signal it means that you can connect to the nearest point of YOUR network. When you do not have signal, it means that no antenna of your network is around, but you can still make emergency calls by connecting to ANY antenna of any network that is around you."
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e17vmx | What is actually being paid for when people purchase broadband or mobile data? | Not sure whether this belongs in technology or economics or both, but either way, the internet is not free to use. For people not in the know about the technical side of the internet, the whole thing seems pretty abstract, and the idea that there can be no WiFi but you can pay for magical extra internet in your phone seems confusing and arbitrary. So anyway, when you pay for internet access in some form or another, where does the cashflow end? What physical thing or process is being paid for that allows the internet to function? | Technology | explainlikeimfive | {
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"It depends on what you call internet. Cell phone and wi-fi via cellular (or even old school analog) internet is a different set of technology at the customer level then home internet like cable, fibre or DSL etc. A cell phone vs. a cable connection to your house for example. Both the wireless company and the home internet company meet at what is called an Internet Exchange Point that connect cities, states and countries. Your bill is essentially an agreed upon fee for the use of these networks as well as whatever local hardware is required."
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e18e8n | Do blue-light-blocking glasses with completely clear/colorless lenses actually do anything? And if so, how? | Extra credit question: How should one shop for them if it would be so easy for a company to just sell ones that do nothing? Thanks for taking any time at all to read my curious questions and provide any answer! 😊 | Technology | explainlikeimfive | {
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"There's not any proven evidence that blue light is harmful but if your looking for lenses with blue filter there's a product by essilor called an essential blue filter that filters 20% of blue light and if you add crizal prevencia anti glare it will give you up to 30% uv blue protection. Anything higher than that will start to discolor the lenses into a yellowish color. I work in the optical field.",
"I wear prescription glasses with that blue light treatment, everything is just a shade yellower but barely noticeable. My headaches stopped right after I got them. I love it because I used to spend a lot of time around computers and driving is easier because I don't get hit by the damn LED lights some cars have nowadays."
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e19tx1 | What makes a port and connector on a computer’s limit for data transfer and why? (Ex. Usb, hdmi, thunderbolt) | Technology | explainlikeimfive | {
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"Three things: 1. Physics. There is only so much information you can pump down a particular kind and length of cable and still have it be usable on the other end (bandwidth). To get more information across, you need a better cable (or multiple cables), which is more expensive, larger, thicker, etc, or you need to limit your length. It boils down to how high a frequency you can send down the cable (the higher the frequency, the more information you can send across), and how much noise is introduced, both from imperfections in the cable and outside sources. For example, you can buy very thin and flexible HDMI cables, but perhaps only up to 3 meters, while you can buy thick ones up to 10 meters easily. This is because the thin cable is worse at transmitting the information, so a 3 meter but thin cable might have the same performance as a 10 meter but thick cable. If you try to extend the thin cable to 10 meters, the signal will be degraded too much and it won't work. 2. Modulation. In order to actually use all that raw bandwidth of the cable, we need to somehow encode the raw digital data (ones and zeroes) into some kind of voltage that gets sent down the cable. The way this is done can be extremely simple, like literally just saying \"1 is 1 volt, 0 is 0 volts\", or extremely complicated schemes using many frequencies and hundreds of voltage levels. This is called modulation, and if you've ever used a *modem*, that's what it stands for (**mo**dulator/**dem**odulator) There is no way to use absolutely 100% of the theoretical maximum bandwidth of a cable, but we can get pretty close with more and more complicated modulation schemes. However, those also require more expensive hardware on both ends, and more power to make work. Simpler modulation schemes are cheaper and lower power, but might only be able to utilize a fraction of the bandwidth of a cable. For example, USB 1.1 has two speeds (1.5Mbps and 12Mbps), and USB 2.0 added a third speed (480Mbps). All of these use the same cables. Why have the 1.5Mbps speed when you could always just use 12Mbps in the first version? Because the 1.5Mbps modulation is simpler, so you can use simpler and cheaper electronics, and it's good enough for things like a keyboard or a mouse. When USB 1.1 was designed, even the 12Mbps scheme was pretty simple, so it wasn't using the full potential of the cables. Therefore, USB 2.0 came up with a third scheme that could run 480Mbps over the same cables. There's actually a cheat in USB 1.1: devices are allowed to use lower-quality (cheaper) cables that only support the 1.5Mbps speed, but *only if they are permanently attached to the device* (like a mouse with a cable that is not removable). This is so that you can't accidentally use a cable that is only capable of 1.5Mbps on a 12Mbps or 480Mbps device. USB 3.0 added a 5Gbps speed, but that wouldn't work over the existing cables, so USB 3.0 requires new cables (with more and higher quality wires inside) to be able to achieve that speed. It's just not possible over USB 2.0 cables, due to physics. 1. Protocols. Above all this hardware dealing with getting the data across (what we in the business call the *physical layer*), there are a bunch of complicated rules for how data is to be formatted, broken into packets, how different devices agree on what data to send, what timing is allowed (it's okay if a hard drive slows down a bit, it's not okay if a video frame does not get to your monitor in time), how to combine multiple transmissions into the same wire when multiple devices are sharing it (like using USB hubs or Ethernet switches), etc. All of these things are different for each protocol/standard (USB, HDMI, Thunderbolt, etc) because they are designed for different things, and they also further limit the speed at which the system can run. For example, although USB 2.0 is 480Mbps at the physical layer (bits on the wire), in *practice* you're going to get up to about 340Mbps transferring data to/from a single device on a USB 2.0 connection, due to all the extra complexities in the system (70% efficiency). Some protocols are better than others - for example, Ethernet by default is about 94% efficient, and with a special configuration called *jumbo frames*, can go up to 99% efficiency.",
"Physics, economics, practicality, compatibility... a host of reasons actually. Take HDMI for example. It is a format for transmitting video signals. Since video only needs to be updated at the frame rate of the display, there's no compelling need to transmit beyond that rate. USB is similar. It was designed decades ago when computers were much slower. So speeds are limited in order to maintain compatibility with older equipment."
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e1cx61 | Why do some street lights in America cast an orange light instead of a bright white light. | Technology | explainlikeimfive | {
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"They are called low-sodium lights, and have a warmer (more yellow) color of light. Metal Halide or LEDs are generally bluer (higher color temperature). Super ELI5, different types of materials make different colors of light.",
"It's the type of bulb. Orange lights are generally a low pressure sodium bulb. They used to be fairly efficient by comparison to other types decades ago, so the infrastructure was based around them for years. Other types didn't warrant the infrastructure change until the last few years. Leds are much better, but it's expensive to change.",
"It's a different type of lamp. [Low pressure sodium lamps look like this]( URL_5 ) and are responsible for giving out a single colour of vivid yellow light. It's a deep, monochromatic yellow light meaning a scene lit by it it looks effectively like a yellow 'black and white' image. There's no way of telling any colours, because the yellow light is so pure. [Here's]( URL_3 ) a room lit with low pressure sodium vapour, to give an idea of the 'black and white' monochromatic nature of the light. [Here's]( URL_4 ) an outdoor view using LPS lamps. They were used originally because they're actually a very efficient light source, but there are other lighting solutions that are more efficient, and more advantageous because you can actually recognise different colours under them. The whiter but not pure white lights are [high pressure sodium lamps]( URL_1 ) High pressure sodium, are closer to white (but still quite yellow), so they give some ability to see colours under them. They always tended to be used on highways and so on, because they give out brighter light. [Here's]( URL_2 ) an example. Modern street lamps tend to be either [Mercury Halide lamps]( URL_6 ), which give out a very intense white light, or [LED]( URL_0 ) which give out probably the best light for seeing colours under, and they're probably the most energy efficient. Ironically, back in the day like a hundred years ago, the first big street lamp technology (once we got past rather rubbish gas lamps) was carbon arc lighting. These gave out a [super intense white light]( URL_7 ), but needed a lot of power, and needed the electrodes replacing regularly. Which is why they're not used nowadays."
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e1db2b | How can mobile games support themselves by running ads for other mobile games? | I recently got into one of those shitty mobile games that runs ads between levels and I have noticed that every ad is for another mobile game. So... the more successful other app devs are at stealing your players, the more money they'll pay you. Am I the only one who sees the problem here? | Technology | explainlikeimfive | {
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"welcome to the hyercasual game matrix where games are owned by same company. eg voodoo, ketchapp, lion studio, etc",
"I think most people are missing the actual question here: a game is free, and makes its money by advertising other games that are free that make their money by advertising other games that are free that ...etc. The question is, if it’s all a loop, how could they possibly be making money? Like they’ll make money from ads but also spend money on ads. ONE of these games in the chain needs to be making money from outside sources, otherwise it’s a closed system without any possibility of growth",
"Related: how can a game be somewhat 'playable' in an advert? 30 second advert where you can control (say) the ship or vehicle and fire basic weapons etc.",
"I wondered the same thing and came to the conclusion that they make pretty good money from this. A game like Crush Them All, that I used to like has an option to pay about 15€/month to get rid of most ads, not all of them. So you can see here that they have a really big price tag for those ads and they don't really give a damn about you playing other games, on the long term looks great for them. They create an inconvenience that can only be solve by watching ads or by paying money."
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e1e6mz | Why are CPUs overclockable? Why don’t manufacturers just increase the base clock speed? | Technology | explainlikeimfive | {
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"They rate them at a clock speed that they feel meets a good balance of performance and reliability. By overclocking them you're increasing the risk of failure.",
"ELI5: same reason you don't jog/run everywhere and choose to walk. They could make every cpu run at its maximum stable speeds, but it is harder on the chips, they will consume more power and generate more heat, and they won't last as long. By having them run at a comfortable speed (like jogging), that's less than their maximum potential they are able to run more efficiently and last much longer. Sure you can manually tell them to go faster, but at the added cost of power, heat, and reduced lifespan. Edit: some people are pointing out the lifespan comment. So to continue with ELI5: a Profesional football player will often retire well before they get \"old\". They can, and often will live a full life like the rest of us. However all that early life hard work and stress can lead to more health problems later in life that they wouldn't have had otherwise.",
"When companies make a batch of CPUs, they then test them to determine how fast they can reliably operate, which is called \"binning\". Sometimes (particularly after a given processor has been in production for awhile and all the wrinkles are ironed out of the manufacturing process), they end up having lots of processors that can achieve top-shelf speeds. More in fact, than there is demand for. So some of those really good chips will be labeled, boxed, and sold as lesser chips that customers are wanting, even though they're actually capable of more. Overclocking unlocks that greater potential. In addition to that, it's often possible to wring additional performance out of chips by using non-standard settings, such as adjusting timings or increasing voltage. These have disadvantages (e.g. higher voltage means it will run hotter and consume more power), so these aren't the stock settings.",
"Overclocking CPUs make them produce more heat. And it can get dangerous if the computer doesn't have a proper cooling/ventilation system. The manufacturer can't ensure the consumers' computer to have a good enough cooler to handle the overclocked chip. So they keep it at a base level to ensure safety and longer lifetime of the chip",
"In addition to all the other comments about engineering tolerances and tradeoffs it is worthwhile selling the same thing at different price points: [ URL_1 ]( URL_0 ) The price is not determined by the cost of manafacture (except inasmuch as you generally don't want to sell at a loss) but what people will pay for it. You might produce something at a cost of £3. If you have 1000 people who will pay £5, 100 who can will pay £10 and 10 who will pay £50 you don't want to sell to them all at any of those price points - you want everyone to pay they max they are willing to. The people who pay £50 will buy the £5 version if they can without too much trouble (hence vouchers/coupons and student discounts) but probably won't if it is (or is seen to be) a little inferior (hence gold-plating/limited editions). It can even be rational to deliberately spoil or mislabel some of your output to sell at the low price point, so those people won't buy it for £5.",
"Because overclocking typically requires higher voltages going through the CPU, which increases heat, and increases the risk of computational errors. Heat also reduces the operational life of the CPU. That's why people who overclock often use expensive water cooling. It's a trade-off.",
"Yield management. Each chip is tested to ensure it doesn't fail over the full range of specifications. Often chips that fail at the fastest rating (bin) will work OK at a slower rating (bin). But also chips may operate perfectly fine at a faster speed, but not over the full temperature range. So by adding extra cooling, a chip officially rated at one speed range may work fine at a higher speed as long as the temperature is kept low enough. This is why overclocking typically requires extra cooling. As others have pointed out, by changing other settings (e.g., Voltage) from the official spec., higher speeds may also be possible.",
"Because manufacturers have to make a compromise between longevity, heat output and demand/profitability. CPU manufacturers have to make CPUs that last 10 years. Generally, people who overclock their CPUs upgrade frequently so longevity isn't as much of an issue and neither is thermal management since they will opt for better cooling solutions. They are also more likely to spend money unlocked SKUs which increases profitability for the manufacturer.",
"Why not make 10 louder? But this one goes to 11.",
"In short: To get the clock speed at the same highest level is simply too tricky so manufacturer just give the safest operating clock to make it as stable as possible. Without letting user experiencing some BSOD or just come with fried chips.",
"There's an additional aspect to this that I haven't seen mentioned yet. If you look into overclocking you'll occasionally hear the term \"silicon lottery\". What this basically refers to is the fact that not all chips produced in a batch will be the same. Some will be capable of running faster than others, somewhat randomly. When a CPU company is producing CPUs in the millions (I don't know any sales figures so millions is an approximate number), it's not practical to test every chip to see how fast it can run. Instead, they test a bunch of chips, and decide on a speed that should be 'stable' on all the chips being produced. If they chose a higher speed, they risk running the weaker chips too fast, in which case they may just not work. If they choose a slower speed, they're potentially wasting performance. When you overclock, you test your CPU to see how fast it can actually go, and set it to that speed. For some people this may be a lot higher than the speed set by the manufacturer, for others it may not make much difference.",
"So many wrong/hand wavy replies. The correct answer is yield and testing cost. Whenever chips are made every manufacturer aims for a particular yield. Say 95%. That means 95% of the chips in a silicon wafer (the round shiny things you see in videos about chip manufacturing) need to work and meet the spec -- so that they can be sold (you can say your product runs at 2.4 GHz but have it fail at 2.3 GHz). Say the manufacturer sells CPUs at 2.4 GHz, then that means that 95% of the chips from the wafer need to run at that frequency without problems. If you make it 2.5 GHz, only 80% of the chips might run at that frequency. When making millions of chips, that 15% waste is a lot of money lost. So they just sell at 2.4 GHz. Another thing they do is binning. Where they sell 80% of the chips at 2.5 GHz and the remaining 15% of the chips (the ones that couldn't run at 2.5 GHz) at 2.4 GHz. My example split isn't great. In reality as you push the frequency you have a bell curve like drop. With very few chips able to run at the higher frequencies. So let's say the split if 80% at 2.4 GHz and 15% at 2.5 GHz and say 3% at 2.6 GHz. There's no financial benefit for testing for 2.7 GHz and then selling them. That's 1% of their sales where they might get a few bucks more. But the testing cost would increase more than that. When you are looking at enthusiasts over clocking stuff, they are probably getting lucky with the few percent of the chips that can run faster. Another thing to keep in mind is that the manufacturer doesn't test each component (in SoCs for example) at different frequency bin. That'll be too much testing and binning cost. The CPU might be over clockable but the GPU might not. So that one chip will be put in the slowest bin. The end user might still overclock the CPU and get some fun out of it."
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e1hfgz | How come a phone call still sounds kinda crispy in 2019? Isn’t there a better alternative | Technology | explainlikeimfive | {
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"Yes. They could easily make cellular calls as clear as a really good (heh) Skype or other VOIP connections. But there's a few things. Back when cell phones were starting to go digital there were still bandwidth (Im gonna skip over multiplexing and channels and stuff) issues - in order to ensure the infant cell infrastructure could cope with spikes in traffic and make sure everyone could get a call through under most normal circumstances, they kept the amount of traffic per call down to a minimum. Thus, voice was digitized fairly crudely - think like really low quality mp3. I mean, the land line quality was only so good, and wireless is WIRELESS OMG, that's bonus enough, why make the voice quality _better_ than a landline - particularly when the other end of the call was likely going to be a landline anyway... so even if the cell side was higher quality the overall quality of the call was going to be limited by the landline side. Of course as Wireless AND landline connections went fully digital and bandwidth skyrocketed, and still-bad-but-not-horrible digitization rates still provided \"good enough\" quality but still had amazing compression.... and people weren't complaining... why switch to higher sampling? A few cell companies did experiment with higher sampling rates and the calls were VOIP like crystal clear... but people didn't like it. It felt weird. Like watching The Hobbit in 48 fps vs. regular movie 24 fps... its too clear, too good. And with voice comms, it just needs to be clear enough to be understood. To provide anything better would require all subscriber/terminal devices (the phones) and ALL infrastructure to support it.... and people simply haven't been demanding it. Lastly, unless its changed recently, the channels and frequencies used by voice calls and text msgs are a lot lower than those used for wireless data; lower frequencies travel further and penetrate buildings/concrete better. So you can still get a text message or a voice call sometimes when your data connection is highly attenuated. You _could_ use a high clarity VOIP call on your cell, but you'd be restricted to where your data connection is great."
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e1jdwt | How are space stations heated? | Technology | explainlikeimfive | {
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"The sun. Spacecraft are generally amost entirely in direct sunlight, and have no atmosphere or anything to transfer heat to. Because of this, most temperature concerns on spacecraft are \"how to remove heat.\" Generally, this is done with heat radiators. For example, [these ones]( URL_0 ) on the ISS. The solar panels are black, and the radiators are white. The radiators can rotate just like the solar panels, and can be angled perpendicular to radiate heat away, parallel to absorb heat, or any angle in between depending on the thermal needs of the station.",
"They don't heat, they try to cool the ISS. Most people think of space as cold and it's true, but it's not the same cold as we are used to. There is just not enough atoms around the ISS to absorb the heat from the ISS and cool it down, like cold air would cool you down for example. The heat in the ISS is stock there and can only radiate away, but that is a really slow process. At the same time there isn't an atmosphere to spread the energy of the Sun that hit the ISS AND there is a lot of instruments and system on board the ISS which produce heat (think of your computer that heat up). Overtime heat accumulate in the ISS (or any other spacecraft) and they need to radiate that heat away and for that they have huge radiators. The space shuttle had its radiator on the inside of the dorsal door and so they always had those doors open in orbit, the ISS have radiators panel at 90 degrees from the Solar Panels.",
"Hi, retired NASA engineer and Shuttle manager here. My baby was Atlantis, and we put many parts on the station. The problem with the ISS is not that it needs heating, the problem is it needs cooling. All of the electrical equipment on board would overheat and fry itself, and bake the astronauts on board at a toasty 140 degrees F. To prevent this, we have, simply put, two Giant refrigerators outside the station that use super cooled Amonia to remove the heat generated by the station. And it works very similar to your home thermostat.",
"Not answering the question but my guess is OP got fooled by Hollywood on how it depicts instant freezing once something/someone gets exposed to the vacuum of space. In reality our bodies would be more or less fine, in fact, tears, sweat and saliva would boil out. We would suffocate and dead-body core temp would be celcius-positive for hours, reaching zero kelvin (edit: meant almost 0, not exactly 0) only days later. So yeah, real issue is cooling things down, not keeping them warm. The space suits for example are wired with fluid pipes that prevent the interior from overheating.",
"You have the sun heating on one side and then inside the ISS you have heat pipes that conduct heat from one side to the other and additionally you have radiators to expel excess heat.",
"There's no air to take heat away, so there's no need to heat them. Sunlight, human bodies, and machines all heat up the place, and big fins let heat escape as infrared light.",
"Real question is how do they keep it cool?",
"They have to Insulate it heavily to keep the astronauts from cooking inside. Source: An inlaw rocket scientist of mine worked on insulating the original rocket that launched what became the ISS, and that was my takeaway from an evening with him.",
"A lot of incomplete but super close answers here. Lot's of people have posted \"you actually have to work really hard to cool things down in space!\" and that's absolutely true. But at the same time you also have to heat everything in space. To answer your direct question first, that is primarily done with things that are basically tiny electric blankets: a coil of wire that goes back and forth and back and forth in a patch. Just putting a large length of thinnish wire to get resistance so that running electricity through it will produce \"waste\" heat. On to the more complicated part, the reason that this is necessary in an environment where everything overheats. It is far, far more simple and safe to have \"passive cooling\", what that means is setting up a system that continues to cool the spacecraft with no input from any system, indeed no ability to change the cooling even if input was given. Typically this is done with radiators on a location of the spacecraft that will never see sunlight, and passive heat pipes that transmit the heat to those radiators. The radiators of the spacecraft will be designed such that they match the expected long-term heat generation on board, and then a little bigger. This is because if you screw up and make the spacecraft too cold it's no big deal, you have some tiny, super light little heater patches around, you run a bit of current through them, now your spacecraft is warm again. If you screw up and make the radiators too small the spacecraft overheats and dies. Even if it takes a tiny bit of extra mass and a bit more power (and thus once again a bit more mass) a cold bias is the way to go. A related issue is components that don't have constant use. If something is off for a long time and it's not near another heat source on the spacecraft it can get too cold during the extended downtime. In that case you have to have a heater on those components to keep them warm enough (depending on the device \"warm enough\" may mean anything, -150 C, -10 C, whatever). In practice many, many different components or groups of components on a satellite will have at least two heaters on them. So the satellite is not heated when \"it\" gets too cold, but instead small individual heaters turn on occasionally when specific parts of the satellite are reaching their cold limit. Some of the above leads to the question \"why not have the ability to toggle how much the spacecraft is cooled\". Typically you would have to do this mechanically, such as with \"Louver\" blinds on the radiator, or by having an actively pumped heat transfer system instead of passive ones. That adds it's own weight penalty and, most importantly, the moving parts are more likely to break, and especially for the blinds it's hard or completely impractical to have fully redundant backups. P.S. This is now all the backstory you need to understand the situation on Apollo 13. The astronauts were on a vehicle that was designed to dump all of the heat that three humans produced, and a bunch of other waste heat from normal operations of all of the electronics. The mechanical failure meant that all of that other waste heat stopped being produced, but the astronauts had no way whatsoever to limit the amount of heat that the radiators were dumping off, so now all of those radiators designed to keep an active spacecraft a little on the cold side were keeping three human beings VERY VERY VERY on the cold side. P.S.S. Some interesting examples of active cooling are the space shuttle and EVA suits. The Space Shuttle had an extended period of time in flight when it couldn't expose its radiator (it's inside the cargo bay, that's why there are so many pictures of the shuttle with it's doors open even when they don't appear to be doing anything, it had to be open for cooling). Luckily the Space Shuttle also had extra water up the wazoo because of it's fuel cells. When the cargo bay doors were closed it used evaporate cooling just like our sweat, slowly and in a very controlled manner venting the water to space. EVA suits have occupants with wildly varying heat production based on their activity, and it's not at all feasible to tell astronauts \"oh, never ever let the sun shine on your left side for more than a few seconds or you'll start to cook to death\". So they use a similar evaporative cooling system.",
"Na. The correct question is how is the ISS cooled. Maybe if we start building space stations near uranus or something then maybe we gotta figure out how t heat a space station",
"In short: easier than they're cooled. Space is a colossal insulator. In the best of cases we're way better at heating a place than cooling it, but in space cooling actually becomes a way bigger issue.",
"Actually, the problem is the opposite. Vacuum is a very good insulator, the best there is, so heat (from the sun, bodies, electronics and other machinery) builds up and needs to get rid of. So, they need heat radiators which can radiate the heat away."
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e1jz5a | How do helicopters and planes fly in the dark? | Technology | explainlikeimfive | {
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"The benefit of being up in the sky means that by and large there aren't a lot of things to hit, so you don't really need to be able to see. When it comes to planes, air traffic control keeps them at different altitudes so that if everyone is doing what they should be, theres never going to be anything to hit.",
"The same way they fly in the light. There are a ton of onboard sensors and when sight is needed (which depending on the situation it may or may not be) then there are usually methods of illumination (similar to how headlights on a car will illuminate a road in the dark). One such example of illumination for planes are that runways have lights going along them and once they have landed they get taxied to the terminal. Even then there are planes that don't necessarily require you being capable of seeing as they have the capability of having infrared cameras that would be capable of discerning the runway in pitch black conditions. Which brings to another point, in instances (like in Vietnam) where they couldn't reasonably illuminate the landing zone then they might instead use something like infrared vision or some other form of night vision (which can be anything from infrared to UV to even some types of vision devices that use types of phosphorus that is really sensitive to light so that even extremely low levels of light can allow for accurate vision). Ultimately there are even more developed technologies (that may or may not be implemented in aircraft) that can allow for everything from terrain mapping in the local area using technology similar to radar and ultrasound, all the way to technology similar to gps that can have a preset position and orientation of something like a runway and tell the pilot(s) if they are on course or not. However, in most cases the easiest solution is cheap reflector tape places on either side of the runway with some light illumating as much if the tape as possible. Edit: and regarding inflight colissions, as long as you are flying at the proper altitude and you stay to the planned course then there won't be a risk as air traffic controllers will make sure that no planes are on a colission course and even in worst case, planes have lights on them (which is why you can see them flying in the sky at night) so pilots would be able to see incoming planes"
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e1k4v4 | How can we tell a picture is taken zoomed-in even with the same framing as a regular picture taken closer? | Technology | explainlikeimfive | {
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"Zooming in is not the same as walking closer. When you walk closer, your perspective is also changing because you are viewing the subject from a different spot. When you zoom in, you are making the subject bigger without changing perspective, which is not something you can do IRL. Most camera actions have real-life equivalents - e.g., panning the camera left is like looking left, moving the camera sideways is like walking to the side, etc. But zoom does not have a real-life equivalent. If you want to give the appearance of walking forward, you have to actually move the camera forward.",
"The way things change size with distance would be different. For example if there are 2 equally sized people, one standing 5 feet from the camera and one standing 10 feet from the camera, the second person looks way smaller because they’re *twice* as far away. If you back up by 100 feet, a 5 foot difference is now a small fraction of the total distance. So these 2 people will be about the same size on camera. Actually, this effect can trick your brain into thinking the further-away subject is *larger*, because we expect the distance to make them look smaller than they actually are, but they’re full size. So backing up (and zooming in) “flattens” the image, causing the foreground and background to be more similar in size. And of course, this has other effects on the picture— if you’re closer, so foreground subjects look larger, this might also cause them to block the view of background subjects, but at a distance you can see past them."
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e1kh52 | How do GPS calculate the shortest route to a destination | Technology | explainlikeimfive | {
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"GPS only provides your position. Your device, smartphone, whatever, calculates the path. It does this through data, what Google calls \"map data\", which defines the time to go between each point in the road network where you have an opportunity to turn.",
"If you want to dive a bit more, the most popular navigation apps use what is called Dijkstra's algorithm or also A* algorithm to compute the shortest path from one place to another, and then compare that to current conditions on the road (speed, closures etc etc.)",
"It's an algorythm called A\\*. Simple pathfinding is easier to explain so let's do that first.... It takes all possible ways you can go from your starting position and stores how long it would take to get to the next point where you can make a decision (like turn left or go straight). For each of the points where you are at now it will calculate the sum of: 1) How long would I drive to get here? 2) Rough estimate on how long it would still take to get to the destination from here (usually simply based on distance and average travel speeds). And then it just takes the point with the lowest score and finds all places you can get from there and adds them to the list. Then it takes the now point with lowest score and does it again. And it keeps doing so until a route hits the destination. & #x200B; The biggest optimization to this is what someone already called A\\* where you do routes from the starting point and the destination in parallel and it keeps doing so until routes from both points match up."
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e1novm | If we can stream 4k content over wifi, why aren't HDMI cables slowly getting replaced by wireless transmitters ? | Technology | explainlikeimfive | {
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"Because the stream is compressed, where as display signal isn't. If it were you'd require a relatively powerful computer on the other end to decompress it, also there's the issue of image quality. Uncompressed 4k24fps movie stream is like 600MB/s, an internet 4k video is 3MB/s",
"Besides the bandwith and compression problem there's also a latency problem, this may not be an issue for watching a movie but it can be very troublesome for playing video games.",
"Wifi is less reliable, and more subject to interference, and requires more configuration. If everyone in an apartment building streams 4k over wifi, the bandwidth will be terrible due to radio frequency overlap.",
"That 4k stream is suuuuper compressed relative to the 4k video data being pumped along an HDMI or Display Port cable. Every video you download or watch of a disk has been compressed so it'll fit. Video compression is really good, H.264 gives a compression ratio around 2000:1. Full uncompressed 60 frames per second 4k video requires about 12 Gbps, this is what's flying over your HDMI or Display Port cable to get to your TV or monitor. But that stream you're download *is* compressed, likely with H.264 these days so you only need 6 Mbps to stream 4k video with alright quality. Your Wifi connection can handle streaming video to your chromecast or TV at 6-20 Mbps and then your chromecast/TV turns it into that 12 Gbps 4k signal for the display driver."
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e1nvf6 | What are the benefits of a chiplet design for microprocessors as opposed to a monolithic design? | AMD has been making waves in the past few years by popularizing the "chiplet" design in their consumer and enterprise CPUs, where there are multiple silicon dies on a package, each serving specific functions. What are the advantages and disadvantages of this compared to the traditional chip design philosophy of putting everything on a single die? Which is better for high volume and/or low-cost production? Finally, is this technology as applicable for mobile and embedded CPUs as it is for desktop and server chips? | Technology | explainlikeimfive | {
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"The manufacturing process of a CPU is not perfect. Dies are made from giant wafers that are slices of silicon crystals grown in a cylinder in a lab. Some of these crystals have imperfections on them and when you make a die out of one of these wafers with an imperfection on them you could either end up with a useless die or if you're lucky you can salvage it and turn it into a CPU with fewer cores or some features disabled. Making a monolithic die yields fewer dies per wafer and increases the likelihood if you ending up with a die that's useless because of impurities in your silicon.",
"* By breaking the CPU up into individual components, they can be independently tested and validated, thus increasing yields whereas a single monolithic chip with some design defect may render the whole chip sold as a weaker model or discarded entirely * Scaling up is easier. In the first generations, Ryzen was a single chip with 2-channel memory and 32 PCI-E lanes. Threadripper was 2 basically Ryzens which means 4-channel memory and 64 PCI-E lanes, and Epyc goes up to 4 Ryzens on one chip with the obvious increase in components. But connecting all these individual Ryzens required a lot of interconnects and didn't really fix the issue that memory \"belonged\" to a specific \"Ryzen\" chiplet meaning the speed of accessing RAM is inconsistent unless you were really careful about NUMA node management. By splitting off the memory and PCI-E lanes as its own chip, each CPU core chiplet only has a single communication path to the main IO Hub and the IO hub scales with the number of chiplets under it. In contrast Intel basically has one big chip with everything on it, which might be a benefit for performance in the long run but I'll bet their R & D department spends a lot of time making up many CPU designs when they need to make a 28-core beast while also scaling it down to a quad-core laptop chip."
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e1nwka | How does WinRAR password encryption work? | I meant how does it encrypt my files, what does it do when I set a password? | Technology | explainlikeimfive | {
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"File encryption can be done in a lot of different ways, but the most common is to run the files through an algorithm that changes each number. As I'm sure you know, a computer file is made of a bunch of numbers, designated as 1's and 0's. Each 1 or 0 is called a bit, and a set of eight of those is called a byte. When converted to decimal numbers, one byte can be a number between 0 and 255. Let's make it simpler, and pretend we have a code of letters. A = 1, B = 2, and so on. To encrypt it, we'll subtract 10 from the number, rolling from A to Z as needed. So the word \"HELLO\" is 8-5-12-12-14. Subtracting 10 (with rollover) gives us 24-21-2-2-4, or XUBBD. That \"XUBBD\" is what's stored in the encrypted file, along with the algorithm we used. And it's all locked behind a password, which is encrypted by applying a different algorithm. The password isn't stored, but the result of the encrypted password is. When you enter a password, the algorithm is applied to the characters you entered. If the result matches what's stored, it unlocks the encryption algorithm, which is then applied in reverse to the data. So our rule of subtracting 10 would turn into adding 10. \"XUBBD\" becomes \"HELLO\" again. This is extremely simplified, of course. Since computers are capable of doing complex math very quickly, the encryption algorithms used are much more complicated than our simple \"subtract 10\" rule. But hopefully this explanation helps you visualize the process."
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e1nzrt | what’s the difference between a data scientist and a data analyst? | Technology | explainlikeimfive | {
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"At face value, an analyst would simply look at and interpret data. A scientist would collect data (experiment) and interpret it.",
"Data science is a field of study that combines statistics, math, and computer science. Data scientists use complex algorithms to learn from the associations between huge numbers of variables in very large datasets (also called \"data mining\" or using \"machine learning\"). Data analysts are professionals whose job is working with data. They could work under the direction of a data scientist, but they could also do other types of data work such as public policy research or business analytics."
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e1o77v | How can Google display and monetize things like article snippets and images under copyright? | Technology | explainlikeimfive | {
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"Copyright laws allow for certain types of “fair use”, such as short clips from videos or songs to be played. A great example would be a Youtuber showing clips from somebody else’s video (or a news report) and adding their commentary about the other video. I’d imagine partial text from an article or a reduced-size photo fall under these rules too. Google is not reproducing the entire work in its original format or quality, and a main feature of their search engine is not only telling you where the item came from, but helping you navigate to their website so you can view it there. I think they did have to change their image search function a few years ago— it used to link directly to images but now links to the page that contains the image. This allows the whoever created the image to show their ads to profit from it, as well as present it with whatever additional context or info they include on their webpage."
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e1p0lp | Where do astronauts in space get their air from? | Everybody has to breathe and we on earth have an atmosphere, how is it done in space? | Technology | explainlikeimfive | {
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"They bring up water, which is converted into oxygen & hydrogen using electricity (from solar power). They also extract O2 from waste CO2."
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e1py0g | How Were Old Maps Drawn? | Technology | explainlikeimfive | {
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"When you use a map or chart to navigate what you will tend to do is take bearings (measurements with a compass) which you can then draw as lines on your map/chart. Where the lines meet is where you are. You use features whose position is known (for example, spire of a church, and the peak from two different mountains) to find a position which is unknown (The place where you are). If you are drafting a map/chart You do the same thing, but backwards. You start of by working out where you are (usually by using a sextant in the olden days) and then you start taking measurements of different unknown features around you (mountains, bits of coastline, bends in rivers) You draw these on your draft. You then change your position and remeasure. Then you measure again, and again. Then you move to one of those previously unknown features and begin checking it against the other measurements you took. You repeat this process until you are sure that you have measured everything correctly. Then you move on to a new bit of land... It takes a lot of time, and is difficult, which is why coastlines were explored and charted much better/quicker than inland areas."
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e1rl10 | how would electric cars be any better than gasoline cars? If everyone has an car, they are going to want a lithium ion battery. Lithium is very pollutant to mine, and also we would have to throw away a ton of them when they die. | Technology | explainlikeimfive | {
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"1. The mining of lithium is still far less pollution over the lifespan of the car/battery than burning gasoline or diesel is, and the mining for oil that it takes to make it. 1. Lithium based batteries can be recycled to a relatively high degree to make new batteries. It's not done super frequently due to costs right now, but as regulations and carbon taxes come online, it'll make that recycling more worthwhile. 1. Even if your power doesn't come from a \"green\" source like solar, wind, or hydro, it's still massively more effecient than your cars engine. A typical car engine is in the neighborhood of 20-25% thermally effecient, which means 75-80% of the fuel essentially gets wasted and just turned into heat. Natural gas power plants are generally in the ~35-40% range, but some newer ones get as high as 60% effecient. Meaning that for every gallon of fuel they burn, they get 2-3x as much actual power out of it than you would burning it in your car directly. Plus, since the power generation is centralized, it's much easier to capture and deal with pollutants.",
"Batteries can be recycled, and the studies that try to claim it is damaging to the environment to make a lithium ion battery are very exaggerated - it is true that it produces pollutants to mine and manufacture the battery, but a standard electric vehicle is going to generally pay off its \"carbon debt\" to the world about three years after its made, if you compare how much carbon dioxide it takes to make a lithium battery compared to how much an average person drives in a year with a normal gas powered car. Also, the more we research these technologies and make alternative forms of energy more powerful, the less pollution we have to make to produce an electric car.",
"Mining Lithium is very polluting. Mining oil isn't exactly all daisies and fairy dust. Lithium battery packs can be recycled and reused. Used gasoline can't be recycled or reused. Burning coal to charge EVs makes pollution, yes. Burning diesel to drive oil rig, burning bunker fuel to drive the tanker ship, burning oil at refinery, burning diesel to get the tanker truck from refinery to gas station is again not daisies and fairy dust",
"To start with, lithium production actually accounts for a distinct minority of an EV's lifecycle impact, [clocking in at a total contribution of about 2.3%]( URL_2 ). From there, the operational efficiency gains make EVs significantly more efficient than normal cars. As operations massively outweighs manufacturing in lifecycle impact, even for EVs, this means that EVs go on to make up for the additional manufacturing impact, ultimately leading them to become better for the environment than normal cars. As for end of life battery considerations, EV batteries [are actually non-toxic, and highly recyclable]( URL_0 ). In fact, Tesla [has started recycling batteries at their Nevada gigafactory]( URL_1 )."
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e1s5yx | What is the difference between Git and Github | Technology | explainlikeimfive | {
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"Git is a software tool first made by the guy who made linux. It helps programmers work together. It needs someone to do computer stuff to run. GitHub is a company that does the computer stuff to run Git. They're probably the biggest company that does it. When they first started they only provided Git stuff, now they provide non-Git stuff. They run a website where you can ask them to do the computer stuff for you. So think something like Amazon being both the company and the website. They also aren't the only company to provide computer stuff for Git. For example, the company Atlassian has a service called BitBucket that provides the computer stuff to run Git."
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e1ubru | What happened in the last few centuries that propelled us so far forward so quickly technology wise? | At the turn of the century we finally invent the tractor. We literally JUST invented the Tractor. 30 years later, teh automobile. roughly 40 years after that we get the first manned mission to the Moon. 20 some odd years later and the internet is born. What exactly was invented that caused this huge boom in technology? | Technology | explainlikeimfive | {
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"There are three key things here First is that we learn from others and our past successes. If you invented a sled and I invented a wheel we can combine them into a cart without both of us having to invent the other. Thanks to writing, printing, telephones, and eventually the internet we can share ideas far and wide and draw on the works of others to move forward faster. Next is the technological advances build on each other. I couldn't (easily) build a car 1000 years ago. The precision machine tools I would require to build the car would need to be made first. As we started building better and better tools we started being able to build more precise tools and tech that snowballed as well. Thirdly and much more recently Computers (even simple ones) helped push us forward faster. They allowed us to model and simulate things and try out a lot of possibilities quickly and easily because we didn't need to build them first.",
"In a sense, it was the ability to machine parts accurately. They could do so before the turn of the century, but it was expensive; unviable for most mass production or making interchangeable parts. Once it became widespread, more tools and machines were able to help manufacturers make things, including other machines and tools. There's definitely more that went into it, but that's definitely a large contributor.",
"To sum it up as neatly as possible: The renaissance (1400-1600s) > the scientific revolution > the agricultural revolution > the industrial revolution(s) > the green revolution > information revolution (1960s to present). Once we figured out we can do more than kill each other all day we figured out we can find out about whats going on around us (the renaissance). And then with all that thinking going on we realised science could be done better if we were cooperative and objective about it (the scientific revolution), which lead to even MORE figuring out. Which lead to figuring out how to spend less time doing other things (farming) so we could spend more time figuring out other things (the universe) (agricultural revolution). And then since we didnt have to dedicate 90% of the population to farming anymore, we used those people to just kept reiterating that process for everything (the industrial revolution). And this freed up even more people to figure things out, one of them being industrial fertilizer meaning we could feed everyone much better meaning we could have more kids and live more healthily which meant even more people who could figure things out (the green revolution, without this we would have a fraction of the population we currently have). And then we figured out computers, and the internet. Thanks da vinci.",
"Think exponential change, rather than linear. Change that enables change, at a newly changed efficiency",
"Any society that undergoes an agricultural revolution gets a boost to its technological advancement. Before the agricultural revolution of the 18th century in Britain, ~99% of the population worked in agriculture. If it takes the combined efforts of 99 people to feed 100 people, then only one person in 100 is available to invent new stuff. In practice, there is some overlap and people could work full time on the land and maybe invent stuff. eg. the plough in ancient Egypt. However the principle remains the same. Less people needed to work the land = more people available for other endeavours. Advancement is logarithmic, not linear. Progress is slow slow slow then climbs at a rapid rate. 66 years between the first manned flight and man walking on the moon."
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e1w2td | Internet cookies and what happens if I don’t enable them? | Technology | explainlikeimfive | {
"a_id": [
"f8s1etd"
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"text": [
"A cookie is a piece of data that a website can ask your browser to store. Whenever you visit any page in the website, your browser will automatically send this data back to the site. Cookies are used for storing information about you. For example the first time you enter a website it often generates a random cookie value known as a \"session id\" which can then be used by the website to remember who you are. On the other hand, cookies are also used for tracking purposes - if a website contains an ad, then the ad might inject a cookie that can be used to track you across multiple websites, so they know what sites you visited. Disabling cookies will hurt your experience in heavily used websites - they won't be able to store any info about you, so they won't be able to remember who you are and what your settings are. However if you're just visiting a website that one time, or you just use it for reading content statically, then cookies aren't that important."
],
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7
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|
e1yn05 | How does Disney's new "Stagecraft" technology work? How can it change the way we make and see movies? | I searched the sub and it seems like nobody else asked this question before, so here we are. Recently I've read a few articles about how Disney's new Mandalorian TV show is [using some fancy new tech]( URL_0 ) to make movies. I tried delving deeper, but the explanations seem to only make me more confused! | Technology | explainlikeimfive | {
"a_id": [
"f8seyzh"
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"text": [
"From what I understand Stagecraft just takes the concept of a green screen but realizes it via actual screens onset, and will actually move the background images to match camera movements. So traditionally when they’re shooting a movie in CG the actors are just in a big green room, and have to pretend they’re in another world or whatever... with Stagecraft the green screen is gone and it projects an image of the other world in the background, so the actors can look around and it actually seems like they are there, not in a big green room. Aside from giving the actors a more realistic setting I don’t quite understand how that translates to better settings from us the viewers at home, I’m sure there’s a lot more to it under the hood, it sounds neat id love to see a video of a set using it."
],
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5
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e1ytxo | Why and how do devices charge faster while in airplane mode? | Technology | explainlikeimfive | {
"a_id": [
"f8sfpwt"
],
"text": [
"When in airplane mode (or when shut off) the device is draining less power from the power cord and battery so more energy goes to charging the battery as airplane mode disables certain services that can drain the battery. It's like if you are filling a bucket, if the bucket has a hole in it then it will take longer to fill but if you patch the hole then it will fill up slightly faster."
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4
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e209a0 | I get ads on Instagram for restaurants or products I’ve only talked about but never searched. How do they do this? Are they really listening in to me? | Technology | explainlikeimfive | {
"a_id": [
"f8svpzy",
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"text": [
"A lot of people will say that your phone is listening to you through the microphone. Facebook and other companies say they don't, and I'm inclined to believe them, *because they don't need to*. You say that you switched lights and you didn't Google them. Let's assume that's true, but frankly it probably isn't. Or, maybe you didn't search for lights, but you asked Google where the local hardware store is. Or the local Lamps-R-Us. Or whatever. When you bought your replacement lights, did you do it at a big box store? Did you use a credit card? If you didn't Google it, did any of your friends? Did you not bother with Google, but go directly to Amazon or Home Depot's web sites and look at light fixtures? The real problem isn't that your phone is listening to you. The real problem is that by a thousand little actions you created a marketing profile, all of which was analyzed using cheap AI systems. You don't have to do anything as obvious as search Google for \"lights\" - you did many, many other things that left a footprint in the digital world that resulted in you seeing ads for new lights. No voice recognition or listening to audio required. And, frankly, computationally much cheaper. I strongly recommend you listen to episode 109 of the podcast \"Reply All\", titled \"Is Facebook Spying on You?\": [ URL_0 ]( URL_0 )",
"If you have an Android phone, you can check to see what's being recorded and turn it completely off. Here's a website that explains how to check your phone: URL_0",
"If you allow access to “your microphone” via aps like “snap chat” it records data and stores it. If you have “hey google” or “Siri” it listens and both record. Welcome to the Internet. Now you’re in their data banks too!",
"> lights Lights are very common. This is like when people were talking about how amazon was listening to them because they mentioned wanting to get water from the water fountain and amazon suggested buying a waterfountain. Solid theory, except that it was black friday and I also got that ad as long as like everyone else. I believe it's closer to confirmation bias. You see lots of ads. When you talk about something, you become more aware of it. When it catches your eye you freak out and all of a sudden, everyone is listening to you. If anyone disagrees, please provide evidence that is stronger than I think it does, therefor it is. I'm aware that some apps have stolen information in the past for ads, but I'd like to know if Facebook or Google is doing this.",
"There are two sides to this. 1) yes, your phone CAN listen to you, but it’s likely not. At least not in the way people perceive because of situations like this. 2) Usually people are targeted based on an AI or algorithmic process that is based on much more data than you’d ever believe. For a simple example, if you told your mom about blah restaurant or product, it’s highly probable that you could get immediately targeted for an ad because they can tell the link between you two. She may have searched it or something similar. You never know. Ad companies know all of your public record data, can access your credit report, and are given information about your known associates, people you have in your phone (think about when you pressed “yes” to allow Facebook messenger access to your contact list) and they keep track of your purchases. Every store rewards card you have tracks your data. Every purchase you make carries more data to more places than you would ever think. The algorithms are built to predict who will buy what from where and when. And they are almost too good at their jobs. Most of the time you have taken a behavior that has allowed the algorithm additional access to your consumer profile OR have done something online that you don’t think is connected...but the algorithm will think “ok person A did this, and then made a reservation at this restaurant. Person B is nearly the same, so I’ll serve this as”"
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e20m60 | Why is there a stereotype of it being better to developing applications inside Linux vs Windows? | Technology | explainlikeimfive | {
"a_id": [
"f8sseid",
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"text": [
"Linux was historically a lot easier to develop for, I suppose. In Windows you had to find some tools, often illegally if you didn't have the money to pay for them. In Linux they're all there from the start, you install them the same way you install the system itself. The availability of lots of free and high quality tools under Windows is a relatively new development. Also Linux is a lot more open to experimentation. Want to change the user interface, or the kernel itself? The source for all of that is available. In Windows such things are far harder and much less flexible. Eg, modern Windows still keeps [ancient fixed size dialogs from times immemorial]( URL_0 ) (I think that dialog looked like that in Windows 95?). You want to make that window bigger because scrolling is annoying? Well, too bad. Nobody at Microsoft saw the need to bother to improve that bit in two decades, and you don't get to either. On Linux, if something bothers you, you can change it.",
"Linux OS is free. This means the barrier to entry is low. Windows OS license is $100-$200 a pop. This means more people can jump into Linux systems. Traditionally Linux has been packaged in varying levels of configuration. You want a small version? Ok but it'll miss these things. As long as you don't use those things you're fine. Want a really skeleton version? Ok but be prepared. Want a minimal windows for desktop? It was really really hard to get. Only recently in past 5 years did Microsoft start releasing smaller versions of windows for enterprise use. But the desktop versions are all full blown. You can't get a copy of windows without 500 preloaded printer drivers. Or 1000 kinds of misc devices that you might never encounter.",
"It's not a stereotype. You'd have to actually be a developer to understand, but essentially it comes down to clutter. In Linux you have an editor of your choice and the terminal to test the program on. And usually with Linux systems they come with the tools to make programs like the gcc compiler, and python interpreter to name a couple of examples. On windows you have to use An IDE, you have to learn the IDE and how to use the IDE, and it's annoying to work with because sometimes they make extra unnecessary files. You can't even get gcc on windows without having to use some third party application called mingw. Visual studio, as an example, is absolute overkill for writing C programs. When I could just go on Linux and just write and test my program as I see fit. There are instances where you just can't avoid Windows, like when you need to use its system libraries but I think you get the idea."
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"text_urls": [
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"http://www.downloads.netgear.com/files/answer_media/images/IPv4_properties.png"
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|
e20rmk | What actually happens when we run out of IPv4 Addresses? | What happens when we run out of IPv4 addresses? < - Can no more devices connect to the internet? | Technology | explainlikeimfive | {
"a_id": [
"f8srxb7",
"f8srxhx",
"f8tciet",
"f8st1ya"
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"text": [
"they've already implemented IPv6... per [Wikipedia]( URL_0 ), \"In IPv6, the address size was increased from 32 bits in IPv4 to 128 bits, thus providing up to 2^128 (approximately 3.403×1038) addresses. This is deemed sufficient for the foreseeable future.\"",
"We start using IPv6. As simple as that. We've known that end of IPv4 was coming a long, long time ago. And yes - once all IPv4 addresses have been given out, no more can be given. Which is why there was such increased support for IPv6 in modern devices.",
"Well, yes. That is exactly what will happen. Once all the IPv4 addresses available are in use, nothing else can connect \"directly\" to the internet. Thanks to things like NAT (Network Address Translation) and CIDR (Classless Inter-Domain Routing) before that, we have been able to avoid running out, but there are no more IPv4 addresses available. You can still buy blocks of addresses, but no more are available to be given out. The answer should be \"switch to IPv6,\" but since IPv6 has been around for like, a long time and a lot of organizations haven't made the switch, I feel like it's going to take catastrophe for the change to take place.",
"It just means organisations and ISP's will only be able to buy blocks of IPv6 addresses. The IPv4 in use will still be used, just their is a VERY limited number of IPv4's available to buy. Companies sell back address blocks they don't need, as well as those that go bust, so their will always be a handful of spare addresses around. Day to day for us, their won't be much of a change since we're already using the IPv4 addresses. But we'll see a transition by most ISP's and Host providers to move users over to using IPv6 addresses and \"retire\" IPv4 to legacy equipment usage (i.e. old devices that can't handle IPv6 addresses). Running out of IPv4 does not mean the internet crashes to a halt. It just means their are none available to buy and we'll have to use IPv6 as default."
],
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e25los | Why did Google let microsoft use chromium on edge? | Technology | explainlikeimfive | {
"a_id": [
"f8tmumt",
"f8tvsy4"
],
"text": [
"[Google is an advertising company, first and foremost]( URL_0 ). Everything that they do, they do to further the goal of selling more ads. Chrome, Drive, their MS Office knock-offs: their only purpose is to get people to use them and sink ever deeper into the Google ecosystem. That is why they are \"free\".",
"because it's the defacto standard; atleast for a majority of the mainstream internet now. IE sucked for everyone but especially for developers; i remember the stupid shit you had to do in order to achieve the same result as document.getelementbyid.innertext/innerhtml = blablahblah. hence you can probably defer from that fact that nobody would miss the old IE engine; whatever it was."
],
"score": [
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3
],
"text_urls": [
[
"https://www.visualcapitalist.com/how-tech-giants-make-billions/"
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|
e26if7 | What causes audio feedback, and why does it make that particular sound? | Technology | explainlikeimfive | {
"a_id": [
"f8tsic5",
"f8tsgnp"
],
"text": [
"When a microphone, connected to a speaker, picks up the audio that that speaker is broadcasting. Causes a loop: > Microphone detects sound > Speaker amplifies sound > Microphone detects amplified sound > Speaker further amplifies sound Rinse and repeat",
"The microphone is picking up its own signal from an amp. It takes that noise and puts it back through the amp, making it louder. It picks up this louder signal and puts it back through the amp, making it even louder. This process repeats forever until the mic is too far away to pick up its own signal anymore."
],
"score": [
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4
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|
e27mfx | How do scientists fire something as small as a particle? | How is a scientist able to capture and observe something as impossibly small as a particle being fired at something else? The video I watched stated they do this to detect wave patterns. | Technology | explainlikeimfive | {
"a_id": [
"f8tzmrt"
],
"text": [
"All you need to do is pop off an electron to make a charged ion. Then you can use magnetic fields to hold it and electric fields to accelerate it. (This is of course really hard, but I've oversimplified for ELI5.) If you're talking about a slit experiment, that's likely detecting the wave pattern through some sort of charged particle detector."
],
"score": [
3
],
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e29ubl | why Virtual Reality for PC has higher system requirements but PSVR on PS4 can support those kinds of games with allegedly underpowered hardware? | Technology | explainlikeimfive | {
"a_id": [
"f8ucaob",
"f8ul1ng"
],
"text": [
"It's about how well the hardware is optimized and how the software is designed. Notice that on the PS4, you're not going to get the same fidelity and smoothness that you would on a high end PC. This is because the port that's built to run on the PS4 is tuned to run on that specific hardware. It can't adapt to better hardware, because the better hardware to run it will never be available. In short, the software made for the PS4 is designed to run, specifically, for the PS4.",
"On PC it will be far more detailed/higher resolution and much higher framerate than on console. Current gen consoles really are low spec PCs, a similarly speced PC would be best as bad as the console. There is no optimization advantage ever since AMD released Vulkan, it's essentially the same close to silicon language as the consoles use. Why? AMD designed and built the consoles around their existing tech."
],
"score": [
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|
e2en59 | why do GPUs need to support Graphics APIs (on a hardware level) | like for example "GPU XXX Suports DX12". which is touted as a feature on the retail box as well. from what I understand the API is standardized for a certain graphical pipeline to draw various stuff on screen (polygon pipeline, brightness of a pixel pipeline...etc.) and it's hardware agonistic, and it's up to GPU manufacturers to "optimise" the workflow of said pipeline. You can go into some detail, ELI10 if you will lol | Technology | explainlikeimfive | {
"a_id": [
"f8v8ncp",
"f8v8r7p"
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"text": [
"A graphic API is indeed a standardized way to ask the GPU to do stuff (This includes drawing, as well as general computation). To support and API, GPUs have to be able to handle all the features that the API exposes to the programmer. This includes stuff like supported shader instructions, texture formats. For example, DX12 requires shader model 5.1 which includes a bunch of new instructions to do atomic computations (called `Interlocked...`). Theses instructions most likely require hardware support so GPUs that do not have the circuitry to perform these operations can not pretend to be DX12 compatible.",
"Graphics APIs like DX12 are hardware agnostic to a degree, but the hardware needs to be capable of providing the features which are part of the API. Take ray tracing for example. Say that the next version of DX includes an API for ray tracing (the existing API for it isn't a core part of DX12). For a GPU to be compatible with that API it has to have the hardware to support ray tracing. In theory that could be supported by implementing it in software in the driver, but that would be so slow it would be useless for most purposes. So it needs to have hardware support for it to be deemed fully compatible."
],
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3
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