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8x87d0 | How can tiny little headphones make so many different instrument noises, people's voices? And on top of that, all simultaneously? | Technology | explainlikeimfive | {
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"Headphones are just tiny speakers, so there are two answers here: how speakers work, and how headphones can be so small. All the different sounds in music are added together to make a single complex sound wave. Imagine a low frequency sound wave with big swooping curves and a high frequency wave with tight spikes up and down. When they are added together, you get something that looks like the big swooping curve being drawn using the little tight spikes. So a speaker doesn't have to make a lot of different sounds, it just makes one sound which is the result of all the sounds being added together. Headphones can be so small because of a few principles, but the primary one is the inverse square law of sound levels. Sound gets quieter by a fixed amount (6db) every time you double your distance from the source. So if you listen to a speaker 3 ft away, then 6 ft, then 12 ft, the sound will go down by the same amount at each distance. This means that it get a LOT louder really quickly when you are really close to it. So a speaker does not need to be very loud if you are less than an inch away from it."
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8x8ens | How does your phone detect when you are sleeping? | Technology | explainlikeimfive | {
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"They don't. It's pretty much just bunk placebo app (of course the makers of the apps will never tell you that!) The apps generally \"work\" by detecting movement on your bed at night and trying to make calculations based off that. They don't actually analyze your body or measure anything. It's basically BS."
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8xagkr | What is the importance of metallic hydrogen? What everyday things can it do? | Technology | explainlikeimfive | {
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"> What is the importance of metallic hydrogen? Not much > What everyday things can it do? Absolutely nothing Metallic hydrogen only occurs under extreme pressures like those in the center of Jupiter. We can make it on Earth using a press for making diamonds but very little has been created and none has been used outside a lab"
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8xbz7u | why exactly aren’t plastic straws recyclable? | Technology | explainlikeimfive | {
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"Everything can be recycled. The question is whether it can be done for less money and energy than creating something new from scratch. If the recycling process requires you to burn a bunch of fossil fuels and manufacture a bunch of new equipment, it might actually create more pollution and waste than simply putting the item into a landfill.",
"They are too small and get sifted out or they will clog up the machinery, they are recyclable but need a specialized facility.",
"Some plastic is like water to ice, then ice to water. You can repeat it. Some plastic is like baking a cake and trying to unbake it. Some plastic just can't be recycled"
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8xdqun | I have a slow internet connection, how does sites like Imgur know to send me pictures and videos slower? What happens if it sends data too fast? | Technology | explainlikeimfive | {
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"Most data transfer (that isn't Streaming) uses the TCP protocol. One of the main things TCP does is that when a packet gets sent, it waits for an Acknowledgement (ack) before it sends the next packet. So if you hooked up a garden hose to an outdoor swimming pool, the pool can't push any more water out of that hose than the hose can handle. It just waits and goes at the speed of the slowest link.",
"Servers (usally) have a fast connection. The only thing limiting how fast you can get stuff is by your connection. Think of it like a funnel, everything can flow fast from the imgur serves but your connection is the slow tip that limits everything."
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8xe0ye | Why do governments and companies destroy hard drives for security instead of just writing over all of the data 100% and why does it take multiple passes to make sure the data is gone? | Technology | explainlikeimfive | {
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"It takes a lot of time to overwrite drives like that, this consumes electricity and occupies a computer/employee which could be doing something else. Lastly, it requires that the drive be *working properly* and that's not a sure bet with old equipment. And why not destroy it? You could get some money by selling it, but then you need to *take time* (assign a paid employee) to the task of selling those drives in an attempt to make money back. Seems counterproductive. It's sometimes claimed that after a drive is overwritten, the \"strength\" of the magnetization can be used to find out what was written before. But my understanding is this doesn't work *or at least hasn't been demonstrated* in practice, and that writing random data (rather than all 0s) more than once would seriously hinder this process, if it was real to begin with. I think the main point is economics, speed, and ease.",
"One of the reasons is dead zones on a drive. Areas that can no longer be written over. The areas could have information on them that would not get deleted by overwriting the entire drive.",
"Also take into account the fact that a lot of large companies and governments use tech long past it’s obsolescence. The value of these old units means the cost of secure deletion is even less value for money."
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8xeheg | How does timecode/ drop frame really work. I know it has to do with losing time but I’m still confused. | Technology | explainlikeimfive | {
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"Another user asked this question two hours before you did. [Here's my overly-complicated response to them.]( URL_0 )"
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8xgivs | What is the benefit of glass screen protectors over plastic ones? | Technology | explainlikeimfive | {
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"Speaking from personal experience, two things stood out for me and glass vs plastic screen protectors. Plastic ones scratch easily, but glass ones generally don’t without sharp tools. The other is durability. An impact may just crack the glass screen protector whereas a plastic one would allow the actual screen to crack.",
"Ive always gotten glass ones. I prefer the look and feel. They have broken on many occasions (when I drop the phone screen down on a rock) and act as a sacraficial barrier. Permenant screen remains unharmed. Just swap it out. Not sure about the plastic ones, but I'd want something that could do the same."
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8xh2kr | Where does computer code come from and how does a computer know what to do with it? | Technology | explainlikeimfive | {
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"Novice programmer here, Computers read binary as instructions and follow what it's told. When you write code in another language, the IDE (the software you program in) you are using converts what you write into binary and the computer executes it. Pretty sure atleast, haven't studied in over 7 months..",
"Its literally a massive \"yes or no\" game. You have logic gates which are physically built to take two inputs and give an output, often in the form of high or low voltage electricity. For example, an and gate requires both inpit voltages to be high in order for the output to be high. You string that together hundreds, thousands, millions of times, and you have programming."
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8xjiqn | how we cut our first diamond. | If we currently use diamonds to cut other diamonds most times. How did we cut the first diamond to make it any useable piece? | Technology | explainlikeimfive | {
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"You can grind them down with softer materials, you just lose more of the grinding material than you do diamond. You can sand a diamond down with wood if you had enough wood and enough time.",
"Materials have lots of properties that generally get boiled down to \"strength.\" There is compressive, tensile, and sheer strength, which are the forces that a material can take before it breaks. There's stiffness, which is how much a material bends as you apply force to it. There's toughness, which is how much energy it takes to break something (think opposite of brittleness). Then there's hardness, or resistance to scratching. Diamonds are the hardest mineral but that doesn't make them the strongest, stiffest, or toughest. You can break diamonds without cutting them (an operation largely driven by hardness). If you pulverize diamonds into a powder then you can use that powder as the abrasive to cut other diamonds."
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8xkofq | when shrinking a picture on the computer, how does the computer know which pixels are important in keeping the thumbnail looking like the original picture? | Technology | explainlikeimfive | {
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"In general, downsampling an image doesn't keep pixels from the original image. It averages out multiple pixels to generate a new replacement. This is why hard edges can end up looking soft and worse defined after a downscale has occurred. If you want to turn a 100x100 image to 50x50, a simple thing to do would be to take every 2x2 square across the entire image and, for those four colours, try and find the closest colour to all four provided pixels. In a general image there won't be much colour variance and it'll be easy (for example, taking 4px of my red shirt will likely return a red pixel, even if there's slight shadow on bits of it). Of course, you'll get terrible results if you try to do this on an image of alternating black and white pixels, as the result of my simple method above will just entirely be a single shade of grey. Some things can be done about this in terms of sampling and edge detection, with the intent of preserving features, but these are more advanced."
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8xlkr2 | how does a team of programmers divide their work and create a single application using multiple computers? | Technology | explainlikeimfive | {
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"Imagine it’s not an application, instead, You and your friends are making a cake. You take the eggs. They have to be shelled, separated, and whisked. One friend takes the frosting. Even though it doesn’t go on until the end, rolling, chilling, and dying take time. One more friend cleans the kitchen, sets the oven, makes sure everyone has enough bowls, utensils, etc. Another friend handles the filling, boiling down fruit and pectin to make jam. All of you know what kind of cake you’re making, so your friend making the frosting knows what flavor of filling the other is making. Everyone knows how to make dough. Even though they’re all handling very different things, they come together at the end and combine well, because you and your friends have been making cake together for a while and you followed a very detailed recipe.",
"Using source control software. There's a server which has the \"master\" version of the code and each team member commits changes to that when they've completed a bit of work. The other members of the team can their get those changes onto their computer by downloading them from the server when convenient. Often different people will make changes to the same file. When this happens there's a conflict which the source control software will flag up and someone will have to merge the two versions of the file. You can get software that will show you exactly which bits are different (likely built into the source control system). As for how they decide who works on what, it depends on the application. Maybe each programmer is given some features to be responsible for, or maybe work is divided up by discipline (e.g. for a game one programmer knows about graphics, so they do the graphics work, another does physics and so on).",
"There is one thing that I don't think has been mentioned yet, and that's the concept of interfaces. By breaking up what you want to do in modules, and having well defined expectations for what each module should do, I don't need to wait for you to finish your part before I use it. I trust in the contract made by the description of the functionality. Perhaps a bit abstract? Let's try an example. A team is making a calculator. Jim is working on the addition functionality, and he documents that he will be making a function called \"add\" which takes two numbers and returns a result. Awesome. Wendy is working on multiplication. She knows that she can do it by using Jim's addition feature repeatedly rather than implementing the whole thing herself (after all, 3x3 can just be add(add(3,3),3). Jim won't be finished until next week, but Wendy can still start working on it today. She can write her code to call that add() function, even though it's not done yet, because it's very clear in what it does. Wendy can write a function which doesn't work until Jim's finished, but suddenly both will start working at the same time. In many applications, this is the way things work. Each section has a well defined boundary onto which it meets another section. Specific functions, specific semantics, which allow for safe, sane interaction. Replacing one component is fine, as long as you expose the exact same function from the completely new implementation. Suppose Wayne finds a new way to do addition that involves fancy quantum mechanics. Wendy doesn't care. All she needs to ask is \"If I call add(3, 4) on your new quantum function, am I still going to get 7 back?\" If it meets the existing advertised, documented functionality, it hasn't had any sort of ripple effect, nobody's started tearing Wendy's code apart to make it support the rewrite, and there's not some sprawling mess of interdependencies between all these features. Designing code this way is a good start at ensuring many developers can take on many different tasks without having to co-ordinate some common central file that everybody needs to tweak for their own piece."
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8xpqy5 | The difference between mixed and augmented reality | Is it MR as soon as it is a 3D object in the real world or do you have to be able to interact with it? | Technology | explainlikeimfive | {
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"There's a bit of misinformation in the other replies. The term 'mixed reality' starting coming into general use in the 90's--[this paper from 1994]( URL_0 ) defines it as: > (...) merging of real and virtual worlds somewhere along the \"virtuality continuum\" which connects completely real environments to completely virtual ones. Basically, anything between actual reality and virtual reality can be considered 'mixed reality'. With this definition, *AR is one particular type of mixed reality*. What the other users seem to be describing as 'MR' is more commonly known as 'augmented virtuality', which is another type of mixed reality. (both 'AR' and 'AV' are described in the same paper cited above)."
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8xs0p1 | What is 'SLI' and is it good for gaming? | Technology | explainlikeimfive | {
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"SLI stands for \"Scalable Link Interface\", and it's Nvidia's name for the technology (ATI/AMD call it \"Crossfire\"). Basically, it's using two or graphics cards to split the workload up and increase your graphical processing power. It *can* be good for gaming, but the trend is usually that a game at release is at the 99% support mark for SLI/Crossfire, and then after a GPU driver update or game update it becomes better. Some games benefit from SLI, some don't. Of course if you're doing two 1080s, then yes you're going to notice a performance over a single 1080, but it's a toss-up between two 1070s and a single 1080. Here's a site that shows some comparison charts: URL_0",
"SLI is essentially NVIDIA's method of linking two GPUs together for a single output. Is it good for gaming? That depends. Some games can see notable improvements, but in some cases you can actually see a decrease in framerate (though that's not very common). Obviously it's more expensive because it requires you to have two graphics cards. They also have to be the same model (You can't combine a GTX 1080 with a GTX 970, for example). Not all motherboards support SLI. You can also bottleneck one if they're not EXACTLY the same, since the \"slower\" card will become the \"dominant\" one and the \"faster\" one will match it. There's also the problem of micro stuttering, which can make frame rate wonky. In general, you do tend to see an increase in performance, but it's not guaranteed.",
"It’s a technique to use two NVidia brand graphics cards (of the same type) to improve game performance. The way it works is frame *interlacing*. While one card is preparing a frame to be displayed, the other already works on the next frame. This allows many frames to be displayed per second (smooth motion) even if each frame takes a long time to complete. It does not help, and can worsen, the *delay* in getting a frame to the screen. If it takes each card 1/30 of a second to render each frame, and they take turns you may see 60 unique frames displayed per second. But if you do something, it will take (at least) 1/30 of a second for the results to appear on the screen. An updated frame after you move/shoot/whatever needs to be created from scratch. It also never *doubles* the performance, and sometimes it works very poorly. So it’s usually better to buy a 1080 instead of 2x 1070s, for example. It will get you a performance boost which is more consistent and without the drawbacks of SLI. It’s also more power efficient and usually cheaper. If you have an enormous budget, and you’re already getting a 1080Ti or other top-tier card, getting 2 of those is your only option for better performance because there’s nothing for you to buy that’s better on its own.",
"SLI stands for \"Scalable Link Interface,\" and it's nVidia's technology for linking up to four graphics cards together to produce a single output. However, games need to explicitly support the technology, and with the advances made in GPU power these days, you don't really accrue much benefit from it."
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8xsl2o | How are passwords on websites "brute-forced" when almost all websites limit how many attempts can be made within a certain time frame? | Technology | explainlikeimfive | {
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"The concern isn't hackers trying your password in a website's log-in form. It's hackers stealing the entire password database off of a website and trying to reverse the passwords on their own computers, with no attempt limits. If you have an insecure password that's been re-used, they can figure out what password you used in seconds and then try the same email/password combination on other websites. If you have strong and unique passwords, they won't be able to figure it out in a reasonable amount of time.",
"That's a setting. What if I was able to download the entire content of a server, but I didn't have the passwords? I could set it up in my own environment, turn off that setting, and then attempt to access the data using brute force.",
"Consider the fact that you might have 20 different logins on different websites. I bet you have the same passwords on a lot of them. XYZ site gets hacked. Like, totally hacked. They have 300,000 users in a plaintext password database, or a poorly-salted password database that's vulnerable to rainbow tables (precomputed hashes). Somewhere between 50 & #37; and 100 & #37; of the passwords are decrypted. Yours is among them. Now, they have username-password combinations to try on a bunch of other sites. Instead of guessing your password among tens of trillions of possibilities, now they have, like, one. Now they can try username-password combos with a MUCH higher rate of success, despite rate limiting. username x, password y ... nope username z, password a ... nope username b, password c ... hit!",
"Brute forcing is not as common as it once was. Rather... Brute forcing a single account does not happen against major sites because they have the measures in place that you state. What we see now are brute forces against multiple accounts (we literally just had this at work). These work much the same as old days where someone sends X passwords to the site but for Y users. You are more likely to be breached via a database dump than brute force providing you follow complexity requirements",
"Here is the deal. The true advice is to have a 'different' password for every site online. People stealing accounts have gotten pretty fucking smart. They go out and steal a database from place (A). Then they contact a buddy who has a database from another place. Then they find another buddy. One person might purchase the other two databases, or they might all get together. Now, none of these databases will have complete information. Database (A) might have really secure passwords/usernames but leave addresses in plain text. Database (B) has username/passwords but not much else and database (C) has some variation. You take all three databases, you throw them in bucket and start doing searches looking for hits. When you find a duplicate street address or phone number or username on one and a password on another - BAMMM! This is how it is done. Only with more then 3 databases. And automation. It really is very impressive, if not terrifying. ---------------- Now, thing is, all of us have a couple of enormous weak spots. The first is our lack of knowledge on how any website handles personal information. You sign up to Reddit and they want certain things... we have no way of knowing how that is getting handled. It is impossible to know. The other is that we are human. Asking you to memorize 72 different passwords that are 8 characters, nonsensical, upper and lowercase and special characters is just an assanine request to make. It is what needs to be done - but you can't expect people to do that. ----------------- So what do you do? I recomend password managers. I use URL_0 . There is a competing product called Keepass. Chrome has one built in. Apple products have had the 'keychain' since forever."
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8xu412 | Why do some software processes (like the bot used in the r/thanosdidnothingwrong's snap) slow down in the last few percentiles? | Technology | explainlikeimfive | {
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"Inefficiency of the implemented algorithm. And in movies for the dramatic effect. A good example of inefficiency can be demonstrated by two ways of picking 40 out of 100 lottery numbers: The first one picks a random number 0..100, checks if the number has already been picked. If so, it will retry this step. If not, it will display this number. The second one picks a random number 0..(amount of numbers left), display that one and removes it from the numbers left. Now you have only unpicked numbers left. The second one will take as long as the amount of numbers you want to pick. The first one will take as long as it needs until the random number picker finds an unpicked number, which is at least the amount of numbers you want to pick and can be very long if the random number picked never is an unpicked number. For the dramatic effect, that is just art and needs no logical or technical explanation."
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8xuf4l | How do they condition the air inside the ISS when the ISS is in the vacuum of space? | If the “air conditioning” process requires pulling air over coils to remove the heat from the system how do they do this for the ISS which is in a vacuum? | Technology | explainlikeimfive | {
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"Air from inside the station is filtered and passed through the thermal control system, which uses heat exchangers to dump waste heat from inside the station out into space. [Here's a short article about it.]( URL_0 )",
"I work on the space station and can answer this! The space station cooling system (Thermal Control System, TCS) is quite interesting! Externally (ETCS), there are many massive radiators. These radiators reject heat that is carried from the rest of the space station through liquid ammonia in pipes! Like water cooling your computer, but with ammonia. BUT! Ammonia is very dangerous! We don't want it inside the space station near the astronauts! So inside (ITCS) we use water! The water sucks up heat in large air conditioners (quite a few air conditioners inside) and flows to certain places in where the walls of the space station are extra thin. Here, where the walls are thin, water passes heat through the wall to the ammonia, which passes heat to te radiators! These places where the walls are thin we call \"Interface heat exchangers\" (IFHX) because the heat is exchanged from water to ammonia. If you have any other questions, do ask!",
"Radiators. The ISS has [2 sets of massive radiators]( URL_0 ) and 4 smaller ones that are part of the thermal control system. Heat exchangers inside the pressurized modules collect heat, transfer it to multiple water and ammonia coolant loops, and then transfer it to the radiators where it's dissipated into space."
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8xupij | Why is it when you watch tv shows 90s/80s there are strange lighting effects created by moving lights on screen but not prior to this time or after? | Example of this: URL_0 as seen at 12:35 created by the tray being held I think the answer might lie in something to do with the refresh rate of the camera but I just can’t understand why there was no issue prior or after... broadcast frames have always been roughly the same so it just didn’t make sense. Possible I have this whole thing backwards but it just interested me to know | Technology | explainlikeimfive | {
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"An educated guess on my part, is that prior to the 80s, most TV shows were shot on film. Starting in the 80s, they started shooting shows on videotape. The tubes in the video cameras did not deal well with lights in the shots. There was a lot of streaking and burn in from the lights. You can also see this effect on some 70s shows like All in the Family, which were shot on videotape.",
"It has to do with the cameras they are recorded with. At the time bright lighting would \"burn\" into the photosensitive sensors leaving a streak or flicker on the film."
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8xviyc | Why is it odd for data plans to be unlimited but odd for wifi plans to be limited? Aren't they similar? What are the differences? | Technology | explainlikeimfive | {
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"I'll make a analogy for this. Data is like a small car being used to deliver water. Let's say you want to provide \"unlimited\" water to someone with that car, it's hard to maintain. Meanwhile a WiFi connection is like a bunch of water pipes. It's really easy to provide tons of water via pipes, it doesn't cost too much either so you definitely could provide \"unlimited\" in this case. (For most internet plans it can provide unlimited for the entire month you paid for, at the speed it is advertised) Although sadly due to Comcast and Cox both being horrible companies, those have both silently implimented 1000gb data caps on all their internet saying that the average person will never use more than that (even though many families are complaining about having to pay extra fees cause they go over very often) and if you do need unlimited you can pay more for it.",
"When you pay for wired internet, you're paying for a connection speed. They have to run a cable out to you and have the infrastructure built up so you can use that speed even during peak hours. Once they have the capacity built into the pipe then it doesn't cost them any more if you use just a little or a lot. Someone downloading Terabytes of data between 12am and 5am is actually less of a strain on their network than someone who has 4 different Netflix streams going in their house between 6pm and 8pm. Despite consuming significantly more data, they use far less critical bandwidth and don't need to be factored into peak capacity. With a 4G connection you pay for data because data represents the amount of time your device spent talking to the tower. The tower can only hold so many conversations at once so if you're always talking to it(downloading data) then that's one spot that's always taken up. If too many people need too much data from the tower then it will slow down for everyone in the area and they'll have to add another tower to support all the users. If you consumed less data then you'd keep the tower less busy. Data caps slow people's consumption and reduce the capacity they need to built. Plus marketing has convinced people it should be that way so it's kind of just been accepted. I remember when unlimited data was standard. I remember when you had limited text messages. I remember when WiFi wasn't synonymous with wired broadband internet....",
"Cable companies are greedy and all however they do have to lease data cable usage from other providers or build them themselves. The recent Marea cable cost hundreds of millions for instance. So there is a cost to providing data. It can actually be traded like a resource like oil. However the margins cable companies make on it are quite incredible."
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8xxmxi | Why we can't or don't use satellites to directly transmit cell service instead of cell towers? | Similar to satellite phones. Wouldn't that help spread service to more rural areas and make it less likely to have dead zones? | Technology | explainlikeimfive | {
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"We use hexagonal cells for networking. Those shape give us no blind spots or overlapping. This allows us to re-use cellular frequencies making data plans affordabl. Satellites cant do that for us since we would have to have a lot more individual frequencies compare to popular hexagon cell techniques. Also, signals would be weak and good coverage would require lots of satellites, making it costly to provide internet to mobile devices. URL_0",
"latency is a big issue , I worked with Xplornet setting up satellite internet. The satellites being bounced off of are almost 40000km away. those signals then are sent back down to a relay station and go where needed from there . In the case of the internet for example using standard cable/fiber connections your signal goes from your house to your provider and then follows a chain of relays to get to that gaming server in california and then works its way back along the same path. Round trips are several hundred to several thousand kms causing PING times of 10-80ish ms usually. Now the same signal through satellite service leaves your house travels 40000km to satellite in space which then beams back down 40000km to a relay station on earth and then goes through path similar to before and then goes back the same way to your house. Now our distance travelled is over 160000km total and causes a ping time of around 400-600ms . Impossible to game on and it's very difficult to have a 2 way communication . Also factor in that the actual angle to receive those signals is extremely narrow its just not practical. There is such a thing as satellite cell phones but they are mostly for adventure types to call for help with in emergency situations. Where its more of a broadcast than a 2 way how do you do convo."
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8xxx2d | Why does alt-tabbing out of some fullscreen apps cause black screens or partial alt-tabbing? | Technology | explainlikeimfive | {
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"It depends on which fullscreen mode you're using. If you use borderless fullscreen. It's basically windowed mode without the border to fill up 100 & #37; of the screen space. In this case, everything on the desktop is kept in memory and you can switch back to it in an instant. If you use the real fullscreen mode, which is the case you're asking about. It releases desktop content from memory and let the app take exclusive control of the graphics card. When you alt-tab out of this fullscreen. It will take a second to re-render the desktop before it can be presented to you. That's why there's black screen."
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8y0fhq | How do vacuum tube valves work and what are they used for | I’ve been looking at headphone amplifiers and notice a lot of them use vacuum tube valves. However I don’t understand what they are used for and what their role is within the circuit of the amplifier! | Technology | explainlikeimfive | {
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"A vacuum tube (known as a valve in the UK) is an predecessor to the transistor. They allow a small current to control the flow of a larger current, which is an important part of any form of amplification. Vaccum tubes introduce distortion that transistors do not. People who were used to the distortion complained transistors lacked the \"warm\" sound that vacuum tubes have, and wrongly thought they were a superior form of sound amplification. This one of the many forms of snake oil audiophiles fall for, on the same level as $1000 HDMI cables.",
"One part gets super hot, *very* similar to the filament of a light bulb. This causes negatively-charged electrons to “boil” away from its surface and if nothing is in their way (they’re in a vacuum), they can be pulled towards another part of the tube by applying a positive charge to the other part. In its simplest form this creates a one-way valve for current where electrons flow from filament to “plate” (the positive side of things). You can also add a “grid” in between, and by changing the voltage on the grid you’ll limit this flow of electrons. The grid itself requires almost no power to be put into it, so a small, weak change in voltage can be applied there and it will produce a major change in current through the tube. Run that current through a load (resistor, transformer) and you’ve taken a small voltage and made a bigger one— amplification."
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8y2eo7 | What specifically happens when a speaker “blows out”? | Technology | explainlikeimfive | {
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"Electromagnets are made up of coils of wire which produce magnetic force when you send electricity through them. This is how speakers work. Those wires can literally melt (or deform a lot) if you push too much power through them. The moving part of the speaker also \"floats\", suspended by soft, flexible parts. It needs to be held in the proper location to not hit/scrape on anything, but not be held too \"tightly\" or it won't be able to move. If you physically move it too much you can damage this system and it will rub on other parts as a result. It will either make noise or not be able to move freely. The overheating/melting of the wires I mentioned before can also cause this second result, even if they're not hot enough to totally break and fail to carry electricity.",
"Usually something rips/tears. It can be the speaker cone itself, the elastic material at the edge of the speaker cone, or the elastic material that holds the magnet/coil. It's also possible for wires to break/detach."
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8y3sa2 | How does one get ROMs from video game cartridges? | I am always wondering how people get ROMs from video game cartridges. And then, how do programmers develop emulators to run the games on a computer (like how do they decode all the data on the cartridges?) | Technology | explainlikeimfive | {
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"There's hardware you plug the cartridge into and then into your computer that can read the contents of the cartridge and send it to a ROM file. [Here's an example.]( URL_1 ) Emulation development is a very broad topic and I don't think I could do it justice here, but video game emulator developers will typically obtain or reverse engineer the instruction set for the hardware that a particular video game console uses. Once one developer has done this, the information is out there and others don't need to repeat this work. They then use that info to write software which will read the instructions and process them in the correct way. This isn't a perfect process and there can be a difference in the way an emulator performs compared to an actual console. Here's some resources: URL_2 URL_0",
"Assuming there's read only memory (ROM) on the circuit in the cartridge, and that any system reads that memory into RAM in order to run the operations, all you need to do is connect a lead somewhere in between, and one to their common ground, them record the changes in voltage as the ROM is read. Things gives you a bitstream of the ROM that you can then encode onto a file. To create an emulator you just need to know what chipset the system used then execute the same (binary/ assembly) commands that the system does fit the same command set, and ofc produce the necessary output on the monitor as opposed to the video out threat the system used. If the system isn't using something proprietary, the functionality of standard chips are publicly available. If it is proprietary, there may be some reverse engineering required.",
"The cartridges hold data which can be read like any other stored data, using the right “language” and equipment to hook it up. They’re more similar to modern flash memory— used in USB sticks, memory cards, etc— than technologies like floppy disks, CDs, etc, that were used during or shortly after that time. So the basics aren’t unusual/difficult, but making (or having a company make) the equipment to plug them in to save data to a computer was costly at first. Emulators are a trickier subject. An NES or SNES game console had hardware that worked VERY differently, and was physically different, from modern systems. To emulate that hardware, developers need to analyze how it’s physically built, **or** what it does, and figure out how to make modern computers do the same thing. If feeding a SNES “x” code makes it fetch data from memory, that’s not the same command that makes a modern computer fetch data from memory. So you write another “layer” of code that says— if you see “x” command, do “y” (when y is a command a modern computer can understand) and in this way “translate”. This is oversimplified, maybe wrong in some specific ways, and not the only way to make an emulator. But it gives you an idea of some of the things programmers might take into account when making one."
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8y4xln | What is block-chain technology and how does it work? | Technology | explainlikeimfive | {
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"Okay, I am going to actually try to ELY5 So imagine you, me and 3 other people (Johnny, Sally and Steve). All 5 of us have a book and pen. The book contains record of the balance of all 5 of our bank account. Like so * You: $5 * Me: $3 * Johnny: $2 * Sally: $25 * Steve: $0 Johnny wants to sell 5 of his apples to Sally for $20. Sally doesn't actually have physical money, she just has the balance that we all say is in her account. We all note in our respective books that Sally has given Johnny $20. Then Johnny gives Sally the 5 apples. So the new balances in our journal are Like so: * You: $5 * Me: $3 * Johnny: $22 * Sally: $5 * Steve: $0 BUT Steve is a scumbag. He tries to write in his journal that Sally gave HIM the $20. So his journal is different: Like so * You: $5 * Me: $3 * Johnny: $2 * Sally: $5 * Steve: $20 Let say Steve now tries to spend his $20 to buy some gum from me. Steve tries to pay me $20 but we all look in our journal and see that Steve's balance is $0 and he can't pay me $20. Similarly if we were to check Johnny's balance we would all conclude that it was $22 and not $2 like Steve claims. This is esentially block-chian but with millions of People. Everyone has a copy of everything. The main difference is things are anonymous. So we wouldn't know each others names. But everyone knows the balances of each and every account and what transactions occur in it. A few people can try to change the state of the whole thing but the truth is determined by the consensus of the majority."
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8y52hm | Why is the read head in a VCR slightly askew? | [Such as in this image]( URL_0 ) I have taken apart a couple VCRs before, but never understood, why is the read head slightly askew? | Technology | explainlikeimfive | {
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"Video signals need a lot of information to store and VHS needs to store information very densely on the tape. To accomplish this it uses a helical scan head. Instead of writing one stripe of data along the whole length of the tape (like audio tapes do) it writes a series of stripes diagonally across the tape as it moves along. The head is at an angle to the tape and it rotates rapidly, while the tape moves relatively slowly. Each rotation writes or reads one stripe of data, and by the next rotation, the tape has moved along a little bit and the head writes another stripe right next to it.",
"It is called [“helical scan”]( URL_0 ) and by imprinting in angled stripes on the tape a higher frequency signal can be stored without requiring the tape to be moving at extremely high speed. By tilting the head a greater distance can be covered on a wider, more slowly feeding tape."
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8y53q3 | How does apple’s 3D Touch work? How does it tell you are pressing harder? | Technology | explainlikeimfive | {
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"The first version, which costs Apple about $20 I believe, uses four sensors, which are probably strain gauges. This has a lot of similarity to some modern bathroom scales. There are indications that Apple may drop 3D Touch. Here's a video of a lower cost approach from Peratech URL_0"
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8y5ewn | How can USB 3.0 be faster than USB 2.0? | Technology | explainlikeimfive | {
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"There's more than one reason, but a key difference is half-duplex vs full duplex. Imagine having a conversation with someone where you speak, then they speak while you listen. That is half-duplex. Now imagine having a conversation where both of you are speaking and listening simultaneously (over the top of each other), with both of you understanding completely. That is asynchronous communication - far more efficient. There are more wires used in 3.x connections. More wires in the cable means methods for noise immunity will let you send bits faster without losing bits along the way. Tradeoff is that you can't have cables as long.",
"USB 3.1 gen 1 (formerly known as USB 3.0) added 5 extra pins to the type A connector: two additional differential pairs (in addition to the single pair on the four existing pins) and an extra ground. Having two dedicated unidirectional pairs in addition to a single bidirectional pair enabled the faster transfer speeds of 3.1g1 and 3.1g2, and I believe 3.2 gen 1 will use the same connector."
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8y7mmd | Internal combustion engine was invented a couple centuries ago. Why haven't we come up with something better by now? | Technology | explainlikeimfive | {
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"It's primarily due to the fact that internal combustion engines have a relatively high power to weight ratio. You COULD use a nuclear reactor to power your car, but the weight of the required plant to get you anywhere in a timely fashion would be horribly large. And, when you add up all of the losses due to efficiency, internal combustion engines are actually fair to good when it comes to converting stored energy to motion when compared against other propositions. I'm specifically thinking of hydrogen cars with that last line.",
"Better, or commercially viable? We have. Electric cars. They’re the transport of the future.",
"Yes. Read about the Chinese. Europe invented glass because it didn’t have China and porcelain. China capped out on ingenuity because porcelain isn’t transparent. No glass windows. No glass alembics. They did something so well it hamstrung them. Also we have better things. But like... we spent all this time perfecting the ICE. It’s difficult to rationalize taking literally decades of R & D expenses and cultural change head-on in order to beat something that already works. Hence hydrogen cars being weird things you see on TV and battery technology still being kind of shit."
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8y8iae | how are archaeological sites located? Treasure maps and clues like the movies, or does technology like ground penetrating radar have a bigger role now? | Technology | explainlikeimfive | {
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"A lot of times we have references to places that no longer exist so we are pretty confident that we know where they are. Names do not change as often and can persist for thousands of years. Even if there are no historical records the name itself often refers to what was there. To find the exact site to dig you often does have some remaining features in the landscape from the buildings and such. Even if there are no remaining features above ground you can often look at the landscape and see what the best location to place something is which will give you a pretty good guess. Ground penetrating radar often gives you are very inconclusive result as it can only see vague patterns and features underground. It does not tell you what those features are made by, how old they are or if they are indeed made by man. And often aerial studies using radar or infrared cameras can tell you about similar features and is much faster. But to really find out what is at a site you have to dig a trench and look for things. Most of the time archaeological sites are stumbled upon by accident by locals or when doing construction.",
"We’ve had a ‘heatwave’ in the uk and Ireland the past few weeks which has dried out a lot of grass leaving crop marks, revealing some pretty interesting sites. Like this possible henge at Newgrange, Ireland. [Newgrange ]( URL_0 )",
"Accident is a popular one. Hitting stuff while disrupting the ground, whether for construction or plowing a field, is a tried and true method. If the people who make the find are curious or civic-minded enough to report it, it can then be checked out and assessed. Studying old documents is another. If you know where some places are, and have contemporary documentation talking about some other place you're interested in but haven't located, you might be able to roughly triangulate a place to look. If it's recorded as being three days from point A, two days from point B, and near geographic feature C, you can make some educated guesses. These days, aerial and satellite imagety has become more and more useful. From an plane, one might be able to see patterns in crops caused by differences in soil resulting from buried structures ([this has been used recently in Britain]( URL_1 )). A LIDAR scan of a jungle might reveal temples hidden under the canopy ([Here's an article about a Mayan site so discovered]( URL_2 )). Satellite imagery meanwhile can show differences in density of the soil, revealing old road networks and waterways ([a technique being used for Middle Eastern sites]( URL_3 )). Also, like you suggested, GPR is a method, though that is typically not coming in to play until you already know something is there, and are just trying to narrow down specifically where to dig. It's not a practical tool for initial discovery. EDIT: [This was actually in the news today]( URL_0 ), because of extreme heat causing crops to reveal buried ruins in Wales.",
"In the US land used for construction that has any amount of federal funding must undergo an archaeological survey. We call this a phase one and dig what’re called shovel test pits or STPs based on some predetermined methodology. The holes are dug by hand and the material is pushed through the 1/8” screens. The holes are generally 30x30x80-100 (varies by client). Digging stops if a level identified by geomorphologists is determined to be subsoil or bedrock. The minimum requirement of Section 106 is to have the holes no more than 30m apart from each other and they must cover the entirety of the project area. 15m intervals are required for areas identified as high probability. GPR is a highly useful tool in archaeology but the majority of US archaeological field work is what we call CRM (cultural resource management) and has to bid on contracts and fit within their budget. Most of these companies very rarely use GPR and almost exclusively only use it after some initial discovery has been made and additional money has been allocated to further survey the project area. Using GPR to survey large areas isn’t cost of time efficient and it’s difficult to operate GPR in difficult terrain. Operating GPR is similar to pushing a weighted baby stroller. It’s necessary to clear brush over large areas to access most isolated areas with GPR etc etc etc. GPR will also give very many false positives and frequently identify many anomalies that turn out to be natural changes in soil density",
"Or follow Howard Carter's footsteps and dig up half the desert to find King Tut's tomb. URL_0",
"Theres quite a few ways: 1) survey- finding some random artifacts/bones/stone tools on the surface in a concentration high enough to warrant further investigation. Usually this is done by local field technicians or bone hunters who then contact an archaeologist to do more work. 2) geological survey: if one archaeologist found a site/artifact/etc. at a certain rock layer people will check other places that have that same rock layer (strata) for artifacts/bones/etc. 3) floods/construction/high erosion areas: help uncover a lot of dirt/sand and can reveal all kinda of things 4) water: people tend to live near water for a bunch of reasons! looking at where the water level used to be for the time frame you are looking at, gives you a better chance at finding a site. 5) Drones/Google Maps: extremely rare but some archaeologists check google earth for monumental architecture 6) Migration patterns: if we find a type of pottery/stone tool in one area and the same kind of pottery/stone tool (same shape/decoration/materials/etc.) then somewhere in between may be another site. Archaeologists will try to find paths that make sense (once again near water or paths where cattle could pass- depends on your time frame) *Archaeologists also dig test pits if they find a concentration of interesting materials. Depending on the finds they can be expanded into full blown trenches *Ground penetrating radar (GPR) can help find sites but are really only used when theres a level of certainty that a site is close by. GPR is expensive and time consuming! TL;DR: Finding archaeological sites can seem random and based entirely on luck from an outside perspective. In reality it is a well thought out process based on previous research, general human behavior and surface finds.",
"By accident usually. A farmer dids a hole in a field and hits something weird. Of when a large scale construction like a road is coming through a detailed survey might uncover something. Sometimes it's a hobbyist with a metal detector or someone exploring local folklore. Things like ground penetrating radar isn't brought in until they know someone important is there to justify the costs.",
"Long ago, I put together a survey plan for a small mountain range. We had a smattering of sites known. Broke up the topography into logical types (e.g., various stream terrace levels, several classifications of wind notches, broad ridge tops of various sizes and slopes), determined where we found and did not find sites in the literature. Then went out and surveyed a selection of the various units on foot. That refined the likelihood of finding sites in different areas. Made a prediction of the number of sites in these different areas we would find, selected find or not find for a broader area, and tested. It worked pretty well. Eventually this played into observations that people at X time were using A and B and C areas, but people from Y time were using B and D areas. It was a long time ago and a big area. In another area, we used observation from ground level and air photos to see areas likely of use, went and checked. Kept an eye out. Looked for ancient trails. Found a lot of sites. Some were not related to hunting or travel, but ancient trails led there. Best of these was a material quarry. Thinking like a hunter. I still find sites just walking along. My eyes pick out stone tools regularly, even when I'm not looking. Must have noted hundreds of artefacts just hiking around. They're all over.",
"There are people known as landscape archeologists who know what kind of locations people typically build structures on, and can tell what is man made and what isn't. What looks like a depression in the earth to us can be the sign of an ancient ditch.",
"We did a survey of an area by spreading out and walking in a line scanning the ground for any visible artifacts, which we collected and catalogued. Then turned all the data about the site over to the head Archaeologist at the BLM. He would decide if an excavation was further needed.",
"Archaeologists are training regular people to know what to look for. Recently, in South Africa, an archaeologist recruited cave divers to look more carefully in any and all accessible spaces in the caves they explored. Two of his recruits discovered a new human ancestor deep in a cave where only tiny, skinny people can fit.",
"In the [GlobalXplorer program]( URL_0 ), volunteers use satellite footage to find them from space. Straight lines and other geometric patterns are rarely found in nature, so can be flagged as indicative of human activity. Then ground teams go check them out in person. Anyone can sign up to volunteer, and then you can tell your friends you're a space archaeologist."
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8y9ybv | Why is wireless charging in mobile phones a common thing, but other mobile devices, especially laptops, seem to be far away from that. | I know Dell presented a laptop with wireless charging around last year. But so far I haven't seen much more about this technology build into laptops. It seems to me so practical. Having tables with build in chargers in uni would reduce the cable messes in lecturer halls and libraries significantly. Just one example. But also at home it could be very comfortable to use. It seems even better suited for a laptop than a phone since the laptop usually rests on the table instead of carrying it around. | Technology | explainlikeimfive | {
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"Laptops use a *lot* more power than mobile phones. A typical laptop consumes power at a rate of around 60 Watts. Meanwhile, Qi 1.2 wireless charging tops out at 7.5 Watts. If you do the math on that, the best you're going to get is slowing down the battery drain on the laptop by 12.5%. So if your battery normally dies after two hours, you'd get two hours and fifteen minutes, instead."
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8yao2o | What is Bandwidth and how does it work? | Explain in the most basic human language as possible | Technology | explainlikeimfive | {
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"Imagine you have a pipe. Now let’s imagine that the data you need to watch a youtube video, browse reddit etc is water. The bandwidth in this example would be the amount of water that can pass through the pipe in a given amount of time (often a second). The bigger the pipe the bigger the water flow — > the bigger the bandwidth the bigger the possible data flow."
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8ycn5i | What causes differences between websites on between countries? (Ex. Google US vs Google India, or Netflix Canada vs Netflix Japan) | Technology | explainlikeimfive | {
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"A company wants to earn as much money as possible, so they change their website, selection etc. to earn as much money as possible."
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8yd441 | The technology behind stop lights | Technology | explainlikeimfive | {
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"Some use simple timers, others use sensors to detect cars. I believe the US use loops of wire in the road that generate a magnetic field, and the iron in cars alters the field (a bit like a metal detector at the airport) and so is detected (sometimes bicycles don't trigger these). Here in the UK, its usually an IR emitter, and the pulse of IR is reflected back by a car and detected that way. Sometimes pressure sensors are used, but to my knowledge that is rare, due to reliability issues. No idea where I got that snippet of info from though..."
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8ydgq6 | How does beer become cold from the keg to the tap? | Technology | explainlikeimfive | {
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"The place I used to work for had long refrigerators that you put the kegs in while attached to the tap. So the beer kegs were cold to begin with."
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8yej8p | Why do old cartoons look so jittery? | I'm watching some old cartoons from the 1960s - 1990s and I notice every once in a while the picture will move around sightly. Why is this? | Technology | explainlikeimfive | {
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"Because there supposed to be synced with bass lines and drum hits. URL_0 For real tho, correct if I'm wrong here people but the old way of animating was drawing each frame by hand. It's kinda hard to make sure each individual line or curve is exactly the same frame by frame.",
"A couple of possible explanations. First, there was much more human involvement in both the drawing and the photographing and tracking of frames in those days. Even extremely skilled humans are imperfect. Second, because of the expense of hand-drawing animation, many cheaper cartoons used a lower frame rate (fewer images per second), which can appear more \"jumpy.\"",
"Before animation went digital, the process required intensive physical involvement. The cleaned up line art gets placed on a table that has pegs on top of the background art which is also fixed to the table. A pane of glass is laid over that frame or \"shot\" and a camera situated above the table is fired, recording that frame on film. This process is done over and over for each individual frame. The jittery imagery you may notice comes from the small movements that may move the artwork about on the table, or the artwork itself varies in size or shape in each frame as a result of animating straight ahead instead of pose-to-pose (straight ahead meaning the frames are drawn consecutively from start to end where pose-to-pose allows an animator to maintain greater control over a figure by drawing the frames where the figure makes dramatic changes in pose and then filling in the transition frames much like Walt Disney Studios did in their movies)."
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8yf2wu | What is the difference between using Venmo and using an online banking app to transfer money? | Essentially, why use Venmo when I can transfer money via my banking app? | Technology | explainlikeimfive | {
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"You didn't used to be able to transfer money from all banking apps. Some were free, some charged a free, some didn't permit it at all. For those that did support it it was a multi step process where you either needed their account and routing number or it sent them an email to claim their money Many banking apps have added Zelle over the last year for person to person transfers. Zelle only came into being in 2017 and they've been pushing it this year to compete against venmo. Even with Zelle it's a multi step process for them to actually get their money where they get a text and then have to get it into their account Venmo makes it super easy to send money to the same person again. There's no confirmation on their side, no getting their money. It's streamlined which is the most important feature for mainstream adoption"
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8yg3ao | Why do companies continue to produce 3D Blu-Ray discs if 3D TVs have been out of production for a few years? | Technology | explainlikeimfive | {
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"There are still movies being made in 3D, so it costs nothing extra to produce, there is an audience who will buy them who already own the TVs, so it's a way to make a few extra bucks."
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8yjolj | How are some 3rd party sites offering windows 10 pro keys for under $20 while more commonly known retailers sell it for over $100? What's the catch? | Technology | explainlikeimfive | {
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"The catch is that they're volume lisence keys or stolen or cracked and not real. Grey market sites are a huge risk in terms of whether or not the key is even real, much less functional.",
"It's easy. They're stolen keys, cracked keys, repurposed volume keys taken from companies, \"legit\" keys that were bought with stolen credit cards and all sorts of other things. At best, they're cheap licenses that are meant to be sold in poor developing countries & not here in the US. Pretty much the same shit that goes down if you're buying cut-rate game keys from shady foreign retailers. You're buying stolen goods. There's always a chance your key comes back as invalid or has been sold to other people too. ...and do you want to trust anyone shady enough to steal the keys to **not** steal your credit card?"
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8ykay1 | Why did we shift from calling computer "programs" to calling them "applications?" | Technology | explainlikeimfive | {
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"Mac OS had been calling them applications for a long time. Their application file type is .app while Windows uses .exe (which stands for executable). There are technical difference but I’d argue this is MOSTLY a tradition/preference. Maybe Apple liked that name since it reminds you of *Apple* and these *App*lications run on Apple computers. Well, Apple produced the first massively-popular smartphone and continued to call iPhone programs Applications or Apps for short. This set the standard for how people talk about smartphones and the software they run... similar to *Podcasts* which have nothing to do with iPods anymore, but the name stuck from the time when iPods dominated the market. And since smartphones are as common and often *more* familiar to people than desktop/laptop computers these days, the name also crept over to those devices.",
"Mostly marketing perception. Small and portable computing is the rage right now (although laptops are making a slight comeback.) Most people hear 'program' and think computer which also makes you think bulky and clumsy but when you hear 'app' has been mostly used for mobile (although it was sometimes used to describe computer programs) which makes you think smaller and portable.",
"Applications have user interfaces and perform a useful funtion for a person. A \"program\" is simply code that is executed by a computer.",
"Windows 10 calls everything an app now. It's a little weird seeing \"Microsoft Word - Desktop app\"",
"Speaking as a German, me and pretty much anybody I know still says \"programm\" when it's about computers. Anything on a mobile is an app.",
"Lots of answers but the truth is really a simple answer. All executable code is a computer program. Any program(s) that performs a task or function to assist a user is an application. Ie, printing “hello world” to the console is a simple computer program. A calculator or word processor is an application. Edit: to better answer OPs question, the term application/program has been used interchangeably for as long as I can remember (back to the 80s at least). Albeit smartphone/tablets applications have almost always exclusively been called “apps”. [Compter Program]( URL_1 ) [Computer Application]( URL_0 )",
"While others are pointing out the technical distinction between programs and applications, I always considered \"programs\" to be a Windows term and \"Applications\" to be an OSX (Apple) term. The rise of Apple Mac in the late 90s early 00s saw a rise in the use of their terminology, which was solidified with the introduction and popularity of IOS (Apple's mobile OS) and \"apps\".",
"I’ve been using computers since the mid 80’s and I always saw the program/app thing like this: Computers came out and had programs that you could run. These programs fell into two basic buckets of “games” and “applications”. Applications (apps) were simply any program you built or ran on the computer that wasn’t a game. So an App is also a program. I do wonder if this delineation was helped or even created by the early internet WAREZ community which split everything down into “Apps” and “Games” when ripped and uploaded.",
"Programmer since 1969 here. Terms keep shifting with fashion and with fine or dubious distinctions. **Algorithm:** A strict set of instructions to accomplish something. e.g. cooking recipe. **Computer Program:** An algorithm expressed in code and run by a computer. **Application:** This started out meaning a computer program or set of computer programs *applied* to a business problem as opposed to a computer program to solve other computer programming needs. e.g. operating system or device driver. This gave rise to two disciplines: *Application Programming* and *Systems Programming*. **Applet:** A term coined by Sun (I think) to indicate that a Java Applet was small and run by a web browser. **App:** A term coined for use on phones and then on tablets and then on computers. These are actually full fledged applications and more sophisticated and complex than the applications of the past (c. 1980). However, it refers to a single program. Back in the day (and still today) larger applications consist of multiple programs organized as a network of jobs to aid a business (or scientific) process. These are linked together and run via \"overseeing\" programs (JCL, bash, etc.) and operations staff (people). EDIT: typos and spacing and \"Systems Programming\"",
"I hate the term \"apps\" because I'm from the Tron generation. You can picture programs as being people in the grid, but I can't picture the people being called \"apps\". \"I fight for the users!\" -- > *raises middle finger* < --",
"It’s all because Chili’s is pulling the strings of software development. Placing subliminal messages in our everyday lives. “Download this app!” Also known as appetizer. “Come get an Awesome Blossom App here at Chili’s!” It’s all a conspiracy.",
"Square is a rectangle but a rectangle isn’t a square. Applications are programs but programs are not necessarily applications.",
"Very simple reason: Shortening Application to App sounds better than shortening Program to Prog.",
"The right answer is it's a vocal tic that Steve Jobs had for years. You can find him calling them apps in videos taken in the 1980s.",
"We didn't really. An application is one or more programs that have a business \"application\". For example a funds transfer application may have an entry program that puts user entered data into a database. A program that allows approval of that transfer. A program that actually does the transfer once approved. Or even a couple transfer programs, one for Fed and one for Swift transfers. What has actually happened is in the old days people would talk about the funds transfer \"program\" when it was really several programs. Terminology got cleaned up. To be fair, in the really old days an application WAS a single program. Which is how it all started. Then we started automating more complex stuff.",
"A computer program is any set of instructions that your computer reads and executes. An application, on the other hand, is a program with extra layers to make it more user-friendly. These layers are things like a graphical interface (buttons, text entry fields, check boxes, pictures, etc.) as opposed to a command line interface, improved error handling (a technically-minded person should know how to look up error codes and understand why they caused the error and how to avoid it, but the average person cannot be expected to have such skills), and other things like that. Many parts of an operating system don't affect the graphical presentation of it at all, such as the part that manages internet connections or the part that monitors internal statistics like temperature and memory usage. These would be programs, but not applications. They can usually be accessed, such as if you want to know what your IP address is, but a lot of the time you need to do so with a command line. For more common functions such as checking the battery status on a laptop, though, most common operating systems will have a second program that gets some information from the first and displays it graphically - this is an application.",
"As a software programmer, there is no official difference, but I believe the word change is related to mobile phones and app stores. My opinion is that it was marketing driven, based on that applications can be called \"apps\" which is one syllable, while \"programs\" is two, representing a paradigm shift from software being rare and valuable to common and throwaway. Your average desktop user will have maybe a dozen programs they run. This means that programs are a big investment. When you need a new program, you tend to spend a good amount of time searching around to find the best one, and even once you have found it, you have to navigate through shady download sites that try to install toolbars and such. If it is a very valuable program to you, you may even pay $20 or more. However, this wouldn't work with Mobile phones, as it is much harder to navigate the web on them, so the already complicated process of installing software becomes even more complicated. Thus, the app store was invented. The app store allows software to be vetted and share a common interface so that they can be installed with a simple button click. However, with this easier process, there are a lot more people willing to develop throwaway programs for cheap in the hope that they can make a small amount of money. As a result, the price (and quality) of software went way down, so instead of paying $20, people expect to pay $2. To cope with this, marketers try to get more people to buy the software. To do this, they pushed the idea that you should buy software even if you don't really need it, as it will only cost you a couple dollars and a few minutes. Part of this marketing shift was the word \"app\", a simple one syllable, throwaway word. So at some point program = desktop and app = mobile. However, with Windows 8 Microsoft had the fantastic (/s) idea of creating one OS for both desktop and mobile. At that point, app was the trendy new one syllable word, while program was the dusty old two syllable word, so they started pushing the word \"app\" for everything."
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8yljem | - when a program or game has a bug, how do developers track it down? | This is more about games.. when a bug is found and needs to be patched, is there an easy way of tracking it down based on what it is? Or is it just luck? | Technology | explainlikeimfive | {
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"Depends on the bug. If you're lucky, the bug is associated with an error in the log, which will tell you exactly where the error is happening and gives you a good idea of what code you need to be looking at to fix it. If you're unlucky, you'll have to go through a tedious process of elimination--is it a hardware issue, is it a network issue, is it a problem in the UI layer, is it a data issue...I'm simplifying, but basically, you look at the bug and make a list of all the things that *could* be causing it and carefully and thoughtfully run tests to eliminate each as a possible cause. Depending on the bug, that process could take days or months to complete, which is why sometimes companies just decide not to fix it.",
"Through a tedious process called debugging. Basically you run the program one step at a time and check where is it malfunctioning. For example if you had a bunch if math operations and you checked the results one at a time you could see that X*X=Y instead of X^2. Then you could fix whatever code is causing the malfunction."
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8ym5d4 | What's the difference between say, a 16gb micro sd card vs a 256gb micro sd card from a physical standpoint? | Obviously the 256gb one can hold more data, but how does it do that if they're exactly the same size (and weight to my knowledge). Does the 256gb one have more places to store data inside? Does the 16gb one intentionally block off storage that could otherwise be used in larger capacity cards? | Technology | explainlikeimfive | {
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"The rectangular plastic thing you see from outside is just the \"shell\". Inside, there are a series of solid state memory chips, that hold the data. Higher capacity sd cards just have more and/or higher density memory chips inside. They do not artificially block off \"excess memory\", because the memory chips are the expensive part, it wouldn't make sense to put unused ones in there.",
"Let's compare it to cribnotes for a test. Your teacher says you're allowed to write two chemistry exams with no textbook but a single sheet of 8 1/2x11\" paper with whatever you want written on it. You really know the material for the first term's exam, so you only need a few reminders on your sheet. You write really big. But the second exam is all new material and your cribsheet for that one needs to have a lot more information. So you print a LOT smaller, using a very fine pen. As a result, you get a lot more information on your cribsheet, but you have to be precise when you write so you don't mash answers into each other, and you have to use separating lines or colour coding so it's readable. Micro SD cards are the same: they can pack more information into the same storage volume by using more precise manufacturing techniques. Work is at such a fine and tiny scale that printing the memory cards has to be extremely precise to avoid blotting and blurring, and they have to change the cataloguing and access systems so the data can be found and retrieved fast enough. The more the amount of storage, the tinier and more precise you have to be. Capacity for these cards continues to grow because our manufacturing processes are continuing to get more and more precise as time passes. But why are they the same size though? Well, memory cards with different capacity still have to plug into different devices, so you need a one-size-fits all solution as much as possible."
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8yp24u | Why is it often advised to unplug an electronic device for a few minutes to resolve an issue? How does unplugging it (instead of restarting it) make a difference? E.g. Smart TVs | Technology | explainlikeimfive | {
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"Every electronic device with a microprocessor, will have a memory cache. This cache is constantly sending and receiving data to and from the processor, and acts as a buffer for the data as it cannot be processed all at once. The data in these memory caches is subject to malformation and corruption, often resulting in operational errors of the device. The only way of clearing these caches, is to stop the flow of power / electricity to them.",
"The capacitors will still hold a charge, if still plugged in. Sometimes unplugging and holding a button down for 30 seconds will resolve some very odd errors. Other reasons also include the device may hold some persistent information that isn't cleared out unless it has total loss of power."
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8yre2k | How do password managers sync passwords between devices without compromising security? | Technology | explainlikeimfive | {
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"They sync an encrypted file with the passwords. You still need to decrypt it with your master password in each device."
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8yrz27 | How do smartphone fingerprint sensors work so quickly when sensors used for visas at embassies are back-lit and take longer? | Technology | explainlikeimfive | {
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"Your smartphone is reading your print vs a small library of a couple of prints you gave it. Those other computers as reading your print and have to compare it to all of the prints it has access to. So it is just as fast to read it but the database size causes it to slow down more and more the bigger the db of the comparing entitity.",
"So, the technology we have isn't actually comparing fingerprints per se. They take A few points on the fingerprint, and compare them. The more precise you need the comparison to be, the more points you analyze, the longer it takes. The phone scanner couldn't reasonably keep everyone but you out, so they settled for speed over precision. If you took 20 people with the same fingerprint type as you (arch, whirl) and messed a bit with angle and pressure, you could probably get into at least one other phone. But, that's super impractical, so for most use that standard of security is perfectly fine."
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8yt6hj | How digital signatures work | And how you can verify it as authentic without being able to forge it. | Technology | explainlikeimfive | {
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"Digital signatures rely on something called public key cryptography. You're probably familiar with a [rotation cipher]( URL_0 ). This is where you encode a message by substituting one letter for another letter that is later in the alphabet. The number of letters you shift over is called the *key*. If your key is 1, then encrypting a message works like this: A = > B, B = > C, C = > D, etc. If your key is 5, encrypting works like this: A = > F, B = > G, C = > H, etc. You send this message to a friend, who knows the key you used. They take each letter, count backwards in the alphabet the amount that the key says, and substitute letters that way. If they do it right, they should get the original message back. This is an example of _symmetric key cryptography_, because the same key (the number 5) was used to both encrypt and decrypt the message. Symmetric key cryptography is awesome and useful, but it can't be used to create digital signatures. Enter public key cryptography. In public key cryptography, there are two keys. We'll call them A and B for now. The way this works is that any message encrypted using key A can only be decrypted with key B. Also, any message encrypted with key B can only be decrypted with key A. Also, if you only have one of the keys, it's impossible to figure out what the other key is. There are a couple different ways to do this, but the most common is called RSA. There are lots of articles and videos about RSA if you want to learn more about it. Now that you have your two keys, A and B, you pick one of them (let's say A), and publish it somewhere where everyone can see it. This is your *public key*. You keep the other one (B) secret. Now, if someone wants to send you a message, they can encrypt the message with key A. Since you're the only person with key B, only you will be able to read it. But, remember, you can do things the other way around. If you encrypt something with key B, anyone with key A can decrypt it and read it. But since key A is public, and everyone has key A, that means anyone can decrypt your message, so what good is it? Well, key A only works with messages encrypted with key B. Since you're the only person with key B, then by decrypting this message, the whole world can be sure that *you* sent the message. The fact that the message can be decrypted with your public key is like having your unique signature on the message. This is the basic idea behind digital signatures. So, let's say I want to send you a secret message, and when you receive it, you want to be sure it was me that sent it. We each generate a public and private key. We tell each other our public keys. I take the secret message and first encrypt it with my private key. I have effectively signed the message, but anyone with my public key can still read it. So, I encrypt it with your public key. I send it to you, you decrypt it with your private key, then decrypt it again with my public key. You now have a secret message that only I could have sent.",
"There are differing methods, but I'm going to simply go over private/public key signatures. TLDR: *Imagine a box with a padlock that can only be locked with one key and unlocked with a matching, but different, key everyone else has. If only you hold the key that can lock the box nobody else can change the document you are signing, because they wouldn't be able to lock the box again. Thus, if somebody has a locked box that your matching key can open the only person who could have locked the box was you, and thus the document contained in the box must have been created, or at least approved, by you.* ____________________________ Assume you want to sign some document D. What you do is find a pair of keys that obey a certain mathmatical property. One of those keys is the private key and must be kept secret, The other is a public key and anyone can see and use it. Assume a function F that takes in a key and a message and returns an encrypted message that depends on both the key and the document. You cannot reverse this function except by just guessing the key and message and hoping the same jumble comes out, so the key you used to sign is still safe. The property of our secret keys and this function is that encrypting a message with one key gives you a signature, and encrypting the signature with the other key gives you back the document. If the private key is S and public key is P, then you can \"sign\" a document D like so: Signiture = F(S,D). If anyone wants to verify that you signed it they take your public key and check if the following holds: D = F(P,Signiture). Because your private key can \"unlock\" the signature, it must have been created using your private key. Since you are the only one who has your private key people can be comfortable in knowing you created that document and that signature."
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8ytzgs | Why does Yamaha make so many different things | Technology | explainlikeimfive | {
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"Yamaha is a Japanese company and Japan has historically taken a very different approach to \"the corporation\" then U.S. or European companies. This exists formally (companies doing lots of things) and informally with a system called \"kereitsu\", this itself is an evolution of the broken up family-based conglomerates called \"zaibatsu\". Either way these are focused around functional capability rather then what you see in the U.S. which is often based on brands. These were roughly horizontal, vertical or distribution based organizations - leveraging a capacity in one of these and then piping all sorts of products through them. In the U.S. we'd say \"a car company couldn't make refrigerators\" and the Japanese company might say \"a company is really good a manufacturing with metals\".",
"Started as Piano makers... When Honda motorcycles became an instant success in the early 60's, they jumped on too...And- being a post war Japanese company, Quality and affordability made them one of the best Companies in the world- to this day",
"Would you wear Yamaha clothing if they made that too? Yamaha high heels and underwear? Or would you eat Yamaha potato chips?"
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8yvsna | What exactly is happening when lightning strikes and electricity drops out for a second? | Technology | explainlikeimfive | {
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"The lightning causes a power spike on the line. There are protective circuit breakers that open to help prevent damage. The breakers have automatic reset circuits in them so they don’t have to constantly be manually reset. In the event the breakers opened for something other than a transient spike, like a downed line/tree branch on the line, the auto reset circuits will only allow so many resets in a certain period of time before they stay open."
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8ywnjg | How were the first metals mined? | The only thing coming up is around the time they were discovered and how the metals were extracted from their ores. Pretty much asking what type of tools did they use? | Technology | explainlikeimfive | {
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"Copper the first. You can find its ore in fairly pure forms and cold work it(beat it into shape with a big rock) into stuff like bowls. Then they discovered that heating it made it softer and easier to work Then it was found that melting it and mixing it with tin(also easy to find on the surface) resulted in Bronze which was much sturdier than copper or tin, and thus began the Bronze Age. All of the first metals have relatively pure and easily accessible ores. Metals like aluminum require significant processing to turn from ore into metal which is why they only started being used relatively recently."
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8yx5b5 | How did Disney animation work and how did they save money despite it being different characters? | Referring to these examples: URL_0 I see that the actions are the same but they are different characters. How could Disney save money by supposedly "reusing animation"? What did the animation process look like so that they could save money? How did the animation work? | Technology | explainlikeimfive | {
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"Tracing or, with old animation, painting over the cells. They didn't have to have artists create it all from scratch. They don't have to worry about rejecting pieces because the pov doesn't match up, etc. All that is done already.",
"Instead of figuring out all the angles one frame at a time you can reuse the work others did and draw the new characters over the old ones. Drawing characters doesn't take a lot of time, what takes time is figuring out how it is supposed to move around and around with all the perspective changes. With that all figured out in advance the actual drawing is easier. You can even outsource it to an assistant or something while you work on an original bit"
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8yyon0 | What benefit are the zero G experiments on the ISS to us on Earth, where zero G is rarely (if ever) encountered? | Technology | explainlikeimfive | {
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"Eventually we will need to explore space. A mars colony would be at much lower gravity than earth and we don’t think that would be a good thing for development of baby anythings. Another thing is we need to figure out what solar radiation will do to our food or other things we grow."
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8yza2o | Why do some TVs show a quick black screen when changing channels and why some don't? | Technology | explainlikeimfive | {
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"It’s your cable box that has more to do with the black screen than your actual television. Some cable boxes processing power and connection are faster than others. The black screen is your cable box or satellite taking a second to get the signal from whatever network you are wanting to get access to."
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8yzttn | Where does the energy go if a solar panel is in the sun but isn't hooked up to anything? | Technology | explainlikeimfive | {
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"if im not wrong, it \"stays\" inside the silicon cells in the panel. basically the electrons cant flow because there is no circuit to flow through, so they are released but never used. i suppose they just recombine with other silicon atoms. edit: pretty much into heat. nothing more."
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8z1w0d | Why does underflow occur in computers? | With overflow I understand that there's a mechanical quirk/limitation in a CPU that prevents it from retaining every single bit (and so you just end up with a bunch of 0s or whatnot) I get that underflow results from taking an integer and then subtracting so much you go past 0, but I don't get what the mechanical quirk is. I know some about one's and two's complements, and I've tried doing out the one complement method that I think a CPU uses, but 0 - 1 also ends up as 1 (and I don't know if that's because that's what's supposed to happen or if I'm just stupid). I also realized that if you had 00000001 the two's complement would be 11111111, but if you're using unsigned integers I don't get how the CPU would just take 00000001 and automatically apply the complement. So I guess, what's actually happening *within* the CPU that's forcing underflow to occur? | Technology | explainlikeimfive | {
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"Underflow is a concept dealing with floating-point numbers. You're not talking about floating-point numbers, so you're probably talking about negative overflow, not underflow. Imagine a 2-bit computer. Each register has 4 possible values: Bit pattern|Signed|Unsigned :--:|:--:|:--: 00|0|0 01|1|1 10|-2|2 11|-1|3 You can see, for signed integers, 1 + 1 = -2. That is an example of overflow. Similarly, -2 - 1 = 1. That is an example of negative overflow. When interpreting registers as unsigned integers, 1 + 1 = 2 is well-defined, and 2 - 1 = 1 is also well-defined. However, 3 + 1 = 0 (overflow) and 0 - 1 = 3 (negative overflow). Keep in mind that, for arithmetic integer operations, CPUs have no idea what a signed or unsigned number is. There is only one \"add\" instruction (which works exactly the same way, regardless if the numbers are interpreted as signed or unsigned) and similarly for \"sub\", etc. For those instructions, the CPUs are just mindlessly shifting bits around. It's only when you do a comparison instruction, or make an external representation of the numbers (such as printing them out) that you need to consider them as signed or unsigned.",
"Twos complement is more common than Ones compliment in modern computers Lets say I want to perform subtraction of two unsigned integers and want to do 1-2. You'll take the binary value of 2(0000 0010) convert it to its Twos complement(1111 1110) and add it to 1(0000 0001) giving you 1111 1111 which is the unsigned value for 255. This is an underflow because you've wrapped around zero and gotten a high value. This is because you're interpreting your end result as being unsigned when it should really be a signed integer represented as -1. The result in binary is exactly the same as if you performed it using two signed integers, its only an issue with the fact that the software is treating the resulting integer as being unsigned."
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8z29wh | when and why our ancestors started cooking the food instead of eating them raw? | Technology | explainlikeimfive | {
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"It could have been an accident. Someone dropped some food in the fire, but they ate it anyway. Waste not want not, etc. Maybe they liked the taste and cooked food gave them an edge. Or perhaps fire was a deity in those days. Maybe throwing some meat into the fire was a way to “feed” the god who protects us in the night. And maybe that god blessed our food by cleansing it, improving the taste, and giving us more energy.",
"Cooking generally increases the net energy in food (gross energy - energy required for digestion). Humans who cooked would get more energy out of less food, giving them an advantage during lean times.",
"I don’t think anyone knows why. Probably just experimentation with fire. “ooga ooga fire make pointy stick stronger” “ooga ooga fire make food better for Booga”"
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8z2z5m | Why do capacitors in CRT TVs from 50 years ago still work, but every LCD I've had blew a capacitor in less than 5 years? | Technology | explainlikeimfive | {
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"people like to parrot *planned obsolescence* but there is a much simpler explanation that does not require the assumption of any malice on the part of manufacturers. it is just cheaper to make and more profitable to sell a product which works exactly as long as it is warrantied for and not much longer. the buyer is promised a certain expectation and the seller meets it. if the product exceeds the specified life, it is over engineered and the next round of cost cutting in the manufacturing process will identify and eliminate the expensive step (I.e. capacitors , or any other part for that matter, will be iterated down the quality hierarchy until the product fails minimum lifetime requirements). over years and decades of design and engineering the build quality settles to the minimum demanded by the market. in is an art that separates the small players from the industry juggernauts. that's right. it takes two hands to clap. TVs don't last 20 years because no one is willing to pay for one that does. besides, they are going to upgrade in a few yrs time anyway and the old one is going to the landfill so it better be cheap. people want the latest tech bells and whistles which come along every 1-2 yrs (any electronic devices come to mind?) at an affordable price . incidentally, that's how long things tend to last. because neither buyer nor seller really needs it to last.",
"Probably not the answer you're looking for but I'd guess it was them intentionally installing cheaper/lower quality ones they know will fail so you upgrade sooner. Planned obsolescence... But that's just my opinion... No facts or anything to back this up. Lol",
"Planned obsolescence. When the model T was invented, people would buy one and it would last a lifetime. Companies had to start making their cars intentionally shit so you'd pay more to maintain and replace them."
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8z3dx2 | When data is compressed or zipped, what is actually happening to the data? | Technology | explainlikeimfive | {
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"For most algorithms, the compressor will search for a pattern that appears multiple times within the data, and then replace that pattern with a shorter symbol, and create an entry in a \"dictionary\" recording what each symbol means. Compressing algorithms can get a little more complex than that, but that's the general idea.",
"There are two types of compression algorithms. Lossless compression such as those used in zip files and lossy compression such as those used in jpeg images. Lossless compression basically takes the data and stores a summary of it. Enough data is stored that the computer can reconstruct the original file without losing any data. Lossless compression algorithms are used where every detail must be preserved such as for office documents, computer executables or source code. Lossy compression does the same thing as lossless compression but goes one up by removing details that humans can't perceive. Because it relies on research on what things humans can or can't perceive lossy compression algorithms are specific to certain types of files. For example jpeg for images and mp3 for audio files.",
"The simplest compression algorithm is to look for repeats. Take this comment for example. Start by looking for every time a letter is repeated and replace the two letters with a single symbol that means \"this letter repeated twice\". We could write \"compression\" as \"compreßion\", and \"letter\" as \"leπer\". We've just saved ourselves 1 character in each of those words, thus compressing them. We can also look for the most common pair of letters, such as \"th\", and replace those with a symbol (\"the\" and \"this\" can become \"þe\" and \"þis\"), again saving us one letter in each of those words. Repeat this enough times and you will have compressed the text to its most compact form."
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8z5rrb | how do watches work? | How do each of them work specifically? What’s the spinny thing you always see on the inside? | Technology | explainlikeimfive | {
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"Electric watches work off a quartz oscillator. If you apply electricity to a small piece of quartz (or other crystals, but quartz is usually the one used), the quartz will vibrate at a specific frequency. Put very simply, you can build a circuit that will output a waveform in time with the quartz's vibrating frequency. Quartz vibrates very steadily, so the timing on the output waveform is very accurate. To use it to tell time, you feed that oscillating output into a microcontroller (a very small and simple computer) that keeps track of how many times the quartz has oscillated. The microcontroller is programmed for a specific frequency, so knowing how many times it has oscillated against how many times it oscillates per second lets the microcontroller know when a second has passed. It doesn't keep track of the time, just tells the hands to move when it calculates that a second has passed."
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8z6v3t | The cult of Volvo owners. What makes Volvos so beloved? What makes them preferable/superior to other manufacturers? | Technology | explainlikeimfive | {
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"Volvos are incredibly safe. They're engineered to safety standards that far surpass regular US standards. One of the founders of Volvo had a wife killed in an auto accident and ever since then, they've been pioneers in automobile safety and standards. They enforce standards that haven't been made required yet which is why they surpass legal guidelines.",
"My family owned a Volvo and there was a sports car that smacked into it thankfully when no one was inside. The other car was destroyed, the Volvo was fine and you couldn't really tell it was hit.",
"volvos are frigging tanks. they aren't sexy, they aren't fast (from the factory), they aren't luxurious, they aren't even cheap. but man they will last forever and ever. a family friend had a volvo. she got t-boned by a SUV at a stop sign in what we think is rear quarter panel. it spun her around 180degrees. we tried to find where on body panel she was hit.....but couldn't.",
"They are very long-lived, very durable, safe as houses, and also appeal to the tastes of those who desire to have something different."
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8z71ep | How are games like "Breath of the Wild" ported over to a completely different console (Switch) with different hardware, yet are flawlessly identical when playing both? | Technology | explainlikeimfive | {
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"I don't know the precise answer but the best vague one I can give is that the GPU/CPU architecture on the switch is well known since it runs off Tegra X1 and uses the Maxwell architecture which there is lots of information on. The previous generation consoles were an absolute nightmare to Port games to due to how closed off and complicated hardware was due extreme paranoia of piracy. I heard that porting games to PS3 was so difficult that many devs just opted not to bother and go for the Xbox instead. The Switch uses the same chipset as the shield tablet which runs Android apps pretty well so I imagine it being easy to adjust to."
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8z8as8 | Why people advice not to use cellphones in the gas station? What could happen? | Technology | explainlikeimfive | {
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"The theory is that the radiation caused by a cellphone making or receiving a call could cause fuel vapors to explode. The Mythbusters [busted the shit]( URL_0 ) out of this one, though -- there's absolutely no risk associated with using a phone.",
"Im surprised by these answers I thought it was because they didn’t want you distracted while filling up and leaking fuel everywhere",
"It used to be believed that the cellphone signal receiver could somehow ignite the gasoline. But myth busters did an episode about it. Along with a bunch of other stuff about gas station fired. Link here: URL_0",
"Electrical spark caused by static and your phone could ignite vapors from the gas hose and tank and blow up causing you to die."
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8zbil3 | why don’t we make coffee like we do tea, by seeping the grounds in a bag? | Or alternatively, would it be possible to make tea like we do coffee, with a drip machine? Also is there a reason we don’t make a chocolate drink using cocoa beans ground up like coffee grounds? Would it just be too bitter? | Technology | explainlikeimfive | {
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"edit: RIP my inbox *Coffee cherries are their own fruit from the coffee tree. We do not make coffee from the pits of the cherries we eat. Please do not try this. You could die. Thank you. First off, remember that coffee is the roasted seed of a cherry that is pulverized in a grinder, while tea is actual dried leaves from the tea plant. Because we can grind coffee really coarsely or super fine, we control the extraction time to get the proper strength from the coffee. Finer grind has more surface area (i.e. espresso), and we can get all the good stuff out in under 30 seconds. A big, coarse grind like for french press, can take 4 minutes. As for why we don't use coffee bags regularly, it's for a couple of reasons. Coffee stales very quickly once ground, much faster than tea. It also has to do with 'fines'. Because coffee is a brittle, organic seed, when it is ground, you get a range of particles from large to small. You'd need a bag permeable enough to let the coffee steep and for water to move through it, but also not allow all of the fine particles through. This is simple with gravity brewing like pour over or drip because the water will eventually get out. It's not really moving if it is in a bag in a cup, so the filter would have to allow for the smaller stuff to wind up in the cup and your coffee will be 'muddy'. This happens with french press too, and some people enjoy the body of this type of coffee for that reason. Tea, on the other hand, more or less behaves the same, and needs to be steeped for several minutes to get the most flavor from it. Chopping the leaves up finer helps somewhat, but it seriously affects the flavor of the tea, as breaking the leaves causes them to lose a lot of their essential oils and flavor. If you've ever had a really nice loose leaf black tea next to, say, Liptons bagged tea, there's no comparison. So, yes, you could mill up tea leaves small enough to make a drip machine make 'tea', but it probably wouldn't be very nice. Your last question about cocoa - Chocolate is the most complicated process of the 3. Cacao beans are fermented, dried, roasted, dechaffed, ground, pressed with sugar, blended with cocoa liquor.... It's a crazy process that I can't understand how we figured out it was possible in the first place. If the roasted 'cocoa bean', or cacao nib were just ground up and steeped, it would be very bitter, and probably not to your taste, but this was basically what was drank by the ancient peoples of Mesoamerica (with added chili and spices for some fire). Instead, we just make sweetened cocoa powder that is ground super fine, kinda water soluble and we drink the 'grinds', unlike coffee.",
"I would argue that a French press is pretty similar to the way we make loose-leaf tea. As others have said, the tea leaves need more contact with the water so a drip-type coffee maker wouldn't work with regular tea.",
"They do make coffee bags[ like you describe]( URL_0 ). I seem to remember one of the major U.S. brands trying this, but I don't believe it caught on.",
"Cold brew is basically making tea without a bag, just not using heat. I guess its more like sun tea. And there definitely is a drink made up of ground cocoa beans like coffee. I don't know the name of it but had some in the Dominican Republic. It was literally just \"coffee\" made with roasted cocoa beans. It was really good, tasted like dark chocolate.",
"I think it all has to do with the extraction of soluble solids. There are many different ways to brew coffee, but the best method for producing the “perfect cup” is to get the water temperature just below boiling and pour it over the grounds. The amount of time the water is in contact with the grounds is also very important. Too much time yields too much extraction, and thus a bitter cup. Just as important is the consistency and size of the grind. Tea, in the other hand, is best when the water has more contact with the leaves. It must simply take longer to extract the soluble solids from leaves.",
"Every morning I choose three different teas to mix together along with a bit of coffee. I put the raw ingredients into a cup without a bag or anything, add hot water, add milk, and then drink it through a straw with a filter on the end as to not sip up tea leaves/coffee grounds. Before I got really into tea, I would put 2/3 coffee and 1/3 tea into my coffee machine and it also worked perfectly fine. The method i currently use is more effective for tea than it is coffee, and my old method is more effective for coffee because coffee's optimal temperature is higher than tea, but both methods certainly work for both. Edit: since this seems to bother people, on my days off I'll typically have about 4 or 5 cups of this, and when I work I usually have about 3. I pee roughly every 45 minutes or so.",
"I wouldn't say it's *always* better for tea leaves to contact water for a longer time... it's possible to over-brew tea which causes it to be bitter. But most types of teas, brewed the way most people like them, require longer contact with water than coffee. Comments have given a few different names for it but a coffee machine that brews coffee this way is called a **french press**. Keeping the coffee grounds loose in the water (like a french press does) instead of packed in a bag lets them all contact water, instead of leaving some dry, without needing as much time to accomplish this. It's a variant on an idea much like a tea bag, that fits the quicker brew time of coffee.",
"We do: URL_0 They taste like filter coffee. I’m guessing they’re not popular due to them being a) more expensive, and b) less convenient than instant coffee or tea.",
"There are a bunch of different ways to brew coffee or tea. I use a french press to make coffee. I put grounds in a press, pour in hot water, and then let it steep. Similarly, my tea-drinking wife puts tea leaves in a metal ball thing with holes in it, puts it in a mug and pours hot water in it. It's pretty much the same process. As far as why coffee doesn't come in tea bags, probably because people tend to make coffee by the pot. That would be a lot of coffee bags. It may also have to do with how easy it is to alter the strength of your coffee when you get to dictate how much grounds are used.",
"My favorite hot drink is literally just ground cacao beans in a French press. Look up Crio Bru or Choffy.",
"You can make cold brew like you do tea. It requires a fair amount of coarse grounds and a lot of time though.",
"To answer the question of why we don’t brew cacao beans in a similar style to coffee: culture. American culture thinks of dessert, sugar, and creaminess when we think of chocolate. Brewed cacao beans are slightly bitter, and hardly taste like our idea of chocolate. However, many South American countries do brew cacao beans in a way similar to coffee, and it’s absolutely delicious. You let the roasted cacao nibs steep in water just under a boil for about 10 minutes. Then you can drink it hot, or cool it and serve over ice. I would highly recommend it.",
"Regular brain: making tea with a coffee filter. Expanding brain: making tea in a keurig Galaxy brain: making coffee in a gaiwan",
"Coffee in tea-bags exist; but you need more coffee so the bags are larger. I’ve seen theses mostly used at hotels in the rooms.",
"People do, in various cultures, brew and prepare drinks as you've described. There is a company called Chocosol that makes a spicy chocolate drink that is very popular at their local farmer's markets.",
"A few people have pointed out that brewing coffee in a french press is similar to steeping tea. I would like to add that the reason we don't steep tea in a french press is because pressing down on tea leaves will cause the tea to be bitter.",
"You can, and people do make coffee like tea and vise versa. A french press works by steeping coffee grounds in hot water similar to tea leaves in a teabag that are filtered out after a certain time. You can make tea in a drip machine. There is coffee sold in teabags (instant coffee).",
"Cold brew is kind of like making tea but a way longer process. It still involves grinding the beans but I have to soak the grounds in water for 12-18 hours depending on how strong I want the final product. You stick the grounds in a fine strainer, one that won’t let the grounds loosely seep through into the water but will slow drip into it.",
"Correct way to make tea is china pot*, loose leaves, tea strainer at the ready when poured. Principle is no different from a coffee percolator, except that the coffee gets less time in contact with the water, and the strainer is integral. * And don't forget, warm the pot first with a rinse of boiling water, and then \"Unless the kettle boiling be, filling the teapot spoils the tea\".",
"But we do! Cold brew coffee is made but putting coarse grounds in a \"sock\" and seeping it in water for a long time (~24 hours or longer depending on volume of water). This produces a stronger coffee with less acidity. We also have the french pressed coffee which is _similar_ to how we make tea in which we seep the grounds except the grounds are not in a bag but instead loose."
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8zepm4 | How do antivirus apps work? What are the looking for when they “scan” our files? | Technology | explainlikeimfive | {
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"There are two primary methods for virus detection: signature-based and heuristics-based. A signature-based antivirus program looks at the files on your system and calculates a specific value based on the file's contents. It has a list of values that it knows correspond to viruses and other malware; if it sees one of them pop up on your machine, it knows to delete it. These definitions are updated often, and are very good for detecting and cleaning known threats. Not so good for code that changes, or new threats. Which leads us to... Heuristics. It's a fancy word for a simple concept, and what it boils down to is that your antivirus program will simulate the effects of unknown code in its own private sandbox, and watches the commands as they run. If it looks like a virus, the program will flag it. Advantages: not reliant on signature lists, can detect new variants of old viruses. Disadvantages: can be slower, can generate false positives."
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8zf0eo | Why do super high fps cameras (like a Phantom) record at such low resolution | I understand that recording at a high resolution and an extremely high framerate would generate a lot of data, but surely we have storage mediums large enough to contain and process this data? | Technology | explainlikeimfive | {
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"First off, this isn't true of all super high FPS cameras: URL_0 Second, it's not a matter of storage space, but of write speed. If you had to write one thousand sentences per minute, your sentences would be extremely small, regardless of how much paper you have."
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8zhcgv | How Videogame developers manage to optimize their games and make them run smoother on lower-end devices? | Technology | explainlikeimfive | {
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"Literally by being smart. Videogames often are demanding applications and require to use some interesting tricks in order to make them faster. An example is imagine you need to draw an image that has multiple layers. There is no need to draw the stuff in the background that will be masked. Or maybe you need to find a number among thousands, if you need to do it often enough there are data structures that will give you the number faster if you are willing to sacrifice some memory. I hope that helps to explain it."
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8zi3b6 | Why are moving fan blades visible through a phones camera but not with the naked eye? | Technology | explainlikeimfive | {
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"Disclaimer: I'm not an expert on the brain. However, as I understand it, our eyes don't work like cameras. Our brains take in a certain amount of light in a given period of time and process that (kind of like a long exposure). So when something moves really fast, our eyes pick up the whole trail, but our brains process it as one image, so you see a blur. Cameras, on the other hand, use a shutter to actually cut off an image. When you're taking a video at 60 fps, then the shutter physically closes 60 times in a second and you get 60 images. So, as long as your shutter is fast enough, the fan blades will hardly move when the sensors are exposed to light and you don't get blur. Basically, as I understand it, it comes from our brains doing more of a continuous processing, versus cameras which are much more discrete, but I would love someone to fact check me on that."
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8zi6m2 | How are episodes of TV shows leaked before their release dates? Why do studios not heavily regulate who has access to the material and hence prevent leaks? Or do some studios leak their episodes themselves? | Technology | explainlikeimfive | {
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"text": [
"Episodes of TV don’t just appear on a server somewhere all queues up to air. Producing, marketing and distributing episodes of television require having them pass through a lot of hands just on a basic mechanical level to get them to air. There is a ton of post-production, editing of promos and trailers, teams that work on translations for foreign markets, presser copies sent out to critics so they can write reviews of new seasons, etc. Some episodes of some shows get locked down as tightly as possible, but there is still only so much you can do if you want the thing to exist and show up on public TV screens at some point. All it takes is one person in the chain uploading a copy when they shouldn’t."
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8zjgqm | How does a speaker emulate the sound of many different instruments all playing at the same time at different layers / rhythms? | Technology | explainlikeimfive | {
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"text": [
"All sound is actually rapidly changing air pressure. The air pressure at your eardrum can really only have a single value at a single moment; the fact that we can mentally process that varying pressure into all the differerent instruments and voices is really a testament to how wonderful our brains are! So the speaker just has to reproduce, to a certain level of accuracy, the same pattern of varying air pressure.",
"It’s not actually a bunch of different sounds, they just combine to a certain frequency. The speaker then shakes the air at that frequency."
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8zl30u | What are wingdings/dingbats, where do they come from and why do they exist as a font? | Technology | explainlikeimfive | {
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"It makes it easy to include some basic pictures/symbols in a document without having to import real images.",
"I used to write TV listings for newspapers and I would have used dingbats for film star ratings. HHHHH = ☆☆☆☆☆",
"In the earlier days of computing this was a way to include symbols that were not yet included as letters of there own. Instead fonts were developed that display existing letters as symbols. Vox made a neat little video about this: URL_0",
"As a way to get things like trademarks (^TM), and other random symbols onto documents as a vector font file (for scalability) instead of importing pixel-based images (that would be blurry when changing its size. It’s not meant as a legible font as most other fonts are, and it’s a little weird that people actually think it’s akin to any other QWERTY font",
"I was so confused before I read the whole post, I thought they were some Australian animals or something along those lines."
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8zlagl | Why do phones still (or ever) need SIM cards? | Technology | explainlikeimfive | {
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"text": [
"Technologically, they don't. It's a feature to have easily removable phone credentials that are independent from any particular phone and don't rely on a phone to exist (for example in situations where you don't have two phones simultaneously to transition them).",
"The SIM card is used to identify the subscriber (you) with your service provider. A SIM card makes it easy to switch providers (just take out the old SIM card and put in your new one) or your phone (just take the SIM card out of your old phone and put it in the new one)."
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8zoegq | why can my heaters easily keep my house at a nice 75 when its 15 degrees outside, but my AC struggles to dip below 70 when its 100 outside? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"What kind of air-conditioning do you have (central, swamp, etc...)?",
"Your heaters are a hell of a lot more powerful than your Air Conditioners An AC unit can move 4-10 watts of heat per watt of power used, but it'll only use a few hundred watts. A big window AC unit might be rated at 10,000 BTU/hour or about 2.9 kW of heat removal which sounds pretty good, until you consider that a 6 foot electric baseboard can be a 1.5 kW heater and you'll likely have significantly more of them than you will air conditioners Your house likely has the ability to add 10 kW of heat to the space but is only able to remove 2-4 kW"
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8zrdmt | What is the Windows .NET framework, and why is it useful? | Technology | explainlikeimfive | {
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"Cooking, eating, washing dishes, and getting rid of trash all took a lot longer and was less effective before we standardized dish sizes, cooking instruments, had a stove and a dishwasher, and were able put all the trash on the curb where it magically disappears later. Frameworks represent standards, appliances, garbage collection, and easy means of getting things to and from your code/house to remote locations/landfills that you haven't the slightest idea about how they work. Additionally, If you write your code to the framework, you can be sure it will work on anything that the framework says it can run on. In the case of Windows .NET, that means 'any' version of Windows. In the case of DotNetCore, that's starting to mean 'any' modern device. There's a few asterisks in there, but that wouldn't be ELI5.",
"When making a piece of software, like an app for a phone or a website, programmers need to do a lot of common tasks, like joining the word ‘Hello’ with your name to make a greeting or sending a file across the internet. To make the software do this from scratch requires a lot of time and effort and knowledge about the physical machine. The .NET Framework has a lot of the common stuff already written for programmers to use so that they can concentrate on the things that make software brilliant like ease of use and useful features. It also means they don’t have to worry about their code not working on a particular computer as if the framework can be installed then their code will work too.",
"The .NET Framework is two main things: 1- A standard library - this is a very large set of built in functions and classes, so when a programmer needs to do something like get the square root of a number, or get the content of a web page, they can use the standard framework classes and it's fast and easy. 2- A virtual machine - .NET runs on a virtual machine, like java, so when they port the framework to various systems you get almost automatic cross platform support. Bonus: The .NET framework supports awesome languages such as C# and F#",
"There's some things most programs need to do. Access a database. Talk to another program over the internet. Ask a user for some information. Frameworks, such as .net, do this for programmers. Thus they don't need to worry about the HOW of what they want to do, they can worry about the WHY and WHAT they they want to do. .Net is a little different that other frameworks in that it is an embrella. Where other tech stacks (lists of technologies a company uses) may list a half dozen or more frameworks, each solving a different problem, .net provides a \"one stop shop\" to solve those problems, all which play nicy with each other. Companies like frameworks as it keeps the coders focused on their problems and engaged in interesting work. Programmers like frameworks as it helps get rid of the tediousness of the job, and helps make jumping jobs easier (I may not knoe the business your company is in, but I can listen to the people who do and know the frameworks you use)."
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8zudhh | How do we discover moons around Jupiter just now, when we have discovered planets more than a thousand light years away from us before that? | Technology | explainlikeimfive | {
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"text": [
"because they are very small and you can only spot them when the sun hits Jupiter and the moon is between Jupiter and Earth",
"On a bit of a tangent, for the same reason as how we still haven't figured out if there's another planet in our solar sytem. We detect exoplanets by the transit method, meaning the planet passes in front of it's host star, of course this won't work for planets in our own solar system, or at least not those further than the sun than earth Edit: said tranfer instead of transit",
"Keep in mind that \"moon\" can mean any natural satellite that's not pointlessly tiny chunks in a ring system. The newly discovered moons of Jupiter are not the well known planet-sized objects that we typically imagine as moons. They're small fragments of rock that Jupiter has collected in orbit over the eons. Four of Jupiter's moons contain 99.997% of the mass in the moon system, the rest are cosmic gravel. Finding these pebbles is a lot more challenging than identifying a behemoth gas giant in another solar system since their gravity and ability to block light are negligible."
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8zvuhn | Why can't we recycle the stuff that's sent to landfill? | Technology | explainlikeimfive | {
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"There are two reasons, both of which are applicable in many cases: 1) Things that are mixed together are more expensive to take apart. Aluminum cans are easy to recycle because they are almost pure aluminum. There is aluminum in food packaging, but it's bonded to paper, plastic, and other non-aluminum things in a way that's hard to undo. 2) Some things are not very valuable, and the energy that would be needed to process them costs more than the output of the process could be sold for (even when the cost of the landfill is included).",
"Sorting is the problem; it's expensive. Someday when robots are ridiculously cheap, or (less likely) we are truly running out of some key material, we'll dig them back up and sort them to recycle the valuable bits, and likely compost or burn the rest for fertilizer or energy.",
"In general, recycling is what we call it when someone figures out how to break something down and then rebuild it into something else, or just straight re-use or re-purpose it. For example, lots of plastic gets melted into a big blob of mixed plastics, which gets re-formed into something else. With some substances, like certain plastics, metals, and glass, this is pretty easy to do. However, there are some products where recycling would just take so much energy or time or fancy tech that it's simply not worth it now. And even if you can do it in a city, it would be way too inefficient to do in rural areas. So there's a simple question of logistics for certain things. For example: construction scraps. Could someome, somewhere use little broken bits of wood thrown out from a housing build? Sure. But sometimes there simply isn't the demand nearby, or the system to connect the disposer with someone who might want it. And depending on regulations where you live, you can't always just leave stuff on the street and say \"free\" for a variety of health and safety reasons. So what's a contractor to do except throw it out? It's simply not worth their time to try to find someone to take it risk-free. Then there's stuff like styrofoam. Could it theoretically be broken back down into base chemicals and re-used? Probably. But does the technology to do that exist today in a way that's cheap enough and common enough to do that? Not that I know of. (Though there are people working on bacteria that dissolve polystyrenes, so maybe we'll be there soon). Sometimes people say magic is just science we don't understand yet. Landfills are where we put the stuff we don't know how to recycle cost-effecticely *yet*. Maybe someday we'll figure it out. Until then, dump. Although \"mass burn facilities\" are things. Giant incenerators with state-of-the-art filtration for removing toxic fumes and such. It's a way of at least turning trash into heat energy/electricity. But again, expensive and high-tech, so they're not very common...yet. Maybe someday they will be, though.",
"Comes down to money. It doesn't pay to filter the invaluable things. Contrary to popular belief you can filter a good 95% of garbage. But some you can like paper cups. The wax inside the cups to prevent breakage/leak prevents the cup from being recycled. I'm sure there are ways around it by now but.. cost."
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8zwxjc | Why do cable boxes respond to TV remotes so poorly, but video game consoles respond to their controllers excellently? | Technology | explainlikeimfive | {
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"text": [
"1. Not all cable boxes respond to all remotes poorly 2. Completely different technologies. Remotes use IR - basically sending very rapid pulses of infrared light from the remote in a pattern to signify a particular command. This requires direct line of sight for the entire sequence. Modern wireless controllers use bluetooth which is more expensive and elaborate but more stable and does not require line of sight.",
"Most TV remotes use infrared, which is a very slow and very unreliable transmission technology. New devices that use radio-frequency connections (and that aren't designed to be backwards-compatible with infrared devices) respond better."
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8zytn7 | why did you need to wait for the "green light" on old cameras to use the flash? What was taking so long ? | Technology | explainlikeimfive | {
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"The flash bulbs required a large amount of power very quickly in order to produce the flash. The battery in the flash was not capable of delivering that amount of power that fast, so the flash would store a bunch of power in a capacitor which would then deliver it to the bulb for the flash. Once the capacitor discharged, it took a few seconds to charge up again. This isn't a big deal anymore, as our batteries are a lot better and our flashes much more power efficient.",
"The flash in an old handheld camera was a bulb called a flashtube. Basically, the camera's battery would charge up a capacitor to a very high voltage (anywhere from 2,000 to 15,000 volts.) Then the capacitor discharges, creating a spark, which causes a very bright light for a very short period of time. So when you saw the green light, you were waiting for the capacitor to charge.",
"Oh wow I totally forgot that used to be a thing lol. Back then you had to wait for the flash to charge up before it would work. I remember on the disposable cameras you could even hear it whining as the battery charged a capacitor. I was always wondering if the damn thing was going to blow up.",
"As others have said, the camera was filling a capacitor so that the energy could be built up and used to make a bright light from that stored energy. But I'm surprised you ask the way you did as flash cycling time still exists (except for LED \"flash\" like on a smartphone). [This video]( URL_0 ) shows recycling time on a high end Canon flash. Alkaline batteries are slow. The NiMH batteries are much faster as they can produce a higher current."
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8zz4z3 | How can Amazon Prime video know which actors are in which specific seems for every single second of a video? | When watching most Amazon Prime videos you will also have a display that will tell you what actors are in the scene you are watching right that second and what music as well. How is this done? | Technology | explainlikeimfive | {
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"text": [
"Someone actually watches it and tags them. A lot of tv and video stuff like this is just done manually. While it may seem like a lot, people just power through and get it done."
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902ezm | Getting computer programs to utilize multiple CPU cores is difficult because the programs have to be specifically coded that way. Why can't CPUs allocate instructions to different cores themselves? | Technology | explainlikeimfive | {
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"text": [
"The main advantage of programs designed for multi-core use is that they can be sped up by running multiple tasks at the same time on different cores. Some tasks cannot be divided up into multiple simultaneous tasks to take advantage of multiple cores. Imagine the CPU like a restaurant kitchen. The chefs are the cores. Some tasks like a main dish can be sped up this way. It can be divided up into three tasks. One chef makes the meat, one makes the potatoes, and one makes the vegetables. Since they can do each of their tasks at the same time it's quicker to make the meal than having a single chef make each part in sequence. Now imagine you're trying to bake a cake. You too can divide it up into multiple tasks. Mixing ingredients, baking the cake, icing the cake. However fundamentally these cannot be done at the same time. They have to be done in order. You can't bake an unmixed cake, you can't ice an unbaked cake. So you cannot speed this task up by doing one part at the same time as another. A good programmer will write code that makes use of multiple cores if the task they are writing can benefit from it. But not all calculations can be split up into simultaneous tasks. Some tasks, like our cake, cannot be divided into simultaneous operations to take advantage of multicore systems.",
"When a task cannot be partitioned because of sequential constraints, the application of more effort has no effect on the schedule. The bearing of a child takes nine months, no matter how many women are assigned.",
"The problem with doing this on an instruction level is that instructions often require the results of previous instructions to be completed first. So if you're going to execute instructions at the same time, you need something that can figure out which instructions don't rely on the results of others that haven't been executed or are still executing. CPUs already do this. But they don't send the instructions to other cores. A single CPU core has multiple ALUs (Arithmetic Logic Unit) which can operate at the same time. There's only so much you can do with this. Sometimes it just has to wait for the something else to finish, sometimes it doesn't know what instructions need to be executed next such as when it hits a branch (i.e. an if statement). So multiple cores exist to do parallelism on a higher level. That needs a programmer to describe how the program can be split up because it relates to the overall problem at hand, not something that can easily be done by a CPU inspecting instructions."
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905dg0 | Why do noise cancelling headphones make me feel sick? | Technology | explainlikeimfive | {
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"text": [
"So the thing with noise cancelling is that what you hear is not 'silence'. They use anti-noise to cancel out unwanted noise: they measure phase and amplitude of the noise to cancel, and send out an anti-noise with the same amplitude but inverted phase, and the result of this is that you hear 'nothing'. But this only cancels out the vibrations that reach your eardrums directly. The sound vibrations also make your bones in your head vibrate, and this vibration will make your eardrums vibrate nonetheless. Your brain gets confused because of this: It gets the signal 'i hear something' from one place, and the 'i hear nothing' from the other. The more important part of this is that we use audio signals for orientation and balance, to determine distances and our position in the room. The sound your shoes make when you move gives your brain a pretty good idea on the acustics around you: is the sound reflected, how, by what? Noise cancelling earphones tend to cancel out all of this, so your brain immediately looses sensory input it uses for orientation. Example: If you see with your eyes that you stand in a big factory hall and there should be a lot of echo, but you don't hear any, this mismatch of sensory inputs causes the motion sickness like feeling. One addition: When you listen to music, this often adds to the effect, especially with noise-cancelling. Imagine you sit in a small room full of fuzzy and comfy furniture (no echo) and listen to a classical concert recorded in a cathedral (lots of echo), the mismatch is intensified. Your eyes see no huge cathedral, but your ears do, and if you do this in your bedroom, your brain pretty much knows how sounds should actually sound there (this is why everything sounds so strange when you move furniture). If you listen to music with normal earphones, you still get subtle inputs from your surroundings, making it more clear that you just sit on your bed with earphones on, listening to a cathedral concert."
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906r6r | When on a call on speaker, how does the other person not hear their feedback on their end? | Technology | explainlikeimfive | {
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"text": [
"Depends on the phone. Cheap phones have a gate. When the are playing audio they turn the microphone off. More expensive phones have echo cancellation. They know what audio they are producing, then they can subtract that waveform from the incoming audio waveform, leaving everything but the echo. You can tell if your phone is using a gate if only one end of the call can speak at a time.",
"Most VOIP and conferencing systems utilize a technology called Acoustic Echo Cancellation (AEC) that detects the echo of your voice from the other end, then filters it out from the signal. It's literally a textbook example of a technology called adaptive filtering, which is similar in theory to an artificial neural network with a few differences. Namely that the system is less complex and the weights in the system (the values that change as it learns) adapt in real time as opposed to being trained beforehand. AEC works for the echo sounds which are normally a bigger problem than feedback, but the same concepts are applied in systems called Dynamic Feedback Reduction (DFR) which also use adaptive filtering. Those are more commonly found in hearing aids and live sound environments, although they are in a few conferencing systems."
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906xrf | how does Ddosing work and what is bad about it | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Imagine you run a shop, someone malicious with a lot of friends starts sending all their friends to your shop, not to buy anything, not even to browse, just to exist in your shop and take up space. They have a *lot* of friends so eventually your shop is choc full of people with no interest in buying anything from you. At that point, your shop might as well be closed as you can conduct no business. DDoS attacks work the same but digitally. A malicious party starts requesting content from your website, and they keep doing it, and they do it to an extent where legitimate visitors to your site get caught up in all the fake traffic and can't engage with your site. It's not even limited to websites either, any online service can be flooded with communication requests to effectively force the victim functionally offline."
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9086ny | How does sorting by "controversial" work? | Technology | explainlikeimfive | {
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"text": [
"Controversial are posts and comments with a similar number of upvotes and downvotes. So a post will be more controversial if it has lots of upvotes and downvotes, and the upvotes to downvote ratio is close to 1. The actual formula used by reddit is anyone's guess.",
"Probably looks at whether a given thread has received a large amount of both upvotes and downvotes, by percentage of how many people engaged?"
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908pcg | How can video games produce sounds from specific areas in the game? | I.e. when you're playing Call of Duty and you hear gunshots how is it possible for the game to emit the noise in a way where you can figure out where it came from instead of just hearing gunshots? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Science.meme But seriously, it’s all in just using the right balance between left and right to mimic what he hear and how we perceive direction in real life. We experience the sounds we hear all the time in stereo (i.e. out of each of our 2 ears), so it’s *relatively* straightforward to create this same effect by splitting the sounds just right between 2 (or more, but a minimum of 2) speakers. You can confirm by playing one of these games with headphones on backwards. It’s pretty trippy, to be honest.",
"There are two main ways to produce directional sound and positional audio. The theory for each is more or less the same in both stereo speaker configurations and surround sound configurations. The first method is called *amplitude positioning* and is by far the simpler and less computationally intensive of the two. In amplitude positioning, a single sequence of audio samples, such as a voice or gunshot, is played back in each of the speakers at different volumes. Amplitude positioning on a stereo speaker configuration allows for reasonable positioning across one dimension (left/right). positioning across a surround sound setup allows for positioning across two dimensions. The second method is called *head related transfer function*, or HRTF, and is much more computationally complex. HRTFs adjust the pitch, delay, and amplitude (volume) of sounds in order to position them in 3D space. Although surround sound speaker configurations still provide the best positioning, HRTFs can provide excellent and highly accurate positioning on stereo speakers as well. Many \"virtual 7.1\" headsets are in fact stereo headphones with a digital signal processor that uses a set of HRTFs to convert a 7.1 audio signal into a 2.0 audio signal. Running HRTFs in real time is computationally complex and thus demanding of CPU resources, so many sound cards provide hardware acceleration for doing so. Reverberation and other sound processing techniques are often supported in hardware as well."
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908x5o | How Do Machine Learning Algorithms Actually Learn? | Watching an AI play the dinosaur game has got me thinking about this. How does the program make the leap from "jump whenever" to "jump when a cactus is in front of me"? It's really confusing to me how a program is able to learn the same way we are able to. Thanks in advance! | Technology | explainlikeimfive | {
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"text": [
"There are a number of techniques, but it typically boils down to weighted probabilities. Somewhere in the code there might be something that says \"jump 1% of the time when you see a green pixel\". If that leads to a good outcome, the next time that is upped to 2%, then 3%, then 4%, until it reaches some optimal value. That, combined with dozens of similar statements, allows the algorithm to eventually dial in those values to what will win the game. The learning is the process of figuring out what those values should me.",
"The AI is programmed to constantly collect data about its actions, its environment, and the outcome. The data is collected and stored and a graph is developed of the data. After amounts of trial and error, the AI looks at the trend of the graphs it developed and tries to predict the outcome of doing something along the trend. For example, if the AI collects data on three things: 1. Its actions (such as jumping) 2. Its environment (where the cactus is) 3. What the outcome is (the score) Initially the AI will just jump randomly regardless of the environment and the outcome. Then after it collects enough data it may find the trend that the outcome is better (score is higher) when it jumps 20 pixels before the cactus. It will adjust the way it jumps. But then as the game starts speeding up, it may learn that the trend line is changing and it will learn that it should jump 100 pixels earlier, etc."
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10,
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909w5m | how was the internet invented? | Technology | explainlikeimfive | {
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"text": [
"ARPANet originated in the 1970s as a method of connecting various research institutions together. In order to transfer data between them effectively, they needed a protocol to use existing infrastructure (telephone lines) as a conduit for data transfer. Many of the backbone technologies were developed for this purpose. It grew to more and more universities during the 70's, and in the mid 80's the military developed their own system (MILNET) to transfer information themselves, based on the same technology. It didn't take long for the value of this tech to become apparent to the civilian sector, so in the late 80's ISPs began to spring up allowing access to other commercial servers."
],
"score": [
34
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|
90a0m4 | Despite being on the Do Not Call Registry, we receive daily scam calls with fake caller IDs from "Customer Service Department", "Card Member Services", or "Blue Cross Blue Shield and Aetna". What technical or legal limits prevent US telcos from ending this illegal harassment of subscribers? | Technology | explainlikeimfive | {
"a_id": [
"e2oy5td"
],
"text": [
"I don't believe for a moment that they (the phone companies) don't know exactly where a call is coming from, and can't tell when the caller ID data is spoofed. They should be giving us the right to opt out of any call that has it's caller ID spoofed; that would solved 99% of the problem. The last 1% would be taken care of when you called to place a complaint that that company called you and tried to scam you or violated the do-not-call registry."
],
"score": [
3
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"text_urls": [
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|
90csgw | How our electric devices acurately tell us the percentage of battery life. | Technology | explainlikeimfive | {
"a_id": [
"e2pgt5r",
"e2ps0vo",
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"text": [
"Batteries have known characteristics as they deplete, dependent on cell type, age, and quantity ( URL_0 ). Voltage in a battery will slowly decline at a predictable rate until it becomes too low to be useful (depleted). In addition, devices are decent at self-measurement of current draw, and can extrapolate a decent estimate of battery life based off of current draw and the observed voltage of the battery, which tells the device roughly where the battery is on its discharge curve.",
"Voltage is easy to measure, and will drop as battery charge drops. Your 3v battery isn't exaclty 3v, it starts higher & ends lower",
"Usually they measure voltage. Voltage will drop as you discharge the battery: URL_1 However, voltage will also (temporarily) drop the more current you draw and the colder it is. Of course you can measure current and temperature and correct for these effects, but it increases complexity. During charging the voltage will be a bit higher (~0.1V) than if it’s disconnected. That’s why you sometimes see a sudden jump in devices which don’t take this into account. I think some devices (e.g. Lenovo Thinkpads) measure the electric energy going in and out of the battery (i.e. measure battery voltage and current, multiply them and integrate the result over time), which allows them to provide more accurate readings. The downside is that they have to be “recalibrated” by discharging and then fully charging the battery from time to time. Wikipedia article listing the different approaches: URL_0"
],
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"https://www.mpoweruk.com/performance.htm"
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"https://en.wikipedia.org/wiki/State_of_charge",
"http://siliconlightworks.com/image/data/Info_Pages/Li-ion%20Discharge%20Voltage%20Curve%20Typical.jpg"
]
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|
90dnjc | How data is transferred between different towers and my cellphone when I’m playing game and constantly changing my position (like riding in a vehicle)? | Technology | explainlikeimfive | {
"a_id": [
"e2pq15h"
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"text": [
"Each tower advertises their identification, has a synchronisation routine and is able to communicate with your device (UE) to establish how much signal is getting between you and the tower. This allows them communicate with each other to see if another tower is a better candidate for you. Secondary (I'll keep this to 4G technologies only) each tower (eNodeB) has a connection (X2) to near by towers. This allows one to take over if your signal with one beats the other for a period of time -- you don't want to be on the edge of a cell and bounce back and forth between towers. Eventually if you go far enough then you'll do a much larger handover. Towers talk to telecommunications routers (SGWs) and these are also all interlinked so they can hand over to each other. It's a much slower process so this is why traveling on a high speed trains can have more issues related to communications. You may travel even further and hand over between your gateway (PGW) but luckily these are all interconnected with a technology called GTP (GPRS Tunneling Protocol) -- the idea is that your data goes from A to B without knowing or caring how it gets there so you just need to update the routes. You may even need to hand over between the controller (MME) which incidentally is what controls when every other device hands over. Again these are also all interconnected. Fortunately there's a database of who you are, your identity and where you are called a HSS. This helps the network know where you are at all times and provide you a service. This is a tiny subset of the problem and doesn't cover things like. If I go somewhere new and my phone is off, how can I receive phone calls if I move and turn it on again? Source: I build telecommunications equipment."
],
"score": [
9
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} | [
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|
90do0l | How do fibre optic cables actually work? | The extent of my knowledge of fibre optic cables is simply that they carry light as forms of information. How is this information interpreted and how does it generally work? Edit: Thanks for the responses guys! | Technology | explainlikeimfive | {
"a_id": [
"e2pn3a1",
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],
"text": [
"On its most basic functionality you can think of it this way: If the light is on, the receiver thinks it is a 1 If the light is off, the receiver thinks it is a 0 How fast can you change states? Depends on the fiber and the devices connected at each side. Basic fiber connections use two fiber strands. One for receiving and one for transmitting (inverting the function of each strand on each side). More advanced fiber systems allow you to send and receive information over one strand by sending the information on one frequency and receiving it on other frequency. The most advanced systems can send multiple communications over one strand by using multiple frequencies.",
"Lets add a section on light. Light is sent at a specific angle resulting in the angle of refraction equaling 90 degrees, and \"total internal reflection\" occurs. This is how the light travels through the cord, it constantly reflects back and forth without any leaving the material.",
"There is a laser on one end and a photosensitive transistor on the other. Electric signal is used to control the intensity of the laser and the light recieved at the detector side is turned back into electric signal. The middle (the cable) is made out of some carrying material that bends the laser in such way that it reaches the reciever end even if the cable is bent. So basically you take electric signal on one end translate it into electromagnetic radiation (light) send it trough cable and translate it back. Now for translation you can use any of the methods you would use when encoding regular radio signal (this process is called modulation). I think it is very difficult to explain the different types of modulation without pictures. [Here is short introduction.]( URL_0 ) If you have questions about it ask away but I don't think it is possible to ELI5 it without pictures."
],
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"text_urls": [
[],
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"https://www.elprocus.com/different-types-of-modulation-techniques-in-communication-systems/"
]
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} | [
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90e745 | How do phones (or any battery powered device with a readout for battery life) know how much charge their battery has left? | Technology | explainlikeimfive | {
"a_id": [
"e2pq8jo"
],
"text": [
"The voltage drops a bit as the battery gets flat. A typical rechargeable battery starts full at 5v. At 4.9v it is 50% charged. At 4.8v it is 25% charged. The numbers above are made up, the real numbers are dependent on exact battery make/model/design. But you get the idea."
],
"score": [
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|
90een1 | Why aren’t USB and HDMI cables designed to be inserted both ways? | Technology | explainlikeimfive | {
"a_id": [
"e2prsum",
"e2psvgy"
],
"text": [
"It wasn't considered an issue when they were first designed. You weren't expected to be regularly plugging things in, you were expected to just set up your computer and leave it at that.",
"Designing a connector that can be inserted both ways is a little more complex and expensive. It wasn't considered worth the effort when HDMI and USB were designed in 2002 and 1994 respectively. At that time, portable devices weren't nearly as common. It was expected that you'd plug your DVD player, PC monitor or games console in using a HDMI cable once and then leave it there for years, so it didn't matter if it was a little awkward or took multiple tries. Likewise USB was designed as a standard connector for PC keyboards, printers, joysticks, etc, they didn't have people carrying around USB flash drives or charging their phones with it 3 times a day. The latest USB standard does include a both-ways (reversible) connector, and the latest HDMI standard lets you use USB-C cables with HDMI connectors on the end as HDMI cables; it has been rumored for a while that the next big HDMI standard will use plain USB-C cables and effectively make HDMI a 'mode' of USB. In 10 years it's pretty likely we'll be using the same USB-C cables for just about everything. Plug one cable into your phone and the other end into a charger to power it, into a TV for AV-out, into a PC to transfer data, etc. This is all driven by the popularity of portable devices (phones, tablets, laptops, Switches) where (A) everyone's plugging stuff in everywhere multiple times a day and (B) it's nice to only have to carry one cable. Two things that didn't matter at all 20 years ago."
],
"score": [
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|
90fear | Why do the 220V of home outlets kill you but the several thousands of V of a taser dont? | Technology | explainlikeimfive | {
"a_id": [
"e2pxp6o",
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"text": [
"For the upcoming comments saying it's not the volts, its the amps that kill you, my current understanding is this: amps depends on voltage and resistence. For a given body resistence, amps are proportional to the voltage. What's the mechanism i'm missing here?",
"Tasers indeed use high voltage (in the kilovolt range). As noted by others, due to Ohms law (I=U/R) this means you will get a high current. High enough to be considered very harmful. The human body is not a semiconductor, so Ohms law will apply. High voltage = high current. Always. No matter the source impedance, fusing, current controls, etc. The trick to keep tasers non-lethal is that they pulse the current. The victim gets a small number of high intensity shocks with relatively long pauses between them. This keeps the total energy transfered to the target low enough to prevent damage, but the shocks are powerfull enough to cause severe muscle contractions, incapacitating the victim. [source]( URL_0 )",
"Because outlest has more amps and tasers have small amount of miliamps its not volts that kill you but amps like an outlet has 20 amps and a taser has like 4.5 milliamps"
],
"score": [
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"https://www.google.nl/amp/s/spectrum.ieee.org/consumer-electronics/gadgets/how-a-taser-works.amp.html"
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|
90g3v1 | How did those inbuilt battery testers work? | Technology | explainlikeimfive | {
"a_id": [
"e2q2s0d"
],
"text": [
"The bar is made of a thermochromic strip of paper/film (paper that changes colour based on temperature) layered on top of a strip of some conductor. When you press down on the two ends, the strip makes contact with the battery terminals and allows electricity to flow through it. This causes the strip to heat up and change the colour of the paper/film. The width of the strip is also not constant, so different parts of the strip requires different currents to heat up enough to cause the colour change. The \"0%\" end of the strip requires less current, the \"100%\" end of the strip requires more current. That corresponds to a discharged and fully charged battery."
],
"score": [
9
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"text_urls": [
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|
90g7vf | Why do Production companies sometimes cut out important bits in movies to save time? | Technology | explainlikeimfive | {
"a_id": [
"e2q6166",
"e2q5sg0"
],
"text": [
"If you mean a theatrical release, a movie needs to be a length that most audiences will want to see. Putting aside epics like Lord of the Rings or Interstellar, most movies are between 90 and 120 minutes including the end credits. Most movies shoot more content than is needed, which is how sometimes you get a special edition or director's cut, or cut scenes on the DVD or youtube. It is simply a matter of producing a final edit that tells the story as concisely as possible. On television, sometimes movies are cut for time. 1 hour of American television, with commercials, is about 40 minutes of program, 20 minutes of commercials. So if a 2 hour movie is shown on TV, it either needs to be cut down to 80 minutes, they need to put the movie into a longer time slot or run fewer commercials. In a few cases it has been proven that programming has been sped up. Someone discovered that Seinfeld reruns were being sped up in order to fit more commercials in a 30 minute time slot.",
"Because overall they aren't that important to the story telling. While die hard fans might think certain details are important, when looking at the overall movie the detail/scene may be unnecessary and interrupt the flow of the plot line. Ultimately you have to appease a wider audience than just the \"original\" fan base. Also yeah, wouldn't use Justice League as an example considering the film's rating was...questionable."
],
"score": [
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|
90g8gu | How does reverse image search work? | Does it literally scan through all the images on the web, looking for an exact match? Come to think of it, how does any search engine work? Is the whole internet downloaded onto a massive hard drive, and then searched with a powerful computer? If this is not the case, how is a single search done so quickly? Also, is there a unique challenge to reverse image searches because you probably have to compare each pixel in the image, instead of just matching some words? | Technology | explainlikeimfive | {
"a_id": [
"e2q41bi",
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"text": [
"Oh this is a fun one! Can’t wait to see what people will say. I just tought it was interesting to note that there are two very distinct approaches to current image searching technology. There is the google way : URL_0 That is aimed at recognizing what is actually in the picture, like a car, or a tree, and then finding a picture with the same element as your submission, let’s say a blue car, a red car, three trees on a purple background. Then there is the Tineye way : URL_1 A technology that identifies exact shapes, and uses face recognition, to identify pictures, in part or as a whole, and then creates a hash of each part of the picture. So for example, you could put a picture on your tv screen in a hotel lobby, and take a picture of the whole lobby. It will recognize the lobby from pictures of the other tourists, but it will also identify what’s on tv!",
"It's been a long time since I took computer graphics, but the basic idea is to create a fingerprint of an image, one that's small enough that you can quickly compare two images and large enough that most images will be different. Like you might turn the image to grayscale, and then turn those grays into just black and white, and then scale it down to 16×16 pixels. This is the image's fingerprint. It's 256 pixels, and in theory, you can distinguish nearly as many pictures as there are atoms in the universe. In my informal tests just now, this is surprisingly good at distinguishing similar pictures, which might not be what you want. I took two photos of a person's face about a minute apart, in the same lighting and position. [Here's the fingerprint of the first]( URL_2 ) and [here's the fingerprint of the second]( URL_1 ). (The white spots are because the person was wearing cat-ear headphones.) This is a very good result for \"I want to find pages with this image (even if it's scaled or in a different format)\" and bad for \"I want to find images like this one (even if they're a bit different)\". There are other ways of making a fingerprint. You might use hue (which will give you trouble finding the same image but in grayscale, or with a color filter) or brightness (which will give you trouble with other filters). You might [find edges]( URL_0 ) and base your fingerprint on that.",
"> Is the whole internet downloaded onto a massive hard drive Not the whole internet, just the pages in the search engine's index. If you put a website up and it's not linked to from anywhere, the search engine has no way of knowing it exists, so it won't be listed."
],
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"https://en.m.wikipedia.org/wiki/Google_Images",
"https://tineye.com/technology"
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"http://ikeran.org/lowfi-bw-face-2.png",
"http://ikeran.org/lowfi-bw-face-1.png"
],
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} | [
"url"
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"url"
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90gmb9 | How do counties "Hack an election"? | Technology | explainlikeimfive | {
"a_id": [
"e2q7ikv"
],
"text": [
"Countries attempt to “hack”, or influence, elections in other countries by taking actions that are likely to sway undecided voters one way or another. For example, in the 1960 US presidential election, the USSR had captured Gary Powers, an American pilot, after his U-2 spy plane was shot down. The Russians believed that releasing Powers before the election would help Nixon win, and releasing him after the election would help Kennedy win. Since they thought Kennedy would be easier to manipulate, they refused to release Powers until after the election. In 2016, it appears that Russian Intelligence agents hacked into the Democratic National Committee’s email servers, looking for information that would be damaging to Clinton, which was then released via social media channels and directed at voters who would be more likely to switch their support from Clinton to Trump. Putin has since admitted that he preferred Donald Trump as President, because it gave a greater possibility of economic sanctions against Russia being lifted."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
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|
90gyk6 | How can people say SSD is far worse than HDD because they fail more with constant writes and smartphones use the same technology and I never heard of a smartphone disk failing? | Technology | explainlikeimfive | {
"a_id": [
"e2q9yar",
"e2qad1d"
],
"text": [
"The cells do fail with usage. People who buy new phones every 2-3 years don't see enough usage to see it fail. Hold onto your phone for longer and you'll see it fail.",
"Early SSDs failed a lot quicker than modern ones Modern flash is a bit more robust, we've implemented software to help preserve it like better wear leveling in the flash controllers and TRIM in the operating system, and most drives are over provisioned with more flash than they claim so they have spare blocks to bring into rotation The end result is that you can write 1-1.5 PB to a 1 TB drive before it starts having issues. Most people won't encounter this, but if you're using your SSD as a scratch disk for your professional video editing work then you may hit these limits and burn through the flash on the drive HDDs have no effective limit on writes or reads since no damage is inflicted in either case"
],
"score": [
3,
3
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"text_urls": [
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} | [
"url"
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|
90h9t1 | Why do emergency broadcasts over the radio have such horrible sound quality? | An example would be a tornado warning over the radio. Most of the time when I hear them, they are so muffled and have so much static, that it's hard to make out what they are saying. Yet, when the station switches back to whatever music it was playing, the sound quality goes back to normal. It seems like it would be important to have decent sound quality when relaying information about the storm. | Technology | explainlikeimfive | {
"a_id": [
"e2qcodn",
"e2qc7r8"
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"text": [
"The emergency broadcast system was originally built during the cold war. Today we use it largely for storm warnings, but it also has the capacity to operate during major natural disasters and national security events. Basically, the equipment is supposed to withstand a nuclear bombing and deliver instructions to the survivors. So fancy power hungry high-fidelity radio equipment isn't important. Rugged, low power wartime radios that can run from a bunker are. It sounds like a cold war era doomsday radio message because it is.",
"They are trying to reach a bigger area on more frequencies. And they don't care about sound quality, as long as the message gets through. So they dont spend much time/money on really nice recordings, on tuning their equipment to a specific frequency, or any of the other tricks the radiob stations use to get clean sound. Just blast it out and make it good enough."
],
"score": [
14,
6
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"text_urls": [
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} | [
"url"
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90i01o | How do calculators work out complex mathematics essentially instantaneously? | It's always baffled me how even a "simple" hand held calculator can do so much. How exactly do they process the information and give you an answer so quickly? | Technology | explainlikeimfive | {
"a_id": [
"e2qip4z",
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"e2r33r9",
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"text": [
"All modern digital computers can only perform simple manipulations on binary numbers. However, because those simple operations are done in the hardware, they are blazingly fast, micro- or nano-seconds. So if you want to do more complex mathematical operations, you have to write programs to do it by running lots of simple operations, and that's what's going on inside a calculator or a supercomputer. But because modern digital chips are very, very fast, those programs take only a very short time to run, maybe a millisecond or less. Humans can essentially not differentiate time scales like that, we don't begin to notice a delay until the time gets up into the tens or hundreds of milliseconds. So something that happens in 2-3 milliseconds seems instantaneous to us.",
"To add onto the fact that basic operations are fast, more complex functions (such as trig) are often broken down into these fast basic functions by the means of Taylor series.",
"While they're much slower & capable than desktop PCs, they're still tiny computers. Even a basic calculator is capable of performing thousands of operations per second. Low end graphing/scientific calculators can do *millions*. Since they're dedicated, single-purpose machines, they're not wasting any of those CPU cycles drawing graphics, playing music, handling networks or sending everything you say to the government.",
"Look up a Minecraft red stone calculator. It’s a good visual of how it can work. Red stone has two states (on and off), and it can be used just like ones and zeros. It takes a little more time in Minecraft because there is a delay in the red stone, but it’s fascinating nonetheless. People are awesome",
"They’re like a bunch of little electronic “junctions” or “switches” that route signals down “pathways” to arrive at an answer based on your inputs. Making this translate to, say, artificial intelligence is no easy task. But computers excel at simple math where there’s a known process for figuring the answer out. These switches can do their thing *millions* of times per second so anything you could write out by hand on paper, they can do *millions* of times faster. Powerful desktop computers can do things *billions* of times per second! Yet, you can still see desktop computers slow down if there are multiple things going on at once or the task is not simple (attempts at voice recognition and other “AI” are still not that streamlined)."
],
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90ii96 | How do home pregnancy tests work? | Technology | explainlikeimfive | {
"a_id": [
"e2qmht3",
"e2qygo3"
],
"text": [
"There is a chemical in the stick that turns colors when a certain hormone is detected in your pee that you produce while pregnant. One line detects moisture and the other detects the Hormone",
"Home pregnancy tests are designed to tell if your urine contains a hormone called human chorionic gonadotropin (hCG) which is made when there is a fertilized egg in the woman's uterus. If you're pregnant, levels of hCG continue to rise rapidly, doubling every 2 to 3 days. If the stick detects the the hormone it'll show two lines, indicating that you're pregnant. If you only see one line, you can assume that you're not pregnant. The first is the control line while the second shows your test results. A test result line without the control line makes the test invalid."
],
"score": [
14,
7
],
"text_urls": [
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]
} | [
"url"
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