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j7pics | why switching off computers directly is bad for computers and why should we first shut down it? | Technology | explainlikeimfive | {
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"Operating systems often run backgroud services that let you do the things you can do. These services can have system files open while running to operate, and can occassionally write data onto the hard disk. Removing the power from the system while data is being written (and not completed) causes the data to become corrupt, and can break the service using it. Majority of the time you will not run onto any issues, however encountering it once can take down a system completely, requiring the operating system to be reinstalled. Shutting down causes all of these services to finish and stop before the power is turned off to prevemt that corruption. Similar to how ejecting a USB drive ensures your files are properly closed and not in use when being removed.",
"I think it's mainly for the hard drive\\operating system. Especially with spinning platter drives (HDD) sudden power loss could cause physical damage. Now that's not an issue with most computers having SSDs (solid state, no moving parts) but the issue is data loss\\corruption. If a file is being moved from one spot to another on the drive, or written or saved etc, it could potentially be lost or damaged. Modern operating systems try to compensate for this possibility with caching, and other tricks, so that the only copy of important files are never at a single point of failure, but it's still possible.",
"When a program wants to write data to disk, instead of writing the data to disk immediately, the OS often keeps it in memory for a while. It really enhances the performance and user perception of a program if it doesn't freeze every time it wants to save something permanently. If you cut the power, the OS doesn't have a chance to write the data to disk. Data can be lost or corrupted. Sometimes this doesn't happen, and sometimes it doesn't have noticeable consequences. But it's possible that it can have bad consequences (for example the computer might refuse to start if some important part of the OS is damaged, or you might lose an important file you spent a lot of time creating and really need for school or work).",
"If I’m understanding this correctly, it’s like someone getting knocked out versus someone going to sleep."
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j7stkz | Why do old(maybe some new) phones suddenly shut down or turn on when dropped? | Technology | explainlikeimfive | {
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"Older phones had batteries that were meant to be easily swapped out so they just had contact points that were spring loaded just like the batteries in a remote control. If you drop it hard enough in the right way the battery loses contact with the rest of the phone long enough for the phone to shut down. Phones now mostly have batteries that are semi permanently attached by wires and wiring clips that attach the battery to the rest of the phone securely."
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j7uy9i | Why cell phones batteries capacity is represented in mAh, while electric car batteries capacity is in kWh? | When you look up specs of a cell phone battery, capacity is represented in Ah (Amp hours), while car battery packs are in Wh (Watt hours), with their magnitude prefixes respectively. I know their capacity differs greatly, but at a glance of an eye I don't have any idea how they compare. Why the different standard? | Technology | explainlikeimfive | {
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"Amp hours have been the traditional measure of batteries for a long time because they represent the amount of charge stored in a fixed voltage battery. Typically you know the voltage of the battery so you can easily convert to the amount of energy stored. OTOH car batteries work at different voltages depending on the car. What you care about is the total amount of energy available, and this is what is being expressed by watt hours.",
"If you want to know how much energy a battery contains, you use the following formula: Energy (Wh) = Voltage (V) x Capacity (Ah) If all the batteries or devices you're comparing use the same voltage anyway, you can just compare the capacity in Ah. Cell phones all use single-cell li-ion batteries with a nominal voltage of 3.6-3.8V. Electric car batteries can vary widely in terms of voltage (350V for a Nissan Leaf, 800V for a Porsche Taycan), so a 100 Ah battery may actually contain more energy than a 200 Ah battery if the voltage is more than twice as high."
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j7vxe6 | How do organisations who put satellites into Earth's orbit make sure that they're not going to be in the path of another orbiting satellite? | Technology | explainlikeimfive | {
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"For most things, it's a free for all. Space is big. EXCEPT for geostationary orbit, which is tightly regulated. Geostationary orbit is a very narrow, very specific orbital path. It's the path that makes satellites alway stay over a particular spot on earth. That one is regulated by the International Telecommunication Union, an organization within the UN, which resolves disputes about who get what Geostat orbit slot. If enough countries start launching so space around earth isn't big enough, the ITU would probably start regulating that like they do geostat orbits, or maybe the Committee on the Peaceful Uses of Outer Space (another UN agency) But that hasn't happened yet, so it's all speculation.",
"They don't. Space is big^citation ^needed Really big. Hitting something on purpose is hard, so chances are it'll never happen - for a given satellite - by accident. There *are* government agencies that track everything above a certain size in orbit around Earth and let's you know if your satellite is about to pass within a hundred km or so of any other satellite within your next few dozen orbits, just in case you'd like to steer clear, but the only satellite that has the fuel to do so every time is the ISS - most satellites just have to hope for the best. Edit to add source: as a student I was part of developing and launching a satellite. A year later it had a near miss which we did absolutely nothing to avoid either before the launch or before it happened (since the satellite had no propulsion)."
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j7wruy | What does Xilinx do and why are they worth 30 billion USD? | Technology | explainlikeimfive | {
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"They produce FPGAs. Field Programmable Gate Arrays are very basic but efficient digital circuits that are needed for many industrial applications or in vehicles. It's basically a bunch of blanket digital circuits, that fulfill a specific task based on how you connect the parts internally by writing a program into it's memory. They are the world Leader in that because the founder of that company invented FPGAs and also a business model where they don't produce the circuits themselves (Fabless) but only design them and order the production from someone else.",
"In case anyone is wondering why this question is being asked, there's a rumor that AMD is acquiring Xilinx. Hence why Xilinx stock is up ~17% right now (US pre-market).",
"Most complex electronic devices use either a general purpose CPU that can be programmed to do anything, but not very fast, or an ASIC (application-specific integrated circuit) that can only do one very specific job, but that is much, much faster. The problem with ASICs is that it's very expensive to design one and set up a factory to produce it, so they only make sense for products that sell millions of units. Xilinx makes FPGAs (field-programmable gate arrays) and FPGAs are somewhere in between CPUs and ASICs. They have similar performance to an ASIC, but they can be programmed to do different jobs. However, the unit cost of an FPGA is relatively high. You often find FPGAs in high-performance lab equipment like oscilloscopes for example. A general purpose CPU is too slow to process a billion samples per second, and the company isn't going to sell 10 million units of a $20,000 scope, so they would use an FPGA instead.",
"Let me take a stab at a simpler phrasing on FPGA's, the product that Xilinx makes. When programmers write code that describes what a computer should do, most of the time a processor runs it. That's what \"software\" is - the processor reads the code and decides what to do. But sometimes you can make a chip that is custom-made to do what code would do - that's \"hardware\", and hardware is faster than software, because it doesn't have to decide what to do. Let's use an example: Sorting beads. Let's say you have a bowl of beads, some are big cubes, some are big spheres, and some are small cubes. Let's say you want to take out all the small beads and take them out of the bowl. Software works by looking at each bead and saying \"is this one big or small?\" and then picking up the small ones and taking them out. Now let's say you drilled a hole in the bottom of the bowl, just big enough for the small beads to fall through, so they automatically pour out. That's what hardware does - it makes it so the \"thinking\" part of the program happens automatically. The downside to this is that hardware is inflexible. Using our bead example, let's say instead of taking out small beads we wanted to take out just the square beads, no matter the size. The \"software\" way still works - we can take out a bead and think about its shape, and take out the square ones. But the \"hardware\" way doesn't work anymore. Now we need to throw out the whole bowl and make a different one, one with a square hole that the round beads won't fit through. FPGAs, which Xilinx makes, are chips (hardware) that you can program like software, but they are as fast as regular hardware. In our bead sorting example, this would be like a bowl where you can make and unmake whatever holes you want in it!"
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j7xz63 | What is peekers advantage and how does it work? | Why can't they fix it? | Technology | explainlikeimfive | {
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"Basically because of lag (milliseconds, but still) if you quickly peak out of cover, you can see the enemy for a fraction before they see you, giving you an extra moment to aim and shoot. They can’t fix it because it’s caused by differences in upload and download speeds",
"Multiplayer game servers typically don't update players about everything that often, maybe 30 times a second, and it takes some time. So if someone stands around the corner and you peek for a fraction of a second you see them, because they were already there. But since you were not visible to them initially and then moved back they might not even get update and see your character on the screen at all, even if they were looking your way. So the one peeking around the corner gets the advantage of seeing the opponent first while remaining unseen."
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j7zx7l | While some smartphone touch screens can be used the same way with or without gloves, many smartphones don't even react to fingers touching the screen, what is the difference? | Technology | explainlikeimfive | {
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"There are two types of screen usually used (nowadays almost always only one on Smartphones). Capacitive and Resistive. Capacitive screens use the body's electric condutivity to know that a human touched the screen, and usually, using a glove creates a barrier, which is why there are some gloves with special materials that let that eletric charge flow through it. Resistive screens are 2 layers, one on top of the other, and when you press somewhere with your finger, they touch, so the phone knows where you pressed. Since this screen is based on pressure, anything can be used, not necessarily your body. Nowadays most phones use capacitive screens.",
"All smartphones use the same type of sensor these days, the capacitive type. The sensitivity of a particular screen is up to the manufacturer. Some can even detect your finger before it makes contact."
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j80vq7 | Why do our upload speeds only like 10% of our download speed? | Technology | explainlikeimfive | {
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"Sure, there are some physical tradeoffs required to allocate more infrastructure to upload speeds. But this is mostly by choice. In short, your internet service provider doesn’t want you to use your connection for activities that typically require upload speed, because these are often classified as “business” activities... if you need to use these functions, they would prefer to sell you a business-grade internet plan, and charge a whole lot more money for it. Examples such as hosting a website, streaming content stored in your house to devices elsewhere, uploading large numbers of high-quality videos to sites like YouTube, etc, are not activities ISPs consider “normal consumer” behavior. While you might not be using your YouTube channel, or streamed music library, for profit, they consider these activities to be similar to somebody using their internet connection to operate a business. And if you’re doing those things and needing better upload speed, they want you to pay extra for the fancy internet plan that has good upload speeds. In fact certain activities such as hosting a website from a residential internet connection are usually banned by the contract with the ISP and would require you to pay a fee or buy a more expensive plan... however, instead of tracking down every instance of somebody breaking that rule, they simply slow down non-business plans in a way that makes this activity slow or impossible, but normal users who mostly download won’t notice any impact, so this practice won’t decrease their customer satisfaction or profit in most cases",
"Because most people download more often than they upload, so ISPs optimize for that, but different people have different needs and business customers get the option for the same speed on both upload and download",
"* The physical connection between you and your ISP has fixed amount of bandwidth. * That bandwidth can be split between downloading and uploading pretty much anyway the ISP wants. * The vast majority of home internet users are downloading way more data than they are uploading. * So it makes sense to use the majority of the bandwidth for downloading. * Otherwise a bunch of bandwidth set aside for uploading would just sit there unused.",
"Because most people don't need to upload as much as they need to download. There is only a fixed amount of information that can be sent through the cables to your house, and that includes both directions of traffic. So a decision needs to be made in allocation how much of that is for traffic going away from your house (upload) and traffic coming into your house (download). Almost everything you do is downloading. Streaming, browsing, e-mails, it's almost all download. The upload component of that is simply your computer sending out requests for information (which are relatively very small). The replies to those requests contain the actual information which is the bulk of what is being sent."
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j84gzm | Why are there so many buttons and controls on a spacecraft (for example Apollo spacecrafts) and what do they do? | Technology | explainlikeimfive | {
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"A spacecraft need to contain a lot of different systems to work, and a lot of them is redundant so that even if one system does not work another can be used. This is because there is no way to safely eject or otherwise quickly land in a spacecraft. Any problem needs to be solved then and there. So each of those systems have a separate panel with buttons, switches and dials to allow the astronauts to operate them. The manuals to most spacecrafts is actually made available to the public so you can look them up and read through it to see what each one of those buttons does. Today cockpit design have changed a lot. Even the Space Shuttle got a significant update to its cockpit removing most of the switches and dials. Instead of having lots of different panels, one for each system, you now have a central panel with a monitor and keyboard where you can access each system through the menu. But there is still some controls that is required in order to solve issues with this central system. For example the fuse panel and the electrical management panel.",
"The vast majority of the buttons should never need to be touched, but they're there because if you need them you'll probably die without them. Let's start with a simpler control panel like the one from [the Crew Dragon]( URL_0 ). The whole left and right most panels of buttons are \"Oh Shit\" buttons that are there if something is going really really wrong so the crew can override any automated systems. It gives them ways to deal with fire, and to return to Earth if needed. The third from the left is a redundant set of controls for reentry and parachutes just in case something is going wrong. SpaceX moved a lot of the subsystem controls into touch screen menus, but critical ones are still physical buttons. Apollo era stuff had buttons for flight computers because they would have to calculate their orbit and reentry burn so they would land off the coast of Florida. The computers were big and not so automated so the screens with a lot of buttons next to them are generally the flight and reentry computers that they have to feed their numbers into, and then they have to set the knobs and dials in the spacecraft to give them the right orientation and thrust to get where they want to be. The modern systems have adequate sensors and computing power to figure it out themselves and be checked by ground control. But most of them are because they had buttons/switches for anything that could be operated independently. Have 3 oxygen tanks that can each be stirred? You get 4 buttons, a stir all, stir 1, 2, and 3. Why would you want to stir them one at a time? Well you probably wouldn't, unless the inability to do so results in loss of crew. These weren't meant to be user friendly. The guys going in them were highly experienced Air Force test pilots. The more control you can give to them and the engineering team on the ground, the more likely they were to be able to find a creative solution to recover from an unexpected failure mode. The ability to power each system on/off independently saved Apollo 13"
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j8egvv | Why do we have to wait 10 seconds when you restart your WIFI router? | Technology | explainlikeimfive | {
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"In the circuit boards there are capacitors. They function like short term rechargeable batteries. To make sure all systems are truly off you have to wait for them to deplete.",
"Also, because your session (with the device in the internet providers) is kept open by time. So if you quickly turn off and on again, it's possible it hasn't realised you've gone offline. By leaving it off for 10 seconds or more, it usually gives it enough time to realise nothings communicating and to kill the session. Realistically you should turn it off for much longer, but it usually does the trick Source: this was my job to fix these for 2+ years",
"Imagine a sink. When you turn the tap on it starts to fill up. The plug is set to open for 1 second every 5 seconds. It's the water coming from the plug hole that powers the device. Not the power coming from the tap. So you can turn the tap off, and there still be water in the sink, so when the plug opens water comes out and powers the device. You have to wait sometime after closing the tap for all the water in the sink to be used.",
"I did tech support for an internet provider for seven years. We told people to leave the router unplugged for ten seconds for the same reason we told the to ‘swap ends’ on the network cable - because if we didn’t, people would lie and just say they did it.",
"You don't have to wait 10 seconds to restart your router. This is an urban legend. Back in the day (20+ years ago) some routers would not immediately respond to the reset button being pressed. This was a software/firmware issue, not a result of capacitors failing to self discharge.",
"I work for a national ISP in the US. Your box won't completely forget the connection it had for those first few seconds it's off, meaning it might not have to start from scratch when you start it back up. If it doesn't start from scratch, it might not get rid of whatever is causing your problem. That's the official Eli5 that I give to the boomers when they complain about having to wait 15 seconds. The other comments mentioning capacitors and the like are kinda Eli10 imo",
"A WiFi router is actually a small computer. It has a CPU, RAM, and other similar components inside of it. This is because a Router is not merely a transmitter of a signal, instead it actively manages every single device that is connected to it via WiFi, every request sent to it, and it manages the data flow that happens over the WiFi connection with each device. By turning off your router and giving it a couple of seconds, you essentially give it the chance to properly clear out any memory stores from it's previous active sessions - essentially allowing it to start out fresh and ready for new action once you turn it back on. 10 seconds is suggested simply as a good practice, but in reality just a couple of seconds is enough to achieve this in most cases."
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j8f0n9 | What is DLSS and how does it benefit gamers? | Technology | explainlikeimfive | {
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"It's an AI assisted image upscaling technology developed by nvidia. To give you an example, you're given a low quality image which you want to make it better. If you're a good artist then you may use your imagination to make the image look clearer, hence making it look better. Or if you're good at computers you could make your machine to learn imagery imagination by teaching it tons of images by which your machine can learn. Once it learned how to 'imagine', you let it do the job. This is basically what Deep Learning Super Sampling (DLSS) does. For gaming, you could make your GPU to quickly render shitty graphics and let the tensor cores to upscale the shitty images by DLSS."
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j8f8h5 | How polygraph test detects a person lying? Is there any way to cheat the test? | No, I'm not guilty of anything. Just curious. | Technology | explainlikeimfive | {
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"Polygraph doesn’t detect lies. They take find a baseline by asking you normal questions to see how you react when they know you’re telling the truth (what’s your name?). Once they have a baseline, they ask harder and more dubious questions. They compare this to the baseline And determine whether you are nervous or not. Polygraph proves nothing. It’s pseudoscience.",
"A polygraph measures a bunch of things. Breathing, heart rate, perspiration, etc. They take baseline measurements by asking questions that don't stress you. Humans really dislike lying and display a lot of stress when they are being deceitful. But there are tons of other reasons to be stressed that will look the same to a polygraph. You can train yourself out of the physiological effect of lying, most people report that thinking about something innocuous while answering works. Polygraphs are not very reliabke",
"Absolutely! Im sure there are likely well known cases of people beating them... that's probably why polygraph tests are considered controversial because they more of less measure how nervous or anxious someone is. Theres no way to know 100% that someone is guilty of something without actual proof. You would probably be nervous if you were being questioned of murder knowing the wrong answer will cost you your freedom, even if you are innocent. Someone can commit a GRUESOME murder and be completely calm and relaxed telling you every single detail, and lie to you saying they have no idea what you're talking about.",
"Polygraph operators compare reactions to relevant questions (for example, \"Did you shoot John?\") with reactions to so-called \"control\" or comparison questions to which everyone, whether innocent or guilty, is expected to lie (for example, \"Did you ever intentionally hurt someone?\"). If reactions to \"control\" questions are stronger than reactions to relevant questions, then the subject is deemed to have been truthful in answering the relevant questions. Conversely, if reactions to relevant questions are stronger than reactions to \"control\" questions, then the subject is deemed to be lying to the relevant questions. This simplistic methodology has no grounding in the scientific method, and it is vulnerable to simple, effective countermeasures that polygraph operators cannot detect. One can beat the polygraph by covertly augmenting reactions to the \"control\" questions, for example, by doing mental arithmetic, thinking frightening thoughts, or covertly biting the side of one's tongue. For more on polygraph methodology and how to pass or beat a polygraph \"test,\" see the free book [*The Lie Behind the Lie Detector*]( URL_0 ) (available in PDF, EPUB, and Kindle formats)."
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j8giem | Polymorphism in C# or generally in programming. | Why do we use it, what's the purpose of it? | Technology | explainlikeimfive | {
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"As someone who is many years in programming, i honestly advice OP to check any tutorial (youtube is also good) for this answer.There are plenty of them. It needs some background explanations, and pictures, and it is just extremely hard to do it in this post."
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j8ifvo | Why are 12-13 MP cameras on flagship smartphones better than the 48-64 MP cameras on mid range and budget smartphones? | Technology | explainlikeimfive | {
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"48 MP is only possible by making the sensors larger, meaning a larger phone, or by shrinking the pixels, which decreases their effectiveness. They are trying to overcome this, but it is still a work in progress. Its important to remember that a resolution is simply a measure of size, not quality. It has more potential detail, but is not guaranteed.",
"Because the number of dots you read is one tiny, tiny statistic about how a camera operates. Lens quality and design, quality of each of those pixel sensors, the sensor range and sensitivity to each of the colours, post-processing performed on the camera chip and on the device itself, distances between lens and sensor and can the lens adjust/move itself and how far?, image stabilisation, ... It's like saying \"My car has 47 exhausts, why isn't it faster than a Ferrari with only 1?\"",
"Every sensor is a compromise. More pixels increase resolution but often at the cost of quality, particularly in low light. Fewer, larger pixels improve quality but reduce resolution and your ability to crop an image. You choose the sensor that suits what you shoot."
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j8j0a4 | Why are newer TV's so slow to start up, slower to load a TV guide and slow to switch channels. | Technology | explainlikeimfive | {
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"I am going to go ahead and re-use my answer to this question from [eight years ago]( URL_0 ), because it is still true today. --- Here's the process an analog TV goes through when changing channels: * Tune to new frequency, display signal. It's instantaneous, there are no processing steps required, it can just pipe the signal it receives directly to the screen. Here's the process a digital cable box or TV goes through when changing channels: 1. **Tune** to new frequency 2. **Demux** bitstream and identify correct channel 3. **Decrypt** individual channel (on pay-TV systems) 4. **Unpack and Decode** channel video and audio streams 5. **Wait** for a keyframe in the video stream. 6. **Display** video signal. Each of those steps takes tenths of a second to complete. The wait for a keyframe, especially, can take 1 or 2 seconds. Let me explain each of these steps in more detail. **Step 1** is tuning to the frequency on which the desired channel is broadcast. This step is pretty much instantaneous. **Step 2** is *demultiplexing* or *demuxing* the signal. This is required because on the vast majority of digital TV systems, a single frequency will carry several individual video channels. These individual channels are smooshed (*muxed*) into a single stream of bits. Your TV/Cable box looks at this bitstream and figures out which bits belong to the channel you selected. It separates the correct bits into a different bitstream that carries just the channel you selected. This is called *demuxing*. **Step 3** is decryption. On Pay-TV services, most of the channel streams are encrypted to prevent people from watching them if they haven't paid. Your cable box or satellite receiver must consult its internal decryption key table to get the right decryption key, and use it to decrypt the stream. If the key is not available, the box must wait for it to be resent, which can take several seconds (but this is unlikely). **Step 4** is unpacking and decoding. This is another demux process, but instead of looking for the bits for a video channel, it is now separating the channel stream into video and audio streams. The video uses a codec like MPEG2 or MPEG4, while the audio uses a codec like PCM or AC-3. The box must identify these codecs and begin the proper decoding routines. **Step 5** is waiting for a keyframe. MPEG2 and MPEG4 are video compression schemes. The way they compress video is by transmitting a *keyframe* (which is a complete frame of video) and then only transmitting the *changes* from one frame to the next. The receiver gets the keyframe, then applies the specified changes to make up subsequent frames. But what if the receiver jumped into the stream in between keyframes (which is the most likely scenario)? All it has are a bunch of changes, but no original to make the changes on. So it has to wait for the *next* keyframe (which usually takes a second or two) and begin decoding from there. This is the biggest reason for the delay in changing channels on most digital TV systems. **Step 6**, finally, is displaying the decoded video and audio. All of those processing steps take a little bit of time, and the cumulative effect is that it takes a couple of seconds to begin showing a newly-selected channel. --- As for why the TV itself is generally slow, that's simply because the computing hardware (CPU, GPU, RAM) they use for the operating system is often the cheapest they can get.",
"The other answers are technically correct, but the main reason “why” is missing: *Money*. The manufacturer is putting in the bare minimum processing power they can get away with. It would be possible to increase processing power which would reduce various times that add up to the slow feeling, but powerful processors cost more money. Of course, a few wait times (namely for the keyframe) cannot be shortened.",
"I also bought a tv recently and it is so slow!! Ive always wondered why if the specs and tech is so new that it should be slower than older TVs i have owned in the past!!"
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j8js0d | why do Geiger counters make that strange noise and why is it so different to other sensors that just beep? | Technology | explainlikeimfive | {
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"Because geiger counters are *old school*. Geiger counters have a tube of inert gas. When an ionising particle passes through this tube there's a chance it will ionise an atom. This effect is amplified and turned into a little surge of current. That current can move a pointer on a dial or be fed into a speaker, where it sounds like a click. Now of course you *could* build something more complex that makes a speaker beep rather than click. But why complicate something that works?"
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j8k11w | Why do people say over after talking on a radio? | Technology | explainlikeimfive | {
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"text": [
"To inform that they are done speaking. If both people are talking at once nothing goes through so you wait till you hear \"over\" to respond"
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j8n8e1 | Why do motion pictures or videos feel smooth at 30fps but playing a videogame at 30fps will feel choppy? | Technology | explainlikeimfive | {
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"A camera's exposure, the time a camera's \"eye\" remains open to collect light, collects information from the scene over a period of time per frame. Let's say you have a video capturing someone kicking a ball. The ball is fast enough that doesn't remain still during one frame's exposure. This causes it to leave a streak in the image. Since the camera is continuously capturing frames, the beginning and end of the streaks line up on each frame. This motion blur makes the movement of the ball line up so it doesn't feel like the ball teleports from one position to another. Video games operate differently. They generate an environment or scene at one exact point in time. In a rendered video game frame, the ball is at a fixed position in the air. Each following frame has the ball move but it's still frozen in mid-air. Viewing the frames in sequence, you see a stationary ball jumping from one mid-air to another. There's no motion blur unless the video game adds it in. With low frames per second (fps), this may feel choppy. However, if you display the ball with enough fps, it will show the ball at all positions at its path, smoothing it out. Motion pictures and videos can sometimes have the same choppy feel if the exposure time is very short. If you're filming in bright sunlight, cameras have to reduce the time it's \"eye\" is open to prevent overexposing the scene. Since it doesn't collect all the scene in the time between frames, you can get this choppy feeling that you get from low FPS video games. This is most common in outdoor action scenes where there is a lot of environment light and many things are moving at once.",
"This is kinda an oversimplification. There's plenty of cases in movies where they look choppy, especially with things like panning shots in documentaries. 30 can also look smooth in a videogame provided that there's little movement. You probably think of 30 as choppy in games because you're used to free-cam movement. Cameras also average all movement over a frame, where digital rendering renders a single instance. This means that cameras have a natrual blur that masks a lot of the jumping, where digital renders don't. It's also possible to invert the two with per-object motion blur in games and decreasing exposure-time in cameras. The choppyness is a result of objects moving too quickly for the framerate, which is why 30 can look fine in some games, but 120+ is ideal for First-person cameras in games. Input delay is also a factor when you're playing. Lower framerates have more delay."
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j8nsg2 | What does that guy that trademarked PS5 before Sony did get out of it? | Technology | explainlikeimfive | {
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"What you're talking about happened in India. Third world countries, such as India, frequently have laws or legal systems that are heavily slanted against foreigners. India's trademark system is one such law/legal system - there is no requirement that you be using a trademark to register it and its almost impossible for a foreigner to challenge a trademark registration through the courts. The entire point of India's trademark system is to allow local citizens to preemptively register trademarks that are being used elsewhere in the world. This allows Indian citizens to extract a sort of trademark tax on foreigners who want to use their marks in India, and who failed to register their mark as early as possible in India. India's copyright and patent systems also work pretty similarly - if a foreigner doesn't file their copyright/patent simultaneously in their home jurisdiction and India, then an Indian citizen can just copy it, file for protection in India, and become the legal owner of the copyright/patent in India. So what does the guy who registered it think he's going to get? Money. Its basically impossible for Sony to reclaim the mark in India, so if they want to sell something called the \"PS5\" there then they'll either have to spend the next 20 years fighting him in what will probably be an unsuccessful court battle or just buy the mark off him.",
"Probably just hoping for Sony to buy it off of him. Either way, all it’s doing is preventing the launch in his country.",
"His hope is that instead of going through the possible expenses of contesting the trademark (which they may still lose) Sony will just pay him off."
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j8o95c | Whenever a road is built or worked on, a worker is looking through one of those telescopes on a tripod. I assume they are surveying or measuring straightness.please? | Technology | explainlikeimfive | {
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"They’re surveying. The “telescope on a tripod” is probably a level. A level is used to measure elevation. You look through it at a rod, and the height your eyes hit the rod at tells you how much higher or lower the ground at the rod is, compared to where you are standing. Levels are pretty old school, but they still see a lot of use because they’re cheap and easy to use. Modern surveyors use a device called a total station, which looks like a big camera on a tripod. It’s operated remotely by a surveyor with a reflector on a stick. The device rotates to line up with the reflector, and then sends out a signal. It can figure out the distance between itself and the reflector, as well as the elevation difference. And it automatically updates a database in a computer with that data.",
"They are called total stations. They measure angles and distances from point within line of sight of the total station. Super simple use example. You have a known point and then you use to total station to measure other points. When building roads you need to know where and how high the road is supposed to be based on blueprints at each point.",
"They are measuring distances in three dimensions, up and down, near and far, and side to side. Roads have to conform to certain standards, which are determined by engineers. The standards determine things like how hard it is for a vehicle to go uphill (grade) and how the road sheds water (to make it safe for driving.) The measurements that the surveyors make help the road builders to keep their construction in conformance with the standards."
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j8q39u | How do vacuum tubes work? Particularly in guitar amps? | How do tubes work? How is a preamp tube different from a power tube? And what components/elements of preamp/power tubes affect the tone of the amp? (example: what makes EL34’s sound different than 6L6’s, or makes 12ax7’s sound different than ef86’s) | Technology | explainlikeimfive | {
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"In a vacuum tube there's a beam of electrons going from one metal piece to another metal piece. That's why it has to be a vacuum - otherwise the electrons would bump into the air. There's a metal mesh or grid in the middle of the beam. When the grid is electrically charged, it pushes electrons away and they don't want to go near the grid (not even through the holes) which makes the beam weaker. So you can use it to amplify a signal, e.g. put the beam in between the power supply and the speakers, and connect the grid to the guitar pickup, and now the small amount of electricity from the guitar pickup is controlling the large amount of electricity going to the speakers (it's actually more complicated than that). So the small variation in electricity, that represents the sound, turns into a big variation in electricity. i.e. a small signal turns into a big signal. Your amplifier has two stages - the preamp turns the tiny weak signal from the guitar pickup into a medium strength signal, and then the power amplifier turns the medium strength signal into a really strong signal for the speaker. A preamp stage is designed for accuracy because it deals with tiny weak signals; a power amplifier stage is designed for maximum power. If you have a bigger sound system with mixing consoles and stuff, the preamps go at the earliest possible points in the system (i.e. right after the guitars and microphones) and the power amplifiers go at the last possible point (i.e. right before the speakers). Everything in-between uses the medium strength signals. I'm not an expert on sound, but different tubes may sound different because of different design - basically the same amount of grid charge repels the electron beam a different amount. Especially the \"non-linearities\" will change the tone of the sound. Adding a bit of charge when the beam is strong probably weakens it more than it does when the beam is really weak, but how much less? You can plot the beam strength vs grid charge on a graph, and different tubes will have different graphs - they'll be about the same overall shape, but the details can change. Even different tubes of the same type can be different, but the difference is less than with different tube types."
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j8rn10 | How can passwords be cracked, but not Prepaid Gift Cards? | Technology | explainlikeimfive | {
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"With most gift cards they have to be activated to be used. So while in theory the alpha numerical number on the card could be cracked as long as the card is not activated the card can it be used.",
"The alphanumeric string that is on an Amazon giftcard maps to an entry in Amazon's database. If the string is 16 characters long and can be any value A-Z/0-9, then that is 36\\^16 possible values. That is almost **8 septillion** possible values. Presumably there is some algorithm that is used to generate valid numbers, and they are not completely random. So you would have to guess a value that a) is a valid combination, b) has not already been claimed, c) is not expired, d) has already been issued. If you guess one per millisecond it would still take billions of years to try them all. And it's a safe bet that Amazon will lock your account after a couple of bad guesses."
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j8sdtx | . why do scientists always search for radio sygnals in space? Why do they think aliens use that to communicate? | Technology | explainlikeimfive | {
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"Ultimately, there only are four ways that matter and energy can influence each other. We call these the *fundamental forces*. **1. The Strong Force** This is, as the name implies, the strongest of the four forces. It binds quarks together to form protons & neutrons, and in turn binds those together to form atomic nuclei. It's responsible for the existence of the very elements. However, its range is ludicrously short. It can only reach across the width of an atomic nucleus before it vanishes, and so cannot be used for communication across any distance. **2. The Weak Force** This is the weaker of the two nuclear forces. It's responsible for nuclear decay. Its range is also ludicrously short, rendering it useless for communication. **3. Gravity** This is by far the weakest of all four forces, although it does have a long range. It's created by mass, but it's so weak that you need planet-sized clumps of mass to get a noticeable amount of gravity. Generating signals for communication is nigh-impossible; gravitational waves are so weak that we only managed to prove that they exist a few years ago, and it took the collision of two supermassive black holes to create a signal big enough to detect. **4. Electromagnetism** This is the other long-range force, and it's responsible for almost everything we experience in our everyday lives. It creates atoms and molecules, and dictates the behavior of solids, liquids, and gases. *Light itself* is a wave passing through the electromagnetic field, as are microwaves, x-rays, radio waves, and others. Electromagnetic waves are so easy to generate & so common that we have two organs embedded in our faces that are evolved to detect them. You can generate a radio signal simply by moving an electric charge back and forth rapidly, and detect it by watching the radio wave move an electric signal in a wire somewhere else. TL;DR: Radio is a type of light, one of the most basic components of our universe, and the only such component that's suited for long-distance communication.",
"It's pretty much the only thing we can actually search for. It's not as if we have any idea how to look for some kind of Startreklike subspace communications or similiar SciFi inventions",
"Radio waves are easy to detect, and an artificial sequence would be easy to identify, so it is a very practical search to undertake. We also have gravity detectors, which could potentially pick up organised signals if such things existed, but because we don't know how to produce such signals, it would be a lot harder to know if the signals picked up were artificial or not."
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j8tl41 | How does a bidet (cheap, handheld attachment kind) not cause poopy water to run down the legs? | If a person were sitting down on a full bidet, it makes perfect sense. However, the other way just baffles me. I just can't see how dirty water doesn't get sprayed/misted all over. | Technology | explainlikeimfive | {
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"You're sitting down, not standing up, so the poopy water is almost entirely in your ass. Then you wipe it dry, and it doesn't drip."
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j8udnx | Why haven't any public figures really been outed for their search/download history? | Technology | explainlikeimfive | {
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"There was an actual law passed when Robert Bork had his video rental history leaked by the press trying to subvert his nomination for the Supreme court in 1988. The push against him was so destructive and slanderous that \"Borked\" became a verb.",
"I guess it’s because nobody gives a shit. Also, it would be somewhat hard to prove without doubt that this is [insert public figure name]’s history.",
"Besides probably being illegal (and not profitable), you'd have to hack the companies that maintain the data (Google, Microsoft, major ISPs, etc), and that data would need to be attributable to a specific person. This data is likely very well protected, and it's probably not in a form that makes it immediately obvious or easy to determine whose is whose. There are various ways to obscure identities while still delivering targeted content to a specific person, by assigning unique IDs instead of names, and splitting this information across data stores, among other things.",
"Porn is the biggest industry on the internet. I'm not sure what \"outing\" someone influential would do. \"You like naked men/women? SCANDALOUS!\""
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j8v1oo | why are car headrests angled forward? | Every single car I have ever been in the headrests always are angled at such a way that you can never rest your head comfortably on it. Like my step father has a Lincoln Navigator XL nice big ol car but if you try to use the headrests it pretty much forces you to stare down. Is it for safety or something? | Technology | explainlikeimfive | {
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"To prevent your head from yanking backward in a rear-end collision (reward hyperflexion), the headrest pushes your head forward and down to keep it close to your spine.",
"The head rest isn't a head rest. Resting your head on it isn't really the idea. Ideally, the back of your head should be just touching it or a few centimeters/inches away from it. The industry term is head *restraint* which is more to the point. The head restraint is there to catch your head and prevent whiplash if you get hit from behind. The shape has to do with how it catches and cushions your head if it ever has to protect you. The foremost part of the angled headrest is the part that should line up with the back of your head. That way, it will guide your head forward instead of backward when you get hit.",
"It is safety. Your headrest is not really for resting your head. It's main function is to catch, slow down and then stop your head from moving when you get hit for behind. This is to prevent you from getting whiplashed."
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j8w1cz | Why is fuel/petroleum the liquid that makes cars run? What’s happening inside the car with this specific liquid that makes it go that can’t happen with other liquids? | Technology | explainlikeimfive | {
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"Are you asking why some liquids are combustible and other liquids, like water, do not burn in the presence of a spark? The liquid is aerosolized inside the cylinder, air (oxygen) is pulled in and a spark fires which causes the fuel air mixture to combust and push against the piston and the process repeats. There are certainly other liquids that are combustible but not every one has the same energy content. Ethanol, for example, burns but you cannot go as far with the same amount.",
"The piston pulls fuel and air into the cylinder, and when the piston moves up, it compresses the fuel/air mixture, then the spark plug lights causing the flammable mixture to explode, pushing the piston down and sucking the exhaust out of the exhaust valve. Diesel fuel runs different in diesel motors, but that’s a basic example of how a gas engine works",
"You can make cars work on other liquids (ethanol for instance). But it has to do with the amount of caloric energy in the liquids, the density of the liquids, etc. Petrol/gasoline isn't terribly dense (so it isn't heavier/more viscous), and has a very high caloric energy value (it burns better than say, water, which has no caloric energy). It also has a relatively low combustion temp (ie, how hot something needs to be to catch on fire, hence why you can light it on fire with a spark rather than needing an already lit flame to burn it). All of these combine to make it the BEST, but not the ONLY fuel for cars."
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j8yvu7 | Why is it on a lot of lamps that have a twist knob, you have to twist it two clicks to turn it on/off, instead of just one? | Technology | explainlikeimfive | {
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"What you're seeing is a lamp that's expecting a three-way bulb. With a three-way bulb, it would take one click to turn it on low, one to move to mid, one to move to high, and a fourth to turn it off. But since there's only one filament, and it's in the middle position of the bulb, it takes two clicks to move it to mid, and two to move it to off."
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j909zi | Why does every piece of software I install get stuck on "100%" complete? | Technology | explainlikeimfive | {
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"Depending on the SW it will do various things when it reaches 100%. This usually means that the SW has finished writing to the computer memory, but after doing this a lot of SW check and verify that the stuff was written correctly and that there were no errors etc. This can take some time depending on how fast your computer is, how big the SW is etc.",
"Making an accurate progress bar is actually *really really hard!* You have different kinds of tasks that run at different speeds and you have to account for different hardware. Say your 'install' happens in 2 stages: A and B. On one PC, task A takes 30% of the time and B 70%. But on another it's a 50/50 split. So what percentage should you give when B starts? How do you even *know* what the percentage of the total time A took before both tasks are complete? There's a certain amount of guesswork involved in all of this. What probably happens for the 100% is that the installer has tasks A, B, C and only measures A and B. So when A and B are finished, the installer thinks it's done (100%) even though it's still running task C."
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j9389a | Why do we not have central locking for our homes like we do for our cars? I'm forever fumbling with bags trying find keys. | Technology | explainlikeimfive | {
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"This does exist. You just don't have it. Go buy and install a smart lock, you can find one at Home Depot.",
"Because people can pick up the frequencies to your key fob easily with a radio and open your front door With a repeater... if you left your keys by the front door, they could easily pick up it’s frequency and copy it, play it back and open the door",
"I have one of these locks. I can use an app on my phone to unlock my door from literally anywhere I have data, and there's a touch pad for keyless entry as well",
"This exists, but it isn't secure. Convenience is nice, but some things should be \"dumb\". Anything wireless or connected to the internet can be hacked. Other stuff that should not be able to be controlled remotely: your car, your oven, and anything that can be dangerous or that has to be kept completely secure."
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j9870x | What is the purpose of a dual ethernet port on a motherboard? Why get one? | Technology | explainlikeimfive | {
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"Most of these answers have some truth to it but also some misconceptions. Most people have no use for it. Yes, you could have your internet connection running off one, and use the other for local network communication/local gameplay and the like, but in almost no cases will the bottleneck be the limitations of the network adapter, and you can just as easily accomplish local network communication through a switch or the existing ports on your router, without a specialized motherboard and additional configuration on the computer. I mean sure, something like a NAS (Network Attached Storage) server may get more benefit from two ethernet ports instead of one but very few home users are going to need that, and those that do are much better served by using more purpose-built hardware for such demanding applications. Where could it be useful? Special use cases such as if you're using a computer to build a router or other special purpose machine like a server that could benefit from one network adapter on a public-facing network (internet) and one on a private-facing network. Or if you're running a virtual machine off of that computer and you want the VM using one ethernet port.",
"Short answer: It's a gimmick that very few can take advantage of at all let alone need. I would not bother. Longer answer: The primary use here is to bond them if you have a router that supports it, so that you have 2x the network speed. This is only relevant if there is something on your local network that also has a connection that fast and is able to deliver content that fast. And even then you'd probably be better served with a 2.5gbit port or a 10gbit port, though again those really arent needed or able to be used by most people. An anscillary use is to use virtualization passthrough and have a dedicated network interface for a virtual machine, instead of just routing all traffic through the host machine like a normal person. This is like niche within a niche though.",
"If you are using at a server, you may want to have to completely separate network segments.",
"There's a technology called Link Aggregation. Essentially, use two connections to get greater speed than either one could individually give. In order to use it, both devices on both ends of the connection must support the same link aggregation protocol. In addition, it is typically useful for local network only. Very few places would have an internet connection capable of sustaining the kinds of speeds you would be using this technology for. For instance, I have my local Plex server on a link aggregated connection, because it regularly does a couple 4K Streams locally to different TV's in the house."
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j9bqsz | How do motor vehicles calculate the exact mileage they travel? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"We know that each revolution of the driveshaft corresponds to one revolution of the wheels, so every time the driveshaft goes around once it should mean the vehicle has moved forward by pi x the tires' outside diameter. (That's wrong if you're spinning your wheels on ice, but it's valid the other 99.9999999% of the time.) Mechanical odometers use a series of gears so that the far-right wheel turns at a tiny fraction of the driveshaft speed, and if you use just the right gear ratio for that, then the odometer will read correctly. I think newer cars have an electronic sensor instead, and there actually is a revolution counter in the car's computer. If you ran over- or under-sized tires on your car, your odometer and speedometer wouldn't read correctly anymore.",
"They know how big their wheels are and know how fast they're spinning. Since the outside of the wheel moves at the same speed at the road below it, all they have to do is add up that movement."
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j9dfby | How does window tint work? How can you see out but not in? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Your eyes adjust to the available light. When you are in a dark car looking at the bright outside through tinted windows, the eye is adjusted to the darkness and the reduced light through the tint is plenty to see with. When you are outside in the bright light, you can't see the dimly lit inside of the car with tinted windows because your eyes are adjusted to the brightness. The light traveling through the tint twice (Sun to inside & Inside to your eye) makes the situation worse."
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7
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j9iwe5 | Finding the maximum number of hosts an IP network can support? | Technology | explainlikeimfive | {
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"text": [
"2^10 = 1024 - 2 = 1022 2 to the power of (32 bits in an address - bits in subnet mask) -2 The -2 to account for the Subnet address and the Broadcast address",
"The mask of 22 means the first 22 bits of the IP address represents the \"network\" part of the address and the remaining 10 bits represents the \"host\" addresses So there are 2^(10) possible values for the hosts. The first and last address are generally reserved for network and broadcast addresses leaving 1022 hosts left to be addressed.",
"The important part here is /22 - that tells you the subnet mask - specifically, it says the first 22 bits of the IP address are the network, the last 10 bits are the hosts. This gives you 1024 IP address (2^(10)), when you remove the network address itself and the broadcast IP, that leaves you with 1022 usable host addresses",
"An IPv4 (hereafter referred to as IP just for convenience) address has 32-bits, divided into a network and a host segment. Each bit can be on (1) or off (0) -- again the numbers are for convenient purposes. So, 172.168.4.0 becomes -- as a 32-bit binary address, 10101100.10101000.00000100.00000000, the last set of 0s are the host portion (00.00000000). Every spot can be 0 or 1 (because we're dealing with binary). Since there are 10 bits to be flipped, the total would be 1024 hosts, however, per [RFC]( URL_0 ), 2 are reserved -- .0 for the network and .255 for broadcast, reducing your total to 1022."
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j9kgtm | How can everything run Doom? | Title, basically. Inspired by [this post]( URL_0 ) of Doom running on a graphing calculator powered by potatoes. Is there something about Doom specifically that allows it to be ran on microwaves, graphing calculators, or anything else with a screen? Or could other games run on all those as well, but Doom just became the **thing to do** over the years? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Doom's source code was made open source in 1997 and was written in c which is one of the most portable and best optimized languages allowing it to work on weak hardware. Since the source code is easily available and it's an old and notable game with low system requirements written in a language that is both optimized and easy to port, it became a popular game to port to weird platforms. After it became a meme in its own right, it took on a life of its own with people porting it to more and more things to continue the joke.",
"Other things can run on it. Everybody just picks Doom. It's not like Doom is special, every one just picks that to reprogram on the respective device.",
"There's nothing special about Doom, it's just a very old game. The most basic microcontrollers today are more powerful than computers were 1993, so with proper adjustments they can run any software from that time. So why Doom? No good reason really, it's just a very popular game.",
"Your calculator is basically a mini computer with its own processing power, and universally every computers can do the same job; some are just more powerful and faster than others. As long as you can create a programming instruction that can tell the device what to do, anyone can literally make any game out of it."
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j9mrbh | What are the orbs of light in photos that everyone claims are ghosts? | Technology | explainlikeimfive | {
"a_id": [
"g8kpfxi",
"g8krdpu",
"g8l1itw"
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"text": [
"Most often dust on the lens or in the air, either way they’re tiny particles that reflect light.",
"Dust particles and sometimes small insects that walk over the (video) lens. It's out of focus so it seems like something blurry that moves. A ghost !",
"In many cases it's just lens flare - when light glints off the glass in the lens. Those will typically be caused by some bright light in the photo, and appear exactly opposite the center of the photo from the light source."
],
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j9udpy | How do fighter pilots know when an enemy has them "locked on"? | Is that ominous buzz Hollywood or reality? | Technology | explainlikeimfive | {
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"text": [
"There are systems on the plane that can detect when a (potentially, but usually) hostile radar signal is frequently pulsing the plane directly. Other alerts are displayed/sounded if there are similar signals in the area, but not necessarily pulsing off of the plane directly.",
"A lot of missile targeting systems use radar to find their target. These radars have different modes depending on what data they want to collect. When looking for a target the radar might for example scan as much of the sky as possible while it might switch to scanning a tiny part of the sky to speed up its updates when a suitable target have been found. It is a bit more complicated then this with different frequencies and modes being used to gather different parameters about the target but this is the basic principle. The fighter airplane can also have a receiver that picks up the signals sent out by the radar. And by looking for different patterns of signals it can determine what mode the radar is in. So they can tell if the radar is doing broad scans of the sky or if it is doing frequent detailed updates on a tiny part of the sky. It is also possible to determine if the radar is doing some sort of countermeasures against jamming, the exact countermeasures would be secret and therefore only used in actual war so that the patterns do not fall into enemy hands. You can therefore tell a lot of things from receiving the radar signatures of a missile system in different modes. During peacetime one tactic that can be used to help develop countermeasures is to fly close to the boarder of a foreign state in order to provoke a response and gather the radar signature. There is also cases of airplanes being fired upon during such maneuvers and getting a bit more data then the pilots might have been comfortable with. Detecting incoming missiles in this way is also just limited to radar guided missiles. This is the most dangerous ones as they can operate in all weather and at great distances. However missiles can also be guided by infrared, visual, sound or dead reckoning. None of these techniques of missile guidance is detectable. However it might be possible to detect a launched missile, for example by intercepting the communication between the missile and the control system. But this does not give you any advance notice of a missile before it fires. On the other hand using these forms of missile guidance requires a lot more skill or luck from the anti-air battery commander then can be expected.",
"The electronics systems on board are able to detect and differentiate when they are being \"painted\" and when an enemy has fired at them. It's based on the type of radar signal received by the on board systems.",
"First, what is \"locking on\": in this case, it's a radar lock on. It means that the plane's radar (usually located in the nose) is tracking a plane. The radar emits radar waves and uses what is reflected to track it's target. Fighter planes are also equiped with radar warning receiver (RWR), wich detect the radar waves hitting the plane. That's how you can determine if an enemy has a lock on you. Bonus : if you are intersted in how realistic jets fighter movies are, I recommend you the channel \"ATE\" chuet topgun2speaker. He is an ex-french navy fighter pilot. Most of his videos are in french, but he also made videos in english."
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j9wpcq | if compiling a code takes hours for some software , how does they code (means how they debug , compile and check if it's running correctly etc) ? | Technology | explainlikeimfive | {
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"text": [
"For large projects, you perform debugging/testing on sub-sets of code (often called modules) with the rest of the code merely being simulated. Then, once the individual modules have been tested, you assemble everything into the final product for an integration test that tests the interaction of the modules. Large projects are also very rarely created from scratch. Rather, most of what goes into the project is already well-established code that you're re-purposing for your project. In most cases, you don't need to re-compile it because you've already got the object files for the final build. All you need to do is link those files to your new code."
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ja076u | Why does water screw up touchscreen sensors? | Technology | explainlikeimfive | {
"a_id": [
"g8mrxv1"
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"text": [
"Touchscreen works by detecting a change in electricity (CMIIW, I'm not sure) on the surface. When a finger touches the screen a tiny electrical charge is transferred to the finger and completes the circuit, this creates an electrical change at that point on the screen and signal the device to do something (open app, press icon, typing, etc.) problem is, water may also conduct electricity like fingers. screen may register a 'touch' when there's moisture on the screen."
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ja2da7 | How do military drone operators deal with delayed video feeds? | Assuming military drone operators are often very far from the drone, wouldn’t there be times when the signal is delayed and could be a problem when timing is critical? | Technology | explainlikeimfive | {
"a_id": [
"g8nas52"
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"text": [
"Well... Military drones can perform SOME mission 100% autonomously. \"Go launch hellfire missiles at this airport\" The airport isn't going anywhere. Sometimes intelligence and quick calculations are important. \"A convoy heading west from these coordinates at this speed is making a beeline for these other coordinates. It will reach this halfway point in almost exactly THIS time. The convoy will consist of X number of hard targets. Identify each distinct vehicle. Follow the 3rd one at surveillance altitude. It is a yellow jeep wrangler\" In which case, some control is needed, but once close, let tracking software do the job. If manual control is needed, use dedicated bandwidths with secure satellite connection (good enough for real time phone calls, good enough for a drone). After all, the launch facility isn't always the base of operations. Remote field locations can be set up, close enough for radio wave or the like latency to be sufficiently low."
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ja32sf | How does moving a GPS device like a mobile phone or watch in a figure-8 pattern calibrate its compass app? | Not sure if all devices are calibrated this way but I have two different brands that have instructions to these procedures. How does making figure-8 motions calibrate the sensors? | Technology | explainlikeimfive | {
"a_id": [
"g8ncqcn"
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"text": [
"You're accomplishing one very important thing when you do this: You're moving your phone through the Earth's magnetic field, allowing its magnetometer to confirm which voltages (the Hall effect produces a voltage based on how an electrical conductor moves in a magnetic field) correspond to \"This is pointing north.\""
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ja35a2 | Why is it so hard to catch/arrest/block spam/scam callers? | Technology | explainlikeimfive | {
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"text": [
"Because they operate in jurisdictions that have little to no resources or interest in doing something about it, like China or India. Both countries have significantly bigger problems affecting their citizens to actually do something that potentially affects a citizen of another across the world.",
"For the same reason it's hard to _\"catch\"_ spammers on the internet. There's just no way to know the actual identity of the caller, despite any means of authentications. The total value gained for the amount of effort you're going to have to put into this, isn't going to be worth it. The primary factor that makes emails so clean is that you can filter spam with machine learning, but you still get plenty of scam and spam, because the problem is just so complicated.",
"It's not hard, but there are laws. To make sure phone companies don't abuse their monopoly, laws require them to connect calls from all callers. There is a technology, called STIR/SHAKEN, which could allow calls to be authenticated. But it can't work until everyone adopts it. Lots of old college and company PBXs will have to be updated before that.",
"Multiple reasons 1. A lot of these callers are based in countries with limited oversight on these \"companies\" 2. Law enforcement doesn't really care both domestic or international. Small crimes like this are very low priority to them. 3. Scam business in general even in the USA are hard to shutdown. I work in car insurance and there are so many scam clinics and attorneys, the only way that get shut down us when they are sued to death, and even then alot of times they just move under a different name. Again see point 2, property crimes against the public are low priority for LE.",
"There are a lot of half right and partial answers here. But the very short ELI5 answer is that it's hard. It's a lot harder than it seems. Longer answer... I've worked in telephony for over ten years, and contrary to what others are saying law enforcement does care, they do want to stop this. I've personally worked with GBI helping track down scammers in other countries. The FCC spends a lot of time on this. This a great write up on one of the most prolific robocallers ever caught: URL_0 Different agencies are constantly working with other countries shutting down operations when they find them. But it's like whack-a-mole. This is BIG business in a lot of small poverty stricken places. Hell it's big business in the U.S. too. You have to realize that phone lines are not all simple and connected. It's not like plumbing where everything flows easily from one place to another. It's more like a relay race. Where pieces of a call are handed from one carrier to another. And you have very little insight into what's being handed to you. You have to just accept it. There's no authentication about who's calling (though see my comment about Stir/Shaken below - it's in the works). And it's not always just two carriers involved. Your call might go through multiple carriers before reaching the other end of you or the person you're calling are on VoIP, and each of them are part of this relay race handing the baton off. With mobile apps, add that for a $1.99 fee ANYONE can make ANY call look like it's coming from any other number. And that's at the consumer level. At the contact center level there are lots of legit reasons to mask your caller ID, sales calls, etc. But this means there's a ton of easily available software out there to hide who you are when you call someone. So the U.S. congress comes in and says fix it, with very little idea how tricky it is. The major carriers came up with \"Stir/Shaken\" which is a series of protocols and agreements between each of them. Basically saying \"if I send a call to you this way, I swear that I know who the caller is and they're legit\" or \"if I send a call this other way, I think it might be a spammer\". Then the other carrier has the responsibility to block the call or pass it on. This may help. But it relies on each carrier signing an agreement with the others. And it's taking a long time to roll out. And every time the industry finds a way to combat one scam, another pops up Tldr: it's complicated *Just added some more detail and a link to explain stir/shaken: URL_1"
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"https://www.fcc.gov/call-authentication"
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ja579b | Why do we need to turn off our mobile phones or put them in airplane mode? Is it really necessary? | Technology | explainlikeimfive | {
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"There are a couple of reasons. First and foremost: your phone wants to stay connected. To do that when it's far away from a tower means that it will boost it's signal until it finds a tower, or reaches its signal limit. This can cause a bunch of problems. Your phone will run out of battery faster. A stronger signal takes more energy. There is a fear that it will interfere with navigation equipment. Maybe not a well grounded fear, but a fear nonetheless. The towers on the ground also want to respond to your phone. This causes the [near-far problem]( URL_1 ) for people still on the ground. Basically, the towers on the ground need to talk extra loud to be heard by the plane phones, so it's harder for all the phones nearby to hear without boosting their volume too. Have an entire plane full of people going from tower to tower, and it just adds a bunch of load and decreases the signal quality for people on the ground. Keeping the plane slightly quieter is nice for everyone. By enforcing airplane mode, no one is making phone calls, it makes it quieter for everyone, and easier to hear the crew member instructions. There is a proposal to essentially add mini cell towers (pico cells) to planes. It would mean airplane mode would still be needed for take off and landing, but phones could be used above 10,000 feet, for text and data only. [This article]( URL_0 ) has a good about of further information",
"In modern planes, the primary concern is that you won’t be paying attention to announcements if you’re using electronics. In older times it either could interfere with the operation of the plane or they thought it could.",
"[Cell phones can connect to multiple towers at 40k feet.]( URL_0 ) It has absolutely nothing to do with interfering with flight instruments and all about the FCC and how cell phones interact with towers at altitude.",
"Airplanes communicate using a couple of VHF radios. VHF is susceptible to static interference from cellular devices. Nextel phones liked to interfere with communications so did a lot of older devices. It’s no longer a real issue anymore but, it definitely was."
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ja9ugu | Why are we using Ethernet cables for internet rather than USB? | Ethernet ports are relatively bulkier and have trouble fitting in some laptops. Why isn't a USB port used instead which is significantly smaller and is used for practically everything else nowadays. | Technology | explainlikeimfive | {
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"text": [
"Different connections for different purposes. Biggest practical difference today - ethernet maximum distance is 100 meters between switch and computer, USB can only do 5 meters.",
"Usb and Ethernet are completely different protocols, one was meant to connect many devices together in a network, while the other was meant as way to connect a computer to a peripheral, these are two fundamentally different things so you cannot use one instead of the other. Also while you could in theory just run an Ethernet signal through a usb cable, it’s not really gonna work well because Ethernet cables are designed to carry a signal for longer distances than usb"
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jaa15s | Why aren’t tablets easily used as secondary monitors? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Mainly because you add two extra layers; USB transport and Application processing Monitor; Video signal > Processing > Picture iPad; Video signal > > USB encoding/compression > USB decoding/decompression > Application-level processing > Hardware Processing > Picture On a device that has native support or great hardware access this could be significantly mitigated, but iPads are no such deviced.",
"There are a lot more steps involved. A second monitor is most likely connected directly to a computers video output. For the iPad screen to work it needs to: send a video signal over USB (not sure for HDMI, but VGA is an partiality analog protocol), that signal then gets to the iPad which has to convert it into a signal that the iPad screen can deal with and then display it. Each of those steps take time which may be mitigated with an compression algorithm. Even that can get slow when there are a lot of thing going on on the screen. Tom Scott did a video about video compression, he also showed that the resolution or frame rate drops when there is a lot of confetti on the screen."
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jad2c5 | Why can voices pass through noise cancelling earplugs? What's the science behind it? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"If they are active noise canceling, they work by creating an inverse a wave of the sound coming in. This is most effective with constant noise sources (e.g. jet engines, road noise). Voices are dynamic so creating an inverse waveform is more problematic and the headphones are less efficient at blocking them."
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jagdln | why scratched PS2 disks have low odds of loading but once they load, they don’t have problems at running the actual game? | Technology | explainlikeimfive | {
"a_id": [
"g8pf1un"
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"text": [
"CDs storage is slow to access compared to memory, so the first thing the console does is load the game program to memory. Then the program actually runs from memory. So if the disk is scratched the console may not be able to read the program at all and it's got nothing to run. But IF it can load it (CDs have quite a lot of built-in error correction to work around scratches), then it's in memory and the console can mostly ignore the disk when it's actually running."
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janw5s | Difference between Dual Rank and Single Rank RAM? | I'm trying to choose which RAM I should buy for my clients Laptop, and the processor is a i5 6200u. It is an HP 250 G5 Notebook. So far I see the RAM that is compatible with the i5 is DDR4 2133mhz, and I want 16 GB (8GBx2) but there are two options for it: Single Rank and Dual Rank; yet these two options are both 8GBx2 I'm confused. What does this mean? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The technical side of this is complex but imagine it as a spiral that only goes round twice. When data is wrote to the ram this data has to go round a 'loop' twice before it gets to the end. This is dual rank. In single rank, its more like a ring. It simply goes round once and its done. This is almost always the quicker option. In reality, unless you are doing something technical where this difference matters, a user will notice zero difference or benefit. Go with the cheaper option."
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jaqsex | How come the new Iphone can have magnets built into it and be fine while older electronics would be damaged if I put a magnet near them? | Growing up I was told not to put a magnets anywhere near things like our TV, monitor, desktop computer, laptop, and VCR. Now the newest Iphone uses a magnet to hold accessories onto it. Why isn't it damaged from this? | Technology | explainlikeimfive | {
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"A lot of the things you’re talking about from back in the day were using magnetic fields to function...CRT TVs and monitors for example using the field to control the light and color emission. Putting a strong enough magnet nearby would screw with the performance and maybe even damage the equipment. There were also a lot of magnetic storage media at the time...like, almost all of them. Audio and video tape, floppy discs, etc. a strong enough magnet would erase information and really screw things up. Things now are not only shielded better, but also not as reliant on magnetic fields.",
"Very few things are really damaged by magnets, mostly just CRTs (they use electromagnets to move the beam) and magnetic storage (which use magnets to write data), and magnetic hard drives generally need a very strong magnet to do damage, putting a fridge magnet on the case won't do anything. Modern phones don't have any of that.",
"Today's electronics are not the same as older technology. Magnets will affect/damage CRT's (television and monitor displays); hard drives (computers and laptops); magnetic tape (VCR's). Phones now actually have magnetic sensors in them and many flip covers for phones have magnets on in them to keep the cover closed (or open) and some phones and most tablets use a magnetic sensor to turn on and off the screen",
"Everyone is explaining that electronics these days are different from older ones that used magnetic fields. But how can they have magnetic credit card holders? Won’t the magnet erase the strips (but not the chips or RFIDs)?",
"Older electronics relied on magnetism to function, while modern electronics barely do. Hard drives and tapes both rely on storing data as a varying magnetic field on the storage medium, so proximity to magnets could lead to data loss. (Although, modern hard drives really aren't as susceptible to magnetic fields as many people think, and even decades ago it was rare to lose data from simply being close to a handheld magnet.) Old school CRT TVs (the thick ones), relied on magnets to direct and electron beam and make the image, so they could be temporarily distorted by having magnets nearby. Modern electronics really don't use magnets in either of those ways, so they're safe to put magnets in / around. One exception is solid-state compass modules, which help orient your Google Maps. Sometimes proximity to magnets can cause erratic readings, but most of the time even then, the app is able to correct itself pretty quickly.",
"I've used phone cases with magnet catches for years without much of a problem.... except it tends to throw the compass out. I wonder how Apple get round that",
"Older hard drives, the spinning kind, would have all data erased if a strong magnet came close enough to it. The old CRT t.v.' s would have the images warped by having magnets near them. Technology has fixed all those things.",
"I remember one of my friends had a older version phone or earbuds (cant remember which) and we’re in marching band and that year there was these strong ass magnets in our uniforms to hold an accessory to the uniform while we marched. They put their phone/earbuds in their bibber pocket which was directly where the magnet was at. Their earbuds/phone broke",
"Old CRT TVs and monitors actually rely on magnetic fields... the electron gun has it's beam redirected by an electric field to move them in one axis, and a magnetic field to move them in the other, placing a magnet near the screen would introduce another magnetic field. LCDs and OLEDs do not have this as a problem. Floppy disks, hard disc drives, audio tapes, and VHS tapes recorded everything in magnetic fields and could screw those up. SSDs don't use magnetic fields so they're pretty resilient to magnetic fields. The other issue is knowing where the magnet will be. Over a decade ago, apple started using magnets to keep the lids in their laptops closed, even when the computer had hard disk drives. The trick was that they placed the magnet in a specific area and it would never be in a position that would interact with the hard drive. If these magnets are only in the charging adapter and not in the phone, it's not a huge problem because you're not going to put much close to it and the field will fall off very quickly and most things are more resilient both by not relying on magnets but also being better shield against them. The thing I'm most curious about is the magnetic wallet attachment and if that will cause any problems with magnetic strips in credit cards. That said such strips are going away so that's going to be less of a problem. But it's also worth noting they've also gotten very good at shaping magnets and their magnetic fields to go exactly where we need them. So most of them might be designed to create just enough field in just the right place to link up with the phone without causing strong fields elsewhere that would screw up magnetic strips.",
"It guy here. So, in the old days of floppy disks and the big tvs, everything was based on magnets or metal 8nfluenced by them. Floppy disks are basically thin paper or plastic with a coating of specially aligned metal on top. Much like spinning hard drives, they are made up of cylinders, heads, and sectors, referring to how the individual 1s and 0s are arranged. Think of them like a round cake with a chessboard pattern. Each square is either a 1 or a zero. If it has a magnetic field, it is a 1. Not magnetic, 0. Take this concept and miniturize it to truly amazingly small squares and you get a general idea of a modern spinning drive. Add multiple platters or disks stacked, with built in RAM for frequently used locations, better organization, some tricks like extrapolation logic (think removing the vowels from words. You know what the words are, but they are written shorter), and other ways to pack more 1s and zeros in less space, and you see the progression of storage space to costs. Solid state drives do a similar process, but using electricity to affect transistors rather than magnets to magnetize or clear the bits. Advances in hard drive shielding, error detection, things like RAID where it increases the number of places the same data is stored to allow for errors, etc all make modern spinning drives nearly immune to consumer grade magnets. The rare earth magnets can be an issue, but they would have to be very close to the drive itself. Most mobile devices use solid state drives, and LED screens. Even many laptops use SSDs for durability and speed. At the other end, large storage arrays or servers often use hard drives that spin faster (10,000 RPM vs 5k or 7200 RPM) so are more sensitive to movement and ambient magnetic fields. They also usually have more platters and thus more read heads, so more complexity in the same space. There used to be a cautionary tale of someone who wrote a massive program by hand and put the stack of floppies with it stored on top of their tower speakers. They lost months of work thanks to the magnets in the speakers. Not so much of an issue anymore. I still cringe seeing people put the large portable drives near their speakers, but they rarely have issues anymore.",
"I've got a question for you: why are there magnets in my 7 years old ultrabook and for apple fans putting magnets into electronic devices is something totally new? To answer your question: Old crt monitors need magnets to operate and thus an additional magnet will influence or even damage them. Old harddrives use magnets and thus putting a magnet close to one will erase data on it. Same with magnetic tapes in VCRs. But there haven't been parts relying on magnets in our devices for years, so this hasn't been an issue for years.",
"People have been putting magnets in their phone cases to attach to holders for a decade. Apple didn't invent anything new. The only issue is a magnet in front of the wireless charging coils.",
"Does this freak out anyone else who has a pacemaker?",
"On top of what others have said, it's also important to know that the fields produced from magnets inside a device can be very precisely controlled. On top of being able to control their fields, other, more important pieces that could be damaged will also have very good shielding.",
"Lots of comments on how devices are not actually susceptible to magnets and they're all true if course, but there have actually been significant improvements in manufacturing magnets too. It's now possible to very precisely manipulate magnetic fields so they don't extend too far beyond where you want them to. I suggest you watch this video to see some really interesting examples of what can be done with magnets. I found it extremely interesting to see how precisely magnets can be set up. The spring at 5:45 is amazing. URL_0"
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jas84j | How do credit/debit card chips work? | What is it in that tiny yellow-orange Square that makes it possible for millions of them to be put into a machine and Identify its owner? How do the readers work in addition to the cards? | Technology | explainlikeimfive | {
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"the chip contains 2 key pieces of information to identify and verify the owner. it has your account # and the something that basically you can think of as a digital signature (cryptogram). the terminal reads this info and sends a message (typically via 1 or many 3rd parties) to the networks (visa, mc, discover, amex, union pay, etc) , the networks know which bank (or third party) processes your card based on the first six digits of the account # and send the transaction there, the bank (or third party) then looks up your account #, verifies the cryptogram, and a hundred other checks and then either approves or declines the transaction",
"In the old days, you couldn't even swipe a credit card. The department store would use a press to take an imprint of your card with the card number on it, and then submit their receipts to the bank for processing. Then came cards with magnetic stripes and card readers hooked up to a telephone line. It was still just reading your cards ID number, but these could charge your account in a couple minutes! When they got connected to the internet this time was reduced to seconds. The problem here, though, is what happens if someone behind the counter writes down your card number? What if a seller gets hacked and your card number gets stolen? Along came chip cards. Instead of simply reading your card's ID number every time, that little gold square generates a new, unique number every time you make a purchase that's only good for 1 transaction. That way, if someone were to hack in and steal the number, it would already be expired since you used it to buy a cup of coffee. The mathmatical formula used to generate that number is unique to each card and your bank can tell exactly who made the purchase.",
"They are essentially crypto chips. Basically when the card is made the bank generates a secret key (random gibberish) and your account number, the bank keeps a copy of both of these. They program these into the chip. The chip can use the contacts to talk, and it can perform some cryptographic hash function. Importantly once the chip is made by the bank, it's designed to never tell anyone it's secret key, it stays in the chip forever. When you buy something the process is something like this (simplified): 1. They ask the card for your account number and tell the bank how much the order is and give the Bank you account number, and the bank gives the store a random number (a token). 2. The store asks your credit card for the hash, it gives the card the amount and the token 3. The card generates the hash, which is something like hash(key + token + amount) and gives it to the store. 4. the store sends the hash to the bank and the bank runs the same computation, if it matches they accept it hash() is a special algorithm that can't be reversed (you can't figure out the key if you see the hash), since the amount and token are used to generate the hash, the hash is different for every transaction, even if it's the same amount. Because of all of this, a person who sees everything between the card and the bank still can't copy anything because all the data is good for only one transaction and it can't be used to running additional transactions."
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javk7e | How come mobile phones fast charge only with their respective company's fast charger even if we use a different charger with more watts | Technology | explainlikeimfive | {
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"It depends on the method and hardware they use in the device for fast charging. If they use a standard (something like Qualcomm's quick charge), then any charger supporting that would work.",
"There's more to fast charging than the amount of Watts a charger can deliver. The charger and the charging device communicate with each other and higher voltages are used than the standard 5v There are multiple standards which aren't all compatible with each other. Qualcomm has a system called Quick Charge which has versions 1 through 5. Some manufacturers use Quick Charge, but brand it under their own name * TurboPower (Motorola) * Mi Fast Charging (Xiaomi/Redmi) * Adaptive Fast Charging (Samsung) * Etc Other proprietary protocols not compatible with QC * VOOC (OPPO) * SuperCharge (Huawei) * Dash Charge (OnePlus) * Pump Express (MediaTek) * Super FlashCharge (Vivo) * Dart Charge (Realme) * XCHARGE (Infinix) [Wikipedia page ]( URL_0 .)"
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jaxbch | Why are some USB cables better at charging than others? | So if USB stands for universal serial bus, that, to me, means there is only one stream of charge, however some cables are significantly faster than others. Is this due to the width of the cable? Or quality of the material in the cable? | Technology | explainlikeimfive | {
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"USB cables contain power lines and signal lines. Some very cheap cables don't contain signal lines, so the charger and device can't talk to each other and negotiate the supply power. In addition to this, for higher power levels the cables contain a chip, this signals to the attached devices how much current and voltage can safely flow through the cable. Without this chip, charging will default to 5v 1.5A (or lower).",
"None of the answers given by the other commenters are the main reason. It is because USB does not actually refer to only one type. USB refers to many standards that have developed over the last 20 years. As the standards have improved (1 to 2 to 3 / 3.1 to 3.2 to 4) the data transfer rates and power delivery have increased. However for this to work, they needed to utilise more pins in the ports among other things. So in reality these cables are built different based on the USB standard they are designed for. Plugging a USB 2 cable into a USB 3 port will limit you to USB 2 speeds. Edit furthermore there are standards in USB 3 called power delivery that can deliver up to 100W, so it very much depends on the design of the cable, and the port it is plugged into. (This is why you can buy cables that are specialised for data transfer or for lower delivery.)"
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jaxv4m | How do rail guns work and why are they not used to launch things into space? | Technology | explainlikeimfive | {
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"A rail gun is basically a gun that uses electromagnets to accelerate the payload rather than rockets or an explosion. They can theoretically be used to accelerate things to far greater speed than conventional guns, but that comes with some caveats: a) With the level of technology we have right now, the wear on the rails inside the gun is horrific--they need to be replaced after every couple of shots. b) They can't really be used for anything very large yet either. As for using them to launch stuff into space? The problem you have there is the atmosphere. Orbital velocity is around 17,000mph, so to fire an object into space with any type of gun, it has to be going quite a bit faster than that in order to compensate for gravity and air resistance. Anything hitting the atmosphere at those sort of speeds will rapidly heat up--you can see this when spacecraft re-enter the atmosphere from orbit, and bear in mind that those are hitting the really thin atmosphere high up, not the thick stuff lower down. Chances are trying to fire something at 17,000mph anywhere near sea level would immediately destroy it. And then, even if you could somehow get around all that, it wouldn't remove the need for whatever you're launching to have its own propulsion system, because once it gets out into space it needs some way to circularise the orbit--otherwise, it'll just come straight back down.",
"Rail guns are a type of electric gun design. By applying a voltage between two rails and short circuiting them with a projectile while continuously supplying them with massive currents will create a force that pushes the projectile forward. The problems we have is related to supplying it with enough current without melting and damaging components. This does include the projectile which have a tendency to melt, boil and then turn into a ball of plasma before it can leave the rails. But even if you can solve these issues in the gun and were able to shoot a projecile at orbital speeds it would compresse the air in front of it heating it up so it would melt, boil and then turn into a ball of plasma. And satellites do tend to work slightly better if you manage to keep them from turning into plasma. Similarly astronauts do tend to feel better about the launch knowing that their bodies will be able to retain the same state of matter after the launch as before.",
"The most fundamental issue is that either the acceleration would be high enough to turn astronauts into a paste, or you'd have to make the thing miles long. Neither option is really any better than current rocket tech.",
"Rail guns us a law of electricity to shoot. But to go fast you need a lot of power, and just like your PC gets hot when using a lot of power so does the thing you're shooting. This is a big limitation. You need to go really fast to go into space, like really really fast. Wind resistance slows things down just like it slows down a baseball or a bullet. Rockets overcome this by constantly pushing. Just like driving a car. You need to have the throttle down or you just keep slowing down."
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jaxvdg | How does software "improve" a phone's camera quality? If it does, can it (software) be used on cheap 2MP phone cameras and make it look really good? | Technology | explainlikeimfive | {
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"One of the ways this can help is by noise reduction. Instead of simply taking one picture which will have a certain amount of graininess due to random noise, you can take a series of pictures over a short space of time. You can then average between them (using software to make sure the images are lined up), and that can help reduce the noise in the image. Because the noise is random, it'll be different from image to image. By contrast, the actual stuff in the image will be in the same spot. This is essentially what Google's astrophotography mode does, but here it takes a decent camera and makes it look epic!"
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jb0c14 | why cant we create video game graphics as good as cinematics? shouldnt the texturing be the same as making video games? | Technology | explainlikeimfive | {
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"A frame in a video game must render on a $500 computer in 1/30th of a second or less. A frame in a movie is rendered on a six or seven figure rendering supercomputer and can take however long it needs.",
"By cinematics, I assume you mean movies. The main difference is that video games need to render frames in real time, whilst movies are filmed either with a real set, or CGI which takes many hours of work for a few seconds of footage.",
"Cinematics are pre-rendered, the game is essentially just playing a movie clip. This isn't very taxing for the computer. The game's real graphics have to be rendered in real time, which is very taxing. You have to draw all the textures, calculate all the lighting, particle effects and so on 30/60 times per second.",
"For CGI in movies, an entire team of artists spend hours or days on each scene, tweaking the animations by hand (or using motion-capture on actors) to look fluid and natural. They then send the data to a cluster of supercomputers that can spend hours, or even days, rendering a single frame of the resulting video (*Toy Story 4* took between 60 and 160 hours to render each frame of the movie, and there are 24 frames per second). Compare that to a video game, where the animation has to be programatic (so that what the character does can respond to user input), so there are a limited number of actions and movements that a character can make, and all of them have to be predetermined. Plus, each fame has to be able to be rendered on a fractions of a second on consumer-grade hardware. There's just no possible way to get movie-quality visuals in a real-time medium like a video game, because the game will always be running on hardware with a fraction of the power, and won't have a team of artists hand-animating character movements (or motion-capturing actors) in response to every single button press."
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jb1dsd | When i'm wearing headphones and I remove the cord from the device, I hear a static. What exactly is happening there? | Technology | explainlikeimfive | {
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"There are small voltages involved in sending an audio signal to your headphones. So when you pull the plug out you are disconnecting an electrical circuit. In the split second the resistance is spiking as the voltage tries to connect to push across the air gap. It's not enough voltage to \"arc\" electrically but it's essentially a tiny attempt. This tiny electrical spike is picked up by the speakers in your headset and reproduced."
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jb3ymg | During WW2 how did the Germans accurately hit London with v2 rockets , when the rockets could not be guided | Technology | explainlikeimfive | {
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"The rockets had a basic inertial guidance system. Essentially it functioned by tracking the compass heading, speed, and flight time. This is really all that's needed to hit something as large as a city. The purpose of the V2 was primarily psychological. They weren't trying to hit a specific target, just anywhere in the city. That lowers the bar considerably, when it comes to navigation.",
"Yes London is a very big sprawling metropolis and it is difficult to miss entirely, however it also means that your chances of killing people or destroying anything of value are also reduced it has been calculated that more people were killed making the V2 than were killed by being under one when it landed.",
"They were not very accurate and often didn't hit the targeted cities. They were basically fired like artillery. They were more psychological weapons to intimidate the general population as they could hit and caused damage and deaths. Thousands were fired so that at least some hit their wider target. Later in the war they became somewhat more accurate when a radio guide beam was used, but that also had limitations."
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jb4b3v | Why is it often necessary to restart a computer after a large program is installed? | Technology | explainlikeimfive | {
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"Programs use shared files called DLLs. The DLLs are like a toolbox that provides commonly used functions to lots of programs so that those programs don’t have to worry about knowing how to do them. Some programs lock these DLLs so they can’t be changed or deleted while the program is using them. If an installer has to update one of these shared files then the update has to be scheduled at the next reboot and the computer has to be restarted so the programs close and unlock the files."
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jb5h1c | Why was Windows Vista considered "bad" compared to XP and Windows 7? | Technology | explainlikeimfive | {
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"**XP** was considered a very good OS, especially after the second update (called service pack 2). It ran fast and effectively even on older hardware, was compatible with everything, and had most of its issues and bugs squashed. **Vista** comes in and is a resource hog, many even fairly new hardware setups ran poorly on Vista, older systems ran terrible, and even newer systems struggled at times. Additionally a lot of minor changes across the user interface and elsewhere were implemented that were not well received, and while any single change wasn't huge, adding them up together culminated in a bad experience. Basically, it ran poorly, had changes that didn't make sense, and didn't really provide any benefit over running XP. There was almost nothing to gain from upgrading to Vista over XP, you were more likely to lose functionality than gain anything. **7** came along, and we can basically call it windows XP the sequel. They backtracked from a lot of the Vista changes, actually made the OS work with worse hardware (that is, hardware that struggled with Vista, worked with 7, and hardware that was just OK with Vista, blazed on 7). Essentially it was a return to form, while including a lot of new modern changes to bring it up to the current time."
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jb8w9i | How NES was able to release games of just few MBs? | For example, any SNES game is not more than 5MB, despite the fact that it was packed with a good sound track and graphics. How NES was able achieve such tight packing? | Technology | explainlikeimfive | {
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"They didn't store audio clips or large images. They stored something akin to a machine version of sheet music, which told each of the NES audio channels how much sound to play at any given time (which is a pretty limited format, which is why NES sounds are so distinctive). The Game Boy did the same thing, which is why you can find glitchy Pokemon who have \"cries\" formed of garbled data interpreted as audio. Most NES games have at most a few dozen tiles, perhaps fifty or a hundred not-very-high-resolution sprites (which often got palette-swapped to extend their useability), and limited animations, none of which take up very much space. But even then, a great deal of work was put into those games to trim down their size as much as possible.",
"Yeah you gotta remember that even tho SNES games had good music it was still 8bit(iirc?) So the real genius is in the people that made the music. Graphically it's the same, only so many bits to work with mean that the design team had to really think about how each pixel would be moving on your screen as you played to achieve clarity."
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jba3fr | How do 3.5mm headphone jacks work? | Technology | explainlikeimfive | {
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"There’s are three or four “layers” in the jack, separated by the plastic usually black or white rings Each of these layers is connected to a different wire, so you are just connecting wires like any other connector, one wire is common for everything, the others are one for each ear, and if it’s got a fourth connection, that goes to the microphone"
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jbc3a7 | how exactly does one guide a TOW missile? | It shoots from the launcher, but then they’re able to steer it somehow. I understand there’s a cable or something involved? I still don’t understand how it works. | Technology | explainlikeimfive | {
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"Yes there’s a wire URL_0 it steers using the fins based on input it gets from the wire (some are wireless)",
"yes, the TOW missile is wire-guided. meaning that when it's fired, there's a spool of wire unraveling behind it which transmits the guidance instructions from the operator. there is also RF variants that use radio signals to guide it."
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jbevnx | What is 5G, and why is it so much better than 4G? | Technology | explainlikeimfive | {
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"You're incorrectly assuming that 5G is always better than 4G, but that's not necessarily the case. Easy real world example: T Mobile currently has one of the biggest 5G networks in the world, but Verizon's 4G network has higher speeds than T Mobile's 5G one",
"With 5g they use mini cell tower that are usually on light poles and other neighborhood infrastructure. These mini cell towers communicate with the big cell towers using frequencies different then the mini to end user frequencies. So there is less congestion and competition to get to the large regular cell towers. The mini cells are usually placed with in a couple hundred feet of the intended end users.",
"5G is a completely different technology that will eventually replace your 4g on the same frequencies used today. Most 5g you hear about today are two different types - 5gNR which is low frequency, and 5g ultra wideband which is using new high frequencies. 5g gives a bunch of new benefits, but the main two you will experience is speed (up to 10 gbps) and latancy ( < 1ms). Latancy is how fast the signal actual gets to you. Having this quick connection and low latency allows for some really cool things to be developed over the next decade. One example is robotic surgery controlled by a surgeon anywhere in the world. With latency that low you'll see a lot of advancements in VR and AR as well."
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jbkpcs | Where does that extra small storage in internal and external hard drives go? | 1TB shows 940GB (my laptop) 128GB shows 100GB (my phone) 64GB shows 58/59GB (my USB Pen drive) Where does that extra storage go? What takes that storage? Some hidden hidden files that are used to run that storage properly? If that's the case then why is there so much difference in that unaccessible storage from 5-50GB and more if you go beyond 1TB? | Technology | explainlikeimfive | {
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"So, this is a bit of marketing mislabelling that technically is true but unintuitive. There are two ways to measure storage. One is in powers of ten (like other SI units). A megabyte is 1000 kilobytes. A gigabyte is 1000 megabytes, and so on. However there is a different storage base that is more sensible for computers: as powers of 2. In this system a mebibyte is 1024 kebibytes. A gib is 1024 mib, and so on. Marketing material uses the former is it appears larger. Windows uses the latter as it makes more sense. This makes it appear as the device is smaller than adverised. It isn't. Sure, some of it is index tables and reserved file system data, but a lot of it simply is that 1TB ~= 940gib or so.",
"Base 2 vs base 10. Hard drive manufacturers measure drive sizes in powers of 10. A 1TB drive holds 1,000,000,000,000 bytes. Windows, however, shows drive and file sizes in powers of 2. In this system, 1 kilobyte is 1024 bytes, not 1000. One gigabyte is 1024\\*1024\\*1024 =1,073,741,824 bytes, and so 1TB (in base 10) is slightly less then 940 gigabytes (in binary). Technically, in this system the sizes are named ki*bi*byte, me*bi*byte, gi*bi*byte etc. (which would distinguish them from the base 10 kilobyte, megabyte and gigabyte) but nobody uses these names. Your phone is an exception, as it doesn't show part of the drive that is dedicated to system files."
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jbmx3u | - Server maintenance | What happens when a computer game server is being maintained? I have in my head they delete caches and do a reboot, what else? | Technology | explainlikeimfive | {
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"Usually the are doing software upgrades or otherwise making changes to the core services that might disrupt gameplay. It is much, much easier to just take the servers down for a few hours, do all of the patches that they need to do, test it, then bring everything back up.",
"Could be many things. Examples are: applying operating system fixes and patches, adding more memory, installing new software, doing network updates, updating the applications that run on those servers... it's usually different each time depending on the needs of those specific servers."
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jbosax | Why are beakers made of glass? | Is there a special reason for why lab containers like beakers or test tubes are made of glass besides the fact that its see through? | Technology | explainlikeimfive | {
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"Glass is very resistant to a wide range of chemicals, can be heated and cooled to a wide range of temperatures, and is fairly sturdy.",
"Glass, particularly borosilicate lab glass, is highly resistant to chemicals. It's also temperature insensitive, so it doesn't crack when heated or cooled.",
"On top of all of the previous listed things, glass is not very porous and is easily sterilized.",
"Beakers are made from different materials, but a common one is made of what is commonly called Pyrex. It needs to be resistant to chemical reactions (you know, like how metal can rust with oxygen and salt). It also needs to hold it's shape/volume over large temperature ranges (anything from liquid nitrogen to boiling hot liquid) and Pyrex can handle this without shattering. You also don't want the material of the beaker to interact or react with anything you put inside, and glass is generally inert."
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jbqfab | How do tv channels/online streaming companies count the number of viewers watching shows? | Is it by internet activity? Or by individual accounts logged in and streaming? If for instance, I were to put the same show on 2 TVs and my laptop, all on the same WiFi network, but 2 different streaming accounts, would it count on their end as 3 (individual streaming devices), 2 (individual accounts), or 1 (individual household/WiFi network)? | Technology | explainlikeimfive | {
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"With streaming services like Hulu, Netflix its that simple. Each browser/user agent/playback device has a uniquely identifiable ID that counts as a distinct \"view\". I.e. so the Chrome browser on your laptop watching Netflix can be discerned from your Android tablet also watching Netflix, even though you might be watching the same show... episode even, same Netflix account even.",
"Streaming networks know how many devices are connected to their services, including how many devices per account. So it is very easy for them to track viewership by household, by account, or by device. TV channels can't do this; they have no way of finding out for themselves who is watching and where. They rely on input from third-party services such as Nielsen, which pay people to tell them what they are watching and when. The Nielsen system has been in place for longer than I have been alive (I'm in my forties) and works quite well. They can turn out viewership reports in a matter of hours, which they turn around and provide to the networks."
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jc021b | Why is it that computers can (for example) run minecraft shaders at max settings at 100FPS but take forever to render photos/videos? | sorry if the title is confusing but my computer can run a game with good graphics at around 100FPS but when i try to either render a video or photo in archicad or something, it takes longer than it would to run a game that looks way better. | Technology | explainlikeimfive | {
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"text": [
"Render software are usually optimized for accuracy not speed. Games on the other hand are optimized for speed. This doesn't mean games *can't* look good, but rather \"realistic\" looks in games take shortcuts and are essentially fake and not as accurate as the same things in rendering software. Rendering software on the other hand doesn't take shortcuts and uses much more intense, accurate calculations. As such, every piece of every frame takes significantly longer than a *similar* scene being rendered in a game engine.",
"Reading data and writing data are different. To put it simply: Rendering a video is like drawing a picture, or writing a book; it takes time. Looking at a picture or reading a book doesn’t take that long by comparison."
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jc0ght | Why can't we use text in things like italics or bold in cell phone text messaging? | Technology | explainlikeimfive | {
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"text": [
"The SMS standard is plain text only, so doesn't include any formatting information - adding it on new devices would break compatibility with older or simpler devices. However, some SMS apps will allow it by using basic markup, such as enclosing text in asterisks in order to signify bold. Apps which recognize this will hide the symbols and display the text in bold, but the message will still be readable on other devices."
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jc0lu0 | How do applets work in contactless cards? | I work at a financial institution and we just rolled out new contactless cards. While reading a third party research report on the technology it said that the chip is still important and relevant to keep as a part of the new cards for the protection of consumers’ data because it has applets that can’t be cloned by fraudsters and add a layer of security during authorization. A Google search just says applets are like single purpose applications or software, but how do they actually work in conjunction with the contactless credit or debit card? | Technology | explainlikeimfive | {
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"A magnetic strip contains a string of characters that it uses as a password. This can be read by anyone with the right scanner, so a fraudster can just steal it and add the string to their card. There's no security there. A chip can run a simple program, which means it can do a little song and dance to send the password without just sending it in plain text. Here's how this works: 1. The cash register sends a really big number to the chip. 2. The chip knows the correct password, but can't just say it. Instead it uses some complicated math to combine the password with the really big number. It then sends the combined number back to the cash register. 3. The cash register does the same math on its end. If password + really big number = response from chip, then the chip must know the correct password. Even though it never said the password in plain text where an eavesdropper could overhear, it must have the password if the answer is correct. Now, a clever attacked could normally reverse the equation and turn the response and the really big number into the password. The trick is that the complicated math is a one-way equation. It's very easy to do one way, but would take literally millions of years of computer power to do the other way. The simplest example of a one way equation is multiplying two prime numbers together. Multiplying 47 and 31 is easy. Math tells us that there is only one way to get 1457 by multiplying two prime numbers together. To figure out which two, there's no easy way aside from just trying every prime number until one works. For a four digit number that's easy, but cryptography uses numbers hundreds of digits long. It would literally take longer than the lifespan of the universe to crack good encryption on your desktop. If you're interested in the math behind this, [Computerphile has a video]( URL_0 ) has a video explaining this strategy. It's a little more complex but still fairly approachable.",
"The primary purposes are to do \"authentication\" and encryption. Authentication is to prove to the Point Of Sale (POS) terminal that the card is what it claims to be, and to prove to the card that the POS terminal is valid. Encryption is used if other information must be passed back and forth if you don't want a potential attacker to be able to read it. Authentication is done using encryption. The POS terminal generates a random number and encrypts it. The card decrypts that number, re-encrypts it using its key, and sends it back. The terminal decrypts it and if it is the same random number that it generated, then both the POS terminal and the card \"know\" the proper encryption keys and are hence assumed to be authentic. You can't have a \"man in the middle\" attack from a third party intercepting the messages from the card and the POS terminal and passing them on, because there's no information sent in the clear. Since it uses a random number, this authentication process is different every time and can't simply be recorded and played back to fake authentication. After that, they can send encrypted information (such as the debit card name/number) to each other using either those same encryption keys or preferably a new set generated just for that transaction. One of the challenges for doing this with a contactless card is that all of the power to do these calculations comes from the radio signals sent out by the POS terminal, since the card doesn't have its own power source."
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jc4aph | why does your trash folder always have a lot of spam emails which were sent to different and similar email addresses | Technology | explainlikeimfive | {
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"Oh, okay. So the email protocol is actually ridiculously insecure, like laughably so. And it basically works like this: 1) Connect to the receiving email server that your recipient’s account is on, say URL_0 2) Send a “hello” message 3) Send a message telling the email server what account on that server to deliver the message to, for example, user (at) URL_1 . This is the account the email will be delivered to regardless of what is specified in the header of the message. Note we haven’t even sent the actual email header yet, this is still the actual SMTP mail protocol. 4) Now we send the actual email contents, including the headers of the email. Note the email headers can specify a totally different “from” and “to” address than what you’re expecting, which is why they can specify a totally different “to” address than your actual address, and it’s the address in the “to” field in the email’s header that shows up as the “to” in your email client. Also note that you can put any “from” address you want and the message is still considered valid as far as the SMTP mail protocol is concerned. So that’s why. Because the email account the message is delivered to is sent separately from the email message that’s sent in the email headers. Edit: I was sleep deprived when I wrote this but the legitimate use case for this is if your address is in the message’s CC or BCC then it wouldn’t be one of the addresses in the “to” field."
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jc7axw | How do ultrasounds work? More specifically, how does it look like there's a live cross-section of the womb and fetus? | Technology | explainlikeimfive | {
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"I worked with ultrasound imaging, but in solid mechanics, and not biomedical imaging. I can explain the broad principles, but not the details. An ultrasound device sends out a short pulse. This pulses travels through material. If it hits a boundary, part of it is reflected, part is transmitted. The receiver measures the reflection. From the time that passes between sending the pulse and receiving the echo, you know how far in the pulse was reflected. Youre interested in the boundary between the fetus, amd the surrounding liquid. When imaging structures in a body, woull get all kinda of reflections (from different tissues, etc). The trick is to know which reflection is the one youre interested in. Since you roughly know how far from the sender you expect the kiddo, you know where to look for the relevant reflection. Also, since the fetus swims in some water there is a very hard boundary, and it will be one of the clearest reflections you receive. In this way, you can scan the foetus and get a heightmap. The software processes this into an image, and youre done."
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jc7jtx | How are smartphones still able to display the "battery depleted" symbol if there is no more battery? | Technology | explainlikeimfive | {
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"text": [
"Because the phones still have just enough battery left to display it. The battery is not truly dead until you cant turn your phone on at all.",
"A car can have 0.25 gallons of gas in the tank, so it's not truly \"empty\". But it's also not enough fuel to start the engine either."
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jcb235 | Why does basically every web page ask about allowing cookies/settings? What is the correct response to this? Accept and allow? Disallow? | Technology | explainlikeimfive | {
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"text": [
"Cookies are basically like a small identification card that *the website gives to your browser* to identify it later. So now this card can be used by advertisers for targeted advertising. Since it can used to profile people that way the EU has put up laws mandating that they inform the user that this data is being collected about them. You will not be able to fully disallow them but you can disable certain parts which will be a bit of a process after you click the disallow button. In my case I only give allow all if I'm impatient at the time.",
"Cookies are small pieces of information in the form of text, websites store on your computer. Cookies were designed to allow websites to remember information (such as items added in the shopping cart in an online store) or to record the user's browsing activity (including clicking particular buttons, logging in, or recording which pages were visited in the past). The text can be a user ID, any other text. For example, web pages can be configurable – a web page could have a Hide link that hides a certain element on the page. The page can save this setting on your computer with a cookie. When you load the page in the future, the page can examine the cookie and automatically hide the element. If you don't accept cookies, no information will be stored. When you go back to the site it will not know what pages you have looked at or what links you have clicked. If you clear your cookies, you’ll be logged out of all websites and websites won’t remember any settings you’ve changed on them. It is a legal requirement for websites to ask you if it is OK to store cookies. There are some conditions to the law but I don't think it helps to explain them here.",
"If you disallow some pages might not show correctly, for example YouTube videos require third party cookies to be accepted because they track what videos you watch on other websites. What the good option is really depends on the website. Shady websites can fire up to 50 cookies that are all focused on showing you more relevant ads by building a profile across others pages. No harm comes because of it besides you giving away to other websites which pages you visited, but I disallow them on shady ones because I dont want them to build up a gigantic profile of my behavior. Other websites only use them on that specific website, for example for showing relevant content, or to store your login credentials or to remember where you left off. Good to remember that before 2018 they fired the cookies anyways, only since the GDPR officially they have to ask and give you an option to decline. But many websites don't give you proper options to easily do that. So: Fine to accept them on websites that aren't completely tailored to ads, try to avoid em on the ones that are focused on ad revenue if you like your privacy. Source: Deal with these things at work.",
"Others have covered what cookies do. I'll add that they have been a normal part of most websites for many years. All of the notifications were added pretty recently, due to a change in EU regulations. If you've been online for 15 years, chances are you've been using cookies that entire time."
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jcd8fz | why are single camera-shows considered higher quality than multi-camera shows | Technology | explainlikeimfive | {
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"text": [
"Basically, if you are doing a show with a single camera, you have to plan the shots carefully, and work ahead of time to figure out how the camera is going to film the action. A show with a standing set that has multiple cameras going can just film the action and pick and choose what looked good afterwards. It's seen as an easier and more convenient way of filming, but means you aren't going to get anything special.",
"Two reasons: lighting and focus (bokeh). Multicamera setups require uniform lighting over the whole set. They also have to flatten the depth of field, requiring a tighter aperture (higher F #) meaning the lights have to be very bright. Single camera setups can use a wider range of lighting and can use much faster lenses (more open apertures) allowing for much darker shots. This allows for much more subtlety in the lighting and creamier bokeh contrasting against the sharply focused subject. \"Higher Quality\" is subjective. Personally, I prefer the cinematography of a single camera to multi camera shows like Friends. I find them more visually interesting. But that doesn't mean the show itself is actually better. Any good story can make a good show, no matter how it's shot.",
"In general it's because multi camera shows used multiple cameras in order to get all the shots they needed in one take. But that also means you aren't doing anything very exciting with those cameras and you only get one take! Single camera shows are shot like a movie, lots of different shots, lots of takes, and assembling the best of everything. That said I'm not sure this is as true anymore. It seems like most 'multi camera' shows are using the style but not the actual techniques and corner cutting."
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jce6fh | What’s the hype behind 5g. Will the average person see any benefits from using it? Is this just a marketing tactic? | Technology | explainlikeimfive | {
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"It is just the next iteration of wireless phone technology. Its isn't _just_ marketing - it is a different radio tech using a different portion of the frequency spectrum. As for benefits, it is primarily faster phone internet speeds. 4G tops out at a theoretical 100Mbps, but 5G can theoretically do 10Gbps - which is probably faster than your home internet connection.",
"5G makes use of a wider range of radio frequencies. This will allow cell towers to serve more concurrent users before degrading performance. That means more reliable service in crowded areas. 5G has the potential to be a big deal, but not for the reasons that are being marketed. This is probably because most providers aren't keen on pointing out how shitty their service can be in densely populated areas right now.",
"For most people, getting a 5G-enabled smartphone, nothing is going to change much compared to the 4G-LTE smartphone you have now. In fact, many 5G smartphones will continue to use 4G-LTE most of the time, only using 5G when necessary. 5G will provide marginally faster download and upload speeds and slightly reduced latency. The notable difference is if your smartphone supports millimeter-wave 5G (AKA 5G \"ultra-wideband\", as Verizon likes to call it.) When connected via mmWave 5G, you will potentially experience massively increased download and upload speeds; faster than you have probably ever seen before, even on your home wired connection. We're talking about speeds that will let you download 4K UHD movies in seconds. But mmWave 5G coverage is *extremely* finicky and sparse; you'll only really find it in major city centers on specific blocks. What 5G *really* does is it enables cellular data usage for things *other than* a smartphone. Things like laptops, cars, IoT devices and more. Yes, those things can already connect to 4G-LTE, but 5G will provide the kind of bandwidth, low latency and reliability to make those things really come alive with new applications that 4G-LTE can't quite handle. For example, cars in the future will be able to use 5G networks to talk to each other and to roadside infrastructure in real time, enabling self-driving or remote-driving vehicles on a large scale. Millimeter-wave 5G can be used to connect homes to the internet where it would be too expensive to run a fiber line. While these things are *possible* with 4G-LTE, 5G will make them mainstream. So the average smartphone user probably won't see a whole lot different when upgrading to a 5G device. But 5G technology does enable a lot of new scenarios that justify the hype behind it.",
"5G is using higher frequencies than older generation, which mean it can carry more energy, which mean it can carry more data. 5G can in theory be 100 times faster than 4G. Of course not all 5G network will be using all the exact same frequencies and tech so the speed will vary, but the different is massive. The other advantage is the amount of free frequencies available, which is really important because the frequencies we are currently using are getting crowded. In the past we couldn't really use those higher frequencies because they get absorbed more easily. But with a couple of new technology we can build smaller, more numerous antenna that will bounce the signal around building and allow us to keep the signal strong in cities."
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jce8vw | How much capacity of a storage device can be lost to formatting before I'm being ripped off? | Background: **I am aware** about binary vs decimal measuring of GB, so for the sake of my question, I am only worried about bytes. For example, my "32GB" SD card advertises that 1GB is 1,000,000,000 bytes. Fine. The capacity of the drive when formatted is 31,145,295,872 bytes and even completely empty, 65,536 bytes are used. The guiformat tool tells me the disk has 60860416 sectors, 512 bytes per sector - if I do the math, that gives me 31,160,532,992. Still well short of 32,000,000,000. If I'm not mistaken, that means that even if I could format it such that every single byte in every single sector was mine to use, I would still be about 2.6% short. Is my reasoning wrong? I asked Google, ended up here. It wasn't good enough for me (thus, ELI5). URL_0 Edit: The gap in my understanding here is, wouldn't 31,160,532,992 be the unformatted capacity? And the formatted capacity (which includes FAT and such) is 31,145,295,872. It seems like the first number should be 32,000,000,000 if the product was completely true in advertising. Has any mfr ever explained away where that 0.9GB of *unformatted* capacity went? | Technology | explainlikeimfive | {
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"text": [
"Filesystems aren't just like a big book of blank pages with stuff to be written in them. They're a complicated system of indexes, pointers and cross-references which are designed so that you can quickly find, add/append to, and delete different paragraphs and pages of the book in whatever completely random order you like, without resulting in an unusable disorganized mess. Imagine writing a manuscript for a book, and you wrap up chapter 1, and get started on chapter 2, and halfway through chapter 2, you have some more ideas for chapter 1. But you didn't leave any blank pages in between, so you're gonna have to type out your additions later in the book, and add a \"please jump to page 47\" at the bottom of page 28, and... You can easily imagine how writing the book out of order will get complicated. So the filesystem includes a bunch of indexes and \"where to find the next chunk of data if it's not physically adjacent on the disk\" tables designed to strike some sort of balance between ease of reading, ease of writing, and efficient use of space. Filesystems like NTFS, ext4, FAT32, HFS+, etc. represent different tradeoffs between those considerations."
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jcgamu | how are phones able to make emergency calls without service ? | Whenever Im at the gym I have zero service and my phone says emergency calls only. Why can it call 911 but I can't call my grandma? | Technology | explainlikeimfive | {
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"text": [
"Your phone service is owned by a specific cell provider. If you have no service, it's because the phone isn't able to talk with that provider. However, there are other cell providers that *usually* have service in the area. Emergency calls (to 911) were deemed important enough that *all* cell providers in the US must allow them to dial the service. So you don't have cell service to your provider, but you have service to *some* provider, and that provider has to give you 911 access regardless of who your cell provider is.",
"Every phone that can reach at least one cell tower that uses a frequency band that its radio chip and antennae can communicate with is mandated by law to be able to use any network it can reach to make emergency calls. i.e. even if the phone isn't recognized by a carrier's network, it still has to allow that phone to make emergency calls. So what your phone is saying is that it can't reach your regular network but it can reach _A_ network (that it can talk to) and can make a 911/999 call if you need. Imagine if you were out of range from your AT & T network but within coverage of Verizon or whatever and someone died because you couldn't call 911? Yeah. So, every cell phone that can talk to a compatible network can make emergency calls. Same thing if you don't have a SIM card -it can still be used for emergency calls. Also, if Im not mistaken \"emergency\" mode on your phone will kill all background apps and data for maximum battery life and boost your radio signal - so maybe your coverage is too weak for normal calls and data, but still reachable in case of emergency. LPT tip: go buy a cheap / used cell phone, charge the battery up and turn it off (or throw in a battery eliminator) and throw it in your car emergency kit.",
"Because there are other cell carriers towers in the area that you aren't normally able to use because your carrier doesn't have an agreement with the carrier that runs them, but by law are able to do so to make emergency calls."
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jcllzq | How was ice made and transported before refrigeration? | Technology | explainlikeimfive | {
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"text": [
"It was mined from places where ice occurs naturally and kept in giant insulated warehouses. Sometimes evaporative cooling was used too. I highly recommend the wikipedia article on evaporative cooling, the history of it is pretty incredible.",
"Sawdust was used as insulation too. They used to cut ice out of a pond near my house in NH and transport it to the south. They even put it on ships and transported it across the ocean.",
"Ice was mined from lakes and rivers in the winter as large blocks and stored in insulation like straw and sawdust Large quantities of ice keep surprisingly long with only a moderate amont of insulation. In our city we have a snow pile that builds up over the winter from clearing the roads that reaches 4-5 stories high. With only a coating of gravel left over from the melting snow the hill steadily shrinks but lasts well into July."
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jco17q | Why is the steering wheel on the left side of the car for countries that drive on the right side of the road and vice versa? | Technology | explainlikeimfive | {
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"text": [
"It’ safer when the driver is nearer the center of the road. They have better visibility and are less likely to drift into the other lane by accident. Also, if buses weren’t designed that way, passengers would be getting on and off from the center of the road instead of the sides.",
"If you are driving on the right side of the road, someone heading in the opposite direction is to the left of your car. By sitting on the left, you can most accurately judge the distance between your car and the oncoming car."
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jctk5h | Why do most websites tell me "Incorrect E-Mail or Password" and not just tell which one i put in wrong? | Technology | explainlikeimfive | {
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"text": [
"For security reasons. Otherwise a bad actor would know the email is valid and just keep bruteforcing the password.",
"Because it's checking to see if they match, and not checking for anything else. Also, if someone is trying to break into accounts, confirming that a particular email or password is in use is information that person didn't have before, and giving it out is bad.",
"Not really the biggest deal, but not exactly a great idea or a good database call to let you enter passwords and have it scan if anyone has that password then tell you that you got the password right (for someone) but not the username you wrote.",
"Security! If you tell someone that a certain user exists than you have already done half their work for them. It helps a potential hacker create a list of email accounts on that system by trail and error. A hacker might look through past breaches where on a different sites a now known email was used with different passwords and try those. They might also send the email a phishing mail knowing that they have an account there. In general it is a bad idea to give any sort of feedback on a login attempt to let the person know how close they came to getting things right.",
"Aside from security, they don’t know which one you put in wrong. Say you have two users: skinnyseth012 skinnydeth012 If skinnyseth012 messes up their password it could be because they were actually skinnydeth012 who put the correct password in but made a typo when they entered their username. The computer doesn’t know which one you are, all it knows is the password and user name didn’t match. Some websites tell you flatly if you entered a username that doesn’t exist, but that’s an extra step and has some security issues, so a lot of the time even when you enter a wrong name that doesn’t exist they just say you got one of the username or password wrong"
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jcwjv9 | How audio and microphone in a "wireless" earphone work? How good/bad a "good wireless earphone" is compared to a "good wired" earphone in terms of audio quality? | Technology | explainlikeimfive | {
"a_id": [
"g9472pn",
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"text": [
"Ok so there's really two things at work here: 1 - the quality of the audio components. This is determined by the quality of the speakers and microphone(s). Higher-end products often use multiple microphones and compare their signals to reduce background noise. Whether the speakers and mic(s) are good or bad is not really a function of whether the headphones are wired or wireless, but rather of the overall quality and price of the hardware. Better speakers/mics typically are made of better materials and have more sound engineering put into them. Increasingly software also plays a role here as the headphones will have circuitry that optimizes the audio for the hardware. 2 - the transmission method (wired vs wireless). The first thing to know here is that most of the time we're dealing with digital audio these days. This means that your audio is not an analog waveform but rather a series of 'samples' of the original wave. Think of it like the audio equivalent of pixels in an image. What may look like a smooth gradient is actually a mosaic of small dots that are imperceptible unless you zoom in. Digital audio is similar. The 'resolution' of audio is measured in bitrate, which is how many of those samples are taken per second. Here's why that's important: a wireless connection can transmit a certain number of bits per second, and the audio is also a certain amount of bits per second. So if the transmission speed is greater than the bits per second of the audio *there will be no quality difference between wired and wireless* aside from some latency. Most bluetooth devices now transmit at 345 kbps. An MP3 has a maximum bitrate of 320 kbps. This means there won't be any impact on the mp3s audio quality from being sent over bluetooth. Some other 'lossless' codecs such as flac use higher bitrates like 1411kbps, in which case it would be downsampled lower before being sent wirelessly. This may or may not reduce quality depending on the track. Most streamed music is streamed at 160kbps so for streaming services bluetooth will always support full quality. Sorry for the long reply.",
"Your pc or phone will bunch together a load of 'sound data' into a nice little packet and sent over bluetooth to your headset, hundreds or thousands of times a second. Your headset gets the data and reconstructs it back into the sound waves to vibrate a speaker and turn it into sound you hear Microphone is just exactly the same but the inverse. Is it better or worse? For the average listener it makes absolutely no difference. Sound doesn't require that much 'data' (or bandwidth) so it's easy to reconstruct almost perfect sound quality at the other end. A disadvantage of wireless headphones is that it takes time to bundle up the sound into packets, so sometimes there can be a latency with the sound that you hear. Not an issue for music, but watching a video you might see lips move out of sync to what you hear"
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jcy8xa | How are websites able to tell if their ads were blocked? | Technology | explainlikeimfive | {
"a_id": [
"g9482sy",
"g948wfp",
"g9496mr"
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"text": [
"Simply by noticing that when they request data from their ad provides it doesn't arrive. The process of getting something from the internet and displaying it on your website is a multi step process, it isn't all that difficult to detect if some of those steps went wrong.",
"An ad blocker like Adblock will allow the website you are wanting to visit and block things that are not a part of the web site. Third parties will want to post advertising and cookies that the Adblock detects as trying to load. It will block them before they are sent past the rendering of the site. How they detect it is because often those cookies and additional graphics try to load sometimes several times and isn't getting through. So it will try and send more to try and get through. The website sees this and now has detected you have an Adblock. In the days of slow internet speeds ( below 1mbps), you could easily see these ads trying to load and slow down the page from displaying. Today we have much higher speeds and you don't notice all this as much, sort of. Some sites just go overboard and push lots of ads for little content. This was the original reason for ad blockers, to block these ads so when you were on a slow internet you could still go about the internet.",
"One way is to serve you \"unique\" ads. The advertising server has one advertisement which they are set up to deliver when asked by many different names. For example the website might see that user \"Jack\" is accessing their site. They send Jack a page with \"advertisement-jack.jpg\" that points to the advertising server. That server probably isn't even run by the same organization as the website and has no idea who Jack is, they serve up \"advertisement.jpg\" no matter what is after the dash. They do remember it though. Jack's browser is looking through the page it was sent and sees the instruction to load \"advertisement-jack.jpg\" from a server known to be an advertising server. It blocks the ad and doesn't even ask the advertising server to send it. The website server sends the page and then asks the advertising server if they had any requests for an ad including \"-jack\"; if Jack is blocking ads then they won't have seen that and let the website server know."
],
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jd0dzt | What Exactly Is Happening When A Program On Your Computer Is "Not Responding?" | Technology | explainlikeimfive | {
"a_id": [
"g94l5uu",
"g94nl2e"
],
"text": [
"Programs interact with the operating system using a \"message queue\". When you interact with a program (click the mouse, press a key) the OS sends a message to the program through the program's message queue. After the program handles the message, it responds to the OS saying the message was handled. \"Program not responding\" happens when the OS is not receiving confirmation that the messages were handled. This can happen when the program is too busy to handle all the messages. This shouldn't happen in a properly written program - the part of the program that handles the messages should be separate from the parts that do the heavy work, so if the program is busy it should still be responsive.",
"Quite literally that: The Operating System is trying to send messages to the program and the program is not reading or responding to those messages. this can happen for a lot of reasons. The program might be stuck and unable to do anything. It might just be a bit busy and is getting a bit behind. It might be waiting on something or trapped in a loop so that it can't get to the message queue. It might even intentionally be ignoring the message queue albeit that is very rare for obvious reasons."
],
"score": [
18,
4
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jd16j6 | Why do ads on social media platforms load with no problem, while the videos endlessly buffer? | Technology | explainlikeimfive | {
"a_id": [
"g94q70l"
],
"text": [
"Usually for me its the exact opposite, so you have a false premise that this is just the same way for everyone. But I CAN answer the question in any case. The video on a site are hosted from that site, are using their bandwidth and subject to whatever issues anything else on that server has. The ads, on the other hand, are not coming from the site you are viewing them on. They are being stream instead from a completely unrelated ad server. So problems the affect the main sight won't apply to the ads and vice versa. As for the specific issues you are experiencing, that I do not know. For that you'd have to consult a subreddit dedicated to helping you diagnose technical issues."
],
"score": [
4
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jd271a | how does 8D audio make it sound like audio is moving around me? | Technology | explainlikeimfive | {
"a_id": [
"g9548vo"
],
"text": [
"8D audio is a marketing term for something called binaural audio. It's a type of surround sound that takes advantage of how our brains perceive sound in order to work with only a left and right channel. when we hear something that is in front of us, the sound reaches both our ears at the same time. But when something is off to the side, the sound hits one ear first (i believe there's other stuff involved, but this is the basics). Our brain times this lag and uses it to figure out where the sound is coming from. A sound coming from the right will hit our right ear before our left as an example. In 8D sound, the left and right channels have slightly different timing on them which tricks our brains into thinking the sound is coming from a certain direction. If your recording something, you can set up two mikes with the same gap our ears have between them. If you have regular surroung sound (ie 5.1 or 7.1) there's software that can turn it into 8D audio."
],
"score": [
5
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jd2kd2 | In glitter paint, how does the paint color not cover up the glitter and just turn it into gritty paint? | Technology | explainlikeimfive | {
"a_id": [
"g9529yx"
],
"text": [
"Paint is really translucent. In blending, layering, and with thickness (and painted over other colors in base capes and primer) is when it has an opaque quality. When flecks are suspended in the paint it’s close enough to to the surface that it’s visible. In addition it also adds the perception of depth as it suspends at differing levels within the paint."
],
"score": [
14
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jd37sv | How are space movies and shows able to simulate zero gravity? | Technology | explainlikeimfive | {
"a_id": [
"g9557by"
],
"text": [
"Early on it was done with thin wires which were able to support the weight of the actors, now it is more likely to be done with CGI."
],
"score": [
5
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jd9jov | Why is it we still get dozens of calls a day from scammers? Don’t we have the tech to tell a spoof number and prevent it from coming through? | Technology | explainlikeimfive | {
"a_id": [
"g97efat",
"g96pcdr",
"g96htno"
],
"text": [
"It's not a technical problem but a legal one. As long as it's legal this will keep happening. This problem hardly exists in the EU because there are strict laws about these kinds of things.",
"There are billions of potential phone numbers in the US, and they are very cheap for businesses to acquire and also to cancel, like a dollar a line or less per month. A scam company can cycle through dozens if not hundreds of new numbers every week, so by the time your phone company gets enough complaints/blocks for a single phone number to flag it as spam in their system, the scammer using it has likely already moved on to a new number.",
"Because spoofing a number has legit reasons. For example. A company could have thousands of employees and hundreds of phone lines. But sets, by the same technology that scammers use, so that all outgoing calls come from the company's main number."
],
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jdffsy | Why is the main hard drive always called C: ? | Technology | explainlikeimfive | {
"a_id": [
"g97piiy",
"g97pmgr",
"g97poe1"
],
"text": [
"It's ancient convention from the MS DOS days, most computers before harddrives that used DOS would have 2 floppy disk drives labelled A: and B:. When hard drives got released C: was the natural progression from there.",
"Because back in the day, your first drive, a boot drive, was removable media (A:) and the second removable drive for making copies of drive A:, is naturally, B:; leaving C: as the first mass media location.",
"Holdover from the original computer (pre hard drive) days where A: and B: were the floppy drives. A: was the default boot drive (and I believe is still dedicated to a floppy drive if you have one ). So, B: was the secondary floppy drive, used for data storage, making copies of A:, etc. Some systems had more, but it wasn't common because it wasn't needed or useful. So, when HDDs came along, they naturally got C:. Once HDDs became primary storage, the pattern was set so C: is still the first HDD So, basically, HDDs start as C: because \"That's how we've always done it\" *spellcheck is my friend"
],
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5,
4,
4
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jdi0wi | why would one hide his IP-address before downloading torrent? | Technology | explainlikeimfive | {
"a_id": [
"g988cmv",
"g9893zt"
],
"text": [
"It's a way to protect yourself from being tracked. If someone's watching your activity, and you give them the wrong IP address to watch, then it makes it that much harder for them to prosecute you or issue you a fine.",
"IP addresses are identifying information - they are typically assigned to a single connection for a single account. The owners of the content being torrented will often join the swarm, copy all of the IPs, and then send letters to the ISPs that allocated the IP addresses telling them to cease and deist. Your ISP may disable your connection or just hand over your information to them outright, leading to you being sued. For this reason, many people who torrent use log-free VPNs. This way, when the content owner gets an IP address, it is the address of a VPN server in a different country that has no legal obligation to comply with the cease and desist."
],
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5,
4
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jdj5vp | What is an IP rating? (eg. "IP68") | And is it required for a phone to be able to handle any amount of water? | Technology | explainlikeimfive | {
"a_id": [
"g98g2ub"
],
"text": [
"You can fund the meaning of the numbers [ URL_1 ]( URL_0 ) The first number is solid particles and 6 is Dust-tight . The second I liquid and 8 is \" Immersion, 1 meter (3 ft 3 in) or more depth \" the test time is at least 30 minutes."
],
"score": [
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/IP_Code",
"https://en.wikipedia.org/wiki/IP\\_Code"
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jdld5u | If voice recognition on our phones has been made so fantastic and accessible for free, why is it so shoddy on the PC? | Technology | explainlikeimfive | {
"a_id": [
"g98un7p",
"g99016g",
"g98uwnr"
],
"text": [
"I havent seen any voice recognition for pc. Most people just use Google home or alexa for that no?",
"I mean, what service are you using? This isn't a pc vs phone technology. Not all voice recognition services are created equal, just like any software. Apple, google and Amazon each have a solid platform but if you are using something not based on one of those three then you have your answer.",
"macOS uses the same voice recognition as iOS... so that’s not true there. For Android, voice recognition is done on a remote server, so can work just as well from any other OS, as it’s not the local computer that’s doing the work. As such, Chrome has the same quality of voice recognition on any device it runs on. However, it’s not free - the remote server uses that voice data for marketing and improving voice recognition tech."
],
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jdltub | how touch screen phones tell the difference between skin and random objects | Technology | explainlikeimfive | {
"a_id": [
"g98xhar",
"g991gdl"
],
"text": [
"Capacitance. Your skin allows a certain amount of freedom for the electrons in it to move around. Electrons are attracted to positive charges and repelled from negative charges - including each other - which means under normal circumstances electrons will tend to spread around a material to fill it evenly, so they're equally crowded everywhere. But in the presence of an external electrical field, they'll move away from one side of an object to the other side, making that side more crowded, and that will produce a measurable change in the electric field around the object. So basically, a touchscreen is creating an electric field around/through your skin, which induces the electrons in your finger to move, which the touchscreen can detect. Other materials will not have the same properties with respect to electron mobility, and that's how it knows the difference.",
"Because you are made mostly of water. Touch screens work due to capacitance, the ability to store energy due to an electric field. The screen creates a tiny voltage and looks for something disrupting it. Water is a \"polar\" molecule, meaning that it is slightly more positive at one end and slightly negative at the other. When placed in an electric field it will try to rotate, which takes a little energy from the source. Your screen's electronics can detect that. This also can work if you touch a good electrical conductor to the screen, since it acts kind of like a conduit between the screen and your fingers. Use an electrical insulator or just a poor conductor and it won't work. **TL;DR** - Because humans are skeletons enclosed in watery meatbags."
],
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jdqz9k | How are onion sites hidden from search engines? | Hey there :) I'm curious, how are `.onion` sites hidden from public search engines like Google, Bing, DuckDuckGo or Yahoo? Aren't all websites accessible online; even with Chrome? As far as I know, Tor keeps track of nearly all `.onion` sites but somehow the network is hidden from the public... I'm thinking of creating a minimal Tor-like clone with somewhat small onion routing implementation. Thanks in advance ;) | Technology | explainlikeimfive | {
"a_id": [
"g99yvef",
"g9aeus6",
"g9abrpl"
],
"text": [
"Because Google is a commercial company. Their algorithm includes the availability to access website - as has been seen by attempts to block The Pirate Bay, where search results invariably include an accessible proxy above the site itself in areas where the main site is blocked. A search engine where a result on the first page doesn't load for the majority of users will fail. Most users cannot access the Tor network. Therefore, it would be madness to include it in results.",
"Search engines only look for web sites on the World Wide Web. The Tor network is not on the World Wide Web. Therefore those websites do not get indexed in regular search engines. It would be trivial for a company like Google to crawl the Tor network and add sites to its index. But a) the sites are inaccessible to users without the Tor software running, so the links won't work for 99% of users, and b) there's not a lot of incentive to do so, and given the kind of content hosted on Tor there would be more effort moderating the results than any benefit they would get from having them.",
"Are you asking why it doesn't show up in search results, or why you can't access it through a regular, non-TOR browser? There's a massive difference and I really can't tell which question you're asking."
],
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6,
3
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jdqzmb | How does a buffer overflow work? | Technology | explainlikeimfive | {
"a_id": [
"g99xbjr"
],
"text": [
"When a program is running, its instructions are stored in the same memory as the data of that program. Everything is bytes, and those bytes are all in roughly the same location. The memory used to store data needs to be allocated by the program. For example, if you want to read and store the user's name, you'll allocate 21 bytes of memory to store it. Sometimes, a badly written program will attempt to store too much data into its memory. For example, the program mentioned above will now say \"enter your username (at most 20 characters)\", read a string from the user and store it into the allocated memory. However, the program hasn't made any checks on the length of the username yet. It just told the operating system \"read a string and store it into memory starting at this address\". If the user ignores the prompt and enters a 3000-character username, OS will use the next 3000 bytes of memory to store it. This may overwrite not just other parts of data used by the program, but it may also overwrite some parts of its instructions. A buffer overflow attack is an attack where the attacker notices such a bug and then feeds the program a carefully crafted input that will cause it to do something bad. Usually, the program that is being attacked runs with higher privileges than the attacker has, and the attacker's goal is to have the attacked program execute code the attacker provided, but with those higher privileges."
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jdr6j1 | Why can my white gold wedding band be used as a stylus? | Not sure how I figured it out, but I can used my white gold wedding band as a stylus. Works pretty well actually. Wouldn’t be good for swiping though. | Technology | explainlikeimfive | {
"a_id": [
"g99wf76"
],
"text": [
"White gold is conductive, which is the main method touch screens use to detect that something touches them. You can use any conductive metal as a stylus, since the screen doesn't care what exactly is being used nor does it know the difference. All the screen knows is \"There was some drop in voltage in this location. Register it as a touch!\"."
],
"score": [
13
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jdtbrj | What are subtypes and supertypes in databases? | Technology | explainlikeimfive | {
"a_id": [
"g9afzk0"
],
"text": [
"A supertype is simply a \"parent\" type of another database object, while a subtype is that database object. For example, if \"vehicles\" are your supertype, they might have subtypes of \"sedan\", \"truck\", \"van\", etc."
],
"score": [
3
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jduux7 | Types of cotton fabric | ELI5: how is it that so many fabrics that seem to be different can all be 100% cotton? | Technology | explainlikeimfive | {
"a_id": [
"g9amyls"
],
"text": [
"Thickness of fiber is one factor, then there's woven vs knit, fiber density (number of fibers per square inch) was the cotton combed to align the fibers before spinning into thread? How many plies/layers to each strand? Was it polished, dyed, dipped in a fabric stiffener/starch. Was the cotton all the same type. How long was the staple (the way the strands grew) all of these contribute to the difference between your favorite soft tee shirt and your new pair of jeans."
],
"score": [
4
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jdyljr | How did the Zapper for old NES systems know where you were aiming on the screen when playing Duck Hunt on those old TVs? | Seems like tech ahead of it's time to me. | Technology | explainlikeimfive | {
"a_id": [
"g9b4tc0",
"g9b4dul",
"g9bgkll",
"g9b4noo"
],
"text": [
"It’s actually a pretty cool thing of engineering. The zapper itself contained a light sensor at the tip. When you pressed the trigger the next frame of the TV would become all black. The frame after that would be mostly black except for a white box in the hit box of the target. If the gun detected light during this moment, it sent a signal to the NES which meant it was a hit. If you didn’t aim at the right place on the screen, then the light sensor wouldn’t have detected light well enough. Using a lens you can get it’s “pointing accuracy” to be a little better as well.",
"When you point at a duck and pull the trigger, the computer in the NES blacks out the screen and the Zapper diode begins reception. Then, the computer flashes a solid white block around the targets you're supposed to be shooting at.",
"Along with the actual answer, I'll add in why it doesn't work on modern tvs: input lag. Signal processing has added a delay to modern flat screen tvs that wasn't present in old CRTs, which synced with the console to display properly, allowing precise timing required. this delay means the sensor doesn't see the proper frames and the game cannot work. There has been work on zappers designed to work with modern TVs using camera imaging: [Here's a nice LTT video explaining why light guns don't work on modern TVs and how the new ones manage to.]( URL_0 )",
"There is a sensor on the zapper that detects the light level where you point it. So it knows if you are pointing it at a dark or light pixel of the screen. When you push the trigger button the screen flashes for one frame with white where the duck hitbox is on a black background. Due to the high refresh rate it is very hard to spot this by the human eye and can easily be interpreted as simulated muzzle flash. But this quick flash is enough for the NES to read from the sensor if you are pointing the zapper at the hitbox of the duck or not."
],
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