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e7guez | Why do all legitimate streams run almost half a minute behind their television counterparts? | You could be watching a 100m final but they've already finished on your TV stream where they're still in the blocks on your internet stream | Technology | explainlikeimfive | {
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"Modern video streaming protocols (e.g., Apple's HLS) require the player, when starting playback, to accumulate the video stream without actually playing it for about 18-30 seconds. This is needed for two reasons: first, player needs time to measure the speed of the network connection in order to choose the suitable quality of the stream. E.g., if the network connection is bad, the video will be streamed in a low resolution like 420p, while for a good connection an HD or even 4k stream will be selected. The second reason is that the player needs to make sure that the amount of buffering (\"the spinner\") will be minimal. So the player wants to have some of the video in it's buffer ready in anticipation that network connection can go off in the next 10 or 20 seconds. This is based on the assumption that people psychologically prefer to wait 10 seconds for the video to start rather than to watch a video that is stopping for \"the spinner\" and resumes again all the time. As a result of these precautions, live digital stream are usually behind the TV to allow this 20-30 seconds buffer.",
"i'll give you a placeholder answer that you can hold onto until someone who's worked with this technology at a lower level can speak on it. There is a lot of preprocessing that goes on with video, sending it too. You don't get sent raw video data of every pixel at every frame - which is why you can select the quality at any one point. This preprocessing didn't really exist for TV since the bandwidth is always there to send pretty much whatever the camera and microphone read from the world as-is into the air for your TV to pick up. This preprocessing can be put into analogy if you've ever worked on project based office jobs. You tell your manager what you think you can do according to a relatively conservative estimate, and in that you factor in many things which might not be related to you (in this case, it would be latency or server load from twitch or anything else that would consistently slow down packets from being sent, read, processed and spat out to consumers). We can deduce from this that the shortest common stream delay is probably that conservative estimate that most streaming services recommend (or sometimes, enforce)."
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e7jscl | What is the "TLS handshake" protocol that runs before you connect to a website? | I noticed it briefly before a page I visited loaded and I've never noticed it before. | Technology | explainlikeimfive | {
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"Essentially, there's a large number of cryptographic methods available, since we've continuously improved them over time. Your computer is sending which ones it would like to use. The server checks against the ones it will use. There's usually a discrepency because newer ones get added, older ones get removed since they're less secure, so the exact group is not consistent. They'll find the highest one they can use. Once they've determined protocol, both computers generate and exchange session keys using a special protocol that allows you to send something securely over an insecure medium. [This video]( URL_0 ) does a good job of showing what happens there."
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e7mwwy | How do the different names on video cards work? | and why are there so many? Like you can get the same card from EVGA, Gigabyte, NIVIDIA or MSI. They're all a 1080ti or whatever but made by different companies? | Technology | explainlikeimfive | {
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"The video card is the same but there are different models that have their own cooling solutions and plastic enclosures",
"All the video card names you’re referencing are brands of video card manufacturers. Just like there are lots of brands of TVs or even PCs all these companies are designing products to sell to consumers. When it comes to the central graphics chipsets there are two main manufacturers - AMD & NVidia. These two companies design the chip which does most of the main graphics processing on a graphics card, but there are other chips and components that also are needed to create a fully functional card. The video card manufacturers design their product around one of these main chips (e.g., NVidia 1080ti) and use whatever other parts they think will work well with them. When they sell them they make sure to tell us the main chipset part, because it’s the most influential part when it comes to graphics card performance.",
"Nvidia and AMD make the graphics chip itself, and provide reference designs for a basic version of the card. Companies like MSI and Gigabyte take these reference designs and make minor changes like outputs, RAM amount, bios, and flashy lights and fancy coolers. All these cards use the same architecture, and performance is generally the same. Quality may vary based on manufacturing processes and quality of individual components. The biggest difference will probably be the cooling system. An inadequate cooler can result in the GPU overheating, which will give you lower performance as the processor throttles down to protect itself. Apart from that, they're all pretty much the same card, and performance won't vary a whole lot."
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e7nyxp | In video games, why do the feet of characters appear to "hover" over the ground slightly? | In other words, why is it a challenge for game creators to have the feet of characters make direct contact with the ground instead of floating slightly above it? | Technology | explainlikeimfive | {
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"collision boxes, which are basically invisible 3d shapes that tell the game whether an object has a physical presence in the world (vs say a smoke effect which you should be able to walk through) hopefully line up exactly with the actual “skin” of characters or objects, are separate entities from the characters that you see. never designed a game before but i’d imagine it’s a case of wanting to be safe and not have the character model clip (go) through objects at the cost of things not always appearing to “touch”. not necessarily the most eli5 answer but i’m not sure how to word it more simply."
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e7om8m | What does night vision make some black clothing appear white? Additionally, why does some black clothing stay black? | Technology | explainlikeimfive | {
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"\"Night vision\" often refers to the capture of infrared light on a camcorder or binoculars. As Fleaslayer pointed out, those generally emit IR light before capturing it as it bounces back. But IR light is also emited by the sun and tungsten lightbulbs, for example. I've walked into clothing stores with IR cameras, and it seems that most commercially available fabrics reflect that part of the spectrum. In IR, they either appear white, or much more pale then they do in visible light. Leather is a notable exception. It stays black. Source: I practice IR videography."
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e7ptdq | why don’t all phone services send texts over the internet (like apple’s iMessage does)? | Technology | explainlikeimfive | {
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"The short answer is that they don't because they didn't originally. *Short Message Service*-messages, as they are called in the GSM standard among other more recent standards, is a technical feature offered in the communication protocol used to communicate to and from the phones. Internet traffic relies on one or several other technical substandards that are also offered in the communication protocols. From the phone operators point of view, a SMS is awesome. Because they have full control. The problem, if you wish, is that since they have full control, they also have pretty pricey business models. Or had, at least. iMessage, WhatsApp, Line, Facebook Messenger, Google Hangouts, Signal, Telegram and all the others are internet services that happen to be linked to your phone number. SMS is a phone network service that is offered to your phone number. It doesn't necessarily have anything to do with the internet. The idea is pretty much that if the phone plan has a pretty decent cost for data (and often there is a monthly allowance of sorts in the data plan...) it's cheaper to use the data plan for your messages than to pay for each individual message that you send out. But. Smartphones too must follow the phone network communication standard. They *must* be able to receive SMS. Which means that they all can. No matter if your grandma has a brand new iPhone 11 (or whatever the newest one is?) or if she runs around with a Motorola from 1996, the terminal has SMS reception capabilities. And probably sending capabilities too. It's also a pretty dumb thing if you compare an iPhone and an Android phone; Google has their text messaging app. Apple has theirs. They don't work well together. If you want to communicate with others, you have to first agree on which app to use for your communications. With SMS, you don't. You just have to know the phone number, and that's it. Which is why your phone falls back on SMS every time it tries to communicate with someone who is not on iMessage. Because SMS always works. If you typed in the correct number, the message will be received."
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e7q7hs | Are HDR movies edited in HDR? | Technology | explainlikeimfive | {
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"Not necessarily. Shot in HDR, probably but a lot gets thrown out somewhere in the pipeline. That being said ... There is an incredible amount of post production work that goes into media that can add color detail back in. Obviously it's best for the final product to have as much information inputted but after color grading, visual effects, etc. there is plenty that would be improved via HDR. Keep in mind HDR is mostly about a screens ability to not only give more granular levels of color but also do it all at once. Screens have to compromised somewhere whenever a detailed image is shown and HDR certified screens can handle it better."
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e7rfuy | What is Max pooling in convulational Neural network? | I had this question after reading this article that talked about how a convulational neural network worked - URL_0 'CNN approach to solve this issue is to use max pooling or successive convolutional layers that reduce spacial size of the data flowing through the network and therefore increase the “field of view” of higher layer’s neurons' Can someone give an Intuitive explanation of this concept(max pooling) and why Hinton says it's a big mistake? | Technology | explainlikeimfive | {
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"**What are maxpool layers used for?** You have a grid of 100x100 values that you want to feed into your convolutional neural network. You feed it into a convolutional layer with 8 filters. The result is a 100x100x8 Grid of values(or 98x98x8 depending on your configuration). As you can see, the data is getting more instead of less, which is contrary to what you usually want in a neural network. Maxpool layers are used to reduce the size of the layer after a convolution. **How do maxpool layers work?** A Maxpool layer will \"pool\" together a number of values from the input (usually a block of 2x2 values), then it will only output the maximum value of that block. So a 100x100 input will be \"split\" into blocks of size 2x2, resulting in 50x50 \"pools\". For each pool the maximum value is taken, resulting in 50x50 values. That is the output of the maxpool layer. **Why are they used?** The idea is that convolutional layer find \"features\" in an image, like a certain line or a pattern. A high value indicates that pattern is present, while a low value indicates the pattern is not present. By using maxpooling, you essentially throw away the data about patterns not being there, as you only care about the patterns that were recognized. Additionally by reducing the size it means that in the next convolutional layer after that maxpool layer, every value in from the maxpool layer \"represents\" 2x2 values. This is what they mean with inreasing the field of view. I cannot help you with why Hinton sees them as a mistake."
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e7sqw2 | How those drink machines that can give you a large array of drinks at fast food restaurants | work | Technology | explainlikeimfive | {
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"They have cartridges of all the different concentrated flavour syrups, which are mixed in with the base drink based on the users choice. They also report back the most popular flavours - this is why you've probably seen things like Raspberry Coke in bottles/cans in stores.",
"Did you forget the rest of your question? How they what?"
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e7umtz | when you update an application, does that application then take up extra memory equal to the size of the download? | Technology | explainlikeimfive | {
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"Not permanently. Usually part of what you downloaded as an update replaces stuff that is already there in the old version."
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e7v3e2 | Why mobile phones require pin after boot, even when fingerprints/irises/faces are registered? | Isn't the security the same? | Technology | explainlikeimfive | {
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"A pin is also used as an encrypt/decrypt key after reboot and the fingerprint is used as for ease of authentication only. You cant use fingerprint after reboot as the biometric info is stored in the encrypted state.",
"Fingerprints, irises and faces can be compelled, pin codes generally can't. For example, someone could knock you out with chloroform and use your finger to unlock your phone. Can't do that if it requires a pin code, so the security profiles are vastly different. That said, the general reason that it requires a pin on bootup could be to decrypt your phone. Even without a sim card, modern smartphones store all kinds of data in memory chips which is encrypted at rest in many modern smartphones. The reason the phone designers decided to request a pin at startup is likely a combination of both concerns. If they so choose, they could use your fingerprint as a decryption key, but it would be less secure."
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e7w2tk | what is going to happen when flash becomes obsolete? | Since Adobe is making flash obsolete. I'm confused with what is going to happen to all of the flash media that is online. Are all of the flash games/movies just going to be erased from existence? Or would you still be able to play them? | Technology | explainlikeimfive | {
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"You will still be able to use it, Adobe will no longer be working on it. DOS is obsolete but I can still boot up DOS 6.0 on an old computer my Dad keeps for some odd reason, and then spend all day playing Sopwith."
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e7wo35 | When two TVs in TVs same house are run through the same cable service, why does one seem to always lag behind the other? | Technology | explainlikeimfive | {
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"A modern TV contains electronics which decode the digital HDMI signal and then turn it back into a picture and sound. Unfortunately these usually introduce a delay, and on some models it can be a notable fraction of a second, and it's not a standardized amount."
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e7x3p8 | what's the difference between " URL_0 " and " URL_1 "? | I've seen both formats used to display a specific page on a website, and I'm curious what the advantages/disadvantages are of each. | Technology | explainlikeimfive | {
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"www.website/webpage is a page within a particular site. These pages are all themed the same and collectively tell one message. These are all covered under one standard SSL. URL_0 is a subdomain. These are typically used as a standalone to the primary website. These are often times used as landing pages for an ad, where the site owner is trying to acquire a lead (usually the contact information of a viewer). These are usually styled differently and can be used as a stand-alone. These are not covered under a standard SSL, and require a separate SSL.",
"Everything before the / is a house address; everything after the / is a book in that house. * \" URL_0 \" means \"look in the purple house, and bring back whatever book they left right at the front door\". * \" URL_0 /foo\" means \"look in the purple house, and bring me the book labeled Foo\". * \"foo. URL_0 \" means \"go to the purple house, then find the room labeled Foo, then bring me whatever book they left inside that room\". * \"foo. URL_0 /booga\" means \"go to the purple house, then find the room labeled Foo, then bring me the book labeled Booga from that room\"."
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e7xiyr | Why are naval and air speeds measured in knots but cars speeds are measured in 'per hour' speeds? | Technology | explainlikeimfive | {
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"Because you can easily measure a car's speed in miles per hour using information from the car's engine (information that relates to how fast the wheels are moving and subsequently how far the car is moving over time). Additionally, we drive distances that are measured in miles or kilometers, not nautical miles. Historically with ships you can't do that - there are a lot of conditions, like the sea state, strength of the wind, etc. \"Knots\" are called \"Knots\" because they literally... used knots in rope that would be fed into the water. One sailor would keep track of time, another sailor would let the rope into the water and keep count of how many knots passed through his fingers. The higher the count, the faster the ship. It was essential for navigation purposes to make adjustments to course / calculate the location of the ship. It wasn't until 1969 that the Federal Aviation Administration actually adopted knots as the official unit of measurement for aircraft. It's just easier for navigation since knots and nautical miles match up better with latitude and longitude readings.",
"Knots is a per hour speed. It measures nautical miles per hour. It comes from the old days of sail when, to measure speed, ships would literally use pieces of rope with knots tied in them to work out their speed. Hence the term knot.",
"Knots are superior for navigation. The statute mile is a totally arbitrary value loosely based on the marching rate of Roman soldiers; the nautical mile is 1/5400 of the distance from the North Pole to the Equator. If you have a map with latitude and longitude marked off in degrees and minutes, one minute of latitude is one nautical mile. A knot is simply one nautical mile per hour.",
"Navigators use nautical miles because one minute of arc on your sextant (one 60th of a degree) corresponds to one nautical mile on the surface of the earth. Since Mercator projection charts show degrees and minutes of latitude, it’s easy to turn sextant readings into distances on the chart. If you’re measuring distances in nautical miles, nautical miles per hour is the logical unit of speed. This unit of speed is commonly known as the knot, because it used to be measured by counting how many equally spaced knots ran out on the log line, a rope thrown over the stern, in a fixed period of time. Aircraft and ships still use these units and this terminology."
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e7xoc7 | Why does a video taken of a stationary object (with no moving objects) look different than just a still photo? | Technology | explainlikeimfive | {
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"text": [
"There are usually subtle visual clues like changing lighting, movement of objects in the background, slight vibration of the tripod, and even changing noise patterns in the video."
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e7y6x4 | When entering a card number via keypad on a phone call, how does the recipient know which digits you entered? | Technology | explainlikeimfive | {
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"Touch tones. Each number causes a tone at a specific frequency to be played down the phone line. The computer systems are programmed to recognise this and convert them back to the relevant numbers.",
"With my work we connect to a third party company when taking card payments - they intercept the tone of the number, the numbers input to our system but the tone on the call is silenced so our call recordings are safer",
"Fair enough. How about noise pollution on your end? I’ve never had to call a number like that in public but could outside noise affect it? Would the system recognize its being affected by outside factors? Sorry I have so many questions I’m very curious",
"Hey! I know this! The tones are pretty specific and are called DTMF (dual-tone multi-frequency. Each column and row of the keypad has its own frequency. When a key is pressed, the tones for the appropriate row and column are mixed creating a unique tone for that key. Only seven tones are needed for twelve keys. The receiver has a set of filters to discriminate the seven possible tones into row and column tones and thus deriving the key that was pressed."
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e7y9ja | Why haven’t Bluetooth video projectors been invented yet? | Technology | explainlikeimfive | {
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"Bluetooth simply doesn't have the bandwidth for video and sound at any decent resolution. Regular Bluetooth that doesn't have any of Bluetooth's 4 WiFi utilisation trickery has a bandwidth of about 3mb/s. It also has a relatively high error rate.",
"Bluetooth barely has enough bandwidth to support audio, and the audio is still very poor quality (less than an mp3). If you could send video through Bluetooth, it would be at such a low bitrate that the image would be almost unrecognizable (think early 2000s flip phone quality).",
"Bluetooth 4 can only theoretically do 25megabits/sec Max. It never does though. When it does transmit/receive at relatively high bandwidth, it's sporadic & not smooth. And also Bluetooth really really sucks. It really does."
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e80m4d | Why would a video of a still image take up less space than a video with moving frames? | I figured that the lines still have to be drawn every frame anyway regardless if they are the same or not | Technology | explainlikeimfive | {
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"Videos use something called [inter-frame compression]( URL_0 ) to shrink the videos. Instead of storing each frame in full, they store only some frames in full, and between them they store inter frames which only contain the difference from the last frame. Since a lot of videos have shots where the next frame is very similar to the previous one, this allows many inter frames which just have information about how to move and re-color a few chunks of pixels. For a video that's a still image, you could have a single frame, and the remaining video just be interframes that say \"do nothing\"."
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e81ftc | Why dont we have 1000v1000 multiplayer games? | Technology | explainlikeimfive | {
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"As I understand it, Essentially it's a problem of co-ordinating and distributing information. If you have 2000 players all in the same space, everyone needs to know where all the other players are, what they're doing, how they're moving, what projectiles they've set in flight, what THEY are doing, where they are heading, etc. This can amount to a sizable volume of data. Distributing and co-ordinating it isn't THAT difficult, but in order to prevent noticeable lag on they players end, it all has to happen unbelievably quickly. That's the tricky part. Not making it work, but making it work fast enough to be invisible and flawless. Remember, it's not just the speed of the pc/ console / servers that's a limiting factor, Telecommunications networks and geographical location also play a significant role.",
"Eve Online has suuported 1000's of players fighting in the same system. It starts to slow down to essential unplayability ( < 10% real time speed) past a certain limit, but 1000 - 1500 players in one place fighting is perfectly playable. To answer your question though, it's down to a couple of key things :- getting info about what everyone is doing to everyone else quick enough to avoid lag, and also calculating the game state on the server end based on everyones actions. It is very CPU intensive to do it in a timely manner."
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e82oi0 | If I have an SSD with 400MB/s Write speeds, should it take 2 seconds to transfer 800MB from a disk to it? | Technology | explainlikeimfive | {
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"Only if the other disk also has 400MB/s read speed, and whatever connectivity between the two disks you have supports this. For example, having two of these discs connected to your motherboard, you should be able to transfer 800MB of data in 2 seconds. However, if you have two machines, both with these discs, connected to each other over a network, the speed of the network may be a limiting factor in your overall transfer speed.",
"800MB across many files or a single 800MB file? Every file needs to be opened and closed while reading and writing. Generally a small number of large transfers is faster than a large number of small transfers."
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e84lp5 | How do they preslice hotdog buns? | Technology | explainlikeimfive | {
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"text": [
"[With a hot dog bun slicer]( URL_0 ) The exact method varies slightly. But it's almost always the buns on a conveyor belt, plus something cutty that doesn't go all the way to the bottom."
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e84u3u | Why are movie audio volumes so different from action scenes to talking? | Technology | explainlikeimfive | {
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"I feel ya man. I always have to have subtitles on because people seem to whisper the main plot :/",
"Center channel. Often neglected, rarely understood. I don't actually understand it either (really) just know it made a huge different when we got one. AFAIK It's where 95% of the dialog is sent out through and will make a night and day different in volume level normalcy. We don't even have surround, just a nice pair of stereo speakers (I'm a music nerd) and a decent center channel. No more going from whisper dialog to neighbor waking action scenes out of nowhere. Added bonus, when watching something like an event (think olympics) you can simply mute the center channel if you don't want to listen to narration/announcements, but still want the rest of the noise.",
"It's mostly not a technical limitation. Scenes are at different sound levels to evoke different emotions. The difference between the loudest and quietest scenes would be called the dynamic range. Sound engineers are probably targeting an audience in a theater with a professionally designed audio system, and working on the assumption that the audience has good hearing (which is hard to concisely define, but for any professionally produced piece, you can assume that *lots* of people listened to it and found it acceptable). Outside of these \"ideal\" conditions your results may vary. There are technical solutions to your dilemma. One, of course is to utilize subtitles, but that often creates a diminished result for people. You're more likely to want an audio compressor with makeup gain. The compressor lowers the intensity of the loudest scenes and the gain settings increase the overall volume. When combined you get an audio track with much less dynamic range, which means less volume changing and hopefully no waking up of others nearby.",
"Most of the time, this can be a result of an audio format your system is not decoding properly, losing the majority of the voice track. A better decoder (receiver) will address this more than additional speakers. However, sometimes it is just simply inferior track mastering, or levels intended for movie theaters rather than optimized for home playback."
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e84wl3 | . What is the belief to warming up your car for a few mins in the morning? Are there any benefits to your vehicle, or does it cause harm? If so, then why? | Technology | explainlikeimfive | {
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"Warming up your car gives the engine and oil a chance to come up to operating temperature when it is particularly cold outside. The oil does a better job lubricating once it is warmed up enough to thin a little bit,and this significantly reduces engine wear and tear at the piston rings, valve lifters, and other moving parts. The transmission fluid also works better close to normal temperatures, but doesn't usually warm up much from idling, and needs to be driven gently as it warms up. Shifts can feel rough when the transmission fluid is still cold. Modern cars with lightweight, aluminum engine blocks warm up pretty quickly, but old steel engines take 10-15 minutes. Carburetors also work much better once the engine is warm, so older cars without computer driven fuel injection can be difficult to drive before they warm up. My 1969 Pontiac can be so rough in the winter that it actually dies at stop signs if I don't bump the throttle a little bit when the car is cold. Once it warms up a bit it does fine. I try to warm it up until the coolant reaches normal range before driving it. The oil is a little behind the coolant in warming up, but by then it is close enough.",
"1. Traditionally, the carburetor needed to warm up to operate effectively, otherwise the engine would stall due to insufficient air supply. (This is no longer true with most modern automobiles.) 2. Colder metal is more brittle / warm metal is more flexible. As the engine block warms up, it takes a bit of time for temperatures to equalize, so you don't want to introduce a large pressure or sudden temperature change on your engine before it's gotten at least somewhat warm. Slamming the gas pedal of a cold engine can crack bits of metal (or heaven forbid, crack the entire engine block itself). 3. Until the engine has some heat to give, I've got none of that sweet, sweet heat to defrost my windshield with!",
"A quick search online brings in [several]( URL_0 ) articles that essentially say it's not really [necessary]( URL_4 ). The [EPA]( URL_3 ) and [ URL_2 ]( URL_1 ) say no more than 30 seconds is plenty, with one expert from Penzoil claiming that the time it takes to warm up oil in cold weather is milliseconds, not minutes. So it seems like, turn on your car, scrape it off if necessary, and you're good to go. The general consensus seems to be that anything else is just wasting fuel. This is all assuming your vehicle is newer enough to not use a carburetor, which seems to be early to mid 90s? Anything past that and you shouldn't have to worry about it."
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"https://www.energy.gov/energysaver/vehicles-and-fuels/saving-money-gas",
"Energy.gov",
"https://www.epa.gov/transportation-air-pollution-and-climate-change/what-you-can-do-reduce-pollution-vehicles-and-engines#dont_idle",
"https://www.accuweather.com/en/weather-news/experts-weigh-in-do-you-need-to-warm-up-your-car-in-cold-weather-2/433065"
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e86rad | Why are not all gloves touch screen friendly? | Technology | explainlikeimfive | {
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"There are different ways the touch screen itself works... The 2 main ones are resistive and capacitive touch. Resistive works of of pressure, you could use any glove you want. Capacitive uses your body or the stylus to complete a circuit to tell the screen where you pressed. So most insulators will interfere (rubber, plastics, things like that)",
"The screen creates tiny electric field lines adjacent to the screen. When you touch the screen your finger, the electrons and other charged particles in your finger react, and change the shape of the electric field. This is detected by the digitizer under the screen, and that registers as a touch. Your glove doesn't have any free charged particles that can interact with the electric field, and as such the screen doesn't detect anything - it's as if it was air as far as electric fields are concerned. The gloves that work with touch screens have some conductive substances, like tiny metal wires, in all or some of the glove. This allows them to interact with those fields in place of your finger.",
"Because most touchscreens now are capacitive type, reacting to electric change, not pressure. If your gloves are electrically insulating your body from the screen then the touch isn't detected."
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e86zu8 | Battery life | I just went out to buy some 9 Volt batteries because the fire alarm decided to be my alarm clock today and tell me, quite loudly, it was hungry and needed more batteries (/s). I replaced the battery and went to go pick up some more batteries for when the other fire alarms require replacement batteries, and I had thought, if those batteries stay in the package for an extended amount of time, will they still have the same amount of life in them as when i first bought them? Or will they lose power and life, even though they are sitting in a sealed package? | Technology | explainlikeimfive | {
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"Batteries slowly die even when in their package. I don't feel qualifies enough to explain why but I think it has sth to do with their internal resistance.",
"Lithium batteries contain a solution inside of them that changes form to release energy. Essentially when the battery is discharging the solution inside of them transforms into another state that releases electrons and creates power, and unlike single use batteries this solution can be returned to it's original form when you recharge it. You can think of it like a spring. When your using it it slowly spreads out and loses energy, and by charging it you compress it again. Unfortunately this process isn't perfectly efficient and it's thought that this solution can also react with the casing around the battery and turn it into a type of salt. The more times you use the battery (cycles of charging and discharging) the more of this solution turns into this salt and the less is left to store energy."
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e8741t | why do only some materials work on touchscreen, and what is in touchscreen gloves that makes them work? | Technology | explainlikeimfive | {
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"text": [
"The basic difference is conductivity + surface area. A needle will not work because it has very little surface area that can directly touch. A cotton glove will not work because it is not conductive. A glove with a bunch of flexible little conductive fibers WILL work.",
"Capacitive touchscreens you see on recent smartphones use differences in capacitance to detect touch. Your body is in fact a giant capacitor. If you touch the screen, the capacitance of your body adds to the capacitance already in the system and your smartphone detects \"Yay, capacitance has changed, someone has touched me!\" Pencils for example are not a giant capacitor. So to make touch work without the human body you have to use materials which mimic the capacitance of the human body. Conductable rubber works good. This material is then added to the fingertips of the glove."
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e888rw | Why are some keyboards able to register three inputs at once, while others can only manage two? | Technology | explainlikeimfive | {
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"A keyboard have far too many keys for each key to have their own sensor. It would just be too many wires and sensors to manage. Instead the switches on the keyboard are mounted in a grid matrix of wires where they connect the row and column wires together when pressed. The controller will activate a pattern of columns and observe the signals on the rows to figure out which keys are pressed. The issue is that if you press too many keys there is just too many rows that activates as all the wires gets connected together and there is no way to figure out which keys are actually pressed. Identifying two distinct keys is already a challenge and requires some interpretation of the signals. Identifying three distinct key presses is almost impossible unless you put resources into solving the issue. Some keyboards do allow three button presses as long as they are common patterns as they are able to arange those keys on the matrix in a way that makes it possible to distinguish them. Others allow three buttons as long as some of the buttons are control keys which may have extra hardware on them to make them easier to distinguish. Other keyboards will add extra hardware to the keyboard to make sure all keys can still be distinguished from each other even though this increases the cost of the keyboard significantly."
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e8conx | . What causes the echo I sometimes hear on phone calls? | Technology | explainlikeimfive | {
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"Your voice travels across the phone system to the other party, their phone's speaker plays the sound, then their phone microphone picks up on that sound and it is transmitted back to your phone as an echo. Speaker phones are notorious for experiencing this problem due to their loud speaker and sensitive microphone.",
"Not an answer, just expanding upon this issue, sometimes it’s not that. Sometimes it’s some other issue and I’m curious about this as well. Sometimes I hear my echo clearly, and it can sound echo-y or robotic, and I know it’s not the Microphone picking it up. I can hang up, call again any the echo is gone. What caused it in the first place? I’ve asked the other party if I’m on speaker before and after doing this and the answer was no both times, and somehow hanging up and calling again resolved the issue.",
"Follow up question: why it's this sometimes causes by something else than the physical layout of the microphone and speaker? Sometimes there is an echo in Skype (for example) but it disappears when disconnecting then connecting again, with no other change."
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e8dnlt | Why do ads load quicker then youtube videos? | Technology | explainlikeimfive | {
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"First of all, ads are the priority to load, not the videos. YouTube wants to make sure ads load. Ads are also sometimes pre-loaded behind the scenes in many cases, I can’t say if YouTube specifically does this all the time, but it’s common in advertising to do this.",
"If the video doesn't load, the customer waits. If the ad doesn't load, youtube doesn't make money. Youtube does this by storing the ads in accessible locations and likely pre-loading them to your device as soon as possible. When you're contacting Youtube's servers and saying \"I want to see this video\", it's like walking into an office and asking the receptionist \"Can I see [specific] employee?\" The receptionist calls the employee and might offer you a seat with a magazine while you wait. The magazine is the ad. It was ready right there in the lobby for you, while the employee was called and came to the front desk. Essentially, the ad is kept on the front end server in your country and maybe even your city, while the video is stored in a massive databank that may be half a world away and has to route to you. Then there's the fact that the video itself may be of much higher quality (fps, resolution, sound fidelity) than the ad itself. If you have a fast connect you probably won't notice because the video will be loaded enough to start by the time the ad finishes. If you have a slow connection, the ad is the #1 priority. Get that to the device before loading *any* of the video. That means your video might start with poor quality since your device was busy loading an ad instead of properly buffering.",
"There are less variations of ads compared to regular videos. So the ads get played more often than a specific video, and can be cashed on a server closer to you."
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e8do73 | Why is it such a common bug in video games for people to be launched up into the sky? | Technology | explainlikeimfive | {
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"It's a problem with the PhysX engine itself, which many games have used. Basically what happens is that when two objects collide, the algorithm figures out the \"force\" and tries to determine what happens. The \"force\" moves the objects according to the algorithm the engine works out. But there are thousands or millions of objects in a game, and when one of them isn't coded correctly, the engine doesn't know what to do with it, and so it imparts all that \"force\" into the object that struck it instead of distributing it correctly. This can cause the object to clip out of bounds, go flying out into space, or otherwise behave incorrectly. NPCs and the player are objects that can be affected by this.",
"It's an issue with collision detection. Put simply, when your character walks into an object, it might compute the character as going slightly into it. To compensate, they make the object \"push back\", typically just enough to undo how far the character went past it. This is what actually prevents a character from walking through the wall, ground, a tree, etc, the ground actually pushes them. Now sometimes you get bugs, and the character ends up inside an object completely without getting that push back (typically enters via a corner or something). But then he hits the edge and it computes a push back to fix their position, and pushed them out of the object. The problem is it was never designed to work with a character mostly inside, so it makes a force way too high, and that lends up launching them into the sky.",
"Basically, the physics engine gets confused. Physical models have the visual component you can see, and an invisible collision model that the physics engine uses to detect.... collisions. Sometimes, an error happens and these collision models overlap with the ground. This causes the physics engine to repeatedly calculate a lot of tiny collisions in a very short time. Internally, it can build up a huge amount of force bouncing back and forth. Eventually, the overlap is resolved, and the force is suddenly released in one direction. If the force is down, you don't notice, but if it's up, you get launched into the air. These kinds of bugs are entirely random, and are very hard to track down in normal testing environments. Most games will have this kind of issue at some point in development, but the worst issues get caught in internal testing. These random issues don't normally pop up until the game is released and players put the game through nearly every possible scenario.",
"Video games calculate physics using forces (that move things around) and collision meshes (that prevent things from moving through each other). In nearly all games, the two major examples of this are the force of gravity pulling things down, and the collision mesh representing the floor or ground, holding things up. However, because video game physics isn't perfect (it uses shortcuts to make the calculations faster), sometimes there are glitches. If something or someone doesn't trigger a collision with the floor for a short time, it will start to sink through the floor (due to gravity). When the game catches up and realizes that the object isn't supposed to be partway through the floor, it thinks that the object should instead bounce off the floor. So it propels the object upward."
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e8hln1 | RFID Systems, how do they work, how do you make them, etc. (What's the best resource to use to learn more?) | Technology | explainlikeimfive | {
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"An RFID tag is basically a storage device, it's a chip that can only hold a small amount of data, like in the order of 2 kilobytes. But the advantage of it is, it can be read wirelessly, and it's also powered wirelessly by the RFID reader (passive tag), though you can get powered ones that can transmit further if needed (active tag) but they obviously require a power source. They can also be reprogrammed, and some standards allow for things like encryption. Because of the small storage space, generally they're only storing data like unique identifiers or URLs, much like a barcode or QR code. Their use case is also pretty much the same, they can be used to keep track of stock in a warehouse, movement of freight etc. In commercial usage, the RFID reader will usually be connected to an enterprise management system of some kind and take action based on the system's requirements and business rules. For personal usage, one might use it for asset management, or home automation, though consumers would usually use NFC, a subset standard of RFID. That's the general idea, at this point you'd need to ask about a specific RFID system implementation to know more about how they work. Of course the exact usage is limited to your imagination. Nintendo's Amiibo and other toys-to-life products are one example. How do you make them, well it depends what you want to do. But the basic steps are: 1. Buy a bunch of RFID stickers/tags/chips 2. Affix them to the stuff you want to keep track of 3. Buy an RFID scanner (or use your NFC-capable smartphone) that can read and write tags 4. Download or develop software that does stuff with the scanned data You can find info about how RFID/NFC work just by googling, but the technical detail isn't really important, what you need to know first is, what are your requirements, what do you want to use RFID for? And once you've worked that out, search online for existing apps/software for that use case, or get to work developing your own. You probably don't want to buy the actual tags until you've worked out the rest of the solution first, because the solution might require a particular type of RFID tag."
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e8kscy | How come even a mild breeze can cause such loud noise on an outdoor phone call or video? | Can the mic be designed to eliminate it? | Technology | explainlikeimfive | {
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"The microphone cavity creates turbulence. If you just had an exposed microphone it would be much better.",
"Best way to explain it is like you’re blowing at the top of an empty glass bottle. You’re not putting much effort in the breath but the sound it makes is five times louder. The same thing happens with a cellphone’s microphone, there is a shallow cavity the air rolls over, the cavity catches it, making that awful tearing sound the other person in the other end of the phone call hears. The best bet to eliminate that noise is to use an omnidirectional mic and deadcat or a windscreen."
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e8m43u | Why are there DVD regions? If the players are what's different, then why is that even a thing? | Technology | explainlikeimfive | {
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"text": [
"It's so the the studios and the distributors can negotiate different prices in different markets without worrying about a (shady) supplier buying a bunch in one region and re-selling in another region.",
"It's not the players. Most companies manufacture all the players they sell worldwide in a single place. So there's no hardware difference between one sold in the US and one sold in Japan. The difference is in the software. After manufacturing, the players are split up into batches to be sold in the different regions. Each batch is then program-locked to only play DVDs coded for that region. Since they're only locked in the software, most DVD players can be \"unlocked\" in the same way. There are many websites (and probably at least one subreddit) where region-changing codes and instructions are shared. One can easily change a DVD player meant for the US market into one that works in Europe instead. Or, more commonly, a player that is \"region-free\" and should be able to play any DVD from any region."
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e8mtby | . How do smart phones detect if an original accessory is connected to the device. | For example, how can an iPhone detect if you're using an original Apple charging adapter and/or USB cable | Technology | explainlikeimfive | {
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"text": [
"The cable plug actually contains a tiny electronic chip that identifies itself as genuine. It isn't incredibly sophisticated but it talks back to the device and conveys information instead of it just being a set of wires."
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e8nssq | When a band is recording in a studio and everyone has on headphones, what are they listening to? | Technology | explainlikeimfive | {
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"They're listening to themselves. It's easy to lose track of just your own instrument/voice in all that noise, which means you could start playing slightly incorrectly and you might not notice, which could ruin a take. How awful it would be to tape a full song and then notice someone was one key off for half the song during the editing process.",
"They are listening to each other. Most of the instruments are mic’d in isolatiom so that the engineer can later mix each track individually which means that the band needs headphones to be able to clearly listen to what each other is playing. Aside from that you need headphones for instruments that dont require mic’s and are connected directly to the mixer. You also need headphones to listen to the engineer in the booth talking and giving instructions while the band is in the main room/booths. You might also need headphones for playback if you are overdubbing and for click track (metronome) if you record with it.",
"Well, think of it this way: let’s pretend we have a group of people sing happy birthday. They need to hear each other, so they sing the right notes and words at the right time. Otherwise, grandma’s saying “to you” while dad’s still on “birthday.” Also, when folks record music, we want to mix it; we want some things louder or quieter than others. Using the birthday analogy, maybe uncle has a voice that can sing the low part—but he sings a bit quietly. If we just put one microphone in that room, we can’t control how loud each voice is, or where the listener hears it in their ears; maybe dad sings off-key and super loud, and we can’t quiet him down, or the microphone is too near him. Plus, even if we record mom and dad at the same time with two microphones, you’ll hear mom faintly in the background of dad’s take, and vice versa. Change these family members to individual instrument parts—a singer, a rhythm guitar, a guitar with a fancy riff, a bass, a keyboard, a drum set, etc.—and you can kinda get why the headphones. Mixing is super nuanced, and people really want to balance how much you hear of each part, and what ear it’s in. Therefore, nowadays most tracks are recorded one-by-one (person by person). Even if a song has mostly computer-made sounds, the singer will wear headphones. So there’s your answer! Recording with headphones solves the paradox that: -We don’t want to hear one track in another track (i.e. dad in the background of mom’s), and we want to control them one-by-one BUT -The people need to play along to other tracks so they are in sync (i.e. grandma isn’t saying “to you” while dad says “happy”) I hope this makes sense! I’m largely self-taught at studio engineering, so people with more formal training might have a more nuanced or better explanation; but about thirteen years in, this is the understanding I’ve got."
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e8pzfm | - how does dungeons and dragons work? | Technology | explainlikeimfive | {
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"text": [
"Rolling dice is just a small part of Dungeons and Dragons; the rolling dice is used for the mechanics of the game, however the stories are like playing any RPG. While you fight or talk your way through the story, the main plot is always in the background some choices may drive the story in a dorection but in the end the story is already written.",
"The dungeon master (organiser) creates a plot line out of their imagination, the dice rolls are just used to see if the players spot a trap, defeat the skeletons, cast magic etc.",
"The key to a good game is a good dungeon master. He is the one who creates the game using basic tools like the Monster Manual (which gives the characteristics of different \"monsters\" you might encounter) and the Player's Handbook (which outlines the rules) From there the whole world is up to the dungeon master, though you can buy pre-made kits with adventures already lined out. The only time dice come into the game is when something has to be decided by chance, and even then the dungeon master rolls the dice in secret and decides whether to go by the dice or not. It's his call because he is in charge. Example: first you decide what sort of character you would like to pretend to be. Maybe you want to be a travelling minstrel, or a wandering priest. Maybe you want to be a thief, or a warrior. Once you decide on a character (and use the dice to see how good you are at things like wisdom and charisma andof course strength) then the DM (dungeon master) will tell you where you are and what you see. \"You're in a small village on the main street. It's market day and there are stalls selling various things, mostly food but also curios and tools.\" So you look around, maybe you find something interesting to buy. Maybe it turns out to be magical or contain a secret. That's up to the DM, he's running the story. You are oding your best to survive in a world you just got dropped into, and maybe find some adventure. Maybe a shopkeeper tells you a story about a hauted house at the edge of town and you decide to go look. Or you can head out of town and see what happens. WHat you do is up to you. Notice that so far you ahevn't rolled any dice since you created your character. Role=playing is just that, playing out whatever the DM has created in his imagination. A good DM has good stories and knows how to make the adventure interesting."
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e8qipx | How does satellite television know about my user account information? | How do satellite tv boxes (which have no internet connection) retrieve user specific data (Like my name, my current tv account balance, the list of channels available to me etc) considering that they can't talk back to the satellite due to the immense transmitting power required? | Technology | explainlikeimfive | {
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"Some boxes connect to the phone line for data packets to be sent. If u book an additional channel etc it send the signal back that u are receiving it and the operator adds that to the bill. Billing data is sent not received.",
"The satellite doesn't know which receiver can see which content, so it sends all of it to everyone over different channels. Channels are coded. In order to watch the content of a certain channel, the receiver needs the code to decode it. Think of that code as something you can buy from your TV provider and save it on your receiver. That code can be sent to you any possible way. The easiest way would be via TCP IP if your receiver supports it. It'd also be possible to send it to it via SMS. Another possible way would be to send it to everyone via satellite coded with your hardware's mac-adress which is known to your provider and your receiver, thus different receivers couldn't make sense of it."
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e8sway | What stops humans from fully studying the bottom of the ocean? Why does it seem like there is still much to be discovered? What prevents us? | Appreciate the knowledge! 😁 | Technology | explainlikeimfive | {
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"Pressure, temperature and light makes it a very tough zone to study. We can get a human in a tin can down there but not for long and it can be really dangerous. It means we can’t get out and collect samples by hand. Any organisms we drag up tend to die and change shape since their bodies are built for high pressure systems, not low. Organisms are extremely well spread out down there so even finding them can be purely luck. Sometimes we drop ‘laboratories’ which are basically robots we control from above. Down there they can record video and using arms can collect samples of plants and tiny organisms which might survive the journey back up.",
"Lack of oxygen for one and insane pressures. Every 33ft below increases by 14psi. That means 100ft down is 4x more pressure than our bodies are adapted to. Your lungs, for example, at 100ft below will contract, they aren't strong enough to resist the pressure so you have less lung capacity. Deeper still, your lungs collapse and you die instantly. Your blood pressure can't keep up, your heart rate slows, you're brain is starved for blood and pulls it away from your limbs. In some cases, the pressure differential causes blood to enter your lungs. Further, your eyes, blood, breathing, etc... are all dependent on pressure. You can wear a scuba tank and breathe, but that does no good when your body is being crushed under the weight of an elephant balancing on a quarter on every inch of your body.",
"It's dark and opaque and under very high pressure. That makes remote observation difficult and direct observation costly. It also suffers from the same problem the moon does: it's academically interesting but mostly barren, boring, and unprofitable. A good chunk of sea-floor surveying was done by petrochemical companies sniffing around for offshore deposits. Nobody else really wanted to pay for it.",
"There is no technical limitation to study it all because we have visited the Challenger Deep, the deepest point of the oceans. What has limited the exploration is that it is cost. The equipment that is needed to dive to the depth and the support vessel you need is on the surface cost a lot of money to operate. So you need a lot of money to do detailed surveying of it all. So you need to get someone to pay for it. There is not a, in general, a clear economic incentive for private companies to explore it all. So the alternative is governmental and them money that they are willing to spend on research is limited and you have to prioritize what you spend it on. Because there is not clear scientific question to answer but it is in other fields like space exploration. In space, there is a clear question and discoveries that the public is interested in so it is easier for a politician to spend money there than on deep-sea exploration. So the result is that we have better maps of the surface of the Moon and Mars then we do of our own planter because 70% is not hidden by water.",
"The whole \"we know less about the bottom of the ocean than the surface of the moon/mars/whatever\" is kind misunderstanding the issue, it gets repeated a lot because it makes a fun sound bite. On the one hand, we do have much better detailed maps of the Moon and Mars. This is because they aren't covered in kilometers of water. You can pop a satellite around the Moon or Mars (and we have) and just photograph the entire thing down to high resolution. You can't do that with the ocean, because you can't see through the water. The best resolution you can get is through sonar, and it's much less precise. On the other hand, we have a much higher amount of samples of the bottom of the ocean than we do of other planets, basically because we can drop scoops off of boats, or send down rovers. Of course the ocean is really big so we don't have samples from everywhere, but they are fairly representative. Relatedly, the ocean is full of life. The ocean's big, you can really only see what's near your sub, and it's not cheap or easy to get all the way down to the bottom. We've got samples from nets and trawls and sending rovers down, so we know a lot...but we also know there's a whole lot more out there which we don't know about. This contrasts with the moon and Mars, which don't have big biospheres full of life to study. There's just less to know in those places. So big picture, we know the large scale topography of the ocean but not the small details, because you can't see through kilometers of water. We have a good broad-sense view of the forms of life in the bottom of the ocean, but we don't know anything close to all the details, because it's hard to get subs and rovers down there to make observations and the ocean is simply enormous compared to the land. I mean imagine if your goal was to learn about life in Africa, and you could only do it using a single video camera for a few hours at a time, and Africa was 10x bigger. That gives you some idea of what we are working with.",
"Most simple quote I remember: \"we are sure there is loads of live down there, but everytime we come it runs away.\" That's one of the problems. Deep sea animals are very good at being deep sea animals, meaning they are good at not being catches by bigger predators. Also the conditions like temperature, pressure etc are very bad for exploring."
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e8tueb | Why does it seem that cell phone batteries go from 100% to 95% much slower than 10% to 5%? | Technology | explainlikeimfive | {
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"The battery percentage is based on a math magical calculation that can be +/- 15% correct. When you first unplug it there is less \"data\" for this calculation so it is more likely to be incorrect. Many new phone are programed to use less battery when your phone reaches 15-20% charge, but your speed and phone services may be affected by this \"resource throttling\".",
"[This]( URL_0 ) is what a battery discharge test looks like.",
"Lithium ion batteries need to be charged much slower as they approach full capacity. If this isn't done then there is a risk of the batteries exploding."
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e8v5wh | How did the 3D effect on Nintendo 3DS work without glasses? | Technology | explainlikeimfive | {
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"The Nintendo 3DS relied on something called a *parallax barrier* to achieve its 3D effect. Simply put, the 3DS' top screen is sliced into many columns, each one alternating between displaying an image for your left eye and an image for your right. In front of the screen is a physical barrier that, when the 3D slider is slid up, blocks the columns in such a way that each of your eyes sees a different set of columns, thereby producing a 3D image. The upper image [here]( URL_0 ) provides an idea of how it works. This is why you had to keep the device just so in front of your head, otherwise the effect would be lost.",
"For those who are unaware, there are even phones that have 3D cameras and 3D screens. I don't know of any new phones that do this, but six or seven years ago I had a phone called an Evo 3D. the 3-D effect work very well with the camera and the pictures look very good on the screen.",
"Also fun to know, the heads-up display of certain cars uses that effect. It's very neat to see that small display floating above the car's nose."
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e8ynd3 | How do Apple AirPods stay in sync? | How do the AirPods stay in sync with each other to make sure one isn’t ahead of the other? I know that this was solved with wires before, but with wireless earbuds like this how is it done? | Technology | explainlikeimfive | {
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"They communicate with each other and with the phone. They time each other, so they know how long it takes for a message to reach the other device. If one airpod receives a little bit more slowly, then the other will \"wait\" that amount of time, so they can stay in sync. Say, for example, that I want Tom in Vermont and Debbie in California to do something at the same time. I am in New York, so a letter to Tom takes 2 days to deliver, while a letter to Debbie takes 5 days. I send Tom and Debbie their letters, but I tell Tom to wait another 3 days while Debbie's does not include a \"Wait\" instruction. Now, both will do the action I asked them to on the same day. The same happens with your wireless earbuds. Of course, the difference in sync is measured in tiny fractions of a second instead of days, but the same principle still applies."
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e8yqxw | How does gravity work in video games? | Technology | explainlikeimfive | {
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"Depends on the game's physics engine. In source-engine games like team fortress or counter strike, players are essentially attached to the ground when it goes up and down. When they leave the ground, they accelerate downwards based on a number (which can be adjusted in the console) until they hit the ground again. Usually, acceleration is recursive. This means that every physics tick, speed downwards increases by the same amount. In some special games, gravity may be predictive, in the sense that the game calculates an arc for you to follow beforehand and then moves you along the arc. One such game is Kerbal Space Program.",
"Every thing is checked to see if it meets a few parameters (ex: it's actually tagged to be affected by gravity and/or physics (sometimes termed \"is a physics object\"), it's not already resting on the ground or another object with collision detection) Then if it meets those checks, it adds a predetermined negative value to that object's \"y velocity\" property (with \"y\" being the up/down axis) So for instance, let's say that you have a jump button that launches your character into the air with a velocity of 50 pixels per frame, but your gravity is set to 10 pixels per frame. Frame-by-frame, it will look something like this: Frame 1: You move 50 pixels up Frame 2: You move 40 more pixels up, to a total height of 90 pixels from the ground under you to the bottom of your feet (ish) Frame 3: 30 more pixels up, total of 120 pixels Frame 4: 20 more pixels up, total of 140 pixels Frame 5: 10 more pixels up, total of 150 pixels Frame 6: no more upwards movement Frame 7: 10 pixels down, now you're only up 140 pixels off the ground Frame 8: 20 pixels down, only 120 pixels up now And so-on until you hit the ground or another object that will stop your progress. (because I forgot but can't be arsed to re-write this) You will also have terminal velocity variable that gets set, and the additional step that after the calculation, if your velocity would be set to the terminal velocity, you stop accelerating. Other collision detection might happen; for instance if you're playing a Mario game and you jump on an enemy, instead of stopping you might get your Y velocity set to some fixed positive value at the end of the collision detection, so you get an extra hop, and it could be a bigger hop if you hold down jump."
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e90jv3 | Why are people less concerned about installing anti-virus software on cell phones, even though they access the internet just as much, if not more, than computers? | Technology | explainlikeimfive | {
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"Because it's not windows. Linux (which fundamentally is what Android is) with SELinux in enforcing mode is just a lot more secure than Windows on the desktop.",
"Phones use different operating systems that were designed with security in mind. That means they're very hard to infect compared to a regular computer. By default they can only install apps from the official app stores, which are being monitored for malicious apps by Google and Apple, and apps are limited in what they can access.",
"Android phones, and iPhones, have a much more tightly controlled ecosystem. Most of the viruses on Windows didn't happen because you just navigated to some website - you were either convinced or tricked into downloading and running something on your computer. Sometimes this was as simple as advertising a program that you might want to use, and installing malware along with it. Antivirus was necessary to scan all this untrusted stuff people were downloading. Androids and iPhones both have standard repository, run by Google and Apple respectively, which validate the applications you get. Developers go through an approval process before they're allowed to publish, and both companies scan binaries just in case. This is not perfect, and there have been major cases of malicious applications published to both app stores, but it's a lot better than literally everyone in the world being able to install stuff on your phone. While there are some systems that are more or less secure than others because of what they allow users and programs to do, this is the main reason, and is why Windows has also translated to a model where software is installed through a central repository."
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e90nlw | How does google photos recognize my baby pictures? | I just uploaded my baby pictures to google photos and it immediately put them into my face’s photo album. My friends can’t even recognize me as a baby so how did Google Photos? It’s so cool! Would love to learn more about it. | Technology | explainlikeimfive | {
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"The same way it can distinguish your friends from you. Or your dog from your baby. It scans the photo and compares it to a large large pool of already identified images and decided what its most likely to be. Big brother is watching and it’s very smart 👀"
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e912up | How is cellphone data made and distributed? | Technology | explainlikeimfive | {
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"If you're referring to the thing that cell service providers call \"data\" with regards to data plans it isn't made at all. Rather data in this case simple refers to how much information (in megabytes or gigabytes) you phone has requested that the cell towers send to your device (over a monthly period or something). Specifically data is information that does not use the channels for sending voice or text messages and usually is data requests for information from the internet. There is no finite resource pool of data that might run out. Its an artificial limitation on usage to prevent users taking up too much bandwidth, which is a true finite resource at any given moment. Cell towers can only talk to so many devices at a single time, and each user talking or requesting data takes up a piece of bandwidth while their voice is being transmitted or data sent/received. Once they are done, their \"spot\" in the tower communication queue is released, ready for someone else to use. All major upgrades 2G - > 3G - > 4G - > 4G LTE - > 5G etc have been more and more creative ways to manage bandwidth as more and more users try to request more and more data simultaneously through the network.",
"What do you mean by cellphone data? The programs on phones? Text messages? I'd be happy to answer your question if I knew specifically what you're asking."
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e943rx | The difference in the algorithm that separates 'top' comments from 'best' ones. | Technology | explainlikeimfive | {
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"text": [
"I assumed top is raw votes (up-down) and best is a composite of high raw votes and a good (up vs down) ratio."
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e98i2p | 1 TB Micro SD Cards | how is this even possible, especially when not that long ago 100 MB was a lot of storage | Technology | explainlikeimfive | {
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"There's an observation in technology called \"Moore's Law\", which states that transistor densities on chips will double approximately every 18 months. Computer chips are just large collections of transistors, and SD cards are just another form of computer chip. So, we can expect flash memory storage densities to nearly double every 18 months. If 1TB is today, then 3 years ago 256 GB would be State of the Art. 3 years before that, 64GB. 3 Years before, 16GB (2010). On top of that, flash memory had a huge jump in density with the development of 3D NAND, which builds the memory in three dimensions, rather than just a two dimensional plane of transistors. This allowed Flash memory to achieve a higher density of data per square inch than hard drives for the first time. In 2016, companies were reporting lab tests of 2.77 TB/square Inch."
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e9a017 | how can some websites “trap” the user to their homepages when pressing the back button, but others take you right back to the search page. | Technology | explainlikeimfive | {
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"There's an html element called a redirect; essentially if you make a page that immediately redirects you, your back button history will look like this, in descending order from most to least recent * Current Site * Site that redirects to Current Site * Google So if you *just* hit back, it takes you to the redirect site. The trick is to double-click back so that it takes you back to Google through the redirect site, or in a more general sense, right click the back button and click google out of there. Now, if you chain redirects in certain ways you can make it almost impossible to *just* click back. Some browsers have a built in \"too many redirects\" feature that will stop the browser after a certain number of redirects, but often they don't cover all the ways a redirect can occur, and the feature is most useful if you're working on your own site on the server-level, trying to get a redirect for a legitimate purpose, and not getting infinitely-recursive redirection due to an oopsie.",
"They do this sometimes intentionally, but usually accidently or as an accepted consequence of the way they handle links into their site. For example, if I run some ads I want to know what ads people are clicking on so I make a landing page that does nothing more than record what ad was clicked on (known at the time of the click and transition between ad-page and landing page (or site), but lost after that) and then redirect the user to the home-page. That means that when the user then clicks on the \"back button\" they are brought back to a page that did nothing more than redirect them to the homepage. So...if the page one-back from where you are redirects you to where you are, then...the back button doesn't work very well :). There are ways a friendly developer would prevent this."
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e9aoju | Why are CCTV cameras such low quality when even the cheapest video cameras are a much higher quality? | Technology | explainlikeimfive | {
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"Storage. The issue with security cameras isn't taking the video, but storing the footage. Yeah, you can film in 4k, but at 375MB for 30 fps for 1 minute x 60 minutes/hour x 24 hours/day = 270 GB/day x number of cameras. If you need to retain video for 1 month, that's \\~8TB per camera. Drop the resolution, drop the framerate and you reduce your storage needs immensely.",
"Among other reasons, CCTV cameras have to record 24/7, as opposed to the few-minutes-a-day that cheap video cameras do. Because of this, they record at a lower quality in order to use less storage space, since recordings are generally retained for a while.",
"I work in this area and wondered this myself before I worked with it. Many stores setup their systems before they open for business. This involves tall ladders or scissor lifts to install the cameras. This is not something that is easy(or cheap) to do once a store is opened. Yes, this depends on store hours. Not all cameras are IP based. Many are NTSC(coax) and the resolution isn't that high(nowadays). Many security systems run for years without issues. The recording unit's hard disks might fail but the cameras(in my experiences) work much longer. FYI, there are still systems running today dumping to magnetic tape. If it works, why not. So this means the cameras that were installed at the time might not even be top of the line at time of purchase. It could be a budget reason or the store was provided with this equipment, end of story. There are more details but this is the gist in my experiences. tldr; not easy/cheap to upgrade and cameras are way older than what you can get on amazon for $100 today."
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e9c0gg | A couple of decades ago we had 8bit, 16bit, 32bit and 64bit gaming consoles. Is there an equivalent "bit" that we're at now? | Technology | explainlikeimfive | {
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"We are still at 64 bit. In this case these numbers basically mean the space available to the computer to work in. 64 bit has more addressable memory space than 32 bit does. - 16 bit = 65,536 bytes (64 Kilobytes) - 32 bit = 4,294,967,296 bytes (4 Gigabytes) - 64 bit = 18,446,744,073,709,551,616 (16 Exabytes) You can see from above modern consoles need more than 4GB but are ages away from needing more than 16 Exabytes.",
"The main reason we are still at 64 bit is that as you increase bits, you increase the number of possible values exponentially (with base 2 because binary). You would think that going from 16 bit to 32 bit doubles possible address values, but it doesn’t. It is way, way more. Every bit you add doubles the value. So, if you wanted to double the number of address values in a 16 bit CPU, you would only need to have a 17 bit CPU. Because of the nature of exponential functions (they grow very quickly), the jump from 32 bit to 64bit is so large that it is going to take a very, very long time before we reach a limit. 32 bit was already approximately 4GB of usable memory. Now imagine doubling that 32 times. Not really an easy concept to ELI5, since you sort of need a good understanding of binary and some mathematical knowledge.",
"They had 128 bit. However it is diminishing returns. Our current processors are either 32bit or 64bit. The bit wars ended"
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e9cbax | Why, when buying a new product that runs on a rechargeable battery, is it recommended to fully deplete the battery before you charge it? | Nearly every battery-powered piece of tech seems to carry this instruction upon purchase. But it never made sense to me why it makes any difference how low a battery is before you decide to charge it. | Technology | explainlikeimfive | {
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"Fwiw this has not been the recommended practice for a long time. Older nickel cadmium batteries had a property for which this is useful however fully depleting modern lithium ion batteries is not recommended and can be harmful to the battery. I know that doesn't answer the question but figured out was worth knowing"
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e9dvse | how does the Face ID on my phone recognise my face in low light but my selfie camera just shows up as pitch black? | Technology | explainlikeimfive | {
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"text": [
"It generates light in a wavelength humans can’t see. The Face ID system fully illuminates your face with infrared light, then interprets that reflected light. There’s a separate IR emission diode beside the front-facing camera and speaker (there may be more than one).",
"FaceID on the iPhone uses infrared lasers to light up your face, but you probably can't see it. The selfie camera doesn't have any lights."
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e9g9jo | When one light on a strand of Christmas lights goes out, why do all the lights after it in the strand quit working as well? | Technology | explainlikeimfive | {
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"They are wired “in series” such that the electrical output of the first lite is wired directly to the input of the second and so on. If one light burns out then the path is broken. No way for the electrons to flow into and out of the string.",
"Think of it like this. Tie a string around a rock. Then hold the other side of the string in your hand and let the rock hang. Then take some scissors and cut the string. No matter where on the string you cut the rock always falls. The bulbs are wired together in one circuit. For electricity to flow the circuit must be complete. If any bulb breaks the circuit is broken and electricity cant flow so all the bulbs turn off. This is called being in \"series\". Only one path to flow from start to finish. If the bulbs were wired in parallel it'd be like tying multiple strings to a rock. Then hold them all in your hand. Cut one string and that string falls but the rock still stays because it is being supported by the other strings. Bulbs wired in parallel if one bulb breaks the rest stay on because electrical flow to those bulbs is not disrupted. The issue with this in Christmas lights is you have 200 bulbs on a string if each bulb has it's own wire then you have 200 wires going down the string, which would be very big and heavy and expensive."
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e9gyjc | Why is microSD cards affordable and have high capacity of upto 1 TB and very small compared to SSD and HDD? | Technology | explainlikeimfive | {
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"Micro SD is really good at being small, but not great at being the things a typical SSD or HDD is good at. Most notably, the microSD isn't good at doing lots of things simultaneously, or in queue (quasi-simultaneously). If you think of the uses of micro SD it's usually just _storage_ on devices that use that storage for one thing at a time. For a SSD you are running lots of applications at the same time, or maybe you're a server handling thousands of nearly simultaneous web requests. The capacity to read and write rapidly and efficiently and in parallel and buffer large amounts of data is not something a microSD card is good at.",
"The size is more based on the usage. MicroSD cards are designed for small electronics, stuff like phones and cameras. SSDs and HDDs are meant for laptops and desktop computers. They don't need to be as small, they're for larger electronics. This makes them cheaper (the smaller something is the harder it is to make) and allows SSDs to be faster and use better memory management than a MicroSD card. It also allows them (HDDs in particular) to have a lot more storage, you can't get an SSD or HDD that has 8 gb of storage while you can get a microSD card that small. As for affordable, we've gotten really really good at making small transistors for really cheap. But that's also true for SSDs and HDDs. MicroSD cards are actually pricey compared to the others (once size stops being a factor). Here's the cost of 1Tb of memory. MicroSD: $250 SSD: $90 HDD: $40"
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e9j9a4 | How does school computer return to it's "default" state when shut down the Computer? | Technology | explainlikeimfive | {
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"Windows has a feature called mandatory profiles that do not allow saving of settings or changes to the desktop. Another way is a through an application like DeepFreeze that restores everything after a reboot. URL_0",
"Depends in the setup, but in many cases those computers arent actually running windows. They're hosted by a server that is virtually sectioned off. So all the computers are independent, but all are simultaneously controlled by the server. To reset, the server basically just closes a session and then opens a new one."
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e9o54v | Why we can recover files after deleting them from HDD/SSD drives? | Technology | explainlikeimfive | {
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"text": [
"Deleting is more like removing the index card that tells you where a book is in the library. The book is still there, you don't have a record of it or where it was on which shelf, but that book will remain there until you use the shelf space for something else instead. If someone looks through all the shelves though, it will take a long time, but they can still find the book where you left it. If you want to get rid of the book, you need to shred it, so that there's nothing but random paper scraps where it used to be on the shelf.",
"When you delete something off of a HDD or SSD, you aren't actually erasing it at that point. If you were to imagine your HDD as an apartment building, all of the tenants are like your data. When you delete a file, you're not actually evicting the tenant, yet. By \"deleting\" it, you tell the computer \"This space is available for someone else to move in\". When you download something else, it can replace the space that you've \"deleted\", overwriting the data you previously deleted. However, if this information hasn't been replaced by something else, you can still recover the information because the \"tenant\" hasn't actually been evicted yet, the computer just thinks that there's free real estate there for something else."
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e9pzvi | If a Stealth Fighter battles another Stealth Fighter, will it turn into a WWII like battle where each pilot has to rely on eyesight, since radar won't pick up the other plane? | Technology | explainlikeimfive | {
"a_id": [
"faklkjf"
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"text": [
"No, there are a number of technologies which can see stealth aircraft. Stealth aircraft are usually stealthy only to microwave radar."
],
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3
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|
e9qxqi | How does a flashy green light on my watch measure my heart rate? | Technology | explainlikeimfive | {
"a_id": [
"fakujt2"
],
"text": [
"Similar to many other wearable fitness trackers, the Apple Watch relies on green LED lights for a method called photoplethysmography (or PPG). Because blood absorbs green light, and each pulse brings a spike in blood flow, determining heart rate is a matter of measuring the changes in green light absorption. [article]( URL_0 )"
],
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"https://www.macworld.com/article/2911939/how-the-apple-watch-heart-rate-sensor-works-according-to-apple.html"
]
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|
e9t60k | why do servers run most applications in virtual machines instead of a single shared space? | Technology | explainlikeimfive | {
"a_id": [
"falerpt"
],
"text": [
"VMs are much easier to backup, restore, clone, and generally manage than physical boxes. Imagine your company has a bunch of applications, web sites, databases, and tasks that require 10 servers to operate it all. If they were all physical boxes you'd need complete sets of hardware, power supplies, ethernet connections, physical storage drives, etc. Each of those becomes a point of potential failure, and to backup/copy any of them you'd need to perform those tasks piece-meal. By virtualizing your servers on a single VM host, you have a single set of hardware with all your individual servers managed virtually. You can easily take software snapshots of your machines, rollback to previous images, copy/clone machines, spin up new temporary machines for short-term projects, and delete them when you don't need them (rather than have an inventory of old useless and/or outdated hardware in a storage room). It's also easy to just add another blade of storage media to a VM host, or increase one set of hardware specs should you need to expand your data server needs in the future. tl;dr: scalability, ease of maintenance, and data integrity."
],
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4
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e9v7zi | How do MRI and fMRI work, are they used simultaneously? | Technology | explainlikeimfive | {
"a_id": [
"falyatk",
"famc0ld"
],
"text": [
"Your body is exposed to a strong magnetic field, it forces all the protons to align with it. You are then exposed to a radio pulse which knocks the protons out of alignment. Sensors then measure things like how long the protons take to realign and how much energy they give off when they do so. Different body tissues respond differently and were able to differentiate between them and draw a picture of the body. An fMRI (functional MRI). Is a special type of MRI that tracks blood flow in the brain. This allows us to learn which parts of the brain are used to do stuff and find brain damage. So you might be asked to write a sentence while getting an fMRI and that will tell us which parts of the brain are working really hard to do this.",
"Allright, here is my ELI5 attempt! * Every single cell (and smaller) in your body is a little bit magnetic. * Because they are so weak they all point in random directions, and it looks like [this]( URL_0 ) * Now we place you in a magnet, and every mini-cell-magnets aligns to the magnetic field (like [this]( URL_1 ) or [that]( URL_3 )) * When we turn the magnet off, all the mini-cell-magnets return to random directions. * BUT some cells do it slower than others! * If you quickly take a photo in that time, you see something like [this]( URL_2 )! ^(note: I took a lot of shortcuts, e.g. its isotopic atoms not cells. But I think my 5 year old nephew would be able to understand this while staying close to the principle.)"
],
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"https://raw.githubusercontent.com/tomduck/electrostatics/master/images/dipole-vectors.png"
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ea0lgi | How come some video games end up bad even with testers and QA people? | Technology | explainlikeimfive | {
"a_id": [
"fan2dlu",
"fan2cqb"
],
"text": [
"Usually extremely tight deadlines and not enough budget. Games are an incredibly complex thing to make and when you fix/implement one thing, ten things break. Combine that with execs breathing down your neck with impossible deadlines, employees being stressed and terrified, etc. some games are doomed from the beginning.",
"What do you mean by \"bad design\"? If you're talking about about the design/concept of the game then that is subjective. \"I don't like Metroidvania games so Metroid has bad game design\" isn't a valid argument. Now, if you're talking about how does a game end up with bugs and glitches? First, it's almost impossible to tell with limited testers everything that will happen. I remember when a new raid would come out in Destiny the devs would always say that it's played 100x more I'm the first hour of release than in the entire testing process. There is just not enough resources to try every conceivable scenario. As for known bugs, a Dev team will often have a \"punch list\" which is every known bug, glitch, issue in the game and it will be prioritized. They usually have a \"cutoff\" where everything before the cutoff MUST be fixed before launch and the rest is something that isn't game breaking and will only be fixed if time and resources are available. If they fix the big stuff in time for release but a few small items are still there they will ship it and fix it later if they become bigger issues. The other scenario exists usually in a bad business environment. This scenario is where the release of the game takes precedence over any known glitch. As long as the game is complete in terms of story/playability it will be shipped no matter the bugs. In that case they likely didn't have the time and resources and instead of spending the extra they just decided to ship it as is."
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|
ea51bo | what is lambda architecture (big data)? | Thank you! | Technology | explainlikeimfive | {
"a_id": [
"fao12hr"
],
"text": [
"Lambda architecture is a data processing technique for large quantities of data (Big Data) that uses a hybrid approach with batch and stream processing. There are 3 basic layers: **Batch**: Where the data is stored. Both manages the master dataset and pre-computes batch views. **Serving**: Forwarded from the batch and stream (speed) layers as batch/near real-time views. They're indexed so they can be queried in low-latency. **Stream**: Handles the data not delivered in the batch view due to latency. Focuses on recent data so users can adjust decision making and respond based on current views/trends. The main benefits are business agility, lack of server management, scaling flexibility and availability."
],
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3
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ea7u7e | What makes one CPU faster than another CPU? | Technology | explainlikeimfive | {
"a_id": [
"faogh23"
],
"text": [
"Other than the speed of the clock ticking (the GHz number), two main differences are how much it can do concurrently (in parallel), and how much ultra-fast \"cache\" memory it has. Both of these require more transistors, which drive up the cost of manufacture."
],
"score": [
5
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|
ea9gk3 | How can computers solve algebra without dedicated hardware for it? | Technology | explainlikeimfive | {
"a_id": [
"faouxm6",
"faopb45",
"faop9j8",
"faoqcbc"
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"text": [
"One of the fundamental concepts of computer science is that, with some caveats, any general-purpose computer hardware can be programmed to do anything any other computer hardware could. Practically speaking, there are cases such as graphics cards or sound cards that are designed to do perform large amounts of specific calculations more efficiently than a general-purpose processor, and then there's quantum computing which seems to be able to do certain tasks astronomically faster than traditional computers, but in all of those cases there's still nothing stopping any old processor from doing those tasks, it'll just take longer. In the case of, say, breaking cryptography, that might end up being billions of years longer, but things like that seem to be the exception rather than the rule. The bottom line is that there are very few situations in which you *need* dedicated hardware to do something.",
"I'm not sure i understand your question. What do you mean by \"dedicated hardware\"",
"By doing it in software instead. The programmer assigns various symbols (numeric values in memory) to represent the various algebraic items.",
"The same way humans do algebra. Algorithms utilizing general purpose hardware."
],
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eaafop | Why can't CPUs merge cores? | So this is probably really stupid, but why, for a company such as AMD, cant they make a CPU similar to the 3970x but with 8 or so big cores with improved performance? I keep seeing insane core counts from them, but I don't quite get why they can't make really good single-core performance. | Technology | explainlikeimfive | {
"a_id": [
"faow49z",
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"text": [
"There's a whole host of reasons, heat production, physical limitation to addressing, bandwidth to each core, etc. Basically, if each core has its own addressing, it gets it's own data pipes, its own RAM, etc. One giant core would still be limited to what a single core could address, you'd also run into limits of thermodynamics. Power consumption would be off the scale, and there would be bottlenecks all over the place.",
"If one has a big house and multiple cabinets and kitchen appliances but only one person (thread) then that takes time to process serially in length versus a team of people (multiple threads). A small house and kitchen cannot fit many people walking about either, which goes to the physical traces of people routing to needed parts of the house. Then there is the agreed layout and remembered organization of tools and ingredient access (data storage and memory addressing). If there is any conflict of calls or needed slowdown to translate, this adds time to resolve for performance access of a timely manner. In short, this is a balance of the intended output of a quick bachelor meal or a banquet for a large family gathering. Larger houses can process more at the cost of energy and heat with the space and usage. To merge cores would require to decide what appliances and house layout to keep for optimal energy use with little uncomfortable heat for the people that walk about the area and this is given the output intended (a simple dedicated meal versus an excessive large buffet of varying side dishes)."
],
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eadhm1 | Why is a 4g connection almost useless now when a few years ago it was perfectly fine for streaming audio and video? | Whenever my phone shows an LTE connection, I have really fast speeds and can stream anything. If I drop to a 4g connection, and can barely load text. | Technology | explainlikeimfive | {
"a_id": [
"fapi3kz",
"fapo2xm"
],
"text": [
"When 4G was \"cool\" there were very few users. Now there are lots, far too many, and LTE seeks to move traffic out of 4G except for edge areas with poor access. Alas, when you're there, everybody in the area is 4G and data users are much, much more common. So, yes, it is un-excellent.",
"LTE is older than 4G. What is just called LTE in the late part of the 3G standards? 4G standards include LTE Advanced and LTE Advanced Pro. Mobile phone companies often do not use the name of the standard. So they called late 3G stand for 4G like they today call LTE Advanced Pro for 5G. AT & T 5G e is the 4G LTE Advanced Pro standard So the name on your phone show can mislead. I would suspect that when you phone say that it 4G is is the, in reality, 3G LTE and LET is, in fact, 4G LTE Advanced But the name confusion is not the explanation of your experience. What happens is that the oldest standards, in general, use lower frequency and/or less complex signal encoding. So today you only jump back to the older standard when there is bad reception and the newer standard does not work. So you can the past you had god reception and used \"4G\" because that was the latest your phone and/or the network supported. Today you have \"LTE\" when you have a good connection and only jump back to \"4G\" when the connection is bad. So \"4G\" on your phone work bad today because it is only used when the connection to the towers is so bad so \"LTE\" does not work. So it is not a fair comparison. You should compare to how your phone was in the past when it jumped back from \"4G\" to \"3G\" or what it was called because of a bad connection. So if you used \"4G\" in the past with the same bad connection it would have worked as bad back then as it does today. So the situation when you used \"4G\" today and in the past is not comparable. On Android, you can in the networks setting force old standard and I suspect that you have a 4G or 3G alternative that is not the latest. The test is and you will find that it works a lot better if used with good reception. 3G will likely work better than it did in the past because most phones will used the 4G/LTE networks so you are quite alone on the 3G network."
],
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eaee56 | Difference between memory and SSD | Looking at laptops and confused between memory and SSD. | Technology | explainlikeimfive | {
"a_id": [
"fapxbsb",
"faq4829"
],
"text": [
"Memory typically refers to RAM (random access memory) where as SSD (solid state drive) refers to storage. Easiest way to know the difference is think of RAM as a work table and SSD or other storage device like a hard drive as storage cabinets. If you want to work on a project, you can only use as many tools (aka apps) as you have room on your work bench. If you run out of room on your work bench but need something else, you'll have to put something away in the cabinets and search for the new thing you need, pull it out and put it on the work bench to use. The bigger your work bench, the more stuff you can use at one time. The bigger the cabinets, the more stuff you can have in total, whether using it or not. Things like editing software take up a lot of room on the work bench. Games can too. Games also take up a lot of room in your storage cabinet. Things like pictures are tiny and take up little room on the work bench, but can add up in your storage cabinets if you have enough of them",
"Memory is temporary storage, similar to your brains \"working memory\". It controls how much stuff you can have \"in-flight\" or be working on/thinking about simultaneously (e.g., many browser tabs). SSD is like you brain's long term memory. A big, slow data store for things you want to refer to much later, like a word document or your garage code."
],
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eag0gh | Why youtube dosent have anti addblock like other sites do? | Technology | explainlikeimfive | {
"a_id": [
"faqrhve"
],
"text": [
"Nobody can say for sure what goes on in Google's meeting rooms and why they make the business decisions that they do. But I can give you a few hunches: * Google, as a company funded by advertising, obviously wants people to see ads. Therefore, any action that Google takes regarding ad-blockers is highly political and potentially a conflict of interest. It is also very likely to stir controversy, as has happened when they recently proposed changes to Chrome that would make it a lot more difficult to write effective adblockers for it. Google likely does not want to step into this PR minefield without careful consideration. * Google sets precedent and has a huge influence on web design in general. When Google does something, they are communicating to all other websites that it's okay to do that thing. Anti-adblockers pretty negatively impact the web browsing experience, so Google may be reluctant to send the message that anti-adblock should be widely deployed. I suspect many Google engineers use adblock themselves. * Anti-adblock is a cat-and-mouse game. You have ad blockers, and then you have ad blocker blockers, and then you have ad blocker blocker blockers...etc. Ultimately this is a difficult game for websites to win, and a huge site like Youtube deploying anti-adblock will likely just spur more interest in ad blocker blocker blockers, landing them back at square 1. * Google isn't strapped for cash. Youtube doesn't actually make money for Google; the cost of running it exceeds the ad revenue it brings in. There is lower-hanging fruit for them than trying to squeeze ad revenue out of people who use ad blockers on Youtube. The negative PR that implementing anti adblock would attract probably far outweighs the revenue that they would gain. * Part of good design is designing for everyone. That means stuff like designing for big and small screens, fast and slow connections, old and new browsers, etc. but it also means designing for the substantial proportion of users who use ad blockers. Intentionally creating a poor experience for a certain group of users is not something that should be taken lightly."
],
"score": [
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|
eah4al | CPU Cache | Technology | explainlikeimfive | {
"a_id": [
"far2u46"
],
"text": [
"It's memory that is very close to the CPU and can be quickly used for calculations. It's the equivalent of scratch paper when doing math, or using calculator memory to hold a few numbers to quickly finish a problem."
],
"score": [
3
],
"text_urls": [
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} | [
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|
eaj87a | How do apple/google maps know where traffic is and how quickly can it be worked out? | Technology | explainlikeimfive | {
"a_id": [
"fasgke4"
],
"text": [
"Since they track everybody's locations in real time, they knowl how fast you are moving. If a group of people they are tracking are suddenly stopped or slowing down on an open the road, it's obviously a traffic situation. Google has also added real time user updates like Waze used to do, to supplement that information."
],
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16
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|
eamb6u | Why is wardriving dangerous? | I was taught that wardriving was a type of "attack", but never really explained why it was bad. Maybe I was just dumb and didn't pay attention idk but 🤷🏻♀️ | Technology | explainlikeimfive | {
"a_id": [
"fau3caj"
],
"text": [
"Wardriving is a type of computer software attack where a person drives through a neighborhood and collects information on Wi-Fi networks. The goal is to find one that someone stupidly left unsecured or secured with a common password. Once a vulnerable Wi-Fi signal is found, hackers can attempt more complicated attacks to try and gain access to computer and other equipment, like video cameras, Amazon Echo devices, smart lights and more."
],
"score": [
16
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"text_urls": [
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} | [
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eao3a4 | Pilots, what are squawk codes? | So I'm doing a presentation for my class about aviation safety and I want to put in the squawk codes like 7500 or 7700. Before explaining the specific squawk codes and what they do, I want to let the class know what squawk codes are and how they work. I myself know what squawk codes are since I have slightly above average info about aviation, but I have no idea how to simplify it for the rest of my class to understand while still not giving too little info. Help would be much appreciated! | Technology | explainlikeimfive | {
"a_id": [
"fauuvjw"
],
"text": [
"Airplanes are fast moving, and they can't stop where they are in case something comes up. Normally radios are used to communicate with the folks who control air traffic, to get them the help they need. What happens if the radio is affected by the problem? Well, aviation came up with a backup system. Radar is a super handy way for air traffic controllers to keep track of planes, but it doesn't work like you might think. In a military radar, there is enough power to create a reflection from the aircraft's skin, because military adversaries don't cooperate with you. That much power in a radar beam has side effects, like disrupting TV, so airports use a lower power technique. Every plane carries a radar transponder. When it detects a radar pulse, it responds with a four digit code, the plane's flight number is most common. The computers that track the plane display the number, called a squawk code, next to the plane's location on the display. The backup to losing radio contact, is to switch the transponder number to a a different one. Since you know what the numbers mean, you can explain them at this point."
],
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eaol5j | Help me explain to my mom what a podcast is. | Technology | explainlikeimfive | {
"a_id": [
"fauyx1k"
],
"text": [
"Like a radio program that you download and listen to at your leisure instead of just when it airs"
],
"score": [
8
],
"text_urls": [
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} | [
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|
eaoy22 | How to the underwater fiber optic cables work and how are they able to handle the massive amount of data sent? | Technology | explainlikeimfive | {
"a_id": [
"fav5hig",
"favu9nh"
],
"text": [
"A laser shines through the clear fiber, and basically flashes on for 1 or off for 0, billions of times a second. (The exact signals are more complex but that's the basic idea.) Because lasers can turn on and off very fast, and because several different colored lasers can shine through the same fiber, and because each cable can contain several separate fibers, the total capacity per second is immense.",
"Lasers are used to send pulses of light through the cables. The light bounces around inside the cable but doesn't escape due to total internal reflection. The data is encoded within these pulses of light. On is a binary 1 and off is a binary 0. Because different frequencies of light waves will not interfere with each other, but can be easily detected and separated on the receiving end, different frequencies of laser pulses can be used to encode multiple data streams in the same cable strand. For data traveling through the transatlantic fiber optic cables buried under the seafloor, the trip is extremely brief, since it's quite literally lightspeed. It takes way more time for the machines at the ends of the cable to decode the data back into electrical binary streams then it does for data to travel the length of a fiber optic cable strand."
],
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|
earjbj | How do satellites keep orientation in space? | For example, how would a communicaitons satellite keep its antennas pointed towards the earth? Wouldn't it keep its orientation and begin to point away from the earth? | Technology | explainlikeimfive | {
"a_id": [
"faweha9"
],
"text": [
"There are some minor station-keeping operations that happen. Small thrusters can adjust its orbit (read: accelerate) if required, and reaction wheels can adjust its orientation. Otherwise, Sir Isaac Newton is in the driver’s seat! Gravity and orbital mechanics are very predictable."
],
"score": [
6
],
"text_urls": [
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} | [
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eascnr | How is weather predicted? | Technology | explainlikeimfive | {
"a_id": [
"fawuoox"
],
"text": [
"Supercomputers are used to run simulations (\"models\") that try to \"fast-forward\" current conditions based on what we know about how weather works. Multiple times a day, the supercomputers are fed data about current weather conditions all over the world. The data mostly comes from weather satellites but also includes information from radars, ground stations, weather balloons, etc. Based on how things are currently, the models try to figure out what's going to happen next. There are many models of varying quality that are operated by various agencies, mostly government agencies like NOAA/NWS but also some private ones. Every model is going to produce slightly (or sometimes drastically) different results, so it is necessary to reconcile their predictions. Sometimes this is done in an automated fashion but usually it is better to involve a meteorologist. They look at the output of many different models and try to figure out what outcome is most likely based on their expertise. Then they release a final forecast for public consumption. Many agencies freely release the results of their models. If you are interested, you can [look at the output]( URL_0 ) yourself, in near real time as they come out. It can be a fun exercise to look at these and try to synthesize your own weather predictions!"
],
"score": [
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"text_urls": [
[
"https://www.instantweathermaps.com/"
]
]
} | [
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|
easkry | Why is it that after I buy a new game on Steam, Origin, etc., wait the hour+ for it to download and install, then finally open it to play and the first thing I’m greeted with is an update download? Why isn’t all this a part of what I just downloaded/installed? | Technology | explainlikeimfive | {
"a_id": [
"fawtmp5",
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"text": [
"Depends on the game but general 1) When a game downloads from Steam (or any other service) it usually comes with some redistributable libraries that need to be installed once. Those can have security or stability patches that get installed separately. 2) Multiplayer competitive games will often have 3rd party anti-cheat software that is a totally separate installation and often has its own frequently updated pipeline. 3) Additional content... if a company is pushing out a decent amount of content for a game but not changing anything in the \"code\" there isn't a huge reason to push those changes to Steam/Epic.",
"Liability and logistical issues. When a developer uploads a new game to Steam, it actually takes a fair bit of work on both ends to do quality control, content approval, indexing, technical troubleshooting, etc. Going through the same process to upload a revised version of the game every time there's a minor update would drain resources from both Steam and the developers, AND it would confuse the issue of who is responsible for addressing customer problems. Under such a system, if you buy and download a game and then it's not the version you wanted or isn't what you expected, who is responsible? Steam or the developer? By comparison, the current system has the developer upload one version of the game to Steam which includes an updater as part of the original package. It does add a step when you, the customer, buy and download and then have to update the game, BUT you know exactly who to go to if there is a problem and it's easier for Steam and the developer to do business together. **EDIT:** I have been corrected on the particulars of this description with regards to Steam. See replies below.",
"Since no other top level comment has actually funny explained it... This will only happen on Steam if A - There's been a new update gone live since you started the download. Or B - The game uses its own launcher to get updates (which generally only occurs with multi-player games because they'll hash check all the files before launch)",
"That has, quite literally, never happened to me. Unless a game has its own launcher, such as FF14 or another MMO, there is no reason for it to happen. As far as I know, Steam does not differentiate between installing and updating a game. It checks what you have and sends you the files for the current version of the game (unless you're purposefully downloading an old build). Can't speak for Origin, as I haven't used it in a couple of years, but I don't recall anything like that happening on there either.",
"Sounds like you're playing a game (And following a publisher) that isn't actually using the Steam platform.. but rather.. they have their own launcher and manage updates on THAT, while only sending periodic 'base' updates to the Steam platform, so it's always behind during the first install. Using Steam purely to cover ground rather than their actual update distributor. Many (MANY) people will have no idea what you're talking about because most Steam games publish directly to Steam, every update, every patch, etc. No shitty launcher-in-the-middle topology.",
"What game? Just like everyone else I have never seen this happen before. Never used origin though only steam."
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eat70i | How does raytracing work? Not what it does, but how it does it. | Technology | explainlikeimfive | {
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"A fundamental theory of light and rays and reflection is that how it reflects doesn't matter which direction it travels. A beam of light fired from point A to eventually point B (bouncing off whatever) can be fired back in the opposite direction from B to A successfully along the same path. Normally we see things because light comes from a light source (the sun, light bulb, etc), bounces off things causing colour filtering, and eventually into our eyes or a camera to be seen. Raytracing does it the other way around - starts at the camera and fires \"scanning\" rays to see what it hits and hence what it could see. That ray may also bounce or scatter in the same way light would. Historically raytracing has been a pixel-by-pixel computationally expensive process. Obviously \"RTX\" graphics cards have changed that in an attempt to make it a nearly real-time thing. I don't know what magic nVidia has thrown in their cards to make it so fast, but I'm kinda impressed."
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eavk1b | How a smartphone can detect only my finger but not another object ? | Technology | explainlikeimfive | {
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"It detects the elecrical current going through your finger, which is why unconductive objects such as plastic and even your clothes wont trigger a reaction"
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eaz8cz | What is a hyperparameter in machine learning? | This is the definition of hyperparameter from Wikipedia - URL_0 'whose value is set before the learning process begins. By contrast, the values of other parameters are derived via training' Can someone give a simple and intuitive example of this concept - why you would want a value to be set before the learning process begins? | Technology | explainlikeimfive | {
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"The \"parameters\" are usually things to describe the actual pieces of the neural net, i.e. the individual weights between connected nodes. Ultimately those are determined by the algorithm as a result of training. The \"hyperparameters\" are the settings for the whole setup of the network and training. Things like the learning rate, number of units per layer, etc. They are \"hyper\" because they are a level above things like the weights between nodes.",
"The word \"parameter\" is a bit overloaded. Models have coefficients typically called (estimated) parameters, e.g. y = x + b has two coefficients/parameters to be fit/trained. The fitting algorithm could be MLE, MSE or something else. You could say the choice of algorithm is a parameter too, but to disambiguate from the data-derived parameters it's called a hyperparameter.",
"It's a parameter that determines how the model learns, in contrast to the parameters learned by the model. You want to set a value before learning begins, so that the learning process is optimal for the application (the dataset, and the performance expected of the resulting model)."
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eazez8 | Computer building basics and compatibilities for parts make no sense to me. | Technology | explainlikeimfive | {
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"Use a site a like PCPartPicker to find parts that are compatible. You need a case, motherboard, processor (and its cooling accessories), RAM, graphics and sound cards, and storage (SSD and HDD)."
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eb06fj | How do pirating groups profit from uploading movies/games to torrent sites? | Technology | explainlikeimfive | {
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"They don’t. They do hard work so you can enjoy the game, but cracking the game is more fun for them, just like building games is more fun than playing them for others.",
"They don't get any money from it necessarily, unless someone paid them to crack it in the first place. Otherwise, it's about the excitement / challenge of cracking the media. Maybe their reputation will go up in certain circles, too, if they're cracking particularly hard games or are putting media up online really quickly after it releases.",
"Add malware to the app to mine Bitcoin or add your machine to a botnet can make money. That's normally not the main cracking group though but someone else along the way."
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eb571a | how does a short wave radio allow you to speak to someone who's in a whole different country? | Technology | explainlikeimfive | {
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"As you know, the Sun emits a stream of electrically-charged particles, which are responsible for the beautiful [Northern Lights]( URL_0 ). The area of the atmosphere these lights occur in is called the *ionosphere,* so named because it's filled with ionized air due to the Sun's particles. Shortwave radio is exactly the right frequency that, when the waves hit the inner surface of the ionosphere, they bounce off and return to Earth. This permits shortwave radio to travel a lot farther than you'd expect, allowing radio operators in America to speak to people on the other side of the world.",
"tl;dr - shortwave radios use comparatively long wavelengths that are harder to disrupt and can travel farther, use a *lot* more power to help signals travel farther, and use antennas to increase the direction that the power is focused to allow it to travel farther. Most people's understanding of how radios work comes from the radios they have in their everyday life - WiFi and cell phones. While they both use similar general fundamentals about how radios work, there are some differences that should be highlighted: * \"Shortwave\" is a bit of a misnomer these days because the wavelengths they use for transnational and transcontinental contact are actually really long compared to what cell phones and WiFi uses. Shortwave radios will measure their wavelengths in meters - 144 MHz (a common amateur radio band) is 2 meters in length, while 2.4 GHz has a wavelength of 12.5 centimeters. The shorter the wavelength, the easier it is to disrupt the signal. The shorter the wavelength, the more data you can stuff in there which is why modern systems tend to go to higher and higher wavelengths. * Lower wavelengths can actually bounce off of certain layers of the upper atmosphere, allowing you to bounce signals to hit distant points that would normally be out of range due to curvature of the earth * Shortwave radios can use a *lot* more power. WiFi uses 100 milliwatts to cover your home; by comparison, the 3.5 MHz amateur radio band (80 meter wavelength) has a maximum power of 1500 watts, or 15,000 more power that can be used. * The other main difference is the antenna. Antennas are used to radiate power, can different antennas ran radiate power in different distribution patterns, meaning you can point power more in one direction than another. WiFi is designed to be as general purpose as possible, which means that since the radio builders don't know how people will use it they want to radiate power as equally as possible in all directions. Advanced antenna designs such as a parabolic dish or a Yagi can allow you to reshape the power so > 90% gets focused in a small direction, which allows the signal to travel significantly greater distances."
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eb571t | Why are subjects illuminated by blue light so hard to show on TV? | Such as in this [image. ]( URL_0 ) This screen cap was taken from a live stage performance where the subject was briefly illuminated by a blue light. Why is there such a strange effect made by the light? I have played the broadcast on an OLED and a LCD screen and the effect is the same, so I’m guessing it is a camera side issue? Thank you. | Technology | explainlikeimfive | {
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"When a digital camera sensor picks up light that has a very bright color or overall light it can clip at the top. Basically the blue is so much brighter than everything else that the camera can't tell the different intensities of blue anymore so it records them at maximum brightness. This gives an area of full bright blue that is no longer a good representation of what it looked like live. HDR helps fix this by giving more possible brightness values for each color."
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eb5btd | how effective were old cannons? | ELI5: I'm pretty sure everyone saw old cannons that used big round balls, but how effective were they? pretty sure the pirate ones were pretty effective at making holes in enemy ships. The early ones seem like they would hit the dirt and the dirt would shrapnel over the soldiers. Am I missing something or would these cannons offer a single shot kill or what? | Technology | explainlikeimfive | {
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"Basic cannon balls were mainly good at punching good sized holes in things If they hit the side of a ship they would splinter the hull and send sharp pieces of wood flying at high speed into the crew. They could also hit loaded cannons which could cause misfires or fires on board, both of which are very bad for a wooden ship full of gun powder. Ships also used Chain Shot(literally chains) for ripping through enemy sails and potentially taking entire masts down. They had grape shot too which was really nasty buckshot which would chew through the enemy crew but only at close range. Field artillery(cannons used by the army) had a variety of shot. There was round shot like the navy boys use which would punch big holes, but there was a variety of other rounds they could use. There was canister shot, basically a big shotgun shell for the cannon which would decimate infantry at short range. There were explosive shells which would detonate after a fixed time, percussion shells which would detonate on impact, shrapnel shells which would detonate at a fixed time but spew shrapnel down on enemy infantry, and quicklime and carcass shot which spewed fire down below them. Round shot is nice and simple to show in movies, but Admirals and Generals had a variety of rounds available to do their deeds with.",
"They were clearly effective because they were used by everyone who could get hold of them. The use of cannon caused the end of stone castles. It's worth knowing that a cannonball doesn't have to hit you to kill you. If it passes within a few inches the shock wave can damage internal organs.",
"In Napoleonic wars, the solid shot was usually used against massed troops and they would shoot at a flatter trajectory so it would bounce across, like skipping stones. If the targeted troops were in a square to ward off cavalry, the bounding shot would take out soldiers on two sides of the square. Deploying in line helped but that was inviting a cavalry charge, in which case they deployed back to square."
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eb8b7s | How come it takes '10 business days' for a company to successfully unsubscribe me from emails? | Is there a logical answer to this other than "they just want to try their hardest to change your mind and/or flood you with an enormous amount of emails before they unsubscribe you"? I can't be alone in thinking that this should be a rather seamlessly and automatic process that should take less than half a second to compute in a system's database, right? | Technology | explainlikeimfive | {
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"Most companies are just being lazy and don't want to spent time on tech required to unsubscribe instantly. Moreover, they may have scheduled some emails to you already. And just to be safe, they say that you'll be unsubscribed in 10 days, instead of removing those scheduled emails from their system.",
"Many of those companies use a third party to send out their emails, so it just the time it takes to inform the other company along with some buffer so nobody can complain if you somehow aren't removed right away.",
"It is actually defined by law, from experience managing these systems presently the unsubscribe is effectively immediate. Back when the law was passed (2003) systems weren't as well integrated and it could take days for the email campaigns to get fresh address lists.",
"The US federal law (CAN SPAM Act) mandates that companies take no more than 10 business days to honor an unsubscribe request... Even though most unsubscribes are immediately processed, companies tend to say, “We will process your request within ten days.” to give some breathing room (in case some messages were already batches up and about to be sent). Better for the company to promise less than to promise more and risk breaking the promise.",
"There might be some technical merit to it. Servers have databases, and the databases have operations running on them. Take for example a website with an e-commerce platform hosted on it. It has to serve the website, manage orders, and handle automated emails and other tasks. When someone wants to access the website or place an order, thats an operation that must be completed ASAP or the user will get annoyed. When these requests come in they are handled as soon as the server has free time for them. Unsubscribing to a newsletter, sending out a newsletter, deleting a user account, these are all lower priority tasks. The server can accept the task, respond to the user telling them it will handle the task, and then queue that task up. It might wait until its expecting fewer real-time requests (3am, weekend, etc..) to execute these tasks. This is probably a case of their server only runs the task of changing subscription data once every week or something.",
"The process is largely automatic and usually does take instantly, but there are two major points that could result in you getting emails a few days after unsubscribing: 1) These email marketing campaigns are usually conducted by contracted third parties, and they can be set up days before hand. And there's not usually a \"recheck\" before they're sent out, so even though you've unsubscribed, the next few days worth of mass emailings are already queued and ready to go. 2) Email is a \"store and forward\" type system, meaning each server along the way holds on to the mail until it can deliver it to the next one in the chain. For most people using major email providers, that doesn't have a lot of impact, but it's possible if your email tends to pass through multiple mail servers that if a server in the chain was having an outage that emails would have been backed up / delayed and delivered to you later than they otherwise would have been."
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ebcet8 | How do Skylanders/Disney Infinity video game pieces work? | I'm just wondering how the pieces work when you place them on the 'portal' and it loads the character into the game? | Technology | explainlikeimfive | {
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"NFC/RFID technology. The 'portal' has a big coil of wire resonating at a set frequency, which produces a magnetic field. when the 'piece' sits near the portal, the coil of wire inside the 'piece' picks up the alternating magnetic field as electricity in the coil. this electricity charges up a capacitor in the 'piece', which is used to power up a very simple memory device, which pushes back on the alternating electricity coming from the 'piece's coil, which is in turn passed through the magnetic field back into the 'portal's coil, and then interpreted by the 'portal'. in this way, the two devices can setup a communications link, share a small amount of power from 'portal' to 'piece', and use this to read the small amount of memory ( typically around 1000 bytes) stored in the 'piece'"
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ebf330 | Why do musicians recording their voice wear headphones? What is the purpose? | Technology | explainlikeimfive | {
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"The instrumental they’re singing to is playing through the headphones. It can’t play through speakers because the recording will pick up the instrumental along with the vocals. Instrumentals and vocals need to be recorded separate so they can be mixed through different channels.",
"Not a vocalist but when I record drums I have the track playing in the headphones with a metronome as well. I assume vocalists have the same thing playing in theirs.",
"It is also to hear the click track, if it is that kind of session. Orchestral musician here who does sessions occasionally. A click track is a loud, clear click on each beat. This gives the kind of precision needed to punch in and out, to replace measures of music where a mistake has been made. The software will be able to replace exactly what is needed. Some musicians prefer to have the headphones over both ears, others like to leave one ear off so they can hear the click track but have a more familiar and natural sound in the other ear.",
"When you sing (or speak) you hear yourself through your head, your voice is traveling in your head passing throught bones, tissues and water, and so is distorted. The others hear your voice that had traveled trough air, and so is not distorted (that is also why your recorded voice sounds different to you). Singers wear headphones because they hear themselves through the mic giving them an optimal knowledge of how they voice sounds, and so they can correct and perfect their sound. They do that in live performances as well, they have a special hearplug that transmits the sound that the public is hearing, it also helps tuning down the volume not to hurts themselfs (this only in live performances)",
"Two reasons: You need to hear the song you are singing to. Vocals are recorded usually last so they need to hear the other instruments. We can't use speakers as then the sound from the speakers would be recorded to the vocal track, defeating the whole idea of isolating each instrument or sound source to their own tracks. This makes mixing much easier, you can change levels of single instruments. Sound leaking to other channels is a problem but it can also be a method, studio live is one such where leaking is often considered very important. Second reason is monitoring. Have you tried singing with headphones on? It sound muffled and even when speaking it is hard to know how loud you are. So we need to route your own voice back to you. The balance between the backing track and monitoring is adjusted for every singer separately and changes a lot. Some like to keep headphones only in one ear, some like to have effects such as delay and reverb, or pan the backing track more to one ear and less on the other.. and also they may require a different mix of the band instrument, they may drop bass completely, decrease some of the drums, remove keyboards and raise guitars, what ever is the instrument most important to them is raised up. Reverb is one \"secret\" weapon for many, without it your sound dies off instantly whereas in a regular room your voice will reverberate around and come back to you. It can also help one to keep a constant pitch as changes will be immediately heard from the reverb. Specially at the beginning this can be a problem as it can actually be hard to keep pitch in a room with no echo at all. But we can't use a room with strong echo as that would then be imprinted to the vocal track: the mic captures all sounds in that room, it is often specifically made to do that. So the compromise is to artificially create some virtual space that aids performance. Also: if it sounds cool, you also sing better and with more confidence... Good recording engineers are willing to go to great lengths to get a good performance from an artist, that performance is then captured as well as possible. The former trumps the latter, the performance is more important than minor technical details, which is not always understood by said recording engineer.. If they had their way, you could be hanged by your ankles 20ft in the air in a freezing hangar to get natural reverb without early reflections from ground messing it all up. It is better to just use headphones instead. Some have said about latency and that is important factor these days. This means you may not be able to use virtual plugins but have to invest into hardware just to get that one channel, vocal monitoring, its own signal chain and tap a split into that to get your recorded signal.. Lag or delay in the signal can be very destructive as that messes up with timing and also makes your brain feel funny: you can literally think your head is 10ft in diameter since the sound arrives so late. We know VERY well how and when our own voice should sound."
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ebmwg3 | when swiping (or inserting) a card, how does the card transfer its information to the machine? | Technology | explainlikeimfive | {
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"Your information is stored either in a magnetic strip (similar to a hard disk drive) or in a chip that the card reader has an interface too (like the metal bits In a charger) When connected the reader reads the information and confirms with a site whether the pin is correct and whether you have enough money to purchase the goods. If so it sends a code authorising the payment to the reader allowing you to go about the day and deducts it from your account",
"These days there are four ways to enter card data onto a credit terminal: 1. Type it in—highly discouraged these days, since it is pretty insecure. Anyone with the account number (and a low-tech terminal) can place charges on the card (until the bank takes notice). 2. Swipe the [magnetic stripe]( URL_2 )—like a cassette player, there is a magnetic head that reads the data encoded in the stripe. Discouraged because it is insecure, equipment to spoof and skim magstripes is now easy to get, and magstripes can be thrashed by magnets and other magstripes. 3. [EMV]( URL_1 ) chip—transfers much more secure information to a chip reader inside the terminal. The terminals maintain encryption and can defend against some kinds of intrusion, such as preventing use of the previous methods on the same terminal. 4. [Contactless]( URL_0 ) (tap to pay)—an RFID or 'near field' communication system wirelessly powers the card's chip, and reads the data that it transfers back wirelessly. Although vulnerable to attack from wireless skimmers (e.g. someone \"bumps\" into you at the airport), the weak signal practically requires the physical card to be present."
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ebpab1 | What is an electrical surge protector and what can potentially happen without it? | I see that commonly labeled on outlets is a "surge protection" feature, but what are the benefits and the consequences of not having one? Also, why do some of these devices have an Ethernet and phone line ports? | Technology | explainlikeimfive | {
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"Surge protection basically means that if there's a lightning stroke or something that causes a sudden increase in voltage, the protector will stop it from ruining your electronics. It's good to have in general, but especially on your expensive devices.",
"A surge protector is basically an electrical \"bypass\" for your equipment. When a high voltage occurs, they are designed to short to ground, basically collapsing the voltage across your device. Once the condition is past, they basically restore to normal (assuming the voltage wasn't high enough to destroy them). Anything electric (ethernet, phone) can benefit from them because surges can come from the ground as well as the power line. The closer they are to what they are protecting, the better they can work, so while a \"whole-house\" surge protector is good, having one at the point of use is better. To elaborate a little, a 'varistor' is a device (used in arresters) whose resistance decreases as the voltage exceeds a certain level. So it sits there fat and happy as a high resistance to ground in parallel to your device. Once the voltage exceeds it's design level, it starts conducting (basically a controlled short) to ground and collapses the voltage, which protects your device. The amount of energy they can withstand is rated in joules, so make sure you get one ample enough to do it's job."
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ebpv3n | why are subtitles on streaming services sometimes not the same dialog? | Edit: I meant for English subtitles on English shows and movies but I was answered already thank you everyone who tried to help 😊 | Technology | explainlikeimfive | {
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"They are often using the shooting script, rather than paying a transcriber for each episode of potentially 100+ episodes. The shooting script will often have minor variations to the actual broadcast version, due to editing, on the day direction or cast improvisations, so the script won't perfectly match what you see. For a big budget production the studio will ship the perfect subtitles, but it's simply not cost effective for some shows.",
"It depends on the show. In the case of foreign language films (eg: anime from Japan), videos will often have multiple audio tracks in different languages, but then this causes issues for the subtitles. The language dubs may tweak the exact dialogue to better lip sync with the foreign language video or generally appeal to the translated audience, whereas subtitles may be written to best convey the original intention of the dialogue and most sincere translation. This results in the audio and subtitles not matching."
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ebs6ej | why can motorbike batteries sit on a shelf unused without losing charge but when sitting inside a motorbike for a few weeks that hasn't been turned on, go dead? | Technology | explainlikeimfive | {
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"When its on the shelf, there no where for the energy to go. In a motorbike, the battery is slowly and passively discharging. even if nothing is on. This is because the electrons in the battert have another place to go, the motor bike electrical system",
"There are two things: First, some portions of your bike's electrical systems will often remain on when the bike is turned off, causing minimal, but noticeable drain. Second, on the shelf the battery is in a climate controlled environment, while in the bike it is not. Repeated heating and cooling causes many types of battery to lose charge, especially if it is outside of the battery's ideal temperature range."
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ebu4a5 | How does touchscreen work? | Technology | explainlikeimfive | {
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"Electrically conductive materials that are near each other make a capacitor. If you use a battery you can charge a capacitor up to full charge very quickly. If you put a resistor in the path of the electricity it will slow down the charge up process enough that you can measure the charge up time to see how much capacity it has. Touch screens have a grid of thin wires. The left-right wires never touch the up-down wires, but are very close. Picking a left-right wire and an up-down wire lets you pick a capacitor at some location on the screen (since you have two electrical conductors near each other.) The touch screen scans across every \"capacitor\" in the grid and measures the capacity. Your skin isn't very conductive. However, your blood is very conductive. When you bring your finger close to one of these capacitors, the meat-bag conductor increases the capacity nearby, and that will be picked up by the scan. (You can activate a sensitive touch screen without even physically touching it if you have steady hands.) Fun facts: The bits and bobs inside your phone and tablet make the capacity of these little wire-pair capacitors vary across the screen, so the screen needs to learn in the factory what no one touching it looks like, generally after the device is fully assembled. I've been told that Apple holds a patent on square wire grids, so everyone else uses a diamond pattern, and does a little extra math to put it into screen positions.",
"There are two kinds, but I'll explain capacitive touch because it's cooler and easier to use. There are electrons being rapidly pumped into and out of a bunch of transparent wires on your screen. When something comes near the screen, it makes it easier for these electrons to move into the screen since they're attracted to the something. The computer senses this easier movement, and knows there is something there. If the movement is too easy, it's probably just a piece of metal. If the movement is too hard then there's probably nothing there or something with a lot of resistance (not a finger)."
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ebxw4i | when I’m on loudspeaker during a phone call on my phone, why don’t the speaker and the microphone create an infinite loop of echo? | Technology | explainlikeimfive | {
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"text": [
"URL_0 Here is an article that you’ll probably find useful. Essentially there is usually an algorithm that will cut out frequencies to avoid feedback. Sometimes it doesn’t work. I’m guessing there is also gain attenuation (variable mic input) goin on to help avoid feedback.",
"There are several ways this is handled, but the most interresting to me are: Phase Locked Loops (PLLs) Basically, the system \"knows\" what is being sent out from the speaker, and these frequencies can be timed and very precisely removed from the microphone input. In the past, this was done using analog circuitry. It's the same technology that has kept major rock concerts from being ear-splitting feedback since the invention of the loudspeaker. Because processors are so fast now, the same functionality can now be done in software in the digital world."
],
"score": [
4,
4
],
"text_urls": [
[
"https://electronics.stackexchange.com/questions/24470/avoiding-echo-feedback-on-speaker-phones-how"
],
[]
]
} | [
"url"
] | [
"url"
] |
|
ebxzh2 | Why does deleting things clear storage even though the pc only can’t find it? | Technology | explainlikeimfive | {
"a_id": [
"fb7vbe5",
"fb7w09s"
],
"text": [
"When you delete a file the file system marks that file for deletion and deletes any references to that files location on disk. As far as the OS is concerned, this space is now clear and that's reflected through the GUI. The files are still on the disk in the same place, the OS just sees that space as \"Oh hey I can store stuff in those blocks of space now\". The OS doesn't read a disk and say \"How many blocks read 0?\", but rather \"How many blocks can I write to?\", a deleted file is marked as blocks the OS can write to.",
"It’s like you run a big neighborhood and you have an address book with all the people who live there in it. One day one of your neighbors calls up and says “hey I’m moving. Take my name out your book.” So you do that. You don’t erase the address, just the name, and you don’t go to their house and clean it for them. Then a few days later someone comes up to you and says “Hey I’m looking to move into a new place. Are there any open houses in your neighborhood?” And you look through your address book and sure enough, there’s a space without a name. You and your friend drive up to the house and all the neighbor’s old stuff is still there, so you clean it out and help your new friend move in. Then you put his name in the book at that address so you know where he lives."
],
"score": [
10,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
ebyk7r | how do podcasts insert advertisements that are unique to my location? | I have noticed some ads in my podcast for things in Southern California, and I'm sure listeners in the northeast get different ads. I'm not surprised the podcasts know where I live, but what's the technical method they use to serve these ads? I was under the impression a podcast is just a single audio file. Is there a database of ads that get injected into the file once I play it? Or once I download it? And does this work the same for podcasts on Spotify versus Apple? | Technology | explainlikeimfive | {
"a_id": [
"fb8azyq"
],
"text": [
"A podcast is a single file when you get it but is it not necessarily a single file on the server. So you have podcast files that are split into multiple parts and you put them together with the ads into a single file when you download it. What is selected depending on your IP address. Perhaps cookies and other similar data if it is available. You can combine multiple sound files into one with needing to encode the sound. Look up \"mp3 merger\" and you find a lot of software and website that do that. I suppose you can do the same in other audio formats. Another option if fewer ad alternative is needed you can just upload multiple files and the server just select one. [ URL_0 ]( URL_0 )"
],
"score": [
3
],
"text_urls": [
[
"https://castos.com/dynamic-ad-insertion-for-podcasts/"
]
]
} | [
"url"
] | [
"url"
] |
ec32z7 | How are dubbing voices replaced without messing with background noises? | Technology | explainlikeimfive | {
"a_id": [
"fb8uvf1"
],
"text": [
"Basically, all the footage and sound effects are kept as separate files. These days there’s software that you can load these files into and then arrange and edit, and then the software will compile it all into the video that’s actually distributed to tv networks, streaming sites, or movie theaters. Different audio is typically recorded separately, so voice acting and sound effects are stored in different files - even different lines likely are stored as separate files. This makes dubbing largely just a matter loading a different set of voice files into the software. If it’s animated, they might also edit the facial animations. The exact process can vary depending on techniques used, but that’s the basic idea"
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
ec5b7f | Why do some images in softwares such as Photoshop appear fine at 85% zoom, blurry at 100%, and then fine again at 125%? | Technology | explainlikeimfive | {
"a_id": [
"fb9pl8j"
],
"text": [
"Imagine an image was to be displayed 50/50 red and blue. You start out viewing it at a size when it's 20 pixels wide, so 10 pixels red and ten blue. Bam, it is perfect. Now you zoom in by 25 percent, making it 25 percent larger. The red and blue should each be 12.5 pixels wide, for 25 total pixels Uh oh, a pixel is a smallest we go. A pixel has to be all one color, it can't be half one and half the other. So maybe out of our 25 pixel width, we either do 13 red and 12 blue, or vice versa. Or maybe 12 red 12 blue and a purple pixel in between. Either way, it doesn't look perfectly 50/50 red blue anymore, there's either a purple blurring of the line between the two, or it looks slightly off. Zoom in farther! 50%! Now that ten and ten becomes 15 and 15, for 30 total. The screen can totally do that, no problem, there's no half pixels there. So you had the weird half pixel problem at 25% maginification, but not 0 or 50. This is super simplistic, and the problem is drastically more complex over curves, but that's a basic. This is also just one element. There's also a case of extreme zooms where the 'pixel' elements Photoshop is representing get so big individually your brain stops seeing the pixels together as a picture, and start seeing the clear delineation of the pixels as separate elements."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
ec6r1q | In the movies when banks are robbed, the thieves demand "unmarked non-consecutive bills" or something along those lines. How do the authorities track bills? | Can the bills only be tracked if they are deposited at a bank? Are they marked by a special invisible ink? | Technology | explainlikeimfive | {
"a_id": [
"fb9hfby"
],
"text": [
"Bills can be marked with special inks or other concealed markers, and serial numbers can be recorded and reported to banks and law enforcement agencies."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
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