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7e7xm8 | Why does copying a timestamped video from youtube result in URL_1 instead of URL_0 ? | Technology | explainlikeimfive | {
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"It's actually URL_2 . YouTube bought the domain URL_2 to make short URLs possible. This is actually no longer necessary, since services like Twitter (where short URLs were necessary) now use their own link-shortening services; but the option is still there. Basically, if you go to URL_0 , it simply redirects you to https://www.youtube.com/watch?v=xrCtMgKghW8?feature= URL_2 -- the \"feature=...\" part simply tells YouTube that you used the shortened link, so that YouTube can keep statistics. Quite simply, if you go to a YouTube video and click on \"Share\", it gives you the shorted URL. If you then click the \"Start at\" box, it adds the timestamp, giving you, for example, URL_0 ?t=1m30s -- which redirects you to URL_1"
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7e83ec | If computers are lightning-fast at running calculations and performing tasks, why does "freezing" take seconds or even minutes? | Technology | explainlikeimfive | {
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"Think of a computer as a train station. The computer manages the programs (trains) as they move about the station. There are always more trains than there are platforms and tracks, but the computer manages the trains carefully so each train gets time on a platform to do it's business. Now imagine one of the trains breaks down for some reason. Every train behind it is forced to stop and wait until the broken down train is fixed before it can move to the platform. If the broken down train is broken down in a way the computer can't easily fix, it sits there indefinitely.",
"Applications run on CPU threads. Single-threaded applications load everything on a single thread. You can think of threads as tasks. A single threaded app will do everything on its single thread. In this case, any long running operations will cause the UI to lock up and become unresponsive. This is because the thread is too busy attending to whatever work has been allocated to it in the background - it can't process UI interaction while this is busy. This is exactly why multi-threading is preferred for more complex applications. Multi-threaded applications move the background tasks that take a long time onto worker threads that work independently and (mostly) asynchronously from the UI thread. This frees up the UI thread to process user input and report progress of any active tasks that might be running in the background. Source: I'm a professional software developer.",
"If you send computer into infinite calculations - it's really don't matter if he is slow or fast. He will be calculating it forever). Like: While (TRUE) do I=I+1. It's freeze because of code bug. Or let's say there may be semaphore lock. Process A need resources X and Y to complete his job. He will lock resource X, but Y is already locked for process B, so A will wait until Y is released. In mean time process B will require resource X to complete his calculations (and he will release resource Y after it). But X is already locked by process A. So we ended in double lock, that will freeze your system forever. (Or until operation system will interfere and kill both A and B ))) And it's freeze because of resources allocation. All this freezes are independent from CPU speed."
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7e8f61 | why does ALT CTRL DEL sometimes fail? | Technology | explainlikeimfive | {
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"A computer and all the things connected to it are managed by the operating system. When you're running a program that uses a keyboard, the operating system works as a translator of sorts that receives the button presses from a keyboard and then forwards that onto the program you're running. When you press Ctrl+Alt+Del at once, your operating system triggers a special response that attempts to pause all other running programs, start the task manager, and switch to it. When it fails, that means that this process got messed up in some way. The process of pausing the other programs is called a \"context switch.\" Basically what happens is the OS makes a quick backup of the current state of the program and moves all of the currently running code out of the processor and into the RAM. In order to do this though, the OS has to first ask the running program to get to a point where it can be saved as a state. If the program is stuck (in a loop), it will not respond to the operating system's request to pause. So ultimately the operating system is dependent on the currently running program being able to pause itself, which it can't do if it is stuck for any reason. When it's stuck, then the OS has to go through some more complex recovery routines that take a while and will cause slower computers to freeze."
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7ea8ea | Why do older video games look so angular, like they were pasting faces on the blocks of wood? What changed? | Technology | explainlikeimfive | {
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"Computers do 3D graphics with angular, pointy shaped polygons. If you wanna make something look smooth and rounded, you need to use **more** little polygons to approximate a rounded edge. Problem is, more polygons means more resources for a computer to keep track of, and on older systems eventually you'd run out of memory to keep track of it all. So in ye olden days, you had to look for stuff you could skip drawing in 3D, and paste a picture on instead. Pasting a picture on aka \"using a texture\" could be less \"expensive\" for the computer to spend time on rather than really building details in 3D. So a lot of facial detail (how eyes are set in, how cheeks are rounded) would get skipped over. [Here's a kinda long video showing off Mario's evolution over the years.]( URL_0 ) In his N64 days, it took 752 polygons to make his shape, but by the time you get to modern models, it takes over 10,000. But in exchange you get to model all sorts of little details (like his mustache! And fingers!) that help him look way better. The N64 simply didn't have enough memory to store this, and even if it did it's CPU was too slow to draw it fast enough: ideally games need to draw a new picture of what's happening on screen **at least** 30 times a second in order for the motion to look okay.",
"They are still using blocks of wood, but nowadays computers can handle bazillions of blocks at once so each one can be microscopic.",
"back when these games were made, computers were far less powerful than they are today. as such, games were designed to work with whatever hardware was available at the time, meaning that things in the game had to be made as simple as possible so that it would run properly on the average consumer machine. The qualities you're describing, such as everything being angular, is an example of that simplification.",
"That's actually a fairly accurate comparison. Game consoles were very limited up until around the Gamecube/PS2/XBox era where 3D graphics were advanced enough to actually model a character's face. Compare it to Mario (Jumpman. w/e) in Donkey Kong, to Mario in Mario World. I Donkey Kong He doesn't have a mouth, or eyes, or many distingusing features. Then as technology improved, his' body can be better drawn because the console supports higher fidelity sprites.",
"They looked so angular because they were using computing hardware which was much less capable. In order to create the minimum 3D object you need at least 3 points, and connecting them together forms a 2D triangle located in 3D space. These triangles can be connected together to form a 3D model, and more triangles mean the model can become more detailed. When an image is \"rendered\" the computer needs to process the locations of all those triangles and how their surfaces would look from a particular direction. For a complex scene this can mean an extremely large number of calculations which need to be performed very quickly. Older games were designed so their number of triangles could be processed 30 times a second which resulted in blocky models. These days we can process a lot more so you probably can't tell they are made up of those same triangle shapes."
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7ebdxw | Why do fridges pop and bang (very loudly) | Technology | explainlikeimfive | {
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"Cracks, pops and bangs (especially rare, kinda unpredictable ones) may be your ice maker. Ice forms in a mold and eventually gets ejected, often shattering in the process, then tumbling down onto it's cubey brethren. More \"mechanical\" noises might be the compressor.",
"It's likely the defrost cycle. Refrigerators work with a liquid (refrigerant) that gets compressed by the compressor then allowed to expand inside some tubes. That expansion absorbs heat from inside the ice box, making the area cold. Unfortunately, a limitation of the refrigerant is this process happens at only a pretty cold temperature, about that of freezing ice. So because of that the moisture in the air of the ice box gets frozen on the coils inside. So ironically, there's a heater in there that melts the ice off the coils every hour or two. It's called a defroster. As that ice melts and heats up, sometimes it cracks and breaks, dropping into a drip tray. That's the sound you're hearing. :)"
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7eck14 | what physically changes in a computer when you save something? | If you were to look through microscope what is the physical change you would see in the components? | Technology | explainlikeimfive | {
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"It depends on what type of computer. If it is a conventional hard drive, or mechanical drive, with the right instruments you would be able to 'see' microscopic magnetic pits on the surface of the disk change from off to on. The mechanical drive is a magnetic storage device. Depending on what areas are on or off tells the device and thus the computer what is written there. If your talking a Solid State drive (SSD), or the type of chip memory in phones the storage of data is written into the memory in a different way. As far as I know, there is not a physical change that you could see from the outside."
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7edja4 | How is music remixed? | I cant wrap my head around how people music so deeply. How can you isolate and edit/remove certain lyrics or instruments? | Technology | explainlikeimfive | {
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"When you record music in the studio, you record a bunch of different audio tracks (anywhere from 4 to over 100) and then mix those together to produce a final track. A proper remix starts with these raw unmixed tracks and then cuts them up, adds a few new pieces and creates a new song out of it.",
"Everything is recorded individually. So you have everything separate then mix it together.",
"Musician and producer here (amateur). I'm assuming you want to know how people without access to the original multitrack master recordings might do it. IE amateurs. There are several tricks to creating the parts to do a remix or mashup. The short version is that it is possible to replicate certain sounds, purchase the same samples or instruments that the original artist used, find and obtain acapella or instrumental versions of a song, or simply edit and process the original track to obtain different parts of the song like bass, solos, vocals, etc. I'll rank them from easiest to hardest 1. Technical trickery and available acapella or instrumentals. Find acapella or instrumental versions of a song. Using phase reversal, take one, or the other and add it to a track along with the original song and synced up. Since the two tracks are out of phase with each other, you end up hearing the two parts cancel out, and only hear whats left. IE get an acapella vocal, reverse phase, mix with original and you end up with an instrumental with no vocals. Re-render this to a new track and use along with the acapella and you got the lyrics and music separated. Another trick for getting vocals is that they are often in the center of the mix. So if you take the left channel and reverse it's phase, it tends to remove vocals from a track, leaving just the music. You can also do the opposite where only the center channel (vocals) is kept and the music is removed. 2. Re-do the song. Find out what instruments were used to make the original track or come up with your own sound alikes and use to make a backing track. 3. Editing mastery. Using low and high pass filters, filter the original track to remove any frequencies that don't belong to the parts you want to re-use. IE if you just want the bass guitar, you add a low pass filter to isolate it. You can also snip little clips of the song to remove drums or other instruments etc. Like say the beginning of the song has the drum beat with a bass guitar. The drums repeat, so using several sections where the bass plays over some notes in one section, and other notes in another, you can get the cleanest drums from each section to re-assemble into a clean loop with no bass guitar. This can be done for any part of the song provided there are reasonably un-busy sections of the song and enough sections of it. Some parts are in the left or right channel only, which helps isolate them as well. Using those techniques, you establish some parts you can use or re-use and then you can add additional instruments on top of it by tempo matching the source material. Tempo matching, along with re-sampling or slicing, allows the original samples to be sped up or slowed down without affecting pitch. Since many bands use stock synth sounds, or drum machines, samples, etc, it's often possible for an experienced producer to create a new arrangement using the same, and re-creating the song from scratch, then using either an acapella version, or carefully processed vocals from the original to add that element back. I used all of these techniques in[ this Queen - Lady Gaga mashup]( URL_0 )"
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7efz23 | What stops pop up ads and viruses from simply making the "no" or "cancel" button take users to the same place as the yes button? | Technology | explainlikeimfive | {
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"Nothing. Personally, I never click popups. You can easily get rid of them by: - F12 (open devtools) - click the \"Select Element\" button (top left of devtools, looks like a mouse cursor) - mouse over the popup so it is highlighted and click (won't trigger a normal click) - adjust if the popup is inside an iFrame or similar - right click the element and \"delete\" - profit. (With practice, this takes me ~1-2 seconds) Edit: Apparently this can be brought down to about 15ns using /u/ajgz 's shortcuts below :)",
"Below is one reason why they can't do this. There may be workarounds or other methods I'm not aware of. To hijack your browser and prevent you from closing the tab most of these companies use an alert window which is different from a regular popup. This window is a terminal event you must interact with it before you can do anything else. This window is actually generated by the browser not the website you're visiting. So the website can launch the window but can't really control what happenes if you press cancel (the browser handles that)",
"Nothing. Plenty are simply an image link and will direct you regardless of where you click. It's why protection with Malwarebytes and uBlock Origin is so essential."
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7egb4u | Why does Apple not build its own manufacturing plants? | if Apple is having so much trouble sourcing enough iPhones to meet demand, and labor issues in third-party OEMs routinely cause bad press, why hasn't Apple already used it's massive cash reserves to build some insane mega-manufacturing plant where everything is in sheer white and Jony Ives' voice floats softly out of loudspeakers at all times? Why does Apple not follow the Tesla model of designing the manufacturing process itself when Apple is so clearly committed to vertical integration? | Technology | explainlikeimfive | {
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"Money, it's all about money. They are not making products out of the goodness of their hearts. It's to make a profit, and so far they have ran the numbers and they would make more how it's currently operating.",
"Apple doesn't make anything that requires them to build their own cutting edge manufacturing plants. They can just buy parts from other people & send them to Chinese factories for assembly. When you're dealing with something commoditized, like LCDs, mobile semiconductors & electronics assembly, it's far cheaper to contract it out and let people complete for razor thin margins on it. Compare this to Intel. They need to spend billions of dollars building factories every few years because they're pushing the envelope of semiconductor manufacturing & are years ahead of the #2 company in the industry. A big part of what they offer the market is having the absolute best tech."
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7egs4l | What’s the purpose of a distress signal on submarines, if we can’t locate them once it’s been used? | We've all heard the news about the Argentinian submarine which has gone missing. I am just wondering, as they have sent a distress signal, but we don't seem able to locate them, what the purpose of the distress signal is? | Technology | explainlikeimfive | {
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"Think of the distress signal as someone yelling out \"Help\" really loadly into the night, someone hears them and calls the police. The call doesnt tell you exactly where they are, but it does tell people to start searching and gives an approximate starting location.",
"If they never send a distress signal, how would anybody know that they need help? Also you can locate the radio source, but they have probably been moving since the sent it out, thus making it hard to find them.",
"It would appear they didn't send any distress signal. Perhaps the EPIRB wasn't deployed or malfunctioned."
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7ehdo9 | Could someone explain network encapsulation and how data is split up into frames and packets? | I've recently been set an assignment where one of the questions goes along the lines of "how is data encapsulated and split into packets and frames?". The teacher hasn't really given a answer to this so can someone give a simple explanation for me to base my answer off? | Technology | explainlikeimfive | {
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"So in general when people talk about the network stack they use the [OSI model]( URL_0 ). You can think about it this way, at one point you have a piece of data on your computer and you want to send it to another computer. In order to do so, your data has to traverse this so-called network stack. Each layer of this stack has different responsibilities and so requires its own header or metadata to be added to the original message. Adding this extra information at each level is called encapsulation, removing it when it arrives at the destination is then de-encapsulation. So we've started at the application layer. Then you walk through the steps of sending the message. First you add any application layer metadata you want to add (like a REST header). Then you add whatever information you need for the presentation and session layers, but at this point it's still all part of the data layer. Next you move to the transport layer. This is where the message gets broken up into packets (technically datagrams packets). Each packet has a TCP or UDP header added that contains information about where the packets need to go and how to reassemble them at the destination. The data is broken up into packets at this layer so you can \"fit\" the data into the network. Now we move to the network layer. At this layer you're working with routers and IP addresses. Basically this layer moves the packets around between networks. Next is the data link layer. This layer is what handles communication between two nodes on a network, say between two routers or a computer and a router. It's purpose is to guarantee the message gets across a single wire without errors or data corruption. Messages are broken apart into frames and each frame contains an ordering number, so the layer can tell if the message got across successfully. Lastly is the physical layer, which is just the electrical signal carrying the data. Here you add error correction bits to the data. _Now_ that you finally have each lower layer's data encapsulating the upper, your message is ready to be sent across the wire as electricity. When it arrives at the destination or intermediate hops, the headers are successively stripped as you work your way back up the layers, until your message arrives at its destination application (layer)."
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7ejt7j | Entities - Databases | I'm starting a computing course and cant get my head round the concept of entities in databases. If i had a flat database that i needed to turn into a relation database with the headers: Surname, Firstname, Venue, Price, and Length of stay what would the entities be and why? I'm pretty sure 'Customers' would be an entity with Surname and Firstname as instance of the entity but what would the other be? Thanks! | Technology | explainlikeimfive | {
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"An entity is a thing. You make tables in a database out of entities, each row ideally represents an individual entity. In your case, what is the table storing? Customer information? Order information? Venue names? It's not clear. Ideally you'd have a table to represent Customers, Venues, and Orders, all are \"entities\". So you'd have a table, Customers. Customer ID - Last Name - First Name - Contact Info, etc. a table, Venues: Venue ID - Venue Name and a table, Orders: Order ID - Customer ID - Venue ID - Price - Length of stay The benefit of a system like this is if you want to change a customer's contact information (or name) you do it in one place. Same if you want to rename a venue."
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7ekxr0 | What's the difference from an Ethernet Switch and the extra Ethernet Ports on the back of my router? | I know what a switch does, and why its useful, but on the back of my router/modem provided by my ISP, there are other Ethernet ports that I can hook up my computers to for wired connection. Is that a "built-in" switch? Also, do most home networks not use switches? when does a switch become necessary? when 5+ devices are on ethernet? 10+ devices? | Technology | explainlikeimfive | {
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"Exactly, it's a built-in switch. Your home router/modem is actually a router, a modem, and a 4-port or whatever switch in a single unit. Most people don't have that many things that need or benefit from a wired connection nowadays, with wifi being so popular. So those 4 ports are usually sufficient for most people. Those that need more ports would have a switch. A switch is simply necessary when you have more things to plug in than you do ports."
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7emc0f | How can I get electroshocked while building a computer, even when it's all turned off? | Technology | explainlikeimfive | {
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"Capacitors are things that hold a charge after the computer is turned off. Capacitors slowly lose their charge, but it takes a while. Some capacitors can be deadly."
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7en65q | How do (usually paid for) fake social media likes, favorites, and followers actually happen? | I often see advertisements for tools to rapidly gain likes, followers, plays (on soundcloud), or additional methods of clout on various social media sites. What methods do these programs use to make this happen? | Technology | explainlikeimfive | {
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"It's actually generally not controlled by a computer program, but sadly but people in countries with low wages, typically like Indonesia or sometimes the Philippines. Companies hire people and pay them very little to click \"like\" or \"follow\" or whatever on thousands of people's page/groups/companies/etc. that have paid for the likes, but as this takes very little time the workers can often follow hundreds or thousands of new links a day. Keep in mind that they will have little or zero engagement in the thing they've liked, which often hurts people on Facebook more than it actually helps because of how the programming is set up."
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7end7k | Why is the Internet governed the way it is? .... How did it become controlled by a handful of companies? And also isn’t there a way to get internet without these big companies and their contracts? | Technology | explainlikeimfive | {
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"Its more or less always been that way because the Physical infrastructure needed for the internet is very expensive. This causes something called a natural monopoly where very few companies can pay the needed cost to start up an ISP. Natural monopolies arent even rare and usually aren't too much of a problem due to large amounts of government oversight. Water, Gas, and Electric companies are all examples of natural monopolies and thanks to constant government oversight most people dont think about them as a monopoly. Alternatives to the current set up for the internet all have problems. The internet is very large, and decentralized internet isn't quite practical on a global scale(yet).",
"This fully depends on where you are, and who paid or the infrastructure to get internet to your house. Different nations have different rules and histories with internet infrastructure, but if you are in the states and only one company paid to put down wires to your area then you are sorta fucked. And infrastructure is expensive, thats why its only a few companies, who were mostly telephone companies before that (because they had the capital and existing infrastructure to be viable).",
"Imagine the internet like a tree. To go from one leaf to another, you need to travel up the branch and join with other smaller branches until you reach the trunk, then reverse the process to get to the other leaf. The internet is physically built this way, a bunch of cables connecting Tier 1 ISPs to Tier 2 ISPs to Tier 3 ISPs all the way to the end consumer. If you wanted to become a Tier 1 ISP, you would need to lay millions of miles of cables and make deals with the other Tier 1 ISPs to access their data. Even if you built your own internet-capable satellites like facebook or google, you would still need to negotiate with the Tier 1 ISPs to access the rest of the internet outside of your satellite network."
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7engdb | I'm told that if you delete data from a computer, it isn't *actually* gone, and is recoverable - so if the freed up memory can be used for new data, how is it possible given storage capacity limits? | Technology | explainlikeimfive | {
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"Imagine it like a whiteboard. You write information on it, and anything you want to keep you write next to it 'do not delete'. When you finally dont need this data anymore you just remove the 'do not delete' message. This doesnt mean the information you wrote on the board is gone, it just means that when you need to write something new you can wipe it and write the new thing over it. When people say it is recoverable what happens is they put the 'do not delete' message back and the computer can read it again. To ensure that data is really gone there are programmes that write junk messages over the data several times so that even if you put the 'do not delete' message back, the original contents arent there, or are badly over written.",
"Think of your file system as a book. To make locating and organizing the files faster and more efficient, every file is listed in the table of contents. This way the computer only needs to look at the table to locate the file rather than flipping through the pages. This also means that all file management is handled by that table of contents. Moving a file is just changing it's place in the table, the actual pages it's stored on don't change. Deleting a file just removes it from the table of contents, the information on the pages is still there, but the table says they're blank. Since the computer relies on the table to tell it the state of the pages, it assumes those pages are empty and will over write them. you can use certain programs to ignore the table of contents and go directly to pages marked empty and read whatever data is still there, this is how the data is recoverable, however this only works when the computer hasn't over written the data.",
"Data can only be recovered for so long after something is deleted, and its very possible to delete something permanently off a drive. Basically when you \"delete\" something it just pretend that the data isnt there and will write new data over it in the future. Once data is written over it the original data is gone forever and can never be recovered. Until the data is written over though it is treated as empty data, but if you really tried to read that portion of the drive it would pull up whatever was saved there."
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7enrdx | How do "text x to xxxxx" numbers work? | Technology | explainlikeimfive | {
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"at least in the US, these are called shortcodes, and you buy them from [this company]( URL_0 ) which has agreements with all the telecoms to support these numbers. as to 'how do they work,' well it's no different than a normal phone number as far as how you interact with the phone network is concerned as the user/provider of a shortcode. they are really expensive to acquire compared to normal phone numbers and fun fact: every single one of them supports texting STOP to the number to opt out of receiving any more texts from it. supporting this is a requirement of the contract you sign as a company to acquire one of these numbers (or at least was when i looked into it for the company i worked for). source: worked at a company where we briefly looked into buying a shortcode to use when sending text message based notifications to our customers, and decided it was not worth it at all.",
"Could be completely wrong here but I am quite sure it works with partnership with a cell company. The cell company can make any numbers they wanted to and the show is partnered up with them to split up the profits from the phone calls and text messages like 60-40 or something which is still a stupid amount of money. It basically forwards < contents of a text message > to a shortened phone number that moves to a program, that takes the contents that text message and tallies it up with whatever contestant it is. For Example: `if < contents of text message > is \"resist\" then` ` votes_of_person gets incremented by 1`"
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7ep6x2 | I thought the internet was a series of interconnected routers and computers that communicate however they want. How does one institution in one state control this communication even for people in other parts of the world? | see title | Technology | explainlikeimfive | {
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"The internet is mostly run by companies who own infrastructure (like wires and shit). The institution you're talking about (assuming the FCC) gets to decide what these types of companies are allowed to do. Right now they are FORCED by the FCC to treat all traffic equally. We are worried that the FCC will change their mind and no longer force these companies to do this and thus the big greedy companies will do more greedy stuff. The reason it effects the world is because the US is big and rich and important so stuff that happens here has consequences elsewhere. That doesn't mean that this decision changes how the law works for everyone. Some countries already have service providers that do exactly what people in the US are worried will happen."
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7epz9n | In networking, what is the difference between a router and a hub? | Technology | explainlikeimfive | {
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"A router operates at layer 3 of the OSI model. It handles IP addresses, and decides where packets go based on the IPs store in the TCP or UDP packet headers. A switch operates at layer 2. It handles packet movement based on MAC addresses, which are physical addresses of interfaces as opposed to software defined ones like an IP address. A hub operates at layer 1. A hub is sometimes called a repeater, because that's exactly what it does. It takes any incoming signal on one port and replicates it across all other ports. It doesn't do any fancy logic. If your machine is plugged into a switch, you will receive only packates destined for your MAC address. If you are plugged into a hub, you will receive all packets destined for any device on that hub. Your machine will intelligently discard them, unless you want to keep them to... say, sniff someone's traffic. Very uncommon though. Pretty much everything you see nowadays is a switch or router. Your home router is actually performing both the router and switching functions in one, bit the differences in the 2 types of devices become very important in enterprise networking. Check our /r/networking for more info.",
"You can look at a hub as a kind of intersection in a busy street. Every vehicle can come in and go anywhere they want to. Except in a hub all of the vehicles that come in go to every street that is connected to the intersection. A router is like a smart traffic guard. They look at the vehicles that come in and tell them where to go, according to their destination. So hubs send messages they receive to every client that is connected and a router only sends it to the intended recipient.",
"The eli5 version: Assume you're sending a letter to your buddy who lives a few cities over. The mailman is the switch. His job is to pick up local mail from mailboxes ( aka switch ports ) and take it to the post office which would be the router. The postoffice looks at your addressing on the envelope and sends it off to another postoffice somewhere else. Each postoffice it passes through looks at the address on the envelope. If it doesn't recognize the address, the letters journey continues on to the next postoffice. If it does recognize the address, it gets handed to the local postman ( the switch ) and is delivered to your mailbox ( the switch port ). While beyond the scope of an eli5 explanation, know that the postmans job and the postoffice can be combined. This is known as a layer 3 switch which can do both jobs. Sort of like taking your mail directly to the mailboxes that are at the post office itself."
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7eq094 | How is it possible that ISP's can see what your up to online? I thought HTTPs encrypted your traffic so it can't be read? | Technology | explainlikeimfive | {
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"Sorta. The ISP is your mailman. They need to get packages to where they need to go, Reddit for example is sending you a package containing this reply. You pay the mailman monthly for a rate at which they send packages from you and to you. HTTPS encrypts the package’s contents, however the ISP’s responsibility is still to move the package from A to B, and therefore needs to know what these A and B are. Therefore the postage address cannot be encrypted, and your ISP can track who you are exchanging packages with, be it Reddit or YouTube or Netflix. So your ISP can’t actually see what you are viewing on Reddit, YouTube, or Netflix, but they can see which sites you are accessing.",
"HTTPS is not a perfect solution. It prevents them from seeing what messages are exchanged but not from seeing who exchanges those messages. They can see that you are on reddit but not which subedits you are viewing for example. There are additional things they can see. For example some researches a while back for example showed that you could still recognize which movies a person was watching despite them being transmitted via https. The transmission itself was encrypted, but observers could still see the size of the packets transmitted and match those with what they new about the movies in netflix's library. So https is good for not having the entire world see your password when you transmit it, but if you don't want your ISP to know that you are visiting URL_0 they won't help you at all and in some special cases they might in theory learn much more about your browsing habits than you would want them to.",
"I want to point out that my isp actually will perform man in the middle attacks to send copyright notices. I was torrenting one night and my browser wouldnt connect to https reddit. After a few seconds i got redirected to a 'copyright violations are bad, click here to restore your internet' page. Realistically, i should be able to charge them under the CFAA for that. I couldnt believe they would stoop to MITM for copyright.....",
"Your ISP doesn't know what you ordered from Amazon, just that you got a package from Amazon. This becomes an issue when you order a package from URL_0 , and there is little doubt as to what you're ordering.",
"It sort of does. Your ISP cannot read HTTPS data you send or receive (for the most part) But when you send data, they can see where it's destined for. When you receive data, they can see where it came from. So they can generally tell which websites you visited. But they can't tell what you *did* on those sites. There are a couple of ways they can *sometimes* snoop on your HTTPS traffic however. If you install one of their certificates, they can potentially act as a man in the middle, reading everything you send and receive. But that requires you to manually install this certificate. It can't be done silently just by visiting a website. Alternatively, if the website has a non-HTTPS landing page, they can potentially manipulate that so that you are never forwarded to the HTTPS version. But yeah, assuming your PC isn't compromised, and the *entire* site runs HTTPS, then the ISP can only tell where data packets are going and coming from, not what's in them.",
"They can see the volume. If you go to Pornhub for example and watch a video, you are going to pull down data from the video yeah it is encrypted, yeah it is streaming. If the video is exactly 14,586,304 bytes how many possible videos on the site are exactly 14,586,304 bytes? Even streaming wise with enough sample data you can peg what they are streaming. Go to a download site, same thing. I can't tell what you downloaded but I can see how much you downloaded. How many possible files on the site match the size? The ads are a different connection and unless a website has a substantial random amount of data on each page, it's easy to gauge what you are looking at. You can never get 100% but you can say \"Out of 6 million videos there is a 98% chance he watch video A, 87% chance it was Video B, and 76% chance it was video C.",
"Related: On March 28, 2017 congress passed legislation (bill: H. Res 230) that legally allows your ISP to track, store and sell your internet surfing history to ANYBODY who pays them money. This legislation was also passed basically \"under the radar\" just like they are trying to do with Net Neutrality. The bill was passed because 50 Republicans voted for it. On average a Republican received $368,648 from the telecom industry during their careers [ URL_0 ].",
"So my friend who owns my ISP knows what kind of porn I watch?",
"They know the IP address you’re sending/receiving information from, not the content. Quite literally just like properly addressed mail through the post office.",
"I work at an ISP and we can’t really see what you’re doing. We can see where packets are being sent, what time they’re being sent and who sent them, but that’s it.",
"They can’t see inside the HTTP session, but can inspect the entire TCP/IP packet. So, they don’t even know the host name in the HTTP header ( URL_0 ), but they can see the source and destination IP addresses. The mailman analogy works.",
"If someone moves your data for you, they get to read it. It's the same issue with Tor. No outsider can read it, but it is possible for outsiders, if they're creative enough, to become insiders. There's a small scene in Mr. Robot that talks about this briefly. I think it's actually in the pilot.",
"I've always thought of the post card anology. In http You exchange information with a web site in post cards. Everyone who handles your post card can read it. With https it's like using an envelope. They still know the address but not the content. The main thing to remember is that the website address is still visible. ~~So even if your communication is encrypted going to https: URL_0 /r/Am_I_Pregnant tell the ISP a lot~~ with https only URL_0 is visible thanks to /u/ChoilSport for pointing that out",
"This is the best link I have ever seen. URL_0 Basically, when you send information, like others have said, it gets put into a package, like a box. As the box goes from device to device, each device can add a box and put a sticker label on it. Some devices open the outer box package to read the label on inner boxes. Kinda like how you can recognize a home depot box, these labels and boxes are recognizable. And because it's all electronic, it's easy to build a software that can open and read those quickly and do all sorts of analytics. The very inside package might not get opened, but there's a lot of info you can gather to make very educated and statistically proven guesses in the worst case scenario, and when you compare it directly to other known packages from non encrypted sessions, it becomes a matching game.",
"I was actually looking into this the other day after my internet was slowed the day after I made a huge download. Turns out it was unrelated. However I found some interesting info about how service providers can determine your online activities without actually seeing the queries of your URLs. For example, when you're streaming a video, there is a specific bandwidth usage pattern that is easily distinguishable from downloads and stuff. [Here]( URL_0 ) is a diagram representing streaming network traffic pattern. When a video is buffering, it's pre-loading part of the video so that it can be viewed without any hiccups. Normally videos will give around 15 seconds of buffer time. When the video comes too close to the non-buffered part of the video (the rest of the video) the bandwidth will be used once again to buffer the next 15 or so seconds of the video. This results in a choppy, zipper-like bandwidth usage pattern. (See the hyperlinked article for a diagram). While service providers might not necessarily be able to see what you are viewing exactly, by combination of the general address of the website, and the bandwidth pattern. They can usually make a pretty good guess as to what you're up to. And with all the data they are collecting at the same time, it's only becoming easier. Edit: replaced link to article to simply just a link to the diagram"
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7erm40 | Off Camera flash Duration and Shutterspeed | I've been reading about off camera flashes for a while now, but can't seem t figure out the whole logic behind the flash duration and it's relationship with the shutterspeed. I understand that t0.5 (t0.1) means the amount of time it takes for the flash to lose 50% (90%) of it's power, so if you want to freeze action it's best to have as short t0.1 as possible (does it depends on the max power too?) , What exactly would be a good t0.5 and t0.1 and how do you connect it with shutterspeeds? I've also been looking into [these flashes]( URL_0 ) for a while now and connect the theory with the written specifications as well. Anybody that could clarify? | Technology | explainlikeimfive | {
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"The flash duration and shutter speed are independent. However, many cameras use a double-curtain shutter, or electronic rolling shutter. The effect of these shutter systems is that at slow shutter speeds, the whole sensor is active, but at faster shutter speeds, only part of the shutter is active at any one time, and the activation travels over the sensor in a (relatively) slow fashion. If you use a short duration flash, together with a short shutter speed on such a shutter system, then the flash will only illuminate part of the image. So, to get around this, cameras have a specified minimum flash sync shutter speed, which is the fastest shutter speed where the whole sensor is active. (1/75 for older mechanical cameras, faster these days). The electronics in the camera would trigger the flash at the point when the shutter is fully open. Some cameras and flash systems, offer a special \"fast sync\" option, which allows the flash to illuminate the whole image at very fast shutter speeds - but what these actually do, is lengthen the flash duration so that the flash remains active for the whole shutter cycle (t0.5 = 1/50 or 1/75). In general, the faster the t0.1, or t0.5 time the better the ability to freeze motion. The speed you need depends on what you are photographing, how much motion there is in the scene, how fast it is, how close you are cropped to the motion, and how much blurring is tolerable. As a rough guide, 1/500 will freeze most human movement, except for things like the the feet in a runner or dancer; 1/1000 will be often adequate for ball sports, but 1/2000 may be required in certain conditions (e.g. close cropped shots of tennis).",
"It's been a while since I worked as a profession photographer, but here's what I remember from a couple years ago – Most modern cameras have a traveling shutter system. In essence there are two \"curtains\" – at the start of the exposure the first one is closed, then it opens all the way, then the sensor/film is exposed, then the second curtain slides over to meet the first curtain, ending the exposure. Both slide back to their initial positions (remaining closed the whole time). If you're using a flash, you want to fire the flash at some point while the shutter is fully open, so the flash has to dump its light during the open part of the exposure. This works pretty well up until faster shutter speeds, usually at 1/250th of a second (but higher or lower in some cameras). Beyond this point – the flash sync speed – the second curtain will start to close before the first curtain is completely open. At very high speeds what's really happening is that a narrow moving slit exposes the sensor. This allows for fast effective shutter speeds – 1/2000 – but there's no point at which the entire shutter is really open at once. If you fire the flash at these higher speeds (say, 1/500th on a camera with a 1/250th sync speed) only part of the sensor will be exposed to the flash's light. Fortunately, a \"high speed sync\" system allows the flash to be synchronized – I think through a system of lower power pulses - while the slit travels across the sensor. If the strobe takes 1/500th of a second to discharge 90% of its power, though, an exposure of less than that won't be able to get the full power of the flash. If you're using key flash (strobe provides the primary illumination), then you can treat the flash discharge time as if it is the shutter speed: set the camera for an exposure at the sync speed or below, dial back the ambient light to minimal, and fire away. If the flash takes 1/500th of a second to discharge 90% of its power, and you set it to full power, it's equivalent to a 1/500th exposure."
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7escds | How do Car Keys hold their charge? Do they get charged by the car? | Technology | explainlikeimfive | {
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"The battery holds charge like any other battery, it just lasts a long time because it uses so little electricity. You can open your key fob and change the battery if it runs out.",
"It's just a normal battery, it just doesn't take much juice to send the unlock pulse. Eventually they do run out, it just takes a long time.",
"it doesn't. it eventually runs out of battery. the circuit is very low powered and only turns on when you transmit the unlock button and the battery holds enough juice to last many years.",
"As others have mentioned, the battery does eventually die. You should know that if that happens, you're not stranded: you can almost always still drive the car. For instance, on my car (Toyota Prius), the key fob has a little latch that releases a mechanical key that will open the door, and if you hold the key fob against the car's power button, it will start even with a dead key battery. Check your owner's manual, just in case!"
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7eupo2 | How can different image file types differ so much in size for the same content even though visually there is no difference? | Technology | explainlikeimfive | {
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"The difference is how they store and compress the data. One format may use 24 bits per color per pixel. Another may use 24 bits per pixel reducing the number of shaded available. The next might use compression to store the data. With my camera a raw uncompressed file is up to 50 meg. Same image in jpeg is 5 but I have more useable information for editing with the raw file."
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7ev81e | When there’s a mirror scene in a movie or television show, how do they get the shot without showing the camera in the mirror, especially with a head on face shot? | Technology | explainlikeimfive | {
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"The \"head on\" face shots are actually shot at a slight angle. So the actor is looking at the camera in the mirror, and not at themselves. And in cases where it's absolutely impossible to shoot the mirror at an angle, they just edit out the camera using computer software in post-production.",
"Usually with rotoscoping, that is painting the camera and crew out of each frame with tools like photoshop. Shooting at an angle is another good one. James Cameron in T2 used a window and a 'mirrored' duplicate set. Sucker punch used body doubles.",
"They dress the camera up like the actor, throw a tie on it, and hope that you don't notice.",
"Sometimes it’s not actually a mirror but an opening into another room and they use doubles to compose the shot. They did this in Terminator 2 before computer trickery was good enough using Linda Hamilton’s twin sister."
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7ewwjh | What's the difference between UEFI and BIOS? | Technology | explainlikeimfive | {
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"UEFI is the replacement specification for BIOS - it does the same basic role of bootstrapping on launch, but BIOS has a host of technical limitations owing to the fact that the original specification is nearly 30 years old and unable to work with some modern hardware (for example, BIOS can't work with a hard disk of over 2.1TB). An easy illustration - any newly built computer that boots into UEFI will have usb mouse support. No such luck on an old AwardBIOS.",
"Every computer needs some *firmware* that tells it what to do when it first powers up, before it starts loading the operating system. The firmware for the original IBM PC was called BIOS. Every x86 PC clone since then has been designed to be backwards compatible with it and suffers from a bunch of limitations due to that. At least until UEFI came out. UEFI is a modern replacement for BIOS, designed from the ground up, based on the needs of modern systems. For starters, it can be a larger program - this allows you things like a GUI, the ability to go onto the network to get updates & room for a bunch of diagnostic/repair tools."
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7ey3t3 | Why SMS messages cannot come in Bold/Italic/Underlined, etc | Technology | explainlikeimfive | {
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"Technically, they can. But the support for such formatting has to be widespread and unified between phone hardware manufacturers for it to be useful, which is obviously not the case now. Also, the SMS protocol has been designed with a limited message length in mind, adding the formatting would make the message even shorter."
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7f0dzx | how do shopping cart anti-theft wheel locks work? | Technology | explainlikeimfive | {
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"There is a braking device inside the wheels which contains a radio receiver. Around the boundary of the store grounds is a transmitter loop, much like an invisible dog fence, putting out a signal. When the cart crosses the invisible fence, it receives the signal from the transmitter and triggers the brakes inside the wheel, locking it up."
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7f51sj | How do the ridges and bumps on a record translate to the music we hear? | Technology | explainlikeimfive | {
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"Talk means sound Sound means vibration in the air Vibration is little wiggles (think of glass shaking on a plane) If you put those little wiggles through a needle onto a surface that's soft, the surface will keep a \"record\" of the little wiggles. Next, harden the surface with the wiggles on it. Put the needle back on the wiggly surface except this time have the pattern of the wiggles coming through the needle be amplified out. Voila, a record.",
"What I don't understand is how we can record audio if everyone has a unique voice? How is there enough variation in the waves/trough to record every unique sound?",
"Imagine a speaker playing music. The cone goes in and out to make the sound. Now, imagine attaching a needle to the base of the cone so that it also moved in and out. Now imagine dragging sheet of wax under that needle. You would be left with a bumpy groove that exactly describes where the base of the cone was at each instant in time. If you could somehow freeze that and drag it under the speaker again at the same speed, the cone would move back and forth exactly the same way it did while it was creating the recording. This is exactly how records were created and played originally (except that they didn't really have speakers...the needle was attached to a diaphragm and the amplifier was just a big horn). Eventually to improve dynamic range and amplification, they replaced the diaphragm with a magnetic coil which actuated another magnetic coil in the speaker. This, in turn led to stereo where instead of one bumpy track at bottom of the groove, they could have two tracks on the sides of the groove."
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7f6hs7 | What is Artificial neural networking? | Trying to do a presentation for college. Can't make sense of the topic. | Technology | explainlikeimfive | {
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"Neural networks are a software based problem solving tool that are inspired from how the brain works. Brains are made of neurons, which are connected to each other to send electrical signals. Each neuron makes a small change to the signal before passing it on and somehow eventually the signal becomes the answer. Neural networks are like that. They are made by arranging a large numbers of really small programs in a network. Each small programs can only change the answer it got from another small programs in a tiny way. So you start with a lot of presolved question answer pairs. Things like (2,2 =4), (1,4=5)....etc. and now you make the tiny programs modify what they will do to their answers again and again millions of times until you start getting the right answer. This is called the 'training' stage. If all goes well, the network of small programs will end up such that even when you give it a question it never saw before (1,3?) , It will come up with the right answer (4). The neural network has *learnt* addition. Even though you didn't exactly tell it to add, whatever the tiny programs have ended up doing, the net result is that they do addition. This becomes really useful for complex problems when we have only question answer pairs but have no idea how the answers are derived from the questions. Like how the temperature and wind are related to storms. Neural networks pick up patterns in such problems (even if we don't see them) and give us the right answer."
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7f743l | Where does the internet come from? | Technology | explainlikeimfive | {
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"The internet is a network - thus the name. Its devices from all over the world connected by cables basically (some by wifi signals but only locally), some of which are servers (hosting content) and some are clients (accessing content) or a combination of both. You can become a service provider for example by providing space/servers to host data (cloud service providers, for example), or by selling access (aka cables) to end users. How you become an ISP also depends on where you live and how the market is or isn't regulated by your local government.",
"Your ISP buys their internet service from a larger ISP in bulk and splits it across all their users - think a taxi company buying a car, it is in use a lot more than a private car and if the taxi company has enough cars it's like everyone having their own. When you get to the biggest ISPs, they can't buy internet from anyone - instead they have what are called peering arrangements with each other that say if my customer wants data from your customer, it will go over this link. If the data flows are roughly symmetrical, this is often free. If not, there will be a charge (it's one of the reasons Netflix has caching near customer endpoints so data doesn't have to go over as much of the wider internet). An individual becomes an ISP by getting a connection big enough to support multiple customers that permits resale and getting some way to share that connection with the customers. The simplest way is to set up a WISP, a wireless ISP, which needs a tower with good visibility and some equipment on the tower and the customers home."
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7f76xa | How can a program teach itself to play a game like mario cart? | Technology | explainlikeimfive | {
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"text": [
"Software that learns how to play a game is usually based on a machine learning technique called 'reinforcement learning'. The problem with learning games is that you don't immediately know wheter a certain action or turn will lead to success (Imagine Go or Chess), so you lack labels for unique actions in the game. So you need a different approach - the reinforcement learning: A reinforcement learning program interacts with the game in time steps. At each time, the program receives an observation which typically includes the reward (like which rank, how many points it got) It then chooses an action from the set of available actions (randomly, or based on previous rounds or actions). At the next time, you see whether this improved, decreased or held the reward. When the programs performance is compared to that of an program that acts optimally or really good (e.g. a good human mario player), the difference in performance gives rise to the failure or 'regret'. In order to get better at the game, the program must 'reason' about the long term consequences of its actions (i.e., learn patterns that maximize the end result).",
"So if i run a program like that and go to bed. The program would have improved while i was sleeping?",
"The program needs to have some concept of whether it did good or bad. And then you tell it to, through whatever means necessary, maximize doing good. Basically, the same way you learned to play Mario Kart. You learned how to deal with sharp turns by playing it over and over until you had good strategies (\"good\" being measured in \"improving my overall speed\")."
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7f95gf | How do laptops stay on when unplugged if it says the power source is from the adapter? Would't there be a moment of no power when switching to the battery? | Technology | explainlikeimfive | {
"a_id": [
"dqa8tqu"
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"text": [
"1. (not necessarily in the case of your macBook, but) a lot of mobile devices _always_ run from the battery. Plugged in means the battery is constantly recharging. Which is not necessarily good for the battery, which is why a lot of laptop vendors will say don't leave it plugged in for an extended period. Run on battery, recharge. In fact I was just looking at Dell's support site for this. 2. the power supplies will have some kind of super capacitor in them which is capable of holding enough charge for just long enough to switch between AC and battery. And the switch really can happen near instantaneously, like milliseconds or faster."
],
"score": [
6
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|
7fb96t | why is it hard to reproduce metallic colors (shine) accurately on display screen? | From Wikipedia (silver color): > there is no mechanism for showing metallic or fluorescent colors on a computer without resorting to rendering software which simulates the action of light on a shiny surface. is it because silver (metallic) is not a wavelength? | Technology | explainlikeimfive | {
"a_id": [
"dqansf2"
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"text": [
"That's exactly the case! \"Shiny\" isn't really a color so much as how humans interpret the brightness as reflections. To see for yourself, find a picture of something shiny. Google image search, or screen cap something from a game. Now zoom in really close to the shine. It's probably some variant of grey. If you have a color copy tool, usually a dropper in Paint, take that color and fill in a giant block. The color of the \"shine\" should be pretty dull. In terms of absolute color, shine or matte aren't really anything unique. It's rather how the brain interprets the color relative to it's environment."
],
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3
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7fbdju | Why aren't aspect ratios expressed in simplest form? | e.g. 21:9. Edit: of displays. | Technology | explainlikeimfive | {
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"text": [
"I might hazard a guess that its for easier comparison. 16:9 is a common resolution (i.e. widescreen), and 21:9 is marketed as \"Ultra-wide\", and comparing the terms 21:9 and 16:9 you immediate see \"oh, yeah, 21 is clearly bigger than 16\". If you reduced it to simplest terms, you'd be comparing ~~3:1~~ 7:3 and 16:9, and my immediate reaction to those is to actually think 16:9 is wider, despite actively knowing its not as I type this. Also, as said elsewhere, 21:9 sounds more impressive than ~~3:1~~ 7:3, so there's that too",
"For things like gears or cogs, it's how many teeth each wheel has, not a specific ratio. For other stuff it usually is. Do you have a specific example?",
"Because 21:9 makes it easier to compare to 16:9 so that consumers have an idea of what they are getting (an extra wide screen) without having to understand math or ratios that well. The actual ratio is 64:27 (2560x1080 = 64x120 x 27x120) or about 21.3:9 in order to follow 16:9 and 4:3 (4^2 : 3^2 = 16:9, 16^2 : 9^2 = 64:27)"
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7fbtfg | Why does television have so much bandwidth compared to Internet? | Technology | explainlikeimfive | {
"a_id": [
"dqarwzc",
"dqasfrj"
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"text": [
"The advantage television has here is that one signal is sent out by the transmitter, and everyone receives the same signal, and no return signal is needed, and different channels are using different frequencies. With an internet line, every end user is receiving an unique signal. (Also, 1080p is rarely used OTA, it's usually 1080i or 720p.)",
"When you watch a youtube video, YouTube opens up an individual connection specifically for you so that you can watch the specific video you want to watch. TV just blasts whatever they are broadcasting and anyone can pick it up. The benefit of the first option is that you can specifically choose what you want to watch."
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6,
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|
7fd6ci | How do TV shows that post videos on Youtube earn enough revenue to continue existing? | I'm talking about shows like Last Week Tonight with John Oliver, which basically post the bulk of their episodes on YouTube | Technology | explainlikeimfive | {
"a_id": [
"dqb236b",
"dqb26ly",
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"text": [
"Ads. Plus if you like it enough you might actually tune in. If not & you remain on Youtube; ads. Otherwise you wouldn't have begun & they wouldn't have made cash on you in the 1st place.",
"John Oliver is made by HBO. They get their money from investors and from those that pay to watch HBO. The show also gets ad revenue from Youtube and because it is the channel of an established TV network will rarely be demonetized.",
"1) Ads! these work as you think, someone watches ad and you get paid. People as big as HBO may be able to cut special revenue sharing deals with Google and Facebook. 2) Free advertisment. You like a clip and give your friend the youtube, he watches it and may like it and tune in on TV. Bam new viewer. Also if it just happens to come up on the next auto playlist. 3) More free advertisement. You can show up on someone's facebook and twitter feed. 4) Figure out which clips people like. TV kind of sucks at user metrics. Computers are way better, so good it is scary sometimes. They can then adjust future shows."
],
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12,
5,
4
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7fdgrm | Why does audio rapidly repeat itself when a computer crashes? | Technology | explainlikeimfive | {
"a_id": [
"dqb54m0"
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"text": [
"At a high level, sound cards playback sound by reading digital data from a buffer and converting it into an analog signal to transmit to the speaker. When a normal stream of audio is being played back, its data is written into the buffer as a stream so there's no hops or skips - as the digital audio converter scans back and forth over the buffer, the buffer data is overwritten as its being played. If the audio controller crashes but the hardware is still going strong, it begins to simply replay what happened to be in the buffer at the point of the crash, causing the effect you describe. The audio will fully stop if the OS can catch the program going unresponsive and eject it from memory, which frees the audio controller."
],
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29
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|
7fdm4s | why does every website including Reddit want me to use an app instead of their damn website these days? | Technology | explainlikeimfive | {
"a_id": [
"dqb53k1",
"dqb57gq"
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"text": [
"Hmm those apps sit in the background and silently collect user data. All those permissions you give them? Full contact, internet, storage, location access? They dont need all of that to work. They may need some, but they're collecting data silently. And you wonder why there's so much battery drain. After all you've signed your privacy away when you agreed to the permission access.",
"Apps have a lot more permissions and device access than mobile web. For example, your web browser typically will not have camera access, which is why places that want to scan br or QR codes will need to have an app. Apps also can usually access more memory than mobile browser tabs, useful for high memory consumption sites. Spying is a big part of it though"
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3,
3
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|
7fdmdk | how do tv commercials work? | Is there a guy in a room somewhere picking them? Why do some only last a split second? Why are there sometimes 2 or three in the same break? How is the length normally set? Who picks them ? Etc | Technology | explainlikeimfive | {
"a_id": [
"dqb5icc"
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"text": [
"TV commercials are bought and placed into \"slots\" during regular programming. For instance, Doritos or Pepsi or whoever can choose to buy a slot that's open in the middle of a broadcast of CSI or whatever show. Typically companies do a lot of demographic research to see what their target consumer watches (sugary cereals usually slot their ads into kids TV shows, that's an easy example). Likewise, length varies, but ads can be a few seconds up to 15 or 30, typically. The \"split second\" ads that only blink on your screen are probably just glitches, bits and pieces that didn't quite get slotted in correctly OR it's interference from another channel. EDIT: regular network TV shows are generally a half hour or a full hour - a \"half hour\" show is typically 21-23 minutes while a \"full hour\" is roughly 48 minutes. This is standardized so networks can consistently produce their shows. Whatever time is left, that 7 or 9 or 12 minutes, is broken into 3 or 4 ad breaks, and those breaks can be split into segments of 15, 30, however many seconds and then sold to advertisers."
],
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4
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7ffj4s | What is project treble and what does it mean for Android? | Technology | explainlikeimfive | {
"a_id": [
"dqbhvww"
],
"text": [
"Treble separates the vendor specific part of the OS from the Android specific part of the OS. Because there are two separate parts now, the vendor can focus on \"their side\" of the house when working on getting their devices for the major android updates. While before, a manufacturer/vendor (HTC/Samsung vs Verizon/Sprint) would have to rework the entire android OS in many different areas to make it fit their device. Now they'll only have to worry about the driver side, instead of customizing android as a whole. What it means is when a large upgrade comes out (like Oreo), the vendors will be able to get their phones upgraded to the best and the brightest OS faster, only having to do about 1/3rd of the work from before."
],
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3
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|
7fg18d | Why do certain websites load several times in your browser history, so that when you click the back button it doesn't do anything? | Technology | explainlikeimfive | {
"a_id": [
"dqbl3nu"
],
"text": [
"Because they are assholes, and don't want you to leave the website by hitting the back button. BTW you can right click the back button, and choose a location from the history that pops up."
],
"score": [
3
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|
7fhsz7 | Why is it such a difficult task to locate and rescue a malfunctioning submarine at sea and why can't all the sailors escape safely via the torpedo tubes in pressure suits? | These questions came to my mind in light of the recent San Juan disaster. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The ocean is *big*. Incredibly big. And huge swaths of the sea floor haven't been mapped. You're talking thousands upon thousands of square miles to look through, except you can't just look. You have to use sonar instead. Is that roundish bump that showed up on the sonar the nose of a submarine? Or is it just a roundish rocky bump on the bottom of the sea floor? Is the sub not in this area, or was it just in the shadow of a rocky underwater ledge so your sonar couldn't hit it? Is the submarine even still in one piece, or is it in pieces? How many pieces? Did the pieces settle on the bottom together, or did an ocean current drag different sections miles apart before they hit the bottom? Did the submarine continue on a straight course, or did it get caught in a current? Did the engines or props or rudder malfunction, so that it veered off course? When? By how far? You're basically looking for a needle in a haystack after a storm blew your haystack all over the place and also you're not allowed to look for it, you just have to poke around with your finger until you find it, and also it could just as easily be in your neighbor's haystack. There aren't pressure suits on board. You can't carry enough for every sailor, and it would be impractical and expensive to carry the right kinds, especially since at some of the depths a sunken sub would end up in, a suit wouldn't help you. There are hatches and small oxygen tanks and flotation devices to get you out, but you have to get to those. There's no guarantee that the sub isn't already flooded in the corridors between you and any of those things. Sure, you could open up the torpedo tubes, *if* you are close enough to them, *if* that room isn't already flooded, *if* you can get the tubes open, *if* the sub hasn't already sunk too deep for you to escape without help...",
"The ocean is incredibly large. Subs are designed *not* to be heard/found. There are too many crew members. Torpedo tubes aren't designed as escape hatches. There are no \"pressure suits\" to combat the pressure at depth, which is to say nothing of the cold, dark of the water and sheer length of time it would take to reach the surface only to get \"the bends\" (nitrogen narcosis) without anyone, or anything their to rescue them at the surface.",
"Pressure suits aren't carried, but there are escape suits that can be used. The submarine I went to sea in (Oberon Class) was equipped with two escape towers(also known as trunks). These allow one person at a time to escape the sub. It takes time to cycle them, if a boat is sinking in very deep water, there will not be time for anyone to get out before it reaches crush depth. If you are lucky enough to end up on the continental shelf, It is a different matter altogether. The preference of course is to wait for DSRV(Deep Submergence Rescue Vehicle) rescue. If the boat becomes pressurized, or is too deep, then there is a risk of getting the bends. As /r/Geetarzkool has stated, the world's oceans are a very big place, and if something catastrophic has occurred, the beacon a Sub carries may be damaged or rendered inoperative. In a perfect world an EPIRB (Emergency Position Indicator Radio Beacon) is released and will transmit on radio. I do not know if the Argentine sub was equipped with such a device, but we had one, and it was set on a timer that had to be reset every few hours, or it would automatically launch. When things go bad on a submarine, they can go very bad very quickly."
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8,
8
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7fjoli | How come most (or all) TV remotes are black? | I just realised I’ve probably never seen a tv remote in any colour other than black (and I sold TVs for a year). How come? Are they easier to find around the house that way? | Technology | explainlikeimfive | {
"a_id": [
"dqch6zo",
"dqcbr84"
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"text": [
"TV remotes are colored to match the TV they go with. Recently, consumer electronics (such as TVs, stereos, etc.) have all been black. Black is a great color, because it doesn't clash with most home decors. Black has been the most fashionable color for a while. In the 80's the color of choice was silver/grey. In the 70's it was fake wood paneling. (And I've seen remotes with fake wood paneling stickers. Really.)",
"It's only older television sets/VCRs I had that were lighter. Usually grey. I once had a silver TV/VCR combi in silver and it had a silver remote. I'd say when lcds came on the scene was when most started being black. Not sure of the reason, maybe to stop them looking dirty as easily? Stop discoloration (see also: nintendo snes yellowing)"
],
"score": [
15,
3
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7fkabb | How is binary read? Especially the numbers. How is 10010 the number 18? Is there an algorithm or is it more complex like learning a language with letters? | Technology | explainlikeimfive | {
"a_id": [
"dqcgapk",
"dqci86y"
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"text": [
"its very simply read in 'columns'. each column is worth a value. you add the values together anywhere there is a '1'. example; 10010 is actually like 16 | 8 | 4 | 2 | 1 so there is a '1' in column 16, and a '1' in column 2. what is 16+2 = 18. that's literally all it is.",
"The fastest way to learn binary is to *really* learn base 10 (\"normal\" counting). When you count you go 1, 2, 3, 4, 5, 6, 7, 8, 9, *what*? What happens when you run out of digits for one-digit numbers? You wrap around to 0 and put a 1 in the next place, giving 10. Then you go back to incrementing the lowest place value: 11, 12, 13, 14, 15, 16, 17, 18, 19, *what*? You reset the last digit to 0 and increment the next digit again, giving 20. That pattern continues when you run out of digits in the next place value: when you try to count past 99 you need to reset the ones place to 0 and increment the 10s place, but the 10s place is already 9 so you reset that to 0 and increment the next digit, giving 100. When you look at a big number, say 8,675,309 you can recognize that as 8\\*1,000,000 + 6\\*100,000 + 7\\*10,000 + 5\\*1,000 + 3\\*100 + 0\\*10 + 9\\*1. Each place value is worth 10 times the one before, since we're in base *10*. For binary just forget that the numbers 2-9 exist. You start counting and you only get to 1 before you're out of digits. You have to reset to 0 and increment the next place value (the 2s place now). That gives you 10, then you count one more to get to 11 and you're out of digits again. Counting to 8 in binary looks like 1, 10, 11, 100, 101, 110, 111, 1000. With each step you increment the last digit by either turning a 0 into a 1 or rolling a 1 back into a 0 and incrementing next digit (following those same rules). Also, like with base 10, you can find the value of a number by counting up the contribution from the individual digits. The number 10010 is 1\\*16 + 0\\*8 + 0\\*4 + 1\\*2 + 0\\*1 = 16+2 = 18."
],
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13,
3
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7fm5ku | How do they make 100 year old pictures look like they were taken yesterday, also, old movies, how do they look 1080p | Technology | explainlikeimfive | {
"a_id": [
"dqcstlu"
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"text": [
"Old movies (most movies in fact) are shot on film, which is analogue and therefore doesn't have a resolution as such. The resolution is only restricted by what you transfer it to (Video, DVD, Blu Ray etc). Therefore if the original film master exists, you could create a new version in pretty much whatever resolution you want."
],
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21
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|
7fm8eh | Europes AC electricity has a frequency of 50hz instead of 60hz. Is it still possible to get 60fps on televisions and monitors? | My father keeps telling me that it is impossible to get a monitor refresh rate of 60 in europe, telling me that because our AC has 50hz the standard for fps is also 50fps. I believe his knowlegde may be out of date. So my question is: How does the frequency of alternative current correlate with the refresh rate of monitors? | Technology | explainlikeimfive | {
"a_id": [
"dqctdad",
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"text": [
"Back in the days of analogue TV, refresh rates were tied to the frequency of AC power. This is why PAL televisions were based around 25/50 Hz instead of NTSC's 30/60. These days, it's not relevant. Wall current is converted to DC before it feeds into the monitor where it drives a frequency-generating crystal to figure out how everything else works. The adapter on my laptop will run on anything 50-60Hz and 100-240 Volts and still provide a constant 19V output.",
"In the days of the CRT monitor, (those massive boxes that flickered and were always staticy), the refresh rate was directly controlled by the AC frequency it was supplied with. So in Europe, your lightbulbs flicker at 100hz, and your CRT's flicker at 50hz. And in North America, our lights flicker at 120hz and CRT's at 60hz. In digital monitors and TV's, the AC electricity coming from the wall is converted to DC before anything happens. For digital, the refresh rates are usually locked to what the manufacturer specified. The frame rate of your computer has no connection to the AC frequency so there is no need to worry about that, your computer can output any frame rate it can handle. *(Sometimes it is converted outside the monitor, on those you'll see a black box on the line that looks like a laptop charger. Other times the converter is placed just inside the device so for \"neatness\")",
"Your father is thinking of older CRT monitors. Essentially, these work by firing a single ray at the screen. Electromagnets deflect this ray so that it scans in horizontal lines from top to bottom, while the ray itself is switched on and off rapidly (colour monitors had three guns, one for each primary colour, but the basic principle was the same). Each frame is therefore scanned from top to bottom, and this is timed using the mains frequency, which is 50 Hz in Europe but 60 Hz in North America. But because of the fact that high frame rates weren't easily possible in those days coupled with the way human vision works, each frame was scanned twice, alternate lines each time, so you actually got 25 fps in Europe and 30 fps in North America. (Actually, because of bandwidth problems with the NTSC system used in North America, when colour was introduced they had to slightly slow the frame rate to 29.97 fps -- the reason for this is highly technical and not easily ELI5-able.) This isn't relevant at all these days, because monitors and TVs work on completely different principles. Instead of using mains frequency to time everything, monitors have their own internal clocks, and the cathode ray tube monitor is now rarely seen outside of a museum -- thankfully: those things were massive, weighed a ton, and if they broke would send shards of glass flying about the room.",
"The frequency of your AC electricity has nothing to do with how fast your monitor can refresh. 120+ Hz monitors exist after all."
],
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14,
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3
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7fmqjd | Why isn't 900p common like 1080 or 720p? | Technology | explainlikeimfive | {
"a_id": [
"dqcvy8u"
],
"text": [
"720p and 1080i were chosen as the standard resolutions for HDTV broadcasts. While they both use roughly the same amount of data/bandwidth, 720p sacrifices resolution for getting a full 60 frames per second update, making it preferable for things like sports. 1080i, OTOH, gives you higher resolution but slower screen updates due to the interlaced signal (it only redraws half the lines at a time, 60 times per second, giving you 30 frames of actual motion). Since these became standards for televisions, there is a *huge* number of display panels being built that support these resolutions. The large number of available panels made the cost lower & very popular for computer displays."
],
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15
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|
7fo98b | What does bloat wear actually do with to take up that much computer power? | Technology | explainlikeimfive | {
"a_id": [
"dqd6lni"
],
"text": [
"Bloat**ware** is a term for software that is unneeded or unwanted. It is installed on new PCs by manufacturers because they are usually paid for each installation. In this manner a Windows PC can cost the manufacturer *less* than a PC without an operating system installed, because the paid installations total more than the cost of Windows. Very often this software is not the kind that is only started when the user wants it (like notepad or a game) but is instead set to start with Windows, running continously in the background using CPU, RAM and disk IO resources. This is because the software is there to push advertisements of a kind for either itself (\"you need to renew your Norton subscription!\") or for another product, or to push you into using another product instead of the default (for example maybe they install their own special client for Facebook that runs extra ads)"
],
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4
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|
7fp7ku | why do laptop and PC manufacturers install all of this useless software that slows the computer down so much? | Technology | explainlikeimfive | {
"a_id": [
"dqddoru"
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"text": [
"$$$ You'll notice that a lot of the software has a premium version and it tries to get you to upgrade after the trial period is over. These software companies pay the OEMs to load the trials onto the prebuilt machines in hopes that a small percentage of those who buy them will buy the premium version when the trial runs out. HP, Dell, and other OEMs load the software on the machine because it lets them charge less for the machine while still making the same amount of money and lets them move more machines that way."
],
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27
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|
7ftsux | When the entire world is driving electric cars, is the risk of batteries exploding greater due to larger capacity? | Technology | explainlikeimfive | {
"a_id": [
"dqec0cs"
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"text": [
"Yes, basically. The risk of exploding batteries is obviously increased the more of them that are around, since it is a non-zero risk individually. edit: i should add that while this is pedantically correct, it is also true that the risk of 'exploding batteries' is infinitesimally small, and absolutely pales in comparison to the risk of petroleum-based fires."
],
"score": [
6
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|
7fuoh8 | Why can’t two phone numbers calling each other be connected instead of being prompted with a busy line? Is this something that could be fixed easily? | Technology | explainlikeimfive | {
"a_id": [
"dqehmkk"
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"When you dial a number on your phone, it goes \"off the hook\". That is, it's no longer able to receive calls, because dialing a number is the same as being in the middle of a call. This can't be fixed easily, because it's rooted in the basics of how the telephone system works. However, if you have call waiting (where you can see that someone is calling even when you're in the middle of a call), you'll be able to see that the person you're calling is calling you, and switch over to that call."
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7fxt4k | Why do pilot cabin in planes have so many buttons and switches? | Can't they be simplified using touchscreens? Like how our smartphones have so many functions and options, yet only few buttons and 1 huge touchscreen in the middle. | Technology | explainlikeimfive | {
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"The touchscreen would then be full of controls, except they're virtual, can't be felt with your hands, and the software driving it would have to be that much more complicated. Either way the pilot needs those controls (planes are complicated!), and given that, I'd rather have real knobs and tactile switches/buttons than a touchscreen.",
"If something goes wrong in a plane, you can't pull over and take a look under the hood. Either you can fix it without leaving your pilot's seat, or you're dead. The cockpit needs every conceivable control measure available. Touch screens would only complicate things by putting more computers in the middle, computers that can't or don't provide the same positive feedback that a metal switch does when it *clicks* into the right position. Pilots can navigate their cockpit by feel alone because they often need to be watching things outside the plane. You can't touchscreen blind.",
"Aerospace Engineer here: Most of those switches you see are actually circuit breaks for critical or semi-critics systems. There are other circuit breakers in the cargo compartments for other systems as well. Most older airplanes are configured this way since that’s just how circuit breakers work. If you look at the 787 flight deck there are significantly less switches and circuit breakers because we now have a lot of the circuit breakers as electrical switches on display screens in the flight deck. So in essence we are moving there but it’s only on clean sheet airplane designs because even new dash models of existing aircraft (737 MAX for example) won’t redesign the whole electrical system for something like that. TLDR: Newer airplanes do have a lot less buttons, switches and circuit breakers. You’re just used to the older airplanes.",
"Most of what they do can indeed be controlled on just a few screens in front of them. However, the extra buttons and switches provide more controls in the event something goes wrong. They can still operate the plane even if the main computer completely dies.",
"There are not as many controls as you might think. Most controls will have a set for both the pilot and the co-pilot, and many of the controls are going to have one or two levels of redundancy. That means there can be as many as six buttons or switches that do the same thing. Also, a lot of what look like buttons are actually fuses and fuse indicators and are not something that will get used regularly.",
"Airplanes are designed so that it's very unlikely that anything goes catastrophically wrong, because when something goes wrong in an airplane hundreds of people might die. Touchscreens are much more complicated and have many more failure modes than simple switches, so they're very unlikely to be used for controlling the airplane in the near future. If you imagine that every time your iPad or Surface had an app crash, several hundred people died, you'd probably agree that it's a wise choice."
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7fywoc | What is the difference between a router and a modem? | Technology | explainlikeimfive | {
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"The modem is the device that converts input signals such as cable or land line phone signals from your ISP into digital data useable by a computer or similar device. A router is a device that manages the flow of data to multiple connected devices. So in your standard home, the outfacing connection (such as a cable line) is connected to a modem. That modem is then connected to a router which all of your computers, phones, or other devices connect to.",
"This should be more ELI5-y IMO: Internet comes in through a special cable your Internet Service Provider (Time Warner, Cox, Charter, AT & T, Verizon, etc) uses. Usually it's a Co-ax cable so let's just pretend it's a co-ax cable. (Replace the cable type with whatever your ISP uses). You need something to connect to that co-ax cable because your laptop, tablet, phone, computer doesn't connect to Co-Ax. A modem basically takes that co-ax cable connection and changes it so you use Ethernet instead. It does more technical stuff than that but most people should just think of it as changing co-ax cable into a Ethernet port. > ISP --(Co-ax)-- > Modem (has an Ethernet port) Great! Now you have things that can use an Ethernet connection and have them use the internet! > ISP --(Co-ax)-- > Modem --(Ethernet)-- > One single device But there's only one Ethernet connection. You can only use Internet on ONE device and that device has to be connected by an Ethernet cable. That's no good! You want to use WiFi! You need a way to change the one Ethernet port into WiFi. Say hello to the Wireless Access Point! It turns one Ethernet Port into WiFi! > ISP --(Co-ax)-- > Modem --(Ethernet)-- > Wireless Access Point --(WiFi)-- > Your devices But you lose the ability to use Ethernet now because the Modem only has one Ethernet port and you just used it for your Access Point. Well, say hello to the Wireless Router! It's pretty much a hub (turns one Ethernet connection into many) AND an Access Point all in one! Now you get WiFi AND you get extra Ethernet Ports! > ISP --(Co-ax)-- > Modem --(Ethernet)-- > Wireless Router --(Multiple Ethernet AND/OR WiFi) -- > Your devices But what most ISPs offer now is a COMBINATION Modem/Wireless Router device which is just what it sounds like. A Modem and Wireless Router in the same device. So now you have it much simplified. > ISP --(Co-ax)-- > Modem/Wireless Combo --(A few Ethernet Ports AND/OR WiFi)-- > Your devices",
"A modem MOdulates/DEModulates different kinds of carrier signals. The one you have in your home turns a signal over a phone line (DSL), or a coax cable, (or maybe fiber), into the ethernet signal that your computers use, and probably also the wifi. A router takes the information conveyed in those signals (whatever kind that is), and routes packets of data to various other locations. Routers can have fiber optic cards, ethernet cards, etc. They take data and decide where to pass it to next. Modems just take a signal and make it another signal. The object you have at home is likely both a modem to turn your cable or whatever into ethernet, along with a router to allow you to connect multiple systems to this connection, and a 4-port switch in the back providing physical connections, and a wifi transceiver.",
"A router is used in woodworking to \"rout\" (hollow) out sections of wood. A modem connects you to the internet."
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7fzmme | What is RAM and why is it important for computers? | Technology | explainlikeimfive | {
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"A way to think of RAM is working memory. Normal memory is you remembering your address, say. Working memory is you remembering a phone number between looking it up and dialling it into a phone. A computer is similar. You have the main memory, which is your hard drive (or nowadays as common as not, an SSD), which stores programs, and files. Then the RAM is the working memory, which stores the current data being worked on, anything that's needed now and fast, because RAM works vastly **vastly** faster than the storage. Windows has a lot of little odds and ends that have to be stored in RAM to ensure the fast running of the system, as well as the program or programs you have open.",
"Random Access Memory is a type of data storage device that allows bits of information to be read in any order, at any time, extremely quickly. Unfortunately they are volatile - meaning they are unable to hold their data without constant electricity - and they can't hold that much data compared to something like a hard disk. So you have all your stuff on the hard disk, and then it copies over the files for a specific program to RAM when you open it. Then, the computer doesn't have to go dig through the massive hard drive every time you do anything in that program - it's in the RAM so it can access it quickly. A hard disk is like a fridge. Lots of storage for long term. RAM is like a plate. it would suck to eat food directly out of the fridge, having to go back in the kitchen every bite. So you transfer to a plate to eat it."
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7g0hp3 | What is a SSD and HDD? Differences and pros/cons of both? | Technology | explainlikeimfive | {
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"A SSD is a solid state drive and are must faster. they can read write at a much faster rate and never need to be de-fragmented. The down side of this is that they are very expensive in relation to storage size so its most computers only run a small one. HDDs are slower and Need to be De-fragmented every now and then depending on how often you delete stuff. On the upside the data in a HDD will last until the platter is physically broken and because of how cheap they are you can buy a 1TB for bulk storage relatively cheap."
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7g6bky | How do Emulators like Dolphin make old GameCube games look almost like they are in 4K? | Basically what i'm asking is why does Super Mario Sunshine look blurry and terrible on it's native resolution but the water looks Crystal clear and amazing on the highest settings if the game was never intended to be seen that way? | Technology | explainlikeimfive | {
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"The output of the gamecube was limited to the displays they knew they were going to use back then. I think the Gamecube's max output was 480p which is basically 640x480, because most TVs couldn't display any more detail than that. An emulator doesn't have those limitations. It has much more power to throw at the problem, and it has much higher output resolution, so it can take the original game code and render the output at greater resolutions, to truly from the ground up, increase the 3D detail. There's no way to improve the textures, but some things will gain a lot of definition by doing it."
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7g6x63 | Why are speakers capable of reaching volumes that can break the speakers? | Technology | explainlikeimfive | {
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"That's a bit of an odd question. A speaker is an entirely passive device, it just creates a sound based on the electrical signal that's going into it. If you put more power into it than it's rated for, it's going to go bang. It's like an electric motor. They'll be designed for a certain rate of speed at a certain power level. If you have a power source that can put more power into it, it'll spin faster and faster until it fails. That's not a fault of the motor. Why don't they put protective circuits into these things to stop it happening? If that's what you're asking it's a simple matter of cost. For something most people wouldn't ever need, it'd be an extra expense, so the manufacturers are pragmatic and don't include it. Even if they did though, if you overdid it enough, the devices would still fail."
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7gb31c | Why is Netflix's website so fast and slick. I mean the actual site not the streaming videos. The site takes ~2-3 seconds to load 100+ of images, a streaming video and more with almost never a delay. | Technology | explainlikeimfive | {
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"Quote from a former employee at Netflix: \"Variable data streams, multiple CDNs, buffering, metric-gathering, and because we've been doing this arguably longer than anyone else and have the experience to support a large number of devices and connection speeds.\" (Yan Biao Boey) I guess he's right bc Netflix was founded in 1997",
"There's another factor as well. Advertising supported sites often have the ads \"bid\" for which ad gets shown. To allow time for this to happen, the page load is sometimes delayed as a second or third request needs to be made to another server before the page is displayed. Netflix, on the other hand, hosts all it's stuff itself, so it doesn't need to ask anyone else, thus reducing the delay for a page load.",
"Someone correct me if I'm wrong but, Amazon Cloud Servers hosts Netflix servers. And they are decentralized meaning areas like Houston, Texas or Columbus, Ohio may have its own server farm. This helps in reducing routing between you and them. ELI5- Picture you local postal server if it was 50 miles away your mail would take longer to deliver, but move it within 10 miles and add 5 mail servers to cover that 50 mile radius and it becomes efficient."
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7ge14s | What does overclocking do to my processor? | Technology | explainlikeimfive | {
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"You know how in the old times ships used to have a bunch of people with oars, and [a guy with a drum]( URL_0 ) to set the rhythm? Some people are weaker, some are stronger, so if you let everyone do what they want, you wouldn't go anywhere. If you want to go straight, the people on both sides of the boat have to row at the same rate, or the ship will start turning. So you have a guy with a drum setting a beat, so that everyone pushes at the same rate. There's also going to be some speed at which all the rowers can go forward comfortably. That's what the CPU clock does. Overclocking is just banging on the drum faster. CPUs are also like that. They have a bunch of components, some of which are faster and some of which are slower. The clock synchronizes everything. Usually there's a bit of margin, so if you run the clock faster, you get better performance. But if you overdo it, some parts of the CPU won't get their stuff done in time, and the synchronization will fall apart. Just like different ship crews are going to have different qualities, fabrication is imperfect. Some CPUs will have better made internals than others, and will have a higher maximum speed at which they can operate correctly.",
"You put a little more voltage into it, the CPU \"cycles\" through its operations at a slightly faster rate of 3.5Ghz instead of 3.2Ghz giving you a marginal increase in performance. But as you're putting more voltage into it, more heat is generated as a result.",
"Overclocking runs the processor chip at a rate faster than the rate the manufacturer guaranteed it would work at. The manufacturer tests chips and provides a few speed ratings as appropriate. However, every part if different. The manufacturer wants to minimize the number of parts returned for not meeting the specs, so it is very conservative in marking. If you want to get the most performance out of the chip, and you are okay with occasional failures, then you can overclock it."
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7gem2p | How did the enigma machine work, and why was it so hard to crack the code? | Technology | explainlikeimfive | {
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"You know a letter replacement code that kids use? A very simple one is every letter is shifted 13 spaces, so if your message has an A it becomes an N, B becomes an O etc. Those are easy to break because some letters are used more frequently than others and your encoded message preserves the frequency of the letters. As an example, shifting each letter 13 places, \"This is my secret message\" becomes \"Guvf vf zl frperg zrffntr\". Someone might notice there are a lot of letters R, G and F in my code, and suspect those letters might be E, A, T, I, or O (the 5 most common letters in English), and pretty quickly be able to guess secret or message, then figure out the whole thing. To make codes harder to break, you can change your cipher for each letter, so if the first letter if shifted 13 spaces, the second might be shifted 2 and the third might be shifted 24 spaces. Using a system like that a message like AAA would now be NCW, that's a lot less obvious than an encoded NNN. This type of code is much harder to break by hand, even if the sequence is pretty simple. The enigma machines shifted each letter by different amounts, using lettered wheels that rotated and made different connections with each other (changing the shift for each letter pressed), and further changed things by using plugs that didn't just rotate letters, they substituted them in a non-rotated way (sort of like manually converting all your As into Qs and Bs into Es then applying the shift to each letter in the message). It was readable because an encoded message put into the same machine would be decoded, if the settings started at the same position (the tricky part then becomes getting the set up information transmitted to the users so they were using the right settings each day). It was hard to crack because with all the shifting and converting, there were 158,962,555,217,826,360,000 different starting set ups that could be encoded, and to crack the code you had to figure out how the machine worked, and then which setting was used for an encoded message."
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7gg62j | how do batteries (phone, laptop) get charged? And why does it take an lengthy amount of time? | Technology | explainlikeimfive | {
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"Batteries employ reduction/oxidation reactions, also known as electrochemical reactions. Two compounds are contained in the battery, one is an oxidiser and the other a reductor. When you use the battery, the reductor lets go of some of its electrons, which flow out of the negative terminal of the battery, through your equipment (providing electrical energy to it), and back into the battery, via the positive terminal to the oxidiser, which takes up the electrons. These chemical reactions are reversible. A charger pushes the electrons the other way around, reversing the chemical transformation of the oxidiser and the reductor that occur when they exchange electrons. One important reason that you cannot charge the battery very quickly is that the process of charging/discharging generates heat. This must be dissipated, which takes times. Also, sometimes compounds must migrate towards electrodes in the battery. This also takes time."
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7ghizn | How do motion detectors detect motion in the dark? | Technology | explainlikeimfive | {
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"You have two common types of motion sensors - passive infrared(PIR) and Ultrasonic. The most common type is PIR which sees IR which is emitted by hot objects. There is a special lens in front of the sensor so a warm object moving through its field of view creates sudden transitions that are easy to detect. Since it is relying on heat emissions it works fine with or without light. Ultrasonics send out a sonar burst and effectively echo locate like a bat. They check the sound they get back after each one and compare it to the last one, if it changed significantly then something in the space moved and they trigger",
"While I can't speak to the newer tech I've seen discussed here, older motion detectors *do not* work in the dark. I've fooled them many times. Older detectors use a [cadmium sulfide cell]( URL_0 ) in front of a fresnel lens. The sensor is a resistor that passes electricity depending on the amount of light hitting it. Passing that light through a [fresnel]( URL_1 ) lens scatters it. Now you have a sensor that trips according to light variations it \"sees\" over time and because of the scattering the sensor \"sees\" a nice, wide, blurry area. Stand still, let all the light and shadows remain static, and nothing happens. Move through the lenses ( < -sp?) eye and the resistance on the circuit changes, tripping the alarm. Move *really* slow and the sensor doesn't trip because the incoming light doesn't change fast enough. Not sure how the timing works but you don't want your alarm to trip because the sun moved a shadow a bit."
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7ghka4 | How does red dot sights work? | you know, the red point to aim in games with guns. and in real life too. if normally with a gun you need two separate points to know the gun is aiming the correct way (one bump near the trigger and another at the end of the cannon) how does only one red point in a glass works for aiming?? | Technology | explainlikeimfive | {
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"The dot in a red or green dot sight is not actually a coloured point that's hovering in a fix spot in the air like an iron sight does. Instead, the red dot you see is a reflection of a little red lamp that falls onto a spherical mirror which filters out only the red (or green) spectrum. This mirror is installed in a way that no matter what angle *you* look on it, the Red dot will always point towards the spot the bullet will hit. EDIT: That way the Red dot itself is virtual and basically only exists in your eyes, two people looking through the same sight at the same time from different angles would see the spots in different 3-dimensional places, but still pointed towards the target.",
"a red dot sight (also known as a reflex sight or a reflector sight) bounces a laser off of a reflector that is curved so that the angle the dot reflects off of it changes where it appears to reflect off of the reflector. The reflector itself is actually transparent, and that's what you are looking through when you look through the sight. The curve of the reflector is tuned so that the image of the laser that is reflected appears to stay in one position relative to the target that you might be looking at through the sight, with it ideally being kept in the center of the reflector. you could think of it as sort of the opposite effect of using a curved mirror to focus light to a point, where the image of the reticule is at the point, and your eye being able to see it from anywhere within a certain cone of vision. if you;re curious about the specific internal workings, there are some good diagrams on the [Wikipedia article]( URL_0 )",
"The other posters are correct in how the device functions. However, I think you are asking, \"Why is it an effective way to aim something even if it only has one point?\" The simple answer is it is built to have the dot lie on a parallel line to the gun barrel. It is worth noting that reflex sights are not for long range or precision shooting. They are more for close-medium range combat situation, i.e. getting all shots in a bad guy shaped target. To get the best accuracy out of a reflex sight, you should mount it as close to the barrel as possible so that the point of aim and point of impact are as close together as possible. This principal also applies to scopes as a perfect scope(mounted perfectly on a perfect gun) at 0 windage and yardage should only be off by the same distance it is away from the center line of the barrel."
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7girxx | Why does using a cheap charger sometimes cause ghost-touches on my phone? | Technology | explainlikeimfive | {
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"Generally what the cheaper chargers are cheaper because they have been made to a lower price point - often by removing parts that are not required for it to work, but required to reduce electrical noise on the output - and radiated from the charger itself. These parts are often the input filter, some parts of the output filter, and shielding that is there to prevent the power supply radiating electrical noise and interfering with other products. This noise which is normally attenuated to prevent it posing a problem can be picked up by the more sensitive parts of a phone, or a laptop, specifically touchscreens and touch pads, that work by detecting very tiny changes in capacitance, using very small signals. If you have noticed that some laptop chargers have a heavy 'lump' in the middle of the cable? That is a ferrite ring, also called a 'choke' used to made it harder for current to change rapidly in the cable, therefore suppressing high frequency 'noise' generated by the power supply."
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7gjble | why can't the big companies like google deny service to non neutral ISPs | Technology | explainlikeimfive | {
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"> wouldn't the customers go to other isps Oh sweet summer child. Much of the problem lies in the fact that people don't have other ISPs serving their area."
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7gjkk2 | How are games like Fallout: New Vegas only 5.5 GB and games that are way less content like Call of Duty take ~70 GB? | Technology | explainlikeimfive | {
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"Because one is an AAA game with lots of unique full motion video (which your computer couldn't render on it's own) and the other is made by an almost-indie company with hordes of repeatable low-poly models that all use the same hundred textures. It really doesn't take much CPU or hard disk space to render a giant landscape with a few textures. It's much more expensive to render it on a supercomputer(literally) to make it as pretty as possible then store the video on your computer. TL;dr AAA games use videos which take up lots of disk space, smaller games don't",
"Call of Duty often uses stuff once then never uses it again. Fallout takes something it used before and uses over and over again in different circumstances. So the total amount of stuff *in* CoD is more, while the each thing in Fallout is used more. Also the things used in FO:NV are smaller than each thing in the new CoD. Less details means less space.",
"It's mostly graphics that take up the majority of storage space in games nowadays, and Call of Duty is a game that banks heavily on graphics whereas Fallout: New Vegas is not so much."
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7gl4a0 | How do Fingerprint scanners on smartphones work? | Technology | explainlikeimfive | {
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"Its alot like a barcode scanner really. Your fingerprint has a unique series of lines to it. Your phone records that pattern of lines as a code and that's your password. (truthfully though its looking for the spaces in between the lines rather than the lines themselves) That said given how many things you touch in a day... obtaining your fingerprint isnt that super hard. Which is why they are super popular really."
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7glra2 | What's the difference between a 10Mb/s connection and a 100Mb/s one when the "bits" travel at the speed of electricity in both cases? | Technology | explainlikeimfive | {
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"Imagine two dogs. A big ol' sheepdog ... Woof ... Woof ... Woof ... Woof and a little terrier ... Yip-Yip-Yip-Yip-Yip-Yip-Yip-Yip In both cases their barks are reaching your ears at the speed of sound, but the smaller dog is getting twice as may barks-per-minute. It is the same basic idea with 10Mb/s vs 100Mb/s connections speeds.",
"Nobody is really giving a good answer. The difference is this: at 100 Mb, the bits are packed tighter together. So suppose you have a piece of wire such that it takes a [nanosecond]( URL_0 ) for the signal to travel from one end to the other. This is the same regardless of how fast you're sending data. What changes is how long you wait between changing the voltage on the wire. If you're sending data at 10 Mbps, you're changing the voltage on the wire 10 million times per second. If you're sending at 100 Mbps, 100 million times. At both bandwidths a bit takes the same amount of time to cross the wire, but in the second case it's 1/10th as long. Physical characteristics of the wire smear the signal, so that if you change the voltage too fast information gets lost. So to transmit at a higher bandwidth you can need better cabling, besides faster hardware.",
"Bits do not travel with speed of electricity through the most of their journey, they travel with the speed of light. [[Demonstration of a signal traveling through optical fiber internet cable]]( URL_1 ). The bit that is travelling is either \"0\" (off) or \"1\" (on). Once it reaches junction box of your internet provider, then it is connected to a switch and sent via [[CAT5 cable]]( URL_0 ) If you think about Internet connection like a road, then the bits travelling to your house are the vehicles. \"Mb/s\" (Mega bits per second) is telling you how many cars can travel per second through the road, it is technically called \"bandwidth\". Speed at which the bits travel is called \"latency\", and it is never as good as speed of light, because the vehicles need to pass through junctions, bridges and corners, or even a gravel road which slows them down before they reach your house. Limit of 10Mb/s usually means, that the Internet Provider simply enables small amount of their road for your bits, so that bits of other customers can also travel along them.",
"The capacity has nothing to do with how fast a single pieve of information (a bit) arrives, it rather indicates how much can be sent in parallel. Think of it like water, if you have a small vertical tube and pour some water in it, it will fall by gravity. If you have a bigger tube, it will still fall by gravity and arrive just as fast. Now lets say you add a lot of water, more than the small tube can handle, it will accumulate on top until there is space for it, the first water will arrive just as fast as before, but you'll have to wait before you have the whole chunk. While with a bigger tube, it may all pass through and fall by gravity, just as fast as the small amount of water."
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7glsb3 | Why is Random Number Generation so important for IT security? | As far as I know the primary application of RNG algorythms in IT is security algorythms such as hashing and encryption. Play Station 3 was hacked basically because some number wasn't truly random. How exactly does the ability to predict "random" numer compromise security? | Technology | explainlikeimfive | {
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"I'm thinking of an ATM PIN. What number am I thinking of? If you can guess it, you can access my checking account. It's like guessing a password. If I use a system to generate my ATM PIN that seems random, but can actually be reproduced (like taking my birthday and scrambling the order of the digits), someone could figure out the system I use to generate PINs and guess only a few times before discovering it. Randomly generated passwords are related to randomly generated numbers. Computers generate pseudorandom numbers with a lazy function called Rand() or something like it that use the time that the function is called to generate a number. This is like creating an ATM PIN with your birthday. It can be guessed if you know enough of the other pseudorandom numbers the system generated. Even perfect security - like one time pads - rely on truly randomly generated passcodes. If the code isn't randomly generated, nothing is secure.",
"At the simplest level, IT software security is based on the idea that is really really hard to guess a large randomly chosen number. This is used to separate and secure different 'sessions' of interactions. An example... I log in to a website. The website confirms my password '2' and gives me a temporary secret keyword: 6 , for further communication. You login with your password '4' and it gives you a temporary secret keyword: '12'. A hacker has been watching this and figures out that the temporary secret keyword is always the password x 3. It is not random. Which means there is a very high chance that temporary keywords like 3, 6, 9, 12, 15...exist. He can try to communicate with the website using a secret keyword : 21, and boom...he has hijacked the poor souls account whose password was 7. To prevent this, it is extremely important that the secret keywords do not have any pattern. They must not be predictable. In other words, they should be random and very long so that they are harder to guess. Now it turns out that it is very hard to generate truly random numbers, because the process you use to generate them may have a hidden pattern. It is also the case that process used to generate them is itself a pattern. So computers use what are called pseudorandom numbers. These are numbers generated using steps such that the pattern is extremely difficult to figure out because any normal computer would either need ridiculous amounts of time (age of the universe) to calculate out or it would need near infinite amounts of memory to do so. They are for all practical purposes, as good as random numbers because you can't realistically detect the pattern.",
"Computers aren't really random at all. They do everything step-by-step in a logical way that's been programmed into them. They can't \"think of a number\" like a human can. They only follow instructions, and if you use the same starting conditions and instructions, you get the same answer every time. When it comes to security, this kind of repeatable consistency (called *deterministic* output) is bad. The computer needs to create a secret key that protects the information it's creating or transmitting - if you know, or can guess, the starting conditions of the program, you can easily find the secret key that it creates. There are ways of getting around this, by using data from sources that *shouldn't* be deterministic - like user input for instance. Unfortunately that can be quite difficult to get, especially if you need to do it at start up and the user hasn't touched anything yet. You can get it from \"worse\" sources like the current time, which should be different every time you run the program, but can be manipulated. When hackers can manipulate the data the random number generator receives or if the random number is used incorrectly by the code, that greatly increases their ability to get to the secret key that the computer generated, and thus break the encryption."
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7glzgd | Why are Apple’s iOS updates so large? | Technology | explainlikeimfive | {
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"In addition to the fact that there's more to the update than they list in the little blurb description they provide, it's also down to how the update is packaged. Some companies choose to provide updates in a \"delta\" format, where only the changes to files are sent to your device. In that format, the computer must calculate the new file using the old file and the provided delta data. This process is pretty reliable, but not perfect. When you're talking about OS files, this process can introduce errors that brick your device. Companies that use this for updates have to write additional code to check for errors and correct them, and sometimes updates may need to be downloaded multiple times as part of that. It saves time and bandwidth for most people, but it can unpredictably cost a lot of time and bandwidth for some people when it goes wrong. Apple often chooses to supply the entire updated file instead of just sending those bytes that changed, although they do now support delta updates. The advantage to full file updates is that there's no calculation needed on your device to install the update. You just change the code that pointed to the old files to point to the new files. If there are any problems, point them back to the old files. It's a more reliable method for the consumer, and is more predictable, but it does mean that updates include a lot of duplicate data you already have on your device."
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7gool9 | How does throughput actually work on cabling? | I understand what throughput and bandwidth are now. I get the ANALOGY. But don't understand the literal use and how its implemented. I get that its not the speed of the signal, thats always the same really. its how many bits are sent at once. like a bus vs a 2 seat car. But how can you sent more than one bit at a time? on a wire you have one bit after another. its not at the same time. voltage represents bits. [Unless it is referring to UTPs]( URL_0 ) in UTPS, there are many other smaller wires. So is it saying that bits are sent on the different wires at the same time? like if you want to send the transmission 1010 on one wire, it will be 1...0...1...0... But using UTP with 4 wires, its all at the same time? (if so, how does the device know which bit comes first in that block of bits sent at once?) | Technology | explainlikeimfive | {
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"Your question is less about throughput/bandwidth, and more about how bits are modulated onto a cable. That's a fancy way saying how is a digital quantity (one or more bits) represented in the real physical world. Trivial case is two different voltage levels. We'll use +10/-10 volts as an example. When a device wants to send a bit, it can represent a 0 as -10 V and a 1 as +10 V. We'll call this concept of sending a bit with voltage, a symbol. The voltage for each symbol well be held steady for a specific time, intuitively called the symbol time. In my theoretical standard, 0 volts could perhaps mean no data is currently present (in practice far more complex framing schemes exists to determine when real data is present). I think you can already understand everything I just said, so let me know if I'm mistaken. A receiver built to my standard will start idle and wait there, continuously measuring the voltage. Once the voltage transitions away from 0V it is aware that data is now present. It can than determine the bit sent based on the voltage measured. This process can be referred to as demodulation. Then wait the symbol time and sample again. If the voltage ever goes back to 0, then no data is being sent and the receiver can return to an idle state. In reality there are several other details that are very important (and links with more bandwidth are much more complex than this example) but this is a good introduction (and is similar to how RS-232 works). Now to rephrase your question, what if I want to send more than one bit of information in a given symbol time. As you noted you could use multiple wires to send multiple symbols. However nothing says my symbol has to be able to only represent one bit. Indeed many standards have 2, 3 or 4 bits per symbol. Let's go to a 2 bit symbol. for 2 bits, there are 4 possible states (00, 01, 10, and 11). We can use four voltage levels to represent these bits. We'll use -10 to represent 00, -5 to represent 01, +5 to represent 10, and +10 to represent 11. The receiver would work very similar to my previous example, but now instead of demodulating 1 bit per symbol, we're demodulating 2 bits per symbol. There are a LOT of standards for how bits are modulated and sent across a medium. From your comments (if you're really interested) I would suggest you you first study a simple protocol like RS-232 which is really only sending one bit at a time. However it also discusses start/stop bits and you may be able to understand how a simple receiver can be built. Than you can start to look at the more complex protocols used in Ethernet like 1000Base-T (gigabit Ethernet over copper cabling) which play some very interesting games but require a much broader knowledge base to understand."
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7gpq9r | How does a company get its product's code in the product? | I'm not terribly familiar with coding. I kind of understand it, but I'm still confused how, when you code something like Siri on a computer, how is the coded material put into the Iphonet? I hear people say they write code, but how is the code they wrote put into different products? | Technology | explainlikeimfive | {
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"by uploading it into the device's memory. physically same process as you uploading your music from your itunes on desktop to the iphone. except....apple's new iOS code gets loaded in at the factory thru a special loader.",
"Code is written in a \"programming language\". Think of it like a dictionary, it tells the device the meaning (function) of each term (code). Different devices use different languages. There's hundreds. It's easy to teach a computer a new programming language, you just have to upload the correct information. You can write code for almost any device, in almost any programming language, using a properly configured computer. You can also make a computer act like almost any device, through a process called \"emulation\". You can make your computer act like a cell phone, or a Nintendo, or even a car! So: A programmer uploaded the iPhone programming language onto a computer. They installed an emulator, that allows the computer to act like an iPhone. They wrote the program for Siri in the appropriate language, and tested it using the emulator. Once complete, the code was compiled into a single program that an iPhone can install. Any product running the correct programming language can run that program. The programmer will have to re-write the program in a different language to work on devices that can't use that programming language."
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7gs0ws | What is "blue light" and why does filtering it on my phone help protect my eyes? | Technology | explainlikeimfive | {
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"The most important thing about filtering blue light from your electronic devices is that blue light keeps you awake at night. Light signals your body to stop the production of melatonin and destroy the melatonin in your body, and blue light is the most effective at causing this. Melatonin signals the rest of your body to sleep and gives you that sleepy feeling. Filtering out the blue from your phone screen and computer monitor helps prevent sleep disorders because it helps prevent those devices from falsely signaling your body to stop producing melatonin."
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7gsb6z | Why does “turning it off and turning t back on” fix so many problems in IT? | Technology | explainlikeimfive | {
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"Every complex system has something called 'state' - the current status of all the various elements in a system. Consider a chess match. When you begin a chess match, it's in a fixed state - all the pieces nicely lined up in a specific order on their side of the border. As the chess match proceeds, the state becomes more and more muddled - until you finally reach a state where one side is no longer able to make a legal move. Computer systems can also work the same way. They can potentially work themselves into a state where there are no valid moves to make. Just like with the chess match, starting over changes the state into a known good state from which operation can continue."
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7gvuv4 | password keepers | Technology | explainlikeimfive | {
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"I'm assuming you're talking about apps like LastPass and 1Password? The idea isn't that they're more secure than *typing in your password*, it's that they're more secure than *other* methods of keeping your passwords (like writing them all down on an index card and keeping it in your purse or wallet, like my mom does). If your master password is secure but memorable to you, it is a relatively safe way of storing a multitude of other passwords that you might not otherwise remember on a day to day basis. It's more secure because you can use a different password for every account without having to remember them all individually (rather than using the same one or two passwords for everything, which is a security disaster)."
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7gzlat | Why and how exactly do computer files become corrupt? | Technology | explainlikeimfive | {
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"Let's say you work in sandwich shop, and all you do is make sandwiches all day. Bread, meat, bread, bread, meat, bread, all day long. It is super boring, and sometimes your mind wanders. One day, you mess up and do an extra bread...Bread, bread, meat, bread, bread, meat. And since you weren't paying attention, you might make a hundred bread, bread, meat non-sandwiches before anyone notices, and all that work is wasted. File corruption works the same. Files are a series of ones and zeros, that have to be in just the right order. One number gets changed, or even worse, one is skipped or added, and the file gets corrupted. Sometimes the impact is local, and you just see or hear a little blip. Other times the first is messed up so badly the computer doesn't know what to do with it.",
"There are a number of different ways that this can happen, and it can happen at various different levels of the hardware-software stack in a modern device. First, let's define \"corrupt\". That basically means that for one reason or another, when your device tries to read a file that looks like a duck, it finds out that it doesn't quack, or doesn't have feathers, or it has a beak and then the rest of it is a frog. At that point, the operating system will refuse to load the file and something will tell you that it's corrupt. Files are stored on your device's storage drive. In the past, this was most likely a hard disk, so let's start there. Hard disks use rotating magnetic platters to physically represent the 1s and 0s that make up your data. They're almost like tiny, *tiny* switches that can be flipped on or off. To store more and more data, the switches (and the arm that reads and writes them) have to get smaller and more precise. So, a hard disk depends on lots of precision pieces moving very close together, and it depends on them being highly durable and accurate for a long time. If the bearings that let the disk spin freely start to wear, the disk can wobble, and the arm can either contact the wrong part of the disk, or contact the disk way too hard, damaging a big fat line of those tiny, delicate switches. That's one easy way to lose data, or make a hard disk permanently unusable. The way that most disk manufacturers mitigate this risk is by implementing a \"sudden motion sensor\", which you might have actually heard on an old iPod or laptop - if you shook it or moved it around while it was changing tracks, you'd hear a sound like \"Click! Sssssyyeeeewwwww\". The \"click\" is that read/write head getting parked *away* from the disk ASAP. The little laser noise is the drive spinning down. The goal is to make sure the disk doesn't wobble while it's at full speed, and the head is nowhere near the disk while it might be wobbling. But, that's far from everything that could damage data on a hard disk. Dust on the drive platters, liquid - really anything at all inside the case - could damage the delicate parts. That's one of the main reason the cases are sealed. That's one of the reasons that almost all modern devices use non-volatile flash storage. Flash storage is conceptually similar to computer memory - internally, it looks like a 'chip' instead of like a metal disk, and the way information is recorded onto it is with electricity rather than with a physical arm. Briefly, instead of little physical \"lightswitches\" like a hard disk would have, a flash drive has little gates that can be \"opened\" or \"closed\" with electricity, using that \"open\" or \"closed\" state to represent a \"1\" or a \"0\" when they're read later. But, anything that undergoes a physical change will wear down. That's the same reason that usable space on a flash storage drive will wear out over time and your \"usable space\" on a drive will decrease. Eventually, the gates get stuck or break, so they can't be opened or closed anymore. When that happens, the flash drive will make a note to itself, like \"when I try to open and close gates in this area now, they don't work well\", and decommission a small chunk of the drive. Before that happens, it will try to shift your files around so that they're still accessible, and use error correcting code to make sure they still \"look\" right. Speaking of memory, that's another opportunity for a file to become corrupt. Files are read off your storage device into memory while you work on them, and when you save them, the version in memory is written back onto the disk. If you've got bad or broken memory, such that your disk hands it \"my name is bob\" and the memory creates \"y nane is bbb\" when it comes back out, that's an opportunity for corruption (especially if the garbled bits aren't in your thesis statement, but in the part of the file that tells Windows \"hey, I'm a Word file\"). The next level up is the filesystem. You might have heard a big fuss about this recently with Apple's release of APFS, their replacement for the older HFS. One of the big dangers in a filesystem is \"hey, if I lose power while I'm saving my file, what happens to it?\". This is another potential case for data loss. If your computer was halfway through saving your homework and then the power went out, you might very well have had half of the old file combined with half of the new file, and even though the hard disks still say \"yep, those are the 1s and 0s you told me to write down\", the filesystem is going to get confused and probably refuse to open the file. To get around this obvious nightmare scenario, most filesystems used in the past 20-30 years have used something called \"journaling\". Rather than risk your one and only copy of a file, the filesystem will first write the changes you want to make to a log. It then reads the log, copies the original file, applies the changes, verifies that the new file looks like the old file (plus your changes), and then deletes the old file. At any point in that chain, the drive could lose power and you'd still have *at least one* good copy of *a version* of the file. Much better than nothing. One of the big features in APFS (and a lot of other modern filesystems) is that it gets rid of journaling in favor of something called \"copy-on-write\". Copy-on-write is a lot like journaling without creating the second file. When you save a file on a CoW system, you're saving what's different, very similar to the log. But now, when you ask for that file, the filesystem will pull up the original, apply the changes on the fly, and transparently give you an identical file to the one you would have created on an older filesystem. CoW is a big deal, because you get a lot for free. For instance, when you copy a file, if there are no changes, the filesystem just creates a sign that points to the old file and says \"done!\". If you change the copy, it creates a list of changes that apply to the sign (that points at the original file, which hasn't changed). That's how Apple's Craig \"Hair Force One\" Federighi was able to do his demo of \"instantly\" copying files in the new macOS - they're not being copied in a literal sense anymore. Ultimately, the point is that you don't risk the original file nearly as much if you're never moving, copying, changing, or deleting it - all of which are opportunities for corruption. And that's just about it. There are definitely other cases that can cause corruption, but those are the main ones, and the gist of it is: anything that physically or electrically causes a file to not be what it says it is will mean the file is now \"corrupt\". Sometimes it's faulty hardware, sometimes it's faulty software, sometimes it's a power loss or a malfunction. Final parting thought: As a software developer, I also can't promise that devlopers don't sometimes change things like configuration files between versions, and instead of translating the old one into the new one, just avoid the work by saying the old one is \"corrupt\".",
"If a computer is using a file, it's probably going to read it and write onto it constantly. If something disturbs the computer enough, it might mess up and write the wrong thing. If I'm writing my banking account number to you, but I accidentally write a 3 instead of an 8, suddenly the entire number is useless to you. A single mistake can irreversibly ruin a file, thus making it corrupted."
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7h2ns1 | How does different data traveling on the same cable not get lost with all the other data? | Technology | explainlikeimfive | {
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"Data is encapsulated into packets with headers and trailers that identify it. Sometimes it does get lost though. When 2 devices establish a connection, they decide on packet numbering. If I send you a packet that says it contains data 1500 - 1600 you expect that my next packet starts with 1700. If it doesn’t, then you your response to me is essentially “I need 1700”."
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7h2t4u | Why are public toilet seats in the show of a "c", and not "O" like the ones in homes? | Technology | explainlikeimfive | {
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"It's so that males don't have to pick up the toilet seat in order to urinate. In the circle shape, there is a possibility for dripping on a seat to occur. In the U shape, the drips just fall into the bowl.",
"The missing piece is by your genitals. No one wants a public toilet seat to touch their genitals."
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7h3etg | Why do some websites still use "www." before their domain name and some simply don't? What's the purpose of it anymore? | Technology | explainlikeimfive | {
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"The \"www\" is what's termed a \"subdomain\". Originally, the \"www\" (which stands for \"world wide web\") was used to indicate that you wanted the web server for the domain you entered in, as opposed to something like their FTP server. Subdomains are still used today. For example, you can go to \" URL_0 \" to get to Google Maps, or \" URL_1 \" to get to gmail. But generally it's assumed that if you don't specify any subdomain, you're probably interested in the domain's main webpage, which is what the www is for, so it's often redundant, and thus not required.",
"It doesn't really serve any purpose anymore, except that some people expect it to be there. You need to make both URL_0 and www. URL_0 work because people will type both into their browsers, but it doesn't make much difference whether you choose to have URL_0 redirect to www. URL_0 or the other way around.",
"There are also some technical reasons for it to do with managing big websites. There's heaps of info at URL_0 but basically, managing your domain well often requires splitting it into manageable pieces. It's harder to split things up if you haven't used some sort of subdomain - and that's what \"www.\" is. A small personal website probably doesn't need www."
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7h40ia | How is Ceramic Body Armor Made? | There is a hard strike face, then a fibrous layer, then a hard ceramic layer, right? | Technology | explainlikeimfive | {
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"Ceramic body armor is usually covered by kevlar and has a metal plate in the center of 2 ceramic plates. So when a bullet hits the ceramic it breaks and causes the bullet to expand and slow enough to stop it before entering the person. Fun fact: military strike plates (ceramic body armor) are rated to stop 5 7.62 rounds within a 4 cm triangle!"
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7h4n8e | How are multiplayer games programmed? | for example in league of legends it is 5v5 and there are so many different actions and interactions that can happen with each other is it just a bunch of if statements that handle every single situation? | Technology | explainlikeimfive | {
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"There are a number of ways it can be handled. Most often these days, multiplayer games have a \"server-client\" architecture. To put it very simply, the server handles the game logic, and the client renders graphics, plays sounds, sends input commands and tells the server where it thinks you should be. (Which the server may disagree with, hence glitches where you get hit even though it looked like you didn't). Part of the server logic is a thing called an \"event handler.\" Which is *kinda* like a bunch of if statements, in that it is conditional, but it is more dynamic. For a very simple example, let's say a new player joins. An event, maybe called player_join, is triggered. The server sends some info to all the clients, which each run their own code to say \"Dr. Mux joined the game.\" It gets a lot more complicated than that, and I'd go much more in depth if I weren't on my phone at work.",
"There's a central server that acts as the dungeon master. Each player's computer has a network connection to that central server and sends messages like \"I swing my +5 Sword of Smiting at the giant rat\" or \"I cast Magic Missile at player 7\". The server then looks at the strength, armor, hit points, etc. of the target, along with your strength and weapon stats, rolls a virtual D20 (aka random number generator) and sends a message back like \"The rat eats your face\" or \"You just did 30 hit points of damage to player 7\". (Player 7 also gets a similar message.) Your game software then displays the appropriate animation. The server is, basically, a bunch of statements that handle every situation. There's a lot of database lookups involved. So if the server receives the message \"I try to move to position 323,719\", the server executes a function that looks up information from the map to determine if that's a legal move, and if so, how much progress you made. If it receives the message \"I swing the chainsaw at monster 77393\", it looks up your stats, the monster's stats, and makes the appropriate updates. The server has a very very long list of actions you can perform, and statements for each one. As the game evolves, the developers add new actions (do a little dance, make a little love, get down tonight, etc.) and add the code for those actions to the server. Then they issue a game update that includes those actions in the list of things you can do.",
"If you broke down every single computer program out there, basically yes. The programmers create abstractions on top so they're not literally writing every single if statement. But at the hardware level, it is effectively equivalent to billions of if statements. If a user clicks here then figure out what they clicked on. If it was a person do a command to attack. If you are not next to it start moving toward the target. If I need to move update the screen. If this pixel is where the character is change its color to match character."
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7h4vgu | Why does your voice become metallic on Skype/Discord when there are network problems? | Technology | explainlikeimfive | {
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"It is not unlike how sometimes an image gets pixelated when the connection gets bad. When sound is digitized, the [sound wave]( URL_1 ) is converted to a list of values that represent its amplitude. The human ear can hear sounds up to 20,000 Hz, so if there are about 40,000 of those values taken each second (known as the *sampling rate*) our ears can't tell the difference between the digital data and the original. More samples require more data, and if the connection cannot stream it all in real time, it will downsample, essential only using ever other sample, or every fourth one, etc. This uses less data, but also makes the wave [less precise]( URL_0 ), losing the higher frequencies, and making the mid-range ones squarer, kind of like autotune.",
"General \"my voice sounds different\" answer: A lot of it has to do with the compression of the audio data coming from your microphone. The human voice only uses a small portion of the audible range, so anything outside of there gets thrown away, and consequently some parts of your voice (overtones mostly). Once this gets sent to the other person and it comes through their speakers, it isn't the same soundwave that was recorded. Specifically when you have network problems: Not all of the data your computer sends gets to the other end, but the program still tries to put it together in the same order it was received. This creates more sharp-looking sound waves when played through a speaker."
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7ha954 | What exactly is the advantage of smartphones having all glass bodies? Is there a reason companies have been making the backs of their phones glass too? | Technology | explainlikeimfive | {
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"They look really pretty in product shots. Makes them look & feel \"luxurious\" even though glass is of course cheap as dirt, but plastic *feels* cheaper."
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7hag2w | How does a fridge work? | Technology | explainlikeimfive | {
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"HVAC guy here: Refrigerators work by TRANSFERRING heat from one location (inside the fridge) to another (outside the fridge). This is done using a chemical compound called REFRIGERANT (Like R-134). Refrigerant is a liquid that boils a a low temperature (R-134 boils at -15deg~F/-26deg~C) Essentially the refrigerant \"boils\" (absorbing heat inside the fridge) and then is pumped back towards the outside of the fridge where it \"sheds\" that heat. The process repeats continually using an electric pump (condenser) and fan as needed.",
"In thermodynamics they love cycles, usually in 4 steps. The one that applies for this process is the [reverse Carnot cycle]( URL_0 ). We start our cycle in point D: * D - > C is an isotherm expansion. As u/apatheticviews said: this is accomplished by using a liquid that boils at a low temperature. Boiling happens at a constant temperature (= isotherm) and expands a liquid into a gas (= expanson), and absorbs heat from the fridge. * C - > B is an adiabatic compression. The pressure increases (=compression), without exchanging heat to the environment (=adiabatic). This causes the temperature to rise. This step requires a lot of energy! * B - > A is the reverse of step 1, but this time on a higher temperature (above room temperature) so that it can transfer heat to your room. The heat has now succesfully be transfered from your cool fridge, to your hot room. * A - > D is the reverse of step 2, and recovers some of the energy you used in step 2. As with all thermodynamic processes: full reversal is not possible. The energy that isn't recoverable is the energy you will need to provide as electricity from the wall. Additional note: This energy you add as electricity also gets dissipated as heat to your room, as shown in the left diagram on the picture. Therefore, using your fridge to cool your room is counterproductive: all heat you extract is dumped in the room anyway + all electricity consumed in that process is also dumped as heat = > You'll only heat up your room even more.",
"Don't even ask me what internet hole I fell into this morning, but what are the odds that I ended up watching this 1963 US Air Force training video about the principals of refrigeration??? It seems fate wanted me to share it here today. URL_0",
"You see, matter is a bit claustrophobic. If you reduce the volume some matter has to its disposition, it gets agitated and heats up. Similarly, if you increase the room the same matter has, it becomes less agitated and cools down. A fridge or freezer works by transferring heat from inside the fridge to the outside room. It does this by circulating a fluid (the refridgerant) which absorb the heat on the inside, and release it on the outside. The way this works is by manipulating the state of the refrigerant with a low boiling point (around -15 degrees Celcius) from gas to liquid. The refridgerant starts in a liquid state and is pumped into the fridges walls & doors. There it absorbs heat from the air inside the fridge, which makes it boil making it go from liquid to gaseous form. Note that you can have matter at two states even if the temperature is the same! This is because instead of using the added energy to heat the matter up, you use it to convert it to gas. Thus the refridgerant is now at a gas state. The refridgerant is now run through a pump which increases pressure. This is the noise you hear when the fridge is running. Now since the pump to forces more gas into the same volume, the gas heats up. The gas is then fed through the condensator, the typical tubes/grills you see at the back of your fridge. The tube here has a wider diameter than before, which makes the gas less agitated, and thus it releases enough energy to condense into liquid again. The heat is therefore released to the surroundings. From here the cycle repeats and the now cooled liquid is pumped back into the fridge walls to transfer more heat. This is also how a heat pump works, just in reverse! tl;dr the fridge transports heat from inside the fridge to the outside by evaporating and condensing gas."
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7hakxb | If pictures are stored as a bunch of numbers, why can't you just create random new pictures by changing some of the numbers? | Technology | explainlikeimfive | {
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"text": [
"You can do that, but if you try to create a picture from completely random pixels, then in most cases (as in 99.9999999999999999999999999% of the times) you'll get [white noise]( URL_0 ) (well you'll get it in color, but it's the same idea). You need to have some algorithm that will make your image make some sense."
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7hfq5b | How does Google Maps show satellite maps of other planets and moons? | Technology | explainlikeimfive | {
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"text": [
"We have photos of those celestial bodies from various sources, including high resolution telescopes (for the larger and closer bodies), satellites (for the more explored bodies, like Mars) and space probes.",
"Yes, NASA has sent space probes to orbit the moon, Mars, Venus, and other planets to completely image them. All of the data is freely available to the public, too."
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7hfqw5 | why is it that if you refresh/go back/etc. on some websites it will save information you entered but not on others? | Technology | explainlikeimfive | {
"a_id": [
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"It all depends on the site but it has to do with cookies. Cookies are temporary stored information that are saved within the web browser. Some sites make it so if you’re on a certain page (like a sign up one) it will save the information that was assumed entered correctly. It’s mostly used for convenience but when sites don’t use it, it’s because it can be a security risk.",
"Simple answer: it depends how they are written. On a webpage every time you load a page from scratch is a totally new transaction and you've effectively started again. So, by default, when you load a form up again, it will have forgotten, unless the website programmers have explicitly saved what you wrote in last time and filled it in when drawing the page back again. Imagine a conversation between 2 people, one of whom, the Server, has severe face blindness and/or short-term memory problems. Customer: can you please get me the info for URL_1 please? Server: yes, here you go. Customer: OK, thanks. Hmm... Can you get me the info for URL_1 /interesting-news-story please? Server: yes, here you go. ok that's fine, it doesn't matter he can't remember who you are because everyone sees the same stuff. Customer: I want to log in so I can demonstrate to these idiots how correct my opinions are. Server, can you please send this username and password to URL_0 please? Server: Yes. Here you go. [Server sends back a custom page with a delicious cookie] Customer: OK now send this comment to nytimes,com/speak-your-brains \"lol no libtard wtf\" Server: can't sorry, I need to know know who you are. Customer: OK now send this comment to nytimes,com/speak-your-brains \"lol no libtard wtf\" - here is my cookie. Server: [looks at chart of photos of cookies and recognises yours (this is a weird metaphor)] Ah yes, Customer. I will post this and return a page. so actually you need to send the server who you are every time you make a request (that's what's in a Cookie). This won't contain your username and password but it will contain some kind of identifier, so they server will know who you are each time, and will look up and see that you logged in a bit earlier. OR it will see that you filled in part of a form earlier. To complicate things even more, you'll have a cookie given _every time_ you visit a website so you can be identified whether you logged in or not. Er rrr this got really rambling, I'll leave it to others to clarify my incredible mixed metaphor"
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7hk5wi | Why does autotune sound so bad in 2017? | It’s 2017. We have smart-everything now. Autotune has sounded the same since 2000s. How come it hasn’t improved since? Side question; why does autotune sound so bad in the first place? | Technology | explainlikeimfive | {
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"Autotune has been used, unbeknownst to the public, long before Cher's Life After Love, which is commonly credited as the first song to employ apparent autotune. Before then, it was simply used to correct pitch in studio performances. When applied thusly, it is nigh unto undetectable. When you can hear the autotune, that's intentional.",
"99% of the time you don't hear autotune/pitch correction when it's used as a tool and not as an effect. It's gotten really, really good and it's integrated into most recording software. Back in the day you needed a hardware unit or third party software, now it's a standard feature and it's used so much you wouldn't believe it. It's primarily used when you have a take with a few notes that are out of tune slightly and need to be fixed, which is cheaper than booking studio time or a musician to redo the takes. When you hear it like you're talking about, it's used as an effect. You may think that it's a cheesy effect that sounds bad, but artists make a conscious decision to use it in that way because they think it sounds cool. It can be used as a callback to tunes they were influenced by or are trying to emulate from the early 2000s. But it's just that, an artistic effect. If you don't like it in music don't buy that music. The reason it sounds \"fake\" is twofold, the first is the actual pitch shift and the second is how it is applied to the audio. The sweeping majority of pitch correction software essentially time stretches the audio (without changing pitch) and then plays it back faster or slower by the same factor. Both stages will have artifacts, or add crap you didn't want. Time stretching without shifting pitch is an old idea (it was done back in the 50s) but one of the things that happens is transients (fast changes in the signal envelope) get smeared or shrunk in time, and in bad cases can even be repeated giving you some pops and blips. When you speed up the signal after stretching it, you have to filter it or else you get \"aliasing\" which is high frequency garbage on top, if you slow it down you naturally filter the signal which rolls off the high frequencies. Now *even if* you have no artifacts from the shift, you have a problem which is that the general curve of the frequency response is shifted up or down. This is not how a real instrument works, where the curve is fixed based on the acoustics of the instrument/voice, but the individual harmonics move up and down. This causes the timbre of the instrument to shift with the pitch changes, and it sounds alien and unnatural. In general the only way around those problems is to only use tiny pitch shifts. Which is where autotune excels today, it's great for fixing tracks that are out of tune, not for changing the melody entirely. Now when the shift is applied it is done with an envelope, meaning the pitch shift is applied over time. The signal will ramp up or down to the new pitch, it isn't instant. The longer that ramp time, the more natural it sounds. When it's very short you get that T-Pain sound, as the pitch correction kicks in almost instantly rather than how a voice would naturally change."
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7hk699 | Is there any advantage to put the power buttons on the side of laptops or embedding them into the keyboards? | Technology | explainlikeimfive | {
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"text": [
"There are a number of reasons for the location of power buttons. Minimum length of connecting cables. Free space on the face maybe at a premium. Think of edge to edge screens. But hidden buttons by the keyboard are a great location. If you have ever accidentally turned off your phones display. Imagine doing that while working on your laptop without having your work saved. Some laptops allow you disable the power button. You can still power off, by holding for a longer time, but no more accidentally power offs.",
"Typically you would find these side power buttons on laptops that swivel all the way around to turn into a tablet. If you had the power button on the keyboard when a laptop is in tablet mode, it’d be an awkward push. Thus, it’s placed on the side for compromise. Source: I own a 2-in-1 laptop and it just makes the most sense."
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7hlmdo | How do screens produce the color black if it’s, physically speaking, just the absence of light? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Exactly as you say. They don't emit any light. It you turn of a screen it is black so turning of the light is enough for the pixel to be black. In practice it is not as black as a turned off screen types because the back light is always on and make it darker with a LCD that can block the light. It might look darker then when a screen if of but that is because you compare it lit pixels beside it or previous scenes."
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7hm6ae | Can hardware work without drivers? | Technology | explainlikeimfive | {
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"text": [
"Short answer: No Imagine your computer is person A and your other hardware (Lets say a monitor) is person B. Person A wants to tell person B is to flick the light switch. The driver defines how they will communicate. Maybe it's English, maybe it's sign language. But without it, no matter what person A does, person B has no idea that person A wants them to turn on a light switch. And there is no way person B can tell person A that there is no light switch in the room. Plug and play hardware works because a bunch of companies got together and told everyone else that is going to make a generic type of device (eg monitors, mice, keyboards, etc) that they need to speak in english back and forth if they want generic functionality to work. If the need to do something fancy, like sing, they can write their own language. But if they want to talk, they need to speak in English. For a lot of stuff, like mice and keyboards, this is enough. For other stuff they actually need to sign... and dance... and throw pies in people's faces. They need their own language.",
"No. The drivers make the hardware work. Some operating systems put drivers in the kernel and some have them separate, but in most cases drivers are needed, like for printers and things like that.",
"A driver is, by definition, the software that allows your computer to interface with hardware. For modern operating systems that do not let programs directly access hardware, there must always be some sort of driver telling the OS how to use that hardware. That driver might be a generic driver that came with the OS rather than something specific to that piece of hardware (eg - standards compliant USB keyboards and mice or running a video card as a generic VGA adapter) but there's going to be a driver in there somewhere."
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7hmd75 | What is happening when a video lags and loses quality but continues to play? | Technology | explainlikeimfive | {
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"text": [
"> What is happening when a video lags and loses quality but continues to play? The streaming service has detected that there isn't enough throughput of data necessary to maintain a full resolution video stream to your computer, but that a lower quality video stream which consumes less bandwidth can be supported. It lags for a moment as the stream is converted to the new resolution but it keeps going afterwards."
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7hmq34 | What are protection rings? | I keep seeing people write Ring 0, Ring 3, Ring -2, and have no idea what they mean. A quick Google search brings up Wikipedia but I find the explanation confusing. What are protection rings, what function or use case do they have and what happens if something “breaches” a ring? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"To be honest (based on several decades of IT experience) this is one of those things where people invent overcomplicated terms for something rather than just explaining it. I believe this is done in order to make this easier to make colourful charts of so that non-technical people can pretend to understand it. Basically, an operating system has different levels of privileges. The highest privilege (or lowest \"ring\") has access to everything. Letting everything have that kind of access is obviously bad, so we reduce privileges for processes that don't need them. For example, a device driver would need *some* privileges, but not all, so you put it on a different \"ring\". An end-user program needs even less privileges, so you put it on an even farther ring, etc. Again, basically an overcomplicated way to \"simplify\" something that wasn't really complicated to begin with.",
"x86 hardware has a number of privilege levels. * Ring -3 is Intel AMT, a server management functionality. It allows remote control of the computer, even while it's sleeping. * Ring -2 is the System Management Mode. It's firmware that runs outside the control or oversight of the operating system. The code does things like fan control, reacting to hardware error events, emulating some old functionality like PS/2 mice and keyboards, etc. * Ring -1 is the hypervisor. It's used for virtualization. * Ring 0 is where the operating system runs. This includes device drivers. * Ring 1 is unused. * Ring 2 is unused. * Ring 3 is where applications run. This separation makes it impossible for your web browser to do any arbitrary thing it wants without going through the operating system. Rings lower than ring 0 are worrisome because they're outside of the control of the operating system and the user. The code is effectively invisible and undisclosed, and any vulnerabilities there make it possible to access the computer remotely in a way that's undetectable to any software running on it."
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7hntv3 | Why do small stripes show up distorted when displayed on a screen in a picture or video? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Because a screen is made of many individual pixels. Imagine a classroom with 5 x 5 desks where each desk is a pixel on a screen. Now, you take a string and move it about the desks. If the string intersects a desk, that person stands up. It's easy to make lines of people that are horizontal and vertical. However, things get strange if you start making the string diagonal. You can have every person stand up but then the line looks fatter than usual. You can have fewer people stand up but then the line looks like it has breaks. This is known as aliasing. It's difficult to display small things (usually lines and edges) on screens simply because pixels have a certain size. By making pixels smaller, you can reduce this effect (phone screens have very high resolution despite their small size). Other methods such as anti-aliasing selectively blur these edges so they do not appear as distorted."
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7hopme | Why do downloads, file transfers and renders always seem to linger on 99% longer than any other percentage? | Technology | explainlikeimfive | {
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"text": [
"I dont know how accurate this is, however at the end of the download i assume this is the whole package being checked for errors and any missed packets or segments are redownloaded to ensure it is complete",
"There can be a vast number of factors that affect progress reports including bugs, design flaws, and programmer laziness that may make progress bars behave illogically. Some bars could get stuck, go backwards, freeze, or spend inordinate amounts of time at certain percentages depending upon the implementation of the progress bar by the programmer making every progress bar unique. Often there could be a last routine run before 100% is reported to check for issues or perform an action which may take longer than each percentage point before 99%, for example, writing a file or log to the disk. The are innumerable factors, including your own confirmation bias."
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7hrjxy | why are some electric toothbrushes cheap and others in triple figures ? Do they actually provide a oral hygienic difference? | Technology | explainlikeimfive | {
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"I currently use a Philips Sonicare. It cleans better than a cheap electric tooth brush and the vibrations are less course. So the difference between a cheaper and more expensive electric toothbrush is the method it uses move the bristles and the cheaper ones tend to be cruder. my dental hygienist noticed when I switched to the more expensive toothbrush and I usually require less scaling. I still have my wisdom teeth, so an electric toothbrush is the only effective way to clean back there",
"Some do, but it's mostly marketing. Phillips has funded studies that show their toothbrushes are better, and while statistically significant, the actual benefit to your health is marginal. In general, if someone is being watched during a scientific study, their oral hygene improved. They're less likely to skip brushing, a researcher is giving specific instructions on how to brush, etc. An electronic brush seems to be better than a boring brush. URL_1 But the specific brush requires a clinical trial to prove it's better than anything else. You certainly FEEL better if you believe your toothbrush is better because it's expensive. Placebo effects on health are a real thing. But to control how much is placebo vs. how much is the toothbrush, we need studies. Here's a study that shows Sonicare is superior to Oral-B. URL_0 But personally, sure, maybe the fancy toothbrush vibrates harder at a higher frequency, but I'd question the value of $250 for slightly whiter teeth. If you think that's worth it, feel free to splurge.",
"Both my dental hygienist and dentist could tell I switched to a sonicare before I told them. They said it was the best they've ever seen my teeth (I've always had a lot of dental issues). It makes a HUGE difference. Edit: thought this was askreddit so I didn't actually explain anything. The biggest difference I've noticed between the cheap and expensive ones is the amount of work you have to do. Most cheap electric brushes are basically just manual brushes that vibrate, so you still have to brush the way you would with a manual brush. With the sonicare you just gently touch the bristles against your teeth and slowly move it around your mouth. It vibrates every 30 seconds to indicate when you should switch quadrants. After 3 months of using it I had the least amount plaque on my teeth for any dental checkup in my life, and after using it for 2 years, it's the first time I've gone more than 2 checkups without a cavity. It has literally saved me thousands of dollars at the dentist.",
"While I'm not sure about them cleaning objectively better the more expensive ones will have rechargable batteries, Bluetooth integration, and replaceable heads."
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"https://www.ncbi.nlm.nih.gov/m/pubmed/28392215/?i=10&from=electronic%20toothbrush"
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7hrq9b | How can businesses immediately tell you that your card has been declined? Are all card readers connected to the internet and what is the universal network they’re all connected to? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Yes, card readers communicate to the bank over the Internet to validate transactions in real-time. It used to be phone lines but today it's almost all IP in the US and Europe.",
"Yes. Credit cards and debti card machines, when they say \"Authorizing...\" they're phoning home to query if you have a balance large enough for what you are trying to buy. They don't phone YOUR bank directly, they're phoning through a network. Here in Canada its Interac, a big one in the US is the Plus network... there are most likely caching servers on their network that have just your balance and daily withdrawl limit saved. When your bank updates your balance, they probably send a new balance to the network. Theres intrabank networks in every country (because banking laws tend to be at the national level), but VISA and MasterCard run global networks.",
"Yes, they're all online. The card reader calls the credit card company's computer system with the card info and the amount to be charged, and the system says \"yes\" or \"no\" depending on various factors. If you don't have enough credit left or if the card is frozen, then the answer that comes back is \"no\" and the sale doesn't happen."
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7ht8n2 | How was the Playstation 3 able to perform so well with only 256MB of RAM? | The PS3 and the Xbox 360 were able to run games like GTA V and only had 256MB and 512MB of RAM, while on PC the minimum requirements are 4 GB of RAM. | Technology | explainlikeimfive | {
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"PC run Windows OS that multipurpose generic OS that will consume 2+ GB of RAM on it's own plus there is other software running at the same time so with 4GB of there is not even 2GB left for the game. The game on console can be fine tuned to specific configuration of the console. On PC it must be prepared to work with different configurations. PS3 has lower details. The thing about computational complexity (how it is hard to compute something) doesn't have to be linear."
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7hvvsy | Why is it that we can transmit sight and sound over the Internet but not smell, taste, or touch? | Technology | explainlikeimfive | {
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"Sight and sound are senses designed to detect waves of energy coming from far away. Smell and taste only detect real molecules that actually *get into your head,* nothing remote about that. Touch could be simulated, and there are some prototype devices that do it.",
"Sound is really simple. Air vibrates with a certain simple one dimensional wave, it simply goes up and down in pressure over time. This is sound. We simply record the pressure at a very fast interval. We then send it as a string of numbers. On the other end we have a variable voltage source match these values, it drives an electromagnet near a diaphragm with a magnet on it (aka speaker), the diagram vibrates just like the original air, it pushes the air to vibrate with it. If you want to get complex, you can have a left and right channel, or even more, but it's still just a string of numbers. In short, audio is just a string of numbers telling you the air pressure at time intervals, and that's all sound is. Sight is slightly more complex. We take a grid of light sensor, each sensor records the intensity of the light falling on it, and we record this as numbers. This means we have a number for each sensor (aka pixel). That only gets us a single still image though. We then repeat these light intensity measurements at a certain time interval (aka frame rate) and we get a video. We send this much large string of numbers over the internet. And on the other end, we simply use these intensity values to adjust the brightness of a bunch of small light arranged in a grid again. If you want to get fancy, you record the light intensity of red, green, and blue seperately, and you get colour video. In short, video is just a string of numbers for mutiple locations telling you the light intensity at time intervals, and that's all sight is. Touch we can and do transmit. Ever used a videogames controller? That rumbling, that's touch transmitted over the internet if your playing an online game. Same goes for the vibrate on your phone. We could go more complex, but you'd need a masisve full body suite that can apply pressure and temperature all over you body. You really could make this suit and transit a string of numbers for pressure and temperature on every inch of your body over the intenet. It's not really an internet limitation, just a cost and practicality issue on the receiving end to reproduce it. Smell and taste are pretty much the same thing. A chemical that our body reacts to a gives a sence. So while we could easily transmit a string of numbers coded for chemicals over the internet, how would you get the chemicals on the other end? Well, you could make a machine with a large amount of the chemicals you can smell/taste and have them emitted on command. Again, it's not really an internet limitation, just a cost and practicality issue on the receiving end to reproduce it. We do crappy job of transmitting smell with \"scratch and sniff\" paper, you could easily do basically the same thing over the internet. Have a robot taking commands over the internet scratch the right one. That's (very limited) smell over the internet I guess. That said, if we could interface with our nervous system, that is fake senses with electrical impulses our nerves could read, then we could send whatever sence we wanted over the internet. However, we don't understand our nervous system well enough to do that. So for now, transmitting senses means you need to actually recreate the physical condition on the other end. Moving air or turning on some coloured light bulbs is easy. Actually touching and warming or cooling every inch of someone's body is not. Nor is releasing a plethora of chemicals from a vast storage vault of all possible smells/tastes on demand into a room or someone's mouth. TL;DR:. We could easily send a list of chemicals over the internet (smell/taste) or a list of temperatures/pressures and locations (touch) over the internet. It's really not that much harder than a list of air pressure (sound) or light intensity and location (sight). The issue isn't transmitting over internet, it's recreating them on the other end."
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Subsets and Splits