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7b6hpk | How can someone recover files that were permanently deleted from a drive? | Technology | explainlikeimfive | {
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"Deleting a file is like abandoning a self-storage unit. All the stuff is still there, it is just marked as available. If someone needs that space, the old stuff is cleared out. The main difference is they don't make crappy reality shows about deleting files.",
"Permanently deleted? they can't. But computers rarely permanently delete files. What they do instead is mark the space as okay to be overwritten. If nothing is saved over it, then its still there, but you won't run into the problem of filling the drive because it will simply overwrite that space.",
"Most delete operations don't delete the file, they delete the record of the file. This is sort of like the difference between condemning a building (the space that building occupies can now be reused) and actually knocking it over (the building is removed and something new is put in that place). Unlike construction, computer files can be overwritten pretty easily and the process isn't very different than writing it over previously empty space. So at some point in the future, a new file will be written over the old data. So recovery process recreates the records of the file, and it works when the space hasn't been reused. Note that there are file deletion applications that actually overwrite the data that was in the file's location (usually several passes with all 1s or all 0s) to increase the difficulty of recovering data that's intended to be securely lost. It doesn't really matter if the \"blank space\" on the drive is old files or nothing, the two are pretty similar to for the operating system and hard drive to overwrite. Think of building a sand castle in a place where there may be some remnants of an old sand castle, vs a place where there are just footprints, you still need to smooth the surface to start your own sandcastle."
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7b8o6u | In video games, other than namesake, what's the difference, if any, between saving and quick-saving? | Technology | explainlikeimfive | {
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"Almost nothing. Its the same difference as Save-As vs Save on a standard document. Save As (normal save) gives you options as to where you save it, what you overwrite, what you name it as, etc. Save (quicksave) just immediately saves it to a standard named file in a default location."
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7b9evp | How do the heart rate monitors at hospitals work? | First, what is the official name of those machines? I keep calling them heart rate monitors but I feel like that's more accurate for something you wear around your wrist, not one of the machines with the beeping and squiggly lines. Second, what do the squiggly lines indicate? What does the peak mean? And the valleys? (Not sure what else to call those parts...) Third, at what point on the squiggly lines does the machine beep? I wish I knew more of the technical terms but I guess that's why I'm asking all these questions here! Thanks in advance :) | Technology | explainlikeimfive | {
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"It depends on which monitoring machine you're talking about. There's a Cardiac Monitor (also known as \"Tele\" for \"telemetry\") that uses leads on your chest to trace the heart's electrical activity from different angles. The heart normally goes through a highly organized electrical pattern and changes to this pattern can tell you alot about the heart's functioning. There's also a Pulse Ox machine attached to your finger that measures both heart rate as well as how oxygenated your blood is. This is called a plethysmograph tracing. Technically, it's measuring the changes in light absorbance of the blood in your finger, but it correlates nicely with your pulse. You generally want to have a smooth, uniform waveform. If it's chaotic and haphazard, the machine isn't getting a good signal and may be incorrectly calculating the oxygenation level of you blood."
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7b9jgy | how do the popular search algorithms - the kind we see solving mazes - work? How are they different from one another? | Technology | explainlikeimfive | {
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"IT graduate here. I'm going to talk about two algorithms: The greedy depth first search, and the A* (A Star) algorithm. Imagine you are walking through a maze; you know where you started, and you have a rough idea which direction the end point is. Depth first search - whenever you come to an intersection you take the path that you think is closest to the end point. You keep following this path until you get to a dead end at which point you go back to the last intersection and this time take the opposite direction from what you did last time. A* - whenever you take a step you make a guess of how far you are from the end point, and you add that distance to how far you've already traveled from the start point. Each time you come to an intersection you make this guess twice and compare weather you should go right or left. Let's say in this example you turn left: if you keep walking and it turns out longer than what it would have been if you'd turned right then you turn around and take the right turn instead. There are a lot more complexities and many more algorithms beside these two, but I've tried to ELI5 this as much as I can.",
"There are lots of different search algorithms out there, they are typically designed with a particular problem in mind. The one you see solving mazes is pretty simple, always turn left, when you reach a dead end turn around."
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7b9mjf | how do the servers know a game is pirated, like if you had a pirated copy of C.O.D what happen s to stop you playing online? | Technology | explainlikeimfive | {
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"Old games used to just want to connect so servers would let them play. Now a days with faster connection, the first message your game sends to the server is the exact version of the game and the serial number of the copy and a signature of all the parts of the computer(processor, Ram, graphics card, sound card ect) and the IP address exact version of the Operating server ect. The server then looks up the serial number of the key with its database to realise that it has already been given to an other completely different computer with a different IP and not the same patch of the OS. It now safe to say it is a copy. Eli5: you call from a number. It is linked to your voice, speech pattern, the noise in the back and the caller ID. Same day, somebody with a different voice on a different caller ID, and a thick different accent call the same number pretending to be you. The person at the other end now knows it is not you."
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7bbbaq | How does a download know that it's receiving the correct data? | Technology | explainlikeimfive | {
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"The transmitter creates a *checksum* for each packet, plus typically another one for the whole file, in which all the bits are put through a formula and a number calculated from all of them. The formula is designed so that any small change in any of the bits will result in a different (non matching) number. The receiver recalculates the checksum, and if something doesn't match, it can tell that the data contained an error, and it requests retransmission."
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7bc0ex | How do cars know how much gas is in your tank? | Technology | explainlikeimfive | {
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"Inside the gas tank there's a variable resistor connected to a float that goes up/down depending how much fuel is in the tank. The value of the resistor is then sent to the car's computer/fuel guage."
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7bd9bh | why can't 32 bit or 64 bit Windows run 16 but apps? | Technology | explainlikeimfive | {
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"The difference isn't so much in the \"number of bits\", but rather in the fact that 16 bit apps are old and are designed for an entirely different runtime and file format and they require a completely different set of dependencies. They're now known as \"16 bit\", but the reality is the operating system's kernel was completely different at the time, and the apps were designed for that particular kernel.",
"Because newer Windows isn't designed to read/run 16 bit apps. As far as I understand it, it's not a hardware issue, a 64bit processor could handle anything up to 64bit, but if the software wasn't designed to handle 16bit apps, it won't.",
"32-bit Windows **can** run 16-bit applications but you have to enable the legacy [NTVDM]( URL_0 ) feature first. This can be done by typing (at an elevated command prompt): fondue /enable-feature:ntvdm 64-bit Windows does not support 16-bit applications because Intel processors in long mode do not support 16-bit real mode and virtual 8086 mode. As the NTVDM uses virtual 8086 mode to emulate a Windows 3.1 environment, this would have required extensive modification to enable support for 16-bit programs. Market demand dictated that this was not worth doing. Workarounds include the use of virtual machines and the open source DosBox program."
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7bdksq | How do they make old songs sound clear in movie trailers? | Technology | explainlikeimfive | {
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"Large Hollywood movie production studios have contracts with many large record labels for access to their original master recordings of music, and for more popular songs, the record labels can also sometimes provide the individual unmixed track recordings of those songs. Basically, the movie studios can get separate high quality recordings of the drums, vocals, horn section, guitar, piano, etc, and completely remix the song to fit the context of the movie/trailer. As far as making the tracks sound “clear”, this is either just done by having high quality recordings, or the audio engineers have added some sort of compression, equalizer, or other form of effects processing to the tracks to give them and crisper, more modern sound. EDIT: These multitrack master recordings and the individual tracks are referred to as “stems.” I was not aware of this term at the time of writing.",
"Audio sweetening is a big field. As some others mentioned, studios try to get the best original sources they can find. When media has degraded they'll multiple different sources, each the highest quality they can find. These will be integrated together. There are many noise reduction techniques out there. Many begin by transforming the clips from temporal data (the waveforms you are probably used to) into frequency data (often visualized [like this]( URL_0 )). When working in frequency space the data is more like a speckled image rather than waveform data. Constant frequencies, such as a 60 Hz electrical hum, can be removed; as frequency data that can mean erasing or cutting down (perhaps to 10% of their old value) at the 60 Hz line. Many noises are easily visualized as long lines or dark areas when viewing audio as frequencies, and they can be digitally removed or have their intensity reduced. Frequencies outside the regular voice range can be removed; the sound engineer can start by dropping everything below about 300 Hz and above about 3500 Hz, then fine tune the range based on what they hear. The traditional high-pass and low-pass filters used in analog equipment do the same type of work, only less precisely. Mixer boards, both digital and analog, do them on a coarse scale. They cut both the high-frequency sounds and the low-frequency sounds, and can be used to boost or drop different frequency bands as needed. The big mixer boards with tons of sliders that are shown at concerts do this, allowing the sound engineer to modify different frequencies of noise during the live event. Reverberations and echos can be easily added, and with some software can be scanned for and removed or reduced. Multiple recordings can be mixed together. If the quality of old tracks is not good enough new recording can be mixed in. If part of a word is unclear in the original recording, a voice actor can sing the lines in a similar voice, and the sound engineer can align the sound sample, adjust the pitch and volume, and blend the two together. It may be Sinatra you hear, but there may be a mix of singers that have been skillfully blended in. Similarly for orchestral parts, new violin recordings, cello recordings, or flute solos may be recorded and mixed in. There is far more -- it is an entire industry with signal processing math, specialized software, in addition to artists and engineers involved -- but that should give an idea of how it works.",
"There are two other major possible ways to make it clear. First studios will go through and clean up old recordings or use remasters to make it sound clear. Second, although used less frequently, sometimes they will rerecord a song with an voice actor that can impersonate a persons voice and a Hollywood orchestra for the instrumental part.",
"When possible we get high quality remastered tracks of each instrument, called \"stems\". These stems allow us to basically remix the track as needed, pulling out parts we dont want and boosting ones we do to modernize and \"trailerize\" the music cue. Also, most of the songs you hear are not simply the song. Usually we have a music library company add some additional elements to it, like more drums, or a rise, or a string element, etc. On top of that, you have all the sound effects you typically hear in trailers, (the Hits, the Rises, the BWAAMS, etc) that can sound like part of the song when cut rhythmically. source: am trailer editor.",
"Any song can be remixed to sound \"clearer\" with proper compression. An audio engineer can use the equalizer to filter out any frequencies that don't sound good to the ear, and make the song more \"modern\".",
"Aside from the obvious (remastered stems, etc) it's also true that things sound different at high volumes in a theater environment than they do on your car radio or earbuds. It's harder to discern audio quality when it's being blasted at you in surround sound.",
"I actually work in a studio that does this very work! I’m an imaging specialist so I can’t speak for the specifics of the audio engineering aspect, but the place I work has literally millions of master recordings stored for different record companies, and they are digitized for the very purpose you described (as well as preservation and restoration). Check out this video to see where the work is done (and my office!): URL_0",
"Probably a combination of the following.... 1) access to a high quality source, possibly the original master recording on tape. The audio quality of a tune someone put up on YouTube, your parents cassette collection, a worn out record or even a CD might not be anywhere near what it was when the track was originally recorded. 2) Compression. Trailers and commercials are notoriously over compressed. This means the loud sound in a piece are squashed down a bit and the quieter sounds are boosted giving the whole thing more power and punch but making it a lot more fatiguing to listen to for longer. It’s kind of like how they say a sweeter drink might taste better at first but but by the end you might prefer one less sweet. This is why people complain that many commercials are much louder than the TV or Radio program they are listening to. Compression allows the whole thing to be made louder without blowing out the speakers or our ears during the loudest parts.",
"Remastering. Basically you take the original recording which is probably on a big roll of tape and feed it through a machine that lets you 'tune' it. In the older days it was an actual machine that had sliders and knobs for turning these parts up and this part down and clear out this scratchy sound, etc. These days it all goes into computers that do the same thing. Some programs even have interfaces with virtual buttons and knobs for those that want to feel like they have their mixer again. Those mixers were the size of a dinner table btw, like a full on Thanksgiving sized dinner table. Source: Dad's a producer, he had one of those for years until they cleared it out to make room for bigger speakers and newer tech. It had mostly been used as a table/cat bed for the last 10 years of its life and was incredibly expensive back in the day. But when they got rid of it it was worthless pretty much unless they wanted to find a collector which they didn't have time for."
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7behyz | how do “smart” products save on electricity bills if they are always on? | As above. Smart lighting is supposed to save on energy costs but if they are always on and waiting for a signal, surely they are expending more energy than if it was a normal bulb turned on and off at the socket? The same question applies to smart plugs. | Technology | explainlikeimfive | {
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"The amount that these devices consume for the purposes of waiting for a signal is very small. The idea is that the amount of energy saved by the primary utility of the device (the light bulb, or the device plugged into the smart plug) being on less because the smart circuitry turns it on and off as needed far exceeds the amount of energy that is consumed when the device is not operating but is communicating with the controller. In other words, you might spend an extra two cents in \"smart controller\" power to save 30 cents on power consumption.",
"They use about 2W or 3W when \"off\" which is most of the time. Let's say this means your 150W lamp or TV stays on for 1 hour less each day. The savings exceeds the waste. Even better if you get a very efficient device that uses under 1W when \"off.\" The savings are of course proportional to the energy involved, so a \"smart\" air conditioner or heater is your best investment here."
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7belfr | How are locks mass produced such that they all require different keys? | Technology | explainlikeimfive | {
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"They aren't as unique as you think. Even if they made only 1000 different keys, the chances of someone both having the exact same key as you *and* trying it in your lock are basically zero. If someone wants into something you have locked with a mass-produced lock, they will pick the lock or bypass it completely. They can't really just go around hoping their key will unlock something, especially since using the wrong key can get the key stuck or damaged."
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7bgri3 | How are files moved with SFTP and AS2? | So, my school participates in a program to encourage girls to get interested in math and science. Last Friday, we visited a local business that moves a lot of data. They said they move millions of files every month using SFTP and AS2 (IBM software, no idea the name though) I wrote what I could down in my notes and went home to do some research. After searching around (Reddit, Youtube, etc.), I have a basic idea of what the SFTP and AS2 protocols mean and a very basic understanding of how they work, but I'm still wondering how the files actually move. For example, if my question was going to be sent to another person using SFTP or AS2, how does that work? How does the actual letters get transformed and reassembled from one computer to another? Thanks in advance!!! | Technology | explainlikeimfive | {
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"Files aren't letters. They're saved as millions of blocks of 0's and 1's. That information is broken up into chunks and encrypted and transmitted to the other side. Imagine secret code Morse signals. The receiving side receives the signals, decrypts it, and then saves it onto their storage device",
"> For example, if my question was going to be sent to another person using SFTP or AS2, how does that work? How does the actual letters get transformed and reassembled from one computer to another? A file is a series of bytes. A byte is just a number between 0 and 255 inclusive. (In base 2 numbers, you can use eight binary digits to write any number between 0 and 255. We chose to use eight binary digits just because. Some older computers used six or ten.) If you want to put text into a computer, you have to come up with a way to make numbers mean letters. You need a function that maps between them. There is no one right way to do this, but we've come up with some ways that work okay. ASCII is one of the most famous and widely supported methods. Someone just decided that they'd represent the symbols you can type (along with some others that made sense for controlling the computer hardware at the time) as numbers between 0 and 127. A byte, except you use one binary digit less, just to leave space for later. Let's say you want to write a famous quote, like: \"Sen luktado, ne ekzista progreso.\" (Without struggle, there is no progress.) You look up each letter and symbol in the ASCII table: `S` is 83, `e` is 101, `n` is 110, ` ` (space) is 32, and so on. And you put those in binary: 01010011 01100101 01101110 00100000 Hard for you and me to read, easy for a computer to read. But we can teach the computer how to show us the right letters for each of these numbers. > I'm still wondering how the files actually move. The \"explain like I'm a computer program\" version is found in the series of links [here]( URL_0 ). If you really want to learn things the hard way, you can have a go at it, but I would have trembled at reading those RFCs when I was in college. SSH is a protocol built on top of TCP/IP. TCP/IP is about the lowest level of networking you'll ever need to know if you become a software developer. TCP/IP is a protocol that allows you to send a series of **packets** of data to another computer and get a series of packets in response. A packet is a blob of bytes that starts with a bit of metadata: who it's for (the IP address and port), who it's from (also an IP address and port), how long it is, some other stuff that tells you how to send the packet around. See, the internet is a series of tubes, and you can send a ball bearing down a tube, but it's a lot harder to send a basketball... Anyway, you break up your data into a series of packets that you can send one at a time so you don't overload everyone's network hardware and so you can resend only a little bit of data if something gets lost. The SSH protocol adds on authentication and encryption. You can prove who you are to the other computer, and it can prove who it is, and the data passed back and forth is obscured so nobody else can read it. The SFTP protocol adds on a series of commands. Each packet starts with a length (four bytes) and then a type indicator (one byte). The type indicator can be a command, like \"read data from this file\", or something that tells you what the data in the packet is about, like a blob of data read from a file, or a list of file attributes (size, last modified, etc). So to send a file with SFTP: 1. Create a TCP/IP connection. 2. Open an SSH connection on top of that TCP/IP connection, set up encryption, and authenticate. 3. Open an SFTP connection on top of that SSH connection by sending a packet with type SSH_FXP_INIT, aka \"start doing SFTP things\". 4. Open the file by sending a packet of type SSH_FXP_OPEN. We need to tell it the file path we want to open, that we want to write to that file, and potentially some extra bookkeeping info. The server will give us a handle we can use to refer to that open file. 5. Write data to that file by sending a packet of type SSH_FXP_WRITE. We'll give it the file handle, a number (byte offset from the start of the file) saying where to write the data, and the data to write. 6. Close the file by sending a packet of type SSH_FXP_CLOSE, again sending the file handle. It's a little verbose, but it works."
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7bhgud | How do elevators for extremely tall buildings work? | There obviously is some kind of code, but how does the elevator know where to go and when? | Technology | explainlikeimfive | {
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"Typically the ground-floor elevators each visit only a certain range of floors (e.g. \"express to floors 30-45\"). For *supertall* buildings there is an express to a *sky lobby* from which new, different elevators go to higher floors. URL_0"
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7bhrqb | Why is it that we have emojis but have yet to utilize bold, italics, or underlining in text messages? | Technology | explainlikeimfive | {
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"The chosen method to implement emojis was to add each one as a Unicode character. Messages remain just a sequence of characters with no mechanism to add \"markup\" for formatting such as would be required to have italic and bold text. Unicode explicitly refuses to add character variants like italic and bold for several reasons including: it would greatly multiply the number of characters needed; and it would make searching for text very hard, because then abc would not match *abc* or **abc** ."
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7bkh77 | What is the purpose of having a Concert hall volume option? | Technology | explainlikeimfive | {
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"The purpose of the setting is to digitally simulate the slightly delayed echo effect of a large venue. While in a small room (like the typical location of a household computer) both the soundwaves coming directly at you and the ones bouncing off your walls, floor, etc, hit you at essentially the same time from a human perception standpoint; you are technically hearing an echo, but your brain doesn't bother to process it as a separate sound. As the room gets bigger, the longer it takes for the sound bouncing off the walls and floor to reach the ear, eventually reaching the point where the echo starts being processed on its own. For classical music in particular this echo (or reverberation/reverb) was both an obstacle and a tool, as the composer would need to adjust their performance for individual venues to properly account for the reverb, but could also integrate it into the performance for a more 'full' sound. More information on reverb and reverb settings (particularly from a music production standpoint) can be found here: URL_0"
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7bksmy | How does the text summarizing alghorithm work? | Technology | explainlikeimfive | {
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"I do text analysis/extraction for a living so this is my thing (I've only been doing it for a year, so I'm no expert). I skimmed the algorithm posted by rift95 (he deleted his comment so here is the link he posted URL_0 ) and will try to explain it (assuming I understand it correctly). Basically you rank each sentence in a paragraph based on some factors (will explain later) and the sentence with the highest score is the best summary for that paragraph. Do that for each paragraph, and you have a list of best summary sentences. Then you make a summary paragraph by chaining those summary sentences together. The ranking of each sentence is determined by how many words in that sentence appear in other sentences. (i.e. The score of a sentences is the sum of all its intersection). edit: Also a good implementation would give more important words get more points (e.g. prepositions don't give many points, keywords like location names and people names get more points). Here's an example paragraph I made: We bring you this new interesting story. This is my favorite news because we talk about the President. This Tuesday President Trump went to China. What will Trump do next? Notice that not many words in the first sentence appear in other sentences in the paragraph. This means that it will get a low score and be a bad candidate for a summary sentence. The third sentence has words like \"Trump\" and \"President\" which not only appear in other sentences, but are also proper nouns so they would be given more points. I need to go to a meeting so I'm cutting this explanation short. Hope someone found this interesting or helpful!"
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7bne7n | The true difference between i5 and i7 processors | Technology | explainlikeimfive | {
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"The biggest difference between i5 and i7 processors is the number of concurrent threads they can handle. i7 processors are equipped with hyperthreading, which is a technology that allows a single processor core to do almost as much work as two separate cores. Imagine a single processor core is like a chef. Both the current generation i5 and i7 processors have 6 chefs. The chef receives a set of ingredients and a recipe, and lays it all out on the table. This table is like a processor's cache - it's the memory that the processor has to work with. The chef then prepares the meals, and puts them back on the table. Now, the chef has to wait for the waiters to clean up the table and bring new ingredients. The chef busts out his phone and takes a break while this happens. Hyperthreading is like giving the chef 2 tables. Now, while the chef is cooking one set of meals from table A, the staff can clear table B and bring new ingredients. Once table A is complete, table B is ready for cooking. The chef can now switch back and forth between the two tables and have almost no down time. One of the other big differences is the size of the table - that is, the size of the cache. i7's generally have larger cache sizes than i5's do, which can help them do more work in the same amount of time. Edit: Just realized that I didn't really help you make a decision. :) Having more cores is only useful in certain situations. When the work can be 'parallelized,' - that is, divided up such that the result from one chunk of work doesn't depend on the result of the previous chunk of work - then being able to handle more concurrent threads is a very good thing. For example, if you're building a house, you need to pour the foundation before you can set up framing, and you need to set up framing before you can run electrical and plumbing lines, and you need to set up electrical and plumbing before you can put up drywall, etc. It's not possible to split a task like that up into several chunks and do them all simultaneously. If you're building 20 houses, you can pour all 20 foundations at once, set up all 20 frames at once, etc. The result of building part of one house doesn't depend on the construction of other houses. To a CPU, gaming is often like building a house. The calculations for one moment in the game will influence subsequent moments in the game, so it's not possible to divide the work up among several processor cores. Video editing, on the other hand is highly parallelizable. Rendering frame #25 doesn't usually depend on the results of rendering frame #20, so software can divide that work up and distribute it across the processing cores. TL:DR; Gaming doesn't usually benefit as much from multiple processing cores. Results will definitely vary from game to game though. Video editing often does benefit from more processing cores, so you can reduce rendering time significantly by using an i7 instead of an i5.",
"Quick shout out to /r/PCMasterRace and /r/buildapc. The daily simple questions thread in the former might be a big help to you going forward. Now, onto your question. Generally speaking, the difference between i5s and i7s (in the desktop realm, laptops are different) is the number of threads. This basically means how many tasks the processor can do at one time. You can picture it like pieces of paper. In the i5 scenario, each piece of paper can only be used for one thing at a time. So, if you want to doodle, an entire piece of paper has to be dedicated to doodling. In the i7 scenario, each piece of paper can be used for two things at a time. So, if you want to doodle *and* take notes, your piece of paper can handle that. The slight catch here is that software has to be programmed in a certain way to take advantage of multi-thread technology. Most modern programs do this, but some still don't which could lead to a situation where you have a piece of paper that can handle both doodling and note taking, but the program (person) using the paper is like \"no, this paper is for note taking only.\" PS for CPUs: AMD also makes processors that you may wish to look into. They generally have lower single core speed (smaller paper), but more cores and threads (more papers overall). Their current line is called \"Ryzen.\" Bonus: GPUs (graphics cards) are basically processors (and RAM) specifically designed for visual calculations and outputs. Feel free to ask more. :)",
"ELI5 is not really the right place to get the help you are looking for, u/bendvis gave a great answer to i5/i7 but that does not answer the questions you don't know to ask yet. To add some answers about the rest of the system, you really want to educate yourself before rushing out to buy that shiny i7 and 1080ti, you should check out r/buildapc. You say you want to build for gaming and video production. What kind of gaming? Is it match 3 clickers or you trying to play ArmA? The hardware you choose depends on the task. What sort of videos are you producing? Gaming youtube stuff or you rendering output from a high end camera? You will want different hardware if you are streaming vs local recording. What sort of budget are you working with? All these questions are asked and answered all the time at r/buildapc. Welcome to PC, it is not supposed to be easy because that is no fun."
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7bo0ul | Unix shell accounts - what are they? | Technology | explainlikeimfive | {
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"In Unix, the shell is essentially the command line interface. Linux, an operating system designed to be *very* similar to Unix also uses a shell as the command interface. Now-a-days it's easy to download an installation package and install Linux on your own computer. Back in the days when your friend told you how desirable a shell account was, it was much harder to get your hands on a copy of an operating system like Linux. Instead you could pay extra money to your ISP and get a shell account on *their* installation of Linux. This was helpful if you wanted to learn about operating systems and advanced programming. The Unix/Linux systems give users a lot more access to the inner workings of the OS so they make great learning tools."
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7bqwjf | How do computers understand what they were programmed to do? | For example, in java if you write if , how does it know what an I or F is? How did it suddenly just read English and make sense of it??? Eli5 pls. | Technology | explainlikeimfive | {
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"At a very low level, computers only understand how to do simple arithmetic operations, obey simple logical rules like if, and, and or, and store/load values in memory. Basically anything humans ask a computer to do has to be translated into the discrete set of actions you're asking the CPU to do in those terms. There are different types of software that do this translation for different programming languages and it can get very complicated, but at the end of the day their job is to turn code you've written into discrete actions your computer needs to perform.",
"The computer doesn't understand English nor the instructions we write. It needs a translator that can change what you wrote, to something the computer understands. That's the job of the **compiler**. The compiler has a dictionary and a rulebook to know how to change the code you wrote to machine code. Edit: grammar",
"This is just a basic explanation of it - but when the programming language was created, someone went through and basically mapped all the instructions to particular machine instructions that the machine understand. With Java, that is where the compiler comes in. The compiler is set up to go through your code and interpret in a way such as \"If = MachineInstructions\", and so on. A programming language doesn't read your language, someone created it to interpret what you write. Someone could just as easily make a programming language that works off special characters that aren't alphabet letters. The programming language itself is there to give you a sensible format/interface to interact with the machine code."
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7bswtz | Difference between mirrorless and DSLR | I have searched on reddit but most of the information seems a little complicated for someone like me who are not really used to the terms used in photography. I'm looking to get a basic camera in hopes to learn a little about photography and have gotten recommendation from the sales assistant to get a mirrorless camera. I was introduced to both D3400 and A5000 so I'm hoping someone can explain it in layman terms for me to further understand the difference between the both. | Technology | explainlikeimfive | {
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"A mirrorless camera projects onto the sensor at all times. A SLR style camera has a mirror that redirects the image through the lens to the viewer that you use to frame the shot. When you take a picture the mirror flips out of the way so that the image is projected onto the sensor, then it flips back up out of the way so the image can project onto the sensor. Mirrorless cameras tend to be smaller and less flexible on lenses choices, they also perform slightly worse in low light. SLR have more lense choices but are larger and have better overall performance ."
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7bz9um | . How are vinyls made and how does sound project off them? | Technology | explainlikeimfive | {
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"Sound waves are vibrations. Those vibrations are etched into tracks in the vinyl record. Then when you put a needle into that track and spin the record, the vibrations are transferred into the needle. Just amplify that needle with even a piece of printer paper rolled into a cone and you've got sound!",
"u/PM_ME_A_PLANE_TICKET is absolutely correct! I'd love to get a little more technical. \"How are vinyls made?\" - vinyl as a material (when compared to metals like steel, for example) is very soft. This allows it to be easily scratched by, for example, a very sharp and tiny needle (the recording needle). As u/PM_ME_A_PLANE_TICKET's explanation showed, sound waves are nothing more than just vibrations through a medium--usually air--so something that can respond to those vibrations in kind (like a diaphragm) can essentially \"pick up\" what the sound waves look like and translate them into another form. In our case, the diaphragm moves the recording needle in a reciprocal way (corresponding to the sound waves), and it thus etches the sound wave into the soft vinyl. \"How does sound project off them?\" - well, it doesn't really \"project\". In fact, it's a lot simpler than projection: it's actually the exact opposite of the process described above! In the same way that sound waves can cause a needle to vibrate and etch into a vinyl, a similar needle (the pickup) can \"read\" those etchings in the vinyl and cause a similar diaphragm to vibrate, which then moves the air molecules in the same way the original sound wave did, thus reproducing the sound! It's truly magic."
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7c1r0f | How do explosions trigger car alarms? | Technology | explainlikeimfive | {
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"Most car alarms detect movement on the car, like when someone tries to break in. If it is too sensitive, it can be set off by someone leaning on the side. An explosion sends out a massive shockwave, which shakes the car and sets off the alarm.",
"When an explosion occurs, regardless of the source, it creates a shockwave. In large explosions, say like a nuclear blast, shockwaves can level cities/infrastructure just as well as the actual blast itself. Shockwaves can also kill people caught in them if they're powerful enough. When a bomb goes off, lets say in a terror attack, the blast will do immediate damage (likely with fragmentation, being a terror attack and all) while the shockwave will cause massive infrastructure damage. Windows will be destroyed, barriers and fences too. The effect of the wave crashing over a car is what sets off the alarm, since it's enough force to physically rock the vehicle/impact the sensors that trigger the alarm."
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7c270i | Why do fire alarms ring in 3s? | You know, it rings 3 times, and then where it would ring the 4th time there's some silence and then it starts ringing again. Why do they do that? | Technology | explainlikeimfive | {
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"The Temporal-Three alarm signal (a.k.a T-3) pattern is a standard pattern used by alarm manufacturers. It is one of the alarm patterns that is designed to let people know what type of emergency there is. T-3 (three alarm sounds followed by one silent count) is the standard signal for \"Fire in the building\". There are other standard alarms as well. For example, T-4 (4 alarm sounds followed by one silent count) is the standard for Carbon Monoxide alarms.",
"* the alarms are coded, different rings mean different types of emergencies * it makes the alarm stand out more * it makes it clear this is, in fact, an alarm, not some other kind of noise"
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7c3w7w | How much info can a website glean from websites open in other browser tabs? | Technology | explainlikeimfive | {
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"Websites can't see what you're doing in other tabs, as that would be a major browser security issue. However, many websites contain Facebook \"Like\" buttons, or Facebook comments sections. If you're logged in to Facebook (even if you don't have a tab open to Facebook), the Facebook elements on those pages can see that you're logged in, and Facebook can keep track of what websites you visit.",
"Generally no. A browser code cannot access another window tab..... unless that window/tab is opened by this window/tab's code. That's not how Facebook gathers it's data. They gather data because other websites embed Facebook code for serving ads and someone pays them to do it. So when you go to URL_0 , that site tells your browser to go run code from Facebook that records your IP, device, browser, and other info and that you visited URL_1"
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7c6wre | Grid Computing as it applies to a business setting | So my understanding is that it's basically a network of computing devices, but how does this help businesses as far as data mining and data science goes? Specifically, what about grid computing is advantageous to business? | Technology | explainlikeimfive | {
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"Not many businesses use this technology. The idea is to take extremely large computation jobs, and spread them out across many computers in multiple locations. This way they can get done faster than by just using one roomful of computers. And otherwise idle computers can help out with the computation.",
"Grid computing is useful since it utilises idle computers to perform complex tasks, think of it like if you had 100 weak workers just sitting there but instead you go and find 1 very strong worker and pay him to finish the job, it would be a waste of money since you're already paying the 100 workers, instead you could just divide the complex task between the 100 weaker workers who would finish the job in the same time. So grid computing could save money and also would utilise the full potential of resources a company possesses."
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7c806a | Why is it damaging to battery life to charge up when it’s not completely run out? | Technology | explainlikeimfive | {
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"In modern batteries, that's not true. Older batteries technologies had that \"memory effect\" that forced you to discharge it completely before recharging, or you'll lose capacity. The cause of this effect is related to the chemical processes that take place inside the battery when it discharging and recharging, and are quite complex to ELI5..."
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7cc0wd | Why does 3G suck now? | Technology | explainlikeimfive | {
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"3G used to be the flagship signal, it had all the bandwidth dedicated to it and late 3G signal could hit early 4G speeds. These days its the fallback signal. If you're getting 3G it means that the tower is either too congested to serve everyone 4G and had to demote some people, or your signal is too weak to support 4G so it dropped you to 3G to give you a better Signal to Noise Ratio In either case, it means something is going wrong and you're not going to get the 10+ Mbps 3G of old and will instead be getting the 1 Mbps 3G of really old because this frees up capacity on the tower and is less sensitive to noise TLDR - Modern 3G sucks because you only get put on 3G when conditions suck",
"Since no one has explained this like any 5 year old could understand: Carriers (phone service providers like AT & T, VZ, etc.) have certain amounts of radio frequencies (think highways for cars ) that they can put all their phone users (drivers) on. They paid the FCC (or whichever national governing body) a ton of $$ for the highways. Billions. Some are wider and can fit more cars at once at faster speeds. Some are narrower and can still go fast, but with lest cars. Some go really long distances but slower speeds. Some really short distances lighting fast. You get the idea. The reason 3G sucks now is three fold. 1). Had all networks remained the same, phones today require more data (more cars) for the same perceived information (think 1080p streaming, sending 12+ MP pictures, higher screen resolutions). Previously, phones were lower quality and data was less intensive. So that in itself would lead to a slight slow-down (maybe 10-15%). 2). The introduction of LTE required a new way in which data is sent / received (think higher speed limits which require robot-like precision of lane-mergers) so the networks themselves had to add bulk on the backend to support LTE on top of 3G. This back-end complexity itself creates network congestion (again, another 5-10%). And now the big one combined with the previous two 3). Radio frequencies were reallocated (highways opened, and some shut down/moved). The carriers took old frequencies (10 lane super highways) that were dedicated to 3G and repurposed them for LTE, leaving 3G on the two lane country roads (metaphorically and physically, ironically). So when LTE super-highways are in gridlock and you have to bump down to 3G, it’s like a winding backroad that you’re stuck on. Yea you move...but at 40mph max and it’s a longer route. TL;DR: 3G used to be the super-highways of carriers’ networks, but that connection type has been shoved off in favor of LTE and now it’s like driving a country road. Even if no one is on it, you’re slow.",
"3G and 4G phones can handle more than one download stream for faster speed. Although LTE is faster than 3G, network carriers are allocating more network bandwidth and capacity to LTE. As LTE is allocated more bandwidth to service more 4G phones, that takes away 3G network capacity. So where you might have had two download streams on 3G five years ago, the network bandwidth for that extra download stream is now running on 4G LTE. Here's an article covering the disappearing 2G and reduction of 3G: URL_0",
"Most 3G towers were converted to LTE as most phones support the tech and everyone wants \"the fastest\" connection. The remaining 2G towers are converted to look like 3G service, but aren't so great. & nbsp; Simultaneously, cell phones use the internet more and more. Every program that requires communication with a server (which is most everything) eats your bandwidth. & nbsp; Furthermore, wireless devices have become more common. As such, the towers have to handle more connections, handoffs, signal collisions, and frequency issues. In areas with dense population clusters, it is easier to put up more cell sites. & nbsp; Finally, unless cell providers upgrade to true 4G (100Mbps throughput), they are perfectly fine will selling service and claiming that it is \"fastest in the nation\" or \"most reliable\" or \"largest coverage\". Most cell providers share each other's towers.",
"Another factor is that your phone is likely 1080p or higher thus pulling more bandwidth than your lower resolution 2012 phone likely did.",
"> 3G used to be the flagship signal, it had all the bandwidth dedicated to it and late 3G signal could hit early 4G speeds. > These days its the fallback signal. If you're getting 3G it means that the tower is either too congested to serve everyone 4G and had to demote some people, or your signal is too weak to support 4G so it dropped you to 3G to give you a better Signal to Noise Ratio > In either case, it means something is going wrong and you're not going to get the 10+ Mbps 3G of old and will instead be getting the 1 Mbps 3G of really old because this frees up capacity on the tower and is less sensitive to noise > TLDR - Modern 3G sucks because you only get put on 3G when conditions suck What /u/mmmmmmBacon12345 is saying is partially true, in theory. A large extent of it is that carriers have repurposed segments of their 3G spectrum to serve the 4G demand. 5G will be a little different, when it comes, because its frequencies are wildly different to support the insane amount of bandwidth it pushes. In the future, expect 5G to serve larger data needs, 4G to serve basic consumer needs [of course will probably be marketed under a different name, but same basic technology]. Source: former employee for two of the top three US based carriers. Sorry Sprint, you're 4.... 4ever",
"There’s only so much spectrum available in the 700, 800, 1900 and 2100 MHz bands that are common for phones. The carriers pay 10s of $Billions for more. They can devote it to 2g, 3g, 4g LTE. Adding more cell towers helps some, as they can reuse the same frequency slice three towers over. But there’s not enough to go around. They have turned down 2g and repurposed it, forcing people like my mom to replace really old handsets. They are now reallocating a lot of 3g to LTE so it can be used for data. Plan on 3g going away in a few years, and this will just provide better LTE, so it’s fine for anyone with a newer handset.",
"Think of it like TVs. 3 years ago, 1080p HD TVs were all you can find on shelves. Nowadays, 4K has taken over, and 1080ps are getting more rare. Why would companies produce more 1080p TVs when 4K is the new standard? The simple answer is that 3G coverage is reduced. In a competitive market, technology improves. Why maintain 3G coverage when 4G is the new standard?",
"I'll add one other tid bit as a former cell phone tower worker who was a part of 4G and LTE upgrades. Many of the upgrades we did adding LTE antennas, fiber, RRH's, etc. Also called for upgrading antennas on 3G and 2G however the companies didnt want to spend any more money on those old technologies. They constantly sent broken antennas, coax jumpers, etc. or the old coax connectors on the tower would be shot and they would not want to pay to fix any of it, therefore, adding the new antenna many of the times made those frequencies run far worse. It was bad. Edit: sp. Edit 2: Also: A lot of those RF engineers they hire are idiots. A lot of the times when they would have us change out antennas for old tech they would have us change their directions and downtilts for, \"optimization\" but I can't tell you how many of them were changed so they were shooting straight into the ground, a ridge or a giant empty nothingness instead of a populated area.",
"Ok, let me explain here. Radio spectrum is prime real estate for carriers, its real hard to acquire since everyone wants the best bandwidth. LTE propogate radio signals on 700MHz frequency becuase 850/1900 is taken by 3G. This puts carriers in tough position because they can't turn up LTE without taking 3G down on 850/1900. Since internet speed is becoming a norm faster and its getting real hard to keep 3G running beyond 10Mbps. With that said, 3G has become a neighbor where 4G borrows some sugar when it cannot handle capacity. 5G is coming, soon 4G will become that neighbor. source: capacity engineer",
"It's because operators are harvesting spectrum bandwidth from 3G and using it for 4G. In terms of Verizon's 3G, they use to have multiple channels of evdo so lot of bandwidth dedicated to 3G and not much data demand so whoever was using internet, they were getting decent speeds; currently Verizon only have 1 channel available for 3G in major cities as they are using rest of the spectrum for 4G, so now if you are dropping to 3G, you are competing with every one on 3g for resources on that 1 channel. Source: I am Verizon System Performance Engineer",
"I've read a few answers now and I'm thoroughly disappointed so here goes: One would assume 3G *means* 3G and that however fast 3G was, back in it's hayday, is THE 3G speed. That's not the case. 3G, 4G, and LTE all describe different standards for mobile telecommunications. When 3G was the latest and greatest, telecom companies **dedicated the majority of their bandwidth** to it. When the 4G standard came along and they adopted it, they started dedicating more bandwith to it and less to 3G. So if you think *geez I don't remember 3G ever being this slow* then you're not mistaken. It wasn't that slow. 3G describes a standard, not a speed. If all the telecom giants randomly decided to solely support 3G *now*, it would be a lot faster (but not as fast as the latest standard). Edit: if you don't know what bandwith is, it's basically the pipe that data flows through. More bandwith==bigger pipe. Telecom standards==rules for data flow.",
"Here in Germany with 1 bar of 3G/H I can do pretty much everything, watch YouTube, browse Facebook, Google. With LTE things just go faster and are better quality (YouTube)",
"3G was the fastest speed in the US in 2012, at least for wide use and adoption. Now 4G/LTE is the standard, and the signal it puts out drowns most 3G signals, besides which companies are slowly shutting down 3G as 4G matures more fully.",
"Back when 3g was a thing everything was only in like 480p for smartphones, so of course it'd be easier to stream Netflix or YouTube to it.",
"I have a theory that mobile carriers have just transitioned 4G to the 3G network, and 3G is now basically the old 2G / raw mobile data. In a few years they'll roll out 5G and it'll just be 4G rebranded.",
"As applications get more advanced they need better data connections. Back when 3g was the best it was good for the applications of the day, however it's maximum speed wasn't good for modern applications, so as things advanced 4g became the standard and the speed that 3g provided wasn't sufficient for good application performance.",
"Because 4G is actually the old 3G. 3G is just two dudes with microwave ovens shooting microwave rays into town.",
"QoS. 3G is now only being allocated certain amounts of minimum bandwidth so that the rest can go to 4G.",
"Cell tech here. I work on the network connecting towers. To be absolutely blunt, 3G is going to be unilaterally turned off within 5 years. 2G will stay put. The reason is because 3G is mediocre with data speeds in comparison to LTE and 2G is widely used by IOT. Its not worth it to keep an aging technology around that doesn't help us out much.",
"I work at one of the largest cellular tower operating companies. I can tell you it is mainly because 3G is being phased out, most of my new Verizon and AT & T builds have been 4G/4G LTE only. On a lot of the existing sites, they remove capacity on 3G to make room for 4G equipment. This results in lower coverage and capacity for 3G, and 4G traffic given priority.",
"Former network specialist for a telecom company here. I’m seeing some wrong answers on this thread. I️ don’t want to get too technical so will give a very simplified answer. - there are lots of caveats to the question, but,...to simplify the answer: there is less bandwidth allocated to former G networks now. Every time a new “G” network is rolled out, the old network loses resources. As hardware is upgraded to newer generation networks, the bandwidth allocation is moved to prioritize the new G network.",
"In the UK EE went around upgrading thier masts to 4g. This fucked the 3g signal for non 4g phones. At my olds house 4g on the new upgraded mast (nearby) has never worked and 3g is now appalling. We have gone from being able to phone in the house to making a call standing on the rock pile at the end of the garden to get a signal. EE said have a booster in your house but it will cost £100. And that's how you change to tesco (O2) asap. Thankful for good old landlines",
"One aspect that nobody has addressed yet is that \"bars\" are meaningless. Different models of phone & different carriers have different systems for how empirical signal strength in dBm translate to \"bars\". It's very possible that \"3 or 4 bars\" meant a MUCH stronger signal on your other phone than it means today. For a fair signal strength comparison you must go deep into settings (or install an app) that shows you dBm. I'm currently at \"2 bars\" at -115 dBm. This is in addition to all the other points people have made here which are also valid.",
"I'm posting this because I don't see it clearly articulated elsewhere here and I've dealt with your problem a lot here in New Zealand. It's a real problem in many rural areas that don't yet have 4G coverage. *Why is 3G network speed often worse than ever these days?:* The issue is usually **radio network congestion** caused by too many cellular devices being connected to the same cellular tower sector as you. By congestion, I mean too many cell phones, tablets, cars and other mobile devices that are connected to the same radio transceiver on the same tower as you're currently using when you notice the apparent slowness. In these cases of congestion, you'll find it especially bad around schools, large concert venues, or anywhere where large numbers of people (and devices) periodically congregate. You won't usually find this level of congestion in city centres though, as they normally have more tower sectors on each tower to handle more connected devices. The reason you notice the problem only when connected to the 3G network and not when connected to the 4G network is because the 3G radio frequency band is much smaller than the 4G one and if you slice up the 3G band into a tiny slice for each of the thousands of devices that are sharing your tower sector, they all get such a small slice that their data speed drops a lot and their lag increases. This happens with 4G too, but because the frequency band is so much bigger, even a small 4G frequency slice is still big enough to maintain a usable data connection for surfing the internet or most normal stuff people do with their mobile devices. The solution is for your service provider to install more 3G tower sectors to share the load, or to install 4G tower sectors so you can switch to the much bigger (and faster) 4G frequency band."
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7cc35d | How do “Self-Healing” products work? | So I recently stumbled upon a bag that could “heal” itself with the help of our own body heat. I also have heard about an LG phone with a similar tech that could heal dings and scratches on its back by simply rubbing the affected area. How is this process able to occur? Thanks | Technology | explainlikeimfive | {
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"These materials are usually made of very springy polymers (aka plastics, but I refrain from using that term outside of this aside, since it's not entirely accurate). The process of creating the object they're in, puts them in a \"desired state\". When you do work on the object, such as scratching it, or giving it a mild cut (on self healing cutting boards), the springyness of the polymers will cause them to return to the shape of the original object. Sort of like how we humans typically have desired state of being in bed, and go to great lengths to return there."
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7ccoj8 | How do thermostats work? | I recently replaced the batteries in my thermostat and you have to just remove the whole thing from the wall- it wasn't even connected to the wires in the wall.. so how does it communicate with those wires? How do the wires make the furnace or whatever turn on? If you have the thermostat set to say 21C, how does it know when to turn on the fans if the house goes below 21C? | Technology | explainlikeimfive | {
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"Traditionally, thermostats *were* connected to those wires in the wall. Those provided power & allowed the thermostat to send control signals to the furnace to turn on or off. They worked by various, fairly simple, mechanical methods to complete a circuit that turned on the furnace. Since yours *isn't* connected to the wires & takes batteries, it's probably just a remote control for your actual thermostat - probably using radio to communicate with a base station. It might have temperature sensors, it might not. There's no real way to tell without knowing more about how your home is set up.",
"Older thermostats used a [spiral shaped bimetallic strip connected to a mercury switch]( URL_0 ). Since different metals expand at different rates when heated, the bimetallic strip would make the spiral tighter or looser, tilting the switch and completing a circuit with the furnace to it would start up. Eventually the room would heat enough to make the strip curl the other way, breaking the circuit and making the furnace stop. You changed the temperature by rotating the whole mechanism so mercury switch would break the circuit at a different level of thermal expansion. Modern thermostats and furnaces are electronic. The thermostat has a computer than monitors the temperature, and sends on and off signals to the furnace, often wirelessly. Since they are more responsive, to prevent the furnace from cycling too often, they are typically programmed to bracket a temperature. You set it to 21 C, it turns on when it drops to 20.5 C, and back on when it reaches 21.5 C."
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7ccxrs | Why do phones sound so much worse when on speaker? | Technology | explainlikeimfive | {
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"The energy in a sound signal dies off pretty fast the farther away you get from it. This is fine for really small speakers that you put *very* close to your ears like headphones, earbuds, and telephone speakers. When you switch to \"speaker\" mode on a phone the speakers used are still very small and the power dies off pretty fast, unfortunately not all the frequencies die off at the same distance so the sound gets distorted."
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7cd3uq | if red, green, or blue lights allow for better "night vision" why are car headlights not made in green or blue to preserve night sight? | It makes sense not to use red but why not use green or blue tinted lights as headlights rather than what we use? | Technology | explainlikeimfive | {
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"To give a simpler explanation that fits ELI5 better (the others are good so far mind you) Things look different under different lights. We see \"white\" light all day, every day. If our headlights were red, blue, green or any other color really it makes it much harder to see and understand what you are looking at because we are not used to it and our eyes are trained to see things best under white lights. If you grew up using red/blue/green lights every day for everything maybe you could do that and it would be easy for you, but that does not work for the masses.",
"Because car lights aren't designed for the oncoming traffic, but for the driver of the car. What I wonder is why they haven't made some sort of divider that reflected / blocked the lights so the oncoming traffic didn't have to stare into the lights? Maybe something as simple as a slight polarity in the windshields so light from the left is slightly blocked? I dunno. .. something.",
"Red is better for night vision, blue and green would be terrible! Blue light is what you want to avoid when trying to see in low light. Having red headlights would enable you to see in the dark quicker after looking into them, but you wouldn't be able to see nearly as well with them. Under red illumination everything would look weird to you and you wouldn't be able to see a far distance effectively",
"It has to do with how different wavelengths of light react to their environment. For example, if you are an auto-sport fan, you might have noticed that many race cars use yellow fog lamps. This is because yellow light is much better at penetrating water vapor than white light, and therefore performs better in fog or rain. Yellow light also produces much less glare. Blue or red lights would have a very hard time cutting through mist or fog. Humans see much, much better in white light than in any other color. White light appears to our eyes to travel farther than colored light. If you've ever been in a situation in which red, blue, or green lights are used for vision, like night orienteering or a night flying aircraft, you will notice that it is much more difficult to see with colored light than with a normal flashlight. Colored lights would also change the color of the objects you are seeing, potentially causing some confusing situations. Most modern cars use a Xenon discharge lamp that tends to be towards the blue spectrum. These lamps are very carefully aligned so that they cause as little blinding as possible to other drivers. These lamps are great at illuminating a wide cone in front of the vehicle for a long distance. Colored lights would have to be very, very intense to achieve the same perceived effect."
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7cd8dj | Why caller ID allowed spoofing when it was first created? | Technology | explainlikeimfive | {
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"It was for law enforcement. It is pretty easy to figure out which numbers are coming from a law enforcement agency, so caller ID would make it harder for them certain things, like undercover work. Law enforcement pressured telecoms to allow spoofing because think of the children, so it became a thing. Since there are so many telecoms and wireless and VOIP services were rapidly evolving, the technology was not particularly robust, and telemarketers and collection agencies soon figured out how to do it. Nothing said it was specifically illegal, and you don't get a lot of campaign contributions for siding with consumers against corporations, so the current laws are weak. They and subsequent court rulings say spoofing is only illegal if there is an intent to defraud, which is certain to deter fraudsters from committing additional crime."
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7cdw4j | What is RAM and how much should I be using on a phone? | Technology | explainlikeimfive | {
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"**R**andom **A**ccess **M**emory. It's where you phone puts all the data it's currently working on. All the code to run the apps that are open is also in RAM. If you're watching a video, or listening to music, it's in RAM. As long as you aren't using more than 90% of your RAM, you should be fine.",
"RAM is Random Access Memory. It's faster than storage/hard drive space, but it's slower than the CPU cache. If you have 4GB or 8GB of RAM, you're probably more than fine. Think of your CPU as a car mechanic. He has a tool in his hand that can be used immediately. In a CPU we call it a *register*. The mechanic also has a few more tools in his pockets or on his belt. These are still pretty handy, but not as handy as the stuff literally in his hands. The toolbelt is the *cache*. The mechanic also has big toolboxes in the shop. That's like the *RAM*. It's still very accessible, and you'll go there all the time, but it's a lot slower than the toolbelt. Having a lot of RAM doesn't make the mechanic work faster. It just lets him have the space for all the tools he wants. Going to the *hard drive* for something is like ordering a part online. Compared to the tool on your toolbelt, the hard drive might as well be an hour's drive away."
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7ce93w | How does sequence and separation of files in the deletion process of the computer work? | The other day I deleted a folder on my computer by accident. After a short dumbfounded three seconds the deletion process was interrupted by pressing cancel. But the process had already deleted one file of the folder. So two things I wonder about: How does the computer decide what to delete first? what gives the computer the ability to delete one file but not touch everything else? | Technology | explainlikeimfive | {
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"> How does the computer decide what to delete first? Typically the delete command will assume that the sequence does not matter, so it just uses the most easily or quickly available one. Most likely, it will just call a routine to list the contents and delete them in that order, and that routine by default lists them simply in the order the filesystem returns them. Probably in the order in which they were added to the directory, but it really depends on the implementation details of the filesystem. > what gives the computer the ability to delete one file but not touch everything else? That's not an ability but a side-effect of the fact that it has to do something for each file, and can only do one (or a few) things at a time."
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7cevtw | Why does ad blocker still work? If a website can detect that ad blocker is active, why can't the site also just bypass the ad blocker and display ads? | Technology | explainlikeimfive | {
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"Because they use a separate company to provide ads, which come from different web servers. Imagine they're people. Dave works for the pizza company, he delivers your pizza. Sarah works for marketing company, she delivers the ads. Now, you could put a camera on your porch. Then you only open the door for Dave, but don't let Sarah in. Dave can see that you've got a camera, so knows that you're not letting Sarah in. But he doesn't have any ads to deliver along with the pizza. Sarah has the ads, Dave only has pizza. The best he can do is say \"Hey, you're not letting Sarah in so basically you're stealing this pizza. I'm only going to give you one slice at a time to make you think about this.\"",
"Many sites just show the ad without doing much else. Adblockers, however start once the page has finished loading, and does not request more information. Sure, the page could check if the ads were hidden/removed and place them again, but this would slow the page down, decreasing potential users, and adblockers would just repeat their thing. It could basically become an infinite loop",
"Adblocker runs in the user’s browser and the website does not have any control over it. Also, the ad exchanges have a standard code that allows to work in all websites while following a certain set of rules which is recognized by adblockers. It would be quite chaotic to have specific codes for specific sites and with time they would end up being blocked."
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7cfa0q | Why do images burn in to tv screens when you leave them there for too long? | Technology | explainlikeimfive | {
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"That used to be the case with CRT (cathod ray tube) displays on older TVs. Here each pixel was generated by beaming it onto the screen, and leaving the same image for too long would literally burn the screen. Nowadays with LED technologies this is no longer a problem."
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7cfbef | When cell phones first came out how did cell phone companies put up cell towers? | Technology | explainlikeimfive | {
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"You have to keep in mind that when cell phones were introduced, we already had very widespread networks (in the West) of broadcasting towers for radio and television. Wireless communication was not a new idea. Cellular service providers placed antennas on existing towers, leased land for new ones where necessary, and gradually increased coverage where it was most profitable. You need a license from the government for a broadcasting installation like that, as well as permission from local government. From an early stage, people came up with the idea of providing service via satellite, without having to build all those towers--but the ambitious schemes for global coverage never really materialized. There are a few satellite constellations now which provide pricey service that's not high quality, but it's very helpful in areas with no towers at all."
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7ch0p9 | Why do smartphones need sometime hours to fully charge. Electricity and electrons are so fast... | they should be able to charge it in a second. Whatever the capacity of the battery shouldn't it instant charge with all that powers from the socket? | Technology | explainlikeimfive | {
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"Electrons do not move at the speed of light, they are pretty slow actually. What propagates at the speed of light is the electric field that makes the electrons move. Every conductive material is pretty much filled with movable electrons, like a garden hose that’s already full of water. As soon as you turn on the water, it comes out the other end because there’s already water there that is pushed out and it doesn’t need to fill the hose first. gravity is similar: a gravitational field propagates at light speed but the mass it affects doesn’t. That’s why meteors don’t fall to earth at the speed of light, which would be disastrous. In rechargeable batteries, there’s also the charging itself which is a chemical reaction that takes some time as well.",
"* Batteries are charged through a chemical reaction. Those don't happen instantly, especially in the case of batteries. * The faster a battery is charged the more current it draws (electrons smashing into things inside the wires) and the more heat it creates. * Heat is bad for batteries and can cause cell phone batteries to catch fire or explode. So the charge rate is limited to what is safe for the battery.",
"You can't charge in a second for a few reasons. Ignoring efficiency losses, a typical 10 w-hr cell needs 10 watts for one hour to fully charge. A one second charge would need 36,000 watts (10x60x60) for one second. That would require a huge expensive power supply with very heavy cables and connectors. You can't force 10,000 amps through a tiny wire. The chemical reaction in the cell which is responsible for charging can't be rushed. To do so would generate too much heat. The cell would explode. The maximum allowable voltage of lithium ion cells limits the speed of charge. Li-ion chargers can charge faster at the beginning of the cycle. The speed tapers off towards the end. Some battery chemistries like lead-acid or ni-cd allow for higher voltage fast charging for the entire cycle. Edit: Lead acid and ni-cd batteries still have charge speed limits."
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7chi2a | Why do Home dishwashers need to take 3 hours? I know it’s for energy star requirements, but commercial machines get the job done in 90 seconds. Why the massive difference? Wouldn’t even a more powerful motor take less electricity for such a big time difference? | Technology | explainlikeimfive | {
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"The dish machines in kitchens are SUPPOSED to be sanitizers, not dish washers. The poor sucker getting paid barely enough money to survive is the dishwasher. All the machine is for is removing whatever small bits are left over after the dishwasher has already mostly cleaned them off. Long story short: If you want clean dishes quickly, you're gonna have to get your hands dirty. Source: Am Chef",
"also, it's important to note commercial restaurant washers don't have to deal with stuck-on, dried food. The plate comes back from the table, gets pre-scrapped, then rinsed with a high-pressure manual spray, with hot water. The plate is essentially clean now, save for a few random bits. Food never had a chance to dry, thus it is very easy to wash quickly. Silverware soaks in hot water up until the dishwasher has enough to do a full load, so they don't dry out either. The same plate might serve ten people in one weekend dinner service, it comes down to just how FAST plates move through a busy restaurant. Homes don't work like this. People let food dry out on the counter, or in the machine itself waiting on a full load. A longer cycle is necessary to re-hydrate the stuck-on food before it can be carried away. Take an average load of dried dishes from home, I guarantee most of them would not come out clean in a commercial dishwasher, and would require many, many cycles. The restaurant machine exists only to finish plates that are basically 99% clean already. The detergent just takes away remaining oil/butter, and the rinse cycle gets the plates to a high enough temperature to sanitize, with the help of a little bleach. Rinse aide makes them dry quickly. Within ten minutes it's heading back to a table. An average \"round trip\" is under an hour. Any plates or equipment with real stuck-on bits must be manually scrubbed. It's comparing apples to oranges.",
"Oh, finally... My time to shine! I didn't read through all the comments so others may have mentioned all of this already. I work for a major appliance manufacturer and this comes up quite often. One main reason is the fact that they are using so much less water - we're talking just a few gallons. That water is run through the wash arms at different times, so not all of the dishes are being sprayed and cleaned at once. Another reason is due to the sensors inside that tell the dishwasher how dirty the water is. So many people think they are supposed to essentially wash the dishes before putting them in the dishwasher - STOP THIS! It needs to sense the food/drink particles in order to clean properly. And as mentioned in other comments, heated dry. While it adds to the time, heated dry, along with rinse aid, is essential to getting your dishes (and the inside tub) dry. If you don't do these things and your dishes aren't dry, don't call the manufacturer. Read the manual that gives with it. Any other fancy options you may add on, say sanitize, are going to add to the time as well. Mind you all of this applies to the brands I work with, but I'm sure there is some crossover to others as well. Edit: my first ever gold! Thanks, my fellow Redditor! I'm so glad this random knowledge has finally paid off.",
"Commercial dishwashers take 45 mins to heat up when you turn them on, then keep the water hot all day, which saves a massive amount of time in the wash cycle but uses a lot of power. domestic dishwashers heat the water every time.",
"More complex chemicals, which are surprisingly expensive. Significantly higher temperatures and pressures. Higher voltage. They basically turn your dishtank into a loud sauna too, you probably wouldn't want your kitchen like that.",
"They run on very hot water, use dangerous chemicals, and are far too forceful for normal dishes. That's part of why restaurant dishes and mugs are so thick.",
"The commercial dishwasher has a tank with pre-heated water, i.e. in the very moment you close the cover, a wet hot hell with chemicals goes down on the dishes, and everything is done when your dishwasher at home is still thinking how much water to take in and heat.",
"Additional Eli5: why does my household dishwasher from '05 take 88 minutes per load and my girlfriend's 2017 washer take 180 minutes?",
"Along with everything else is dry time. Commercial dishwashers you a drying chemical and air drip dry. Your dishwasher turns into an oven and baked the moisture away. It needs to do this because your not there to open the door and create air flow as soon as it finishes. If you didn't open your dishwasher for a day or two those dishes would not be clean any more, mold would have started to form",
"You hit it on the head. Residential dishwashers are bound by EPA regulations. Lower water/electric consumption. Commercial dishwashers do not follow these. Sinners circle explains how proper balance of chemicals, mechanical power, time and temperature need to be balanced for cleaning. URL_0 If you reduce temperature/mechanical power (to save energy) you must increase time to balance sinners circle. This is where commercial dishwashers can clean in 15 minutes or less. Extremely high water temperature and pressure = low time.",
"Residential dishwashers don't need to take 3 hrs, as many have \"quick\" or 1hr cycles. But if you want to use less water(and electricity to meet Energuide or energy star guidelines) a residential dishwasher will utilize sensors to measure the turbididy of the water(which can eat up a portion of the cycle time and uses a fraction of a penny for each use and some dishwashers will reactivate the sensor portion up to 3 times per load at anywhere from 5-10 mins approx per sense). The filling process will also take time and others have pointed out that heating water through an element will also add time(if you have a 'high heat' option it will add more time as to heat the water up even further, in most cases surpassing what your hot water tank heats to). Then filtering the water. Most \"newer\" dishwashers can filter and reuse up to 75% of the water, some like KitchenAid, in some models, after filtering and reusing water only use about 2.25 gal per load(compared to the average 5-7 gal per load of most other models).The filtering process can also eat up some of the overall cycle time. Also drying. Condensation drying, which is used by most brands can take a long time. Having heated dry option uses more electricity but has a shorter run time(and \"newer\" options like adding fan assisted heated dry help reduce overall times as well). Also unlike commercial applications where you can have a person target a powerful sprayer at baked on foods, at home the machine will operate the bottom sprayer for a time then utilize the middle and top sprayer and cycle back and forth(some machines like Maytag use all the arms at once as the motors on those machines are more powerful but won't reduce cycle times by doing this) hoping to get all the food off(as some have mentioned the need to \"rehydrate\" soils to help get them off is factored in the programming/cycle choices which also plays a part in the overall timing). Source: I work for an appliance manufacturer and spend time with the engineers who build/design/program them. TL; DR: residential dishwashers don't need to take so long but to enjoy resource efficiency(and get dishes clean without you assisting them)they need to do stuff that adds more time. Edit: formatting",
"You do not have the pressure and the temperatures that a commercial system has. Those things are monsters and the water is at boiling temperature. Here is a video. URL_0",
"Temperature, chemicals and manual labor is the difference. For the commercial dishwashers: You need to scrub debris off the items you want to wash as much as you can (someone said something about sanitizing plates... this is what is happening.. just at a faster rate of speed due to the temperature and chemicals) Temperature: wash temperature is about 160F(very hot) in most commercial dishwashers. Home dishwashers could get there but only if your water heater is up to it... most water heaters at home do not have a booster heater like the commercial dishwashers (they are powerful) and they are installed in the machine IN the water tank. The rinse cycle comes right about the end of the trip and the temperature of the water gets to about 180-190F(Extremely hot1!)... the chemical evaporates over 200 degrees and it is worthless then. Most newer machines have a computer that monitors the temperature and keep it at that level. they also let you know when the chemicals are low or at zero level. Chemicals: soap is present at wash cycle. most machines have nozzles that spray the plates/hardware you are washing. All this is pressurized but it wont take all the heavy debris (hence the manual step) then the rinse chemical allows for a faster drying time. Usually all the items that go thru the cycle come out clean, sanitized and dry after the cycle(about 2 min tops). Rinse chemicals allows for a faster dry time. The home dishwasher does not have the chemicals, temperature of the commercial machine. Which translates in longer time to clean the dishes. So, the difference is the temperature and the chemicals. If restaurants do not follow these procedures or skip part of it... they will go the way of the Dodo. Washing dishes one of the most important part of the restaurant business. Source: I have been in the restaurant business for about 30 years. I started as a dishwasher. Yes, I still help wash dishes and check they are being washed properly. Clean plates saves the business. I check daily that my machine has proper temperatures, chemicals and the water gets changed at least every two hours(that also affects how clean the plates come out)",
"Since no one seems to answer the obvious answer, I'll say it. Commercial dishwasher **are not** energy efficient. You can either have quiet and energy efficient, or loud and quick. Commercial dishwashers take the latter and residential dishwashers take the former.",
"When I was younger and worked in commercial kitchens the dishwasher wasn't s washer at all. It was just a hood you pulled down that sprayed boiling hot water and rinse aid on the contents to sanitize the dishes and make them sparkle!",
"Professional dishwashers only have to remove \"fresh\" remains that are still moist and relatively easy to wash off. They use pretty aggressive detergents that should only be handled by professionals. They are great for greasy stuff but are not that great washing off starch and proteins (eggs in particular). Your dishwasher at home on the other hand may have to wash of dried stuff from two days ago and uses milder detergents that are safe for home use. Also, they have different components that are good at decomposing starch and proteins that may take a little longer to be effective. A good part of the home dishwasher cycle is soaking/rinsing. Most modern dishwashers have a quick cycle that skips this step mostly and only takes about 30 minutes and it's useful if you have to wash a full load right after a meal. The professional dishwasher skips it completely and just goes at it with high water pressure and agressive detergent.",
"Did dishes in a big old age home when I was a teenager. The dishwashers operate at such high temps that even if you end up with something left on the dish, it's sterile. Recently helped at a soup kitchen.... naturally, with my experience from many years ago I helped with the dishes. They had a small unit that washed the dishes after initial hand rinse and it worked really well. Guy who did it all the time said he wished he had that unit at home. But I imagine it would be quite expensive. Plus it was designed for a single rack of dishes at one time. Home units are designed with practicality in mind. You load it up over a few hours then run it. Not very convenient if you have to fill a single rack then run it, then dry your stuff by hand. The old Hobart unit we used at the old ago home was a beast. Dishes came out so hot you'd practically burn your hands when taking them out of the racks. Everybody slags dishwashing as a job but I didn't mind it. We had union pay and it was OK. Certainly had a lot worse jobs that that when I was young. Washing dishes we just worked fast and you're like on an assembly line. It's mindless work but you still have to do it right and you have to do it fast. Besides, most work becomes brain stem function after a while. People just don't like to admit this about their work so they say things like, \"Yeah, every day is different\". Honestly....if every day was so different you wouldn't be happy because you wouldn't become any good at your job."
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7cjs9i | Why do some cell phones have area codes different from the geographical area in which they were purchased? | For example, I live in a suburb of Minneapolis where the area code is 952. But my cell phone's area code is 612 - the area code for Minneapolis city proper - even though I purchased it in the suburbs where the area code is 952. | Technology | explainlikeimfive | {
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"Phone carriers are assigned numbers in blocks. For example Verizon with have 612-512-0001 through 612-512-9999 to assign to accounts and AT & T will have a different set of numbers. In major metro areas there are often multiple area codes simply because one got used up. It's not really downtown v. the burbs but that's how it pans out for practical reasons. All the established numbers are on the old area code and downtown. All the new numbers area from newer areas."
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7cjwo7 | Why is it that batteries don't go dead when you connect their ends with wire? | I'm trying to understand Ohm's law and resistance behind circuits. If you take a battery and connect its two ends using a copper wire without any resistance (like a light bulb), your resistance is around zero. Because the voltage is constant, your current going through the wire seems to be absurdly high, which would result in a massive flow of electrons from one end of the battery to the other. So what prevents batteries from going dead if you do this? Because I'm still pretty new to circuits, please forgive me if my question wasn't clear enough. Edit: Also, is "technology" the right flair? I'm still kind of new to this sub. | Technology | explainlikeimfive | {
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"The point is, resistance isn't around zero. A battery might have 2500mAh capacity at 1.5V. The battery itself has a resistance of about 0.2 ohms. A wire connecting both terminals might have about 0.002 ohms. According to Ohm's law, this setup will draw around 7.5 amps, or 7500mA. A 2500mAh battery can deliver 2500mA for one hour, or 7500mA for 1/3 of an hour. So, if the circuit doesn't catch fire or melt it will manage to deliver this current for about 20minutes before it runs dead.",
"Nothing. The battery will go dead. Rather quickly. Not instantaneously, though, because, as you said, the voltage can only go so high. More likely, though, your battery is going to overheat and, if it's a LiPO, probably explode. So it won't have time to empty completely. But yeah, if that didn't happen it would go dead."
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7ck0ea | Why are apartment buildings still using call boxes that look like they were made in the 80s? | Technology | explainlikeimfive | {
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"dpqhg43"
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"text": [
"Because they don't want to spend money to replace them with something newer? If it still \"works\" then why spend a few grand getting a new system?"
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7ckom4 | How come multiple wireless providers can all claim they have the best speeds? Isn’t wireless connectivity and accessibility something that can be objectively measured and ranked? | Technology | explainlikeimfive | {
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"They use different metrics to determine what is \"best\", because \"best\" is a subjective term in marketing. They could be referring to \"the best wireless speed compared to two other local service providers that haven't upgraded their equipment in twenty years\", or \"the best wireless speed available in Sedona, Arizona.\" You have to read the fine print to determine what their metric is. When it's all big-brand companies, they often use metrics gathered from different sources. For example, Verizon might use URL_0 to determine \"best speed\", but they also might throttle their speeds outside of the URL_0 domain; whereas Comcast might use average speed for the top 10 most popular websites.",
"Technically, not to get afoul of the FCC, all they need is to be the best in one small area to be able to make the claim. So, if they are the fastest wireless provider in Podunk, USA where they are the only one, then they can make the claim. It is the same as all the truck companies saying they are #1 selling truck in the US. It is all in the fine print, which no one likes to read.",
"You would think that but not really since there are a lot of metrics out there as to what they mean. Those claims are very broad and can refer to any number of metrics. Not to mention that advertising has a lot of wiggle room for things like puffery.",
"Speeds vary based on location and congestion so where, when, and how it is measured makes a big difference. They only need one test basically to point at to show they are fastest. One method providers will use is they will perform their tests immediate after launching an upgrade to their system... but before most of their userbase gets the update to actually utilize it. That way, they can get \"optimal\" speeds that are crazy fast, but once a million people are using it, it slows down a lot.",
"Let's say three cars are being tested to see which one is the fastest by their manufacturers. Manufacturer A tests all 3 cars and uses the speed displayed on the speedometer, this result lets them say their car is the fastest. Manufacturer B tests all 3 cars and uses GPS data to compute the speed, this result can let them say their car is the fastest. Manufacturer C tests all 3 cars and uses a speed-trap setup to compute the speed, this result can let them say their car is the fastest. By choosing the way they collect data, or the location they collect data, companies can manipulate the results of a 'see who's fastest' test to ensure they win."
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7cnrc3 | The difference between the Thor: Ragnarok light technology and conventional slow-mo technology | Technology | explainlikeimfive | {
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"[Watch this]( URL_0 ) Several things are happening to achieve the look from Thor Ragnarok. 1) The camera is shooting at an extremely high FPS. Thus giving you slow motion. 2) The lights and the camera are also moving extremely fast. 3) The result is a visual effect that makes the slow motion footage look slow AND normal speed at the same time. The subject is slow but the camera motion and light movement is fast.",
"Conventional slo-mo takes many frames per second and plays them back at normal speed. This makes things see to move more slowly. Strobe-tach, and related technology, are very different. If you have multiple flashes per frame, you get multiple images, but regardless you get no motion blur because the light is only on for a tiny bit of time. If you shoot a moving thing at 24 FPS, traditional movie speed, you get motion blur of approximately 1/24^th of a second. If you shoot that same motion at 240 FPS and play it back at normal speed everything is slowed down and you get 1/240^th of a second motion blur. If you shoot the same motion at 24 FPS under a 240 Hz strobe, you get 10 unblurred images per frame and no slow down. If you shoot at 240 FPS under a 1200Hz strobe you get five clear images per frame and those five overlapped images move slowly. It looks a lot different because your eye integrates the multiple images differently than it handles motion blue.",
"The way I understand it, the lighting, in this rig, moves very quickly across the subject so that when you slow down the action, the light looks like it's moving normal speed (giving you the impression you're viewing the scene in real time) but the actors are moving in super slow-motion. The effect gives it a surreal, dreamlike quality.",
"The title is a bit misleading I think. If I understand this correctly it's conventional slow-mo from the cameras perspective except that you add an array of appropriately synchronized strobes. This way you can \"move\" the light source by a significant amount even during super fast slow-mo since you don't actually try to move a physical light source at absurd speeds but you fire strobes along the path in sequence. Similar things were done for cameras in the matrix movies IIRC. Essentially they set up a ton of photo cameras along a camera path and then triggered them all at the same time. That way you can move along the path of the setup cameras while the action remains frozen."
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7co6e0 | How are IP addresses allocated when using mobile data such as 3G/4G? | Technology | explainlikeimfive | {
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"text": [
"Same way, it's still a network of routers and switches. Think of the cell towers and 4g antennae as the wireless access point. Your pc and cell phone access the same isp infrastructure after a certain point.",
"Still DHCP servers as with any other ISP. The cellular nature of the network doesn't change the principles involved. Note that the backbone networks in telecom companies aren't always the same as the routed IP networks in companies. Things are changing, but many still use a different, connection-based packet switching technology called ATM. ELI5 version: in this setup, each cellphone tower isn't a router or DHCP server itself, but instead \"tunnels\" all its traffic straight to a more central location to be separated and handled appropriately. Addresses are allocated at that point. Switching between towers doesn't trigger a new DHCP address process every time."
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7cop0f | What is actually happening when a car is done "warming up"? | I mean besides the literal "the engine is now warm." After I've started my vehicle, I notice the RPMs slowly dial back. Say, from 1200 to 900, over the course of about 3-5 minutes. What is actually occurring that causes the RPMs to start at a higher value, then go to a lower one while the car idles? | Technology | explainlikeimfive | {
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"text": [
"In a modern car it's down to the engine computer making the engine run at a higher idle to increase the speed things warm up at. One of the big ones is the catalyst in the catalytic converter. This is basically a bunch of exotic elements in the catalytic converter that need to be warm before they properly do their job of reducing the emissions from the engine. As well as that when the engine is stone cold, fuel doesn't want to vaporise as easily, and it's the vapour that burns, not the liquid. So basically to get up to efficient running the engine has to be warm, so the computer makes it rev a little to get it there faster. Other points are getting oil warmed up so it flows properly around the engine. All in all there are several pretty good reasons for the engine warming up, but in a modern car, it's literally the computer monitoring temperatures, and making the engine rev a little bit more till those temperatures are reached.",
"I would add that there is no need to warm up modern engines. Most processes are controlled by a computer. You just supposed to start moving without high load first 5-10 minutes."
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7copag | How is mains AC turned into usable DC power, particularly in the context of a desktop computer PSU? | Technology | explainlikeimfive | {
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"text": [
"AC is converted to DC using a rectifier. Diodes (which restrict current flow in one direction) are used in a bridge circuit so that each half of the AC waveform is output at the same polarity, and then capacitors are used to eliminate the ripple and smooth the DC output. To drop voltage, a transformer may be used on the input AC, or a DC-DC converter (inverter / rectifier) may be used on the output side.",
"Here's a [circuit diagram of a rectifier]( URL_0 ). On the left is where the AC is coming in (assuming it's already been stepped down from mains voltage). AC current reverses direction several times a second: as a waveform, it has the appearance of a sine wave. Then we come to the actual bridge rectifier, consisting of four diodes, represented by the arrowheads, labelled D1 to D4. A diode will only let current pass in one direction, as signified by the arrowhead. Imagine the AC current flowing into the circuit\\* along the wire to the junction between D1 and D4 (the connection at the top of the bridge). It can't flow through D4, because it's pointing the wrong way, so it flows instead through D1. This takes it to the + terminal, where it meets D3, which it can't flow through. Its only exit is to follow the arrows around the circuit (\"load\" means \"whatever thing you're providing power to\") and back to the - terminal. There it flows through D2 and back to finally complete the circuit. When the AC current reverses direction, it enters the bridge at the bottom. From here, it can only flow through D3 to the + terminal, where it follows the arrows around the circuit and back to the - terminal: there it flows through D4 and out. So whichever way the AC current is flowing, it can only flow through the DC part in one direction. The resulting waveform is seen below: it's the pink line. Now, instead of reversing direction several times a second, the current flows in one direction, but in pulses. This is where the capacitor, marked C on the circuit diagram, comes into play. A capacitor is an interesting component: it charges up with electricity, and then releases that electricity again. So when a pulse of current comes, some of it is diverted to the capacitor and charges it up; when the pulse has passed, the capacitor discharges and dumps the electricity it has collected back into the circuit. This smooths out the pulses: it's not perfect (there's still a ripple), but usually good enough. -------- \\* Note: I'm talking about the current here, which flows from positive to negative. However, the actual electrons themselves are negatively charged, so they flow in the opposite direction. I'm talking about the *current*, not the electrons. The reason for this is that the positive and negative poles were so named before the nature of electrons was understood: at the time, scientists had a 50/50 chance of getting it right, and they picked the wrong option.",
"It's a combination of a half- or full-wave [rectifier]( URL_0 ) with a capacitor at the output to flatten and stabilize the voltage. At the core, it's really just one or more diodes which only lets current flow one way, thereby turning off or inverting the negative side of the waveform which moves the average positive (and thus the DC equivalent voltage)."
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7cox7v | why is EA games facing so much backlash from Redditors? | Technology | explainlikeimfive | {
"a_id": [
"dpri2az",
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"text": [
"Most recently it is because of their release of Star Wars Battlefront 2. It takes 40 hours of playing to unlock darth vader, or you could just buy him... Microtransactions have always faced a lot of criticism, as well as dlc that should have been included in the main game. Basically EA always rushes their games, released the unfinished bits as dlc, and charges microtransactions (not to mention their insistance on using EA origin). They are just a bit to blatantly cash grabby as a company. Which is a shame considering their roots. Here is their recent comment that got 371k downvotes: URL_0",
"Basically EA is like the video game equivalent of Comcast in terms of greedy, malevolent business decisions and contempt for consumers. One of their most hated practices is buying respected studios, running them into the ground, and closing them l when there's nothing left but a empty shell with a tarnished name. The latest act to draw ire however is the upcoming title *Star Wars Battlefront II* giving those who buy in-game items with real money a competitive advantage in a game that already costs $60 at the very least."
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"https://www.reddit.com/r/StarWarsBattlefront/comments/7cff0b/seriously_i_paid_80_to_have_vader_locked/dppum98/?st=j9y91vfu&sh=16f42e2a"
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7coxo6 | How would charging a charger work? | If I were to take a 5000mah battery pack (like the ones used to charge cell phones) and use it to charge another 5000mah battery pack, could i do so indefinitely, or would there be a constant loss in the transfer? | Technology | explainlikeimfive | {
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"text": [
"There would be losses. As the pack charges up, it also heats up. That heat eventually dissipates out into the air around it and is essentially lost. That heat comes from the energy stored in the other pack so if you constantly charged one pack with the other and then swapped and charged the other pack, eventually all the energy would be converted to heat and then lost.",
"Both parts of the cycle (converting cell voltage to USB voltage, and vice versa) have an efficiency far less than 100%, not including minor loses such as resistance in the cables/connectors/cells/etc. If such a cycle were let to run, both batteries would eventually end up discharged."
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7cpeko | How does carbon dating work? | Technology | explainlikeimfive | {
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"text": [
"In the high atmopshere, cosmic rays strike Nitrogen, turning it into Carbon-14 (Carbon with 6 protons and 8 neutrons). Carbon-14 is unstable and will eventually decay into Carbon-12 (6 protons and 6 neutrons). The rate of Carbon-14 generation and decay is somewhat constant, and there is a roughly static ratio of Carbon-14 and Carbon-12 in the atmosphere. Carbon-14 and Carbon-12 readily combine with oxygen to form Carbon Dioxide, which is absorbed by plants and then eaten by animals. So long as an organism is living, it will constantly be taking in Carbon that originated from the atmosphere, and ratio of Carbon-14 to Carbon-12 in the organism's body will mirror that of the atmosphere. When the organism dies, it no longer takes in new sources of Carbon. The Carbon-14 present in the organism's body will continue to decay into Carbon-12, but no new Carbon-14 will be generated. This will alter the ratio of Carbon-14 and Carbon-12 in the organism's body (until there is no Carbon-14 left). Since we know the rate at which Carbon-14 decays into Carbon-12, we can analyze the remains of an organism, determine the ratio of Carbon-14 and Carbon-12, then calculate approximately how much time would had to have passed to reach that ratio. Carbon dating is only good for dating things less than 50,000 years old."
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7cpu8a | What are the pros and cons of organic farming versus conventional farming? Which one is better? | Technology | explainlikeimfive | {
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"text": [
"The main advantage of organic farming is that you can put the organic label on the stuff you sell and charge more for it. The disadvantages include smaller yields, greater chance of disease, greater use of pesticides, and greater environmental impact.",
"Conventional farming produces much higher yields at the expense of using artificial chemicals as fertilizers and insecticides. Organic farming eschews artificial chemicals at the expense of lower yields. Neither is inherently better until you make value judgements about the use/presence of chemicals, how much you trust that those chemicals are safe, what goes into producing those chemicals, etc.",
"Which is better is up for debate. Some of it comes from people's trust, or lack of trust, in companies like Monsanto. Which is an entirely different discussion. The claim is that organic farming is better for the consumer, better for the environment, and better for the worker. There's strong evidence this isn't always the case. Organic pesticides can be far worse than their counterparts. Some organic pesticides are more toxic by weight than round up and the like. People like to believe organic means healthy and safe because it's something that is a byproduct of a living organism or system. Which is not something that holds true."
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7cqfhq | How does an air fryer work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"it's like an oven, but with the air circulating much faster and sometimes uses hotter air than what ovens are capable of. the crispness comes from fast circulation of air.",
"Many people are saying that an air fryer is just a convection oven, but try telling a pizza maker his wood-fired brick stove is \"just a convection oven\". There's many things in the design that make it better for some uses and worse for others. First up, how it works. Like a regular oven, it works by heating up air, and then using the hot air as a fluid to transfer heat to the food. It has built-in fans to circulate the hot air so that the food is cooked faster and more evenly, just like a regular convection oven. What are the upsides of having one over a regular convection oven? It's smaller and generally a better fit, portion size-wise. This means you don't have to heat up your oven just to fry something, along with the energy usage, and you can use your oven for something else as well. By that same token it's easier to clean at the end of things. It's designed to be taken apart and cleaned too. It has a built-in rack and drip tray, most have handles, and many have stirring bits built-in as well. They're *much* more convenient than sticking something in a convection oven- you don't need to worry about catching the oil drips while keeping whatever you're frying on a rack so that the air circulates evenly, & c. I've used my mom's, and it's incredibly convenient. Quick to start up, fire and forget, easy to clean. That's what you're paying for- not the technology, not the concept. Convenience. If you have access to one, try it out to see how much time you save, and make your decision yourself."
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7csdpi | How do Apps track your sleeping? | Technology | explainlikeimfive | {
"a_id": [
"dpsaii4"
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"text": [
"If it's an app, mostly motion detection, with perhaps some sound detection! If it's a smartwatch, most likely pulse (it changes with your sleep and the stages within it) and motion detection!"
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"score": [
5
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7csol7 | how do we capture helium and put it into tanks? | This probably seems like a very basic question but how was it discovered and how is it harnessed for everyday use? Wouldn't it just float away? [other] | Technology | explainlikeimfive | {
"a_id": [
"dpsdyt8"
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"text": [
"Helium is extracted from natural gas, kind of like how gasoline is extracted from petroleum (oil). It won't float away because it is PART of the natural gas. Since it is extracted in a controlled environment it can be separated from other products, like butane (think cigarette lighters) and propane (think gas BBQ grills). Each product is removed at a particular fracking stage and stored into separate tanks. this is an oversimplified explanation...but this is ELI5. You can google fractional distillation or wiki it for the science(y) details of how the process works."
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7cv2an | Why do sites like PirateBay and WatchSeries constantly change domains? | Technology | explainlikeimfive | {
"a_id": [
"dpsvpot"
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"text": [
"They are being actively hunted by various anti-piracy organisation s. To counteract getting the domain banned/vlocked by providers, they change it, thus being able to continue operations."
],
"score": [
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7cxs23 | Why are some large batteries (like Tesla's) made up of smaller cells? | Laptop batteries, electric car batteries, bike batteries, etc. all seem to be made up with a bunch of 18650 standard cells. Why? It seems inefficient given that the shell of the battery takes up space, and since it's cylindrical, means you have wasted space within the battery pack. | Technology | explainlikeimfive | {
"a_id": [
"dptn97v"
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"text": [
"Because electrically, one huge single cell battery would be extremely inefficient. Spreading the load over multiple cells is how we make batteries work for more cycles, especially longer cycles that electric cars need. If we used a giant single cell battery in something like a car, it would run very hot, be enormously heavy, probably have a range of 10 miles, and the battery would probably need to be replaced after 100 cycles. Electric vehicles demand a specific, high voltage, with the longest deep cycle possible. Multiple small batteries is the safest and most efficient way we can do that with the technology we have. 18650s currently are the cheapest and most reliable way we can do that on a mass scale. tl;dr it's much more efficient to run multiple cells in series than less batteries in parallel (or one single cell)."
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7cycgr | What is the difference between Anti-Malware and Anti-Virus? | I have heard of both Anti-Malware and Anti-Virus and didn't actually understand the difference. I have had some more tech savvy friends suggest either of them based on any issue I face. What actually is the difference between them and which provides the most comprehensive protection and which one is most important to have to protect our personal computers and PDAs? | Technology | explainlikeimfive | {
"a_id": [
"dptljoe"
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"text": [
"Branding, mostly. Technically speaking, malware is an umbrella term for all sorts of malicious software. Viruses are a type of malware - specifically, a virus is a piece of code that copies itself into a file so that when you open the file, the virus's code is executed (which can do malicious things, as well as inject itself to other files on your computer). Today, \"virus\" is often used to describe other kinds of malware such as worms and trojan horses, despite the term being inaccurrate, and \"anti-virus software\" protects against various types of malware, not just viruses, but the name stuck. \"Anti-malware\" is actually the more accurate term."
],
"score": [
8
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7czwek | Why is Bing so much worse than Google? | Technology | explainlikeimfive | {
"a_id": [
"dptygca",
"dpu1iby",
"dptxn7k"
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"text": [
"a) google knows you better, has collected much more information about you and can therefore tailor search results to you b) google has much more users, allowing it to make more precise judgements about which results might be relevant for your query using historical query and click-through data",
"For the most part, it isn't. Several studies have been conducted that do blind comparisons of Google's vs Bing's results. Some favor Bing, some favor Google, but it's always competitive. Bing does not \"consistently\" display less useful results anywhere other than your pro-Google mind.",
"Google has been around much longer, and has been improving their algorithms the whole time."
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7d0pkm | How are you able to hear where footsteps or gunfire are coming from in videgames? | Technology | explainlikeimfive | {
"a_id": [
"dpu4oz7",
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"text": [
"Your brain is really, really, good at figuring out where a sound is coming from, based off of the difference in how each ear hears the sound. Video games use this to make the sound louder or softer in each ear to trick your brain into thinking it comes from a specific direction. There's a limitation to this. Here's an experiment to try. Put on a blindfold, and have a friend use something to make a sound around your head. Tapping two things like spoons together works. You'll be able to tell if it's to your left or right easily, but if they make the sound right in front or behind you, you won't be able to tell. The sound is equally distant from each of your ears, so your brain has to use your sight to help. We use a combination of sight and sound to figure out where a sound is coming from, and video games give us both.",
"> How are you able to hear where footsteps or gunfire are coming from in videgames? There are a variety of ways in which we can locate sounds. Most obviously is volume; if the sound is louder in your right ear than your left it indicates the source of the sound is somewhere to the right of your head. Another major way to determine the location is a very slight delay in when the sound is heard between the ears. Sound travels through the air at a finite speed so it won't arrive at each ear at exactly the same time. Our brains can actually detect the slight delay between our ears and provide a direction based on that. Both of those factors can be reproduced through headphones by a computer. A third way we can locate sounds is due to the shape of the pinna or outer ear. The funky shape of our ears isn't just for show, it actually blocks or bounces incoming sound and subtly changes what comes into our ear canal. Our brains can pick up on these tiny changes and from experience match them to directions of sound. If you change the shape of your pinna then it can take a week or two for your brain to learn how the new shape alters incoming sound, but it will eventually start to match directions again. Reproducing this effect when using headphones is much more difficult but games can apply a generic alteration to sounds from certain angles which your brain will eventually learn to recognize."
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7d3cun | How does fast charge in mobile phones work? | Is it a kind of upgrade on the charger or on the phone? | Technology | explainlikeimfive | {
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"Both, and exactly how it works depends on the specific fast-charge technology. Most work by monitoring heat and cranking up the voltage as high as the system deems it safe to do so, possibly using multiple paths for the connection. Some instead (or also) raise the current used for charging. Either way, both the charger and the phone must support the specific scheme in use, or they'll fall back to the \"best\" scheme that they both *do* support - which might very well be all the way back to basic USB power delivery, which isn't fast-charge at all but is by definition supported on anything that charges over USB.",
"It usually sends a signal to the phone to see if it is compatible, if it is it increases the voltage from 5 volts to 9 or 12 volts at 2 amps. Higher volts at the same amperage is more power."
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7d3ft3 | How do automatic windshield wipers know when the windshield is wet? | Not to mention how wet it is. Edit: flaired as 'technology' because there's no 'black voodoo magic' option. | Technology | explainlikeimfive | {
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"There is a sensor on the windshield, usually translucide so you don't see the wires. This sensor act like a phone touch screen, it changes capacitance when water is rolling down on the windshield. this changes inform the onboard computer and automatically engage the wipers. Some also provide how much water there is. There is a few other ways to detect rain, Different brand will use different sensor technologies.",
"...cars have these? Either I'm broke or we're living in the future.",
"There is an optical rain sensor that is able to sense the droplets and turn the wipers on. Edit: Who the hell downvoted me? I do this for a living. Lol"
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7d43kp | How come a few feet can make a difference in signal strength even when the signal is coming from miles away? | Technology | explainlikeimfive | {
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"The signal is reflecting off some items, blocked by others. And the reflections can collide with each other, creating complex patterns of interference over very short distances.",
"It's like the sun, it's millions of miles away but a few feet can mean the difference between glaring brightness and significant darkness. Much in the same way cell phone towers can have very small dark spots (like shadows)."
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7d5nf4 | What Is The Difference Between A Regular Rocket Engine And A Vacuum Rocket Engine? | Technology | explainlikeimfive | {
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"A rocket engine optimized for vacuum is likely what you mean. It will have a different \"bell\" on the end to let the gas expand a bit more When in the atmosphere the air pushes back against the exhaust so it can't expand as much as in the vacuum so you need a different shaped exhaust nozzle to make it as efficient as possible. Vacuum has no air pushing back so it needs a different shape. You can optimize your rocket engine for atmospheric operation, vacuum operation, or a mix of both. Second stage engines generally only fire outside of the atmosphere so they're optimized for vacuum operation. First stage engines take the rocket from sea level to space so they compromise and make it pretty good at both sea level and in space A rocket engine will work fine at sea level or in space no matter where it was optimized for, it just might not be as efficient as possible"
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7d6kgx | What's inside public commercial electric vehicle DC fast charger (50kW < ) that makes it cost $30k or more? | Technology | explainlikeimfive | {
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"text": [
"A rectifier and DC power supply rated for 50+KW. That's a rather high power piece of kit, you can't make it with Radio Shack diodes. That device consumes twice the power needed to trip the mains breaker on your house."
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7d7px9 | How do CRT displays have the ability to display video below the maximum resolution without the use of interpolation? | I hear that the old CRT displays can operate at different resolutions without the use of any upscaling methods. The flat panel displays can only operate at the maximum resolution format. That means digital video upscaling is required to match the maximum resolution of the display. It is hard to find a good explanation on this. | Technology | explainlikeimfive | {
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"Digital displays have a fixed number of pixels, which is what is called the \"native\" resolution of the display. Because of this fixed number, any resolution that tries to display less pixels than what are physically present requires interpolation if you want the image to fill the entire screen (display scaling). If you turn off display scaling, you get a sharper image at lower resolutions at the cost of the image not filling the entire display (black bars). & nbsp; CRTs on the other hand, shoot electrons at a screen which excites material on the back of the glass display, and creates an image. CRTs being analog, you have a theoretically infinite number of resolution possibilities without needing any interpolating, because there are no fixed number of pixels on the display. This gets into the differences between digital and analog in general. Hope this helps."
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7d82l1 | what is data mining | Technology | explainlikeimfive | {
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"Data mining is finding patterns in massively large amounts of data. There's no universal definition of what constitutes \"big data\", but a general rule of thumb is that if it fits in RAM on a single computer, it's not big data. Today you can get a standard-sized tower desktop computer with 128GB of RAM for under $10,000. [One example from HP]( URL_0 ) - so for sure if you have less than 128 GB of data, it's not big data. Some would even say if you can fit it on a single hard drive it's not big data. So even a few terabytes wouldn't be \"big data\". Good examples of big data: * Every Google search ever performed * Every SMS sent from a Verizon user * Every show watched by Comcast digital cable subscribers * Every \"Like\" clicked on by Facebook users * The compute human genome for all individuals who have had their whole genome sequenced Each of these data sets is trillions and trillions of data points, too much to just look for simple patterns. Data mining is the practice of looking for previously unknown patterns in this data, and coming up with ways to better understand all of the data. It relies on techniques like statistical analysis and machine learning. A good example of data mining is anomaly detection. What are data points that stand out as different, unique, or unusual? In what *ways* are they unusual? Because of the massive size of these databases, it's not practical to predefine what it means for a data point to be unusual, or manually look through the data to figure out what to look for. A better technique might be to come up with a Naive Bayes model to predict the likelihood of each data point, then extract the top 1% most unlikely data points and then use k-means to cluster them and then extract prototypical examples of each type of anomaly."
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7d8ibn | How is it so difficult for video game publishers to detect cheating on PC? | Doesn't their code have digital signatures? Don't they have third party cheat drivers running concurrently? How are PC players able to defeat this and continue to ruin multiplayer games? Is their no practical way to prevent players from cheating in multiplayer? I could care less what folks do in single player but I'm having a hard time understanding how the information coming from a multiplayer client cannot be authenticated and validated and that the client runtime environment has not been currupted. | Technology | explainlikeimfive | {
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"The fundamental problem is that the user has physical control over their own PC and the only information the game manufacturer gets is whatever their PC sends. > Doesn't their code have digital signatures? Sure, and those can always be defeated someone with enough time and perseverance. Let's say the code is running on my PC. The first thing the code does is check to see if it's been modified, and refuse to run if its code doesn't match the signature. No problem, I just modify the code that detects whether it's been modified or not. The code uses the code's signature to encrypt all messages to the server? No problem, I just modify it so that there's another *unmodified* copy of the game installed and it encrypts messages using that signature instead. Basically any checks on the client side can be bypassed by a programmer who knows how to disassemble. It's only a matter of how long it will take or how tricky it will be.",
"Former game dev here, This is a bit out of my knowledge and experience, but I do know a couple bits that can explain how some of the cheating is happening. Multiplayer games are predictive - that is to say, when I start moving across your screen, it's because I issued commands from my client that I am moving. This goes to the server and is disseminated to all other clients. I start moving on my screen before the server even acknowledges it got the message. So your client knows who and where I am, and then it receives the command that I started moving forward. Your client will move my character forward indefinitely until it receives and update about my attitude - maybe I stopped or changed direction. The client will then apply this new command and make corrections to make sure it's consistent with the game world on the server. This is all very telling and an important insight. You can do things, and things can be done, out of sync of the server, authority isn't exclusive to the server, and consistency is a carrot dangled at the end of a stick. This sacrifice is made for performance. Games used to be made where the server was the ultimate authority and clients were only slaves, but latency was intractable. So because your client knows of the other players, who, where, and how they are, this information can be stolen from the running client. This would give a player an unfair advantage, a radar of where everyone else is. They know you're coming or where to find you. Hackers can also take advantage of the render pipeline and modify it. It could be as simple as set a surface to 100% transparency, or it may involve a sort of man in the middle attack where the API calls to the driver are intercepted and modified, allowing the hacker to see on the game screen any information about you available to him, such as player, position, and orientation. Needless to say, effort goes into preventing these sorts of hacks, but it's always a losers game. Any attempt to thwart these style hacks are on the hackers own machine, which they have ultimate control over. A persistent hacker will eventually subvert these defenses. Something like an MMO conserves computation and bandwidth by not transmitting to you the game state of the whole world, which is typically why players will suddenly appear from the ether in the far field. They didn't exist in your world until then. So at least there's that. And any logic where the client is the authority can be exploited. For example, in normal gameplay, if there's a latency hiccup, your client might inform the server you are somewhere else than it expected you to be - you turned when it thought you went straight, so the correction takes place on the server. This sort of logic can be exploited to bump you to all over a map. This sort of thing is going to be very game specific. Needless to say, we try to minimize how much of an authority a client is, where the server should always be the ultimate authority, but certain compromises may have to be made for performance. This sort of logic has undergone quite a bit of evolution and was not my expertise, I'm curious where it's at today. Some people are pathetic. They care about the hollow masturbatory sensation up in their taint of winning over noobs more than the challenge and excitement of the game, or the satisfaction of hard earning victory and advancement. They are boring, under developed, selfish, and anti-social individuals and a waste of the effort they put into their cheating, typically the type of guy who at 24 still can't grow a beard. And all you can do is jump servers to find someone worth playing with. And because that is your only solution, these twats bounce across servers and ruin the experience for as many people as possible. I, for one, cannot be bothered, and avoid multi-play with random strangers at all cost.",
"I actually used to write memory editing based hacks for games like First Person Shooters, and a few MMOs. I've created aimbots, wallhacks, no spread, no recoil hacks, shooting people through walls, and many other interesting things. For some MMO's, I've created speed movement hacks, teleportation hacks, super jump hacks, walk up walls/hills, etc. In one MMO, what was easily done was to tell the game you were \"swimming\" when outside of water. This essentially would turn off gravity and would allow you to \"swim\" through the air. It doesn't have that significant of an advantage, but I have used it to \"fly\"/swim over bosses to the ends of high level instances to unlock treasure chests and such, without actually having to fight the bosses. I've also used the swim hack to gain access to unreleased/new areas, and fly over otherwise dangerous places. Disclaimer: In no instances have I sold any such programs for money, nor broken any laws. Broken Terms of Services, sure, but laws, no. I'll try to focus strictly on the client-side of things. There are server side mechanisms in place, but often are not super robust, because it is very resource intense to track everything about a player, such as where they are aiming at any given second and regulate that. At the end of the day, the client handles a significant majority of the player info, depending on the type of game, and the server is trusting the client to send it accurate information. A lot of games do incorporate various client side mechanisms to detect unnatural memory changes, and in some cases it is effective, but usually only at a rudimentary level. It is impossible to give you a conclusive answer on how exactly certain mechanisms are circumvented, because it is totally situational and dependent upon the developer. A server side example: in many MMOs similar to WoW, in attempts to prevent movement hacks, the server may check your location every 5-10 seconds, sometimes longer, and check to see if you were able to move the distance that you did naturally. If it detected you moved unnaturally far in a period, it may switch you back to your previous location, and in many cases disconnect you. This for instance isn't fool proof as the server must account for lag and other subtle variations. In some cases, I have found myself able to get away with a 15% speed increase without the server detecting it. Sometimes higher, and have used this to outrun and solo bosses very easily. It's not perfect, but some advantage can come from it if done right. When a hack is being written, all the programmer is doing is spending time trying to understand how the game is handling and dealing with certain memory addresses. This frequently requires an understanding of assembly language, and an understanding of how to follow various instructions and changes through the assembly. In other words, it can be extremely complicated in some cases. As an example: some games may not have any mechanisms in place to prevent you from simply editing your coordinates and teleporting across the map. Whereas, some games may crash if you directly edit the coordinates, and instead may require you to edit the instruction that passes the number to the coordinate memory address. In some cases a hacker might have to completely rewrite the function which controls the players movement, which in doing so he can incorporate all sorts of nifty features, like controlling how fast he moves, passing through walls, jumping very high, etc. These are just examples. Technically speaking, pretty much ALL client side anti-cheat mechanisms can be circumvented if the hacker is willing to spend enough time studying how it works and how to get around it. A game developer might make modifying a certain aspect of the memory super difficult, and it might deter the hacker enough so that they don't even bother.... but if the hacker does manage to get around it, the game developer has to figure out what they did, and then block that means. In many cases, once the hacker has figured out the primary anti-cheat mechanism surrounding certain memory regions, it can be trivial for them to get around any updates made to counter them. The only way to make the hacker truly have to start over, is to completely change that anti-cheat mechanism... which if you're starting to catch on, can get VERY expensive for game developers. In many cases for hackers, it's simply a whole lot of trial and error, game crashing, game rebooting, etc. Sleepless nights screwing around with memory addresses for fun seeing what sort of interesting things you can make the game do without crashing it. Many hackers do this for fun in their spare time, and game developers frequently have to spend tons of money to counteract it. It's a never ending cycle. I used to just do it for fun. I would download games I didn't even care about just to see what sort of fun stuff I could do with the memory. In the most general sense, all a hacker is, is someone who studies a mechanism enough to the point where they can manipulate it for their own purposes. It's an engineering mindset. Most career hackers also typically have a somewhat advanced understanding of mid-high level mathematics as it is generally required for hacks such as aimbots and other related hacks."
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7d9dit | What determines what type of battery and how many of them a device takes, as opposed to just using less of a larger battery? | Technology | explainlikeimfive | {
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"These days anything you think of as a “large” battery is just a whole bunch of 18650 batteries wired together. You just wire it to make the voltage you want, and the rest are there to supply more mAh, which equals more runtime.",
"Batteries are spec'd based on the particular application. How long do they need to last, what run-time is needed, what power output is needed, how fast should you be able to charge them, how much can they weight, and how much can you spend on them? These are some questions that will help determine the battery chemistry and package. A \"battery\" is actually a collection of cells but we often call single-cell applications batteries as well. Most lithium cells today come in two flavors, lithium polymer cells and 18650 cells which look a lot like a large AA battery. There are several different lithium chemistries, the most common being \"lithium-ion\" which is itself a broad term that can refer to many other specific chemistries. Lithium-cobalt is the most common type of lithium-ion chemistry. Lithium polymer are the kind of batteries used in mobile phones and ultra-thin laptops. They have an aluminum foil type outer package and are usually pretty thin and flat. (They can also burst into flames if punctured.) Lithium batteries have a much higher energy density than traditional sealed lead acid or alkaline batteries which means they can store more energy per cubic volume. They typically have a cell voltage of 3.7-4.2 volts per cell. For applications needing 12v, you simply connect 3 or 4 cells in series to reach the desired voltage and use a voltage regulator on the input of the device to achieve the desired voltage. We'll call this a bank of cells. You can connect multiple banks of cells in parallel to increase the capacity, or mAh, to give you a longer run-time between charges. The specific chemistry and quality of the cells will dictate how many times the battery can be recharged. Seal-lead-acid = cheap and heavy, few recharge cycles Lithium = expensive and light, many recharge cycles It all goes much deeper than this, but this should give you a general idea."
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7d9unc | Are captchas actually effected against bots? If so, how does to stop them? If not, why hasn't there been a change? | Technology | explainlikeimfive | {
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"captchas are only about 50% about preventing bots. There are many more effective ways to prevent bots - captchas are used when preventing bots is at least a favorable outcome but is not of a real dire security concern. the other 50% of their purpose is to actually teach bots (AI) *(If a bot puts a picture and 90% of users answer the question about that picture a certain way - then the bot (the AI) learns what to look for in pictures such as that.....AI is learning from the user)",
"Bots used to be bad at image recognition, so asking to recognize a picture or skewed text tests if your a human. However Captchas themselves are changing that. One of the true purposes of a captcha is to train ai to recognize pictures . For example, you are asked to select the pictures with a train in it, or to write letters you see. There is sometimes no right answer, but a acceptable answer. If 1000 ppl say pictures 1,2,3 have trains in them, some minor variation is allowed, for example you could say pictures 1,2,3,4 have trains and it would accept your answer. Its about the group collective answer. That way, ai are informed which pictures have trains and add it to its dataset in learning what a train is. A non finite number of pictures can be pulled from google street view and displayed this way in all sorts of combinations"
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7dco1l | With the growing world recognition of climate change, and the push to switch to renewable energy, why aren't most countries looking at Nuclear Power as the way forward? | Surely Neuclear Power would be the most effective, cleanest form of producing large amounts of power, correct? | Technology | explainlikeimfive | {
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"Nuclear power is an extremely expensive commitment. It takes a lot of capital up front to get it up and running. You are making a bet about how competitive it is going to be against other sources for the next 30-40 years, if you require it to at least break even, much less if you think it needs to compete against other sources in a competitive marketplace. This has been a problem not just in capitalist countries but socialist ones as well. It is a general issue with nuclear and not a new one (nuclear power construction was already dipping in the US prior to the accidents). There are also political difficulties regarding things like accidents, waste, etc. Nuclear enthusiasts (and Redditors) like to wave these away as irrational, but they are serious enough that private insurance agencies won't cover nuclear power plants for disasters because even though the risk of accident is low, it is not zero, and the cost of dealing with accidents is very high. There are certainly many irrational fears in this domain (as in most domains of unfamiliar science/technology), but there are also tricky problems at the core of the issue. Many very non-irrational people have concluded that nuclear is a hard sell on this front, that things like truly long-term waste depositories are actually difficult technical issues on top of being difficult political issues. Separately, there are difficulties in using nuclear to help with climate change. There are reports that estimate how much nuclear you'd need to put in place, and how much fossil fuels you'd need to displace, to make a dent in the degree of warming. It is a phenomenal amount — a massive increase in new nuclear plant orders (and replacement of the very old fleet of plants that are gradually being shut down). This does not mean it is impossible, it just means that the political will necessary would need to be _massive_. Even separate from the people who don't support nuclear power (rationally or irrationally), other than the true-boosters there is nobody really clamoring for it. Whereas the enthusiasm for new fossil fuel sources is abundant and well-financed. So it is unlikely to matter on the climate front anytime soon. If fossil fuels were heavily taxed, and nuclear technology heavily subsidized (more than it already is), one could imagine nuclear gaining more industrial support. As it is, outside of basically France it is considered a \"boutique\" power source that can augment a grid but does not dominate it. I would just note: I am not particularly for or against nuclear (I am for it if it is well-regulated and kept safe, against it if it is not — this seems a fair position though I acknowledge that experts and industry advocates will disagree on what \"well-regulated and kept safe\" means). I am well aware of the problems with fossil fuels (as one colleague of mine put it, if nuclear power was implicated in 1/100th of the deaths that coal power is implicated in, there would be no nuclear power), and I am not someone who is terribly optimistic about going full-renewable either (the base load availability problem seems very difficult). I think nuclear should be part of the conversation about energy and climate change, but I am not optimistic that it — _or anything else_ — is going to get us out of the problem we've made for ourselves. I think pro-nuclear people find it easy to imagine that the only problems of nuclear power are the fears in the minds of ignorant people, but there are more difficulties than that, for better or worse.",
"Politics People are scared of nuclear power, despite any engineering merits it may have people just don't want it because they're afraid of \"nuclear\" and \"radiation\". Facts are irrelevant because you can't reason someone out of a position they didn't reason themselves into, so fight the battle you can win and push for wind and solar and batteries",
"Much of the general public have qualms about it, whether it's through being uninformed or just stubbornness to change. There's a lot of fears that come with the word \"nuclear\" like the radiation, what happens if there's a melt down (like Fukushima and Chernobyl [even though Chernobyl was literally their fault]( URL_1 )). That fact is Nuclear Power Plants are some of the safest facilities there are with multiple redundancies to prevent a disaster. The only real problem I've seen so far is dealing with the nuclear waste, since the only solution is literally just [burying it in a mountain]( URL_0 ). Finally it's very political with the \"Save the Coal\" and \"Save the Oil\"."
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7dda4w | How come one power strip with 12 plugs is okay, but linking two power strips that each have 6 plugs is dangerous? | Currently in class and there is a power strip that allows 12 things to be plugged in. How come it's safe for that power strip to have so many plugs in it; yet having two power strips (first one in the outlet, the second plugged to the first) is dangerous? | Technology | explainlikeimfive | {
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"It's not inherently dangerous, but having too many things running off of one circult can overheat the wiring and either trip the circuit breaker or start a fire. A 20 amp circuit breaker can handle 2400 watts of power. You just need to use 12 gauge (or thicker) wiring to handle that much power. However, some power strips might have 14 or 16 gauge wiring in the cord, which is thinner. So as long as you are careful and don't overload anything, you could theoretically have twenty power strips all daisy chained together and not have a problem. Most people aren't that conscientious and so laws are written to protect everyone from that one stupid guy among us who just can't use any common sense. If you want to know whether what you are doing with the power strip is safe, simply hold on to the cord, near the plug. If you are overloading the cord, it will be very hot, so hot you can't hold onto it for more than a few seconds. If it's warm, that's fine, but even a warm one you should keep a close eye on.",
"Because plugging the second 6-plug into the first means the *entirety* of the second 6-plug's power is being fed through a single outlet of the first 6-plug strip. This can easily overload the output and cause a fire."
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7ddyxj | Would a rotary phone work in a modern phone jack? | Would it only receive calls or could I dial out? | Technology | explainlikeimfive | {
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"Many, but not necessarily all landline phone provider still support pulse dialing, which rotary telephones use exclusively. A few years back I purchased a new telephone that lacked dtmf signals, and it still worked without issues using pulse dialing.",
"There's nothing \"modern\" about a wall-jack. It's been the same for decades. A rotary phone will be able to receive calls. It might not able to *place* calls, because pulse dialling might not be available - this has nothing to do with the wall jack, though.",
"If you have a regular analog copper landline, it will almost certainly work normally. If you have a \"digital voice\" or VoIP line, like the ones that many cable companies bundle, it will depend on the type of ATA you use. Most of them, in my experience, don't support pulse/rotary.",
"Hard to say. I expect it'd depend on the carrier. My parents had a rotary phone until more recently (like in the last 5 years. They still have the phone, it's built like a tank). They only stopped using it because AT & T \"upgraded\" their system to tone dialing only."
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7dfnu4 | Telephone Country Codes | Canada and US share the same country code, 1. We don't duplicate any telephone area codes. Therefore any 10 digit telephone number should be unique. However when I a local number and add a 1 it gives me an automated message telling me I don't need to dial the 1. Why can't it just connect me through if it knows the number is not long distance? | Technology | explainlikeimfive | {
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"This isn't about country codes at all. Historically, any area code was preceded by a 1 or it wouldn't work. These days it's confusing. In some regions, phone companies require a 1 before the area code if it's not a free call. On some other companies (mobile carriers), the 1 is never required before an area code. On some others, it's *always* required before an area code."
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7dgybe | Why do so many spacestations on tv and movies have the same circular shape with a pod in the middle? Does this serve any real purpose? | Technology | explainlikeimfive | {
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"text": [
"In order to easily create artificial gravity you can simply rotate the space station around the central axis (probably the center of the pod).",
"I can think of one real world reason. All of the \"real\" space stations build to date have all been cylinders (basically). [All Real Space Stations]( URL_0 ) - each module of a large space station has to be brought up from the planet in a launch vehicle. And to date the most common shape for that is a nice cylinder with no long hard corners. At some point you don't just want a longer and longer cylinder. Imagine a thin cylinder space station one kilometer long, it's not very practical. If you want MORE space on your space-station you could: - branch OUT with attached modules on the side. Solar panels and compartments, like the ISS - make the cylinder's diameter larger, but then you need bigger rockets to bring the parts up. - OR make a circle out of lots of other smaller cylinders (and some creative curving technology). if you think about it, the circle makes a lot of sense. There can be a central area - easy to get to from the rest of the station. you don't have to craft elaborate designs - just the same piece attached one after another. Iconic in shape because it made sense in the early days of sci-fi and science fact, and some experimental designs actually were made with this in mind. Even the \"expandable\" space stations (and components) of the Genesis project are cylinder shaped. (see inside the link above) watch the ISS [being built]( URL_1 ) with lots of components (and mostly cylinders)."
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"https://en.wikipedia.org/wiki/List_of_space_stations",
"https://www.youtube.com/watch?v=h8kOAroNNAo"
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|
7dh5ck | Why do military helmets not protect the face like a medieval helmet? | Technology | explainlikeimfive | {
"a_id": [
"dpxqq35",
"dpxr04i"
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"text": [
"Because any helmet that adequately protected your face from bullets would restrict your head movement and vision, and not being able to see where you're going is more risky than running around with your face exposed.",
"First, facial protection interferes with getting a good cheek weld to see your sights/optics. Second, the primary purpose of helmets have to been to protect against fragmentation. Rifle bullets have easily defeated helmets except for the most rare exceptions up to the last decade. So helmets have primary been designed to deal with fragmentation from things like artillery and mortars. Third. Facial protection decreases visibility. Makes the helmet more uncomfortable to wear for extended time. And makes the helmet hotter."
],
"score": [
15,
9
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|
7dhogd | What's Intel optane? | Extra questions: - How does it work as a memory? - Can my laptop use it? (Lenovo Legion Y520) | Technology | explainlikeimfive | {
"a_id": [
"dpxx7bp"
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"text": [
"It's a memory technology announced by a joint venture of Intel and Micron. They have been a bit cagey about saying *exactly* how it works. It's not quite as fast as DRAM, but close. It's denser than DRAM. It's non-voliatile like Flash. It's more expensive than Flash. The only place that I've read about it being deployed so far is in some high-end servers. I believe (but am not certain) that they stack the memory chips and mount them on a multi-chip module substrate with the processor. This reduces delays between the processor and memory, which is where the biggest performance gains are to be had in computer architecture. It's a pretty cool technology, because right now computers use about 5 levels of memory. The first three, the fastest, are inside the microprocessor die itself. After that, you go out over the system bus to DRAM, which is cheap and fairly large and fairly fast, but volatile. But the bus is incredibly slow compared to the first three layers (the cache layers). The fifth layer is either a Hard Disc Drive or Solid State Drive, which are large and slow but non-volatile. If they can make it at a reasonable price point, it could squish the last two layers of memory into one, making system performance much faster. I'd *love* to see it in a laptop."
],
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7dibzk | What do OLED screens do that make them an improvement over LCD screens? | Technology | explainlikeimfive | {
"a_id": [
"dpy27up",
"dpyipfx",
"dpyl18w"
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"text": [
"Traditional LCD screens use a backlight, the LCD pixels change the color of that light as it passes through them. The backlight makes these screens thicker, and the LCD pixels can't block all the light from the backlight so the display isn't capable of displaying true black. OLEDs emit their own light, there is no backlight. This means the screen can be much lighter and thinner (even to the point of being flexible) and can display true black as each pixel emits no light at all when turned off.",
"At my friends work they have 2 TV's a Samsung Q and a Panasonic OLED. I can't believe the different in the blacks. It's amazing.",
"I bought an OLED LG tv back in 2015 and it has been awesome for watching shows. This article helped push me in that direction to purchase it: URL_0 The picture where they show the StarWars screen and just how much better the OLED screen looked was eye opening for me."
],
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]
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|
7djpob | What is that low humming/ringing sound we hear shortly after a TV or other device is shut off? | It's that noise you hear when you can tell someone has a TV or radio on a few rooms over even if the volume is off. I've heard this sound right before getting a text or phone call, too. I always thought I was some clairvoyant until I realized there must be a scientific explanation for it. | Technology | explainlikeimfive | {
"a_id": [
"dpyhyza"
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"text": [
"Every electronic device vibrates due to electronic collisions in the circuitry. It’s why you hear buzzing in overhead power lines. When electrons hit something, part of the kinetic energy transfer is lost as a pressure wave, ie, sound. In the case of TVs, radios, and phones, it just means the emitted pressure wave is at a frequency that is audible to you."
],
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3
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7dkflw | Why can’t bots check ‘I am not a robot’ checkboxes? | Technology | explainlikeimfive | {
"a_id": [
"dpye9n5"
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"text": [
"It's checking a lot more than whether you can check the check box. It checks how quickly you begin to move the mouse towards the checkbox, whether you move the mouse in an absolutely straight line, or at a steady speed, or indeed if you even move the mouse at all - it would be very easy to program a bot to click the check box, but all of these things would be giveaways that it's a bot. To see if it's a human, it checks that the time it takes you to respond to seeing the checkbox is what's expected from a human, that the mouse movements appear human-like, that the delay between the mouse reaching the check box and you actually clicking it are human-like. It might be possible to build a bot that does all of these things in a human-like manner, but if that bot runs over and over again, patterns would soon start forming where the mouse follows the same path each time, and Captcha would soon block that particular pattern of mouse movement."
],
"score": [
15
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|
7dl0id | Why does water on my tablet or phone screen make it act as if it was being clicked? | Technology | explainlikeimfive | {
"a_id": [
"dpyhp63",
"dpyl3di"
],
"text": [
"Because the touch screen of your phone is capacitive so it works by detecting whether or not something that conducts electricity is touching it. Water conducts electricity",
"You can also use slices of apples as well as hot dogs among many other things as a stylus for your phone."
],
"score": [
27,
5
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|
7dlh7m | Why social media apps prefer showing a trending or popular timeline as opposed to a chronological one? | Technology | explainlikeimfive | {
"a_id": [
"dpyli4j",
"dpyl2hd"
],
"text": [
"Remember, on platforms where you're using it for free, you're not the customer, you're the product (the advertisers are the customers). So they want to show things you're more likely to click on first.",
"It shows stuff people are more likely to want to see (popular stuff) so they keep using the service as they keep seeing relevant things"
],
"score": [
22,
21
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"text_urls": [
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|
7dmt0a | How do planes crash into each other? | I dunno, seems like there's an awful lot of sky to use. How do such things happen? | Technology | explainlikeimfive | {
"a_id": [
"dpywbat"
],
"text": [
"It is pretty uncommon, because yes the sky is quite big. It is more common around airports because the plane concentration is much higher there of course. Also, planes of particular types tend to use very similar routes and altitudes because they are the most efficient. Finally, air traffic controllers use holding patterns that are fairly consistent to avoid the mistakes that can come from complexity. These factors make a small increase in the probability of a collision, but I would imagine the overall safety gains more than off that risk. Also I’m sure there is some selection bias when you hear/think about aircraft collisions. They’re quite rare but extremely memorable."
],
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4
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7dpezi | Why do smoke detectors contain Americium? | Technology | explainlikeimfive | {
"a_id": [
"dpzimgx",
"dpzhdyy",
"dpzhyy5"
],
"text": [
"Americium is radioactive, and we put some next to a radiation detector. When smoke gets in there, the radiation can't reach the detector. Detectors are designed so this sets the alarm off.",
"Because it' radioactive. It's a low cost element that's not fubject to lots of proliferation risk. The radioactive decay particals detect the smoke.",
"So the first question to answer is \"how do you detect smoke?\" Humans can detect smoke by smell and by sight mainly, so let's start there. Smell is a pretty complex chemical reaction, where a certain airborne molecule fits into a complicated smell receptor in your nose. This smell receptor has a lot of different places that the airborne molecule could potentially fit, and depending on which one it fits into best, that's the electrical signal that gets sent back to your brain. I have no idea how you'd accomplish this in a way that is mass-producable and cheap. So let's move on to sight. As it turns out, that's a lot easier to fake. Human sight is pretty complicated, but you don't need to replicate the whole thing, just have a beam of light/energy that if it gets broken (by thick black smoke in our case) an alarm goes off. You could do this with an LED or a laser or some other similar light source, but those all require power. We want this design to be able to work with as little outside power input as possible, so that in the event of a fire that damages the power supply, it'll still work. So what do we have that can have a near constant stream of energy without power input? Radioactive materials fit that bill pretty well . Americium is a fairly cheap, fairly common radioactive material, and it emits particles that are large enough to get blocked by most smoke, making it ideal for this purpose."
],
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5
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7dps2o | When and how did the internet go from being telephone calls between computers to these giant "ISPs"? | Bonus question: how did the FCC get involved in what are essentially (to my understanding) telephone networks? | Technology | explainlikeimfive | {
"a_id": [
"dpzjrlv"
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"text": [
"The larger computers on the Internet were always connected by special network lines, not phone calls. Using phones was a temporary solution to get home computers and small-business computers connected until the telecom companies could build proper network connections using technologies like cable and DSL."
],
"score": [
7
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7dsw2l | How can a needle on a Vinyl record recreate music perfectly including the Audio highs and lows? | Technology | explainlikeimfive | {
"a_id": [
"dq03x48",
"dq053x5",
"dq041gf"
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"text": [
"Sounds are vibrations on the air. Highs are fast vibrations and lows are slow ones. The needle passes over ridges that cause it to vibrate fast and slow.",
"It can't. Not perfectly. I agree with you: how it can work at all with such great detail is short of a miracle. But it isn't without serious compromises: Bandwidth is 40Hz to 17kHz (exceptions are there of course, just so vinyl lovers dont feel the need to say how i'm wrong because some records do exist outside those limits..). Lower frequencies simply are too long to track with the amplitudes they need without the needle jumping out from the groove. We can also hit the next groove so the spacing would have to grow and there would not fit that many minutes on one side. Higher frequencies are too high and they can burn the voiceoil of the carving machine. We need serious cooling to go over 20kHz. 100kHz is the \"world record\" with liquid nitrogen cooled machine at full speed. Lowering to half speed carving means that the wow and flutter that are ALWAYS there, will become much harder to control and can rise up to be detectable. 16-17kHz is common lopass, 40Hz is hipass: that is our bandwidth. Doing this will give us at least some hope but we are not done yet. Not even close.. Next comes the fact that our surface noise is also a problem that makes the high frequencies VERY hard to reproduce. The noise that the needle makes when it scrapes along a surface would be too much. Since we have A: trouble with long waves taking up physical space and B: surface noise at highs.. we can attacks them both by using RIAA emphasis. What it means is that we employa filter that lowers all low frequencies (before we carve the master disc) and raises up all high frequencies. We emphasize. When we playback the disc, after the needle has picked up the vibrations, we put the same filter but in reverse: boost bass and lower the highs. This makes the surface noise drop below masking effect (louder sounds mask quieter ones) while also giving us physical room for our bass. And after this, we have to remember that the lower we go, the less and less channel separation we can have. In fact, everything below 250Hz is in increasing amounts mono information: both channels share the same signal. There is no stereo bass in any vinyl. And we are almost done.. We have to also limit the dynamic range after all that to about 70dB theoretical, around 50dB practical This means we can not pack as much energy into the track as we want, we can't peak limit the material to death.. This is where the \"vinyl is more natural\" comes from, it is just a different master, with the added flaws from your needle, RIAA filter and the inevitable slight distortion..",
"Sound is just vibrations in the air, picked up by little hair like fibers in your ear. If you've ever done the \"make your own record player\" experiment with a needle and a piece of paper rolled into a cone shape, you get the basic concept that the tiny bumps and grooves of the record, produce a reliable vibration when you run a needle over them, and when that vibration is amplified , even just via a piece of paper, it becomes recognizable to the human ear. Fudge I'm no expert but that's how I understand it."
],
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5
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7dtaqm | What is crypto-anarchism and what are it’s beliefs? | Technology | explainlikeimfive | {
"a_id": [
"dq08hqs"
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"text": [
"Cryto-anarchism, is (I believe) something that has arisen mainly out of bitcoin. It's the idea that we can de-centralize our lives away from the state, and the elements of society that have control over us. Bitcoin is the best example. Bitcoins are an encrypted currency, so its incredibly difficult for the state/government to see where money is, who controls it, or where its going. It's the encryption part which makes bitcoin beyond the control of banks or government as we can make transactions in secret, and without the over site of a bank. This has given is the possibility of a new, free currency - one controlled by individuals instead of banks. This is the basis of anarchism - that we can live as individuals, free from control."
],
"score": [
8
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} | [
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|
7dwm4j | why are credit/debit card authorizations painfully slow? | Technology | explainlikeimfive | {
"a_id": [
"dq0wiha"
],
"text": [
"From the question I can only think you are reasonably young, as it's lightspeed quick to me, an old fart. The vendor has a computer that has to connect down a phone line/ internet connection to a bank computer that has to verify the details line up with you, the customer, and that you have the funds, and then transfer those funds to the vendor. It has to do all this for thousands of people at the same time, all securely and without errors. I think it's a minor miracle it's as fast as it is."
],
"score": [
8
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|
7dxudz | Why is cat5 wire used for data? Could regular 18/2 wire do the same thing? | Since data is just 1s and 0s can you use any kind of wire transmit data? | Technology | explainlikeimfive | {
"a_id": [
"dq1414e",
"dq147br"
],
"text": [
"When you start transmitting data at radio frequency (CAT5 supports up to to 100MHz), copper is not just copper and the electrical characteristics of the cable start to limit how much data you can transmit and how far it can propogate. CAT5 is nifty because it has four twisted pairs of conductors (which minimizes some of the effects of long cabling) and it's standard therefore cheap to rely on. So no, you can't just use 18/2 wire. You could if you twisted 8 conductors into pairs, at which point you have a CAT5 cable.",
"It would work (TCP/IP has been successfully used across barbed wire before), but for maximum efficiency CAT5E uses the wire pairs and the twists that each pair have around the individual four pair to help reduce the possibility of crosstalk."
],
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15,
3
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7dxxdq | why does a 1080p movie, on a 1080p screen, have black horizontal bars at the top and bottom? | Technology | explainlikeimfive | {
"a_id": [
"dq14ead",
"dq14dmy",
"dq15smw"
],
"text": [
"1080p is the resolution. The black bars are all about aspect ratio. The screen size ratio of a cinema screen is different from your tv/monitor. To avoid warping the image, they need to add the black bars in order to achieve that same ration on your screen.",
"Unlike TV, which is almost always filmed at 16:9 these days, movies are often created in differing aspect ratio. The actual choice of aspect ratio is one of the artistic decisions made during the production of the movie. If you want to get rid of black bars you can either zoom in the image, cutting off parts, or you can stretch it out & distort the image. Neither of these are seen as idea.",
"The don't add black bars. The movie was edited into a wider aspect ratio than your TV. So when it's shown.....there just isn't any content for that area of your TV screen. Not all movies have the same aspect ratio, like TV shows do. In fact, if you go to the cinema and pay attention between the previews and the feature presentation, you'll actually see curtains on either side of the screen either move in or move out to accommodate the aspect of the content they are currently showing."
],
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4,
3
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|
7dyr64 | What does the "Night Shift" feature on an iPhone actually do? What are it's benefits? | Technology | explainlikeimfive | {
"a_id": [
"dq1axyb"
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"text": [
"it basically reduces the amount of blue light that's displayed by the display when the ambient lighting is low. blue light can interrupt sleep patterns and is generally bad for your eyes in low light."
],
"score": [
11
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|
7dyy65 | How does modern recycling work? How are containers filled with food handled? What percentage of recyclables are actually thrown out? | Technology | explainlikeimfive | {
"a_id": [
"dq1bw2u",
"dq1car7",
"dq1jno7",
"dq1hq03"
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"text": [
"This really depends where you are. Most food is collected, piled, composted and reused as fertilizer. As for recyclables, how much is thrown out depends on how good the sorting system is, also how much non-recyclables are put in initially. If you are really really strict on what goes in then you can recycle almost all of it, if not well... I'm not sure you want to share where you are from, but you could search how your particular municipality deals with waste.",
"According to my friend that works in that industry (in the USA here) food containers are thrown in with the normal trash because they can't be recycled. (We were told this year it's finally ok to recycle pizza boxes). the other stuff is sorted, some by hand, and bailed like hay and then sold to other countries that do the actual recycling. The USA doesn't have the facilities or the funding to do much of it. Recently less and less is being bought for various reasons. Most of the recycling in the USA is sold to China. E-waste is similar, but more of a human horror story in developing nations. The collection, sorting and bailing are all handled according to municipal and state law along with various county and city regulations/contracts. Business is business all around though.",
"Here in Denmark: Food is not allowed on recycling center. That goes in the household trash. All household trash is burned to generate heat. This is done in special powerplant that uses high heat, filters and other techniques to keep pollution at a minimum. The list of things that burns well includes many things you should never put on a bon-fire, like EPS (polystyrene cups, boxes etc).",
"In Finland a recycling engineer once said to me on a plant tour that returning your plastic or glass soda bottles to the store is Ok, but other plastic and glass packing materals are useless to recycle. There's always the one idiot who throws those in with food still in them, so they kept losing batch after another, making useless gunk. Now they just dump it all in one spot, hoping future generations can do something about it. I don't know if metal recycling has same problems. My quess is that metals are more expensive and worth some extra processing."
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7dz954 | How does an ISP plug into the internet? | Technology | explainlikeimfive | {
"a_id": [
"dq1e4kf"
],
"text": [
"The ISPs are the hubs that form the internet backbone and they connect to each other, and by extension the various servers and computers that connect to the ISPs and you have the internet. As to who runs the infrastructure, that varies by country but in general it is the ISPs. Individuals cannot directly tap into the backbone infrastructure. If a country has a strained relationship with others they often do not connect to the larger global internet, or highly limit how they connect. See China and what is called \"The Great Firewall\" or how North Korea has what is effectively a national Intranet rather than a real internet connection."
],
"score": [
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|
7e0mli | How do earphones produce adequate bass despite their size? | Technology | explainlikeimfive | {
"a_id": [
"dq1nw6z",
"dq2jery"
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"text": [
"Proximity to your ear. The volume of air displaced by a large subwoofer is large, but it is many feet / several hundreds of feet away from your ear. If you are too close to something of this size, you will be doing damage to your ears because the volume of sound waves hitting your eardrum is too large. Similarly, small earbuds produce a bass sound with a very tiny volume, but that earbud is mere millimeters away from your eardrum. Change that even to a few centimeters and the bass sound waves diffuse too quickly for them to affect your eardrum.",
"It's actually easier for an earphone to produce bass than for a loudspeaker to. The reason is that the volume of a speaker drops off by the square of it's distance. In short, this means moving twice as far, results in 1/4 of the sound reaching you. While bass frequencies travel farther through the air than treble does, it requires much more power to produce them due to the physical excursion required from a driver. The only way to produce powerful bass in a loud speaker is by moving air. This could be a very large speaker that moves just a little bit, or a smaller speaker that moves in and out very far. Either way it takes a LOT of power to do this and in order for the user to hear it, the speakers enclosure, and placement in the room is critical. However on a headphone, the speaker is very close to the ear, sometimes even inside of the ear canal. And since it is possible to form a sealed enclosure with the speaker on one end, and the ear drum on the other, powerful bass can be produced with very little excursion (very little air needing to move) and with very low power requirements. Larger, over the ear, headphones often have driver sizes of 50mm or more, which is a lot of surface area moving very close to the ear canal, and powerful bass can be produced. The other thing to consider is the tonal balance of the headphone speaker between bass and treble. If you had a perfectly balanced frequency response, and changed the speakers enclosure slightly to reduce the level of treble frequencies, the perception of the user is that the bass frequencies were made louder. They would simply increase the volume control to compensate, resulting in louder bass."
],
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8
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7e1at2 | How do music/video editing programs isolate vocals, frequency, pitch, etc.? | Technology | explainlikeimfive | {
"a_id": [
"dq1pqbf",
"dq1u5eg"
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"text": [
"It’s pretty complex but I think what you don’t understand is that the editing softwares are not meant to isolate anything, they’re meant to take the isolated vocals and turn them into a final product. So with each recording you can edit its pitch and frequencies and do whatever other mixing you wish to do, and then you mix everything together so it’s one big composition. Basically like a puzzle.",
"I don't think there's a good ELI5 answer to this, but basically it's math. Sound is a waveform, you can add multiple sounds together to get a new one. It's just like adding two numbers together. Basically if you want to isolate vocals you just do the opposite. You look for parts of the signal that look like vocals and subtract them out. The hard part is finding vocals. Typically programs will look for frequencies that correspond to vocals to find them but there are many tricks that involve very advanced mathematical techniques."
],
"score": [
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4
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7e1bvi | Why is it that almost all microsoft pc's start their drives with C? Why not A? | Technology | explainlikeimfive | {
"a_id": [
"dq1ps1d",
"dq1pive",
"dq1pmie"
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"text": [
"It's an older convention for computers. Drives A and B are dedicated for Floppy Disc Drives, used for installation of programs on to the hard drive C As the systems evolved, B became a backup to A, sometimes using the older, larger discs, and eventually they were removed entirely, leaving A and C. B was left behind in case. In the advent of larger programs, especially as programs started taking huge stacks of discs, the installations started to move to CD Drives (which defaulted to D), and the Floppy Drives began to be removed entirely. You are probably wondering why we don't move the C drive to become the A drive in new systems... Too many programs actually wrote in references to the C drive *specifically* as the installation drive, and changing it would have caused too many problems.",
"well A: was historically the floppy disk drives, i remember A and B being 5.25 and 3.5\" floppy drives, then the hard drive was C and later cd drives were D: Of course A and B are gone now...",
"Historically the first two drives were designated A and B and were floppy disk drives. You might not even have a hard disk drive at all, just A for the disk with the program you wanted to run and B for a disk to store the output. As technology progressed the C drive being the first hard drive and the location of the operating system became the standard, and there was no reason to break with tradition."
],
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7e1hfm | Why do ads load first, rather than the content of the site itself? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Because the site gets paid for how many views on the ads they get. Therefore add content is more important than the actual content. Sites prioritize this to make sure they get paid essentially."
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7e5m0p | How did the Game Genie from Galoob work as a cheat device? | Technology | explainlikeimfive | {
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"Well information about how the game operates is stored in registers. So your lives is stored in a register with a set number say 5. Should your character in the game dies the game is programmed to take the register for lives and subtract one. When the number is zero, it access the game over mode. The Game Genie intercepted this data and the codes would modify the programming so that it would ignore the lives -1 command that the game would send out or it could modify the state beyond what was hard coded in. It could also modify other values like say, what your jump height would be or your speed of movement."
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7e6b3g | What components makes batteries (Ex: Duracell) last longer than others | Technology | explainlikeimfive | {
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"text": [
"Electrolytic manganese dioxide (EMD). Manufacturing EMD for batteries is hard. You need good purity, the right crystal structure and many other factors to make a good battery from it. It is not marketing bullshit, as /u/T3Kgamer suggests. URL_0"
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7e6w24 | Why are my photos horrible and professional photos look amazing? I used to think it's because I don't have a nice professional camera but I've seen pro photos taken with a cell phone and they make mine look like garbage in comparison. What's the deal? | Technology | explainlikeimfive | {
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"First of all, by the time you see a pro's work, it's been through a lot of processing, like PhotoShop and the like. Cropping for the optimal composition, bumping colors up, enhancing clarity, etc, beyond what the camera itself is capable of. And it takes a lot of time to develop an eye for composition, that is, the best balance of objects in the image, how to make your subject stand out while de-emphasizing potential distractions. Should this subject be captured from a low, middle or high angle? Where's the light source and how is it going to affect the final image? Other variables are camera settings. ISO affects sharpness, but lower values increase exposure time, so can't be used for things in motion, unless you're intentionally going for a blurring effect. There are lots of other variables, but those are the ones off the top of my head. I'm not a pro, by the way. Maybe one will drop in and do a better job of explaining.",
"A better tool makes difference for the expert, not so much for the novice. What you see as quality is an understanding of composition, light, shadows and the limitations of the camera. The professional fotos are not \"Wow, cool, lets snap a shot of that!\", they are carefully planned. Some tips that will make you a better photographer: * Flash. Avoid flash if at all possible, it makes the photos look flat and washed out. If you need to use it, try to aim it at the ceiling or a wall, so you bounce the light. * You are a photographer, not a sniper. Don't aim directly at the subject, aim a little off. Usually, a good rule of thumb is to place the subject 1/3 of the image from either edge, vertical or horizontal. If you shoot a person in a landscape, don't have the person stand in the center of the picture looking at the camera. Place the person 1/3 to the side, looking sideways at the scenery, pretty close to the camera, and place the horizon 1/3 from either top or bottom edge. * Light. Photos live and die by light. In most cases, the ideal position of the main light is something like 45 degrees out over your shoulder. Sometimes you can play with light a bit, such as shooting a person with the full moon directly behind him, as a dramatic outline in the night, but usually, the light should be slightly from above and 45 degrees out. Smaller filler lights help reducing drastic shadows, but don't overdo it, or the foto will be flat and lifeless. * Understand the subject. For example, say that you want to shoot a vast desert landscape. Well, first of all, you may want to do a panoramic shot for that (AutoPano is great software for that). Then, think about what makes the desert so big, what makes you feel so small. Your gut instinct is to lower the camera so you get a lot of desert. Your gut instinct is wrong. It's the vast sky that makes it huge. Place the horizon 1/3 from the bottom of the image, and you get your vast desert landscape. * Don't be afraid to zoom. People often want to get as much as possible. Don't. Decide on what you want to shoot, and go for that. Say, for example, that you want to shoot a magnificient tropical sunset. Your instinct may be to zoom back to get all of it. Don't. Zoom in on the setting sun, with a palm tree in the foreground. Now, you get just the magnificient colors and the outline of the palm tree, and a much better shot. * Depth. If you shoot landscapes, have something/someone in the foreground to give depth (and remember the rule of 1/3) and to make it interesting. * Don't tell people that you are taking there picture. Unless they are professional models, it'll be awkward and unnatural. Just shoot when you get a good shot. Don't stalk people, though... * Shoot a lot. Pros shoot 1000s of pictures to get a few good ones. You'll probably have to shoot more... * Evaluate your photos. When you get a good one, look at it and think about what makes it good. What makes it different from the other photos that are bland and boring? * Tools. A good camera helps, but you can do a lot with a simple camera. I would advice against a phone, though, as they are a big mess of compromises, especially when there is low light (that tiny lens doesn't let much light in compared to a large camera). Get a simple camera and use that until you understand photography so well that you feel limited by it, then upgrade. Even if you later buy a SLR camera, you'll still often find that small camera useful, because the best camera is the one that you have with you. A very good book on the subject which I can recommend is Digital Art Photography for Dummies. Now, I really don't like the \"for Dummies\" series, but this one is good. It gives simple advice, and just reading it and keeping some simple things in mind will make you a better photographer. It sure helped me a lot. (Yeah, I know there are situations where these tips don't apply, but this is an ELI5, aimed at a beginner, so let's keep it simple. Following the rules until you understand them well enough to understand WHY you sometimes benefit from breaking them.)",
"In addition to what Erwin said, the Pros take a LOT of photos. In the days of the huge cameras with glass plates, a photographer like Ansel Adams or Robert Capa would take a few dozen to get the one good one that would be printed, that we look at in books today. In the modern day, with digital cameras and massive amounts of storage, with instant results, a pro might take a few hundred photos to get the one that goes in the magazine. It's a type of Survivor Bias.",
"lighting and composition. and i bet some degree of photoshop to smooth the image out a little bit.",
"I think ElMachoGrande said it the best. I used to take photography classes in high school back in the 70's. We had SLRs with multiple lenses and 3x5's. We developed our negatives and printed our images ourselves. Most of his recommendations are the same as we were taught because the principles of good photography never change. Like any art, it's mainly about learning from people who are gifted and whose work you admire. But there are some basic rules. Following them will help you to get better, faster. It's not about Photoshop, no matter what anyone says. Photoshop is just a tool to be used in post-production. The mastery of tools is not going to make you a photographer. Your *eye* and your perception is what makes you a photographer. You have to recognize an image's potential and be able to figure out how to make the most of it long before you ever get to post-production."
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7e7e0a | How do old TV shows change their Aspect Ratio to 16:9? | I was watching old Sitcoms and Cartoons, and noticed that alot of these have been 'converted' to the 16:9 aspect ratio. While their were originally shown in the 4:3 aspect ratio. The newer versions with the 16:9 aspect ratio don't look like they've been stretched or extremely cropped, but are still wider and have more background. How is this possible? | Technology | explainlikeimfive | {
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"They were originally filmed with widescreen cameras and cropped afterwards. However, these shows often had their photography planned for a 4:3 aspect ration, meaning they knew part of the image would be cropped out and thus didn't really care what was visible at the edges of the camera's field of view. This has caused issues where old shows being remastered in HD now have continuity errors or visible filming equipment in the corners of the screen because the studio rushed out the remaster without much quality control.",
"That largely depends on how the initial shows were shot. A lot of television dramas from the 90s, like ER or like X-Files, were shot on 35 mm film which usually has a default aspect ratio of 3:2 (which is larger than the aspect ratio of 4:3 that we consider to be full-screen). So while those dramas were broadcasted in 4:3 and even framed and directed as if it was 4:3, its source imagery is going to be 3:2 which can be easily converted in 16:9 for homevideo- or streaming-use."
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Subsets and Splits