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9dgow5 | How camera facial recognition works | Technology | explainlikeimfive | {
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"It's simplified to something the camera program can understand like this: \"Look for an oval spot of roughly same color with different color spots inside where eyes and mouth would be.\""
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9dj6jj | What is really in the online terms and conditions? | I assume it's mostly legal jargon. Do companies have to disclose everything that their software does to your computer, such as permission that you'd need to allow? | Technology | explainlikeimfive | {
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"Ideally, Terms and Conditions should describe the product or service, describe how it is meant to be used, how it is not meant to be used, what steps a provider can take to discriminate against misuse, what sort of accountability the user has in regards to what they do with the product or service, what sort of accountability the provider has for what you do with the service, instructions of cancelling the contract, and a detailed description of fees or payment services. It can all be boiled down into simple and readable sentences, but in order for it to be legally binding, it has to be incredibly specific. This is because ambiguity in a contract favors the person who did not draft the contract."
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9djkyx | Why do computers freeze? | Technology | explainlikeimfive | {
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"When you send a command to your computer (Like pressing on a button, clicking on your mouse or even moving it and so on) it enters a queue and your computer knows to read all of them according to the order they were sent. The reason for that is that some of the actions your computer makes cannot be interuptted and it has to wait until their completion. If that is the case, the queue is filling up and is not being read. Sometimes these actions are waiting for something to happen (like reading data from your hard-drive or finishing a calculation) and if for some reason this takes a long time (There can be many reasons for that, like a hardware problem, corrupt data, infinite loops etc) your computer will appear frozen.",
"In addition to the responses given, another reason is a deadlock. That occurs when the computer is doing more than one thing at a time and 2 of the things are waiting for each other to complete. It’s like when two people try to enter a doorway from opposite sides and the first person says “after you”, and the second person says “no, after you” and the first person says “no, after you”. This goes on and on , meanwhile your computer is frozen because neither person is walking through the doorway. The only way to stop it is to kill one of the things that are waiting. Some programs do this automatically, sometimes you have to restart your program and sometimes you have to restart the whole computer to break the deadlock.",
"One of the most common reasons why your computer seems frozen during \"normal\" handling is that is ran out of memory (RAM). If that happens currently not used memory gets written into the harddisk. Normally you don't notice that as the RAM isn't used anyway. But now you switch the application and it needs the memory which had been written to the disk. The application itself has no clue about that as it is handled by the operating system (Windows etc.) and therefore can't react like showing a loading bar as it is still waiting for it's memory. Once it got loaded from the disk you can use the app as you did before. But if you now switch back again it will freeze again... This often happens with badly optimized applications like Firefox. Edit: this is called swapping btw.",
"In addition to the above Waiter analogy, computer programs, as well as the operating system (Windows, MacOS, or Linux) are written as a list of instructions. Sometimes, those instructions get confusing or aren't able to handle something weird. Sometimes this will cause them to go into and change data where they shouldn't or they may go into a loop - repeating the same action over and over again because the instructions are looking for a value that has already passed or that won't appear."
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9dk9mx | How does my gps know about traffic conditions miles up the road? | For context, I use the Maps app on my iPhone. It’s pretty accurate when it comes to reading traffic conditions. | Technology | explainlikeimfive | {
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"Your GPS does not. The maps app does. How? Because countless other people are using the app and apple is using data from their travel to determine traffic conditions in real time.",
"The app works by analyzing the GPS-determined locations transmitted to it by a large number of mobile phone users. By calculating the speed of users along a length of road, it is able to generate a live traffic map. It processes the incoming raw data about mobile phone device locations, and then excludes anomalies such as postal vehicles which make frequent stops. When a threshold of users in a particular area is noted, the overlay along roads and highways on the map changes color."
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9dkock | Why/How is planned obsolescence not illegal? | Technology | explainlikeimfive | {
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"It's hard to prove that you *meant* to make the device break down in two years. And cutting production costs is not illegal.",
"First off, it's not an explicit choice to design something for \"planned obsolescence.\" And virtually nothing can be designed to last forever. So companies designing products weigh tradeoffs on aspects like expected lifespan in a customer's life, costs, and other performance factors to design a product that will best meet all these needs. Let's take an iPhone as an example.... most people upgrade their phone every 2-3 years. Most people want something lightweight, small enough to fit in their pocket. They want to spend a few hundred dollars. So Apple, Samsung design to those specs. Could they build a phone to last for 10 years? Maybe... but how many people WANT their phone to last 10 years, given how technology advances? Who wants a phone that's 3x as thick to withstand that many years of abuse, battery loss of life, etc.? And would people be willing to pay $2000 for such a device? And with all items people buy, there are a variety of options that run the price/quality spectrum from which they can choose to buy. You can buy a $20 toaster that'll last you through a year at college. You can buy a $300 one that will last a generation -- your choice.",
"Why would it be? No one is forcing you to buy their product, and you can’t expect a company to support and maintain a product for an infinite amount of time, if you did, they’d not be too keen on making anything new, as they’d have to spend all their time and money dealing with the old."
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9dkpx3 | How do wireless chargers work? | Technology | explainlikeimfive | {
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"they use an electro magnetic field to “send” electricity over a small gap when electricity flows through a coil it creates a temporary magnetic field. when another coil enters this field, current will start flowing through it allowing a device to be charged wirelessly. hope that explains it well enough."
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9dld6t | How do the lasers on modern computer mice track the movement of the mouse? | Technology | explainlikeimfive | {
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"The laser and LED based optical mice work in a similar way. The laser illluminates the surface at an angle, and there's a sensor that looks straight down on the point that's illuminated. What that does is highlight the imperfections in the surface to make movement clearer to the sensor. Like looking down on a mountain range at sunset. The sensor takes many many pictures a second of this illuminated surface and uses a bit of clever processing to figure out, looking at how the image shifts between shots, which direction the mouse is moving in, and passes that back to the computer as a cursor movement. Laser mice were originally better at more surfaces than LED mice, but in new ones, the difference is much less obvious."
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9dqcl1 | How do we know a computer is "learning" in a neural network and not just keeping track of certain, very specific inputs to be repeated the same way every time? | Technology | explainlikeimfive | {
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"Smart question. The latter case is called *overfitting the data* or *overlearning,* and you can test for it by seeing how the computer responds to new test inputs. If it's great at the original training inputs, but useless at the new inputs, that shows overfitting.",
"It is very possible to build a “memorizer” as you describe. In ML, we call that overfitting. The way we test if a model can generalize is by showing it many inputs it has never seen before, but we know the right answer and see if it gets them right. For example, if we train an algorithm to identify cats and it can only identify cats that we’ve shown it before, it’s overfitting. But, if we show it lots of cats it has never seen before, and it still gets it right, we know it generalizes.",
"Isnt that what learning is though? Finding the best/most efficient way to do things, and repeating them?",
"We don't. There are countless stories of neural networks failing because they focused on the wrong thing. Ones I know off the top of my head A) Neural network to spot tanks. Stock landscape photos were all sunny days, real pictures of tanks (being a British project) were all rainy. They built a neural network that could tell you if it was raining. B) Experimenting with using a neural net to manage trains. If the station was busy, send more trains. If the station was quiet maybe hold optional trains. It mostly worked, except not always. Turns out the criteria the net picked was whether a certain bin was visible. If it was visible, no trains. If it was obscured, more trains. Hell, one of the big flaws with neural networks is that they don't really tell you anything, even if they work. One of the working ones we studied was using GCMS to tell the difference between olive oil and virgin olive oil. It had full control over GCMS settings, read the output and 100% of the time could tell the two apart. However it failed in it's goal - the neural network could tell the two oils apart, but it didn't shed any light on what the difference was. We had a black box that did it for us.",
"Others have answered this fairly well but I'd like to add a little more \"ELI5\" explanation. The word \"learning\" isn't the most accurate way to describe it. Most machine learning is just fancy classification. Even the best machining learning algorithm can only classify what its seen before, and it can only distinguish between classifications based on features that it knows it look for (although you can tell it to decide what these features are in some forms of machine learning). In essence: it is looking for specific inputs, just not \"very\" specific, and if you train it well, it won't be \"very\" specific, it will be more general. So: if you only show it cats in training, it will classify dogs as cats. If it only sees mammals, it will never be able to distinguish a reptile. The key in ALL machine learning is a good, diverse training set.",
"You say \"computers\" as if this doesn't happen to living brains as well The concept of \"over fitting\" is when an intelligence, artificial or real, learns a pattern is significant, when in reality it's actually not, simply because of the specific 'training data' or 'experiences' they have been exposed to. One example being if you're trying to teach a computer to distinguish videos of bees from videos of dogs, the computer might see that all the videos of dogs are 720p and all the bees are 1080p, and so it might learn that 720p things are dogs and 1080p things are bees. But humans do the same thing too, like how most human brains learned that blowing into the N64 cartridges made it work. Every experience we've witnessed included us taking out the cartridge and blowing on it and putting it back in, and, it works now. So we learn that the process to get it to work again is remove-blow-reinsert, when in reality, all we needed to do was remove-reinsert. Because of the experiences we've had that gave us the information we need to learn, we accidentally saw a pattern that wasn't there, because of the specific subset of all possible experiences ever that we have happened to personally witness",
"You have to purposely be broad and varying with what data you feed the neural network so it can get as complete a picture as possible, and not feed it too much data. Feeding it too much data will make the model too narrowly defined, you need to leave it some breathing room and ambiguity. And after a neural network is trained, you test the hell out of it. You want to throw the network curveballs to see how it responds.",
"You avoid this by having two sets of test data: one used for training the algorithm, and one for testing the result, i.e. you only let the neural network \"learn\" based on the first set, then you deactivate the \"learning\" and see whether it has good results on the second set. Of course, you still have to ensure that both sets are representative and there will probably always be edge cases you'll fail on, like the [leopard print sofa]( URL_0 ). Neural Networks have their limits."
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9dqfg7 | Why do some programs stop working properly and need to be reloaded after the computer has been idle for quite some time? | Technology | explainlikeimfive | {
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"Think of running a program like building a shed. You use the blueprint of a shed to build the structure. The shed gets wear and tear over the years, and stops being useful. Eventually you tear it down and build a new shed. Programs work the same way. Your hard drive contains the program, but it's just a blueprint. The actual program is copied over to RAM - basically your computer's short term memory - and does its thing there. Over time errors and memory leaks could build up and it stops being useful. Restarting the program means rebuilding the program from the blueprint, getting rid of the errors. It's just like rebuilding a shed.",
"As programs run through their code, or instructions, it's possible for the software to hang on a line which doesn't execute properly. Generally this stops processing as it is in a sort of infinite loop in that it's still attempting to move forward but some requirement isn't being met."
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9dqj5h | How exactly do data packets work? | What exactly are data packets and how do they work? | Technology | explainlikeimfive | {
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"That's a tough question to answer since there are many types of packets that all work a little differently. But fundamentally they work like a letter. They contain destination info, source info, and an actual message that all the various routers, switches, and devices on the network can use to identify where it's going, how to get it there, where to send a response (if requested), and whether/how to read the contents."
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9drdvt | How do shopping carts know when to lock up when taken out of the store or when it passes a painted line? | They are mechanical devices so how does a cart known when they have been taken out of bounds, such as when it crosses a painted line? | Technology | explainlikeimfive | {
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"I may have found yer answer, matey. Yer not alone in askin', and kind strangers have explained: 1. [How do self locking shopping carts work? ]( URL_4 ) ^(_1 comment_) 1. [How exactly do shopping carts lock once they reach a certain area? ]( URL_6 ) ^(_._) 1. [ELI5: How those shopping carts at certain stores seize from moving when taken a certain distance ]( URL_2 ) ^(_10 comments_) 1. [How do shopping carts wheels lock after they have left the grocery store? ]( URL_5 ) ^(_._) 1. [How do shopping carts lock around the \"yellow line\" in parking lots of major chains? ]( URL_0 ) ^(_1 comment_) 1. [ELI5:How do shopping carts lock? ]( URL_1 ) ^(_5 comments_) 1. [Eli5: how do shopping cart anti-theft wheel locks work? ]( URL_3 ) ^(_6 comments_)"
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9dtn4b | Why is it generally a bad idea to use your computer while it’s charging? | Technology | explainlikeimfive | {
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"That is a myth. There is no reason to not use your computer while it’s charging. I can post link after link to show this is the case.",
"The problem were the batteries. The old ones we used to have could not handle the stress of being charged halfway and powering the computer, or being charged halfway only and then used. This lowered the power the battery can hold and it became less and less everytime you charged it again. The new batteries we use today can handle it way better and can keep more power longer."
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9dtnur | How is a phone or portable charger or other device designed so that it knows how much it’s charged? | Technology | explainlikeimfive | {
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"It doesn't know, it gives an estimate. There's several methods to ddetermine this estimate but most common is coulomb counting, which is very ELI5 in itself. It is literally counting the number of electrons that flow in the battery (charging) and then count the electrons that flow out. Now your device does not do this by itself, rather it knows a table which maps voltage levels to the number of electrons in the battery. This isn't a 1:1 match, which is why you sometimes (especially on much used batteries) see that after heavy usage and the device is put away for a while you can see the charge estimate go up! These tables are made in the factory and programmed to your phone, when your battery starts to degrade the table is no longer accurate. Typical behavior are sudden drops in the % estimate, no longer charging to 100% or turning off above 0%. TL;DR so how does it know it is charged? It doesn't, it just assumes that a certain voltage equals a certain charge."
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9dujx1 | When someone is photoshopped out of a picture how do they place a background behind them where they were? | Technology | explainlikeimfive | {
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"There are 2 ways to do this: Use the clone tool in Photoshop to select the area right next to the person and replace them with that part of the background. Take a picture, wait for the person to move, then take another picture. Layer the pictures in Photoshop, then use a mask to hide the person in one image and let the empty background from the other one show through.",
"You cut a piece of background from the picture and paste it over them. Depending on the background, more or less difficulty is required to eliminate seams.",
"In a professional shoot, the photographer will often shoot a “plate” of the background with no people in it at all, so that people can be photoshopped out of shots if needed later."
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9dvgrg | how to mobile map apps get live traffic updates even down to each specific intersection during busier traffic times? | Technology | explainlikeimfive | {
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"You have a mobile map open. You are driving 55 mph. The company running the app knows you are driving 55 mph. You stop. The app knows you stopped. Over a period of 30 minutes, 100 cars are driving down a street with the map software running. Every single car slows to 10 mph for 5 minutes at the exact same spot, then resumes its prior speed. Your map software reports it to you as a 5-minute slowdown. Your software has live information while you are driving because you are transmitting everything you are doing, *as is everyone else using the app.*"
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9dy9bw | How emails work? | Technology | explainlikeimfive | {
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"Emails, just like real mail, have an address on the front. When you hit send on an email, your email provider navigates to the web address listed (everything after the @ sign) and tells that server \"hey, I have an email here for \\[everything before the @ sign\\].\"",
"What level do you want this at? At the most basic level, you have domains, and the domain servers have records that point to servers that manage the sending and receipt of emails. When you send an email, it has a body and a header; the header outlines who the email is from, what address it is for, and a bunch of optional details about the sender and how it should be sent. When the email is sent to the upstream server, it parses the header and figures out what server the email is supposed to go to -- it then relays the contents to the domain on record for that email address. That server then receives the email, writes a few more headers, and saves it somewhere that the recipient can check with their mail client."
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9e1bzu | how the Bluetooth, Infrared(remote control), and WiFi works. How do we transmit data over these three? | Technology | explainlikeimfive | {
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"You know your friend over the road? Maybe even you can't play at night you make a simple code flashing your bedroom light or a torch/flashlight off and on, and can have a simple conversation. It's slow and clumsy, but you might use a flash for \"can you play\", two for \"yes\", three for \"no\". If you could flash the light faster maybe you could make a more complicated code. That's how all those ways work. Bluetooth, WiFi and infrared all use different parts of something called the \"electromagnetic spectrum\" which are all invisible, but it's still the same method of flashing a light off and on, fast, to send an agreed pattern which both sides understand to mean something.",
"So they all transfer data over the electromagnetic spectrum. There is only one electromagnetic spectrum - this is important. When a transmitter transmits, it radiates out. You can focus the beam a bit, but anything down-range from that signal is going to receive it. Any receiver is going to pick up any and all signals, regardless of who sent them. So if your WiFi laptop and router are both transmitting, your WiFi tablet has to discern which is which, and ignore traffic that doesn't belong to them. So WiFi uses a range of frequencies, everything from 2,400 MHz to 2,490 MHz. Bluetooth also operates between 2,400 MHz to 2,483.5 MHz. Your microwave also makes a shit ton of noise on the WiFi band. So there's a problem, if both your WiFi device and your Bluetooth device both transmit at the same time, any receiver is going to hear both at the same time, and won't be able to discern what's what - it's all noise. It's like shining two flashlights on the wall, by looking at the wall, you can't tell what light comes from which flashlight. And when you have a transmission collision like that, both transmitters are going to wait a random period of time, and try again. That means your WiFi has to take turns. Each device can only transmit one at a time. The more devices that are in range, the more turn taking that has to be done - especially if the network is busy. That means your router, your laptop, your tablet, your TV, your XBox, your desktop, every other computer in your house that is WiFi enabled, **and your neighbors WiFi devices, if they're in range**. Remember, networks don't divide up the electromagnetic spectrum - there's only one. So even though you're not on your neighbor's WiFi, you're both still using the same frequency range. And the same goes with Bluetooth. Now Bluetooth incurs an additional problem. Bluetooth plays nice with other Bluetooth devices, they each take turns, but Bluetooth devices don't typically play nice with WiFi devices - as far as your Bluetooth device is concerned, that's just radio noise, and vice versa. Some Bluetooth and some WiFi devices are aware of the other protocol, and will take steps to play nice. Enter your microwave. It's just a source of noise. Whenever you heat up a hot-pocket while using the network, you just fuck over everything until the microwave is done. So to review, everything WiFi and Bluetooth that's in range is competing for air-time, it doesn't matter if your device is paired with that one or not, it doesn't matter if you're on the same network or not - the more devices within radio range, the more contention for air-time there is, the increased rate of cross-talk, the slower everyone goes. Some of these devices are aware of each other and attempt to play nice. There are still other devices, like some wireless home phones, hand held radios, baby monitors, etc, that also use these ranges and don't care. Infrared is very close to visible light. I think there might be some sort of technology that modulates the signal - just like public radio or WiFi, but typically your TV remote isn't nearly that sophisticated. It's a lot easier to direct infrared, since more things are opaque to it, and it will reflect or absorb off a lot more. The signal sent from your TV remote is usually a sequence of timed pulses and delays, almost like a Morse code. The range of commands coming off the remote is limited anyway, so this is fine. And Infrared is good for this purpose because you don't need broad or far range, polluting the electromagnetic spectrum for miles around because you want to change inputs."
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9e1ku7 | How do MRIs work? | Technology | explainlikeimfive | {
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"If my memory from years back serves me right, basically every subatomic particle has something called a spin. In case of MRI, we we observe protons, which constantly moving in a certain pattern. This movement is affected by it's general environment and position next to other protons. So in short, MRI sends out a magnetic wave of sort that hits the target and then bounces back. Depending on the arrangement of the protons in our target, the wave bounces back in a certain way. This returned wave is then interpreted and thus gives you the image that MRI produces.",
"Oh wow...a loaded subject. I will try. ANYONE PLEASE FEEL FREE TO CORRECT ME!!! & #x200B; An atom has a certain \"spin\" to it. It isn't actually a spin but rather angular momentum. For the purposes of this discussion, lets just say an atom spins to the left or right. Negative spin and positive spin. Don't think TOO deeply on this \"spin\" as a full explanation of nuclear spin is a lot to take in at one time and beyond my comfort level to be explaining. & #x200B; When an atom is forced to change it's spin (in this case by a strong electromagnet) the atom gives off a weak radio wave. In essence, an MRI machine detects those particular frequencies of the Hydrogen atom. We chose H because it is present in all human tissue (except the outer most layer of skin.) So...we tune into the radio frequency of H and we set the body in a large electromagnet (or we can pass that magnet around the body) turn the electromagnet on and off in various patterns. The H atoms give off radio wave s (because their nuclear spin reverses) each time it is influenced by the magnetic field being turned on and off. H is present in all tissues in the body but it is present in varying amounts. This is how we can distinguish the different tissues. This allows us to see things like a tumor (a tissue of a certain density) is inside of a person's liver (a tissue of a different density.) We can also see that an athlete's ACL ( a ligament, a tissue with a certain density) is all coiled up inside of the knee (a cavity) and that's NOT where an ACL should be nor is it the SHAPE an ACL should be. & #x200B; This strong electromagnet is a super conducting magnet and requires liquid Helium to keep the magnet at operating temperatures.",
"Everything is made of atoms. These atoms act like little bar magnets. Just like a compass bar magnet will rotate to align with the Earth's very large but weak magnetic field, when a human enters an MRI machine, our atomic bar magnets will rotate to align with the MRI machine's small but very strong magnetic field. Now the fun part, we can use radio waves to 'tip' these atomic bar magnets away from alignment, after which they realign - just like a compass after you shake it. However, this 'tipping' adds energy, which means, as the atomic bar magnets realign, they lose the energy they've gained. This energy is lost as a weak radio signal. So, we listen to that radio signal. However, because it's very weak, we have to 'tip and listen' many times and add the signals together to get a good image, which is why MRI imaging takes so long. Now, how do we make an image out of this? There's 2 things you have to remember: 1.) each atom gives off its own signal and 2.) the way that each atom realigns depends on its local environment (just like a compass will realign to Earth's magnetic field differently if there's another magnet nearby or not). Now, all the atoms are talking on the same radio frequency. So, the overall signal ends up blending the individual signals from all the atoms, like playing many notes on a piano at the same time to make a chord. Once we measure the 'chord', we know what 'notes' created the signal and because each note is dependent on the environment that created it, we know the environment for every note and can create an image."
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9e4h4l | Why do some offices have a PC connected to a virtual machine? | Technology | explainlikeimfive | {
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"For my firm, working from a virtual server means that updates are significantly easier. Having to update a program individually on 600+ computers would be an IT nightmare (for obvious security reasons, workers do not have the rights to install programs themselves). Working on a virtual machine allows IT to update much more quickly and smoothly.",
"When the user connects a VM is spun up using a copy of IT's VM template. IT can control the VM template, to patch it or whatever, without any pesky users. If something goes wrong, or some malware gets in the VM - poof it gets blown away when the user logs out and a new VM is made from the template when they log in again. This ends persistent malware.",
"We have a certain number of licenses for very expensive software that only exist on virtual machines. We are a global company so folks on one side of the world are using the very expensive software while the other side of the world sleeps and then vice versa. We don't have to buy a license for everyone in the company to have this software locally, just enough to support the folks working at any given time.",
"In my organization, we dealt with a large amount of sensitive data. SSNs, DOBs, Names, Addresses etc. We are laptop heavy and our rules stated that we were never allowed to work with that type of data on our local machine, and must be signed into a remote server. The idea behind that is to ensure that no sensitive material is stored on the actual machine in case of theft or breach. The remote server machine is much more secure. Additionally, it's two step credentialing. One log in for the local machine, a separate username and pw for the remote machine.",
"Because you can use **any** PC to connect to that **same** VM. You get the same desktop whether you are in your office, at home or at a remote worksite. If you spill coffee on your laptop, you don't have to worry about the last time you backed up, everything is backed up at once on the VM server. The *real* machines are locked up in a data center and babysat by experts, so you don't have to care so much about the other ones. You can also get away with giving everyone cheaper, less powerful hardware. There are security and support advantages as well. Laptop get stolen? Stupid employees put malware on their machines? Need to install a crucial security patch **right now**? The VM acts as a firewall, giving the company complete control of the important parts will leaving the employees with a lot of flexibility."
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9e5k5e | How comes that you can connect a smart bracelet and a pair of headphones by bluetooth to a phone but not two separate headphones? | Technology | explainlikeimfive | {
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"This is because the phones aren't designed to send audio to two different headsets. Just because it's technically possible doesn't mean the software has an option to let you do it. The vast majority of phone users only ever want to to connect one set of headphones so the phone makers don't bother to add the option to allow connections to more than one audio device."
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9e5ybd | what's preventing me from randomly guessing someone else's software product key, especially for physical copies of stuff? | Technology | explainlikeimfive | {
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"You're grossly underestimating the difficulty of guessing a key. Let's go with your 37^15 probably, since that's a fair approximation. Now let's assume that we can knock out all the \"most common\" keys that are \"too easy\". That gets rid of 10,000 or so possibilities. Yay. But that still leaves HUNDREDS of TRILLIONS of possible keys. Assuming you can make 10,000 guesses per SECOND, on average it will take you approximately 10,000 YEARS to get a single hit. That's what keeps you from randomly guessing a key, it's why Bitcoin wallets (and other forms of encryption for that matter) are so secure, etc. Statistically you have a significantly larger chance of guessing every number in the Powerball drawing ONE time over the course of your ENTIRE LIFE than you do of randomly guessing one out of 100,000 15-digit product keys.",
"You seem to understand the concept of brute force. I think the reason it's not more common is just the amount of work that entails for relatively little gain. It would be more lucrative to use that program and computational power to guess windows keys or something more valuable than the new CoD DLC or whatever. But it does happen there are a number of \"cracked\" games where you use a keygen program as part of the install process.",
"> but first of all I could bring that number down by avoiding using obvious or simple compinations (e.g. QWERTY) Let us assume there is some sort of filter on the keys to prevent curse words from showing up. Or maybe any word at all, in any language which uses those characters. A couple million combinations ruled out then. How many combinations can you get for a 15 character key that allows letters and numbers which are case-sensitive? That means each character can be one of 62 different possibilities and you are choosing 15 of them in a specific order. The result is that there are about 7.689 times 10 to the 26th power different options. That is 768900000000000000000000000 different options. Your couple million filter doesn't make it much easier. Let us assume you make a copy of the game for every living person on Earth? Still absurdly tiny in comparison to the different possible options."
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9e6xq1 | Why do computer screens (or TV screens) flicker when filming them with cameras | Technology | explainlikeimfive | {
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"The flicker is caused by two things: 1. A difference in the scanning frequency between the TV and the camera. 2. A difference in the way the phosphor dots are perceivedbetween the human eye and the camera's image sensor. Found this in an article a long time ago",
"To elaborate further. Your house hold electricity flickers 60 times per second. TV screens and monitors it depends on the device 50 times per second to 120 times per second. Video and film cameras recording depends on the device but typically range from 24 frames per second 30 frames per second. High for some applications. The flicker you see is usually caused by the 30 frame per second capture or a 60 frame per second display. Which makes it look like it is only partially moving. Try using your camera phone to capture your monitor screen to see this in action."
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9e91rm | how do closed captions on TV work? | Technology | explainlikeimfive | {
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"If the program is live, then it is likely that a real human is involved in giving you your captions. Some programs have a stenographer who types things out, while others use text to voice programs. For some broadcasts the BBC has a single person read back the commentary to a computer to improve the accuracy of the voice to text conversion. Others just have a person typing on a stenotype that feeds the captions. ESPN has one stenographer per person speaking on their sports reporting shows. Other programs simply feed the transcript to the TV captions.",
"It started with analog TV, during the delay when the beam was moving from the bottom back to the top, they sent the text to put on the screen. With digital TV, they mix a packet of text in with the packets of screen data. The TV writes the text on the screen."
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9e9dib | Why can two video files, both 1080p and 24 seconds long, have vastly different file sizes (64MB vs 250MB)? | Technology | explainlikeimfive | {
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"Video codecs(how the video is stored) use compression. For example if you have two videos and one can be described using 50 different colors but the other needs 250 one of the files will be larger. Similar with audio. The more complex the audio the bigger the file."
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9e9prj | Why do video games look differently from tv? | Technology | explainlikeimfive | {
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"Basically, you need to create the information to tell your TV, and while using cameras to just copy reality is easy, video games can't do that since they're making it all up. So you need computer artists to create life-like images, and getting artists to create those images and make them look completely realistic is very time consuming and expensive.",
"Imagine if you are have an orange. Someone asks you to make a picture of the orange in front of you. The tools they give you is a camera, crayons, and paper. Taking a picture would be similar to a tv show, whereas drawing with crayons would be similar to a video game.",
"A movie is the same every time you watch it. Imagine your typical movie, running for 2 hours with 24 frames per second. That’s 172800 frames for the entire movie. The movie is linear, you can only watch it as it was filmed. The camera and the actors are in the same place every time you watch it. Now imagine a video game where you can move the camera around, characters can move around. You could try to film every possible frame like you do with a movie. But you will soon find that there are so many possible frames that would need to be filmed that rendering them all in advance would take longer than the age of the universe for a standard 3D game. Even if you could somehow make all the possible frames in advance. You wouldn’t be able to store them all with all the harddrives in the universe. The solution is to create the frames as we need them. A computer or console will create the image, live. Computers can render extremely realistic images, but for a game to be playable the computer will need to create 30 frames per second at the very least. Images need to be simple enough that an (affordable) computer can render them in 1/30th of a second. For comparison, each individual frame of Toy Story took an average of 7 hours to be rendered by a computer. It obviously wouldnt be acceptable to wait that long between frames for games, so we make simpler images that faster for computers to create."
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9ed07c | why couldn't VR headsets correct for prescription glasses when rendering images so you wouldn't need to wear them with a headset. | Technology | explainlikeimfive | {
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"They can. But you need modified lenses, basically same strength as your regular prescription. I read that Oculus Go will offer this. Won't be cheap, I bet. If you wonder why the image can't be altered by the headset to be \"in focus,\" it doesn't work that way. You need to be able to focus on the screen, requiring appropriate lenses if your vision is poor. No amount of image manipulation can make incoming light focus properly on your retina to be detected."
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9edvke | How do the tick boxes that confirm you are not a robot work? | Technology | explainlikeimfive | {
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"Tracks your behaivour before clicking it. Open tabs, history, IP, computer stats and running programs. It is a lot more complex and demanding method than the original distorted text photo captcha but is much more convenient for human users.",
"So many incorrect answers here. Excerpt from 2016 paper [I'm not a human: Breaking the Google reCAPTCHA]( URL_1 ): > Once the user clicks in the checkbox, a request is sent to Google containing (i) the Referrer, (ii) the website’s sitekey (obtained when registering for reCaptcha), (iii) the cookie for URL_0 , and (iv) the information gen- erated by the widget’s browser checks (encrypted). The request is then analyzed by the advanced risk analysis system, which decides what type of captcha challenge will be presented to the user. > “No captcha reCaptcha” [Figure 1]. The new user-friendly version is designed to completely remove the difficulty of solving captchas. Upon clicking the checkbox in the widget, if the advanced risk analysis system consider the user have high reputation, the challenge will consider to be solved and no action required from the user. For the remainder of the paper, we will refer to this type of captcha as the checkbox captcha. EDIT: ELI5: When you click on \"I'm not a robot\" checkbox, various data gets sent to the server. If analysis system thinks you're not a robot, you passed the test; otherwise, you will be presented with image reCaptcha (for example: \"select all cars in the picture\") or a text reCaptcha (distorted text you need to input).",
"[edit: this answer is wrong, sorry :( ] One of the indicator is the way human being controlling mouse (for desktop). robot move the cursor very precise. Human? Wobbly. No matter how precise and careful you want it to, still wobbly wobbly. Edit: damn, wrong answer. I surely read about this somewhere.",
"I don't like how many of the other answers are somewhat on the right track but add additional misinformation. So first of all: No, the code that does the robot-detection \"magic\" is very limited in what it can read and it cannot access anything outside your current browser tab. And while it may use the timing of your clicking behaviour, this is only a small factor in the whole detection process. So how does it work? **tl;dr: It uses Google's tracking database that is normally used give you better ads.** Since the tick-box technology (called reCATPCHA) is actually provided by Google, what it can access is Google's information about you. More concretely, it can access the unique number that Google assigned you the first time you used any of their services, and all the tracking information that Google collected for this number afterwards. So essentially, it uses the same power that normally allows Google to personalize your ads to instead see if the profile it has about you matches what a typical human would do. So why can't a machine simply use Google's services for a bit and then look like a human? Because timing is also an important factor. Google probably tracked you over the course of weeks or months, so if a spammer wants to pass the tick-box, they would need to spend weeks in preparation, which makes it very unrealistic to do that for their purposes. It is also spam-proof in the sense that you can't make a \"good\" tracking profile once and then use it for a while: If the same number in Google's database solves too many boxes in a short period of time, their \"rating\" in human-ness gets reduced and they may have to solve an additional \"find the street signs\" check. You can test it out yourself: Find a site that uses the tick boxes, click them, reload the page and do it again. After 3-5 times in a row, you get an additional prompt. As a side-note: While this technology works very well, it also has a big caveat: It rewards you for being a good \"Google citizen\" by using their services and letting them track you. If you for example use your browser's private mode or even a VPN to be more anonymous, you are treated as potentially evil and have to solve a lot harder images. In addition, it allows Google to track you even more because they can also collect all the websites you solved their tick-box checks on, and use that again to personalize your ads. So while the technique makes use of Google's immense power over the internet, it also amplifies it even more, which in my opinion might be dangerous for all of us in the long term."
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9ee3bt | Why are solar panels blue instead of black if black reflects less light and can absorb more energy? | Technology | explainlikeimfive | {
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"The blue colour is largely due to an anti-reflective coating that helps improve the absorbing capacity and efficiency of the solar panels. Silicon is used in solar panels partly due to its ability to absorb most wavelengths of light and produce an electric charge, and partly because we can commercially produce near-perfect crystals of it at a relatively low price."
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9ef4x6 | what is the difference between a microscope and a telescope? I know micro is for small and tele is for far but what is the difference with magnification? | Technology | explainlikeimfive | {
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"The difference isn’t (just) magnification. If you look at magnification numbers, you’ll see that microscopes and telescopes overlap. The biggest difference, functionally, is something called focal distance. Focal distance is the distance from the lens that the object you’re focusing on should be when the device is in focus. Microscopes have very short focal distances, because the tiny things you’re focusing on are one centimeter or less from the lens. Telescopes have really long focal distances.",
"Telescopes are more about making things *brighter* than bigger. Magnification is a part of it, but magnifying something too dim to see doesn't help much. Microscopes are the reverse, they are all about magnification. The object still has to be bright enough to see, but it is a lot easier to shine a light on a bug than on a planet.",
"1. Microscopes are used, in general, to see very small objects but telescopes are used to see fairly big distant objects. 2. Telescopes use natural light at the focal point, but microscopes use artificial light. 3. The diameter of the lens, or aperture, is very different. It is very small for a microscope but very large for the telescope ."
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9efa1f | In early ancient history how did they tell whether diamonds (and other gemstones) were real? | Technology | explainlikeimfive | {
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"first up, weight. diamonds are very dense, so they should weigh more then glass. second up, volume. lets say you make a fake crown, filled with iron and not pure gold. the crown weighs exactly 1 kg. 1kg of gold has a certain volume, iron has another volume. so if you carefully place 1 kg of gold in a full bucket of water, some will spill out, that spilling is the volume of the gold. the shape doesnt matter. if that gold bar/crown is filled with only gold, it would displace just as much water as the kg of gold would. the first guy who figured this out yelled \"eureka\" and ran around naked trough town, but the sience is sound. the same trick can be applied to anything, a fake ruby/diamond would have another weight/volume ratio and that can be measured with a bucket of water.",
"No expert, but diamonds are some of the hardest materials on Earth. Their ability to scratch other materials could be tested."
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9egq9f | Why is compiled code impossible to access unless the uncompiled source code is available. Can’t game devs get a retail ROM and decompile the code from that? | Technology | explainlikeimfive | {
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"It's not that easy. Once it's been compiled, you can't decompile it. Think of the code like the recipe for a cookie. If you have that recipe, you can make that cookie any time you want. But if the cookie is baked, you can't just look at it and figure out the recipe. You'd have hints, sure, but the full recipe can't be figured out by looking at the end product. Compiling code is complicated, and the end result can't easily be reversed.",
"It isn't impossible, just very difficult. Source code isn't just the information needed to create the final executable, it contains a lot of information to help the developers know what the code does. If you were looking at code you'd never seen before and saw two variables called x_pos and y_pos, you'd instantly know you were talking about x and y coordinates on a screen. In the final code, they are not called x_pos and y_pos, they are called 0x21E8 and 0x21EA and you have to do a lot of detective work to figure out what is going one. Trying to decompile and executable and understand it is about as hard as writing code from scratch.",
"Yes and not. You can decompile the code but the result not the original code and is a lot harder to understand. There are decompilers but the output is not identical to the original code. It will do the same thing but a lot harder for humans to understand. The first problem is that name of variables and function might no longer exist so what was one perhaps a obvious code is not hard to read. The second part is the compiler optimize the code so they change it and order of things so it run fast on a computer. So the decompiled code is not how a human would write it. The last part is that text documentation is important parts of code and you often have text that describe what more the code does. The are a huge help when you try to undersand code that might be complex and they are no longer there.",
"Compare, say, the Lord of the Rings books, versus the films. You can naively think of the script for the film as being obtained by reading the book, then applying a number of changes. They're recognisably the same story, but you can't rebuild the books word-by-word from just watching the films, because the film format has to be more concise with dialogue than a book can afford to be, the film renders descriptions as actual images, and so on and so forth. Code compilation shares a lot of similarities with this — the final compiled binary is obtained by processing the human-readable source code, but you lose information in the process that you can't recover. In practice, you can often rebuild some chunks from the information you do have, or make an approximation from reasonable assumptions, but it's never quite the same thing. & #x200B;",
"[Decompilers]( URL_0 ) exist, but lots of information gets lost when compiling. For example, code comments and variable names can't be recovered. This makes it difficult to reverse engineer code from executables.",
"Decompiling is possible, but what you end up with is basically a 45000 piece puzzle with a black and white abstract art picture on it. It's annoying to reverse engineer and in case of a more complex program rewriting it from scratch to be a functional clone is much more cost and labour effective."
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9eibm3 | When developers update software (such as Mac OS or IOS etc), how do they implement the code? Do they have to start fresh or do they comb through the code adding in modifications where needed? | Technology | explainlikeimfive | {
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"You always have a code tree that you're working with. As you fix bugs/add features, you just add on to that code base. Once you're happy with your lack of bugs/plethora of features, you take a snapshot of that code and call that your release. You don't have to start from scratch every time.",
"They comb through the code and make modifications. Every app has a master source file, which is a long list of instructions that make like a story, written in a special programming language based on English. When developers are ready to release the app, they “save” it in a special format that turns it into a program (a process known as compiling). This new program file is a copy of the original that’s really compressed and the English is turned into machine language, so whenever they need to make an update they go back to the original script, make the changes, and save/export it again. BTW, The master source file is actually thousands of lines of code, sometimes millions, spread out into dozens of files, with images and sound files etc. Also, fun fact - Everyone in the world learns the same programming languages, so even if you are in China, France, Brazil, or Russia you program the exact same iOS in English as we do in the US."
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9eitx6 | How can Straight Talk use the same towers as Verizon and other top tier providers? | Technology | explainlikeimfive | {
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"Mobile phone companies own a lot of spectrum and towers, generally more than they can use (for now, things are growing). They sell their excess capacity to other providers, such as Straight Talk to use unused portions of their mobile phone networks. It's making $0 while not in use, so they'd rather sell it then have it generate no cash for them. Just about all large mobile phone companies do this to a fairly significant degree, and as such, its not uncommon for a company (such as a Straight Talk) to have deals with multiple providers in order to make sure their network is good enough, as often one single provider can't give them everything they need.",
"In addition to the fact that the big companies (Verizon, Att, etc) lease their towers they do so cheaper than it costs for their own customers, how could they get away with that you might ask? Often times it's because the leased carriers are given lower priority than the primary owner, so Straight talk might not get a fast internet download speed while at the same time a Verizon customer would. The second tier carriers can be a great deal but understand you may not get quite the same quality of service.",
"I work for a cell phone tower company. We own the towers and rent space on each one to several different carriers. Here’s a random tower from a google search. Generally each level of antennae you see belongs to a different carrier. URL_0",
"Towers are expensive to build, own, and maintain. So straight talk just leases space from other carriers that have already built.a tower. They dont have to worry about building them and the other carrier gets to recoup some funds",
"I think there are some anti-competition laws which force large telecoms into sharing their towers with smaller companies. Of course they have to pay to use them."
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9eivmf | How can my iPhone tell the difference between a lightning charging cable and a lightning earbud cable? Both of the plugs seem to have the exact same shape and pins. | Technology | explainlikeimfive | {
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"There's a very small IC inside the lightning connector that identifies the cable/cord/whatever. You can only get them if you're part of the \"Made for iPhone/iPod\" hardware developer program. That's why you'll get messages like \"This cable isn't certified\" if you use cheap Chinese knockoff lightning charging cables.",
"Because the cables INSIDE the cable are not connected the same, nor does the headphone adapter have voltage provided to it. The headphone adapter also has a Digital to analog converter built into it to convert the signal from digital to analog so you can hear it. Anyway - that's the ELI5 version."
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9emptt | Why does 24fps look appropriate for film but is too slow/choppy for any other form of media? | Technology | explainlikeimfive | {
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"When a real camera capture a frame, it capture 1/48th of a second worth of information. Moving objects will appear blurry, so a single frame will still give some sense of movement. Video games (for examples) don't do that. They simulate the world frame per frame. The world doesn't exists in between frames, there is no real movement: objects are basically teleported during the simulation. This means that when the game renders a frame it can only display the world as it is at this exact point in time, all information about movement is lost, it thus need to display at a higher framerate to appear as smooth as a real camera. Motion blur tries to circumvent this (by computing the difference between the current and last state). While it helps a bit, it is an approximation (like anything else in real-time CG) and isn't as good as true, physically correct, motion blur."
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9enbuk | Why are there no electric guitars with built in speakers or amplifiers | if there is, then why are they not that much common | Technology | explainlikeimfive | {
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"It's doable and they exist just not practical. There's only so much space on or in a guitar for hardware and electronics. Between stuff like the bridge and the pickups like the bridge and just wouldn't be able to fit a big or powerful speaker in one. Finding a good spot for the speaker is an issue as well. Having it project well and not be covered up by the person playing it is problematic and so is weight. Just a lot of cons and the pros don't come close to out weighing them. It makes a lot more sense on acoustic guitar since they already have a big hollow cavity designed to project their sound. You can easily add a speaker in there to amplify that effect but on an electric you'd have a hard time not sounding like crap coming through whatever they could fit fit on board.",
"My dad has an old electric guitar with a built-in speaker. I'd have to check on the brand and model though, but they do exist. Just doesn't seem very practical versus having an actual amp.",
"They've existed for decades now. However smaller amps typically don't have the same sound or versatility as a real amp/pedal system. In more recent years, the tone is now more or less the same as a real amp, but people have been using the traditional system for over 50 years now, so why change all of a sudden? For example if you're in a band, most places/houses that you would play at already have amps set up, so there's no real need for one that has a built in one. In addition, if you want a custom or specific guitar, it's easier to find it without build-in amps (and ones with built in amps are more expensive.)",
"My first guitar (~1987ish) was a Synsonics TERMINATOR. URL_0 Built in amp and a maybe 4\" speaker in the body. It sounded like complete shit, but whatever.",
"In addition to everything else everyone’s mentioned: the electric guitar is a lightweight, mobile instrument compared to its peers (keyboards and drums). Adding an amp would mean the guitarist would have to maintain their position and direction for the entire gig."
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9enoqp | When you call 999 or 911 how does it know to connect you to the correct local operator? | Technology | explainlikeimfive | {
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"From a landline - the origin of the call is known down to the address. So it's programmed to route correctly. From a cell phone - things are less certain. It goes by cell tower. However, cell towers can cover huge areas. If you're near a city boundary, your phone could connect to a tower that's technically in another city. (Imagine large cities butted up against suburbs where city boundaries are merely signs and streets). In this case, you can (and very often are) put through to the wrong city's emergency operator. That's why they ask the address of your emergency, to verify they can send help. If they can't, they transfer you to the correct city emergency operators. Source: police officer."
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9eoss0 | Why in videos (documentaries, training videos, etc) where someone is talking to the camera, they never look directly at or into the camera? | Technology | explainlikeimfive | {
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"During interviews a person next to the camera is asking questions so that’s who they answer to, even not in interviews they are usually directing they’re speech to a person near the camera, not only does it help to make them speak and feel more natural, it also comes off as more natural to the viewer. Imagine how it feels during a news broadcast when the anchor speaks to the lens, there is something palpable when a person is “broadcasting” to a camera as opposed to speaking to another person, the lack of interpersonal connection is easy to notice and would make a documentary much less engaging",
"Because in most documentaries etc they are talking ABOUT something. If the person looks straight into the lens then they end up talking DIRECTLY TO the audience. That's useful if you want the speaker to have more power/intensity (or alternatively in education videos if you want the speaker to have an air of instructional authority) but it can be distracting. For examplke, if someone is explaining why whales migrate then you don't need the audience to feel like the person is overly intense and/or instructing them -- straight into the lens (and thus looking straight at the viewer) can give that impression. Essentially the off angle perspective helps us \"listen in\" but since it's close enough to straight on we also don't feel like we're peeping toms (imagine if the whole interview was shot from the side for example, you'd feel like you were intruding)",
"Meet Rick Mercer. His Canadian rants while staring into the camera while walking down an ally way are a bit of a trademark for him. URL_0"
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9eqgd0 | How does task manager close out your window so fast when no other method of closing out a window works? | Technology | explainlikeimfive | {
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"Usually, the responsibility for drawing, resizing the application's window (and everything in it) is the job of the application. Usually, its good operating system behaviour to tell each application to close and let the application take care of that... so it can save files etc.. If the main loop of the application is hung, its no longer responding to the Windows operating system when you click the Task bar or click the [x] in the upper right. Windows is saying \"Hey, user told you to close. Do whatever it is that you close and stop drawing your window and its contents.\" and the application is saying \"lalalalalalalalala I'm not listening to you I'm stuck in this loop lalalalalalalalalal\". Task Manager > End Process however is akin to Windows sneaking up behind the application going \"lalalalalalal\" over in the corner and smashing it over the head unconcious with a shovel. Then dragging it away to its room. Any toys it was playing with (data) get dropped where it is and _maybe_ when it wakes up again it might be able to find them. Maybe not.",
"Hopefully ELI5 for you **Closing the application via the application**: The application is a 5 year old, that you told to get out of the room. If the 5 year old is paying attention to you, they might leave, and depending on how well behaved that 5 year old is, the 5 year old might pick up some or all of the things that 5 year old left in there. The 5 year old may not pay attention for a while because he/she is busy, so that may take a while. If not listening at all, the 5 year old may never leave. **Closing via the task manager**: You (the operating system) pick up the 5 year old and remove him/her from the room immediately. Then you just throw all the crap in the room in a bag, as fast as possible, and toss it.",
"When you close a window normally, it is processed in a way that allows an application to delay closing that window until it decides that the window should be closed. So if you're for example, working on a document and accidentally hit the X, the application has a chance to ask you if you'd like to save before closing, instead of just blindly closing on you. Unfortunately if an application is completely stalled out, it's not going to be processing the logic required to actually safely close itself down. When you close a task in the task manager, you're bypassing this method of ending the application."
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9er744 | What does resampling an image in a computer mean? How different is to simply resize it? | Technology | explainlikeimfive | {
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"Resizing does not affect the amount of pixels - it just tells other applications how large the image is supposed to be (such as printing). It has no effect until you print the image. Resampling changes the amount of pixels in the image, therefore affecting the image quality."
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9erjws | Why do screens do a weird colour thing when you push hard enough | Technology | explainlikeimfive | {
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"These are \"LCD\" screens, which stands for liquid crystal display. Light waves come from a source behind the screen and go through a layer of liquid: when exposed to electricity, the liquid changes how the light waves wave (\"polarization\"). The light then goes through a filter that cuts out one kind of polarization, then a filter that gives it color, before it goes out to your eyes. Squishing the screen makes the liquid layer thinner, so it can't do its job as well, which changes the brightness and color of the screen."
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9ew8ty | What exactly is "hacking" and is it like how it is in the movies? | I'm talking about those scenes in movies where people are "hacking" into websites and accounts within a matter of seconds. Is it really like that in real life? Can you even get to a point where you're so good at "hacking" that you're able to easily access accounts or is it just Hollywood nonsense. | Technology | explainlikeimfive | {
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"Imagine you see a building. It’s one of those company buildings that has automatic doors, but these automatic doors only open from the inside so people can walk out. You think this is interesting, and you want to know how it works. It could work a couple of ways, it could have a weight sensor, or it could have a motion sensor. You don’t see a floor pad, so it couldn’t be a weight sensor. You notice that there’s a gap in between the doors and you happen to have a can of compressed air that has a straw that will fit inside the gap. You figure “if it’s a motion sensor, it should sense the dust the compressed air moves” so you stick the straw through the gap and spray air. The door opens. This is hacking. Typically you think of hacking as computer hacking, but hacking really is just getting things to do something they weren’t intended to do. Computer hacking is typically seeing a system, investigating how it works, and seeing if you can get it to do something it wasn’t intended to do Edit: Thank you kind stranger for the gold!",
"Nobody types that fast. It's mostly reading, studying, then programming attempted attacks. Sometimes it's finding tools and letting them find vulnerabilities. Sometimes it's just outwitting a person on the phone to get Information (social hack). Other times you may disassemble code to find clever security mechanisms and ways around them. Depends on your objectives. Nobody is typing a million keystrokes per second to break into a bank or the defense department or Hillary's email.",
"The most realistic depiction of what hacking looks like that I have seen on tv is the show mr. robot, even then it’s a little far fetched. Hacking is a lot like breaking into a building. It’s a matter of finding a weakness and getting in. The most common form of hacking is essentially the same as stealing the keys. It’s easiest to go in through the front door with the password. From there it gets more complicated and technical, but the basic premise is the same regardless. Find a bug or security loophole and use it to gain access or force the target to run some code that will give you access.",
"In a very few cases, you just use a well-known attack that the target is vulnerable to (meaning their admin only got the site up and was then fired and they don't have anyone to do updates). More likely that a hacker did all the hacking in advance, and now he can login to whatever he needs within seconds. In very VERY rare cases a highly professional hacker finds a way to hack something before the developer does (and before any other hacker reports it to get a bounty) and this is called a 0-day. In this case, the hacker could create a tool for himself to use the hack within seconds, until either the developer finds and fixes it or the target changes to a newer version where is no longer works.",
"Think about it: if hacking websites were really as easy as in the movies, wouldn't every website in the world get hacked every day? We wouldn't even be able to have this conversation on reddit right now because someone would have hacked it. Security vulnerabilities pop up here and there. Clever people can occasionally find vulnerabilities that no one else has found, but it can take weeks or months or even years to discover and develop an exploit. And as soon as the exploit is discovered, it'll be patched up pretty quickly and people around the world will update their software to close the vulnerability. Of course sometimes a website administrator is lax in updating. This is particularly true for obscure and/or abandoned websites. Some hackers (\"script kiddies\") will trawl swaths of websites looking for one that hasn't updated its software in a while and will be vulnerable to already-known exploits. Honestly, these days, most of the \"hacking\" that happens is social engineering. Tricking someone into revealing their mother's maiden name and birth date, sending fraudulent emails (\"phishing\"), phoning up a company and pretending to be a real account owner, etc. That's obviously very hit-and-miss, though, as most people aren't *completely* gullible.",
"I understand that the misuse of the term hacker has become so widespread that the definition has changed, but... A hacker is someone who likes to dissect and tinker with other people's creations. In computer programming, this usually means modifying and extending other people's programs. A cracker, aka security cracker, is someone who finds security flaws and exploits them. There is sometimes a significant overlap, thus the confusion. Neither are even remotely like the movies. Yes, there are times where I can write a Greasemonkey script in 5 minutes to significantly improve a web site's usability, but for the most part, it takes a serious amount of work to learn the intricacies of any given system and even more to bend those details to your will.",
"Believe it or not, the old movie \"Hackers\" came close to being like real world hacking. Dumpster dive for usernames to the company network along with insecure passwords. Social engineer a way in, often using usernames found while dumpster diving. Keylog when you can. Hacking is a slow, boring to watch process right up to the very end. Then it is still boring to an outsider. The closest thing to Hollywood hacking is something called \"fuzzing.\" Fuzzing is an attempt to break a system by probing it with every input you can think of. Press all the buttons, connect on all the ports, send malformed connection requests. Keep throwing more and more ridiculous bullshit at a computer before it gives up and does something it wasn't supposed to do. Then do it again. Then exploit that. Fuzzing doesn't always work, and when it does it doesn't always do something useful. Then again an angle grinder isn't always useful either. The vast majority of hacking follows a simple exploit stack. Exploit the people. Exploit the code neglected by the people. Bypass the security if no one can be exploited. Finally attempt to crack the security. Why unlock a gate if there is a hole in the fence next to it?",
"Hacking is nothing like it is in the movies. It's definitely not like this: [ URL_0 ]( URL_0 ) & #x200B; Instead you got multiple ways of \"hacking\". The one most closely related to the movies is what are called script kiddies. Essentially the \"real\" hackers, the ones who find the vulnerabilities create a tool or script that will do that one exploit. It'll probably be in command line like in the movies but it won't have vertical scrolling text (matrix like) and it's unlikely to spit out thousands of lines per second. In any case, the script kiddies just run that and it may or may not work if patched. & #x200B; The actual hackers are not portrayed correctly in any movie I've seen. What actual hacking comes down to is reading source code to find some potential oversight and then trying to get your code to exploit it. This takes hours, days, weeks or even months of just testing trying to make it work. You also have people that do \"packet sniffing\" or \"man in the middle\" attacks on networks which is reading the data being sent/received. If it's encrypted then chances are that's not even a plausible method since breaking that would take a really long time. & #x200B; Breaking into websites/accounts is also not properly shown. Good websites today will take multiple steps to stop what you see in the movies: 1) Rate limiting the login. If you fail the login X times in Y minutes you get blocked or slowed down. 2) Rate limiting logins against specific accounts. If you keep failing a login to the same account they can prevent logins to that account. 3) 2 factor authentication. This is much newer and requires a secondary device to authorize the login. This could be your phone with an app, receiving an SMS message to your phone or even a USB device. 4) Captcha. Everyone knows what this is. If the failed login rate goes over the highest expected normal failure rate they can captcha the login form and that will defeat most bots. & #x200B; There is also the attack on passwords and encryption which is (kind of) not accurate. Passwords should be stored in a \"hashed\" format. Essentially it will take your password, put it through the \"hashing algorithm\" and it will spit out a string (just a lot of letters/numbers) that is equal to your password. For example, the word \"password\" using the best hashing algorithm will spit out \"45d7ac72e76f242b20b77b9bf9bf9d5915894e669a24e6c6\". That is now your password stored in the database. The reason is so if the database is stolen they cannot see your password in \"plain text\" and will have to work to turn it back into your actual password. So how is this not accurate depicted in the movies? With a proper hashing algorithm, it will take around 2400x the length of the universe to break a single good password. Good websites will make hashing take 200-1000 miliseconds. Even the best tools to break passwords and the best hardware will top out at around 6000 password guesses per second. There are worse schemes which can be broken at around 2.5 billion per second but that's less likely today. & #x200B; Encryption is also another entirely different thing (your password should never be encrypted.) Breaking encryption is also like hashing in that it will take hundreds of years at best to break a single text much less files. & #x200B; \\-- & #x200B; In short, hacking is not fast. There aren't a bunch of popups. There's rarely a progress bar. Intead it's just a methodical and focused attempt to try to make a single piece of code not work entirely as expected.",
"Easiest way to see it is Lockheed Martin's Cyber Kill Chain. 7 steps to it: 1. Reconnaissance - Longest part of the process, and it's where you just spend time collecting info on the target. Email addresses, IP addresses, system information, employee info etc. 2. Weaponization - After you find a vulnerable application on a target system (for example, a certain version of Windows which hasn't been updated to be more secure), you exploit that weakness by creating a malicious program. 3. Delivery - Deliver that program via either spam emails, compromised websites, USB, etc. 4. Exploitation - Exploit the vulnerability so you can run your program on the target system. 5. Installation - Install malware on the target. 6. Command and Control - Communicate with the program (it'll have a backdoor so it can call out to your server) so you can control the target device it's installed on. 7. Action On Objectives - Now you're in control of the target, carry out your goal by stealing info or otherwise comprising it. Hope that helps, if you watch Mr Robot the reason it is so accurate is because they spend a lot of time on these individual steps, in particular the Recon stage. Movies that don't get this right tend to skip past recon and just \"type really fast\"...",
"Let's say you want to brake into a house. If you are an alarm installer, you'd know that the second story windows don't have sensors on them. If you work in tree removal you'd know how to climb trees very easily. If you were a door to door sales man, you'd know how to talk to people and get information or of them. If you gather all these skills, you'd find out that the owners of the house are on vacation, and so you can climb the tree in the backyard to reach the second story window. Or you can find out that they leave a spare key under the mat. Hacking is similar, the more you know about programming, the more weaknesses and lazy habits of programmers you'd know. You can exploit those weakness to gain access. Or you can just find a password by social engineering or just guessing. Some of the resent hacking attacks were successful because employees used passwords like Password123, or LastName1",
"I have very rarely seen hacking done right in movies (Sneakers comes to mind as one that got it mostly right). If you want something accurate to see, Mr. Robot is pretty damn near perfect, as I and others in the information (in)security field helped contribute to it. That said, when you have everything ready, it can go like the movies. When demonstrating a security vulnerability in a piece of financial software, after pre-writing and testing my proof-of-concept attack, it took me around 2 minutes to break into a corporate bank account (just tweaking my code based on my already done work) and transfer 1.3m euro between accounts and cover it up. Made a nice demo!",
"[Here is]( URL_0 ) an amusing comic that explains it pretty well. If you want to see what an accurate depiction of hacking looks like watch mr.robot. Its also a really great show. In simplest terms hacking is just a cool word for “finding and exploiting a security flaw”. Security flaws dont NEED to be found on the actual system youre trying to hack. A security flaw could just be a person who screws up at their job like everyone else does. Human error is normal and hackers use it to their advantage. So that could be bob the accountant has a terrible memory so he writes his passwords on a sticky note that he leaves under his keyboard. Thats a security flaw. Or somehow getting jenny from legal to tell you her mothers maiden name. Or you can convince Olly from sales to check out your “Rap mixtape CD” in his work computer and he does it because olly is a gullible idiot.",
"Watch the movie WarGames, it actually has some pretty grounded depictions of what hacking looked like (in the 80s at least). Getting access to where careless people wrote down passwords, social engineering (Just calling and asking what the password is, works more often than you think). Testing connections one after another until you get a response. But modern hacking is less interesting than that. Mostly it involves running scripts that probe security programs for vulnerabilities, either to improve security by informing the owner or to steal data by exploiting it. Any time you here that 200,000 credit cards have been compromised that's what happened. Someone got in and got access to data they shouldn't have.",
"There are so many different forms of hacking, and a large and relatively simple part is social engineering. This is linked to using social media accounts etc to find usable information on you, that can then be leveraged to gain further information/access to accounts. For example with enough info someone could call your credit card company pretending to be you etc. This is why identity theft is very worrisome, because you have to prove someone with all your information wasn't you. Unfortunately how most movies demonstrate it is like this: [ URL_0 ]( URL_0 ) Then there's stuff like Network penetration, SQL injection etc. & #x200B;",
"Honestly if hacking were portrayed as it usually is in real life people qould be a lot smarter online. 9 times out of 10 hackers gain access to something they shouldnt through plain old communication. Example: hacker sends phishing email to wvery address in a company, something along the lines of \"click here to update your password\" Unwitting middle manager clicks and inputs his information. Hacker now has access to anything said individual has, and can potentially use that to target (spear phish) more higher level personnel. If \"company hacked millions breached\" as a headline was replaced with \"man tricks worker into giving his password away\" things seem less magical. While there ARE in fact vulnerabilites that are exploitable in systems and securities, they are becoming more and more difficult to exploit, and tactics like phishing or simple social contact can often yeild better results far easier. TLDR: hackers are usually just guessing or stealing a password",
"Back in my day, if you knew how to code you were considered a hacker; if you used the tools hackers wrote, you were a script kiddie. But it wasn’t limited to just that - everyone in my group had a special set of skills, apart from being coders. Also - here is an old school “manifesto” - it fired me up as a kid. URL_0 ==Phrack Inc.== Volume One, Issue 7, Phile 3 of 10 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= The following was written shortly after my arrest... \\/\\The Conscience of a Hacker/\\/ by +++The Mentor+++ Written on January 8, 1986 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Another one got caught today, it's all over the papers. \"Teenager Arrested in Computer Crime Scandal\", \"Hacker Arrested after Bank Tampering\"... Damn kids. They're all alike. But did you, in your three-piece psychology and 1950's technobrain, ever take a look behind the eyes of the hacker? Did you ever wonder what made him tick, what forces shaped him, what may have molded him? I am a hacker, enter my world... Mine is a world that begins with school... I'm smarter than most of the other kids, this crap they teach us bores me... Damn underachiever. They're all alike. I'm in junior high or high school. I've listened to teachers explain for the fifteenth time how to reduce a fraction. I understand it. \"No, Ms. Smith, I didn't show my work. I did it in my head...\" Damn kid. Probably copied it. They're all alike. I made a discovery today. I found a computer. Wait a second, this is cool. It does what I want it to. If it makes a mistake, it's because I screwed it up. Not because it doesn't like me... Or feels threatened by me... Or thinks I'm a smart ass... Or doesn't like teaching and shouldn't be here... Damn kid. All he does is play games. They're all alike. And then it happened... a door opened to a world... rushing through the phone line like heroin through an addict's veins, an electronic pulse is sent out, a refuge from the day-to-day incompetencies is sought... a board is found. \"This is it... this is where I belong...\" I know everyone here... even if I've never met them, never talked to them, may never hear from them again... I know you all... Damn kid. Tying up the phone line again. They're all alike... You bet your ass we're all alike... we've been spoon-fed baby food at school when we hungered for steak... the bits of meat that you did let slip through were pre-chewed and tasteless. We've been dominated by sadists, or ignored by the apathetic. The few that had something to teach found us will- ing pupils, but those few are like drops of water in the desert. This is our world now... the world of the electron and the switch, the beauty of the baud. We make use of a service already existing without paying for what could be dirt-cheap if it wasn't run by profiteering gluttons, and you call us criminals. We explore... and you call us criminals. We seek after knowledge... and you call us criminals. We exist without skin color, without nationality, without religious bias... and you call us criminals. You build atomic bombs, you wage wars, you murder, cheat, and lie to us and try to make us believe it's for our own good, yet we're the criminals. Yes, I am a criminal. My crime is that of curiosity. My crime is that of judging people by what they say and think, not what they look like. My crime is that of outsmarting you, something that you will never forgive me for. I am a hacker, and this is my manifesto. You may stop this individual, but you can't stop us all... after all, we're all alike. +++The Mentor+++",
"Hacking is actually pattern recognition, you find a particular pattern and you know how it can be exploited (bend to your will). Mr. Robot (Netflix) is pretty close to what hacking is. Machines rarely make mistakes the large part of hacking in this context is getting into an unpatched system which is due to human error, social engineering, again human error etc. Yes you get good with pattern recognition as you practice more and more.",
"The terms got mixed somewhere. Originally hackers are not bad guys. Those are crackers. Hackers just hack the code to solve problems or find the exploits in security but not act maliciously.",
"It's like walking up to a house you're trying to break into. First thing you'd do is check the doors to see if they're unlocked, then check the windows, after that look around for a hidden key before moving onto more forceful modes of entry. Hacking is just trying to break into a computer system or network by looking for a possible open door or hole somewhere.",
"It's almost never accurate. Actual hacking, to the casual observer, would appear no different from most software development or coding. The key difference is that the code they are working with is intended to interact with and exploit security gaps in other code. To have several screens with scrolling code or random text would just be distracting. You have to carefully read the code text and then add to it or change it, which requires some concentration, just like doing a math problem for homework, so the screens would be quite still. Another reason hacking is always unrealistic in movies is because very often, the show can't use a real world OS because of (presumably) a reluctance to grapple with the implications of portraying the use of commercial products in this light on-screen. Or just a reluctance to secure the rights, if any. Also, the director has to portray the message \"Something happened in the computer\" very quickly to the audience without needing to worry about whether they are familiar with specific programs and code. So the shows use a mock-up, often jokingly referred to as \"Hollywood OS\", which is designed to portray quickly whatever the director is trying to tell the audience without taking up too much screen time. Of course, sometimes there's some paid sponsorship, as companies do like product placement, so often there will be computers of specific brands appearing in shows. The use of Apple computers in Independence Day, for example (also a completely unrealistic portrayal of hacking). One notable exception is 1999's film, \"The Matrix\", at the beginning of which, one of the protagonists is seen using nmap, which is a linux tool for performing network diagnosis. The implication is that the character, Trinity, is searching for open ports on a remote system (although nmap is not specifically a hacking tool any more than a screwdriver is a tool for stealing cars). This is almost an easter egg, because only people reasonably familiar with Linux and Unix style operating systems would be familiar with the tool, and for a blockbuster film seen by millions, that's a minority. At least, in this case, the directors weren't completely wrong in portraying part of an act that might be hacking in that scene.",
"it really depends, fundamentally, most hacking relies on things called 'exploits', this can be any of a number of things. One common approach is an idea known as social engineering, basically, this is the process of convincing someone to just straight up give you access to something, for example, tricking a technician into resetting a password, by pretending to be someone else, or by creating a fake login page for a web service (say facebook or paypal), but which you actually control, so when they try to log in, you get a copy of their login details (this in particular is known as phishing). Other exploits rely on some technical detail or another of a system, a fairly simple example is the old-school art of Phreaking, phones used to use a system known as 'in band signaling', that is, when you did something with a phone, it generated an audible tone, which the exchange hardware listened for, and did things with, by figuring out these tones, it was possible to manipulate the phone system to do things like getting free calls. In the world of computers, the same basic principles applied, but things could be much more complicated. A few of the 'common' attacks that crop up reasonably often are things like 'SQL injection', which is basically where you have a website or application powered by a database, these databases often use a standardized language known as SQL, and if you can figure out a way to interact with the database, you can basically get any data held in there (for example, user email addresses, payment details etc..). This used to be a relatively common attack, which could be as simple as posting a comment on a website, or appending the query to a URL, these days it's a bit more difficult in general, as content management systems do more work to check what's actually being sent to the database, or outright refuse to execute anything that's not already stored in the database. Another old school class of attack are 'buffer overflows', where you try to trick a program into running some code that you wrote, by using a special file that is designed to make an already running program store something outside of its normal memory bounds, or to read something that you have placed in its memory bounds, and execute it. Attacks are usually found by security researchers, who largely fall into one of three major categories, 'white hat' hackers (also known as security researchers) are often considered to be 'legitimate', they will usually find exploits or attacks and report them to a relevant body (either the programmers of the application, or a disclosure bulletin site), and will usually give an amount of time for the exploit to be fixed before they make the details public (its important that they are eventually made public, so they can be studied and analysed, so the industry as a whole can examine the exploit and learn from it. They may be employees of a developer, a consultant, or an independent entity, and they are often paid for finding exploits through a 'bug bounty' program. Next up are 'black hat' hackers, who will find exploits and either use them, or sell them to other would be attackers. Third, there are 'grey hats', who are kind of in between. These days, there are a bunch of systems designed to scan systems for known vulnerabilities, such as the metasploit framework. As for how long things take, in some cases, it will take a very long time, with careful observation to gain access to a system. Gaining physical access to a system is generally considered to be game over, and in the right conditions, a remote hack can be extremely fast. As an example, say you had a website running on wordpress, but its an older version, it may be possible to find a known exploit for that version, using a database like URL_0 and if theres a known exploit that gets what you need, its potentually an extremely quick process. Usually you are either aiming for access to the database that sits under the website, or the shell of the underlying operating system of the server. So for an example of an attack... Say a local gym has a website, which runs on a slightly old version of a content management system (such as joomla, or wordpress, basically, a premade system that runs a dynamic website and allows them to add content to it) with a known exploit, I can use that exploit to get direct access to their database, which happens to contain your name, address and date of birth, I can grab those details and apply for credit cards in your name, and run up huge bills using them until you notice that suddenly debt collectors are writing to you asking where their money is! another example would be giving an employee of a company a USB stick, with some hidden executable on it which sits on the computer and logs everything they do, eventually they will probably put in their credentials for a social media site, webmail portal or something like that, and now I have access to that system, and its a reasonable guess that they use the same password for other systems too. Another attack might involve putting a device in a coffee shop that you know a target regularly goes to and works on his laptop, you set the wifi on the device to log all the wifi traffic, and then send a copy of that log over a mobile internet connection to your email, once you think the target has been in and used their laptop, you go through the logs and look for any connections (say a VPN, or an email sign in) that might have credentials on the targets network, which you can now attempt to use (or to crack the encryption on the password etc..) and use yourself."
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9ex942 | All the steps a washing machine uses to wash clothes | Technology | explainlikeimfive | {
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"Let's not get carried away with the different rotations, even though they are chosen to agitate the clothes depending on their durability and wear profiles. Most cycles vary the heat applied. This matters. The temperature is usually governed by either drawing already heated water, or cold water that must be heated. In both cases there is an energy cost that tends to be high, and I assume, higher than that of the motor run time. So use a detergent that is OK with low or no heat, adjust the cycle profile to turn off using heated water in most of your washes, to both save energy and reduce pollution. Only use heat if the clothes are very dirty, and have an oil/grease component that you think won't be addressed by the enzymes etc. in the powder/liquid. Beyond this, if it's sunny or dry and you have time, reduce the spin cycle to a slower setting, again, in the interests of conserving energy and reducing pollution. Lastly, water is precious, tap water is commonly processed to be drinkable, so reduce the number of wash/rinse cycles. just push buttons for this, or get a new machine that allows you to do. Refer to the manual to determine how many wash/rinse cycles each different setting has. Once you work it all out, simplify it by teaching your family members to select one combination of settings for a normal full load (clothes that are mostly clean, work for < 8 hours by people who don't sweat/work), and a different combination for a very dirty/oily load. Imagine you are on a spaceship... spaceship earth. (research BFI and Mr. Fuller) Wash, without going overboard, as if your spaceship had limited resources, and the true cost was 10x that which you had to pay for. Finally, & #x200B; Consider your poor clothes. If they are smashed against a brick 1000 times, they will last 1/5th the time as if they are smashed against a brick only 200 times. & #x200B; I've not made clothes, because I can't, so I respect them. I try not smash them more times than I have to during cleaning, even if it's a machine smashing them and not my mum using a rock in a river. :)"
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9exkjt | Why will a perfectly good ballpoint pen not work when signing a receipt on a hard surface but if you put just one piece of paper under it, the pen writes just fine? | Technology | explainlikeimfive | {
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"The ball has to be able to roll in order to transfer ink to the paper. If it just slides across the hard surface without turning the little bit of ink already on the outside rubs off and that's all you'll get. Adding a scrap of paper under whatever you're writing on adds a tiny bit of extra give to the surface, increasing the chances that the ball starts turning properly",
"These machines use a single sheet of very smooth paper, and when on a hard surface it does not curl around the ball point as you write, leaving a very small contact area which does not offer enough resistance to turn the ball. As you add more paper, the pressure of the ball point will cause the paper to slightly curl around the ball(and leaving an impression on the pages below), causing more surface area and therefore more resistance which causes the ball to roll and transfer the ink from inside the pen to the paper."
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9ey3qq | Why do hatchbacks come with rear wipers as standard equipment while sedans generally don't have them as an option? | Technology | explainlikeimfive | {
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"When you’re driving there is sort of a swirling area of low pressure air that will pull dirt and road grime up towards the back of the car. This has a tendency to coat the back of the vehicle and obscure a hatchbacks rear windows. On a sedan that has a trunk, the rear window is not in this swirling dirt area and will remain much cleaner. When it comes to rain, the airflow across the rear window of a sedan will keep it somewhat clear. This does not work as well on a hatchback (or van or SUV for that matter). On some flat backed vehicles you will see what might look like a spoiler that is pointing in the wrong direction. This is meant to scoop clean air from the top of the vehicle and blow it across the back window. Hopefully keeping it a little cleaner."
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9ezp68 | Why does a 2 hour long video on YouTube loads up a lot faster than any other movie streaming websites? | I am trying to watch a 2 hour long movie and it buffers every 2 seconds. My internet is fine, and when I click a 2 hour long video on youtube I can skip it freely without having to buffer. Is there a reason to this, or is YouTube just a lot faster than other streaming websites? | Technology | explainlikeimfive | {
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"The length of the movie has nothing to do with it really; it's about caching. YouTube/Google have caching servers all over the world, so when you select the video to watch, YouTube transfers the entire movie over a very fast dedicated network to a server that's physically close to you with minimal network hops -- usually either just outside or just inside your ISP's local network hub. This means that when your browser requests new chunks of the video, there's very little limiting its transfer from the local server to your device. Other services often don't have the same dedicated high speed network to locally cache the video, sometimes don't even have a local cache, and may also have a less optimized algorithm for grabbing and transferring the video in the first place. On top of this, there's the issue of buffering the video on your side; everyone has their own video player; YouTube has a very simple player that just receives MPv4 video and passes it off to the AVC/AVHC decoder on your graphics card. This means it's lightning quick. Other video streaming services either try to do it all in software (meaning decoding is MUCH slower) and/or they have the stream wrapped in DRM so that it needs to be decoded in software and THEN decoded again in software/hardware before being displayed on-screen. Does that answer your question?"
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9f19c3 | When sending an email or other types of digital communication what speed does the data travel at? | Technology | explainlikeimfive | {
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"The speed of light in the fiber optic cables, or the speed of the transfer rate of electrons in the electrical wire. Most long distance communications (such as between servers or overseas are over fiber optics, because it’s faster and cheaper. Short distance communications, such as through HDMI cables, are via electrons."
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9f3dzl | 32 bit processor vs 64 bit processor | Technology | explainlikeimfive | {
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"When we talk about number of bits in a piece of computer hardware, it's like the number of digits for the base-10 numbers we're used to. A computer uses numbers for doing 2 main things - for holding values and doing calculations, and also for keeping addresses of where things are. A 32 bit number can tell you where something is in 4GB of RAM or storage, while a 64 bit number can tell you where something is in 16 billion GB of RAM or storage. Keeping track of where stuff is and finding it is called \"addressing\". Both being able to do calculations with bigger (or more accurate) numbers without special tricks, and the ability to address larger RAM and storage make computers faster and more useful.",
"Bits are just how computers express things. It's their sense of words. A FANTASTIC comparison would be to think of using Twitter. You have a 140 character limit, so sometimes you can't express something as vividly as you want. It's sometimes concise. That's 32 bit. When they increased it to 280 characters? That's a 64 bit upgrade",
"Super ELI5 You know mail has zip codes? Like 01209? And that says what area the mail is going to, right? But then you have the long zip codes. Like 85337-4917. And that's let's them have more \"areas\" in one \"line\", because the number is bigger, right? It's kinda the same. 64 bit can cover more areas (in memory) using the same number of \"lines\" (called a \"register\")",
"Overly simplified: A 32-bit processor is able to deal with 32-bits of information per clock cycle. That's 32 individual 1 or 0 digits for every 'Hertz' the processor is rated for, so a 1 GHz CPU would theoretically be able to do that 1 billion times per second. A 64-bit processor can squeeze twice as much data into each clock cycle by attaching a bigger hose. This works for some applications but not necessarily for all of them. Imagine you woke up tomorrow morning and suddenly received all information twice as fast. You'd kill it at multitasking and math homework but a desk job would suddenly (lol) be a nightmare.",
"It's simply extending the effective storage space it can accurately point to without errors. In more simplified terms, you have two hands with 5 digits. Imagine 32 bit is like your first hand. You can easily count to 5 on it... you can even use some clever Binary counting to reach 32 on a single hand. But... there's no 6th finger to count on, and this is an absolute limit for counting with the first hand. This is fine as long as 5 fingers is plenty, but you start finding yourself needing 6 frequently. While you can store 5 digits and do some slower longer counting to still count these bigger numbers. It's very cumbersome and slow. So we start using both hands to increase our maximum from 5 finger to 10. In binary this jumps us from 32 to 1024. A huge benefit for computer counting compared to the simplified fingers. However, the point is similar, we can quickly show 8 fingers all at once, instead of clumsily trying to show 5 + 3 on one hand. Similarly, 64 bit CPUs can efficiently work with larger numbers."
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9f4lrt | What do people learn as computer science majors? | Technology | explainlikeimfive | {
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"Mainly they learn about programming. It may include topics such as: * Use and comparisons between various programming languages * Use and comparisons between various computing platforms * Study of algorithms to make programs more efficient in terms of speed, memory, power usage, etc. * Study of theory relating to computers * Study of key computer components, including CPUs, operating systems, memory management, etc. As a field, computer science tends to lean toward the theoretical end of things, studying current state of the art only to the extent that's necessary to understand the direction of future development. Similar fields include: * Software engineering, which has the same basis as computer science, but tends to focus more on practical application of current software technology * Computer engineering, which tends to focus more on electrical engineering and the development of computer hardware, drivers, chips, and so on"
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9f5m8v | Why can't we store renewable energy in batteries? | Everyone says the biggest problem with renewable energy is there's no way to store it, but the battery has been invented already? | Technology | explainlikeimfive | {
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"We can but batteries are 1) expensive to produce but have good efficiency 2) cheap to produce but have poor efficiency 3) take up a lot of space that you need to store and maintain. 4) wear out over time and require replacing Ideally you only want to ever produce as much energy as you use. A coal factory can turn on and off at any given moment, changing its supply to meet the demand. In this respect, there are _no losses_. Compare that to solar energy. You generate energy during the day, but no one's using it. It has to get stored, then you use it at night. That's less efficient than making it as you need it. A good solution is hydroelectric. When power isn't being used, it can store energy by pumping water back up into the dam. But hydro is an expensive investment and not suitable everywhere. Alternatively, using renewable energies to supply the grid and then minimally using non-renewable energy when you don't have renewable energies going on. This seems to be adopted by a lot of places. You sell your energy to the grid from your solar panel if you're not using it, and then you buy it back at night, which offsets your cost or even earns you a profit.",
"Our ability to make batteries is so much smaller than the electricity we use that it's not even funny. World production of lithium batteries was roughly 100 gigawatt-hours worth in 2017. World electrical usage was about 24,000,000 gigawatt-hours in 2016. If New York City bought every single lithium battery made in the world in 2017, they could build a battery bank that would store the electricity they need for just one day. And that's just one city, a tiny fraction of a percent of the world. & #x200B; [ URL_4 ]( URL_4 ) [ URL_5 ]( URL_5 ) [ URL_3 ]( URL_0 ) [ URL_1 ]( URL_1 ) [ URL_2 ]( URL_2 )",
"Battery tech needs to catch up with renewables, atm batteries are just too damn expensive / not efficient enough to justify the capital expenditure."
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9f6cgx | What is smooth motion capture on TV? | [ URL_0 ]( URL_0 ) There is recent petition by top directors to remove smooth motion capture on TV. | Technology | explainlikeimfive | {
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"i thought smooth motion capture worked to eliminate motion blur as well as depth of field.",
"Footage that were shot for TV are usually 30 FPS (not sure, but I think it is?) and movies are usually 24 fps. It will look slightly stuttered to human eyes but we will still perceive it as motion. Modern smart TVs has a feature that analyze the input and put extra frames in between those real frames to smooth it out so that motions look, well, smoother. Some people like it, many don't. Personally i feel that it makes everything look like soap opera and feels cheap. I definitely don't want motion smoothing to change the feel of a movie and that's probably their point."
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9f6kmj | What is the difference between NVMe, M.2, SATA 3 and PCI-Express? | I thought that M.2 and SATA 3 were mutually exclusive until I came across a video that said an SSD was both and now I am confused and another video seemed to say that PCI-Express applies to any SSD and another video did not. What are the relation of these terms to each other? | Technology | explainlikeimfive | {
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"PCI Express is a way of connecting various different devices to a computer. It is usually used for devices inside the computer, and USB is usually used for devices outside the computer. SATA is a way to connect storage devices to a computer. It is usually used for internal storage devices, though it can also be used for external devices via eSATA. The 3 means it's the 3rd version of the standard, allowing for faster speeds than the original or 2nd version. SSDs were typically connected via SATA. NVMe instead connects them via PCI Express, which allows faster performance. M.2 is a form factor, meaning shape and way of connecting an SSD or other device to a computer. It can include PCI Express (supporting NVMe), SATA 3, and USB 3 interfaces. But devices and PCs may not support all 3."
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9f8n2n | Why do LED lights interfere with radio waves/signals and cause other types of electrical interference? | I changed the light bulbs in my garage door opener to LED bulbs and right away my range went to about 5ft and my ability to open the door was incredibly limited. The radio in my garage stopped picking up local radio stations until I put non LED bulbs back in. | Technology | explainlikeimfive | {
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"The actual light-emitting elements of an LED bulb run off about 5 volts. Your household wiring is about 120 volts (in the US). Each LED bulb has a circuit that switches the house power on and off very rapidly as a first step in converting to lower voltage. If this circuit is badly designed, it can create electrical noise that will disrupt radio devices. Try a high-quality LED bulb from a reputable manufacturer."
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9f9yjg | what makes tiny speakers like Bose's so much louder than tiny speakers from 20 years ago | Nowadays speakers have an incredibly better sound than before ... explain me what technology breakthrough happened in the recent years please | Technology | explainlikeimfive | {
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"Speakers like those, and the ones on your mobile phone, use feed forward techniques to amplify the sound at the cost of distortion. If you've ever used a megaphone or shouted into a cone, they make your voice perceptively louder. Same concept here. We just now have the materials and manufacturing technology to make tiny megaphones.",
"Glue got better. Back in the day glues that could adhere copper to plastic or paper didn't like high temperatures. Modern glues can take a lot more abuse than older adhesives. So you can apply much more power to small drivers without them ripping apart. Also those small speakers use a trick called hidden fundamental processing to trick your brain into thinking there is more low frequency information than there really is. Processing is dirt cheap so you can apply large amount of correction without spending huge amounts of money on DSP. Ferrofluid isn't something Bose invented. It was invented by NASA. It has been used to help cool the voicecoils of professional speaker drivers for decades. It is more thermally conductive so it moves heat from the voicecoil to the frame much more rapidly. This goes way past ELI5, but there is a modern form of processing called FIR processing that can correct problems that the old IIR processing couldn't."
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9fafd5 | How do they fit 6.9 billion transistors on a 7 nanometer chip? Additionally, how do they connect them up correctly? | Edit: I think Apple means 7 nanometers apart? Either way, can someone please ELI5? | Technology | explainlikeimfive | {
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"7 nanometer technology refers to the smallest feature they can make. As for how they can be made they are produced through a process called lithography. Individual layers are made and projected onto the material with light, interacting with chemicals to either stay put or wash away to mask areas so other material can be deposited. Think about making art on a wall by masking things off with tape or paper, then rolling or spraying paint on the wall to stick wherever isn't covered. Then you take it off and repeat again many times to make complex pictures. With chips they can actually be 3D structures as each pass lays down a tiny layer of metal or other material.",
"The 7 nanometers is the scale of an individual transistor, sort of the \"pixel size\" in the design. Basically, it is built in layers. You coat the top of a piece of silicon in a very thin layer of the material you need, then carve out the pattern you want in that layer with a laser. Repeat as needed to stack layers into a 3D structure. You're shining the laser through a larger template to get the pattern and focusing it very small, so the whole layer is carved at once, not individually 7 billion times.",
"They print them directly onto a silicon wafer, by masking off the parts of the chip that they don't want to become a transistor. For the record, very few people actually care about transistor count, anymore. It's a bit like saying \"this car has a big engine.\" That might be good, or it might be worthless, depending on the car."
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9fasae | How does the Phone Number cloning tech used by scammers work? Can it be prevented? | Technology | explainlikeimfive | {
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"Changing your phone number is a feature of the phone system, and any phone can do it. This is useful, for example, if a company has an outgoing block of numbers, but they want to present a unified callback number. There is no way to fix the problem without getting the phone companies involved, and they're not going to take away this service. Further, there are services, some free, where you can redirect an incoming call in order to reveal the original number. The best you're typically going to get, though, is some outgoing ATA, where the caller originates on the internet somewhere, and is essentially impossible to track. If you couldn't call a phone number from the internet, this problem would basically go away, but that technology isn't going to go anywhere, either, because companies all use VoIP internally and route outgoing calls through some teleservice, and there are companies that offer this as a service to anyone. I would say phone records are really dodgy in court these days, but that's the job of the defense to shoot that shit down."
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9fd1vh | What difference does the depth of water have on water resistant smartphones? | So Apple announced it's new set of iPhones today and one thing I saw about the 3 different models got me thinking... On Apples website they claim the iPhone XS & XS Max both to be water resistant to a depth of 2 meters for up to 30 minutes. However, the iPhone XR is only water resistant to a depth of 1 meter for up to 30 minutes. Not sure if this sounds dumb? But how can these phones withstand different depths and what difference can 1 meter make? | Technology | explainlikeimfive | {
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"Well.... water has weight. So more water is heavier than less water. I hope you can see where this is going. More water above you, as in= as you go deeper, means the water will apply more pressure. Thus, it tries harder to get where water isn't. Therefore, the deeper you go the harder the water tries to invade your phone. EDIT: Also, 1m^3 of water = almost 1000 grams of water. So... if you were in a tube that was 1m wide you would have 1kg of water above you. So, the difference between 1m and 2m down is a bit less than 1000grams of water. Actually more in regular situations because the water on the sides of you also exert a pressure.",
"They are only built to withdtand a certain amount of preasure, when you exceed that water starts to deep into the interior and messes up the electronics. It's pretty much so you can use your phone in the rain and not have to worry about it dying after dropping it in a puddle (although with IPhones dropping it from any hight is going to destroy it)."
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9fddeu | Utility locators - why do you put paint and flags on everybody’s lawn in an area and not just in the area where the actual work is being done? | Technology | explainlikeimfive | {
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"text": [
"Yes, clear up to your meter. The city owns and maintains water lines up to the meter. The meter itself is (should be) within the street right of way, ie. city property. When they replace the service line they will replace up to the meter. When they design the new lines they need to know where to make the service connections.",
"How sure are you they won't be digging *anywhere* near your yard? What are the costs associated with marking it all the way up to your meter versus a change of plans that knocks out your utilities? There is the issue of needing to know where the utilities are in the event of a plan change, and ensuring that they've been marked. If you're going to dig a trench and there is no marking for a gas line, does that mean there is no gas line directly under your trench or that the gas line wasn't marked? If you are going to dig a trench and there is a marking for a gas line 50 feet to the left then you can be pretty sure that there won't be a gas line where you want to dig Digsafe, or the equivalent in your area will generally have utilities(gas, electric, water, sewer) and telecom(fiber, cable, phone) lines marked for a few hundred feet from the actual point of work. Stuff like this runs on \"abundance of caution\" because putting down 50 extra flags at every job is a hell of a lot cheaper than blowing a residential gas line."
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9fdghk | What positive effects could the amendment that "bans memes" just passed by the EU have? | Technology | explainlikeimfive | {
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"There is literally no potential upside, for anybody involved. Not users, not websites, not even copyright holders. Everybody suffers as a result of this.",
"People who create content for a living can post it on a website from which they can derive an income without a million people copying it to media where the entire world can access it for free.",
"Memes could die out as something people spend time on. If anyone can claim copyright over any meme you post, and have it instantly taken down, then you can't get famous by having a meme go viral. If you choose instead to do something else to get famous, you might write some wonderful poetry and make the world a better place.",
"There are two parts, Article 11 and 13. Article 13 is complete shite. It (ELI5) says that every website (Google, Youtube, Facebook, etc) is responsible for making sure there's no copyright infringing stuff anywhere on their site. The website owners have to scan and approve all content that's posted. The problem is called **[Fair Use]( URL_0 )**. If I took the entire movie of *Lord of the Rings* and posted it on my youtube channel, that's copyright infringement and should be stopped. But **Fair Use** says that I can use a few clips from LotR (or any movie) to use in a review/criticism of the movie. Or in a news report, or as a parody, or for a lot of other reasons listed in the link. And Parody is the kicker. That's where memes come in. All of those \"One does not simply\" memes with Boromir are considered parody and protected under Fair Use. They're perfectly legal, even though they're using an image from LotR. But nuance like that makes it VERY difficult to build an automated process. YouTube's been trying for YEARS, and Content ID system is still notorious for being terrible. The fear is that Article 13 will basically force all websites to adopt an even stricter version of \"Content ID\" which will automatically find and delete anything that might, possibly, maybe, be considered copyright infringing... and all of the memes will get tossed out along side everything else. Edit: Completely forgot the other part, article 11. It's mostly shite, but might actually have some very minor benefits. It's commonly called \"Link Tax,\" and (ELI5) says that if your Facebook Friend sends you a link to another website, then Facebook owes that other website some money. Also, have you ever had a link on FB that kinda fills itself out and shows you the page right there. Like, if I linked to a picture, instead of having to click on the link to go to a different website to see the picture, Facebook would just load it up for you, and you can see the picture without having to leave FB. Well, Article 11 says that doing this will require a license, and probably cost facebook some money, on a per-site basis. The possible upside is that smaller sites will actually get a bit more traffic now. If the small site doesn't give FB permission (license) to show their content, you'll actually have to leave FB to see whatever I linked you. On the flip side, you won't know what I linked you until you click on the link. Maybe it's something normal, or maybe you just got rickrolled."
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9fffcb | How do movies or high budget tv series get their cinematic look? | Technology | explainlikeimfive | {
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"text": [
"One of the major differences between soap operas and more cinematic productions is lighting. Soaps tend to have more flat, even lighting that makes the entire scene well lit at the cost of dramatic shadows. This is by design because it allows multiple scenes to be shot under the same lighting which means everything moves faster and saves money in production.",
"You may be interested in looking up \"soap opera effect\" and \"motion interpolation\". Unfortunately, I'm not well versed enough to explain it, but I know it when I see it.",
"In addition to some of the other explanations, it also has to do with framerate. More cinematic movies and shows are typically shot at 24 fps. For some reason, it seems, soaps are not."
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9ffky1 | Devs/software engineers, etc. What are you exactly looking for when searching for bugs? | Technology | explainlikeimfive | {
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"text": [
"Generally, you only look for bugs in the code *after* you've witnessed something break in the program while it's running. From there, you try to isolate the place where the code does the stuff that could make the program break. Sometimes you can do this by following the code, sometimes you need to break out tools like debuggers or just have the program print out tons of information to a logfile. A lot of programs these days are written alongside a lot of tests. If you're lucky, you can use these to find the source of the bug by seeing if any of the components don't do what you expect for certain inputs. If you're not lucky, it's damned near impossible to track them down because the conditions for causing the bug are *super* sensitive & it won't happen once you start trying to debug the thing. When this happens, you either need blind luck or somebody who has seen the same sort of thing before to figure out where it is."
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9fh8na | What happens when you uninstall a program from your computer? | I'm especially interested why it can take so long. | Technology | explainlikeimfive | {
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"text": [
"The uninstaller program runs to delete files that the program created during installation. When it's done, it deletes itself.",
"It erases all files it initially installed. Usually on a computer when you install and application, it stores all the required information under one folder. Think of the computer as a room with file cabinets. Inside each file cabinet are folders. Each folder contains different things, whether it’s pictures or programs etc... On a windows machine, this might look like. C:/programs/program_I_will_uninstall Where the disk “C:” is the room, programs, the cabinet, and so on. When you uninstall the program, all you really do is take the folder from the cabinet, and throw it in the garbage."
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9fj3iv | How does a polarizing filter works? | Technology | explainlikeimfive | {
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"text": [
"Well. Let's say you have horizontal legos and vertical legos, and some giant space monster is throwing them at you constantly. The vertical legos are good, but the horizontal legos are bad. So you want to block them. How would you go about that? Well, one way is to put up a giant 'shield' of vertical legos. The space between these giant lego towers is wide enough for the nice vertical legos to pass through, but the horizontal legos obviously get blocked. It's like trying to shove a square peg into a round hole. It just doesn't fit. So the vertical legos come through, but the horizontal legos get blocked. This is why, if you're wearing polarizing glasses and turn your head 90degrees the light changes, because now you're turning your giant lego towers on their sides and only allowing horizontal legos through while blocking the vertical legos. Poof. Polarized legos."
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9fj3qm | Why do apps like Netflix need a permission to record audio from our phones whenever or info like are we walking or stationary? | Technology | explainlikeimfive | {
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"text": [
"The walking or stationary one means they need access to your phone's orientation to orient the video. The audio permission is probably for voice search.",
"A lot of permissions are lumped together by the peripheral. For example flashlight apps need control of the camera to operate the high power LED. Want to import contacts into your app or add them to phone contacts (like Facebook does for example) - that is the same permission group that pops up as Let this app place calls and access contact information?",
"To be honest I don’t know and I am not a expert but information has lots of uses. Two examples I can think of are: To research if more people are watching Netflix on the go on a mobile device or using it for home cinema. This lets them know if they should put extra time money and resources into developing an app that works better on the move with limited data/signal/ battery life or whether to push for a more high performance app that is better when in a set location. Also the information could be used to build up a profile on you to try and tailor the recommendations list more effectively. For example if it sees your on the move a lot you may be more interested in a documentary about commuting. (Poor example but you get what I mean)"
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9fjlsl | Article 13 and why it's such a big deal right now | Technology | explainlikeimfive | {
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"text": [
"So it basically says that social media companies need to have a filter for copyrighted material. This mean that on websites like Reddit, twitter, facebook...etc. If you tried to post a popular meme for example and this meme uses copyrighted material then it would automatically get taken down. If the companies didn't do this then they would be held accountable. While not impossible, it is definitely difficult to filter through *everything*"
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9flzbk | Why do electronics need to turn themselves off and back on to update? | Just got an update on my PS4 and it turned itself off and back on. I've always just taken as read that that step needs to occur but I don't really know why. & #x200B; Edit: A lot of similar answers basically saying it doesn't have to turn off and on but it's easier and cheaper if it does. This was my guess. Edit 2: Everyone who used the "you can't fix a car while driving it" metaphor, I hope you're happy. You ruined Mad Max: Fury Road for me. Thanks. | Technology | explainlikeimfive | {
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"I'm not a gamer, but in the \"big systems\" (IBM) world I work in, there are two types of storage... working storage/memory; and permanent storage/memory. Updates are written to permanent memory, but the copy in working memory has to be refreshed. You don't have to power cycle the unit after an upgrade, but then the new features won't be available.",
"For the same reason you can't replace critical parts in a car while it's running. You can't remove the gearbox *while you're using it* and replace it with another gearbox, and expect the car to keep running in the meantime. Removing some critical files in the Operating System *while it's running* in order to replace them will cause the Operating System to stop working. Because it needs those files to run.",
"Really, core operating system components, like drivers and kernels specifically are really hard to update without a reboot. Many systems, especially all in one type things (like a PS4) are configured to just always reboot after an update in case such a thing was updated. It makes it so the developer doesn't need to figure out what exactly needs to be restarted, and if it can be restarted. It also minimized testing because they can test the final configuration, after power off, and don't need to verify it works without a reboot. As for why core drivers are difficult to update, basically a driver needs to keep track of the state of it's associated hardware and respond to it in a timely manner. For example a keyboard has a caps lock, when caps lock is on you expect the letters to work different than when it's off. The keyboard might not actually have a feature to tell the computer if it's on or off, just if you pressed it or not. It's up to the driver to figure it out. Now reloading a running program is possible, but you need to know where in the code it is so you can stop it and start the new program in the same spot. Ideally the memory locations will be the same between old and new, and you can just transfer the memory. In real life, people program in high level languages which auto-allocate that stuff, so everything is practically scrambled. Also, the update might have deleted the spot the old code was at so you might not be able to transfer the running code. And further there is a chance that if it's a driver it never supported the new feature (for example number lock), so adding the number lock will result in an unknown state. Things get even more complicated when you talk about other things using the driver (think about a network card adding a feature while some other program is using it, how does the old program learn about the new feature?). My example was simple, real drivers are implementing things that take hundreds of pages to describe. The only sure way to do it is write a program that converts between old and new memory, with is about 1000 times more work than it's worth. It's way easier to just say reboot which will pull the reset line on all hardware and set everything to a known state.",
"It's not the electronics as such. It's the software (programs) inside them. When you turn on the PS4, it loads various programs into its memory, in order to turn a bunch of chips into a working gaming system. By far the simplest way to update those programs is for the machine to download the new version, store it in place of the old version, and so next time the machine starts up it will load the new version rather than the old one. & #x200B;",
"Software development issue. Writing a huge software that can do in-place updates is: 1. 100x more difficult. 2. A lot more costly due to increased difficulty. 3. Largely unnecessary because turning it off and on is pretty easy. It can be done, but unless it's absolutely necessary like in a nuclear plant, it's not needed. Even in nuclear plants, putting two copies of software so one can update while the other is running is much easier and error-proof."
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9fndcl | How do beer koozies work and are they actually efficient in keeping beer cold? | Technology | explainlikeimfive | {
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"text": [
"Beer koozies act like a barrier between a can/bottle and the outside temperature. It keeps the cold in and the warm out. It depends on what the koozie is made of, but yes, they are efficient",
"Your can is cold, the metal of the can is a poor insulator, meaning it can easily transfer energy from one thing to another with little issue, it then absorbs heat from the air and transfers it to your drink thus warming up your drink. The 'koozies' act as layer of insulation between the cold can and the warm air, usually the koozie is a foam like substance that is a great insulator making it harder, thus slower, for the air to transfer it's heat into your drink, slowing down the warming of your drink. & #x200B; \\~edit\\~ To answer the last part of your question, I would say it depends on the koozie as the material making them can vary wildly, but as long as it's more insulating than the can itself and not less so(essentially making it a heater) then yes it's efficient.",
"Some excellent answers already on the insulating nature of the koozies, but I'd also like to add that the warmth of your hand will very efficiently warm your beer through that thin layer of aluminum. You think \"Man, that beer is cold!\" but you don't think about the heat from your hand warming the beer. Wearing a thick glove would probably work surprisingly well at stopping that heat transfer, but you'd look silly."
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9fptf1 | What is the difference between HTTP and HTTPS and how do they work? | Technology | explainlikeimfive | {
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"text": [
"In most ways they are the same. HTTP is a clear text system, anyone can see what is being sent and received. The S stands for secure. The security is done by way of encryption. When your browsers first connects it setups encryption and so you get privacy.",
"A very ELI5 would be that HTTP is a plain text protocol. Imagine you go to a library and instead of choosing from the shelves or asking a librarian in english, you write on a postcard: `To: librarian` `From: your name` `GET name-of-book/page/21` You give the postcard to the nearest person you see and they pass it on until it reaches the librarian. They fetch that book and write the contents of page 21 on a postcard and send it back the same way. But now everybody knows you want to read dirty books. So HTTPS is sending a code on a (plain text) postcard to the librarian and getting a code back and some complicated maths between the two creating personalised encryption keys for you and the librarian. So then you can request your mucky book on a postcard (totally normal HTTP), and then put that into a sealed envelope to pass across the room, knowing that only the librarian will be able to open it with the special key the two of you just generated. Likewise your mucky literature comes back in a discreet brown envelope that only you can open."
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9fpwba | What are balanced and unbalanced connections in audio? | I heard there are no balanced cables, just balanced connections which just means it all depends on the electronic equipment and not cables. & #x200B; In other words, I can use any cables XLR, RCA, 1/4 inch, and they still can function as "balanced" if the equipments allow them? | Technology | explainlikeimfive | {
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"I've searched tha seven seas fer an answer. Yer not alone in askin', and kind strangers have explained: 1. [ELI5 Balanced vs. unbalanced audio signals ]( URL_1 ) ^(_5 comments_) 1. [ELI5: What's the difference between a \"balanced\" and \"unbalanced\" XLR cable? ]( URL_4 ) ^(_7 comments_) 1. [ELI5: what does low/high impedence, and balanced/unbalanced mean for an electric audio signal? ]( URL_2 ) ^(_17 comments_) 1. [ELI5 : what is the difference between balanced and unbalanced audio output? ]( URL_3 ) ^(_2 comments_) 1. [ELI5: line level audio, balanced vs unbalanced audio, phantom power and other audio basics. ]( URL_0 ) ^(_1 comment_)"
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9fq4jf | How noise cancelling headphones work? | Technology | explainlikeimfive | {
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"text": [
"there are actually 2 types of noise-cancelling headphones. Passive noise-cancelling headphones don't require their own power source, and simply have insulation, or extra padding, in the ear cups. Active noise-cancelling headphones require external power. They have small microphones on the outside of the ear cups. The microphones determine the frequency of the noise received and plays noise \"out-of-phase\" of the received noise in order to cancel the noise out. The easiest way to explain \"out-of-phase\" involves using digital conversion (I won't get into the details on digital conversion here)... if the incoming signal was converted to a binary (1's and 0's) signal is: 11010011, an \"out-of-phase\" signal would look like: 00101100.",
"I'm gonna try an actual ELI5. They make the same sound but negative/reversed, so that it cancels out the original sound."
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9fq77u | Why do submarines have to surface at all? Can't they just operate underwater for the entire length of the mission, especially if they are nuclear-powered? | I have heard that diesel engines cannot remain submerged for a long time, so they have to surface very frequently. But what is it they actually do by surfacing? Also, I understand that nuclear submarines can stay underwater for a long time, but even they do surface once in a while. My question is - why? Why do they have to do that? Can't they remain submerged during the entire mission? | Technology | explainlikeimfive | {
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"A diesel engine needs a source of oxygen, to burn with the diesel to power the engine. They can't store enough oxygen for long term running. Indeed, most diesel subs only use the diesel engines when at the surface or at periscope depth, pulling air down to run the engine to power the craft and to charge batteries, and when submerged they run solely on battery power. But nuclear subs can stay submerged for as long as they can keep the crew fed (and sane). They can generate water by desalination, oxygen by electrolysis of water, and the CO₂ is removed by scrubbers that are regenerated using heat - all driven by the power output of the reactor.",
"Nuclear submarines can stay underwater for as long as they have food for the crew, a normal amount of rations is 90 days' worth. Diesel subs need to come up every few days for air, since their engines burn oxygen. Another reason to surface is for communications; you can't send radio signals when deep underwater, and penetrating radio using VLF (very low frequencies) still has a maximum depth of about 60 feet. without coming up to the surface you would't be able to receive orders or information.",
"Former submariner. Theoretically, it’s only a matter of supplies and crew stress. I was serving in the 80s when there was no commercial Internet, and entertainment was limited to books, video tapes, and magazines. I can imagine that this lack of communication would create considerable stress for today’s crews. I discount the whole fresh air argument I keep seeing pop up on this post. The air onboard a sub can be maintained breathable for an indefinite period of time. Think about the ISS. It isn’t like they can dip that thing into the atmosphere every now and then. As long as you have a source of O2 (electrolysis on a sub, shipments of LOX to the ISS), can scrub out the CO2. CO, and H2, and otherwise filter noxious fumes, you don’t need fresh air Another consideration is that the US coast has a number of ‘submerged-free’ zones, particularly at major ports, where nothing should operate submerged. If there is anything submerged in such zones, it’s assumed to be hostile.",
"as a former member of the navy. (not a bubblehead). subs still have to surface to get fresh air (air can recycled to a point, much like apollo mission co2 scrubbers), get supplies, get trash off (plastic and petroleum based waste cannot be thrown overboard, repairs, and some radio signals can only be recieved when on the surface. ballistic subs (the subs that sit off the coast of Russia just waiting to nuke the planet in case of WWIII) in the American Navy have two crews and two captains. the crews switch out due to extended at sea times, the crews can't do computer based training on board due to lack of stable internet, and there are other things that go on that I don't know much about. this little nugget was given to me by a sub guy I met while in the navy. don't know much about subs, other than the pay is good, sea time sucks.",
"Honestly they don’t have to surface at all. The only reason they do is the human factor or repairs. People like to see the sky, even submariners. The only real reason is to restock on supplies and crew rotation ect Otherwise they could in theory stay underwater their entire working lifetime Repairs Food Supplies Crew",
"Former Submariner here, and theoretically, without getting into too many details, they can. Technically the only thing that would keep them from staying at sea, submerged indefinitely is the amount of food they can carry to feed the crew.",
"Nukes are only limited by food. Diesel subs have to come to periscope depth so their snorkel can take in air to run the diesel generators and recharge the batteries for underwater silent running.",
"You could theoretically stay under for about 3 months. Subs are specifically loaded with a \"90 day loadout\". The longest I ever stayed under was 60ish days. Depending on the mission they really should at least stick the snorkel mast up and change out the atmosphere. The HVAC system is very good but it just circulates farts over time. It's amazing the difference ventilating fresh air is after weeks of not doing so. We make our own fresh water and oxygen but can't make our own food. After about day 10 or so the fresh fruit and veggies are gone so it's all canned and frozen stuff. Day 45ish and you're down to all canned mostly. Day 55 it's rough. Beanies and weenies every day almost Source: am bubblehead",
"I have an additional question. What is the psychological toll on sailors who stay in a submerged submarine for extended periods of time?",
"Well, periscope depth and \"surface\" are similar but different. Even able to pull oxygen to run the diesel engines, diesel fuel is consumed in running a diesel sub. Realistically, a diesel powered vessel can go up to a week in \"normal\" operations. Obviously this is highly variable as actually *moving* the boat through the water consumes most of your fuel. Basically, even *if* you could supply your engine with oxygen without surfacing (we can't at this time) your liquid fuel would still get consumed pretty quickly. You might be able to use your batteries or engine heat to replenish your breathing air, but an engine consumes a *lot* more fresh air than human breathing. For a nuclear vessel, amount of power consumed *does* impact how quickly you consume or deplete your fuel, but it's not that big of a difference. 20-25 years is the common lifespan for a nuclear core. Now, I seriously doubt that a nuclear sub would be able to carry (or otherwise supply, grow, harvest, or whatever) enough *food* to sustain a crew for 25 years. And that's assuming they don't go batshit insane. But, mechanically, a nuclear sub *wouldn't* have to surface for anything.",
"I’m currently reading 20,000 leagues under the sea which was deemed futuristic when it was written, and the Nautilus (captain Nemo’s electric powered submarine) had to surface every now and again to change the air. Seems a bit daft that Jules Verne never considered oxygen scrubbers.",
"As a qualified submariner was gonna say exactly the same as the 1st comment. The only real time constraint is food on the nuclear submarines but if we a running diesels then you need air intake and to exhaust the fumes",
"Technically A nuclear submarine can stay submerged indefinitely, the only reason it needs to surface is to replenish supplies for the crew",
"assuming that nuclear energy lasts forever, would it be possible to bring a set of hydroponics into the sub, men and women, some chicken and other small animals, and make a permanent community in a theoretically never surfacing nuclear submarine?",
"Submarine and submersible expert here. Submarines are basically mechanical whales. As is the case with whales, subs must resurface from time to time to intake oxygen through the \"blowhole\", which is located at the top of the sub. The respiratory system is only one of many that have been copied from whales and mechanized for use on submarines. Mesh filters substitute for the baleen filters that whales use to eat. The nutrients are converted to bio fuel to power the subs engines. There's even a reproductive system that allows for the manufacture of smaller underwater reconnaissance drones.",
"with the advent of nuclear subs, and air recycling, the only thing preventing subs from being underwater basically forever is food.",
"The sub can operate indefinitely or as long as the fuel is sufficient. But the crew needs to eat, and that is the limiting factor.",
"Quite simply the sub can and could easily go for many many years. The short coming of any vessel is the humans inside it. The crew would eat all the food and need more. And longer sortis would run the risk of the crew going mad...",
"They surface when pulling into port or when resupplying at sea. Everything else can be done at periscope depth. They go to periscope depth to transmit and receive communications and to get GPS fixes so they can know their precise location, and to pull in fresh air (though not necessary since they can produce their own oxygen with water or use O2 candles). If they stay underwater they rely on their gyroscope for their location, which can get increasingly inaccurate the longer they stay underwater. Source: was a sailor in the navigation division on a nuclear sub about 15 years ago.",
"Sub vet in 90s. During operations never surfaced except entering and leaving port. During training was different. Did one swim call of coast of Hawaii.",
"One reason, among many others nukes surface, is to get a navigational fix. They rely on inertial navigation, which builds up errors over time, and is supplemented with GPS when at the surface.",
"Don't forget the crew has to go up so they can feel the air. It's rough staying in a dark sardine can for a very very long time. Not to mention restocking food supply and daily necessities",
"Former nuclear submariner here. For internet. We needed to surface periodically to receive and send out messages, especially those concerning missions. That and we like to get a breath of fresh air once in a while too. Steel beach picnics are a thing. Good for morale.",
"Hello, former submariner here. There are multiple reasons a submarine might come to periscope depth. Over time a submarine's atmosphere eventually develops a vacuum and this over time becomes dangerous to the crew since the human body has a tolerance which is can diffuse oxygen through our lungs. There are also quite a few other atmosphere contaminants that can grow such as refrigerant from the cooling system or even smoke during a fire or emergency. Submarines also need to come to periscope depth to communicate and check its position for navigation."
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9fvubv | How can the remaining battery percentage on a smartphone be displayed, where voltage and current are constant until the battery dies? | Technology | explainlikeimfive | {
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"found this article and it seems to explain what you are asking...... The battery meter in the corner of a phone’s screen might make you think that you’re seeing a perfect, standardized measurement, but the reality is sometimes a little closer to the guess-your-weight booth at the carnival. One way to understand some of the electrical concepts happening inside your phone is to use the analogy of an opaque water barrel, where the water it contains represents the power a battery can hold. If you open the spigot at the bottom of the barrel and water shoots out with force, you know the barrel is pretty full. Likewise, a steady but less forceful stream might tell you that the barrel is filled to somewhere in the middle, and a trickle would tell you it’s almost empty. Voltage in an electrical system is like water pressure in a plumbing system. In your home, water pressure is constant and the supply is effectively unlimited; similarly, an outlet’s voltage is constant and the supply of electricity is effectively unlimited. But with a barrel, the amount of water is limited, and the water pressure diminishes as the barrel empties. Similarly, the amount of power in a battery is limited, and voltage goes down as the power in the battery is used. The key to measuring a barrel’s content is to know how much pressure corresponds to a certain amount of water,. if a car battery’s output reads 13.2 volts when fully charged, and reads 11.8 volts when it’s unusably empty, you can use that scale (13.2 volts = 100 percent, 11.8 volts = 0 percent) But it’s not quite so straightforward. The voltage change from 100 percent to 0 percent is not a straight line, but rather a curve—and it’s a different curve for every type of battery. And, as an indirect measurement, just matching the voltage to a chart doesn’t take into account other variables at play. For example, one major variable is the speed at which you drain a battery: The faster you drain it, the less power you’ll actually be able to use from the battery—in electronics, bigger, brighter screens and more-demanding processors require more power. So to know with any accuracy how long a device will last on the battery’s current charge, you also need to know how much power the device will draw at any given moment. Because power draw varies depending on what your device is doing, its software has to estimate how long the current charge will last based on your current draw, typical use, or some combination of the two—and lower-end devices generally don’t even bother. So though the estimate on your battery meter isn’t always perfect, it isn’t outright lying to you. Between voltage, the current discharge rate, battery age, and the aggregate performance of its counterparts, it just has a lot to keep track of, and sometimes the resulting estimate just isn’t very accurate. In those cases, the best way for you to know how long your particular phone will last today is to keep in mind how it did yesterday—and keep an eye out for power outlets. URL_0",
"Phone batteries are typically Li-ion. Li-ion outputs approx 4v when 100% charged and drops to about 3.5v at 20% charge. It drops in a linear fashion. So the voltage of the battery is proportional to it's charge. [See figure 2 on this link]( URL_0 ) Their are electronics in the phone to regulate the voltage supplied to the circuitry. So whilst the voltage of the battery varies proportionally to it's charge level the processor receives the correct voltage no matter what the charge level."
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9fww3n | why does green power overload power grids? | I read about California producing so much power with wind and solar that they have to sell it to keep from overloading the grid. Can’t they just “unplug” the windmills and let them keep spinning? | Technology | explainlikeimfive | {
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"They don't in general. It is theoretically possible for a storm to cause a wind turbine to generate more power than it is intended to handle, but such a storm is likely to destroy the turbines. I have never read of green energy overloading the grid and cannot find any actual credible sources that state as such. The problem that Green energy has is that it does not have stable power production. It has spikes of high energy production (windy day, sunny day, etc) and it has lull periods (night, still days, etc) where it produces virtually no power. We do not currently have reliable storage tech for said power and thus Green energy can only be supplementary and as such there are times when not all of that power is used."
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9fyxro | Why do electronic devices (phones, laptops etc) have to be switched off during landing and take off when in an aircraft? | Technology | explainlikeimfive | {
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"It has nothing to do with the electronics, that’s the myth that just won’t die. It’s done so because of emergency procedures. The most likely part of a flight to have an issue is takeoff and landing. They don’t want you fiddling with electronics in case of an emergency and need you to pay full attention to the crew’s instructions. Just telling you to turn it off accomplishes that wonderfully.",
"Except they don't and can't assuming everything is wired properly, With the correct grounds. Source I retrofit avionics."
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9fyy8q | How does smartphones use negligible amount of electricity despite having such advanced features (i.e. multiple sensors)? | Technology | explainlikeimfive | {
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"Mobile communications engineer here. The two most important factors are advances in manufacturing and that we turn off as much as possible when it’s not in use. No need to turn on the cameras when they are not in use. No need to read the brightness sensor (used to adjust screen brightness) like crazy if once every minute does it as well. No need to run the GPS, compass or Bluetooth if it’s not used and even if it’s used you try to use as little as possible. The CPUs (System on Chip (SoC) is a more accurate name) of modern smart phones have multiple cores with different amounts of computing power and efficiency. The cores can sleep independently of each other and the more powerful ones are only turned on when necessary (for example for gaming). On a much smaller scale this is also done inside the chips. We turn off whole areas and clocks of the chip when they are not in use. In a mobile communications chip we turn off the more advanced parts for LTE (4G) when you are only using UMTS (3G) or GSM (2G). LTE has a mode where it’s switching between receiving and transmitting (TDD, Time Division Duplex). Well, guess what: We turn off the receiver during the transmission phase and vice versa.",
"How do you make a CPU faster? You could take any CPU, and if you run it at a higher clock rate, it will improve performance. The limit you run into is that if you increase it too much, it will begin to malfunction and crash the computer. But you can increase the voltage to the CPU, which will stabilize it at higher speeds, but it also greatly increases the amount of heat it generates. So most of the performance limits of any CPU are thermal ones. How much heat can you create before heat itself becomes the limiting factor. So chip manufacturers started a decades long process of making the guts of a chip run stable at higher speeds but with lower voltages. They could then run them faster and faster, while using the same cooling solution as older chips. You got more performance for the same amount of heat, the smaller the chips components, and the lower the voltage it could run at and be stable. A side effect of this race for performance is that as the voltage necessary to run at a particular speed dropped, so did the power requirements of the chip. In particular, if you ran them at a slower speed than they were designed for, then you could produce even less heat, and even lower power requirements. So mobile chip mfg's have chased that dragon of low thermal dissipation, and low operating power. It became more about work done per watt hour of electricity, than work done per second on fast cpu's. The CPU's in mobile and smart devices are part of an evolutionary chain of hardware designed for efficiency over any other consideration. That we have gotten them to the point where they are both efficient AND fast, is incredible. No mobile CPU can stand toe to toe with a desktop processor for speed, but the mobile processors are kings of thermal and electric efficiency and they get more work done, with less power. These improvements in chip lithography and design, had benefits in other areas like low power sensors, memory, hard disks. And more efficient mosfet power supplies, transistors, and other components. By getting rid of heat, they also got rid of inefficiency and allowed lower power circuits to do more work for less power. To make an analogy: In the 1970's a small 4 cyl automotive engine might make between 60-100 horsepower, and get 30-40MPG. Low power output, and decent efficiency. But then the government set limits on gas mileage and fuel consumption due to the gas shortages, and the EPA set limits on emissions, which required a bunch of expensive components added to engines, and further reducing their power. For awhile this really sucked and resulted in expensive, and slow car engines. But in order to meet these demands, designers started finding ways of extracting more energy from the fuel they did have, instead of simply throwing more fuel at it (like doubling the cylinders or making a larger engine). This increased their fuel economy, and it lowered their emissions, but it also meant the cars got more power from the same amount of fuel.... They kept finding better and better ways to improve the efficiency of the motors, and this kept resulting and more and more power from the same amount of fuel. Here we are 50 years later, and a small engine can make 170-250 horsepower naturally aspirated, AND still have decent fuel efficiency. Even our most efficient and tiny engines still make more horsepower than 1970's cars, and yet have sometimes double the MPG ratings. These tiny 1 liter engines that run 60MPG are like mobile CPU's. They are incredibly efficient, and by keeping the power output low, they sip power, getting the most work done for the smallest drain on resources like gas or a battery.",
"The sensors themselves use very little power. But mostly it’s accomplished by a combination of throttling the cpu based upon demand and performing functions then returning to low power states constantly."
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9fzpw6 | when we record a tv/pc monitor with a video recorder we can see strokes/static/waves passing over the monitor when we view the recorded video. However when we look at it with not eyes we see a clear screen. Why is this? | Why do the static strokes or whatever only become visible on video? Why is everything else we record true to what our eyes see, yet this is different? | Technology | explainlikeimfive | {
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"It's called persistence of vision, and it's a limitation of our ability to see very fast objects that we can exploit in order to trick the mind into thinking it's seeing one object moving, instead of many fast objects being strobed. Our eyes kind of summarize hundreds of images and only see the differences between them as motion, instead of as hundreds of still images. Cameras don't suffer this quirk of vision though, and they 'see' by rapidly scanning or sampling a sensor. When pointed at a display that is also rapidly scanning, refreshing, or changing hundreds of times a second, it won't be in perfect sync with the scanning/sampling done on the camera. Sometimes the camera will advance a frame, before the monitor or television has finished drawing the screen, so you get an incomplete image that looks dark in some places because at the exact fraction of a moment the image was taken, it hadn't finished drawing everything. The back lights of most modern monitors also use pulse width modulation in order to change their brightness. To get a lower brightness, they rapidly turn on and off thousands of times a second. Because of our lazy eyes, we see it as a reduction in brightness, instead of as a strobe light turning off and on. But cameras can see this strobing, as each frame of video may be as small as 1/60 of a second. The two ways to prevent this sync issue are to either sync the camera to the video so they both work at the same speed. Shutter or sensor captures a frame only when the display has finished drawing it completely, and the backlight is on, and you get perfect sync. This is actually how analog films used to be transferred to video and blueray. \"Telesync\". The camera syncs up to the shutter of the projector and captures complete frames, with some frames repeated in order to turn 24fps film into 30 or 60fps video. But this would require a connection between the two to sync up, or a very smart camera that can adjust itself to what it's looking at, similar to two drummers playing at the same speed by listening to each other. Or....you can lower the shutter speed of the camera, causing it to open the shutter, or scan the sensor, at a slower rate, giving the display plenty of time to draw one or more frames. In other words the higher the shutter speed and lower the frames per second of a video or still camera, the more likely it will capture incomplete monitor refreshes. The slower the shutter speed or higher the frame rate, and the more likely it will capture an entire frame, or throw so many frames at our eyes that they blend together and we don't see these artifacts."
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9fzxe4 | How do certain websites prevent you from backing out of them to the previous page no matter how many times you click on the back button | for example [this]( URL_0 ) when you get to it through google. which I ended up in because I was looking for the exact phrasing for the warning they put on ads for 4 hours or more for a joke I was sending to my friends...I swear...but that's besides the point.... To quote a special person: "I guarantee you there's no problem. I guarantee." | Technology | explainlikeimfive | {
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"there's a landing page that automatically redirects you to the page you see. so when you click back your browser is momentarily at the landing page again and gets forwarded back to the same page. sometimes you can counteract that by clicking back a few times rapidly (then you go \"backwards\" from the landing page to Google before it's able to redirect you again) to counter this some websites redirect you several times before you see a page, which makes it much harder to get back to where you were just using the back button. finding where you were in your browser history and clicking that will still work fine though _edit: or, as many have pointed out, right click the back button and select where you want to go back to_",
"Web developer here. There are a few ways this can be done. ------------------ You may notice sometimes that there is a `#` symbol somewhere in the URL (web page address at the top of your web browser). In this context, it's known as an anchor. It's native functionality is to jump to a certain spot on a page. You may see this used on tables of contents, where the index at the top has links that cause the scroll position where the corresponding contents begin. Super meta example of this: URL_0 (desktop viewing required) Notice when you click on a link in the index, it jumps a spot lower down and URL contains `#something` at the end. Also take note that the scrollbar has moved and it has not loaded a new page. When you click the [back] button in your browser, it will return you to the table of contents. Browsers consider anchor links to be their own entry in the history record. So, when you go [back], it returns you to the previous state It will continue recording any number of anchor links clicked or entered consecutively as another state. Nasty websites can use this behavior to seemingly trap you into staying on their website by programmatically manipulating anchors; basically, simulating clicks on numerous anchors consecutively so that the browser \"thinks\" its going back through the history of anchors you clicked. ------------------ There are other ways this can be done. Javascript is the programming language that implements dynamic functionality on a web page. There are built-in methods for manipulating and capturing the history state that are very useful for dynamic pages, but can be used to trap users a black hole of back-clicks. There are a number of other ways this could be done with Javascript, like capturing keyboard inputs and rerouting their behavior, opening modal elements (things that block everything else until they are dismissed) that recursively reopen themselves when dismissed, or overflowing execution (making a browser do too much at once and causing it to freeze). ------------------ tl;dr programming good. mean programmers be mean. Edit: I've been informed of my superfluous verbosity.",
"As others have already said, it's because you're just going back to the landing page which is then sending you to the website very quickly. If you click several times quickly enough you can sometimes 'beat' the landing page forwarding. The easiest way though, I find, is just click and hold the back button. Instead of going back a page, it drops down a list of the previous page history so you can simply click on as far back as you want to go. I use that technique often on regular pages when I've been browsing several pages within a site and want to get back to the main search results.",
"When you enter the site, you're forwarded to the the page you expected. When using the back function, you're sent back to the page forwarding you. Hence the loop. Instead, right click the back button and choose the entry you'd like to go back to.",
"An even better ELI5 would be \"why does anyone think this tactic will work to win you more customers?\" It's the equivalent of walking into a store to browse, only to have the door locked behind you and forced to look at more products by a masked man carrying a gun...",
"Usually it has an instant redirect page. Now that I fulfilled the requirement of answering the question. The solution is to right click the back button, this will open a menu of all the previously visited pages and just click the one you want.",
"That particular one has a rewrite to a url from a landing page, so likely the script just keeps shipping you off but you hit back and it redirects you again. Hold the back button and select the 3rd or 2nd history entry to go to.",
"A better question is; Websites that don't even allow you to close your web browser. These soft-lock phones too. They put a stupid message at the top of the browser when you try leaving even via closing and they say bullshit like \"LOOKS LIKE YOU WERE ABOUT TO LEAVE! ARE YOU SURE?\" and if you click either yes OR no, it just closes the prompt and you're still stuck on the page. Seriously have to always task manager these. As for how I find shitty sites that do this, 100% blame predatory advertisements accidentally being clicked on. Even YouTube has done it to me and I've had to report them.",
"The \"back button\" looks in your history and goes to the previous page. Or at least that is what is was ment to do when it was created. Since the arrival of fancy websites like gmail that load all content and pages (like deleted, inbox, starter etc.) On the same url. So pressing the back button would completely close out gmail when pressed while the user expects it to just go back to their inbox. So that's a problem. Luckily, whenever programmers encounter a problem they see it as a challenge and they came up with a piece of code that says \"if the user presses the back button, they don't actually want to go back, just tell me and I'll handle it\". This was a great idea in theory, but in reality those crappy websites just abuse it."
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9g19u0 | What is big data analytics? And decision science ? | Technology | explainlikeimfive | {
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"Imagine data as a bunch of stuff logged by technology that is impossible or difficult to read by humans because of its size. Big data is much more data. Computers can process and organize that big data into information, which is understandable and usable by humans. The amount of data grows exponentially, and without these computers it is impossible to use the data. Computers can find patterns in the data and process it into information that humans can use for decision making. For example, if a grocery chain processes the purchases from each receipt, they might find that people who buy baby diapers also buy beer. These items do not have very much to do with each other, but they are consistently purchased at the same time. The grocery store owners might use that information in their decision by placing diapers on or near the beer isle. If shoppers use a store card or something else that links individual trips to the store, even more data can be used to process information for decision making.",
"Data science is about extracting information, from large swaths of data and performing analytics (statistical analysis) to change the way your business runs. Data is great, but business or academia needs *information*. The job of a data scientist, doing analysis, and using various tools, is to derive information from data so it can be presented to decision makers to do whatever decision makers do. Cash bonus checks from my experience. Very useful in marketing, where you want to know what your customers classification is across multiple dimensions, to effectively market to them, or finance, where you're trying to tie relationships between transactions to find events that can affect investments, to all sorts of things that can affect manufacturing to political ideology. How do you learn it? Go to school. Statistics is used extensively, as well as learning to use various products that exist to do the analytics for you, by interacting with your data to get meaningful information out. Decision science is just using the derived information to make decisions. No mystery there. Analytics, is using the tools with the data to derive the information to make those decisions."
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9g2d3m | In video games, what causes the game to register that i performed an action but the server says that i didn't? | Technology | explainlikeimfive | {
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"An error in communication between your device and the server. It could be any number of things from latency (lag), a temporary outage, or a malformed data packet or something.",
"Both your computer and the server keep track of where everything is in the gaming world, and send updates to each other. These updates take time, and sometimes you do things in your local copy of the gaming world that have since become impossible in the server's copy. If two people try to pick up the same object, both local copies might think they succeed, but only the one that gets to the server first (or with the earliest timestamp) will succeed."
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9g3fa8 | How is sea-level height measured when taking into account the curvature of the earth? | I always see mountains and buildings that are completely landlocked yet have their height measured as being above sea level, but the earth itself is round, making this very difficult to measure. How is it done? | Technology | explainlikeimfive | {
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"What you're looking for is the shape known as the *[geoid]( URL_0 ),* the shape the earth's oceans would take under the influence of gravity and rotation alone. Recent advances in satellite *geodesy,* or the measurement of Earth's fundamental properties, allow us to model the geoid to remarkably high precision; that shape is the basis for measuring inland elevation against sea level."
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9g3kyg | What is nondestructive testing? | Technology | explainlikeimfive | {
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"text": [
"Exactly what it sounds like: a test that doesn't destroy the test sample. A 0-100-0 test on a car. Conductivity test on a metal sample. This is in contrast to \"destructive\" testing like a vehicle crash test or a chemical sample thermal decomposition analysis. Some tests require the destruction of the sample, some don't. Do the destructive test last.",
"Some kind of NDT tests are conducted to assess the degradation of a material or to confirm its integrity. for example, nuclear steam generators, airplane wings, etc need to be in perfect state to operate safely. You can use Ultrasounds (phased array, conventional), eddy currents, xrays and others. An inspection is made before the installation or for periodic maintenance to determine if there are cracks in the material (or solder) or corrosion. There are many defects types which may represent a smaller of larger risk. Why is it non destructive? Because using these techniques will not alter the integrity of the materials while other could. Since the whole ppint is to make sure the material is in pristine condition, it would not make sense. Source: I work in NDT"
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9g4s51 | What is the difference between Ray Tracing and Path Tracing? | So I've been really interested in learning about computer graphics recently with the whole conversation about NVIDIA's new RTX cards, but I just can't wrap my head around path tracing and whether or not it's possible in media like video games, or if it can be done now or in the near future on consumer hardware. Some places tell me the new cards are capable of it. Others say we're still far off from consumer path tracing. Sometimes the terms seem interchangable. Other times they're different techniques. I'm just left lost. | Technology | explainlikeimfive | {
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"Ray tracing is when rays that are going to the camera (or view) hot an object, and then multiple rays are projected out from that point of Orgin, to the various light sources, those rays either intersect with other objects, or reach their light source, depending on where the rays land information is taken and calculated for the original ray point, and that information generates the image. This kinda fakes what light actually does. Ray path is when the ray hits an object, and then bounces to try and reach a light source, and it will do this as many times as needed until it reaches the light source. This is how light actually behaves, each bounce calculation gives more data, and on top of that the actual light source size and shape also matters. This is actual light simulation. Ray's occur for each pixels displayed, which means either of these methods can cause a insane amount of calculations and run an unfathomable amount of lines of code, which is why both of these are so insane to do.",
"The truth is that the border between the two terms can be a bit blurry. Some people would say that path tracing is a specific type of ray tracing, while others would say it’s a step beyond ray tracing. The simplest ray tracer just shoots rays for each pixel on the screen into the scene, they hit an object, and report back a color. (This is different from typical video game graphics, aka raster, which is more like the objects in the scene projecting themselves onto the screen). However, to get nice images and allow for things like shadows and reflections, good ray tracers will allow the rays to “bounce” some number of times. At some point, it reaches a limit and reports back the color it found. But reporting “red” for a red object makes an assumption that it’s getting some”ambient” light; what if it’s in pitch black? What if it’s only getting blue light? Path tracing involves bouncing repeatedly until the ray actually gets all the way back to a light source, and only counting those full “paths”. It can also involve creating those paths in more complex ways, like shooting rays from both the camera and the light source and then connecting those sub-paths (this is called bidirectional path tracing). Path tracing also involves random chance; there are infinite scattered paths of light so you need some way to choose which ones to follow. (There can be some randomness in regular ray tracing too, but path tracing is all-in on it). We are still quite a ways away from real time path tracing in games, and we’re not even quite there yet on full real time ray tracing. Nvidias new tech involves using ray tracing techniques to enhance traditional raster graphics. They can do some neat demos that are fully ray traced, but it’s my understanding that the interactive games that are coming out using RTX are not fully ray traced, they’re just using it for some effects. It’s a hybrid. There’s a lot more to it but that’s about all I can do at a semi-ELI5 level. I’m happy to try to answer in more detail if you have more questions. I also recently got into computer graphics and have written my own bidirectional path tracer. It’s a really cool field."
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9g5r90 | How does audio recording work? How is sound digitized? | Technology | explainlikeimfive | {
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"There's a couple of principles that you need to understand for this. The first is how sound works. Sound is basically air being squeezed. It's sort of like a slinky. If you hold the slinky stretched out between your hands and then really quickly move one hand in and then back out you'll see part of the slinky will squeeze together and then behind the squeezed together part it'll stretch out. If you start moving your hand in and out over and over again you'll see that the entire slinky will become parts that are squeezed together followed by parts that are stretched out moving along the slinky from one hand to the other. [Here's]( URL_0 ) a picture to show it more clearly. Sound is pretty much the same thing, but in air. You hit something, that something vibrates, that causes the air around it to compress and stretch, creating a sound wave. Next is how microphones work. The simple explanation is that when you move magnet near a conductive material it generates electricity. So in a microphone there is a magnet suspended near a conductive material like a wire. When a soundwave hits the magnet it will push it closer to the wire then pull it back away. When it pushes the magnet toward the wire it generates a small positive voltage and when it's pulled back it generates a small negative voltage. Because the voltage is generated by the sound wave pushing and pulling the magnet the voltage will increase and decrease pretty much exactly matching how the air compresses and stretches. So you have a wave of voltage travelling through the wire now that can be represented just like the sound wave. Now the computer takes samples of this voltage. It basically takes a reading of this voltage at one point in time and records how high it is using bits (just a bunch of 0s and 1s). Then a very short time later it takes another reading and records how high it is at that time, and it does this over and over again many times per second. If you were to then plot the voltage measured against the time it was measured at you'd get a punch of points on a graph that, if you traced a line between them, should pretty faithfully recreate the sound wave you were trying to record. How accurate it is then just depends on how good your equipment is. The computer then just stores this data, basically staying \"At time 1 the wave is this high. At time 2 the wave is 'this' high. At time 3 the wave is 'this' high.\" And so on for the entire duration of your recording."
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9g7o3m | If computers only read 1s and 0s, then isn't downloading anything online just creating instructions? Like isn't everything a computer can do already inside of it? | Technology | explainlikeimfive | {
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"text": [
"Yes you are downloading instructions. Extremely complex instructions. Mind bogglingly complex instructions.",
"Your computer can play you a movie by lighting up each pixel on the screen at just the right moment and with just the right color. The \"movie\" you download is a certain set of instructions telling your computer which pixels to light up and when. Software like paint or Photoshop allow you to tell the screen which pixels to light up and what color. With software inside your computer, you are writing the instructions. Downloads are sets of already written instructions."
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9g7up8 | How come newer phones only have hybrid SIM (SIM+SIM or SIM+SD card) when old phpnes were able to have 2 sim slots AND a micro sd slot? | Technology | explainlikeimfive | {
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"Space is at an ultra premium in newer generations of phones, the less they have to deal with for stuff like this, the better they can design the phone. Adding more slots and sizes and places a user needs to interact with the external portion of a phone drastically alters their design ability. In a perfect world, we’d want NO slots or removable stuff at all for optimal designs."
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9ga8di | How do car production lines maintain efficiency but also offer optional features? | Technology | explainlikeimfive | {
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"Most of that efficiency is maintained because there are other assembly lines that deliver what’s needed. For example, the guy or robot that puts the seats in your Toyota, all he does is grab the seat that’s delivered to his work area and install it. It’s no different to him if it’s a cloth seat, or a leather seat. All the computer tracking sets it up so that this leather seat shows up when this vehicle that is ordered with leather seats shows up. I would say look at it like a tree trunk, the assembly line that the car is on is the trunk, and there are more smaller assembly lines that build each component, and feed them in the programmed order that they are needed, so for example one branch has the seats on it, and on that branch, there are branches for leather seats, or power seats, or cloth seats. A different branch does the navigation, and smaller branches from that branch have the option for big navigation screens, or small ones, or CD players. The only probably different part, would be the paint, and that’s just done in groups. This week it’s blue ones, next week it’s white ones, the following week is red ones, etc.",
"Basically every station might have every part readily available. Orders come through and they still do the process the same, just applying different parts. They should know so by some sort of parts # list. Source: used to build interior for '15-'16 C7 Corvettes",
"After all these years in reddit, finally, something I can respond knowledgeably on. I’m a project manager for a major OEM supplier, and started out on the shop floor designing production lines. So you have a final assembly line where they build the car, and parts come in 3 ways into the line. One the chassis comes from the paint plant, as do the doors, the fuel filler flap and any other bits that need painting. Second, there are parts that only have a small number of variants, and are quite small. Each variant has its own box on the station, and the right one is selected and fitted for that car. The third method, for parts that have a lot of variants like door trims and interiors, is where the electronic system that tracks each car coming down the line take the bill of materials for that car and use it to generate a position in a numbered slot in a numbered stillage. The timings are all worked out so when that stillage hits the line, the exact slot is available as the correct car comes down the line. This is sequencing. Consequently the line just keeps running, with all the parts and their variants for those cars being available in line at the right time. Logistically it is quite amazing to think of thousands of suppliers making parts that arrive just as they need it. Sorry I didn’t answer the question about efficiency. Each operators movements are built up as a theoretical model and the total operations are spread equally as possible given the sequence the car is built. Then the rate of the line dictates the total time each operator has. The rate of vehicles leaving the line is the TAKT time. There is a lot more to it than that but that’s the basics."
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9gaenj | How do applications like Timehop show what texts I've sent years ago, even if I've changed phone? | Technology | explainlikeimfive | {
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"The app is remembering, rather than the phone. They likely store all of your messages on a big server somewhere.",
"As another person said, all of your messages are stored on a central server, along with everything else you do through those apps. This is why encryption and privacy are so important"
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9gcfv1 | why do phones/laptops etc have so many different size screws in them? Why not just use one size? | Technology | explainlikeimfive | {
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"First off, let’s only talk about assembly related screws. If they are screws on different components, and the components are made by different companies, it makes sense that there’s no common ground between those right? Next there’s standard following screws that must be be a certain way to follow standards. The mounting screws for m.2 SSD for example must be that size. The mounting/ tension screws are also mostly the same types for a given chip/heat sink. So last there’s the screws that are put in place by the assemblers. The mac book pro is the only one I’ve looked at that has more than like five types of assembly screws. So the different types may be different regarding length. Longer screws lock things in place better, but not every place can support such long screws. On bigger laptops you might see a long screw type and short screw type locking the chassis down. Next you have size, which often comes hand in hand with the screw type (torx, Phillip, etc). Phillips screws are designed so that it’s harder to overtighten them. The head will wear out before you can tighten them too much. But due to this design, they are also extremely fragile when you shrink the sizes down. So the very small screws mostly use torx, which provides extremely well grip and doesn’t wear easily, making them suitable for the internal screws."
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9gdjw2 | Why was Half Life 2 considered such a milestone in gaming? | Technology | explainlikeimfive | {
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"It had amazing graphics and physics at the time, just compare [it's character animations]( URL_2 ) with a similar game at the time like [Far Cry]( URL_1 ) and you can see it still holds up, and is even better than some [current games]( URL_0 ). Not to mention it's just a really good game to boot.",
"At the time it was the pinnacle of a game engine, also had a interesting story and great voice acting.",
"Half Life 1 was fantastic, and the story and gameplay in the 2nd completely lived up to expectations and hopes. Also, the physics engine was incredible at the time. I remember a friend literally called me over to his room to show me that he had figured out you could pin dead bodies to the wall with crossbow bolts, or that ammunition would go through open windows on vehicles, proving they were actually rendered \"realistically\" rather than just as one solid block like they had been before. It was a big amazing step forward in pretty much every aspect. Physics, graphics, storytelling and complexity, voice acting, franchise advancement, etc.",
"It had an engine that could assign properties to materials. You could tell the engine something was 'wood' or 'metal' or 'glass' it wasn't just textures and surfaces, it was actual interactions between materials and lighting. And it was the first well known instance of an actual physics engine- I remember seeing the first time a mattress was lifted up and it flopped around - how barrels would roll on surfaces. light shined through red glass would shine out red, and look distorted . And it was the first time living models talked with moving lips and eyes rather than just nutcracker mouths and 'talking in italian gestures' And it gave us G-Mod.",
"Real time physics on machines that were Pentium 4 single core CPUs. Integrated graphics even.",
"The game engine was developed over 9 years, compared to 3 for the Unreal engine. This contributed to its advanced nature.",
"The main reasons have been already mentioned however, HF2 is a better single player game than 99.99% of recent games. It was made to tell an interesting story in interesting locations that actually needed some basic problem solving skills (quite rare these days). To me it's like asking why Game of Thrones is considered one of the best TV shows of all time. It does all the things it wanted to do well and is still much better than current day's competition. And it does it without hand holding the player and innovating greatly with the engine. Few games (if any) match HF2's physics and believable gameplay. Any player can see that Valve made it because they wanted to make a great game first and make money second.",
"This guy has a good few videos on some of the reasons why, might be worth checking out. URL_0",
"I've waited years for it. It's still one of best games ever. Atmosphere, physics, smart design and great e3 tech demo",
"I have heard the game described as \"The thinking man's shooter\" and I think this is a lot of the reason why it is still considered amoungst the best games. A lot of shooters were/are seen as quite lowbrow, half life and half life 2 were much less focused on the action, allowing a lot of puzzle solving and being rewarded fir thinking outside the box. Take Ravenholm, you could get through the whole section only firing one bullet. The story and setting were also quite new at the time, that era was heavily focused on world war 2 and not a lot of shooters tried to tell a story like that.",
"[This short retro doc]( URL_0 ) gives perspective on the entire series if you watch all of it. I linked to where it starts talking about HL2 and its contribution to the series and gaming as a whole."
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9gf3u7 | Why is the quality of telephone hold music so terrible? | Technology | explainlikeimfive | {
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"Two reasons: The telephone line is optimized for human voices, which have a very limited range. most music falls outside of this range, so a lot of the higher and lower frequencies get distorted or cut off. In some cases it could also just be that the audio file itself hasn't been changed in years or is small to begin with, and lacking in quality there as well."
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9gfimy | - If I’m on a call and my phone is on speaker, why doesn’t the microphone pick up on its own audio? | Technology | explainlikeimfive | {
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"text": [
"It does. There is a special circuit in the phone to provide echo cancellation or that audio would result in feedback through the call. The phone can do this because it knows what sort of sound it is outputting and recognize that when it is picked up.",
"it did but at the same time, there is a circuit that does a 180 degree out of phase action and cancel that out, so you are left with clean audio. this is the basic of noise cancellation technology."
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9gfji9 | If a website/server is hosted in the cloud, how can increased traffic cause the site to crash? | Technology | explainlikeimfive | {
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"> Why wouldn't the cloud allow it to just scale up? \"The cloud\" is just a word meaning \"someone else's computers\" and if their computers aren't able to handle the load they may crash as well. Scaling up capacity might not be fully automatic and takes some time so completely unanticipated load could overwhelm even an outsourced solution.",
"Actual ELI5: Cloud just means not on servers you own. You still have to have good software for full scalability. Not familiar with this case, but in order to have something scale, even on the cloud, takes good coding, and needs to account for many different things. When you enter, say, URL_0 , your request is first looked up on servers that contain the server’s actual ip address. Then, your browser will request data from that ip address. In between this whole process is the physical connection you have to the server, load-balancers on the web server side, and a huge number of other things to account for. To have a well-designed web app is not so different on the cloud vs. on physical servers. You would still have to account for the hardware limitations (although adding new hardware is simpler and can even be automated). You just don’t have to consider things like power, cooling, and CPU specs, etc anymore."
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9gh90r | Why did the number of websites double from 2011-2012 and 2016-2017? | Technology | explainlikeimfive | {
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"If I were to guess those were years when venture capitalists were more open to dumping money into startups. 2011 was about the time of Uber and the buzz was \"disrupting the x business\" If I were to guess now it's about machine learning VC goes in waves and follows the herd."
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9ghir4 | - Why do they use seemingly out-dated scales when doing the weigh ins for boxing/MMA fights? | Technology | explainlikeimfive | {
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"text": [
"Nope. Surprisingly those mechanical scales are more accurate. Also digital scales are easier to be manipulated without anyone knowing.",
"It's all a big show for entertainment when they do the weigh in. How much fun is stepping on a scale and getting an instant result? How do you drag that out? You don't, unless you go old school."
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9ghpg4 | Why do pictures taken of computer screens from a phone look so weird? | They have weird curves and lines on it when I'm zooming in, or rotating the picture. The effect looks somewhat like looking at a wire mesh through another wire mesh. | Technology | explainlikeimfive | {
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"> The effect looks somewhat like looking at a wire mesh through another wire mesh. Because you're basically doing the same thing. The pixels in the computer screen are arranged in a grid. The pixels in the camera sensor are arranged in a grid. The pixels in your phone screen are arranged in a grid. Because those grids don't perfectly align with each other you see an effect that is called [Moiré pattern]( URL_0 ). The same thing happens when looking through multiple wire meshes, because those are also grids that don't align perfectly. The holes of the meshes are similar to the pixels, the mesh themselves are the spaces between the pixels. **Edit:** to answer a few common questions: The strength of the effect depends on the alignment and relative scale between the grids. So you can reduce the effect by better aligning the photo (e.g. making sure the camera isn't rotated or tilted) and by trying different distances from the screen. The effect is stronger if some pixels from the monitor fall right in the middle of the pixels of the camera sensor or phone screen while other pixels fall in-between the pixels of the camera sensor or phone screen. And since the camera app of your phone will show you a scaled down picture (phone screens may have a resolution of 2-4 megapixels, while phone cameras have resolutions of 12-20 megapixels) you may not see the effect in the preview of the photo but later in the actual photo, especially if you zoom in. In order to prevent the effect you can basically only resort to trial and error. Snap a picture, open it, zoom in at the size you want to use it and check if a pattern is visible. If not, then try again at a slightly different distance, or change the photo resolution in the camera app. Also you can use the settings to show an alignment grid to make sure the camera looks as straight at the screen as possible.",
"That's called a moiré pattern. It comes when two grids (in this case, your monitor's pixels and your phone's pixels) are overlapping and misaligned. [Relevant XKCD]( URL_0 )",
"TIL it’s called a moiré pattern, but i’ve taken a picture with my phone on a 4k tv and didn’t seem to notice the anomalies, probably because the pixels are tighter together. I also wonder if you had a 4k phone if you would see them.",
"If I tell you paint a wall, you either gonna apply paint horizontally or vertically. *Ofcourse human goes creative we can do that in a diagonal way / creating various shapes or such. But, computer is not. It's still humans' slave.* So the computer (precisely your CPU) sends the data like an image wallpaper to your monitor. And monitor starts painting your desktop horizontally one row at a time and comes back to the second row (technically called retracing) and goes in a loop till the entire screen is painted. Once it ends it goes to the first brick of your wall (first pixel of your monitor) and redo the above mechanism. Now our cameras are pretty powerful and faster than the speed of monitor painting (measured in hz -hertz for e.g. 60hz monitor). So it captures the continuous refereshing (re-paint) of your monitor right at any point of time which makes it look weird and broken. This was drastically bad with CRT monitors, now you know - slow painting / less hz compared to modern LCDs/LEDs. Bonus: 60hz Monitor = 60 times painting / second",
"Why do I feel like this is why we look different in real life than in most photos?",
"Also, taking pictures of CRTs doesnt work because CRTs will refresh their screen pixel by pixel, line by line, which causes a sort of scan effect going across the screen. Cool demonstration in [this video]( URL_0 )"
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9ghqkf | - How do computers even work? | I’ve never really understood the internal workings of a computer. I know that there’s the hardware (which is like all the physical parts of the computer) and then the software (don’t have a good explanation for this yet other than it’s the stuff that’s not physical). Can someone please explain a) how these two structures work together and b) how a computer manages to store files, communicate with servers and the internet etc, all that sort of stuff? | Technology | explainlikeimfive | {
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"Imagine I am building a machine that prints patterns of blue and green dots on some fabric. In order to define the pattern, I use a piece of paper. I’ll punch holes in the paper when I want the dot to be blue, and no hole, when I want it to be green. Now I can build some mechanics that walks down a row of dots and at every step moves an arm with a blue marker onto the fabric when there is no hole, and an arm with a green marker if there is a hole. When it reaches the end of the row, it moves back and advances the paper by one row. The nice thing is, if I want a different pattern on my fabric, I just need to replace the sheet of paper. The paper is your memory. The pattern of holes on the paper, that’s your program, also known as software. If we talk about bits, that’s hole versus no hole. The machine that „reads“ the paper, that is your CPU. In a modern Computer, things of course get a bit more complicated. We have different types of storage. And we can actually modify the holes in the paper on the go, closing holes and punching new ones. We have fast storage that goes away when you turn the power off (RAM) and slower storage that keeps around (HDD, SSD). We have various ways of communicating with the outside, not just a roll of fabric and parts that can modify how the pattern is read on the go (keyboard and mouse). GPUs display things on a monitor, other parts do USB or networking etc. Data storage used to be mostly magnetic. You basically take a sheet of metal (in reality a spinning disk of metal), and you use a strong magnet to magnetize a part of it. Where it is magnetized, that is the equivalent of a hole. Old floppy disks and HDDs work that way. SSDs are a bit more complicated though, I can’t think of a good explanation right now. If it involves cables, think of the cable as a radio antenna. We shield it, so that the radio waves don’t go anywhere except along the cable. Now to computers can talk to each other using a very complicated version of Morse code, but it all comes down to the hole/no hole thing again. USB is the same as network cables, except the computers attached are often very simple things (like the chip in your USB mouse). If we talk about protocols, it’s just the way we have agreed the the Morse code should represent certain things. And then it gets complicated. We build up from that, layering things on top of each other, trying to standardize things etc.",
"All computer hardware is specifically made to work together when attached to a motherboard. Like circuit lego that fits. These are managed by a CPU which is a chip that has something called logical gates which operated at speeds I can't even think of a series of 0 or 1. The software side there is also a language called binary. It is a computer language that operates in 1 or 0. Now, for example, your title to this post would be saved in Binary as: > 01000101 01001100 01001001 00110101 00100000 00101101 00100000 01001000 01101111 01110111 00100000 01100100 01101111 00100000 01100011 01101111 01101101 01110000 01110101 01110100 01100101 01110010 01110011 00100000 01100101 01110110 01100101 01101110 00100000 01110111 01101111 01110010 01101011 00111111 Check out: URL_1 A quick google brought me to this: URL_0 which probably explains it better than I can. (I wish i paid more attention n my degree haha)",
"Computers are frickin complicated, so this turned out really long and mostly off-topic, sorry. Okay so, if you take a bunch of wires and transistors and such, you can make logic circuits. These take some binary (on or off) input and give an output. for example, an AND gate is on if both inputs are on, and off the rest of the time - they're true if A and B are both true. If you want to mess around with these yourself, most of them can be made in minecraft, like [this]( URL_0 ) AND gate, because redstone emulates certain aspects of electricity. If you put a bunch of these gates together, you can have them do basic math. It's all being done in base 2 though, because of the whole on and off thing. For example, [adding two numbers together]( URL_1 ) can be done digit by digit pretty easily. So if you wanted to quickly add 5001 + 4216, you'd just convert those numbers to binary, toggle power to the respective wires of your adding circuit, and the circuit would turn on the correct wires for the result, and you'd convert that back to decimal. You put in input, and get output. Now, it turns out, basic arithmetic and conditional execution (basically, you can do some math and you can go \"if this, then that. if not this, then those instead\") actually go a long way, if you just link enough of them together in smart ways. For pretty much any task where you have binary inputs and want a consistent binary output, you can make some circuit that hardcodes that task. When you're designing this circuit, it's pretty similar to coding, just at a REALLY low level. But making circuits is hard, and requires physical materials and storage space, and everything has to be done super manually. There are still lots of people who do it, because some things are worth hardcoding to make things go fast, but it's just not realistic or convenient for many of the things we do. This is where the CPU comes in. Basically, you make a little chip with all of the basic arithmetic and logic circuits, just lying there ready to use, and you add a flag, an instruction, to tell the CPU what you want it to do. Let's say we have a simple CPU that can load a number, add two numbers together, and it can check if one number is bigger than the other. So we'll say the flag is in the format \"AABB\". AA tells the CPU what to do. If it's something that requires two numbers, BB tells the CPU what number to load for the second number. You can then say \"00\" means do nothing, \"01\" means load this number, \"10\" means add together the number in registry and the number in BB, and 11 means skip the next instruction IF and only IF the number you've already loaded is bigger than the number in BB. This is fairly simple to hardcode, you just need to turn on and off the right circuits to lead the electrical signals to the right components. Extend this out to a few more instructions, and you can basically design a logic circuit without making any circuits, just by telling the CPU to use the circuits it already has in the correct orders. This is how programming works, this is what software is. You store a bunch of instructions in one area of memory, tell the cpu to start running instructions from the beginning, f.ex. address 0. This sets the instruction counter to 0, the cpu loads that instruction, interprets it, executes it, and adds 1 to the counter. Then you add some flags to change the counter *if* this or that, which lets you have conditional jumps in code, and you're able to program pretty much any logic. This conditional jumping lets you say for example: if the user presses a button, and it's the left key, jump to the part where i tell the player character to move left. if it's space, jump to the part where i tell the player character to jump. So this CPU then connects to some caches (tiny amounts of a faster, more expensive version of RAM, that pretends to be RAM for compatibility reasons), and then to the motherboard, a place to interconnect all the different components, and route power to them, which also connects the CPU to the GPU and RAM The RAM is essentially a place to keep numbers, because the CPU only has room for a few. RAM basically just contains a bunch of little bits that remember what signal you sent them until you tell them to forget, and a circuit to manage all of these so it can store your bits in the right place and retrieve them later. These forget things if you don't keep powering them though, so they can't really store things between reboots. The motherboard then connects lots of other components indirectly to the CPU, such as your wifi card, ethernet card, hard disks, cd drive, etc. Your CPU can then talk to these devices by sending a message to the motherboard like \"Hey relay this message to device 3 for me\", or \"hey give me a number from device 3\" or \"hey load like, a thousand numbers from this place in device 4\". These devices are usually way too slow to bother waiting on though, because the processor is stupid fast, so they usually store their results somewhere temporarily, and send the motherboard a signal that they have stuff ready. After that, it's just a matter of designing individual pc parts, and writing code to make the CPU talk to them in the right way. Harddisks for example work by having lots of tiny things that you can magnetize inside of spinning disks, and having a stick that moves in and out along these plates and can read whether something is magnetic or not, and make things magnetic or not. Once the little things are magnetic, they stay magnetic until you mess with them, so it can store stuff over a long period of time. SSDs and flash drives kind of work like RAM, in that it's just a bunch of tiny circuits that keep their state, but these ones don't slowly lose the charge you give them, so they don't need power to remember things. This means they're faster, because you don't need to physically move an arm around, and they're a bit more resistent to being shaken and turned around. Also, note that most modern coding is like 1-3 levels removed from the raw machine code you feed the processor, because machine code is a pain to write."
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"http://www.minecraftguides.org/wp-content/uploads/2012/06/redstone2.jpeg",
"https://minecraft.gamepedia.com/Tutorials/Advanced_redstone_circuits#Version_1"
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9gisj5 | - How do YouTube to MP3 Converters work? | Hello world! I want to understand how these converters retrieve the necessary data and then convert this to MP3 or any format for that matter? Where does it get the video link data from and such? I just thought it would be a interesting topic to understand. I do understand some basic coding and API knowledge. | Technology | explainlikeimfive | {
"a_id": [
"e64m6o3"
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"text": [
"At the low level, a Youtube video is a file stored on Youtube's CDN, which is fed out to the client. If you can discover the direct URI to a Youtube video ([pretty simple to do with a program like VLC]( URL_0 )), you can download it yourself. That's essentially what these converters are doing -- extract the actual URI of the video, download the file as an actual file, then run it through an audio converter (ffmpeg would work well for these purposes), then present the resulting file to you."
],
"score": [
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"https://lifehacker.com/the-best-hidden-features-of-vlc-1654434241"
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9gjxno | What is quadratic voting in simple terms? What are the advantages and disadvantages? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"For this week's family council, you get 4 \"vote credits\". There are 4 decisions to make: * A: What should we have for dessert, ice cream or fruit? * B: Should we get a puppy, yes or no? * C: Should we buy a cheap new TV or keep using the old and save for a better one? * D: Do we allow people to leave the dinner table early, yes or no? The key is: you are allowed to use multiple votes on the same decision! If you really, really want a puppy and don't care so much about the other decisions, you can put all your vote credits on the \"yes\" for the puppy decision and give up on influencing the others. However, your 4 credits give you only 2 votes rather than 4, in order to prevent giving individual people (or small groups) too much weight on individual decisions. So if your sister and your parents all don't want a puppy but still vote on everything, their 3 \"no\" votes on the puppy still override your 2. But if your sister agrees with you, it's 3:2 for a puppy even though both parents were against it. You'll just have to eat fruit and stay at the dinner table."
],
"score": [
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9gjy1m | why does a computer need to "warm up"? | Warm up not in the sense of a car's engine but rather in the software/OS sense. You start up your computer and in the first few minutes of logging in everything is choppy/laggy, emails take an extra few seconds to load etc. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Because (especially in the case of Windows), the operating system loads and runs just enough components to allow you to log in, and show the desktop, while literally hundreds of drivers and services continue to be loaded and run \"in the background\" . Older versions of Windows would not allow use until everything was loaded and running, which meant that, for several minutes, the system was completely unusable. The newer method is a compromise. You may find that installing an SSD disk drive greatly speeds up the time to usability.",
"Hard drives are slow. RAM is fast. After the computer is on the OS will keep on caching data from HDD to RAM. So waiting a while can sometimes result in faster starting programs. The OS loading data from HDD to RAM doesn't slow down your system so do not disable this feature even if some people say you should. The caching is done with lower priority so if you do something on the active action is given priority over the cache stuff. Also after you close a program some of the data is kept on RAM. So starting the program again is much faster than on first start."
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9gk3x9 | Why is a PIN number considered safe with 4 numbers while a password needs 8 chars with numbers and capitals? | Technology | explainlikeimfive | {
"a_id": [
"e64otfo",
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"text": [
"Because anyone on the internet can have a go and guessing my username and password, often an unrestricted number of times. Only people with access to my PC or my credit card can guess my PIN, and usually only 3 to 5 times.",
"For a credit card, the PIN is an *extra* layer of security on top of needing to physically possess the card with the magnetic stripe. The card itself is the primary security layer, with the PIN adding extra protection against theft. For an online service, the password is the *only* layer of security, since the login is often public information. Because of this, the PIN doesn't need to actually be very secure in order to do its job. Consider the PIN to be a type of 2-Factor Authentication. The 2 factors are, as the saying goes, \"something you have and something you know.\" For an online account, \"something you know\" is the password and \"something you have\" is your phone. For your credit card, \"something you know\" is the PIN and \"something you have\" is the card itself. In both of these cases, the second factor is usually pretty weak--most 2FA tokens are what, 6 characters tops? This is because the security comes from the fact that they're a second factor. Making the second factor stronger has a poor cost/benefit trade-off. Now I have no idea why your PC has both a PIN and a password. This only makes sense to me if either a) the password is for the (online) microsoft account and the PIN is just for the PC or b) the PIN gives user-level access but the password is required for admin functionality.",
"I think it's because you only have 3 attempts for PIN where you have unlimited for password. No brute force hack.",
"The pin is local to your laptop and does not use the online Microsoft account, however it links to the MS account after allowing login. Or to put it another way, when you log in to your Win 10 pc using a Microsoft account and password, the credentials are sent to Microsoft (close enough) which determines if you are allowed on the computer. When you log in with a PIN, it checks against its internal database, allows 4 attempts and then times you out and forces you to reboot the computer. & #x200B; If someone manages to install spyware on your computer that monitors key strokes, they will not be able to capture your password and compromise your files at OneDrive or [ URL_0 ](https:// URL_0 ), because they will only have your pin that works on that one computer and not your Microsoft account. & #x200B; & #x200B;"
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