q_id
stringlengths 6
6
| title
stringlengths 4
294
| selftext
stringlengths 0
2.48k
| category
stringclasses 1
value | subreddit
stringclasses 1
value | answers
dict | title_urls
listlengths 1
1
| selftext_urls
listlengths 1
1
|
|---|---|---|---|---|---|---|---|
b5i73j | Why do clocks sound like "tick tock" instead of "tick tick" or "tock tock"? | Technology | explainlikeimfive | {
"a_id": [
"ejdnlxl"
],
"text": [
"On pendulum clocks one direction of the swing moves the gear forward, while the other direction of the swing hooks the tooth of the next gear, so the even and odd clicks usually have a different tone."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b5jodf | How does food "contaminate" plastic? | I have heard that most food packaging is thrown away and sorted into general waste (a.k.a landfill) because the food residue interferes with the plastic recycling process. Is this true? If so, please ELI5 me | Technology | explainlikeimfive | {
"a_id": [
"ejdyit2"
],
"text": [
"Let's say you have two tons of virgin plastic pellets at your factory. You are going to melt them down and mold them into 1 million dollars worth of Tupperware. Right before they go into the melting oven a disgruntled employee takes a massive shit into the pellets. Do you continue with the molding process or do you stop and spend thousands of dollars cleaning all the plastic costing you profits and never being sure you got everything clean possible costing you the entire batch because the foreign substance caused the plastic to not mold correctly? Same thing with contaminated plastic. If you bought 100 tons of recycleable plastic and had to spend time and money sorting out and cleaning the contaminants and throwing away the plastics that can't be recycled you lose money. Chinese companies are refusing American plastic because it cuts into their narrow profit margins."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b5m7t0 | Why do some radio/alarm clocks have antennas that are just long wires? | Technology | explainlikeimfive | {
"a_id": [
"ejeew6z",
"ejeit95"
],
"text": [
"Most FM radio antennas are just long thin bits of metal. It doesn't much matter whether it's a rod or a wire, and wires are cheap.",
"Because radio signals are just invisible electromagnetic waves blasting through the air around us. Depending on where these radio waves are being broadcast from determines the direction that these waves are passing the radio receiver. The wire is long like that so that it can catch these waves most clearly (avoiding static and shit) by sensing the full wavelength. This is the reason that the antenna are opposable. Bend it one way to catch that frequency or channel clearly. Change the channel and all of a sudden the image or radio is no longer clear? That's because the antenna is oriented in the wrong direction to from the broadcaster. Just jimmy around with the antenna and it'll be clear again when facing the right direction."
],
"score": [
10,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b5p4no | Why cars have driver seat on the side of the vehicle and not in the middle? | Technology | explainlikeimfive | {
"a_id": [
"ejeuui5",
"ejeuynk"
],
"text": [
"Lane visibility, by having the drivers seat, and steering wheel on the side closest to the middle of the toad it gives the driver the best visibility of the road ahead. It’s also more of an effort to get in and out of a car if the drivers seat is central.",
"Because historically there was the hum in the center for the drive line and transmission, plus it would be harder to get in and out of the vehicle if you had to go such great distance, plus then you would not be able to get as many people in the vehicle. It is not really practical for a people mover."
],
"score": [
12,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b5pu6k | why is it that we use petrol as fuel when alcohol is both cheaper and easier to produce? | what cons does ethanol have compared to petrol? one thing i'm certain about is that ethanol is both cheaper and easier to produce. should have cons then. what's that? | Technology | explainlikeimfive | {
"a_id": [
"ejf0hu7",
"ejezrhc",
"ejf0m66"
],
"text": [
"* It isn't as energy-dense; 20 liters of petrol is about equal to 30 liters of ethanol. This means cars either can't travel as far on existing tanks, or would need bigger tanks (and thus need to lug around more heavy fuel, reducing fuel economy) * Ethanol is *hygroscopic*, meaning it absorbs water from the air. Water tends to be pretty bad for engines, so maintenance costs go up. * Ethanol damages aluminum, magnesium, and rubber. These are all used in engines. Engines can be built without these materials but they are more expensive and harder to maintain. * Ethanol can't ignite at low temperatures. For this reason, pure-ethanol fuel is not used on a commercial scale in most of the world, and is instead mixed with petrol in a 85/15 blend at maximum. * Ethanol is **not** cheaper or easier to produce - in fact, in most cases *producing ethanol uses more energy than the ethanol produces* meaning that it's wasteful to use. Once produces of ethanol fuel transition to renewable/non-polluting energy sources this will become less of a concern, but it is still more efficient not to use ethanol. * Ethanol at present tends to require large amounts of land and water to produce; whether this is a problem varies from place to place. As developments with ethanol sources (e.g. high-efficiency algae) progress, this may become less of an issue.",
"There is much less energy per gallon in ethanol than gasoline. It's slightly cheaper, per gallon, and slightly more expensive, per mile. Ethanol is **not** easy to produce. Most ethanol is produced by converting **food** into fuel. People need food to eat to keep them alive, it's highly expensive, in terms of lost opportunity. A corn field's worth of solar cells makes more miles of electric car driving than it makes miles of ethanol car driving.",
"Another thing to note is that fossil fuels were (especially a few decades ago) **extremely abundant.** Technically they still are, since there are vast mats of subterranean organic compounds collected over tens of millions of years, be it coal or oil. Some just require a bit more ingenuity to reach now (deep sea oil rigs for example). But it used to be the case that you could just drill a hole in the sandstone at say...Kuwait. And the natural pressure difference would pump it up for you. [The Burgan Oil Field was the size of 11,000 football fields.]( URL_0 ) And contained about 75 billion barrels of oil. Completely accessible on land with no extremely complex equipment. And that's just one oil field. Insofar as selecting a readily available fuel source for your growing automobile industry in the 20th century...well petroleum is just perfect."
],
"score": [
27,
25,
3
],
"text_urls": [
[],
[],
[
"https://en.wikipedia.org/wiki/Burgan_field"
]
]
} | [
"url"
] | [
"url"
] |
b5qy23 | Why do windows apps since the install shield wizard install crapola all over the place and need an uninstaller? | What’s the advantage over just having everything under one parent folder? | Technology | explainlikeimfive | {
"a_id": [
"ejf8faw"
],
"text": [
"It is because a lot of apps can share common components, but if they are all in their own folders, it would be an inefficient use of storage, due to duplication."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b5wnpa | In a URL, if it doesn't matter if letters are uppercase or lowercase, why do some URLs have some uppercase and some lowercase? | I'm talking about the random letters and numbers and stuff at the end of a URL like: kOuy-8crzV0 Is there any reason why the O and V in that case are uppercase while the rest of the letters aren't? | Technology | explainlikeimfive | {
"a_id": [
"ejgemac"
],
"text": [
"Case does not matter in domain names, but servers absolutely can (and most do) distinguish case in directory and file names. You haven't given a full URL, but I suspect your example is actually a unique ID/code of some sort being passed as an argument to the server for some purpose, and is likewise case-sensitive, which has the benefit of allowing a shorter strings."
],
"score": [
13
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b5xosu | Before binary code and how it knows what it was doing. | Technology | explainlikeimfive | {
"a_id": [
"ejgoox5",
"ejgosnx"
],
"text": [
"Computers made using what are called logic gates. Essentially, you have two wires going into the gate and one going out. Each input wire can be turned on or off, and the output wire depends on what kind of gate it is and what the inputs are. In an AND gate, the output is turned on if both inputs are turned on, and turned off otherwise. In an OR gate, it is turned on if at least one input is on, and only off of both inputs are off. It turns out that by stringing the right combinations of logic gates in the right order, we can do more complicated things. One of the most important is that if we write numbers in binary (which only needs 0s and 1s), and then consider a wire that's off as 0 and one that's on as 1, we can do math (addition, subtraction, multiplication, division) and compare numbers (greater than, less than, etc.). Putting these more complicated pieces together, we can build even more complicated stuff, like your computer's processor. The processor has a bunch of input wires that represent a command telling it what it should do by using certain patterns of 1s and 0s and what numbers it should operate on, using a binary representation. But since those patterns of 1s and 0s are tricky to remember, we write the instructions in a more human readable way, called assembly code. Each assembly instruction then gets translated directly into one instruction composed of 1s and 0s, then stored where the processor can use it as input. Nowadays, we use other programming languages that are easier to use, and translate them into assembly code and from there into binary.",
"Lets start with something really simple. Calculator that adds numbers. Before we start that we have to briefly talk about logic gates. A logic gate a a simple set of switches that will give a certain output depending on the input. For our calculator the important ones we need to know are OR, XOR and an AND URL_0 OR gate will return true if any of the inputs are true. We can use 1 for true and 0 for false. a XOR gate has two inputs and will only return true if only one of the input is true. 1:1 will return 0, 0:0 will return 0, 1:0 and 0:1 will return 1. AND gates return true only if both of its inputs are true. It will only return 1 if the inputs are 1:1. We can combine these two gates together into something called a half adder. The half adder takes two inputs we can call A and B and 2 outputs. The XOR gate will output our sum and the AND gate will output something called the carry. This is an incredibly simple calculator and currently cannot add higher than 2. Finally we can build a full adder. A full adder has 3 input and 2 outputs. the inputs we can call A, B, and carry in while the output will be the sum and the carry. We can build the full adder using 2 half adders connected to each other and one extra OR gate the connects their AND gate outputs. We can then string a group of these full adders together connecting their Carry in and carry outputs together to build a calculator that can add any numbers together as long as we have enough full adders connected together. All the A inputs will represent corresponding digits to one of the numbers, and the B inputs will represent to their corresponding digits to the second number. This got way more complicated than i originally wanted it to be, but whats important isn't how the calculator, work but more important is that the logic gates just need to be able to respond to an input and send an output. This doesnt have to be a high tech computer and can be done with anything that can respond to an input and send out an output. if you attached a weight to two different pulleys, then that would function as an OR gate. Get creative with your pulley design and how they connect and you could build that calculator with wooden posts and rope."
],
"score": [
3,
3
],
"text_urls": [
[],
[
"gate.an"
]
]
} | [
"url"
] | [
"url"
] |
|
b5xvg1 | Why do buffer overflows allow an entry point for exploits? | I don't understand how more data than expected can allow for unsigned code? | Technology | explainlikeimfive | {
"a_id": [
"ejgyn7v",
"ejgolol"
],
"text": [
"Think of a buffer like a wall of PO Boxes at a shipping store. Each part of memory (the wall) has its own unique shipping address. A computer program needs a certain number of memory addresses/PO boxes in order to fit into the memory buffer, and this can be allocated by the OS beforehand. Lets say PO Boxes 10-20 are given to this program. Now if the program overflows and exceeds its allocated memory size, the person placing mail into the PO Boxes (the OS) might stuff mail/program data into PO Box 21 because it needs the room. Exploits can sometimes then steal the information that was already stored in PO Box 21, or instead overwrite whatever was in there and replace it with malicious code. Keep in mind not all PO Boxes are equal, some are more secure than others. If PO Box 21 was a very secure box with elevated code privileges then whatever the overflow forced into it would gain those same elevated privileges and be able to run malicious code. The postmaster (the OS) would pull the data from PO Box 21, see that it came from a box with elevated privileges, and would run it without knowing any better. I am ignoring that there are a huge number of safeguards put into place to prevent this, but it is still possible particularly if a poorly coded program doesn't use the safeguards or uses one of them incorrectly.",
"A buffer is an area of memory--and it shares main memory with other code. A \"buffer overflow\" exploit is where you get the computer to reach beyond the boundaries of that array--which, with low-level programming, is pretty easy to do. More particularly, though, it's when you put your malicious code just beyond the boundary of the buffer in memory and then trick a program into accessing it. Imagine if memory was set up like this, with the first three elements being the buffer: Memory: {\"Good\", \"Good\", \"Good\", \"Bad\"} Now, what happens when you get your computer to reach beyond the buffer, to the fourth element in memory? You run the bad code, and the malware has successfully exploited the buffer overflow error."
],
"score": [
6,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
b5zsvp | Why does space rockets only use fuel and not other energy sources like electric, etc. ? | Technology | explainlikeimfive | {
"a_id": [
"ejh2nwp",
"ejh4bys",
"ejh2ivk"
],
"text": [
"Rockets operate in space by throwing mass in the opposite direction of where they want to go. Whether they get their power from a chemical reaction or a battery or a nuclear reactor, they still have to carry propellant on board. Every ounce of weight a rocket carries reduces its efficiency, so it only makes sense to use a combustible fuel that serves dual roles as both an energy source and a reaction mass. It's not a strict requirement, however. Prior to the development of the Space Shuttle, [NASA experimented with a variety of nuclear-powered rocket engines]( URL_0 ) that fired inert gases rather than combustible fuels, which would have been used for manned interplanetary missions.",
"Short answer. The do use solar power. Rockets make thrust by making something go really really fast and throwing them out the back. Many of the newer probes use [ion thrusters]( URL_0 ), which use electricity to make xenon ions go really really fast and throwing them out the back. They throw them out so fast you don't need a lot of xenon to make the space ship change its velocity by a lot. Thing is, our batteries aren't very good, chemicals hold a lot more power per kilo. Ion thrusters also aren't very strong. They are turned on for many days at a time, while a chemical rocket only needs a few minutes to do that. Chemical rockets are relatively simple, just mix all the things together, light it, and keep pumping in more stuff. The chemical used for burning is the thing that is going to go fast, and it's going to make itself go fast with fire. You don't have to worry about generating electricity, then pumping in the the thing you want to make go fast, then actually making it go fast. Finally, there has been talk about using nuclear heat to make hydrogen go really fast. It's been studied for project [NERVA]( URL_1 ). The idea is that ships and power plants use nuclear heat to make steam go really really fast, then push it into a turbine to make energy. For the rocket, they use nuclear heat to make hydrogen go really really fast, then push it out the back.",
"This will be an incredibly simplified answer and I am sure someone can add more detail and info. It’s effectively about how much energy you can get from your fuel source for the weight. You need a fuel that you can easily use to transform that energy into kinetic energy. And a way to do that both in the atmosphere and in space. Rocket fuel has a lot of energy and is “somewhat easy” to change into kinetic energy (momentum) and works both in the atmosphere and in space."
],
"score": [
20,
10,
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/NERVA"
],
[
"https://en.wikipedia.org/wiki/Ion_thruster",
"https://en.wikipedia.org/wiki/NERVA"
],
[]
]
} | [
"url"
] | [
"url"
] |
|
b607w5 | How do scientists track the temperature of the ocean? | Technology | explainlikeimfive | {
"a_id": [
"ejhff5x"
],
"text": [
"There are many different instruments that work together to give us a global view of the ocean. 1) **Infrared Satellites** can measure the amount of infrared light coming from the surface and infer the temperature of the ocean. But they only see the very topmost surface, and can't measure the deep ocean. URL_2 2) **Ships of Opportunity** are cargo ships that routinely measure the temperature of water that comes into their engine room. They share that data with oceanographers. URL_0 3) **Oceanographic research vessels** are custom-built ships with an instrument on a long cable that can be lowered down to the bottom, measuring temperature and other water properties along the way. These are very expensive, there are only a few of them and they don't cover the whole ocean. URL_4 4) **Expendable Bathythermographs** are torpedo-shaped disposable temperature probes that are dropped off a ship, and signal temperature back to the ship through a fine copper cable that spools behind the probe. These are dropped from both oceanographic vessels, and from ships of opportunity. URL_1 5) **Robotic drifters** are basically submarine drones, they drift around at depth for a while, then float to the surface, measuring temperature as they go up. They radio that data to a satellite, then sink down into the depths again. We now have thousands of these, and they're changing the way we do oceanography. URL_3"
],
"score": [
4
],
"text_urls": [
[
"https://www.wmo.int/pages/prog/amp/mmop/JCOMM/OPA/SOT/soop.html",
"https://oceanexplorer.noaa.gov/facts/xbt.html",
"https://www.ospo.noaa.gov/Products/ocean/sst/contour/index.html",
"http://www.argo.ucsd.edu/",
"https://www.unols.org/ships-facilities/unols-vessels"
]
]
} | [
"url"
] | [
"url"
] |
|
b60sof | What is happening to the pixels of a gray-scale image when we resize them to a smaller image? | If we were to use an 8-bit 2000px by 2000px image as an example, I understand that for each pixel there is a value that is between 0 and 255. I'm struggling to understand what is being done to the pixel values and their rearrangement if we were to decrease the size of the image (for example by a quarter) to 1000px by 1000px. What is the process that allows the image to be perceptibly unaltered whilst taking away pixel values? Thanks for taking the time to read this question. | Technology | explainlikeimfive | {
"a_id": [
"ejh9sah"
],
"text": [
"in your example the image actually goes from 4 megapixels to 1 megapixel. So, you reduce four pixels to one pixel. Take the top left corner: take four pixels, average out the values, make that average into one pixel. Now do it to the rest."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b65zvl | How do quartz watch movement system work ? | Technology | explainlikeimfive | {
"a_id": [
"eji3kz8"
],
"text": [
"The bit of physics that needs to be known here is something called the *piezoelectric effect,* where squeezing or deforming a crystalline material generates an electric field. Importantly, this effect works in reverse -- applying an electric field to a piezoelectric material results in a uniform mechanical strain. Because this effect is calculable, we can measure the deformation that arises in a quartz crystal due to the presence of the watch battery, and use that motion to drive the gears."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b66h6v | I cannot understand a Vigenere Cipher, please help | My husband has a project due and he needs a partner for a Vigenere Cipher. I've watched videos, he's tried to explain it to me and I just do not get it at all. It makes ZERO sense to me and all that happens is that I get angry...like Monopoly angry...please help me understand this stupid cipher so I can help my husband do his project. How do you get a keyword? Do you just make it up? If the message has two of one letter (for example "apple") why doesn't the ciphered txt have repeating letters? I know what a cryptogram is, and maybe I'm treating this Vinegere Cipher like that, but idk how to differentiate between them. Thanks in advance Edit: thank you guys so so much! Between you and my very patient husband, I now have a very minor grasp on this Vinegere Cipher. It's just enough that I think I can help him with his project. Thank you again!! | Technology | explainlikeimfive | {
"a_id": [
"ejibe5c"
],
"text": [
"> How do you get a keyword? Do you just make it up? Yes. > If the message has two of one letter (for example \"apple\") why doesn't the ciphered txt have repeating letters? Each letter of output depends both on the input letter and the key letter. The same combination of both will produce the same output. For example, if the input letter is \"B\" and that lines up with the key letter \"C\" that will always produce an output letter \"D\". So a double letter in the key (such as \"pp\") will only produce a double letter in the output if the input is also a double letter. > I know what a cryptogram is, and maybe I'm treating this Vinegere Cipher like that, but idk how to differentiate between them. A more general explanation is that a Vinegere Cipher is using a different shift cipher for each letter. For example, a simple shift cipher is you pick a number (or letter that represents a number) such as 3 (or D) and you shift *ever* letter in the input message by that amount. That means: HELLO WORLD becomes KHOOR ZRUOG Since every letter is shifted by the same amount, this is pretty easy to crack. To combat this, Vinegere Cipher shifts different letters by different amounts. Ideally, the amount you shift each letter by is random and non-repeating, but that is too hard to implement in practice. So Vinegere has a compromise where you create a key. The letters in the key determine how much you shift each letter. A key of \"APPLE\" basically says: \"don't shift the first letter (A), shift the second letter by 15 (p), shift the third letter by 15 (p), shift the fourth letter by 11 (l) and shift the fifth letter by 4 (e)\" then you repeat that over and over again. It's applying a different simple shift cipher to each letter. Double letters in the key don't produce double letters in the cipher text because all they are doing is telling you to shift two different letters by the same amount. If those two letters in the plain text are different, then the two letters in the output text will be different."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b6ahq9 | How do prosthetics, including a glass eye, move with the body? | Technology | explainlikeimfive | {
"a_id": [
"ejj2f5a",
"ejj6bdh"
],
"text": [
"I know glass eyes have a depression in the back that is fitted to a group of muscles so it twitches with the muscles that control both eyes.",
"It depends entirely on what type of prosthetic you are talking about. Glass eyes are actually going to be completely different from just about anything else, so they are particularly poor examples to use. A common method for artificial limbs, however, is to hook an electrode to the skin above an intact muscle somewhere on the body. Twitch that muscle certain ways and the limb responds. Some of the cutting edge ones will even use the electrode to feed sensations such as cold and pressure back into that same skin area. This may sound odd, but it's hard to over emphasize just how adapatable the brain is. In time, the person with the limb completely forgets they are using a different muscle or feeling sensations there, and can move the limb and feel things with it like it was their real arm and leg because the brain figures out what it is really controlling and adjusts that person's perceptions accordingly. Here is a video of a double hand amputee using bionic arms using this method to do things like putting on makup. Pretty amazing stuff. [ URL_0 ]( URL_0 )"
],
"score": [
3,
3
],
"text_urls": [
[],
[
"https://www.youtube.com/watch?v=4eMQuhxNDJM"
]
]
} | [
"url"
] | [
"url"
] |
|
b6akca | Why is there always static/interference during hold music when the person on the other end is crystal clear? | Is it intentional to make people hang up or is there another explanation? | Technology | explainlikeimfive | {
"a_id": [
"ejjehep"
],
"text": [
"To transmit sound over a telephone connection most efficiently, it is encoded at one end and decoded at the other end. These encoders and decoders (I'll call them CODECS from now on) are designed to work very efficiently, using minimum processing power on your phone (saving battery) and using minimum amount of data ('bandwidth') on the mobile link. Whenever you design something to work efficiently at one thing, you make tradeoffs in another thing - a sports car isn't good at crossing rough ground, and an all-terrain vehicle isn't very fast. In this case, the CODEC is designed to be best at making speech understandable. It is optimised for the patterns, frequencies and tones of human speech: the person speaking is crystal clear. When you're put on hold, the system plays you music, which has very different patterns of tones, beats, and a wider frequency range, which the CODEC is not optimised for. It has to work 'harder', and will use more power or bandwidth if possible, or lower quality if not. There are may different CODECs, but most of them just play you static when they run out of bandwidth. This is because because experiments have found that in speech (which is what the CODEC is optimised for) our brains prefer static noise compared to the line going silent for a second. When the hold music is playing, the CODEC - which is designed for the different sounds of speech - is overworked and throws in static bursts for bits it can't do. It's not a deliberate conspiracy to make you hang up. TL:DR - phones connections are optimised for transmitting speech and rubbish at music."
],
"score": [
10
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b6cadm | The difference between the degrees and the warm/cold settings on a split system air-conditioner. | Long time lurker, first time poster to ELI5. Apologies if I haven't titled this correctly. & #x200B; I am working in a small office today and we have set the air-conditioner to warm and 22C. But my co-worker and I questioned what is the difference between 22C warm and 22C cold. We just thought 22C is just 22C. | Technology | explainlikeimfive | {
"a_id": [
"ejjf67j"
],
"text": [
"Warm=keeping room temp above set temp Cool=keeping room temp below set temp The temp you set the thermostat to isn't necessarily going to be the room temp, it's just the temp that activates the system."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b6cdtb | How did we reach a point where there are 2 and just 2 major types of phones (iPhone and Android)? | Technology | explainlikeimfive | {
"a_id": [
"ejjfv1f",
"ejjil3b",
"ejjgzy8",
"ejjfum2",
"ejjgx9p"
],
"text": [
"The problem is that software ecosystems are a *winner take most* game. If I have to write an app for each model of phone, I can't afford to write 10, so I ask \"which phones are most popular?\" Having lots more apps makes them ever *more* popular, reinforcing their dominant status, and making competitors hopeless.",
"Apple hit a home run with their smartphone. Everyone else tried to copy but failed. Then Google released Android and gave it away to all the other companies. That allowed them to get into the smartphone game and not have to be a software company too.",
"If you're classifying by OS, then there's only 2 major types of consumer PCs, 3 if you include linux. OS's are massive works of software, there's never going to be that many fully fledged products.",
"Symbian was too slow and have app support. And don't get me started on Windows se and phone is terrible. Edit added m to symbian so we could keep conversation clean",
"You'll find that many consumer technologies come out in multiple formats and then get winnowed down to one or two. Sometimes the best technology doesn't win. 1. VHS vs Beta 2. Windows vs Mac 3. Blu-ray vs HD-DVD 4. XM vs Sirius The winner is the one who can acquire the most support for their product. VHS was able to win consumers on price and quantity of titles. Windows is beating Mac on pricing and flexibility. Android is making the play as Windows - more handsets with greater modability than iPhones."
],
"score": [
57,
16,
14,
5,
5
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6cj5m | how does a charger charge your phone for a split second after it was removed from the socket? | Technology | explainlikeimfive | {
"a_id": [
"ejjh99k",
"ejjh1i7"
],
"text": [
"Do you think because the icon shows charging that it is actually charging? Or the software just hasn't updated the screen yet?",
"It contains a *capacitor,* a little power holding device, which is loaded up with power from the outlet. It takes a moment to finish unloading into your phone."
],
"score": [
10,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6cny8 | Is there a reason why it using more than two powerful graphics cards together doesn't have a drastic increase in gaming capabilities? For example, 4 2080Ti GPU's running together doesn't seem to give four times the gaming power. | Technology | explainlikeimfive | {
"a_id": [
"ejji2nv"
],
"text": [
"You are not running a program that efficiently utilizes the 4 GPU cards, they're like $1000 each. This is likely because very, very few people buy that configuration. The game is better optimized for typical hardware."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b6efj4 | Why did rotary phones exist before buttons? They look needlessly complicated. | Technology | explainlikeimfive | {
"a_id": [
"ejjvf6a",
"ejjviw1"
],
"text": [
"Basically it was a method of sending a signal on the line indicating who to call, before we had the technology available to use tones. Same as with any older tech. An old floppy disc has moving parts. An SSD doesnt. Most would say the SSD is more complicated though. Your iphone is more complicated than a rotary phone as is a push button too.",
"It's actually a very simple design for what the phone needed to do. When the landscape was moving from a human-mediated system to a computerized one, the big question was how do you determine what numbers are being sent? How does the system know what number you're trying to call? As it turns out, a really simple solution was to send pulses of electricity (hence the name \"pulse dialing\") down the phone wire to indicate what number was being dialed. How do you get pulses in a predictable pattern? By using your finger to select the digit, then have the dial smoothly return to its zero position."
],
"score": [
8,
7
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6fxb5 | How does a single LED produce multiple colours? | Technology | explainlikeimfive | {
"a_id": [
"ejk4b9m",
"ejk4goy",
"ejk7di5"
],
"text": [
"They don't. Each LED junction can only produce one wavelength, in fact, LEDs are famous for their narrow bandwidth. When we want a multicolour LED, what we do is embed a red, green, blue (and optionally white) LED junction on the same device very close to each other. By mixing the amount of these 3 colours, we can convince our brain that it's actually a single colour.",
"Normally, a single LED does not produce multiple colors. However, multiple colored LED chips can be integrated into a single LED package.",
"I'm sure you mean things like these. URL_4 Where it appears it's a single unit and it produces many colors. But if you look at the diagram on the bottom it has 4 wires. It uses that to switch the between three colors and their intensity. This makes up all the colors we see. It's also called a RGB LED. So what that means is that it has the ability produce Red Green and Blue light. If you look on the manual specifically here you'll see it has the ability to produce these colors. URL_0 URL_1 So if you look here URL_3 * Red ~ 700–635 nm * Orange ~ 635–590 nm * Yellow ~ 590–560 nm * Green ~ 560–520 nm * Cyan ~ 520–490 nm * Blue ~ 490–450 nm * Violet ~ 450–400 nm The Led is really good at producing bright Blue, Red and Green colors and less good at producing the in between especially yellow. As you can see it's kind of really bad from the graph at producing yellow. But when you look at this picture it's indeed yellow. URL_5 But when you look in more detail using a measuring tool. It's actually producing more of a really light green with some red. Your brain gets fooled by the LED since it's emitting both red and green so it sort of merges into yellow. Currently more of our technology uses a RGB spectrum mostly because of the physics of LEDs. And we're honestly used to it because our CRT TVs worked mostly the same. But say printers again because of physics use a different configuration. They use this. URL_6 cyan, magenta, yellow, and key. Key standing for basically \"back\" to darken things. So while an OLED RGB display under a microscope looks like this. URL_2 ()/ URL_7 A printed piece of paper looks like this. URL_8"
],
"score": [
247,
20,
10
],
"text_urls": [
[],
[],
[
"https://www.pololu.com/file/0J133/XLMDKCBDBGA107M.pdf",
"https://puu.sh/D6u2a/1f8a8a7b16.png",
"https://cdn.vox-cdn.com/thumbor/jpP5dKW2T5mYt9tvOvm9EzTRfzM=/0x0:2040x1360/1200x0/filters:focal(0x0:2040x1360):no_upscale",
"https://upload.wikimedia.org/wikipedia/commons/c/c4/Rendered_Spectrum.png",
"https://www.pololu.com/product/1074",
"https://a.pololu-files.com/picture/0J921.1200.jpg?e20ea36efb61d8a0ded305f8b6a47442",
"https://en.wikipedia.org/wiki/CMYK_color_model",
"cdn.vox-cdn.com/uploads/chorus_asset/file/13316251/bfarsace_160118_3014_iphone_XR_0003_vrt.jpg",
"https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/CMYK_under_a_microscope.jpg/1280px-CMYK_under_a_microscope.jpg"
]
]
} | [
"url"
] | [
"url"
] |
|
b6j73e | how can one speaker produce multiple sounds at the same time? | Technology | explainlikeimfive | {
"a_id": [
"ejkpnef"
],
"text": [
"The sound your ears hear and the brain processes is always a combined waveform of many sounds all at different frequencies and pitch. The brain the processes them and can pick out timbre, pitch, and volume and deconstruct them so you can pick out the violin or trumpet from an orchestra separately. A speaker is doing the same But I guess backwards. Sending out a massively complex waveform so combine the sounds. Also many \"speakers\" have more than one driver \"speaker\" and so actually do send out separate sounds. Like your 5.1 setup at home. The subwoofer is sending out a different sound wave to the left front which is itself different to... etc"
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b6kv4d | How is a heart transplant possible ? | I mean, during a heart transplant I assume there's a moment where the patient's heart is removed to be replaced, how can the person survive without a heart ? | Technology | explainlikeimfive | {
"a_id": [
"ejl2dpt",
"ejl2tom"
],
"text": [
"Their blood is \"re-routed\" through an external pump while the hearts are being swapped out. Your heart is basically just a pump. As long as \"something\" is pushing the blood through the other vital organs you can live without it (for a while anyway)",
"They use a technique called \"cardiopulmonary bypass,\" which is a mouthful, so it's often just called \"bypass.\" The patient is hooked up to a machine that pumps blood for them, so that the heart can be safely operated on until the problem is solved and it can be reconnected to the body's blood supply. So for the period of the surgery, the heart is being \"bypassed\" thanks to this machine, and blood can keep flowing through the patient's body. The rest of the body doesn't care much what's doing the pumping, as long as oxygen-rich blood is flowing."
],
"score": [
5,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
b6ov0s | How do astronauts communicate with the planet Earth? | Technology | explainlikeimfive | {
"a_id": [
"ejm1ent"
],
"text": [
"The main way is by radio, in the S-Band and the Ku-Band. These are bands of frequencies that can be used to communicate, the S Band is typically used for Radar and things, but also includes Wi-Fi and microwaves, and the Ku Band is used for satellites (like the ISS!). A few dozen ground stations around the earth can be used to communicate with the ISS. The internet can then be ran over this radio communication. But there is another way to communicate with the ISS - Amateur radio! Many Astronauts operate Amateur radios when they aren't working, like the weekends."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b6risy | How do sports video games simulate matches against each other during a season or tournament mode? Is it completely random or based on some sort of algorithm? | Technology | explainlikeimfive | {
"a_id": [
"ejmwih2"
],
"text": [
"Could you clarify your question a little? Are you talking about the AI within the game (throwing balls, passing, etc.) Or are you referring to the actual selection of teams that will be combated against each other? Edit: I'd be happy to explain either, it's just I'm on mobile so I'd like to be more concise and avoid excessive typing. Edit: Back from class now. Several games may do this differently; they may have weighted probabilities when teams combat each other and use RNG and selection of optimal outcome on these probabilities to get a result when not directly observing a game (i.e. you tap play and get a result instantaneously). Some AI, even when you hit \"skip\" on the appropriate prompt, may still perform the search problem below, especially if it's optimized for efficiency (For example, a Sudoku puzzle with the maximum number of blank squares without there being duplicate solutions can still be solved within milliseconds by an AI designed to do so). But anyways, If you were to observe a full match between two AI, you need to understand some things about how AI agents work and the search algorithms they might use. AI agents are defined by a goal, or end state, and have an environment that they observe through sensors and observed game measurements, which may or may not be omniscient in nature (in a sports AI, they likely are. i.e. they know the full state of the game at any given moment; where the ball is, all observed quantities of the game, where every single player is at a given moment), and a way of interacting with that environment, or actions they can perform. There are a lot of different methods to writing an AI. They use a search algorithm and could use a performance metric (or a way of measuring how close they are to an end state, like distance from the goal line, number of moves an opponent can take at a given moment to put them in check (or vice versa)). They could also follow a constraint satisfaction problem to help them reduce their search space (but still running a search on the next best state). An example of this would be like if you were solving a Sudoku problem, its obvious to a human that if a 1 were in a square of the puzzle, then a 1 could not be in the row, column, or sub-box of that puzzle. This could be extended and changed to follow sport models. Depending on the environment type (a chess AI would be drastically different from an AI trained to play soccer in a video game) and how optimized the search is, an AI could make a small change, measure if they're closer to their end state after that change, and take it if they are, and don't take it if they aren't, and then restart. Other AI might perform purely off of probabilities, where they take the action that is most likely to get them closer their end state, rather than measuring a concrete metric that we discussed earlier. Both agents would repeat these techniques until a terminal state is found. The probabilities could be weighted by a specific sports players stats, like speed, strength, etc, or specific types of strategies that the AI designer might select. E.g. if a team were to run a lot of pass plays, even if they weren't optimal, this could be weighted in decision selection. So how does this relate to our sports simulation? Just think of an AI player as a search algorithm, who uses a bunch of techniques to repeatedly try to get to a goal. Two AIs competing against each other are just reacting in sequence to one another. Source: Studying computer science and taking a 400 level class on Artificial Intelligence."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b6s8j8 | Advancements in audio technology have led to the development of incredible microphones, speakers, etc. We also crank out new generations of cell phones. Why do cell phone speakers and microphones sound like phones from 30 years ago? | Technology | explainlikeimfive | {
"a_id": [
"ejmr9bo",
"ejmrgrs",
"ejmrjow",
"ejmrc1w"
],
"text": [
"Great minds think alike. I've searched tha seven seas fer an answer. Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why, in the modern age of \"HD\" obsession do phone conversations still sound like you're listening through a tin can? ]( URL_5 ) ^(_ > 100 comments_) 1. [ELI5: Why the audio quality of phone calls still suck even though it's 2014 ]( URL_0 ) ^(_14 comments_) 1. [ELI5: Why is a phone call audio really bad but a Skype call is really clear? ]( URL_2 ) ^(_13 comments_) 1. [ELI5: why is the sound on cell phone conversations still so bad in 2019 when compared to a hard line ? ]( URL_6 ) ^(_10 comments_) 1. [ELI5: Why is facetime audio so much better than phone call audio? ]( URL_3 ) ^(_3 comments_) 1. [ELI5: Why does phone voice quality still suck, while Skype and FaceTime sounds like the person is right next to me? ]( URL_1 ) ^(_ > 100 comments_) 1. [Eli5: why does FaceTime Audio call sound so much clearer than regular calling? ]( URL_4 ) ^(_8 comments_) 1. [ELI5: Why in the era of HD quality video do phone conversations still sound like two cans connected by a string? ]( URL_7 ) ^(_ > 100 comments_)",
"They do sound better than 30 years ago. Play music or record voice and play it back. It is much better than 1989 cell phone audio. What doesn't sound much better is the call audio. That is due to the high compression used by mobile phone carriers.",
"Mostly because they're tiny. Speakers work by displacing air, microphones by measuring how displaced the air is. On larger speakers and microphones, they're able to easily push air/be pushed by air without much distortion or noise. Cell phone speakers/mic's are minuscule in comparison, so have trouble measuring/reproducing lower frequencies, and produce/record other frequencies with more noise and sometimes tinny results.",
"They don't? Do you mean the audio quality when calling someone? That's because communicating through actual calls *hasn't* really changed in the last 30 years. But as you can quite clearly tell if you ever call someone through VoIP, or just watched a youtube video, speakers and microphones are much better on newer phones than older ones. The hardware of cell phones isn't the bottleneck."
],
"score": [
5,
3,
3,
3
],
"text_urls": [
[
"https://np.reddit.com/r/explainlikeimfive/comments/22ihh5/eli5_why_the_audio_quality_of_phone_calls_still/",
"https://np.reddit.com/r/explainlikeimfive/comments/2qmmfh/eli5_why_does_phone_voice_quality_still_suck/",
"https://np.reddit.com/r/explainlikeimfive/comments/30p38d/eli5_why_is_a_phone_call_audio_really_bad_but_a/",
"https://np.reddit.com/r/explainlikeimfive/comments/3zu5pm/eli5_why_is_facetime_audio_so_much_better_than/",
"https://np.reddit.com/r/explainlikeimfive/comments/3yqcvt/eli5_why_does_facetime_audio_call_sound_so_much/",
"https://np.reddit.com/r/explainlikeimfive/comments/1lq7dn/eli5_why_in_the_modern_age_of_hd_obsession_do/",
"https://np.reddit.com/r/explainlikeimfive/comments/b55iob/eli5_why_is_the_sound_on_cell_phone_conversations/",
"https://np.reddit.com/r/explainlikeimfive/comments/2aybud/eli5_why_in_the_era_of_hd_quality_video_do_phone/"
],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6vomm | How do services like 23 & me know who your ancestors are? Do they somehow have access to the DNA of people long dead? | Technology | explainlikeimfive | {
"a_id": [
"ejncba1",
"ejnf1na",
"ejnitiq",
"ejnew53",
"ejnoeb7",
"ejnhnnw"
],
"text": [
"They (sorta) do. Genes are weird and complex things. There's the obvious ones - hair colour, eye colour and the like - but there's also some that only have subtle effects, or none at all. Importantly, some of the genes have small mutations in them. Some of these mutations are only seen in certain populations - Mutation #4829, for instance, might only be found in Greece. We can analyse these mutations to work out where your genes are from.",
"They \"estimate\" your ancestry by comparison to a reference dataset. They created the reference dataset using DNA from people that have evidence to support a claim that their families lived in a region for a very long time. It's very neatly explained on their website [ URL_0 ]( URL_0 )",
"I did one of these a little over a year ago. Came back with a big surprise of Scandinavian, 28%. Everything else made some sense, although not exactly the percentages I expected. Earlier this year, they said they 'improved' the system. Radical changes. The Scandinavian was gone, and all of the percentages of everything else shifted wildly. Talk about making me skeptical. What's worse is that before they showed the new results, they required a survey about what surprised me in the old results, and what I expected to see. Boom, new results are much closer. I mean, as entertainment it was a talking point for the family on both occasions. But kind of frustrating to realize they don't know what the fuck they are doing, and any accuracy they have now is probably built on the guesses of participants.",
"Kind of sort of, but what they really have is access to a lot of genetic information about people living right now, coupled with biographical information about those same people. So they can trace back genealogy through both biological means, and social means (things like immigration records, personal histories, etc.). They also have what we consider to be a basic understanding of the origin of certain genetic markers, and they can then correlate other markers with existing ones to see how well they line up to support or refute current theories of genealogy. With decent algorithms, and robust database software, they can refine what they know on both the social side and the genetic side as more information becomes available. As long as they're starting out with decent data, and their algorithms do a decent job incorporating new data, their assessment of genealogy for most people will be more or less accurate.",
"They don't know who your ancestors were, they can tell where they came from by comparing your DNA to DNA from a sample of population from a particular region. So if your 10% Irish what they're saying is that 10% of your DNA is similar to the DNA of people who are Irish",
"I was an early participant in one of these services. I was taking a university class on genealogy. For extra credit, we could submit blood samples and our family trees. There was also a questionnaire about family history, country of origin, etc. This was during the late 90s. The company collected thousands of these samples and personal histories, laying a foundation for their future database. After what I presume were millions of samples, that database is now quite robust. They compare your genome to other known genomes and give a fairly accurate estimate of your personal heritage."
],
"score": [
54,
19,
16,
5,
3,
3
],
"text_urls": [
[],
[
"https://www.ancestry.com/cs/dna-help/ethnicity/reference-panel"
],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6w3t5 | How does a phone make itself vibrate when a call or text comes in? | Technology | explainlikeimfive | {
"a_id": [
"ejne351",
"ejne4ny"
],
"text": [
"There is a small motor that spins with an off-center weight that make the phone vibrates. So when someone calls the motor activates and the weight makes the phone shake that we feel as vibrations.",
"there is a thing called a vibrator motor inside the phone. its a motor with a mass at the end that spins around making the phone vibrate. if you want to see one go to the youtube channel jerryrigeverything. he takes phones apart and do durability tests."
],
"score": [
12,
6
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6wdcg | Why are records still made of vinyl? I know they're more of a collector's item nowadays, but haven't we invented any materials that are more durable or would otherwise be better for the job? | My boyfriend is really into records and he's tired of me pestering him about this. I've heard that records used to be made of something called shellac and then it turned into vinyl around the 1930s. But that only caught on when they started using lighter needles that didn't damage the record. It's almost 90 years later now, haven't they made a material better suited for the job? Maybe something that's more durable so they don't scratch as easily, for example. Edit: I'm adding this because it seems to be coming up in the comments a lot: I am well aware that CDs and other digital media (mp3s, Spotify etc) exist. What I'm curious about it the reason why vinyl is being used for the big black records my hipster boyfriend likes. | Technology | explainlikeimfive | {
"a_id": [
"ejnhfet",
"ejnj4co",
"ejnq13r",
"ejnikvd",
"ejngsds",
"ejnhvjg",
"ejnpb0f",
"ejngoub",
"ejode3b",
"ejo4p64",
"ejnj957",
"ejoas3k",
"ejnutlt",
"ejpx1j9",
"ejon3zy"
],
"text": [
"Audio for records is recorded to a surface that is scratched, then a mold is made, then a metal cast is made, called a master, then that metal mold is used to press vinyl into the shape of the recording. Vinyl is used because it is easier to get a good copy of the mold without sticking to the metal. It's just cheaper and easier, and lasts long enough that most people don't notice the quality degrading. Edit: a couple of people have objected to me leaving out an electroplating step. I will say, my explanation is basically correct. I am not an expert, this is ELI5, one part of the casting step used is electroplating, the terms used vary widely. The part I called a master, is also called a couple of other things at the same step. Enjoy the ELI5 it is technically correct, the best kind of correct, and terms differ in use.",
"I can't quote any of it well enough, but look up \"Adam Savage Third man records\". Adam goes to Jack White's record printing shop, and they explain why vinyl is still used. Super interesting watch. & #x200B; [I'm feeling generous]( URL_0 )",
"I haven't seen a good response that actually talks about the properties of vinyl, so I'll give it a shot... The reason vinyl is still used is because it is really perfectly suited to this task. It's cheap, readily available, very consistent, easy to mold, and most importantly - it's very quiet as a medium. We have stronger plastics, sure. But getting that clean impression from the stamper is important and vital for getting a record that sounds good. Old shellac records were noisy - lots of hiss, the surface was as good as it could have been for the time - but it's still not great. Not to mention, heavy, brittle... shellac was a lousy material for records. Enter vinyl - it's soft, flexible, and durable. Vinyl, as a material, is incredibly stable. It does not break down, and it's immune to most chemicals. I remember a forum post years ago where a guy tested various cleaning products on a Milli Vanilli album, in an attempt to see what could dissolve it. He eventually did find something - but he did find just how hard it is to chemically damage vinyl. This is also why records pressed in the 60's still sound perfect (assuming well cared for) - the plastic is long term stable. Vinyl is very durable. Despite the fact that it can be easily scratched, it stands up to the weight of the stylus well, and an album can be played thousands of times on properly set up equipment without degrading. It's also very flexible - you can hold a vinyl record and \"wobble\" it back and forth and it won't damage it. Sure, you can break a vinyl record, but it's kind of hard to do this accidentally. It survives shipping well. The surface of a vinyl record is very quiet, because the material is so smooth and soft. Making a record out of something like polycarbonate - the stuff they make CD's out of - would function, but the hard, brittle plastic would likely be very noisy, and it would probably be susceptible to the grooves chipping and breaking. Despite the fact that the stylus tracks at only about 2 grams, it's very tiny, and a diamond. The pressure at the tip is actually pretty high. Shellac and vinyl are NOT the only materials that were used for records. Polystyrene was also widely used. This is what they made most 45 RPM records out of, back in the 60's and 70's. Hold one up to the light - if you can see reddish through it, it's polystyrene, not vinyl. This is a hard, brittle plastic somewhat like polycarbonate. These records perform poorly, and wear out quickly. The surface is noisier than vinyl, and the grooves don't hold up to the stylus like vinyl does. This material was used for 45's not because it was cheaper - but because polystyrene can be liquefied and injection molded. This meant that the stampers didn't wear out as fast, so they could crank out more records with less overall costs. They wore out quickly, but - 45 RPM singles were viewed as disposable, and sold cheaply. The wear problem was known at the time, and sometimes they would make vinyl runs of the same single for jukebox and DJ use.",
"So people are talking about the quality of vinyl's sound, but I don't think that is the main factor at play really, as audiophiles are too busy spending money on daft cables to rebirth the vinyl industry. The reality is that vinyl still exists because it faded from popularity, this meant it was cheaper for underground scenes like punk or techno to press records and sell their music because the pressing plants weren't being used by the major labels any more. So no one invested any money (or progressed the tech) because no one was making any real profit or seeing any real market interest outside of tiny niche scenes. Fast forward a few years and vinyl is now super cool again and getting money invested in it, i'm sure in the next few years there will be alternatives, especially as needle-less turntables get better. Similar things happened/happening with cassettes but on a much smaller scale.",
"Due to the biggest advantage of Vinyl being that it is an analogue recording of the sound, the biggest issue is any record material needs to be light enough so that the recording needle can actually scratch down all the fine nuances and details of an audio recording yet also be durable for multiple playback. I'm no expert but I would imagine that there are few materials that can fulfill both criteria, too heavy of a material (like an ultra durable composite polymer) would not be able to adequately be abraded to capture the fine details while something light like Shellac has obvious disadvantages. If RnD persevered, I would imagine they would've refined the medium to some kind of composite polymer in the end but with the advent of CDs, it was not financially viable to keep refining analogue records so Vinyl kinda stuck.",
"Also, you want a material that doesn't damage the needle, so something soft but stiff. Vinyl does that well. Shellac is actually brittle, and flakes off easily. The very first records were was, which has obvious problems. If you made aluminum records, the needle would flake and chip, and wear out quickly.",
"There really can't be because there's no real scientific criteria by which one can assign a set of objective \"wants\" or \"goals\" where vinyl is ideal in the first place. In other words, if you want to say \"this would be better if...\" then it's always been true that the way to address that \"want\" would be simply to not use vinyl at all. Side-stepping the obvious digital-analog debate, not only is vinyl not the ideal analog format for audio, but vinyl records aren't even the highest fidelity point in the analog CHAIN that leads/led to making a vinyl album. When a band used to record a song in the studio, (before the digital age) the sound WASN'T laid down on a vinyl as they sang, it was laid down on analog TAPES, like these: URL_0 It was from these tapes that editing and such was done and tracks overlapped and then a final master tape made and then, finally, was it mass produced onto vinyl. So a vinyl recording can never be better than the quality of these tapes to begin with. Because THEY are the \"original\" sound \"as it was intended\". And of course, the reason for such tapes is that, as analog formats go, their fidelity is much HIGHER than vinyl. They more faithfully capture the sound (that and one can do multi-tracking). And in that case there is a down-grade when pressing to vinyl and of course an uncompressed digital format could produce higher quality reproductions of the contents of these original tapes than vinyl can. But people want vinyl BECAUSE it's a kinda nonsensical status item. From an engineering perspective there's no rationale. Like I said, if people wanted as exactly close to the original recording as possible, they'd ask for direct copies of the studio tapes. Sure, they're deeply impractical for consumer use, but in the modern day so is vinyl, so it's a meaningless point. But people don't want that. So could we make a vinyl with a different resin or what have you that would scratch less? Sure. But to what end, assuming vinyl lovers would even accept them as \"authentic\"? What is one trying to accomplish? If one tries to get specific then the answer is going to be \"oh, yeah, sure, we can fix that, just use this \\* non-vinyl \\* format\". EDIT: Another way of putting it is, despite the rhetoric that vinyl-lovers say, what they are really looking to purchase is a historical replica. Is a historical replica \"improved\" by using a new modern-age resin? (I mean, new vinyls are undoubtedly made using non-historically authentic polymers, but crucially vinyl-lovers don't really know that or, because they haven't really internalized their like for the product in that way, haven't really thought about it in that way for it to diminish their enjoyment of the product).",
"Vinyl is another name for PVC (Polyvinyl chloride). PVC is the world's third-most widely produced synthetic plastic polymer, after polyethylene and polypropylene.",
"We still make houses out of wood and brick. And knives out of steel. Tires have been rubber since they’ve existed. And we still drink out of glass. It’s hard to improve on some materials.",
"Probably get buried, however vinyl is really good for music because of fundamental limitations. Music cannot be pushed too loud, inconsistent bass is difficult and seldom cut in stereo, digital top end is somewhat softer. In my opinion the flaws and limitations of the material directly contribute to the positives of the medium.",
"No, they haven't made any materials better suited. Mainly because the market has mostly moved to digital storage, so there is not a high enough financial incentive to do the research and development it would take to find such a material much less the cost to rebuild the infrastructure to make records in the new materials. Secondly PVC is still one of the mostly widely used materials on earth that has gained more uses over the years rather than being replaced, so its not like the material is in trouble of raising in cost due to lower demand for mass manufacturing.",
"I am going to come off as a bit pretentious, so fair warning. That being said, here we go. 1. They did invent a more durable material. Plastic. The CD and DVD were far denser and could fit higher quality audio. A vinyl does not have the same quality audio as a digital file. That is impossible given that a needle record player is an analog player and a CD player is digital with a laser. Vinyl was replaced by a cheaper, volume alternative. 2. Vinyl is experiencing a resurgence, however, because of what I am about explain below: 1. That being said, people like Vinyl because of the AESTHETIC of the needle brushing on the imperfect nooks and crannies of ever valley in the record. Because of Vinyl's imperfect method of being made, no two records will sound 100% alike and this gives a uniqueness that CDs or DVDs can't come close to. 100 CDs will all sound the same. 100 Records will have unique imperfections in sound that make it your record. You notice certain parts of the track because of the way the needle rubs your vinyl. Vinyl was never improved because CDs were so cheap to make, the music industry moved on to higher profits. And as I said above, Vinyl's imperfections give a distinctly different sound that audiophiles love for its uniqueness and special properties (scratching noise).",
"This is just an opinion on my part but I think it makes sense... The biggest reason that vinyl records still exist is because of nostalgia and audio purists think the sound of vinyl is the best. If you change the material, you'd be taking away the core reason why vinyl records are still made to begin with. If you take that away, you take away the market and there's no need for records anymore anyway.",
"Can we get one answer that does not talk about why vinyl is good? Can someone speak about a a better material without comparing it to vinyl? We know vinyl is good, but what is better?",
"Why is vinyl used? ease of pressing, comparative durability, single materials used, cost effectiveness, shelf life and the fact it doesn't harbor mold. A wax cylinders often became unreadable due to mold. Shellac records broke and required fillers. Has more durable materials been invented? yes. Why haven't they been applied. 1) Cost - they're more expensive. You can use assorted resins to make records but they're quite expensive and would require a lot more steps and you would require a vacuum chamber. There is a video on the most expensive way to steal music where a youtuber makes a crude casting of a record using modern resins and a silicon mold. 2) difficulty of production - production of a record is stamping a puck of soft vinyl on a master which is simple, cheap and fast whereas say a polyester resin casting would require multiple molds, degassing chambers, curing racks to product a single record and time for curing in mold. 3) this is a revived technology. It has been revived skipping over it's digital replacement, which was more durable, in part due to a desire to interact with a physical medium instead of a blinking screen. People want it so companies make it."
],
"score": [
6502,
1873,
1434,
206,
204,
60,
44,
16,
8,
5,
5,
5,
4,
3,
3
],
"text_urls": [
[],
[
"https://www.youtube.com/watch?v=PF4A4wdnXkU"
],
[],
[],
[],
[],
[
"https://www.recordingthemasters.com/audio-tape/"
],
[],
[],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
b6wmms | How do over the air transmissions (tv,radio) know how many are listening/watching to gauge the popularity/success of songs/programs? | Technology | explainlikeimfive | {
"a_id": [
"ejnik3z",
"ejniqwp",
"ejnjwh1"
],
"text": [
"They don’t. However polling, streaming services, and in home devices like the Nielsen program allow statistics to be computed and extrapolated to the larger population set.",
"They don't. Broadcast companies pay to group of people (hundreds or thousands of people) to record what they are listening or watching right now. They then have sample of what are people watching/listening more on which they estimate how many people are watching/listening across whole country.",
"Upvotes for both of you! That seems crazy to think if that wasn't tested properly they could be broadcasting to no one or tons of people. In addition it would be hard to quantify pricing structures for advertisment. Obviously the more listeners/watchers the more advertising is going to cost. Very interesting guys thanks!"
],
"score": [
16,
8,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6x2x3 | How do aquariums keep their water so clear without burning or killing the animals with chlorine or other chemicals? | Technology | explainlikeimfive | {
"a_id": [
"ejnkhpf",
"ejnl5tw",
"ejnkhg7"
],
"text": [
"Filtration, there are a lot of different styles of filters but basically you run water through them and they pull out the nasty stuff. You also do regular partial water changes. You may even have cleaner snails/shrimp in their eating the stuff that can nasty up a tank.",
"Most aquariums have a quite good filter system. With this i don´t mean just the pump you conect to the power. At first you have plants in the aquarium. The fishes feces contain many nutrients. The plants take these nutrients out of the soil and grow. Second you have the filter system with the pump. mostly it has a sponge like filter in it. This sponge contains many microorganisms that again take up the feces and change them to energy they need. This is why you need to have the filter run for a couple of weeks before you put fishes in the aquarium. In this time the microorganisms start to grow and florish, so that the can absorb the bad nutrients in the aquarium. And third: Because this is mostly not enough to keep the water compleatly clean, you have to put out something from time to time. This is calles a water change. With this change you get rid of most of the rest. & #x200B; If these things don´t work properly you see this pretty fast. The water gets dirty and alges are spreading.",
"As long as it's well-lit and there isn't a lot of dirt, the water should remain fairly clear. They have fish or other aquatic creatures that like to each algae that tries to grow, which prevents the tanks from getting grungy-looking as a result of algae buildup."
],
"score": [
12,
7,
5
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b6xci9 | In an episode of "That 70's Show", one of the characters modifies the game "Pong" so the paddles were smaller by tinkering with the hardware of the console. Would this have actually been possible? Was there no software involved in the earliest computer games? | Technology | explainlikeimfive | {
"a_id": [
"ejnnhqx"
],
"text": [
"Yes, Pong was entirely in hardware. It was notoriously complex; schematics were provided in some cases, but extremely hard to read and spotty. A huge amount of the circuitry was devoted to handling the vertical & horizontal sync of CRT screens; this formed the basis of the logic for the rest of the machine. This means that the size of the paddle was bound to the horizontal sync of the screen. The paddle got split into 16 squares; 16 is 2^4, a number which was pretty much enforced by the timer chip used by the game. It used 4 wires to track paddles, each of which can be off or on. It'd be possible to halve the size of the paddle by disconnecting one of those wires; but then your scanning would be interrupted. Making this kind of change without totally fucking everything up would be tricky, but possible."
],
"score": [
17
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b6xcu3 | Why are number keypads on keyboards and phone dialpads oriented oppositely? | Back in the day when one would actually have to dial telephone numbers I would suddenly be an idiot with Parkinson's and end up dialing gibberish numbers to nobody I knew. | Technology | explainlikeimfive | {
"a_id": [
"ejnozzx",
"ejnmu3t"
],
"text": [
"PC keyboard number-pads were made to mimc calculators/adding machines that had been used by accountants and the like for nearly a century. Nobody knows why the adding machine layout is the way it is. If there was a reason, it's lost to history. When the Touch-Tone® telephone keypad was in development, Bell Telephone Laboratories did an [intensive scientific study]( URL_0 ) of various possible keypad layouts, making wooden models and bringing in test subjects to see how they liked the layouts and timing them as they entered test numbers. They tried, among other things, a round layout that approximated the then-familiar rotary dial, and a two-by-five stack. One of them (I-A) was similar to the calculator/computer layout. > Notice that the arrangement frequently found in ten-key adding machines (ar- rangement I-A, Fig. 3) was not the best of the first three arrangements compared. On the other hand, the same geometric configuration with a different numbering scheme (arrangement IV-A) was superior in keying performance when compared in Group IV. However, the performance differences between the two were small: arrangement I-A had an average keying time of 5.08 seconds, and arrangement IV-A had an average of 4.92 seconds. At the time the study was conducted, of course, adding machine/calculator use was a relatively rare and specialized skill. Something that only accountants and clerks would have much familiarity with. Layout IV-A is the one that \"won\" and which we all use today. As a bonus, the way the three-by-three-plus-one layout was wired up using rows and columns gave rise to the *️⃣ and #️⃣ keys on either side of the zero; they were essentially \"free\" to implement since the circuitry was already there. They became useful once IVR systems were introduced.",
"The theory I have heard is that telephone keypads are based on the layout of a rotary telephone. On a rotary dial, 1 is at the top right and zero is on the bottom. When designing the new touch-tone keypad, putting the 1 on the top-right didn't make much sense, because Western writing is read from left to right. But putting 1 on the top-left, and the subsequent numbers to the right, did make sense. Using that formula, the resulting rows fell into place, with zero getting its own row at the bottom. Keyboard keypads, however, are based on the old adding machine styles, where 1 is on the lower left hand corner."
],
"score": [
21,
5
],
"text_urls": [
[
"http://www.vcalc.net/touchtone_hf.pdf"
],
[]
]
} | [
"url"
] | [
"url"
] |
b6y6va | Why is it impossible for the phone company to identify the origin of a call? | (edit) I'm sorry for wasting everyone's time. I genuinely find it absurd that the phone company is completely out of the loop in our technological era where the human genome can be tinkered with, missiles can be launched to other planets, and my cable company knows in seconds if I try to stream Law and Order from a hotel in Canada. I should have asked "why is the world so vehemently opposed to the idea of a trustworthy phone system." I regret asking this here and you should feel no pressure to reply. Have a great day everyone! & #x200B; & #x200B; I pay the phone company for my phone line. They know who I am and where I live. They shut it off when I stop paying. I presume that this is true of other users of my and other telephone networks who are permitted to place and receive calls. Why, then, is it impossible to stop spoofing and spam/scam/fraudulent/nuisance phone calls? Does the phone company really have no way of knowing where the other end of the wire is? (whether or not they choose to reveal that information to me) | Technology | explainlikeimfive | {
"a_id": [
"ejntxfp"
],
"text": [
"Phone numbers are not unique to people, they are easily changed if desired and can't be used to clearly identify who placed a call (only who is currently registered to a number, assuming fake information wasn't used). Managing a system to identify and block spam/scam/etc would take more time and resources than the current system and wouldn't add enough benefit to increase profit margins, so there's no incentive for this to be done. Spoofing is a method that exploits how phone technology works that tricks companies into misidentifying callers."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b6zfd9 | What happens inside the computer when you, for example save a word document onto the hard drive? | To rephrase it, how does a computer store data? What is the process?? I know the computer reads binary numbers but when you save a document, does the CPU recognize it and then sends the signal to the hard drive? Thank you reddit | Technology | explainlikeimfive | {
"a_id": [
"ejo54sk"
],
"text": [
"There's a pretty big difference in recording data on a hard drive and a solid state drive/flash drive. For a hard drive, there are several magnetic platters stacked on top of each other, for maximum data storage. The platters are spun at high speeds (7200RPM) and a read/write head floats over the platters. When I say float, I mean it. The airflow generated by the spinning platters creates enough lift to keep the read/write head from impacting the platter. It actually 'floats' a few nanometres from the surface of the platters, which is a TINY distance. Getting the read/write head as close to the platters as possible allows for more compact data storage. As for what's actually stored on the platters, the platters are ferromagnetic so the read/write head applies magnetic force to the platters while they're spinning to record binary data. Where there's a magnetic spike, it's a 1. Where there isn't, it's a 0. The CPU doesn't actually send all these signals to the hard drive; the hard drive has a integrated circuit built in that keeps track of where the data is stored on the disk and the instructions for the read/write head to move back and forth. When you save a document, there's a copy in RAM while you're working on it and when you save it (and select a destination) the CPU sends the relevant information from the RAM to the hard drive. The hard drive then performs all the instructions above."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b6zi6p | Why are camera lenses round instead of the same shape as the photo they produce? | Technology | explainlikeimfive | {
"a_id": [
"ejo87qw"
],
"text": [
"Lenses typically use spherical surfaces in order to not get any distortion. Historically, the easiest way to do this is to use a round piece of glass when grinding the lens. This is the same reason many early eyeglasses have round lenses. While you could then cut the lenses into a rectangular shape, there isn't really an incentive to. The savings in material cost wouldn't be huge, and aligning the lens to the sensor would require extra precision. As we moved towards casting lenses rather than grinding them, the saving in materials cost still isn't enough, and we're used to circular lenses. There is one situation when rectangular 'lenses' are used instead: plenoptic (hologram) cameras. These cameras use an array of tiny lenses, right next to the sensor. The way that they work means that the need to be perfectly aligned, and it is cheaper to make it the right size to begin with. So a rectangular array is made, rather than the traditional round lenses."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b702c0 | How do album remasters work? | How do good remasters have such a huge difference in quality while using the same recording? | Technology | explainlikeimfive | {
"a_id": [
"ejo8yks"
],
"text": [
"Mastering is just transferring the final mixed tape onto a new media for sales (vinyl, CD, cassette). & #x200B; The original recording tapes for the album are very high fidelity and sound quality. Assuming it's not going to be re-mixed, they will transfer the original tape sound onto a new master. If the process of mastering has improved (or was originally not done well the first time), you can probably get a better sound out of it. & #x200B; This is similar to films. If you've ever wondered how films from the 1950's can be 4K, it's because film is incredibly high quality. It's already 4K quality when it was recorded, but, for example, VHS video tape is nowhere near 4K. It was the equivalent of 480 at best (VHS wasn't digital so it doesn't directly translate to digital resolutions). So a film from the 50's gets mastered onto VHS and it's x quality. Then DVD's come out (720p), and that movie gets re-mastered to DVD at higher quality (but it's still lower quality than the original recording), then Blu Ray comes out (1080p) and it gets remastered to that format. & #x200B; If there's an audio format improvement, the originals can be remastered to it to give you a better quality sound than previous releases on old formats or mastering techniques."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b70vtb | Why do records sound better than digital? | So I recently got into collecting vinyls, and I’ve always heard people say that they provide higher fidelity audio quality. I am running my turntable through a Bose speaker, but even if I play the same song off Spotify right after I play it on vinyl, it doesn’t sound nearly as rich, even through all the clicks and pops. Don’t get me wrong, the Bose makes them both sound great, but on vinyl it sounds like band is right in the room with me. Why is this? Why doesn’t digital provide as rich of a sound as records? I understand a little bit about bitrates and stuff, but you’d think technology would have provided something better quality than 50 to 100 year old pieces of wax by now. | Technology | explainlikeimfive | {
"a_id": [
"ejom8wb",
"ejofjo0"
],
"text": [
"> I’ve always heard people say that they provide higher fidelity audio quality That is actually false. Digital can provide higher fidelity than vinyl. People will say that vinyl can \"exactly reproduce\" the sound wave and digital is necessarily \"choppy,\" but neither one of those statements is true. Any analog recording still has physical limitations - something still has to physically \"carve\" the waveform, and it's limited by the equipment and the medium. Vinyl has to be smoother than the actual sound wave can be, and the result is that can't capture high frequencies or sudden changes. Furthermore, the recording is degraded with every playback, as it is physically worn away. As for digital, it is true that it can't perfectly reproduce a waveform. HOWEVER, *it can perfectly reproduce a signal within a given bandwidth*. This is [mathematically proven]( URL_0 ). So yes, with a sampling rate high enough, you can **perfectly** reproduce all components of the sound within the range of human hearing. You might lose subsonic and supersonic components, but you can't perceive those anyway. And if you did want to capture them, you could arbitrarily extend the bandwidth you are capturing (so your dog can't tell the difference either), and it would simply make bigger file sizes. In short, the difference you hear between vinyl and high quality digital is because the *vinyl* is imperfect. If it's \"better,\" that's because subjectively you prefer those imperfections to a more accurate recording.",
"Vinyl is a direct transfer of the sound waves to the disc. There isn't any conversion other than sounds waves to physical motion. Digital files are a conversion of the sound into a series of numbers. At it's core, it's a record of the volume and time of a part of a sound wave. No matter what bitrate or other factors come into play, it's still an estimation of the sound. Streaming services will use lower bitrates in order to save bandwidth, so they'll sound worse automatically, similar to how a radio broadcast of a song can't stand up to a CD playing the same song. & #x200B; Now, whether or not the difference is actually audible on a given set of equipment in a double blind experiment is another issue."
],
"score": [
14,
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem"
],
[]
]
} | [
"url"
] | [
"url"
] |
b71ob0 | what even are GPUs? are they just floating point processors? | I'm gonna be honest, I know just a little because I write code that takes advantage of floating point stuff for calculations, but any explanation of how it works on the hardware level was always so hard for me to understand | Technology | explainlikeimfive | {
"a_id": [
"ejorcfc",
"ejownf3"
],
"text": [
"Fundamentally, they're \"just\" processors, the same as a CPU. However, they're processors that are designed specifically for 3D graphics workloads, rather than general-purpose computing. So what does this mean in practice? One point is that 3D graphics are what's known as an \"[embarrassingly parallel]( URL_1 )\" problem — because each individual pixel in the resulting image can be computed in isolation from all other pixels, you can get a lot of benefits from investing in higher levels of parallelism (sort of, but not exactly, \"more cores\") instead of faster speeds. In practice, an nVidia RTX2070 has the same TDP (spends the same amount of electric power) as an Intel i9-9980XE, has over 5x as many transistors, but only 0.3x to 0.5x (depending on turbo boost, etc) the clock speed. In much the same vein, reading data from memory is very important for all workloads, but it's extraordinarily important for 3D graphics (reading 3d meshes, reading textures, etc), so GPUs use extraordinarily high bandwidth memory — again, about 5x higher throughput for the RTX vs the i9. Inversely, the sort of programs GPUs were designed to run are very straightforward, and have much fewer \"if this, then that\" decision points (\"branches\", in the jargon) than a general-purpose CPU will see. This means that GPUs can afford not to have branch prediction built in, which is one of the biggest components in modern CPUs (and at the core of last year's [Spectre/Meltdown]( URL_0 ) attacks). Finally, the difference you were talking about — a very _very_ large portion of the work load for 3D graphics is linear algebra (matrix multiplications, essentially). This naturally means that GPUs are designed to be very very good at performing that sort of numerical task, above and beyond what regular CPUs do.",
"Mathematicians figured out that if you can represent coordinates or objects changing in 3D space (moving, rotating, scaling, etc.) with matrices and a bunch of matrix multiplications. If you see CGI with a lot of details, they're really just billions of tiny colored triangles. To move them on the screen, the computer needs to multiply all those coordinates with transformation matrix. GPU is pretty much a piece of hardware that specializes in matrix multiplication. So, the faster you can process floating points, the better the GPU (in a way) Floating points is basically software-way to say numbers with decimal points"
],
"score": [
19,
6
],
"text_urls": [
[
"https://meltdownattack.com",
"https://en.wikipedia.org/wiki/Embarrassingly_parallel"
],
[]
]
} | [
"url"
] | [
"url"
] |
b73io9 | how does a timer work on really small, usually cheap , electronic items? | Technology | explainlikeimfive | {
"a_id": [
"ejpro5b"
],
"text": [
"In general there are 2 types of clocks in use today: 1. RC oscillator. This is usually integrated into an integrated circuit, and usually has something like 2% accuracy. So it is sufficient for running a system that doesn't require very precise clock frequencies. It is ultra cheap and reliable. 2. A crystal oscillator, usually 32.768kHz for timekeeping. This frequency is chosen because if you divide it by 2 fifteen times, you will get 1 second. Crystals can be designed to have extremely high accuracy. Typical accuracy for use with timekeeping clocks is around .0001%."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b73mgf | How do bugs in video games pop up in a certain function when the developers update a completely unrelated feature? | Thought about this today as Minecraft got another snapshot where the devs added/fixed some features with villagers, but there’s a bug where texture packs can’t be changed. How can this happen? | Technology | explainlikeimfive | {
"a_id": [
"ejp2i0n",
"ejp5r1e"
],
"text": [
"Because programs are very complex. And video games are even more complex. Code, especially code worked on by entire teams, can get pretty spiderweb-like. Tiny changes in one thing can cascade into bigger and bigger hiccups elsewhere, even when seemingly different systems are interacting. A messy interaction between two systems can cause bugs in a third system because that third system somehow cares or needs some point of data created by the other two systems; if they dont work properly, the third one doesn't get the right info, and bugs appear. It's really hard to explain without examples, because every bug is pretty unique in what causes/caused by it. This is why they can be so hard to isolate and then fix, and why it's frustrating to hear people shouting \"just fix the bugs!\" - it doesnt work that way. And programmers can't perfectly predict every possible bug from the start, *and* a lot of bugs you see in games don't show up frequently enough in the internal testing, and only start appearing once the game is released to the wider world. [A good example is this thorough explaination of what causes the Missingno glitch in the origional Pokemon games.]( URL_0 ).",
"Think of all the different components of making a game, or any software at all, and how they might interact. You have the textures, but they have to be mapped on to a 3D model that represents a block, or your character or a monster, or an NPC like a villager, then you have the animation of how the 3D model moves, and then the AI that works out when those modes move, and where. Then you have the code that deals with your input (mouse clicks, scrolling, key presses), and the code that deals with the game state (where you are stood, what item you have equipped, what items you have in your inventory, your level, your experience points), and much much more. All these different pieces work together to give you the game that you play. But in order for that to work, they have to talk to each other. Some parts are more tightly ‘coupled’ than others, which means they talk to each other more, or rely on each other more. So there are a lot of dependencies, and potentially pieces of data being passed across the entire application So if you change how the data in one part is computed, and that is sent to different parts of the program to help compute other things, but those parts weren’t expecting different data, you get bugs! Because they weren’t programmed to handle this new data that it’s never seen before. Or, the change you made removed some data that another part was expecting, then the other part would break too. This can be caused by anything, because programming is hard. There are so many things that might depend on areas of the game you are editing, that you might not be aware of, and program for. And unless you sit and test every aspect of a game after every new feature, you never know."
],
"score": [
7,
3
],
"text_urls": [
[
"https://www.google.com/amp/s/kotaku.com/pokemons-famous-missingno-glitch-explained-1653929141/amp"
],
[]
]
} | [
"url"
] | [
"url"
] |
b73vb3 | how does wifi work on transport? | So I understand that the WiFi in my house works from the router. Which is then a mainline to somewhere else. But how does it work on planes. Train buses and anything else that moves? | Technology | explainlikeimfive | {
"a_id": [
"ejp2q4a"
],
"text": [
"They have routers too. Which is simply connected usually via sattelite to \"somewhere else\""
],
"score": [
9
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b754g9 | How does URL_0 (aka Google), manage it's storage and bandwidth costs when thousands of videos are uploaded and stored daily? Do the advertisers actually cover its costs? | Technology | explainlikeimfive | {
"a_id": [
"ejpeymo",
"ejpqddt"
],
"text": [
"Do advertisers actually cover the costs? Yes. That's the business model of google. That's how they set their prices. How does google do it? They have a lot of infrastructure, and a lot of smart people working for them who spend all their time at work coming up with ways to reduce the amount of bandwidth used, and the amount of computation required to produce results. They've built their whole company on this kind of technology, and they're among the best companies in the world for dealing with huge data sets, and storing them safely and efficiently. It's the reason that Google the search engine was able to out compete it's competitors in the early days. In most cases, it was better at finding related results, and faster too. Edit: A couple of people have pointed out that Youtube is loosing money, but that Google as a corporation is able to cover the loss.",
"YouTube is actually losing money now. I guess Google, as in the search engine, has enough ad revenue to make up for it."
],
"score": [
61,
10
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b7ckl1 | Why do the vast majority of online forms consider apostrophes and hyphens invalid characters? | I have an apostrophe in my last name, and 9 times out of 10 when I’m filling out an online form I’ll get an error message saying I’ve entered an invalid character. I’ve been told people with hyphens in their names encounter the same thing. Why is that the case? Is it just lazy programming? How easily can it be fixed? | Technology | explainlikeimfive | {
"a_id": [
"ejqs6dc",
"ejqn44s",
"ejrauch",
"ejqzy0s"
],
"text": [
"For a long time, the people who built forms online spent a lot of time trying to create rules that would keep out bad data. Anecdotally, this was often driven by the presumption that human users were likely to fill out forms incorrectly, more than it was about preventing naughty people from exploiting weaknesses in the application for malicious purposes. That's not to say that those vulnerabilities didn't exist, it's that (for better or worse) people weren't concerned about them. Speaking from experience, a lot of people didn't even know about them -- including among \"hackers.\" Today, everybody in the business knows what a SQL injection attack is; that was not true in 1993. & #x200B; For example, you're building a form so that people can register to attend a seminar. Someone probably says \"make sure the FirstName field doesn't allow spaces, otherwise some idiot will just type their whole name into that box.\" That rule bakes in all kinds of assumptions about names, assumptions which are false even in the Western culture in which this rule is common. But, if you didn't know that, you'd go ahead and write that rule. Now everybody who uses the form has to live by stupid rules designed by ignorant people. Also, one way to implement that rule is to say \"a name can only be letters.\" Boom: suddenly, in addition to preventing spaces (which was the goal), you've also just forbidden dashes, apostrophes, periods, and probably accented characters. Also, programmers make mistakes, so sometimes the effective rule ends up being different (and more restrictive) than was even intended. & #x200B; Some other common validation rules that are foolishly inflexible and unimaginative: \\- ZIP codes must be exactly 5 digits \\- phone numbers must be exactly 10 digits, formatted like \"(xxx) xxx-xxxx\" \\- state must be a two-letter abbreviation & #x200B; These things mattered, because the consumption of data was typically crude and unforgiving of errors. Very often in the '90s, data collected by web forms was stored in a database so that it could be used to do things like printing addresses on envelopes for mailers or produce telephone directories. Sometimes, badly-entered data might just produce an awkward result, such as when \" < LastName > , < FirstName > \" yields \", Bob Ross\". But often, the consuming system would choke on the bad data, because it was not built to be forgiving, and the linkage between the two systems was not fault-tolerant. & #x200B; Consider a web form that students use to register for classes, which is used to (1) send registration information to the state's central database as well as (2) printing out a class list for instructors. And imagine that one student from Canada has a six-character ZIP code that includes letters. That might not be a problem for the printed class list, but if the state database chokes on that 6-character ZIP code, the entire process would stop immediately: records after this one aren't sent to the state, and *no class lists get printed at all*. When this happens, you've got everybody from the college president on down, yelling at you for creating an administrative catastrophe on *day 0* of the semester. & #x200B; Finally, storage space and processing speed was a much bigger concern back then, and one result is that databases were designed to fit the data like a skin-tight wetsuit. These days, when I can buy an SD card the size of a thumbnail that holds 32 gigabytes, it seems absurd -- we often make every text field unlimited length: a first name can be 2000 letters long and we don't care because it's free and easy. But back then, you'd have serious debates with someone about whether you could literally afford to set aside 20 or 30 letters for first names. I've been doing this for 20 years, and I cannot count the number of times somebody said this in a meeting: \"okay, but what is the *longest* first name you've ever seen?\" Yes, we had the technology for unlimited-length database fields, but using them often came with a performance cost. A lot of web applications back in the day were just web pages that showed the content of a database as a giant HTML table. It took a long time for the computer to scan the entire database, then loop through every row and produce the HTML, and then to send that whole thing to someone's computer over a 14.4 modem. Imagine a webpage that takes 35 seconds to load. I am not kidding you, this was the reality back then. A lot of these applications were running on a single physical computer that one guy built from parts he got at the local store, and now it's sitting under a desk in the office. & #x200B; TL;DR: crude technology and brittle software patterns created really strong incentives to design very rigid rules for data entry. Those rules were designed by flawed humans who often failed to recognize their own ethnocentrism, especially in a culture that was less diverse and inclusive than today. & #x200B; EDIT: Thanks for the gold, kind stranger!",
"When data is stored, different databases use characters such as Apostrophe, Hyphens, Pipes \" | \" , to separate fields. Think of it as Microsoft Excel. Instead of having the grid line to separate fields of data, the system uses a special character. ------- If you type in the following: - First: *Johnny* - Middle: *Doe* - Last: *Smith* The system will store it as something like: - *Johnny, Doe, Smith* ------ Now if you filled the form out like this: - First: *John,ny* - Middle: *Doe* - Last: *Smith* The system will store it as: - *John, ny, Doe, Smith* You now have 4 names coming through when the system anticipates 3. This confuses or breaks the system. ------ This can cause errors such as: - Your name would come back as \"John ny Doe\" - Next person's first name returning as your last name \"Smith\". Due to overlapping. - System Crashing or Breaking.",
"Is it just lazy programming? The vast majority of the time the answer is yes. It can also be fixed very easily in 99% of situations. Why don’t they just fix it then? Glad you asked, even if you didn’t. They don’t fix it because companies tend have huge backlogs of work that need to be addressed. That form that doesn’t accept apostrophes is working and delivering data as intended so there’s no cause to prioritize fixing what isn’t technically broken from a business needs standpoint when they need to fix things that actually don’t function or build new things to meet new needs.",
"A form that asks for a name would limit your input to normal alphabetic characters just so you don't send anything invalid, missing the edge case where a name has a hypen or apostrophe. I wouldn't call it lazy so much as they didn't consider this specific situation. If something was programmed particularly badly, apostrophes in input could cause an error if submitted, but this is almost never the case."
],
"score": [
120,
15,
9,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
b7crko | How does the transmission speeds across twisted pair cables keep getting faster with each new category (Cat5, Cat6, Cat7, etc...) When it is still essentially just four twisted pair copper cables? | See title. | Technology | explainlikeimfive | {
"a_id": [
"ejqqken",
"ejqyy2t",
"ejqpobf",
"ejrvdeb"
],
"text": [
"The copper cables themselves haven't really changed much, but the insulation between them and shielding around them reduce interference and noise. The data doesn't get from one end of the cable to the other any faster, but you can squeeze it tighter without electrical interference mucking it up by the other end. Think about listening to someone talking really fast in a quiet room versus in a noisy public space or over a crappy phone, the clearer the connection, the faster they can talk and still be understandable.",
"Different cable types have different electrical properties, more isolation from outside noise and other wires in the same cable, etc. However, in terms of their use for Ethernet, the Ethernet wire protocols are radically different. That's why there's a negotiation when you first plug them in, to decide on 10/100/1G/10G, etc. and why the newer protocols are cutting backward compatibility in some respects (no half-duplex, no hubs, etc. in the new versions). That negotiation isn't just \"I'll talk at this speed\", it's an entirely different modulation, and newer speeds use all kinds of techniques rather than just what the lay person would consider ordinary bit-banging. Twisted pair was originally used so that the white-pair-partner for each coloured cable inside (green, blue, brown, orange) would receive the exact same interference as the wire it was twisted with. That lets you \"remove\" noise by subtracting the signal of the respective white wire from the signal of the colour it's twisted with. But things have got real messy since and most of the protocols now use a lot more clever tricks, a lot more wires in tandem, entirely different modulation on the line (not just \"on-off\" but phase modulation of the signal, quadrature modulation, higher frequencies, entirely different error correction, more levels of modulation (so not just, say, 2 different voltages, but 16 or more different levels that it can detect and use to send/get more data at the same speed). Basically each one of 10/100/1000/10000 uses almost a whole new wire protocol from scratch. Don't forget, these are \"modems\" still - they are modulating and demodulating a digital signal onto an analogue carrier, so depending on the accuracy of the equipment, they can measure and control much smaller changes in phase, voltage, frequency, etc. and thus send more data. No different to the way that your telephone line only ever supported audio at one point, which meant that you had to use the audio frequencies to send data only, which meant that traditional \"voice\" modems were limited to 9600bps for years, then 33.6K (or 56k in one direction if there was special hardware at the telephone exchange) but now that same cable uses more way frequencies than just the audio, over shorter distances (e.g. 10G needs Cat6a for 100m, but you can use Cat6 if you only want 40m, etc. while you home cable only has to go to the street to get onto a fibre connection to Internet, not all the way back to the exchange and then physically cabled to your destination phone line) , with entirely different modulations and protocols, much more signal processing capability both at home and at the telephone exchange, and now stays OUT of the audio range... so you can do DSL over the same two-pair copper cable you've had for 50 years while being on the phone (or even dialling up a modem, in theory!). The biggest change is really being able to put a 500MHz or so processor at one end, and extreme amounts of accurate signal measuring at both ends, for the cost of an DSL router from the local electronics store. Or, in this case, processors in network cards/chipsets/switches/routers routinely capable of handling 10Gb/s on every single port they have without even needing the main CPU.",
"Different technology. Twists per inch, insulation, shielding, materials. Newer manufacturing can cost more to make the cable, but allow things not possible 20 years ago.",
"Twist rate and modulation scheme... To name a few things. Also, wire gauge. As electrical frequency increases the electrons want to stay on the *surface* of a conductor. That is, you can have a very massive copper wire and at DC, the electrons will travel all through the wire from edge to center. But increase the frequency and those electrons won't be found in the center anymore. They want to be near the outside of the copper. We call this the **skin effect**. Even though you might have a 26 AWG wire, the effective size of that wire at 1 GHz, for example, is much smaller so resistance is higher. Think of it like a water hose with a partial plug in it... You won't get as much water through like you will have more cable losses as frequency increases. So IEEE and other organizations will periodically increase the wire thickness to compensate for the skin effect as we use higher frequency signals. Modulation schemes change too. For 1000Base-T I believe they are using a PAM3 or PAM4 encoding scheme. Basically what this means is that you can fit 3 or 4 bits into 1 bit-time. We think of bits as 1s or 0s, but what if you could send a +0.75V for a 00, a +0.25V for a 01, a -0.25V for a 10, and a -0.75V for 11 for example? You still only need to send 1 voltage level at a time but you get 2 data bits out of it. The problem is that now there is only 0.5V difference between one symbol and a different symbol where before maybe you had 1V for instance. Voltages and currents can be affected by outside **noise**, which Engineers sometimes call **crosstalk**. Another downside is that the silicone chips making and receiving these signals need more layers of complexity to work because they have to decipher many more symbols than a simple chip that either detects a voltage or no voltage - this increases cost of the components. We don't like crosstalk because it can make one symbol look like another. One way to combat crosstalk is by adding more twists in the cable. This is yet another way that CAT cables are different with higher category cables generally having more twists per length. Im not sure how to explain *why* in ELI5 style but just know that if noise is emitted from one conductor in a pair, the neighbor conductor will cancel the noise because of the twist. The closer and more uniform the twists, the better the cancellation. But again, increasing twists can make it harder to produce cable and increase costs so you can't just have cable with tons of twists in it and expect perfect results."
],
"score": [
1306,
76,
4,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
b7diz3 | How do open world games go without interstitial loading screens? | So if you’re playing a typical non-open world game, every time you lose a life or enter a new area, you have to sit through a couple minutes of loading screens. How do open world games circumvent this, to create a seamless experience as you transition from one area to the next? Is an open world game continually “streaming” data off the disc/hard drive/cartridge and dumping unneeded assets from RAM on the fly? | Technology | explainlikeimfive | {
"a_id": [
"ejqx8z8"
],
"text": [
"Yes, that's exactly what it is doing. The open world is split in to sections, and only the section the player is close to is loaded. You notice if you die in open world games it will take a bit of time to load the area you respawn in."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b7l4rs | How did people accurately (air pressue changes due to weather) determine mountain hights before the use of GPS? | Technology | explainlikeimfive | {
"a_id": [
"ejsj6y2",
"ejskl2e"
],
"text": [
"Mathematics. Primarily it involves measuring the angles and then complex math. It's more complicated than that but basically a tripod mounted telescope called a theodolite. It wasn't perfect, but if you can figure out some angles,then comparing to other spots on,the mountain. As for air pressure, you used basically what amounts to tools that were pressurized at ground level and then comparing how the pressure on it changes as you go higher.",
"A vast amount of mapping was done using a device called a theodolite - this is a device that can very accurately measure the angle (against North) and inclination (the vertical angle) between two points. If you start out with two points that you have measured the distance between, and you know the altitude of, then by using the theodolite to measure the angle and inclination between each of your known points you can use a bit of trigonometry to determine the height and distance of the new point compared to your two starting points (and if you know the altitude of your starting point, you can figure out the altitude of the new one). If you then repeat the process with one of your original points, and the third point you just figured out, you can determine the height and location of a fourth point. Then you can use any two of your four points to spot a fifth point... Keep doing this and you can keep mapping points as far as you want - and eventually you can reach the peak of a mountain to figure out the exact position and location. One other system is to use barometric pressure to determine altitude change. Because pressure drops as you gain altitude, if you measure the pressure at a starting point, by moving somewhere else and comparing the pressure, you can do a bit of maths to figure out the altitude change. Unfortunately the overall pressure in an area will naturally change over time as the weather changes, so if there had been a big change in the weather between your two measurements then the result will be thrown out as that change in weather will be counted as an additional change in altitude. This can be limited by doing things like taking a measurement on the way up the hill and another on the way down and averaging them, getting two people to take measurements at the two locations at the same time or other tricks. Nowadays we have modern satellite locations systems like GPS which allow us to locate position far more accurately - these have resulted in us being able to remeasure quite a few mountain heights to get a more accurate answer and update our mapping."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b7lawi | how do software based random number generators produce truly random numbers? | Technology | explainlikeimfive | {
"a_id": [
"ejskcw8",
"ejsjek4",
"ejsjisb",
"ejspa22"
],
"text": [
"They don't, usually. They use what's called a pseudo random number generator (PNRG). The idea is to use an algorithm so close to randomness you can consider it random. The trick is that PRNGs are \"seeded\" with a value that is likely to be unique, like the number of milliseconds since 1970. Or you can use a measurement of the heat of a processor which has some thermal noise associated with it. Which is about as random as you can get.",
"Some use the CPU’s internal clock as a source for an algorithm that calaculates a random number.",
"A computer currently cannot produce a truly random number. Computers need a predictable pattern to do anything.",
"So, others have discussed Pseudo-Random Number Generators. These take in a \"seed\", and output almost random numbers. But this isn't the whole story. If you chose the same seed every time, you'd get the same numbers. What a good PRNG needs is called 'entropy'. Entropy is, effectively, random data (in this context). It's the pure amount of random bits in the 'seed'. For example, you might use the temperature of a room as the seed; the value 20.3412341°C is not entirely random, as you'd expect the temperature to be relatively stable - the 20°C is not at all random, even if the .3412341 is. But good PRNGs don't have a single seed, but instead pool this entropy from multiple sources. Things like keyboard and mouse timings, network interrupts, and video data can all be used as sources of entropy."
],
"score": [
15,
5,
4,
4
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b7nlcp | How are music files so small when the state of the waveform is saved 48000 times per second? | Technology | explainlikeimfive | {
"a_id": [
"ejswi4g"
],
"text": [
"MP3s are compressed lossy files. This means that when the files are generated from the original, there is a setting in the algorithm that allows one to set the 'quality' or size of the resulting file. The files don't contain the original data, but details of what the original data was. Wikipedia does a good job describing MP3 files: URL_0"
],
"score": [
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/MP3"
]
]
} | [
"url"
] | [
"url"
] |
|
b7oagb | How do military planes target? | How does a plane (like an A-10) target and fire with such accuracy so high up at such a fast speed? Is there a guy on the ground shining a laser at the target? Satalites? An on board targeting system? A mixture? Is it anything like this video (ARMA 3) URL_0 He's using it drop a JDAM, but it's pretty much the same for strafing runs (in the game). Is it at all like this? | Technology | explainlikeimfive | {
"a_id": [
"ejt1pxf"
],
"text": [
"A-10 in neither fast and can not operate at high altitude compared to fighter and even bombers are faster. It is designed for ground attack so it is rather slow and optimized for low level operations. & #x200B; If you a computer game to compare too look at videos from DCS it is a simulator that attempts to be close to reality. & #x200B; If you a targeting pod like in the game that is likely a [LITENING targeting pod]( URL_0 ) . It has a laser designation that shine a laser on the target. JDAM initially was GPS and inertial guided to a target but some later variant have laser seekers too. GPS can hit tagets covered by clouds and you do not need a laser pointed at the target the whole time but you cant hit a moving target with it like and it can be jammed. Laser can hit moving targets and is a lot harder to jam but clouds or smoke will block the laser and someone/something need to points laser on it so both have te advantages and disadvantages You see real video from targeting pods from the invasion of Iraq of 2003 at [ URL_1 ]( URL_1 ) & #x200B;"
],
"score": [
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Litening",
"https://www.youtube.com/watch?v=XFj6f9L827A"
]
]
} | [
"url"
] | [
"url"
] |
b7q2gq | Why are there so many hackers and bots from East Asian servers on many games? | PUBG, CSGO, APEX LEGENDS, FORTNITE and a lot of other games have people complaining about hackers on their subreddits. Those people who complain are mostly from East Asia and I believe most of them are from China. So why are there son many hackers from China? Can't people from EU or NA also hack or create bots? | Technology | explainlikeimfive | {
"a_id": [
"ejtqeud",
"ejtezwn"
],
"text": [
"Not a complete answer, but something to consider is that there are just a lot more people in general in East Asia. Even if they had the same rate of hacking, you would be very likely to encounter East Asian hackers compared to Western/European ones.",
"In China as in other Asian countries it is common for there to be \"online cafes\", organizations which rent access to gaming PCs rather than people owning them themselves. As an incentive for customers to patronize their shop over others many offer cheating programs on their machines to \"improve\" the experience of their customers. Why this isn't seen as outrageously dishonest and is a plus for the shop rather than a death sentence comes down to the culture, where getting ahead by screwing over distant, unrelated people is seen as normal. There just isn't as much importance placed on fair, honest interaction as in Western cultures."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
b7t6s6 | how do wireless chargers work? | Technology | explainlikeimfive | {
"a_id": [
"eju2ybc"
],
"text": [
"The charger unit contains a coil of wire that basically forms one half of an electrical transformer. The other coil is in the phone. Varying current in the first coil creates an alternating magnetic field through the coil centre. The phone's coil sits on top, and the varying magnetic field through it induces an alternating current in that coil. A bit of electronics takes that and charges the battery."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b7uz07 | How are some IG accounts selling "verification badge" like the celebrities own? | I've been seeing a lot of people claiming they sell verification badge and actually own one themselves despite not having a lot of followers nor being celebrities. How are they doing this? Is this legit? | Technology | explainlikeimfive | {
"a_id": [
"ejuiuqo"
],
"text": [
"From what I've been reading, Instagram is almost giving those things away for the asking, so most likely they are just applying for them for you the legit way knowing that they will almost certain be fulfilled for you. In other words, you could do it for yourself for free, but most people don't know that, so they are basically just charging you an ignorance tax."
],
"score": [
9
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b7vmxt | Why does Iron Man’s armor in movies look faker than it did a decade ago? | Technology | explainlikeimfive | {
"a_id": [
"ejujcgg",
"ejuko8i"
],
"text": [
"Because it’s supposed to be hyper-futuristic these days. When the iron man series started in the mcu, it was meant to look more current and semi-possible. For example, in the first movie he slows down with air breaks, large broad surfaces that are meant to create drag. But now he does it with micro thrusters.",
"Armor upgrades, with more unrealistic, comic-realistic Iron Man suits CGI plays a far more intricate part in showing the suit and blending it with the real world. What made the original Iron Man so iconic was how gritty and possible everything was like story, plot and characters were so grounded while now since everything is connected and time has passed they need to show that. Cant have Iron Man flying in space and dealing with magic without blending it all to look cohesive (imagine Stephen Wolf from DC, good ex of CG that didn't blend well with real life so it looked bad/weird). But honestly it still looks amazing and super realistic, just not the same"
],
"score": [
15,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b7w115 | How does calling 911 work in terms of connecting you to your closest 911 center? | Technology | explainlikeimfive | {
"a_id": [
"ejukyi0",
"ejuuzro",
"ejuk6bu",
"ejuknub",
"ejukwt0"
],
"text": [
"The emergency 911 call is routed to the local call center based on the origin location of the calling party. If it was from a landline then there is obviously a registered address where that phone is calling from, but if it is a cell phone then it is determined by the location of the cell tower. Since such towers generally have a range of about 5 miles (conceptually longer but on average they are within 5) this is a reasonably accurate estimate of the caller's location. If it happens the address of the emergency is just over the line to a different 911 center's territory they can quickly and easily transfer the call to that other center.",
"911 operator here When you call 911 your call is answered by a PSAP (public safety answering point) where they ask “do you need police, fire or ambulance?”. Often, but not always, the PSAP is the police department, so if your emergency is a police matter, you will stay on the line with the same call taker (although this is not the case if the PSAP is an agency other than police of course). If it is for fire or ambulance, they will downstream your call to the designated service provider in your area. In terms of the location, your call is directed to the nearest call centre based on what cell tower your call bounces off of if you call from a mobile phone, and if it’s a landline then the address of the phone line will determine the call centre. Sometimes there are mistransfers and sometimes calls are dropped so that’s why it’s important to know exactly where you are. Important note here too: often non emergency numbers are answered by the same call takers as the 911 lines. 911 lines are a priority line so it’s so important to not tie up these lines if you do not have an emergency. If you have a routine question or complaint, call non emergency, NOT 911. it could be the difference between life or death for someone with a genuine emergency.",
"I’m not sure if my question is confusing so to elaborate — Each individual with a phone has a unique number. If I dial my mother’s phone number, there’s no way I’ll be connected to someone else. So how does calling 911 work? Everyone in the US dials the same number but it can be connected many, many different 911 centers?",
"As I understand it, calling 911 connects you to a call center that then puts a call through to your closest emergency service officer (or at least one in your area).",
"Your local telecom provider automatically routes your call to the closest 911 dispatch center. For older systems this was based on the central office code of your phone number (The first 3 digits of your 7-digit number). Newer systems use the central office code for landlines, and geolocate mobile phones based on what cell tower they are accessing."
],
"score": [
14,
7,
4,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b7w701 | Do modern fax machines make that screechy dial up noise out of necessity or is it something it is programmed to do for consistency/familiarity? | Technology | explainlikeimfive | {
"a_id": [
"ejulkbd",
"ejulrgj",
"ejuo1ub",
"ejuyh78",
"ejv28a0"
],
"text": [
"No, they do it because it is still the protocol for talking over the telephone line to the other fax machine. The tones are actually what is being transmitted over the line and being able to hear them might help with diagnosing a problem with the fax.",
"They do still need to make the noise to communicate the call being answered. Most newer fax machines don't need to have the sound audible to the user, only to the other fax machine over the line. Source: was a Photocopier tech and repaired faxes too. Our main fax guy would usually have the sound so he could confirm that the machine was communicating properly on our end.",
"The person hearing the dial tone, the numbers being dialed and the connection sequence is only for user confirmation, you hear it being sent. There is usually an option to silent dial, but the people wouldn't be sure if it's being sent. Kind of like a gun being racked or the hammer being cocked back before use in a movie, it let's the audience know it's a loaded gun.",
"It needs to make that noise, because that's the data transmission. That said, there is probably an option to turn it off so you won't have to hear it, but, then again, you won't hear if you dialled the wrong number and a human is answering, and risk the fax retrying several times, making said human downright irate.",
"The fax machine needs to send and receive that screech noise over the telephone line. It's the fax machine equivalent of saying \"hello, I'm a fax machine and I have some pages to send, am I speaking to another fax machine?\" and getting back \"yes, I'm a fax machine too, please send me the pages\". But, if everything goes well, there's no need for the fax machine to play that sound out of it's speaker, so you don't need to hear it. And you can usually turn it off in the fax machine settings. However, if something goes wrong, it can be helpful to hear it. For example, if you hear your fax machine making the screech and then a human at the other end going \"hello is anyone there?\" then you know you've dialled a voice telephone number instead of a fax number, and you can either hang up or pick up the telephone on the fax machine (if there is one) and say \"sorry, can I have your fax number please\"."
],
"score": [
20,
11,
6,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b83qf4 | How do radio staions find out ratings? | Technology | explainlikeimfive | {
"a_id": [
"ejvowc9",
"ejvpdzh"
],
"text": [
"It used to be a journal that you filled out saying what station you listened to and at what times. Now they have a pager like device that you carry with you, and that will pick up the secondary signals the radio stations send out. This lets them know exactly what station you are listening to, at what times, and for how long.",
"Nielsen tracks this, mostly using a device called a [ portable people meter]( URL_0 ). Its like a small pager-like device that listens for radio. This is how it works in most big markets. It listens for what radio is on wherever you are (its not big brother, it only hears specialized inaudible tones embedded in the signal for just this purpose) In smaller markets, they use journals/diaries that people manually fill out to say what they listened to. Yup. They attempt to get an appropriate sample size and appropriately diverse people, (i.e. a representative sample) and from there extrapolate out. The people meters are considered pretty good, the diaries are considered complete trash, but nonetheless, right or wrong, this is the currency used for ratings."
],
"score": [
3,
3
],
"text_urls": [
[],
[
"https://imgur.com/sfBP3yG"
]
]
} | [
"url"
] | [
"url"
] |
|
b859w6 | What is the difference between "Frames Per Second" (FPS) and "Refresh Rate" (Hz)? | Technology | explainlikeimfive | {
"a_id": [
"ejvx8bx"
],
"text": [
"Refresh rate - how often the screen itself is refreshed. It is completely independent of frames per second since you still have refreshes even with a static image. & #x200B; FPS - How many frames per second of a moving picture are displayed."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b896ls | Why is it that when rotors spin and increase speed, there is a point where they look to slow down and change direction? | Technology | explainlikeimfive | {
"a_id": [
"ejwk5b7"
],
"text": [
"It's an effect termed 'spatial aliasing'. Imagine you've got a rotor spinning 30 times per second. Now, what happens if you take a picture of that rotor 30 times per second? If you think about it for a moment, you'll realize that every one of your pictures will have the rotor in the same position - the interval between when you're taking the pictures is exactly enough to allow the rotor to fully rotate one time. Now what happens if you take pictures slightly faster than 30 times per second? Well, your rotor doesn't have enough time between pictures to get fully around. As a result, each subsequent picture will have the rotor positioned slightly behind the previous one. If you imagine these successive pictures as instead a film, playing your 'film' will make the rotor appear to spin backwards."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b8d4yh | How do technological devices that use magnets not ruin the circuits within the same device? (E.g Airpods, laptops.. etc.) | Technology | explainlikeimfive | {
"a_id": [
"ejxak12",
"ejxi7wm"
],
"text": [
"TLDR: Because the magnets aren't strong enough to cause a problem, and the sensitive parts of the devices are shielded. Magnets damaging electronics is not false but it is a bit of a misnomer. For instance putting a fridge magnet on the side of your computer case isn't going to wipe the hard drive. It just isn't powerful enough to do that. The commonly held belief of magnets being bad for computers comes from the days of using magnetic media like Floppy Disks and Tape. These media were very sensitive to magnets. CRT monitors could also be damaged by exposure to magnets. While modern spinning disk hard drives are still magnetic, they are shielded to a degree to prevent exposure. They actually have several powerful rare-earth magnets inside of them that help the device function. But given a powerful enough magnet they too will get damaged. For most electronics magnets and electro-magnets can generate EMF (Electro Magnetic Interference) which can have negative effects on electronics. But this requires magnets that are particularly strong compared to what you typically see in devices these days, and most sensitive electronics have shielding like Ferrite beads that help filter out the pulses.",
"Because magnets do not(*) disrupt electrical circuits. This misunderstanding came about because magnets *do* disrupt storage devices like hard disks and tapes that store information on tiny magnetized particles. These devices used to be very common, but nowadays we use SSDs and flash memory that are basically immune to magnetism. \\* This isn't technically true, magnets *can* affect flowing currents, but the effect is too weak to mess up everyday electronics."
],
"score": [
6,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b8fjiy | Why does the picture in the view finder and the final photo change when we rotate out cameras from vertical to horizontal ?? I mean, camera lenses are circular.. it shouldn't make any difference as to the way we hold our phones.. | Technology | explainlikeimfive | {
"a_id": [
"ejxkfki"
],
"text": [
"Lenses are circular, but it is largely unimportant in how they are shaped. All the lens does is focus light onto a sensor, which is actually capturing the image. Sensors come in all sizes, but stick to a few aspect ratios. The one in your phone is probably 16:9 or a similar size. That size sensor results in that ‘shift.’"
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b8isy3 | How the data transits online from USA to EU (for example) | I'm familiar with the principle of bits to convey data (with copper cables first then optical fibers), and I know 99% of international traffic comes from cables in the ocean but I would like to know how everything turns out to work when, say you send an e-mail from London to New-York, how can the ridiculous amount of data in the world transit through a few cables? Hope it's not too complex to be explained. | Technology | explainlikeimfive | {
"a_id": [
"ejy52sq",
"ejy7ulo",
"ejy76vo",
"ejyukov",
"ejyhzr1"
],
"text": [
"There are routers. Routers are made to connect to each other and to your regular everyday computers. They keep a list of who they are directly connected to. So when you send a message, it gets split into little chunks, goes to your local router, who then passes it to the next router, who does the same, until it gets to the destination. There is a pathfinding algorithm that finds the best route for each little chunk to take. They each have an id so that the pieces can be put back together in the right order. Each chunk is put in a special packet so that routers can tell where and how to deliver it. They don't all take the same path to the destination. So one chunk could take the undersea cable, another through satellite, and another going through cables to Africa, then to Europe. As others have said, there are a lot of cables and they can carry a lot of data, and relatively speaking an email is not a lot of data.",
"The undersea cables can carry an incredible amount of data! FASTER, deployed around 2016, runs from Oregon USA to Japan. Alone, it can carry 60TB/s of bandwidth. If you happen to have gigabit fiber from your ISP, which is about the fastest residential service commonly possible, this cable is 60,000x faster than that. MAREA, deployed around 2018, runs from Virginia to Spain, can carry 160TB/s. There are many cables, and more being are deployed every year.",
"Good question! 1. There are multiple lines between the USA and Europe. 2. Each line has hundreds of fiber optic cables. 3. Each cable has multiple data lanes using different colored light. 4. Each data lane transmits millions of bits per second. Designing an internet backbone is a serious engineering task. People devote their entire careers to it.",
"Hey - I am *actually working* on the MAREA undersea fiber optic cable. It is capable of carrying much more than the 80 Tb being discussed here. The cable has 8 fiber pairs (one of each pair transmits east, and the other west). Each pair was originally expected to carry 20 Tb for a total of 160 Tb. With recent improvements in technology each fiber pair can carry ~24 Tb, a 20% increase! I work on the technology, so if you have any ELI > 5 I would be glad to try to answer.",
"Did you ever play with flashlights with your neighbor/friend, where you sent each other secret messages in Morse code, by turning the flashlights on and off? Now, instead of being next door, you and you friend are sitting at opposite ends of a single strand of fiber optic cable, one in London, the other in NYC. You guys have been messaging each other for so many years, you got so good at it, that now you can message each other 10,000 times faster than your average home internet connection. Right, now imagine the colors in the rainbow, and all the colors in between (actually imagine more like 100 different colors), and imagine there are flashlights for each color, and 100 pairs of friends, each sitting at the end of a single strand of fiber, everyone just as good and fast as you and your buddy at sending secret messages. And everyone is doing this at the same time. Now imagine 6 times this: ie. 6 strands of fiber, or 600 pairs of friends messaging each other at 10,000 times faster than you home internet connection. That's your email gets sent from one side of the Atlantic to another... Edit: the above is mean to describe how fiber optic subsea cables work. If you want an intro to how routing works, go watch this video: URL_0"
],
"score": [
15,
13,
4,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[
"https://youtu.be/Cb8b1RMX6XY"
]
]
} | [
"url"
] | [
"url"
] |
b8jl6p | How does KT Tape work? | I'm honestly bamboozled. It has worked several times for me, with pain returning as soon as it comes off. | Technology | explainlikeimfive | {
"a_id": [
"ejy8qjg"
],
"text": [
"Placebo effect, most likely. There's been a lot of studies on KT tape and there isn't any compelling evidence that it's effective, while there's plenty of evidence that it's not. But treating pain with even \"ineffective\" methods can reduce the pain; that's the placebo effect. But there's nothing special about KT tape - you can use cheaper scotch tape if you like, and it'll have the same effect."
],
"score": [
9
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
b8koye | How do vector graphics work? | More specifically, how are they able to be enlarged infinitely without blurring or dropping in resolution? | Technology | explainlikeimfive | {
"a_id": [
"ejybr3g",
"ejybk07",
"ejybqyk",
"ejygj4k"
],
"text": [
"Vectors are made of math. Each line or shape is defined geometrically by math equations, and the math equations can be scaled to any size.",
"They're represented as data points, rather than pixels. Think of it like a mathematical equation. They can be interpolated as much as they need to be.",
"Because vector drawings are saved as a list of instructions that define lines and fills rather than a specific arrangement of pixels. To increase the size of a shape you just make the numbers bigger that define that shape, and the same detail is retained.",
"Lets say you want to draw a line 4 pixels wide. If the line was defined by pixels you would say draw a pixel in space 1, 2, 3, and 4 for a line 4 pixels wide. With a vector drawing it would be defined as a line starting at point 1 and ending at point 4. & #x200B; Now lets try to enlarge our simple line to 7 pixels wide. With vector graphics now we would say \"OK start at 1 now end at 7 instead and make a line in between\". The computer knows exactly how to deal with the new space caused by enlarging the line because you have defined the group of pixels as a line. With pixels you would say \"OK I want to make the size 7 pixels so lets stretch this out. How can we stretch it out? Lets add a blank space between each pixel\". Now our line looks like 1\\_2\\_3\\_4 and the computer has to guess what goes in each blank. For a simple line it's pretty easy to guess what goes into each blank but for a more complicated shape each blank is a guess and the guess could right wrong or maybe there isn't a good answer to what goes in the blank so any guess is wrong. Every time you have to make a guess you introduce opportunity to have error in your images. & #x200B; Now instead of a 4 pixel long line what about a 4x4 pixel box. XXXX XXXX XXXX XXXX & #x200B; Look how many blanks we have if we stretch our 4x4 pixel box to 7x7. You are now trying to fill 49 pixels with information from only 16 pixels so there is a lot of guessing going on. & #x200B; X0X0X0X 0000000 X0X0X0X 0000000 X0X0X0X 0000000 X0X0X0X"
],
"score": [
4,
4,
3,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
b8raau | People often say that “today’s smartphones are more powerful than the technology we sent people to the moon with”. But how is this “power” quantified? | Technology | explainlikeimfive | {
"a_id": [
"ejzng0b",
"ejzolwu",
"ejzokzg",
"ejzo8wm"
],
"text": [
"Compute power. Ie how many Math operations the CPU can do per second. FLOPs is a common but somewhat meaningless metric for performance. It means floating point operations per second. Which is basically decimal math.",
"The computers on Apollo were very basic, but very specifically optimized. Your smart phone could easily do every calculation used to get to the moon and much more easily. However, the key thing Apollo had that a phone does not is rocket power and life support.",
"Well keeping it ELI5 it's measured in different ways but it all comes down to how much work a computer can get done in a given time frame. Better computers can of course do more calculations in the same amount or less time than an older one. So yeah today's smartphones absolutely trounce what NASA was working with during the space race. That honestly also work in their favor since they were using such simple computers they were actually extremely reliable which is what you want for space travel. To put it into perspective, one ways to measure computer performance is how many instructions it can execute per second. The computers used during the space race could do hundreds of thousands per second. A modern computer or smartphone is capable of billions of instructions per second.",
"People usually use metrics like FLOPS (Floating Point Operations Per Second), processor clock speed, and memory. For comparison, the Apollo Guidance Computer had a 2.048 MHz clock, and 2048 words (4KB) of RAM. The iPhone 4 had an 800MHz clock and 512MB of RAM."
],
"score": [
6,
6,
5,
4
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b8rhwm | How do websites know if you're using adblocker? | And is it possible to make an anti-anti-adblocker? | Technology | explainlikeimfive | {
"a_id": [
"ejzolyu",
"ejzoil1"
],
"text": [
"For an anti-anti-adblocker, you could use something like PiHole. It redirects DNS queries for ad servers to 0.0.0.0, effectively blocking all ads.",
"Ads send info to your pc, ie by opening a popup window. Your pc ignores that info and doesnt open the popup window. Website knows you blocked the ad because it doesnt detect the connection to popup window and then sends you another data packet asking why you're blocking ads."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
b905q4 | What are For loops and what is the difference between them and While Loops? | Technology | explainlikeimfive | {
"a_id": [
"ek191r2",
"ek1h121"
],
"text": [
"Imagine you have five apples. You have one sticker for each apple. Your boss asks you to put a sticker on each apple. That's a **for loop**. & #x200B; Now imagine you have an infinite amount of apples. Your boss wants you to put one sticker on each apple until you run out of stickers. That's a **while loop.**",
"The simple analogy has already been provided, but here is an example. The basic structure of the for loop is this: for( < initial statement > ; < condition > ; < Increment > ){ < block > } Which is analogous to the following while loop < initial statement > ; while( < condition > ){ < block > < increment > ; } while loops are handier for conditions that you don't really know when are over or when you just need to go as often you want. For loops are more useful for actually *counting* things out, or running over lists or items with defined sizes. Something like for( i = 0; i < 5; i++){ print(i) } will simply output 0 1 2 3 4 You can, at a quick glance, see this loop will run five times, and that i will take on every value from 0 to 4. It's great for iterating over lists or executing the same block for a defined range of numbers."
],
"score": [
9,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b95274 | How do GPS apps factor in time stopped at red lights when calculating ETA’s? | Technology | explainlikeimfive | {
"a_id": [
"ek2a0hi"
],
"text": [
"Imagine if you walked to the end of your block from your front door every single day and started counting: 1001, 1002, 1003, etc. Imagine you were also to maintain that count even if you stopped to watch a squirrel run up a tree, you stopped for your neighbor to back out of the driveway, or someone else walking to the block passes you and forces you to slow down. After a month a month you add each individual count and divide it by 30 (or how many days they are in a month). After a year you do the same and divide it by 365. Now, imagine you have all of that data being reported through your service daily. So now you're calculating every single person on your block walking to the end of the block millions of times over while calculating averages. With this amount of data, you can start to calculate everything from estimated times with weather conditions, accidents, speed traps, or people being pulled over. Welcome to algorithms :)"
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b96r21 | How do sticky grenades not stick to your hand but get stuck to whatever they hit | Technology | explainlikeimfive | {
"a_id": [
"ek2lwbu",
"ek2nnd0"
],
"text": [
"I know something about the ones in WWII if they're the same as you're talking about. Those had a wooden handle and a glass shell. They would throw them with the handle, or even smack it on the side of a tank.",
"It's covered in a shell. Once they pull the pin the Shell falls off and the business end gets thrown at or attached to a tank"
],
"score": [
8,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b99ujj | with regards to phone technology- what is 5G exactly? | Technology | explainlikeimfive | {
"a_id": [
"ek37eqx"
],
"text": [
"It's the fifth generation of cellular network standards that is being rolled out over the next year or two. It's not one thing, it's a lot of updates to the network infrastructure (and devices) to increase the capacity of the networks as whole, as well as an increase in the number and kinds of devices that can be connected. The marketing crap is just marketing crap. Most of it is a lie anyway."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b99uzz | the difference between USB 3.0, USB 3.1, type-c and thunderbolt | I've found a few threads on here that attempt to explain, but I didn't find any of them particularly clear. Thanks! | Technology | explainlikeimfive | {
"a_id": [
"ek368i9",
"ek35ceg"
],
"text": [
"**USB** is a protocol standard: it defines how both connected devices can communicate with each other. Newer generations of the USB protocol allow for faster speeds: * USB 2.0: 500 Mbit / second * USB 3.0 = USB 3.1 gen 1 = USB 3.2 gen 1 : 5 Gbit / second * USB 3.1 gen 2 = USB 3.2 gen 2 : 10 Gbit / second * USB 3.2 gen 2 x 2 : 20 Gbit / second [The naming scheme is ridiculous, indeed]( URL_0 ). You'll see this speed difference when you transfer large files, but when hooking up a printer or mouse it isn't noticeable. **Type C** is a connector type. It defines the lay-out of the port. For example Type A (= classic USB port) needs to be connected in the correct orientation, whereas type C ports also fit \"upside-down\". **Thunderbolt** is another protocol standard. USB is specifically designed to connect office devices and some file transfers. Thunderbolt on the other hand can do pretty much everything. (This is due to the direct connection to the super fast PCIe lanes on the motherboard.) You can use it as a display output, Ethernet connection or even attach an external graphics card. Thunderbolt also uses the type C connector.",
"USB 3.1 gen 1 is a new name for what was originally USB 3.0: same exact standard. The type C connector is it's own standard for a connector, not a protocol version. It includes the ability to run 3.x versions of the USB standard, plus a few extra pins that can be used for other communication protocols, like Thunderbolt, using the same connector."
],
"score": [
8,
3
],
"text_urls": [
[
"https://www.youtube.com/watch?v=gShRBsahzXg"
],
[]
]
} | [
"url"
] | [
"url"
] |
b99z85 | Why do high definition photos seem to have more detail than real life? | Technology | explainlikeimfive | {
"a_id": [
"ek36mgx"
],
"text": [
"Image processing and sharpening are pretty powerful tools by themselves, but I believe it is because camera/lens technology has gotten so incredibly advanced. Think about it this way, you can have a 100 megapixel camera, but if the lens isnt very good, the images will not be very clear/clean. If you have an immensely accurate lens, it changes completely. As far as the camera technology is concerned, pixel shift is changing the game. With pixel shift, the camera takes several images so that it can collect all spectrums of color inside the size of 1 pixel. If the camera takes 4 photos, it is effectively multiplying the resolution(and detail) by four. This allows the camera to capture as much--if not more--colors than the human eye. Now about the human eye, it is constantly refocusing, adjusting to changes in light, and moving. In the case of this question, the human eye is up against technology specifically aimed at clarity in visuals. At this point in the fields advancement as a whole, I'd say our eyes are outclassed!"
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b9afgv | How does a digital camera "know" if a spot in a taken picture is in focus? | Technology | explainlikeimfive | {
"a_id": [
"ek38hrp"
],
"text": [
"Theres a few ways to do this. Active and Passive. Active ones are like IR lights, ultrasound, lasers etc... You ever seen that red light cameras use? Thats IR focus where the camera measures the time it takes the light to bounce of and then knows the distance, crunches the numbers and focuses. Active methods rely on distance measurements. IR can also be used with passive Phase Detection in low light environments. Imagine it like a laser range finder. Passive methods are more complicated and deal with incoming light contrast and such. Phase detection is more commonly found in SLRs or other more modern cameras but some phone have it too usually listed as AF-PD but this is on the really high quality ones. This picture will explain it a lot better then I can. URL_1 More on it URL_0 Basically it takes multiple pictures compares them until they're \"sharp\" Another way is something called Contrast detection. Basically when the image is sharp the taken pixels in the image have better contrast. So the phone takes a lot of images and compares them and pick the one with the biggest contract difference. This is what most phones, it uses the CPU to check the image and adjusts the motor accordingly. When you use \"touch\" to focus the phone ignores the rest of the image and concentrates on the specific pixels you touched near. This often fails in specific conditions."
],
"score": [
8
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Autofocus#Passive",
"https://en.wikipedia.org/wiki/Autofocus#/media/File:Autofocus_phase_detection.svg"
]
]
} | [
"url"
] | [
"url"
] |
|
b9ef5x | Why do baseball pitches on TV look slower than in real life? | Technology | explainlikeimfive | {
"a_id": [
"ek42iac"
],
"text": [
"It's an effect of looking at the pitch through a long camera lens. When you stick a long lens on a camera, you reduce the width and height of the window the camera can \"see\" the world through. But the sensor in the camera records an image of the same width and height it always does (because the size of the sensor, obviously, doesn't change when you change lenses). In effect, this means everything looks bigger in the photograph. If you play video games and have every fooled around with your field of view (FOV) setting, it's exactly the same thing. When you decrease your FOV, you look at a smaller slice of the game world, but still display it on a monitor of the same size - everything looks bigger. Since it makes things look bigger, a long lens is almost always used for sporting events. There's only so physically close to the action the camera can get, so to make sure the battery fills your whole screen, they film it through a long lens. But while everything looks bigger, it isn't actually *closer* to you. This has the effect of making front-to-back distances look shorter than they are. Say you're standing on the mound, looking at the catcher as the pitcher throws. The plate is 60' away from you (I'm ignoring the extra 6\" for mathematical convenience). When the ball reaches 30' away from you, it's halfway to the plate. When it reaches the plate, it's twice as far away from you as it was at 30'. Since the ball is twice as far away at the plate as it was at 30', it looks half as big. But now say you're all the way back at the wall, and it's 300' away from the plate. So when the pitch reaches 30' from the mound, it's 270' from you. When it reaches the plate, it's 300' from you. That's only 11% further away, the ball only looks 10% smaller than it did at the mound. Since, on TV, you can only judge distance traveled by change in size, that means it looks like it didn't travel as far to get from the mound to the plate. Except time passes at the same rate, so it still took 100 ms to get from the plate to the mound - and therefore it seems slower to you (it looks like it traveled a shorter distance in the same time). Tangentially, this is one way filmmakers make car chases through traffic look so dramatic. They film from behind or in front of the car, using a long lens. It makes distances look shorter than they are, so when the car swerves and weaves through traffic, it looks like it's barely missing the cars in the other lanes. But in actuality, it's not even close; if you saw it from above, you'd see that the cars it's darting between aren't anywhere near each other."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b9f8py | How does Two Separate Switches control a single light bulb work? | I'm wondering about the electrical arrangement on how the light changes its state if you flip either of its two switches. | Technology | explainlikeimfive | {
"a_id": [
"ek435n9",
"ek4jbsi"
],
"text": [
"There are basically two wires between the switches. Lets call it a top wire and a bottom wire. The switches each connect the rest of the circuit either to the top or the bottom wire. When both switches connect to the top wire, the light is on. Both connect to the bottom wire, light is on. If they connect to different wires, light is out.",
"take a look at the diagram here. it illustrates it pretty well. [ URL_0 ]( URL_1 )"
],
"score": [
9,
5
],
"text_urls": [
[],
[
"https://www.reddit.com/r/educationalgifs/comments/5dufgh/how\\_a\\_4way\\_light\\_switch\\_circuit\\_works/",
"https://www.reddit.com/r/educationalgifs/comments/5dufgh/how_a_4way_light_switch_circuit_works/"
]
]
} | [
"url"
] | [
"url"
] |
b9fpau | How do images get printed on cakes or beer foam? | Technology | explainlikeimfive | {
"a_id": [
"ek47sme"
],
"text": [
"Same with home inkjet printer. Just that the ink that's used is edible ink. Tiny nozzles spray high pressurized ink onto a print media, in this case a cake or coffee foam"
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b9ggdn | How do devices show higher than the maximum technical resolution of the screen? | My laptop has a maximum screen capacity at 720p, yet you can notice a difference when changing to 1080p, 2K and even 4K in youtube. Same with my phone. Max resolution is a little over 720p but I see a very notable difference at 1080p and 4k videos. (Why would it record 4k if it cant show it anyways?) Go technical if you want | Technology | explainlikeimfive | {
"a_id": [
"ek4q79m",
"ek50th5"
],
"text": [
"Video compression is lossy. It degrades image quality. Generally if you play high resolution video scaled down you will get better quality than if you play video at the low resolution you want. This doesn't have to be always true, because the bitrate video gets encoded at determines quality. But generally, one would use higher bitrates for higher resolutions, because otherwise higher resolutions wouldn't improve quality and might even make quality worse. So, the high resolution video may have the same quality problems as the low resolution video if you look at pixels 1:1, but as it gets scaled down the problems become smaller.",
"Think of the digital video as a giant grid of crayons. Each frame, the whole grid can change. How often we change it is the frame rate. How big the grid is, that's the resolution. How intricate each crayon on the grid is.. that's the bit depth which is based on the number in your crayon box. Simplest would be just crayon vs no crayon, 16 box would be 16 colours.. 64 box is 64 colours and so on. Nowadays displays can show millions of colours. Now that's great and all for raw video, but not everything in a video changes every frame. Imagine a river with a bridge. The bridge probably doesn't change frame to frame, so we don't need to send that information every time. Maybe only water bits with rapids change a lot. We can just send updates instead. We have parameters we can tune for this, but if we overdo it things get blocky or fuzzy. Also, sometimes you have big areas that are all basically one colour. Say the bridge is grey and so you decide well.. I'm just going to say it's all this light grey crayon colour.. that way I don't have to send all the information for each crayon. Do this too much and fine details and tones get lost. There are many tricks and approaches to doing this, those are trivial examples why you can get blurry sharp edges and so forth. In the case of online video providers, much of the traffic now is over mobile, so engineers have to balance performance with screen size and user expectations. For lower resolutions, that means they can encode a video with say.. the equivalent of a 64 crayon box, and turn down other settings to make the video even smaller and faster to load. For higher resolutions where the user expects more quality, they may specify a 256 crayon box and turn up the other compression settings. Fancier solutions can change the crayon box size on the fly, as well as other settings. TLDR, video resolution is only one factor in overall video quality.."
],
"score": [
7,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
b9ig19 | What's the logic behind real long URLs, full of (seemingly random) characters and weird punctuation marks? | Technology | explainlikeimfive | {
"a_id": [
"ek4yu5h",
"ek4qs2h",
"ek4r0va",
"ek4t99y"
],
"text": [
"OK a few valid reasons here so far but I'm going to jump on the top most obvious one: **so they can track you.** Even with dynamically-generated sites you don't **need** a long complicated URL, you only need enough numbers and letters to make a unique ID for that page or item, whatever it is... for example this post: [` URL_2 `]( URL_2 ) That actually includes a bit of extra to make it more human-readable, as it works if you just do this: [`https://www. URL_5 /r/explainlikeimfive/comments/b9ig19/`](https://www. URL_5 /r/explainlikeimfive/comments/b9ig19/) So you can see you've got the site ([ URL_5 ]( URL_4 )), the sub ( /r/explainlikeimfive ), the fact you're linking to a post or comment (`/comments/`) and the specific ID out of many thousands in this sub `/b9ig19/` and that's enough. Now let's look at an item on eBay: [` URL_0 `]( URL_1 Holy tap-dancing baby jeebus what in the name of all that's holy??? Well, it will still work if you just link to the basic item number by picking the bones out of that horror-show of a URL: [` URL_7 `]( URL_7 ) But they have added a human-readable bit: `PORTAL-2-24oz-APERTURE-STAINLESS-STEEL-WATER-BOTTLE-new` ...and then gone *batshit crazy* adding a whole crapton of encoded information for a whole load of stuff, a lot of which we can only guess at but we can be pretty sure it's tracking you as hidden in there are names like `trkparms`, `algo`, `meid` (my ID?), `pid` (another id), `trksid` (another tracking ID?), etc. etc... This (likely) means they can track you around their site by tagging those ID's onto the end of every link, and also track if you send that item's URL to a friend as it will have your unique tracking ID's attached to it (and your account if you were logged in at the time). Either that or their site is just horrifically badly written, which I struggle to believe. Certainly it makes me suspicious. Interestingly, if you click the 'share' button it generates a much shorter link [` URL_3 `]( URL_3 ) but it likely remembers all this tracking stuff behind the scenes when someone clicks that link.",
"Usually these are used when a URL is generate dynamically (i.e. like people uploading youtube videos), and the website owner wants to ensure there are no collisions. Its just easier to use a random number/string than any other method, so it gets used most often.",
"Depends on the website and it's purpose. It could be trying to generate a unique page. Also, there's a protocol that developers use that the normal person doesn't understand. URL_0 That can be used on a server php file named fruit to send the data apples = 5 and bananas = 10. There's more to it than that, I'm sure someone else may explain better.",
"When mail is sent to your house (using US based address, sorry rest of world), they can't send it like this: > To /u/disintegrationist That's like saying you want to see a specific Reddit post's comment, and going to URL_0 and expecting to be taken there. No, you need to tell the mail person where exactly its going. So you add the street name. But there's other houses on the street. So you add a street number. But that could be an apartment building. So now you add an apt #. Pretty soon, you have a full address and the mail person knows where to take your mail. Often times, the strings at the end of a URL tells the web server exactly which page, and exactly what content to show you. These strings, you'll often notice, have the equals sign sprinkled around. That's like saying: > Send mail to = /u/disintegrationist > Send it to street = 123 abc street > Be sure to give it to Apt # = 4001 Or: > /u/disintegrationist?street=123abc & apt=4001 Now the mail person knows where to send my mail to."
],
"score": [
8,
5,
4,
4
],
"text_urls": [
[
"https://www.ebay.co.uk/itm/PORTAL-2-24oz-APERTURE-STAINLESS-STEEL-WATER-BOTTLE-new/283437202311?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Db96298951f604827804c4766ba7ab92a%26pid%3D100675%26rk%3D2%26rkt%3D15%26sd%3D202391987510%26itm%3D283437202311&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3Ad2a9fff9-572a-11e9-983d-74dbd1806398%7Cparentrq%3Aea83de641690aa13f691bca7fffd9c90%7Ciid%3A1",
"https://www.ebay.co.uk/itm/PORTAL-2-24oz-APERTURE-STAINLESS-STEEL-WATE",
"https://www.reddit.com/r/explainlikeimfive/comments/b9ig19/eli5_whats_the_logic_behind_real_long_urls_full/",
"https://ebay.us/Dze4gQ",
"https://reddit.com",
"reddit.com",
"https://www.reddit.com/r/explainlikeimfive/comments/b9ig19/",
"https://www.ebay.co.uk/itm/283437202311"
],
[],
[
"Mywebpage.com/fruit.php?apples=5&bananas=10"
],
[
"reddit.com"
]
]
} | [
"url"
] | [
"url"
] |
|
b9rgq4 | What are long exposure shots? Can I click them using a smartphone camera? | Technology | explainlikeimfive | {
"a_id": [
"ek6d2ft"
],
"text": [
"long exposure means your arperture stays open for a long time instead of fractions of a second. smartphones generally don't have that option because it wouldn't make sense - long exposure is useless without tripod, as even slightest shaking will make a picture all blurry"
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
b9s01i | What really happens behind the scenes when a website goes down or crashes ? How do developers get them back up and running ? | Technology | explainlikeimfive | {
"a_id": [
"ek6i5zu",
"ek6gmgp"
],
"text": [
"Basically, theres a computer somewhere in the world that runs the software someone made to show the website. The internet is just a bunch of computers connected together by wires. A lot of these computers aren't the same as your personal computer. They're basically just boxes that run code and that's all they do. These are called servers. When you type in the name of a website, its converted into a set of numbers called an IP address. This address is how your computer connects to the server so it can start exchanging info with it. When a website is down, theres either something wrong with the code/information on the server, or theres something wrong with the server itself, like it could be turned off or broken.",
"So, fundamentally, a website can be understood as two things: 1. the software that controls the website, and 2. the hardware that software runs on. When a website goes down, it could be either because the software locks up and needs to be restarted, or the hardware crashed and needs to be restarted."
],
"score": [
7,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
b9xzmd | How exactly do laser thermometers work? | Technology | explainlikeimfive | {
"a_id": [
"ek7prtk"
],
"text": [
"I believe the device you are referring to is actually called a pyrometer (please ignore me if you are talking about something else). Most objects undergo a process called blackbody radiation, which means that they emit light from their surfaces which has a wavelength (a way of classifying light) that depends on the object's temperature. The pyrometer is essentially a very specialised camera that is focussed on a very narrow point in front of it. The camera sees in infrared light instead of optical light because the blackbody radiation wavelength corresponding to temperatures that we might see everyday on Earth is in the infrared part of the spectrum. The camera measures how much of each wavelength of IR it can see and works out the temperature based on which wavelength is strongest."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
ba29b4 | What does it mean to scan a network and how do you use that to find a hidden camera on a wifi network? | I was reading this article on CNN regarding a hidden camera at an Airbnb. It says that the father found a camera by scanning the wifi network. URL_0 | Technology | explainlikeimfive | {
"a_id": [
"ek8jgsy"
],
"text": [
"TCP/IP uses addressed such as 192.168.1.X, where the X can be any number from 0-255. When you log into a wifi, you can open a command prompt and type ipconfig to see the ip address the computer typing the command currently is using. the 192.168.1 can be anything, but most common it is 192.168.1 or 192.168.0. then if you type ping 192.168.1.0, then ping 192.168.1.1 and ping 192.168.1.2. ..., you can build a list of addresses on the wifi. A whois command on the ip addres can give more information. A camera would likely be connected to the same wifi as you. While I'd guess there is an app to do all the ping'ing and whois'ing a scan of the local IP's could reveal a camera on the wifi. Many IP cameras use the same software, so trying to connect to any of the IP addresses could open a camera image. If you want to sweep the room, you want a wifi-detector from ebay for $30. The detector simply looks for radio signals, where a hidden wifi cam would show up, similar to a metal detector finding a horseshoe, with a big string signal and give a small circle to inspect."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
ba7ett | With ping issues in games, why do you appear to teleport around, yet others see you standing still/walking into a wall? | If your character never leaves wall, how can you appear to teleport to new spots, if your computer is just delayed in receiving information? | Technology | explainlikeimfive | {
"a_id": [
"ek9kvx8",
"eka04wu"
],
"text": [
"It all depends on how the netcode is written and interpreted. When you play online your copy of the game receives instructions from other peoples computers playing the game in near real-time. These instructions include what other players are doing. But if/when there is an latency (lag) then the game will malfunction, players will seem to jump around as your copy of the game catches up with the instructions. To compensate the game can include code that takes 'a good guess' of what that player is trying to do if it doesn't receive instructions in a certain amount of time. If for instance you are moving in a straight line, then it's easy to assume that this will continue. This helps smooth out the gameplay. But this invariably causes glitches so the game has to have code to compensate for this which can have unpredictable effects depending on how well it's written.",
"Both your computer and the server are taking your inputs and using them to calculate your position. When the connection between them is bad, the server misses some of your inputs but your computer doesn't, so there's an argument between them over which one is right. Exactly how that argument is settled depends entirely on the programming, but that's why your character will appear to just warp from spot to spot."
],
"score": [
8,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
ba9ro1 | Why aren't driverless trains more common nowadays? | Technology | explainlikeimfive | {
"a_id": [
"eka1brf",
"ekaawyl",
"eka50cd",
"ekac9xd",
"eka9nlr",
"ekaadq9",
"eka7xqg",
"ekadwpz",
"ekajz0a",
"ekadc7s"
],
"text": [
"Nowadays there is already a so called “ATO”-Button in most Trains, which basically drives the train to the next Station with perfect acceleration and braking and so on. For a fully autonomous train you need [Platform Screen Doors]( URL_0 ) as well as a fully fenced track which make sure, nobody accidentally falls onto the track. Also Unions play a big role in preventing the roll out of Autonomous Trains",
"Others have already pointed out \"unions\" but that's only one side of the story. The other side is insurance and cost. Basically insurance wants some other person to blame to reduce costs when something happens. And that human just doesn't cost much. I just looked it seems coal is about $33.72 per ton at the mine, and $39.09 delivered. I'll just take this as gospel, and it is one of the cheapest things I could think of that gets rail shipped long distances. Each train engine can pull 14,000 tons. I've seen trains with up to 5 engines. For a total train weight of 70,000 tons. This gives $2.3604 Million for the train value at the mine, and $2.763.3 Million delivered. The delivery fee is $375,900. Let's also say it takes a month for the longest train trip (it is much lower), so the train is worth $4.5 Million a year in delivery fees. Even if we assume the operator makes $100k a year (and I'm certain they make less) there is only about a 2% boost in train value per year. That just isn't that much difference. Since the insurance for the operatored train costs less, it simply isn't worth the fight to remove the operator. And remember making it full automatic would require investing money, for effectively no gain.",
"Depends on which trains you're talking about and where you are. If you mean like a Metro / Skytrain, those are unmanned in a lot of places. For those that aren't, the older and more used it is, the more difficult it is to replace or update it. Driverless trains require more than just a smart train, the tracks need to be adjusted to accommodate for them; sensors, proper fencing, etc. Unions and already deeply rooted companies / people, also don't like it when technology advances and replaces or undercuts them. It's why fossil fuels are still widely used in some 1st world countries that have better, cheaper and safer alternatives. It also seems to be a US problem, a lot of Asian countries, Canada, and European countries have mostly automated trains. If you mean locomotive style trains, it's because those tracks don't have a lot of the protections the transit sort of trains do, and there is often great value in the train itself as well as it's cargo.",
"For the same reason in the United States you cannot Alexa Enable a gas fireplace. Safety and security with a side of the human element to stop an accident causing mass casualties. ETA- You can Alexa enable it. No professional will do it, it won’t be up to any community code, and if there is a fire in your house it will void your homeowners policy and you will be held civilly if not criminally liable. (I looked into it as a Christmas gift for my sister and was shocked at the emphatic fuck no I got from professionals. Also found out that’s why fireplace remote controls are clunky and short distance only things.)",
"Hard to explain to a five year old... There are several reasons. If you go cbtc (communications based train control) for a goa (grade of automation) 2 (automated driving but start and doors are controlled by driver), 3 (same as two but controlled by a person on the train not constantly sitting in the cab) or 4 (full automation) you have to upgrade your entire line or it gets really messy. You need wayside equipment for that (Wi-Fi to feed the train orders, positioning systems so the train knows where it is and the operations control knows where the train is) and equip your trains for it. You can not pick and chose parts. Mostly you are bound to one provider and buy the entire package from them. Interoperability is a future goal but not yet achieved. So it is mostly used in new lines or if a line reached the end of its life cycle and would need a major overhaul anyway. Afaik there are quite a lot built and planned. Mostly in China and the middle east, though. It is just a huge undertaking and was hard to do with mixed operation (old and new for a time) in the past. But it seems there was a lot of progress made. But that is also a reason why it is mostly reserved for metros and people movers. If you have for example mixed use (light rail/freight rail/high speed rail) it becomes a nightmare to have everything that goes through equipped and tracked. Additionally there are safety concerns. The lines have to be separate from anything or at least they had to in the past. Nowadays we can make sure the tracks are secure and free with radar or laser technology for example. But the best things are subways or above grade rails on pillars or some other elevated inaccessible railway. There are also solutions where the trains are operating automated where the are separate and by a driver on sight at lower speeds where they are not. In general operation and building cost are still higher than for more simple forms of operation and it only really makes sense if you need to realise very low headways (time between trains) and transport massive numbers of passengers. So it is usually the busiest lines. I am not an expert on the subject but I did/do work with some. Therefore my knowledge might be at times imprecise or just outdated. Feel free to inquire further. I can not however give any information about specific projects, I think.",
"Mainly because of accidents like this one. URL_0 That's not even the nasty hazmat stuff. The technology exists for the most part but it's not all encompassing quite yet. It will run the freight trains for us and only kick it into manual mode at certain times. It still requires human input to start. The number of loads and empties need to be entered into the program among other things. They're called fuel trip optimiser, or leader. Also there is PTC positive train control, which works hand in hand with FTO or leader. PTC prevents train collisions and signal violations. That being said, it's not then unions that have prevented automated trains it's Congress who have passed bills requiring at least one person crews throughout some of the country and 2man crews in other portions. Granted the unions certainly funded lobbying for these bills to pass, but I assure you don't want fully automated trains yet. There's just to many variables and ways for it to fail, and with some of the nasty stuff on these trains they need to be as safe as possible.",
"I’m probably not entirely right on this, but I feel it’s like Pilots (in a Commercial Pilot course in Uni now), where they really only control the actual plane during take off and landing, and while climbing, cruising, and descending they are monitoring the flight while keeping in contact with centers and airspace’s they enter as the flight progresses, not actually touching the flight controls. I feel like it’s necessary for safety dying autonomous operation.",
"Passenger rail typically runs the same engine and car configuration Point A to Point B in an endless loop. Cargo rail has to form up trains sometimes several miles long to customer order with several different rail car types, and these trains have to get broken down and reformed often. The separating and joining of these trains is done by humans on massive rail sidings. When they arrive at their destination the cars will be unloaded. Then reloaded. Or moved up the track to be loaded elsewhere. Then return to their origin. Or somewhere else. The “choo choo doing train things along the track” is the smallest part of the work that conductors do. It’s really a massive logistics job. This is done almost entirely by people. And good for them - in an era when industrial jobs are disappearing, train conductors still walk on today at $60-70k / year and engineers at $80-130k+ depending on the size of the railroad (Tier 1 vs Tier 2) and experience. Benefits are ironclad and ridiculously generous. These jobs are absurdly difficult to get, nepotism is rampant and legacy hires are always given preference, just like longshoremen and harbor pilots. Source: grandfather, uncle worked for a major regional RR.",
"A conductor with the BNSF here, for freight trains it's definitely something they are working on but there are limitations with the software. We have what is called Form B's, which lists two Mile Posts (mp from here on out) and in-between those two MP's are workers fixing the track. With the current software, Positive Train Control (PTC), they can't get a train to reliably stop at the limits of these Form B's, which puts the workers fixing the track in danger of getting hit by a 10,000-ton train that could possibly have Haz-mat on it. There are other limitations too like if a train hits a vehicle at a crossing the train is supposed to stop (which can take miles) and the conductor goes back and helps the driver if possible as other help could be an hour or more away if the collision happens out in the middle of nowhere. If there is no one on the train, there could be no help for the driver of the vehicle for a long time. Our unions have also been fighting it for the facts above AND it would put tens of thousands out of a job as well. In our opinion, PTC is another tool and safeguard for us to use, not a replacement for us. I really don't want 10,000 tons of oil hurtling down the track with only a computer system that has proven to not be foolproof operating the train.",
"This isn't really an ELI5 but I would just like to state a bit of my case. I am a member in a train union known as SMART (Sheet Metal, Air, Railroad, and Transportation) union. Personally I'm a sheet metal construction worker, but I'm involved enough to tell you some of what goes on with my train brothers/sisters. First I should mention that the members of our union who work on trains tend to work on cargo trains, not passenger trains. In my 4 years of rather involved membership; I haven't seen much of the unions telling train companies \"no you can't implement xyz technology because it will hurt jobs\". What you do see is unions protecting their memberships jobs; if a company wants to move a job on a train to a different place i.e. an operations center the union will step in because the people in the operations center aren't necessarily union, and usually paid less. Currently today just like most forms of transportation trains have a good amount of automation, the cargo trains my unions members operate are currently 2 person crews, even at the dawn of train unions you didn't see large crew sizes; infact as far as I can tell 5 person crews was the most people unions ever stipulated. Today we require 2 people to be on board trains 1 conductor and 1 engineer. Train companies are actively trying to remove 1 of these persons, but as a union we argue this could cause issues as trains aren't currently 100% automated. If the remaining person has health issues this could cause problems for the train. The union doesn't care if the trains are 100% automated, as long as there's still 2 union men on board kicking rocks all day. But companies have less reason (safety is always a reason to automate) if there have to be 2 people on board. So it's a bit of a finger pointing debate. If someone wants to use some of this in a separate but better for ELI5 feel free"
],
"score": [
1635,
221,
45,
35,
23,
12,
7,
3,
3,
3
],
"text_urls": [
[
"https://en.m.wikipedia.org/wiki/Platform_screen_doors?wprov=sfti1"
],
[],
[],
[],
[],
[
"https://en.m.wikipedia.org/wiki/Lac-Mégantic_rail_disaster"
],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
bab2u7 | How does binary work and how can computers ‘read’ it and then perform a task? | Technology | explainlikeimfive | {
"a_id": [
"ekab7ak",
"ekabfu0",
"eka9gfg"
],
"text": [
"binary is really a math thing. its the simplest way of counting, using only 2 symbols: 0 and 1. Normally we count in decimal (base 10) which has 10 different symbols: 0,1,2,3,4,5,6,7,8 and 9 you can express any number in binary. a few examples: decimal — > binary, 0 — > 0, 1 — > 1, 2 — > 10, 3 — > 11, 4 — > 100, 5 — > 101, 6 — > 110, 7 — > 111, 8 — > 1000, 9 — > 1001, 10 — > 1010 computers pass electricity along a very complicated network of circuits and switches. within each switch, there are two possible states at any given point in time: on, or off (electricity flowing, or no electricity flowing.) This is abstracted to 1 or 0 for each switch. Electricity flowing means 0. No electricity flowing means 1. You can model all of the fundamental mathematical operations and logical comparisons using a series of “yes or no” comparisons that are physically processed by checking if there is electricity flowing or not in different parts of your network of circuits (the cpu). Over the years programmers, engineers and computer scientists have gradually built up more complicated functions and processes using combinations of these already written binary processes. These days, our programs are several steps removed from actually processing ones and zeros. you might write a program in a very popular and accessible language like python, and your individual lines of code would be human-readable, consisting of mostly english words, some symbols like parentheses, etc. When the computer actually executes the program, it converts each python line to C, which is a lower level programming language that references physical memory locations on the computer. Then, these interpretations in C are converted again to assembly language which is even lower level and deals with switches and physical circuits in the computer. Assembly language finally converts your operations to binary 1s and 0s. the computer processes these 1s and 0s very quickly, and then passes the result into assembly, which passes it to C, which finally passes it to python and the result is registered. In this example, you have 4 different programming languages of increasing complexity, different syntax and conventions, and which operate on different layers of abstraction from the physical computer. Python is built on C, which is built on assembly, which is built on binary operations that actually run on the metal circuitry that is your computer.",
"The answer to this question is an entire career's worth of studying, so anything ELI5'd is going to be a really, *really* high-level overview. Binary works the same way normal math does, except instead of rolling over to the next position when we hit 10 (ie, 9 + 1 = 10), we roll over when we hit 2 (ie, 1 + 1 = 10). Since there are only two possible values in binary--0 and 1--we can equate them to \"true\" and \"false.\" There's a whole field of mathematics behind this, called \"boolean algebra.\" Turns out, a lot of really complex stuff can be reduced to a boolean algebra problem--it's versatile enough that we can do all the things that programming requires us to do with it, and create some incredibly sophisticated and complex chains of logic with it. But it also turns out that since \"true\" and \"false\" can be represented by a high voltage and a low voltage, you can turn any chain of boolean logic into a physical, electronic representation of that chain of logic--that is, for any computable problem, you can build a circuit to represent it. The rest is all just figuring out which specific circuits you need, and how to make them generic enough that you can run any algorithm on them. That's the process of CPU design, and it basically boils down to providing a set of built-in circuits that perform specific operations. You provide this list of operations that the CPU can perform, called an \"instruction set,\" and then you can use those allowed instructions to program algorithms for the computer. An algorithm is the basis of all programming and all tasks that computers perform. And the ability to perform algorithms is possible because we can write any algorithm as a series of pre-defined instructions. Each of those instructions consists of a series of boolean logical statements, which can be represented by a physical circuit somewhere on your CPU, which themselves take binary inputs.",
"A computer is made up of tiny switches that when activated in certain ways perform a certain function. There are layers of software that translate each command you give the machine. You see the visual layer, under that is the machine layer. The machine layer takes your clicks and passes them down to complete the task. The switches do their thing and pass the output back up through the layers where you see the result."
],
"score": [
14,
13,
4
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
badh19 | How do water faucets work with going back and forth from hot to cold water? | When I’m showering, adjusting the knob just a bit can make the water go from scalding to freezing. I know the hot water is coming from the water heater. I want to know what mechanism is in the knobs that adjusts back and forth between the two. | Technology | explainlikeimfive | {
"a_id": [
"ekarxg2",
"ekaw96f"
],
"text": [
"It depends on the type of faucet you have, but in general, it let's both cold and hot water in. If you adjust it to hotter, it's just letting in more hot water and less cold water.",
"There is a tube connected to the hot and cold water pipes and inside it a tube connected to the handle and the shower. The outer tube has triangle shaped holes, the inner tube has one or two round holes. When you rotate the handle the inner holes line up better with one or the other outer holes, selecting more cold or more hot water. When you pull the handle the holes line up with the wider part of the triangles, increasing water flow without changing the balance. Roughly. That's what ours looked like when I had to dismantle it."
],
"score": [
5,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
badqn1 | How do Smoke Detectors work? | Recently I read that they have something to do with radiation? What? How does that help you to detect smoke and why did the people who invented it think of that? How did they go to using radioactive material instead of like a thermometer or a light detector or something? Help! Thanks in advance. | Technology | explainlikeimfive | {
"a_id": [
"ekattxh",
"ekau396"
],
"text": [
"The answer to that question is really two answers because there are two quite different kinds of smoke detectors. An optical smoke detector (or photocell smoke detector) creates an infrared light beam and uses a photocell which detects it. Smoke will block the light beam and the alarm goes off. Ionization smoke detectors use a radioactive substance to create alpha particles. The alpha particles crash into air molecules and turn them into positively charged ions and negatively charged electrons. The ions and electrons move in opposite directions between two electrodes. As long as the ions and electrons are moving, a current flows between the electrodes and a circuit in the smoke detector thinks all is well, so the alarm remains silent. Smoke has particles in it that interact with the ions and stop the current from flowing.",
"Ionization smoke detectors have a small amount of radioactive material (usually americium-214) between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm. The americium is not dangerous. It's an extremely tiny amount and the type of radiation it produces can't penetrate the plastic of the smoke detector. Even if you removed it, you wouldn't be exposed, as the radiation can't penetrate skin. You'd have to swallow it to get any exposure. Light and temperature aren't good or reliable indicators of a fire on their own. First, plenty of other things create light or heat that would trigger a false alarm. Second, an alarm that's triggered by heat or light would only be sensitive enough to detect large fires without constantly being triggered on a hot day or by someone turning on a light. A smoke detector can trigger long before a fire gets to that point, and obviously you want it to go off as soon as possible. That being said, there are other types of smoke detectors. There are some that detect heat, but they're almost never used alone and are paired with another type, and there are photoelectric detectors which use a beam of light to detect smoke particles."
],
"score": [
4,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
baeuuo | Why are some radio stations ' FM signals hard to pick up in the city they broadcast to, yet others from far away can be heard easily? | For example, here in England, 96.3 Radio Aire which broadcasts to Leeds, West Yorkshire is very difficult to pick up on FM, either on a car radio or on FM in general, and the signal is very fuzzy. However, Pulse 1 West Yorkshire, which is on 97.5 and 102.5 FM, and covers nearby town Bradford, can be heard far clearer in Leeds, even though it does not *officially* cover Leeds. Radio Aire broadcasts from Tingley, which is 8-10 miles away from Leeds. In the South of England, BOB FM on 106.7 and 106.9 FM covers Stevenage, Hertfordshire, but it's difficult to pick up in Stevenage, so I've heard, and it's apparently easier to get Heart 96.9, which is on 96.9 FM, based 26-30 miles away in Bedford [or was until it moved studios to Milton Keynes, around 31-40 miles away]. Heart Bedford broadcasts from Sandy Heath, Bedfordshire which is around 20 miles away. Why is it that a station whose FM frequency officially covers one city is hard to hear in its own city, yet one from a city around 10-14 miles away is easier to hear? How does proximity of transmitter affect signal? The examples above are general ones, this is *not* questions about any particular business. I would appreciate any explanation. | Technology | explainlikeimfive | {
"a_id": [
"ekbhbbj"
],
"text": [
"Couple of things: - of course, the closer to the transmitter you are, the stronger the signal. - the transmitter may not actually be in the city it is “broadcasting to” - stations run different power levels. One station may be a 50,000 watt blowtorch and the other a 100 watt low power station - station transmitters don’t alway broadcast equally in every direction. You can have transmitter antennas with different patterns that have weaker signals in one direction. This is often the case if there a station on an adjacent channel in a nearby city to help minimize co-channel or adjacent channel interference. - and sometimes, depending on the output power and height of the transmitting antenna, if you get too close to the transmitter, the transmitted waves go “over you” and you’re in a dead zone. This really only happens with low power stations."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
baf8kk | GPS rollover. What is it? What is for? | I have been seen this on internet, what is the significance? | Technology | explainlikeimfive | {
"a_id": [
"ekb2t3y"
],
"text": [
"When your GPS receiver or smartphone receives data from the satellites, one of the items it receives is the number of weeks that have elapsed since August 21, 1999. And because of the way that the GPS system was designed, that number is stored in 10 binary bits. Trouble is, 10 binary bits can only store a number between 0 and 1023. We're now in week 1024, which will wrap around and become week zero. So your GPS needs a software update to tell it to start counting from April 2019, not from August 1999. Otherwise it won't know what the current date is. Why August 1999? Because that's 1023 weeks ago, ie when this problem last occurred."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
bafcp2 | Why does a radio app on a phone require a headphone as antenna? | Technology | explainlikeimfive | {
"a_id": [
"ekb2yk2"
],
"text": [
"FM radio signals have a fairly long wavelength - at least, compared to any other use of radio in a phone. That longer wavelength needs a longer antenna, which you can't fit inside the phone. So they instead use the shielding in the headphone cable, which is plenty long enough. The app could try to work without the headphone plugged in - many do - but it is hard for them to pick up a radio signal without it."
],
"score": [
10
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
bagveg | Why dont car doors unlock if you pull the handle while it’s unlocking? | Technology | explainlikeimfive | {
"a_id": [
"ekbhwxm",
"ekbdwa6",
"ekbpobi",
"ekbjjzu",
"ekbdvmg"
],
"text": [
"Because there's a piece it needs to move before the door will be able to open, and it can't move that part while the door handle is being pulled on. (In general.)",
"There are linkages that have to complete their jobs once the button is pressed to lock or unlock the door. Linkages and parts are moving and actuating once the lock/unlock button is pressed.",
"When the door is locked, the handle still moves but is disconnected from the mechanism that unlatches the door at the striker. When you unlock the door, that mechanism if moved back into place, so pulling the handle will release the striker. If you unlock the lock while the handle is pulled, the striker mechanism cannot reconnect with the handle because it is not lined up.",
"Eli5 version? It's the same as trying to open your front door while twisting the door knob. You have to do one before you can do the other. When you twisting the handle of a door, it causes the metal tongue in the door frame to get pulled into the door handle, removing the physical blocking piece that prevents you from opening the door when not twisting the knob. If you try to pull the door while twisting the knob, the handle jams as the friction of the metal tongue gets pressed against the door frame.",
"Because it's not fully unlocked until it's done unlocking. The mechanism to prevent the door from opening is only fully disengaged at the end of the unlock cycle."
],
"score": [
22,
9,
8,
5,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
bajlmb | What is a web server? | I am having a hard time understanding web servers. how does it work? what does it do? | Technology | explainlikeimfive | {
"a_id": [
"ekc9bcy"
],
"text": [
"Web servers are simple enough that I've elected to use real example code to illustrate them instead of metaphors. I am aware that this would confuse an actual five-year-old. --- A web server is software that implements the Hypertext Transfer Protocol (HTTP), or a computer that is running such software. This means that if you send a message to this computer that constitutes an “HTTP request”, then the computer will respond with a message called an “HTTP response”. A simple example of an HTTP request is: GET /foo HTTP/1.0 The plain-English meaning of this request is “send me the document called ‘/foo’ ”. A simple response to this request might be: HTTP/1.0 200 OK Date: Sun, 7 Apr 2019 12:34:56 GMT Content-type: text/plain; charset=UTF-8 Content-Length: 13 Hello, World! This means that the request succeeded and was sent as the given time, that the document you requested is plain text, and that its contents are “Hello, World!”. Date, Content-type, and Content-Length are called *headers*, and “Hello, World!” is the *response body*. (I'm handwaving some technical details that aren't relevant to the example, like versions of HTTP, line endings, and such.) When you type ` URL_0 ` into your web browser's address bar and press enter, your web browser will: - Find the address of the server named ` URL_1 `. - Send an HTTP request to that server… - …that looks something like `GET /r/explainlikeimfive HTTP/1.0`. (In practice, your browser will almost certainly use HTTP 1.1, and it will send a bunch of other information in headers. It may also use an encrypted form of HTTP called HTTPS. These things are important, but they are not central to what a web server is.) Often, when you request a document from a web server, it will send you an existing document that it has in its filesystem. For example, I might have a web server for the purpose of sharing documents on my hard drive under `/var/sharedstuff`. If you send an HTTP request for the document `/foo.html`, then I will send you the file that's on my hard drive at `/var/sharedstuff/foo.html` if it exists. This is how “static” web sites work. However, I could also have a complex system that generates documents on demand using information from a database or elsewhere. For instance, when you request `/r/explainlikeimfive` from Reddit's servers, those servers will create a brand-new document with the current front-page posts. If you ask for `/r/explainlikeimfive` a few minutes later, you will get another brand-new document that may have different content."
],
"score": [
4
],
"text_urls": [
[
"http://www.reddit.com/r/explainlikeimfive",
"www.reddit.com"
]
]
} | [
"url"
] | [
"url"
] |
bajzrr | How does an infrared/laser thermometer work? | Technology | explainlikeimfive | {
"a_id": [
"ekc1lyo"
],
"text": [
"The laser is just for aiming purposes, it doesn’t actually participate in the temperature measurement. As for the infra red, all bodies which contain heat emit infrared radiation. The warmer something is, the more it radiates. There are infrared sensors that can measure this radiation and calculate the corresponding temperature."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
bak73n | How does a radio telescope turn its readings into a picture we can see? | Technology | explainlikeimfive | {
"a_id": [
"ekc5oij"
],
"text": [
"The interesting bit is that all images made by modern optical instruments (cameras, radio, etc) work the same way. This is because radio, and visible light are really just the same thing. Think of radio as a color we can't percieve Modern instruments are made of a grid if light sensors. Each sensor simply detects if light has stuck it or not. When the computer reads it out it registers where the sensor is on the grid, and how much light it received. The computer then recreates the grid on a monitor, with more light received producing a brighter pixel. Different colors are achieved by taking multiple images, each one has a colored filter on front to only let a specific color through. This is then overlayed on top of the black and white image, and more light is brighter as before. This time though the light is displayed as a specific color to match the filter. If we want the signal as sound, the instrument simply makes the intensity translate as volume rather than brightness, and \"color\" is a different frequency (pitch). This works because while sound is different from light, it is still a wave like light, so we can treat then in a very similar fashion."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
bakb5f | Virtual Environment in programming | Hey, I'm specifically interesting in understand the idea behind venv in python Thanks. | Technology | explainlikeimfive | {
"a_id": [
"ekc66tu"
],
"text": [
"You install Python on your machine. This includes some standard packages. For a lot of projects though, you'll have to install additional packages (using PIP for example). As you build more, and more complex projects, it becomes hard to track which projects use which packages. Also: different projects may use different versions of the same package. To make this more structured, you should create a virtual environment for each project. This basically contains a copy of your original Python installation, and you can add all your project-specific packages here. Other projects won't be affected. Take it a step further, and you arrive at Docker containers. These create isolated environments, containers, not only for your Python installations, but for all project dependencies. This makes it very easy to transfer your project to another machine as well. You just have to clone the Docker container."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
bakxdo | Was there an address besides www when the internet started? Why were these necessary and why is "www" still around? | Technology | explainlikeimfive | {
"a_id": [
"ekc8x7j",
"ekc8yjv",
"ekca2uk"
],
"text": [
"Yes absolutely. For example URL_0 for email. Email is much older than the Web, and so are several other Internet services.",
"The internet existed for a couple of decades before the world wide web. The subdomain was used to indicate different services, such as ftp for file transfer and mail for emails.",
"Yes. And there still is: for example, [ URL_1 ](https:// URL_1 ). The \"www\" is just a convention. Back in the old days (say, 1995 or so), when you really needed to worry about people accessing your server using the wrong tool, you would often see [gopher.]( URL_6 ) URL_4 or [ URL_2 ](https:// URL_2 ) in addition to [ URL_0 ](https:// URL_0 ). As http has replaced just about everything else for that initial contact, you don't see them too much anymore."
],
"score": [
6,
6,
3
],
"text_urls": [
[
"mail.stanford.edu"
],
[],
[
"www.whatever.org",
"docs.google.com",
"ftp.somecompany.com",
"https://ftp.somecompany.com",
"someschool.edu",
"https://www.whatever.org",
"https://gopher.somewebsite.com",
"https://docs.google.com"
]
]
} | [
"url"
] | [
"url"
] |
|
bamb0w | how much of a multiplayer video game runs on the user's machine vs. on a game server? | Technology | explainlikeimfive | {
"a_id": [
"ekcl72g",
"ekcm3mp",
"ekcluyi"
],
"text": [
"It varies slightly from game to game, but in general: Server: Where is each player? What weapons do they have? How much ammo do they have? Which character are they playing? When can they use their next ability? Client: What does the map look like(graphics)? What does my character look like(graphics)? What do my weapons look like(graphics)? What does this ability’s animation look like? Server=Logic, Client=Graphics",
"That depends heavily on the game, but the general rule is that the server handles anything important regarding the game state. A rule of thumb is \"Could a user cheat if he is given authority over the given information or mechanic?\". If the answer is yes, it probably is run by the server. The most strict version of this is that the only thing the client is allowed to do is send what buttons are being pressed, and render whatever the server tells it to render. This of course is rather straining on the server, so in practice the server isn't quite so strict about it: albeit the general rule of never trusting what the client says still applies.",
"It really depends on the game. Generally speaking you want as much of the heavy lifting to be done by a users computer as possible. This includes things like rendering graphics. The reason for this is that the less work your server has to do the more people can be on it at one time. This helps keeps costs down, or more accurately pushes the burden of the heavy lifting to the players. The servers generally just track numbers like your position, which items you have, etc. Doing this allows multiple players to interact, but can always be used to save games on the cloud and curb things like cheating because the devs can track what's going on in the game by looking at the server data."
],
"score": [
19,
4,
4
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
baosv6 | How does testing a nuclear weapon in ones own country is considered safe but attacking other country causes mass destruction and environmental problems? | Technology | explainlikeimfive | {
"a_id": [
"ekd4ca0",
"ekdn7fi",
"ekd4huk"
],
"text": [
"Testing of nuclear weapons is normally done underground where no one can be directly affected or in a desert setting where, again, no one can be affected. One nuclear bomb is not going to destroy a country. It affects the direct area of the blast but if that’s in the middle of a 500 mile long salt flat, it doesn’t really matter. Dropping a bomb in the middle of a populated city is what’ll get ya. The former is considered “safe” because it’s highly highly controlled.",
"ELI5: It's the difference between having experts setting off fireworks outside at a carefully chosen distance from people, and setting them off inside your kitchen. Note that even setting them off outside can sometimes be dangerous.",
"Nuclear weapons testing is never environmentmentally safe. It's historically unhealthy for the populations of the testing country as well as fallout gets blown by the wind which is hard to accurately predict. The closest we've gotten to safe testing is underground, as it doesn't enter the atmosphere. Instead, it contaminates the ground and can taint the watershed. Obviously when used as a weapon against an enemy, you make a point to hit targets, which are generally populated areas since that is where governments and resources are centralised. That is going to kill people immediately and in large numbers as opposed to being detonated in the desert or ocean where its going to be slow and fewer casualties due to health effects."
],
"score": [
14,
6,
6
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
bapxbf | how did we switch from having operators connect our calls to being able to call people directly? | Technology | explainlikeimfive | {
"a_id": [
"ekdcxu2",
"ekdcd9y",
"ekdfxm9"
],
"text": [
"We automated the operator. A phone number has information that directs how it is to be routed to get to someone. So we will use the tv phone number of all 5s. The number to Jim Bob is 1-555-555-5555. The first 1 is the national code for the USA and if you are physically within the USA it is not always needed. The next 3 numbers is the Area Code and it sends you to a specific region of the US. The next 3 numbers are the Local code and it sends you to a specific city or part of a city. The final 4 numbers are the specific number assigned to Jim Bob. In early days of phones each of these connection steps (National, Area, Local, Specific) were changed by hand by physically moving cables on a switch board. We then developed permanent connections that could be switched between by the operator pressing buttons and switches. Now that nothing has to be physically moved it was simply a matter of time before a computer is controlling those \"buttons and switches\" electronically and automatically when you place the call.",
"Think of you in a classroom, if the teacher gives you a graded paper and tells you to give it Karen, you know who Karen is, she's been in the same classroom as you all year long. In a small phone network, it's easy to transfer someone by name, receptionists in small offices still do that. If I told you give that paper to Karen and that she's someone on campus, you have no idea if that's a student, teacher, or staff, or where they are. So I'd have to tell you, give this to Karen, room 53, 4th period, front row, center desk. Likewise when the phone network grew larger, you had to tell the operator the city and line number. Eventually area code, exchange code and line number, which is in North America, 123-456-7890. The first version was pulse dialing, on old rotary dial phones, pulses of electrical current told the phone system what number was dialed. Then later DTFM which are sound signals. In North America until the about 1980s, the phone company owned the phone that you connected to phone jack, so upgrading your phone to support pulse dialing or touch tone dialing was a matter of them trading out your phone. From memory, I think I had pulse dialing until the early 90s.",
"Back in the 1880's phones were taking off and businesses started using them. In a town in Indiana and undertaker called Almon Strowger noticed that he wasn't getting any calls about his undertaking business, but his competitor was. A little investigation showed him that his competitor's wife worked at the local phone exchange (she was the one who connected the calls) and surprise surprise anyone calling for an undertaker was connected to her husband no matter who they asked for. Strowger then developed a machine that could be remotely operated by the phone to connect the calls. The phone would send signals down two wires, one to indicate the user was dialling, and another to send the numbers as a series of pulses. The Strowger switch would take the incoming call and route it out of one of ten output connectors which could be either connected to a phone, or another switch. So if you dialled one the signal would be routed out of connection one. Initially during the manual age of phones you would call the operator (by picking up the phone) and ask them to connect you to a specific town, then ask that operator to connect you to a specific phone in that town. With Strowger's system you used phone numbers as almost driving instructions for the phone call. If you dialled 123 the phone call would take exit 1 at the first switch, then exit 2 at the second, and exit 3 at the third."
],
"score": [
6,
5,
5
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.