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
|
|---|---|---|---|---|---|---|---|
jdyvw0 | Why is a Ethernet cable connection more stable than WiFi? | Technology | explainlikeimfive | {
"a_id": [
"g9b5u5p",
"g9b6483"
],
"text": [
"Imagine filing a bucket with a hose and the other with the rain wich one will fill faster?",
"Less interference - the signal that your WiFi uses must (by law) be within a specific frequency range, in order not to interfere with things like public radio, emergency services radios, taxis etc. The range that is used by WiFi and Bluetooth, especially at the power output which is allowed, is easily blocked by thick walls or metal surfaces (like corrugated metal roofing). In addition since all WiFi and Bluetooth devices operate within the same range of frequencies, you get interference of there are a lot of devices close together (like in a hotel or apartment building. There are also non-wifi appliances which emit signals that can interfere with WiFi because their emissions are in that same frequency block, eg microwave ovens, older cordless phones, baby monitors etc Ethernet cables by comparison are insulated and shielded. Whiles it is still possible to have external interface on an ethernet cable, it's far less likely, especially in a household setting. It's also a better medium, for transferring data electronically. Ethernet uses copper wire, which is very good an maintaining the signal over a reasonable distance, so you can send more data more quickly and be reasonably certain it will get there. Air on their other hand is less consistent (even without the issues mentioned above) and so you need to send data more slowly and it smaller amounts to get the same consistent successful transmission rate."
],
"score": [
18,
6
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jdzgvk | How exactly does “lossless” audio work (and why is it important)? | Technology | explainlikeimfive | {
"a_id": [
"g9b9ovd",
"g9b9t4x"
],
"text": [
"\"Lossless\" and \"lossy\" refers to compression, the method in which large files are made small enough to be reasonable to store and transport. Lossless compression schemes will always restore the file to what it originally was. It will never \"lose\" any information, it is exactly the same as what it originally was when being created. However because all information *must* be preserved there is a limit to how much smaller you can make the file. At some point you've found all the patterns you can compress and are just left with a file where every bit encodes vital, irreplaceable information with no patterns to encode. Lossy schemes however don't care. They will try to find ways to throw out as much data as they reasonably can get away with without you really noticing. They will try to nudge data around so that it has easier to store patterns. they will try to approximate the final product instead of keeping it 100% intact. This allows lossy compression schemes to create much smaller files, but at the cost of lowering the quality or changing the audio so that it isn't identical to the original audio and probably has lost some dynamic range or tiny audio features. Now, the good thing about lossy compression schemes is that they typically are pretty good at identifying the information you'll never notice was missing, and a good one is great at making their product sound \"Almost the same\" even if it's slightly worse because you have literally thrown out parts of the audio. For the most part, most average consumers don't notice nor care. However depending on who you are and what you're doing you may actually prefer to have the high quality, information-dense audio that has all of the sounds and all of them in the exact same condition as they started out in. The methods you suggested won't bring back the information lost, you're just adding new information that you think make the song sound prettier. Maybe it does, but odds are you're just smudging the audio file around to give the illusion of being higher quality.",
"I'm far from an expert but one of the major ways lossless differs from lossy is dynamic range. Lossless audio generally speaking has a wider dynamic range, which is to say the difference between the loudest and quietest sounds is greater than what you find on lossy. This allows for greater subtlety and depth in music, though mostly classical music these days. There's something called [The Loudness Wars]( URL_0 ) which is a phenomenon where over the years music is being produced/mixed at increasingly higher volumes. It's fascinating, but also worth noting that lossless audio doesn't combat this. Recordings that predate the Loudness Wars will generally sound better as lossless audio (though not always)."
],
"score": [
6,
3
],
"text_urls": [
[],
[
"https://en.wikipedia.org/wiki/Loudness_war?wprov=sfla1"
]
]
} | [
"url"
]
| [
"url"
]
|
|
je0dp6 | How do the machines at the exit of a store detect an un-purchased product? | Technology | explainlikeimfive | {
"a_id": [
"g9bdrvl",
"g9be8kw"
],
"text": [
"It varies by stores, but most of them make use of a disposable tag and have readers by the doors. At time of purchase, said tags are removed, or encoded to no longer trigger the readers by the door. Check this: [ URL_0 ]( URL_0 )",
"EAS stands for electronic article surveillance. It uses a variety of tools like security tags, stickers, labels and cables that are paired with sensors that sound an alarm whenever a stolen item is taken out of the store or a tag is tampered with or forcefully removed. There are four basic types of EAS systems: electro-magnetic, acousto-magnetic, RFID and microwave. Out of the four, RFID is one of the most commonly used types in retail stores. They work by having each RFID tag possess a specific resonance peak, which RFID sensors monitor constantly for any anomalies. There are also ink-loaded tags that go perfectly with clothing and other similar products. If a shoplifter ever tries to break them open, the ink inside would leak all over the item making them virtually unusable. As well as having a transmitter and receiver at the doorway, every item in the store contains a concealed RF \"tag\". In bookstores and libraries, you'll find very discreet \"soft tags,\" stuck to one of the inside pages. In record stores, the plastic shrink-wrap may have an RF tag stuck onto it, or CDs may be locked into large plastic cases with RF tags built into them, which can be removed only be a special tool at the checkout. In clothes stores, there is typically a \"hard tag\" (a chunky, round, white plastic tag) bolted onto each item with a sharp metal spike (sometimes the tag has ink inside it so it spills all over you and spoils the item you're trying to steal if you attempt to remove it). Some of these tags are cleverly concealed so you can't spot them. Others are deliberately very obvious and easy to see—so they deter you from stealing. The gates on the doorway (and the frequent alarms) are another very visible deterrent to shoplifters. If you walk through the doorway without paying for something, the radio waves from the transmitter (hidden in on one of the door gates) are picked up by the coiled metal antenna in the label. This generates a tiny electrical current that makes the label transmit a new radio signal of its own at a very specific frequency. The receiver (hidden in the other door gate) picks up the radio signal that the tag transmits and sounds the alarm. Why doesn't the alarm sound when you pay for something? You may have noticed that the checkout assistant passes your item over or through a deactivating device (sometimes it's incorporated into the ordinary barcode scanning mechanism, and sometimes it's completely separate). This destroys or deactivates the electronic components in the RF label so they no longer pick up or transmit a signal when you walk through the gates—and the alarm does not sound. As an example, imagine a shoplifter trying to steal a book from a store. What he doesn't realize is that the store's using electronic article surveillance (EAS): the book has an RF tag stuck just inside the back cover. Here's the sequence of steps that triggers the alarm: The gate on one side of the doorway contains a radio transmitter. This constantly beams out radio waves to the gate on the opposite side of the doorway, which contains a radio receiver. 1. A shoplifter walks through the doorway carrying a stolen book. 2. The book contains a hidden RF tag stuck to a label inside, which picks up the radio waves. 3. Once activated, the RF tag transmits a radio wave of its own at a very precise frequency. 4. The receiver gate picks up the radio waves and identifies their frequency. 5. If the frequency is correct, the gate figures out that a stolen item is moving through and sounds the alarm."
],
"score": [
5,
3
],
"text_urls": [
[
"https://www.securitytags.com/the-different-types-of-security-tags"
],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
je0t4i | Why does depth matter in regards to water resistance on cell phones? The new iPhone is rated for up to 6 meters for 30 minutes. Why is 6 meters ok when anything deeper isn’t? Does pressure matter that close to the surface? | Technology | explainlikeimfive | {
"a_id": [
"g9bh96r",
"g9bh4jx",
"g9bkaro",
"g9bhfop",
"g9bhtq9"
],
"text": [
"You answered your question already: pressure. Small slits and sealings fail at certain pressure. Pressure increases rapidly under water. Starting from the surface, pressure increases by 1 atm (100 kPa) every 10m. 1 atm at surface level 2 atm at -10m 3 atm at -20m and so on.",
"Yes, it does. The water pressure at 6 meters is about 9psi. While barely perceptible to humans, it's definitely a factor for the seals on a piece of electronic equipment. Additionally, standards like IP are performance based. It doesn't mean the iPhone can sit at 6m for 30 minutes and fail at 31, nor does it mean that it necessrily can't go to 8 meters for a few minutes. It means that 6m at 30 minutes is the standard it met during testing. There are higher IP ratings available, but engineering the phone to achieve them would likely have been undesirable for cost reasons.",
"There are two sides to this... The first is that yes, pressure will matter - water is actually pretty heavy, so the deeper underwater you are, the more weight will be pushing down on you - and in the case of something like a phone, trying to force its way through any cracks or imperfections in the phones water seals. The second part is that they need to be able to test a gadget and put a specific rating on it. We need to know that when we buy something that is 'water proof', how water proof will it actually be? There is a massive difference between something being splash proof or able to survive being dropped in the sink, and something that will survive 10+m underwater... So to this end we need to have a specific way to rate how water proof a gadget actually is - in electronics this is typically in the form of a depth rating, and how long it can stay at that depth for. So a product will be designed to a certain rating, which we can then test - take a big enough sample of products, test them by putting them underwater at an equivalent water pressure, for the correct time and make sure they are all (or at least a high enough percentage) are all passing. This doesn't mean that every product will instantly fail if you take it any deeper underwater - a lot of products will work far beyond their specified rating - but the manufacturer expects that they will start failing more regularly when you go beyond the specification.",
"> Does pressure matter that close to the surface? Yes, pressure increases steadily and the increase starts immediately. The deeper you go, the more pressure. Pressure is the force trying to get inside the phone.",
"Each meter of water adds about 1.4 psi or 10 kPa Sitting at 1 meter for 30 minutes means the phone only needs to withstand about 10 kPa of water pressure, but sitting at 6 meters means it'll need to withstand 60 kPa which is 6x the pressure and therefore a lot more challenging Water resistance ratings come from the Ingress Protection standard and the higher level ratings generally use 30 minutes because that is the time spelled out for IPx7 (1 meter for 30 minutes) and IPx8 is just something better than 7 as defined by the manufacturer. Phones are water resistant not water proofed like dive watches so while they're underwater, the water is slowly working its way through the protections. More pressure forces the water through those protections faster, and more time gives it more time to get to the important bits. The phone might make it an hour at 2 meters, or 30 minutes at 6 meters and its up to the manufacturer to decide what they want to claim once they can exceed 30 minutes at 1 meter"
],
"score": [
38,
37,
9,
6,
5
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
je1jq0 | Why is Apple using ARM at all? | Technology | explainlikeimfive | {
"a_id": [
"g9blvk6"
],
"text": [
"> Cant apple just make their own architecture in-house and skip over the middleman (ARM)? Sure, they just need to hire a couple thousand experienced chip designers, spend $10B, and wait a few years ARM has already done most of the legwork with designing good enough CPU and GPU cores that others can license from them for a reasonable rate. Companies that don't want to or can't afford to design their own chips can just license ARM designs, put the blocks together how they need, and then call up a Fab and have the chips made with relatively little engineering effort of their own letting them focus on what they're good at while leveraging the fact that ARM is good at chip design."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
je4i2d | is wireless signal targeted to a device or is the signal sent in every direction? | If my phone is playing music but I'm hearing it on a bluetooth device, the information of the music is being sent on every direction? Isn't that a huge waste of energy? | Technology | explainlikeimfive | {
"a_id": [
"g9c7b7y",
"g9c77pv",
"g9c7i3q"
],
"text": [
"It's being sent in every direction. Some newer wireless standards can aim the signal to a certain degree at least. It's not really the power consumption that's the problem with this but cross-talk from all sorts of other wireless devices.",
"Bluetooth, Wifi, Cell, is generally omnidirectional, either in with omni directional antennas, or directional antennas arranged in an omnidirectional array. Of course there are tons of exceptions, but for typical consumer stuff, it's transmitting in all directions. And it's not a big waste of energy, the wattages they are transmitting in are very low. P2P (Point to point) is more rare and can take more set up expertise.",
"It's sent in all directions. But it's not lot of energy because the range is pretty limited. Communicating with a celltower for sending mobile data is a lot more energy, but still not extreme because it's still fueled by your small phone battery. Generally it's like they are whispering very silently but they all have extremely good ears to understand each other anyways. (And they have a good system to agree who is talking when so they don't scramble each others messages) It's possible to direct signals, but that is usually not worth the effort, because you would have to point your phone antenna at the right direction to get a signal, and often you won't even know where that direction is."
],
"score": [
3,
3,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
je7086 | How do fighter jets detect that they've been locked as a target of a missile? | Technology | explainlikeimfive | {
"a_id": [
"g9dgltq",
"g9cotba",
"g9cny90",
"g9cofko",
"g9dp6ok",
"g9crbbs",
"g9coicu",
"g9dghrw",
"g9d45x2",
"g9dbj1m",
"g9e0g8p",
"g9dcfqy",
"g9ehzwd",
"g9djjc1",
"g9coenm",
"g9e0xlw",
"g9ea8yh"
],
"text": [
"Ooh! Finally! A question I'm 100% qualified to answer! ELI5; a radar is basically what you get when you put a radio on the Steve Rogers super serum. It detects and tracks targets by sending out a ridiculously powerful pulse of radio energy and listening for that energy bouncing off of an airplane and back to the source. Now, any radio can be picked up by another radio, so modern fighters have antennas and receivers all over that will detect when a radar is targeting them, and alert the pilot. Such a system of antennas is called a Radar Warning Receiver and is standard on any military aircraft. We even have specialized \"Anti-Radiation\" missiles that use the same principle to attack enemy SAM sites. I'm an ex-Air Force avionics tech who's super passionate about this stuff. If you want a more in depth answer, or want to know anything else about modern avionics, hit me up, I'll talk your ear off! The cat-and-mouse game of engineers designing radars to avoid detection by RWRs, and engineers designing RWRs to detect these new radars is also an interesting subject Edit: Oh sweet Jesus this blew up! I didn't know I'd be doing an AMA today lol. Don't worry, I'll get to all you guys, but it might take a bit lol. And thanks for the awards, strangers! I appreciate it!",
"Radars that serve different purposes behave differently and use different frequency bands. A search radar scans huge swaths of sky every few seconds. Good at covering a large area, but accuracy is fairly low. It can tell you \"There's somebody flying around over in this general area\" Track radar is more specific. It scans a smaller piece of sky and scans much more frequently. It can tell you \"There's something roughly the size of a tactical bomber on X heading, at Y altitude, and Z speed\" Fire-control radar scans a tiny piece of sky and does it many times a second. It says to the operator \"That's an F-15, it's got a big scratch in the paint, and the pilot's name is Mike. Wanna shove a missile up Mike's ass?\" A sensor on the plane can detect what kind of radar is looking at it. When it sees a search beam it says \"Someone just swept a big search radar over us\", when it sees a tracking radar it says \"Someone definitely knows we're here\" and when it sees a fire-control radar it starts screaming \"Oh shit Mike, we're fucked!\"",
"They monitor radar signals that are hitting the jet. Plane radar is generally scanning over a larger area, but when targeting a missile the plane will begin to ping a specific area more frequently. The jet being targeted can detect that increased frequency and warns that the radar is \"locking on\".",
"The missile is using a directed radar pulse to track the speed and direction of the target. Unlike a generic sweeping radar that might pulse the plane every few seconds, this new signal is *furiously* pulsing the plane multiple times a second to continuously track it. If an unknown radar frequency is rapidly blasting your plane, something malicious is tracking you. If the radar source is itself moving rapidly across your own radar, it’s a missile or enemy aircraft.",
"Hi Everyone, Please read [**rule 3**]( URL_0 ) (and the rest really) before participating. This is a pretty strict sub, and we know that. Rule 3 covers 3 main things that are really relevant here: **No Joke Answers** **No Anecdotes** **No Off Topic comments** **No Links Without a Written Explanation** This only applies at **top level**, your top level comment needs to be a direct explanation to the question in the title, child comments (comments that are replies to comments) are fair game so long as you don't break Rule 1 (Be Nice). I do hope you guys enjoy the sub and the post otherwise! If you have questions you can let us know here or in modmail. If you have suggestions for the sub we also have r/IdeasForELI5 as basically our suggestions box. Happy commenting!",
"Can modern jets detect heat seeking missiles? How if so? Heat seeking don't use radar do they? Can the infrared homing be detected?",
"In the past, you'd use two different modes for tracking an aircraft. You'd start with a broad sweep with relatively slow pulses to determine if there were any targets in the sky. Once you detected a target, you'd rapidly pulse it to get precise positioning data. This shift from slow to rapid pulse could be detected to determine if you were 'locked on'. Modern radar systems are digital and don't use this sort of mechanism.",
"There are basically two systems which help modern airplanes to know if they've \"locked\". **The first system is the Radar Warning Reciever (RWR).** Long and mid-range missiles tend to use radar to guide them. Semi-passive and Active Radar missiles. Semi-radar only have a reciever and rely on an aircraft or ground radar to \"Paint\" the target. Active radar missiles carry their own radar which does the same thing. The RWR detect this \"painting\" and warns you about it. Since a guidance radar needs to paint the target several times per second it's fairly obvious if you are the target. However, while other practical missile guidance systems tend to be lacking in range (generally heat or optical), they have the advantage that they don't paint the target, so they're harder to detect. **The second system is the MAW (Missile Approach Warning system)** and there are basically three methods that these use to detect missiles. Radar: Radar MAWs vary from really simple (basically a simple radar that points backwards. If it sees something small is closing on you really fast it says MISSILE! MISSILE! MISSILE!) to very advanced (with a wider field of coverage and a smarter computer analysing the signals). Generally these are a part of the Electronic Warfare Pod that can be mounted on aircraft. Radar MAWs have one BIG problem. They send out an active signal. So it makes it possible to find the aircraft by looking for these kind of signals. Although in some cases that's what you want\\* Infrared (IR): Infrared MAWs try to detect the rocket-engine. Since missiles go really fast these engines tend to send out a lot of heat. So when it detects that kind of heat-source it warns you that a missile has been launched. And if that heat source is closing on you it gets really worried. Ultraviolet (UV): The thing is. There is a really big infrared source in the sky (the sun). So in the infrared or the visible light spectrum something like a mirror might trigger an Infrared sensor. That means that the IR sensor might see a reflecting piece of metal as a missile launch. So to make the sensor more effective (and to reduce the dry-cleaning costs for pilot pants) people tried to find an area where sunreflections won't send false signals. And there is a certain spectrum of UV light which is blocked by the ozone layer so the sun can't interfere. Any light in this spectrum has to be man-made, and rocket engines do send out light in this spectrum (it is after all, a really hot fire). So many modern MAWs basically function like the IR sensor, but are instead looking for UV lights. If they find one and it seems to match a missile they warn the pilot about it. & #x200B; \\*There is a air mission type called a \"Wild Weasel\". If you've ever played Dodgeball a Wild Weasel is the equivalent of that athletic guy going \"yeah yeah, you can't hit me sucker\" and trying to taunt you into throwing the ball at him. Such aircraft are loaded to the gills with anti-missile tech, and tries to get SAM systems to reveal their location and shoot at them so that other aircraft can destroy the missile launchers or do their job undisturbed.",
"First off, the radar wave. Radars work by sending out waves of energy. Imagine the ripples in water when you drop something into it. Radar waves work similarly; instead of coming out in a circle, however, the ripples only move in one direction, in the shape of a cone. Imagine your phone’s WiFi image for an idea. The farther out from the radar source, the bigger the wave is. So military aircraft have a device called an RWR - Radar Warning Receiver. This device watches for these pulses of energy from a radar. Imagine the ripples in the water in the above explanation; but put your hand into the water before you drop something into it. Your hand represent the target that the firing plane is shooting at. You’ll notice that with your hand (the target) in the water, when you drop the object into the water, the ripples (the radar wave) will extend out. Once the ripples hit your hand, you’ll notice that the ripples bounce off of your hand (the target) and move back to where they originally came from. The firing plane knows where the target is because it’s radar is watching for these ripples that come back to it, and it’s able to calculate a surprising amount of information based on how these ripples are behaving when they get back to it. It can see how fast the target is moving; in what direction it’s moving, and sometimes it can determine what kind of target it is looking at. Now that you know how the radar works, let’s go back to the RWR (Radar Warning Receiver). Every radar manufacturer has a distinct ripple pattern to it (a distinct radar wave) it produces. Your hand; the target, will have a device (the RWR) that listens for the water ripples (the radar waves). The RWR is programmed with as many known radar emission types to be able to tell not only that a radar is bouncing off of you, but what kind of radar it is as well. Most military jets have their own special radar, so when your RWR sees that a particular Radar is bouncing off of you, it’s able to tell you what kind of plane it is as well. There are several planes that share radar types, most notably the MiG 29 and the Su27. Western RWRs will display both of these as a MiG 29, because it can’t tell which one it is, so the pilot must treat a 29 RWR contact as either a 29 or a 27 until they learn through some other means which type it really is. Going a little bit further, there are two types of radar guided missiles. Semi active and Active. Semi active missiles watch for the ripples (radar waves) that came from the launching aircraft bouncing off of the target and steer toward those until they hit it. Thus if those radar waves stop bouncing off of the target (if the firing plane has to move its radar off of the target) then that missile can no longer track. Active radar missiles have their own small radar inside them. For the first part of their flight they watch for the radar waves generated by the firing aircraft, and once they get close enough to use their own smaller radar they switch to it, generating their own radar waves so that the firing plane can go do something else. Hope this breaks it down well enough for you.",
"The same way police radar detectors work in your car, actually. It's a radio that's listening on a certain frequency. When it picks up a signal, it beeps (that beep is the police speed radar sending out a signal) As the beeps get more repetitive, that's the radar detector hearing more signals on that frequency, until eventually it's a constant beep as the radar is bouncing a strong signal off of you. Fun fact, if you drive by an airport (or a plane with radar flies near your car) the radar detector could go wild as it's bombarded by air search radar. Also the same reason why it goes off next to modern cars, because many blindspot detectors are radar.",
"Crazy-brave pilots intentionally fly into areas to capture the fingerprints of the radar systems being used there. Then other pilots’ radar warning system can recognize which radars are in their area - just like Shazam can listen to a song, create a fingerprint, and compare to all the fingerprints it has of songs. Where does the “crazy-brave” part come in? They taunt a missile site to launch *at their jet* and record the radar signals the site and missile use, from which fingerprints are created to recognize those radars. [Vietnam’s Wild Weasels]( URL_0 ) tells the story of the first Wild Weasel missions. (Long ago I worked for a company that produced the radar warning systems used by the Air Force.)",
"I was radar operator in the us navy. Fire control specifically. If we were doing range testing we would lock on to something like a tall building near Pearl Harbor. What we would not do is lock on to a military jet or commercial jet as it would create an alert to the pilot. The airplane can tolerate a radar “sweep” from a radar but constant illumination means something bad may happen soon. We would sometimes engage a radar towed dummy towed behind a military jet. The dummy was a mile or two behind the jet. We had to make sure we weren’t actually tracking the jet so we would visually confirm we were tracking the dummy and the pilot would also respond ok.",
"Ever wondered what it meant when fighter pilots announced \"Fox 1!\", \"Fox 2\", etec? Theyre refffering to a huge part of your question. A fox 1 is a semi active radar guided missile. Fox 2 is infrared. Fox 3 is active. Fox 1s give the warning you are describing. When these missiles are launched, the plane provides the radar pulse out, while the missile only has a receiver it's like if a person with a knife had his buddy hold the flashlight. Fox 1s, like the Sparrow, need a lot of energy to see the target. So the warning isn't from the launch, it's from the attacking airplanes radar hitting you with constant radar energy. It is safe to assume a missile is on its way but not a given. Because the missile needs the parent aircraft to illuminate the prey, if the parent aircraft turns away and stops lighting up the target, the missle will go blind and sail harmlessly off into oblivion. Fox 2s are infrared. They do not provide the radar warning because they do not use radar to see their target, they just look for your heat signature and try to follow that. Fox 3s are full active radar missiles. They work similar to fox 1s, but they also carry their own illumination equipment (transmitters) so the launching aircraft can turn away. A huge advantage the US had in the 90s and early 2000s was a missile we introduced called the AAMRAM which had the advantage of not giving the warning that you'd been locked up until it was about to hit. Older systems like the Sparrow gave a warning because they required the extra energy of a \"lock\", the AAMRAM would allow a pilot to notice a victim passively in scan mode, use the radar and comouters to rememeeber about where the prey is, tell the missle about where it needed to go and then launch it without a lock up. On the way the missile and parent would remain passive, and the parent would discreetly relay updates to the missile on changes to the targets position. When the missile was within a certain range of where it knew the target should be, it would kick on its own internal radar and light up the target for itself(if youre following along at this point that makes them fox 3s). You would still get a warning, but had very little time to respond. I've hear convincing arguments that the AAMRAM was more of a factor in our dominance in Desert Storm than the Stealth aircraft. One last thing, there are other warning systems than the \"lock up warning\". The system you are thinking of and shown in most movies is called an RWR, Radar Warning Reciever. In practice, RWR not only emits a frantic beepbeepbeepbeep but also chirps when your aircraft is pinged by less concerning scan radars. It emits a unique sound depending on the signal it hears. There are also launch detectors that aim to sense when a infrared missile is on its way, which of course don't send a radar warning when fired. These systems look for the flash accompanied by the missle's motors kicking off and politely inform you it has seen evidence that a missile is on the way.",
"A lot of people here don't know much about modern missiles/rockets. Neither do I, but I did read a book. Apparently modern systems use combinations of infrared, radar, GPS, and optical robotics, just like others have said, except ... by the time the target knows it's locked, the target is pretty much dead. All modern fighter jet warfare has been done out of visible range. So the target (there hasn't been many dogfights in recent decades) is over 100 miles away when they are fired on. It's not like Top Gun.",
"The target plane has both an active and a passive radar system. While the passive radar is used to detect other objects (aircraft) it's the passive radar system that detects the kind of energy that is being directed towards it from an enemy missile. Once the system has detected this level of energy, it sends an alarm to the pilot.",
"Okay so I can weigh in here, I literally specialized in RWR and TEWS when I was in the USAF. So a missile locks on by sending out invisible light and seeing it get reflected back. Kind of like how a bat or Dolphin uses echo location. The jet has detectors in important spots all over it that when they get hit by that light they trigger an alert to a computer. That computer gets signals from all the detectors and figures out which way the missile is coming from and even what kind of missile it is. So think of it like this, the missile is yelling at the plane really loud, and just like your ears can hear what way someone is coming from. The jet can \"hear\" where the missile is coming from. And just like you can tell the difference between a little girl yelling at you and an adult man, the jet can do the same. That triggers a voice warning to the pilot known at \"Bitching Betty.\"",
"There is a system on the aircraft called a Radar Warning Receiver (RWR). It does the job of detecting when an enemy radar is locked on to the aircraft as the target of a missile. There are many different types of missile guidance systems, but the ones that require a \"lock\" are radar guided. The firing aircraft uses radar to \"paint\" the target, similar in concept to a using a laser pointer to single out an object on a slide presentation. The missile then \"rides\" the radar beam all the way to the target. The RWR receives radar energy and then figures out the characteristics of the radar signals it is seeing. It can tell things like a radar's frequency, the time in between radar pulses, and how long the radar pulses last. Radar systems are complex and those developed for high performance aircraft are very complex. As a result of this, each type of aircraft radar has a \"signature\" that makes it possible to identify the type of the radar. With all this in mind, we have a 3 step process for how an RWR works: 1) Radar signals in the environment are detected and characterized by their \"signature\". 2) The signature is checked against an electronic library for enemy aircraft that might use a radar to guide a missile onto the aircraft. 3) When an enemy radar is found to be targeting the aircraft, it alerts the pilot with a visual or audio warning. This is the basic scenario and while all the possible scenarios can be more complex than this, they are all variations on this basic setup. Source: I have developed/designed simulations of 3 different RWR systems for 3 different types of military flight simulators."
],
"score": [
11148,
3010,
449,
100,
65,
28,
16,
13,
9,
5,
5,
5,
5,
4,
3,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[
"https://www.reddit.com/r/explainlikeimfive/about/rules"
],
[],
[],
[],
[],
[],
[
"https://www.historynet.com/vietnams-wild-weasels.htm"
],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jebdih | what is the point of fan ovens being able to turn the fan on by itself | Technology | explainlikeimfive | {
"a_id": [
"g9dezw1",
"g9de2co"
],
"text": [
"It will change your life.. you ready???? You put frozen food on a tray with the door ajar a little and it will defrost in about 1/3 of the time it would just left on the work top",
"I've never heard of a fan-only mode on an oven. o.O Is this a manufacturer-specific thing? The purpose of a fan in an oven is to move the hot air around more actively, so having a fan without heating seems like it would be fairly pointless. The only use I can imagine for such a feature would be \"rapid cooldown\" or somesuch, but even that feels like it would be a stretch."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jedja8 | What is that hot air balloon eye test for? | Just had my eyes tested and wondered what the machine where you have to look at the hot air balloon is for. | Technology | explainlikeimfive | {
"a_id": [
"g9dr4wa"
],
"text": [
"It's called an autorefractor and it determines the starting point for your prescription which is then narrowed down using the \"One? Or Two?\" device."
],
"score": [
13
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jefm1l | Why can’t cold fusion work? | Technology | explainlikeimfive | {
"a_id": [
"g9e79w6",
"g9e39s2"
],
"text": [
"For fusion to take place, a large amount of energy is required to overcome the electrostatic force. Also known as the Coulomb force, this is the force that repels protons in the nucleus from other positively charged particles, like other protons. When two nuclei come close enough together the electrostatic force is overcome by the strong nuclear force, the force that binds fundamental particles together to former larger particles. The challenge for cold fusion is the fact that overcoming the Coulomb force to reach the point at which the strong nuclear force takes over (by way of quantum tunneling) requires a tremendous amount of energy (ie. heat) and pressure (like the gravity at the center of the sun), so keeping this reaction at room temperature and normal pressure is very hard.",
"Cold fusion works fine. Put a bunch of deuterium in a tank and it will fuse. It will take many thousands of years for it to be 50/50 hydrogen and helium, but that reaction has a non-zero probability. Experiments to generate fusion at a faster rate, a rate where one day it might be a power source, have been disappointing. The Ponds/Flieshman experiments got a little hype, which made their disappointment even more troubling as now few folks are likely willing to pursue this particular path. Edison had many, many failures before he got a light bulb that worked, so failing doesn't prove something is impossible at all."
],
"score": [
10,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jefx7o | How do Sensors work? | Technology | explainlikeimfive | {
"a_id": [
"g9e3zj2",
"g9edha3"
],
"text": [
"It's most likely an infrared sensor. Your hands are 98 degrees, the room is 72 degrees. The sensor senses the heat coming off of your skin.",
"They're almost always infrared. Using night vision goggles you can see the pulses of light. They then have a detector that will either look for a reflection of light, or a change in temperature. Some air dryers you stick your hands into may even have a receiver sensor on the opposite side of the transmitting LED and your hands block the light. Open your cell phone camera and point your TV remote at it while pressing a button on the remote. You can see the light pulse coming out. The're using the same things that the tv remote and TV itself have."
],
"score": [
10,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jehb5i | is there any difference between having two ram sticks of 4 gb each and one ram stick of 8 gb? | and if there is, what is that difference? what should i get? | Technology | explainlikeimfive | {
"a_id": [
"g9eczkx"
],
"text": [
"Theoretically, yes. Practically, most likely not. If you install two sticks of matching RAM and your motherboard supports \"dual channel\" mode, then you could see a theoretical boost in RAM utilization because both channels can be run at maximum capacity over an equivalent amount of RAM in a single channel. But realistically I doubt outside of specific applications if that ever really matters. I would be shocked, honestly, if there was any perceptible difference between two 4GB DIMMS in a dual-channel configuration and one 8GB DIMM in a single-channel configuration. Also, just from a practical standpoint I would go with the biggest DIMM your motherboard will support in a given slot because it leaves room for upgrading. For example let's say your motherboard supports up to 8GB per slot and has four slots. If you do 4 x 4GB (for 16GB total) instead of getting the equivalent with 2 x 8GB, then if you want to upgrade you'll have to replace some RAM instead of just adding more."
],
"score": [
12
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jeig4o | before advanced timekeeping technologies, how did we first figure out exactly how long a year was? | Technology | explainlikeimfive | {
"a_id": [
"g9ejvi2",
"g9ek4wn"
],
"text": [
"In early spring, note the position along the horizon at which the Sun rises (and/or sets). For added precision, set up a couple of large stones to mark the alignment. Keep an accurate tally of days as that sunrise position moves north and south and north again. When it's back to that position ... it's been a year. Keep that up for a decade or so. It helps if you're a priest or something, so this is part of your day-job.",
"Every morning, the locations where the sun rises and sets are a little different. [if I get this backwards, be gentle] As you go from summer to winter, in the northern hemisphere, the location of the sunrise should creep further and further south, until you get to the winter solstice, and then it should start creeping north again. At the summer solstice, your sunrise would be as far north as it ever gets, and then it starts the cycle over. Same with the sunset. Creeping south in the fall, then back north in the spring. Not easy to spot if you live on a huge grassy prairie, but if you lived someplace with a nice jaggedy horizon (mountains or buildings or distinctive trees) it would be easier to notice that cycle, and then to say \"in midwinter the sun rises halfway up that peak - it's almost there so I'd say another week or so to midwinter\". Hammer some stakes in the ground, or engrave some marks on a piece of metal, and you can start to really crush those measurements. If you believe that your gods want you have festivals and sacrifices at specific times of year, you'll be motivated to do that work. Likewise if your life depends on farming and you have traditional times to sow and harvest."
],
"score": [
7,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jeisnm | What is the difference between RAM and ROM? | Technology | explainlikeimfive | {
"a_id": [
"g9elpuj",
"g9emvxp"
],
"text": [
"RAM is your computer's \"working memory\" - it's like a huge notepad where the computer can jot down anything it needs to remember as it works. The amount matters, and so does the speed - ideally you'll have a big notebook *and* you'll be able to write in it, and read from it, quickly. The programs you're running get loaded into RAM, as well as any information that comes up as the program runs - the words you're typing, the website you're on, the status of characters in a game, whatever. RAM means Random-Access Memory, meaning the computer can read or write any part of the information whenever it wants. ROM is Read-Only Memory, which means you can't change it. That's much less useful, but also there's no way to screw it up (mostly) so it's good for information like \"my processor is an Athlon 3000g\". The tiniest amount of memory you can have is a bit - a single 1 or 0. If you have eight bits in a row, that's one byte (1B) of memory. About a thousand (1024) bytes of memory makes one kilobyte (kB), 1024 of those make a megabyte (meg or MB) and 1024 of those make a gigabyte (gig or GB), so 4GB is roughly 4 billion bytes. These days, 4GB is an okay-but-not-great amount of RAM, 8GB is a decent amount (I think - haven't bought for over a year) and I think the cool kids are running 16GB or so. [Edit: I thought I had 8 gig but I just checked and I have 16. Woo hoo! Unintentional self-stroke.]",
"RAM stands for \"Random Access Memory\" while ROM stands for \"Read Only Memory\" RAM is used as the \"short term memory\" of your computer. Any programs currently running reside in RAM. The \"Random Access\" part means that data in RAM can be near instantaneously retrieved or written regardless of its location. This is in contrast to another form of data storage like an HDD, where there is a \"seek time\" since the read/write heads have to wait for the platter to rotate and then find the data that they are looking for. The difference is very noticeable if you've ever overtaxed an old computer with a small amount of RAM. When you run out of RAM, the operating system starts using regular storage devices as a sort of \"virtual RAM\". If it didn't, your computer would crash. Since a hard disk is far slower than actual RAM, performance will suffer greatly. SSDs could be considered to be \"random access\" devices as well, although they are still nowhere near as fast as RAM. RAM is incredibly fast, but because of the way it works, the data on it is deleted when power is lost. RAM needs a continuous supply of electricity to maintain the data stored on it. This is why it's not used for general storage. Every time you power down your computer, everything in RAM is gone. There are multiple projects in the works that aim to create a universal memory with the speed of RAM, but that maintains its data when powered down. Higher frequency = more read/write cycles in a given timeframe = better performance. Read Only Memory is just what it sounds like. The data can only be read under ordinary circumstances. ROM is flashed with an image it is meant to retain. A common example would be Nintendo cartrides."
],
"score": [
19,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jels3p | Why has solar power become so much cheaper? | ... and how much cheaper can it get? | Technology | explainlikeimfive | {
"a_id": [
"g9f0sqo"
],
"text": [
"The more industry, research and logistics are devoted to a product, the cheaper it becomes. Since material-, labor- and shipping costs depend on the former factors and margins depend on competition there aren't really any realistic minimum price points to be guessed here."
],
"score": [
12
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jen3ge | How does the science of solar (photovoltaic) panels actually work? | Technology | explainlikeimfive | {
"a_id": [
"g9f6onw"
],
"text": [
"The real science is based on quantum physics which can be hard to explain. But the simple explanation is that photovoltaic cells consists of two different crystal structures bonded together. One side have impurities that cause it to have too many electrons then it should have and the other have impurities that cause it to have too many holes where electrons should have been. This creates a natural voltage gradient preventing electrons from passing one way but do allow them to pass the other way. This is called a diode and is the same construction as is found in LEDs and transistor logic although the size and structure is different. When light hits the PV panel it energizes an electron and can knock it past the gradient into the other side. But due to the voltage gradient it can not return by going steight back. So it gets pushed onwards into the wires that is connected to the crystals which charges the battery."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jeo6ub | What would happen to the Voyagers once they are out of fuel to operate in interstellar space? | In a year or so, there won’t be enough fuel left to keep the heaters working, and everything of value will shut down in both the Voyagers. What will then happen? Will the communication transmission break? | Technology | explainlikeimfive | {
"a_id": [
"g9fc6pv",
"g9fx1dk",
"g9i3nn4"
],
"text": [
"Yes. No energy, no transmission. They will freeze and drift through space forever (or until they randomly hit some other object)",
"Fun fact- the voyagers are so far away from us it takes nearly a full day for the signals to reach us at the speed of light. In 45 years Voyager 1 has traveled 19 light hours. Eventually, we're not going to be able to recieve data from them anymore due to distance. That time is coming very soon. They'll still transmit a while after that, but they'll eventually go quiet. At that time they'll still be hurtling through space at 35,000mph so after a few thousand or tens of thousands of years they'll possibly get trapped in the gravity well of a distant planet or star, and we'll have completed our first bombing run of interstellar space with a kinetic weapon.",
"The voyager probes don't really have much fuel. They continue going because they were launched at high speed, and in space there is nothing that causes them to slow down. They are still able to rotate as they move using gyroscopes powered by electricity, rather than fuel. The Voyager probes have nuclear batteries that last for a long time, but the power output slowly gets weaker. As there is less and less energy, they have to shut down more of the sensors and other systems to save energy. There are clever people at NASA to try to figure out useful things to do with the remaining power budget. Eventually the batteries will get so weak that the probes won't be able to power the radio or gyroscopes. When one or both of these go, we will lose contact with the probe permanently."
],
"score": [
14,
10,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jephvd | Why CGI in early 2000 movies looks more realistic than movies today? | Technology | explainlikeimfive | {
"a_id": [
"g9fjg2m",
"g9fke64"
],
"text": [
"In 1998 CGI was EXPENSIVE. So it was used sparingly and combined with traditional SFX to make things work. As CGI got cheaper movies could use more of it for less money. Now some fast and dirty CGI is actually the cheapest option for most sfx scenes. So we're starting to see a lot of really low quality CGI just because CGI can be cheap now, so it's getting thrown at low budget movies.",
"Godzilla 1998 did not have better special effects than Godzilla 2014. Compare these scenes. URL_1 - 1998 URL_0 - 2014 The lighting on the monsters is better, the actual movement of the feet correspond to the speed of the monsters, they move in less of a slapstick manner etc."
],
"score": [
8,
5
],
"text_urls": [
[],
[
"https://youtu.be/nglTPbYIhf0",
"https://youtu.be/GKuPSf9P3tw"
]
]
} | [
"url"
]
| [
"url"
]
|
|
jerag4 | What's the point of signing something (like signing an iPhone with your finger) if it looks nothing like your actual signature? | Technology | explainlikeimfive | {
"a_id": [
"g9fu47x",
"g9fzl7h"
],
"text": [
"The law lags behind technology. It's easier for tech companies to come up with a tech solution to the problem than it is for the law makers to create a new law.",
"These days, signatures aren't really used to verify your identity in most cases. They're just used as a fancy \"I agree to the above\" checkbox, but one that you can't \"accidentally click\". So no one is getting out of a signed document with an excuse of, \"Oops, I must have accidentally click the button, but I didn't *mean* to agree to this contract!\""
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jest69 | How does Audio in Old Video Games sound "Pixelated"? | Technology | explainlikeimfive | {
"a_id": [
"g9g3e1q",
"g9g35qk",
"g9islye"
],
"text": [
"There’s usually a single chip and it’s designed to take in electrical current and output literally mathematic noise. Most chips have “voices” or the number of notes that can be played at once. On the C64 I believe it had 3 and each one was only one “instrument”. An instrument in this case is a wave form that can be modulated like a square wave. Called as such as it had square edges on an oscilloscope. So these waves are modulated to make sound kind of like how a human hums, but since they are digital signals being turned into analog sounds they have little points where they aren’t fluid so they sound “chirpy” or pixelated. Now some ppl can get these chips to sound divine with a lot of work, but games didn’t have the time or luxury to do this so they went with noisier solutions. Check out Chiptunes in the ‘Tube or the 8-Bit guy/8 Bit Keys for more!",
"I'm afraid your question is too simple, the bots won't like it. Pixelated the word refers only to images. But I get what you mean. Simple music can sound very pixelated because it is made of up very simple tones, there's no fading in or out of notes, it's just different tones playing in a timed order. It's not recorded music like a song. So, it's not pixelated, I understand why you think of it that way, I don't really know what else to say.",
"There are a couple of different reasons: 1. Back in the days of 8-bit and 16-bit consoles, consoles and cartridges didn't have enough memory to store their soundtracks as audio files. Instead, consoles had basic synthesizers built into them to create the music on the fly. The cartridge would contain a series of instructions saying what note to play and when, which would be passed along to the synthesizer to create the music. 2. These synthesizers were fairly limited in their capabilities. The gameboy, for example, had 4 audio channels that could play at once: two square waves, a programmable wavetable, and a noise generator. The NES had 2 square wave channels, a triangle wave channel, a noise channel, and a channel that could play a short audio clip. [Take a look at this video]( URL_5 ), showing what each of the NES' audio channels (minus the sample channel, which is not used here) is doing while playing the Legend of Zelda theme. This meant that the developers didn't have a lot to work with in terms of audio. Music on the gameboy and NES could have at most 3 notes playing at once, and developers would have to create \"drums\" with little clicks of white noise and low-pitched notes. If the developers wanted to use anything other than what they could create with the built-in synthesizer - a guitar, or a flute, or a piano, for example - they were simply out of luck. 3. The bit depth. It's easy for a digital system to produce an output that is either on or off, 0 or 1, but they can't create any in-between values on their own. Without being able to make any values in between 0 and 1, they can't really create anything except for a square wave. To create in-between voltages, a device called a digital to analog converter (or DAC) is used. DACs only have a limited amount of precision - maybe they'll be able to make 16 or 256 unique values - which means that if you attempt to make a smooth curve or angle, it will round it to the nearest values the DAC can produce and turn your smooth waveform into a series of steps. For example, look at how a [perfect triangle wave]( URL_0 ) looks versus how the [NES's triangle wave]( URL_4 ) looks. The NES' white noise generator also isn't a true white noise generator, which would produce a signal that would randomly increase and decrease. The NES' white noise generator actually just switches on and off at random, hence its unique sound. The precision of a DAC, the range of values it can produce, is called bit depth. A higher bit depth means a less steppy waveform and greater precision to the way it's 'supposed' to sound. An NES's triangle wave generator uses a 4 bit DAC, which can produce just 2^4 or 16 different values. Nearly all audio you hear nowadays is 16 bit, which allows for 2^16 or 65536 different values. [Here's a little demonstration I just made]( URL_1 ), the first thing you hear is a modern 16-bit triangle wave, the second is a 4-bit triangle wave like you'd get on an NES. Notice how different they sound? 4. The sample rate. Digital audio has a second important parameter that determines its quality: sample rate. As you may have figured out from the picture of the NES triangle wave, digital audio systems approximate smooth sound waves by creating a series of values that more or less follow the same shape. Sample rate determines how often a new value (a sample) is outputted. Most high-quality digital audio nowadays has a sample rate of 44.1 kHz, which means that a new value is put out 44,100 times a second. If the sample rate is too low, a phenomenon called aliasing takes place which creates very distinct artefacts in the sound. I'm already pushing the limits of ELI5 so I won't try to explain it, but if you're interested in learning more about it, you can look for information on Nyquist-Shannon sampling theorem. [Here's an example I made of the effect that sample rate has on audio]( URL_3 ). The sample rate starts at a normal 44.1kHz, but gradually decreases more and more over the course of the clip until it gets to just 300 Hz. Artefacts become audible, and the piano is unrecognizable by the end. This is most relevant when talking about things that play audio clips rather than synthesizing audio on the fly, like the fifth audio channel on the NES. Audio clips can take up a lot of memory. One second of uncompressed 16 bit 44.1 kHz audio takes up ~88 kilobytes, or about 5 megabytes for a minute. NES cartridges usually only had a couple hundred kilobytes to work with, so any audio clips needed to be as compact as possible. For this reason, they used very low sample rates, and the low bit depths of the NES' DACs required them to use low bit depths as well. The low sample rate and bit depth results in the distinct lo-fi sound of voice clips played on the NES. [Here's an example]( URL_2 ). That's about it! Sorry if this was a bit too complex, I'm happy to answer any follow-up questions or try to explain stuff better. I hope this helped with your understanding!"
],
"score": [
16,
3,
3
],
"text_urls": [
[],
[],
[
"https://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Synthesis_triangle.gif/350px-Synthesis_triangle.gif",
"https://clyp.it/nxkwc1bd?token=c4273c2684a7b4603170a8b0399ee865",
"https://clyp.it/qc2tub0p?token=ebbe0d878dff4b2bde49c12b64443184",
"https://clyp.it/qljo35x2?token=4e6de3f49edcf1a0cb58ed01d698e532",
"https://64.media.tumblr.com/7aaeb4ae1744c235d59f7ce6375a9f4f/tumblr_inline_os39gvDOQ51r8cudp_500.png",
"https://youtu.be/gKXGDuKrCfA"
]
]
} | [
"url"
]
| [
"url"
]
|
|
jexkcf | How can a camera lens tell what is close up and what is far away when it refocuses? | Technology | explainlikeimfive | {
"a_id": [
"g9gz0te"
],
"text": [
"The lens does not do that it is the camera. The focus is changed by moving elements in the lens but it is the camera body that controls the motion. It is multiple ways it can be done. The simples to explain is contrast-detection. It works like if you focus it manually move the lens so the area you focus on is as sharp as possible. A shape image has a higher difference in values of neighboring pixels than an unsharp image. So the camera changes the focus and compares it to how the constant change. Change it in the direction so the contrast gets higher and stop when it starts to get lower again. The camera is in focus if the contrast gets lower if you change the focus in any direction. You might have noticed that is not uncommon for a camera to move the focus in the correct direction get info focus and slightly out of focus and back to focus again. That is when happens on contrast detection. & #x200B; There are other ways that measure the distance with the option and even with direct measurement of the distance by sending out a plus of light and detect how long time it takes until it is reflected and return to the camera. This is like how a RADAR or laser measuring tools works You can read about others ways in the wiki [Autofocus]( URL_0 ) artic.e"
],
"score": [
7
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Autofocus"
]
]
} | [
"url"
]
| [
"url"
]
|
|
jexx1u | How does the internet work? | Whenever I’ve asked this to someone they just give me some nonchalant sentence that goes like “it’s a bunch of servers connected to each other”. I’m 30 and still don’t understand how the internet works exactly. | Technology | explainlikeimfive | {
"a_id": [
"g9gzmod",
"g9hrcm3",
"g9gzqx9",
"g9iqg8y"
],
"text": [
"if you think of it this way. the internet is like people relaying messages to each other. the computers (or people) want to talk to each other. but they have no direct way of talking to each other. what they do instead is go through intermediaries aka other computers/networking equipment that relay messages to each other. if you're in school, and you want to pass a note to your best friend across the room, what to you do? you write the note, fold it, put a label on it with the name, and pass it to someone next to you, which sees the name, then they pass it to someone else in the direction of your friend, until it reaches your friend. your friend sees the note, see's the message, sees that it's from you. and does the reverse to send a message back to you. now that is a very rudimentary example of \"the internet\". the \"internet\" there is basically the classroom full of students. each student is a node in the internet and also a host/client that can send/receive notes as well as pass notes across. that's how the internet works. just a bunch of computers or students that are connected to each other (ie they have some method to transmit data between them, whether it be hand passing notes, talking, sending signals on a wire, etc).",
"Imagine I have some information you want, it could be a picture, a song, a video, or document about spiders webs. Before the internet, you had to write me a letter requesting that I send you the pic or the page or what ever you wanted, so you write me a letter telling me what you want, you put it in an envelope, write my address on it and drop it in a post box. Once posted it does not travel directly to me, it goes from one mail sorting office, to another and another until eventually it gets delivered to me. I open the letter, find out what you want, then take the information you requested, put it in an envelope, write your address on it, and post it back to you. Once posted it does not travel directly to you, it goes from one mail centre to another to another and eventually gets delivered to your door. The internet uses the exact same principal, its just done using electrical pulses (a bit like morse code). If you want from information from me now, your computer will send me an electronic letter asking for it, lets say you want a page about spiders webs, lets call it a web page lol. Your computer must know the address to send the request to, we call this an IP address but it’s no different from a postal address or phone number in principal. If your computer doesn’t know my IP address, it can look it up, which is just like looking someone up in the phone book. So your computer takes your request, puts my ip address on it, and sends it electronically using pulses, to your local ‘sorting office’ at your internet provider. The term we use for this electronic sorting office is a server, because it serves you with information when you ask for it. Now just like the postal service, that electronic request will be sent using pulses, from one sorting office (server) to another and another until it gets delivered to me. My computer (server) opens the request, finds out what information you want and where to send the reply, it then takes the ‘web page’ you asked for, puts your IP address on it, and sends it to my local server, which forwards it on and on from server to server until it reaches you, just like the postal service does. This is a super basic explanation that glosses over a LOT, but I very much hope it might help you grasp the concepts of how the internet sends and receives information.",
"That's the jist of it. The internet is a collection of \"computers\" controlled by other routers. When you make a search, your query is sent to a router who looks for where your specific request's computer is located. There are multiple levels to this search. Say you search for URL_0 , the router looks to see if this site is cached (stored locally, knows where it is). If it can't find it in the cache, it makes sends the request to routers higher up. If none of them can find it, the request goes to the top level router that searches the .com for www.reddit This is a really fast process which happenes while the page loads. This search can be thought of how post travels through the Postal Service. A packet is sent (your letter) and it the postal/ zip code determine where to send the request. Once the request is received by the \"new\" office, another lookup for the home number is made. At that point, the delivery is complete. Hope this helps!",
"Here's a copy of my answer to this question on a thread that asked this a couple months ago. It approaches the question as a series of problems we ran into when creating what would become the Internet and the solutions we came up with to solve them. --- Let's start small and work our way up. My computer wants to send your computer a message. How can we acheive this? Simple. Wire them up, and send the message over the wire. Easy. Now, what if we have many computers in our building? They should all be able to talk to each other. But if I send a message intended for you, only you should get it. What do we do, link every computer to every other computer with its own cable? That would not scale well. They should all be able to share one common line, where all the local computers in the area can communicate. A **local area network**, or **LAN**, if you will. But now every computer is now broadcasting every message to everyone. How can we tell which messages are for who? How about... we assign every computer on the network a special ID number. A permanent ID baked into the hardware that uniquely identifies that device wherever it goes. Now, when my computer talks to yours, it can sign the message as TO: < your ID > , so your computer knows it needs to read it, and everyone else can ignore it. I can also sign it FROM: < my ID > , so if you need to respond, you know who to send your response to. So now we have IDs that are kind of like mailing *addresses*, that *control* who can *access* certain *media*. A *media access control address*. Perhaps, **MAC address**, for short. So now we have a world full of local networks, that's well and good. But what if I want to talk to a computer *outside* my network? We need a way to go *between networks*. (How can we make that sound catchier? *Inter-network*? **Internet**?) We could just combine our networks outright, but we want to maintain some autonomy over how we run the place, so we want some separation. How about, we each take one computer from each of our networks, and link only those two together on a seperate line. Then, any time one of our computers wants to talk to a computer on the other network, it forwards the message to that special computer, who sends it through the special line, and the other special computer delivers it. These special computers *route* messages to their intended destination... we'll call them **routers**. But we have a problem. Now I can't just sign my messages as TO: < your MAC > anymore. I have to sign them to my router's MAC so it knows to read them. Even if I put in some kind of footnote telling the router to forward it to you, it still doesn't know where your computer is. All my router sees is my network, and all the other routers it may be hooked up to. And I certainly don't know ahead of time what chain of routers lead to you. How could I, with computers constantly connecting and disconnecting all over the world? This MAC thing isn't going to cut it. We're going to need a new *protocol* if we're gonna talk over the *Internet*. An *Internet Protocol*, or **IP** for short. Let's create an entirely new kind of address for this, an **IP address**, that is designed with a built-in hierarchy that routers can read to decide where in the Internet the address is. We'll let one central corporation control all these addresses so it's clear who owns each one. This corporation can sell huge blocks of them to other companies, who can then further subdivide those blocks and sell them... somewhere down the line, a company starts selling individual IP addresses to end customers. These are your *Internet service providers*. You pay them to dig a cable to your house that you plug into your router, and they let your router rent one of their IP addresses. Any time a message for that address hits their system, they forward it to your router, and any message they get from your router, they will pass on to wherever it needs to go. So, recap. I want to send your computer a message. I don't know your MAC, but I have your IP address (how I got your IP address is its own long-winded answer, it usually involves something called DNS). I write my message, sign it with my MAC, sign it to my router's MAC and to your IP, and I send it. My router reads it, sees your IP, and uses it to figure out which router nearby has the best chance of knowing where that is (this is also a fiendishly complicated process), and sends it there, with a FROM: < my IP > attached to it. From there, a bucket brigade of routers pass the message along, always trying to match the branch of the Internet that matches your IP. With luck, it finds your router, which finally delivers the message to your computer. If you respond back, this all repeats in reverse. This is the gist of how all communication over the Internet works."
],
"score": [
21,
6,
4,
3
],
"text_urls": [
[],
[],
[
"www.reddit.com"
],
[]
]
} | [
"url"
]
| [
"url"
]
|
jey77e | With the massive increase in bandwidth and network speeds, why do web browsers and other internet apps continue to use caching? | I just went through the apps on my phone and cleared the cache on my Chrome and Reddit apps. The cache was quite large on both, and it made me wonder why these types applications even use caching anymore. Plus if I ever go back to a page, generally I want the most up to data and wouldn't even want the cached version. | Technology | explainlikeimfive | {
"a_id": [
"g9h1l6z",
"g9h4me9"
],
"text": [
"Because network speeds aren't *that* good. For the most part, caching has very few drawbacks. Most web/app content doesn't change very frequently (if at all), and it will always be faster to recall a cached local copy than request a new one from a server. The difference might be milliseconds, but it adds up. And even milliseconds matter. There's a great deal of research that suggests that our perceptions of an app are greatly shaped by how responsive it is, and even very slight delays can give us a bad impression. And lastly, caching eliminates an enormous amount of network traffic. If every asset on every website in the world had to be requested fresh from the server and was never cached, it would massively degrade most networks' performance.",
"With the massive increase in bandwidth and network speeds, we also have a massive increase in the amount of data getting sent back and forth. EVERYTHING'S increasing, so it's not necessarily going to be faster."
],
"score": [
11,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jeygfd | What are all the different types of noises that an MRI makes when you’re getting a scan? And why is it different noises every few minutes? | Technology | explainlikeimfive | {
"a_id": [
"g9hrvt1",
"g9hikg9",
"g9hqmz6",
"g9hq5tz"
],
"text": [
"An MRI machine collects data by delivering electromagnetic energy into the body to ‘flip’ the spins of nuclei in the body. When the nuclei flip back, they emit electromagnetic signals of the same frequency that are then detected by the system. The machine is set to have as homogeneous a magnetic field as possible at the center of the tube when nothing is happening. When a scan is taking place, the system rapidly changes the magnetic field within the magnet, using gradient coils, to provide spatial information. The sounds you hear have a variety of purposes. The slow knocking sounds that precede a scan are a pulse sequence designed to tune the cool to maximize the signal returned from the body. Then, the rapid knocking is from the rapid changes in the gradient coils during the scan itself. Different scanning sequences change the gradients at different rates, so the frequency of the sound you hear differs. The gradient coils that sit on the outside of the magnet are long loops of wire that vibrate due to the current pulsing through them during the scan. What you hear is that vibration. Source: spent 10 years working for MRI vendor.",
"You might be interested [in this recent Reddit post]( URL_0 ) that shows a CT scanner running at full speed without its cover on. There is lots of information about these and MRI scanners in the comments, including an explanation about the sounds.",
"The noise is caused by the vibration of metal coils inside the machine. Inside an MRI is a big magnet and large coil of wire. To take a 3D picture, the high power coils pulse on and off. Energizing a coil of wire creates a magnetic field. This field is SO powerful that it causes the actual wire to vibrate. During a scan the coils are rapidly switched on and off, creating a loud pulsing sound. During a scan the control computers modify the signals sent to the coils. A faster pulse for example will likewise sound quicker in pace. I am not an MRI tech, but I assume the different signals modify the properties of the image. Have you ever heard the low hum of large electrical transformers / equipment? The same principle applies.",
"I was told the first scans are low-res and let the shot be setup or aimed correctly. Then when all's good, hit the higher res scans. There's differences in power, frequencies, etc. for low- vs. high-res scanning, and the machine sounds different when these variables change. Source: had an MRI, asked the technician."
],
"score": [
61,
13,
5,
3
],
"text_urls": [
[],
[
"https://www.reddit.com/r/mechanical_gifs/comments/iy4ej9/a_ct_scanner_at_full_speed_without_the_cover/?utm_source=share&utm_medium=ios_app&utm_name=iossmf"
],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jeyohy | Why is 8d music called that? | I like 8d music but I’ve always wondered why it’s called that | Technology | explainlikeimfive | {
"a_id": [
"g9h4agz"
],
"text": [
"It's 8 directions, not 8 dimensions. It's because the source can move forward, backwards, left and right, up and down and around you"
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jezbha | What would happen if I charge my phone with a charger that produces higher watts | e.g. my iPhone 11 charger is 18w but I use my MacBook Pro to charge is (which is 61w) | Technology | explainlikeimfive | {
"a_id": [
"g9h9loj"
],
"text": [
"Nothing. The actual charging circuitry is inside the phone, and the phone will only draw as much current from the charger as it needs, In fact phone chargers shouldn't even be called chargers. They're just power supplies."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jf0j0c | How is a wi-fi enabled device able to tell the signals from one specific wireless router from the (potentially) hundreds of other wireless routers in range? | Also, how is it able to simply do a scan and see all the wi-fi networks in range? Wouldn't all those separate wireless signals travelling through the air at the same time interfere with each other to some degree? | Technology | explainlikeimfive | {
"a_id": [
"g9hks9y"
],
"text": [
"Wifi breaks the frequency in channels similar to TV. Your computer or phone will surf through the channels and listen for a bit to see what is on the channel. Each access point or router will broadcast a unique ID number and also a name set by the user. This scan will make the list of networks in the area that you can try to connect to. When a device wants to talk it listens and waits until nobody else is talking. When done it listens for the other side to say that they got the message. If two talk at the same time the message will not be acknowledged and they will know that they need to wait and resend."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jf2jlh | Why cant we rename folders when a file inside is opened/in use? | Technology | explainlikeimfive | {
"a_id": [
"g9ht4to"
],
"text": [
"Because whatever program has the file open is accessing the file by its \"path\", which is the entire sequence of folders and sub-folders and sub-sub-folders starting at the root of the hard drive. If you renamed one of the folders along that path, the program would no longer know where the file was while potentially being in the middle of modifying it, which could data loss."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jf3bgz | how the heck do waveforms (like sine, saw, or square waves) work? | EDIT: Explanation I mean how do they make the sound that they do, why do they sound the way that that do? | Technology | explainlikeimfive | {
"a_id": [
"g9hzayp"
],
"text": [
"This video is a bit above eli5 level, but it's a very good introduction to how a particular shape of waveform can contain many different frequency components. URL_0"
],
"score": [
3
],
"text_urls": [
[
"https://www.youtube.com/watch?v=spUNpyF58BY&vl=ar"
]
]
} | [
"url"
]
| [
"url"
]
|
jf468e | How can a car battery die from a light being left on overnight, then a quick jumper cable charge has it good as new for months+? | Technology | explainlikeimfive | {
"a_id": [
"g9i308v",
"g9i2w3a",
"g9i3711"
],
"text": [
"Whenever your engine's running, your alternator should be working, and one of its jobs is to recharge your battery. So whenever you go for a decently-long drive, your battery charge should increase. If everything's working well you'll get to full charge and stay there. As long as the boost gets your engine started and then you run it for a bit, you'll recharge the battery enough to keep the cycle going. If your alternator is underperforming, or if you have corroded contacts, or if your battery's getting old, or if you go for a lot of short trips, then you're spending |----| this much juice starting the engine and only getting |--| this much back from the drive. Keep doing that, and you'll wear your battery down.",
"The jumper Charge is not actually charging the battery it is using the other cars battery to start which in turn gets the alternator going which is what keeps a car battery charged though doing this a lot will ruin your cars alternator.",
"Lead acid batteries have a very low \"depth of discharge\"- once about 7% of the energy has been drained the voltage drops too low to power the starter motor. Once you jumpstart the car you usually leave it running for a while or go for a drive, which lets the generator put that 7% of energy back in pretty quickly."
],
"score": [
7,
3,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jf47q2 | Why does iPhone (and I presume Androids as well) display cellular connection in the status bar as "3G" or "5G", but "LTE" instead of "4G"? | Technology | explainlikeimfive | {
"a_id": [
"g9ie9y7",
"g9i3k93"
],
"text": [
"I seem to recall AT & T lieing and advertising as the first to 4G, which was actually 3G with extended backhaul (HSPA+). 4G LTE was advertised to differentiate from the \"fake\" 4G advertised by AT & T.",
"\"LTE\" was originally used because early networks did not quite meet the 4G standard, although they were still faster than 3G. Most networks are now LTE-A and do meet the 4G standard. Source: URL_0 Speculation: It could be that the OSs simply lump them together for the sake of simplicity."
],
"score": [
23,
14
],
"text_urls": [
[],
[
"https://www.androidauthority.com/4g-vs-lte-274882/"
]
]
} | [
"url"
]
| [
"url"
]
|
|
jf4rsh | How do wireless chargers work? Like honestly how do they charge phones and whatnot | Technology | explainlikeimfive | {
"a_id": [
"g9i8te1"
],
"text": [
"iductivity. when current goes through a circle, it creates magnetic field. when magnetic field changes, it makes current in metal circles. so, you have a pad with a circle, through wich current goes & changes regularly. it changes the magnetic field, which affects current in a circle that is inside your phone. this current charges the battery"
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jf67sn | Why Would YouTube Enforce COPPA Regulations? | Technology | explainlikeimfive | {
"a_id": [
"g9ifng1"
],
"text": [
"COPPA is a law in the US, YouTube is a US-based company. To remain a legal business, they are required to comply with COPPA. Their other option is to move their entire business outside the US, but that could cause other complications of ISPs potentially blocking access to comply with COPPA regulations regarding YouTube, significantly reducing potential traffic (and therefore profit). So yes, parents are responsible for monitoring what their kids do, but enough parents complained because they didn't, or couldn't, regulate their kids that lawmakers said \"Lets make it a regulation so businesses hold responsibility\". And so a law was created, passed, and enforced....making businesses either follow the new laws, or move out of the US."
],
"score": [
10
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jf6lee | Why does stuff videoed from far away look like its going in slow motion until it gets close? | Ive noticed this a couple times, the most notable and recent of which being this clip from r/videos URL_0 | Technology | explainlikeimfive | {
"a_id": [
"g9iiw7x"
],
"text": [
"Part of it is we track motion in general by how fast it travels across our eyes. And stuff farther away has to move a longer distance to cover the same angle as something a foot away. Another part is that there's no real evolutionary reason to treat fast moving objects that are far away with too much importance. If a car is moving at 60mph a mile away it's still going to take close to a minute before it's your problem and that's only it's directly aimed at you perfectly which it probably isn't. So it isn't as immediately important to dodging/interacting with,etc as bike moving 5 mph a few feet from you."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jf7hja | How does youtube know I have watched enough of a video to justify paying a creator? | Technology | explainlikeimfive | {
"a_id": [
"g9imv3f"
],
"text": [
"around 30 seconds. But this progress bar isn't for the creator it's for you the viewer to more easily see if you've seen the whole thing and isn't connected to if they get paid or not"
],
"score": [
9
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jf7ka6 | Why is Africa frequently shown as smaller than its actua size on maps? (Or I guess why are maps in general not proportionate??) | I've seen a (non) literal billion maps with different depictions of how large Africa is. I gather that it is actually far larger than the United States, but it doesn't usually seem to be depicted that way. This seriously confuses me. ISS flyovers give a good idea of the difference. Why are so many maps disproportionate? | Technology | explainlikeimfive | {
"a_id": [
"g9imuvx",
"g9in5zs",
"g9inw9q"
],
"text": [
"There’s no clean way to convert from a sphere to a flat drawing. Different maps use different methods of conversion, but each method tends to distort certain continents by making them look bigger or smaller. You can read about the Mercator projection for more details.",
"It wasn't an evil and intentional conspiracy to diminish Africa's standing in the world. The Mercator projection is good for navigators, because you can read correct compass headings off it. That's basically why it became a popular type of map. Something has to give when you put a 3D surface onto a 2D sheet of paper, either the proportions or the orientations. People who wanted to sail from A to B chose the map that gave them correct orientation.",
"Wanted to add to the other two posts that the reason Africa in particular gets so distorted into a smaller size is because so much of it is in close proximity to the equator. When converting to a 2D surface in a lot of projections, the space and shape near the equator becomes smaller and the spaces near the poles becomes larger. This is also why Greenland appears huge AF. Adding this clip because it’s always a good watch. URL_0"
],
"score": [
26,
19,
13
],
"text_urls": [
[],
[],
[
"https://youtu.be/vVX-PrBRtTY"
]
]
} | [
"url"
]
| [
"url"
]
|
jfao71 | How do those “power saver” boxes work, if it all, to reduce household appliance electricity usage? | Technology | explainlikeimfive | {
"a_id": [
"g9j2r9g",
"g9j33q5"
],
"text": [
"As far I am aware they don't. They shift power between real and inductive/capacitive, but unless you have a contract that reflects those (big power consumers like factories so) it won't change your bill at all. So it's basically a scam, because a multimeter will show lower currents, but the electric company counts the actual power you consumed and not the current a multimeter shows. The total power is dependant on Voltage, Current and Phase power factor (how simultanous Voltage and Current are). The device increases the power factor, reducing the current, but not your bill.",
"They have a blinking LED, and that makes people think it's actually doing something. They work in the sense that they make money for the people selling them. They claim to improve the power factor, and without going into detail about what the power factor is, it's enough to know that a) the power factor doesn't matter at all in residential buildings b) the amount of actual circuitry contained within the device is too small by several orders of magnitude to do what it's claiming to do It's just a blinking light."
],
"score": [
9,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jfc4p6 | Why bother with the URL_0 ? Is there another option? | While we no longer need to write out the " URL_0 " in order to get to our website of choice, indeed most of us just search google for it now, I'm wondering what the purpose of this ever was. Why did this need to be spelled out? What was the original purpose of it? Perhaps a pre-web-browser thing? DO we still need this as a prefix to every website? Is there some other option to hypertext transfer or the world wide web that I'm not aware of? | Technology | explainlikeimfive | {
"a_id": [
"g9jchpp",
"g9jbbot",
"g9jded8",
"g9kgbfl",
"g9jauaa",
"g9jb97c"
],
"text": [
"When all of this was developed, there was no telling how these interconnected sets of computers would be used by the public at large. So things were designed with lots of flexibility and openness. The first part, the \"https://\" is the protocol. A protocol is basically just an agreed upon way of doing things. HTTPS, which is \"Secure\" HTTP is the protocol for how to managed web pages, primarily requesting and retrieving them. The \"www\" is part of the domain. Domains and subdomains are how things are organized and found on the internet. An organization \"owns\" the .com Top Level Domain. If you want to be part of it, you have to buy a domain from them, such as \"[ URL_2 ]( URL_1 ).\" Then you can add as many sub domains as you want, usually reserved for different kinds of services. Like \"[mail. URL_2 ](https://mail. URL_2 )\" \"[calendar. URL_2 ](https://calendar. URL_2 )\" \"[drives. URL_2 ](https://drives. URL_2 )\" etc. WWW stands for \"world wide web\" and was used for your typical web page. As the Internet developed and became wide spread, everyone was using HTTP and HTTPS to access www. pages. They became so ubiquitous, that it became safe to just assume that, if someone was going to a place, they were going to \"[ URL_0 ]( URL_0 ).\" so browsers and web pages simply started being programmed to use that as the default unless the user specified something else.",
"The \"http\" and \"https\" are what are known as \"URI schemes\". [Here's a list of all valid schemes]( URL_0 ). They range from things like \"ftp://\" for FTP file transfer links, to \"mailto://\" for links to send someone email, to \"magnet://\" for BitTorrent magnet links, along with *dozens* of others. A fun one to try if you're using Chrome is \"chrome://flags\" (I used that to enable tab groups, which lets you right-click on tabs and assign them to groups to keep things organized). As for the \"www\" part, that's what's referred to as a \"subdomain\", and it's *not* always \"www\". For instance, that Wikipedia article that I linked begins with \"**en**. URL_1 \", to indicate that it's the English-language Wikipedia. Replacing \"en\" with a different language code will get you a different website that is written in the appropriate language. And that's not some sort of auto-translate thing. Different subdomains route you to different HTML pages.",
"You're asking about the structure of a Uniform Resource Locator (URL). A URL is a specific instance of a URI (Uniform Resource Identifier). They are used to identify the location of specific resources on the Internet. A URL has several parts. The **protocol** is the part before \"://\". It identifies to the client (the browser) what communication protocol to use to retrieve the requested material. HTTP stands for \"HyperText Transfer Protocol\" and HTTPS for HTTP Secure. These indicates to the browser that the protocol you are using is a request for a document (web page) from a web server. There are other protocols for communicating with other types of servers, e.g. FTP (file transfer protocol), SMTP (sendmail transfer protocol), RTSP (real time streaming protocol), etc. etc. However, those other protocols are frequently abstracted away from the end user by applications or in settings. The **domain** (e.g. \" URL_2 \") is a unique address that its owner can use for the direction of requests to servers (web server or otherwise) under it's control. It consists of the domain name (\"google\" in this example) and the top-level domain or TLD (\".com\"). TLDs are limited and typically controlled by national or non-profit organizations. The domain name is requested by its owner, but issued by that organization and attached to a TLD. The \"www\" is a **subdomain**. Subdomains are used by the domain owner to further direct traffic to the appropriate servers under their control. Unlike domains, the subdomains are totally in the control of the domain owner; the owner does not need to request them from an issuing agency, like they do with domains. The subdomain \"www\" is the *default* subdomain used by most web servers, but there's no reason it *must* be used. It's just a common convention. **Do you still need this? Yes, absolutely.** Traffic originating in a web browser relies upon the formal construction (the syntax) of a URL to communicate with a web server. Modern web browsers will take care of some of this for you, e.g. if you type \" URL_2 \" into the address bar of your browser, it will automatically prefix it with the default \" URL_0 .\" or \" URL_1 .\" because the request to Google's webservers *literally* will not work without that. However, since that's a *technical* requirement for one application (the web client) to talk to another application (the web server), and not something humans really need to understand in full, browser developers and web designers have tried to remove as much of the burden from the end user of having to know and understand all of that.",
"A bit more ELI5 than the others: https tells your browser what language it should use to talk to the other end of the conversation. There are many others, many of which work with the browser. The first introduction conversation your browser has with the server needs to be in the same language so they can understand each other. https is like \"I would like to have this conversation in English\".",
"Yes, there are other protocols than https. For example ftp, wich is used for file transfer. And house internal nets can use the same adress system.",
"Not all internet addresses have the www - your bigger websites have redundancy in their address so that typing with or without the www will refer you to the same page and the same with http and https. BTW whenever using a secure password or credit card details make sure the site is showing as http**s** The alternative which is nearly out of use is \"ftp\" - File Transfer Protocol. This has been largely been replaced with more secure file sharing like Google Drive. Corporations can operate their own internal system called Intranet."
],
"score": [
52,
27,
8,
5,
4,
3
],
"text_urls": [
[
"https://www",
"https://google.com",
"google.com",
"drives.google.com",
"calendar.google.com",
"mail.google.com",
"https://calendar.google.com",
"https://drives.google.com",
"https://mail.google.com"
],
[
"https://en.wikipedia.org/wiki/List_of_URI_schemes",
"wikipedia.org"
],
[
"http://www",
"https://www",
"google.com"
],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jfesle | How can radios tune in to multiple frequencies if their antennas are a fixed length? | If antennas should be exactly half the size of the wavelength of the signal, how can radios tune in to a wide range of frequencies? Also, can you change the range of a radio receiver by just replacing the antenna or is there more to it than that? | Technology | explainlikeimfive | {
"a_id": [
"g9jwmrk",
"g9ku0by"
],
"text": [
"The tuning isn't done with the antenna, it's done by adjusting the resonant frequency of a little circuit inside the radio. That circuit has a high \"Q\", meaning it's really good at amplifying signals that are right at the current tuned frequency, and really good at suppressing signals that are not. Like it will be perhaps 100X difference in performance for a 1% change in frequency. In comparison, the variation in performance with antenna length is not very steep for car radios. It's more like a 1% change in performance for a 1% change in frequency. (NOTE: I made up the numbers 1% and 100X because I didn't feel like looking up the typical actual numbers, but this is ELI5, not AskEngineers) FM: The entire FM frequency band (in the US) varies by only about +- 10%, which is basically negligible when it comes to FM receiving. FM radio performance is really insensitive to the actual signal intensity, since the signal is encoded in rapid, small changes in the frequency without any concern for the actual amplitude. So as long as the antenna is roughly the right length it will work. You could probably cut foot of length off your car antenna and you wouldn't be able to detect difference in FM performance. (Your favorite station that suddenly drops out when you're 60miles from home will instead suddenly drop out when you're 58miles from home, but who notices that?) AM: AM performance does depend more strongly on how well the antenna performs. The AM band is much wider, with a factor of 3 in freq from lowest channel to highest, so the optimum antenna length should also vary by a factor of 3 depending on the station you're listening to. But the difference isn't much compared to other factors such as distance to the transmitter. If you cut a foot off the antenna, your AM signal-to-noise performance would get worse for some channels and better for others. You still would have a hard time noticing the difference -- it would sound a bit noisier on some channels and clearer on others.",
"Antenna length only determines the frequency that the antenna is most sensitive to. Frequencies further from the peak frequency will be quieter, so antennas are generally designed for the mid-band. The radio then has an internal filter of some kind that can be swept across the entire band to select exactly which station you want to listen to."
],
"score": [
13,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jfgvqy | How did Roman technology get lost and how did it stay lost for so long? | Technology | explainlikeimfive | {
"a_id": [
"g9k57rx",
"g9kf60k",
"g9kxgb0",
"g9k53qv"
],
"text": [
"It’s a bit of a false history that Roman technology was collectively lost for centuries. Facing internal divisions and external pressure, the Roman Empire split in half in the 4th century and the western half collapsed soon after. The Eastern half survived for another 1000 years before falling to the Ottomans in the 1400s. The collapse of the western half split the empire into innumerable feudal states with local leaders. This badly disrupted trade routes and severely decreased the availability of money, materials, and manpower to complete large infrastructure projects. Technology and architecture continued to advance, but there were few places in the west capable of financing major architectural projects.",
"Don't miss that there's a difference between \"lost\" and \"economically not feasible.\" Knowledge can be lost, in that it's not written down and passed to others. But more often, the case is ... sure, we all *remember* how to build aqueducts and bridges, or we can quickly figure it out by observing previous examples of aqueducts and bridges. But we just don't *want* to build new ones, because it doesn't make economic sense to do so in every situation. \"Nice fancy aqueduct you got there, Mr. Roman. You know what else works? Living closer to the river. And that's fine for us right now.\" Over time, this kind of short-term economic thinking can, via propaganda and revisionist history, get turned into \"OMG we forgot how to build a bridge LOL we're so dumb.\"",
"One of the lost technologies is [Roman concrete ]( URL_0 ). We think one of the secrets of it was a type of volcanic ash. It would be a lot harder to make it if you were a long way from the nearest volcano. Kind of like how you might have a really awesome recipe, but you couldn’t make it any more because a key ingredient became unavailable or really expensive. You’d be less likely to make an effort to keep that recipe around. Maybe you would modify it to use something else that is available. Even if the original was better, you’re probably going to make more effort to keep the modified version that you can actually make, rather than the original. Then you might not be able to replicate the original even if the ingredients became available again.",
"There was a time when things just didn't get written down in the way we do now. You could have knowledge that only 50 people in the world had, and was only written down in one or two places (and maybe only in 1/2 a place - like you needed two books and one was kept in rome and the other in another city. If those fifty people die, move away, retire, forget, and the books are lost then you are just out of luck. Now... you might be able to figure it out again if you knew all the basic stuff, and examined the work others did and talked to the workers who helped do things. But that would be a major enterprise and with each drop of knowledge you lose from there the harder the task gets. It is really only in the modern age that we think of knowledge as something that - once learned - is there forever."
],
"score": [
29,
12,
5,
3
],
"text_urls": [
[],
[],
[
"https://science.howstuffworks.com/why-ancient-roman-concrete-stronger-than-modern.htm"
],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jfh6wj | what is the difference between firmware and software | Technology | explainlikeimfive | {
"a_id": [
"g9k6f6b",
"g9k9p2f",
"g9kcqsb"
],
"text": [
"Firmware is actually a very specialized piece of software. Often small and not changed very often, and died to a specific piece of hardware that allows it to run properly.",
"It kind of helps to include hardware in there too, since \"firmware\" is kind of a play on/extension of hardware and software. \"Hardware\" in computing jargon is the bare metal (or silicon) that makes up the machine. Wires, circuit boards, RAM, CPU, all hardware components. Hardware is related to terms like \"hard requirement\" in that if you don't have hardware, you don't have a computer at all. \"Software\" refers to a set of instructions that run on that hardware to make it accomplish a certain task. This is anything from an operating system or web browser to video drivers, games... most anything code. Software, similarly, is like a \"soft requirement\" in that it's really good to have some of the basic stuff, but if you were really dedicated you could operate a computer without any pre-compiled code if you learned the CPU's assembly code and had an idea of how to build all the things you need to do from the ground up. However: by default, hardware doesn't always know how to work with other hardware, or where to look for what instructions to run. This is where \"firmware\" comes in: it is not \"soft\" in that you *really do* need firmware to run your computer, but it's also not \"hard\" in that someone *does* have to code firmware, but it's typically a very low-level instruction set that does very specific things to make sure that the computer has the required instructions to load any other programs you might want it to run. That is, it's a \"firm\" requirement: Not absolutely necessary, but *extremely* recommended if you want to avoid a lot of headache. Another big differentiator that not many people think about (because almost nobody has any reason to bother with it anymore) is that firmware is typically installed onto a piece of Read Only Memory; ROM is useful for firmware and this essential working stuff in that it takes very specific steps to edit it, and that means your average user won't try to just edit it accidentally; you have to *really* get what you're doing to edit it, and as I said before not many people even realize that ROM is still in computers (hell, I work with them for a living, and I forget we still have some ROM in modern CPUs). This also means that you should treat any updates to firmware much more seriously than updates to software; anything updating firmware is changing on a very deep level how your device does what it's doing, and if a firmware update fails halfway through, you often end up with a computer/phone/whatever that is a very expensive doorstop or a fairly expensive repair/replacement cost; this is different because even if you do something like erase your operating system, your device can still boot off of an external device like a USB stick (or you can connect it to another working computer) and the OS can be reinstalled. Firmware isn't like that; if you don't have startup instructions in your random access memory (RAM) that are meant to install new firmware to the ROM during the next boot from a \"soft reset\" (where the device unloads the operating system from RAM and then starts the boot process again, but without powering RAM down); if power stops flowing to the RAM in your system, the data in it is lost, so some other method of getting that data onto the ROM is needed. **TL;DR: Firmware lives in a special place that users generally can't access or edit and tells the hardware how it can even see the devices the software is stored on**",
"Firmware is kind of a joke term. You probably know what hardware is, and what software is. \"Firm\" is between hard and soft. Firmware *is* software, but it's software that runs the hardware at a very low level, and is rarely (often never) updated or changed. Regular software, like games or applications, use the firmware to access the hardware."
],
"score": [
9,
8,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jfmb88 | If cell phones are essentially just radios, why can't anyone just build a receiver to listen to calls? | Technology | explainlikeimfive | {
"a_id": [
"g9l4ddt",
"g9l4v5j",
"g9ldbqh"
],
"text": [
"While cell phones certainly are not \"essentially just radios\" (you might be thinking of walkie-talkies) and - depending on the transmission standard - there will be quite a lot of authentication going on for transmitted signals, siphoning off mobile traffic is [both possible and actively practiced]( URL_0 ).",
"Not unless you have some device to decode the digital data stream being sent to the cell tower. HAM radio is analog, which means that within that HAM radio frequency band, the audio was represented by modulations in the radio waves. Cellphones, in all but some really old cases, are digital now, so you'd tune in and hear, essentially, static. Through the late 80s to the early 2000s though, you could do this, and sometimes some crappy phones (or other radios) absolutely *would* pick up some other conversations from other cellphones that were crossing over into your used frequency when you were connected. I haven't heard anything like that since 3g became a thing though. Source: I'm old. EDIT: I forgot that encryption exists somehow (long day) but that's also a factor, but the standard last I checked was GSM and that's easy enough to crack if you know what you're doing.",
"You can make a radio that receives the signals but that's the easy part, you have to *understand* the contents of the signal All cellphone traffic is encrypted to some extent, it's like little enigma machines on each end. If you receive an encrypted text message you don't even know it is a text message until you decrypt it The standard attack method is to instead build something that pretends to be a cell phone tower so the phone tries to talk to it and willing gives it the encryption key it needs. These devices are often called Stingrays and are wayyy fancier than just receiving the signal"
],
"score": [
8,
7,
5
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/IMSI-catcher"
],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jfowe9 | How come my MacBook Pro 16" has internal SSD speeds of 2800 MB/s Read/Write while my external Samsung T5 SSD only goes up to about 500 MB/s? | How come the difference is so huge? And are there any faster alternatives? | Technology | explainlikeimfive | {
"a_id": [
"g9lk619"
],
"text": [
"The t5 uses a SATA (3) SSD internally, which sets a cap at the transfer speed between the ssd and the chip between your computer and the ssd at a maximum of 600 megabytes per second (minus protocol overhead, etc)."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jftroq | Is "planned obsolescence" a real thing with our devices? | Technology | explainlikeimfive | {
"a_id": [
"g9mf057",
"g9mpsj4",
"g9mdlgx",
"g9n1hgm",
"g9mh87b",
"g9myoao",
"g9nhtrf",
"g9n3t9m",
"g9mege2"
],
"text": [
"Sorta. Rechargeable batteries do go bad. They do not last forever, and if phone manufacturers put customers first, batteries would be replaceable. BUT phones nowadays are iP67 or better, which usually means that there’s a glued seal that your average user isn’t going to replace if they swap to a new battery. For your Xbox, chances are that either the thermal paste has bit the dust, or dust has collected in a heat sink. Things get old and stop working, and because consumer devices are much more complicated than they were 30 years ago, more things can (and do) go wrong. They are planned to last a minimum amount of time, so sometimes it feels like things are planned to go wrong, but it’s usually less ‘planned obsolescence’ and more ‘accounting for entropy.’ Usually, at least; there are probably some cases going through class action lawsuits for it.",
"There are two items here. What you think of as 'planned obsolescence' is really just 'building to cost'. Planned obsolescence is knowingly designing a product in a way that will require customers to later buy an updated version of your product. It's way more difficult than it sounds, as the fundamental idea of this is to retain your customers. Manufacturers are moving away from this as it does not work, you lose customers. Adding backward compatibility is a good example of this, it's something we expect now. Say you sell 25million xbox ones. Building to cost means that every dollar you save per unit is $25 million dollars profit. Your design target is to, as cheaply as possible, make the product that looks good quality to the consumer, can deal with the normal amount of abuse it will take and 99.99% (some secret number) of units produced will survive the normal life cycle of the product without failure. You could build an xbox one to the standard of an airplane black box, however the games will be just the same and the thing would cost $20,000+ They could also, easily build a cheaper version of the same equipment. They won't though, as the customer will not accept that buying cheaper means buying lower quality. Rather than being praised for building a cheap accessible version they'd be hammered for building a flimsy unreliable version. TL;DR - In almost all cases planned obsolescence is not real.",
"Apple does have planned obsolescence, they throttle performance to 'retain battery life'. They've gotten sued over it before, but there's no laws in the US to prevent these activities (but the Consumer Product Safety Commission can regulate durability standards). The XBox is probably just happenstance.",
"Planned obsolescence was a thing for incandescent lightbulbs. The Phoebus Cartel was founded in 1925 to control, among other things, the lifespan of incandescents. [from Today I Found Out]( URL_0 )",
"The main thing about electronics is that electronics develop far more quickly than things like say bolts. Like no one is going to come up with a 6.77mm nut and try and get everyone to adopt a new system of nuts. There's no benefit. But electronics get way faster very quickly. There is real benefit to changing things in ways that make them completely different than previous generations. Expecting say, Microsoft to still be supporting DOS is silly. And processors and things are usually built only once with enough stock to last X number of years. That stock can be stretched out by increasing the price as the number of processors in stock drops, but the problem is it doesn't make financial sense to invest in a new run of years out of date processor. However! The problem is when planned obsolescence cycles is that the companies doing so don't advertise the timeframe. If a company was very very clear that some device is only goimg to be supported for 3 years people would probably not be as mad, but saying that of course is going to be bad for marketing.",
"Yes, you even learn about this in Production Management classes and engineering classes. Planned obsolescence is in everything from furniture, to cars, and electronics.",
"Absolutely, I work in a industry which utilizes materials built to break. Check out [this known instance.]( URL_0 )",
"Lots of new products on the market after WW2 advances. Product makers move towards light and portable leaving heavy and durable behind. Lots of marketing revolved around \"buy many\" so products are built faster with a smaller lifespan with endless updates and a serious focus on \"keeping up with the johnses\"",
"All products are made to last a minimum amount of time. That includes each piece within a whole device. Batteries have a spec to last a certain amount of charges reliably. Memory chips and all other components in phones, video game consoles, and other systems also have a specification (spec) like this. These specs are targeted based on on expectations of the product. If new consoles come out every six years, then any given component within a console does not need to last more than that. Also there are many ways to reduce the cost of making a product. Often these cost savings come at the price of reliability beyond a spec. For example, a console that has a blu-ray disc drive needs that drive to open and close a minimum number of times (lets say 2 times per day for 6 years ... 2x365x6 = 4380 times in its lifetime). The maker of the console doesn’t want to pay extra for a drive that will last a lot more beyond that, there’s no need. And yes, the console maker wants you to buy the next gen console when it comes out. Other systems like refrigerators may have parts that are spec for only a few years. Most parts in a fridge these days are made of plastic that will wear out faster than a metal part. It’s cheaper to make the fridge with plastic and when it breaks, the person will need to buy a new fridge. Win-win for the fridge maker. They save money on making the fridge and get us to buy a new fridge when the parts fail."
],
"score": [
160,
41,
16,
13,
7,
5,
3,
3,
3
],
"text_urls": [
[],
[],
[],
[
"https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DulUI7JsFjZU&ved=2ahUKEwj8-IqQksjsAhVuhXIEHZQIBx8QtwIwA3oECAUQAQ&usg=AOvVaw3FvL4b0Dlf6BCsufzLKvyH"
],
[],
[],
[
"https://en.m.wikipedia.org/wiki/Phoebus_cartel"
],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jfuoj7 | Why was no one preparing for Y2K until the years right before it? | Basically the title. Why were so many computer programs designed to roll back to 1900 and why did the programmers writing programs not do anything about something they knew was going to happen? | Technology | explainlikeimfive | {
"a_id": [
"g9mj1we"
],
"text": [
"By the late 1990s most program written were already Y2K compliant, outside of minor bugs like leap year handling problems. The problem was with older systems that were written in the 60s and 70s. Of course programmers were aware of the problem, but companies needed to actually allocate resources in order to test and fix the problems, and it's hard to convince some executive in 1991 that in 9 years they're going to have a problem. Also, a lot of the time and money was allocated to simply testing and making sure the systems are compliant."
],
"score": [
19
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jfvhz2 | Why are .mp4 videos automatically streamable once uploaded to the cloud while other videos such as .flv need to be encoded first? | I was working on an assignment last night for my cloud computing course. The assignment was to stream a .flv video on different cloud services. After some research, turns out I have to encode them first. This what sparked up the question. | Technology | explainlikeimfive | {
"a_id": [
"g9mrzqg",
"g9mpepr"
],
"text": [
"Video files are actually multiple parts. There's the \"container\" and then inside that are tracks for video and audio... and sometimes subtitles and other things. The container has information that explains how the video and audio tracks are formatted, and what the player should do to play them back, and also contains things like an index to allow the player to quickly know where it can skip to. Old formats used to put this at the end (like the index of a book) because it was just easier to do AFTER you'd encoded the whole file. But newer standards can put it elsewhere, including the start. and thus the player can start playing the video without having to download the entire file first. This is important so you can start streaming quickly. The second issue is that browsers have built-in support for certain containers (and for certain video/audio encoding formats.) Encoding to the right combination means that the browser itself natively understands the file and knows how to start playing it. mp4 is a container that is meant for streaming (mostly) and while it can technically contain a bunch of different formats, it almost always is used to contain h264 video these days, which pretty much every player in the world supports, and is one of the main standards in Blu-ray as well. So when you pick mp4, it's not that alone that makes it work, but rather, your encoding program has a bunch of defaults to go with that choice that basically say \"Yeah, you probably want to stream this on the web...\" and sets up all the little details (like where to put the index, etc.)",
"It's more re encoding than encoding. And It's just because most streaming sites will use mp4s directly as most browsers will be able to read mp4s. Technically mp4 is just a container and depending on how it was generated might still need reencoded however by usage an mp4 video is likely to use H.264 encoding which is widely supported. Flv is a less universally supported format though. So the cloud hosting service is just converting it to mp4 first. Think of it like sending a .zip file vs a .rar file. Both are compressed folders, but you can just open a zip file in Windows, but need to download a program to open rar files. The cloud server is effectively decompressing the rar and then recompressing it as a zip so that people don't have to download extra stuff."
],
"score": [
10,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jg1lre | How is electricity used to create freezing cold temperatures (Ex. Freezer/Air Conditioner) | It makes sense how electricity can lead to hot temperatures, but how does it convert to cold temperatures? | Technology | explainlikeimfive | {
"a_id": [
"g9nlj7b"
],
"text": [
"Air conditioners take advantage of the ideal gas law - when you compress a gas it gets hotter, and when you expand a gas it gets colder. Your AC takes a specialized coolant gas outside and compresses it until it’s very hot. Then it allows this hot gas to cool off outside. That less-hot gas is then brought back inside and expanded again, where it cools off to well below where it was before. Effectively it has moved the heat outside. Your freezer does this too, but just dumps the heat out the back of the unit."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jgc5th | What is UFS (Universal Flash Storage) and how can it be a standard and also a card? | Technology | explainlikeimfive | {
"a_id": [
"g9pqk74"
],
"text": [
"It's a lot like microSD flash cards. The UFS is a standard for the mechanicals (size, shape, contact placement, etc.) and the electrical interface, including how the memory behaves. It's not really \"a\" card; it's the way you describe *any* card that meets the standard."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jgh4o6 | How Are Hertz And FPS different | So the new consoles are coming out and I wanted to know if I needed a 120 Hertz monitor to play with 120 fps or if my 30 Hertz tv will suffice. | Technology | explainlikeimfive | {
"a_id": [
"g9qetzb",
"g9qelas"
],
"text": [
"If your computer generates frames faster than the screen can display them, you can get a phenomenon called 'screen tearing'. That doesn't hurt anything. It just means your screen draws the top half of frame 5078, then the computer generates frame 5079 and the screen draws *that* over the bottom half. If things are moving fast, you'll see the seam where it switched from one frame to the next and it's a little distracting. You can prevent screen tearing by enabling a feature called Vsync, which makes your computer generate frames at exactly the rate that your screen draws them, but in that case some of your computer's capability is going to waste.",
"Hertz are the maximum amount of FPS a specific monitor can display. You can 'technically' have 120FPS on a 30 Hertz display, but you'll only be shown 30FPS and the rest is pretty much fluff."
],
"score": [
5,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jgiy5t | What is source code and how do they compile into apps? | Technology | explainlikeimfive | {
"a_id": [
"g9qnopd"
],
"text": [
"From my understanding, a compiler takes a source code, code the creator(s) writes, and translates into assembly language, a language in which a computer system can understand and execute."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jglhnt | Why isn't electric motorcycles that big of a thing? | I've read somewhere that the only significant difference between conventional motorcycles and electric ones are that one uses gas and the other uses batteries. What are the drawbacks as to why people don't entertain the idea of electric motorcycles much? I think it's got something to do with the mileage and business but I feel there's more that I'm missing. | Technology | explainlikeimfive | {
"a_id": [
"g9r00x2",
"g9r015r",
"g9r1rr4",
"g9qzs6h",
"g9s7vv2"
],
"text": [
"The biggest problem is with mileage. Electric cars have *massive* batteries in order to have reasonable mileage. A motorcycle, even with the much lighter body, would only have a range of about 50 miles at best with a battery the size of the existing fuel tank. Anything bigger would greatly change the aesthetics of the bike.",
"- Comparatively expensive to combustion bikes. - Range is relatively short at 200-250 city miles. - Increase in unknown complexity vs combustion. Once battery and component prices come down as more automotive makers make progress, we should see a noticeable drop in price, increase in range and electric motorbikes become more commonplace.",
"Give it some time - in 10 years, maybe 15, most new bikes sold will be electric. Right now, they're super pricey, have range limitations and riders haven't had much opportunity to see them or ride them to see how they feel to ride. A few people I know have test ridden the Harley LiveWire, and they are fans of the tech, and absolutely giddy about performance, especially acceleration at speed. A few more early adopters, some marginal improvements in battery tech, the ability to scale up manufacturing - all of these will happen over the next decade, and gas-powered bikes will become less and less prominent.",
"Sounds, aesthetics, charging station convenience. . A gas engine will be louder than an electric one. Although science proves that the sound of the bike doesn’t make you any more noticeable due to newer cars having better outside noise reducing equipment, audio systems being better, more distracted drivers, etc. It’s probably a comfort thing. Aesthetically, you’d need a pretty massive battery/batteries. I prefer to take mine on backroads, twistys, etc. I don’t want to have to think of when/where I have to veer off course to get to a charging station.",
"It's already being done just not in the main stream. Take a look at Zero Motorcycle, they have a 200 mile range and quick charging. The infrastructure from Tesla is already there. There is a buy named Ben Rich that has rode the 4 corners (Over 5,000 mile) and other adventures all on an electric bike. [ URL_0 ]( URL_0 )"
],
"score": [
21,
9,
6,
4,
3
],
"text_urls": [
[],
[],
[],
[],
[
"https://electrek.co/2020/09/17/electric-motorcycle-rider-covers-7000-km-to-arctic-europe/"
]
]
} | [
"url"
]
| [
"url"
]
|
jgminz | Why when you use a phone camera to take a picture of a computer screen, does the picture turn out slightly distorted with weird lines in it? | Technology | explainlikeimfive | {
"a_id": [
"g9rb3qn"
],
"text": [
"It's called a moire pattern. The computer screen is a grid of pixels, and the camera is another grid of light sensors. Those weird lines come up when you put two grids on top of each other, and they don't line up quite that well. You can see the same effect when you put something like a piece of mosquito screen on top of another piece. Nothing to do with refresh rates and shutter speeds and whatever."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jgof6m | What causes the distortion in this photo to change so drastically when zooming in and out. Also why does this happen when taking a photo of a display? | URL_0 | Technology | explainlikeimfive | {
"a_id": [
"g9rlalu"
],
"text": [
"Ah, No Man’s Sky - my favorite space billionaire simulator. Your display is an array of tiny rectangular diodes that emit light. Your camera is an array of tiny rectangular sensors that detect light. Your phone screen that you’re zooming in and out on is - you guessed it - an array of tiny rectangular diodes that emit light. So you’re using an array of rectangles to display the readout from a different array of rectangles, that’s pointed at a third array of rectangles. The different sets of rectangles are never quite perfectly aligned, and so you get this “screen door” distortion effect that undulates when you move the different rectangular arrays around."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jgog0n | Why is the International Space Station approaching its expiration date? | I have heard there are plans of letting the ISS crash down and burn up into the atmosphere. Why can't they just do maintenance and keep it running? It sounds incredibly wasteful to me to let those years of hard work just wither away. | Technology | explainlikeimfive | {
"a_id": [
"g9rhrlu",
"g9rhw7v",
"g9rirku",
"g9rvew2",
"g9rth8a"
],
"text": [
"There are plans, but it's certainly not set in stone yet. > Why can't they just do maintenance and keep it running? At some point operational costs exceeds it's value. Think of it like keeping a used car running. If I $5000 used car needs a $1000 repair every few months, it's often not worth it. And remember the money is only one resource. It's the downtime while it's \"in the shop.\" > It sounds incredibly wasteful to me to let those years of hard work just wither away. Don't get hung up on the [sunk cost]( URL_0 ) If it's not worth it to continue, it's not worth it, initial cost isn't a primary deciding factor.",
"They certainly can do maintenance to keep it up and running - we've pushed out the date multiple times now by doing just that. The question is - who is going to pay for it? The ISS isn't cheap to maintain or run, and the US shoulders the bulk of the financial responsibility for its operations. If I had to hazard a guess, there will be a last minute reprieve for the ISS, just like all the times before.",
"Everything has a design lifespan and keeping it running for longer and longer gets costly That said, the ISS's operational life has already been extended several times and is now expected to continue through at least 2030 but will likely receive another extension before then, but 10 years is about as far ahead as NASA and Roscosmos can secure commitments As for letting it crash down and burn up in the atmosphere. At some point we will stop supporting the ISS and unless it gets put in a space museum it'll have to be disposed of. The best way to do that is to lower its orbit and let it burn up over the Pacific so the debris falls into the ocean. All space stuff is expensive, but its not feasible to commit to supporting something *forever*",
"Let's pretend that the ISS is a car. Every single component in a car is designed to last through a certain number of operational cycles. Or to last a certain number of years. Or a certain mileage. It's not necessarily decently advertised, but that is pretty much how it works. The car is built with the intention that it should last for a certain while without any major repairs. And it should last a certain number of years without the need to take the engine apart. But, eventually you have to do that. Even if you are notoriously good at changing the oil and the filter when you should, you will still eventually end up with the problem that there are parts of the engine that are not made to last forever. If it's just an exhaust pipe, it's probably pretty easy to replace it. If it's a cam chain, it'll eventually create a malfunction if you don't replace it. But...think about the space station again. What do you do when you need to take apart something in the space station because there is a movable part that needs to be replaced, when you also at the same time need the something to be operational, because it's needed to make the space station habitable? You can't start meddling with the system that provides oxygen (no mater how that is done, and that is besides the point) unless you have a spare system that you can fire up and rely on while you repair the original one. At some point, you will end up with solar panels that are not producing well, batteries that are not charging well, a charger that is not always working as it should and that is just about producing energy for the rest of the systems. What do you think happens when the electrical production is a bit flakey, when you rely on electricity to keep the station heated and let out enough oxygen? At some point, eventually, there is so much stuff that is getting worn out that you either have to send up an entirely new station and put it into the old one, or just build a new one and forsake the old one and scrape it.",
"Things last only so long, even well maintained things. And for most things, the costs of maintenance grow over time and it takes more and more effort and expense to yield less and less results. And in the incredibly harsh environment in space, and it's incredible the ISS has lasted this long. But the real issue is sunk cost thinking. What's been spent already has been spent already, and it should have no bearing on whether or what to spend in the future. If from today forward it's worth spending $XXX to keep the ISS running, so be it. But that's an assessment to be made based on what that spending will accomplish in the future, not what prior spending may have accomplished in the past. At a certain point, it's more cost effective to build and launch an entirely new station (or alternative like a set of satellites or an orbital or lunar or Martian base) than to continue to maintain decades old tech that's taken a huge beating and lived well beyond it's anticipated life already. Besides, there's only so much available funding for space endeavors, and every dollar spent on the ISS is a dollar that won't be spent on another project."
],
"score": [
29,
7,
7,
5,
4
],
"text_urls": [
[
"https://www.behavioraleconomics.com/resources/mini-encyclopedia-of-be/sunk-cost-fallacy/"
],
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jgqc1y | Why does only charging a lithium battery to 75 percent help prevent premature aging of the battery? Can’t they just make an app or program that makes it look like 75 is max capacity to prevent the battery from dying faster? | Technology | explainlikeimfive | {
"a_id": [
"g9rwzoc",
"g9rtows"
],
"text": [
"All modern battery designs for electric cars and phones and such already do this. When it says \"100 percent\" it doesn't mean \"literally the maximum possible -- no more electrons, now fuck off.\" It means \"This battery is fully charged to what we think is the appropriate capacity for the most number of examples we designed and tested.\"",
"Chevy volts do just that. The physical parts of a battery swell and contract as they gain and lose power. Maintaining a lion battery between 15-85% maximizes its life by limiting this size change."
],
"score": [
13,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jgqfgt | WiFi: difference between 2.4 ghz and 5ghz | Which is better? Which should I use and why? Thank you!!! | Technology | explainlikeimfive | {
"a_id": [
"g9rtxo5",
"g9sicvi",
"g9rtu3s",
"g9rttkt"
],
"text": [
"2.4g can reach a farther distance, but at lower upload/download speeds. 5g can reach shorter distances at higher speeds. I’d say if you’re streaming, working or gaming, stay close to your router on your 5g connection, or just plug an ethernet cable in. If you have smart devices or security cameras, connect them to your 2.4g connection because normally they are not close to the router. 2.4g is the turtle, it’s slow but can reach pretty far 5g is the rabbit, it’s fast but doesn’t make it far",
"Another thing I don't see mentioned in regards to wave length and throughput/bandwidth is interference. A lot of household applicances operate on 2.4Ghz frequency, thus higher chance of interference in comparison to 5Ghz.",
"Lower frequency allows the signal to penetrate walls more effectively, but transmits less data in the same amount of time. So 2.4GHz gives you strength and range at the expense of speed. 5GHz is the opposite. Being higher frequency, it transmits more data in the same amount of time than 2.4. However, the high frequency signal is more easily attenuated by walls and distance. So you get strength at the cost of range and speed. Generally 5GHz is going to perform well in a smaller environment, like an apartment while 2.4GHz is more suited to cover a whole house.",
"5GHz has faster throughput, but at a shorter physical range than 2.4. The max throughput of 2.4 is 450mbps and max throughput of 5 is 1300mbps. Basically, if the internet into your home is slower than 450mbps, there is little benefit to using the 5GHz band. Edit: I didn't think to include the local network into account. If you are connecting/transferring data between two devices on the same network over the air, 5GHz is the way to go."
],
"score": [
43,
8,
8,
4
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jgux20 | Why are recycling places such sticklers about items being washed out? | If a bottle or can has a label glued to it or paint on it, how is that so different from a bit of food? | Technology | explainlikeimfive | {
"a_id": [
"g9slo4g",
"g9stp8z"
],
"text": [
"Rats and other vermin are hard to deal with. Dump a bunch of oily, dirty old food tins and soda bottles with sugary residue into a big pile, you're getting mice, rats, and vermin of all sorts. They'll travel with the cans and bottles down the sorting lines, into the shredders, etc., messing up the equipment and the workers. Labels and paint can be removed by passing the shredded materials through a chemical bath or sprayer. Food particles have to be washed out (along with the vermin).",
"There's another issue - when plastics are recycled the oil residue on the surface ends up mixing into the recycled plastic. If there is too much oil the plastic properties are changed too much and it doesn't behave properly. It can be a significant problem."
],
"score": [
60,
17
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jh05ji | Why do recordings get a higher pitch if you speed them up, and is there a way to make a recording actually just sped up without increasing the pitch? | Technology | explainlikeimfive | {
"a_id": [
"g9u0ibh"
],
"text": [
"Pitch is caused by the frequency (oscillations per second) of the sound waves, where a higher frequency = higher pitch. Playing something at higher speed means the recorded waves are oscillating faster. Computers can correct for this, but record players can't."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jh43lj | What actually happens when a file is being compressed? | Technology | explainlikeimfive | {
"a_id": [
"g9v5erb",
"g9v6ag4",
"g9v5ai1"
],
"text": [
"The program doing the compression tries to find patterns in the file and records the pattern rather than the information in the pattern. The most common illustration people use is pictures: say you have a picture of flowers: there's a whole lot of green, so the algorithm will find a pattern that says: \"this whole region is green\" so instead of recording \"green\" for each pixel in the region, it will just record the boundaries of the region and the information \"green\". The type of patterns that are found depend on the algorithm, who made it, and what it's optimized for. Files that don't have patterns cannot be compressed!",
"Patterns or rather repeated patterns are identified and can be made redundant as long as the compression algorithm is known so that the document can be decompressed later. So let’s say you have a text file with XXXYUHJJJJKKGBVVVVVVV. Well you could instead store it in a format that saves the file as x3YUHJ4KKGBV7. You’ve therefore reduced and compressed the size of the text file.",
"Basically, files are ultimately made up of 1s and 0s. When enough of those 1s and 0s fit into a larger pattern, you can replace those 1s and 0s with a smaller \"compressed\" pattern that represents the original."
],
"score": [
11,
8,
5
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jh4ir7 | How are the CPU and GPU different? Why can't a CPU do the work of the GPU or vice versa? | Technology | explainlikeimfive | {
"a_id": [
"g9vb06z",
"g9ve0i2"
],
"text": [
"The ELI5 answer is that it is like the difference between a dump truck and a school bus. Both carry stuff and you could fill a dump truck full of school kids and put gravel in a school bus, but they aren't really designed to do that. A GPU is designed to be very good at the kind of work required to display an image, mainly a lot of fancy math stuff. A CPU is designed to be a lot more generalized and is better at doing all the non-math stuff, but not as good at the math stuff.",
"You can have a CPU do what a GPU does it is just much worse at it. Think of it like a CPU is a Swiss Army Knife. It can do all sorts of things, it is not very specialised. Now for a picture think of it like you cwould have to put a lot of screws in for that. Sure you can do that with a Swiss Army Knife, but that takes a lot of time. A GPU on the other hand is like a ton of those little screw drivers that can screw in a lot of screws at the same time. In general GPUs just do a lot more limited tasks a lot more paralell."
],
"score": [
15,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jh4x7y | What is the difference between DDR and GDDR | Technology | explainlikeimfive | {
"a_id": [
"g9vh9xr"
],
"text": [
"DDR memory uses a 64 bit wide bus and gddr uses 256 bit and 512 bit bus ddr had lower latency and lower bandwidth, and gddr has higher latency and higher bandwidth so ddr was made for complex tasks that would be one after the other and gddr was made for less complex tasks that need to be ran multiple times at once"
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jh7cd5 | Why do some technical problems simply disappear as soon as you switch a device off and on again? | Technology | explainlikeimfive | {
"a_id": [
"g9w93w3"
],
"text": [
"That typically resets things, and the error that causes the problem in the first place can be erased that way."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jh9ndm | why are decibels expressed as negative numbers when using a stereo system? | Pretty much the title. | Technology | explainlikeimfive | {
"a_id": [
"g9wzphq",
"g9x1s0l"
],
"text": [
"They don't have to be. The decibel scale is totally arbitrary. 0 dB is just a reference value, and less than zero just means whatever you're measuring is weaker than the reference value. Similarly, more than zero means stronger than the reference value. In stereos, 0 dB is defined to be the maximum audio signal strength the hardware is capable of. Therefore, less than 0 dB means you're making the signal weaker which results in a lower volume. -10 dB is 1/10 of the reference value, -20 dB is 1/100 of the reference value and so on.",
"Decibel is a unit of relation. So you can not use it on its own, it is always in relation to something else. The problem is that a lot of times this is implicit so you have to know what the reference number is. In the case of sound the reference number is the lowest sound pressure humans can hear. So any sounds under 0dB is not heard by humans. In amplifiers and attinuators you might see the reference as being the input. When talking about sound levels though you are usually using a standard reference voltage to measure against. The exact voltage used depends on the equipment, more expensive systems use higher voltages. But you are not supposed to go over that voltage much as it is the maximum voltage that the amplifiers and speakers are designed to handle. If you go over they may distort the sound or even destroy themselves. So you want to keep the sound levels lower then 0dB."
],
"score": [
19,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jhbcjc | why do camera's make noise when they take a picture? Do they need to? | Technology | explainlikeimfive | {
"a_id": [
"g9x9a59"
],
"text": [
"Old-school film cameras had a mechanical shutter that had to move, which created the \"click\" or \"snap\" that we've come to associate with taking a picture. Digital cameras absolutely do not need to make any noise at all, but there are two reasons they do so: 1. We expect cameras to make that noise, and 2. as a matter of privacy, to indicate to your surroundings that you're taking a picture."
],
"score": [
11
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhbjwm | How does navigation in cars gets updated without Wi-Fi? | Technology | explainlikeimfive | {
"a_id": [
"g9xak74"
],
"text": [
"Some of them require manual updates via disc or USB drive. Others are able to update over satellite...though not the ones it uses for GPS but rather satellites for other services such as satellite radio (this is how some cars get live traffic updates on their built-in GPS)."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhc45a | What is HDR and how much of a difference does it makes with SDR on smartphones or TVs for that matter? | Technology | explainlikeimfive | {
"a_id": [
"g9xe0an"
],
"text": [
"HDR is basically a video and image format change that adds a lot of colors, its supposed to give a more vibrant and real-life like colors in an image or video. Many people regard the addition of HDR into video as much more impactful than the eventual transition to 4K, which has been oversold because to general consumers its easier to understand 4K, while HDR just adding \"more colors\" doesn't sound as interesting. Does it make a difference? Under certain viewing conditions and video/picture formats, yes HDR produces a better overall picture than non-HDR. However, these are specific conditions, if those conditions are not met, the difference is nothing"
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhdfgj | What exactly is 'Youtube-dl' , why was it taken down by RIAA and what does the DMCA takedown of youtube-dl affect? | I saw this on trending, I read [THIS]( URL_0 ) post but I am still a bit confused even after reading some of the comments. What exactly is YouTube-dl and why did it get taken down? What exactly does the takedown affect? And how? | Technology | explainlikeimfive | {
"a_id": [
"g9xnn66"
],
"text": [
"Youtube-DL is a little program that downloads videos and/or audio from basically anywhere that hosts them. This means you could go on YouTube and download videos with it. This is a form of digital piracy and technically also falls under hacking; you're using a website in an unauthorized manner and making digital copies of something you do not own. For example, you could pay the $2.99 rental fee on any of the movies hosted on YouTube, and then you could download that video and own a copy. You aren't authorized to make a copy, and you're bypassing legitimate channels to purchase and own that movie. You could also go to somewhere like Netflix and download anything you like off of that. Again, bypassing the legal channels that you would otherwise be required to use. It's all very much like going into a movie theater with a video camera and recording the movie you're watching, except this is in HD. The takedown just means that Youtube-DL had to be taken off of Github (the place it was hosted and downloaded from). That's it. You can't harass people who use the program (because it's basically impossible to track), but you can make it harder to download the program."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jhdg9f | how compasses work | Technology | explainlikeimfive | {
"a_id": [
"g9xmvru",
"g9xnevx",
"g9xn47i"
],
"text": [
"The needle in a compass is just a magnet shaped like an arrow. One side points north because the earth itself has a huge magnetic field and Northern pole of the magnetic field attracts that side of the needle.",
"The flow of liquid metal inside the earth's core creates an induced magnetic field wich gives the earth a North and South magnetic poles. The needle in the compass is also a magnet, so it gets attracted to the poles of the earth, the marked end of the needle gets attracted to the magnetic north pole, wich is really close to the true north direction, and that gives you a good direction of the cardinal points.",
"The north end of one magnet is attracted to the south end of another magnet. The Earth is a big magnet, with the south magnetic pole at the north pole, and the north magnetic pole at the south pole. As such, all magnets experience a slight tug to point their north end north and their south end South. Compasses put a tiny magnet on a needle bearing and let it rotate freely, at which point it aligns with Earth's magnetic field, showing which way is north and south."
],
"score": [
13,
6,
6
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhf3bq | How are sports game statistics kept track and displayed in real time? | Technology | explainlikeimfive | {
"a_id": [
"g9xxzc3"
],
"text": [
"they're done manually. for each and every game. there's a person that is tracking what player does what in the game. how many steals, rebounds, 2-pters, 3-pters, free throws, fouls, etc. and all of that is put in a database and displayed in a nice format in monitors to all the people who need to know. like the press, coaches, reporters, commentaries, etc."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhg300 | how speed radar guns work | Technology | explainlikeimfive | {
"a_id": [
"g9y6xjk",
"g9y51i9"
],
"text": [
"Have you ever listened as a train goes by with it's horn blaring? Have you noticed how the pitch changes? This is called the doppler effect. It is caused by the frequency changing due to the speed of the object relative to the wave. If it's approaching, it is goes up, sounding higher. If it is going away, it goes down, sounding lower. The faster it is going, the more up or down it goes. It turns out this follows a mathematical equation. Radar guns send a pulse of electromagnetic waves that bounce off of the object and return back to it. It measures how much the pitch of this has changed, does some math, and tells you how fast that thing is going.",
"Signal goes from the gun to the car and back the time taken for that to happen gives you the distance, with subsequent signals you have the change in distance over time or the speed of the car."
],
"score": [
7,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhgdov | How did they record the sound from films onto film before digital techniques and how did they then get the sound back off the film? | Technology | explainlikeimfive | {
"a_id": [
"g9y7gyk"
],
"text": [
"Was recorded seperate. You know that clacker that you see in a behind the scene shot? It's got black and white lines on it an some writing. Scene number, take etc. Put right infront of the camera before the director yells action. The crack sound it makes is synchronized with the film of the two parts coming together on the audio track and video track. It's also one of the two \"rolling\" calls before a shot. The sound recording tape is rolling, or on, and the film is rolling."
],
"score": [
11
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhm8ti | What’s inspect element and what does it do/ do you do with it? | Technology | explainlikeimfive | {
"a_id": [
"g9zy3sx",
"ga0pjhk",
"g9zzp47",
"ga0ayaf"
],
"text": [
"Inspect element is like x-ray for websites. It’s a tool we use to understand how a website works. Because we can see pretty much everything, we can find bugs quicker or we can even use it to make temporary changes to preview new features. (It comes with more tools like console, source maps, responsive view, computed values, fonts through the page, etc)",
"A website is a bunch of code that tells your browser what to display on the screen. Inspect element allows you to see that code. It also has a bunch of useful features to make navigating that code much easier.",
"For html pages? When you inspect an 'element' (like anything on the page, a text box, image or some button) it shows you what is written in html and css to tell the browser how to display the webpage. Ie, this image is contained in a div with a class (css) attached to it. The html might be a link wrapped in an < a > tag with a plain text caption underneath. The class refers to the css styling that will tell the browser how exaclty it should be displayed. Ie, image is centred, text underneath is 12pt, bold, calibri font. The style editor tab displays this. Its used to inspect how something works, for debugging or say im learning so i would like some real examples of how an image gallery is implemented so i can use that on my own page. Mousing over a block of text will show you what on the page it is referencing. In firefox, its really useful for developers as you can change the viewport width to mimick an iphone or android device, thereby displaying the page as it would look on a smartphone. So it saves me time when im designing becaus i wont need to view the page on a other device (although its not a 100% replication of how a smartphone would view it). You can edit in the inspector the style and raw text of a webpage. For example, if you went to URL_0 . and you found the 'placeholder text' for the search bar, you could change it to show a rude word, close the inspector and then show your friends like 'woah bro google is swearing at me'. Its been used by students to play with websites that their teachers tell them to go to, and is pretty funny when they dont know what is happening. More maliciously - there is a remote access scam that utilises the page inspector. Many remote access scams begin with the caller informing the victim that their network has been hacked. They then convince the victim that they are microsoft support or some similar company and request remote access to 'remove' the virus (many alternate versions of this scam also claim that they can fix the victims slow connection speed). After they have remote access, they instruct the client to check if their bank accounts have been accessed - the scammer will then tell the victim that their bank accounts have been compromised by 'hackers', and that in order to catch them, microsoft will deposit a large amount of money into their bank accounts. The scammer uses the page inspector to edit the page to display the victims total balance as much higher than expected. They will then ask the victim to deposit the money into another bank account so they can 'track the hackers' who will inevitably intercept the funds (most of these scams make use of victims lack of computer literacy, its sounds rediculous to me, but to a 55 year old pensioner it sounds legit). TLDR: for development and debugging, also for sneaky students and scammers.",
"A website is basically just a text file where all of the text is tagged with information about how it should be displayed. A browser is a program that takes that raw text file, reads the tags and then displays the page in the pretty way that you are familiar with seeing webpages. Inspect Element let’s you click on a part of a web page in the browser and see what the tags and styling information in the raw text file looks like. It also lets you edit those things within your browser, allowing you to make temporary changes to how the page looks locally on your computer. This can be useful for understanding how part of a website works or for quickly finding and testing ways to fix an issue with the way the site is showing up if you’re the one building it."
],
"score": [
18,
9,
5,
4
],
"text_urls": [
[],
[],
[
"google.com"
],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhmenu | why movies look good at 24 FPS, but games don't | When a decently fast-paced, action-packed game can't consistently be rendered at 60 FPS, gamers usually consider that sub-optimal. When it regularly dips below 40 FPS, it actually becomes unenjoyable. Even a low-movement, cinematic simulation game has to hit at the very least 30 FPS. Some gamers even find 60 FPS stuttery after experiencing 144 FPS. Why then do movies just never feel choppy? | Technology | explainlikeimfive | {
"a_id": [
"ga01c9w",
"ga00n4o"
],
"text": [
"1. Movies are passive. They don't respond to your input. 2. The movie frame rate is consistent. Every frame is 42ms long. Where a game might average 24fps, but the frame time might jump from 20ms to 100ms depending on what is displayed. 3. True motion blur. shutter speed does play a huge role in this, but in general a movie frame captures more than an instant of motion. With motion blur off in a game, you only see a single instant. Even with motion blur on, the game is guessing and isn't nearly as good as a long shutter speed on a video camera.",
"It is all in the motion blur. A movie camera captures a period of time during which its shutter is open, while a computer game renders a theoretical instant of time. Because of this a single frame of a movie can contain a lot of information about the movement of objects, connecting where they start from the previous frame and end up on the following. A computer game only models a single instant and this means there is no information about movement at all."
],
"score": [
14,
9
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jhownz | How complicated is the DMCA? | Technology | explainlikeimfive | {
"a_id": [
"ga0r35s"
],
"text": [
"It's not really 'complicated' so much as it is way too overbearing and powerful. It's a law from like 1996 so it never really anticipated things like Youtube and streaming. With technology as it is now, you've got so much user generated content, and you've also got systems that just scan it and file automatic takedown notices and claims. So you've got a blunt force law coupled with the ability to enforce it thousands or millions of times a day without human intervention. You've also then got no way to systematically check for things like fair use or even permission being granted or context. You get things like Star Wars music being DMCA'd because someone is playing a Star Wars game and the music is in the game itself."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jhpy02 | Whats this "Earn It" bill Im hearing of recently? What do I need to worry about as it seems like people are going crazy over it? | Technology | explainlikeimfive | {
"a_id": [
"ga13s5m",
"ga150iq",
"ga170q0"
],
"text": [
"The EARN IT bill is an effort to mandate backdoor keys to all encryptions in the commercial sector. Encryption is a means of encoding data so only people with the right code or “key” can read it. It is vital for banking, commerce, and private communications. If this bill passes, all commercial companies would be required to have backdoors to access all data encrypted on their servers. That means that they can see all your banking info, messages, history etc etc etc. Having a backdoor means a built in massive vulnerability to hacking, or over zealous or authoritarian government. The proponents of the bill argue it would make it harder for pedophiles to share images, or other criminals to commit computer crime, but opponents say (correctly imho) that it is far more dangerous than useful to do",
"I think most of the controversy right now, is that the bill is obviously very Pro-Law Enforcement, and not very considerate to individual privacy. In addition, since it's written by law makers who are generally not very tech literate, there language of the bill is still quite vague. It outlines the penalties for companies to fail to follow \"best practices\" with regard to user data, but those best practices are undefined, and will be determined by a new committee, but must be approved by the Dept of Justice and the Attorney General. So if the bill passed, the DoJ basically gets free reign to define \"best practice\" and punish companies who fail to comply. Attn. Gen. Barr for example has said he would be happy to outlaw secure encryption entirely ( URL_0 ). I think the other big problem that people have with it is that is framed as a child protection law, but there is little evidence to suggest that it can be effective... Any new measures recommended by the new committee would need to be adopted and implemented before law enforcement could actually gain access to the incriminating data. Child trafficking rings and child porn sites, will not comply... This is just one more law they will continue to break, and there is no indication this legislation will change this in any meaningful way. Perhaps in a few years when all non-government internet traffic is the US is interceptable, it may become possible to detect devices sending and receiving \"suspicious content\" and the baddies will need to try a little harder to mask their behaviour...",
"The EARN IT Act basically is supposed to protect people by giving the government a key to your personal information and everyone else's as well. Encryption is like a door to your information. When you send a message or go to a website or log in to your payment program, this door stops other people from walking in and taking that personal information. The encryption turns your information into a coded message that only you and the people you are communicating with can see. Think of it like having a key to the door or a decoder ring for the coded message. The government wants companies to make a special key or ring for them that allows them to better police the information being sent and received. The problem is if someone figures out how to use that government key for the wrong purpose then it could put a bunch of people at risk and it obviously is a breach of the constitutional right to privacy we have from our government. The NSA was already caught recording all of the information sent in the United States (and other places). If they had the key to any information they wanted then they would be able to go back and see all your information. The other problem is that it is unenforceable imho. Companies will sue the government for their client's right to privacy and it will be deemed unconstitutional. It is a ridiculous bill that shows how little our current congress understands technology or how well they are being paid to pass this sort of thing."
],
"score": [
20,
7,
6
],
"text_urls": [
[],
[
"https://arstechnica.com/tech-policy/2019/10/the-broken-record-why-barrs-call-against-end-to-end-encryption-is-nuts/"
],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jht6he | What are databases and how do they work? | I tried reading about it but everything just got more complicated when I stumbled upon the words "hierarchical" and "SQL and NoSQL"... | Technology | explainlikeimfive | {
"a_id": [
"ga1zfw2",
"ga287dl",
"ga2aqik",
"ga29rdy",
"ga2afua",
"ga2exhp",
"ga20p10",
"ga21jwz"
],
"text": [
"a database is a system for cataloguing and storing information. Note that this includes several things: * The hardware necessary to store the data * The rules by which we organize the data that are stored * The software that implements those rules and uses them to let users add/delete/lookup/alter/etc. data in the system Technically the second could be referred to as the database's model and third its database management system (dbms). However, in practice, people often refer to these things, both collectively and on their own, as \"the database.\" There are lots of different sets of rules (models) by which we can organize data that are optimized for different purposes. However, a very common one is the relational model. In this model you have relations, or tables of storing particular features of a class of objects. For instance, in a database of university students I may have a table of students with their ID number, major, etc. I may have a separate table of courses, with their course ID, professor, etc. I may then have a third table linking student IDs to course IDs to denote student membership in classes. This method of storing data is very popular because it allows for very easy tracking, updating, inserting, deleting, and linking information with minimum duplication of data. It also is very popular because there exists a standard language for interacting with relational databases, structured query language (SQL). This is a very specific programming language just for interacting with relational databases. The relational model is not the only game in town, though. The \"hierarchical\" term you found refers to a hierarchical model, where data is stored in a [tree]( URL_0 ) through which you can navigate. As I said earlier, these are best used for different purposes, but the relational model is, by far, the most common in everyday use.",
"There are other good answers, but I'm going to attempt an actual ELI5 (ie. focused on simplicity rather than specifics). Think about a teacher entering grades into a computer program. When the grades are entered, they have to be stored somewhere, right? And you have to be able to go back to that place at the end of the year to make a report card for all the students by adding up their grades. You might even need to find out a particular student's score on an assignment on the fly if their mom comes to school. The place you put the data has to make it easy to find again. Otherwise, it's not much use. That place is usually a database, which is just a program that stores data in some format and provides a way to get it back out. Some databases are very simple and store data in a file on the computer. Other databases are really big and complex and store data far away on a server or even multiple servers. Servers are just big, fancy computers that some times have special parts. SQL va NoSql is mainly about how the database keeps the data stored and how you get it back out. SQL databases are something called \"relational\" which mean they keep the data in tables. Think of a chart with numbers in one column and the word spelled out in another, but these tables could be hundreds of columns wide and with many, many rows. The way that you get data out of one of these databases is with a tool called SQL that some programmers and computer programs know how to use. The other kind of database is NoSql. There are lots of different kinds of noSql. The thing they have in common is that they do not use Sql to get the data back out. There are some things that are hard to do with SQL, so you do those with NoSQL. It's like it's hard to screw in screw with a hammer. Programmers like to argue about SQL and NoSql and which is better, but it's a lot like people arguing about Coke and Pepsi. They're both good for different reasons and in a lot of cases either will do.",
"ELI5 Attempt here. Too many technical reply below. Database is simple. It stores data. Data is a file , database is a filing cabinet. There is a predefined system of filing eg alphabetical order , followed by serial no , etc. So a database is a data filling (storage) system that allows eady insertion and retrieval of data.",
"It's a collection of data stored in a computer system in a way that's \"easy\" to reference, manipulate and sort. SQL is \"structured query language\" so instead of hard coding to get data to do stuff it's in fairly plain English. E.g: select username, user_id from customers where user_id > 40; The only tricky bit there is the > which is \"bigger than\".",
"ELI5 - a bunch of excel spreadsheets and a computer language that understands your commands and can go get the data you’re asking for. From there you build more and more complicated things from that basic framework.",
"I’ll go full ELI5. It’s data, along with structure. That’s it. Imagine going to the beach, and wondering “Can I pick up a specific type of rock?” The entire beach, is the raw data-set. It’s very difficult to find a specific rock. That could be data, pasted into a text file. Now imagine a bunch of trucks come along, scoop up all the rocks, and put it in a big vending machine. Now if I wanted a specific rock, I could press the button, “D5”, and a specific rock would pop out. If your vending machine not complex, the D5 rock might not be specific enough. If you want a more specific answer, you need a more complicated vending machine. And instead, you might press “D5qz@225” and out pops an even more specific type of rock.",
"Databases are specialized software that store data for easy retrieval. You can store data in other ways — in an Excel file, for instance, or as a text file — but that isn’t a great way to store the type of structured data that goes in a database. When you build an application, there’s usually some sort of database that saves data for/about the user. In the modern world, the primary database is usually on a server (or across multiple servers) so a desktop program, mobile app, and web site can all access the same data. When you want to get data into or out of a database, you write queries. You may have seen CRUD used. That stands for the four main types of queries (create, read, update and delete). Those queries have to be in a language the database knows and by far the most common language is SQL. (There are several variants of SQL, including Oracle, MySQL/MariaDB, PostgresSQL, and Microsoft SQL but they’re all very similar for the most common commands.) SQL databases usually store data in flat tables (similar to a spreadsheet tab) that are independent but almost always able to be connected. NoSQL databases (like MongoDB and many others) became very popular recently but they’re typically specialized. They’re just database languages that purposely do not use SQL language because they’re hoping to solve a problem SQL isn’t great at. For instance, MongoDB stores data in a similar way to web browsers and each record doesn’t have to have the same fields/structure.",
"A Database is some method to store and work with some data in an organized manner so that it's easy to work with. A hierarchical database is a database that is organized like a tree: You can have an industry that has some company that has some employees that have some children that have some toys: there is a hierarchy where each \"thing\" in the database is related to a more general thing: Each employee works at a single company, but one company can have multiple employees. Each child only has one parent (in our model at least), but each parent can have many children, e.t.c. This makes the data more organized and more easily understood by humans. There are several different systems that implement databases, but one of the more popular one is SQL, or \"Structured Query Language\". This is a kind of a programming language that operates on specific types of databases. It is fairly english like and can lend itself to easily get the data you need: such as SELECT name, birthdate from Employees where company = 'Apple'; which will return all the employees of Apple. or Insert into Toys(type,color,child) VALUES('boat','red','Clare'); Will insert a new toy into the database that is a red boat belonging to Clare. The thing about SQL is that it expects the database to be structured in tables, almost like a collection of Excel spreadsheets. However your data may not fit in to that presumed idea, so NoSQL is then the opposite, a database system that doesn't use SQL that doesn't follow the \"table\" idea of databases. NoSQL databases typically have their own strengths, and are common in fields like big Data or where you need stronger scaling to hundreds of computers working together."
],
"score": [
80,
37,
8,
7,
6,
3,
3,
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Tree_(graph_theory\\)"
],
[],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jhykw0 | How does a iterative model work in system development life cycles. | I've watched videos and read explanations on the iterative model and how it's used in system development life cycles (not to be confused with software development life cycles) but I still don't get it and i'm getting desperate; can someone please explain it like i'm 5 years old, because mentally I am. Best source I could find: [ URL_0 ]( URL_0 ) | Technology | explainlikeimfive | {
"a_id": [
"ga34zlq"
],
"text": [
"With a system like Waterfall, you're given a project, figure out the requirements, then you build them in order until the project is complete and shown to the client for approval. With an iterative system, you repeat this process in smaller time increments, building a bunch of stuff, showing it to the client for feedback and testing, then going and making the required changes. Once you feel enough iterations have been performed, you deliver the project"
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
ji0itb | Why do so many games start with “Press [Button] to start?” | Technology | explainlikeimfive | {
"a_id": [
"ga3k8nt",
"ga3kc9v",
"ga3td65"
],
"text": [
"Well to think of it another way, you don't want the game to start suddenly. The push button to start phrase goes back to the days of arcades. In am arcade, if the game started when you added money, then the second player would have to join once the game had already begun. So by waiting for a start button, it allowed multiple player games to start at the same time for everybody.",
"It's a hold over from arcade machines, which would be set to display action scenes from the game on loop to get people interested in playing them, then if someone wanted to play, they'd press a button to move it away from the display mode into actually playing the game. Later home console games started by adapting those arcade games directly, and it just sort of stuck around despite not having a purpose outside of the arcade.",
"Consoles require games to have player interaction within a certain time limit of launching the game. They don't want players to feel the console is broken. So many games throw up a start game or similar button just to have you do something. They then finish loading the game."
],
"score": [
12,
5,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
ji0oep | When there are multiple light switches controlling one set of lights, how is each switch made to turn lights on from both the up and the down position? | Technology | explainlikeimfive | {
"a_id": [
"ga3n3n8",
"ga3nvb7",
"ga3pf4l",
"ga3p30d"
],
"text": [
"A picture says More than 1000 words URL_0 (In dutch as I don’t know the English term, but only the pictures matter).",
"Think of a railway line. It's a single line, and then it splits into two parallel lines with a switch track which could send the train along either track, those two lines run in parallel for a while, then they converge via another switch track back to a single track. At each end there's a switch track. So imagine the line is connected all the way across. Either switch track could be switched, and it would disconnect the line. Equally, if the line wasn't connected switching either track would then connect That's how two-way light switches are wired.",
"This is known as a three way switch. You need a switch made for it, and the switches need to be connected to each other in a certain way for it to work correctly. This video from This Old House explains how a three way switch is wired. URL_0",
"There are two wires between the switch. Let's call them A and B The first switch connects either A or B to the incoming wire live with power. When you flip it you just change what wire is connected. The second switch connects either A or B to a wire that goes to the lamp. The lamp is also connected to the neutral wire. So if the first switch if flipped so it is connected to wire A the second switch turn on the light. If the second switch to B the light turns off. You can turn it on if you flip the first swithc to B So the key is that there is two wires between the switches and the current has to pass trough both to get to the lamp The illustration of the [wiki page]( URL_0 ) is simpler to get than the text. & #x200B; You can have more switchers than two if the one in the middle. Let's call the outgoing wires C and D. So in one position is to connect AC and BD and in the other AD and BC. & #x200B; If it is a system where you have multiple buttons and you press it to turn on and to turn off the light the button just sends a signal to a control box that is it pressed and you have a simple computer that controls the light. So you can build quite a complex system."
],
"score": [
18,
4,
3,
3
],
"text_urls": [
[
"https://nl.m.wikipedia.org/wiki/Wisselschakeling"
],
[],
[
"https://youtu.be/LozeRVU7YKU"
],
[
"https://en.wikipedia.org/wiki/Multiway_switching#Traveler_system"
]
]
} | [
"url"
]
| [
"url"
]
|
|
ji1up0 | Why do PCs run faster with 2 4GB sticks than 1 8GB stick? | Why isn't the computer faster if all the information you need to access is on the same place (in this case, the 1 8GB stick)? I recently saw a post about a guy who had a very slow PC that became 2x more powerful when he changed his 8GB with 2 4GB (don't know if it matters, but the three sticks were ddr4), but it doesn't make sense to me?? | Technology | explainlikeimfive | {
"a_id": [
"ga3t7dl",
"ga3tt2v"
],
"text": [
"It's like having 2 doors into a room instead of one. You can get twice as much through the door in a period of time",
"RAM communicates with the CPU over channels. Each channel is more or less fully saturated with each write or read operation regardless of the size of the RAM stick(s) connected to that channel. So, if you have more than one channel, you can speed up *access time* of data even if you don't expand the amount of RAM storage you have. A modern desktop CPU usually has 2 channels, with either one or two RAM slots connected to each. Thus, you need 2 sticks of RAM to utilize dual-channel speed. A modern *server* can get up to 6 or even 12 channels, with up to 4 CPUs in one motherboard, [where stuff gets a bit bonkers]( URL_0 )"
],
"score": [
19,
5
],
"text_urls": [
[],
[
"https://lenovopress.com/assets/images/LP0646/ThinkSystem%20SR860%20internal%20view%20with%20callouts.png"
]
]
} | [
"url"
]
| [
"url"
]
|
ji1z72 | How might one explain the meaning of “DDoS” to a less tech-savvy individual? | Technology | explainlikeimfive | {
"a_id": [
"ga3tnk9",
"ga3ucij",
"ga3v8d7"
],
"text": [
"DDoS is like a Black Friday sale. You just wanted to pop to the shop for some milk but now you can't because thousands of other people are preventing you getting in.",
"10,000 people are talking to you at the same time and you have to answer all of them immediately.",
"Your local pizza shop has a phone line. Normal ppl call in and order their pizza and hang up, leaving it available for other ppl. DoS stands for denial of service. The actor is denying the service to other users. One guy calls the pizza shop and doesn't hang up. The shop owner hangs up on him but he just calls right back. He's using a computer to dial the shop phone number continuously 24/7. Other ppl that want to call for a pizza get a busy signal. The pizza ordering service is denied. Shop owner gets fed up with this cause he's loosing business. He calls the phone company and tells them this guy needs to be shut off. Phone company shuts off the assholes phone. Shop owner and pizza eaters are relieved. Asshole throws a hissy fit. He builds a computer program to hijack phone from all over the world and call the pizza shop. Phone company can't shut off phones from other places other countries. The service is denied from a distributed source."
],
"score": [
22,
9,
7
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
ji27rm | Why some games, even with extremely simple graphics are laggy? | Technology | explainlikeimfive | {
"a_id": [
"ga3vcq4"
],
"text": [
"Games like Minecraft are graphically undemanding, but tend to have a large number of digital assets (ie textures, colors, templates, \"worlds\", weapons, etc.) and those have to be loaded in as well. I've been in minecraft worlds so dense that it brought my 1080ti to its knees along with large RAM usage. Another explanation could be poor optimization for the platform you're playing on. This is especially prevalent on console to PC ports (eg RDR 2)."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
ji5aip | How does digitalization of money work? | Technology | explainlikeimfive | {
"a_id": [
"ga4l504"
],
"text": [
"Don't forget that if you really look at it, cash is also just data - declarations printed on paper - and is also vulnerable to compromises, such as pickpocketing and counterfeiting. The information in a computer is subject to a different set of \"laws of physics\" than the information carried by a banknote or a traveller's check, so the practical considerations about keeping it safe are different: digital money is usually protected using cryptographic ciphers to hide the data, and using cryptographic signatures to authenticate its source and prevent tampering. But we need to keep our expectations scaled back. Currency was never perfectly secure. Long long before the computer age, banks kept their ledgers in, well, *ledgers*. Great big books full of, basically, handwritten spreadsheets. In that form, the money was just information in a database, and if you could sneak into the room where the ledger was stored and forge some updates to the balance, then you could steal money, just like you could do today by breaking into a bank's computer systems."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
ji8nq5 | Did the first people to own a television have nothing to watch? Or did the first broadcasts go out to nobody? | Technology | explainlikeimfive | {
"a_id": [
"ga52d5a",
"ga5v5ni",
"ga5ehgb",
"ga5dxmc",
"ga5i55d",
"ga5v8lr",
"ga5dk5k",
"ga60afq",
"ga5mfwb",
"ga5w4n7",
"ga64esk",
"ga5utuz",
"ga5wx48",
"ga5y6pz",
"ga6jnz9",
"ga5zn5r",
"ga62s95",
"ga66ngj",
"ga5ziyx",
"ga5wbam",
"ga6pu7m",
"ga6muq2",
"ga62s2n",
"ga6pjsa",
"ga769sf",
"ga6vzzy"
],
"text": [
"Chicken vs egg problem. The first TV broadcasters were TV/Radio set manufacturers. Shows were broadcast on both radio and on TV and had to be done live as there was no way to prerecord video like there was with audio and the phonograph.",
"In the early days of broadcasting, there would be very few channels (perhaps only one), and TV would only be available at set times of the day, for example a news broadcast, and then they'd stop broadcasting and the TV would just pick up static for the other ~23 hours of the day.",
"In the UK anyway, the Queen’s coronation (broadcast on both TV and Radio) was the “killer app” for everyone to go buy a TV. Before that it was a very limited audience, with almost nothing broadcast only for TV.",
"Same with the telephone right? First phone, who you gonna call? Heard a story about the first phone salesmen. One guy was selling way more than anybody else. So they asked him how he did it. He said he told people they wouldn't have to get dressed to talk to their neighbor.",
"I guess that it happened the same that now happens with the VR sets. People bought them for the cool factor, even if there was still not a lot of content for them.",
"An elder relative says that back in the fifties there were three channels and they didn't even stay on the air all day",
"The first television broadcasts went out to a very small audience. Mostly other technicians. The first mass audience was mostly people in bars and department stores.",
"Think about when you imagine people watching Television. Think of FDR's fireside chats and picture the family, they are listening to radio, right? Now picture the earliest you imagine the family watching Television. What time period, 1950s, 1960s? If you are in the UK you probably are aware that the Queen's Coronation was the first widely watched television show there, in 1953. Now realize that the first broadcast television show was in 1928. That's a long time of struggling with the chicken and egg problem.",
"My mother tells us of her first experience of watching TV while growing up in Puerto Rico. My grandfather bought one in the states where, presumably, there was some programming. She said all 1¹the neighbors would gather around it and watch a static image of PR's version of color bars which figured a native american.",
"Dual broadcasting to TV and Radio, at the same time. Good way to do it. You get to have a large enough audience, and you will drive more listeners to get tvs",
"If you want to do a deep dive on the technology and history behind TV, check out Technology Connections on the YouTube. He's fantastic. I almost kinda understand how TV works.",
"Yes, people had TV’s first with nothing to watch. Live broadcasts were rare or set at certain times of the day, then after the show ended (for example the news) the TV would return to its static state.",
"For the case of radio -- and I suspect also TV but don't have a source to confirm that -- bootstrapping was done by shared organization of both sides. That is, you're not just limited to domestic mass consumption; you can use broadcasts to shared locations where you provide the reception hardware as well. > Starting around 1920 a small number of broadcasting stations began operating, and soon interest in the innovation was spreading nationwide. In the summer of 1921, a Madison Square Garden employee, Julius Hopp, devised a plan to raise charitable funds by broadcasting, from ringside, the July 2, 1921 Dempsey-Carpentier heavyweight championship fight to be held in Jersey City, New Jersey. Hopp recruited theaters and halls as listening locations that would charge admission fees to be used as charitable donations. He also contacted RCA's J. Andrew White, the acting president of the National Amateur Wireless Association (NAWA), an organization originally formed by American Marconi which had been inherited by RCA. White agreed to recruit the NAWA membership for volunteers to provide assistance at the listening sites, and also enlisted David Sarnoff for financial and technical support. RCA was authorized to set up a temporary longwave radio station, located in Hoboken a short distance from the match site, and operating under the call letters WJY. For the broadcast White and Sarnoff telephoned commentary from ringside, which was typed up and then read over the air by J. Owen Smith. The demonstration was a technical success, with a claimed audience of 300,000 listeners throughout the northeast. It's also worth noting the participation of NAWA there -- quite a lot of the early radio pioneers were amateurs with broadcast licenses. So they didn't need broadcast content to participate, but had the hardware to listen to broadcast content if it was available.",
"It all started with demonstrations with the 1939 Worlds Fair in New York. I think FDR was the first broadcast. There were only a few receivers, but that grew rapidly in the 40s after WW2.",
"Not many people are really answering the question or they're just guessing. Here's a good rundown of how it started in the US. [ URL_0 ]( URL_0 ) The answer is closer to \"the first broadcasts went out to nobody\", just the people who were at the 1939 World's Fair in New York. There were some events broadcast in the next few years, but television didn't really take off until after WW2. Broadcasts were like radio is now...over the air. So you wouldn't buy a TV unless and until the nearest city (assuming it was near enough) started broadcasting.",
"The very first thing broadcast was by RCA - a 13” Felix the Cat doll rotating on a gramophone turn table. Audiences saw it on a 2” screen",
"In the very early days, test transmissions were sent out for a short time every evening, after normal radio programming had shut down. Hobbyists and enthusiasts could try out their equipment, although at first the sound and pictures had to be transmitted separately -- there was only one channel to use for both! This started in 1929, with simultaneous sound and vision from 1930. Typically the user would use their normal radio set for the sound, and their new (and very expensive) tv for pictures. Real service began in 1936, but shut down at the outbreak of World War 2.",
"I dont seem to see anyone talking about shows being sponsored by a brand instead of regular commercial breaks. im young so this comes from VHS of Red Skellton show but after a bit he would do a sponsored PET sweet and condensed milk or floor wax then go on to the next skit but i dont know how verity shows match up with other broadcasting",
"I read up on the history of TV in Germany once (one of the first places to experiment with the technology). In the mid to late 30s there were only a hand full of TV sets set up in public halls for people to gather around a d watch. Maybe if you were super rich you could get one for your home. So in this situation they started at the same time: get a few sets in some halls set up - > start broadcasting (I think it was like 2 hours each night of a variety program).",
"In 1948 the Democratic National Convention was “broadcast” (not a term used in those days) to about 200 sets in the Philadelphia area, most of them experimental and owned by engineers.",
"this happens all the time. as an example, there are 5G phones but no 5G networks. Same thing for 4K TVs. Porn has been credited with advancing much of the push for higher resolutions.",
"The first demonstration of a 'high definition' television transmission - in those days that meant 405 lines - was made to an exhibition called Radiolympia. So the people who saw it did so on a demonstration set there URL_0",
"They started out with one station in NYC for example and scheduled an hour or two here and there. This random page I googled gives a timeline where for example in 1932 a station had 4hrs of broadcast per day. URL_0",
"My dad said there was lots of dead air and \"test patterns\" especially at night in the 50s and 60s. If you've seen the movie \"Back to the Future Part II\", you'll see a hint of it when Howdy Doody comes on in that scene. There was literally nothing broadcasting before that hour.",
"I actually had this happen to me. Lived in Iraq, we had like 3 channels total. When their was nothing to show u only pick up static. So during the night we point our antennas at Kuwait, and pick up their channels. Otherwise if theirs nothing on TV u can’t get or see anything, so I’m guessing they had the same issue back in day too.",
"My Father saw his first TV when he was in the Coast Guard in NYC 1949. He said the only programming was some show called Super Circus which was like vaudeville and baseball games. Wiki Super circus =[ URL_0 ]( URL_1 ) You couldn't see much of a picture unless you stood in directly front of it and baseball tickets were free from the USO so why would you watch baseball on the little screen?"
],
"score": [
5296,
761,
743,
518,
175,
118,
95,
31,
27,
22,
19,
14,
14,
9,
8,
7,
7,
6,
4,
3,
3,
3,
3,
3,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"https://www.encyclopedia.com/media/encyclopedias-almanacs-transcripts-and-maps/television-broadcasting-history"
],
[],
[],
[],
[],
[],
[],
[
"https://en.wikipedia.org/wiki/Radiolympia"
],
[
"http://jeff560.tripod.com/chronotv.html"
],
[],
[],
[
"https://en.wikipedia.org/wiki/Super\\_Circus",
"https://en.wikipedia.org/wiki/Super_Circus"
]
]
} | [
"url"
]
| [
"url"
]
|
|
ji8xye | What is a “Raspberry Pie” and what does it do? | Technology | explainlikeimfive | {
"a_id": [
"ga541nz",
"ga5429p",
"ga5497c"
],
"text": [
"A Raspberry Pi is a low cost low function computer. It can be used for a lot of low performance requirement tasks where a full size computer is expensive for overkill.",
"A Raspberry Pi is a small, cheap computer that can be used for a variety of functions. I had one to run Kodi, and I have a friend that uses one to operate some automation in his shop. It’s basically the size of a cell phone but can be daisy chained with other Pis to make a more capable unit.",
"Really small Computer that you can control all kind of things with. LED stripes, robotic stuff, home automation, home Media Server, automatic watering System for your plants etc. I have three RPis in my home. One for my network drives and to control my lights and heating One connected to the smart mirror I built One inside an old radio from the 70s that is now a a facy mp3 player. It's about the size of a mobile phone. The RPi is not comparable to your ordinary home PC in regards to computation power but is capable to achieve a whole lot of stuff"
],
"score": [
15,
9,
7
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
ji9hau | How does a video game developer optimise loading times in a software update? | Recently saw an article explaining that loading times were reduced by 70% in the latest update for the last of us remastered. I was wondering how is this possible without upgrading the hardware used to load the game, and also why it wasnt done earlier by the developers | Technology | explainlikeimfive | {
"a_id": [
"ga58q7m",
"ga5bg0z",
"ga58wln"
],
"text": [
"Time. I’m not a game dev. But the software projects I’m developing have a very short window to be released in. In defining what will go into the initial release I cut out absolutely everything I could to meet the deadlines management set. I looked at pieces of the project and decided what I must do now and what I can put off for later. This way I can make sure it works well. It may be slow and under optimized but it will be on time. In projects where time isn’t as much of a factor I’ll spend much more time making certain something works well.",
"One way they can do this is to optimise the load order--with existing consoles they have the traditional mechanical hard drives in them, and the issue with those is that it takes time to move between two different parts of the disc. If you can somehow move all the stuff you're loading around so it's right next to each other, it will load faster than if you load the first item on the disc, then the 77th item, then back to the 12th item, etc. Doing this takes a heck of a lot of time, though, time the developer probably was unable to spend during the initial development of the game. Next gen consoles will use SSDs, which have no real delay between switching to different parts of the disc, so this particular optimisation will no longer be relevant.",
"So there are a lot of algorithms to use to load stuff and such. They can switch algorithms to something more efficient. An example is you have a set of date sorted by a key let’s say 100 items long. And you need to X item. You can A search the set 1 by 1 and check to see if it is the item you are looking for. Or because it is sorted check if it is greater or less than. So you want to find the 39th item in a sorted set of 100. First you check if it is greater or less than 50, than 25, then 33, 41, 37, 39 and your done after 6 steps. Vs the 39 it would take you to do it otherwise. Using more efficient algorithms is one way to do it. Another is to take advantage of the hardware you are using. You’ve probably heard of cores and threads in a CPU. A big part of optimization is utilized those extra cores and threads you have. Let’s say you need to load a large list of texture into memory and process player data. You can send one thread to load the textures while another one loads player data. I hoped that helped. If you have any questions I’ll try and help you out."
],
"score": [
7,
3,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jib70o | what is the point of airplane mode?? | Technology | explainlikeimfive | {
"a_id": [
"ga5fxnc",
"ga5g93j",
"ga5g0jr"
],
"text": [
"When you first land in a new country your phone makes a bunch of handshakes with the local networks. These transmissions are often audible in the pilots headsets and can hinder their communication with the tower/ground. It's just a little background distortion, but you can imagine the result when a planefull of phones all do so at once. It used to be you couldn't use your phone in flight, even if it had airplane mode, because not all phones had it so the devices were just banned. Thankfully it's now an industry standard Source:. My father is a professional pilot.",
"It was added as a feature so that you wouldn’t have to turn off your electronic devices during a flight. Airplane mode is supposed to stop your or anyone else’s electronic devices from interfering with the radios on the airplane.",
"Its a feature that was implemented into phones because some older airplane electronics could be negatively impacted by cellphone signals Turn on airplane mode, and the relevant signals are shut off. Nowadays, most on board electronics doesnt really care anymore, but it stuck around."
],
"score": [
15,
3,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jif5x3 | how did the people who invented the clock know what time it was? | Technology | explainlikeimfive | {
"a_id": [
"ga63hqe",
"ga61snk",
"ga62qxl",
"ga61uwa"
],
"text": [
"The sun. Originally before railways and stuff time was based on when the sun rose, reached its zenith and set locally. This meant that every town had a slightly different time than the next but since clocks weren't all that accurate and it took a long time to travel between places that were far away from each other that didn't matter. Our current system of telling the time comes from older system where you just divided the time between sunrise and sunset in twelf parts and then also divided the night into twelve parts too. You could use stuff like sundials or all sort of primitive timekeeping mechnicsms like hour glasses or water clocks or simple candles to create hours without too much effort and a resonable amount of accuracy. At some point it was decided for the sake of consistency to divided not just day and night into 12 hours but the entire day from midnight to midnight into 24 hours, so hours would all be the same size. Later the hours were subdivided into minuted and the minutes were subdivided a second time into seconds. But seconds take an amount of accuracy that you didn't really get until fairly recently. For the longest time before widespread industrialization you set a big public clock on a church or city hall after the sun and that was good enough for everyone else to copy. When railways became a thing, the fact that each stop had their own time really confused things. So railway companies create their own time that was synced between all the platforms where their trains stopped. Eventually that developed into the timezones we use today which can be synched via longwave transmitted time signals from an atomic clock and slightly less accurately via the internet and ntp servers that take their time from the same atomic clocks. The atomic clocks are frequently operated by nation standard bodies so they don't tell the time as much as telling time what it legally is.",
"Time has been around for a lot longer than clocks, people were using sundials long before clocks were invented. Clocks were just modeled after the sundial.",
"Noon: \"Sun is the highest now. Lets call that meridiem. A good time to start counting.\" Noon, next day: \"Tis' be noon again. There shall be a dozen equal chunks of time before Noon (Ante Meridiem) and a dozen equal chunks in the afternoon (Post Meridiem).\"",
"Figuring out local noon is actually very simple. Take a straight stick and hammer it into the ground. When it casts no shadow, it's noon."
],
"score": [
31,
30,
6,
5
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jigcc4 | How do ISP's offer faster internet without installing new cables or fiber? | I have pretty-slow internet at 50Mbps through "ISP A." Fiber is not available in my area even though a friend living one mile away has it. The fastest they can offer me is 75Mbps "ISP B" offers "up to" 1,000Mbps (Gig). Why can't "ISP A" offer that? Are faster internet packages just dependent on the type of router/gateway a provider, well, provides? I obviously don't know how anything works. EDIT: wow. Thanks so much for all the insight folks. About to read through them all! :) | Technology | explainlikeimfive | {
"a_id": [
"ga69qtz",
"ga6x6jb",
"ga7c6uo",
"ga6in46",
"ga6znww"
],
"text": [
"If they're different ISPs, then they're different physical networks. Typically that might be cable TV vs. telephone line vs. fiber vs. microwave vs. satellite. Those have inherently different speed capabilities, and the actual speed you get will also depend on the type of equipment on each end (both in your house and on the network). ISP A can't offer you ISP B's speed because, probably, they don't have the same equipment and cables as ISP B. If it's all over the same wire (I'm not sure if there are jurisdictions with competing ISPs sharing cables), then it's the end-point equipment...the modem on your end, the router on theirs.",
"Are you in the UK? If ISP B is Virgin Media or Hyperoptic or a few others, they have separate cables. Most fibre providers offer fibre to the cabinet then VDSL2 over standard twisted pair telephone line, which is the limiting factor. Providers offering fibre to the home or DOCSIS over coaxial cable can offer faster speeds.",
"It depends, mostly on the last mile. What I mean is that the backbone is usually FAF (fast as f) but the cabling that comes close to you won't be nearly that fast. If you are being offered 'up to' 1Gb then you probably are dealing with a DOCSIS 3.0 implementation - you can't go any faster than that. DOCSIS 3.1 would be 10x that, but the back end equipment and your modem would have to be compatible. You can typically reuse that cabling. ISP A and B may have the same cabling (typically only one or 2 firms do 'cabling' and everyone leases them out, when you do 'carrier diverse' internet you have to make sure that you are getting true diversity and the carrier isn't just leasing another's cabling) but support different standards. If you have fiber to your house, which is becoming more common, that fiber can go up to 100Gb (so 100x faster than your offerings) but the cost of the provider equipment and the modem make that an enterprise only offering. TLDR; cabling matters, but less than you might think",
"The operative words in that description are \"up to\". ISP B is saying that you could theoretically get 1Gbps in absolutely perfect conditions, but they don't actually know those conditions exist at your house until they actually come out to install their equipment, so if you were to switch and end up with a connection no faster than ISP A gives you, they wouldn't ever have actually \\*lied\\* to you...",
"Basically there is a hierarchy of throughput associated with broadband access networks. At the bottom of the list is DSL which uses telephone wires. There are multiple types of DSL with some being quite an old technology (20+ years). They can get very fast but only when you're close to the central office. So if you live out in the middle of no where and DSL is your only option, you might get 1 to 5 Mbps downstream max whereas someone with good telephone cables and fairly close to the CO will get 100 Mpbs. Then there's cable which can also get very fast but it depends on the condition of the coax cable (which can be decades old) and what kind of technology they use. So a fairly new DOCSIS system can provide gigabit services but they arent offered everywhere because of the reasons I just mentioned. Fiber-to-the-home is at the top of the throughput capability for broadband. They can offer gigabit service and some systems even 10 Gbps although you dont really need that for a residential connection. These technologies are based on passive optical networks (PON) which offer a roadmap for 25G and beyond in the future. As for the different speed tiers offered by a service provider, they can do traffic shaping in their network to make it top out at any speed they want."
],
"score": [
15,
5,
4,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jijo7x | Before the PS2 era, why were video games much smaller in total byte size than other mediums such as a DVD movie or an Episode of Seinfeld? | Technology | explainlikeimfive | {
"a_id": [
"ga6vunx",
"ga72rzn",
"ga6unm1",
"ga6uchh",
"ga71hd5",
"ga7dl1w"
],
"text": [
"Size of games is completely based on its visual and audio resources. The code itself takes very little, and there are many games that are very intricate and complex, but they don't rely on graphics or a lot of high quality audio files. Minecraft is a very good example. Games nowadays take so much space because of huge amount of high poly models, high definition textures, and a lot of voice files for characters and localisation. Games like Warzone take such huge amount because they force you to download highest resolution textures and localisation for every language. Other games like Apex legends and Rainbow Six siege offer optional free localised audio and higher quality texture upgrades respectively.",
"Because an episode of Seinfeld is a record of every single image (30 per second) and every second of distinct audio. By comparison a game doesn't store every possible image, it simply stores some assets and the instructions on how to use them to create images with them. For example Tetris doesn't store every possible combination of pieces on the board as a seperate image the way that a video (or twitch stream) would. Instead it has a small image of one block, an image of the board, and the code to place that block repeatedly as needed to form a complete picture. Similarly the music doesn't need to be stored as a complete sound recording lasting several minutes (though these days it usually is). Instead older games would just store a single copy of each note needed (amounting to a few seconds of audio at most) and then have a programmed music sheet to play them in the correct sequence.",
"Old games were restricted by the technology of the time. It was difficult to put large amounts of information on a small object and the consoles of the time could only handle so much data at a time so the games of the time are (relatively) tiny. On the flip side, the Fresh Prince was shot on a reasonably high quality film camera. When you convert that film to a digital format you decide how compressed to make it(more or less determining the resolution of the video/audio). Because Amazon isn't sure what kind of screen you'll be watching the episode on they want to give you the highest quality video available. Higher quality video = more memory required.",
"the Ps2 was the proof of concept that games could use Dvd's as a medium, this came with a lot of extra space that developers are more than happy to capitalize on. this was the same jump when moving from cartridges ot disc based medium, developers gaining ton of extra Headroom that made optimizing to the single byte less necessary(but still required since console developed is entirely around Ram, if you go even a single bit over max memory a console will Crash.)",
"Games are a conglomerate of assets, logic and (recently) shaders. That answer isn't good for a five year old, so here we go: A modern video game is made up of data on a hard drive. Some of that data is code (we are VERY good at coding, so we can make code very small on a hard drive because we know how to optimize it), models (we are GREAT at modelling, therefore meaning we can make things look beautiful and almost lifelike - which means that they take up MORE space) and shaders (we are only getting used to the idea of a shader, a graphics library abstraction that allows us to make our models/textures look better than they're meant to otherwise). Shaders take up a medium amount of space, models/textures a large amount of space and code a small amount of space. As we go on, we expect better graphics - not more solid logic or more sick slick enormous fuckin shaders.",
"Art assets (mostly textures and the several layers of textures needed by modern graphics engines) and the explosion of RAM. That's really it. The game code itself doesn't take up a lot of space. In the height of the 16-bit gaming era during the SNES' day, games were still 2D, and those games didn't require a ton of space, partially because the games just didn't require a ton of textures because 1) the hardware usually restricted the number of colors or objects on screen at once because 2) the hardware couldn't fit a whole lot in RAM at once and so used a ton of tricks to try and save space. Now that modern computers have a lot more memory, and even have large swaths of dedicated *video* memory, they can fit a ton more in there, and suddenly you need more textures, bigger textures, and more detailed textures to paint all these glorious 3D models with the latest fancy-ass graphics techniques. To render a single model, that model will have the general color texture. Then they might overlay a normal map for extra lighting accuracy. Then they might put a bump map on top of that (think bricks). Sometimes a single character may have a secondary set of textures on top of all that to create animated effects. One of the finest examples of this is easily laid bare by Final Fantasy 7 Remake. Go look up videos of the original on PS1, and then find videos of the new one. And then, look for videos of Chrono Trigger, which was considered gorgeous at the time, but still took up a small fraction of the space FF7 did. The original FF7 and Chrono Trigger are roughly equal in terms of scope and play time but the space requirements for both games differ massively. The reason for this is mostly down to the art assets required to draw everything in 3D. As games get bigger, with more detailed artwork and larger levels, the required space to store them will just keep going up. Incidentally, remember that FF7 Remake is just the opening 2 hours or so of the original game. It also takes a lot more time to make a game of the same scope as it did back then, again, due to art assets. \\[Edit\\] Clarity."
],
"score": [
204,
25,
21,
20,
6,
4
],
"text_urls": [
[],
[],
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jijru4 | Why gifs take longer to upload than Videos do even if the video is longer. | Technology | explainlikeimfive | {
"a_id": [
"ga6v3j5"
],
"text": [
"Because animated GIFs are a hack that was never intended for what we use for them now If you take a video, even a short one, and turn it into a GIF it will be wayyyy bigger, generally ~10x the size because GIF compression isn't nearly as good as video compression. This was part of the push behind GIFV/HTML5 videos because they operated like a GIF but were compressed like a video so a 30 second clip wasn't 50 MB. GIFs are a series of independent images that are each compressed as independent images, there is no compression between frames. Videos are mainly compressed through time not across the image because the background tends to stay constant so you don't need to store it more than once or twice."
],
"score": [
18
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jik4wh | Why do simulations and renders (Blender, etc.) take so much more time and processing power than, say, video games that achieve the same thing much faster while also being more complex? | Technology | explainlikeimfive | {
"a_id": [
"ga6ztfg",
"ga6xiog",
"ga74m9e",
"ga70itm",
"ga74nx9",
"ga7c3vc",
"ga7d4za"
],
"text": [
"Video games are trying to render something *good enough* before the next frame is due to be sent out Blender is trying to render something as perfectly as possible *eventually* You can model things in Blender with a level of detail that would bring video games to a screeching halt because there are too many surfaces and polygons to calculate in a timely manner. Video games use a series of cheats to get good performance like using low resolution textures on things that are far away and only using the highest resolution on close up surfaces. Video games also use rasterization rather than ray tracing like Blender so you get functional lighting and shadows in video games, but reflections and multiple light sources and interplay of shadows is generally lost while proper renders retain that to give things a more realistic look. Video game graphics have gotten a lot better through the years, but you could never swap them in for movie CGI. There is sooo much CGI in movies that you never notice because it is *that much* better than a video game's renderings",
"Video games have to finish rendering 1 frame at least every 1/30 or 1/60 of a second to produce a smooth experience. This means shortcuts are used to achieve the goal. Rendering in blender or in movie cgi doesn't have this requirement. They're not shown in realtime. You can spend 24hours to render the hair in every detail",
"video game rendering is definitely not more complex its gotten good but its not studio quality good since that takes too long be done in realtime. Dedicated renderers on the other hand strive to achieve high fidelity and proper simulation, that takes too long to be done in real time but as a plus the only limitation to the accuracy of the render is time and the detail that was programmed in.",
"There are a huge amount of shortcuts taken in video games, that are considered GOOD ENOUGH. Some examples could be using simpler physics equations, (you can often get like 80% accurate equations that are simple algebraic equations rather than recursive computational differential equations that are more 99% accurate, but the computational likely takes at least 100x more processing power), you often have pre-scripted animations with video games that don’t really use physics, but looks like it, and there’s also a lot of visual polygons that aren’t using in physics calculations(example: often capes in video games do not interact with other objects). The point of renders is to specifically see these interactions, and as accurate as possible, so the shortcuts in video games aren’t useful in renders/simulations.",
"If it were actually true that video games do the same thing much faster, then we wouldn’t have any need for pre-rendered cutscenes and things like that.",
"Video games cheat. For example, to render a tree, something like Blender is taking into account every leaf, every branch, every shadow, every texture, every ray of light, to make a perfect picture of a three dimensional tree. This takes a long time. A video game takes that perfect picture of a tree as a 2D gif and pastes it on a rectangle and orients that rectangle toward your face. This takes no time.",
"Video games don't achieve the same thing. If you doubt this, look carefully at the way light reflects from curved surfaces in any video game. Compare with a CG Hollywood movie - the movie is much better."
],
"score": [
77,
12,
12,
7,
5,
4,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jik7db | What causes bugs in code and how are they fixed? | Technology | explainlikeimfive | {
"a_id": [
"ga6z721",
"ga7enn1",
"ga6ym6z",
"ga7k9tr",
"ga7fwat"
],
"text": [
"Code is like a series of instructions. Computers follow instructions perfectly. If you yourself have ever been given instructions, like in LEGO or IKEA furniture, you'll know that sometimes following instructions directly without using your own brain and reasoning can quickly result in [abominations]( URL_0 ). Computers are the stupidest things out there, and if there is an error or gap or unforeseen edge case in your instructions, the computer will just stop, or it will produce [abominations]( URL_0 ). To fix a bug, you need to find out exactly why your instructions weren't good enough, and then modify them to correct for the error.",
"Code is a long series of really dumb instructions. They're dumb instructions because the computer will attempt to do *precisely* what you tell it to do. It won't deviate, it won't troubleshoot, and it won't make any assumptions about what you really wanted. Bugs occur when a thing you tell it to do turns out to be impossible, or when the tiny things you tell it to do don't actually accomplish the goal you want it to accomplish. Imagine the following set of dumb instructions for a person washing clothes. 1. Remove a handful of clothes from the hamper. 2. Insert handful of clothes into washer 3. Repeat #1 and #2 until washer is full 4. Pour 1/4 cup of detergent into washer 5. Insert Y money into washer 6. Select wash. Seems simple, right? This set of instructions has bugs. What if the hamper runs out of clothes before the washer is full? There's no condition to skip past #3, and therefore the program will pause on #3, or rather it will throw an exception to say you triedto remove clothes from a hamper that didn't have clothes. The CPU doesn't know how to handle this situation, so it throws an error. Okay, let's fix that. 3: repeat #1 and #2 until washer is full *or hamper is empty* We've just fixed the bug. Now, we continue and let the program run. Now we can have a situation in which it's possible for the washer to run with only a single handful of clothes. This is legal from the computer's perspective, but it could be considered a bug from the programmer's perspective because the programmer doesn't want to computer to handle the laundry inefficiently. This is a different type of bug -- it's a bug of functionality and intent. In order to fix the bug, the programmer needs to write more instructions to further specify more precise conditions about when to run the wash and when to wait for more laundry.",
"The simple answer, is humans. Humans write the code. We aren't perfect. Sometimes it's a logic error that the coder made. Sometimes it's something they didn't think about happening. Sometimes it's a misunderstanding of how an API works or a failure to do boundary checking. They are also fixed by humans. Someone has to go back into the code, fix the bug, and recompile.",
"Bugs in code are caused by- yes sir, I'm working on it right now- errors that get intro- no, not for another week, sir- excuse me, introduced by the developer- no sir, that won't make it happen any sooner- where was I? Oh yeah, errors which are introduced by the developer. They're called logical errors and- no, _sir_, spraying a bottle of compressed air upside down will _not_ make compilation any faster- and they're distinct from another category of errors known as \"syntax errors\", which can almost always be caught- JESUS FUCKING CHRIST MAN, DO YOU WANT ME TO FINISH THIS OR CHAT WITH YOU!?!? Ahem. Bugs are caused by micromanaging bosses.",
"Because humans think in \"do what I mean\" and computers think in \"do what I said\" URL_0 This is ridiculously accurate."
],
"score": [
37,
36,
32,
5,
4
],
"text_urls": [
[
"https://d2otcp20hyujm8.cloudfront.net/wp-content/uploads/2018/04/05103539/Ha4W6qW.jpg"
],
[],
[],
[],
[
"https://www.youtube.com/watch?v=Ct-lOOUqmyY"
]
]
} | [
"url"
]
| [
"url"
]
|
|
jimgrk | How does a camera "see" the real world? | Technology | explainlikeimfive | {
"a_id": [
"ga7f7c7",
"ga7imty"
],
"text": [
"Using a piece of technology called a CCD. Basically there are photoreceptors that can record light as a series of electrical charges. If you understand how the photoreceptors (we can just call them pixels) consistently record the light as voltages, you can reproduce an image based on the those voltages. This will look like poop smear with a few pixels, take an image and zoom in, eventually you will get to little dots and that is it. The more little dots the higher the resolution, or the ability to discern between lines. If we let our eyes naturally scan we get about 515 megapixels worth of resolution, a single glance is 5-15. So a 5 megapixel photo looks like a decent representation as long as you don't zoom in (or blow the image up a lot). A 50 pixel image might give you some idea of what you are looking at, but not much. Clear as mud? TLDR; a sensor was invented (by Kodak, of all peopel) that records the impact of photons as discrete electrical charges. Those charges are recorded into memory as bits. Knowing how those bits were laid down lets us produce an image from that information that reflect the way our eyes interpret the visible light spectrum.",
"Same way you do. Your eyes take in light that is reflecting off of objects and your brain makes sense of it. A camera lens takes in reflected light and, nowadays, a sensor makes sense of it."
],
"score": [
8,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jinkra | If LEDs are supposed to a decade, why do so many die so quickly? | Context: I moved into my apartment 18 months ago and I've already replaced four of these lights. I thought these bulbs were supposed to last at least 10,000 hours. Guessing at about 4,000 hours of usage, the cost savings is not much better than incandescent. | Technology | explainlikeimfive | {
"a_id": [
"ga7iyti"
],
"text": [
"Governments and consumers were sold a lie. The LED chip itself may last 10,000 -25,000 hours but that spec has nothing to do with the internal switching circuitry that converts AC power to DC power. That’s what usually dies within a year or two. The higher cost of LED upfront doesn’t save money over incandescent- yet. LED still has a long way to go to even reproduce a proper white balance. Most LED’s aren’t even rated for a 90+CRI. The colors off of LED are horribly green or yellow because in order to produce RED wavelengths, it comes at a design sacrifice of requiring greater power + cost. I’m still waiting for a truly incandescent equivalent LED bulb that doesn’t cost $20ea. I still haven’t found one. Lumens mean nothing if the color quality is crap. 7.5 Watts vs 60 Watts mean nothing if the bulb needs replacing every 2000hrs anyway. Besides, that 60W bulb put out 80% of that energy as heat... heat that my furnace doesn’t now have to pick up the slack for when I change all of the lights in my house. LED still doesn’t meet the standard of the prior Incandescent bulb. /rant."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jinkrk | How is Tesla already selling cars with hardware fully capable of self-driving when the technology does not even exist yet? | Technology | explainlikeimfive | {
"a_id": [
"ga7i151",
"ga7mkob",
"ga7jfrs",
"ga7y04t"
],
"text": [
"The hardware is pretty simple. Think about it. All you need is the camera and the motors. Many cars already have motorized steering and gas, some even brakes. A human could remote control a car with ease. That brain is really all we're missing. So, we slap the motors and cameras in, and we wait until we can program the brain as that is the only piece left.",
"What makes you think the self-driving technology doesn’t exist?",
"Think of it like a Kickstarter campaign. You pay now and they promise to deliver something to you in the future. I (perhaps foolishly) paid for full self-driving when I bought my Tesla a few years back. I just got a notice that they will upgrade my hardware to support the latest update that recognizes traffic lights and stop signs. Still not full self driving, but my point is, there are making (slow) progress.",
"The hard part about self-driving isn't the hardware but the software. Drive-by-wire where the controls aren't directly connected by mechanical linkages to the moving parts but instead have an electronic linkage isn't that hard to do, and fly-by-wire has been a thing in airplanes for decades. Putting a computer between the controls and the moving parts is pretty easy. Putting cameras and other sensors all around the car to monitor the car's surroundings also isn't hard to do. The hard part is putting in a control system that can take the input from the cameras and other sensors, figure out what's around the car, and controlling the moving parts. But that control system is software and can be upgraded."
],
"score": [
12,
9,
8,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
|
jinyvp | how does your PC distinguish between gaming music and your voice? | My friends and I are playing games online and I have them on discord, on a voice chat. Even if the game we were playing has background music on almost full volume, they still are only able to hear my own voice and basically nothing else from my side? | Technology | explainlikeimfive | {
"a_id": [
"ga7qx2p",
"ga7p8zx"
],
"text": [
"My understanding is Discord has a built in noise suppression software ([ URL_0 ](https:// URL_0 )) that uses machine learning algorithms to determine what noises to cancel out. To answer \"how\", we would need to get into machine learning and AI. In an attempt to keep it simple, the software uses untold amounts of data from across the userbase to recognize patterns. Using pattern recognition and other math wizardry, the software can determine which noises, captured by the mic, are \"background\" and which are your voice. This is determined by using several of the properties found within a recorded sound. As a rudimentary example, the volume of the sound (in comparison to distance from the mic) could be used. There are other methods using multiple mics, however, since you specified Discord and PC I believe the Discord software on your PC is the answer to your question.",
"Its a basic version of noise cancellation. A speaker and a microphone are functionally the same device. A signal sent to a speaker to create sound is the exact same signal the microphone would pick up and transmit when recurring the sound. So the computer know the sounds it's making, and exactly what that will look like when it picks it up in the microphone. What it does then is subtract that signal of from everything that picks up leaving just your voice."
],
"score": [
4,
3
],
"text_urls": [
[
"Krisp.ai",
"https://Krisp.ai"
],
[]
]
} | [
"url"
]
| [
"url"
]
|
jioxuz | In word processing software, why is the option to create a pdf file always so far removed from the regular 'save' option (e.g. somewhere on the print menu)? | edit: Thanks, everyone - this has all been perfectly insightful | Technology | explainlikeimfive | {
"a_id": [
"ga7qfq7",
"ga7qkjz"
],
"text": [
"It has mostly to do with software licensing and ownership. Adobe owned the PDF proprietary format until 2008, when it was released as an open standard. Other companies prefer you use their own proprietary formats so in their own self interest, make it not so convenient to publish to PDF, since in years past they would have to pay Adobe to read and write that format, and may still see Adobe as a competitor in document creation and management solutions.",
"Because it's not the default file type a word processor uses; typically using - .doc, .odt, .docx, .txt etc. PDF don't allow editing - they're like a Read Only File. Any PDF to WORD converter uses OCR and other techniques to create the Word Documents. But yes, it is a really cool idea for a quick save as PDF button. But it should make the user save the file before they export as a PDF, to avoid potential data loss."
],
"score": [
6,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
]
| [
"url"
]
|
jip3qc | How do "minerals/solid raw materials" become programmable? | I can't understand how electronics that are programmable are created. I understand how crafting works, but I don't get how we can make those "minerals/solid raw materials" do certain things. Like I get how programming works, but I don't get how we created this technology to allow programming. I would love someone to ELI5 from scratch (material) to lets say a computer. So the question is not how do we make with iron and gold a chip but rather: That chip what magic did we apply to allow us to code and do anything we want! I hope this is not too vague, if it is please tell me what I could explain better so I can get the answer I desire for! | Technology | explainlikeimfive | {
"a_id": [
"ga7sj04"
],
"text": [
"We are not programming iron and gold, we are using semiconductors, namely silicon, doped with other elements. Basically, we can take this silicon, and make it only conduct electricity along one path when a voltage is applied to a different part of it. This is called a transistor. Using a number of these transistors, we can create things called logic gates, and chaining together these logic gates, we can make a program."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
jip98r | How is it that, in a videocall (Skype, Zoom etc) my mic only pick up my voice and not the other person voice coming out the speakers? | Technology | explainlikeimfive | {
"a_id": [
"ga7s1gx"
],
"text": [
"Your computer can recognize the waveforms it's sending to the speakers, so when the microphone picks up those same waveforms. They get filtered out and aren't sent back to everyone else."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
]
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.