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Where is the "equal but opposite" force where gravity is concerned? | We all know that things with energy are gravitationally attracted to each other. We also know that every force has an equal but opposite reaction... Is this some special case where Newton's third law doesn't apply? Or are two bodies that are attracted to each other pushing away on the fabric of space-time or something?... | 16 | Newton's Third Law implies that every object that is pulled towards another object, in return also pulls that other object towards itself. Similarly, anything that pushes against an object also has the object push back with equal force.
Now with gravity, the Earth pulls us towards it. But in return, each of us also ex... | 29 |
Do photons have any appreciable impact on spacecraft outside the atmosphere? | I know that photons can be used in solar sails, and that they are technically able to propel objects, albeit very slowly. But is there any consideration for photons as they relate to, say, the ISS or some other vessel in outer space? Are there any adjustments made to flight trajectories due to photons over long periods... | 19 | Yup. Photon pressure applies not only a change of momentum on spacecraft but also a torque. Spacecraft need to be designed to carefully minimize the torque imposed by photon pressure and to have mechanisms to counteract those torques and trajectory changes. They may be small, but they are consistent, and that can be pr... | 12 |
CMV: The vegans are (mostly) right (especially about pork) | If you believe causing pain and sufering is wrong, obviously causing pain and suffering is wrong, especially to animals that have a deeper capacity to feel.
People have gut intuitions towards consumption of dogs because we understand them as sentient beings that can feel and think and pigs are even smarter. Vegans ar... | 40 | > People have gut intuitions towards consumption of dogs because we understand them as sentient beings that can feel and think and pigs are even smarter.
I think that's actually more of a historical development. Dogs and cats lived together with humans for a long time, because they were useful for humans to keep th... | 41 |
What is the most culinarily elaborate “dish” made by a nonhuman animal? | Whether it involves combining two separate foods, cooking the food, or preparing it some other way, what the most complicated transformation that an animal has made to its meal? | 32 | I'd argue honey bees producing honeydew honey. First juices of plants normally unsuitable for bees are extracted from leaves by other aphids and transformed into honeydew, a thick, dark, sticky secretion. Bees collect it and transform into honey, which they then seal in the honeycombs, alongside with larvae who can fee... | 29 |
[ATLA] Any idea what happens to Azula in the end? | I mean, from what I can tell she goes into hiding but does she ever reemerge / deal with her mental issues / find happiness?
| 43 | Spoilers for the comics ahead (specifically The Search)!
After losing the Agni-Kai and suffering her breakdown, Zuko had her taken to a mental care facility elsewhere in the Fire Nation. She was kept there under supervision for about a year before Zuko let her out to help him search for their mother. Unsurprisingly, t... | 35 |
[Batman] I'm an honest Gotham cop and I'm under immense pressure to close a case on a mid-level (non-superhuman) crook. Is there any way I can enlist Batman's help with this case without using Jim Gordon's spotlight thingie? | 433 | It depends; if he’s something like a crime boss it’s likely that another member of the bat family is already on the case. Hang around the scene of a crime for a bit for one of them to show up to collect evidence and coordinate with them. They can’t be everywhere at once and would likely cooperate with willing police ... | 299 | |
Is the sound on atom bomb videos real? | Like many of you I enjoy watching atom bomb videos on YouTube. However one thing strikes me as unreal: the sound. Usually the sound of the explosion is shown at the same time of the blast. However, the recordings are made from miles away, which lead me to believe that they are edited. I wonder: are these sound reco... | 18 | Yeah, that sucks. The sound is usually real, but the timing is adjusted for some inane reason. Before people started doing this on Youtube, one of the best things about seeing a nuclear blast in a movie or on tv was waiting for the sound, because it was stock footage and you always knew it was going to take a few secon... | 12 |
[DC/Marvel] Which superheroes are best able to handle natural disasters and how would they do it? | Storm and Thor from Marvel is an obvious one. But aside from them, who are some heroes who are best suited to handle things putting out wildfires, averting tidal waves or helping with civilian and property rescue? Some that come to mind are Flash, Green Lantern especially for rescue efforts. Would Mera be strong enough... | 51 | I don’t know if he has ever actually done it aside from situations where all the heroes turn out to help, but in any situation where normal rescue workers would be useful Multiple Man would be able to handle quite a bit of work. | 31 |
[Alien] What happens to elderly xenomorphs? | So let's assume this specific xenomorph is strong and smart enough to survive for a prolonged amount of time, there is already a queen in the hive so there's no use for them to grow into one, what would happen? | 244 | The strongest and smartest ones are turned into Praetorians by the Queen. Those would be the ones who survived that long. They protect the queen, act as generals and can replace the queen if she is killed. | 209 |
CMV: Libertarians should establish their own experimental society, to crash-test their ideology. | I believe that the truest test of the principles of liberarianism (by which I mean pro-capitalist libertarianism, anarcho-capitalism and objectivism influenced ideologies) would be if (sufficiently rich) libertarians and libertarian-owned corporations funded and built (or bought if possible) a small island and establis... | 111 | Where? All viable land is claimed, save for some weird null zones on the Croatia-Serbia border which would not exactly make a country. There's not really a place anarchists could build a society free from government involvement. | 52 |
[Death Note] Can the Death Note be pre-empted when it comes to a scheduled death? Is it possible to kill someone sooner and in a different manner to what has been written in a Note or does having your name in it make you effectively unkillable until the specified time and date and method? | 27 | Yes, it can. The rules specifically state that the Death Note cannot be used to prolong someone's life; if they have a knife in their chest and are hemorrhaging blood, you can't write "Tony will die next Tuesday of a pleasant opioid overdose" to save him.
This is just a variation on that rule. The Death Note kills; it... | 18 | |
Why is the presence of Cadmium in cigarettes a problem when foods such as carrots contain similar trace amounts? | I found one article says that the average cigarette contains 1.56 to 1.96 μg/cigarette. The same article shows (with a very strict p-value!) that cadmium blood concentrations are higher in smokers.
In another article, it says that control group wet carrots contains 4 μg/kg
Many grown foods contain trace amounts of ... | 18 | Likely something to do with it being easier to cross into the blood stream via the lungs rather than digestive tract.
A quick Google says about 6% of ingested cadmium is absorbed in the gastrointestinal tract. While the lungs absorb ~40-60% of inhaled cadmium. It can also be absorbed via the skin.
There are obvio... | 41 |
ELI5: What purpose does eye movement serve during REM-sleep? | 32 | It's more of a response to REM.
During REM sleep, the visual cortex of the brain is “awake,” just as it would be during an awake state.
Sleep researchers believe that the eyes may be working to focus on an
area “seen” in a dream, but more research needs to be done in this area.
People who are blind experience... | 30 | |
How do Computer Algebra Systems, like Wolfram Alpha, solve algebraic problems? | I've been working with mathematica and maple a lot over the last week, and I still don't understand how computers can interpret and solve algebraic equations, yielding closed form solutions. | 288 | It represents the equations and has rules for how to manipulate them.
For example, if you tell it "expand (x + 2)(x+3)" then it might:
1. Parse the expression into a tree representation
multiply
add
symbol("x")
number(2)
add
symbol("x")
number(... | 70 |
Why do we prefer to sleep in the dark? | I've always wondered this. | 188 | Humans are evolutionarily adapted to sleep at night (when it is dark) and be active during the day (when it is light). Chemicals that make you sleepy build up in your brain over the day until you go to sleep at night and your brain gets rid of them all.
There is another chemical as well which wakes you up and stimula... | 99 |
ELI5; How do Gatling guns/“miniguns” have such reliable accuracy? | With the very manner of how they fire bullets, guns like the M134 and GAU-8 for example must create a large amount of centrifugal force, which is still in motion while the bullets are traveling down the barrel. How do they fire accurately rather than with a spray area, as a result of centrifugals upon barrel exit? | 53 | > must create a large amount of centrifugal force
They don't for the simple fact that the bullets/shells are travelling at really high speeds so they spend almost 0 time in the barrel and so are barely affected by the fact that the barrel is rotating. | 103 |
Do we know how long dinosaurs lived? | I'm talking about each individual dinosaur, not the time period. Did T-Rex live for 10, 50, or 100 years? Do we have this information? | 108 | Yes, we do. For some.
Or at least we have an idea.
Animals tend to grow seasonally, with more growth in warmer weather and less in colder weather. This results in what are called "lines of arrested growth" or "LAGs" for short. As an analogy, you can think of them sort of like tree rings for animals.
Now, for some di... | 50 |
ELI5: Why is a small amount of inflation considered "good" for an economy? | I mean, it's pretty obvious why large amounts of inflation are bad. But it's much less intuitive why some amount of inflation is considered "good." Does that help money move around somehow? Or are people more motivated to spend because the value of their savings diminish over time? | 61 | Small amounts of inflation are good for the economy because it encourages investment. If you have a large sum of cash, it's losing value every day (slowly, but it's still happening). If you want to make the most out of your money, you'll recognize that you need to to put into an investment fund of some sort so your sto... | 66 |
What is the difference between "targeted relief" painkillers and the generic painkillers? | I saw an advert for Nurofen period pain targeted relief pain killers and I wondered what the difference was between that specific Nurofen tablet and the other plain version? From my knowledge, isn't there some sort of molecule in the tablet that will bind to a receptor in the brain to alleviate pain? How is the tablet ... | 72 | That's actually pretty controversial. Nurofen is just ibuprofen. Ibuprofen doesn't do anything specific for pain or discomfort associated with menstruation.
But the thing is, ibuprofen *has* been demonstrated to relieve pain associated with menstruation … just the same way it relieves most other types of pain. So it's... | 33 |
ELI5: How much of a cold or flu virus do you have to be exposed to in order to catch it? | As I sit on a train home from work in Australian winter, half the carriage is coughing and sneezing. My understanding is that, generally, cold/flu viruses spread either through the air and being inhaled into the nose/lungs, or by being left on a surface by contact and subsequently picked up by new contact and then pass... | 15 | In terms of "how much of a virus do you need" - we don't really know, in most cases. Some viruses, such as influenza or adenoviruses, only require 10 particles to cause infection. It depends on how the virus infects (it is harder to get infect through the skin than it is to be taken in as someone breathes, for example)... | 16 |
If half of the matter falling in to a black hole during Hawking Radiation emission are anti particles and half are their particle counterparts, why does it cause the black hole to shrink? | Why aren't the effects of particles and anti particles netted out? | 18 | There is a variety of misleading information in this thread.
To begin with, you are correct: the absorption of particles or antiparticles would increase the mass of a black hole.
Next: this whole description you are referencing is a description of one way of calculating the existence of Hawking radiation, but you sho... | 20 |
Is time quantized ? | We know that energy is quantized by the Planck constant.
There is such things also for time, or time is continuous ? | 20 | We don't know. We have no evidence of any discontinuity in time down to about 10^(-28) seconds. If time is not continuous, it will show up at shorter scales. It may also be that time is not a fundamental construct, and only emerges as an effective notion.
| 10 |
ELI5: When you make red hot metal hotter, why does it become white hot, rather than blue hot? | 25 | Color temperatures go red->orange->yellow->white->blue.
It could become blue hot if you mad it much much hotter. But in practice you can't make iron hot enough to be blue hot.
6500 K is "standard white" (color of sunlight).
You'd need to make it around 8000 K hot to be blue.
Iron **boils** at around 30... | 29 | |
ELI5: If the Sahara desert used to be a jungle. Is there fossil fuels here? if not why | 24 | Having a bunch of vegetation in the past isn't enough. You need to 1) have a bunch of vegetation, 2) that gets buried and sealed in before it rots, 3) with a porous rock that can hold the oil, 4) with a sealed rock above that that can trap it.
If any one of those things doesn't happen, you don't get an oil reservoir ... | 49 | |
If men are obligated to recognize any children they have, should't they have a say in abortion? | So this question popped up in a debate I had with a friend of mine about feminism. He was arguing for the rights of men and he asked me if forced fatherhood is fair when a man impregnates a woman and she decides to keep the child but he doesn't want it considering that he doesn't have a say over abortion.
&#x200... | 194 | With the way this is framed this isn't an abortion issue, but rather a child support issue. If the man does not want the child and the consequences of supporting it, then it is possible for the child to be born while still not forcing him to have to support it. The issue isn't so much, "should men have a say in abortio... | 225 |
ELI5:Why don't we like the taste of everything that's edible? | I mean from a survival view point it would be more logical to like everything; because it equals more food, which means more chances of survival. | 182 | Edible things have different nutritional values.
Early humans who thought everything was delicious spent their days eating dirt and grass. This was fun but did not provide the nutrients their bodies required so those people died off.
Early humans who thought meat and fruit were delicious were extra motivated to ga... | 126 |
Evolution of Galaxies that have no Super Massive Black Holes in their centers? | It's still fascinating to me that such a HUGE galaxy like the [A2261-BCG](http://www.nasa.gov/mission_pages/hubble/science/a2261-bcg.html), which is 10 times wider than our galaxy, does not have a Super Massive Black Hole (SMBH) in its center. Will it form a new SMBH under gravity or will it eventually ~~divide into sm... | 31 | Ooch, this is a tough topic. We don't actually know exactly how SMBHs form. While we know that galaxies tend to have mass concentrations in the centre, so it seems likely that having all that mass in a small space will give you an SMBH, the exact process is unknown, and why some galaxies have SMBHs and others don't is ... | 17 |
What does the term Linear Independence represent graphically? And what are the implications of two things being Linearly Independent? | 79 | Two vectors are linearly independent if they are not parallel.
Three vectors are linearly independent if they don't all lie in the same 2D plane.
Four vectors are linearly independent if they don't all lie in the same 3D "hyperplane."
... | 24 | |
ELI5: How does the International Space Station have enough oxygen for all the astronauts? | How does NASA calculate the amount required? What happens in case of a leak? Do they refuel it every trip there? If that is true how come we can't setup multiple ISSs on the way to reach further into space? | 48 | **How does NASA calculate the amount required?**
Decades of research by the Russians and Americans (Skylab / Salyut)
**What happens in case of a leak?**
They generate it on board from water and backup solid candles, also the ISS is pretty air tight. It has to be.
**how come we can't setup multiple ISSs on the way to ... | 17 |
How is it that radiation suits protect people? | Maybe this is TV magic and I don't know what a real suit looks like but it seems like people become immune to radiation when they put on these thin plastic suits. How is it that radiation can be so dangerous and yet so easily dealt with. | 31 | The radiation suits you typically see don't block a lot of radiation. To understand their purpose, you first need to know what happens in a nuclear incident or any other situation where radiation exposure is a risk.
Essentially, radiation is emitted by unstable particles that decay (the radioactive material). Normally... | 57 |
Can I make any solid into a liquid by adding sufficient heat? | I want to know if I can take ANY sort of substance that is in a solid form and turn it into a liquid with enough heat.
I do not want to burn the substance.
Some examples of the substances I am interested in are Collagen, PMMA (Poly(methyl methacrylate)), PA66 (Poly Amide 66).
For anyone curious, these are some polym... | 84 | Not necessarily.
Some substances at normal atmospheric pressure will skip the liquid phase and go straight to gas.
And example of this would be Carbon Dioxide. Solid Carbon Dioxide is dry ice and it doesn't become a liquid when you heat it up to room temperature. | 54 |
Why is zero multiplied by infinity not defined as zero? | 37 | Infinity isn't a number (you can't point to it on a number line), and since both things that you're multiplying have to be actual numbers, you can't multiply anything by infinity. In general, infinity is not a valid term to use in any "normal" math.
What you *can* do is take the **limit** of "0 * x" as x approaches i... | 86 | |
ELI5: Why is Africa always in a state of peril? | Maybe that title is a little imperfect, but I know how valuable Land and resources are, and I think Africa has a lot of that, but it always seems to be unevolved and always in disarray. Also , I know a little about most countries and continents, but not very much about Africa, why was it left out of my education. Thank... | 15 | Plus, the continent is really fragmented. The entire continent has almost no quality natural harbors (one in South Africa, a few on the Mediterranean, and that's it.) The coastlines tend to be rather jagged cliffs, which made it hard to catch up to commerce, back in the day.
Many small rivers bisecting the land, lar... | 11 |
Why does Bacillus thuringiensis produce a protein that is toxic to Lepidoptera? What does Bt need to kill caterpillars for? | 35 | *B. thuringiensis* can be present on basically any surface in a caterpillar’s environment, including those it eats. Delta endotoxins paralyse the insect digestive system causing it to starve to death, providing a delicious substrate for a primarily saprotrophic bacterium. | 29 | |
ELI5: Why do dogs lick people? | 97 | There could be several reasons.
* To show submission to someone they recognize as dominant over them
* To show intimacy with something else, which they learned from their mothers while young
* To gather information about you through sweat and other things your skin secretes
* You might taste really good
Lickin... | 84 | |
Is there any evidence of a liberal media bias in the united States? If so can anyone tell me why? | 95 | Here is the most highly cited journal article that directly addresses your question.
Watts, Domke, Shah, & Fan (1999). Elite cues and media bias in presidential campaigns - Explaining public perceptions of a liberal press. Communication Research 26(2)
Abstract: Public perception of a biased news media, particular... | 82 | |
When you donate blood, are you accelerating the depletion of valuable stem cells you will need as you age? | I was just thinking about this when I saw the blood bus today. I know blood cells come from marrow. Could losing a large amount of blood on a semi-regular basis deplete the stores you need to make more red and white blood cells in the future? | 24 | Red blood cells are manufactured in the bone marrow and are replaced every 100-120 days. Outside of some chronic disease, you have a infinite ability to manufacture them.
White blood cells, or leukocytes (there are 5 different kinds), are also manufactured in the bone marrow and are replaced every few days. You also h... | 17 |
ELI5: Private equity or hedge funds that buy successful brands and drive them to bankruptcy within a few years. What do they gain by doing this? | Just thinking about JCrew, Toys R Us, Payless, Sears, Neiman Marcus and more were all bought out by funds seemingly trying to bankrupt them. Isn't the point of buying a business trying to get them to succeed? | 124 | This isn't always the case but when that's the plan, it goes as follows:
- Borrow money and buyout the company.
- Have the company massively go into debt and use the money to pay yourself an enormous dividend.
- Use the dividend to pay back the money you (not the company) borrowed.
- The company i... | 131 |
Where does body heat originate? | I've been wrapping my brain around this and the best I can do is that the metabolizing of proteins and sugars during digestion must create energy that provides heat for the bloodstream to carry around. Is this correct?
If so, I'm thinking that blood gets warm near the digestive system but this doesn't make too much se... | 15 | Heat is a byproduct of inefficient conversion of energy. In most living organisms' cases the this takes form in the conversion of the chemical energy in metabolic substrates like carbohydrate, fatty acids and amino acids to the phosphodiester bond of ATP. This process is inherently inefficient due to several factors su... | 12 |
ELI5: Why do my teeth hurt when my drink is too cold? | 31 | The nerves in your mouth become numbed by the cold like if you put an ice pack on a bruise, but since your teeth are more important than a bruise your body freaks out and thinks that something bad happened because it is no longer receiving a signal from your numbed teeth so it tells you that it hurts so you will figure... | 39 | |
[Endgame] (spoilers) How did Thanos know | .
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,
,
,
,
,
,
,
How did he know how to use the Pym Particles? He was only able to go into the future because he got them from the Avengers in the past, correct? via the past Nebula? | 22 | Thanos was able to access all of 2023 Nebula's memories. She may have learned quite a bit working with Banner and Stark. Additionally, he likely has access to some of the best minds and technology in the galaxy. Also, there wasn't necessarily a 1:1 correlation between elapsed time for 2014 continuum and the 2023 contin... | 42 |
ELI5: Does the case of Warren Vs D.C. boil down to the police not having a duty to protect us? | 39 | They don't have a duty to provide services to individuals. So if the police fail to respond to your call, or don't prioritize properly...there's nothing you can sue for. Their duty is to the public at large, and there's no duty to respond to you specifically.
In practice that means if you call multiple times because s... | 24 | |
[Harry potter] why are wizards and witches auch elitist and racists? | 15 | In the past their people, a distinct minority in the human population, were heavily persecuted. This was during the medieval era. Despite being powerful, they still struggled to survive.
As a result, the wizards and witches isolated themselves, forming their own ethnic (for the lack of a better term,) enclaves, pre... | 18 | |
Why does earth rotate ? | Why does earth rotate ? | 2,689 | Planets form out of a protoplanetary disk, which is a collection of material that’s all orbiting the sun. This disk has some net angular momentum vector, usually pointing in the same direction as the angular moment vector of the solar system. Since angular momentum is conserved, when the disk coalesces into a planet, i... | 2,047 |
ELI5: How can cross eyed people still see straight? | 18 | Some do and others don't.
If adults become cross eyed they might very well get double vision. It's usually only if the cross is quite light that they don't.
In children it can depend. Some children with cross eyed will have one eye that will not be able to see in the center of their field of vision (where both eyes'v... | 14 | |
[the Silmarillion] Why did the Valar ask Eru to intervene against Ar-Pharazon's fleet instead of dealing with it themselves? | 32 | Because Men are children of Eru. Despite the fact that they were afraid that Numenor could ruin Valinor, they asked Eru because they did not want to directly kill humans or indeed any child of Ilúvatar by their own hands. It was basically a problem with too much ramifications.
Also, remember that Eru didn't just kill ... | 35 | |
[DBZ] So if almost dying makes a Saiyan double in strength, why wasn't future Gohan on a self harming sensu bean craze to stop the androids? | 146 | The problem with abusing that ability is that there's a high risk of accidentally killing yourself. The only time it's worth the risk is when you have an incredibly short time to become powerful enough to defeat an opponent who would be impossible to defeat otherwise and retreat is not an option, like with the fight ag... | 106 | |
ELI5: Why is there such a wide gap in the intelligence of homo sapiens and every other organism? | The answer I've been given was basically: GOD. I'm not convinced..... | 47 | Chimpanzees are actually pretty close to us. But here's the thing. Once we reached a certain level of intelligence, we adopted a way of life centered around intelligence -- notably the use of language, tools, and complex civilizations. Suddenly being intelligent was *even more valuable* because our societies were desig... | 43 |
Is it more energy efficient to leave the heater on low when nobody is home, or to heat it up from cold when you get back? | So this morning as I was the first to walk back into my freezing office after the holiday, I was reminded of an argument I used to have with my roommate when I lived in a drafty old house in upstate New York. We would both leave the house for one to two weeks every Christmas, turning the thermostat down to something l... | 306 | The amount of heat lost by an object to the environment is proportional to the temperature difference between the environment and the object.
So if the object is at 20C, while the environment is at freezing (0C), then the rate of heat loss will be twice as high than if the object was at 10C.
If you keep heating the h... | 202 |
Is the galaxy a mostly flat plane like it’s depicted in pictures? If so, why? | In most artistic depictions of the Milky Way galaxy, it’s illustrated as a roughly flat 2 dimensional plane. What I was wondering is if that’s really the case, or if solar bodies revolve “above” (relative to said 2D “plane”) and “below” the center of the Milky Way? | 41 | To add some numbers to the good answers here: our galaxy has some thickness to it, but it’s wider than it is thick by a factor of 10-50 depending on how you measure. Roughly the same relative thickness as a thin-crust pizza. | 51 |
[MCU] Which timeline would be the least unpleasant to live in had one of the villains succeeded in their goal? | For example:.
If Obadiah Stane killed Tony Stark at the end of Iron Man 1, would the long term repercussions have been better or worse than if the Project Insight helicarriers had successfully launched during Winter Soldier? Or if Ronan the Accuser had killed the Guardians of the Galaxy and purged Xandar with the Powe... | 75 | *Spider-Man: Homecoming*.
If Spider-Man hadn't stopped Toomes, he would've sold a few more weapons to street criminals in New York. Maybe there would've been a few more robberies before the Avengers or SHIELD stepped in. | 83 |
ELI5: How can someone call a phone number they heard on the radio and get "80% of their IRS debt completely gone!" | Are you in debt with the IRS? Do you have $20,000 or more in back taxes? Call this number for IRS relief! | 170 | Some of these businesses are scams, but some are legal and just charge for a service that anyone has access to.
For instance, people in a lot of debt to the IRS can make an "offer in compromise." They agree to pay a good chunk of their debt within a set time, based on their income and assets, and the IRS does not coll... | 91 |
Can butterflies remember being caterpillars? | During the metamorphosis of insects it seems their cellular structure is completely reorganised. How much of the memory of the individual survives this? For example, if you "trained" a caterpillar or conditioned it to respond in a certain way would the resulting imago remember this conditioning? | 15 | Yes, and it's actually quite amazing that it happens at all. The caterpillar's body breaks down to reorganize into it's adult form yet does retain memories. This was discovered using your example, conditioning. Caterpillars were conditioned to avoid a scent and remembered it as adults. However, it seems events are more... | 14 |
ELI5: How does simply observing a particle (like in the double slit experiment) change the way the particle interacts? | Like in this video: https://youtu.be/U7Z_TIw9InA
How does a particle "know" it's being observed, and why does it act differently when being observed? | 29 | To observe something you need to whack it with something or it needs to spit out something.
For example, for you to observe your fingers, you need to whack it with light to reflect into your eyeballs.
To observe your screen it needs to be spitting out light.
This is what they mean by "observe", whacking it with... | 16 |
ELI5: What does it mean to sing a song in a particular key? | 21 | **First and Foremost: The vast majority of people saying this have no idea what it means! Especially Singers.**
Notes are Frequencies. Doubling a Frequency results in a Note that sounds "kinda the same but higher", which is why it is treated as a higher version of a lower note. Example: 440Hz is an A, but so is 880, 1... | 38 | |
ELI5: Why do we give North Korea humanitarian aid instead of forcing them to give up? |
So, why? Why doesn't everybody just cut off them completely, forcing their government to "surrender" as it were, open their borders and join the rest of the world.
I mean, their situation ain't exactly been improving over the years [while giving humanitarian aid].
| 31 | If North Korea were to collapse, it would be the closest thing we've experienced to a refugee crisis from another planet. North Koreans are forced to live in a completely different reality, and China has absolutely zero interest in integrating them into Chinese society.
Providing humanitarian aid is a preventative mea... | 28 |
[Pokémon] Why do some pokémon not evolve? (Only have one "form"). And, is there any advantage to that? Or is it all disadvantage. Examples would be nice too. | In each generation there are pokémon that do not have an evolution. I'm thinking of pokemon like Taurus. Is there any in-game explanation for why some species don't evolve? (Bar them adding an evolution in a later game.) Also, for this question, I'm not counting mega-evolutions because I think those are really more aki... | 37 | Why are humans born looking like small adults? Frogs are born as tadpoles, that turn into frogs as they get older, but humans never change form. Why is that?
Answer that, and you'll find your answer. | 44 |
ELI5:Why were some very toxic substances formerly thought of as medicinal? | This question was inspired by [this](https://www.reddit.com/r/interestingasfuck/comments/3g7689/deadliest_rocks_in_the_world/) post, which included information on the rock [stibnite](https://en.wikipedia.org/wiki/Stibnite) which is toxic but was formerly used as medicine and material for utensils.
I understand that e... | 26 | Most of the "medicine" back then worked by trial and error. If your medicine "cured" the sickness by placebo effect without poisoning the patient that was a success (there is a reason most doctors had a seriously bad rep in the old days). | 15 |
ELI5: Why, sometimes, you dislike a song at first, but after hearing it a few more times you begin to like it. | 50 | Music is all about patterns and repetition, but just simple repetition is boring, so there is also change. So music sits on the boundary between predictable/boring, and chaotic/incomprehensible. This is something you will notice in almost all music, that it sets up a pattern, and then changes it before it becomes predi... | 46 | |
ELI5: Why are fights between players allowed in the NHL when it is very strongly prohibited in just about every other sport? | 53 | It's just part of the game. The refs do stop fights when they go to the ground or when it gets out of hand to prevent any real injuries occuring. The players aren't really fighting to hurt eachother. It's more to show the other team that certain things won't be tolerated. It can be strategic or just because emotions ar... | 43 | |
ELI5: Why can't I swallow twice in quick succession, without it being difficult? | 130 | It's because swallowing starts a chain reaction of muscle movements in the throat all the way down the digestive tract called peristalsis. So the top muscles in the throat have to wait until the adjacent muscles are ready to start again. It's like trying to start a "wave" at a sporting event when the person next to y... | 218 | |
CMV: School Lockdown Procedures actually makes students less safe. | As someone who grew up in the post-Columbine world and has always known school lockdown drills, there's some things that have always bugged me about them that I could never get past, and even as a child I knew some serious flaws that never made me feel safe with them:
1. The Standard Lockdown Procedure Relies On An Op... | 32 | What works for an individual doesn't work for a crowd. The objective is to keep as many people safe as possible, and that often means making the shooter's objectives as hard as possible, hence the practices.
Crowding up against the door doesn't stop a shooter from getting in, but it does make it impossible to shoot s... | 22 |
ELI5: Unbiased explanation of Critical Race Theory? | Most of the ones I found through the search were not ELI5 at all, like they didn't even make an attempt at explaining in a simple fashion. Some others were obviously biased. | 220 | Critical Race Theory is the theory that most, if not all, aspects of modern society have racism baked in, which is why it’s been so hard to get rid of racism.
For example, we tend to assume that our laws are written to be race-neutral, but critical race theorists point to the fact that people from different racial ba... | 515 |
Why do people keep dreaming about their old friends/relatives even though they're no longer in touch? | I keep dreaming about my childhood friend for years. I have not seen the guy for at least 6 years and even before that we went to different high schools, so we weren't in touch since elementary school. I finished university and still have dreams about him once a month. I don't consciously think about him, I don't wonde... | 32 | Because the stories of our dreams, are compiled from our memories, worries, concerns, etc.. **The only thing your brain has to use as content matter for dreams is what's already there.**
If you've seen it, experienced, or have ever thought about it, it's a possible inclusion.
Then, the more you worry about it, the ... | 10 |
ELI5: After eating spicy food, why does breathing-in cool my mouth, but breathing-out burns it more? | 23 | most spicy foods work by activating a receptor that reflects heat. Imagine if there is a thumb print machine and the thumb that opens it is heat, the spicy food has capsaicin which also has the same thumb print. Basically activating the sensor. When you breath in, the air in ambient which your body is used to. But when... | 12 | |
ELI5: how did radiation destroy machines in Chernobyl? | I remember hearing that everything from cameras to trucks stopped working because of the radiation, what's up with that? | 17 | You heard something wrong about the trucks then, those certainly didn't stop working. There's a graveyard of them because the metal became irradiated, it's not so much "they don't work" as they're now unsafe to be around because they are radioactive from induced radiation.
Only more sensitive stuff breaks - film in me... | 18 |
In animals like octopuses and cuttlefish that die shortly after mating, what is it that kills them? | In documentaries about cephalopods, sometimes footage is shown of octopuses and cuttlefish post-mating indicating that they die shortly afterwards. They usually look very disheveled, with their skin peeling off it looks as though they are literally disintegrating. What causes this, is it some sort of super fast aging p... | 3,987 | The trait you're looking for is called semelparity. A classic example is a marsupial mouse, which basically fucks its way into the grave. As it enters the mating season it starts producing a huge amount of the stress hormones adrenaline (epinephrine) and cortisol. These make fat stores more available for energy, reduce... | 2,533 |
ELI5: Do trees have a life span, or will they continue to grow if not damaged or diseased? | 13,043 | **Edited to correct stuff.**
Many trees can live for an exceptionally long time. The oldest known trees are over 5,000 years old.
Trees are an interesting case because, as they grow older, they also grow *faster*. This basically means that the older they get, they’re simply more and more likely to die of a disease o... | 8,275 | |
[Terminator 2] How do we clean up this mess? | So some idiots just crashed a tanker full of liquid nitrogen into the foundry where I work. I’ve hit the alarm and my colleagues and I have escaped from the spill, but that’s about 40,000 litres of liquid nitrogen sloshing around in there. Who do we call to handle that much liquid nitrogen and how will they go about cl... | 25 | You don't have to worry about cleaning the nitrogen up. Its going to warm up pretty quickly and boil off into nitrogen gas once it reaches a balmy −320 °F (yes minus 320). Then dissipate into the atmosphere which is 78% nitrogen anyway.
The only clean up is the tanker itself and the physical damage done. There will ... | 20 |
ELI5: How and why do almonds have a split directly down the middle? | I was eating some today and I didn't know why this was... | 34 | Almonds are seeds, almond seeds are dicots, meaning they have 2 cotyledons.
When you split the seed in half you are exposing each cotyledon
Therefore both sides of the almond are not completely joined | 19 |
ELI5: How do electronics with battery indicators "know" how much battery they have left? | My phone has a battery icon that shows a visual representation and a percentage of battery remaining. How does it tell how full the battery is? | 50 | Batteries voltage changes slightly as they discharge. A simple way is just to measure this voltage (like a battery tester). Smarter batteries, like laptop batteries, have micro-controllers built into them that allow the device to communicate with the battery. Charge is measured in Coulombs and battery capacity can be m... | 34 |
If the story of Adam and Eve were true, how fast would the population have to grow in order to reach 7 billion people in 6,000 years? | I'm an atheist* who ~~believes evolution is real~~ accepts evolution as fact. I'm just curious what the math would look like for my question.
Edit:
1.) Thank you for help everyone. This wasn't designed to be a religious debate. I just thought it was an interesting story problem for math that I don't understand.
2.) ... | 30 | 6000 years is roughly 300 generations. Using the premise that 2*x^3"00=7000000000, this gives a rate of 1.076 per person per generation.
Put in human terms, we multiply that by 2 to get the average fertility rate of 2.15, meaning each woman would need to have 2.15 children on average to attain this rate. The current ... | 148 |
CMV: I think people who get noticeable body modifications know what they are doing and shouldn't be surprised or shocked when they are viewed differently because of them. CMV |
_____
To start off, I don't personally judge people negatively because they decide to get body modifications, piercings, tattoos, very noticible plastic surgery. But I think that these people know what they are getting into when they make these decisions.
It is your right to modify your body how you wish but you ha... | 578 | I think everyone who get a significant body modification *expects* to be treated differently because of it.
However, i don't think anyone should *accept* that they are treated differently. It is a completely superficial aspect to judge someone for, same as hair-style, clothes or what have you. Albeit more permanent. | 193 |
[X-Men, Marvel Comics] How dire does a situation have to get for Charles Xavier to go out on the field with the X-Men. | 15 | I don't know if it necessarily needs to be a dire situation, just one that requires his specific skills. It doesn't have to be a fight, sometimes it can be some kind of diplomacy or communication. Sometimes the X-Men need to appear as a united front, and for that it can help to have the guy who runs the whole thing.
O... | 14 | |
ELI5: Why can't news stations (CNN, NBC, CBS) sue the President for defamation when he calls them fake news or says they don't cover certain stories? | 38 | First, it would be a poor public relations move -- it would make the media look petty and thin-skinned to attempt to sue the President over negative tweets. This would likely damage, rather than help, the media's credibility. This would play directly into the President's strategy of marginalizing and denigrating the me... | 49 | |
ELI5: What "sins" did Jesus "die for" exactly? What would have supposedly happened to us if he didn't? (Serious) | 118 | Christians believe that after Adam ate from the tree of knowledge of good and evil, that all humanity was fallen and carried a sin nature, even the most innocent of babies carries this with them (passed from father to their children). It's this nature that causes sin to be tempting. The only way to pay for sins is vi... | 71 | |
[Dragon Ball Z] How did Vegeta keep his sanity after becoming Majin? | 22 | Saiyans have a tremendous will, and Vegeta's will is extreme even by Saiyan standards. He's extremely focused on one thing: defeating his enemies. He's also extremely arrogant, and there was a part of him that just wouldn't let himself be controlled by an _inferior_ like that.
He allowed himself to be controlled when ... | 22 | |
If you break your bones to a point you need metal rods and bolts, after the bone heals do the metal implants make your bones more sturdy & less susceptible to breakage? | 40 | Nope. The metal won't break, so it is technically more sturdy there... but the attachment points through the bone weaken them quite a bit, leaving weaker points. To some degree time can fix that.
Modern implants get better and better but thin bones won't become stronger after drilling holes through them. They can even... | 45 | |
If Helium is so scarce, why are Helium balloons so common? | Also, if we stopped using it in balloons, would that make much of a difference in the long term? | 139 | It's not scarce yet, but the alarm is because there is only just so much in the earth and it is being used up fast, often just released into the air, where it relatively quickly floats to the top of the atmosphere and gradually gets propelled by the solar wind away from earth.
It's somewhat controversial as to exactly... | 108 |
[Cuphead] If Cuphead's soul belongs to the devil, then why does his ghost float upwards, with a halo? | 43 | He still needs to be judged. There's a Tom and Jerry episode where Tom dies and goes to heaven, only when he gets there the guy at the gate looks over his paperwork and gives Tom the bad news. Everyone's an angel until they're evaluated. | 104 | |
ELIF: What does the phrase "corporations are people" mean and why is it significant? | 15 | "Corporations are people" is a legal fiction (that's not a derogatory term, it's just the name we use for the concept). What that means is that it's something that isn't technically true, but legally we pretend it's true because it makes things easier. We do this so that we can apply existing laws to new scenarios th... | 17 | |
ELI5 how a jet engine works | I don't understand how jet engines work. It's awkward when I'm around people that are talking about jet engines - I just have to come up with an excuse to leave or just guess how they work.
Thanks for your help, webernet! | 29 | A gas turbine engine is a tube designed to take that air from the front (the intake), add fuel, burn it and the blow it out the back at a greater rate than it was sucked in, the result being called thrust.
In it's very simplest form it is a tube with 3 stages, with each stage performing a task, and each stage from f... | 16 |
What kinds of acids could damage a jacuzzi? | Are there any with innocuous household uses? | 2,372 | Chemist - There are lots of acids that could damage a jacuzzi, depending on what it's made of. There are specific interactions to watch out for, but as a general rule, higher concentrations cause more damage. Perhaps you could specify what you are doing?
There are a number of acids that you can get for household use:... | 719 |
ELI5: if a human embryo isn't viable, by what mechanism does the body decide to terminate? What is it that goes "this isn't working, scrap it"? | Cannot add a flair but I suppose this would come under Biology | 69 | A precise answer probably wouldn't be really eli5 but basically there will be some chemical signal if the embryo isn't viable on a cellular level. When cells die they release a lot of different chemicals that signal for other cells to recover and destroy the remnants. Also, when the embryo dies it stops secreting hormo... | 31 |
ELI5: Why is the unit circle divided into increments of 90 degrees (90, 180, 270, 360) and not based on 100? | I'm just genuinely curious as to why we separate it like that?
For example, 100 degrees would be the same as 90 based on 100 system and 400 degrees would be 360. | 18 | The Sumerians started with a base 6 numbering system. They studied circles for things like navigation and came up with 36 degrees for a circle (in base six, 36 is 100). Later the Greeks decided they wanted more degrees, but found the divisibly of 36 useful. Since they lacked the decimal point, they chose to make a cir... | 41 |
ELI5: What happanes to someone with only 1 citizenship who has that citizenship revoked? | Edit: For the people who say I should watch "The Terminal",
I already have, and I liked it. | 2,875 | They are considered "stateless." Countries will likely grant him certain residency statuses or asylum after they consider what exactly caused his citizenship to be revoked.
Statelessness due to political conflict and ethnic discrimination, particularly in central Africa, is actually a significant issue that burdens su... | 2,414 |
ELI5: why does any form of storage device (usb, hard drive) never have its advertised storage space available.. for eg 4 gb usb have only 3.81 available | 174 | Two things: formatting, and different definitions of MB, GB, etc.
Formatting isn't the drive manufacturer's fault. When you have any storage device you need to be able to store things in some ordered way so that you can retrieve them later. To make this possible your system writes a list of where each file will be ... | 103 | |
CMV: The theory of evolution and Christianity are incompatible | A couple of quick notes: I am going to use the term "believe in evolution" simply for convenience. Evolutionary theory is generally not considered something that you believe in, but since some Christians deny evolutionary theory they effectively don't believe in it. Also, I am going to be using Christianity as my refer... | 25 | > The Christian genesis story states that god created man in his current form
Actually, it doesn't. Nowhere does it provide a description of early man that suggests he looked just like the humans of today.
Secondly, let's stop for a moment and talk about what Christianity actually means. Christianity means bel... | 25 |
Cmv: Gentrification shouldn't be demonized | I am by no means married to this idea and would love to hear from different perspectives, but as it stands now, I don't believe gentrification should be demonized.
I live in a rural area but close enough to a major city to see how gentrification has turned a once desolate area into a thriving community with lots of n... | 20 | Do you think there is a difference between revitalization where you infuse capital while supporting the people and culture that already live there and gentrification where you put those people aside because f*** you I've got more money | 10 |
CMV: The concept of gender is irrelevant. | I'll start by laying out my thoughts and please correct me anywhere I am wrong. I know I have a lot to learn about this topic and I would really appreciate if someone could show me why and where my thinking is wrong if it is.
From what I understand: gender and sex are different. Sex is grouped into male, female, and s... | 81 | Just like doctors assign your sex depending on your genitals at birth, so too do you get assigned a gender and socialized as such at birth. Gender dysphoria comes from a misalignment with the *gender* assignment, not the sex assignment. No one is trying to change their sex, a trans man will continue to have the chromos... | 53 |
ELI5: Why do we have to raise breast cancer awareness? | I'm all for preventing breast cancer, but I'm pretty sure most people are aware of it by now. It's not some unknown problem that nobody knows about. | 24 | Women still die all the time because they ignored a painful lump in their breast until it was too late. Having a breast removed is sucky, but it's way better than being dead. The awareness is to encourage these women to get to their doctor before it's too late. | 19 |
[Lord of the Rings] Do the Uruk-Hai inherently know how to fight skillfully? | In the Two Towers, the Uruk Hai bred to attack Helm's Deep know battle formations, can wield crossbows, use siege engines, and are able to duel trained elves to the point where they can pretty much slaughter them.
Were they taught how to do all that, or do they have some sort of inherent knowledge about how to fight a... | 15 | Sounds like "Movie Version". IIRC, there are a couple really short scenes in the movies that show them doing some form of practice against each other... usually in the scenes showing them being bred. | 16 |
Can you actually create jobs? | Often times people will bring up how company x has created thousands of jobs, but they never include how many jobs were lost by company y because of company x out-competing them. Long-term is there good evidence that a company can create jobs (I'm sure in the short-term it's possible) or do things tend to normalize aft... | 22 | Not really, at least not beyond the natural rate of unemployment sustainably.
It's just a political talking point really.
Long run increases in the standard of living are created by destroying jobs if anything (productivity growth). "Job Creation" is only really desirable in a recession or when we are otherwise below... | 26 |
Can multiple exact same sounds played over each other produce a louder decibel output than the original sound? | 68 | This is an example of constructive or destructive interference. If the waves are in-phase, this is constructive interference. The intensities of the two waves will add up and create one much more intense wave.
If the two waves are out of phase, then destructive interference will be experienced. If we have destructive ... | 25 | |
[WH40K] What's the armament of the Phalanx? How many guns are we talking? | I mean, I know that it definitely has a ridiculous number of guns and my sources in the "Lexicanum" syndicate speak of "it's upper surface bristling with weapons and sensorium domes".
Looking at the [Phalanx] (https://i.imgur.com/Cd0X7tN.jpg) this is perhaps one of the most striking, intimidating and [beautiful] (htt... | 65 | The Phalanx is suspected by many scholars to be an original generation Starfort upon which the Ramillies class fortresses (the second picture is actually a Ramillies, not the Phalanx) were based. It is larger, has superior power systems and actually has its own propulsion, but follows the same basic structure and defen... | 24 |
[Overwatch] Since Reaper can see (and eat) souls and both Bastion and Zenyata drop soul orbs, does this mean that Zenyata is right and the robots DO have souls? | 44 | It's unknown what exactly reaper absorbs. Outside of gameplay, there is little to suggest that he has any connection to the supernatural. So until the lore surrounding reaper is further explained, there is no clear answer. | 31 | |
[Star Wars] What's to stop the newly-destroyed planet of Alderaan from re-coalescing into a similar-sized planet again in a similar orbit? | Bonus question: if nothing's stopping it from re-coalescing, how long would it take? | 178 | IIRC a significant part of the mass of Alderaan was thrown into hyperspace when the planet blew up, water and other gasses would be carried away by the solar wind... if the planet reformed it would just be a cold lifeless dwarfplanet at best.
RIP | 138 |
[Avatar the Last Airbender] How does Toph "see" attacks coming at her? | She can only see things if they're connected to the ground right? so how does she effectively dodge/counterattack a rock flying at her? | 86 | Though the vibrations in the ground, she can track where her opponents are standing and get a clue as to which earthbending move they're using against her, since she primarily fought against earthbenders and they heavily rely on footwork and solid contact with the ground. Similarly, she'd be able to hear and feel where... | 88 |
ELI5: If a computer only takes an input of 0s and 1s how does it know to expect an image as supposed to text? | I get that any symbol is usually 8 characters in binary and that pixels colors in an image range from 0-255 with 255 being 11111111 using binary But how does it actually determine to either look for a letter or a colored image by just using strings of 1s and 0s if that makes sense. | 32 | It doesn't. You can interpret the same binary data multiple ways. It's up to the program that's running what it does with the data, which is why you can open binary files in Notepad.
However, if the program is expecting data of a certain structure, it may fail if it sees data that doesn't fit that structure. A BMP fi... | 44 |
ELI5:why are the noses of rocket, shuttles, planes, missile(...) half spheres instead of spikes? | 5,612 | Blunt noses are fine if not preferable at low speeds because the airflow can start to move out of the way before it hits the aircraft. The air in front of the craft pushes on the air further ahead to allow for a smooth transition.
Supersonic travel does not have this. The air is 'notified' of the oncoming plane right ... | 5,764 |
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