[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Why doesn't dark matter clump into singularities?

With only some undergrad physics courses, I've asked a few cosmologists and particle physicists but could not get an answer and they suggested posting here.

Dark matter (as I understand it) is used (among other things) to explain the discrepancies between the rate of rotation of stars/galaxies near the edge of a cluster being observed as faster than prediction.

In order for this explanation to work, one must assume that a Dark matter "cloud" is relatively uniformly distributed over an area larger than the galaxy/cluster.  The explanations I've read about dark matter consistently mention its uniform distribution.

However, why would such a massive particle stay uniformly distributed?

Should not even the slightest irregularities (even the gravitational irregularities of the stars themselves) cause clumping of the dark matter?

Since dark matter is not affected by electromagnetic forces, as it clumps there is nothing to stop it from keep clumping (unlike stars/matter which have electromagnetic repulsion).

Therefore, why wouldn't all dark matter eventually clump into a singularities, eventually coalescing into a single massive singularity?

[Assistant]
First of all, dark matter is clumped, just not into compact bodies like planets and stars and black holes.  It would only be uniform over galactic distance scales - one of the signatures of dark matter searches are looking for are effects it may have on the sun via clumping in the core.

The reason you don't expect many dark matter singularities is that in order to get a cloud to collapse into a dense body, you have to have some mechanism to redistribute and radiate away momentum on some fast enough timescale.  If the dark matter particles only interact sufficiently weakly with one-another, you won't get this process to happen fast enough for the dark matter to settle into compact objects compared to the lifetime of the universe.  If you just have particles and gravity, then they zip past eachother in lots of fun and intricate ways, but they won't in general undergo collapse unless there's something that lets them get rid of their relative kinetic energy.

It's easier to think about in the limit of two bodies interacting only gravitationally: there are no solutions that involve collapse!  They either stay bound and orbit eachother (maybe even move through eachother - keep in mind we're saying *only* gravity for this thought experiment) or they have enough energy to escape - to get them to collapse to one spot they have to do something else besides gravity.  You need some kind of drag force.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5:why are horses put down if they break a leg while other animals are looked after?

[Assistant] Horses legs, compared to the rest of their body are lighter, for speed, so when they break, a lot of times they shatter. When that happens, it's almost impossible to repair. The bones actually bends before it breaks (plastic deformation) so even if you tried to repair it, it would be bent. There is very little soft tissue  there, so a break usually is an open fracture. Living tissue needs blood, and in a open fracture the blood supply is damaged. They need all four legs to support in excess of 1000 lbs, so if they try to compensate for healing, they can end up with laminitis. You can't use a sling to support the leg, because they will get sling sores, and the pressure from the sling can damage the intestinal tract. There's no way to get a horse to lie down for weeks, impossible, and even if you could, they would get pneumonia.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why is haggling commonplace at the car dealership but not at other stores?

[Assistant]
Large ticket items like this are usually where the most negotiating happens. Same as buying a house, boat or RV. The sales model of dealerships lends itself to negotiation.

Pricing for smaller ticket items can sometimes be negotiated too: things like furniture and stuff. You can negotiate for anything but the roadblock is often going to be that you arent talking to someone who has the authority to make a price change and the fact that its not likely a profitable sales model to negotiate for 30 minutes over cheaper goods.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Is it possible for there to simultaneously be no rain everywhere in the world?

Follow-up question: Is it also possible for it to simultaneously rain everywhere?

[Assistant]
Like most physical problems the funnest way to deal with them is the extremes.

When it comes to not raining yes it is absolutely possible for there to be a moment in which it is not raining anywhere in the world.

However the follow up question is different...  If literally cannot be raining everywhere on the world at any given time because of the north and south poles.  Interestingly the north pole - very occasionally - gets above freezing so you could have rain falling.  The south pole is much colder however.  The highest temperature ever recorded there was negative 12 degrees Celsius.  Thus it couldn't rain... only snow.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5:IF I give a bank enough time, could I withdraw 1 Million in cash from them?

[Assistant]
Yes you could.

For large sums like that, which they might not have on hand, you would have to tell them in advance so that you could pick it up.

They don't 'legally' have to do anything. Their obligations to you are determined by the contract you signed when you opened the account.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why does Ron Paul get virtually no media coverage and support from conservative news networks?

I'm from New Zealand and have been semi-following the bid for the republican nomination. It just seems odd to me that Ron Paul, who appears to be the most consistent candidate in terms of policy and support gets slammed in the media.

[Assistant]
Ron Paul is unelectable to the presidential office. He's too extreme, and if he was ever nominated to the Republican ticket, he would lose all the swing voters. In American politics, swing voters are probably the most important demographic to win. Paul cannot win them - so Paul will lose.

Ron Paul is consistent, yes, but to many Republicans, Paul is far too weak in terms of foreign policy. Traditionally the GOP has been about strong military. Paul is the opposite. Paul wants to go back into ~~isolationism~~ Non-interventionalism. This is in direct opposition to the GOP platform and a significant portion of American Conservatives.

Finally, Paul is known to us Americans as a "Libertarian". This means he's in the left political wing in terms of social policy but in the right wing in terms of economic policy. In contrast, the GOP and the average conservative is in the right of both social and economic policy. This means Paul will have little to no support from the Social Conservatives, a large and influential segment of the Republican Party.

So let's review:

1. Paul loses the swing voters (too extreme)

2. Paul loses the base social conservatives (too liberal)

3. Therefore Paul will most likely lose any general election, and will most likely lose the primary.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Back To The Future] Did Marty's siblings witness their bodies fading away as they did in the photograph?

After Marty stops his parents from getting together the first clue that his past is changing is an image of his older brother fading away in a photograph. Later, when his brother and sister have both vanished, we see Marty's hand fading away before his eyes. Does that mean that in 1985 both his brother and sister experienced the horror of slowly vanishing? Did other people see this? What about other changes to newspapers and photos? Was everyone in 1985 Hill Valley freaking out, witnessing things and people around them slowing vanishing or changing?

[Assistant]
No, they just didn't exist anymore.

In Back to the Future, people fade from existence once they no longer have the ability to prevent whatever time change that altered their past.  That's why Marty is the last to go -- he's the one who is actually in 1955.

For Marty's older siblings, they were living as normal until the moment Marty went back.  At that point, their fate is out of their hands.  Whatever Marty does in 1955 will affect them before they're even born.  They don't have a time machine, they don't have any way to influence Marty or change the events of the past.  The exact alterations to the photograph are some quirk of time travel that we don't really understand, but Marty's brother wasn't walking around without a head.  Regardless, if Marty succeeds, then his brother and sister will have always existed.  If he fails in getting his parents together, then his brother and sister will have never existed.

Think about it like this -- Marty sticks around until the pivotal moment of the Enchantment Under the Sea dance.  As long as George kisses Lorraine while "Earth Angel" is playing, Marty's okay.  He isn't going to disappear as long as he has the ability to make that happen.  He only starts to fade out when George is gonna miss his chance.  But for his brother and sister, they have zero ability to make 1955 George kiss Lorraine.  That's why they start to fade as soon as Marty pushed George out from in front of the car.

In 2015, Old Biff travels back to give a sports almanac to his 1955 self.  Old Biff experiences no problems until he returns to 2015.  At that point, he starts having health issues.  They get worse as he moves away from the Delorean.  That's because his ability to go back to 1955 and fix his own past is going away.  He doesn't fade out until Marty and Doc get back in the time machine and leave.  At that point, Old Biff's ability to repair his past is gone completely, and he disappears.

The changes Old Biff made don't affect Doc and Marty, because they've still got a time machine.  It's not too late for them to fix the changes.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: How do bats circulatory systems tolerate being upside down for such long periods?

As far as I know, other mammals (I think theyre mammals) cant tolerate this and the pooling of blood in the brain causes issues.

[Assistant]
The quick answer is that Bats don't weigh enough for gravity to affect it's blood flow.
This includes the largest species, the black flying fox - it only weighs 1.1Kg.

As a human, we have litres of blood to move around so we have quite large arteries to help with that - so when we hang upside down there is alot of blood for gravity to affect, and an effective highway for blood to migrate towards our heads.

As a bat, they don't have nearly as much blood and their arteries are considerably smaller, so when they hang upside down they aren't affected in the same way.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[LOTR] Did the Elves suppress Men's innovation in the Third Age?

Its often asked why in the Third Age Men never get past medieval technology but it's also well known that the Elves want to preserve the world as it is. Could it be that the Elves selfishly advised Men into behavior that doesn't favor innovation and once the Elves left in the Fourth Age, Men were free to be inventive?

[Assistant]
No, that would require waaaaay too much interaction with Men than the Elves left in Middle Earth by that point wanted to have.

The Third Age was very much a Dark Age in general for the world of Men. Consider that the only major kingdoms anywhere near Erebor to begin with were refugee states founded by the handful of Numenoreans to escape the wrath of the Valar, and in addition to the depredations and destruction caused by Sauron directly and his minions (chiefly Angmar), as well as the wars fought against easterlings and southrons, a huge plague swept through Arnor and Gondor and their surroundings only a century or so before the events of LOTR. The whole back half of the Third Age was about the Realms of Men getting the ever-loving shit kicked out of them, while Elves continued to turn inward and retreat from the world.

There's not going to be much innovation at all going on in such a world.

Now, after the final defeat of Sauron and the creation of the Reunited Kingdom, you've finally got a growing population and the political stability needed for some good, solid technological and sociological progress.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[S.T.A.L.K.E.R] Is the Zone a net boon or curse for Ukraine and neighboring states?

The Zone is clearly an excellent source of fascinating specimens and research data that would be of great value to outside businesses, institutes, wealthy individuals, and states. One can only dream of the incredible inventions and technology being developed from the scientific bounty of the Zone.

However, I imagine that the mutated horrors that populate the Zone are a grave danger to the populace. Remember the terror caused by that wild bloodsucker police shot almost 30km from the quarantine line?  The steady flow of desperate men with empty pockets and full holsters could be dangerous in the future. Seems like the Zone might also be a tempting target for a Russian or American "humanitarian intervention."

I don't follow the news much these days, but I've heard intriguing rumors. Can anyone shed light on the political/social/economic impact the Zone has had both locally and on the world stage?

[Assistant]
You know how in the late 20th century countries with oil attracted all kinds of religious fundamentalists and iron-fisted dictators and "democratic liberation" from world powers? And how people living near oil operations reported all kinds of problems with their water and general health problems? The Zone is like that time a thousand.

The best part is what was revealed in the Strugatsky account. Countries drop "research teams" in the Zone without local consent. The local agencies who are supposed to guard its boundary just take bribes and look the other way because *everybody* is going into the Zone to bring stuff out. The tech coming out of there is being used to power cars and supposedly solve the energy crisis, so the media *loves* praising world powers and talking about cool science-y stories about the Zone, and completely ignores any real news from there.

No *official* mention of weapons tech coming out of the Zone, but it's happening. It's illegal under the amended Geneva Convention, of course. The Strugatskys mention something that sounds a lot like a research facility being melted by gray goo. If you read the reports on what tech from the Zone looks like, it's obvious that it's worse than plutonium.

There are rumors that people living near the Zone get rounded up by the government and detained in a holding facility just outside of it, even if they were smart enough to move out years ago. Supposedly it's to protect the general population from some kind of imaginary "contamination" attached to anyone who was near the Zone during the Visitation. Entering the Zone is a death sentence, and being unlucky enough to live near it is almost as bad.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: What is the difference between FLAC and WAV audio files?

[Assistant]
WAV is uncompressed, the raw data.

FLAC is lossless compression, it stores the raw data more efficiency (smaller file size), think of it like a ZIP file.

MP3 is lossy compression, it loses some data (high and low notes are mostly effected) in exchange for a much smaller file size.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: How does hydroplaning work?

[Assistant]
Generally fluids have to go somewhere when displaced - when you dive into a pool, you have to move all the water that used to be where you dived into. This takes a little bit of time and energy, which is why there's a shock when you break the surface of the water and slow down significantly - you're pushing all the water away.

Your average car tire has treads which are engineered to wick water away from between the tire and the road - when moving at speed on a significantly wet surface, the tires are pushing forward into a surface that has a layer of water on it and they need to wick away the water that goes between the tire and road in order to maintain traction. Some tires do this very well and some do not (slicks).

As soon as the tire is unable to clear the water faster than water goes under the tire, the water pushes the tire off the ground and you lose traction, i.e. hydroplaning. Cars are pretty heavy so you need to be going pretty fast in pretty wet conditions generally for this to happen.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Can you break or bend the rules of the "Fire Triangle"?

In school, we were taught about the Fire Triangle; the three requirements for fire, those being fuel, heat, and oxygen.  Being that this was middle school (I think) I assume this was a dumbed down or simplistic version.  What are some ways these rules can be subverted?  Is it possible to replace oxygen with another gas, or perhaps start a fire without heat?

[Assistant]
To varying degrees, yes!

As was noted in another thread a few days ago, anything combusted by oxygen will still react with fluorine (and the original fuel will as well) in what is essentially a fire. Such environments are... uncommon, however.

Heat is an inescapable requirement, but the amount required can be extraordinarily low. Hypergolic combustion occurs when two chemicals burn simply by being in contact with one another, and the temperatures at which this reaction still occurs is very low indeed. Outside of a rocket or a lab you probably won't find these substances though.

I think the fire triangle is "technically" an over simplification, but for 99.99999% of the population in 99.99999999% of all situations, it is an accurate depiction of what is required for a fire.

Edit: it should be noted that oxygen can be provided by an oxidizing agent as well as free oxygen. Probably the most common occurrence of this is in bullets : along with gunpowder, an oxidizing agent allows the shot to be fired underwater or even in a vacuum.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Marvel] What does "peak human" mean in terms of Captain America?

I remember reading that the super serum boosted all of Steve's attributes to "peak human" levels. I can see how it applies to physical traits like strength, speed, stamina, etc. but what about mental? Intelligence was on the list where I read it, but surely Steve's intelligence cannot compare to the likes of Tony Stark,Hank Pym, and other humans.

Also, regarding his physical attributes, does this mean even after a billion years of evolution Steve will still eclipse other humans?

[Assistant]
Intelligence doesn't really equate to knowledge, more like comprehension and retention. Why he doesn't do the same super sciency stuff as other intelligent characters is simple, he isn't interested in it. Even for someone of a Genius IQ, learning something that doesn't interest them is difficult. Which is why somone like Hank Pym isn't good at everything ever, he has particular areas of expertise. Captain America's particular area of expertise are things like tactics, leadership, and probably physics judging by how well he can ricochet that shield. Captain America is a genius, he just doesn't apply it like other smart characters.

The physical portion is a bit murkier, even more so with how murky evolution is with the marvel universe. When it's said Captain America is peak human, it means he's as physically strong, fast, ect. as any human could possibly be currently. So sure, humans might evolve their way past Captain America, though that would be a lot of evolution for humanity's base parameters to be higher then marvel's peak.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Kim Possible] Who does Kim work for? Why is a teenager allowed to go on such dangerous missions even before she has her drivers licence?

[Assistant] Kim works for herself. She set up a website to advertise for babysitting gigs and then her first call was dealing with a disaster. After discovering that her ability to deal with pressure, combined with her athletic and cheerleading skills helped her deal with extraordinary circumstances, she continued in that line of work relying on word of mouth.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Supernatural] Why aren't the boys better actors?

Kind of an obscure question, but: in the Season 6 episode *The French Mistake*, there's a gag where Sam and Dean have to pretend to be actors and fail miserably. They act woodenly, constantly forget lines, end up reading all their lines off pieces of paper and ruining every single take that day.

These are guys who's day job involves pretending to be other people (FBI agents etc), and memorizing complex incantations (Dean actually re-writes a ritual from memory he only saw once in the same episode!) Shouldn't their skills be extremely transferable to a  TV set?

[Assistant]
It depends on the nature of the set.

Incantations are recited, not delivered; you don't normally have to act while giving them. Meanwhile, most of their "acting" - their impersonation - is done on an improvisational level, constantly adapting to the reactions of the people they're trying to fool.

Forcing them to stick to a script stifled their improvisational skills, leaving them off balance and unable to properly inhabit their characters. Hence, wooden line readings and general uncertainty.

They probably should have done better at learning their lines, but there were two big differences from memorising incantations - firstly, most incantations are written to be chanted, giving them a natural rhythm and tendency towards repetition, both of which help when trying to remember then; and secondly, when they're learning incantations they know that it's basically life or death, adding focus to their efforts, while it is quite simply impossible for them to take the script that seriously, leading to them unconsciously half-assing it.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: What's the"resolution" of film photography?

[Assistant]
There isnt a specific resolution. It depends on two main physical characteristics of the film itself - the size of the film and the speed of the film - as well as the way that film is exposed.

The first physical aspect is what format of film youre using - theres small, like a standard 35mm film that your average point-and-shoot camera would take; medium, which takes a range of film sizes (popularly 120mm); and large, which takes film sheets with dimensions of several inches.

The second physical aspect is the speed of the film, or how long it takes for light to affect the film; the higher the speed, the lower the quality of the image. This speed references the density of the films grain- a higher speed has a larger grain, and thus the image is a lower quality, because a finer grain has the ability to capture more detail. This is probably the most direct similarity to digital photography and resolution, because the grains are essentially like pixels; more pixels = more details.

The combination of film size and film speed essentially boils down to how many grains of film the image is being captured on - a large format film with a low speed will capture the most detail, because it has the most crystal to capture the details with.

These physical factors are then combined with the way the film is shot - specifically, the length of exposure - because again, the longer the film is exposed to light, the more time that light has to affect the film in greater detail.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Star Wars] When Anakin was consulting with Yoda about his Padme dying vision, why didn't Yoda ask follow up questions?

Anakin might have been talking about another Jedi or someone else important and isn't it just good practice to investigate if there's reason to believe someone is in danger? Always in motion the future is so isn't it possible that the death could be prevented?

[Assistant]
Yoda didn't really care all that much about Anakin's problems; he offered guidance where he could.

"Always in motion, the future is" just refers to the passing of time; the future always changes because the future will always become *now*. Anakin's Force dreams could tell him the will of the Force; he tried to break it, but you don't mess with the Force.

Yoda knew that whoever it was that Anakin wanted to save was screwed anyways; a lover, Obi-Wan, someone important to Anakin. They were a goner. You can't prevent the Force from carrying out its will. Anakin saw the Force's next move, he told Yoda about it, Yoda didn't bother doing a thing because he knew that the Force is absolute. The Jedi carry out the will of the Force, they don't change it on the fundamental level (like Anakin wanted to do).


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Eli5: How is engine power different from torque qualitatively? And why is a diesel engine better than petrol at low rpms?

Eli20 works as well!

[Assistant]
torque = force but rotational

rpm = speed but rotational

power = speed \* force = work per unit time = (force\*distance) per unit time = torque \* rpm

You can have all the torque you want from an engine if you're willing to cope with imperceptible motion. Similarly you can have all the speed you want if you can cope with it stopping when you look at it the wrong way. This makes them sound useless but there are actually uses for the extreme ends of both of those. A projector can use high speed, but doesn't need to be all that strong to move the film to produce a moving image.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5 why is the temperature one number but often the "feels like" is a different number!

At least in the mid west it happens fairly often. Right now its 5 degrees but "feels like" -8. Also how is that determined? To me "feels like" isn't really scientific...

EDIT that wasn't suppose to be an exclamation point in the title.

[Assistant]
The "feels like" includes a wind-chill factor.

We all sweat, and when our sweat comes into contact with the air, it evaporates. The process of evaporation causes the area surrounding the sweat - our skin - to cool down. If there's a wind blowing, then the air that now contains our evaporated sweat will be carried away from us by the wind, and replaced with fresh, dry air - which means more sweat can be evaporated, and more heat taken out of our body. This happens regardless of the temperature of either us or the air - although the temperature will be one factor that determines how much cooler we will feel.

The wind-chill factor is a calculation of how many degrees colder our skin will become as a result of this process.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why is there no cure for the common cold?

[Assistant] The common cold is a constantly mutating virus. There are many strains of it, and the reason it is constantly caught many times over by the same individual is because you are catching a different strain every time. It is much the same reason as why a new flu vaccine is needed every year.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] CMV: "Islamophobia" is a highly loaded word that is often improperly used to deter criticism of harmful cultural practices.

[Assistant]
Let's clear some stuff up:

**Islamophobia:** Trying to disallow people from building a mosque in your town because you fear that "those people" will use it as a toehold to establish a terrorist training camp.

**Not Islamophobia:** Trying to disallow people from setting up an enclave inside your town wherein laws against sexual abuse don't apply or can't be enforced.

**Islamophobia:** Using Arabic terms (such as "dhimmi") as slurs for Western politicians whose policies you disapprove of. Claiming that a non-Muslim politician such as Barack Obama is a secret Muslim because you don't approve of his policies.

**Not Islamophobia:** Investigating financial connections between the Saudi royals and Western politicians.

**Islamophobia:** Treating a crime as "terrorism" if it is committed by Muslims and "ordinary crime" if it is committed by Christians or atheists or Jews or Scientologists or something.

**Not Islamophobia:** Taking explicit threats from terrorist groups (including those who identify as Muslim) seriously and investigating in response.

**Islamophobia:** Using anti-Muslim rhetoric to justify crimes against humanity, such as torture and conspiracy to commit torture.

**Not Islamophobia:** Noticing that ISIS hasn't yet been around (as an entity occupying territory and claiming statehood) as long as the Bush Administration was, and it's already getting *way* up there in the crimes-against-humanity department.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: How is it that, say, Lebron James and Danny DeVito are considered to be the same species despite being so physically different, but a brown bear and a black bear are considered to be completely different species despite being so physically similar?

[Assistant]
Defining species is a tricky and often subjective part of the various scientific disciplines which interact with it.

Some will say that the viability of offspring among groups of sexually reproducing organisms is a good test, and it does offer some utility, but it is by no means exhaustive. Polar bears and grizzley bears are a famous example of two types of organisms which are generally considered different species, but which occasionally mate in wild, producing reproductively viable offspring. Mosquitos can become behaviorally different enough that they don't know how to entice mates between groups and they are often considered diferent species despite the reproductive viability of offspring created by human intervention.

Archaeological evidence throws in additional wrinkles. Although we generally consider domesticated dogs to all be of the same species, if the only record we had of them were bones (ignoring DNA) we would likely consider great danes to be a completely different species from pugs. This problem rears its head when examining hominids which co-existed as it is difficult to say if these are divergent groups of one species or two separate species; some the scientists involved usually prefer the latter result as it is more prestigeous to discover a new species than just a member of an existing one.

Non-sexual reproducers add additional problems as the detectable differences in species has a lot to do with how they look and how they behave around other similar organisms.

DNA has added an additional tool which allows us to statistically compare gene differences between two organisms. This has been done to create base-lines of what we already feel are different species and how much their genetics deviate from each other and then we can use this to compare other similar appearing organisms, both those we can observe today and those from the relatively recent past. If they are too similar, it is a strong mark against it being a different species and if they are quite different, it is a strong mark in favor of it.

In the end, the idea of 'species' is only important when it is useful in describing our world. It's useful to differentiate between predators and prey, or the reproductive viability of populations of organisms, or tracking forms of organism through the archaeological record. It is important to recognize that the walls we put up around species are not entirely sound and if we aren't careful we can make mistakes, but in so far that they are useful tools for helping us to grapple with the complexity of the world, they are just fine.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[ASOIAF / GoT] Why are the Unsullied castrated so young?

The Unsullied are said to be the most ferocious warriors in the planet, both from their iron will and from their physical prowess. Yet they're all castrated at an early age (the GoT wiki says they're castrated at age 5), isn't this counterproductive?

Sure, I understand they're castrated so they never develop distracting carnal desires, but doesn't gelding them early also messes up their development because of the complete lack of testosterone?

You are essentially creating a group of castrati who will never develop the muscle mass they normally would and training them to be soldiers.

Wouldn't it make more sense to castrate them **after** puberty? Once their growth is at least somewhat done and they can then just train to maintain their muscle mass.

[Assistant]
A eunuch who is cut young will never have the brute strength of one of your Westerosi knights, this is true. A bull is strong as well, but bulls die every day in the fighting pits. A girl of nine killed one not three days past in Jothiel's Pit. The Unsullied have something better than strength, tell her. They have discipline. We fight in the fashion of the Old Empire, yes. They are the lockstep legions of Old Ghis come again, absolutely obedient, absolutely loyal, and utterly without fear.
 Kraznys mo Nakloz to Missandei and Daenerys Targaryen

It helps to condition them to make them "absolutely obedient, absolutely loyal, and utterly without fear"


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why does cracking your knuckles/back/neck feel good?

[Assistant] Usually when you crack your joints you relieve the pressure that was building over the cartilage, which mostly happen because your joints aren't that tight anymore as they were when you were a kid, so they start "slipping" to a position where they were not actually supposed to be, but are not entirely wrong (as in a dislocation, which usually hurts). Pressure, most of the times, is not painful, just unsettling, so when you release it you get that pleasury feel.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [MCU] How might things have played out differently had Tony Stark decided to go along with Agent Coulson's plan to hide his identity as Iron Man?

[Assistant]
Stark chose to go without a secret identity because (1) he's an egotist who likes attention and (2) he's already a famous billionaire. Being known as a superhero isn't going to prevent him from enjoying his usual lifestyle. If he chose differently he'd have to be a slightly different person, at least from that point onward.

A humbler, more cautious Tony Stark is quicker to become an asset to Nick Fury. Iron Man starts being deployed as an extra-governmental asset, which discourages Senator Stern from siezing the technology. Meanwhile the public buys the cover story that Iron Man is Stark's bodyguard. They speculate that it's either Rhodey or Happy.

Whiplash attacks Happy in Monaco. Stark ^develops briefcase armor and gives one to Happy, Pepper, and Rhodey.

Rhodey is present when the Hammer drones go on a rampage. He fights as best as he can using his briefcase armor but is badly injured. In the aftermatch Stark begins designing a tougher, much more heavily-armed suit.

Iron Man is present for the events of *The Incredible Hulk.* He arrives at the university with a special suit. However, this version of the Hulkbuster armor was built without Dr. Banner's involvement and lacks the quick-repair capabilities of the suit from the original timeline. It is defeated in time for the helicopter gunships to arrive. Stark sees the Hulk shield Betty.

Blonsky still becomes the Abomination. Iron Man arrives too late for the fight, but just in time to take the Hulk to safety. Banner recuperates in a Stark safehouse, where he learns to control his transformations.

Iron Man and the Hulk are present for the events of *Thor.* Now good friends, they compete to lift Mjolnir. They fight the Destroyer and lose. Then Thor regains his worthiness. The experience causes Stark to begin researching Asgardian magitek.

Captain America wakes up to an established team of superheroes. The events of *The Avengers* still take place, but with less bickering. The nuke never gets launched. Instead, Stark flies through the portal and ejects his arc reactor on the other side.

*Iron Man 3* happens very differently. Tony has less PTSD from the Battle of New York. He never challenges the terrorists to attack him where he lives. The *Extremis* threat is crushed by the full weight of the Avengers. Tony never blows up his suits in a big if futile gesture.

Steve tells Tony about his parents after the events of *Winter Soldier.* Their fight in *Civil War* never happens. But the Sokovia Accords still happen and this time the entire Avengers team defects to Wakanda.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
How do we know redshifting is due to the universe expanding? What if it's an effect similar to friction, so the wave loses energy as it travels through space, and it's just more noticeable from the extremely distant galaxies?

I ask party out of curiosity, but also because the idea of space expanding so fast that light can never reach us really kinda freaks me out.

[Assistant]
With respect to photons losing energy as they travel, one has to understand that, although we perceive light as taking billions of years to reach us, in the frame of reference of a photon, the journey is instantaneous. There is no opportunity for a photon to "leak" energy, or change in any other way, as it travels.

In fact, the same argument has been reversed to demonstrate that another type of particle, the neutrino, must have mass: neutrinos come in different varieties, and the ratio of those varieties change as neutrinos move through space. This implies that the neutrinos have time to randomly change from one type to another as they travel, meaning that they travel at less than the speed of light, meaning that, unlike photons, they must have a nonzero rest mass.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Why are light blocked by walls but radio waves are not even though they are both electromagnetic radiation?

[Assistant]
One of the ways to think of light is as an individual little "chunk" of light.  Imagine that your class goes on a field trip to the amusement park.  You're walking around together, and then you pass the entrance to the Ferris wheel.  There's a problem, though, a sign says you have to be at least 4 feet tall to ride on the Ferris wheel.  Your tall friends all go on the ride, but you and the other kids have to keep walking through the park.  Later, you guys might pass by one of the kiddie rides, and that says you have to be UNDER 4 feet tall to ride, so now you get to go on that ride, while your tall friends keep going.

That's the way light works when it goes through stuff.  All of your friends are like little pieces of light.  Just like not all of your friends are the same height, not all pieces of light are the same color.  When it passes through a material, if it's not too tall or too short, it gets 'absorbed,' but if it's unlucky, it might go through the whole park without ever finding a ride that it is allowed to go on.  If that happens, then the light passes right through, like it does in glass or water, or like how radio waves (very very tall guys) go through walls.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why are vehicles capable of going faster than the fastest speed limits if they're not intended for racing?

[Assistant]
It has to do with engine's optimal running temperature.

If an engine's top speed is limited to 55 miles per hour, that means it's usually running at 100% capacity just to meet the maximum highway speed limit. Over a long time, running at 100% capacity will result in a lot of wear-and-tear, overheating, and possibly meltdown of engine.

If the engine's top speed is 120 mph, then running at 55 mphs is only like 50% capacity, so lot less strain on the motor/engine.

So the engines are over designed to allow for the average highway speed to be in the optimal zone for engine running efficiency.

I agree with you though, electric cars of the future won't have this problem of optimal running efficiency, so they can be designed to have limits on speed without affecting motor longveity/durability/efficiency/.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Nolan Dark Knight] Why did the crime lord's agree to pay Joker half of their money?

At that point the Joker wasn't a famous criminal mastermind, he was just some random dude who robbed one of their banks. Why would they think his services/expertise was worth half their money??

[Assistant] Because not only did he manage to rob their bank, he also discovered and left behind the radioactive marked bills, and found the secret meeting place of the gangs. He also warned them about the Chinese character who's name escapes me at the moment. His track record was spotless and he has proven himself as being able to not only beat batman but to get away with attacking city officials. He'd killed off at least one gang and was threatening the others who paid him off as much to stop him from coming after them as to stop Batman. You have to remember they didn't agree to pay him until much later on after Batman had gone to China. Before then they treated him like anyone would a homicidal lunatic.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why can't we use the ocean to dump onto fires?

[Assistant]
Saltwater changes the pH of soil and can really hinder the regrowth of plant communities.

If you consider an area that seldom receives rain then you have a very long time before enough freshwater (rain) has fallen to restore soil chemistry.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[MCU] Why didn't Zemo just kill Karli Morgenthau?

When they met at that factory, he had a clean shot and she was distracted, looking over her shoulder for WS and Falcon.

Yet, Zemo, gets her in the gut and pauses, giving her time to run before resuming, he could've double tapped her and been done with it, yet he didn't, why?

[Assistant]
He wanted her to lead Sam and Bucky to the rest of the super soldiers and to uncover their larger plan so it could be stopped.

He knew killing her wouldn't end the super soldier threat due to the cell structure of the terrorists.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Mass Effect 2]Why is Shepard solving all of his squadmates issues?

Isnt there more pressing matters, like the extinction of the galaxy by the reapers? Cant their daddy/mummy issues wait until after?

[Assistant]
Resolving personal deep issues is pretty important in not dying when facing an existential force that wants to wipe out all life. Its not always like the movies where people are able to overcome their past in the heat of battle to become invincible heroes. Sometimes resolving your life problems can give people a clear head about what theyre fighting for, or at least hope against such terrible odds.

Shepard is experienced with this sort of thing, he knows how to handle even the darkest of scenarios as best he can.

That being said, while the threat is credible throughout, the only really time constraint is your own. The Harvesters seem content to hide behind their relay for now. He should take his time, prepare, research and do whatever he thinks is best as a prior and possibly future hero of the galaxy.

That being said, if by chance most of his crew gets abducted by them if say, Harvesters ambush the Normandy? Then he should haul ass straight through the relay to save them. Who knows how long theyll have...


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Harry Potter] Why was Ginny Weasley allowed to return to Hogwarts during the last year of the Second Wizarding War?

Molly Wesley almost didnt allow Ron and Ginny to return to Hogwarts the previous year because of the risk brought forth by Voldemorts return, and that was while Albus Dumbledore was still alive and protecting the school. Without him and with Ginny being the last of the Weasley kids in school, why did Molly and Arthur not pull her back to keep her safe?

[Assistant]
Before, voldemort  was a terrorist. Now, he's in charge.

You survive a terrorist by avoiding them. You survive a dictator by playing along. If she'd kept her at home, that might inspire some visits about why a good pure blood family isn't sending their daughter to Hogwarts now it's got a "proper" curriculum? Something to do with their known muggle and muggleborn sympathies, maybe?

Best to act normal until the opportunity to strike back shows itself.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: What is the difference between an ointment and a cream?

[Assistant]
Ointment = 80% oil, 20% water

Cream = 50% oil, 50% water

Lotion = <50% oil, >50% water

That is the medical distinction. Over the counter products may be regulated as drugs and/or cosmetics, and may not be held to strict standards.

Basically, feels oily, it is ointment, feels creamy, cream or lotion.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Stargate SG-1] How does an SGC team know a dial-home device will work before they go through?

I imagine, since the stargates are one-way, that without knowing this, there's a chance a team could travel through a stargate and encounter a malfunctioning DHD, leaving them stranded.

I know they send probes through first, but it doesn't really look like that probe could work the DHD to test it.

[Assistant]
The MALP confirms that there is a DHD and that it shows no visible signs of damage.

If it looks okay but turns out to be damaged once the SG team arrives, SGC should send generators for manual dialling once they realise at the first check-in.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why do symptoms of a cold sometimes go away overnight and sometimes take several days to fade away?

[Assistant] There are over 200 viruses responsible for giving you a cold, so there is a lot of variability between these that your body will deal with over different time lengths, the usual length is 7-10 days if you get a cold but it can be less or up to three weeks. Sometimes your immune system can react quickly to the virus and snuff it out (especially if you have been infected with it before or a virus that's very similar - this is called adaptive immunity and is how vaccines work). Also as others have said there are many other viral and bacterial infections or allergic reactions (e.g. a particularly bad day of hayfever) that will present similar symptoms.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Yu-Gi-Oh's- All Series] Why if they are such master duelists do the main characters always have to drop to less than 100 LP's before they find their feet and begin to fight back in every single duel?

Why not you know knock out the opposition while still having 2,000 life left?

[Assistant] You see in card games, such for example lets use Magic, there's no difference of lfie until you're at 0. SO if you have 800000 life or 1 life effectually you have the same state, because until you hit 0 you're alive. Therefore if you're at 100 life points then you're still alive and therefore okay and you don't really gotta worry about it.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] To what degree should casual readers of philosophy care about authorial intent?

[Assistant]
This question opens onto a massive field (philology, hermeneutics etc.), but it can be interesting to juxtapose what authors intend to mean and what they do mean, what they intend to do, and what they do. Intention in philosophy can, and has, been quite broadly construed - attaining truth, providing laws that govern experience, comprehending Being - and since philosophers as philosophers can *share* intentions their exploits can be contrasted with each other. This procedure is not external to philosophy, all philosophy has used previous philosophies, if not as material, as its stage.

But insofar as intention objectifies itself (minimally in language, sound etc.), it is beyond the controlling scope of the individual's interiority. Yet even there the subject is not in full possession of their intentions anymore than anyone can be wholly present to themselves. The primacy of the author has long since past for most. Those still holding to intention as the source of meaning are confronted with the problem that the meaning of any intention must itself be understood and so cannot be a ground, must be relative. (i.e. is hard to understand what Kant intends without a minimal understanding of the history of philosophy, enlightenment etc.)


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Elder Scrolls] If you read an Elder Scroll while wearing an eyepatch, would you only go blind in one eye?

?

[Assistant]
No. You don't go blind because the scrolls damage your eyes. You go blind because you are "trading" your sight for the sight of the scrolls.

And it's a lot more complicated than just "read them and go blind". For the great majority of people, reading the scrolls will do nothing. No blindness, no insight, just looking at piece of paper with a lot of nonsense on it.

It's when you know enough to start to understand the scrolls then things start to happen. Most likely you'll just go mad (but keep your eyesight), but if you've got the knowledge *and* the mental fortitude to comprehend what you're reading, that's when the blindness happens. And if you've got an exceptional amount of knowledge and mental fortitude, then it's possible to read them several times before you go fully blind.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why does jailbreaking technology exist? Why is there something for me to break into, instead of never having it there in the first place?

I asks because I just read an article about how hackers had figured out how to jailbreak Google Glass, as there had been some features that Google didn't want available on the glasses. But why do they exist there in the first place? If they didn't want them to be used, why are these capabilities still on the software? Hope this makes sense...

[Assistant]
A digital watch is a computer, but it's limited. The computer hardware is designed to be a clock, and nothing else. There's no point in jailbreaking a digital watch. They're like a train, they have fixed rails they run on, and you can't take them off those rails, or they won't work.

But phones, tablets, computers, google glasses etc are "fully general computing devices", which means they can run any program. They're like cars - they can drive on any road, or drive offroad, or anything. Making a computer (or phone, tablet, glass etc) that only runs certain programs is like making a car that only drives on certain roads. You have to deliberately restrict it by putting up some kind of barrier, because by default it can drive wherever. Google glass can run any type of program, and if Google only wants it to run the program they put on there, they need to put up some kind of barrier.

Jailbreaking is figuring out a way to get the car over or through or around the barrier, so you can drive it wherever you want. You're not breaking in, you're breaking *out*.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Logarithms of complex numbers? Logarithms with complex bases?

I was recently thinking about math, and I realized that I could use Euler's Identity [e^(ix) = cos(x) + i*sin(x)] to define logarithms of complex numbers. Here's how: those of you answering this question should know that any complex number a+bi can be transformed through Euler's identity into the form re^(ix), where r is the radius from the origin and x is the angle this radius makes with the real axis. This can be further transformed into e^[ln(r)+ix]. So if I have a complex number z = e^[ln(r)+ix], I can take the natural log of both sides to get ln(z) = ln(r) + ix

This, in itself, is crazy enough. I was taught all throughout grade 11 and 12 that you cannot take logs of negative numbers, yet this equation allows it and produces results consistent with each other and with Euler's formula. For example, the natural log of -1 is i(pi). The natural log of i is (1/2)i(pi); ln(i) is half of ln(-1), because i is the square root of -1.
I'm getting side tracked.

Evaluating the natural log of complex numbers allows for logs with complex bases. Start with ln(x) = y, then apply change of base formula by converting to exponential form {e^y = x}, taking a complex log of both sides {log_z(e^y) = log_z(x)}, using log properties to bring y out front {y*log_z(e) = log_z(x)}, then replace y with it's equivalent from the starting equation {ln(x)log_z(e) = log_z(x)}. So, a complex logarithms can be taken as long as we can evaluate log_z(e), which we can. Knowing that z = re^(ix) = e^[ln(r)+ix], the question is "What power should we put on e^[ln(r)+ix] to get e? The answer, of course, is 1/[ln(r)+ix]. So my equation from before becomes log_z(x) = ln(x)/[ln(r)+ix]. This allows lots of interesting things, like logs with negative or imaginary bases.

I'm sorry if this comes off as rambling and not much like a question. My question is, is all of this mathematically valid? Has it been discovered already? Has it been discovered, but left undefined for the same reason that 0/0 is? Why do my teachers tell me I can't take logs of negative numbers?

[Assistant]
Yes, all of this works, except there's one thing you haven't taken into account:

when you write z = re^(ix), that representation isn't unique, you could take x' = x + 2pi, and z = re^ix' as well. Thus, when defining the logarithm^(*), you have to be careful and take this into account. You can address this by saying "x is the angle between 0 and 2pi such that z = e^(ix) " or (more commonly) "x is the angle between -pi and pi such that z = e^(ix) ", or something like that. This is called a "branch cut" and is needed to prevent the function from being multi-valued (only one output for each input).

One final note, you still can't define the value of log(0).

\*: usually, in complex analysis and further mathematics, "log" is synonymous with "natural logarithm", since the base 10 logarithm isn't really special, important or needed.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[The Matrix] Were there any exceptional people in the Matrix, like James Bond, Indiana Jones, or Lara Croft, or was everyone a worker drone?

Did the Architect allow for competitive dominance and extraordinary people, like SEAL teams, super scientists, and creative geniuses?  Or was the world fairly bland?

[Assistant] There's a questionably canon (prequel?) series where the Machines cause a simulated WW within the Matrix and utilize humanity's best pilot to take out an alien menace. Not as cool as it sounds, but to me it seems like they'll breed excellence when required to.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] If muscle cell never divide, how does people become muscular ? How do they build muscle ? How does a child grow?

[Assistant]
Skeletal muscle cells do not divide, but there are precursor cells that can turn into new muscle cells. Those precursors are capable of dividing, though in an adult they're usually just resting.

In addition, an existing skeletal muscle cell will be able to grow in size without dividing.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Resident Evil] Spencer is the founder and owner of the largest and most advanced pharmaceutical company but why can't he find a cure for his condition?

[Assistant] His condition is old age, which is recalcitrant to any form of treatment. He even tasked Alex Wesker, one of his eugenic ubermensch pet projects, with finding a cure. He gave her unlimited funding, unlimited test subjects, a private island, and a bunch of viruses that can do basically anything. She abandoned the project and abandoned Spencer when she realized it was impossible to achieve somatic immortality.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why does the sound of filling up a water bottle change the higher up it gets?

[Assistant] Because as the bottle fills the space the sound is bouncing around changes. When you're filling up an empty bottle the sound is coming from relatively far away, as opposed to the top where it's moving a small distance and thus has a different frequency (sound). It's similar to putting your finger on a closer to further hold on a wind instrument, but with water.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] There is a real fear that AI will become too advanced for humans to control and we will be "enslaved" to the AI. So, is it our obligation to train AI to govern us the way a king would train his son to rule?

[Assistant]
There might be a real fear but it's an open question whether that fear is justified. The current popular conversations are fostered by people who don't actually seem to be experts on AI (Sam Harris, Elon Musk, etc.) and those who are experts usually dismiss the current conversation as overly enthusiastic and closer to science fiction than reality.

I think rather than jumping ahead and thinking about some robot apocalypse future we ought to be asking questions like: what constitutes intelligence, what does 'far more intelligent than humans' mean (we know what 'twice as much water as this cup holds' or 'processing videos three times faster' means in the relevant contexts). Does 'twice as intelligent' or 'many times more intelligent than humans' have any sort of sense? What would it mean for intelligence to emerge from a neural net? Does intelligent behaviour require pain and pleasure, avoidance and some form of success (i.e., a creature that has no goals, or at a more basic level if there is nothing that constitutes success or failure for it, how can we measure its intelligence?).


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Are there any weapons -- real or theoretical -- that have greater power than thermonuclear weapons?

Edit: To clarify, I am talking about man-made devices.

I'm not entirely sure what I meant by power either, I suppose what I meant was the destructive potential of a single device.

[Assistant] Depends on what you mean by power.  Antimatter weapons would theoretically be more powerful than nuclear weapons.  Even with the same energy released, the antimatter/matter collision would occur faster than the nuclear fission/nuclear fusion reactions used in current nuclear weapons.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Star Wars] What would happen if I were to shoot a Stormtrooper at close range with a standard earth handgun? How about a shotun?

[Assistant]
Stormtroopers' reinforced plastoid armor is completely resistant to anything short of "abnormally large" or specialized armor piercing rounds. Your best bet is moving up to some sort of specialized rifle capable of firing one of those.

An extremely lucky shot might hit the bodysleeve beneath the plastoid plates and penetrate, but you'd have to be a Jedi or something to hit those with any accuracy.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Star Trek]Why isn't Naomi Wildman socially awkward around other children? 99.9% of the time she never gets to interact with anyone her age

when she didn't want to play with the  Vaadwaur children (because they kept saying racist stuff about Talaxians) Neelix's first reaction was to say "that's not like you".

.....These are some of the only other kids she's ever gotten to play with, but it's weird she'd be socially awkward around them?

[Assistant]
I'll assume that Star Fleet has special holoprograms for children in that situation, ie living on a ship/star base with very few other kids.  Think Sesame Street with 3 centuries of improvments.

Also, see'The Diamond Age' by Neil Stephenson.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] When the LHC first started the beams had 3.5TeV per beam but the heaviest particle discovered is 173GeV. Since they're upgrading, does that mean no new particles have been found between 173GeV and 7TeV?

[Assistant]
1. It's a bit more complex than that. Even though energy of the center of collision is X it does not mean you will produce a single particle with such energy (assuming such particle exists). Normally lots of particles are produced. Higher energy means you cover broader energy range, and you raise probability of getting some very high energy particles. New particle discovery is purely `statistical` - if we notice enough signals from some particular energy range, we can assume there is a particle there. But probability of producing such particle might be very small, so it requires lots of data to confirm. Maybe there is a particle at 7TeV but the chance of all collision energy going into this single particle is so low, that it didn't give significant enough signal.
2. Current LHC upgrade moves towards `higher luminosity` and not `higher collision energy`. This means LHC will have more collisions, over the same energy range.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5 torrents

I think I understand it but i'm not sure.

[Assistant]
You want a new book that has 100 pages but don't actually want to purchase the whole thing, so you go to a meeting place (tracker) where everyone who has the book or who is interested in getting it all get together.

Then, you tell everybody that you are looking for pages 1 to 100. People start making copies of random pages from their own books and give them to you. You will received them out of order, but it doesn't really matter since the page number is at the bottom, so you can easily put them back in order.
After a while, you have a small stack of pages yourself and can start sending pages even if you don't have the full book.

Leechers are people who don't have the full book.
Seeders are people who do have the full book. They won't ask for pages.

One seeder is enough for a whole group of people. For exemple, as soon as the seeder has sent a page to someone, both of them now have the page and they can both start making copies for other people.

The strength of torrents is that:
1. You can start sharing even if you don't have the full file.
2. You can receive the file out of order.
3. Everything is checked in real time so that if you receive a corrupted page, it is discarded and requested from someone else.

The main disadvantages are:
1. The file comes in out of order. For a video file, for example, you will have to wait until you have the whole thing before you can watch it.
2. People have to share. Otherwise, it's the same thing as normal P2P software.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Is a submarine able to safely contain humans in space?

[Assistant] From a pressure point of view, yes, but what would soon be fatal would be temperature. In a vacuum, it is difficult to radiate off waste heat without features specifically designed to do so. The temperature inside the submarine would rise to lethal levels.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why do computer games need to "restart to apply new settings" after changes are made by the user rather than applying them to the current session?

Exactly as it sounds - many computer games need to restart in order to apply some graphics setting changes, but I do not understand why. Some changes require the restart and others don't. Why?

[Assistant] Those settings involve things generated during initialization, while the game is loading up for the first time. If they could simply be changed on the fly, they wouldn't need you to restart, but some settings (especially graphics settings and memory usage) require those settings to be initialized with the launch of the program and can't be changed during runtime, typically because they call upon the graphics card or OS to set aside particular resources for the program and the OS gets super testy if a program starts out saying it'll want a certain amount of RAM and then changes its mind while running.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: If USA and Russa had an all-out nuclear war during the Cold War, would there really be a nuclear apocalypse like we see in movies?

[Assistant]
To be honest, no one really knows.

We know there are enough nuclear weapons to take out the worlds major cities, but if countries like India, Brazil and South Africa weren't directly involved, they might survive with their populations intact  They could emerge relatively unscathed at the worlds new superpowers, and humanity would not take too far of a step backwards in terms of development.

We speculate that the smoke from the ensuing fires would result in reduce sunlight reaching the earth.  That could result in anything from a few lean years to a complete agricultural collapse sending man kind back to the Dark Ages, or worth.

There would also be nuclear fallout, and this could be made much worse if dirty bombs were involved.  This could be the difference between land being resettled in a decade, or being uninhabitable for centuries.  It would also impact how much poison enters into the overall ecosystem impacting all humans.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
What exactly is a photon?

I'm a bit embarrassed to ask this question. I sort of know what photons do but not exactly what they are. Where do they come from? How are they created and what particles are they made up of?

[Assistant]
Photons are little disturbances/ripples that move around the electromagnetic field. This electromagnetic field fills all space, and it is stronger near things like electric changes and magnets. Because this field obeys quantum mechanics, the ripples carry discrete properties that can only be certain numbers. This makes it very different from things like water ripples in a pond. This is what we mean when we say something is 'quantized.' They are created when charges move or change configuration. Some examples of this would be the light given off by light-bulbs when you run current through the wire, when you bounce two electrons off each other and when an excited atom relaxes to a lower energy field configuration generating a photon.

Photons are, as far as we know, not made up of anything else. They are their own particle which is fundamental. They also do not have mass, but they do have energy and momentum.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Fantasy] What purpose does a dragon "rider" actually serve?

The dragon does all the work, what good is some dude with a sword on its back when you already have a firebombing monster?

[Assistant] In most cases, it's probably that dragons in that universe do not have much tactical prowess beyond burning everything. So you have a general riding on his back, getting an amazing overhead view of the tide of battle, who can swiftly relay orders or apply searing, roaring, immolating literal *fire*-support wherever it's needed.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Star Trek] What is the Federation's policy on people that were genetically upgraded against their will?

I know the Eugenics Wars made the Federation strongly opposed to genetic manipulation (apparently to the point where they're willing to allow death itself to keep existing even though they could probably cure aging anytime they wanted to).

So what do they do if they encounter someone that had been forcibly manipulated despite not wanting it? And what if those manipulations were highly beneficial? Would they execute the poor sucker or banish him from Federation space?

[Assistant]
Mild spoilers for Star Trek: Deep Space Nine below...

>![Doctor Bashir was modified in childhood due to significant disabilities, and when the information slips out is genuinely scared that his career in Starfleet is over. In the end, his father confessed in full to having his son illegally modified, and is sent to prison, and Bashir is able to retain his post and commission.]!<

So, presuming A) the target of the modification is unwilling or unable to consent and B) the culprit can be positively identified, someone could be subjected to genetic modification and still have a life. That said, the victim would likely be watched like a hawk; Khan and his boys have permanently etched "superior ability leads to superior ambition" into the human psyche, and many would fear that the victim might go full super-tyrant if the conditions are right.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: What is a 'beer belly'?

How do they form and what do they consist of?

[Assistant] It's actually a combination of fat from a poor diet and an inflamed liver. Alcohol causes inflammation of tissues, particularly in the liver. Add in a crappy diet with carb-heavy beer, and the gut takes on a swollen appearance. Just a plain old fat belly won't be as round and swollen looking as a beer belly because a beer belly is actually swollen.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Doctor Who] Do the Daleks hate any race more than others?

I know that the Daleks believe that all races are IN-FER-I-OR TO THE DA-LEKS, but is there any specific race that they believe deserves to be EX-TER-MIN-AT-ED more than others? Or are they all equally inferior?

And I know they hate the Doctor specifically, but does that extend to the rest of the Time Lords?

[Assistant]
They absolutely want to get rid of the Time Lords above all else, hence the Time War.

But that's mostly because the Time Lords are the most pressing *threat*.

When it comes down to it, you're Dalek or you're Not Dalek and must be EXTERINATEd.

Hell, sometimes it's "You're either Dalek or Not Dalek Enough".


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Star Wars] What are the possible uses for a lightsaber scabbard?

Inspired by episode 1 of Star Wars: Visions.

A lightsaber is already a sword with a retractable, nonphysical blade, so what possible uses would a scabbard (designed to protect a physical blade from rust and damage) serve for a lightsaber?

[Assistant] I could very well see it being useful as a non-lethal weapon in itself. Basically, assuming the connection between hilt and scabbard is secure, you have what is essentially a kendo sword. If a Jedi or Sith want to make a statement or put some hurting on someone without just killing them or wounding them with the blade, hitting them with that scabbard is going to *hurt* without doing too much damage.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5 why MRI machines make so much noise.

My boyfriend got an MRI of his brain the other day and will not stop talking about all the noises it made and has been obsessing over the Why of it. Can someone ELI5 so I can give him the answer he so desperately needs?

[Assistant] because on the inside of the machine, the large metal coils are vibrating when electricity passes through rapidly, creating a magnetic field, which causes the banging noise.  the louder the bang, the more the vibration, the more detailed the scan.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why do radio stations that can't receive a signal turn into static instead of silence?

[Assistant] Cosmic radiation, electromagnetic radiation, even lightning - your radio picks it all up, and, in the absence of a stronger radio signal, makes the sound of the background hum of the universe.  That's kind of beautiful, isn't it?  It makes me wonder why no one has popularized listening to static as a meditative exercise.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Harry Potter] What place do vampires have in wizarding Britain? Why aren't they more feared?

I recently moved to Britain from somewhere with a very different culture, and I'm still trying to get used to the way you Brits do things.

Yesterday I was shopping at my favorite candy store and I saw these things called "blood pops", hidden on an obscure shelf. I asked someone "What's the appeal of blood-flavored candy?" and she said "Vampires love them." in a very casual tone. That has me extremely worried. Where I come from, we see vampires as vicious predatory creatures: Monsters to be hunted and feared. Like giants, acromantulae, or werewolves. But it seems like over here they've integrated into society completely. I mean, why else would they be able to openly buy blood-flavored candy? Why else would there be a large enough market for that candy to even be manufactured?

As far as I know, I haven't met any vampires yet. But I can't help but feel confused and worried. Are vampires accepted in British society? If so, why? Is my vampire prejudice misguided? What's going on?

[Assistant] Well, first of all, if they need blood, there's no reason they can't prey on animals-- and the fact that blood-flavored candy is a standard item suggests they can. If they need human blood, they can always just be pointed at Muggles-- few wizards particularly care what happen to a few random muggles a month.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: What is the stuff between atoms?

Like my chem professor was talking about how atoms bounce against each other. So what are they traveling in?

[Assistant]
Space.

Space doesn't start once you get out of the atmosphere.  The atmosphere is just a part of space that has some denser gas concentrations than the bit farther out.

There is even space between the atoms of solid metal, just not spaces big enough for gas atoms, that's what we mean by "solid".

To squeeze all the space out, you'd have to have some sort of degenerate matter, like neutronium.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Futurama] Why did Fry's bank account still exist after 1000 years? Wouldn't he be declared dead in absentia and his assets liquidated?

[Assistant]
Working cryogenic freezing existed in the year 2000 in this universe. Heck, apparently it existed in the 1980s, since there was that guy with Bonitis. And there was Fry's old girlfriend and Paulie Shore.

So Fry's situation can't be unique. If people waking up from a thousand years of sleep is just something that happens on a regular basis (regular enough that working with them was Leela's original job and support groups for them exist), then it makes sense that society makes allowances like keeping bank accounts open.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: What's the advantage of different pupils in the eyes of different creatures? I.e. Cats having slit pupil, where as ours are circular.

[Assistant]
A lot of it is a byproduct of evolution. The theory is that nocturnal animals have slit pupils so if they have move around in the daytime they won't burn out their eyes from the sun since slit pupils can block out most of the light.

We don't really have many answers apart from that. Grazing animals also have large pupils, presumably for better peripheral vision. Big cats, like lions and tigers, have round pupils like we do as well, the theory being that their vision is higher up from the ground because they're bigger. Slit pupils are linked to small predators apparently.

The most valid and true answer at this point in time is: evolution is weird.

Did a few minutes of research on this, scientists can only speculate.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why are some items only top rack dishwasher safe?

What is the difference between the top and bottom rack?

[Assistant]
The proximity to the giant heating element at the bottom of the dishwasher.

When the dishwasher goes into its dry cycle, that heating element gets really really hot, the top rack doesnt get nearly as hot as the bottom rack.

Picture sitting right next a fire place versus across the room on the couch. Sure the fireplace warms the whole room, but sitting on the hearth is WAY hotter.

So if youre made out of plastic that could warp or deform from high heat, you should stay on the top rack.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5:Why aren't claw machines and other similar arcade games considered gambling?

[Assistant]
In THEORY, those games involve skill. Now we all know the computer is a cheating bastard, but you do have to have skill with the machine to get the prize. Gambling is mostly or entirely down to luck.

Also, gambling laws usually refer directly to money, not goods as prizes. Japanese pachinko parlors spent DECADES skirting the "no gambling" laws by only offering prizes....which you could then conveniently sell right across the street in exchange for cash.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Is the handedness of a subject important to know for doctors and scientists, and if so, why?

I've seen a couple of medical TV shows recently where they talk about patients or test subjects as follows:

> Patient is a right-handed man in his 50s in generally good health etc. etc.

I'm just wondering whether that's considered important in real life and if so why? My doctor has never once asked me which hand I use, for instance.

[Assistant] If it pertains to musculoskeletal or rheumatologic disease then handedness does indeed matter. Right hand pain in a right-handed, older mechanic is more likely arthritic or degenerative in nature as opposed to right hand pain in a left-handed person. Bilateral pain can sometimes be worse on the dominant side as well, also giving clues to a diagnosis. In terms of other diseases handedness plays less of a role, and is likely included for thoroughness.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
I believe movies on imdb with more than 20 - 30 years should not be open for rating, CMV

I state this because I think movies in general are made/released in the context of their time and that people who see them decades in the future might not really understand them or their importance/quality.

I can give 2 examples: some years ago I saw Citizen kane for the first time, I understand as a movie being realeased in the time of musicals and westerns it must have been an amazing breath of fresh air, but decades away it's looks to me just as an ok movie, so I refrained from rating as it would be unfair to give it a relativelly slow rating.

Another example was the blues brothers: saw it weeks ago and thought it was mainly boring and childish, after seeing the reviews (and trying to understand the high rating) I realized at it's time with those actors, those cameos it must have been something great, just not from my actual point of view...
(this could probably be said about most movies of the 80s)

SO basicly that's it: movies/tv shows should be judged in the context of their time and rating them decades in the future will result in unfair ratings.

[Assistant]
If someone goes onto imdb to see how good a film is, knowing how good a film was to people 30 years ago isn't going to help much. What is useful to them (and indeed would have been useful to you before you watched those films) is how much you, in the context of modern society, will enjoy those films. If a film has aged badly, this would be reflected in the ratings.

Perhaps what would help would be two ratings, one that was given at the time, and one that can be constantly updated.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Do any of the stars in the centre of our galaxy harbour planets?

I'm also curious as to whether there are a ton of star/planet collisions in the centre.. I'm assuming there would be massive, massive explosions of stars constantly blowing themselves up.

[Assistant]
There aren't many collisions in the centre of the galaxy - the stars are still plenty far apart from each other. You do get some mergers in places like dense globular clusters, but not all that many. However, rather than direct collisions, the gravity of a star coming even vaguely close may disrupt the orbits of the planets and throw them out of the system. So you might not expect many planets in this inner region.

In terms of explosions - in the Milky Way, much of the new star formation is going on in the spiral arms, so the central bulge tends to have older dimmer calmer stars, while the spiral arms have more big bright young stars that burn themselves out quickly and go supernova.

But you do have a higher intensity of background radiation because of the large density of stars, which may have some effect on life and evolution - although it's not completely clear which way this would go.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why is the lowercase 'a' we type different to the '' I write by hand?

[Assistant] Partly because of old printing presses with handset type. The lettering used on old presses could become worn, making that a look like an o, or vice versa. By using the a we know in common typefaces today readers could easily distinguish between an actual a and a worn o.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why does water taste delicious and refreshing, but watered-down drinks taste disgusting?

[Assistant]
You're used to the "taste" of water, and you expect what you get when you drink it.
Likewise, you're used to the flavor and sweetness of sodas/juices/teas you get in stores. Your body likes sugar. If you dilute it, your body isn't used to the reduced sweetness and it won't taste as good. If you drink a diluted stuff for a while, you could get used to it.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [star wars] During the galactic civil war, did anyone know (or suspect) that Palpatine was also Sidious?

[Assistant] "Sidious" was an unknown to all but his inner circle. Were there people aware that Palpatine was not the kindly grandfather he appeared to be up to and during the Clone Wars? Absolutely. But most who could link Palpatine to the mastermind behind the Confederacy were dead at the end of the Clone Wars.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
What exactly composes the taste of freezer burn? Is it a chemical in the food that tastes like freezer burn?

Not asking how freezer burn happens, but rather once it happens, what are the constituents of the taste?

[Assistant] So, you can taste the freezer burn taste in the fost that builds up in the freezer if you put a little on your tongue. This suggests the freezer burn taste is some kind volatile/aromatic in the food that tends to vaporize and recondense with the water that sublimates from food. Likely is those aromatic compounds, but oxidized from exposure to the air before they recondense.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[WH40k] How do Tyranids and Necrons intract?

Do Tyranids attack Tomb Worlds, do they even have any reason to attack Necrons (no organic material). Why would Necrons attack Tyranids?

[Assistant] "The long-lost final Silent King of the Necron Triarch, Szarekh, enters the bounds of the Milky Way Galaxy once more. Having encountered the Tyranids in the intergalactic void, he recognizes the threat they pose to the Necrons' apotheosis -- if the Tyranids devour all organic life in the galaxy, the Necrons will never find living bodies to house their consciousnesses once more. Thus does the Silent King break his self-imposed exile with the goal of marshalling his people against this new threat."


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
If black holes are so powerful that not even light can escape, how is it possible that they emit xray/gamma rays?

If a black hole is so powerful that not even light can escape it, how is it that we "observe" them by the x-rays & gamma rays they emit? How is it possible that they emit anything at all!?

[Assistant]
The X-rays are emitted by infalling matter just outside the event horizon, not by the black hole itself.

Edit: black holes are also theorized to emit Hawking radiation, but this has never been directly observed.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] When we microwave food, why isn't the air in the microwave heated?

[Assistant]
It's not just water molecules, it's polar molecules that rotate in response to the alternating magnetic fields.  This constant rotation is more akin to a vibration, and when molecules hit each other, they create heat.

The majority of molecules in the air aren't polar (80% n2 19% o2, trace amounts of others).  Since they aren't polar, they don't rotate to align with the magnetic field and thereby generate heat.  However, the air does heat as a result of convection/conduction from the material that is polar.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
CMV: Taco Bell is by far the best fast food choice for vegetarians

Earlier this month I switched to being full vegetarian after experimenting with some restrictions for many years. The transition has been pretty smooth for the first part, although I've had to transition away from some of the ways I've handled my diet.

The biggest change has been fast food. I work strange hours and am often on the road, so there are many times when a fast food place is the only reasonable option if I'm going to eat at night. Before, that would have meant a McDonalds run, but they are completely ill-suited for a vegetarian unless you just want fries or a boxed salad.

But then I discovered the joys of Taco Bell. I probably could count on one hand the number of times I ate Taco Bell each year before, but their options for vegetarians are actually quite reasonable. Aside from menu items like a potato taco, they also have nachos, quesadillas which are more flavorful than just cheese and a tortilla, and a full array of menu items which can substitute beans for meat quite easily.

It's gotten to the point where I've given up on just about every other fast food chain unless I'm really craving a grilled cheese.

Perhaps I'm unenlightened though. CMV.

[Assistant]
I would say Chipotle is better as a fast food choice. Less individual items, but the quality of food is much better.

You can get nachos (I think?), Tacos, quesadillas, and burritos. You can get them with either mixed grilled veggies, or sofritas, if you need more protein.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why does AM radio sound different than FM radio?

[Assistant]
AM waves are long, thick, and don't transmit much data. This allows them to travel long, long distances without too much loss of quality, making them ideal for emergency broadcasts.

FM waves are shorter and contain much more data, making them ideal for commercial radio. They don't travel nearly as far (because there is more data to lose).


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Before modern consoles, why didn't older games have bugs like newer games that get updates constantly with patches?

Although older games did have bugs, it doesnt seem as buggy as newer games.  Were older games more well written?

[Assistant]
Older games were much simpler, so it was far easier to make them without having as many bugs.

Also there really was zero option to update games reliably with patches in the past, now it's automatic since everyone is almost always connected to the internet.

"more well written" is incredibly difficult to answer, since we almost never have an actual idea about the code that actually made up the game.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why can't we dump nuclear waste in the same place we mine nuclear fuel?

[Assistant]
Old mining shafts are the most common places to store nuclear waste, so we kind of do that.

Its just that these shafts have to be checked and prepeared because if there is for example leaking water, it could radiate whole lakes and countries.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
What is known about neurological/psychological differences between genders in cultures not using a binary gender system?

Since there's some neurological and psychological sexual dimorphism in humans I was wondering to what extent the differences are due to culture. I've only seen studies comparing male/female/intersex in western or westernised cultures using a european gender system.

Are the differences in personality traits, aggression, types of intelligence, brain structure, hormones and such seen in the same way in other cultures? Do they vary based on sex alone or also gender? Is it too difficult to study due to the influence of western cultures?

[Assistant] I think people tend to exaggerate the existence or importance of "nonbinary" in cultures largely due to their own social agendas (e.g., positing that intersex is descriptively parallel to male or female). You could also argue that even in western cultures there isn't sufficient neurological or psychological consensus to ask the questions you appear to be interested in, let alone for culture's that have long passed from the scene or are remote.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
I believe that rap music and the culture surrounding it is barbarious and detrimental to western civilization. CMV.

What I'm talking about is what you would call a 'punk' or 'chav' in the UK- the people who belong to this culture often criticize caution, introspection, and sensitivity and glorify hedonism and base pleasures. Rap, house, reggae, and hip hop are the genres of music that these people most often listen to. A higher percent of latinos, and especially blacks, tend to belong to this culture, but recently a very large percent of young whites have adopted this as well. The people who belong to this culture tend to not care about achieving self actualization- they seem to care about money and sex and drugs. They can't see why somebody should care about education, or things outside of their narrow view of the world. They are unorganized and apathetic towards politics. I don't think this is a class based thing- I see lots of middle class white kids adopt this culture. And other impoverished, lower class cultures seem to have been able to produce art and organize to help themselves. I don't know. By the way, I don't mean to say that there is no artistic value in rap, I know there is some good rap, but I can't think of a better way to identify the type of people I'm talking about. CMV.

[Assistant]
You're talking to today's mainstream rap music.

The only issue is it is being targeted towards these very same people that aren't quite so smart but will spend money on it and immerse themselves in the "culture"

There are however TONS of current rappers that promote education, hardwork, equality, etc through their lyrics. They are however (with the exception of a very select few) not very famous.

There was also a huge amount of conscious rappers around the late 80s and early 90s...when the genre was dominated by socialist activists lyricists.

I very much enjoy rock...and it doesn't take long to realize that rock has the same kind of fans. They go no where in life, they drop out of school, etc.

Same thing happens with metal, country, alternative, etc.

**tl;dr** stupid people like all diff. kinds of music.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[MCU/ Winter Soldier] Modern HYDRA members knew and understood they were part of an organization with strong Nazi ties, right?

I know that Red Skull renounced his allegiance to Nazi Germany in The First Avenger, but that doesn't mean his goals at the time weren't in line with Hitler's just on a grander scale. Director Pierce is not only aware of the existence of Arnim Zola but was in active collusion with him until Zola's destruction. Pierce at a different point mentions his father fought in the 101st airborne during WWII. So presumably at least some high-level HYDRA agents were aware and accepting of their Nazi roots but did the common staff or the politicians like Senator Stern know? Was there any rationalization or justification given to try and coax them into joining HYDRA?

[Assistant] Luckily for HYDRA, most people who are willing to join HYDRA aren't known for their strong moral fibre. It appeals to people who want to implement and run a global authoritarian state, and most of those people either already have strong ideological similarities with fascism (if not legitimately fascists already) or don't give a shit about ideological connotations. Neither would be particularly cut up siding with an organisation that once allied with Hitler.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: How does eating spoiled food actually make you sick?

[Assistant]
Most food gets spoiled because of microbes growing in it.  These microbes are competing with animals like you for dead animal and plant material...if you eat the food they are growing on, they lose their food source and might die.  So some kinds of microbes make chemical compounds that taste bad or are straight up toxic to keep animals from coming along and eating their meal.   A lot of food poisoning happens when you consume these toxins and they make you sick in various ways.  Sometimes you also get infected by a pathogen, but it's definitely not the main way to get sick from spoiled food.

This is why cooking spoiled food doesn't necessarily make it safe.  If you kill all the microbes, you may still leave behind the toxins.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: How are private prisons legal?

I've been wondering how it's legal for a private organization to incarcerate a federal/state prisoner (or any prisoner of the government for that matter).

[Assistant]
How is the government hiring a company to manage prisoners different from the government hiring guards to manage prisoners?

The company does not decide who goes to prison or for how long, the government does. The government also sets the standards for how prisoners are to be treated, and has a responsibility to enforce those standards - just like it does for state-run prisons.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: If bruising is the body's way of protecting itself, why do we try to reduce swelling when treating an injured person?

[Assistant]
Bruising is not the body's way of protecting itself.  A bruise is the result of a trauma that ruptures capillaries/blood vessels.  The resulting swelling is blood "leaking" into the surrounding tissue.

The treatment for swelling is applying something cold to the bruised area.  The cold causes blood vessels to constrict which reduces blood flow to the area.  This allows the capillaries to heal more quickly.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Does an insect's exoskeleton heal from injury?

Does an insect's exoskeleton heal from injury?

[Assistant] It depends on at what point the insect is in its life cycle. They do have clotting mechanisms that will block an external injury and keep them from desiccating, in most cases. If it's an adult insect, that may be as far as external "healing" goes. If the insect is a juvenile and pupates or moults after the injury, the exoskeleton will typically be completely reformed or replaced.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Why are there deserts near the coast? How come they don't get more rain, despite being near to a large body of water with plenty of sun and evaporation?

[Assistant]
So, let's take an obvious one like Namibia.  Namibia has a very cold current running north up it's coast called the Benguela.  It is quite cold.  The air above it is also quite cold, and therefore *dry*.

This cold air hits the hot desert dunes and warms rapidly and heads straight up.  Very little moisture makes it inland.

So temperature difference between land and sea due to ocean and wind currents can cause the situation you are describing.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: why do people throw up after extreme workouts?

Just curious as to why it happen.

[Assistant] If you body is doing a lot of work, it needs all the energy it has, digesting food takes energy, so getting rid of it allows more energy to be used for task at hand.  Sort of a fight or flight response.