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

[User]
Why are research databases so bad at picking up keywords in search string?

Hi there,

I am currently trying to conduct a literature review and I have found this (many times in the past and present) that no matter what combination of very specific keywords I use, the results still end up with random papers that have nothing to do with what I searched.

Now, I know you may say this is because I am being too specific and its just finding the next closest result but when I go on and trawl page after page, I can actually pick up papers here and there that I do need!

But why is pubmed/medline/google scholar bringing up so much irrelevant stuff?

[Assistant] Librarian here, probably because you are using a keyword search so the database shows results where those terms show up anywhere in the article, even the citations or authors names. There is a lot of nuance to catalog or database searching, you really have to utilize tools like Boolean operators, subject search, and wild card symbols and quote marks if you want high accuracy.


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

[User] [Batman] Why is there a Dinosaur and Huge Penny in the Batcave ?

[Assistant]
Trophies from previous capers.  The penny is from a deathtrap that Two-Face put Batman and Robin in one time; each was tied to a different face of the coin.  When the coin was flipped, random chance was to determine which one was squashed.

The animatronic T-Rex is from a deadly criminal-run, dinosaur-themed amusement park.


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

[User]
ELI5: How military units get their numbers?  Like where does 25th ID come from?  Wheres 24th ID?

I dont understand the number structures at all and what they symbolize. I get that there is like a 1st INF DIV but why is their FA unit Charlie 3-07 (just as an example)?

[Assistant]
It's largely random. In WWII we had the first, second, and third armies, but then you get reasons like:

-SEAL Team 6: Actually the second SEAL Team, but we wanted the Russians to think we had more.

-112th Airborne: Made up of 2 different units, something like the 50th and 62nd, couldn't decide whose number to take when they got combined, so they just added them.

Other units were just split up and given "the next number" that wasn't being used and then became autonomous by circumstance, so they were reinforced and became their own unit. Really there's no single rhyme or reason to it.

Charlie 3-07 sounds more like a callsign. Like the 7th crewman in the 3rd vehicle of Charlie platoon.


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

[User]
Why did old CRT TVs get some discoloration when you hold a magnet up to them?

And why dont modern led tvs do that.

[Assistant] The pixels of a CRT are made from a phosphorescent material that emits light when hit by electrons. To create the picture, a modulated electron beam is swept over the screen to selectively light up the pixels you want to light up. For each point, you actually have three pixels for the elementary colours. If you put a magnet up to it, you distort the electron beam, and thus it does not hit where it is intended to any more, causing colour and shape distortions. In a modern TV, the pixels are actively light emitting semiconductors which are switched on and off and do not need such an electron beam.


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

[User] ELI5: Why does it seem that there are always massive breakthroughs in finding a cure for cancer, then we never hear about it again or It seems we never actually get any closer?

[Assistant]
Because the media is very very very very bad at properly reporting scientific breakthroughs.

Meaning they hype up something gigantically, taking it out of context, presenting it as if it is already ready to be used, but in reality that is never how it goes. Usually what happens is

1. someone does research, realises that cell X is present in nearly all early stages of cancer Y, and that maybe if we find a way to detect cell X, we can find cancer Y when it is still easy to treat.
2. a paper is written about this, indicating that caution is still needed, tests are still in progress etc etc.
3. Media reports it as AMAZING NEW CANCER BREAKTHROUGH, WE CAN NOW DETECT CANCER EARLY.
4. Scientist cries and drinks.


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

[User] ELI5: Why did computer cases and monitors change from being beige/white to being black?

[Assistant]
For the first decade-ish of PC's existence they were considered serious machines meant for business and utility. If you had one at your house at all it was it shoved in your home office or somewhere else out of the way.

Thanks to the Internet and some other things, the culture changed: computers weren't just serious business anymore - now they were also for entertainment and recreation. People started putting them in their rooms, their dens, etc.

Around that time the marketing departments of the various computer computer companies realized they might be able to get a leg up on competition if they started making their computers pretty as well as functional. And just like that the clunky beige boxes started to be replaced with sleek, darker designs.

TL;DR - Computers let their hair down, finally the quarterbacks noticed them and asked them to prom.


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

[User] [General Fantasy] There are widely available potions that can cure major injuries. Does this mean minor medical issues like headaches, allergies, or the common cold have been eliminated? Would a standard health potion cure my migraine?

[Assistant] One thing to note is that while healing potions often feel inexpensive to adventurers, they are very expensive in terms of the average commoner.  They do work for a wide variety of common illness and injury, but often are economically out of reach for most folks.


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

[User] [Men in Black] Is there any scientific or rational reason why as to why a "galactic standard week" is equivalent to one Earth hour?

[Assistant]
Humans are woefully underdeveloped when placed alongside most aliens - the standard week appearing so short to us reflects this fact.

Typically enough, galactic standard measurements were established by the more advanced alien species, resulting in the ridiculous discrepancy involved here.

Basically, you know how little kids have a terrible grasp of time despite understanding the fundamentals? Pretty similar.


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

[User] [MCU] What's space exploration like at the time of Infinity War? Is man on Mars yet or what? Colony on the moon? Rovers on Titan? Subs in Europe?

[Assistant]
Its only been something like ~~10 years~~ 5 years or so since the general public learned that aliens even existed. Thats not really a whole lot of time to set up manned missions to anywhere, even if there was interest.

And there wasnt, since that general first contact took the form of a violent invasion  not from space, but through the conduit of a space-time portal generated on Earth, through a stolen cosmic artifact.

The prudent first measures to be taken in the aftermath of such a contact would be to shore up your defenses and attempt to either make sure it wont happen again or be ready when it does. That would take the form of developing advanced defensive technology (Starks suit of armor around the world), securing and containing known cosmic artifacts to prevent possible ingress through them, and trying to account for and control the enhanced human assets that proved so crucial to fighting off the first invasion. All of which were exactly what the world as a whole has been up to since New York.

Space exploration is going to be somewhat lower on the priority list here.


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

[User]
Did humans develop complex vocal chords as an accidental byproduct of evolving to have longer necks or did ancient humans slowly develop them by making enough sounds that more complex vocal chords were forced to be developed?

Did humans just get really lucky to be social animals that accidentally developed complex vocal chords?

[Assistant] Since genetic material doesn't change depending on people's activities, so vocal chords couldn't have been forced to evolve. Vocal chords, just like everything else, is an accidental feature, that stuck, because it was useful. In evolution, no feature is forced to develop.


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

[User]
[Star Wars] What would have happened if Luke joined Vader?

Personally, I think he would certainly have been justified in doing so. He's been lied to, kept in the dark and stashed away on planet desert shit hole for most of his life.

Here's his opportunity to get to know what's left of his father, learn about his gifts and have a better life.

Anyway, assuming Luke says yes, rather than throwing himself to his death. How do things play out from there?

[Assistant]
The Han Solo rescue op doesn't go as well.  It's either a colossal failure or has to be postponed until after the assault on the Death Star. (Han wasn't going anywhere, but there was a *very* narrow window for the rebels to pull off the Death Star attack)

Without General Solo on the ground, the shield generator remains up, which causes some issues for the rebels during the fighting over Endor.  Depending on how confident in victory Palpatine is feeling, he may even send Luke and Vader into combat either in the space battle (both Skywalkers being among the best pilots in the Empire), or on the forest moon, leading the force that traps the Rebels.  (IMO, he'd have Luke in space just in case being face-to-face with the Rebels might shake his new loyalty)

Although without the moon strike team being led by General Solo, perhaps Calrissian and Ackbar are quicker to bail on the attack and withdraw before the trap is *fully* sprung.

In either case, Luke's insider knowledge of the rebellion probably makes it easy for the Empire to roll them back following the defeat at Endor.

As for Luke, he probably becomes Vader's apprentice and, as Luke is still pretty raw in terms of Force use and lightsaber ability and Vader is a shadow of his former self in both of those respects, it's a toss-up as to whether they kill Palpatine, or he sees them coming and kills them first.  There is the *slight* chance that Palpatine gets Luke to kill Vader and become *his* apprentice, but if the whole father-son bond was what got Luke to turn at Bespin, it'll probably keep him from betraying Vader (at least until he's older and brings Kyle Katarn or Mara Jade on as *his* new apprentice).


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

[User]
ELI5: How does a person's body decide where fat is stored?

I understand that some people have a high metabolism and can just burn it all off. But other people can carry all their fat in their mid-section, where others have it more dispersed in other regions of their body.

[Assistant] One of the major factors is hormones. High levels of estrogen, for example, increase fat storage in the thigh, butt, breast, and upper arm regions. High levels of cortisol increase fat storage in the belly. Testosterone is a fat repellent, especially in the thigh and hips area. People with higher levels of testosterone metabolize fat better than those with lower testosterone levels. Your body's hormone levels are a combination of genetics, lifestyle, environmental, and even pathological influences.


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

[User] [The Incredibles] How would you argue the ethics of Dash being able to compete in track and field, both for and against?

[Assistant]
For: It's his natural ability, so there's no rule that prevents him from participating (he didn't dope or cheat). Everyone should be allowed to do their best.

Against:  Their's no more point in letting Dash run in these races than in allowing Usain Bolt to run in a high school track meet, or a kid driving a rocket car. Since he'd obviously win, there's no need for him to compete, and honestly nothing gained by him or the audience from his entry.


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

[User]
[Wreck-It Ralph] How fast could a Nicelander throw something?

Nicelanders move their arms to poses instantaneously due to the early-animation nature of their game. If a Nicelander was in Game Central or another game with more proper physics, would they be able to throw something incredibly fast?

[Assistant] No. The frames are reduced, but so is the framerate. I.e. 2 frames of animation at 20 fps is the same as 6 frames at 60 fps. In game central with better animation they would still be moving at the finite speed they were, we would just see the between time.


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

[User]
ELI5: When a rocket slows down, what happens with the kinetic energy?

Getting an object to move requires energy to get it moving. But when it slows down again, where is the kinetic energy going? For a car I understand brakes turn it into heat through friction, but a rocket needs to burn its engines retrograde to slow down. Isn't that actually adding more energy into the rocket? Or if that dissipates the energy, where does it go?

[Assistant] You are completely right. When a rocket slows down it loses kinetic energy and that energy needs to go somewhere. When a rocket fires its engines it spews out a lot of propellant at high speed. When the engine is pointed in the direction of travel these exhaust gasses will get the speed not only of the rocket but also from the combustion in the engine. So the exhaust gases have a lot more kinetic energy then the rocket. This is because the rocket gives its kinetic energy to the propellant. And this causes the rocket to slow down.


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

[User] [General] What currently existing human technologies or scientific discoveries are advanced or creative enough that other intelligent alien species would likely not have discovered them?

[Assistant]
As aliens they will not be mammals so they may not produce milk. This means their smoothie and milkshake technology may not have reached the stage where they use blenders. Soon we will become renowned all over the extranet for our blends of fruit, ice and yoghurt.

Planet earth will become the galactic equivalent of a zumos juice bar.


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

[User]
[Star Wars] Are there non-Force sensitive people that still follow the Jedi religion?

Are there people in universe who follow the Jedi for the philosophy and don't have powers?  Obviously they wouldn't live at the monastery/temple, but do they exist anywhere?

I guess same question for the Sith, but in the Old Republic before the rule of two. I know the Sith had soldiers who didn't have powers, but did they care about the philosophy at all?

[Assistant] There are, yes.  Lor San Tekka  - the old guy that had the map to Skywalker's location - was actually one of their number.  No Force potential whatsoever, but an avid practitioner of the Jedi way of life.  And while it's not made super-clear, there's an argument to be made for Chirrut Imwe and Baze Malbus as well (though the latter has fallen off the wagon some).


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

[User]
ELI5: How come we always see the same side of the moon, thus it rotates around its own axis at the exact same speed s it rotates around the earth; and do moons of other planets behave the same way?

If not: what makes our moon different?

[Assistant]
Lots of moons, but not all of them, exhibit the same behaviour.  It's a phenomenon called "tidal locking", and how it works is a little complicated.

Essentially, the parent body exerts tidal forces on the satellite which cause it to bulge in certain directions.  If that body is rotating in the corotating reference frame of the two bodies (meaning if you can look at the world as though neither is moving and still see the satellite spin), that will carry the tidal bulge out of alignment with the gravitational forces, so they'll drag it backwards.  Over a very long time, these effects add up, until the satellite is rotating with the same period as its orbit.


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

[User] ELI5:how are these millions of refugee migrants are coming up with the money to smuggle themselves out of the Middle East into Europe?

[Assistant]
FFS they're not stone-age indiduals. Most of them lived like you or me with a middle class job, earning enough to support themselves and their kids. A lot of them have iPhones and laptops and whatnot.

Imagining you're from a 3'rd world country, hearing about the glorious wealth and no wars of the 1'st world, paying money for a free card to luxury seems like a bargin I'd imagine.


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

[User]
ELI5: Why graphic card's processors are faster than the "normal"?

If it's faster then why wouldn't we have a CPU that is at least as fast as the graphic card's one

EDIT: sorry I couldn't write "than the machine's normal CPU" in the title:(

[Assistant]
GPUs can only carry out very simple instructions.... but they often have thousands of cores, meaning they are very good at the type of calculations where it's possible to break it down into thousands of simple sub-parts and work on them all at the same time - this is known as "parallel" processing.

This makes them very good at certain types of problem, chiefly at drawing things (although there are other problems that can be solved with GPUs too).

But most problems require a much wider range of capabilities than a GPU has, and aren't suitable for doing in parallel. That's the kind of thing CPUs are good at.


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

[User] ELI5: Why we usually see ourselves in mirror much more "beautiful" than in photos?

[Assistant]
This is because we are far more used to seeing ourselves as a mirror image, in a mirror. When you look at a picture of yourself your face appears backwards to you, and because it is unfamiliar you like it less than the way you usually look to yourself.

This is the same thing that happens when people hear a recording of their voice. You go around hearing your voice distorted by your head your whole life, so when you hear what you sound like to someone else it sounds way different than you thought. This tends to unsettle people.


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

[User] How did chemists explain reactions before the discovery of the atom?

[Assistant]
To put it bluntly, they didnt. The first attempts at explaining the states and reactions of matter led to the postulates that theorized the existence of the atom, so they were mutually dependent. Reactions such as fire and the creation of alloys were found empirically, but never studied like they are now.

There were early theories as to what composed matter, such as the idea that all matter consists of fire, water, earth, etc. But such theories never tried to explain reactions other than saying that things were how they were.


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

[User] ELI5: What is the overall goal/point of google deep dream?

[Assistant]
Google deep dream was developed as a test of Google's image recognition software.  Basically, they're running it backwards - rather than taking a picture of a dog, and asking the software "Is that a dog"; they take a random picture and ask the software "show me what looks like a dog".  By seeing what the software draws, you can determine what characteristics it uses to determine a dog.

For instance, back in the early days of image recognition, the department of defense thought they'd trained a computer to recognize tanks in pictures.  It turned out they'd actually trained the tank to recognize sunny days, because the tank pictures were all taken on a sunny day, and the no-tank pictures on a cloudy day.  Google deep dream, for instance, discovered the Google Image recognition thinks dumbbells have a human arm attached to them.

Then they released it to the public because it makes cool pictures.


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

[User] ELI5: why do so many celebrities not wear underwear to important events?

[Assistant]
Women don't want the line of their underwear to be visible when they wear a dress that is going to be photographed six hundred times. They want to look perfect, have the media talking about how they "owned" the red carpet. Any imperfection means they get less attention.

If they are going to be a disaster, they at least want it too be a BIG disaster.


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

[User]
[Star Wars] Why do so many Jedi turn to Sith masters when they know that, by definition, it will only lead to misery and death?

The Sith practice a brutal system where the master *must* be killed by the apprentice or the apprentice will be killed by their master or someone else, all for the greater goal of creating an individual who will have more power than their master to pass to their apprentice.

The Sith doctrine emphasizes passion for power, most notably wrath, hate, depression, and overall misery.

Why would anyone other than those desperate for power (Such as Anakin trying to save Padme or Darth Nihilus trying to be immortal) choose to follow Sith Teachings?

If a Jedi was stifling under the Jedi Order, why would they join the Sith when they could just use their powers to be an awesome bouncer on Nar Shadaa and party every night, or a similar rebellious action to takeout their frustrations with the order?

[Assistant]
Because you don't see the hook until it's already in you.
Jedi don't just up and decide to turn Sith.  It's a path of deception and seduction that leads you towards it one tiny, apparently reversible, step at a time.  Always just a little farther telling yourself you just need to learn this one thing and then you can turn back until you find you've actually passed the point of no return long ago, and you're so beholden to your master that the only way out is to become more powerful and kill him.


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

[User]
ELI5: Why have all major cell phone games fallen into the same categories and are basically the same game with a different coat of paint?

I noticed this recently. Whether it's Star Wars and the Marvel Champions fighter, or Clash of Clans and Dungeon Keeper and any number of other games, nobody seems to be doing any kind of innovative gameplay. There is such a big audience, why not develop all kinds of different games?

EDIT: And are there any developers who have bucked this trend?

EDIT: Thanks for all the great answers. I guess it was kind of what I figured, but there are a lot of nuances to the industry that I wasn't aware of. Cheers.

[Assistant]
No protection for creators of mechanics in games. Candy Crush is Bejewled which was probably something before that, Angry Birds is Crush the Castle, etc.

Lack of curation by Apple, Google , Amazon, they just let any shit on their service so long as they are taking a cut and can market "One million Apps Launched"

Most players are not "gamers" most gamer culture knows these games are shit but its not the target audience. Your mom is, not kidding.


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

[User] [SpongeBob SquarePants] Why does Mr. Krabs call Squidward, Mr. Squidward, but not Mr. Tentacles? For that matter, why doesnt he call SpongeBob, Mr. SpongeBob?

[Assistant] Squidward is a man, therefore deserves the respect that comes with. SpongeBob is a kid, and while he deserves respect as well, not enough to be called Mr. That's why Squidward was promoted to manager, because it requires a man. Otherwise it'd be called kidager.


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

[User] [Marvel] What radioactive creature would Spider-Man need to be bitten by to have the largest strength to body weight ratio?

[Assistant]
The strongest animal on a pound for pound basis is the orbatid mite, coming in at 1180x its weight (with the dung beetle, the old champion being 1100x).

Spiderman is stronger than he should be pound for pound, but if we scale is current str.

A jumping spider (what spiderman is supposed to be) can hold around 170x its body weight.

So if spiderman had been bitten by an orbatid mite, he would be in the upper lvls of marvel in terms of raw physical power.


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

[User] ELI5: 'Colon cancer','breast cancer', 'prostate cancer'... Do cancerous growths never originate in muscle tissues like arms or calves?

[Assistant]
Cancer that originates in muscle does exist, but it's rare. They are called soft tissue sarcomas. About 3% of childhood cancer is rhabdomyosarcoma. In the US, that translates to about 350 cases per year. It's more common in children as they are rapidly growing, and it's the rapid growth of muscle makes it more common.

Muscle itself is a pretty cool thing -- mostly a bunch of long fibers coated in this sheath that's a bunch of cells that have fused together into a giant single cell. That sheath is what builds new muscle when the muscles are damaged or growing. In children, this is frequently active, but in adults, it only "switches on" in the presence of chemical that activates the cells - and that only happens as a response to local damage. Without the signal, they simply never divide -- they can't. Cells where cell-division is deactivated don't tend to change into cancer cells -- cancer being the name we give to cells where the division process goes off the rails.


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

[User] [Star Wars] In an emergency how many Rebel Troops could the Millennium Falcon safely evacuate?

[Assistant] For a short lift (say, to orbit where the Falcon transfers personnel to another ship) perhaps fifty or sixty. For a hyperspace jump or long travel where they're reliant on the Flacon's life-support, it's probably best to keep it to a dozen at most.


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

[User] ELI5:How does Antivirus work?

[Assistant]
I expect others will chime in with more detailed answers but for an ELI5 it works in a few ways.

Firstly it scans for programs people have identified as viruses/malware.  A virus may be a file on your computer or it may be just a part of a file on your computer the virus has modified.  These are scanned everytime a file is opened from the hard disk.  Because a new virus may be found and added to the database your computer also needs to be scanned periodically to make sure nothing slipped through the net.

Secondly it detects suspicious behaviour.  For instance one program editing an existing program on your machine is rather dodgy.  There are a few applications that would do this (think AppStore or Updates) so if you exclude those anything else attempting to do that is likely dodgy.

In order for virus scanners to detect viruses it needs to make sure it gets priority over everything else which is why they usually get a bad rep as this low level tinkering/invasive scanning slows machines down and can do rather annoying thing like giving false warnings.


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

[User]
[Terminator] If the T-800s come from an assembly line and all look alike, why does Reese wait until it is about to kill Sarah Connor to be sure it is a terminator? Wouldnt he recognize it by its appearance?

Maybe he has to be sure he doesnt kill the future governor of California by mistake?

[Assistant] Not all T-800s have the same tissue appearance. The one sent back to kill Sarah was a T-800 model 101. Even though we don't see other models, the fact that this one is labeled indicated there would be other models of T-800. Reece was likely not familiar with model 101.


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

[User] ELI5: If flies don't bite, why does it hurt when they land on you?

[Assistant] While some kinds of flies do bite, what you're likely feeling is the hairs on their feet that can be irritating especially to sensitive skin. Flies have adhesive pads on their feet called pulvilli that consist of tiny hairs that have spatula-like tips. These hairs produce a glue-like substance made of sugars and oils that help them stick and can irritate some people's skin.


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

[User]
Should residential rental investment be disincentivised?

Across the world, investing in residential housing as an investment is extremely popular. So much of people's wealth is tied up in housing.

Are there any disadvantages of this? Should residential renting be disincentivised?

[Assistant]
Should is not a thing economics can tell you about, but here we can also talk the trade-offs present in a policy proposal so that you can decide what trade-offs you think we should make.

When an "investor" buys a house the purchase price of housing is expected to marginally increase but when they go to rent it out the rental price of housing is expected to marginally decrease. So, what actually changes when we allow investors to buy housing to rent out? The person who gets to live in the housing unit. Do you have some reason to prefer that the, on average, relatively well off get to utilize some random house instead of the, on average, relatively less well off?


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

[User] [Harry Potter] What if a pregnant animagus gave birth in their animal form?

[Assistant]
Animagi temporarily vanish their human bodies, including clothing and held objects, when they transform, and carried babies are the same.

A pregnant animagus effectively becomes not pregnant until they turn back, so they can't give birth in their animal form.

That said, don't do it. It's not good for the baby.


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

[User]
[The Last Airbender] what does blue fire symbolize?

for example, Princess Azula fire blended blue flames. why was her's blue?

[Assistant]
Blue fire in ATLA is supposed to be hotter or more intense.

Also it is related somehow to Lightning, which is said to only be usable by those who have complete control of their emotions (and as such, Zuko was not great at it). For Iroh, this was achieved via meditative balance. For Azula....well, having zero conscience, she's not really conflicted by much. Not hard to be in control of your emotions when you have none except a singleminded ambition to rule. So it's implied this also affects her firebending, causing it to be blue and more dangerous.


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

[User]
When a material is cut or broken, where exactly is the separation happening?

Does the break happen at a molecular level or is it at a larger scale? I know the atoms aren't spring but do molecules break apart?

[Assistant]
Depends on material:

When you break ice, you break the Van der waals bonds between molecules.

When you break a metal, the metal is all atoms bound by metalic bonds so you break metal to metal bonds.

In some ceramics, the ceramic can be thought of one big molecule, and you are breaking molecules. (Ionic and covalent bonds)

In some you can be breaking between molecule thick plates.

In polymers, you can think of a polymer like a sphagetti. Each individual strand is strong but connections between them are weak. You are most likely pulling apart the strands, not breaking them. However some may have very long strands or interconnected ones. In those cases you are breaking the molecular bonds.

In all cases the crack is likely to follow flaws in the material (or weak points).


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

[User]
ELI5: Why are almost all boats white?

There are so many colors of cars and planes, just figured boats would follow in their footsteps.

Edit: Thanks for the feedback!

[Assistant] Ever notice that the line on the side of the road is white while it is yellow down the middle? That is because in fog it is vital to see the edge of the road. White shows up better in fog. White boats don't hit each other as much in fog, then.


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

[User]
ELI5: Why do large buses not have seat belts included in them?

As a frequent rider of public transportation, I have become curious why, unlike most other vehicles on the road, why they don't require seat belts on them. I feel like they would be more dangerous without them but I honestly don't know.

[Assistant]
Imagine hitting a basketball with a baseball bat. Now hit a bowling ball with the same force of the bat. You'll probably notice that the basketball will travel further.

Now, throw those two balls at the same speed at each other. You'll notice the bowling ball does not change much in terms of speed or direction after the impact.

The basketball in this case is a car while a bus is the bowling ball. A bus is usually 10 times as heavy as a car. If it gets hit by a car, it's so heavy so that it doesn't move much at all. Thus, the passengers won't move around the bus too much so seat belts are not as necessary.


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

[User]
[End Game Spoliers] Was Thanos about to.....

When Thanos got the nano IG and was about to snap before Captain Marvel intertrupted it, was he going to snap out ALL of life there?

Based on his previous conversation with the trio, he said he was thankful that this all happened because he now knows what he must do, which is to basically create a new universe with all new life.

My other questions are.... would he have survived snapping out all living things? Would he have kept his army and black order alive? If not, then what about his daughters?

[Assistant] Yes, his intention was to shred the universe to its atoms and rebuild it from scratch, with himself as its god. Only he would have survived, and while he might have created people similar to Gamora, Nebula, and the Black Order, there would definitely have been a Star Trek Transporter issue about whether or not it was really them.


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

[User]
If gravity is caused by the bending of space, why doesn't that mean there is a fourth dimension (or something similar) for space to bend into?

In every video I have seen about space-time, they always explain gravity by the "bowling ball on a sheet analogy" where space is a huge sheet and placing a massive object on it causes space to bend and other objects to be attracted. There is a similar analogy when explaining wormholes - a sheet bends so much that two points are touching.

What I don't understand is how the 3d spacial dimensions can bend and remain three dimensional. Doesn't bending imply that there is another dimension that is being bent into so to speak? (If you bend a 2d sheet, you are entering a third dimension)

My guess is that this comes down to a misconception of space-time, but this has still been on my mind a lot recently.

Thanks for any input!

[Assistant]
>Doesn't bending imply that there is another dimension that is being bent into so to speak?

Nope. At least, not necessarily. The mathematical framework we use to describe curvature is perfectly capable of doing so *without* assuming that there is a larger space in which the "object of interest" is "being curved". It's just that all of our *experience* with curvature comes from curved two-dimensional surfaces of three-dimensional objects; that's all we ever encounter in our day-to-day lives, and that's the sort of thing that our brain has evolved to "visualize". But there's no reason *in principle* that there must be such a larger space; specifically, the geometric description of spacetime curvature given by the general theory of relativity works perfectly fine without assuming such a larger space exists.

[edit]

I want to add that if you *do* want to insist that the curvature be "in" another dimension, probably so that it "looks" like what we're familiar with, then in a lot of cases you'll need significantly more than just one extra dimension.


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

[User] [Kids Next Door] How did Delightful Children make Nigel permanently bald?

[Assistant]
It was never canonically stated *what* exactly happened, just that the DC made Nigel bald before he joined the KND.

However, given the kind of world C:KND is, you could probably imagine the Delightful Children did something like "transfer Nigel's hair-growing to a balding adult (Father?) with some advanced helmet device" or "suck out the hair follicles of kids with good hair and turn them into hair growth pills for evil adults" or something along those lines. Probably more like the former, given that perma-baldness might require a special device.


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

[User] What is the purpose of pointers in C/C++? What benefits do they provide?

[Assistant]
Benefits compared to what?

Pointers are needed for any piece of code that need to dynamically allocate some amount of memory (since it needs to track the location of the allocated memory which may change from one run to an other depending on how much it needs to allocate and how much has already been allocated.)

An alternative is to simply never allocate memory and only use static buffers everywhere (which is unpractical for big and complex program).


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

[User]
ELI5: Why are some skills "use them or lose them" but others are kept for life?

How is it that I can ride a bike for the first time in 10 years with ease, but I can't math myself out of a paper bag, even though I completed multiple calculus classes in college?

[Assistant]
These are stored as different types of memories in different areas of your brain.

Riding a bike is an example of a procedural memory which is essentially muscle memory that is largely done unconsciously and automatically by your brain.

In contrast, how to solve higher level mathematics is a declarative memory, similar to memorizing a phone number. These are facts that can be declared that you have to consciously remember. In school, all youve been taught is to memorize math as a series of facts (memorize this pattern of integration, etc.) and once those facts stop being useful you wont hold onto them in memory anymore.

If you made a career out of mathematics, though, it is probably less likely you would forget how to solve problems, even after taking a break from it. It is also a lot easier for you to learn calculus the second time around, which is probably the true purpose of learning calculus in schoolnot to hope that you memorize all the facts past graduation, but for you to learn the reasoning behind it.


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

[User]
ELI5: Can you put an electron in a nucleus?

I'm thinking the negative charge would attract more protons and allow a larger nucleus and thus a larger element.

[Assistant]
This is what happens during the formation of a neutron star. If the pressure gets too high, the electrons get "captured" by protons in the nucleus and create neutrons in the process.

Electron capture also happens in radioactive isotopes as an alternative form of decay.


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

[User]
Have you ever had a really terrible research experience?

I made a new reddit account to ask a question similar to my current situation. I am a second year undergrad and am finishing up my first research experience. My mentor was awful. He was gone for most of the summer, dodged questions. Right off the bat there was a lot of miscommunication. Combined with my anxiety and also poor (but growing) communication, things turmoiled into chaos. I am meeting with him next week to hopefully form some closure and leave off on a better note.

Everyone I talk to seems to be having great research experiences, but the grass is always greener on the other side. Have you ever had a terrible research experience? What was it? Did it leave a defined mark that affected your future, or did it become a blip of the past?

I am in the heat of the aftermath now. My future "feels" hopeless, though I know things will get better, but it would be some motivation to hear others with similar experiences.

[Assistant]
I've had research experiences which ended with the cops citing the pi for breaking the law and the pi making the undergrads cry.

... So yeah, bad experiences exist. The most important thing is that you can learn from them. In your situation, maybe you've learned to advocate for closer supervision, or more one on one support. Or maybe you've learned to be more independent, or take failure in stride.


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

[User]
ELI5: why doesn't an airplane reach its destination quicker when traveling in the opposite direction of the rotation of the earth? (Think: walking with or against a treadmill)

If the earth is spinning my destination towards me while I'm flying towards it, it seems like I'd get there quicker.

[Assistant]
Because the air, in which the aeroplane is flying, is (kind of) moving around with the earth as the earth rotates. The speed of the aircraft is basically the speed it moved through the air.

(The reason for the "kind of" is because the air doesn't move exactly with the earth. Any difference between how the air moves and how earth rotates is what we call wind.)


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

[User]
ELI5 Why did RAM doesn't have writing cycles like the SSD do?

Isn't they're using the same chip?

Sorry for my bad english.

[Assistant]
OP's question is "Why doesn't RAM have a lifetime write count like SSDs do? They use the same chips, right?"

This is an insightful question, and OP should be commended for it.

The answer is no, they don't use the same chips.

RAM stores data in banks of paired transistors and *capacitors*, a type of electronic component that is designed to be filled and emptied over and over, but requires a constant power source to keep it alive.

A SSD, on the other hand, uses something called "flash memory," which is made of a different kind of transistor that can hold onto electrons -- hold onto data -- even when no power is applied to it. In order to do this, though, the disk has to push electrons through a highly-resistive layer, which eventually wears it down. Capacitors have no such resistance, and so don't suffer this problem.


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

[User]
CMV: There are only two genders in Humans

Sex determination is genetic: males and females have different chromosomes.

XY chromosomes and maleness develops.

XX chromosomes and femaleness develops.

Some creatures such as various plants and fish do not have a fixed sex. They can change sex based on genetic cues during corresponding life stages.

Humans cant do that.

So, a transgender person who transitions will still be a genetic male or female based on their chromosomes.

For the record I believe every human deserved to be treated equally and without prejudice.

I dont think that Trans Women (who transition from maleness) should compete in sports against women.

It mixed martial arts for example the size of the person, their musculoskeletal system is male even after transitioning. This gives them an unfair advantage.

India has a third gender, which is neither male or female and it a catch all term for all non-binary individuals.

To put it bluntly, there are those who ejaculate, those who menstruate and those who do neither (due to transitioning).

However, I believe that deep down, even after transitioning they are still genetically male (xy) or female (xx).

My view is based on science and logic and does not factor in mental health or personal choices.

And again, I think all people on this earth should be treated equally and with respect.

Change my view.

[Assistant]
The crux of the issue here is this:

>Sex/Gender

Your CMV is that there are only two genders, but after you say this, the rest of your post is about sex. In fact, the next time you mention gender is to say:

>India has a third gender, which is neither male or female and it a catch all term for all non-binary individuals.

Which directly contradicts your CMV. Did you instead mean to argue that there are only two _sexes_ in humans?


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

[User]
[Star Wars] What percentage of people have been off planet?

Did most people stay on the planet they were born on for their entire lives? How accessible was transport to a different planet? This likely depends on the planet and its relative wealth, similar to differences in how many people have left their home country at some point in the real world, either for work or vacation, based on their wealth and demographics.

[Assistant]
People seem to move planet much more often and easily than moving elsewhere on their own planet. I'd say it's about the proportion of people who travel to different countries for work or fun from our universe.

We see in Andor that tourism exists as does interplanetary trade on an individual level. It's not all freight pilots moving shit around, sometimes people go places to get stuff.

I'd say it's probably about as hard and common to leave the planet as it is for your garden variety American to leave the US.


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

[User]
[Star Wars] Why doesn't the Executor have redundant command and control systems?

When the bridge of the Executor is struck and destroyed by a rogue A-Wing, the ship immediately veers off its present course and its orbit collapses into the surface of the Death Star.

Why isn't there a backup system to prevent this? Surely the designers of such a large and advanced warship would have understood the value of redundancies so that the ship doesn't immediately become helpless if the (small, exposed) bridge is damaged?

[Assistant] I would posit that, normally, a super star destroyer wouldn't be so close to a gravitationally-strong object like the Death Star. It lost power, but before commands could be transferred elsewhere, it was claimed by the gravity well of the station.


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

[User] ELI5: Why do some electronics use all 3 prongs to plug into the wall, but others only use 2 (based on US wall sockets and electronics)?

[Assistant]
The third prong is the ground, which is used as a 'safe exit' for power -- particularly you'll find grounds on higher power devices, particularly those with metal enclosures, as they'll want to be able to ground a short circuit, should a wire inside come loose and make contact with the shell.

This could prevent you from getting a nasty shock from a broken microwave, for example.


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

[User]
ELI5: How did the solar system begin spinning?

In class right now and my professor just glossed over it and I am confused.

[Assistant]
So the solar system began as a ball of gas, with some point in the middle.  Eventually, the gas began to coalesce under the force of gravity towards that point in the middle.  All of the gas particles were moving around that middle point... some were going clockwise, some going counterclockwise, etc.  Just by random chance, more were going one way than the other... let's say more were going clockwise.

As gravity sucked everything in, the speed of these particles increased.  Ever see a figure skater pull their arms in and they spin really fast?  That happened to all of the gas particles.

Since more were going clockwise, the solar system ended up with a clockwise spin!  All due to some random motion of particles and then gravity speeding them up as it pulls them in.


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

[User]
[Doctor Who] How come the Doctor thought he was the only Time Lord?

Pre-50th Anniversary, the Doctor was always swanning on about how he was the last Time Lord. So did he forget that his granddaughter was a quick flight away?

[Assistant]
There are a few hints that he went looking for Susan in his Ninth incarnation and couldn't find her. A short story also suggests that he might have tried again in his Current incarnation.

We don't know what has become of her. She may have been summoned or taken back to Gallifrey or something.

The post-timewar version of the universe is separated from the pre-timewar version due to the time lock on the war itself, and there are times. places and people - including other Time Lords - who are simply in timelines that the Doctor cannot access any more.

Now that Gallifrey is back, it is possible that its re-emergence may have triggered yet another version of the universe to supercede the  last, and make further time-lines inaccessible - whilst possible opening some that had previously been locked.


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

[User] eli5: Why does there continue to be water in a river, even though it doesn't rain all the time in the upper parts?

[Assistant]
It's called base flow.

Basically there's a bunch of water underground. It seeps into the rivers. So, usually it's a combination of the water cycle and base flow. But when the water cycle is interrupted (drought), the base flow is still running.

So you get lower water levels, but still running.


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

[User]
[Marvel/DC Comics]Has a major hero or villain ever really, truly died and never come back in any incarnation?

Heros and villains die all the time. But it seems like it always turns out that it was their long lost brother, or a robot, or it just *looked* like they died, or someone they inspired replaces them, or someone uses a godlike power to revive them, etc. Has any important hero or villain ever really and truly died and never come back in any form? Events happening in alternate realities notwithstanding, of course.

Edit: I should specify, omit characters that have died recently, say within the last couple of years, as they may not have been resurrected yet but are likely to be in the future.

[Assistant]
Ted Kord, Jonah Hex, Eric Masterson, Doctor Light, Skurge the Executioner, a good chunk of the original JSA (Johnny Thunder, Doctor Mid-Nite, Mr. Terrific, the Sandman, Starman, the Atom), Johnny Quick, Max Mercury, the Phantom Lady, Pantha, Wildebeest, Kid Devil, Richard Fisk, Emperor Vulcan, Charles Xavier, Madelyne Pryor, Lian Harper, Uncle Ben, Captain Mar-Vell, Genis-Vell, Omega Red, Adeline Kane, Wade deFarge, Tommy Monagahn, Brainiac 8, Terra...

I could go on for a while, man.


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

[User]
"Can we have two entries in a page table to point to the same page frame in memory? Why or why not?"

I tried answering this question myself: " Yes, we can. Allowing 2 entries can share data, modify code, and memory space can be saved. However, whoever access it and change it can affect others copy;"

However, I am unable to answer the "why or why not" part:  why can we allow 2 entries.....?

 Pls let me know if you have an answer. Thank you!!!!

[Assistant] You answered your own question while asking it: to save memory. You don't need 500 copies of libc in memory for your 500 processes. In cases where changes could impact others' copies, this is where techniques like copy-on-write come into play.


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

[User] [ZOMBIES] If a pregnant woman transforms into a zombie, what happens to the baby?

[Assistant]
It dies from lack of nutrition. Assuming it's a reanimated dead type zombie, it's the same as if a normal mother died.

A baby inside a Rage zombie would survive as long as the mother could take in nutrition and didn't bash it around to much. Still dies sooner or later, at best it would last to labour and fail to be born.


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

[User]
[Wreck-it Ralph] What happens if two Fix-it Felix machines (or other arcade machines) are in the same arcade?

Would you have two Ralphs? Two Felix's? etc?

[Assistant]
Yes. This sort of thing is also known to happen with humans. They're called identical twins. It can get confusing sometimes, but it's generally not a huge deal.

Edit: It's also fairly common for a single cabinet to have several identical people in it. Again, not a huge deal.


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

[User] ELI5: Why did the Nazis give the strong and healthy people who arrived in the concentration camps work instead of just killing everybody upon arrival?

[Assistant]
To fuel their war machine.

look at it like this, if you have a bunch of prisoners making ammo and digging for metals then your normal population can enlist into the military or doing more complex work.


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

[User]
[Agents of SHIELD/MCU] Who is paying the SHIELD agents'/researchers'/engineers' salary post-HYDRA?

You could argue that Coulson, May, Fitz, Simmons, and Skye would do it for free, but we also see a fully staffed base throughout season two.

Even if they aren't getting paid, someone still has to pay for their food.

[Assistant]
Reappropriation of Hydra assets goes a long way toward keeping the base running.
That's why it was tough keeping the bus fueled at first, but as they regrow and gain operational capability, it gets easier.
In a pinch, there's also merc-work they could do that wouldn't necessarily be mission conflicting.
Also, Fury's toolbox probably contained information about reserve assets for just such a situation.


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

[User]
[Star Wars] Is experience the best teacher for a Jedi/Sith?

Even without additional formal training, Luke Skywalker progressed significantly between ESB and ROTJ, albeit he is a special case -- son of the Chosen One.

For a less special example, Cal Kestis managed to go from struggling with the Second Sister, to besting her in a duel.

Therefore, is experience the best teacher for a Jedi/Sith?

[Assistant]
To some extent, yes.

But strength in the Force isn't the most important thing for a Jedi. Wisdom is. In one sense experience is the only way to really become wise, but that's a long process. A master is important because they can impart their own wisdom on their padawan.


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

[User]
Why are folks living in urban areas more likely to be liberal?  Conversely, why are people in rural areas more likely to be conservative?

It's not a secret that the more heavily populated an area in the United States, the more likely the residents will vote for a liberal.  Just look at any election by county, it will be speckled with "red" and "blue" areas that generally correspond with the metropolitan areas.  There is obviously some connection between population density and political inclinations.  What is that connection, and why does it exist?

[Assistant] Just a guess but living in town, seeing public transport, infrastructure, it's a reminder this is a team effort. If you live in a rural area, you have to be more self reliant, it's easier to think fuck everyone else.


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

[User]
ELI5: When the Arthritis Foundation states that "losing just one pound can take up to 4 pounds of pressure off of each knee", how is it possible that one pound can equate for eight pounds of pressure?

Gravity?

[Assistant]
Leverage and impact.

If the knee sat still with a weight rested on top, it would only ever experience that weight (1 pound). However, the knee actually get more stress than that. When supporting weight bearing on it to lift the body from a lower position, like stairs, it experiences more force because of the body being behind it being pulled up and over. For a time, it also bears the whole weight of the body frame instead of just half (like you would standing up).

Also, when you walk or run, there's an impact force pushing on the knee that is more than the force of just holding up the weight. The faster you move, and faster the knee goes from loaded to not loaded, the more force the knee experiences.


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

[User] ELI5: That temporary "watermark" on our vision when we look at something bright then either look away or close our eyes?

[Assistant]
The color-sensing cone cells in your eyes need time to "recharge".  When light hits those cells, special molecules absorb the light and are forced to change shape, which activates the nerves in your retina.  When you stare at a bright light, your cone cells are all firing, all of those molecules are getting bent, and when you close your eyes they're stuck bent for just a short while and continue activating your nerves.

The longer you stare at bright light, the more cones are activated and don't have time to fix themselves.


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

[User]
What causes clouds to be grey or white?

Ive always wondered, how come some clouds are dark grey, while others are bright white?

Dark grey clouds are usually associated with rain? What makes rain clouds different from normal clouds?

[Assistant] They have more water vapor in them. Rain clouds are dark for the same reason theyre rain clouds- theyre much more dense. They displace/block more light, thus the darker color; and the water vapor is condensed enough to turn to create an ice nucleus, which more water condensed on until it becomes heavy enough to fall, thus rain.


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

[User]
[Marvel, MCU] If Doctor Strange teleported Thor's hammer into the mirror dimension and Thor called it back. Would the hammer come back to him?

Would the hammer travel through different dimensions or would it be stuck in the mirror dimension.

[Assistant] There are many holes in dimensions, we see in Thor 2 that it's quite capable of orienting itself despite some dimensional issues. That said, he's probably not capable of overpowering Mjonir if it decides it doesn't want to leave through a portal. If it couldn't find a way back to him it wouldn't sense a call to return, and wouldn't come back.


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

[User]
[LOTR] How is Gandalf able to use one of the Elven Rings of power, even though he is not the intended bearer nor is he an elf.

Additionally, how did he even come to acquire the ring? Was it passed down to him or did he find it somewhere? Just looking for a little more clarification!

[Assistant]
The whole "Three Rings for Elves, Seven Rings for Dwarves, Nine Rings for Men" thing only refers to who happened to end up with which Rings. Originally, they were all (except the One Ring) made by and for the elves. But there's nothing to prevent anyone else from using a Ring of Power if they got their hands on it (again, except the One Ring, which fully belongs to Sauron and which would require immense inherent power and force of will for anyone else to master.)

Celebrimbor made the Three Rings, but did not keep them. He gave one to Galadriel (whom he greatly respected and felt some degree of unrequited love for) and sent the other two to the High King Gil-galad. Gil-galad kept one of the Three (which he later passed on to Elrond), and gave the other to Cirdan, lord of the Grey Havens. When Gandalf first arrived in Middle-earth his ship docked at the Havens, and Cirdan was able to sense the Wizard's hidden greatness. He suspected Gandalf would need a Ring of Power more than he would, so he gave up his Ring.


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

[User]
Why are our lips darker than the rest of our skin?

Just found myself wondering this, not really sure why this is.

[Assistant] The skin on our lips is thinner than the other skin on our face. This allows blood vessels to be more visible and for the lips to appear darker. In light skinned people, fewer melanocytes in the lips  = less pigment so the contrast is usually more prominent.  In those with darker skin, more melanocytes are present, so the color contrast is less because there is more pigment to conceal the color from the blood vessels.


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

[User] [General Sci-fi / Fantasy] Why do warrior societies tend to have a "whoever kills the leader becomes the leader" rule? Why not something more pragmatic, like "whoever kills the leader's killer becomes the leader"?

[Assistant] One thing that's usually hidden is the 'unspoken social contract' of how and when you can challenge someone to become leader.  It isn't just that the leader was killed, it was that someone was bold enough, confident enough, and strong enough to actually do the challenge.


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

[User] ELI5: How come people get brain damage after 1-2 minutes of oxygen starvation but its also possible for us to hold our breath for 1-2 minutes and not get brain damage?

[Assistant]
Brain damage happens when the *brain* is starved of oxygen.  When you hold your breath, your heart keeps beating and blood keeps flowing, bringing oxygen to your brain.

Hypothetically there's an amount of time where if you could hold your breath for that long, you *would* start to deprive your brain of oxygen, as you deplete the oxygen left in your lungs and blood stream.  Realistically you'll pass out and begin breathing again before you get to that point though.


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

[User]
Cooling a hot room with a fan and a window.

Say you're in a uncomfortably warm room, the window's open but there's not much air movement.

If you put a fan in front of the window will the room cool down faster if the fan is pointing into the room (to blow cool air into the room) or pointing out (to blow hot air out of the room)?

Secondary question, is doing this any better than just pointing the fan at me? The aim here is to cool the room down.

[Assistant]
Both of those are better than pointing the fan at you.

Keep in mind that the fan creates undirected suction on the back, so it draws air in from all over the place - even in front of the fan.

If you place it in the window to blow air in, the further out the better. If you place it in the window, blowing out, it'll take some of the outside air, and blow it straight out again.

The stream of air that the fan creates in front of it, is highly directional, and pulls in more air around the airstream. If you place the fan as far away from the window as possible, it'll pull hot air into the airstream as it passes through the room and out of the window.

There is no one true best place, but with this knowledge, you'll be able to find the best solution for your room.

Overall, the good options are:

* in the window, blowing air at the farthest corner of the room

* in the farthest corner of the room, blowing air out the window.


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

[User] eli5: Why is it that when you accidentally bite your lip or your tongue while eating, you are now destined to bite that same spot over and over for sometimes days on end?

[Assistant] It tends to swell which makes it easier to bite again and again. It's also more painful, so you're more likely to notice when you DO bite it. Finally, if there's mechanical/habit issues with the way you chew or contributing factors from the shape and positioning of your teeth, you might have a natural predisposition to bite that area.


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

[User] I once heard a Language teacher tell me that a reason colder countries tend to be more advanced is that they have to advance their civilization and technology to cope with the cold. Are there Sociological studies supporting it?

[Assistant]
Recommended reading: Guns, Germs and Steel.

Cold countries did not really advance because of the cold, but rather because Eurasia is a huge horizontally spread landmass with TEMPERATE climate.

Cold would actually be a hindrance since people do nothing in the long winter months.


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

[User]
ELI5: How do two devices on the internet agree on a transmission rate?

Im teaching a high school intro to computer science course and this question came up, but I cant find an answer at the very low level that were talking about.

We know that the most basic level of the internet is a wire with an electrical current. You can set or read the wire voltage as high or low, and interpret that as 0 or 1. The only way to consistently send/receive messages is to have an agreed timing protocol of when to read and when to set the wire.

But in the real internet, devices all communicate at different connection speeds...so there are clearly multiple timings. How is that decided? Ideally at the physical/binary layer.

The best I can imagine is sort of like radio systems, where theres a default channel (timing in this case), and then on that channel you both agree to change to a different frequency. That would also explain why transfer rates fluctuate during the same connection or download, since a computer could be switching timings several thousand times a second if it was needed for the best speed. But can anyone verify that this is an accurate analogy?

[Assistant]
Across the Internet they don't sync up transmission rates. The Internet is packet switched, there is no direct connection.

One device sends data in packets, which is received by a router, and then retransmitted to another router, and so on until it reaches the intended destination.

Generally speaking Internet protocols have to be tolerant of packets not arriving with consistent timings. Or even packets not arriving or being corrupted along the way.

It's only necessary to sync up with with the device that's the next step along the way. So your PC has to sync up timings with your router, and your router has to sync up with your ISP.


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

[User]
[That 70's Show] How did the gang fare going into the 80's and 90's?

How did the decades following the 1970's go about for the residents of Point Place?

[Assistant]
Red passed away in 1989, the tragic victim of a heart attack induced by Don Majkowski. Kitty ended up in a retirement community in Florida. Laurie has never visited. Eric brings his family every year as part of a Disney vacation. He has an ordinary wife, two ordinary kids, and an ordinary job in some town close by Point Place. He shares a morning coffee and/danish with Officer Kelso every few weeks. He doesn't listen to Donna on the radio though - she's the #1 drivetime host in Milwaukee. Fez & Jackie moved to DC where Fez works for the Parents Music Resource Center and Jackie hosts fundraisers. Hyde was last seen headed west and Kelso secretly hopes he never sees him again.

Randy was murdered and his body was never found.


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

[User]
How does Hegel's use of the term "phenomenology" differ from its usage in 20th century phenomenology?

I'm new to the history of philosophy. I know a bit about Hegel and the phenomenological tradition that proceeds Husserl, like Heidegger, Sartre, etc. I can tell that, for instance, Husserl and Hegel mean different things when they consider phenomenology, but I don't know enough to really understand what the fundamental differences are.

[Assistant] One of the most salient differences is that Hegel conceives his phenomenology as a progressive process that involves different stages whereas 20th century phenomenology is a method of describing a phenomenon. One is diachronic, the other is synchronic. The two also have different aims so they mostly just share the fact that their main concern is phenomena. Hegel calls what he does a "phenomenology" because it is concerned with a progressive set of experiences of consciousness (the way the world appeared to us in different configurations of rationality). Husserl named what he did a "phenomenology" because he wanted to develop a science that'd explain the structures that rule the way things appear to us.


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

[User]
[Batman] How does Bruce Wayne build the Batcave? Seems to be way too much work for two people, even if one of them is Batman.

Specifically things like the long bridge the Batmobile drives across in BvS.

[Assistant]
He is a eccentric billionaire, he probably hired people to do the tunnel and the long bridge and said it was for security purposes or secret sex escapades. Once finished it was tested with some sweet custom car.

They all had to sign a non-disclosure contract and that's it. When they made it there wasn't bat stuff besides guano in there.

Maybe it was all people from his company. Lucius Fox was probably involved.


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

[User] ELI5: The Paradox of Thrift.

[Assistant]
When everyone saves their money instead of buying stuff, demand drops (because nobody is buying stuff) this causes the economy not to grow which means nobody is making much money so overall less money is being saved because people are getting less money to save.

So even though more people are saving, less is being saved.  That's the paradox.


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

[User] ELI5: How do sleepwalkers know where they are going or what they are doing when their eyes are closed?

[Assistant] You don't have to have your eyes closed to be sleep walking. Most don't, actually. Often times it's just a state of being semi-awake, where you can go about doing things but you memory or higher reasoning functions are asleep or dillusional.


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

[User] ELI5: Most of my money is a number in a bank database. What is there to stop a bank artificially inflating someone's number?

[Assistant] It is not just 1 number, it's the sum of a transaction history that is cross-referenced to the various accounts that put money in or took it out of your account. If you just made one number bigger, the whole thing wouldn't balance and that would be picked up by the auditors/accountants.


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

[User] [Star Wars] With almost no one to train Luke, is he really a guy with the skill level of a Youngling masquerading as a Jedi Knight?

[Assistant]
In some respects, yes.  For example, his saber skills, around the time of his duels with Vader, are rudimentary at best.  He was thoroughly outclassed in their duel on Bespin, and he needed a dark-side-infused frenzy to beat Vader in their duel on the second Death Star.

However, because Luke had such strong potential in the Force, he could basically make up for his shortcomings in skill.  For example, when Luke was storming Prince Xizor's palace along with Leia, Lando, and Chewie, he found that if he let the Force simply flow through him and guide his actions, he could easily deflect the blaster bolts Xizor fired at him.  (Xizor was notably stunned that anyone could possibly be that fast)

After the Battle of Endor, Luke more or less had to re-teach himself all of the lost knowledge from the Jedi of ages past.


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

[User] ELI5: Why can you hear the voices in the apartment above you so easily, but not the voices in the apartment below you?

[Assistant] Because sound travels through the solid medium ( the floor slab). On the floor above, people are directly in contact with the surface; while on the floor below, you're only depending on the noise traveling through air and noise traveling in air is divided into reflected, absorbed and transferred, major percentage of which, is reflected.


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

[User]
[DC] How strong is Batman compared to your average Amazon or Parademon?

Like Batman ranges alot so how strong is he generally?

This isn't a who would win but more does he need to prep for the Average Amazon/Parademon or can he breeze through that with ease?

[Assistant] Batman wins fights with much stronger people/things because of technique and intelligence and often equipment, not because of raw strength. An Amazonian can out-lift him, but even the best of them is going to have trouble with him in combat.


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

[User] If I attached my feet to a machine that moved my legs for me, and then took anesthesia. Would my body be burning calories or gaining muscle while I'm unconscious?

[Assistant] Nope.  Movement doesn't cause calories to be burned, burning calories causes movement.  Think of it like putting a car in neutral and rolling it down a hill, or towing it with another car, it doesn't burn any gas to move in those cases.


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

[User]
[DCU/Marvel] What makes the citizens of the Marvel Universe so hateful to their supers, especially compared to the DCU?

Both universes contain their fair share of good and evil, along with a lot in-between. Yet, it seems as if the MU almost always hates super-powered individuals, no matter what they do in service for the regular joe.

Meanwhile, over in the DCU, a vast majority of people adore and look up to their heroes. Sure, there is still discrimination and prejudice against them, but it seems comparatively tame.

So, is there an explanation for why each universe has a different general opinion on supers?

[Assistant]
I'd say the presence of Superman himself.

For a half century, he's been a strong symbol of powered beings.  He's represented "Truth, Justice, and the American Way" and reinforcing that *our* ideals are great enough that even a superpowered being would venerate them.  The citizens of the DC universe could always look to him and see an example of a good powered person that they understand and shares their values.  Some people dislike or fear Superman, but he's had a long time to win over the average person.

In the MCU, Cap was powered during WWII, but lost shortly after.  The average person never met him, only a small number of veterans and scientists.  The citizens had no experience with powered people for a long time.  When they suddenly started appearing in the 80s and 90s, it was already a scary time, and seen almost as a disease.  It was a time when the drug epidemics were growing, the AIDS epidemic was peaking, the internet was emerging.  Just as they saw AIDS as punishment for being gay or drug addiction as a weakness, they saw being a mutant as wrong or weird.  They saw it as a problem, not as a power.  The number of powered people in the MCU, not to mention alien invasions and gods. The world was changing too quickly for people to be comfortable with and they lashed back.


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

[User]
I hope this isn't a dumb question. I am taking ekg classes to further my education, and one lead on the machine I am using is the "ground". My question is this: what is the natural "ground" for the electrical activity in the heart?

Everything I have learned about closed electrical systems has come from working in an automotive shop for 15 years, and replacing or installing electrical outlets in my home.

I do understand how the heart works, chemically and anatomically. I just can't seem to understand the grounding part. I have a BSN, but this was never touched on that I can recall. Google gives me nothing, no matter how I ask.

Edit: google, rrrrrr.

[Assistant] One thing I'd like to add is that voltage is used to measure a *difference* in potential. When you have circuits measuring change in potential caused by something like the heart, they need to compare this change to a baseline value. This value is often called ground, allowing different parts of the circuit to know how the input (or other components) potential is changing.


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

[User]
[Superheroes] Why are most heroes geniuses?

as far as i know, it seems like every hero ever is a super genius, smart enough to go to a special school, or knows over 600 different martial arts. why cant they just be a normalish dude/dudette that got superpowers? Yeah theres heroes that arent geniuses and dont have any formal training, but i think theyre the minority?

[Assistant]
Not *every* superhero is a super genius. It's just that the most exceptional ones are. Why? Because the stronger you are, the more attention you attract from those super geniuses seeking to either remove you from the board, or take advantage of you.

Most of the superheroes who were notably powerful yet normal-ish in intelligence typically *lose* to those super geniuses, even if they are significantly weakerbecause in a world of superpowers, you can hire other super-powered individuals to do the dirty work for you, if you have the right amount of money and influence.

There's still normal-ish heroes/villains out there, but they are in the minority because most of them tend to *die* fairly quickly.


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

[User]
[Aliens] Why does the newborn acknowledge Ripely as its mother?

I never understood the whole Queen/ripely reproductive process. In Alien resurrection, the new born brutally kills the Queen after she gives birth to it. Surprisingly,  it has human characteristics. Why does it acknowledge Ripley as its mum if the Queen gave birth to it?

[Assistant]
'Ripley' was cloned from the hybrid DNA created by the retroviral alien infection that would have eventually gestated into a queen alien and hatched out through her sternum. She was an unwanted byproduct.

The intent was not to clone Ripley. The intent was to clone the queen, allowing them unlimited access to that genetic retrovirus. (Queen lays eggs, eggs incubate virus in facehuggers, facehuggers implant virus in host, host gestates alien.) Because their genetic material was hybridized by the virus, they had to make several attempts to get a viable product from the cloning. 'Ripley' was the second to the last attempt. The last attempt was the queen herself. But the progeny of the queen still had some of Ripley's genes, and therefore, her progeny can see and sense Ripley using the same pseudo-telepathy they have evidenced time and time again to stalk and ambush their prey.

This means that, yes, the aliens did not kill her because their sensory apparatus tells them that they are descended from her. The reason the humanoid alien kills the queen alien, is because he lacks the pseudo-sensory apparatus. Instead he has eyes. He can tell what is human and what is alien.

It's the eyes. If it had been born without eyes, it would have been unable to distinguish between Ripley and the Queen Alien also.


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

[User]
ELI5:Why do we get brain freeze?

While eating a big bowl of ice cream I got a brain freeze, and I was wondering why we get them? Mine also appear in my right eye and never "in my brain" for some weird reason.

[Assistant]
When you eat a cold food, the nerves in the roof of your mouth constrict because of the cold. When they expand back to normal size, the blood flow starts coming back, and that's what's known as "brain freeze". All it is is the roof of your mouth returning to normal temperature.

Pro-tip. Push your tongue to the roof of your mouth, and it will recover quicker, meaning shorter brain freeze.


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

[User]
How does baking soda absorb/remove odors?

For example in the refrigerator/freezer?  Other things I've heard from my mother is to sprinkle on carpet before vacuuming, and it will make the house smell better and keep the vacuum bag from smelling.

How does this work?

[Assistant]
It's acid-base chemistry.

Baking soda is an amphoteric substance, which means it can act as both a acid and a base.  Many odor-causing compounds, either acids or bases, react with it to form a less volatile salt, which reduces the observed odor.

There is also absorption effect, small molecules can diffuse into the porous solid and they have difficulty diffusing out.


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

[User] [Star Wars] The Sith tradition is to train an apprentice who eventually disposes you (supposedly strengthening each generation of new Sith), but did Palpatine want to be killed and replaced?

[Assistant]
I dont think its as much they want to be killed and replaced as much as keep their own skills sharp.   A wise Sith master doesnt teach his apprentice all he knows so he always has an advantage.

The master has an apprentice to do their bidding but a good fighter needs someone to train with and challenge them to stay sharp.

If the apprentice ever gets strong enough to kill you, you have him assassinated or ambush him at an opportune time.


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

[User] ELI5: Why is it that Iron is the worst element to a star? Why is it that it causes the end of a star?

[Assistant]
Elements can be divided into two categories. The first category contains elements that require outside energy to push together (fusion) and give off energy when they split apart (fission).  The second category is the reverse, giving off energy when they fuse, and requiring extra energy to sustain fission.

Heavier elements, like plutonium, tend to be in that first group. Lighter elements, like hydrogen are in the second. The dividing line falls roughly at Iron.

Since stars are basically giant fusion reactors in space, they can run on everything fusion produces, up to Iron. After Iron, they aren't getting enough out of the fusion to keep the cycle going. And so the reaction stops.


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

[User]
What keeps magnetic domains in alignment?

In the production of permanent magnets, it is known that heating the metal up and then slowly cooling it down in the presence of a large external magnetic field will align the domains and they will stay in line creating  a permanent magnet.

What is it that stops the domains from scattering after they are cooled down in the same way that the domains scatter after a normal piece of metal is removed from a magnetic field?

[Assistant]
In these materials you need energy to randomize the magnetization, the aligned state is energetically favorable based on the properties of the atoms and their crystal structure.

You can provide that energy by e.g. heating the material above its Curie temperature, then the material will lose its magnetic field.


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

[User] Why do snowflakes exhibit a 6 fold symmetry?

[Assistant] Water crystallizes in a hexagonal unit cell  (the smallest repeating pattern in a crystal), and crystals tend to take the shape of their unit cells, much like sodium chloride makes cubic crystals that match their cubic unit cells.


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

[User] ELI5: What is happening memory-wise when someone says "if you hadn't asked me I would have been able to tell you."

[Assistant] A little older than ELI5 version: It's a state of knowing psychological phenomenon where there is a self-reflective knowledge of the memory's existence, but the pathway through which that memory needs to be accessed and articulated is unavailable for some reason.  The context where the fact in question is brought up is different than original context and brain pathway when the memory was forged.  You can't recall it because you aren't accessing the right memory pathways, and you can't consciously change these locked-in pathways in that moment.  You need an extra stimulus to provide information or you need to wait for a time where your mind wanders and let's your creative meandering merge with your memory to find it.


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

[User] ELI5: how touch lamps work.

[Assistant]
It detects changes in capacitance, just like the touch screen on most cellphones.

Capacitance is a fancy way of saying that since you and the lamp both contain electrons which can flow around free inside you but which don't transfer to the lamp, touching the lamp changes the amount of electrons that the lamp could hold. Since the lamp is connected to a source of electrons changes in capacitance cause electrons to flow in or out of the lamp when you touch it which triggers the electronic switch.

Anything that has some capacitance can change the equation and trigger the switch again which is why you can turn on the lights by poking your cat if your cat is touching the lamp.


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

[User]
My student isnt taking the hint...help please!

Hello all! Apologies for typos and weird formatting as I am posting from mobile.

I teach theatre and have a student in my class who I can tell is very well-intentioned but also very insecure. I can tell that she does not read social cues well and is likely relegated to the category awkward girl over there. I have no idea if my student is neurodivergent or not, but some of her behavior in class makes me think she might be.

We had auditions for staged readings (low stakes, we try to cast a ton of people so everyone gets a chance to perform) and she asked me if she should audition. I told her that she should as it would be likely she would get in and we need lots of actors. This turned into a twenty-minute series of verbal jousting as her anxiety took over and all logic went out of the window. I have never, EVER told a student to not audition before and I said this to her as an option because the thought of auditioning gave her an incredible amount of anxiety.

While Im sure she does not intend to be anxious, the emotional labor I have to perform to attempt to alleviate this students frequent crises and anxiety is wearing me down. It was so bad that on Friday, I bolted to the bathroom immediately after class so she couldnt corner me in the 15 minutes I have in between classes to keep stating her insecurities.

I dont want to push this student away and alienate them as I can tell they may not have many resources, but Im just worn out and its only March.

Totally open to any tips, tricks, and ideas on this one.

TL;DR: My students anxiety is causing me to perform an exhausting amount of emotional labor. How do I set better boundaries without feeling bad as she is likely neurodivergent?

[Assistant] Especially if this person isn't paying attention to boundaries because of neurodiversity (vs, say, being self-centered or confused about school or alone) then letting her know directly that you do not have time to discuss extra-curricular things after class would be helpful. Folks with autism spectrum minds tend to be less good at hints! It would probably also make sense to schedule an office hours meeting with this student so that you can then forward her to the school counselling service.


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

[User] ELI5: How are underwater tunnels built?

[Assistant] There are several techniques, but the most common way is to make concrete rectangles, like a box with no top and no bottom.  Then you lay the rectangles on the bottom of a trench across the river bottom, making a rectangular tube.  Then you bury the tube and pump sealant into the seams.  After the sealant cures, you pump out the water.


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

[User]
ELI5 : How come forging doesn't seem to have improved since the metal ages ?

I'm a huge fan of "forged in fire" and it seems to me that technology hasn't done a great job of improving this craft. I mean except for things like a power hammer, how is it possible that we're not able to control a quench.

There are so many "castrophical failures"from what seems to be competent bladesmith. I don't understand how in 2020 there are still variable in that process that we are unable to control.

I'm french so sorry in advance if there are error in the text.

[Assistant]
Things like forged by fire and other hand crafted forging is more for the novelty than practicality.

There are modern ways to make knives for example, but they don't make good TV shows or collector items.


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

[User]
When we visit other moons or planets in the search of life, how do avoid bringing bacteria or other microorganisms with us?

What if we do, and the microorganisms essentially become invasive species?

If thats the case, then how would we tell the difference between an organism from Earth and an organism that had its origins on the celestial body were studying?

[Assistant]
This is actually a large issue NASA has had to deal with. It is an international law that all spacecraft must be cleaned to avoid contamination.

They use a variety of compounds and radiation to kill microbes and bacteria but the unfortunate thing is some microbes are very, very hardy. Some bacteria love radiation and NASA even found that a bacteria was surviving in one of their clean rooms by consuming one of their own cleaning products. It is virtually impossible to remove all life from the surface of an object.

Current NASA standards are up to 300,000 spores from the exposed surface of a landed spacecraft and a maximum density of 300 spores/m^2. There are also zones on mars that are quarantined from all spacecraft and extraterrestrial life to avoid contamination.


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

[User]
[Doctor who] What exactly is the nightmare child?

I have known about its existence for a long time but I've never actually bothered to find out what it is and for some reason I kind of want to know now.

[Assistant] If you're asking that question, then you couldn't possibly fathom the true horror of the Nightmare Child. The existential angst of all those who might have existed, who could still exist but don't. The unborn of all space and time. People think the "Clockroaches" that straighten out paradoxes are the worst consequence of muddling about with the timeline. Those people haven't seen the Nightmare Child.


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

[User] ELI5: Why is everyone not one race? & Why we look different?

[Assistant] Populations were isolated and unable to pass mutations between them. Different mutations were favored in different places as well. Gradually these mutations built up, both beneficial and benign, into racial differences.


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

[User] Famous Philosophers/Philosophical works that deal with Competition?

[Assistant]
Nietzsche wrote a lot about what could be considered competition to some extent. A lot of his morality/ontology (not sure which youd consider it tbh) is based around the concept that life is will, specifically the Will the Power. This means very roughly that the driving force in life is to maximize its potential as much as possible. Since different wills conflict, there is competition in nearly everything (including the human psyche).

For example, in section 14 of the Gay Science he writes Our pleasure in ourselves tries to maintain itself by again and again changing something new into ourselves; that is what possession means. To become tired of some possession means tiring of ourselves. When we see somebody suffer, we like to exploit this opportunity to take possession of him; those who become his benefactors and pity him, for example, do this and call the lust for a new position that he awakens in them love; and the pleasure they feel is comparable to that aroused by the prospect of a new conquest. So for Nietzsche, even love is a conquest, which of course requires at least a bit of competition.

Point being, if youre looking for a philosopher whos really into competition, conquest, domination and the like, Nietzsches probably your best bet.


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

[User] ELI5: Why do humans subconsciously move body parts to music?

[Assistant] Music is very ancient for humans. Music was developed before our language centers were fully developed. We were making flutes before we could call it a flute. Our brains are hardwired to respond to a beat. Tapping your foot is just one way your brain responds to the beat.


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

[User] [physics] what happens to atoms when they are extremely crammed together like in black holes or in neutron stars? Are the orbits of the atoms overlapping each other?

[Assistant]
Atoms don't really exist in either of the situations you named.

In a black hole there's no way to know what the matter is like since no information can escape the event horizon, but general relativity predicts that all of a black hole's mass is packed into a single infinitely dense point called a singularity, which is nothing like any kind of matter we are familiar with.

A neutron star is made of closely packed neutrons with a density similar to an atomic nucleus. It's almost like one gigantic nucleus, it's not composed of many separate atoms.


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

[User] ELI5: Why don't some planets in our solar system orbit the other way around the Sun?

[Assistant]
Try to imagine the solar system before there was even really a star. There would have been a cloud of material flying all around. If everything was very random, then very little would have enough speed to avoid being sucked into the newly forming star. If some things had a velocity in one direction and other things had a velocity in another direction, then they would likely end up dragging on each other, slow down, and get pulled in.

What we think happened is that as the sun was forming, it acquired a spin and that spin ended up transferring to the cloud of material, shaping it into a disc which eventually would collect together to form the planets. Without this spin, the material would have just fallen into the sun and it would have burned a little bit brighter.


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

[User]
eli5: Why do oil/gas places have big towers with big flames burning?

Such as refineries and oil rigs.

[Assistant] These are flair stacks. If there is any kind of leakage in these places they need a safe place to vent the gas that is leaked. You can not just vent this gas into the atmosphere because it can be quite poisonous, explosive and a strong greenhouse gas. So the solution is to vent it through a fire where any bad gasses will burn into harmless ones.


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

[User] What is the relationship between the rate of change of a function and differentiation?

[Assistant] The derivative of the function f(x) with respect to x is a function whose value at x = a is the rate of change of f(x) at x = a with respect to x. In other words, the derivative and rate of change of a function are essentially synonymous.


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

[User]
Eli5: the lack of biped land animals

When dinosaurs roamed the earth there were many species that were bipedal and were strictly land based. Now only some mammals and a handful of birds are strictly biped. Why is this?

[Assistant] First of all, birds are dinosaurs. Second of all, the quadrupedal mode of movement has advantages over bipedal in terms of stability, agility, and power. In order for bipedal modes of movement to win out, you need to make quadrupedal movement disadvantageous or impossible. One way to do that is to evolve delicate, sensitive, hands and an upright posture. Another way is to evolve the forelimbs into wings that cannot be used for walking as opposed to bats who can crawl with their wings.