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

[User] [Terminator]If the T-1000 had been successful in killing the T-100, Sarah and John at the end of T2 what would it had done afterwards?

[Assistant]
The Terminators were launched back in time with no method to achieve further mission details from SkyNet and no way to communicate success or failure back to SkyNet.

In that context they are a desperate last-ditch effort to stop the Human Force's success during the final battle.

It is unknown if secondary objectives were programmed into the Terminators, no mention of secondary targets are made in the canon films, and their singular focus on John Conner seems to suggest that secondary targets may not have even been provided to them.

In the first film the Terminator was not even sure how to even begin to find the "correct" Sarah Connor and was just destroying all of them in a comprehensive manner.

If they had any data about Secondary targets, it makes sense that they would go after all of those Secondary non-defended once they hit any kind of defense or snags and discovered that John was defended (Since SkyNet was destroyed before John reactivated the time machine, it had no idea that there would be any defender's going back in time to try to save John), thus it would be up for thee Terminator in the field to perhaps make that judgement call.

Where-as the Terminator in the first film shows little adaptation, and acts more like a sledgehammer brute-forcing all of the situations, the T-1000 is more subtle and creative, but also doesn't engage in any attempts on undefended secondary targets while pursuing Connor, perhaps suggesting that he had no other significant mission details.

Additional mission details if Connor is destroyed may not have even been handed down by SkyNet and instead would be a matter of personal creativity.

The T-800 would probably find a cave and stay out of history's way until after Judgement Day, and return to SkyNet for additional orders.

The T-1000 would probably continuing impersonating authority figures, and pursuing potential mission goals, since it was presented as being more autonomous and creative and wily.


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

[User]
Does DNA ever get tangled?

When chromosomes are condensing, does DNA ever get tangled up, preventing the chromosomes from condensing?

[Assistant] Yes, of course. Like an old phone cable, DNA tends to tangle like hell. There are special enzymes in the cell nucleus called topoisomerases, which basically breaks and rebuilds DNA in specific locations to prevent tangling. (This is more of a ELI 5 version, though.)


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

[User]
ELI5: What is in the center of the galaxy?

Also what makes all the stars spiral around it. Also if are galaxy is a apart of a greater orbit of like a super galaxy or if thats possible?

[Assistant]
More than likely a supermassive black hole.  This is what pretty much everything in the galaxy orbits around.  We cant see it directly but from our observations of other similar galaxies we can assume ours is pretty much the same.
Also our galaxy is part of a larger group of galaxies called a super cluster.  They dont orbit anything specifically but are held close together by their gravity.


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

[User]
[Kung Fu Panda] Why not use Tai Lung as a Jombie?

In Kung Fu Panda 3, we see that the villain Kai has Tai Lung on his little belt of captured warriors. This makes sense as presumably the Wu-Xi finger hold from the first movie sent him to the Spirit Realm, where Kai confronted him and captured him.

But if Kai can resurrect dead kung fu masters as his Jombie warriors, why didn't he ever use Tai Lung, as opposed to, say, Master Porcupine? It's established that Tai Lung has more Kung Fu talent than almost anyone else, so why not send him in? Is there are particular reason his skills were not applied?

[Assistant] If you watch the battle, Kai had to excerpt some degree of control over his Jombie's to make them battle and did get some form of shock when they were damaged.  Tai Lung may have been too difficult to control due to his combat style or get damaged to frequently to make it worthwhile.  Or Kai may just not have been all that impressed with him when they fought and he captured his chi so he put him on the back burner.  Tai Lung was one of the only masters there that Po had defeated so it might have just been better not to deploy that known quantity.


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

[User]
ELI5: Why are most librarians required to have college/advanced educations?

As a frequent library user, I always found it curious that librarians required bachelors and/or masters degrees. From the end user perspective, they mainly sit at a front desk and answer basic questions or help customers find books.

What exactly do they do that requires a four year degree?

[Assistant] A library technician (the job you described) usually does not require a college degree. A librarians job is different. A librarian curates and manages a collection, organizes resources, and manages finances among other things.


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

[User] ELI5:How do "smart bombs" work? Specifically, how are they guided to the target if they are simply dropped from a plane.

[Assistant]
There are a number of different guidance systems for "smart bombs" but one of the most common uses lasers.

Basically the bomb is released from the plane, and it has sensors in it that constantly scan the ground looking for a laser marker at a specific frequency. So after releasing the weapon, either the bomber aircraft itself, or a support aircraft, will shine a laser at the target.  The weapon then "sees" this laser and attempts to guide itself to where the laser is shining.

Strictly speaking, most laser-guided ordnance are missiles rather than bombs, as they usually have the ability to use propulsion systems to change their course.

Laser-guided missiles are extremely accurate when tested under ideal conditions, but in practice their use is often curtailed due to smoke, low cloud, or even the difficulty of keeping the laser permanently shining at the target during the weapon's flight.


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

[User]
ELI5: Do animal mothers in the wild immediately know what sex their offspring are?

Was just watching a documentary about a tiger and her cubs, and the narrator mentioned that litters tend to be 50% male and 50% female.  Does the mother know this right away?  Or does the offspring have to develop more before she can tell?

[Assistant]
They kind of don't have to because it's not really that important at that stage. There might be some odd exceptions within some species, but in general the wild animal momma thinks "baby" rather than "boy baby" or "girl baby", and cares for either just the same.

Later on when it's older, and depending on whether there's some sort of gender-role in a group society that the young male or female must fit itself into, there might be differences in care that are provided. But at the start they're all nurtured the same.


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

[User] Do insects like bees and ants have freeloaders who don't do their share of the work but obtain the advantages of living in the community?

[Assistant]
Drones in a honeybee colony do not do any work for the colony. They do not gather pollen and nectar, do not feed brood, do not care for the hive in any way. Their only function is to consume resources, then fly out and attempt to mate with a queen from another colony.

They are not bringing any resources or genetic diversity into the colony they live in, and therefore may be "freeloaders" by definition. However, they are providing genetic diversity to other colonies by passing on the DNA of their queen to other colonies.


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

[User] ELI5: why does my nose get so used to a smell that I can't seem to smell it after being in the room with it for a few minutes?

[Assistant]
it's not your nose, it's your brain. your brain is permanently filtering data which it classifies as "not necessary at this moment". if that smell doesn't change your brain decided at one point that this smell seems to be normal - and normal things are not really important, normal things will not harm you or at least you know how to handle these things. your brain is focused on unexpected, unusual things which might be dangerous.

it's the same with a continuous, never changing sound - first it seems to be annoying, loud as hell and everywhere, a while later you don't hear it anymore.


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

[User]
[Last Airbender] the guy with the three Eyes

Where are his powers from? Is that some kind of bending?

[Assistant] It's a very specialized type of fire-bending, not unlike blood-bending or metal-bending. Known as combustion-bending, instead of producing open flames the bender channels chi energy through their Light Chakra and projects a beam of super-heated energy that explodes on contact. It requires a great deal of focus and a mastery of chi to be able to pull off, which is why it is so incredibly rare.


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

[User]
ELI5: How exactly do prisons make money by having more prisoners?

I keep seeing/hearing about for-profit prisons and people making comparisons to how it costs more to put someone through prison than college, but this goes against basic logic in my head that to house, feed, and clothe, bathe, etc. A person is more of a loss than a gain.

I've done cursory Google searches, but turn up mostly articles that are too jargony and beyond my current level of understanding..

Who is giving money to prisons and how/why are they getting profits? Any peripheral knowledge that can help me understand would be helpful too. Thank you!

[Assistant]
They get paid by the state per prisoner. The more prisoners the more money they make.

> A person is more of a loss than a gain.

They're not. They get paid more to house that person that it costs to house them. If they didn't it would be completely pointless for a company to run a prison.


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

[User]
ELI5: What are the black rope-like things sometimes put on roads across lanes? Are they counters? How do they work?

Not sure if this is everywhere, but in the US occasionally these small ropes are affixed to the roads across the lanes.

I guess they're used for traffic counting or something but I don't know how they'd work. Like how does it know how many axles you have? or what happens if two cars drive over the rope at the same time? Or what determines how long to leave it?

[Assistant] Yep. Those types are usually hollow rubber hoses sealed off at one end and attached to a pressure sensor at the other end. When a car drives over the hose it increases the pressure in the hose slightly triggering the counter to go up 1. If two cars go over at the same time it will probably count it as only one, but the frequency of that happening is low enough that they'll still get a good idea of how much traffic is going by.


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

[User]
[The Hobbit] How powerful was Radagast?

So it was shown that Radagast could at least hold his own aganist one of the nazgul, even if he was the weakest of the wizards he still must be very powerful. Why wouldn't Gandalf want him to come with him into dol guldur? I understand he wanted him to go send for help, but couldn't he have sent a message though a moth or other means? Surely 2 wizards is better than one.

[Assistant]
In his pure form, Radagast is a powerful Maia, a being of awesome, reality warping power compared to an angel or a minor god. However, once embodied, Radagast's role in shaping the world was to be a gentle and subtle gardener of the woods, and a caretaker of the lesser creatures of Arda (just like Gandalf's role was to inspire and motivate Men, Elves, Dwarves and Hobbits to fight against evil).

If the Radagast were to truely take off the kiddy gloves and go brawling, he would ruin his mission. It was more acceptable for Gandalf to break the rule of non-interference when Men/Elves/Dwarves are not looking, but Radagast did not promise not to interfere, but rather not to harm, so going nuclear on some wraith-ass would violate the spirit of his vow, unless it was strict self-defense or immediate defense of others.


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

[User]
Why water?

The majority of all power plants uses some sort of energy source to heat up water. It is then the water vapor which turns the turbines that produces electricity.
Water is also a compound has an extremely high heat capacity (requires an incredible amount of energy to heat up).

**My question is this:** Why not use a compound which has a much lower heat capacity, and therefore requires a lower amount of burnt fuel to vaporize it?

Thank you!

[Assistant]
There are many advantages to using water versus another substance in power plants: water is cheap, unreactive,non-combustible, easy to dispose, readily available, non-toxic, etc. There is no other substance that offers all of these beneficial properties.

Secondly, although water has a high heat capacity, this property isn't as detrimental as it may appear. When the steam condenses back to water after turning the turbines, it is pumped back into the system to be re-used. Thus, only a small amount of energy must be supplied to re-boil the water, and water's high heat capacity is irrelevant. Since the water also releases it's heat of vaporization when it condenses, this heat can also be partially recovered, as well. Therefore, using a substance with a lower heat capacity would not offer a significant advantage. The high heat capacity of water also helps keep the operating temperature of the system's fluids stable.


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

[User]
[Mario] Does Mario even need to kill most of his enemies?

Most of them are very passive, just pacing back and forth or flying up and down for eternity. You could almost say that they're just civilians.

[Assistant] You could say they're civilians, but you'd be wrong.  They are called Koopa Troopas.  They're definitely King Bowser's soldiers.  Now true, a lot of them are just guards pacing back and forth, but they're on the lookout for that Mario guy.


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

[User]
[Star Trek] Why didn't the Temporal Integrity Commission of Star Fleet from the 29th-century intervened when the "Narada" a 24th-century starship showed up in the 23rd-century creating a whole new timeline?

Isn't their whole purpose to prevent exactly this kind of accidents?

They did dispatch a time travel ship to pick up the "Voyager" when it was stranded orbiting a 20th-century Earth.

[Assistant]
That particular incident (whether it be due to the red matter or the size of the supernova affecting things) created a new quantum timeline, instead of changing the past of an existing timeline as many other time incursions in Star Trek did. The difference being that the old timeline still exists - people are still running around after Spock and the Narada travelled back in time, they're just in a timeline with a different quantum signature to the new "Narada attacked the planet Vulcan" timeline.

So, the TIC has nothing to fix - the old timeline is there, unaffected, and the new timeline is now off on its own course in its own quantum area. The new quantum timeline is not under their jurisdiction - it's under the jurisdiction of that quantum timeline's TIC, if such a branch still exists in the new scenario.


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

[User]
ELI5: What are tennis players looking for when they request 3-4 tennis balls and immediately toss 1-2 of them back?

(also, go Djokovic! :P)

Edit: Thank you all for a good discussion/explanation! I hope you are all ready for the Wimbledon final! Djokovic v Federer. :)

[Assistant] To explain this to a 5 year old, essentially they are testing (for lack of a better word) the bounce of the ball. Because they hit the ball so hard they wear and tear causing the balls to bounce in different places making the game difficult. It also loses the energy that is put into the ball when hitting it. For example, when you kick a flat football it will stop much quicker than if you were to kick a fully inflated football.


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

[User]
ELI5:Why is Bill Nye considered an 'authority' on science when he only has a bachelor's degree (in science)?

He obviously is a smart guy, but I don't understand why he is always mentioned as some sort of 'science god'. How is he put on the same level as scientists such as Neil deGrasse Tyson and Lawrence Krauss, when he is more qualified to talk about engineering than science?

Dammit I have no idea how to write this out without sounding like I have an agenda. All I can say is I am curious to how this all works

edit: As I see it's all to do with his ability to be interesting. Thanks for the responses, I would wish for more detailed responses but as I can tell there will likely be no more :P

edit 2: OH SHIZZLE this blew up. Much appreciated (in reference to the answers).

[Assistant]
Very few top-grade scientists are very popular, because most scientists aren't particularly interested in political advocacy or popularizing their field. Bill Nye, Neil DeGrasse Tyson, Carl Sagan, and the like are well-known because they represented a public face for science as a whole. Think of them as ambassadors of the scientific community afforded respect as a result of that status.

EDIT: Dear god guys, we don't need the complete list of names of every scientist who has ever does public work.


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

[User]
If the Sun is around 300,000x as massive as the Earth and pulls the Earth into orbit, why aren't small objects on Earth affected by much larger objects in the same way?

Eg. A ping pong ball and a skyscraper

Edt. Thanks for the responses guys! Askscience is great :

[Assistant]
They are; but it's completely insignificant compared to the earth's gravity acting on both objects.
A very early experiment into gravity involved hanging a pair of large spheres and measuring the minute deflection caused by the gravity between them.


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

[User]
[Star Wars] Why did Han Solo and General Leia *spoilers*?

Why did Han Solo and General Leia name their baby after Obi-Wan? None of them was ever that close to him to begin with. Did they just like how "Ben" sounded?

[Assistant]
* Hero of the Galaxy
* Friend of the Family, Both biological (Anakin and Padme) and adoptive (Bail Organa)
* Trained Uncle Luke
* He delivered Leia to the Organa family
* He effectively introduced Han and Leia, dying in the process

While he was never that close with them personally, he was a huge factor in Leia's life, and very close to three of her parents.


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

[User]
Why do rabbits hop, even over short distances? Is it something about their bones and muscles, or could a rabbit be trained to walk?

I've never seen a rabbit attempt to walk.  Even if they only need to reach some grass that's just barely out of reach, they move both front legs, and then hop their back legs.

Is there something about rabbit physiology that makes them hop?  Do their bones and muscles make walking difficult?

[Assistant]
They actually do walk. It looks as if they were cats doing a stealthy approach.

I've seen them do it when they are either being aggressive or scared.

Used to raise rabbits.

I can't find a video, but it's kinda funny to watch. I've seen a line of agressive bunnies fast walking after each other so they could fight and nip at each other.


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

[User] [Pokmon] Can Ditto turn into a human man and impregnate a human woman?

[Assistant]
Probably. Ditto copies the very genetic code of the target up to and including the elements and fluids produced by that Pokemon. A Ditto that transforms into Blastoise can use Hydro Pump and if it turns into a human it should theoretically also have functional sex organs including a hot load ready for your girlfriend.

After all there's a reason Ditto can breed with every Pokemon. Interestingly Ditto uses its own genetic material when breeding. If it literally copied the genetics then any eggs created would be clones. This is why perfect IV Ditto are popular for breeders.

I guess that means most Pokemon used in competitive battles are Ditto hybrids. Filthy mud bloods.


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

[User] Does skin color affect the darkness you see when you close your eyes? E.g. is it darker for people with lighter skin color because more light is reflected by the eyelids.

[Assistant] I believe that dark skin is more opaque, and light skin more translucent. Thus the light absorbed by dark skin is stopped and actually absorbed by the material, where light skin allows light to pass through. Similar in effect to viewing through clear glass as opposed to  welders goggles.


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

[User]
[Dragon Age] Did they ever do anything with that flower that cures the Taint?

So in *Dragon Age: Origins*, one of the first sidequests you get after you've finished your character's prologue is to go into the wilds and get a couple of flowers so you can cure one of the mabari hounds at Ostagar of the Taint. Said cured hound goes on to become a party member if you're not the Human Noble.

And... that's it. No follow-up. Just "Hey, this flower cures the Taint, which is meant to be incurable death save for becoming a Grey Warden and even that only holds it off for a while." Did they ever establish anything else about this magic flower, or are we just left to believe that the cure to the Taint exists and nobody's doing anything with it?

[Assistant]
They imply that hound recovers because it was treated early.  If you advance the story, it dies and is no longer recruitable.

This makes it seem like the Wilds Flower wouldn't be helpful to a Grey Warden, most victims, or the Spawn themselves.  It seems only beneficial for minor infections or taints that are treated quickly.

Imagine that the flower cleanses up to 10% of the taint, and that it's already too late if the infection has grown beyond that point.  And it's likely an amount closer to 5%.


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

[User]
ELI5: The significance and ramifications of a Hassan Rouhani victory in Iran.

Please explain the significance of his victory, if any, for the people of Iran and their leadership's relationship with the United States and the UN.

[Assistant] Rouhani is considered more moderate and willing to negotiate with the US over its nuclear program, and what some people hope that happens is that if he can meditate with the US then the US and a lot of other countries that followed with the US, would start to back off on sanctions on iran which would improve their economy.


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

[User]
What is a phantom vibrate?

For those unfamiliar with the term, a phantom vibrate is when you think you felt your phone vibrate in your pocket, but It didn't.

Does it have any relation to when amputees think they feel their amputated limbs?

[Assistant]
Your brain thrives on patterns.  If something is close to a pattern that your brain recognizes strongly, your brain will force it to match that pattern.  Tihs is why you can raed senteencs wehre the wodrs are mxied up.  Your brain has been trained to recognize the pattern of your phone vibrating, so if some motion of your pants is close enough to the phone vibration, your brain will fill in the gaps and complete the perception.

In artificial intelligence, this is known as content-addressable memory, which is just a fancy way of saying that your brain will try to force a sensory state to a known pattern instead of perceiving it "raw".


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

[User]
[Godzilla] How can Godzilla stand at full height on the surface of the ocean?

In the newer Godzilla movies (Godzilla 2014, Godzilla: King of the Monsters 2019, Godzilla vs Kong) and in some of the Toho movies, Godzilla is seen walking or standing on the surface of the ocean at full height or close to it. How is he doing this? Is he treading water with his feet and tail?

[Assistant] Depends on where he's at. He can float or tread water for a bit but won't appear at full height when doing so. In most cases hes walking along coastal shallows or outcroppings when appearing full height at sea. 60 foot deep water is enough for most large ships to pass through without issue but to Godzilla it's puddle depth.


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

[User]
Why shouldn't one give food nor drink to a person in shock (as in trauma)?

I know that you shouldn't, but I have never got a explanation why.

[Assistant]
When a person is in shock their body protects their core functions by stopping anything not necessary for life. They need to be covered and kept warm because the blood vessels in their extremities constrict to keep their core warm. Their digestion stops including their ability to swallow. If they were to get any fluid or foreign bodies in their airways while in shock their body may not have the cough reflex.

Shock is really strange to deal with. A person going into shock may be functioning seemingly normally one moment and they can become unresponsive the next. Any time shock is suspected the patient needs to be kept warm and given nothing orally because of the choking hazard. They can choke without showing any signs of choking except by ceasing breathing. They may not struggle in the least and their breathing can just stop. Without the bodies automatic breathing help it's very hard to restart breathing in a patient that is in shock.


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

[User] ELI5: Why do some sodas (like Coke) produce a lot of foam when it's poured into a cup, from say, a can, while other sodas (like Sprite) don't produce nearly as much?

[Assistant]
the most important factor in how "foamy" a soda acts is which of its ingredients raise or lower surface tension. Aspartame promotes the formation and persistence of bubbles, as do certain preservatives.

The combination of multiple foam-promoting ingredients and circumstance is why Diet Coke reacts so energetically with Mentos candy.


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

[User]
[Transformers] Are Decepticons inherently evil? Or are they just led astray be Megatron?

I've always wondered, Decepticons seem to be, as a rule, evil! Are there any of them with any good in their matrices?

[Assistant]
In the old G1 cartoon, it's pretty much the good vs evil thing, as all they were trying to do was sell toys, with an exception here or there.
In the just recently ended IDW comics universe, the Decepticons started out as a force for change.  Megatron was originally a peaceful protester who didn't believe that a person's alt-form should dictate their life, function, career, etc.  So if a person was born/built with the alt-form of a big drill, the only thing they'd be able to do with their life is be a driller, no matter their inner desires.   Megatron wanted to change that, but fighting the bureaucracy led to escalation, death and eventually war.
A lot of the original Decepticons joined because they felt the same way as Megatron, or they were outcasts.  Eventually seedier individuals would join the ranks because they saw an opportunity to make things better for themselves.
After millions of years of all out war, the Decepticons went from a group of freedom fighter outcasts looking to change the world for the better, to an army of killers wanting to bend the galaxy's will to their own.
You could say Megatron himself was led astray by Megatron.
If you're a Transformers fan and a comics fan you should definitely check out the IDW books.  There is a lot of top notch story telling and character development there.


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

[User] ELI5 why I can't recharge normal household batteries? When they build them they charge them, so why can't I?

[Assistant] They don't charge them when they build them. The current is generated by a chemical reaction, and the batteries are built with the required ingredients for the chemical reaction. They don't build an empty battery and then charge it up. When you make a "battery" by sticking nails in a lemon, you don't have to charge up the lemon first.


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

[User]
If humanity isn't going to develop a fully sustainable method of living, then it must greatly limit and lower it population. CMV.

Having studied in depth the effects of our population level on the environment, the dangers of having too large populations on a population ecology and genetic level with the pollution of the gene pool etc and the dangers of having the whole planet living the way that most developed countries do and the oncoming climatic and environmental problems (not ignoring of course the destruction and fragmentation of ecosystems, great losses of biodiversity, deterioration of many of our agricultural land through soil erosion and loss of soil nutrients and many others) my conclusion has been that if humanity does not seriously change the way it lives, massive decreases in the current level of the human population is necessary in insuring the long term survival of our species. CMV

* Leaving in the original badly written post, but adding a clarification. Many of this systems on this planet a changing into an undesired, for us humans, state. Most of the damages are anthropogenic, or at least can be somehow blamed on humanities activities. My point is that if we do not change our methods of living as a whole, and we decide to stick to them, the only viable way is by greatly limiting the amount of people that do it. Thus, lower the population. That, or keep it as it is, while dramatically changing nearly every single aspect of the way we live. It is not the numbers of humans that count, but the amount of humans living in a fashion similar to us westerners..

[Assistant]
Thomas Malthus thought the same thing in 1798.

He wrote his "Essay on the Principle of Population" which theorized that, since population grows geometrically (2, 4, 8, 16, 32, 64, 128, etc.) and since agricultural land was limited (and, at best, could grow arithmetically, or 2, 4, 6, 8, 10, etc.) we would have to severely limit population in order for the developed world to not literally starve to death.

But, with greater need comes greater innovation. People tend to naturally limit population growth (lower birth rates in the developed world) and people have come up with far more efficient ways of farming. Malthus thought that, even with its colonies, the island of Britain couldn't fit as many people as are in London alone today.

In regions with good soil, modern farming technology can have just a few places be breadbaskets of the world, operating in a relatively small area. The Soviet Union was the largest country the world has known, and Belarus (a small part of it) supplied food for most of the union. North and South America, with greater preservation and transportation technologies, could probably feed the world on their own.

Technology rises to meet the needs of a population, so this shouldn't be much of a problem. With current technology, we could probably supply around 10 billion, easily, and we keep developing every day.


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

[User]
ELI5: How do the parasites that infect insect brains and such actually manipulate the host body's movements ?

I recently saw videos regarding like the fly that decapitates fire ant heads and the zombie ant fungus and I'm really curious what the parasite does in the brain of the host that makes them go or do what they want them to do.

[Assistant]
Screws with the hormone system (eg serotonin) .
Doesn't make the ant do things, more it changes the way the ant behaves.

EG. not make the ant climb, but make it really like the feel of sunlight so it goes and seeks that high place clear of shade.


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

[User]
[Finding Nemo] So the diver that caught Nemo in the bag was the dentist, right?

So he has a habit of taking random sea animals away from their natural habitat and putting them in his little office aquarium and giving them to his niece who has a history of killing fish by shaking bags?

[Assistant]
Yes, pretty much.  He thinks that a fish tank is a nice attraction for his office.

And since his hobby is scuba diving, he decided to have a saltwater tank and collect the fish himself to save some money.


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

[User]
How long can I reuse the same breath?

So I have a balloon like device attached over my mouth, it easily inflates when I exhale.

How long can I continue to use this device (and therefore the same volume of air) before I blackout/die?

[Assistant]
Is there any air in the device to start with?

Are you pre-breathing 100% 02 or room air?

 If it starts with 0 volume and you're an average male, that means you'll exhale ~600mL of air, since we use about 25% of the oxygen we inhale on a single breath you will have about 95mL of oxygen exhaled into the bag.  We normally use 250mL/minute of oxygen, you won't be able to extract all 95mL of oxygen because of diffusion pressures anyways, so you will run out of oxygen in under 30 seconds.  Passing out can vary wildly, some individuals can last minutes, others will last 15 seconds.  Syncope is not something we have a defined limit on for oxygenation at least, but I'd go somewhere within 60 seconds for most persons.

If you were pre-breathing 100% 02 that means you'd have 600mL of oxygen to work with.  The problem here is that you exhale CO2, and it will again screw with the diffusion pressures.  Let's work within the 250ml/min and an average rate of 12 breathes per minute.  That means we're extracting ~21mL of 02 and exhaling close enough to that amount of CO2.  That means in 1 minute you'll be at 350mL of oxygen, and 250mL of CO2, this will drastically hinder oxygen uptake within the lungs, the pp of the CO2 within your blood will actually prevent it from diffusing back across, making you acidotic and reducing the Hgb affinity for oxygen further.  Thus, you'll be unable to clear CO2, and become acidotic, this alone won't make us pass out however, until CO2 becomes high enough to make a person faint (again, highly variable, let's go with 140mmHg as a reasonable guesstimate point however.)

This of course all presumes you have the nose perfectly sealed the entire time.

If there was a way to evacute just the CO2, you'd have considerably longer, but in the case of being unable to evacute it, we're in the same neighbourhood as the original, somewhere right close to 60 seconds.


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

[User]
[Star Wars] Why did the Empire phase out all the perfectly good technology from the Clone Wars?

In ROTS, specialized clone trooper units, multiple walker types, and perfectly functional Venator class Star Destroyers were all shown late in the film as belonging to the new Empire. Why did they eventually replace these with more standardized units when they could've kept them for different situations (ex. Venators as carrier ships)?

[Assistant]
Cost-cutting necessitates standardization, and even with the assets of the Separatists seized, the Empire needed a way to pay its war debts.  When the galaxy is relatively at peace, there's no need for all that specialization.

Besides, a lot of that older equipment was getting on in years and maintenance was becoming a hassle.  Contractors went out of business, parts became out-of-stock, the sort of thing that's given engineers and managers headaches since the invention of replaceable parts.  At some point, it's cheaper just to bring an entirely new vehicle into service than to keep fixing the old one.


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

[User]
[SW Republic Commando] Are the members of delta squad bred from a different genome than Jango Fett's?

Their squad leader Delta-38 is clearly a clone of Jango Fett but the other three members have very distinctly different vocal patterns from 38 and other clones why is that? Can a clones vocal cords develop differently from other clones? Are these three particular clones bred from other genes? Are there examples of this among other commando squads or clones in general?

[Assistant]
In the Clone Wars all clones were from Jango Fett. Some batches of clones were footsoldiers, others were pilots, commandos, ARCs, and so on. This led each type of clone to develop certain personality types. Officers were raised in an environment so that they would be confident in themselves and their tactics. Footsoldiers were raised so that they wouldn't make a fuss when given orders. The ARCs were given more freedom to be an individual and we're trained personally by Jango himself and later by other bounty hunters after his death. The Commandos like Delta Squad were taught specialized skills and focused on improvisation under stress.

What's more interesting is that despite being raised in a controlled environment that each clone developed a unique personality. Batches became squads and developed social hierarchies regardless of designated rank. It was as if they craved individuality. From clone to clone subtle voice tonality was a huge difference just as other humans hear accents or see hair color. The only other humans they had ever seen growing up were clones. When the war started regulations relaxed and clones immediately began getting custom hair cuts and tattoos to identify themselves and to express individuality.

Check out the episodes of The Clone Wars that feature the Domino Squad. Their story arc covers their training, personalities, and relationships quite well despite being carbon copies of one another.


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

[User]
CMV: It's stupid to care about the environment in space.

I'm a big proponent of space colonization/exploitation and every time I bring it up there's someone who says something along the lines of "Oh we're gonna trash the Moon like we did Earth?" "Oh good more mining!" "Humanity won't rest until we've exploited everything we can!" and other snide comments to that effect.

Honestly, it just sounds like the dumbest argument to me and I wouldn't even be bothering with a CMV if I hadn't heard it so many times. *It's rocks. Uninhabitable barren rocks floating through vast chunks of literally* ***nothing****.* There's no space squirrels to worry about, we haven't found any aliens and we really have no reason to assume any are out there, let alone that they give a shit what we do to Mercury. Furthermore, you want to stop desertification or the human rights violations of cobalt mining, you're gonna be hard pressed to find a better solution than the absurd volumes of water and cobalt from here to the asteroid belt.

[Assistant]
You realize that leaving actual garbage floating around in space presents a serious navigation hazard, right?

There have been actual satellites that have been knocked out after getting struck by debris that was discarded from other launches/missions.


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

[User]
How increasing interest rates stops inflation?

Hello.

Could you explain me how increasing interest rates stops inflation, increases money value the way you would explain it to a little child?

[Assistant]
Explained for a child

Inflation happens when there is too much money in the country.

People can borrow money, but they have to pay back a bit more after some time, that is an interest.

Increasing interest rates makes people less interested in borrowing money, since they would have to pay a lot of money back.

People don't want to borrow money, so there is less money in the country.

Since there is less money in the country, interest rates helped control inflation.


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

[User] ELI5: Why are German products higher quality?

[Assistant] Germany was one of the first countries to get mass amounts of high quality steel by way of Krupp steel. This led to the development of higher precision machine tools and higher quality metal goods. This reputation has survived largely because of this history but now Germany can't compete in the cheap markets where Asian business dominates. Instead they stick with premium goods at a high price.


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

[User]
[The Matrix] What are the Potentials?

I've seen this movie a million times, I've *studied* this movie, and yet I still don't have any idea who - or what - the Potentials are.

Humans, trapped in to the Matrix still? Humans, freed but somehow continuously plugged in for some reason?

I want to say they're Machine programs, in hiding like the Oracle, but we know the there-is-no-spoon kid is living in Zion by the second film.

They can't possibly be potential-Ones, since the Oracle already knows who the One is.

Any ideas?

[Assistant] Potentials are humans who've begun to reject the Matrix on various levels but aren't quite ready, for whatever reason, to be unplugged. For most humans the process happens fairly gradually; the rebels generally let people see through the Matrix on their own before they consider them ready to leave. The ones with the Oracle, for example, are fully capable of psychic powers but don't seem to be quite in on the whole "the world is a computer program" schtick. Or the Runner from The Animatrix, who actually manages to break free on his own but doesn't quite make it stick. Neo was a special case in that Morpheus wanted him out asap.


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

[User] ELI5: On a lower gravity planet, would it be possible to jump high enough that you could injure yourself when you land? Or would it be impossible for the impact to be that severe?

[Assistant] Assuming no atmosphere, the force it takes to launch from the surface would be equal to the force of collision with the surface upon landing.  So the gravity of the planet doesn't matter - the question of whether you can injure yourself is dependent solely on the force you can exert with your legs.


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

[User] ELI5:How do glowsticks work?

[Assistant]
Glows ticks contain two primary chemicals; a base catalyst (which is used to speed up the reaction) and a dye such as fluorophor.

The small glass capsule you can see in an unlit glowstick typically contains both phenyl oxylate and the aforementioned fluorescent dye.
When you 'crack' a glowstick what you are really doing is breaking this glass capsule, which in turn causes the contained solution to enter the larger tube of the glowstick, typically filled with a hydrogen peroxide solution.

When the two solutions mix, an exothermic reaction takes place which creates the glowing light through a process known as chemiluminesence.

And that's what makes the glowstick glow!


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

[User]
[MCU] How does Thor's age work?

He looks young but has been around for thousands of Earth years. Is he basically immortal or does time just move faster in Asgard than in Earth's realm? Seems weird that a weekend in New Mexico would undo a thousand years of ass-hattery, feels more likely he's only lived through 30ish years or whatever but doesn't explain how he's been around so long.

[Assistant]
In agents of sheild there is an asgardian from odins war against the frost giant's still on earth. So they are immortal. And thor is hundreds of years old.
As to thor having all his character growth in the movies, that's because they are traumatic points in his life and they force him to grow as a person. Other wise he is a rich guy dossing about.


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

[User] ELI5 What did Albert Einstein mean when he said for us believing physicists the distinction between past, present, and future only has the meaning of an illusion?

[Assistant]
Because of Einstein's theory of relativity, there is no absolute timekeeper in the world.

What might be a past event for person A might be in the present for person B and might be in the future of person C. And there is no "correct" perspective - to each of them that same event has a different "now-ness" to it. So past, present and future events are simply constructs of our individual experience of events happening in time.


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

[User]
Could we eliminate the Flu if we all got vaccinated for the flu and wore masks during flu season?

Masks have been pretty effective at keeping my family healthy this year and I was wondering if some viruses like the flu are so endemic that there will always be substantial spread, or if mask use would be effective at isolating or eliminating the flu?

[Assistant] No, there are large reservoirs of flu in bird and swine populations. Its probably more helpful to think of flus not flu. Being vaccinated against one or a few doesnt do much if you get exposed to a different strain. Each year health authorities try and predict which strains will be the major ones.


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

[User] If the speed of light is absolute, how come it is measured differently in every medium?

[Assistant] The speed of light *in a vacuum* is constant. This is often shortened to "the speed of light" for convenience, but the distinction is important. Light does travel at speeds less than c in other media.


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

[User]
[MCU][Endgame][Spoilers] Finally watched endgame and have a few questions

Spoilers obviously you have been warned!!

>!Why did Tony snapping hurt him as much as it did? He wasnt wiping out/returning half of everyone, only dusting Thanoss army. Also why couldnt he use it to heal himself/someone else resurrect him?!<

>!At Tonys funeral we saw all the major characters but there was one I couldnt identify, the person standing behind Bucky but in front of Danvers. I know thats not a great description but I dont know of any online clips to reference.!<

[Assistant]
Using the infinity stones for any mortal is dangerous and basically to much power. It wasn't the effect that hurt him, it was wielding the power of the stones that did it.

And that person was the boy that helped Tony charge his suit in IM3.


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

[User]
[Transformers] What causes some Transformers to have genders?

As commonly seen, most TF's are the male body type but there's a small number of TF's that are female body type.

What causes this?

I've been recently thinking about this and thought the spark of a TF is similar to our souls. What the spark chooses to be, determines their body type. Is this true?

[Assistant] (In regards to originals.) Humans, actually. Normally Transformers don't have gender features, as they are an asexual species. While by default, they naturally take a masculine form, it's their interactions with humans that make some like Arcee take a feminine form. Mostly for aesthetic reasons.


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

[User]
ELI5: Why is polyester often added to cotton cloth, even if only in tiny few percentage quantities?

I often see on clothes, bags, sheets, etc. a few % of polyester in the cotton cloth label.   What does this mean and why do they do it?   Are they weaving one out of every few strands out of polyester?  Or is the fiber itself made of a few % polyester in composition?  And what does it do for the cloth?

[Assistant] Because poly is spun in long threads it allows for shorter cotton fibers to be used. 100% cotton threads need long fibers to make a strong, thin thread or you end up with lots of pilling (pilling is all those short ends that stick out getting rolled up together from friction). So it's a cost effective measure, as well as reducing wrinkles and shrinkage that 100% cotton fabrics are prone to, as others have said.


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

[User]
CMV: No doesn't always mean no

Let me be clear, of course no means no, but let's be honest, lots of people, women being no exception, like to be pursued. A fairly sizeable minority enjoy actively making it difficult for potential partners and enjoy watching them making a persistent effort to "win" them. Social interactions are so broad and convoluted, from body language and tone to double entendres there are a million ways in which you could be engaging in non-consensual activity from the strict point of view of a conversational transcript while not once violating consent in reality.

By the same token of course there are also a million ways to say no that don't involve words and both partners need to take responsibility for being clear when you really mean it to being receptive to subtle signals.

My point is simply that a spoken "no" does not always mean "stop what you're doing" because taken in context with the rest of the communication, it sometimes means quite the opposite and i think this grey area is often skated over.

[Assistant]
The concept of "no means no" simply invites to always err on the side of caution in some specific contexts, e.g. the context of discussing sex on a date. It doesn't literally imply that nobody is ever coy.

For example, when discussing the aforementioned sex on a date, it is now considered good to assume that no literally means that, even though in some cases it doesn't. On the other hand, if you're offering to gorge on three pizzas to a friend and they say "no im dieting pls no", you're free to insist, because they're *so* fat anyway, what could a couple of pizzas change ffs.


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

[User] ELI5: Were our teeth naturally supposed to be yellow? And is it actually healthy for them to be white?

[Assistant] Enamel is white, and it covered Dentin, which is yellow. As bacteria and acids eat away at enamel, yellow dentin is exposed. Teeth would have naturally been very white up until processed sugars because widespread, because bacteria thrive on sugar and churn out acids which break down enamel.


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

[User]
[Comics/ general] Why do so many superhumans or powered people like mutants in marvel or metas in DC want to get rid of their powers so badly or hate thier powers when they have cool ones that are pretty much under control or come with honestly pretty cool cosmetic changes?

 Like you're born with or gain abilities  that' are useful and you have pretty much control over it  and maybe u might have pointed ears  or different eyes. Maybe you transform or whatever but , for some reason you hate your powers and want to get rid of them? why ???

[Assistant]
Would you be super strong and have blue fur and being target of verbal and physical threats that you legally may not answer with violence, or would you be who you are now?

Humans are pretty racist, living with anything that isnt considered human makes your day to day activities a pain in the a. Many just dont want to have to do any business with any *hero* stuff and just exist peacefully.


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

[User] [LotR] If Frodo had somehow managed to destroy the Ring by himself, what would have become of Gollum?

[Assistant] He was far older than any Hobbit could live. The Ring doesn't provide *more* life, it just kind of stretches out your normal lifespan. Without the Ring artificially doing this, he would die (and if the fate of the Witch-king is any indication, his own guess that he'd crumble to dust is likely accurate).


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

[User]
Big O rule #4

Hello folks, I was wondering anyone could explain to me in simple terms what the big o notation rule #4 means (drop non dominant terms)? Thank you.

[Assistant] Let's say your algorithm takes O(n + n^2) seconds. for example it first reads data - which is linear - and then does a calculation with quadratic complexity. Very quickly that linear component (n) will be completely dominated by the part with quadratic complexity, so you can ignore it and end up with a total runtime of O(n^2) only.


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

[User] What part of lightning does the thunder come from? Is it the bolt hitting the ground?

[Assistant]
The bolt doesn't "hit" anything in the sense of an object hitting another object. A lightning discharge is formed when the lightning precursor, a so-called "leader", forms a conducting channel between the cloud and the ground (or between two different parts of the cloud in the case of cloud-to-cloud lightning). At that point, a current can flow through this channel, with the channel acting somewhat like an electrical cable between the two endpoints.

Since the current running through the lightning channel is very high, the channel heats up rapidly. And since hot air expands and displaces surrounding cooler air, this rapid heating causes a rapid expansion of the air in the channel. This rapid expansion generates a shockwave which is what we hear as thunder.

While the initial shockwave is a very brief burst, the sound is distorted and reflected by different parts of the atmosphere having different temperature/pressure and by elements of the landscape. Combined with the fact that the shockwave doesn't originate in a single point, but rather along the length of the lightning channel (which can be several kilometers long), this results in what we call thunder: Not an instant and short "bang", but rather a prolonged rumbling.


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

[User] [It] Pennywise describes itself as The Eater of Worlds. While it could probably wipe out a planet, how many worlds could it have eaten if it doesnt leave a certain geographical location and only feeds for about three months and then hibernates for thirty years?

[Assistant]
Pennywise is a demon from the outer dark.  It was a being that existed before creation and would likely have existed after if not convinced to allow itself to be destroyed.

Some cosmology: in the beginning there was void and chaos in the outer dark.  This sea of primordial possibility was called the Prim.  Gan raised the tower up from the Prim and around it created existence, pushing back the Prim. There were many wonderful and horrible things stranded by the raising of creation.  Many died. Others learned to breath and exist in the light of creation and started to feed of other things... But the process made them lesser.

They were more constrained by reality and in the case of pennywise he had only as great a power as the beings around him thought he had.  There might have been significantly more trouble if pennywise had landed somewhere else with a more imaginative population.

It's also possible that what we see of pennywise is only a fragment of their previous power which they began losing as the tower began to fail.  The world is moving on they say.

Long days and pleasant nights.


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

[User] Can you break sound barrier under water or any other material?

[Assistant]
Yes, breaking the sound barrier in any medium (including air) will result in a buildup of sound waves (pressure waves) which causes a sonic boom.

However, the high viscosity and higher speed of sound in water means a ridiculous amount of energy will be needed to create that sonic boom.


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

[User] if hot air goes up, why are the top of mountains cold?

[Assistant]
Because the air at high elevations (mountains, for example) is actually more-or-less in thermal equilibrium with the air at sea level, if you take into account the pressure difference.

Since the pressure is lower at the mountaintops, the air from the sea level will expand as you lift it higher. Expansion, in turn, causes cooling. So if you just take a mass of air from the sea level and transport it to the mountain, it'll be around the same temperature as the mountain air by the time you get there.


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

[User] ElI5: How our lungs prevent/eliminate dust ?

[Assistant] Your nose and trachea are lined with tiny hairs, cilia, which are covered in sticky mucus that traps most dust from getting to the lungs. The cilia in your windpipe are always doing a wave, so to speak, that pushes stuff up and out.


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

[User]
[Star Wars] Upon learning that Palpatine was a sith lord how could the Jedi have handled the situation better.

Instead of walking into his office and making it look like they were trying to seize power.

[Assistant]
I believe the short answer is, they couldn't. In that moment, Jedi master Windu and his three cohorts were prideful and arrogant. They believed four against one would intimidate even a Sith lord into surrender. In fact, Palpatine was counting on their hubris all along. It was, in fact, the raison d'tre for his infiltration of the senate and downfall of the Jedi. They played into his hand flawlessly, and when Palpatine sensed the presence of young Skywalker when battling Windu, he made his galaxy-altering decision to allow himself to be cornered in order to force Skywalker to fall to the dark side.

Consider that any other move, other than confronting Palpatine at that very instant, would have been antithetical to the Jedi beliefs. To allow him to continue to be in power without making a move against him immediately would be unthinkable. On the other end of the spectrum, to somehow connive to expose him would be dishonest and bordering on the dark side.

The only thing they might have done is send more Jedi to apprehend the Sith lord. However, again, they were too arrogant, and furthermore, since they had not dealt with a threat of that magnitude in Jedi knows how long, they were simply unprepared for the level of infiltration they were dealing with.

All in all, it might have actually been to their advantage to NOT send Windu. If Palpatine had not stood toe to toe with Windu for so long, Skywalker may have seen Palpatine for who he really was (with the corpses of Jedi strewn about his office), and found his way back to the light side....


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

[User] [Fallout] How do I become a Raider? They appear to have their own community and locales, but it seems impossible to join. Whenever I run into them they open fire at sight.

[Assistant] Raiders form from groups of people, usually drug addicts, that take to murder or threats of murder to obtain goods instead of... Well... Working like honest people. You are unlikely to ever find a group that's mellow enough to accept new applicants. The only real solution is to form your own raider band. Grab some friends and hold of a caravan, or murder some settlers. Bam! You're a raider.


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

[User]
ELI5: How does a bomb suit protect a bomb technician during an explosion?

Edit: Thank you all for the responses. They very very clear!

[Assistant]
There are three big dangers that typically come from a bomb explosion: heat, shrapnel, and shockwave.

A bomb suit is designed, as much as possible, to protect from those three things.  It's got thick layers of padding and kevlar to keep shrapnel from the bomb from piercing and harming the wearer.  It's thermally insulated so that heat can't get inside the suit and burn the wearer.  And it's got layers of material with a high acoustic impedance and soft foam layers to keep the shockwave from exerting too much pressure on the wearer.

The shockwave is the biggest danger to the wearer if they're close to the bomb, and the hardest to protect against.  A light suit can protect very effectively from shrapnel and heat, but might not be able to withstand a close-range shockwave that could still cause a lot of internal damage.  Heavier suits are more able to withstand that pressure, but it's the hardest factor to protect against.


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

[User] ELI5: How does a computer unset a bit (set it from 1 to 0) in memory/storage?

[Assistant]
It depends on the particular kind of storage.

In magnetic storage, like a spinning-disk hard drive, it magnetizes the region storing the bit in the opposite direction.  (In practice, hard drives write entire blocks at a time, but the technology could theoretically be managed a bit at a time.)

In typical flash storage, like in solid-state drives or external flash drives, it can't write a single bit at a time.  In order to change a bit from a 1 to a 0, it erases an entire block of memory, then rewrites the new data into it.

In DRAM, which is the typical kind of RAM in a computer, it connects the capacitor holding the bit to a current drain, which allows it to discharge.  (Similarly to others, standard DRAM actually can only write a whole line at a time, so switching a single bit means writing the previous value into all the other bits.)

In SRAM, which is typically used for things like on-CPU caches, the bit line is set to 0 and then the write line is set to 1.  The transistors switch into the alternative configuration, and then the write line is set back to 0, which causes them to maintain their current configuration until written again.


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

[User] ELI5 why we stopped using large battleships.

[Assistant]
Large battleships have the majority of their firepower in side mounted guns, which have a range of 15 km at most and can't shoot up. In contrast, aircraft carriers have an insanely long range and can shoot basically whatever. This gave aircraft carriers a huge advantage over battleships in World War II, to the point where the battleship-centered fleet model was rendered obsolete.

There actually is some speculation that having some battleships would make more strategic sense. But there haven't been any major naval battles since World War II to test this, and since the USA has more naval power than the rest of the world combined there won't be for the forseeable future.


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

[User] ELI5: "The road to hell is paved with good intentions."

[Assistant]
It generally means that often when people try to do things for reasons they think are good, bad things happen anyway.

One example is the UN giving free food to Africa.  At one point it was driving the price of food so low that the farmers in Africa that had an economy that functioned, even if it couldnt build a jet fighter, would basically go out of business because you cant compete with free.

It generally warns that wisdom requires caution, and not all ideas that sound good are actually good ideas.  It pays to stop and think about what you are doing.  The bigger the thing you are going to do, the more you should think about it.


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

[User] ELI5: Why do fashion shows show off ridiculous clothes?

[Assistant]
The stuff they show isn't intended to be purchased and worn by consumers.  It just shows what designers will come up with on a clean sheet of paper with nothing holding creativity back.  Further, these radical designs typically show certain design elements that will be toned down and carried over into a consumer line in the near future.

If you're familiar with cars, think about how automakers show these crazy concept cars for large auto shows.  The manufacturer has no intentions of producing these cars, rather they showcase the direction their car designers will be taking in the next few years on production cars with toned down interpretations of the style elements of the concept car.


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

[User] Does nuclear fusion produce radiation like nuclear fission?

[Assistant]
There are two types of radioactivity that can come from fission/fusion.  The first is *prompt radiation* - this is particles given off instantaneously during the fission or fusion reaction.  For instance, fission of a U-235 nucleus leads to the emission of 2-3 neutrons, gamma rays, and two energetic fission products (which are just two smaller nuclei).  Fusion of deuterium and tritium (H-2 and H-3) gives off a neutron.  So both of these reactions lead to prompt radiation.  Prompt radiation is mitigated by shielding the reactor core.

The other component is due to the instability of the products of the reactions.  Due to some characteristics of the stability of atoms, the products of fission are almost always radioactive.  In other words, when the uranium nucleus splits into two pieces during fission, these pieces go on to decay later in other ways.  This is what causes spent nuclear fuel to be radioactive.

There are several different fusion reactions that could be theoretically used to produce power, but most of these don't lead to the creation of radioactive products.  For instance, in D-T fusion, the product is helium-4 (which is quite stable).  There are secondary ways in which the neutrons emitted by fusion can lead to the activation of materials within the reactor, but in general there is very little radioactivity in the products of nuclear fusion.


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

[User] ELI5: Body organs. Whats in the space between them? Can organs leak? What holds them in place?

[Assistant]
Held in place by fascia *(sheets of strong connective tissue sort of like ligaments / tendons, but not involving bone or muscle)*.
Yes, they can leak. If it's your intestines leaking it's probably going to lead to a nasty infection. A leaking lung can lead to collapse of that lung. A leaking gall bladder or stomach can eat away nearby tissue.
There isn't much space; usually the organs are against each other. Some slime to make movement easier. In the brain, both between the hemispheres and between the layers of covering, there's fluid.


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

[User] [Economics] Why are there so many divisions in Macroeconomic thought?

[Assistant]
The degree to which there are schools of though in **academic macroeconomics** is vastly overstated. There were major, substantive, paradigm-destroying debates in macro during the 1960s (Keynesian/Monetarist), 1970s (Keynesian/New Classical) and 1980s (New Keynesian/Real Business Cycle) but we've largely converged since the early 1990s. Almost all applied macroeconomic research is New Keynesian of some flavor, with heavy methodological influence from the New Classical and Real Business Cycle theories. Time will tell if the rise in agent-based computational macro will prove to be as paradigm-destroying as Lucas' program was forty years ago.

We have largely coalesced on a common language for modelling (DSGE), a common baseline language for causal inference (SVAR, though it's far from perfect), a common language for thinking about economic shocks (impulse, amplification, propagation), and a common language for thinking about the role of inefficiencies in the economy (wedges). By 2007, we had a few working medium-scale models that economists mostly agreed were ready for use in policy analysis (with some vocal exceptions).

We continue to disagree, sometimes heavily, on the empirical importance of the various wedges, frictions, and market imperfections in the economy. The financial crisis has weakened the c.2007 consensus somewhat - the much-vaunted policy models weren't able to analyze large financial panics.  There is serious lack of data in macro, and an equally serious lack of good identification techniques (what natural scientists would recognize as "natural experiments"), which makes inference difficult.

The proliferation of divisions of macro in the **public policy sphere** can be attributed to politics, lack of data, the public debate lagging the academic literature, etc.

The public lags the academic literature; that's fine. It means that in the public sphere the trifecta of Keynes, Hayek and Friedman continues to have sway on how people think about macroeconomic policy, even though all three of those thinkers had become irrelevant by 1972, their main insights absorbed into the body of academic work.

I have a pet theory that the "divisions" in macro, that we see in the popular media, are manifestations of the general need for a "story" or "narrative," akin to political narratives, but it's just an hypothesis.


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

[User] "If you gaze long into an abyss, the abyss will gaze back into you" - What does this mean?

[Assistant]
You have to hear the whole aphorism for it to make sense.  Here it is...

>"Whoever fights with monsters should see to it that he does not become a monster in the process. And when you gaze long into an abyss the abyss also gazes into you.

If you seek to fight the "monsters", then you shouldn't do it using their methods, or you'll be as bad as the thing you want to destroy.

And the next part is just a reiteration almost... If you surround yourself with negativity, that's what you'll become. Negative.


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

[User] What would Earth be like if it rotated on the ecliptic?

[Assistant]
- You mean if the orbit of the Earth lay in the ecliptic plane? It does in any situation where the Earth orbits the Sun (Edit: like in real life).

- You mean if the rotation of the Earth had it's axis in the ecliptic plane? The seasons would be dramatic - like the entire planet was in the arctic circle. The equator would probably still be inhabitable: in two seasons it would have a fairly normal night day pattern, but in the other two seasons it would be sunset/sunrise pretty much all the time. Further away from the equator, the winters would be completely dark and freezing, and the summers would be impossibly hot. No part of the planet would be cold all year round because every part of the planet would spend time directly facing the sun.

- You mean if the rotation of the earth had orbit perfectly perpendicular to the ecliptic plane? It would look much like it does now, except with no seasonal variation at all.

I hope one of those answers your question.


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

[User]
[Lord of the Rings] Had Merry and Eowyn not defeated the Witch King, would the Dead Men of Dunharrow have defeated him instead?

Or would he have just faded to etherealness and returned to Sauron?

[Assistant]
Well as already stated, in the books, no, as they were never at that battle.

So then who else could have defeated him? The prophecy says "if words spoken of old be true, not by thehand of manshall he fall". Notice it doesn't say "the hand of A man".

It seems to be that it was going to be Gandalf himself who was going to face him, Gandalf being a Maiar, not "man". The movie made it seem as if Gandalf was fearful of the Witch King, however in the books that is not the case. Gandalf stands before him at the Gates of Minas Tirith ready to fight him. When the Rohirrim arrived and the Witch King left the gate. Gandalf was going to go after him, but Pippin asked him to save Faramir. Gandalf reluctantly went because he knows he is needed on the battlefield instead and if he isn't there than people with die, which is how Theoden was killed.

It was here that Eowyn stepped up and killed him, but had she been unable, it probably would have been Gandalf instead.


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

[User]
CMV: If universities implement pass/fail grading, it must be mandatory.

There is going to be a wave of proposals, petitions, and maybe even protests for pass/fail grading at universities now that a few major colleges have announced they are going that route. Some are making the pass/fail grading optional. Regardless of whether the pass/fail grading system is a good idea, I think making it *optional* is a mistake. When an employer sees on your transcript that you opted into a pass/fail grading system, regardless of your actual reason for doing so, some will assume it was becasue you were doing poorly in the class. You could potentially explain to them that you had difficulties with distance learning, but you would have to get to the point of direct communication first, which in some applications is not easy.

Certainly employers (and graduate programs, medical schools, etc...) know that spring 2020 transcripts will look funky, but the other two options (keep letter grades or mandatory pass-fail) are better in this regard. If you keep letter grades employers can see how much your grades dipped (if at all) in response to stress, which may convey adaptability. If you have mandatory pass/fail, then its a black box whether you were doing well or poorly prior to the move to e-learning. If you have optional pass/fail however, people who have and can keep an A will keep the letter, whereas those who were doing badly, regardless of the reason, will take pass/fail if they can meet the pass cutoff. This means that the "pass" pool is a mix of good students hit hard by the circumstances and academically poor students. The A's (and maybe even B's) will always be better than the passes. I have a feeling that something is missing from this chain of reasoning, but as it stands in my mind an optional pass/fail policy would hurt the people it is trying to help.

I'm aware that this post is tangentially related to certain events which shall not be named. I would hope that the mods can recognize that the principles of this discussion also apply more generally to other types of crisis which may occur in the future either locally or nationally.

Edit: preemptively clarifed wording.

[Assistant]
Many students are currently retaking courses in order to raise their GPA.  If pass/fail becomes mandatory all the money they spent on retaking those courses is now wasted.

Many students need particular grades in key classes in order to meet licensure requirements. If pass/fail is mandatory (and their licensing boards don't loosen restrictions) then all of those students would need to retake those classes.

At many institutions a grade of A, B, or C gets converted to a pass, while a grade of D or F gets converted to a fail.  Under normal conditions a grade of D still earns credit, and unless the course is for a student's major still meets the requirement.  Under mandatory pass/fail students who normally would have gotten through a requirement with a D would now have to take the class again.

If an institution wants to offer pass/fail as an option to students, then making it mandatory would do more harm than good.


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

[User]
ELI5: What's so special about the eye muscles that someone with locked-in syndrome can still usually move their eyes, while all other voluntary muscles are paralyzed?

Was thinking about this and did some cursory googling but can't really find an explanation. Why those muscles and no others?

[Assistant] It has to do with where damage is. The oculomotor nerve (cranial nerve 3) controls some eye movement and eyelid movement and is higher in the brainstem. Cranial nerves and other nerves further down are not spared.


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

[User] ELI5: Why does boiling water stop rolling when you stir it?

[Assistant]
When water is at a rolling boil, the hottest water near the heat source is becoming gaseous and forming bubbles.

When you stir, you are mixing the cooler water from the rest of the pot in with the very hot water, cooling it down and preventing the formation of steam.


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

[User]
[Star Wars] How were years measured before The Battle of Yavin?

Whenever we talk about events before the battle we use BBY (similar the BC in our universe). How did people measure time before that battle though since the obviously didn't know that that battle was even coming. Did the use Years After the 1st Galactic Civil War?

[Assistant] The Galactic Standard Calendar was based around Coruscant's solar cycle, and it set the standard for the rest of the galaxy. Since its creation along with the Old Republic, historians have used major events as a new turning point, much like the Battle of Yavin is used today. The creation of the Galactic Empire and the Battle of Endor were ones used in recent memory, but others include the Ruusan Reformation and the Great Resynchronization. However, many smaller/more isolated planets use their own calendars, based around events their residents would know extremely well.


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

[User]
[Harry Potter] Did Voldemort know he was done for in the final fight?

Rereading Deathly Hallows, there was no way he could win. All his horcruxes were gone, and Harry had just come back from the dead. Was he delusional enough to think he could win, or was he just committing suicide by Potter?

[Assistant]
Voldemort only feared one wizard, Dumbledore. Widely considered one of the greatest practitioners of magic of all time.

With Dumbledore defeated, him thinking he was the true master of the elder wand, and thinking Harry was just someone who got lucky with a love sacrifice. Voldemort was pretty sure of himself. There was no way, in his eyes, he would lose to someone so far beneath his skill level.


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

[User] ELI5 - If gunpowder accelerated bullets can barely travel a few feet underwater and arent even really lethal, how the hell does a spear accelerated by goddamn plastic bands kill fish from quite a distance?

[Assistant] It is all about kinetic energy. The kinetic energy depends on the mass and velocity of the projectile. To get enough kinetic energy to kill something you can either use a low mass projectile that you accelerate to very high speeds (such as a bullet going supersonic) or you can have a large projectile going at low speed (such as a spear or arrow). In air it is obviously much better to have something going high speed because it is much easier to hit things with it. However in water there is so much resistance that it is almost impossible for anything to go at speed. So for hunting in water you are much better off with a heavy projectile because then you do not need much speed to get enough kinetic energy to kill the fish.


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

[User]
Why did Kant write the way he did?

You probably know what I mean by the title if you've read any of his works, he is tremendously hard to read and constantly uses hugely complicated wording as well as sentences that spread through multiple pages.

But why is this? Why did he think this was necessary? I vaguely remember reading somewhere that he admitted in a letter he was very rigorous in the contents but didn't care about style at all, and that he was influenced by somebody who he knew in his youth in his style of writing, though there is no source for any of this that i can find which is why I've resorted to coming here for aid.

[Assistant]
Here's a bit taken from the Introduction to the Cambrdige Edition of the *Critique of Pure Reason*:

>  The book is complex, however, not just because of the complexity of Kant's own position, but also because he argues on several fronts against several different alternative positions represented in early modern philosophy generally and within the German Enlightenment in particular. In order to make room for his own dualistic defense of both modern science and human autonomy, Kant, like Descartes, Locke, and Hume, felt he had to rein in the pretensions of traditional metaphysics, which was represented for him by the school of Christian Wolff (1679-1754) and his followers, especially Alexander Gottlieb Baumgarten (1714-1762). Their position, which Kant called "dogmatism," was compared in the Preface to the Critique to the despotic ministry of an absolute monarchy - Kant held dogmatism to be capricious, opinionated, faction ridden and consequently unstable and open to the contempt of rational observers.

Kant wrote the way that he did due the nature and scope of the task that he set out to accomplish, which was, in no small words, revolutionary in philosophy at the time - challenging many of the fundamental assumptions of how philosophy was done up till then.


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

[User]
What are some new, instant, or probable "classics" from 1995 to 2017?

Do you have favourite books or papers you'd consider to be or become "classics" from the last 20 years?

EDIT: Great answers here, thanks everybody! Follow-up question: Do you also have more recommendations from outside the Anglo-Saxon sphere of philosophy? What about Skandinavian, German, Italian, Russian thinkers? What about Africans and South-Americans?

[Assistant]
In Political Philosophy:

Books

- *Multicultural Citizenship* by Will Kymlicka: Perhaps the most important publication to come out of the liberalism versus communitarianism debate, it has largely defined the liberal approach to issues of culture, nationality, and ethnic identity. Widely cited across multiple disciplines which is somewhat rare for a contemporary piece of political philosophy.

- *Rescuing Justice and Equality* by G.A.Cohen: Arguably Cohen's Magnum Opus, this book is probably the most rigorous left-wing critique of Rawlsian liberalism. It has become a foundational text in modern debates regarding the methodology of analytic political philosophy (especially the debate over ideal theory).

- *National Responsibility and Global Justice* by David Miller: A seminal text in the Global Justice literature, Miller provides a comprehensive, lucid, and intellectually rigorous statist/nationalist alternative to the dominant cosmopolitan paradigm.

Articles

- *Justice in Migration: A Closed Borders Utopia* by Lea Ypi: Ypi completely breaks through the traditional dichotomy in debates about the ethics of migration by proposing that the relevant principles of justice must consider both the effects of immigration and emigration. In doing so, she turns our attention towards the vastly under-theorized idea of justice in emigration and pushes against the received wisdom that emigration ought to always be permissible.

- *What is the point of Equality?* by Elizabeth Anderson: A massively impressive article both in terms of originality and scope. Anderson successfully challenges some of the most influential conceptions of egalitarianism (including luck egalitarianism) and sheds a lot of light on one of the central concepts of contemporary political philosophy.

- *The roles of religious conviction in a publicly justified polity: The implications of convergence, asymmetry and political institutions.*
by Gerald Gaus and Kevin Vallier: A central work in the emergent  literature on post-rawlsian public reason, Gaus and Vallier challenges the dominant "consensus" model of public justification. In its place, they offer a now highly influential "convergence" account which they see as better able to deal with the facts of persistent disagreement in society.


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

[User]
ELI5: How do painkillers 'seek out' the source of pain?

Title pretty much says it, how do painkillers know where the pain is?

[Assistant]
generally they dont. Many pain killers are actually just anti-inflammatory drugs as any part in you body that is in pain will also be inflammed, so reducing this will also reduce pain.

EDIT: so in ELI5 mode: drugs go all over your body (bloodstream) but only affect places in pain.


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

[User]
[One Piece] Everyone is pirates. How is a piracy-based economy sustainable? Or... How could ANY economy support what appears to be an entire civilization of lifelong pirates?

Pirates. Pirates pirates pyrites.

Pirate piracy, private pirates pirate your pirates.

What's up with his outfit? Are you a pirate?

Pirates are in this year!

[Assistant] They aren't all pirates.  Frankie was a shipwright before he joined the straw hats, there's thousands of navy soldiers and officers, the crew regularly stays in Inns and eats at restaurants, there are bakers, smiths, engineers and people of all variety of careers in the world.  It only *looks* like everyone is a pirate because the straw hats are pirates and thus interact primarily with other pirates.


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

[User]
Did Aristotle believe in God?

I had an argument with someone who got angry at me for saying that Aristotle believed in God. I am curious what the consensus is, although I suspect it is in my favor.

[Assistant]
Well, since Aristotle thought that God, as the unmoved mover, was rather central to his metaphysics, I'd say you're right.

Now some Aristotle scholar will probably come along and show how a nuanced and critical reading of Aristotle as he was received by 9th and 10th century Islamic scholars proves me wrong, but in general, I'd say, yes, Aristotle, who argued for an unmoved mover as a centerpiece of his metaphysics, was a theist.


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

[User] How do we know the composition and mass of some planets/stars ?

[Assistant]
In terms of composition. We're looking at a technique called spectroscopy. Basically, for any chemical element (or larger structures like molecules but when you're talking about stars it's too hot for molecules), the electrons can only have specific energies.

For each chemical the gaps between the available energies will be unique, this means we can identify a chemical by the gaps between its energy levels.

But how do we know what the gaps in energy level are? Good question. Electrons move between energy levels by either absorbing or emitting energy. One of the ways this can happen is by photons (light). Because the gaps between energy levels are specific sizes only specific energies of photons can be absorbed or emitted.

When it comes to photons their energy is also proportional to their frequency (because photons have wavelike properties as well as existing as distinct particle like things) and the frequency of light determines its colour.

Either we put in light at a range of wavelengths and see what's absorbed or look at the light being emitted. This works for both stars and atmospheres of planets.


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

[User] ELI5: How does smoking while being pregnant affect the baby?

[Assistant] Smoking reduces the amount of oxygen that is available to a growing fetus, which it does in two different ways.  First, the carbon monoxide in the cigarette smoke makes the blood less capable of carrying oxygen, and secondly, the nicotine acts to make blood vessels constrict and become narrower.  The reduction in oxygen makes it harder for the fetus to develop.


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

[User]
ELI5: Why did musicians decide middle C should be labeled C and not A?

So the C scale is sort of the first scale because it has no sharps or flats. Middle C is an important note on pianos. So why didnt it get the first letter of the alphabet? While we are at it, where did these letter names even come from?

[Assistant]
When the 7 notes of the western scale were named, the standard scale was A B C D E F G. What we now call the natural minor scale, or the *Aeolian Mode*

Composers in this period, medieval Europe, didnt have the sharps and flats. So to gain access to different harmonies they used used *modes*. Modes are the same 7 notes, but you start on a different note. The third mode of this scale is called the *Ionian Mode* and starts on C and goes through all the notes C D E F G A B.

During the classical music period, this became the mainstream scale for music. Music notation was invented and based around this mode. So now we think of the Natural minor as starting on the ~~5th~~ 6th note of the major scale. When really the Ionian Mode is the third mode of the Aeolian Mode.

In reality they are all just frequencies and there is no more or less *correct* notes. The music notation system is made up by us, and we could change it.


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

[User]
Why exactly are glycine and proline considered "special" amino acids?

I heard this many times throughout my biochemistry class and now I'm hearing it again in biopharmaceutical science, but I've never understood what really separates them from the other amino acids.

[Assistant]
The answer here boils down to degrees of freedom. Because it lacks a beta substituent, glycine can adopt a number of psi- and phi- angle combinations that are energetically disfavored for other amino acids. As a consequence, the Ramachandran plot for glycine is radically different; additionally glycines tend to favor flexibility in the local backbone (because the entropic cost of folding becomes higher).

In the opposite direction, the fact that proline is cyclic significantly reduces its range of favorable angular configurations. Additionally, its cyclic character prevents it from forming hydrogen bonds at the amide (making it a "helix breaker"). However, for proline the cis- configuration of the peptide bond is not as unfavorable as it is for other amino acids, which opens up some additional conformational space.

Both amino acids have significant effects on the local flexibility of the chain and have angular restrictions that differ substantially from other amino acids. This is why they are "special".


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

[User] If something is faster than the speed of sound, it's supersonic. And slower is subsonic. If something is the same as the speed of sound, is it just considered "sonic"?

[Assistant] There isn't really a sharp dividing line between subsonic and supersonic flight. As an object approaches supersonic speeds, local airflow can exceed the speed of sound as it is forced to go around an object, even before the object itself exceeds the speed of sound. This speed range is generally described as transonic.


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

[User]
[Harry Potter] What level of sentience do moving pictures have? Why can some talk and others not?

Also is there a difference between portraits and photographs?

[Assistant]
Portraits take time to create, and because of the care and attention involved, magic infuses with the paint, giving it a semblance of sentience.

Some portraits, however - such as a Hogwarts headmaster portrait that the castle automatically creates, are completely sentient.


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

[User]
[Marvel] Who would be the most dangerous entity to wield the Infinity Gauntlet? The most benign?

Obviously Thanos was pretty darn bad when he had it, but what about if someone like Galactus was to wear it? Or \(somehow\) Dormammu?

On the other hand, who would do the most good with it? And without somehow being corrupted and doing untold evil anyway..?

[Assistant]
The most good would be either Spiderman or Captain America probably.

The most dangerous? Deadpool is a contender for sheer insanity.

But it's probably one of the lessor villains who thinks they deserve everything they want.

The purple man with the infinity gauntlet would be terrifying for example.


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

[User]
ELI5 What makes the strong 'click!' sound when you snap your fingers?

What on the finger's surface causes it to make such a strong sound?

[Assistant]
The sound doesn't actually come from your fingers themselves.  The sound you hear is your finger hitting your palm just under your thumb - it's like a small version of clapping.

The reason you need to 'snap' to get it is to get the finger moving fast enough to make noise.  You build up pressure against the thumb, and then the finger slaps into your palm fast enough to make noise.


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

[User]
ELI5: How can a rocket reach escape velocity of Earth (11.2 km/s) if chemical fuels allow exhaust velocity 4.5 km/s at most?

It seems obvious that higher energy density than original energy density of fuel is impossible - but somehow rockets can gain 63 MJ/kg with fuel which offers only 10 MJ/kg. How is it possible?

[Assistant]
Imagine hitting a tennis ball at 4km/Hr straight up. But then just as it starts to slow down you keep hitting it, moving with the ball so it's always travelling at the same speed. Eventually the resistance from the air reduces as you get higher and higher.

Escape velocity is the speed at which you hit a ball once to make it leave earth permanently. Rockets instead just keep hitting the shuttle over and over again with thrust until they reach this velocity.


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

[User] ELI5: If it's so difficult to cool things down in space, how do satellites and the ISS not overheat from sunlight?

[Assistant]
Most surfaces are painted white or coated in reflective material to reduce absorption of sunlight.
There may also be areas painted black that face away from the sun that radiate heat.

White absorbs light/IR the least, but also radiates heat the least.
Black absorbs the most, but radiates the most too. By using both in the right positions, the temperature can be controlled.

Thermal management is basically all about moving heat to a part of the spacecraft designed to radiate heat to keep the craft cool.


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

[User] [King Kong] How often do the Skull Islanders give a bride to Kong?

[Assistant]
It is probably based on weather cycles of good and bad harvest.  Kong is worshiped as a god, therefore offerings are made to the god when god's favor is needed.  If there is a long drought, they offer a bride to Kong to end the drought...or they give him the bride in thanks for ending the drought. Either way the offerings are based on the needs of the people, not the needs of Kong.

Therefore the offers are probably irregular lengths of time.  Through classical conditioning, Kong has probably learned that if he goes to the village during a drought, he gets a reward. The banging drums and lights serve as additional conditioning clues that there is a reward waiting for him.

If we go by the Peter Jackson version with the pile of bride bones, it would seem that Kong treats the bride reward in much the same way we treat a cookie or cheap plastic prize.  We want the reward, but we are not that deeply attached to it and are okay with it breaking or getting lost within minutes of receiving it.


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

[User]
Why do some animals hop instead of walking?

Some birds, rodents, marsupials etc hop rather than stride, but not all. What is it that makes it a better way to move for only certain members of the species. Why is it always one or the other and not some mix? Are there any examples of it being individual case by case rather than across the board for that animal?

[Assistant] Hopping is usually taken up because its a low energy way to move while keeping some sort of high speed mechanism for escapes intact. Rabbits can sprint incredibly fast, but their morphology for this makes it so hopping is the easier method of movement when they arent running for their lives. Similarly for frogs, their legs are adapted for swimming and strong leaps to catch prey and avoid predators. So the easiest form of relaxed locomotion is a hop.