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

[User]
ELI5: How the "trillion dollar" coin idea would work, and why it wouldn't throw the US economy in to hyperinflation

I was watching the news and saw this "trillion dollar coin" idea that congress had talked about. Can somebody explain how this would work, why it isn't an insane idea, and why the US economy wouldn't turn in to an economy like post WWII Germany's with hyperinflation?

[Assistant]
Let's pretend that the US has a credit card with a set credit limit.  The credit card is the national debt and the credit limit is the debt ceiling.  The US has bills coming up that will need to go on the credit card, but we are already at our limit.  That leaves us the following options:

Option 1:  Convince the credit card company (Congress) to raise our limit (debt ceiling).  The problem is the credit card company doesn't want to raise the limit unless we promise to cut down our cell phone plan.  We really like our cell phone plan and don't want to give that up.

Option 2: Is to borrow cash from someone else.  Dad (the President) can pay our upcoming bill if we promise to pay him back.  In the end we still owe the same amount of money, but we get around the whole issue with dealing with the credit card company (Congress).  This will make our financial planner mad because it doesn't really addressed the real debt problem.  However, it gives us the ability to keep paying our immediate bills without paying any late fees or dropping our credit score.

The reason option 2 wouldn't cause immediate inflation is because it is the exact same physical outcome as option 1.  The US still continues to pay its bills as normal, all its creditors get their scheduled payment on time, and no new money is entering the system.  The credit limit is simply artificially raised by borrowing from a secondary lender.  Inflation generally happens when new money enters the money supply.  Money enters the money supply when the government spends it or lends it out, raising the credit limit is neither of those.  Although it is a sign that the government will spend or lend in the future, which could lead to future inflation.

Finally the reason the money provided by the President (or the Treasury to be more specific) needs to be a trillion dollar platinum coin is due to archaic and somewhat random rules on the type and denomination of currency they can print.  A coin of that value is basically a loophole in the established laws; the transaction wouldn't be allowed with a trillion dollar bill or a trillions dollar gold coin.


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

[User]
[iZombie TV Show] Why do zombies eat daily doses of brain?

> You know what you're looking at?"
> "A brain?"
> "You're looking at 20,000 dollars, one of these can last a zombie a full month"

In the show its stated that a single brain can last a zombie a month, but when separated from their food source for over 24 hours extreme uncontrollable hunger sets it. This is presumably because the zombies ration their brains for daily consumption. Either this is by choice or because a zombie grows hungry regardless of a full stomach. (I just started Season 4, so if theres an explanation forgive me)

Assuming its the former, this diet doesnt make much practical sense. It may work for Liv who has to frequently switch between murder victims. But I dont see how it benefits the two other zombies we see in-prisoned nor the rest of zombie society who have enough problems feeding themselves as is. For example: >!When Filmore Graves is rationing out brains, in a food shortage and while fighting humans, would it not be far easier and safer to supply and eat them once a month rather deliver a supply and put the tubes in storage to be eaten across the month?!< additionally this method would mean fighting visions and personality disorder in shorter and possibly stronger bursts. Also Zombies dont even like the taste. A tasteful diet for them would be snacking on peppers if you really got the munchies.

Assuming its the latter, this answers the title, but raises serious questions on the sustainability of zombies. For one, overeating should be a much bigger problem. I mean human hunger is controllable to the point we can starve ourselves to death and we still have an obesity problem. Imagine what a Zombies daily hunger would do. Every time a delivery was late and the hungry zombie ate a little too much, they would need to eat even more brains that month. Eventually these insistences add up and suddenly Blaine would need to kill twice as many people. Those same zombies would also have to be really good at packing brains with them on every out of state trip, or out for the day, or visiting anyone. Or they all just got away with murder easily. And this without even considering zombie island. >!Its hard enough to get monthly brains for a city half full of zombies. And remember how many starving kids there were? What stopped those guys from going rabbits day one?!< The level of error involved with feeding zombies, both biological and practical, makes such a city impossible to feed. One of the hundreds of zombies in hiding should have went rabbit after after a year or so. What could have possibly prevented the apocalypse?

[Assistant]
It seems that the infection makes their bodies stop producing certain chemicals necessary for higher brain function, and they have to acquire those chemicals by eating brains. Starve a zombie of brain matter, and they become stupid and hungry.

You are correct, Graves' plan is only a short-term solution, not manageable in the long run, and it could turn into a "zombie apocalypse" scenario under the right circumstances. The primary reason it hasn't is that zombies are compelled to stop after one kill and eat the brains of their victims, which prevents the victims from rising as new zombies. It doesn't spread unless their victim survives the attack.

This means outbreaks are manageable, they progress reasonably slowly, more like the pattern of a serial killer than a contagious outbreak.


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

[User]
[Pokemon] What separates normal animals from pokemon?

I'm pretty sure in season 1 of Pokemon, you see some normal animals, and fish.

What separates those animals from pokemon? I'm pretty sure you could train a cow to tackle someone. Sure, a cow can't evolve, but what's to stop someone from putting a big old bull from a bull fight into the Pokemon league?

"Cow, use trample... No, not on the trainer! Not on me! Oh, christ, get the tranq gun!"...

Other than that I mean. But what's the difference between an animal and a pokemon?

[Assistant]
Pokemon have within themselves a form of power known as infinity energy. This energy is what makes pokemon more than just animals, what makes them able to control the elements and allows them to evolve.

Take a Miltank for example. It may be a "normal" type but this itself seems to be an element along the infinity spectrum. Its normal attacks carry within them some sort of extra energy, which is why moves are limited by power points. Even a simple move such as tackle is actually a way for a pokemon to channel its inner energy.

Therefore a pokemon will almost always be stronger than just a regular animal. Animals and humans (aside from say, psychics but that's a whole other thing) can only rely on their innate physical strength. A pokemon however has their physical and elemental (or special) strength to use in tandem. Thus a cow is a cow, and a rhyhorn is a rock-plated rhinoceros.


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

[User] ELI5:How do we calculate the world's population from 100s of years ago?

[Assistant] Countries have had Census programs since the Egyptian empire. Taking the averages of those, and applying it to other areas with assumed similar population density, allows for a fairly accurate prediction.


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

[User]
ELI5: Why are pain management doctors required to obtain periodic drug screens but medical insurance companies not required to pay for those drug screens?

Several friends and patients are required to submit to periodic urine drug screens in order to remain in the care of their doctor but the insurance plan rarely pays for that required medical lab test.  Why?

[Assistant]
Liability.

The drug tests are to prove that the patient is actually taking the prescribed drug and not selling it, especially if it's a narcotic. If the patient is accused of selling their prescription narcotics, and the doctor has blood test results that support that accusation, the doctor can be charged with a crime. In addition, if the insurance company is found to have aided in the purchase of these narcotics (through medical coverage), they could be found liable, and assessed a fine by the federal government.

As for why the drug test isn't covered by the insurance company? That depends on what the test is submitted as. If the doctor's office submits the claim as "Insurer Mandated Drug Test", the insurer is probably going to reject that claim. If it is submitted as a generic "Blood Test", it has a better chance of being accepted as a valid claim.


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

[User]
Is electric heating inefficient?

I've always been told that electric heating with a personal heater is very inefficient compared to central gas heating. Are they talking cost wise, or energy wise? Or am I just completely mistaken?

[Assistant]
The answer to the question depends on how you define efficiency here. In general heating can be an extremely efficient process, close to 100% in fact. The reason is that virtually all energy you use will eventually be converted to heat. This is equally true for passing electricity through a resistor as in a space heater, burning gas directly for heating, or even running a computer. All of these devices are essentially 100% efficient in taking their energy source (electricity/gas/whatever) and in the end producing heat.

The biggest difference between using natural gas or electricity for heating lies in the overall efficiency of acquiring the fuel, generating and transporting the electricity, and finally heating your home. Consider two possibilities 1) using natural gas to create electricity to power a space heater or 2) using natural gas directly in a gas heater. In the first case, you first need to burn the gas to create electrical energy (which even for the most efficient power plants will only have an efficiency of around 50%), and then you will need to transport this electricity from the power plant to your house (which again will eat up roughly 50% of the energy). So in this scheme you are only left with 25% of the initial energy stored in the gas before you can turn on your space heater. In contrast, in the second case you take the gas tank directly into your house, where virtually all of its stored energy will result in local heating. It is in this more general sense that we can say that gas heating is more efficient than electrical heating.


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

[User]
[General Superheroes] So, which popular heroes actually got their powers from a vat of toxic waste?

This is the definitive cliche power origin, but I don't recall any popular heroes that actually got their powers from this method.

Batman just trained really hard. Superman uses the Sun. Iron Man has a suit. Thor has a hammer. Captain America took a serum. Spider-Man got bit by a radioactive spider, which I guess is *close* but it isn't quite there. Wonder Woman is just a god. Flash got hit by lightning. The list goes on, but none of them are "fell into a vat".

[Assistant] Daredevil got radioactive waste thrown in his face giving him the power of blindness and Two-Face got acid thrown into his face giving him the power of disfiguring acid burns. Also, the Teenage Mutant Ninja Turtles got their powers from the same accident as Daredevil, and theirs is not a disability.


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

[User] [Call of Duty: Modern Warfare] Why did the United States do absolutely nothing when 30,000 troops were nuked? Why didn't they retaliate?

[Assistant]
Al-Asad, the man who set off the nuke, was the ruler of the country the United States was already invading, and had more or less occupied at that point. To the vast majority of the US population, the nuclear detonation was just a suicide bombing on a mass scale; a last, defiant act of a mad warlord willing to sacrifice his own people. Who's there left to retaliate against? The people who did it are already dead, in custody, or living in US occupation.

Within the inner echelons of US and UK intelligence, they likely know of Al-Asad's connection to Imran Zakhaev, the Russian Ultranationalists, and the fact that the warhead was Russian in nature. But hey, what can you do? Zakhaev and Al-Asad are both confirmed KIA, and what else are you going to do? Invade Russia? That's a bad idea in the real world, and in Modern Warfare world, Russia was able to launch a surprise attack on the whole of the continental US, get beaten, then launch right into an attack on the whole of continental Europe (literally from Poland to Portugal) in under a year. For those select few who knew about Russia's involvement, they would also know the utter impossibility of any kind of retaliatory strike against Russia.

Of course, some people did try to retaliate. That was Shepard's whole plan; he realized, like Zakhaev, that the people needed to rally against a common foe to regain their strength, and just as the Russians had rallied under the Ultranationalists, he would rally the Americans under... well, himself, and a mutual desire to punish the Russians for their actions in the invasion of America.


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

[User]
[harry potter] why didn't voldemort hide one of his horcruxes with fidelius charm?

before they said that voldemort did not trust anyone, he had genuine confidence in the bellatrix, enough to hand him the cup. he could have made her the secret keeper of the cave, for example.

another thing, he didn't need to say that this was a horcrux, he just had to say that it was an extremely valuable thing for him.

[Assistant]
Voldemort was really confident No one would even know he had a horcrux, let alone more than one. Like it's mentioned in the books the items he used and the places he chose to hide them were just trophies and spots he wanted to establish permanent attachments to, the security was mostly to stop anyone stupid enough to accidentally get close to them.

With Bellatrix for example, like Harry says he left it with her not because he trusted her but because he had some reverence for the old vaults owned by old discarding family in gringotts, he gave her the cup just to establish a personal link with an ancient Gringotts vault owned by a noteworthy pureblood family.

The only reason Dumbledore figured out he had any horcruxes at all was because Lucius fucked up and tried to use one to screw over Dumbledore and Mr Weasley, even after Voldemort realised Dumbledore new about the book he didn't expect Dumbledore to question why he left a piece of soul so casually with a follower and start the whole investigation into Voldemorts big secret.


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

[User] ELI5: Why can't you just remove the wires from a bomb in order to disarm it?

[Assistant] Some bombs instead of being signaled to go off are instead constantly being told not to go off.  If you remove that signal then they explode.  This is how the abort explosives on rockets work.  They are constantly receiving a signal from the ground saying please don't blow up.  That way if ground control ever loses control of the rocket it automatically explodes and doesn't plow into some random city.


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

[User] (-1)^(1/2) is imaginary, but (-1)^(1/3) is real. What is (-1)^(1/2.5), and why?

[Assistant]
Note that when dealing with roots and complex numbers, you actually get multiple results. For example, -1^(1/2) actually has two values:

1. i
2. -i

Similarly, -1^(1/3) has three values:

1. -1
2. cos(/3) + i\*sin(/3)
3. cos(/3) - i\*sin(/3)

Finally, note that 1/2.5 = 2/5. Thus, (-1)^(1/2.5) = (-1)^(2/5) = 1^(1/5). We therefore need to find the fifth roots of 1. There are five of them, and they are

1. 1
2. cos(2/5) + i\*sin(2/5)
3. cos(2/5) - i\*sin(2/5)
4. cos(4/5) + i\*sin(4/5)
5. cos(4/5) - i\*sin(4/5)

Any of these numbers satisfies x^(5/2) = -1 (and x^(5/2) = 1), since they all satisfy x^5 = 1, and -1 satisfies -1^2 = 1.


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

[User]
What evidence is there in Evolutionary Psych for Hunter Gatherer models?

Hi all,

I've sat through about five Psych courses in the last year, and I've noticed that whenever the class discusses something that might be influenced by social settings, like gendered colour preferences or personality traits, inevitably someone mentions evolutionary advantage for the thing developing in hunter-gatherer societies.

I'm a humanities person, so maybe my questions are going to seem stupid, but I don't understand how something like colour preference could appear so quickly in the genes of a species. I thought humans started organizing into hunter-gatherer societies like 40,000-20,000 years ago, is that wrong?

Plus, I would assume that from the point where those societies arose onward, we would have to attribute a certain amount of psychological traits and changes to cultural influence. I don't understand how or where psychologists (or anthropologists, or historians, or anybody) found evidence for behaviours after hunting or gathering became things that apply globally to every regional group of homo sapiens on the planet outside of, like, cave paintings.

TBH I'm at a point where I don't even feel like evolutionary psych is legitimate. It seems equivalent to using Freudian psychoanalysis to prescribe anti-depressants. Can someone tell me where, if at all, the evidence comes from that supports evo-psych, or can you direct me to some readings so I can understand why it's so ubiquitously used in psych classrooms?

[Assistant]
Color preference shows up way earlier than hunter gathering as humans.  Turtles have color preferences and it has everything to do with optimal nutrition.  Deep reds and blues are great indicators of nutritional value, and then taste to determine carbohydrate quantity and possible overabundance of alkoloids.

If you really want to dig in deep, there are two books that you absolutely must read together. The red queen by matt ridley. DO NOT STOP HERE.  Read Sex at Dawn next.  NOW YOU CAN STOP.  Matt ridley falls a bit into the Gouldian trap of proposing that noses evolve to hold up one's glasses.  Sex at dawn overwrites those parts with another explanation that better explains edge cases and cultural aspects.

Remember, always remember, that agriculture is at best 20,000 years old.  That is insufficient time to significantly to push evolution at the population level.  So almost all traits post agricultural revolution are pitted against and working in concert with our foraging roots.  If people can opt to return to foraging, they absolutely do, assuming the environment is conducive to doing so. Maxing out at 4 hours of labor per day, with the rest committed to social interaction, is what crafted us for 4.48 million years.  Moving beyond foraging has only had .02 million years of evolutionary pressure on the human race.


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

[User]
[Doctor Who] I've heard that an evil Doctor would be way more terrifying than the Master. Is this true? And if so, what does the Doctor have that the Master lacks?

The Doctor holds back... a LOT! But the Master is no slouch, either. And yet, I've heard that an evil Doctor would be far more terrifying than the Master.

Why? Is it intelligence? Resourcefullness? Willpower? All of the above (and more)?

[Assistant]
Ironically? Unlike the Master, the Doctor is good, sane person.

For all their power and genius, ultimately all The Master's plans are basically more complex variants on "show up in a place and stab people until someone stops them". They don't really have any ambitions beyond wandering around the cosmos ruining people's lives at random- they're basically just that bedwetting kid who tortures animals but a genius with supertech.

But the doctor *cares*. They're not just at this for the fun of it like the master, they're not a mad child throwing a cosmic temper tantrum. They're *dedicated,* they have a *purpose.* They want to make the universe a better place and will do anything to accomplish that. And there's little more dangerous then someone who thinks that hurting you is their sacred duty to the world.

It's the difference between the serial killer and the terrorist leader. The serial killer can do a lot of damage, but ultimately they're just a broken person lashing out and they lack the ability to do much more then gut people in dark alleyways. The terrorist leader, meanwhile, is sane and rational. They think that they're making the world a better place, fighting the good fight against malicious enemies, and that allows them to leap to a whole new level of threat.


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

[User] [Harry Potter] What happens to ghosts like Nearly-Headless Nick when the Earth eventually explodes or gets eaten by a red giant Sun?

[Assistant] Ghosts are imprints of souls on the Earth.  No Earth, nothing to imprint on.  Sometimes ghosts are cited as only being able to haunt places they've been in life.  When all those places fade into the shadows of history, so too fade the ghosts that live there.


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

[User]
[Star Wars] So does Vader ever feel angry at himself for having not listened to Obi-Wan about the high ground?

I mean, Obi-Wan *warned him* not to go for the jump. He went for it, he lost his legs, then got fried. Does he ever feel bitter that he didnt just wait a minute or two until he found a more advantageous position to get back on shore?

[Assistant]
Vader's entire existence is self loathing over all they ways "The Jedi" failed.

Vader thinks of Anakin as a separate being. And when he says "I destroyed him" when referring to his old identity, he's telling the truth... from a certain point of view. His pain over everything Anakin lost has broken him so much that he'd rather think of his past as a separate entity than dwell on it.

Except that he does dwell on it. All the time. One reason he's so freakishly powerful with the dark side, aside from being the chosen one, is that he keeps all of his internal pain roiling like an ocean of lava. And that includes reliving his duel on Mustafar. Mentally kicking himself for missing every chance to end the fight on his terms, the high ground included. So yes, he is extremely bitter about it. And it only makes him angrier to see Obi Wan again on the Death Star.

Granted, other losses weigh on him quite a bit more. Losing Padme above all.


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

[User]
What would happen if you jumped in a gravity-simulating centrifuge?

Like the ones in Interstellar or The Martian. Since there's nothing pulling you to the rim, after you've overcome your own inertia by jumping, would you just gently float above the 'ground', with it rushing beneath you? Would you slam into the nearest wall opposite the direction of turning?

If you jumped high enough, could you float to the center and just stay there?

I Imagine the moving air around you would eventually build up enough momentum that you'd contact the ground, which might be uncomfortable if it was spinning fast enough.

[Assistant]
When standing still, your *acceleration* is inwards towards the centre of the ring, provided by the floor beneath you. Your *velocity* is *tangential* to the ring. That is, if you're standing on the inside of the rim of the ring, facing the "forwards" direction that the ring is rotating, your velocity at any moment is also "forwards". Your velocity does constantly change (this is the acceleration) so that your "forwards" velocity changes direction to match where you are at the ring.

The acceleration is provided by the floor beneath you, but you keep your velocity unless something actively changes it. If you were standing inside a rotating ring, and the ring suddenly disappeared (maybe the floor just breaks), then you would just continue to float forwards in the same direction. If you draw a circle, and at some point stop curving and just keep drawing in a straight line, that's what your path would look like.

Similarly, when you jump, you add an additional inwards component to your velocity, but your forward velocity does not disappear. Instead, you are now going *forward and inwards*. This means your path will intersect with the ring again, a little bit forwards and up from your initial position. However, as the ring is rotating at a very similar speed, when you contact the floor again will be pretty close to where you lifted off. For a very big ring, it will feel just like jumping on the spot. But for a small ring, you will notice a bit of a shift.


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

[User]
[Arkham Knight] MAJOR SPOILERS, Question inside.

How does having the Joker's blood inside you turn you into the Joker? His blood isn't psychotic, his brain is. Am I missing something?

[Assistant] I think the implication is that the blood didn't infect them with the aftereffects of Titan, but with the chemical mixture that caused the creation of the Joker. The vat of chemicals that originally turned the Joker into the Joker basically infected him with a new disease causing him to look and act the way he does. The Joker would be the final result of this transformation, and the virus would be in his blood and transferable to others. This disease gives you green hair and eyes, red lips, and chalk white skin as well as changing your brain function, causing you to develop violent tendencies, obsessive behavior, manipulative tendencies, megalomania, and a twisted sense of morality. All the patients Batman rounded up displayed some of these signs, and if they lived long enough for the transformation to complete then they would all essentially be just like the Joker.


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

[User]
[Matrix] Would it be possible for someone who didn't know how to code to be The One?

From what I understand, Neo's experience with hacking allows him to quickly modify the code in the Matrix around him to do things like slow down bullets and fly. Could you drop someone with no experience in and expect him to do the same?

[Assistant]
It's not really their ability to code that allows the Rebels to stretch the limits of the Matrix, but rather their mental discipline. Neo doesn't consciously rewrite lines of code, he just wills the Matrix to change, and the program responds to what he believes he's capable of.

"Stop trying to hit me and hit me!"

As for why most of the Rebels are drawn to computers for answers before they get unplugged, that can be explained as their subconscious mind leading them to the truth of their reality.


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

[User] ELI5: Why isn't anyone going to war with North Korea to try and stop how they treat their people?

[Assistant] too much of a nuclear threat and not worth upsetting relations with china. NK is a puppet state that was partly established by China and completely depends on china's support for survival. Attacking NK would be seen by china as a direct attack on their interests and sphere of influence.


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

[User] ELI5: What happens when we recycle things, and how do we turn it back into usable products?

[Assistant]
It depends on the material

What happens is they first get sorted into different basic types of materials like paper, metals, plastics etc. Within these groups there might be different forms of further sorting, such as magnetic from non-magnetic metals, or different types of plastics.

In the case of paper products, it's broken back down into fibers where can be rewoven back into weaker papers. So its diminishing returns, good paper products might be turned into things like toilet paper, paper towels, or tissues, but you can't really recycle a tissue into new paper, it's already been processed too much.

Metals and glass products can basically be melted down and remade into new metal and glass products almost indefinitely, they are the "Best case" things to recycle.

Most plastics aren't really truly recyclable and the market for recycled plastics is weak. Best case is you can grind them into a dust and "Blow" that dust into fibers for clothing. Things like fleece jackets can be made from 100% recycled soda bottles. Or you can compress the dust into things like decking, chairs, or picnic tables. Unfortunately the market for these products is so weak, the cost is so high, and quality of recycling (your average person doesn't really understand how to separate their plastics properly) is so poor that the vast majority of recycled plastics are either just collected and thrown away in landfills, shipped overseas where *they* throw it away, or burned on cogeneration plants (a power plant the burns trash as fuel).


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

[User] ELI5: If my brain controls my hands, why can't I draw things as well as I can see them in my mind?

[Assistant]
Because the first thing your brain does with an image is interpret it. It does not see the outline of a nose it sees "(symbol for) nose", which is a simplified version. So when you try to recreate this, you get "(symbol for) nose", which only looks more or less like "(outline of) nose".

Artists need to learn to "see differently", to make their brain stop interpreting, so to say. Draw what you see, not what your brain thinks it sees.


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

[User] ELI5: If the Devil is such a bad guy, than why would he punish people for sinning?

[Assistant]
In many traditions, he doesn't.  He's in Hell being tortured along with all of the sinners.

In other traditions, he's just an overall angry guy who will torture anyone.  People in hell are just convenient.

In jokes, he's usually a real nice guy, until a punchline ending in sex with Bill Clinton.


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

[User]
Is a solid just a liquid with really high viscosity?

Title. If a liquid achieves a high enough viscosity, does it start being considered a solid?

[Assistant]
In general, no. A fluid with high viscosity will deform continuously under even an infinitesimally small amount of force over sufficient time. A solid won't.

There are composite materials, such as gels, which blur the lines, but only because they're more than one material linked together.

Lots of solids can be *fluidized*, like sand, but these are composite, as there are gaps, and therefore air, making them act as composite materials again.

The only way a solid can be a liquid with high viscosity is if you accept that at some point, that viscosity is permitted to effectively be infinite or permit the material to crack or deform.

But that's just it: the very definition of solid precludes that it cannot be a liquid or a gas. Period.


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

[User]
Do microwaves leave residual changes to molecules after heating?

Have a coworker who claims microwaves have a residual impact on the molecules in food and this is what causes microwaved food to taste worse than oven-baked food.

I've been puzzled by this since from what I know microwaves just excite water molecules and cause them to heat their surroundings. Yet he claims this changes the molecules in minorly-unhealthy ways.

He also claims the effect of microwaves on food aren't understood, something which I am incredibly sceptic of in this day and age with all the nutrition agencies around the world.

So my question is: do microwaves have any residual effect on food beyond the heat from excited water?

[Assistant] No. Microwaves aren't energetic enough to be ionizing, they don't cause any other changes than conductive heating or radiatiative heating with IR (that is, grilling). Note that this is a feature of the individual photon energy, i.e. it doesn't matter how high you turn up the microwave because that increases the amount of microwaves hitting the food but not the energy of the individual microwave photon. This is the same reason why Wi-Fi (same micrwave spectrum) doesn't cause cancer.


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

[User]
On 'To Catch a Predator' how are they allowed to show the faces of the pedophiles on national television when they say they don't want their faces shown?

I thought it was illegal to show people's faces on television without their permission, that's why so many are blurred in news stories, documentaries, etc.

EDIT: ephebophiles, not pedophiles.

[Assistant]
Dateline is a news show rather than mere entertainment so it doesn't have to follow the same rules.  It's a sting operation and the ephebophiles* are arrested.  That make it news, despite it being entertaining to watch.

*pedophiles are people who are attracted to prepubescent children, usually under age 13.  The people being caught on that show are euphebophiles, which is an attraction to adolescent minors.


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

[User]
ELI5: Were the Space Shuttles really so bad that its easier to start from scratch and de-evolve back to capsule designs again rather than just fix them?

I don't understand how its cheaper to start from scratch with entirely new designs, and having to go through all the testing phases again rather than just fix the space shuttle design with the help of modern tech. Someone please enlighten me :)
-Cheers

(((Furthermore it looks like the dream chaser is what i'm talking about and no one is taking it seriously....)))

[Assistant]
The problem with the Shuttle wasn't so much that it was an old design but that the *basic idea* of the Shuttle is painfully inefficient.

It takes a lot of energy to move mass high enough & fast enough to even start orbiting the Earth.  If you want to travel away from the earth, there's even more energy involved.  The Space Shuttle orbiter weighted 150,000 pounds empty - by comparison, the new Orion capsules are only about 20,000 pounds.  That's 130,000 pound of "it's cool to fly like a plane when you're landing" which complicates *everything* about space travel.


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

[User]
[Star Trek] Why is it even possible to disable safety protocols on the holodeck?

Especially on a starships holodeck, it seems like disabling the protocols can only lead to bad things, like a damaged ship or injured/killed crewman. What are some positive examples that require the protocols to be off?

[Assistant]
Starfleet is not a military organisation. We hear that time and again. Yeah - don't kid yourself.

Holodecks are used mostly for entertainment now, but in the early days they were developed as a research tool - and specifically a research tool for the officially non-existent military section of the fleet. And when you are simulating prototype weapons it is pretty much a given that some thing you will want to do will not be safe - so a safety override was essential.

Later on, when they are installed in just about every starship, they are still there for research among other things, and even in engineering research, you will need to simulate forces and mechanisms that are simply not possible to do fully without an element of hazard - so responsible officers are still able to deliberately disengage the protocols that are usually in place when the decks are being used for whatever sleazy holonovels are in fashion otherwise.

Of course, the software is pretty much universal, so even in civilian setups - the kind of thing that are used in bars on deep space stations or where ever - any self-respecting hacker can get into the settings and disable the safety protocols there too if they really want to.


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

[User]
If entropy increases with time in the universe, then how come the stars and the planets have formed?

As time progresses, entropy of the universe increases. But the stars and the planets have condensed from the primordial gaseous soup(of high entropy) to a state of low entropy(now). How?

[Assistant]
The formation of structures such as stars and planets, primarily due to the influence of gravity, adheres to the laws of thermodynamics just as every other physical process in the universe does. These "pockets of order" are offset by the heat and radiation that was necessarily emitted back into the universe during their formation.

In turn, we as "life" are actually, in a way, "feeding" off the lower entropy in these pockets. Life creates order out of chaos, but it can only do this by emitting back a greater amount of disordered heat back into the cosmos (more entropy out than was put in).

As you are reading this sentence, your brain is forming memories (ordered), and therefore is necessarily warming up a little bit and adding a little bit of heat (disorder) to the universe. That's why your brain is stuck out on your neck in a hard almost spherical skull -- to dissipate the heat, rather than stuck in your belly in a hard casing for protection.

The same thing is going on in the CPU of the device you are using to read this sentence. It's why it needs cooling and consumes energy from the battery/power, and the whole thing constantly gets hot, and runs down.


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

[User]
I have a bachelors in music education but Im interested in clinical psychology. Will PhD programs even take me seriously?

My undergrad did involve some psychology classes, and I have taught in public schools for three years, but I will obviously be behind someone with a BS in psych. I have a respectable GRE score and research topics that interest me. Im curious as to whether or not the effort and expense of applying for graduate psych programs would be worth my time. I dont know much about the culture of such things.

Thanks in advance!

[Assistant] You wont get into a PhD clinical program. They have higher rejection rates than Med school due to demand. Youll need two years of lab manager work or a Masters in SW or Psych. Research experience is tantamount.


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

[User]
ELI5: What would prevent the U.S. Military from a coup on the U.S.?

I assume there would be some safeguard measures in place? I assume a lot has to do with the varying mindsets and views that make it impossible for a consensus amongst the entire military to agree it would be a good idea to overthrow it's own country, but we would have to have more than a total reliance on social policy to prevent such a thing from happening. The government plans for ALL scenarios, so I don't see how one like this would be magically over-looked.

[Assistant]
Military officers rotate often, this is on purpose.  It develops a broad base of experience and it prevents a "cult of personality" from developing.

We also have a relatively top-heavy force structure which would make it more difficult.  If one General wants to take over, he has to convince a lot of other generals it is a good idea, where if they were all colonels it would be easier to just give orders.

Also, congress has to approve all flag appointments.


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

[User] [YU-GI-OH's - All Series] Why do the duelists explain the rules and effects of each card to each other in battles, wouldn't they already know all this being top tier players?

[Assistant]
There are a *lot* of cards. And the top tier players have some rare cards that they don't want **everyone** knowing the secrets of.

And a lot of the time, they are explaining how their card combos with another card, another thing they don't necessarily want to advertise before they use it, because it just makes it that much easier to counter.

And of course, there's Pot of Greed, and who can even remember what that does?


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

[User]
What is the difference between a router, switch, and hub?

I understand that a modem is used to basically translate a signal (from cable to Ethernet, for example).

I understand that these three devices are used to route packets between connected devices on a network, but what exactly is the difference, and why would you choose to use one type over another?

Are there other devices that fall into this same category that I am missing?

Thanks for the clarification :)

[Assistant]
Very generally speaking:

* Hubs are the lowest level, and they are basically dumb machines.  They take all data coming in one input and broadcast it to the outputs, then receive data from the outputs and send it back to the input.  Think like a USB splitter.

* Switches are a little more intelligent.  They can detect packet collisions and manage multiple packet streams going to multiple inputs and outputs at once.

* Routers are the most complex, and are basically full fledged computers than can manage data almost like a server.  They can provide NAT translation to subnetworks, QoS, run dhcp, etc.


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

[User] ELI5: Why Sia doesn't show her face, despite being photographed multiple times at high profile events and being classically beautiful?

[Assistant] She said that she wants people to focus on her vocals and performance of hue dancers she usually has, and not how she looks. It has backfired for some people, because all they think about is her hiding her face and not focusing on the performance.


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

[User] Thinking about the umbilical cord, at what point is it the mother's DNA and at what point is it the baby's DNA? Is there a point where they're mixed?

[Assistant]
The umbilical cord is entirely the babys tissue. But the placenta is the interface between the fetal bloodstream and the mothers is the closest the two come to mixing. But they never actually do. During a healthy pregnancy and birth, a mother and her babys blood would never mix.

Edit: Placenta is half mother and half fetus.


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

[User]
ELI5: How do they build those rickety rope bridges? I can't wrap my brain around it...

They always seem to be in the middle of nowhere and I just don't understand how it could possibly be constructed. I'm imagining that they pre-construct it, have a buddy stand on the other side and continue to toss it over until it finally makes the gap.... this cannot be the case. Please Explain!

[Assistant]
Generally you take a thin rope that's a lot longer than the gap, secure one end and take the other end the long way, down through the valley or whatever. You pull it tight and secure it, then you can use that rope to pull across a bigger, heavier and stronger rope, and do that as many times as you need until you've got enough strength to carry workers who build the thing out into a full bridge. Yes, this does mean hanging from a few ropes over an abyss while building the bridge.

Sometimes people even take the first string across with a kite.


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

[User]
(Zathura) In Zathura (and to a greater extent, Jumanji) what would happen should one of the players die?

Does the game reset and they have to play again? Are they actually just dead? Does everything just go back to the way it was before they started playing? Or are they stuck in the game, with no way of being able to finish it?

And what was up in Zathura with Walter's future self? Was he from what *may* have been/a separate timeline? Technically he may have been able to roll for present-Walter in this scenario as well.

[Assistant]
A death - a *natural* death, not a "I wish you didn't exist" death - simply means that player loses, and the remaining players get to continue to play as if the dead player's turns were being skipped. What the two sets of players failed to appreciate is that the board games, though incredibly vivid, are meant to be *fun* (and more importantly, winnable). There aren't supposed to be actual consequences; this is why Jumanji resets itself to the moment before the game is played. If everyone dies, they respawn at the beginning with a cute "game over" message.

Future Walter was basically being punished for cheating. By wishing Danny out of existence, he made it impossible for himself to lose, so the game couldn't continue - it's meant to be winnable, but for the team as a whole. And he was basically from a projected future timeline, based on the time powers that these board games clearly display.


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

[User]
CMV: The way you win at life is by spending the most time being happy.

Hi Reddit,

I teach in an inner city elementary school.  For the past decade or so, Ive taught my students a simple life philosophy: The way you win at life is by spending the most time being happy.

The idea being, when your life is at its end, if you spent your time being happy, you can pass on in peace with a smile on your face.

I wont go into all the nuances but I do explain to my students that focusing too much on short term happiness might make you unhappy in the long run, and likewise, spending too much energy on a perfect end game, might make you miss the small moments in between.

I believe this correct but I truly love the kids I teach and in many ways they are my happiness.  So if you disagree, Id appreciate your response.

Thanks and have a really great day!

[Assistant]
The problem here is that it's meaningless - it's a platitude that doesn't change behavior.  happiness is an _outcome_, and while it may or may not be the most important outcome, there is essentially no difference between the statement "the way you win at life is the spend the most time being happy" and "the way you get to be the most happy is to win at life".  It simply _does not inform behavior_, making it non-instructive.

There are - of course - moments when saying "what would make you happy" where the pause allows someone to reflect on the situation and make the right decision, but this is really a simplified way of saying "step back and look at your choices and which one do you really think is the best one".

Lastly, there are times when people should suffer more to do good.  If you believe that this brings you happiness then you're stuck in the meaningless problem of number 1, or if you think that it's just true on face that your suffering in exchange for some other good is the right thing to do then you're saying that "doing good" can be more important than happiness.


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

[User]
[Fallout Series] ELI5: The physics of the Power Fist?

Now, don't get me wrong, ever since I looted it off that Raider who was all jacked up on chems, I've loved using my power fist. I make sure to keep it in really good condition and it is *great* for fucking up radroaches and crippling-- well, anyone who gets too close for comfort. But I don't really get the science behind the thing and usually feel vaguely uneasy that one of these days it is going to rip my arm off while I'm using it. I haven't found anything  in my *Big Book of Science* that is helpful.

 Can anyone ELI5 the physics involved?

[Assistant]
The power fist is a mechanical glove mounted with a hydraulic piston powered ram. When punching, the pistons push the ram forward, smashing into the enemy. Sometimes, enough power is transferred to the target to knock them down.

So, in effect, you are punching them with a piston-powered hunk of hardened metal rather than your squishy, easily broken, fist.


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

[User]
Eli5: Why do we not desalinate our ocean water as a viable resource for water?

Seriously, I've been thinking about the major draughts around the world. Our planet is like 2/3 water. Why can't we just use that?

[Assistant]
It's enormously energy intensive, and electricity is expensive. A desalination plant basically requires it's own nuclear core to provide water enough for a small city, and a bigger city like LA would need several plants.

But that isn't going to stop us. We're doing it anyway - in fact, desalination was one of the main reasons Iran insists it needs nuclear energy.


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

[User] ELI5 What is the biological reason that we are able to grow long strands on our head?

[Assistant] The strands of hair from our scalps/heads grow longer because the hair follicles there have a much slow "turnover rate" programmed into them than the hair follicles in, for example, our arms. In other words, your arm hairs fall out much more frequently, so they don't have the chance to grow as long.


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

[User]
Does gallium dissolve gold?

I'm looking to use gallium as the liquid phase in an electronics cooling setup.

If I were to make the cooling block and the radiator out of gold plated silver, would the gallium phase dissolve the gold plating or otherwise destructively interact with the gold/silver solid?

[Assistant]
I can't find anything on gallium on gold, but gallium on aluminum is a nogo.  Liquid metals are not friendly to solid metals typically though, they like to infiltrate and do other strange things.

This does feel like a bit of an XY problem though, why are you trying to use gallium as a heat carrier?  Why not use a well documented coolant like water or oil?


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

[User]
[Doctor Who] What do the psychological and mental changes of regeneration feel like?

Let's say that I start regenerating into my next 'incarnation'. Obviously, I'm going to look different, but what of the mental and psychological changes?

If I loved apples before, while I regenerate would that instantly 'reverse' to hating apples? Would what I was thinking during regeneration change, in terms of feelings and mental processes? Would it be like flicking a switch? Would a stranger I met and thought to be cute suddenly seem to be average in my opinion?

[Assistant]
Whilst the Doctor is a bit of a unique case, you kind of have to base it off them.

(Going from Doctors 9-12, as I've only seen the new series) There is a retention of memories of people and places, and general ideals/mannerisms (see also the Master), but each Doctor has a unique level of flair; whilst The Doctor is always eccentric, they will deal with problems slightly differently, and have unique perspectives ("What you do in your regeneration is your business" or some such in a crossover episode).

It also takes a bit of time (a couple of days generally) for The Doctor to return to full mental and physical health, and will be disoriented for that time and relatively weak. Though the change to the 'new you' takes place immediately.

The start of 11's run showed that tastes change after regeneration (sorry, it's possible you will hate apples now), however their opinions on people relatively stayed the same, and they will still be attracted to the same people (9-10, 11-12) (that person will still be cute in your case, hopefully they're still attracted to you).

Overall, it's quite a dramatic change in  unique mannerisms, but there's a retention of the same base, most memories, and relations with people. These changes are basically immediate, but it will take them a few days to get out of the disorientation and back on the feet.


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

[User]
CMV: Pokemon is just like Call of Duty.

Since X and Y has been announced everyone has been going wild over Pokemon and the world rejoiced(exaggerating). I noticed that as soon COD: Ghosts was announced it received an UTTER SHITSTORM

To clear up ANY misconceptions I just want to say I enjoyed Pokemon as a kid growing up, and I enjoyed Call of Duty growing up. **AND I AM NO WAY SAYING THAT THE GAMES ARE ALIKE IN ANYWAY OTHER THAN WHAT I AM STATING**

Quite a few people in recent years have complained about how Call of Duty is the same and that they never come up with anything new to refresh the series. Call of Duty games are all alike because it is a game method that sells, HIGHLY. Of course if it's Call of Duty everybody hates it but when it's Pokemon everyone goes wild. 14 Call of Duty games exist right now, including Ghost

Now tell me what exactly has Pokemon done? Have the exact same game interface(until recently) just like Call of duty does, shell out 19 different games according to what I've looked up. Both have large fan-bases and both sell VERY well. I've kept this view to myself because apparently I'm the devil if I speak against Pokemon in anyway. Well here it is.

Change my view.

[Assistant]
Call of Duty put out fourteen installments in ten years. Pokemon put out seven installments in twenty years.

A good sequel needs time to bake. Annual releases don't allow enough time for anticipation to build up. Pokemon waits long enough between installments for its fans to actually get excited about the new games before they're released, and the longer development cycle gives them time to make more substantial improvements.


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

[User]
[Daredevil (comics version)] Does Matt Murdock often use his legal abilities to his advantage as a superhero? Legally implicating villains, avoiding certain infractions of the law, etc.

.

[Assistant] Yea. All the damn time. He got arrested a million times on suspicion of being Daredevil and he gives the best sitcom defense (Only Matt Murdock could ever defend him!) Then just pretends to be a scared blind guy and always gets away with it.


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

[User]
[Star Trek] How hard is it to get accepted into Starfleet Academy?

Is there any lore regarding that?  Do they only take exceptional applicants or is enrollment a little more open?

[Assistant]
Starfleet Academy only accepts the best. Cadets must undergo a battery of tests after their initial application is accepted.

From Memory Unit Alpha

>Dynamic relationships test- a spinning 3D cube consisting of a grid of blue dots in a 666 configuration, totaling 216 individual points. Surrounding the cube were 216 red dots flying around in a seemingly random pattern. To complete this test each of the red dots must match up with a blue dot. The solution required discovering the appropriate rotation factor and vector coordinates.

>Hyperspace physics test- among others, it featured a trick question: "If the matter and antimatter tanks on aGalaxy-classstarshipare nine-tenths depleted, calculate theintermix rationecessary to reach astarbaseone hundred light years away atwarpfactor 8." It was a trick question because there is only one matter/antimatterintermix ratio, that being one to one.

>Psych test- this test allowed the candidate face his or her deepest fears. The test itself was tuned to the experiences of the candidate.Wesley Crusherfound this section of the test the most difficult and fearsome.

>Otherculturesandspeciestest- not always announced in advance, its purpose was to test the candidate's reaction to a member of another species. The reaction of the candidate was important.

>Carlundrum IQ test- here the candidate had to predict the variable patterns of platonic solids. The response time was important.


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

[User]
ELI5: Back when there was no written or spoken language, how did people think?

Did cavemen think in grunts or something?

[Assistant] I think of it like, you know when you're trying to think of a word, and you can't think of it, but you still know the feeling you're trying to portray? Like if you couldn't think of "dangerous" to describe walking close to a cliff. You would still have all the feelings, but not the word. Now imagine that's everything, all the time.


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

[User]
Because light has momentum, can it move an object with a defined mass?

Could light be used say in space to move a spaceship at high speed?

[Assistant]
Yes. Solar sails have been used to transfer momentum from light to spacecraft. The Mariner 10 used radiation pressure on its solar panels to adjust its attitude, and the JAXA IKAROS spacecraft utilised a solar sail as propulsion.

The amount of propulsion provided is minuscule, but it would be useful for extremely long journeys.


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

[User]
CMV: the original method is better than common core maths.

Why was it changed? Who changed it? I really need someone to tell me what's so special about this new way of doing simple maths. I don't understand! Well... I do understand how it's done but I don't understand why it's better than the original method. I mean, if it isn't broken don't fix it am I right!? I know a lot of parents that are even more confused because they don't understand how this new maths is done therefore leaving them unable to help their children with maths that require them to show their work. Should they relearn mathematics? No! Because what they originally learned was not wrong, but I've heard too many stories about children getting low grades as a result of their parents helping them with their homework because they "did it wrong" even though they had the same answers just different work shown.

Edit: my view has been changed. Thanks for all your comments.

[Assistant]
common core is a curriculum, not a method.

One part of the common core curriculum that some people are upset with is teaching several means of computing addition and multiplication.

These means of computing addition are meant to convey the mathematical properties of addition, so that the student not only understands how to add numbers like 5 and 8 but understands the principles behind addition sufficiently to go into algebra with an intuition for how to apply their knowledge of addition to quadratic equations.

people who learned mathematics as rote memorization will struggle to pick up new approaches that are meant to convey underlying principles, sometimes in part because those adults never learned the underlying principles (and relied on rote memorization of mnemonics like FOIL instead of an intuition for basic mathematical properties of addition and multiplication).  These underlying principles are important.  They do convey a deeper understanding that enables students to pick up later concepts faster and retain them better.


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

[User]
Are black holes all thought to be homogeneous internally, or is it possible for a large enough collection of massive objects in a small enough space sufficient to create an event horizon?

I have a layman's understanding of physics and astronomical phenomena, so please forgive me if this question is absurd.

However, it occurred to me that it might be possible for enough material- such as suns and so forth- to be in such close proximity that their collective gravitation creates a black hole to outside observers, even though it isn't really a single blob of matter- but for all intents and purposes it would still appear that way to outside observers.

I guess my question is- is this possible, or is it something that would be rendered impossible by the requirements for how dense a mass must be to create an even horizon?

Thanks!

[Assistant]
Eclectic mixtures of matter inside the Schwartzchild radius will form a black hole.

They won't stay eclectic mixtures of stuff, however.

An outside observer will only be able to tell their total mass, total charge and total angular momentum. Nothing else.


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

[User] [Marvel] Does Spider-Man stub his toe, get paper cuts, bite his tongue, or make any of the other painful mistakes the rest of us do? Because Spidey Sense.

[Assistant]
Depending on where in the continuity you are thinking it is possible that a blood relative may do something that causes that kind of low level pain.

In an old issue of Amazing, Aunt May knocked Peter out because she thought he was a home intruder. His spider sense didn't register it because Aunt May was filtered out by default as a friendly party.

It's entirely possible that this flaw was immediately fixed if you believe spider sense is a practicable skill.


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

[User]
ELI5: How did the nature documentary planet earth get such incredible footage ?

Are the cameras planted? Some of them it feels as if the camera was on the animal almost- it's amazing that the animals are not bothered by the cameras.

[Assistant]
Start with really good camera's and phenomenal lenses.   Add in a good documentary cameraman.   Tell him to go film nature for a year.

Then trim out 99.99% of the footage and cherry pick the most amazing shots.


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

[User]
If time dilation increases exponentially as an object approaches a black hole's event horizon, how does anything ever reach the singularity?

I've read that time dilation tends toward infinite as an object approaches the event horizon of a black hole. Time passes normally for the object itself, but to an outside observer they would see the object move slower and slower, until eventually it red-shifted out of the visible spectrum.

However, for outside observers not under the influence of the black hole's time dilation, wouldn't that mean that any object falling into the black hole takes billions of years to actually cross the event horizon? If so, how does matter actually reach the singularity? Wouldn't the majority of every black hole's mass be currently in the process of still crossing the event horizon, given the age of the universe?

[Assistant]
Well, the key point is that time passes differently for different observers. So yes, someone looking from far away would see everything quickly redshift and essentially become frozen and dark right on the surface of the black hole (at least until it evaporates).

But from the perspective of whatever is falling into the black hole, time passes normally, and things take a finite amount of proper time (that is, time as measured by them) to reach the singularity.


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

[User] ELI5: What exactly was Prussia vs. Germany? What exactly was Bavaria in relation to both? I'm trying to get a handle but it's very convoluted with monarchies that covered different countries, and independent states that aren't really independent, but also had its own monarchy?

[Assistant]
Germany is a modern nation state that was created in 1871. It unified several of the German states, two of states included Prussia and Bavaria.

In the middle ages, there was realm called the Holy Roman Empire. This empire has origins in the empire that Charlemagne created in France, the Benelux countries, and western Germany. However the HRE shifted more towards the Germany states, as well as other central European powers. Within the Holy Roman Empire was the kingdom of Germany, and many of the early HRE emperors were Germans (such as the Ottonians).

In the early modern era, the Hapsburg family became the Holy Roman Emperors. This family comes what from what is now Austria. That is why Austria became the leading nation withing the HRE in its later history. During the Napoleonic Wars, the HRE collapsed and was essentially replaced by the Austrian Empire.

Starting in the middle ages, the Hohenzollern family became powerful in North-East part of the HRE, which is Prussia. They basically replaced the rule of the Teutonic Order. First as a duchy then as a kingdom, the Prussian country grew real powerful real fast, and essentially became a competing power to the Hapsburgs rulers of the HRE. In the late 19th century, it was the Prussian that really pushed for German unification and were the driving force in that. The German Emperors were Hohenzollerns.

I am not too familiar with the history of Bavaria, but they were a duchy and then kingdom that was a part of the HRE. They were mostly ruled by the Wittelsbach family. They joined the Prussians during the push to unify Germany.


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

[User] ELI5: If bathroom hygiene is so important why don't we get sick after performing oral sex?

[Assistant]
It's more a matter of frequency. If you consider all the times in a day you touch a person (shake hands, etc.) or touch something they touch (doorknobs, etc.), it ads up to a lot of exposure.

If you sucked that many dicks, every day, from that many random people, you would probably get sick a lot.


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

[User]
[SW:TFA] Did Kylo Ren found the Knights of Ren; or did he just join them and become their leader?

While writing this it actually became a two part question; did Kylo Ren found the Knights of Ren, and is his name Kylo of the Knights of Ren or are the Knights of Ren titled as such because his name is Kylo Ren?

In TFA, Snoke refers to Kylo Ren as "master of the Knights of Ren" when Ren is telling Snoke about "the scavenger" resisting him. General Hux refers to Kylo Ren as Ren, now this is either a militaristic sign of respect, in calling people by their last name; or Ren is what he goes by. I bring this up because if that is his 'name' then it's possible to assume that the Knights of Ren were named after him. Or the other option is that his name is Kylo and Ren is the title given because of being a member of the group Knights of Ren.

I've been thinking about this since before the movie was released and pretty much every time I have watched it since (well over 30 times). So is Kylo Ren the founding member of The Knights of Ren? Is his name Kylo Ren, in regards to addressing hi; is he Kylo or is he Ren, or is it as simple as what we have been given Kylo Ren. I personally thought it was Kylo, a combination of s-KY-walker and so-LO.  I may just be putting way too much thought into this.

[Assistant] He did not found the Knights of Ren.  Ben Solo assumed the name Kylo Ren upon becoming a Knight of Ren.  It's a naming convention similar to the Sith, they don't all have the first name Darth.  "Master of the Knights of Ren" is a rank similar to Master Jedi.  There are more than one.  Hux refers to him as Ren quite possibly because he is not aware that it's not his official surname, though for all intents and purposes, it *is* his official surname now.


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

[User] ELI5: Why must we forget things, and how does the brain 'choose' what to forget?

[Assistant] Memory is often compared to a hard drive, from which you need to erase something once it's full and you want to store something new. But the problem is not so much the availability of storage, but the availability of access. Your brain is like a big forest full of different trees called neurons and a memory can be stored by making a certain connection between those trees called synapses. How available that memory is basically depends on the strength of that connection. If you just walk the route along the trees of that memory once, you have a very shallow path that you may be able to find back once or twice, but if you don't use it for a few days it will overgrow and trees along that path will probably become part of another path soon. The more often you walk that path, the more prominent it becomes and the easier it is to find and follow in your forest. This steps over a lot of complexity like 'how does a path determine what memory or knowledge is stored' but it explains a lot of things about learning, like why you can learn something the day before an exam then forget it, or study it for six weeks and retain it for much longer. The analogy also shows that there is no active selection process, or automatic 'least recently used' logic. Sometimes if you don't use a path for a while it may disappear completely, but if it was prominent enough to start with you may still be able to find it later.


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

[User] ELI5: Why has belief in the Illuminati recently sprung up in the hip-hop community and, subsequently, mainstream pop culture?

[Assistant] It's like something you want to believe even though it is clearly not there. Think of a ghost story or the Lochness monster. There is no proof that they exist yet people still believe in them because of the thrill of it. Not only that, but you can show random things make it look like proof. If a door randomly opens at night, someone is going to use that as a proof that ghosts exists. Now if a musician decides to place the all seeing eye (The triangle with the eye) on their album, people assume its illuminati. Now think of it this way, this stuff sells. Once the rumor spread, artists started deliberately placing symbols on their albums and videos. People will listen to it and buy the stuff to prove it to their friends that illuminati exists but in reality, it's just marketing. It's like the Ghost hunters of music.


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

[User] How can saunas have temperatures between 158 and 212 degrees F and not burn compared to something like a hot tub which operates at a lower temperature?

[Assistant] Water conducts heat much better than air. It takes longer for the hot air in the sauna to transfer the heat energy into a person than it does for water to transfer that energy. Additionally, you can sweat in a sauna. The sweat absorbs energy and takes some with it when it evaporates. Eventually though, the sauna can cook you, if given enough time.


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

[User]
[Superman] Could the sheer force of Superman's stream of piss break a toilet?

If Superman were to take a piss at full force, could he break a toilet with it?

[Assistant]
Trivially. He could let loose at a urinal in the 10th floor lavatory of an office building, aiming exactly straight down (he may need to hover for the right angle). That stream's leading plane would shear straight through the porcelain coating, through the metal, back out the other porcelain side, through the floor layers, through the next nine levels of urinals and floors, continue through the eight levels of concrete reinforced parking garages underneath, and then keep punching down into the Earth below. Eventually it would bleed off sufficient kinetic energy that it simply became a little puddle of pee that got diffused into the soil.

Elapsed time for all this: microseconds, *if* that.

Here's the trick: *every* aspect of him is Super, including his bladder and velocity control, so if Supes was peeing next to you at the urinal (spoiler: he probably hasn't *had* to #1 or #2 since he was a little kid), you'd never know he was anything else besides a 6'3" massive alien dude in tights at the next urinal over from you, who makes great small talk as you wash your hands, takes a selfie with you after in the hallway, and for thirty seconds before he flies off, makes you feel like the most important person in the galaxy.


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

[User]
Is it possible to get eye damage, or even a sunburn, from the moon's light?

If moon is just reflecting the Sun's light, then are the UV rays also reflected? And are the UV rays strong enough do damage or affect the human body at all?

[Assistant]
No, the intensity of the reflected moonlight from a full moon is about 300,000 times weaker than that of direct sunlight (the exact number depends on various conditions such as location on Earth, where the moon is in its orbit, etc...).

So in order to get the same amount of UV radiation as you'd get from 15 minutes of direct sunlight, you'd need to be exposed to the moonlight for 8.5 years. In this time, the skin's limited self-healing capabilities are easily able to overcome the damage.

Your eyes are safe as well, because even looking directly into the moon is orders of magnitude less bright than looking at the sky on a cloudy day. It's even well below the intensity of dimly lit interiors.


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

[User]
ELI5: How would dropping thermonuclear weapons on Mars warm the planet like Musk claimed on the Late Show?

I don't have a terribly strong understanding of nuclear physics, but I was under the impression that (at least on Earth) dropping thermonuclear bombs results in basically a soot rising into the atmosphere, blocking the sun and thus cooling the planet (Nuclear Winter). Can someone help me out here?

[Assistant]
>dropping thermonuclear bombs results in basically a soot rising into the atmosphere,

Mars has a serious shortage of plants and other stuff to burn.

The idea is that you use the bomb to melt the Martian icecaps. These contain carbon dioxide, thus triggering Martian warming.


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

[User]
Is light made of particles, or waves?

This comment by RobotRollCall got me thinking:

>"In a sensible, physically permitted inertial reference frame, the time component of four-velocity of a ray of light is exactly zero. Photons, in other words, do not age. (Fun fact: This is why the range of the electromagnetic interaction is infinite. Over great distances, electrostatic forces become quite weak, due to the inverse square law, but they never go to zero, because photons are eternal.)

>"In the notional reference frame of a photon, all distances parallel to the direction of propagation are contracted to exactly zero. So to a photon, emission and absorption occur at the same instant of time, and the total distance traveled is zero."

This sparks so many questions. Light is emitted radially from the sun, so does that mean that, if the range of electromagnetic radiation is infinite, an infinite number of photons are sent into space in all directions, just waiting to interact with something a billion light-years away? Wouldn't a wave-like definition make much more much more sense in that situation?

Honestly, I've never been convinced that light is made up of particles...

tl;dr What the F are photons?

[Assistant]
Photons are particles. Period. End of paragraph.

To be more specific, photons are massless, uncharged vector bosons. They have no mass, no electric charge and a spin quantum number of 1, and they obey Bose-Einstein statistics. The behavior of photons is *extremely* well understood, and is essentially the same as the behavior of any other type of subatomic particle.

But *light,* however, is something else. Light  and by extension, things like radio waves and X rays and so on  is what you get when you put a bunch of photons together.

A photon left on its own behaves in a fairly simple manner. It moves in a straight line at the speed of light forever, until it's absorbed by a charged particle. Mostly.

But when you get a lot of photons together, new and curious behaviors emerge. When you consider a bunch of photons as a single thing  a ray of light, in other words  you see behavior that looks more like a wave phenomenon than a bunch of particles. Light can be very accurately modeled, in fact, as a wave phenomenon. The mathematical models that describe light as a wave phenomenon work extremely well  except when you try to apply them to things like the photoelectric effect. For that, you have no choice but to zoom in and examine light for what it really is: a bunch of particles. That's how Einstein got his Nobel prize, incidentally.

So to sum up, light is made of particles. Period. But those particles are not like little bowling balls. They cannot be modeled with classical mechanics. They have properties that can only be described with quantum mechanics, and it's those properties that cause light, when viewed at a larger scale, to look like a wave phenomenon.


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

[User]
[LOK] Why is Korra's avatar state so much weaker than Aangs?

Seriously. Aang had only had a year to practice his elements before he fought Ozai, while Korra had about 15 years of k owing she was the avatar, plus mastering all the elements when the series begins. Her avatar state is basically her slightly more powerful.

[Assistant]
You mean post-Season 2? She lost her connection to her past lives which resulted in a *huge* power drop.

Pre-Season 3? Korra was never as spititually powerful as Aang and thus he had more power, though not nessecarily more control, over the Avatar state.


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

[User]
[Like a Bat Outta Hell] Why are there bats in hell? Are they born there? Does the bat afterlife overlap with the human? Are they an invasive species? And why do they want to leave so badly?

Also is the saying likening something to regular bat behavior, if that bat were from hell, or is it likening something to a hell bat escaping hell?

[Assistant]
For centuries, Hell has been depicted not as a *Doom*-like alternate dimension, but as a physical place deep beneath the surface of the Earth. Heaven, by contrast, is in the clouds. Even some modern cartoons show these depictions.

Bats live in Caves beneath the surface of the Earth, near where Hell is. If a Bat accidentally ventured too deep, and suddenly found itself surrounded by flame and lakes of fire, you can imagine it would escape with the greatest haste.


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

[User]
Eli5 Why does salt make ice colder but we use it to melt ice on sidewalks?

Edit: Wow I love this sub, thanks for all the answers!

[Assistant] Saltwater freezes at a lower temperature than fresh water. Ocean water freezes at around -2 C, and higher concentrations of salt decrease that temperature. This allows water to go colder before it turns into ice. So, if you put a bunch of salt in water, that water can get colder than normal because it does not freeze. Similarly, you put salt on the ground so that when it snows, the snow melts not because the salt warms it, but because it makes it so that it needs to be colder to remain in snow form.


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

[User] [Star Trek] With all of the treatments undoubtedly available for anxiety and depressive disorders, why does Reginald Barclay continue to suffer?

[Assistant] Reg Barclay suffered because his prior command officers found it easier to bury the issue and shuffle him off somewhere else than to deal with him and his problems, causing him to "fail upwards" instead of really developing. Picard, not having that buck-passing garbage, invested time and energy in the man; as others have noted, by the time of Voyager he's massively improved personally and professionally.


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

[User] ELI5: Why when I click the "X" on the top-right of an ad box does it always remove the ad? Why do advertisers never link the "X" to their ad page?

[Assistant]
Ads are served by middle men, for example Google, and they never would allow that becauese it would mean sites just wouldn't use them to place adds.

Also you could likley sue or in some way take action agasint the company for that kind of thing. It would be really blatent misdirection.


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

[User]
Is WISE 1828+2650 habitable at all?

I just found out recently, via a temperature of the universe info graphic, that WISE 1828+2650 has a surface temp of 80F/27C.

Is there a maintainable orbit where the radiant temp would be appropriate for human living conditions? What about the surface directly? Other than lack of oxygen, is there anything inherently toxic about the environment that would need to be overcome?

[Assistant]
So a few points about this:

- That infographic just gave a single temperature of 27 C / 80 F, which is a little disingenuous since it says nothing about the uncertainty. Estimates are that the cloud-top temperature is anywhere between -23 to 127 C, or -10 to 260 F.

- Even if the cloud-top temperature really is mild by human standards...that's at cloud-top. There is no surface to stand on, just an atmosphere that gets thicker and thicker, until the pressure and temperature is so great that hydrogen becomes a liquid metal. If this object formed like a brown dwarf, there's likely not even a solid core under all that crushing pressure of metallic hydrogen.

- The range on the mass estimate is pretty large - plausibly anywhere from 3 to 6 Jupiter-masses. That means the gravity at cloud-top is anywhere from about 8x - 15x Earth's gravity. Even if you could float in a balloon at cloud-top, the gravity would crush you pretty quickly - no one can survive that for any extended period, and you'd black-out pretty quickly from your heart being unable to properly pump your blood.

So...don't plan on building your vacation home at WISE 1828+2650 just yet.


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

[User]
CMV: I believe that all illegal immigrants need to be deported

It makes no sense to me as to why an illegal immigrant can't take the legal approach to becoming a legal immigrant. We have methods for citizenship but immigrants choose not to take it. They come here with no prior education for our language and somehow expect entitlement to welfare they don't pay for. We have an unemployment issue in america, how can we expect to provide them jobs when we can hardly provide jobs for american born citizens? Plus, illegal immigrants get paid less then legal immigrants, what's the point of coming here when you won't get equal opportunity? If their country's so bad, why don't they just stay there and try to fix it?

Immigrants in America are more of a drain then a contribution.

[Assistant]
> It makes no sense to me as to why an illegal immigrant can't take the legal approach to becoming a legal immigrant.

Are you familiar with the legal approach to becoming a citizen? It's lengthy (several years) and often requires a lawyer. If it were easier and cheaper, perhaps more people would be legal. Most of the illegal immigrants come here to work for low wages to feed their families; how can they afford this process?

> They come here with no prior education for our language and somehow expect entitlement to welfare they don't pay for.

Why do you think they expect entitlement to welfare? Most of them work under the radar, and applying for welfare would put them squarely *on* the radar.

> We have an unemployment issue in america, how can we expect to provide them jobs when we can hardly provide jobs for american born citizens?

No we don't. Our unemployment rate is actually pretty low. The type of jobs illegal immigrants do are not the jobs that American's want. The threat to high paying jobs is by *legal immigrants* that are granted visas.

> Plus, illegal immigrants get paid less then legal immigrants, what's the point of coming here when you won't get equal opportunity?

Because the lesser opportunity in the US is better than the best in their own country. If $3/hr will feed your family back in Mexico, it's a no-brainer.

> If their country's so bad, why don't they just stay there and try to fix it?

Yes. It's really easy and fast to fix a corrupt and impoverished country.


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

[User] [Star Trek] Picard treats Q [basically a trickster God] as an unwelcome and annoying guest. Is this just Picard being honest about his feelings, or is it a deliberate psychological strategy to 'manage' Q?

[Assistant] I think it's genuine annoyance. Q is omnipotent and omniscient; why even bother hiding your annoyance? You're not going to able to kiss his ass enough to make a difference, or offer him much that would be worth anything to him - might as well play it straight and honest.


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

[User] ELI5: How can a government go in and freeze someones account, especially when the person is a citizen of another country?

[Assistant]
The government can freeze any account within a bank within its borders. The status of the citizenship of the owner of the account has no bearing on this, the bank follows the laws of the place it is located.

Now, in the US they have to have a reason to freeze your account but that reason can be as simply as they are investigating you for a crime.


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

[User]
[Groundhog Day] What caused Phil's time loop?

And for that matter, why ended it?

[Assistant]
Punxsutawney Phil controls the time loop. The Seer of Seers and Prognosticator of Prognosticators was deeply offended when Connors called him a "large squirrel predicting the weather." Phil isn't a squirrel and he isn't predicting shit. He's a motherfucking *groundhog* and he *decides* when the seasons change.

To punish Connors for his hubris, Punxsutawney Phil summoned a freak storm to trap him in his domain, then looped time until Connors learned his lesson.

Remember, it's not until Phil Connors delivers his sincere monologue on the beauty of Groundhog Day that his curse is lifted.


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

[User]
Is there any association between left-to-right languages and right hand dominance, and vice versa?

Maybe not anymore, but was there ever any evidence that languages that were created and written right-to-left were done so by primary left handed people?

[Assistant]
Nope. Hand-dominance is not correlated with writing systems. Even though there is some variation in the world (although it is difficult to judge because more conservative cultures that value conformity still often "encourage" lefties to use their right hand) the vast majority of humans everywhere are right handed. So if they were correlated, we'd expect NO variation in the direction of text.

As an aside, hand-dominance *does* have an impact on language-lateralization in the brain however.  That is, the language centre is usually in the left hemisphere of the brain, but a small number of people have it lateralized on the right. The proportion of people that are right-lateralized is slight higher for the left-handed population than the right.  Just to be clear because it's easy to warp that statement---the vast majority of left-handed people still have their language centre on the left side. It's just that the small percentage of right-lateralized left-handers is slightly higher than the small percentage of right-lateralized right-handers.


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

[User]
ELI5: Self-immolation as a form of protest

Another day, another story about Tibetian monks setting themselves on fire to protest something.  I have no idea how that's supposed to protest anything - is it just a cultural thing?

[Assistant]
Let's say you want to show the world that you're really angry at your treatment.  REALLY angry.  Like, psychopathically angry.  What would be a good way to do that?

Well, you could go on a big terrorist rampage to show your dismay.  But for a certain type of person, killing others who are either innocent, or just doing their job for an authoritarian regime, isn't very palatable.

What's another way of making a VERY strong statement about how angry you are?  How about purposely subjecting yourself to intense agony, in a very spectactular and visible way?  That's what self-immolation is.  It's probably the strongest possible way of telling people how angry you are.


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

[User] [Zombies]. They've got bodily fluids. Why don't they freeze solid in the winter in places like Minnesota and Canada, creating an effectively worry free season?

[Assistant] In World War Z (the amazing book, not the horrible movie) this is actually a pretty big factor. Above the permafrost line zombies basically aren't a threat, and anywhere it drops below freezing in winter becomes clean up time.


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

[User]
ELI5: How do some symptoms of illness being an impending sense of doom work, chemically?

I don't mean like mental Illness but like if
you have something physically wrong
with you just happen and you're gonna
die. I read that the wrong type of blood
transfusion can cause that feeling as a symptom of something being seriously wrong with your body. What makes the doom feeling feel so different than other
feelings, chemically?

I know similar questions have been asked before, Im not asking why its a symptom, Im trying to ask how does the doom feeling happen, what kind of things does the body and brain do to produce that feeling, versus a normal adrenaline rush when you are in danger.

[Assistant]
The body is full of many sensors, that try to measure what's happening.  This information is used to operate many of the body's safety systems.

For example, if you eat the wrong plant and it starts to impact your sense of balance, the body detects this and you barf.  Alas, you evolved before cars were invented, so sometimes the balance confusion is a function of being inside a moving car, which we call motion sickness.  Throwing up doesn't change the car, so this doesn't work, but the body sensors don't know that.

When the brain hasn't experienced something before, and doesn't have an instinct to fall back on, it makes you very upset.  Many things act this way, like your blood example or high CO2 levels in the room's air.  You don't know what to do, but you get upset in hopes you'll try something that works.  It's your body trying to engage your brain to solve the problem, whatever it is.


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

[User]
ELI5: Why is it predators are reluctant to attack us?

I've never really understood why this is the case (as it appears to be the case).

If we start with something like a bear, it is very reluctant to interact(engage/attack/etc.) with a Human, at all. Now I don't understand why, it's massive compared to us, taller, wider, stronger etc. It must know that it could easily take us out if it wanted but doesn't (a vast majority of the time). I don't understand why.

Something like a Great White shark too, they don't outright attack Humans, they 'investigate'. They circle then 'nip', why not just attack us the way they do Sea Lion's etc?

The same for a vast array of other animals, too.

Then there are animals such as the Gray whale that even if they have a negative experience with humanity they will still approach us...

[Assistant]
We're large enough that even a bear might get injured before it kills us, especially since it doesn't know what nasty tricks we may have up our sleeve.

Since any injury can get infected and be fatal, the predator will not take that risk unless it is very hungry and has no other, more familiar prey available.

And that's not even taking into account the fact that we usually come in groups, which multiplies the threat we represent.


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

[User] ELI5 why do submarines and boats have propellers in the back but airplanes have propellers in the front?

[Assistant]
Some airplanes have the propellers in the back.  Some airplanes have them in the front *and* the back.  Some have them on the sides (when they're mounted on the wings).

It boils down to the fact that air inside an airplane is okay, but water inside the boat is a bad thing.  Propellers on an airplane are (usually) directly attached to the engine, and air in the engine is good.  You need it for fuel mixture as well as cooling.  On a boat, however, you don't want water getting into your engine or the hull at all, if you can help it, so the props are at the rear so the force of the prop doesn't push water into the seals around the shaft.

There's more to it than that, but that's the eli5 version.


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

[User]
Do animals get periods?

I've been learning about the menstrual cycle in biology but we only talked about the human menstrual cycle. I was wondering if its the same sort of thing with animals since I've never seen my cat on her period before.

[Assistant]
Yes, most female mammals experience a "period" if their cycles complete without a successful mating. Dogs and cats are usually spayed (which prevent this). Female dogs (formally known as a bitch) will have the blood discharged from the privates just as in humans. However this is not the case with all animals, since most will retain the blood.

Hope that answers your question.