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

[User]
If atoms only emit light with specific (discrete) values for wavelengths, why do bodies emit a continuous spectrum of radiation?

The notions of the emission spectrum kind of collided with the black-body radiation information I had...

If you heat a body, like tungsten wire in a light bulb, it acts like a black-body and you get the classic continuous spectrum... But that body is made up of atoms, and atoms only release discrete radiation when an electron goes back to a lower energy level (E=hf=hc/l)... So how can you get that continuous spectrum of wavelengths from atoms that release light with discrete wavelength values?

[Assistant]
A black body is an idealized model, like a perfect vacuum or a frictionless surface. It is an approximation which holds up well in many cases, but actual things deviate from the black-body model.

The hypothetical black body is a substance that absorbs all light perfectly, and emits light in a well-defined spectrum depending on its temperature, ie. blackbody radiation. A single hydrogen atom is therefore a poor candidate for applying the black-body model, because it only absorbs some wavelengths of light and generally does not behave much like a black body on its own.

But if you took a huge ball of hydrogen, like the sun for example, and heated the whole thing up to 6000 kelvin, it follows the black-body model quite well. At this temperature, we happen to get the spectrum we are familiar with from the sun.

It is still the case that photons are emitted from electrons changing energy states. But energies of electrons are not limited only to their quantum numbers. There are also vibrational energy states, so if you have a gas of really hot hydrogen atoms bouncing around, there will be a lot of kinetic energy that will result in electrons being bounced around, emitting light accordingly. This is somewhat independent of what particular material it is, and then you have blackbody radiation :)


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

[User]
[Deus Ex: Mankind Divided] Why does the UN care so much about humanitarian appearances of the tulek Complex?

It seems like the tulek complex is an open secret as a humanitarian nightmare, yet Talos Rucker manages to leverage the UN into keeping a section for himself with threats of going public about the conditions. Why does the UN care though? Isn't tulek just days away from a "resident" leaking the poor conditions? Even if the Czech is anti-aug and doesn't care, I doubt they can keep a tight restriction of information.

Why isn't there a more public demand for Rucker to be arrested? Even if Czech state police aren't up to the task, it sounds like both the Czech government and people would support foreign intervention to bring Rucker in for questioning.

[Assistant] All they need is a suspension of disbelief. Like how China has concentration camps literally right now, so long as somebody can believe otherwise then some people will, and that is enough to continue the debate, and so long as the debate is happening nobody will actually do anything.


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

[User]
What causes the first heartbeat?

What causes the heart to beat it's first pulse? Is there an electric pulse from the mother to jumpstart the heart when it is ready?

[Assistant]
Heart muscle cells are unique in that they are the only muscle cells that can self-excite. They will beat on their own in an intrinsic rhythm that does not require outside stimulus. Basically, as soon as the first heart cells are formed in the embryo, they will start beating immediately even if the heart isn't formed yet.
You may have gotten the impression that hearts need to be jump started by depictions in TV or other media, where a patient 'flatlines' and then an electric shock is used to 'jumpstart' their heart.
In reality, that doesn't happen. The electric shock cannot start a heart - it stops it. It is used to 'stun' an heart that is fibrillating, that is a heart whose cells want to beat, but they are all out of sync so that there is no contraction. In that case an electric shock can stop them all briefly, giving an opportunity for the main signal source of the heart - the sinus node - to take over again and get an organized rhythm. In a 'flatline', called asystole, there is nothing to shock. There is no electrical activity in the heart and zapping it does nothing.


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

[User]
[Harry Potter] Polyjuice Potion unlimited supply

I'll use Barty Crouch as an example:  Did he need to keep Moody alive? or was he able to use polyjuice to turn into moody, and whilst being fake moody pluck his own hair to use for the next potion?

[Assistant] He had to keep Moody alive to get raw materials for the potion - his own hair, even though it was morphed to look like Moody's, wasn't actually Moody's - such magic works on internal essence, not external appearance.


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

[User]
What caused the Cambrian Explosion?

The Cambrian explosion was a period in geological history starting from 542 million years ago in which most classifications of life appeared. Is there any consensus in the scientific community as to what caused it?

[Assistant]
It's what's called an adaptive radiation. These can be caused by mass extinctions that leave many niches vacant, or by drastic environmental changes that cause new niches to form. It can also happen, as in the case of the first land-dwelling creatures, when species themselves discover a new environment full of previously unclaimed niches. We mostly agree that it was caused by the latter, but we cannot be certain what specific factor caused it. Many speculate that it was caused by changes in oxygen levels that supported previously impossible levels of respiration or the formation of the ozone layer that provided protection from previously destructive levels of solar radiation.

It is important to note that at the time it happened, the 'most classifications of life' that you speak of were still very closely related. These classifications (domain, kingdom, phylum, class, order, family, genus, species - which are being done away with for exactly this reason) only represent a useful way for organizing species. They do not reflect the true divergences between species. When the radiation first started, the species would be separated by no more than one 'level' or classification - species. They have only become phyla over the many years since they first diverged.


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

[User]
ELI5: What is Torque, and why do high torque engines not have super high rotation speed?

I asked my physics teacher this and she didn't really give me a proper answer. I want to know why engines with high torque do not spin super fast. Because, if you apply a bigger force to something, shouldn't it also move faster?

Sorry if my understanding of engines is wrong, but I guess it also applies to a simple pivot with a beam attached to it. If you apply a bigger moment of force to the beam (which according to my book, moments of force can be called torque) shouldn't it rotate around the pivot faster?

How can you apply more force but not increase the rotation speed?

[Assistant] Torque is not related to rotation speed. Torque is defined as the force you are using to turn something multiplied by the distance the force is from the center of rotation. For example, if you pull on a 2 foot long lever with 50 pounds of force, you will create the same amount of torque no matter how long it takes you to turn it.


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

[User]
ELI5: How can the two oceans be different heights?

The Panama Canal is a series of locks that help raise or lower ships so they can move from one ocean to the other ocean. But the oceans are connected bodies of water! How can they be at different heights? If I had two connected bowls of water, I wouldn't be able to raise the water level of just one bowl, so how do the oceans do that?

[Assistant]
Two reasons.

1) There was a lot of land between the two ocean where the panama canal is right now. So to make the construction easier, they make a lot of dam to create an artificial lake. That lake is about 80 meters higher than the average ocean level, so the lock first make the ships go up to reach the lake, then go down to get to the other Ocean.

2) Ocean are not the same level everywhere even if they are connected. The gravity of our own planet isn't uniform so how much they pull on the water isn't the same everywhere which lead to a different in ocean level from one place to another. This is why you have an average ocean level and not just an ocean level.


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

[User]
What is the relationship of quantum field theory to quantum mechanics?

The way I see QM is as a sort of general "protocol" for making predictions at the quantum scale. First, choose a Hilbert space representing all the possible states of your system; then choose a self-adjoint operator A representing the variable you want to measure; find the eigenvalues and eigenvectors of A; use the Born rule to calculate the probability distribution; exponentiate iA to find the time evolution.

My understanding of QFT is that it uses this protocol to model fields like the EM field, so that the basic procedure is the same; the difference is that you use classical fields as a guide for choosing Hilbert spaces and operators, and this leads to things like Feynman diagrams and whatnot. How correct is this?

[Assistant]
Correct. QM is a framework in which to describe physical systems. QFT is basically a certain subset of QM where you

1. Can create and destroy particles, and

2. Treat things relativistically (as in *special* relativity).

To make a classical theory quantum, you just apply the postulates of QM. You describe your system as a state vector in a Hilbert space, you promote dynamical quantities to operators, and "have at it".

To turn a classical theory into a QFT following canonical quantization, you promote your fields to operators which create and destroy particles, and impose the canonical commutation relations.

To get from there to Feynman diagrams, you just consider time evolution and expand the time evolution operator (or the S-matrix for scattering problems) in a perturbation series. There are some cool tricks due to Feynman, which allows you to do everything in a relativistically invariant way, and Wick, which allows you to easily work out the kinds of diagrams you need to draw.


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

[User]
[Fallout 4] How is there Irish and Russian accents in the Commonwealth?

So the Commonwealth doesn't really have a huge shipping industry anymore. And although running boats exist (far harbor) I'm doubtful that they can tackle GOING TO IRELAND.

Travel is much harder, so how is there a couple of Russians running a bar, and some irish running around kicking ass and doing hard drugs?

[Assistant]
There is actually transatlantic travel. Colin Moriarty from Fallout 3 is from Ireland and arrived in the US as a child.

Oceanic travel is actually pretty straightforward, if rare, in the post-war world. All you need is a watertight hull, working engine, a nuclear reactor to power the engine, and enough supplies to last the trip.


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

[User] [Marvel] With so many reality warping beings out there (potentially some of them not even aware or insane), how is the reality not changed every few days? Alternatively it is but nobody can notice?

[Assistant]
I think the latter is the explanation.

Think about it, if someone else changes the timeline, from your point of view, you wont notice any difference, because youre living in the slathered timeline.


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

[User] ELI5: How do transmissions such as Wi-Fi signals and cellular phone signals transmit through solid objects like glass and wood? I understand that it degrades the signal, but how does it still make it through in the first place?

[Assistant] Have you ever shined a bright light through your finger tips? Notice how you can see the light coming though? It may not be as bright because your finger is absorbing a lot of it but still light makes it through to the other side.  well wifi or radio signals are essentially light or electro magnetic radiation. They are simply outside of the human visible spectrum so we don't see them. Same thing happens though with certain wavelengths of light can penetrate through solid objects. They'll be weaker on the other side but they can go through. On an atomic level there are gaps even in solid. If light is of the right size aka wavelength it can slip through these gaps. Differing materials have different gaps and density this absorbing different amounts of light. Glass will let through more light than metal for example.


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

[User]
[Frozen] Why wasn't the Duke of Weselton tried for attempted murder of the queen?

Shouldn't it have sparked into a war between Arendelle and Weselton since one noble from a neighboring country tried to kill a royalty in another kingdom?

[Assistant] Mostly, he just didn't get caught. No one thought to ask his henchmen if they had explicit orders to bring Queen Elsa back dead, and in the aftermath of Prince Hans' botched coup the matter of the ice castle fight slipped through the cracks. As for the coup itself, Weselton was pretty much just a bystander/pawn in Hans' moves.


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

[User] ELI5: What is actually happening with a "knot" in your back?

[Assistant]
Former massage therapist here.

A knot is a little bundle of tightly contracting muscle tissue. Sometimes during daily activity, small areas of muscle get slightly strained and hurt a little bit. Muscle fiber contracts when it hurts (because if you're over-stretching, for example, the overstretched muscle will want to contract to prevent further injury). When small areas contract a lot, this will cause more pain. Knots, cramps, & spasms happen when muscle fibers get stuck in a pain-spasm-pain loop.

When the tight bundles remain for awhile, blood flow to the area becomes limited. Blood brings oxygen and nutrients to cells while washing away cellular waste. With limited blood flow, cells are more likely to die. Cellular waste can be irritating to other cells if it builds up, and reduced oxygenation & hydration can hamper healing of the injured fibers.

Muscle fibers are surrounded by fascia, which is made of collagen and other proteins. If muscle spasms keep an area tight enough to restrict blood flow, fascia becomes less hydrated and more sticky. (You can see how sticky for yourself if you play with hide glue or warm gelatin dissolved in the bare minimum amount of water.) When fascia gets sticky, adhesions (or "stuck" areas) form.


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

[User] [Jurassic Park] So was Dennis Nedry being paid below industry standard or not?

[Assistant] He put in the lowest bid for the work proposed by Hammond, however once the job was under way, there were a lot of changes to the scope of work that Hammond refused to pay for. Since Nedry was under contract, he couldn't just walk away, and was stuck doing an excessive amount of work that was not initially planned for.


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

[User]
ELI5:-273 Centigrade is the lowest possible temperature.What is the highest possible/feasible temperature in the Universe?

There was a paper today at the Physics section of the Open University I attend and the author was discussing the bounds for pyrometry.Here he was postulating a system of 'virtual' particles travelling at c,and this caused a huge controversy.Of course ,no particle could conventionally attain c,but the question argued about was,what is the upper bound on temperature?

[Assistant] The Planck Temperature is the upper bound at which our current understanding of physics breaks down. However, even in the first moments after the Big Bang, the universe was still a few orders of magnitude away from this temperature.


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

[User]
[Raimi Spider-Man 3] Why did Eddie think he could get away with faking the photo?

He obviously didnt know that Peter is Spider-Man, but did he really think Pete wouldnt examine his faked photo? Peters been taking photos of Spider-Man from the very beginning, plus theyre both competing for the staff job.

Now only that, but there were no witnesses or police reports on the crime (because it didnt happen).

How did Eddie think hed get away with it?

[Assistant]
Eddie was likely banking on Jameson being so happy to have a picture of Spidey committing a crime that no one else would raise any objections, or that any objections raised would be quashed by Jameson.

Of course, he miscalculated, because Jameson's a more principled man than Eddie had expected, and even he wouldn't ~~slander~~ libel Spider-Man like that.


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

[User] ELI5: What are the benefits and drawbacks of having an overvalued or undervalued currency?

[Assistant]
Overvalued- It's easier to buy imported stuff cos they're cheaper than your domestic stuff. Even though your currency is worth more, theirs is worth the same, so their prices will decrease from your perspective. On the downside, your domestic market suffers, and so do your country's exports, because they are costly relative to the world market.

Undervalued- Pretty much the opposite. Imports become costlier, and your domestic market thrives. Your exports also thrive because they become cheaper to other countries. On the downside, other countries don't take kindly to you dumping your cheap exports (like China does) and you could face embargos and stuff.

Obviously this isn't a comprehensive overview, but it goes through the essentials.


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

[User]
[DC] Was Clark Kent able to get his shots as a kid?

Schools usually make a kid get their shots before coming to class, at least that's my impression. But was little Clark able to get a shot, what with the bulletproof skin and all? Did Martha and Jonathan forge medical records?

[Assistant]
In some universes, particularly those where Clark displayed powers from infancy, the Kents were able to use legal loopholes, forged documents, and their friendly relationship with Smallville's local doctor to get around Clark's shots. Given his unusual adoption, this was part of the process that allowed him to stay with his human family.

In other universes, Clark didn't show any superpowers until adolescence. As a small child, he was able to be pierced by needles, and so would have gotten all of the usual vaccinations and medication of any kid in his age group. His skin didn't become fully bulletproof until he was either out of high school, or just about to leave. So even his teen years might have been able to get shots, but the doctor would have had to apply more pressure than they expected.


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

[User]
ELI5: Why was Windows ME so horrible?

I've heard tons of horrible stories about Windows ME, but WHY was it so horrible? I've never experienced it first-hand.

[Assistant]
There were a few factors.

The first, and probably the most important, is that XP came just over a year later and murdered it. Unlike Windows Vista, it never really ended up having a chance to have many of its issues worked out before consumers migrated.

In terms of the problems that it faced, it was slow. Very, very slow. It's infamous for having had some memory leaks on launch that made it unstable. Unlike Vista or XP, which also had some performance complaints, it failed to deliver other features users were interested in. Security was still bad, there was still a gap between Windows NT and DOS-based systems, and, most damningly of all, it broke compatibility with many DOS-based applications.

The biggest thing to remember, though, is that it was preceded by the much better Windows 98 SE and followed by the also much better Windows XP. Its inability to show significant improvements to justify its cost and issues was the factor that killed its public perception moreso than any of the things that were actually wrong with it.

edit: In terms of the constant horror stories that you hear on the Internet, they're more meme than anything. Windows ME was only out for about a year before XP completely erased it, most users never bothered upgrading, and it ended up being used mainly by people who upgraded personal computers between September 2000 and October 2001. Most of the people who talk about how shit ME is have never used it.


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

[User] ELI5: Why are cashews so much more expensive then peanuts?

[Assistant] Peanuts grow in the ground, can be mass harvested by machines, and are safe to eat in their raw state.  Cashews have to be hand picked from trees, are highly poisonous in their raw state, in fact one of the most toxic substances on the planet.  They have to go through a process of drying out and detoxing before they can be eaten.


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

[User]
Is the belief that mindless consumerism boosts the economy an example of the broken windows fallacy?

If I spent $50 on a pet rock, did that really boost the economy? Or if that $50 had gone towards SpaceX funding, might it perhaps have been better spent.

[Assistant]
If you spend 50$ on a pet rock it means that you really wanted that pet rock, more than what 50$ invested in spacex and somebody was willing to sell you one for 50$. Economy doesn't hold a stance for the utility of purchases agents do in the grant scheme of things, because said utility is subjective to the agent making the transaction.

"One man's trash is another man's treasure".


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

[User]
[Pokemon] What are the FAA (or equivalent) regulations regarding the use of HM Fly?

From my understanding, you must first obtain from the appropriate gym badge for your respective region before your Pokemon are even allowed to use HM Fly for travel, and the leader of said gym is almost always a user of flying types, but am I missing something?

I was never given a test on mid-air collision avoidance, and  I certainly wasn't informed about what to do around airports or helicopter landing pads.  And furthermore, some of the Pokemon that can learn Fly can easily grow to be 20 feet tall (that's bigger than some personal aircraft) and at least two of them, assuming you can even find them, are said to be able to outrun a jet.  Surely there's some level of federal oversight to help keep disasters at bay, right?  Especially when you consider the sheer number of trainers that have acquired the right to use HM Fly outside of battle that are under the age of 10.

My Pokemon Trainer's Field Guide is being absolutely useless on this matter, and I'm not sure if it's because my Charmander edited my copy again or if it was just lacking to again.

[Assistant] It's mostly the honor system, to be honest, although you'll probably get arrested if you get caught flying without a badge. Pokemon are incredibly durable and maneuverable. You don't see flying-types raining dead from the skies after constant mid-air collisions, even carrying humans they're pretty inherently safe, at least by the lax standards set by the system.


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

[User]
Is the mass of the earth constantly changing?

I mean everyday we're increasing in numbers human, animals etc. The mass probably won't change by a significant amount.

But is it theoretically possible that the mass of the earth (without any mass from the cosmos, like asteroids) changes that much that the "elliptical path" the earth has around the sun changes by a significant amount?

[Assistant]
You have to remember that the mass of animals comes from the air they breath and the food and water they consume. It doesn't just magically appear.

The only real change in mass comes from asteroid activity, and loss of atmosphere to space. But even that is basically insignificant when compared to the mass of the body as a whole.


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

[User]
Is it actually possible for a healthy individual to increase their lung capacity/function?

When I was a kid I used to think free divers and other swimmers could increase their lung size via breath training, but it turns out training actually just increases CO2 resistance. Still cool, but I'm still slightly disappointed these swimmers aren't actually growing their lungs like muscles.

So, my question is, is it impossible for a healthy adult to increase their lung capacity/function?

[Assistant]
It depends on what you mean by capacity/function.

If you mean the volume of air that the lung can hold, no not really.  They have compared sedentary people to regular exercisers and have found very little difference between the two in both largest breath intake (TWC) and exhalation after largest breath (FVC).

But you could also mean how much oxygen can be extracted.  By that measure then yes!  But it is mostly down things like the heart and blood volume, both of which can be increased by exercise and training.  So the real limiting factor in a healthy individual isn't the lungs themselves as it's the body's ability to transport the oxygen away.


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

[User]
CMV: Voluntary euthanasia should be available for all parties regardless of health

I just don't understand whats the drawback for allowing people to kill themselves other than the famous answer the pain is temporary life gets better. For some it doesn't get better so why shouldn't they be allowed to kill themselves with voluntary euthanaisa. My view point is one you you have less humans using resources since most say we are a determent to the environment. Also your allowing a person to relieve their pain it seems like a win win on both sides.

In addition, your solving the overpopulation problem. My viewpoint is if your suffering through life regardless of mental or physical why should you be force to do this miserable journey. Everybody always say life is beautiful but we all have different perspectives why should I be forced to choose a path I don't want to take. It seems cruel to me to force people to be alive. I'm under the assumption its my body my choice regardless of sex or gender

Edit: I was just saying that if you can consent to do all of these task in society sex, get a job, fly internationally, live by yourself, why cant you end the pain and euthanize yourself.

[Assistant]
There isn't an overpopulation problem and there never will be. Populations are on the decline in the developed world and are vastly decreasing even in places like Africa.

Would you allow children and the mentally ill to kill themselves?


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

[User] ELI5: Why do fruits like pinneapples and kiwi leave a rough feeling on the tongue?

[Assistant]
Human skin contains oils which aid in blocking out the absorption of chemicals which would harm or irritate the skin. Those oils contain proteins. Pineapple contains a chemical compound called bromelain which has the ability to break down these proteins. This enzyme is called a protease. Kiwis also contain a protease called actinidin.

Because these enzymes readily breaks down proteins, bromelain is frequently used as a natural meat tenderizer. In addition, they may also induce a prickly sensation in the mouth when consumed.

In pineapples the enzyme is present in all parts of the plant, it's most concentrated in the stem, the hard piece in the middle of the fruit, which is much more fibrous and chewy but still edible.


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

[User]
[MCU] Even if Loki had killed the Avengers with his army, would he have even been able to hold New York until Thanos came to collect the stones?

Assuming the TVA didnt get involved, the Council didnt decide to nuke him, and the Ancient One ignores New York.

[Assistant] If the Avengers fell, then we would have the nuke option. Following that we have Carol Danvers if she doesn't arrive or Ancient one and their army of wizards. Failing that Us Military, failing that we have the potential for the Eternals to step in if the celestials think its enough of a threat. We also have Wakanda if they think an alien invasion in the US is earth risking. We also have villain groups like Hyrda and The 10 rings whose best interest lie in the world still existing and they have powered individuals to help fight Thanos army.  Furthermore Inhumans, aliens etc living on earth would weigh in.


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

[User]
[Game of Thrones] Are the old warriors from before really better than modern day swordsmen? Or is it just nostalgia?

Everyone thinks Barristan in his prime or Arthur Dayne were the most dangerous swordsmen to have lived. Arthur Dayne famously almost defeated Ned Stark and multiple companions.

Could this just be nostalgia talking? I mean everyone thinks Muhammad Ali is. the greatest boxer to have lived. And he DID dominate his opponents. Everyone has those memories of Ali dodging punches effortlessly and out smarting opponents. He was a superstar compared to his opponents. But really sit down, watch his fights, and see the caliber of his opponents. Could you imagine those opponents lasting ten minutes with a modern day elite fighter?

So going by that.... maybe Ned Stark was so blown away by Arthur Dayne just because Ned Stark and his companions were such mediocre warriors that Arthur Dayne looked great in comparison. After all, The Hound would have also killed a whole group of men too just like Arthur Dayne almost did. He just got mortally wounded because he was drunk and starving.

If the Warriors of old really are better, why is this? What happened to the training that swordsmen receive in the modern era of the books/show?

[Assistant]
One thing to remember is that the current generation of warriors have been in a constant state of war for a generation.  That sounds like it would be fantastic practice and a great proving ground, but in reality war doesn't care how good you are, it's still a meat grinder.

War kills and maims through random bad luck just as much as skill, often more so.  That means that while heroes of old had decades to hone their skill, practice and perfect their craft, and generally prove themselves from relative safety, our current crop are constantly in a brutal fight for their lives.  This doesn't create great swordsmen, it creates brutal survivers.


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

[User]
What is the Color of the Sun: White or Yellow?

I remembering hearing during a science interview that our sun's color is white instead of yellow.  It only appears yellow because our atmosphere filters out the other colors.  The reasoning they used was that if the Sun were yellow, then snow would appear as yellow instead of white.  That reasoning does not have me convinced =/.

Can anyone please shed some light on this topic?

[Assistant]
Color is a bizarre, only quasi-defined notion -- it only loosely maps to the spectrum.  Hence, there are several good answers:

* **The Sun is yellow** both by contrast to the blue sky and because of scattering in the atmosphere.  If you look at the Sun with neutral-density filters that don't affect the spectrum passing through them, the spectrum is skewed toward the red by scattering of blue light (which goes to form the sky).  The mixture of dominant red and green elements gives a yellow resultant color.  If you simply squint, so that you can see the very bright Sun embedded in blue sky, then to the extent that you see color at all it is extra-yellow by contrast to the blue sky around it.

* **The Sun is green** because its emission spectrum is peaked in the green.

* **The Sun is blue** by contrast to the very red/yellow light we use indoors.  Its characteristic temperature is 6000K compared to 2700K for incandescent lights, so a small amount of sunlight seen in a darkened and artificially-lit room will appear quite blue.  (This is why old black-and-white TVs, which had a 6000K characteristic color, gave off the famous "blue glow").

* **The Sun is white** because sunlight is the most spectrally-even light most people ever experience.  Truly spectrally even light appears magenta or bluish magenta by contrast, though of course it just looks white after a while if it is the ambient light source.


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

[User] [Pirates of the Caribbean] Why isn't Will a skeleton zombie since he has one of the cursed pieces of gold?

[Assistant]
It only curses you if you take a coin from the chest. Its the act of taking it away from its place that curses you, just owning you doesnt curse you.

Remember, the crew used the coins to buy shit before they realised what happend, and none of all those merchants and whores got cursed.


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

[User] How does the body react to food after prolonged food deprivation. Will eating even a normal portion of food cause stomach aches or other adverse reactions?

[Assistant]
Food stimulates the pancreas to produce a hormone called insulin. This hormone has various functions, including lipogenesis (creation of fat) and glycogenesis (storage of sugar in the form of glycogen). Some resources are needed in order to make these processes happen, but a prolonged period of fasting depletes the body of them. So, in the end, the cells pull too much of those minerals from the blood, causing low phosphate presence in blood (hypophosphatemia), low potassium (hypokalemia), and others. That usually leads to various cardiac and neurological problems.
This is referred to as refeeding syndrome, and has been documented for a long time throughout history.


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

[User]
[LOTR] Did Gandalf suspect Sauron's return before he heard of the Necromancer?

It seemed pretty clear that after Gandalf heard of the Necromancer he suspected it was Sauron and thus wanted Smaug defeated all the more because he feared that Sauron would try to recruit Smaug. But did Gandalf always suspect this or did he just want to rid the world of the last Dragon?

[Assistant] Gandalf knew of the Necromancer long before he heard of Smaug. The Necromancer's presence was discovered around 3rd Age 1100, but at the time it was thought to just be one of the Nazgul. The world had many other, seemingly bigger problems at the time and it wasn't until 2060 that people began to suspect it might be Sauron in Dol Guldur after all. In 2063 Gandalf entered Dol Guldur, but Sauron fled into the East to avoid discovery and returned in 2460. The dragons didn't start their attacks on the dwarves until around 2570, and Smaug himself didn't take Erebor until 2770. In 2850 Gandalf entered Dol Guldur again, but this time in secret, and discovered the Necromancer was Sauron. But Saruman stalled and delayed, meaning the White Council did not agree to an attack on Sauron until 2941, during the events of The Hobbit.


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

[User] What is the difference between mortgage, rent and lease?

[Assistant]
Mortgage:  You get a loan for house.  You buy the house with this loan.  You pay interest and principle over decades.  After you're done paying, you own the house.

Rent/Lease: You pay weekly/monthly for the privilege to live there.  You don't own it.


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

[User]
ELI5: How do we know voter fraud does not occur in the U.S.? Is it possible that it occurs undetected? What evidence should voter fraud theoretically leave behind?

I've been wondering about this for a while and want to get a straight answer. One of the reasons people condemn voter ID laws in the U.S. is because they claim voter fraud is a non-existent problem. Apparently, we know that voter fraud does not happen, and I'm not sure how.

To me, it seems like voter fraud is the kind of crime that would leave behind no evidence if performed successfully. That's the whole point; nobody is supposed to know you voted illegally.

Based on my understanding, there is no evidence for widespread cases of voter fraud, but do we apparently know that nobody gets away with it undetected?

[Assistant]
I suppose that there is no way to "know" that people don't commit voter fraud undetected.  However, several organizations and government entities have looked into it, and have found that the rate of in-person voter fraud is ridiculously low.

Typically in-person fraud occurs when someone goes to the polls and says that they are someone else.  This is very rare.  The reason is simple, there is no benefit for the fraud committing party to do it.  Persons who want to commit fraud are typically politicians or those directly connected to them.  In-person fraud would be a slow and time-consuming process which would leave a lot of witnesses.


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

[User] ELI5: What happens if you get more than one "common cold" or seasonal illness at once?

[Assistant]
You get multiple viruses that likely have similar non-descriptive symptoms.

This happens all the time and you likely never noticed. You just might think you had a particularly bad cold.


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

[User]
What kills you when you burn to death?

Ok so the title sounds a bit silly but my question is,

What exactly is shutting down or ceasing to function when one burns to death? Obviously burning skin probably wouldn't *kill* you (not quickly anyway) and pain cant kill people AFAIK

So what is the fire doing to your body that causes you to die? is it heatstroke? does the fire burn through your skin and begin directly damaging organs? i was of the understanding fire killed you long before it was able to do this.

[Assistant]
> Obviously burning skin probably wouldn't kill you (not quickly anyway)

If your skin is burned deeply enough and widely enough, it can compromise circulation and also breathing as the skin tightens and blood vessels are compressed and the chest is unable to expand. In such circumstances an escharotomy can be performed, putting long incisions in the burned skin to allow the chest to expand without the skin needing to stretch.

It's very not pretty, in case you were thinking of googling it.


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

[User]
[Star Wars] Why does Darth Vader hand Han Solo over to Jabba?

Han Solo is a smuggler. Who does he smuggle from? The Empire! Who does he smuggle for? Jabba the Hut! So we know that the Empire and Hut clearly don't have much of a working relationship, otherwise this wouldn't be necessary. Even if Vader doesn't really care about Han, why would he go out of his way to help Jabba?

[Assistant]
Today, he does Jabba the Hutt a favour. Tomorrow, or next year, or in 20 years' time, when he needs to find a fugitive who's taken refuge on a Hutt-controlled world, Jabba may be called upon to do him a favour in return.

Solo was nothing to him except a bargaining chip.


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

[User]
Why is China preventing people from withdrawing?

Hi guys,

So apparently Chinese banks are preventing people in China from withdrawing their money.

My question is why?

Even if banks there lacked the liquidity, wouldnt they be able to just inject liquidity from their central bank as they have monetary sovereignty (rely on their own currency they print at the central bank rather than an imperial currency)?

Thanks.

Note: Im not interested in the cop out answer of oh well theyre an authoritarian communist regime or something like that, Id like an economic argument not a political one.

[Assistant]
Chinese banks are not stopping people from withdrawing money. 4 small village banks in Henan: Yuzhou Xinminsheng Village Bank, Shangcai Huimin County Bank, Zhecheng Huanghuai Community Bank and New Oriental Country Bank of Kaifeng; have stopped people from withdrawing money under suspicion that the banks might collapse.

All of them are in the same province and have the same private majority shareholder Henan New Fortune Group. Authorities have accused the company of being run by a local gangster who is using the banks to illegally finance other private investments. Under public pressure, the government has begun reimbursing villagers many of whom held savings accounts there under promise of high interest rates and other benefits.

This reimbursement has been both slow and patchy, while communication about how it will take place has been dismal, creating significant unrest particularly given it concerns many people's life savings.


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

[User]
[General] What individual has the highest kill count ever?

I was reading about a galaxy far far away in my local achieves and read about an individual named Luke Skywalker. He destroyed a massive star ship in one strike, killing many.

It got me thinking, who has killed the most, for good, evil, one attack, and over time?

[Assistant] Under Lord Rassilon of the Time Lords, trillions died each day, only to be reset and killed again. He's also responsible for the Great Vampires, who consumed entire species, the destruction of entire star systems, and who knows what other atrocities. He's a generally unsavory chap.


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

[User] eli5: Why do repetitive movements cause inflammation (ex tendonitis)? What exactly causes the muscle to become inflamed?

[Assistant]
it's not the muscles, it's the tendons.  Hence, tendonitis.

Repeatedly flexing tendons do not make them stronger.  They don't benefit from exercise.  In fact, repetitive actions weaken them since they're not made of muscle.  They're made of collagen, and while they're naturally resistant to damage, repeated actions over long periods of time can overcome this and cause real damage.


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

[User]
[Star Wars] How is it possible that Kanan isn't dark side?

The first time we saw Kanan in *Rebels* he shot and killed a rather defenseless stormtrooper. Yesterday I watched an episode where he shot a rodian in the back. He's definitely not following the doctrine of 'knowledge & defense'. He's also often angry and lashes out with rage. At the very least he must be the worst Jedi ever. I pity Ezra.

[Assistant]
> At the very least he must be the worst Jedi ever.

I mean, *he kind of is*, and that's what's so fascinating about him. If nothing else, it's because Kanan doesn't believe in himself anymore, not after he ran away from his master during Order 66. He even changed his name to help run away even further.

Kanan is pretty much the last person who should teach anyone anything about the force, and his mistakes are ramping up on Ezra rather quickly. Just look at how fast Ezra tried to jump head-first into the dark side if it meant gaining a new edge against the Sith/Empire.

Killing an enemy who is actively trying to kill you, or will present a threat in the future (Jedi can see the future, so they'd know) is not an instant road to the dark side. Jedi kill all the time, and it usually balances out in the long run. Kanan knows just enough about the dangers of succumbing to evil that he can toe the line, and try to provide an example to Ezra in how he *should* behave. And yes, this can be somewhat hypocritical when Kanan gets emotional and does extreme things in the name of defending his friends/family, but he's only human. And only half-trained himself.


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

[User]
[General] I'm new to this whole "villain" thing, why are all my fellow bad guys wasting their best shots against the heroes by *throwing* them?!

Alright, maybe I'm missing something here cause I'm not much of a fighter - I mostly just make bombs really - but every time I happen to catch a glimpse of our toughest guys fighting the heroes, it's like they're *trying* to lose! I swear, every time it looks like they've got the perfect kill shot, one of the meatheads just picks up the fallen hero and *throws* him. In what martial art are you supposed to kill someone by throwing them? Sure enough, nine times out of ten the hero just gets up, takes a breather while our guy lumbers over to him like an idiot, and proceeds to outsmart him and knock him out. I know the boss purposely hires idiots so they can't figure out how to overthrow him, but this is on another level. What good are henchman that can't stop one vigilante crime fighter?

[Assistant]
Unfortunately, there tends to be an inverse correlation between high physical strength and fighting skill. When you can kill people with a headbutt, you don't get enough serious fighting practice against opponents that can actually match you in physical combat.

Heroes aren't exempt from this, but you're right: it's definitely most common amongst henchmen, as they're intentionally chosen to be dumber than average.


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

[User] Since its been getting cold, when I get in my car in the morning and turn my music on it seems like its playing 1-2 pitches lower and a tiny bit slower. The best theory I can think of is the cold. Do we perceive our senses differently in colder climates?

[Assistant] I think you need more data. Get something to record with and record how it sounds on a cold morning vs how it sounds after warming up. You can then listen back to back in controlled circumstances. If the two recordings sound the same, it's a change in your perception. If the recordings sound different, it's something physical.


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

[User]
[40k] The Golden throne fails

What becomes of the Emperor? Do all the prayers of mankind turn him into a God? Is he reborn? Does mankind got extinct?

[Assistant]
There are a few theorys about what will happen when the throne fails.

1. The Emperor dies, dissipates in the warp and is gone. (*Heresy!*) The astronomicon goes out, the webway wards fail and demons overrun the throneroom and are now free on Terra. His death might also create a warpstorm, a new Eye of Terror that swallows Terra. The Imperium have now almost no way of navigating safely, and it will fail quickly. Its basicly the long night all over again, but this time there is no Emperor to reunite them.

2. The Emperor dies, the astronomicon fails, demons on terra, maybe warp storm etc,. except this time he is reborn somewhere in the galaxy. Most likely as the Emperor, but maybe as the schamans, but its unlikely they have the power to keep together their souls. The imperium fails, but this time The Emperor is there to fix everything again, but it will take time.

3. The Star Child. All the prayers and worship have given him enought warppower to become a full on God in the warp, a Chaos God of Order and Humanity. He most likely attacks the other chaos gods, , and the extreme amounts of people worshipping him makes him more powerful then the other gods, and he wrek shit. He will probably stop any demon incursions or warpstorms on Terra, if he can react quickly enought. He will probably not be the same as when he was alive, as the imperiums image of him is very different from how he actually was. But we will have a God which now basicly have the warp for himself looking over us, which is nice. Safe warptravel, no chaos, might get help from the emperors demons/saints. If everything goes right here, this might be the best option, as it would elminiate chaos, the worst enemy. If everything goes wrong, empy cant take out the other gods, cant save terra, cant calm the warp etc (he can probably keep the astronomicon lit, but if terra gets fucked that might be a problem.) If the worst happens we will have lost Terra, and have a ~~chaos~~ Order god that is as useful as the other 4.

4. The Emperor, finally free from the Golden Throne, heals himself and gets up. Its revealed that The golden throne have been keeping him in this living death all this time, stopped him from healing himself. He starts to fix his Imperium, which will be hard since eveyrhting is fucked up and exactly how he didnt want it. Ironicly, this would probably spark civil war, because some would declare the whole thing to be Heresy, some would think he is a lier and some just wanna keep the status Quo. He would have all of the Space Marine chapters with him tho, so he will win, after a long civil war where everyone else takes advantage to attack the Imperium.


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

[User]
ELI5 How does waking up work?

What makes our body decide, ok now it's time to get up? Why do things like nightmares often allow us to shortcut sleep and wake up early?

[Assistant]
Our circadian rhythm dictates our sleep/wake cycle. And it's primarily driven by light and temperature. Once the sun goes down, our bodies start releasing melatonin, preparing us for sleep hours before we're actually ready to go down. Cooler night temperatures also aid in this.

As the sun rises and temperatures increase, our bodies stop producing melatonin, allowing our bodies to wake naturally and slowly over time. Even with your eyes close, you're still receiving light through your eyelids.

It's another reason people say if you want to fix your circadian cycle you should go camping for a few days and get away from all the artificial light in your life.

Your body is still able to receive external input while asleep, to protect you from danger. Hence why certain noises might wake you in the middle of the night. Adrenalin helps get your body going in stressful situations while awake and also asleep. However, at night, you've still got melatonin coursing through you, so it's relatively easy to go back to sleep. If something startles you awake after the sun is up, your body has already slowed or stopped the production of melatonin and it's harder to get back to sleep or stay asleep.


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

[User] Is there a rule that states that calculations of particle interactions at micro scales, by nature, cannot be scaled up into the macro-systems? Or are we just limited by our current understanding and nothing really prevents us from finding a way to scale quantum equations upwards?

[Assistant] The problem is that even quantum systems containing *a few* particles are extremely difficult to solve. Treating a system of 10^(23) interacting quantum-mechanical particles is impossible, even if you know exactly the nature of their interactions.


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

[User]
Headphone material differences, why such different sound quality?

I am familiar with how speakers work, how different windings and cone materials and magnet strengths and so on, as well as the cabinet geometry, can work together to create speakers with wildly different sonjc quality.

What I am wondering about, though, is earbud headphones. The speakers are so small and the power and other characteristics are so much smaller scale, it seems like the materials will have much different behaviors.

So, in the context of a tiny little speaker in an earbud, what is it about the different materials that make one earbud have super detailed and clear response, and another pair sound like a tin can or, even worse, a super mid-range echo chamber or tunnel?

[Assistant]
For small headphones, there are two popular sorts of drivers. The first is the standard moving coil transducer you mentioned before, where a stationary permanent magnet interacts with an inductor attached to a cone, causing it to vibrate back and forth. The second is called a balanced armature transducer. These transducers are often used in hearing aids and higher end earbuds, and they rely on a carefully balanced permanent magnet being rotated slightly by the magnetic field created by a n inductor wrapped around the armature. The advantages of the balanced armature transducer is its naturally small size, it's efficiency, and the accuracy of its response.

Designing a loudspeaker is largely about tradeoffs. You want a flat frequency response, but the way you flatten it is by adding mechanical losses. You want high power output, but the mechanical losses you add to flatten the response take away from that. The mass of the cone and the stiffness of the elastic spring holding it in place will determine the cone resonance, which you generally want to be as low as possible, but that means having a really heavy cone (difficult to get at a small size) or loose spring (which has its own problems). Of course, acoustic filters can be placed in front of the transducer to help improve the sound after it leaves the transducer but before it hits your ears.

Geometry of the enclosure generally plays a smaller role for earbud design than traditional loudspeakers, since you don't have the resonances associated with a large box, and there's no real feasible way to increase the volume behind the speaker.

Often the best solution is just to put in multiple transducers for different frequency ranges. This allows you to tune each transducer for its individual range, with the tradeoff being larger size and higher cost. Balanced armatures are great for this because they can handle midrange and highrange very very well. You will sometimes see them supplemented with a moving coil transducer to shore up the bass frequencies. Of course, when you do this, you want to add a crossover to ensure that each transducer is only playing back the frequency range intended for it.

As for your question, the reason materials matter so much is that the materials largely determine the traits of speaker itself. The material of the cone determines its mass. The material of the elastic determines both its stiffness and its mechanical losses. The magnet chosen determines the power output. Likewise for the balanced armature transducer. The materials and build quality for the surrounding enclosure ensures that you don't have any weird mechanical resonances or vibrations.

Hope that answers your question. It's always fun to talk about transducers!


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

[User]
Did the United States' history of slavery contribute to its modern day wealth?

It seems to me that most of the modern day economic success of the United States can be traced to the industrial revolution and not to our past agrarian systems, but is there some way that slavery contributed to the dynamics that saw the United States reach the level of wealth it has?

[Assistant]
Going into the American Revolution, slavery was thought to be going extinct. The over planting of tobacco had exhausted southern soils, and plantations were suffering.

In the 1790s, however, new inventions began to appear in England. Utilizing steam power, they spun and wove textiles on an industrial scale. Factory owners scrambled to buy up whatever cotton was available, and its price shot up.

Eli Whitney's invention of the cotton gin in 1793 was no coincidence. It had been common knowledge that the South was ideal for growing cotton for a long time, but there was no incentive to do so. Now, cotton was in demand and profitable.

Remember when slavery was becoming *un*profitable? Well now states like Virginia had a huge surplus of slave labor, but its climate (cotton needs 200 days without frost) was unsuitable for growing the new cash crop. A new system arose. Enslaved individuals, becoming increasingly valuable, were shipped from the Upper to the Deep South. There, they were forced to produce valuable cotton for export to England's industrializing textile markets.

The significance of the new cotton industry cannot be overstated. By 1840 cotton comprised over half of all US exports. Tariffs helped fuel public projects in the North such as the building of roads and canals (not to mention that about 25% of Southern cotton was going into *their* growing textile industries).

So in many ways, the institution of slavery fueled the economic success of, not only the United States, but Britain as well. Textile industries are commonly the first stage in the industrialization of any nation. Here's a quote from Marx writing in the 1840s:

"Slavery is the pivot of our industrialism today as much as machinery, credit, etc. . . . Without slavery you have no cotton, without cotton you have no modern industry."

If you want more info/clarification, try these:

American Slavery: 1619-1877
by Peter Kolchin
Pg. 94-96

The Political Economy of the Cotton South: Households, Markets, and Wealth in the Nineteenth Century
by Gavin Wright
can't give you pg. numbers at the moment, sorry.


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

[User]
[DC] What happens to Gotham when Bruce eventually falls ill?

Let's assume this is before Robin became Nightwing.

Does the City go into absolute disaster?

[Assistant] He's rich, so has access to the highest standards of healthcare, and he's in great physical health in general. Right now, he's unlikely to fall ill for long enough for the city's evildoers to notice that the Bat Man is not around. As he grows older he'll start to have to worry more about being physically capable of crime fighting, but presumably that's why he took on a younger protege - an apprentice and eventual future replacement.


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

[User]
CMV: YouTube rewind will never be "good" again

Now, I'm not hating on YouTube for making a rewind people don't like. Quite the opposite. Before this year's rewind one of the most common criticisms of rewind was that it doesn't represent the YouTube community. I think YouTube has grown so large as a platform that they can't fit enough familiar faces for the majority of people to recognise in a rewind. This leads to most people who watch rewind thinking "this doesn't represent YouTube, I hardly know anyone in this". I don't think it is possible for YouTube to create a rewind that the majority will feel represent their perception of the YouTube community purely due to the number of creators compared to how many creators each of us can watch. Looking at numbers, there are over 2400 channels with more than 1mil subs. I'm not sure how many channels the average user actively engages in but it would be lucky to be even 0.1% of this number. Back when YouTube rewinds were liked the ratio of YouTubers engaged with to total YouTubers would have been much higher making it easier for YouTube to show the majority of people familiar creators. As such the like/dislike ratio has been gradually getting worse as the number of creators expands and the concentration of familiar creators in rewind is diluted for viewers. I accept it is possible that I am wrong and YouTube are capable of making a "good" rewind. Perhaps my reasoning as to why they won't be "good" is flawed and people don't feel like they need to see a lot of their favourite creators in rewind to like the video or even not dislike it. I hope I am wrong and it is possible for YouTube to make a rewind that the majority like, but I really don't think it's possible.

[Assistant]
counterpoint: Youtube rewind **was never good** **to begin with**.

It has always been shameless corporate marketing, showing token favoritism to big-money creators. It's like the academy awards: stars of the platform are coerced into participation for fear of appearing 'ungrateful' for receiving such an honor as appearing in the rewind. Youtube in turn gets the labor and celebrity of their stars for free to make their corporate video. And the whole 'it only comes once a year, who's gonna be in it?!' is just to generate hype in the youtube audience, to encourage that we all watch it and talk about it.

Asking when it will be good again is like asking when the oscars will be good again. They were never good to begin with. They are terrible every year and always have been.

To make a 'good' video, they would have to pay popular creators for participation/labor, and allow them to have creative input on their contributions to the rewind video. Neither of which youtube will ever do, because it goes against the very nature of what rewind is supposed to be:

A cash-grab pseudo-award ceremony, to make them look good.


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

[User] Why do some parts of the eyes not need blood vessels?

[Assistant]
The cornea and lens both lack blood vessels, since they need to be clear for good vision.

The cornea (front window of your eye) is only about 0.5 mm thick, enabling it to get the oxygen it needs via diffusion (the front half gets oxygen from the outside air, and dissolved O2 in the tear film. The back half gets its O2 from dissolved O2 in the aqueous humor).

The lens is not nearly as metabolically active as the cornea, so its oxygen needs are much lower. The oxygen it needs, it gets via diffusion from the aqueous humor (eye fluid).


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

[User]
[Star Wars Empire Strikes Back] Why was that cave on Dagobah strong with the Dark Side?

When Yoda tells Luke to enter that "Dark Side" cave and fight the vision of Darth Vader, what exactly makes this cave strong with the dark? Is it just that its appearance resonates with fear and anger?

[Assistant]
Canon: There's a vergence in the Force there,  infested with the Dark Side. It's origin is unknown.

Legends: Centuries ago a powerful leader of a group of Dark Jedi was killed there, and his death caused an intense dark presence to linger there. Similar phenomena have been seen in locations where other Dark Side users were killed.


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

[User] ELI5: Why are some upper case letter just a bigger version of their lower case (c to C, k to K) and some are completely different (a to A, r to R)?

[Assistant]
Different reasons. As you probably know, romans didn't have lower case letters at all. So they didn't develop simultaneously with the upper case ones.
Greek, on the other hand, does use lower case letters, so they got adapted into the alphabet that we use now (with varying levels of accuracy. Rho looks like p, but has nothing to do with it, for example).
Some letters, like R for example, used to look the same in lower case, but "evolved" over time into something that was more efficient for writing quickly by hand.


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

[User]
When is the right time to bring up a spousal hire?

My husband and I went to the same school for undergrad. He is now finishing his PhD and applying for a TT job there. I am currently a TT Assistant Prof. My husband would only take the job if they hired me too. He's getting ready for a campus interview. How/when do we bring this up? It's a small college, so people there remember me and know I'm a professor. I know they don't have any posted openings in my field, but I think they could use me.

[Assistant] After he gets an offer.  Thats the point at which the university has decided that they want him.   Thats when you bring up negotiating points, and this is definitely a negotiating point.  Before then, it is moot.


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

[User]
ELI5: How can they tell that a huge wildfire, burning hundreds of thousands of acres, was started by a single campfire, or dropped cigarette?

Surely whatever evidence was there is long gone?

[Assistant]
Fire investigators can tell which directing fires burned. With that knowledge that can get pretty close to the point of origin. Once there, they do some investigating.

I live in California and the Rim fire WAS suspected of being started by Marijuana growers. That's what the news said but fire officials have stated the origin is very steep and would not be a good place to grow weed.

One scientist has said it's possible the fire was ignited by a rock slide. Two rocks slamming into each other can cause sparks and it's been pretty dry up here.


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

[User]
When you sequence DNA, can you see epigenetic changes?

Would you have to have an older sample too? How's that work?

Edit: You guys are very informed in your fields. I'm impressed. A lot of academic communities act aggressively to those that are uninformed. Thank you all for your answers. Almost like I would need a few years to comprehend your discussions adequately. Weird, huh?

[Assistant] No, you cannot see them with standard DNA sequencing. Although egenetic changes do modify the DNA, they do not modify the actual sequence. You can detect epigenetic modifications with techniques such as chromatin IP, bisulfite sequencing, ATAC-sequencing, and Western blotting, among others; the technique you use depends on the precise modification you're interested in and how sensitive you need it to be.


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

[User] ELI5: What does Anti-Dandruff shampoo do that is different from regular shampoo?

[Assistant] Pharmacist here. Most common anti-dandruff shampoos contain selenium sulfide which helps decrease the rate of cell turnover AKA slows the rate of your skin flaking off of your scalp, therefore minimizing not only the appearance of dandruff but the amount of flakes that actually fall off. Other anti-dandruff products can also contain active ingredients pyrithione zinc or ketoconazole. The key difference between regular shampoo and these "medicated" shampoos is in the active ingredients.


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

[User] [Star Wars]Is there an origin/creation myth in Star Wars? What's the source (for lack of a better word) for humanity and/or life in the galaxy?

[Assistant]
Legends:

The biological ancestors of the humans where the Zell who fought a war on the planet Notron (Later: Coruscant) against the Taungs 200,000 Years before Ep. IV.

100,000 Years before Ep. IV humanoid settlers migrated to other planets. Over the next 70,000 Years the Zell evolve into humans and Notron is renamed Coruscant.

Canon:

Unfortunately theres no information in Canon about human history or anything related.


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

[User] [Castlevania] How exactly are there countless floating Medusa heads and yet each Belmont has also faced THE Medusa?

[Assistant]
It isn't fully explained but the "Medusa heads" are spawned from Medusa's head in some manner.  Maybe the individual snakes will fall off and grow into a flying head.

As for how so many Belmonts have killed Medusa, it is likely because of how powerful Dracula's dark magic is.  He is much more than just a vampire, he is essentially the embodiment of evil.  To the extent that Death itself acts as Dracula's henchman.  So reviving Medusa is probably pretty trivial.


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

[User]
I don't want to be anyone else. But I don't like myself much either. Are there any philosophers who has expressed this thought in philosophy terms?

I would much prefer to be myself than anyone else in this world. However, I really dislike some of my personal characteristics, my life circumstances etc. It's a kind of dysphoria that I am sure is not unique to me.

So my question is: Any any philosophy expressed this thought in their writings or speeches?

[Assistant]
Sren Kierkegaard said something close

"Marry, and you will regret it; dont marry, you will also regret it; marry or dont marry, you will regret it either way. Laugh at the worlds foolishness, you will regret it; weep over it, you will regret that too; laugh at the worlds foolishness or weep over it, you will regret both. Believe a woman, you will regret it; believe her not, you will also regret it Hang yourself, you will regret it; do not hang yourself, and you will regret that too; hang yourself or dont hang yourself, youll regret it either way; whether you hang yourself or do not hang yourself, you will regret both. This, gentlemen, is the essence of all philosophy"


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

[User]
ELI5:Why does closing your eyes after your alarm wakes you up feel so good?

Like you're not even asleep yet but it feels amazing compared to ur eyes being opened.

[Assistant]
The tear film on your eyes is reduced while your eyes are closed during sleep. If your bedroom is air-conditioned, the low humidity can make this even worse. When you first open your eyes, the reduced tear film dries out quickly and closing them helps redistribute the liquid that's left.

BTW, you may notice that your eyes do not focus as well when you first wake up - this is also due to the fact the the tear film is reduced or momentarily absent. Your eye's focusing system depends on the different refractive indices between each layer, i.e., from cornea to tear layer and from tear layer to  air, and is not as effective when the transition is directly from cornea to air.


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

[User] [Batman][Pokemon] How would Poison Ivy's plant-controlling powers affect grass Pokemon?

[Assistant] Well if we assume that all Grass types are Plant\animal hybrids. This is shown by their obvious sentience coupled with both plant appendages and features(flowers and leaves) as well as Plant abilities such as photosynthesis. she would be able to control them to some extent possibly greater the resemblance to the base plant the stronger the mental grip would hold.


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

[User]
Do any other monogamous species get "divorced"?

As the title says, are there any other monogamous species that stay together to ensure the success of their offspring but then get divorced and find new partners?

[Assistant] Swans (despite being famous for their pairbonding) do occasionally "divorce" around the rate of 4% if memory serves me. Swans are also known to cheat, but some evidence suggests that well established pairs are much better at raising cygnets (baby swans) than non-established swans.


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

[User] [General Time Travel] Which historical figure has the most time travelling vistors and how does the knowledge of becoming world famous for centuries/millennia affects that person?

[Assistant]
by far, FAR, the most visited historical figure is Hitler.

Countless amateur Time-Travellers go back to try to kill him, and are usually thwarted either by:

- time travelling Neonazis
- actual Nazis who dabble with super-science/occult and know how to stop a time traveller
- Time Cops that want to protect the timeline

The thing with visiting, let alone trying to kill historical figures is that it changes history greatly, splitting a branching timeline. For example, killing Hitler almost always results in Germany getting a new, smarter and more pragmatic villain for a leader, and WW2 gets much worse.

Interestingly, in timelines where Hitler meets time travellers and survives, he is not changed much. He already seems to consider himself a god-like being, and his enemies Untermench. Time-travelling anti-Nazi assassins only confirm his conviction.


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

[User] ELI5: If you're not supposed to microwave metal, why are there metal racks in some microwaves?

[Assistant]
You can microwave metal depending on it's time and shape as long as it is designed to avoid arcing. Microwaves cause localised charge to build up in the metal and in a fork for example it will try to redistribute this charge evenly which can be seen with sparks.

Basically rather than trying to educate Joe public in what metals are ok to go in the microwave it is easier to say you shouldn't use them and avoid lawsuits.


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

[User] [DC Comics] Could Superman give someone Lasik eye surgery with his laser vision?

[Assistant]
Depends on which incarnation of Superman, but probably.

In Superman vs The Elite we see him >!cut a tumor out of someone's head by shooting a laser through their eyes.!<

That version of Superman would be able to do so easily, but in most other versions the laser is probably too inprecise or simply too powerful to be used like that.

So, sadly, the answer is "depends".


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

[User]
Twins and DNA tests

As an identical twin and as someone that shamelessly watches the Maury Show this question always lingered in the back of my mind: If twin A fathers a child, and both twins were given a paternity test, would it say that both twins are the father? I know that twins have the same DNA but is expressed differently through the phenotype. But could this test say that both are the father?

[Assistant]
There are small DNA level differences between monozygotic twins that can be tested for - epigenomic changes (environment changing DNA expression) or differences in copy-number variations.

However, most paternity tests look at only a few parts of an individual's genome, and wouldn't be sensitive enough to differentiate the twins. They look at your "DNA fingerprint," choosing genes that are highly likely to vary between individuals. Monozygotic twins would have the same DNA fingerprint.


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

[User] [X-Men] whose power is actually very dangerous but often overlooked because when compared to others' it looks 'ordinary'?

[Assistant] Domino just appears to be generally lucky. Shit just happens and it's usually in her favor. But in actuality she's a mutant with the subconscious ability to manipulate probability in her favor. In other words, if she sets her mind to something, and it isn't impossible, it very well may happen. Now imagine if she wanted you dead how easy it could be for her.


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

[User]
ELI5: Why do machine dried clothes feel smoother than naturally dried ones?

Whenever I dry my clothes in the patio they get extremely hard but if I dry them in the machine they get extra smooth. Why is that?

[Assistant] The tumbling action allows the fibers to bend and move freely. Sort of like when spaghetti is cooked. if it's done at a rolling boil the spaghetti rarely sticks together but if it's done too low the starch holds the fibers together and you have to work to separate them.


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

[User] ELI5: Why do you often have less of an appetite when the weather is hot?

[Assistant] Some can be attributed to needing less input.  If your body does not need to create any warmth of its own because the weather is doing that for you, your body uses less than its normal amount.  Keeping warm is just one use of food energy, but a significant one.  Less drawn from reserves means less desire for food input.


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

[User] ELI5: Why does US debt and deficit seem not big of a deal, but that of Greece and 3rd world countries does?

[Assistant]
As a percent of GDP our debt is smaller than Greece's. We also have a much more diversified economy, more natural resources, and our citizens actually pay taxes.

We also have a couple advantages that are unique in the world, the biggest of which is that the US Dollar is the world's "reserve currency" meaning many international transactions take place in USD and all of these countries have a vested interest in a stable dollar.


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

[User] [MCU] If Dr. Strange didn't break the time loop in which he had Dormammu and the Eye of Agamotto trapped, would Thanos be able to acquire the Time Stone?

[Assistant] With all the other stones in his possession, Thanos could probably find and enter the loop.  He'd also have the power to wrest the stone from Strange and use it to break the loop before everything reset.


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

[User]
[Firefly/Serenity] Mal's Record.

Serenity tells us he was a Captain in the Browncoats army who was awarded a commendation of valor for his actions in the battle of Serenity Valley. The same battle we saw in the first episode of the series, where the Independent a were clearly on the ropes, denied air support, and told to lay down arms by command.

Is there an in-universe explanation for how Mal survived the battle? Did he retreat? Did he surrender?

[Assistant] Iirc one of the comics mentioned his unit managed to hold on for dear life while a cease fire was negotiated a few days after the events of the pilot episode.  The independent leaders capitulated after the cease fire and all soldiers were ordered to lay down arms in exchange for amnesty. Some like Zoe refused to comply though.


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

[User]
ELI5: How do series like Planet Earth capture footage of things like the inside of ant hills, or sharks feeding off of a dead whale?

Partially Im wondering the physical aspect of how they fit in these places or get close enough to dangerous situations to film them; and partially Im wondering how they seem to be in the right place at the right time to catch things like a dead whale sinking down into the ocean?

What are the odds theyd be there to capture that and how much time do they spend waiting for these types of things?

[Assistant] some of the series at the end do a brief section about how they go about capturing the footage that they showed.  They make their own custom rigs with various types of cameras to help them get shots. They leave camera 'traps' in places and hope to get lucky with them. They wander around following research or local guides to help increase their chances of being in the right place at the right time. So a lot of it is somewhat down to luck. They will know from research roughly where to go for certain things, but being able to capture specific things is down to luck on whether they get any usable footage in the days they allocated at a site. Depending on what they are looking to film at any given site, the time they allocate will differ.


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

[User] ELI5: Why do all living creatures have such wildly different life expectancies?

[Assistant] Basically every living creature only has to live as long as necessary to achieve maturity, find a mate, reproduce and optionally care for its offspring for a while. Reproduction has to be repeated as many times as is required to avoid population decline, taking into account the offspring mortality rate which is normally quite high. Any living time after that is just a free bonus and is not maintained by natural selection. Its just there. So life expectancy of a species depends on how much time is required for this species (on average) to complete doing all the things above.


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

[User]
Is it possible for a universe to have more than one dimension of time?

It is generally accepted that we live in a universe containing 4 dimensions (3 spatial, 1 time). Would it be possible for a universe to have two spatial dimensions and two dimensions of time? What about three spatial, two time?

[Assistant]
Multiple time dimensions lead to CTCs (closed timelike curves) which allow for violation of causality (timetravel).

Assuming you're familiar with special relativity:

take a Universe like ours but with an additional time dimension (2+3). So

`[; x^\mu = (x^0, x^1, x^2, x^3, x^4) ;]`

with `[; x^0, x^1;]` both time dimensions. The spacetime interval is:

`[; ds^2 = (dx^0)^2 + (dx^1)^2 - (dx^2)^2 - (dx^3)^2 - (dx^4) ;]`

now, as in normal relativity, the sign of `[;ds^2;]` being +, 0, - tells you if that little segment can be followed by a massive object, massless object, or not possible to follow at all (timelike, lightlike, spacelike).

Any infinitesimal movement purely in the `[; (x^0,x^1) ;]` plane is obviously timelike, since `[; ds^2 = (dx^0)^2 + (dx^1)^2 > 0 ;]`. Therefore, taken a closed loop in the `[; (x^0,x^1) ;]` plane, (e.g. a circle), that loop is timelike.

So you've built a timelike loop, a time machine. An object following the loop would return to its past, without needing to travel faster than light (and in fact, without having any velocity at all, since it does not move in the space dimensions).


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

[User] ELI5: What is Islamic Financing?

[Assistant]
Interest is banned under Islamic law so Islamic banking uses other means of profiting from giving loans.

for example, to get the equivalent of the mortgage, the bank doesn't charge interest. Instead the bank buys the house and you agree to buy the house from the bank for a higher price by making regular payments.

The end result is the same but the legal structure of it means that technically it isn't interest.

That's just one example. There are a variety of techniques that are used to effectively charge interest without it being what religious scholars would consider interest.


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

[User] ELI5: When I put chocolate milk mix in a glass and then add milk, it clumps up and doesn't dissolve well. If I do it the other way around it works fine. What's happening?

[Assistant] When you have a pile of powder at the bottom, not very much surface area is exposed to the milk, only the top layer. When you pour it into milk it is spread out and there is a lot much more surface area to dissolve into the milk.


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

[User] [Doctor Who] How do Time Lords genetically limit regenerations?

[Assistant]
We get conflicting information but it seems that the regeneration isn't an inborn ability, but something they're bestowed with- possibly part of the process that makes them for-realzie Time Lords instead of, well, ordinary Gallifreyans.

So they control the number of regenerations by only giving you that many in the first place, and can give more if they choose to (and everyone in charge of deciding to, decides to). As for why they'd bother putting a limit on immortality- it might be a failsafe to prevent society from growing too stagnant from having the same people in charge for eternity.


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

[User] Why was early universe made up of H and He? Were there any heavier elements?

[Assistant]
A bit of context first: Atomic nuclei join each other fusion, and that takes a lot of energy to occur. Take two or more "small" atomic nuclei (like hydrogen, say), crush them together under extreme temperature and pressure, and they'll transform into a helium nucleus. Those atomic nuclei are made up of smaller bits - protons, neutrons - that are in turn made up of smaller bits - quarks, gluons.

The Big Bang created a soup (called a quark-gluon plasma) of the parts that make up atoms, not atoms themselves at first. As that soup cooled and expanded over the first few minutes, those parts came together to form the simplest atoms - hydrogen and helium... and a tiny bit of lithium and beryllium (the next heaviest elements) too.

Over time and as stuff continued to cool, the hydrogen came under the influence of gravity to form local areas of higher density gas, then gravity sucked in more hydrogen. The centre of these clouds became hot and dense and under pressure enough for the hydrogen to start the process of fusion...and stars were born. Hydrogen transformed into helium, then helium fused into lithium, and lithium fused, and so on until the star couldn't do this and remain stable. Some of those stars eventually reached a point where they effectively exploded in novae and supernovae, and this hugely energetic explosion created enough energy to  fuse even higher elements to create uranium and other atomic elements with large numbers of protons.

**TL;DR**: The universe started out as a fog of dissolved subatomic particles. These first came together to form largely one-particle atoms (hydrogen). Then the hydrogen collected into stars, and their fusion results added other heavier elements later.


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

[User] ELI5: Why do weightlifters wear a belt on their waist?

[Assistant]
When you lift something heavy, you have to brace your core to protect your spine and stay tight. Imagine flexing the ab muscles and much as possible, as if you were anticipating someone punching you in the stomach. Now, you need to do this regardless of whether or not you wear a belt, but what a belt gives you is something to brace against. The most simple way I've seen it explained is this:

Imagine you can squat 500lb. This means you can generate around 500lb of force, right? But if you tried to squat an empty bar, you wouldn't be able to put 500lb of force into it because you'd have nothing to push against. The belt gives your core something to push/brace against.


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

[User] ELI5: Why are teeth the only bone we get baby and adult versions of?

[Assistant] Teeth are not bones they are made of completely different cells. Adult teeth would not be able to fit inside a babies mouth. A toddler with full primary baby dentition has 20 teeth. An adult, wisdom teeth included has 32. Contrary to popular belief you are not born with all of your teeth at once, the permanent teeth grow and develop under the baby teeth at varying ages. Baby teeth are very small as you grow and develop you need teeth that also bigger and can accommodate your larger jaw.


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

[User]
[Marvel] Can Wolverine get fat?

If he somehow managed to eat too much, would the excess just go to the meat dimension?

[Assistant] There was a post-apocalyptic mini-series called Universe-X. This world's version of Wolverine, is old, washed up, and fat. He later meets a version of himself from another universe who questions just how much he had to eat to get fat with a healing factor. So the answer seems to be yes but with great effort.


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

[User] Where there any texts/works that referenced Socrates before Plato existed?

[Assistant]
The playwright Aristophanes satirized Socrates and other philosophers of the time. Most of these plays, most notably *the Clouds*, were written around the time of Platos birth and before he started writing. Plato would later describe *the Clouds* as slanderous, and claimed it contributed to Socrates execution.

One notable feature of Aristophanes plays is that he doesnt seem to distinguish between Socrates (and philosophers in general) and the rhetoricians such as Gorgias. This is notable because several of Platos dialogs pit philosophy against rhetoric as two fundamentally incompatible approaches. This may reflect the fact that the divide between philosophers and rhetoricians was an intercommunity fight and Plato is exaggerating the differences, or it could reflect the fact that the typical Athenian wasnt knowledgeable enough about schools of philosophy and schools of rhetoric to know the difference.

The other pre-Platonic source is fragments of Ions *Travel Journal* which provide some bibliographic info about his childhood but little about his adult life or intellectual thought. Ion died around the time of Platos birth.

Theres only one other primary source of information about Socrates: the writings of Xenophon. Xenophon was a student of Socrates and a contemporary of Plato. While the exact date of authorship of his and Platos writings are unknown, his writings do not significantly predate Platos. While Xenophon certainly knew Socrates and some of his writings are primary sources, others are known to not be. He claims to be present for the dinner party featured in his *Symposium*, despite being nine at the time. Its believed that *Symposium* was written about sixty years after the date it is set and is a fictionalization and composite of real events. Another example of this is his *Apology*, which cannot be a primary source because Xenophon was not in Athens at the time of Socrates trial.


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

[User]
[DC Magic] What is the hierarchy of power among the magic users?

For example is Dr. Fate the most powerful being then followed by Zatanna  followed by John Constantine ? Have the magicians ever commented about other magicians being more powerful than them?

[Assistant]
Kinda depends.

Generally speaking,

Fate has the most raw power, but is somewhat less flexible.

Zatanna is next, has a lot of raw power, and a lot of flexibility, but she also tends towards the straightforward in thinking.

Constantine is the least powerful in terms of outright strength, but has a lot of knowledge, and knows a lot of tricks.

He is also the most twisty-minded of the lot, and has pulled some stuff seriously out of his supposed weight class.


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

[User] [MCU] So are Peter 2 & 3 variants? If so why weren't they pruned long ago?

[Assistant]
As of Loki the TVA and He Who Remains are gone so the multiverse can expand freely. It's how we got all of the alternate universes from What If.

A universe or a timeline can also exist as long as a Kang isn't born. So the TVA wouldn't care if Thanos won in Endgame or if Ultron, Dormmamu or Ego won as long as a Kang isn't a born.

But if a random Joe is 2 seconds late to work and that makes a Kang variant then that entire timeline gets pruned.


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

[User]
[MCU] Does the Bifrost lead anywhere or only the Nine Realms?

Heimdall was able to Bifrost Hulk away from a ship in the middle of nowhere. In AoS iirc, Sif Bifrosted the Kree away and took him back to the Kree planet. Also, did Sif take the reality stone to Knowhere using the Bifrost?

[Assistant] The Bifrost Bridge can go anywhere, but it requires more effort to create the one to one correspondence portal in new locations, so mostly it just goes to the nine realms, and unless stealth or haste is required, to some fairly predictable places in those realms.


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

[User] How come when pixels on an HD TV "glitch," they follow things like people?

[Assistant]
It's due to the way video compression works. Raw video would need extremely huge bandwidth (bits it takes to encode a second of video), so data compression techniques are used to lower the bandwidth usage to be able to fit on a DVD or being streamed over the internet. Using current compression techniques we are able to achieve huge reductions in file size as we can cram a full HD image in 6mbps (megabit/second) and still retain decent quality. Uncompressed HD footage can go up to 190mbps.

To achieve this, video frames a grouped together and encoded. Simply put, the differences between each frame are described rather as encoding each frame as a separate entity. So when a TV 'glitch' you see only the 'changes' between frames (often moving objects) until the video hits its next keyframe (every now and then a complete frame is embedded) and the decoder can start fresh from a complete image.

These glitches can happen because decoders are build to handle missing data or malformed data which inevitably will happen when reading media from the internet or optical storage.


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

[User] ELI5: What is a Ponzi scheme?

[Assistant]
Jill has 2 dollars. Jack tells Jill if she gives him the 2 dollars, he'll be able to give her 3 dollars back later. Jack does so and makes sure Jill tells all her friends what a wonderful deal Jack is offering.

One of Jill's friends now wants to lend money to Jack. Jack takes this money and waits for another one of Jill's friends to lend him some money. With the second friend's money, Jack is able to pay back the first friend with the higher return while pocketing some for himself. Now the first friend will tell his own friends what a wonderful deal this is. As more people lend Jack money, he is able to pay back the people whom he borrowed from earlier, pocketing a bit each time.

The problem is that this money doesn't just appear out of nowhere. The only money coming into the system is the money from Jack's lenders. Meanwhile, money is going out through higher pay outs to earlier lenders and money that Jack has been pocketing and spending. Eventually, there won't be anyone left to lend their money to Jack. Earlier lenders now want their money with interest back. Suddenly, there is more money going out of the system than into it. Eventually, Jack decides to just disappear with what is left, leaving a lot of his later lenders with nothing.


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

[User] ELI5: How is a currency's "value" determined?

[Assistant]
Supply and demand.

If the demand for a certain type of currency increases (i.e. more people want it) and the supply stays constant, the value of the currency increases.

Conversely, if the supply of a certain type of currency increases (i.e. more of it is created) and the demand stays constant, the value of the currency decreases.


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

[User] On a molecular level, what is happening to molecules/atoms when a sticky substance is torn in half? For example: modeling clay. What creates the "tension" in these substances?

[Assistant]
Tearing something in half is a physical change, not a chemical change. While that means that chemical bonds arent necessarily broken or formed during this process, weaker interactions caused by intermolecular forces between molecules (as well as the surface energy penalty to create two new surfaces) hold the substance together and must be overcome for a tear/fracture to occur. Something being sticky just means that the intermolecular forces between your hand and that substance are relatively large, but its really the IMFs that are present between different molecules of the substance that affect how easily something tears.

As it turns out, modeling clay is little bit more complicated. What we think of as modeling clay is more generally known as polymer clay, which is composed of PVC (polyvinyl chloride). PVC is the stuff that those white pipes are made of, so by itself, its pretty tough. A plasticizer is added to decrease the attraction between the polymer chains just enough so that youre left with a flexible substance that you describe as having tension. Ultimately, the degree of tension or plasticity comes from the intermolecular forces between the polymer and plasticizer, as well as how much cross-linking is present in the polymer. The combination of PVC and plasticizer gives modeling clay some interesting rheological properties: when we mold the clay, we apply stress and it flows like a viscous liquid. But when we release the clay, it behaves as a solid.


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

[User] ELI5: If sweating exists to control body temperature, why do sometimes people sweat from their feet or hands even though they are frozen cold?

[Assistant] If you've been doing physical work, your core temperature will increase, largely regardless of the outside temperature.  the natural response is to sweat to remove the excess heat.  since your head and feet (and hands) tend to have alot of capillaries near the surface of the skin, they tend to be much more efficient at removing excess body heat compared to the rest of the body, where blood vessels are deeper.


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

[User]
Is there a social scientific equivalent to what A Brief History of Time is to popular science?

I have some friends who are getting me interested in science writings like Surely You're Joking, Mr. Feynman! and A Brief History of Time. Basically, science writing for the general population. Is there a social scientific equivalent to what these books are? Something I could recommend to a math major to get him interested and to understand the basic principles of social science?

[Assistant] Despite its many criticisms, *Guns Germs and Steel* and other mass-media publications by Jared Diamond probably fits the criteria. His work is geared more toward the anthropology and human geography side of the social sciences.