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

[User]
ELI5- [physics?] firing a gun from a moving train.

So lets say I'm of the front of a train traveling 200mph (it's a special train that goes 200 mphs). And I firing me gun directly ahead of me. Does this add or subtract from the speed of the bullet? Also, if I was on the rear of the train and fired that direction would it have a different effect?

[Assistant]
In relation to the train, bullet would go at the speed of a bullet.

In relation to someone standing near the tracks, it would go at the speed of a bullet + speed of a train.

If you were to shoot opposite to the direction of a train, your bullet would go at bullet speed - train speed.

If you were to shoot at an angle, you would have to do some trigonometry to calculate its speed and exact direction.

EDIT This is an approximation that works only on normal speeds. When you start adding speeds of light, then you need another equation because time and space do very weird things at these speeds.


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

[User] [Star Trek: The Next Generation era] Does the Federation have a zero-tolerence policy regarding genetic engineering? Do they allow parents to fix things like Down's Syndrome, or repair faulty genes that cause severe inherited genetic disorders?

[Assistant]
No. The Federation does not have a zero-tolerance policy regarding genetic engineering.

* They use it for scientific and research purposes (TNG: Unnatural Selection)

* The Federation allows for a more "natural" form of genetic engineering via Eugenics practices (TNG: The Masterpiece Society)

* Yes, genetic modification is allowed to fix conditions or diseases (VOY: Lineage)

* Extreme genetic modification of a fetus is discussed for cosmetic reasons and denounced, not on legal reasons, but because there was no valid medical reason (VOY: Lineage)


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

[User]
Do animals demonstrate traumatic responses to "sexual violence"?

I've read that much reproduction in the animal world is what we would consider rape if they were humans. I was wondering if there are any studies that examine the response of females before an after forces reproduction / "rape". (I put the phrases "sexual violence" and "rape" in quotation marks because I don't want to act as if human sexual assault is "no worse than" as animal reproduction, it obviously is horrible.)

[Assistant]
The other poster is correct that we cannot measure subjective experience in non-human animals. That said, however, we *do* indeed see trauma responses in mammals (someone else will have to contribute for other animals) in response to situations that humans would consider "sexual violence".

As an example of this, kittens can be overpowered and "raped" (quotes for the same reason as you have used them, OP) by adult male cats before they reach a year old. This is known to stunt their growth if they have kittens of their own as a result. Female cats to whom this has happened also have a tendency to exhibit fear, aggression, and avoidance behaviors around male cats for the rest of their lives.


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

[User]
[Star Trek TNG / BSG Reboot] How would Captain Picard handle running into the Colonial Fleet under Adama, with the Cylons in hot pursuit?

This takes place after Best of Both Worlds in TNG, and before the discovery of New Caprica in BSG. Assume the BSG Colonies all exist in an uncharted corner of the Star Trek galaxy.

How would Picard and the Federation respond to an aggressive force like the Cylons? Would he offer sanctuary? Military assistance?

[Assistant]
Federation technology is so far ahead of the Cylons they can essentially do whatever they want.

It'd be like the original Enterprise trying to fight the Borg.

Anyway Picard would step in but would avoid declaring for either side given that he has the power to basically bitch slap both sides in perpetuity. It would likely end up with Picard giving a grand speech which ends up with Cavill killing himself while all the women Cylons all have sex with as many humans as possible. Something like that.


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

[User]
If you are campaigning for president and explicitly lie about a topic publicly and you win the presidency you should be impeached and possibly removed from office. CMV

So, for example, lets say President A said "I will lower unemployment to below 6% by November of next year." If the President does this, then it is all fine and dandy. However, if he does not he should be impeached. The senate should then decide if he is worth of being removed from office. I think this would work because it would force the President A to state how he is going to get unemployment below 6%, instead of just saying blatant lies. It would also add some transparency to the President and U.S. Government, instead of everything being "hush-hush." I agree, some things have got to be kept quiet but blatant lies should be punishable.

[Assistant]
The president doesn't just get to "do" things he wants to or promised. He can influence legislation but as far as the actual drafting and passing of bills that's all about Congress. He can strive to change tax rates but at the end of the day what he can and cannot accomplish is hugely tied up  with the other two branches of government (for good reason) and so it would be unreasonable to base his job security on things outside his control.

Most candidates, at least successful ones, do lay out plans they'd follow to carry out their campaign promises. Unfortunately they need everyone on board to actually carry out the plan which rarely happens.


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

[User] ELI5: Why are alot of train stations in major cities (mostly north american cities) are all called Union Station.

[Assistant]
Basically a station is called a "Union Station" when tracks and other facilities were shared by more than one railway. It's always a passenger terminal.

This allowed passengers to quickly go from one service to an other, when railways were more regional. So, for example, you took one train to Chicago, and jumped on another train from there to Los Angeles.

In Europe they're called "Joint Stations".


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

[User] [MCU] Did Thanos ever at any point care about Nebula?

[Assistant]
Thanos cared about all his children.  We can see this towards the end of Infinity War when he realizes they're all dead or dying, and his heart is barely in it to keep going.

The issue with Thanos is that he's insane, and sincerely believes he's being a good father to his children and helping the universe with his slaughter.


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

[User]
ELI5: What gives aspartame and other zero-calorie sugar substitutes their weird aftertaste?

Edit: I've gotten at least 100 comments in my mailbox saying "cancer."  You are clearly neither funny nor original.

[Assistant]
Sucrose is considered clean and has no aftertaste (clean meaning it only activates sweet receptors). Other sweeteners activate both sweet and bitter receptors. However, because artificial sweeteners are so powerful, they quickly overwhelm the sweet receptors. The bitter receptors still scale up though with greater mass for longer. That is why aspartame you consume is actually mostly filler ingredients, because otherwise you would be overwhelmed by the bitterness.

Edit: If you are particularly affected by/dont like an artificial sweetener feel free to avoid it.


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

[User] ELI5: What is a 401(k) and how does it work?

[Assistant]
It's a type of tax-advantaged retirement account available in the US, set up by employers for their employees to use. The employee controls how much money gets put in, up to a certain amount ($18,500 for this year). The money is withdrawn straight from their paycheck to deposit in the account. The money is usually invested rather than just sitting in a savings account. In some companies, the company will match part or all of an employee's contributions to the account. You have to pay a penalty if you withdraw money from the account before you're 59.5 years old.

There's two ways to put money in: either traditional (you don't pay income taxes on the money now, but you do pay taxes when you withdraw the money in retirement) or Roth (you pay income taxes now, you don't pay any income taxes on the money when you withdraw in retirement).


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

[User]
[Pokmon] What happens to the Pokmon in the PC when a trainer dies unexpectedly? Are they trapped forever?

What happens to orphaned Pokmon anyway in this situation? Left in wills? Donated? Released? Given to the state?

[Assistant]
From the *National Trainer Handbook*, chapter 17, section 2:

"In the event of a trainer's injury or incapacitation (see section 3, *Blacking Out*), the trainer's Pokedex notifies the nearest Pokemon Center, which is capable of teleporting the trainer to the Center for emergency care.

"Use of this emergency system is not billed to the trainer's account, but excessive incidents may cause a safety meeting to be called on the trainer's behalf. Continued use may void the trainer's status as a legal Pokemon Trainer.

"Since its implementation, there have been no confirmed trainer deaths in the field. However, it is impossible to accurately gauge the mortality rate of illegal trainers in the field, who refuse to maintain their legal status in exchange for the many programs offered by the Pokemon Center."


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

[User]
[Hunger Games] I snuck outside of District 12 with a friend of mine and we found a flag with a blue rectangle in the top left corner with I think 50 stars and 13 red and white stripes. My friend also found this book on this think called the Constitution. What is it, and what do we do?

So me and a friend of mine were just walking around outside of 12 when we found the things listed above in the title. It looked pretty cool and the book has some weird writing and lingo, but it has a really nice leather cover so Im keeping that.

But what should we do with the flag and this book? Should I report it? Sell it at the Hob? Keep it?

[Assistant] Think we went over that for a chapter in history class. Has something to do with one of the old governments that went to shit and destroyed the world, before the Capitol reined everyone in. I'd just toss it.


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

[User]
[Star Wars] Why did Obi Wan blow 20 years of hiding on Tatooine by using his lightsaber to cut off the arm of the guy who hassled Luke at the Mos Eisley cantina?

I was just watching clips from A New Hope and a certain scene jumped out at me. In the Mos Eisley cantina when Obi Wan takes Luke to meet Han, Obi Wan uses his lightsaber to cut off the arm of a guy who was hassling Luke.

So Jedi have systematically been hunted down throughout the galaxy and Obi Wan has been in hiding on Tatooine for the past 20+ years, successfully evading the Empire, but now he just blows all that by whipping out his lightsaber and maiming some lowlife thug who could have easily been dealt with in a much quieter manner? And in an establishment filled with bounty hunters and criminals who would no doubt report the presence of a Jedi for a reward no less? Why draw attention to himself like that after all those years, especially since he was trying to get himself and Luke off-world rather covertly.

I know it's probably irrelevant, but it just seemed kind of odd to me.

[Assistant] Because he was going to Alderaan anyway to initiate a Rebellion against a Galactic Empire. And this drunk peon on some shit hick planet is getting rowdy with the enemy Sith lord's kid, his past padawans kid, who is now under his protection. He's Obi Wan. He was making a statement. Bitch, the jedi aren't dead yet. We're just getting started.


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

[User]
Could a gradual (but accelerating) slowdown of the
speed of light account for the appearance of an
increasingly expanding universe?

First, please understand that I am NOT referring to the c-decay theory that young-earth creationists try to use to reconcile astronomical evidence with the notion of earth being only maybe 10 millennia old.  I am instead asking how we could (and presumably do) know that the acceleration of the expansion of the universe is due to the actual expansion of the universe and not the the fact that our meterstick (the light-year) got shorter over time?

Consider a universe with only two bodies; a star and an observing planet a great distance away, stationary to one another.  Then assume that the speed of light decays over time, and the rate of decay increases over time; not the lifetime of the light in question, but all light in this particular universe.  Would not the light from the star appear redshifted to the planet?  Each photon that came out would be slightly faster than the next to come out, which would be slightly faster than the one that follows it, and so on and so on.  As the decay of the speed of light grew, the apparent redshift would also increase, without any necessary movement on the part of either body.

But even if that was the case, how would we KNOW?  Assume the planet has a ship that can travel at relativistic speeds, say .9c; as the speed of light decreases, .9c also decreases, and so the trip would take longer each time, which, for all intents and purposes I can think of would seem to be identical to an increase in the distance between the two bodies.

I'm just a dabbler in phsyics and astronomy, but I can't see how this result would fail to stand if extended to our universe; the rate of c-decay would be very slow (probably requiring at least geological timescales to be noticible), but it would still make sense.  It also seems to me more plausible for c to decay (a form of entropy) than objects accelerating away from us with no visible input of energy (anti-entropic behavior)(although I realize both notions are based off probably-inapplicable analogy rather than a proper understanding of the relevant physics).

I'm sure that someone has proposed it and there's good reasons for dismissing it, but I can't think of any way we could tell the difference between acceleration and c-decay.  Help!

[Assistant]
No.

You mention doppler shift based purely on time of arrival of photons. An analogy to your example: If we had a pulsar and its pulses were growing further apart then we could say either it's rotation is slowing or it is accelerating away or more unrealistically the speed of light is slowing down. However, if we have a spectral line for which we expect to be a certain colour then it doesn't matter how spread out the photons are they are ALL the wrong colour.


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

[User] [Canon] How are the giants from GoT able to sustain their body mass in an area with little food?

[Assistant] Large animals can definitely survive in cold lands.  There is probably more food up there than you think just little for large immobile cities.  Slow metabolism is most likely a part as well as a broad omnivorous diet.  But think of polar bears, moose, wooly mammoths, etc.  All live in similar climes and are quite large.


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

[User] ELI5: Why vehicles depreciate in value so quickly as soon as you leave the lot?

[Assistant]
Imagine if somebody just bought a new computer and within a few days tried to pawn it off on you. Would you take this as a generous offer, or would you assume there's something wrong with it?

Cars might be made in factories, but there are a number of moving parts that can go wrong, or worse, it could be a lemon. Within those first moments of going off the lot, you can only have things go wrong. If you want to resell it, why? You obviously aren't going to get the same price you bought it for, so you aren't trying to flip it for profit. Statistically speaking, there is something wrong with that car.

Now lets say you waited a year. The new models of cars have come out and there could be dozens of reason one wants to sell last years car. Even if it was a lemon, the resale value is much higher than it was right off the lot if only because it's more reasonable for somebody to get rid of such a "fine" products. Unless the model in question had several recalls and/or a particularly bad reputation, you can expect a higher resale value than you would get had you sold it right out of the lot.

One last thing of note is, practically everything about selling cars is a headache of many people in the know selling to a customer they hope is ignorant. Sales people will try to mark up everything where they can, well past the actual value of the car, and sometimes up-sell things that are assumed standard in a resell market as "features" to wriggle even more money from customers. It is fairly rare that cars are actually sold at their proper value as even people who are good at negotiating a fair price get fatigued by tenacious sales practices. One of the reasons cars depreciate so quickly, is because they were never actually as valuable as the price they were bought for.


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

[User]
Why can you see fog in the distance, but not right in front of you?

I always wondered, why 50m+ near me I can see the fog, but not closer to me.

[Assistant] Fog is water particles in the air. When youre looking in front of you, you notice the particles in a low volume (just in front of you). When you look in the distance you observe a higher volume and by extension a higher number of particles. The higher number becomes noticeable and yousee the fog.


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

[User] [Harry Potter] Why are there no wizard colleges or universities?

[Assistant]
Very few students would want to go into that level of education, plus the fact the role is taken by apprenticeships similar to how medieval blacksmiths or bakers were trained.

When a wizard or witch wishes to take a career path they must ask a wizard / business within the field to take them as an apprentice in order to pass down the teachings and training. Certain government professions, such as Healer or Auror, have you assigned to a senior to train but in the private sector it's entirely at the digression of the person you are seeking apprenticeship with.

Of course there are rules primarily governed by the union / guild that the business owner must follow such as taking at least one apprentice and breaching these rules can lead to fines or union / guild support seizing.


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

[User]
[WH40K] Aside from Malcador the Sigillite and his Space Marine legions, did the Emperor ever employ other immortals like himself?

I know he had designs for John Grammaticus, but he unfortunately died in battle and was snatched up by the Cabal before he could take the Emperor up on his offer.

[Assistant]
First, a correction. Space Marines and the Sigillite are not known to be immortal. Space Marines suspect themselves to not die of old age, but they always die in combat and no one has any idea about the Sigillites past.

His gene-son Vulkan was a perpetual like the Emperor. He also directly employed another perpetual, Alivia Sureka, to watch over the warp gate in Molech. Ollanius Persson also fought for the Emperor in the Imperial Army, but their exact relationship at that point is unclear. Persson had retired from the Army before the Heresy and was trying to be a farmer,  before the Heresy put a stop to that.


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

[User]
ELI5: What is a credit score, how does it work, and why is it so important??

Im sorry if this basic knowledge, but I honestly dont understand any of it.

[Assistant]
A credit score is a number that financial institutions use to judge how likely you are to pay back any loans or credit extended to you.  The higher the score, the more stable and trustworthy they view you.

The score is important because many large purchases in life usually require a loan.  For example, a car loan or a home mortgage.  The better your credit score, the better terms the bank will extend you on the loan.


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

[User] [Marvel Cinematic Universe] Can Antman punch the coronavirus to death?

[Assistant]
He technically could punch individual virus "cells" (virions) into pieces. However he'd be overwhelmed by the number of individual virions even a single infected person would have in their body.

Edit: A typical infected cell can release 1000 virions per day, and each virion creates another infected cell. Typical incubation time before symptom onset for coronavirus is 11 days, so that's at least 10^32 individual virions that he'd have to punch.


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

[User]
When was the cosmic background radiation in the visible spectrum?

And how long ago did it fade out of visible?

[Assistant] The CMB was in the visible spectrum when it was emited. The universe was at roughly 3000 K (For comparison: The surface of our sun is 5800 K) at that point, which means it would seem red to us.  From this point on it was shifted to the current value of approximately 2.7 K.


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

[User] ELI5: If the Gregorian Calender (Common Era) uses the birth of Christ as a reference for year numbering, why isn't Christmas celebrated on 1st of January?

[Assistant]
The Gregorian calendar (1582) has nothing to do with year numbering.  It was just a small revision to the Julian calendar (45 BC) in order to account for the fact that a year wasn't *exactly* 365.25 days.  In other words, the calendar was set in place before Jesus was even born.  We had the same amount of days in each month as the emperors of Rome had.

Christmas is on December 25 because the Romans wanted the pagans to become Christian, so they sorta set Christmas up on the same day as the pagans' solstice festivals, to make it easier for them.  This was sometime in the 300s or 400s AD.  But the AD system wasn't invented until 525 AD (*after* Rome fell), when Dionysis Exiguus determined that Jesus was born in 1 AD (he was off a few years though).  The date of Jesus's birth was already "settled" by then...just not the year.

You are assuming that the religious holidays would have been set at the same time as the year numbering system (and at the same time as the calendar was set).  They were all different times.


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

[User]
ELI5: Why do simple-looking websites like Google's homepage sometimes have enormous amounts of seemingly incomprehensible code?

See for yourself by going to Google and clicking 'view source'

[Assistant] Because to the right person, it's not incomprehensible. All that code does something whether provide analytics, predictive text, sizing for your browser, etc... a lot of stuff happens behind the scenes to make things appear smooth, fast and easy.


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

[User]
If cancer and psoriasis are both overactive cell growth, what is it that makes them different?

If you were to compare skin cancer vs. psoriasis they are both described as overactive cell growth, though with different results and degrees of danger. A) how are they different, and B) what is it that makes cancer more dangerous than psoriasis?

[Assistant]
oncology doc - Interesting question!

The short answer is that you're right, psoriasis and cancer are both due to overgrowth of cells - but different kinds of cells, and for very different reasons.

Try to visualize this a pyramid. At the apex is a single cell type. On the next level, there are two cells. Then 4 cells on the level below that. That's sort of how cellular differentiation works in the body; a non-specific cell gives rise to slightly more differentiated cells, which gives rise to slightly more differentiated cells, etc, until you have mature cells of X,Y,or Z function.

There are a multitude of different kinds of cancer, all of which are due to an uncontrolled proliferation of a certain cell type. Leukemia, for instance, is due to clonal overgrowth/expansion of an immature blood cell precursor. Something like, say, breast cancer, is due to an uncontrolled overgrowth of the cells that comprise certain types of breast tissue. Cancer cells have typically undergone/acquired some mutation that allows them to either proliferate without the need for external stimulus, or ignore external stimuli telling them to stop dividing, or shuts off a cellular 'self-destruct' mechanism that should make them stop once DNA damage occurs.

In psoriasis, there is an overgrowth of a well differentiated type of cell - the keratinocyte. HOWEVER, and this is the key, the overgrowth is not due to a driver mutation as in cancer, but rather, the result of an inflammatory stimulus. In psoriasis, there is hyper activation of the pro-inflammatory/immune cells within the skin. That activation causes them to release cellular signals (cytokines) that encourage the keratinocytes to proliferate and divide far faster than they usually would, because those signals are meant to be released when local destruction occurs and extra cells are needed to fill in the damage. That proliferation isn't due to some mutation in the keratinocyte, but rather, overactivation of immune cells, which are telling them to do so. To take it a step further, the keratinocytes are then attacked by the immune system, release signals that cause the recruitment of immune cells (because there is localized inflammation), which continues the process.

TL;DR: Cancer is an uncontrolled proliferation of cells. Psoriasis is an immune deregulation where inflammatory cytokines are causing local inflammation, which causes cells to proliferate secondarily.

I hope that helps!


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

[User]
[General] Can someone be both a werewolf and a vampire at the same time?

If so, what would their life be like?

[Assistant] In the vast majority of settings no.  In some, attempting to turn a werewolf into a vampire will kill them, and werewolf bites / scratches can harm vampires.  In Underworld, there is someone who is a vampire/werewolf combo, but he was a special case and that setting in general falls squarely into the two races being lethal to each other if combined, even at a cellular level when mixing their blood.


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

[User]
ELI5 : How does flowing electricity in a closed circuit lead to an LED lighting up?

An LED (bulb) lights up when it is in a closed circuit with a battery. 'Because electrons flow in the circuit'. But what is the mechanism that transforms this kinetic energy of electrons into light energy? Should I be asking a different question?

[Assistant]
Older incandescent lights worked by making part of the circuit a special kind of wire that electrons really don't like to flow through. They scrape and bang and batter as they flow through that part of wire, which creates a kind of electrical friction. That friction heats up the wire so much that it glows, like a campfire cinder. That's why those kinds of bulbs are really hot to the touch, they're less light-making machines as they are heat-making machines that happen to glow as a side effect.

LEDs are trickier to explain correctly. You can imagine an LED like a huge cliff, with a high end and a low end. The power source stuffs electrons onto the high side and pulls them out of the low side, creating a situation where you have a ton of electrons crowded together at the top of the cliff and almost no electrons at the base of the cliff. The electrons don't like being crowded, they'd prefer to be down at the bottom where they can get out of the crowd. Luckily, there's a set of playground slides that will let them slide all the way down. But to ride the slide, they have to pay a toll. The price is 1 photon of light of a certain color. So electrons "pay up", release a photon of light, and go down the slide. Those released photons make the LED glow in a specific color.


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

[User] ELI5: Why is it that when I'm very thirsty I'm able to chug water very quickly but when I'm less thirsty it feels like there is some resistance?

[Assistant] Hunger and thirst share some pathways. Leads to the pro dieting tip - if you are on a diet and think you are hungry drink a glass of water first. If you still feel hungry then you are actually hungry. The reverse applies here - if you have a full stomach and try to drink, your body will be more resistant than if you have an empty stomach.


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

[User]
Can the Standard Quantum Limit for the repeated measurement of a free mass be broken in theory?

Maybe I am cheating here, given that my not knowing the answer may come from my incomplete literature review. But I am getting confused by the claims of the contractive states breaking the limit, and yet a reinterpretation of definitions of precision and resolution seems to validate that *repetitive* measurements can *never be broken* due to the Heisenberg Uncertainty Relation between the Standard Deviations of the positions of the free mass at the first and the second measurements, which equals to the SQL. But the review paper I read itself said, after pointing the the HUP=SQL, that the SQL is not a fundamental limit. How?

Does the Uncertainty relation mean that the SQL can never be broken? Shouldn't it? Does it mean no one's working on breaking it? All the above paragraph was from papers from before 2000s, so what's the consensus now?

[Assistant]
It's hard to answer without more context or without knowing the papers you're actually reading, but maybe it's *squeezing*?

The Heisenberg inequality is typically the product of the variances of two conjugated variables or quadratures, e.g. XY/4. Naively, one would assume that X/2 and Y/2 in this case.

However, it's possible that one of the variance is smaller than that *naive* limit, as long as the other is greater, e.g.  X=/4 and Y=. In this case, we say that X is *squeezed* (because X</2); i.e. that it *appears* to beat the quantum limit. In reality, no real limit is violated because XY/4 holds.


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

[User] ELI5: Why does time seemingly pass so fast when I'm lying in bed and can't sleep?

[Assistant] There's a good chance you are sleeping some of the time, but don't realize it. Probably not a deep, restful sleep if you are repeatedly flitting in and out of consciousness. But it will make time seem to go by quickly.


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

[User] ELI5 Why, in an airplane that cost millions of $, the mic of the pilot sounds like a 5$ mic ?

[Assistant]
The mic is fine. If you've ever been on a plane with a built-in entertainment system and heard an announcement over your headphones, it was probably perfectly audible.

The issue is projecting the sound that mic captures into the cabin. It's not trivial to equip a large space for sound, especially when you're fighting all the vibrations and white noise produced by the engines.


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

[User] ELI5: Why do birds fly south for the winter instead of just staying where its warmer all the time?

[Assistant]
Two reasons: summer days are longer near the poles compared to the tropics, meaning more time for activity; and springtime sees an absolute explosion of food resources (insect and plant population growth) so the birds that fly back north get access to it, whereas the birds that would stay down south continue having to compete for a standard amount of resources.

Basically, seasonal variation makes for some months with an overabundance of food (ie spring) and some months with a dearth of food (ie winter). They fly south to avoid the lack of food.


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

[User]
[DC comics] How does Waller ever expect her suicide teams to succeed or complete the mission when she makes them as difficult as possible to the point of becoming antagonistic to the mission itself? like not giving them enough information or straight up lying to them.

Or instead of letting them regroup and try a  different strategy just forces them to go into completely unwinnable situations where everyone just dies and she gets nothing. and the tons of other crap she pulls ? How is she expecting them to accomplish anything? or is this just her sick enjoyment in killing prisoners?

[Assistant]
There are two main points to consider:

First, they're super-villains. They can't be trusted with knowledge, because they'd find a way to use it to fuck her.

Second, she can just keep throwing bodies at the problem. She willingly sacrificed an entire strike team in order to make it slightly easier for another strike team to infiltrate an island.

She doesn't care is a whole team is wiped out, as long as one of her other contingencies works. She's playing the odds, and spending lives like a degenerate gambler.


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

[User] [Star Wars Episode IV] Thats no moon, thats a space station theres absolutely nothing nearby to give you a size relation of how big it really is. How did they know it from that distance then?

[Assistant] It looked like Han was looking at readouts from the Falcon when he mentioned it looked like a small moon.  Im guessing the Falcon had something onboard to give relative size of incoming objects (a necessity for a starship.).  However, Obi-Wan could feel the millions of lives and weight of the dark side inside of the moon and correctly interpreted it to instead be a massive space station.


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

[User]
ELI5: How does clicking the "I'm not a robot" reCAPTCHA box confirm that I'm human?

Couldn't a spam program automatically click the box to bypass this?

[Assistant] reCAPTCHA takes account of a whole lot of information about how your cursor moves before you ever click that box.  If it looks like something a spam program might do, it throws up an extra challenge, like identifying features in images, that humans are still much better at than bots.  Things that can set it off include "teleporting" the cursor to the right location, moving it in perfectly straight lines, and similar.


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

[User]
[Avatar:TLA] Why was Long Feng so dismissive of Team Avatar's war information?

Long Feng was the power behind the Earth King's throne, running all day-to-day matters including military.  He must have been coordinating the Earth Kingdom-wide war effort, even if he didn't allow such things to be spoken aloud in the city.  So when Team Avatar appeared with information about an upcoming solar eclipse, why did he not jump at the chance to end the war?  It seems like it would've been easier to keep hold on his power without an invader knocking on his walls.

[Assistant]
If memory serves, the Earth King was under the impression that the conflict with the Fire Nation was limited to small skirmishes far from Ba Sing Se.  Mobilizing an Earth Kingdom force would have almost certainly alerted the Earth King to the fact that the War was much grander in scope than Long Feng and the Dai Li had allowed him to know.

With the King informed -- or at least suspicious -- of his advisors' deception, he likely would not have allowed them to maintain their influence and authority over day-to-day ruling.


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

[User]
ELI5:The rationale and the end game for terrorists

Omitting the Boston bombings because it's probably too soon to really grasp a full understanding of the situation. I'm not sympathizing with terrorists by any stretch of the imagination, but I don't understand what blowing up or killing a bunch of innocents accomplishes. It happens in the US few and far in between but it seems to happen pretty frequently in other parts of the world. What do these terrorist groups hope to gain? What's their end game? Why specifically do they seem to target innocents?

[Assistant]
Pretty sure you're just wanting a basic simplification, but to start here is the ELI5 Version:

A terrorist wants to scare people.  He's mad enough or crazy enough that he just doesn't care if anyone gets hurt, and he tries to find some way to hurt people so everyone else gets scared.

As for why they want to do it, well that's hard to answer and it's different for different people.  It can be that someone else who was mad tricked them into it (brainwashed), or it could be that they're just really angry about something they think is not fair.

The important thing is this, don't let them have what they want.  They want you to be afraid... afraid to go to school, or afraid to go do things with friends.  Don't let them get away with that, and don't make them famous by talking about them.

---

The laymen friendly simple version is this;

Look at 9/11... look at what happened in the US after that.  We're at each others throats over everything, the TSA checks your ass before you can travel, and we've spent ourselves into debt blowing up mud huts in a war that has made the region hate us even more than before we started.

That is the terrorists end game.  Make them scared, and make others hate them.  Break down their position.

Think of it from a swapped position... it's easier if you think about it being aliens instead of humans (because these fucks don't tend to value lives).  Alien occupation of earth, and you're fighting a losing battle.  Many humans have become complacent slaves and you're trying to shake it up and bring them down.  Now, with that view in mind, imagine different acts of terrorism that have been done.


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

[User] [Doctor who] Why is the master evil?

[Assistant] It's implied that the Master was driven insane by a constant drumbeat playing inside their head, which was put there by the Time Lords as part of a gambit to escape the Time War, and that this is why they're evil.


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

[User] [DC] why did Krypton explode?

[Assistant]
There have been numerous accounts

* A natural supernova

* Damage done to the planets core by a terrorist group using an ancient super weapon from an ancient conflict called (get this) the Clone Wars

* Over-mining of the planet

* Brainiac (or at least he gave them bad advice to ensure they wouldnt escape)


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

[User]
[Star Wars] So is this what I get when I hire a bounty hunter?

I hire Jango Fett to kill Senetor Amidala.  Jango then out-sources the job to a Changeling.  This Changeling then employs a droid who in turn delivers two venemous bugs.  What the hell am I paying for here?  I could have thrown bugs at her myself!

[Assistant] That's not how bounties work. You put a generic price on her head, then you pay the first one who brings it to you. The bounty hunters can then decide to work together and share the bounty should they so choose. You are thinking of an assassin, which neither Zam nor Jango are.


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

[User]
[Star Trek] Why is the Federation so bad at fighting the Borg?

The entire premise of the series seems to revolve around out-thinking more powerful opponents and yet the Federation seems to repeatedly use the same ineffective tactics encounter after encounter when facing the Borg.

For example, when dealing with drones they continue to use phasers in every encounter when from the very beginning it's been shown that after a couple shots the Borg adapt and render these weapons useless until they are manually "re-modulated".  Why has no one in the Federation created an "Anti-Borg" rifle?  Just off the top of my head it could include:

* Phaser with auto-remodulation
* Disrupter Ray
* Old fashioned Laser
* Kinetic rounds (conventional bullets or railgun)
* Holographic/forcefield  rounds (such as Picard's Tommy gun on the holodeck to kill two drones)
* Flame Thrower
* Bayonet

If the Borg could just be immune to everything all the time then they already would be so clearly they have to be selective about their defenses.  Putting together a multi-purpose weapon like this should render their defenses futile.

[Assistant]
Part of it really is that the Federation does not want to consider itself a military. Oh, it has the function of one, the structure of one, it is a military in most senses of the word. But 23rd Century Federation citizens want to believe that they are above such things. They hold to their ideals that Starfleet is a peacekeeping and exploratory agency primarily.

As such, development into pure weapons and dedicated anti-Borg tactics is stymied by budget restraints. The Federation feels that if they admit that they need such research, that they admitting failure. That they can't protect the galaxy with just defensive and exploratory methods.

There are plenty of things the Federation could do if they took war seriously. They don't.


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

[User] ELI5: How does a dishwasher get water into every piece despite their proximity and angles?

[Assistant] The nozzles shoot water at an angle, the angles overlap each other and the nozzles are on a rotating arm so every area is more or less covered. Pieces that may be at a weird angle will get less water but over 1h they will eventually be blasted with enough water and some pieces just dont get washed if you put enough effort into it.


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

[User]
Take a container.Fill it with birds.Weigh the container.If all the birds took flight within the container, it would still weigh the same.How?

I just saw this on QI, and even though I think it makes sense I can't really figure out why.

*edit
Asked and answered comprehensively in under ten minutes. Thanks! I was thinking the birds flying was analogous to someone jumping up, which it clearly isn't.

[Assistant]
>Take a container.Fill it with birds.Weigh the container.If all the birds took flight within the container, it would still weigh the same.

Yes\*.

>How?

For the birds to stay aloft, they must exert a downward force (via their wings pushing the air) equal to their weight.  The air presses down on the box with the same force as the birds' weight (assuming that the box is air tight) , and thus the box weighs the same.

\**The weight of the box will, in reality, fluctuate very slightly around the target weight as the birds accelerate upward on a wing beat, and then fall downward.  But then again, that's the same effect you'd see if they were all walking around instead of sitting still.*


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

[User]
Do just liquids have pH? Or do all states of matter?

I only ever see pH being talked about with liquids. Could a solid or gas have pH?

Is it just that we cant measure the pH of the other states of matter, or does a material simply lose the property of pH when it freezes or boils?

If they still have a pH, how would we measure it? And if the pH is not measurable when in a non-liquid state, can we just liquify it and then measure the pH? Does this measured pH still apply once we then freeze or boil the liquid?

[Assistant]
pH is a way of expressing the volume-based concentration of hydrogen ions, which is what gives a solution the "property" of acidity. In water, hydrogen ions are "carried" on water molecules (the resulting structure is called a hydronium ion).

At its core, pH has to do with solutions. For this reason, it isn't really meaningful to talk about the pH of gases or solids, unless they are dissolved or slurried in a liquid (in which case it's the liquid you're measuring). Even then, the liquid is pretty much always water, as it is very challenging (and again, not as meaningful) to measure pH in non-aqueous solvents.


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

[User] eli5: why do humans form blood clots on 8 hour flights, but not during 8 hours of sleep?

[Assistant]
Lower cabin pressures mean the partial pressure of oxygen you inhale is lower. So your blood is less oxygenated and that increases clotting.

Also you don't move enough on a plane (people move quite a lot while asleep in bed). So your veins are kinked at joints, slowing flow, and you don't use your large muscles very much (muscle contractions aid in the return of blood through the venous system).


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

[User] [Spinal Tap] Despite its lack of commercial success, was Smell the Glove ever considered to be a classic album?

[Assistant]
*Smell the Glove* continued Tap's long history of critical failure.  In the UK, the music press poured scorn on the album.  The NME called it "...dated, posturing, Willy waggling nonsense from a band who should have done the decent thing years ago." This was one of the more polite reviews.

Things were much the same in the USA.  One influential DJ notoriously bought every copy he could find and used them as targets at his local shooting range.

Of course, the reaction from Japan was massively different, which saved the album.


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

[User] ELI5: How are sport drinks supposed to hydrate you more than drinking water?

[Assistant] They don't. What sports drinks are supposed to do is replace minerals/salts/electrolytes (different words for the same stuff) that you may have lost during intense physical exercise. They also have sugar to replace the calories you burn during the same activity. Unless you are an elite athlete in the middle of an actual competition, you do not need a sports drink (even then, the evidence is pretty sparse that they help). A normal diet has more than enough minerals for even the most work-out obsessed individual. Even if you exclusively drink distilled water, there will be more than enough salt in your diet to keep you going.


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

[User]
[DC] Could a Green Lantern ring create a person?

Obviously it could create cars, fists, and weapons, but if Hal Jordan tried really hard enough to imagine a person, would it work?

[Assistant] A living, breathing, fully autonomous being?  no, it can't do that.  It can create constructs that LOOK like people, Kyle does this a lot, Guy too.  But the ring cannot create life, no.  Kyle once used the power of ION to reanimate his mother after she passed away, but it didn't last long.


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

[User]
[LA Noire] What exactly happened in boot camp with Cole Phelps?

There's a flashback in the game where everyone has to rate each other and then at the end of the flashback Kelso gets rated by Phelps and then he says he didn't join the corp for this school yard bullshit and storms out after having his weekend pass denied. What was that all about?

[Assistant]
They were in OCS (Officer Candidate School), not boot.  It's implied that Kelso dropped out, being fed up with "this schoolyard chickenshit" and enlisted instead (where he'd actually go through "boot camp").

Hence Phelps outranks Kelso, as Phelps completed OCS and entered as a Lieutenant, whereas Kelso chose to enlist and entered as a lowly Private.


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

[User] [LoTR] Does Aragorn have a more noble/illustrious lineage than Legolas?

[Assistant]
Possibly a matter of opinion, but I'd say so.

Legolas is of Sindaran lineage, mixed with Silvan Elves (possibly in blood, definitely in culture) which are considered less "noble" and "illustrious" than pure Sindaran.

Aragorn is descended from:

* Numenorians, perhaps as "noble" and "illustrious" as you can get with respect to Men, including one of the men who slew Sauron
* All three major branches of elves, in descending order of nobility/illustriousness: Vanyar (via Indis > Turgon> Idril> Earendil > Elros); Noldor (via Finwe > Turgon > Idril > Earendil > Elros); and Sindar (via Thingol > Luthion > Dior > Elwing> Elros).
* An actual, literal angel: Melian (wife of Thingol)

So he has some more nobler and illustrious names in his pedigree, for sure.


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

[User]
ELI5: is the way we walk genetic?

So i have noticed my cousin walks similarly of not exactly the same as my uncle. I feel like I also kinda walk like my dad. Is this just another genetic thing?

[Assistant]
The way you walk depends on things like genetics, such as leg bone length which impact stride length. Fitness, a fat person might have a waddle like walk, a fit person might not. Health, such as injuries might give a limp or other change in stride length, or how the foot lands.

If you've worn shoes most of your life or walked barefoot/sandals most of your life.

It's not really one factor.


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

[User]
Is there a conservation law associated with CPT symmetry? Shouldn't it be conservation of probability?

I've been reading a lot about symmetry lately and I can't articulate why but I feel like for there to be predictable laws that comes from an ultimately statistical (random) microscopic world, that the conservation of probability must come into play. So my ultimate question is, is there a conservation law associated with CPT symmetry?

[Assistant]
Per Noether's theorem, only *continuous* symmetries (e.g. rotations, translations, etc) give rise to conservation laws. CPT is a discrete symmetry, and so doesn't have a corresponding conservation law.

Conservation of probability is associated with the unitarity of quantum mechanics: quantum states stay normalized as a function of time. In some sense this is a 'deeper' fact than any symmetry; it's true in any quantum system regardless of how symmetric the Hamiltonian (or Lagrangian) is.


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

[User] [Community] Do other trades have secret societies attached, or are the air conditioner repairmen the only ones?

[Assistant] Air conditioner repairmen are likely unique in that regard, since  they are much more successfull than the rest of the school, with their trade school having a Job placement rate five times higher than the rest of Greendale combined and the donations by the Alumni of the Greendale Air Conditioning Repair School making up 80% of the Budget of Greendale.


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

[User] ELI5: What exactly is napalm and what makes it so notorious?

[Assistant]
It's notorious for a couple of reasons.  One is that creating a firestorm in a city is more horrible than bombing the same city with explosives: the firestorm pulls in fuel and oxygen and expands, burning many people to death.

The other thing it's notorious for is its use as an anti-personnel weapon dropped from the air.  That is, not being used to blow up buildings or tanks or munitions supplies, but specifically to burn people. It is liquid, so it can run under shelters, into tunnels, etc. It burns very hot  so you could be burnt to death even if you weren't physicaly hit with it.  And it's also sticky, so the person being burned can't scrape off the incredibly hot stuff burning through their skin.  During the Vietnam War, the US found that Vietnamese people were jumping into water to stop the burning so it was reformulated to stick to skin and continue burning under water.

^(Edit: fixed a spelling error, changed 'stock' to 'stick')


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

[User]
CMV: Burqas and Niqabs are one of the biggest oppressors of modern women

Austria, France, Belgium and now Denmark all have laws against the wearing of these garments.

My view on Burqas and Niqabs:

"It's for religious purposes" or "It helps liberate women from the male gaze"The best argument I heard for this was "Why are the burqas made of black polyester? In the middle east no less. Why can't it be a white, light weight, flowing material? Maybe cotton or silk?" Even the richest people use the same black material, so it isn't a question of wealth. The choice of material proves that the burqas exist simply to punish women for being women.

I'm living in France, but over the years I have heard of feminist movements in the U.S. like free the nipple where feminist claim that bras, or high heels are oppressive pieces of clothing even though it's pretty much the woman's choice. but for the most part, feminists won't denounce the forcing of the burqa.

In France, a lot of muslim girls say that "it's their choice to wear it", and then the feminists I know argue that it's feminist clothing  because of this "choice". My argument here is that their mother wears the burqa, their grandmothers wear the burqa, every other female in their religious circle wears the burqa. An woman not wearing the burqa would not be well accepted by their community, so yes it's their "choice", but if they choose not to wear it, then they will be punished for it by their community.

How to CMV: Convince me that burqas are not oppressing women.

edit: I shouldn't have said biggest, but I'm not sure how to reword it and still have the same meaning, I'm simply relating the burqas to western "oppressions" such as high heels, bras, and air conditioning.

[Assistant] The title and what you wrote at the end are completely different.  If its the view in the title its obviously incorrect. Stoning women for adultery, honor killings, barring them from working, going out on their own, driving, voting, holding public office, going to school are much larger problems.


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

[User] ELI5: If 3D vision is natural to humans, then why does our eyes and brain have a hard time watching extended hours of 3D entertainment? Will Holograms be any better, and more acceptable?

[Assistant] I imagine holograms will be much better. 3D presentations are still coming from a 2D screen with images projected through the 3D glasses, also affecting where your eyes attempt to focus, whereas a hologram will have a natural 3D presence. The way our eyes process images is quite complex: just think of optical illusions and that stupid black and blue dress (people who saw white and gold were somehow unable to process the over-saturation of reflected light off of the dress)


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

[User]
[MCU] What happened to Obadiah's stun tech from Iron Man 1?

In IM1, Obadiah has a handheld device that temporarily paralyses someone with some kind of ultrasonic frequency. The tech looks like it would be highly useful in a number of situations, so why did Tony never develop it further?

[Assistant]
Well Tony was busy developing the tech he cared about. Hes a genius, but hes only one man, and theres only so many fields he can develop at the same time.

Additionally, it might be the case that the range of the stun weapon couldnt be amplified, making it fairly useless for someone like Iron Man.


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

[User] Why are nuclear bombs activated above their target and not on ground impact?

[Assistant]
They can be detonated at any height, depending on what whoever planned the attack is trying to achieve. Some factors that would be considered:

**Fallout**

When a nuclear device detonates, anything within a vaporization radius of the device will be turned to vapor. The vapor of that matter will mix with the vapor of the device debris. That's how you get what's called fallout - various types of matter get mixed in with the highly radioactive device debris, get irradiated by neutron radiation, and can be transmuted into other radioactive elements. The more matter that's in that vaporization radius, the more and more dangerous fallout you get. So detonating high enough that the vaporization radius doesn't touch the ground will minimize fallout, and detonating on or right above the ground will maximize it though vaporizing all of those cubic meters of earth. In most cases, you would prefer to minimize fallout.

**Thermal Radiation**

This is non-ionizing radiation put out by the bomb, that travels in a straight line, doesn't go through things, and heats up whatever it hits. It can burn people to death, start fires, melt things, etc. If the device detonates too low, buildings and terrain may shield some of the surrounding area from thermal radiation, while a detonation high enough to be above these things will expose more things to it. You detonate low to get the maximum destruction to things very close to the detonation, and detonate higher to spread the destruction out more at the expense of a little less effect right under the bomb. Of course, even the lesser destruction from being under a higher-altitude detonation is more than enough to completely destroy most things.

**Blast wave**

This is a shock wave of outgoing high-pressure air. It tends to knock down buildings and other structures through high winds and pressure and inflict blast injuries to people. It spreads in a kind of similar way to the thermal radiation, but is more complex due to reflections, interference, air pressure at detonation altitude, and other factors. There's charts for what altitude to detonate at for various effects at various ranges.

**Physical Vaporization**

Back to the vaporization mentioned in the fallout section. The other side of that is that, if you are attacking a hardened target, like something deep underground or not very affected by heat and blast, like train tracks, etc, it may be necessary to physically vaporize the target to ensure the intended destruction. So back to a ground or near-ground detonation.

**Summary**

It all depends on exactly what you're trying to attack. Destroying a nuclear missile silo is different from destroying a military base or navy yard, which is different again from going for maximum casualties in a city, and any number of other types of targets one might want to attack.


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

[User]
I think Wikipedia is a very reliable source. CMV

When I go on Wikipedia, most of the stuff is cited and I feel as if every fact stated is backed up by a source. People say that anyone can change it, but usually, it is either blatantly obvious or quickly reverted. When I read something on Wikipedia, I automatically assume it is the truth. I understand that most of the stuff written is by mundane people, but the fact that an overwhelming amount of people have confronted me that the site has little value to knowledge absolutely astounds me. Sure, it's written by everyday people, but it has a sophisticated enough moderation to make it as truthful as possible in which I find a highly reliable source of knowledge.

[Assistant]
Sure, it's GENERALLY reliable, but what if some random guy messed it up five minutes before you look at it?

Go ahead and use it to find the population of Germany, but not for your research paper due next week.


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

[User] [Warhammer 40k] Do ships ever hit warp-entities while traveling through The Immaterium?

[Assistant]
Yep, all the time.  The Warp is full of - in some interpretations, *made* of - daemons and other horrible things.
 Fortunately, though, those warp entities cannot enter realspace without specific methods of transition, and bad things happen (to them) if they try.  Human ships use Gellar fields to create a bubble of realspace around their ships, and that bubble basically splatters daemons like bugs on a windshield as the ship moves through the Warp.

If that bubble fails, though, and you're moving through the Warp unshielded?  Well, then, the daemons and other horrible things pass right *through* your spaceship, physicality being subjective in the Warp.  And if they feel like it (inertia also being subjective) they will stop inside your spaceship, or your cerebral cortex, and hang out for a while.  Bad things happen (to you).  Eventually - if you're lucky - your body and soul will be damaged enough by those bad things that they cease to exist.  If you're unlucky?  Let's not go there.


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

[User]
[Marvel] What does fiction look like on marvel earth?

Stories about superheroes, action heroes or wizards and aliens must lose their interest when you have real life examples.

What does the average marvel earth working man go to see at the cinema?

[Assistant]
While trading cards and comics about Captain America do exist in Marvel's universe, they seem to be the exception rather then the rule.

Comics about detectives, spies, pirates, and fictionalized historical peoples like the Romans and Vikings are all ideas that could have become very popular.


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

[User]
[Stephen King's It] What forms would Pennywise take in 2014?

In *Stephen King's It* (both the novel and the miniseries), many of the monster's forms are based on pop culture figures that kids of the 1950s/1980s would be familiar with. The Teenage Werewolf, Creature From The Black Lagoon and the Mummy were familiar 1950s movie monsters. In the 1980s, it took the form of Jaws.

If Pennywise showed up in Derry today (30-something years after the end of the original story), what forms would it take to frighten its victims?

[Assistant] Pennywise didn't watch TV and go "Ah, alright, that's what the kids are afraid of." Rather, Pennywise can sense what the greatest fears of its victims are and manifests them (rather like a boggart). True, when dealing with children it often manifested in pop-culture horror icons, but not always. So if it was still around today it might take the form of Jigsaw, but it might also take the form of a pitbull or snakes or fireworks or whatever its victim is afraid of.


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

[User] ELI5: why are bank vault doors round and not rectangular like normal doors?

[Assistant] Traditionally, they work by pushing big rods into holes in the door frame. This is easiest if the rods are all the same length, which is what a circular door gets you. The circle shape also means you can't make use of stress concentrations at the corner, since there isn't one, and you can't really use a jack to force the door frame open like you could with a rectangular door, since it will just squeeze the rest of the door even tighter.


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

[User]
[Warhammer 40k] You are a relatively high up person on X World and you encounter a Purii Genestealer (and get away unscathed). What do you do to alert The Imperium, and what happens as a result of that?

So you encounter a tyranid genestealer in its purii form. It doesn't spot you, but you see it and are able to capture irrefutable proof of a genestealer infesting the planet you inhabit, be it video footage or whatever.

For the sake of argument, you are high up enough in your respective planet's government so that somebody would at least look at your evidence and not just dismiss it out of hand.

How would you go about informing the right people about the infestation, and what would happen as a result of you informing them on the following world types?

1. A Hive World

2. A Forge World

3. An Armory World

4. A Shrine World

Extra Note: You only encountered one genestealer, but you don't know how many others are on the planet or whether they have infected anybody or begun a cult yet.

[Assistant]
Citizen,

Your failure to notice a xenos infestation is a massive dereliction of duties and responsibilities as part of the ruling class. Purii Genestealers are only encountered in Space Hulks and last stages of a genestealer infestation. And genestealers are never, ***NEVER ALONE!!!***

The signs of genestealer infestations are appallingly apparent. The first outward signs would be cults growing disappropriately in size and strength, often as deviations of the Imperial Ecclesiarchy. Next would be massive riots across the planet. That your failure to report this in the annual reports reeks of heavy genestealer infiltration within the upper echelons of the planetary government. The final stage would be the sightings of purii genestealers and the jamming of all astropathic communication within the subsector. That signals the imminent arrival of a Tyranid Hive Fleet.

As of this time, an Imperial Exterminatus Fleet is prepped to purge your subsector of all biomass to deny the xenos. You will not survive to receive this message. Your heirs and descendants are stripped of all rights and property on the charges of dereliction of duty and heresy. May the Emperor have mercy on you.

The Emperor protects.

Inquisitor BuddhaFacepalmed,

Ordo Chronos.


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

[User]
[Star Wars] Why don't Jedi turn off the lightsabers of non-force users

I've been watching Clone Wars recently and it seems like there's a good few people wielding lightsabers who aren't force users. I know that Jedi can't turn off other force users lightsabers because they have a sort of 'force bubble' but could you not turn off the lightsabers of Grevious, Pre Vizsla or that guy who just happens to pick up your fallen lightsaber to cut the fight short. These people won't have a 'force bubble' so there shouldn't be anything stopping it, no?

[Assistant]
Force bubbles only ever existed in the Legends Darth Bane trilogy - nowhere else, not even in other works by the same author.

Force usage isn't easy. It takes time and effort, which isn't going to happen when you're toe to toe with someone wanting to kill you. We see Yoda deactivate and take the sabers away from Ventress in an early TCW S1 episode, but that was before she actually moved in to attack.


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

[User] ELI5:How can rich people maintain their lifestyle after bankruptcy ?

[Assistant]
There are certain assets that you can't be forced to give up in bankruptcy, so even after you've gone bankrupt, you may still own a lot of valuable things. The exact list varies from state to state, but generally includes your house, if it's your primary residence, one car, and professional tools you may own, etc. In Texas, it includes a fairly substantial herd of livestock.

And, anyway, depending on the reason you went bankrupt, you may still have a well-paying job, or the opportunity of finding one.


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

[User]
With our current capabilities, would we be able to tell that our own system contained a habitable planet if we were a number of light years away? From how far out would be be able to identify this?

What would we be able to tell about our own system and its planets if we were in another system? Would we be able to identify the number of planets or would we only see the effects of the gas giants?

[Assistant]
This has been the subject of multiple spacecraft investigations.

Both the Galileo mission and the EPOXI mission observed Earth to determine if they could detect signatures of life from only spectra of our planet to determine its chemical make up.

A few things stand out strongly among those:

- Free Oxygen in the atmosphere. It's very rare to find this, since oxygen is incredibly reactive with just about everything. One would expect it to quickly decay, but the abundance in our atmosphere suggests some very interesting process must be producing it.

- Free Methane in our atmosphere. Methane on its own isn't all that uncommon (the outer planets all have a good deal) but it simply shouldn't exist in the presence of free oxygen without some process actively producing it to keep the planet in "chemical disequilibrium".

- The Red Edge. Chlorophyll produces a distinct spectral feature in the red part of the spectrum. This isn't the strongest signature of life (other chemicals can produce similar features), but when combined with free oxygen, is a very strong indicator of plant life.

The red edge is probably the easiest feature to detect, but also the weakest evidence of life of the three. Exoplanet spectra are pretty ratty right now, and generally not good enough to pick up anything but the red edge (particularly for Earth-sized planets), but give it 10-15 years. Once the James Webb Space Telescope and the ELT come online, we should be able to pick up more of these definitive spectral features on exoplanets at least a few hundred light-years away.


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

[User]
[The Endless Universe] What is Dust, anyways?

We all know that the golden Dust is all important and very, very useful.  But what is it?  I tried asking but I can't get a straight answer out of anyone.

It doesn't seem to be nanines.  I mean, it generates its own power!  And if you ingest it, you apparently either die or get super-powers...

[Assistant] It's a combination of zero point energy matrix, programmable matter and computer. It's basically the pinnacle of technology, a singular creation capable of generating limitless energy, and being shaped into any form for any purpose.


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

[User] (ELI5) Why does honey never spoil?

[Assistant] It is so high in sugar that organisms don't have enough moisture to live. The sugar is hydrophilic and will suck the water out of bacteria that encounter it. Basically the same idea behind salting meat, except that uses salt of course.


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

[User]
[Futurama] Why does Bender wear clothing while a fembot?

Most fembots and manbots wear nothing at all, yet people object to fembot Bender taking off her shirt?

[Assistant]
According to the censors at the Box Network, regulation 3.74:

     It is lewd and lascivious for a female to unclothe her upper torso on television.

But there are no regulations stating that a robot cannot be unclothed on television.  The result: robots can be naked on TV, but female robots cannot remove their shirts.

This is technically correct.   The best kind of correct.

*Addendum: the executives responsible for this clusterf@#$ have been killed and ground into Torgo's Executive Powder.


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

[User]
[Squid Game] Question about a certain game. *Spoilers*

Why did the old man let the protagonist win the marble game?

If the old man had been forced to pick another partner, would the old man have also let the other person win?

[Assistant] a few reasons. the first is that he actually liked the protagonist and wanted him to win the most so he threw the game. the second is that the next few games would have been far too dangerous for the old man to play and he had to throw the game anyway since those next games would have killed him.


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

[User] ELI5: Why do gif files take so much longer to load than everything else on the internet?

[Assistant]
A gif is a bunch of picture files that it shows in order, like a flip book.  So for a gif, imagine all those pictures stacked on top of each other.  It's a pretty big stack, right?  Your computer needs to download all those pictures - one for each frame of the gif.

A video doesn't take up as much file space.  Each frame of a video isn't a whole picture.  You start with a whole picture, and instead of having another whole picture for the next frame, the video file only keeps track of what has *changed* about the picture.  So moving from frame to frame, the video file only needs to store the information of what has changed from each frame to the next.  You don't need a stack of whole pictures, just a bunch of snippets of each one, so the file sizes aren't as big.


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

[User]
Is it better to blast my car A/C and then turn it off, or let it run at a higher temperature continuously?

In terms of energy usage, which is more efficient?  Say I turned the temperature on my car A/C all the way to its lowest setting and blasted it until it was chilly, then turned it off, and repeated this. Would that be more or less efficient than leaving it at a higher (but comfortable) temperature and letting it run continuously?

[Assistant] Car air conditioners have one temperature setting; only the fan speed changes. The most efficient way to cool down your car is to turn the fan up (the difference in energy consumption between speeds is negligible in the short term) and recirculate the air in the cabin.


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

[User]
[Fallout] What are East Coast caps backed by?

West Coast caps used to be backed by water, NCR dollars are backed by gold, so what exactly makes caps valuable on the East Coast? Why would people suddenly start using bottle caps rather than normal money? I get why caps are a suitable currency, but what *makes* them currency rather than something else? What got them in circulation in the first place?

[Assistant]
Hard to say as factions come and go. I'll have a guess on what little we know.

We know a Nuka-Cola machine was on every street corner in the Capital before the war, making them widely available to all groups no matter how scattered. This maybe why they adopted them.

Rivet City, Megaton and Underworld were the only real influential groups before the Brotherhood of Steel arrived and it seems they mostly kept to themselves but trading caravans suggest they adopted bottlecaps as their currency.

The Brotherhood arrives in 2255 and become the dominant force in the region, being the only ones capable of pushing the Super Mutants back. Since they come from the West where bottlecaps are the universal currency they may have forced its usage on the locals.

The cost to repair something on the East Coast is a lot lower than on the West Coast which means it is relatively newly adopted and prices are sketchy at best, that bottlecaps in the East are regulated better or there are just less to go around.

It is really hard to say but difficulty to replicate and enough to go around makes an ideal currency.


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

[User]
eli5, what is in our spit that can break oil apart?

If I were cooking and got butter on my finger and then try to wash it off, the butter just spreads around.
But if I were to lick or suck the butter off my finger, it's gone immediately without a trace. Why? Is it something in our spit? Or is the surface of our tongue? Both? Thanks!

[Assistant]
Saliva contains enzymes like amylase and lipase. These enzymes act a lot like soap. One side of the molecule attaches to the oil molecule and the other is attracted to water allowing oil to be broken up in water more easily. Aka as emulsification.

Fun fact: some conservators (painting restorers) use artificial human saliva as a cleaning agent to remove the grime on some paintings.


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

[User]
How scientifically legitimate is commercial DNA testing to identify ethnicity? 'biology'

There have been many different sites over the past few years claiming that they can do anything from determining if you are related to this or that famous person (which to me personally seems absurdly improbable) to determining your ancestry more broadly in terms of ethnicity and a general background.

I'd like to hear from a few geneticists, biologists or any related field on how credible sites like 23andme are and their accuracy when it comes to identifying your ancestors' background, their ethnicity and possibly even their nationality.

Thank you in advance.

[Assistant]
Most are actually pretty accurate.

There are a lot of bases in human DNA (around 3 billion), but most of those are invariant. That is to say, in every person whose DNA we've looked at, they have the same base at that position. After decades of examining the human genome, we have a pretty good idea of which bases are invariant, and which ones have variants.

The next part is to figure out if certain variant sites reflect human ancestry. Let's say most humans have a region that reads ' ATCG', but some have 'AACG'. That second base is the variant site we're interested in. If it turns out that all pacific islanders have the 'A', while everyone else has 'T'. Than this site can be associated with heritage from the pacific islands.

We have now examined enough genomes from most ethnic backgrounds (excluding North American first nations) that we have a large number of variant sites associated with each ethnicity.

A company like 23&me will determine what variants you have and then give you a breakdown of ancestry based on those. So being 20% Irish means that of the variant sites that they looked at in your genome, 20% of the variants that are associated with ancestry (instead of say disease) have strong associations with Irish peoples.


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

[User] When I scratch at a pimple on my shoulder, why do I feel pain simultaneously both around the pimple and at a seemingly random spot on my lower back?

[Assistant]
The nerves in your body run in long strands that connect up to the spinal cord at each vertebrae.  The manner in which these nerves are connected together is kind of like the branches of a elm tree, they are connected to a central trunk (the spinal cord) and they branch off into various directions to cover your entire body.

When you are scratching your shoulder pimple, you are activating a twig that connects to a main branch.  That branch is *mostly* associated with your lower back.  Your brain recognizes that there is a signal coming from your lower back branch and does it's best to interpret that signal.  So the "pain" you feel is not due to an external stimuli on your lower back, but from you brain making its best guess about the errant signal coming from your shoulder.


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

[User]
[Star Trek] Why is Starfleet so Earthocentric?

Earth was not the first planet to achieve warp speed, nor do they have the best track record, having only been able to achieve planetary unity and peace after a a war (and that's only because Cochrine happened to be spotted by a Vulcan vessel/

And yet, Starfleet th have its own special fleet. or do they consider Starfleet to be their fleet?

[Assistant]
tl:dr - Earth proved it was very good at this whole space thing and Starfleet started as a necessity and then nobody saw the need for a change.

Starfleet is the official fleet of the Federation, but each planet within the Federation is allowed to maintain its own ships. Earth may not have been the first to achieve warp travel, but by God were the fastest. Within 90 years they had achieved warp 5, something other species had taken hundreds of years to develop. Most planets had very similar histories to Earth, especially Vulcan but the difference was the time between events. On Vulcan it was a thousand years since their Wars, not 15 like on Earth. This showed that Earth was very good at sustaining itself and had the initiative and drive to expand quickly, something other nations lacked, they saw this when creating the Federation.

Earth was a unifying planet, and very peaceful nation comparatively. There was much in fighting between the future founding planets of the Federation, including Wars between Vulcan and Andor, and disputes between Andor and Tellar. These would eventually be solved by Earth, settling most major disputes (thanks mainly to the Enterprise, NX-01) and eventually uniting them. This meant that many of these other worlds put their faith and resources into Earth rather than another planet they may have had a falling out with in the past (Earth was the only planet on very good terms with all the other planets, and therefore the best mediator in their eyes). At first this was a necessity, to avoid any long standing bad feelings from bubbling up, but over time it just became the norm. Humans too were one of the few species that liked to settle on other planets a lot and explore, meaning that a large portion of the Federation was human colonies. This gave them a large presence in the Federation.


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

[User] ELI5: How come sometimes when you pop a pimple it hurts SOO bad for like ten seconds and other times it doesn't hurt at all?

[Assistant]
Dependent on a lot of things.

One usual cause is that nerves are not distributed evenly across the skin. So you can literally stick a needle into your skin and not feel it at all while a centimeter away the same needle will be painful. Maybe there are no nerves at the pimple location.

Another is that the nerves in one location may not be exposed in the pus and/or you may avoid pressuring them by random chance. So you can pop a pimple but if there's no exposed nerve it's not going to hurt(as much).


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

[User]
[Children Of Men] What was it like at the beginning?

There's a photograph of Jasper in 2010 receiving a political cartoonist award, so they were still having awards at the beginning of the infertility crisis.

Were the first five or so years of the crisis fairly normal, then? Were people a little worried, but "Oh, the scientists will fix it"?

At what point did things go from "this is bad, I guess" to what society is like in the movie?

[Assistant]
At first, there was utter panic, possibly even approaching the kind seen in the film. People took it as a clear sign that whatever eschatology they believed in was about to come to pass. But when God did not descend from the heavens to pass final judgement, the first year of chaos came to an end.

By the times they were starting to mass close schools, conditions began a steady degeneration. Like the Great Depression, except without a principally economic source and without any possible cure but the obvious.

After ten or so years, people began to believe that there would never be a solution. This is where the nations of the world began settling their last vendettas while they still could. Societies began collapsing around here. Nukes probably came out.


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

[User]
Why do chewing gums that have their main ingredient as sugar/corn syrup still include Aspartame in their recipe?

I've noticed this in a few products, but the one I have in front of me is Big League Chew...

- Sugar
- Gum Base
- Corn Syrup
- Glycerol
- Natural and artificial flavors
- Soy lethicin
- Acesulfame-Potassium
- Aspartame
- BHT
- Corn Starch, Color (Allura Red)

Wouldn't the sugar and corn syrup sweeten it enough? Is there a preservative reason, or some other chemistry issue?

Edit: I wasn't sure if this should be tagged as Biology or Chemistry. I settled on Biology since it involved taste. Hope that's ok.

[Assistant]
Here's a quotation from Wrigley on the subject:

The Wrigley Company utilises the high intensity sweetener, Aspartame,
in a number of its products - as the primary sweetener in some of our
sugarfree brands and as a flavour enhancer in some of our sugar-sweetened brands. As an ingredient, Aspartame has the added benefit of
providing an especially long-lasting flavour.


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

[User]
[Lilo and Stitch] What exactly is Stitch?

Jumba mentions several things about Stitch that got me thinking about what exactly it is. He mentions how Stitch is a new species but also mentions how he has programming. Is Stitch like an animal, a robot, something in the middle?

[Assistant] He's a genetically engineered life form, like the other 625 experiments. We don't know Jumba's exact procedure, or if Stitch is analogous to any other kinds of extraterrestrial life, but he was most likely artificially grown somehow and is completely organic.


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

[User] [Marvel] What would happen if Wolverine's skeleton was coated in vibranium instead of adamantiam?

[Assistant]
His healing factor would be significantly stronger.
Comparable to, if not greater than Deadpool's.
In an alt universe where he has no Adamantium, his increased healing factor mutated him into a monstrous animal like creature.

He would be unincappable.
Usually, the way he's defeated is by knocking him out, but with a vibranium skull, that ain't happening.

His skeleton would eventually be completely bone again.
Vibranium is significantly less durable than Adamantium, and bullets, impacts and cuts would tear, shatter and bend the metal. Perhaps in decades, most of the coating would have been torn off.

His claws wouldn't be as sharp.
They'd also deteriorate pretty fast, as he uses them to slash at metal extremely often.


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

[User]
[Lord of the Rings] From the perspective of Sauron, was he the good guy?

Evil and good is all about morals and perspective. Could Sauron possibly be good? Taking out the fact that in a way he wanted to control the entirety of Middle Earth, but dont most kings control whatever land they own? To an orc couldnt he possibly be a savior? I personally dont recall many times when characters in the story exactly said what made Sauron so evil. He restored their lives, gave them jobs and a purpose. The orcs are a mistreated race in Middle Earth, he technically saved them, giving them promise of their own land and county. He was forward thinking and industrialized Middle Earth. Honestly it was just another war for territory and power. They often spoke about fighting for their freedom, but does freedom actually exist? They live in a land full of monarchies. All of them were fighting over the same thing. Land, power and a prosperous future. Granted Sauron had a few shady tactics, but its a war. When talking about which age we were in class we established that we might be in the 5th or 6th age. When you think about it Sauron was more or a 5th/6th age man. Trying to gain land, and making weapons. He had a lot of forward thinking going on. So what exactly made Sauron so evil?

[Assistant]
>Taking out the fact that in a way he wanted to control the entirety of Middle Earth, but dont most kings control whatever land they own?

These are two different statements. He doesn't own the entirety of Middle Earth, so controlling is done through conquering it.

Sauron doesn't care about the orcs, they're tools to him. I'll use this wonderful passage about the usefulness of Shelob:

"And as for Sauron: he knew where she lurked. It pleased him that she should dwell there hungry but unabated in malice, a more sure watch upon that ancient path into his land than any other that his skill could have devised. And Orcs, they were useful slaves, but he had them in plenty. If now and again Shelob caught them to stay her appetite, she was welcome: he could spare them. And sometimes as a man may cast a dainty to his cat (his cat he calls her, but she owns him not) Sauron would send her prisoners that he had no better uses for: he would have them driven into her hole, and report brought back to him of the play she made."

>Granted Sauron had a few shady tactics

"A few shady tactics" is really underselling it. The guy came to the different races representing the gods, and acting like you give them a gift in an attempt to let every race destroy themselves from the inside until you can control them completely.

The industrialisation you speak of is used for nothing but war. We don't see any technology that houses orcs, feeds them, or improves their quality of life. We see explosives and battering rams.

Sauron had good intentions in the beginning. Above all else, he values order. He values order so much that his ideal world involves no free will with everyone bowing down to him. There's no endgame, no plans for what he will do to improve the world once he's taken it all. The only thing on his mind is conquest.

If you believe not caring about your own people, intentionally letting a giant spider snack on them so you have a pet guardian and to inspire fear among your people, killing mercilessly, conquering for the sake of conquering, and doing your best to erase the very concept of free will in favor of your own definition of order are all perfectly acceptable, then no, Sauron wasn't evil.


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

[User] Which is brighter, a full moon from earth or a full earth from the moon?

[Assistant]
* Moon albedo: 0.12
* Earth albedo: 0.37

.

* Moon angular diameter from Earth: 0.5
* Earth angular diameter from Moon: 1.8

So Earth is both bigger in the sky and more reflective. Earth is brighter.

    (1.8/0.5)^2 * (.37/.12) = 40

By a factor 40.

Edit: bullet lists.


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

[User]
[Batman] What happens to Batman when he succeeds?

Assume crime in Gotham is reduced to nominal levels.  (Cant eliminate every crime, but levels *can* be reduced.)  Batmans rogue gallery is entirely incarcerated, dead, or reformed.  Justice is the order of the day over corruption in the government.

What happens to Batman?  Does he finally get to retire and become Bruce Wayne again?  Or does his obsession simply move to a larger and larger scale?

[Assistant]
Several iterations of Batman retire for one reason or the other. Sometimes, like in the Nolan-verse, it's because he's completed his mission and saved Gotham from crime and corruption.

Usually when Bruce is done being Batman he quietly retires and keeps a very private life outside the public eye. That's one of the two constants when Bruce stops being Batman.

The other is that he remains vigilant, and isn't just ready to return to action as Batman, but to pass the cowl on to a new generation of crime fighters.

With the introduction of Batman Inc., it does seem like, having saved Gotham, he's is ready to expand the Batman brand to the rest of the world. However Batman Inc. appears after Final Crisis and the Death of Bruce Wayne, which puts it relatively late into Batman's life. This is a period where not only has Batman succeeded in his goal of saving Gotham, but he's also getting older and his body probably isn't going to keep being able to be Batman much longer. Batman Inc. is really just another way for an aging Batman to pass the cowl on to the next generation.


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

[User]
ELI5: What exactly are astronauts doing on the ISS? How does data sent down yesterday differ from data sent down today?

I'm not insinuating the science aboard the ISS is pointless, but I don't understand the meaning. What are some of the massive breakthroughs that happened on the ISS? Are we expecting more breakthroughs?

[Assistant]
during the course of science.  90% of the time, it's monotonus running an experiment, daily or hourly monitoring and collecting data points, rerunning the experiment many times for confirmation.   hypothesis.  create a new experiment,  run a new experiment, repeat and repeat until budget is done and hopefully you've come up with a conclusion that's worthy of getting the next grant.

it's not the just astronauts on the ISS making new things.  it's also the hundreds of thousands of scientists and engineers on Earth that contribute to the breakthrough's.

astronauts on ISS aren't the ones making the new solar panels.  they're just using them and reporting the findings.   astronauts on the ISS aren't the ones making fuel cells.


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

[User]
What makes elements have more or less density?

How come osmium is the densest known element while other elements have a higher atomic number and mass? Does it have to do with the Higgs boson particle?

[Assistant]
No, it has to do with the crystal lattice that the atoms form, which in turn depends on the interatomic attraction. Osmium forms a hexagonally close packed lattice (atoms arranged like stacked oranges), which is mathematically the densest packing of spheres (tied with face-centered cubic). Uranium, a bigger atom than osmium, has an orthorhombic structure (atoms arranged like a rectangular prism, essentially), which allows more empty space between them.

There are other considerations that factor into the distance between the atoms in the lattice.


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

[User]
[Star Wars] Spoiler Rogue One question.

Why was Grand Moff Tarkin so skeptical of Director Krennic's belief in the power/effectiveness of the Death Star? The Death Star's construction began years before 0 BBY under the eyes of both the Emperor and Darth Vader. If they weren't skeptical, why would Moff be?

[Assistant] It wasn't so much that Tarkin was skeptical.  It had more to do with him *appearing* to be skeptical in order to do political maneuvering in the background for his own benefit.  We see the fruition of his machinations when he orders the destruction of the Imperial base on Scarf.


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

[User] ELI5: Could we find pi as a rational number if we had a different number system?

[Assistant]
I think people are missing the point of the question. It's not "can you write pi in such a way that it terminates," it's "can pi be a rational number." Those are two different things.

Irrationality is not defined as "the number doesn't terminate." That's a property that irrational numbers have when you write numbers in an integer base, but it's not what makes a number irrational. There are plenty (an infinite number) of rational numbers that don't terminate. An irrational number is a number that cannot be expressed as a ratio of two integers (whole numbers).

Writing pi in base pi makes it "look like" a rational number, but it doesn't have the same properties as one. It's still not a ratio of two integers: the set of integers does not change when you use a different number base.


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

[User]
What is the phenomenon behind the arrangement of the large North American lakes?

I was looking at a map of North America and noticed in addition to the more recognizable Great Lakes, you can draw a sort of line/curve all the way from the great bear lake in the northwest of Canada all the way to Lake Ontario, including all the major lakes in between. Not only can you draw this curve, it also aligns somewhat with the Canadian Shield. Is this coincidence or was there some prehistoric geological process that caused these lakes to align this way?

[Assistant] You're seeing the geologic boundary between the hard ancient rocks of the Canadian Shield and the soft rocks of the Prairies. Glaciers coming off the Shield had a much easier time cutting through the softer rocks, so they cut deep grooves into it. Later those grooves fill up and become lakes.