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

[User]
If actual temp is above freezing, but windchill is below freezing, will water freeze?

I once heard that "windchill cannot create ice."

If it is 35 degree f outside, and the weatherman comes on and says "35 today, but with windchill, it will feel like 30!"

If it 'feels like' 30 to me, wouldn't it 'feel like' 30 to water? And wouldn't that water, upon feeling like it was 30 degrees, pretty much say to itself "that's my cue," and freeze?

[Assistant]
This is actually kind of a dodgy question. The answer is that yes, the wind can cause water to freeze in these conditions, but not directly because of windchill.

Windchill only describes what happens to warm dry objects like people. If something is cold and dry, then windchill has no effect. It doesn't change the air temperature.

For wet objects, it is more complicated. Evaporation of the water requires energy, and this lowers the temperature. The lowest temperature a wet object can reach is called the "wet-bulb temperature". This can be several degrees lower than the "dry-bulb temperature", depending on humidity. If the wet-bulb is below 0C, then freezing is possible.

Now in order for a wet object to get close to the wet-bulb temperature, there needs to be some convection to take the evaporated water away: There needs to be some wind.

So the wind can cause freezing under the right conditions, but it's not correct to say that this is because of "windchill".

*edit*: Just to point out that you can't neglect heat lost by radiation here. This is an important way that the ground/water can cool far below the air temperature.


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

[User] ELI5: Why is pubic hair generally more coarse and curly than the hair on your head?

[Assistant] We evolved to keep our pubic hair even after we lost most other body hair because it provides more surface area for pheromones to disperse into the air. So, it makes sense that the hair would be curly and coarse--more surface area in a smaller area.


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

[User]
ELI5: What exactly causes paranoia?

Why do we fixate over irrational things and what makes the body react the way it does when we do fixate... (ie. loss of sleep/appetite/concentration)
Maybe if I knew what caused it, I could learn to switch off.

EDIT - Before this goes all weed-based on my ass, that wasn't all I was going for. I meant paranoia in general.

[Assistant]
Paranoia and Panic Attacks are reactions to stress or unbalanced brain chemistry.
Essentially your body is reacting to stress like it did when our ancestors were living in trees and caves.  You get a dump of adrenalin and other hormones to help you focus and discern danger.  With no physical danger, those chemicals start your mind racing and you're trapped thinking about that guy who gave you the stink eye at the mall and rehashing every conversation blunder you've ever made.


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

[User]
[Deadpool] Are Deadpool's sperm immortal?

If you sampled local waterways would you find them swimming freely from years of being dumped into the sewage system?

[Assistant] Isn't the explanation for Deadpool's healing factor is that his cells are constantly dividing and replacing cells that are damaged by injury or cancer? Because if so, individual sperm cells wouldn't be affected.


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

[User]
[Stranger Things] How are people represented in the Upside-Down?

Seeing how the Upside-Down is a mirror of our reality, and we build things step by step in our reality, how would it look to see a construction project in the Upside-Down? Would girders and such just move into place on their own, or are there avatars building it? What about cars moving from place to place? Do they just do that on their own?

[Assistant] I saw a comment elsewhere that ties structure in the Upside-Down to permanence in the Rightside-Up, and that it will 'update' when it is not being observed to reflect changes. This is why you can see relatively static items like signs and cars, but not animate objects like people.


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

[User]
Have you ever wondered about a practice in STEM/the Humanities and wanted to ask?

I am TT faculty in the Humanities. I have a stunning level of ignorance about how scholars in STEM go about their professional lives. In every school I've attended or worked STEM and Humanities faculties rarely interact with each other, which means that we've often misunderstood conventional practices on the other side of campus. My ignorance is exacerbated by the fact that some practices are perfectly normal for STEM faculty, but considered unusual (or even shocking) to Humanities faculty--e.g. willingly paying a fee to publish in an academic journal.

I wonder if anybody else here is also curious about how things work on the other side of campus? Can we make some space here for asking questions we fear might otherwise sound dumb? Can we include the caveat that despite the diversity of opinion in every field and discipline, there do tend to be institutional norms?

For example, I've always wondered how STEM scholars feel about the multiple-author publication system. How often do people undeservedly end up on the author list? Is it common enough that you have strategies for recognizing who did the real work on the project? Do you agree that someone who runs a lab should get credit for a project even if they had no direct involvement whatsoever?

I'm hoping people might chime in with their questions too. I am happy to try and answer questions about practices in the Humanities.

EDIT: Another sign of my ignorance: I mean to include social scientists in this conversation as well.

[Assistant] (Just as an aside... there are humanistic people who actually study these things. The fields of anthropology of science and sociology of science are essentially humanists and social scientists studying how scientists work. Latour's _Laboratory Life_ and _Science in Action_ are great places to start...)


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

[User]
Do Sociopaths Have Empathetic Yawns?

This isn't wordplay, here.

I've heard that when a person yawns shortly after someone else... It can be empathy causing that.

To what extent does a sociopath experience the inability to empathize with others?

Is this purely a barrier of emotions, or does it extend to nuances such as yawning?

Moreso in scenarios like what I've described.

[Assistant] Empathy can be broken down to a cognitive and affective component which are processed by two largely independent neural networks. Deficits for sociopaths typically arise in affective empathy; 'feeling' the associated emotion for the situation. Yawn contagion is theorized to be one of the simplest forms of cognitive empathy and is processed by the mirror neuron networks. Therefore, sociopaths have yawn contagion in tact but deficits in empathy arise when it involves generating the associated emotion with the cognitive appraisal of an event.


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

[User]
Just how dark is deep space?

In scifi we always seem to see space as a place where you can see the ship a mile away just fine. If theres no sun or if the sun is really far away how dark would it be? Would it be like being in a cave?

[Assistant]
I believe It all comes down to the angle of light hitting it and being reflected to your eye, and the amount of light that is being reflected really.

In sci-fi, we'll see a spacecraft in detail because that's what the audience is expecting but, more than likely, in deep space with a vast amount of distance to the nearest star you probably wouldn't be seeing much.

However, the same goes for a moon-sized spaceship that is sitting in the earth's shadow in our own solar system. If there's little/no light hitting it that is reflected to your eye then it's effectively invisible to us.

The point being, while all objects do emit light (usually in the infrared; Google black body radiation) it becomes increasingly difficult to see reflected light from a small source point, onto a small object, that you are well distanced from. Maybe if you plan on venturing into deep space you should bring a floodlight or two?


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

[User] ELI5 If electric cars use precious metals that require extensive mining and disruption to that environment, why are the better than gasoline powered cars?

[Assistant] Building a car is a one-time investment. Running a car is a continuous investment. Current research puts the breakeven point at around 4 years of usage for electric vehicles; at that point, the amount of pollution saved by being electric instead of gas overcomes the additional pollution from the mining/processing of the rarer materials for the construction.


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

[User]
ELI5: Why isn't electric motorcycles that big of a thing?

I've read somewhere that the only significant difference between conventional motorcycles and electric ones are that one uses gas and the other uses batteries. What are the drawbacks as to why people don't entertain the idea of electric motorcycles much? I think it's got something to do with the mileage and business but I feel there's more that I'm missing.

[Assistant] The biggest problem is with mileage. Electric cars have *massive* batteries in order to have reasonable mileage. A motorcycle, even with the much lighter body, would only have a range of about 50 miles at best with a battery the size of the existing fuel tank. Anything bigger would greatly change the aesthetics of the bike.


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

[User]
[Harry Potter] Why did Dumbledore act surprised at the revelation of a Horcrux?

In the Half Blood Prince, after viewing Slughorn's memory, Dumbledore and Harry realize Voldemort used Horcruxes. And that's when they just found out what it was. So why did Dumbledore "raise" Harry for all those years, to have him die at the right time, if Dumbledore didn't even know what a Horcrux was all those years ago?

[Assistant]
It was confirmation that Voldemort was planning on Using Horcruxes at that age already, and that he wanted to make more.

They at that point had taken down 2 already, but didn't know how many there would be. During the conversation with Slughorn Tom specified 7 would be the magical(?) number.


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

[User]
ELI5: Why are new devices batteries never empty but precharged, even if they probably been stored in a warehouse for a long time?

Edit: I want to know why the battery probably lasts longer than I experience with devices I know (turned off).

[Assistant] Lithium batteries are most stable at their "storage voltage", which varies a bit depending on the cell, but tends to be equivalent to about half charge. Having a higher or lower voltage than that would make them more of a hazard, so that's what they are stored at, and subsequently what they are shipped to you at. In short, to prevent fire risk and to prevent the battery from being dead on arrival.


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

[User]
ELI5:Why are 911 calls, when played back, always in such low quality?

I mean without subs, I wouldn't understand half of what they were saying..

[Assistant] When you have something like the 911 call system, something that lives depend on, and something that you know works as it is right now, you DO NOT fuck with it. That means if the recording component makes it a little grainy, you live with it.


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

[User]
CMV - Pope Francis is overrated

I believe that much of the praise for Pope Francis only exists because people are desperate and have lowered their standards for a new pope (rather than letting the pope meet their standards).

Basically, it's all relative.  Francis is wayyyy better than most of the Catholic popes probably.  But when it comes to what our standards should be, he's average-at-best.  Basic human compassion, humility, and kindness aren't praiseworthy traits because that is what a pope is supposed to be.

Lastly, he really isn't doing anything aside from talk and nice gestures.  Yes, he's expressing compassion toward gay people and he's not speaking much on abortion, but he's still not making any actual reforms to the church.  He still hasn't addressed the corruption and pedophilia, for example.

I'm just afraid that people will come to accept the catholic church's worst flaws so long as the guy heading it is decent and can downplay the controversy.

[Assistant]
>Francis is wayyyy better than most of the Catholic popes probably.

Is that not the most valid point of comparison when 'rating' a pope? At least the *recent* popes?

Most other religions do not have single leaders that would make fair comparisons.


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

[User] To what extent does using plastic cooking implements (both spatulas, spoons etc and Teflon pans) increase dietary exposure to microplastics?

[Assistant] When you eat from a plastic container you abrade it and injest particles, but these particles.are fairly large, say 10um to 1 mm. They are far too large to cross cellular membranes, and pretty inert, so they should just pass on through. The more serious issue is plastic nano particles which are 1nm to 1um and are formed from repeated abrasion of micro plastics. These can be systemically absorbed. Effects are still largely unknown.


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

[User] ELI5:Why can Energizer only utilize 4% recycled batteries for their new ecoadvanced batteries and what has happened to all of the other batteries I have went out of my way to "recycle" over the years?

[Assistant] Not sure if recycling is the goal.   Batteries are a form of hazardous waste.  Separating them out of your normal trash and turning them into a recycle center allows the waste handlers to treat them separately, isolate them from normal less hazardous trash and dispose of them properly.


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

[User]
[DC Comics-Injustice] How would Batman have reacted if he were the one tricked into killing someone instead of Superman?

Like if he accidentally killed Dick or Jason, and the dead mans switch destroyed Gotham.

What (if anything) would he try differently?

[Assistant]
The big issue is finding Batman an opponent he's willing to kill or seriously harm, and that is hard. It worked on Superman because Doomsday would have been fine in space, but Lois not so much. Joker would need to find an opponent for Batman that would normally take an ungodly amount of punishment, but would kill a normal person outright. Maybe Bane or Clayface. So here's the setup: Joker infuses Batman with the fear gas and makes dear old Alfred into Bane. Batman fights Bane pretty hard and uses explosive grenades to 'stun' him. Unfortunately, Alfred doesn't have the resistance to survive this and he perishes. The detonation of Gotham occured, and luckily his home is just barely outside the death zone.

Bats figures out pretty quickly who did this, and finds Joker laughing his ass off. Batman realizes that the game has irrevocably changed now, and there isn't a choice. He tackles Joker and strangles the life out of him. The Justice League finally find where they are, with Bats sprawled over the still smiling body. They go to comfort Bruce, but he just stands up, and asks to be taken into custody. They honor his wishes, and soon he is to be incarcerated, though much of the world is against his sentence as they feel he was in his rights.
Alone, awaiting trial, Bruce looks up from his cell and cracks a smile, and a small but steadily growing laugh escapes his lips.


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

[User]
ELI5: Existentialism

Every time I attempt to learn more about this, I become more confused.

[Assistant] Basically it is the idea that the meaning of life is something every individual needs to discover for themselves, rather than the idea that there is a higher power dictating a meaning for our lives.


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

[User] [No Country For Old Men] Suppose Llewelyn Moss had immediately removed the tracker from the bag of money - how would Anton Chigurh have gone about finding him?

[Assistant]
You ever see the Sean Bean, Chris Hemsworth movie "Cash"? That's how.

First hit up the local car dealerships, electronics and jewelry stores etc. Go to places where people buy expensive things and ask around for someone unusual spending lots and paying cash. Interrogate or steal receipts as necessary. Narrow it down that way till you find him.

Most criminals are idiots who think once you've physically got the money away you've gotten away with the crime. They don't realise that they most often get caught afterwards through big spending bringing them attention.


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

[User]
ELI5: How does increasing wages of service workers contributes to inflation if no new money is being printed but just being redistributed.

Edit: Basically what Ive learned is that this can't be explained simply lol. But I understand that it can potentially increase demand for certain basic needs.

[Assistant]
inflation doesnt necessarily have anything to do with the amount of money printed.

instead it is calculated by comparing the prices for various goods and services.

if you increase the wages the workers providing those goods get, those goods most likely get more expensive, thus by definition inflation increases.


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

[User]
[Cars] Was there a Car WWII, and a Car Hitler?

I mean, you see Volkswagons and what not, and the Nazis invented the Volkswagon.

Was there a Car Hitler?

A Car WWII?

[Assistant]
Cars 2 confirms that human cities, countries and religions exist pretty much unchanged in the Carsverse, showing that this is an alternate earth rather then a postapocalyptic world. Indeed, we see a direct one-to-one analogue (Queen Elizabeth the Second, with initials and date of coronation to confirm it).As such, presumably history stayed pretty much the same except that everyone was cars.

So to answer your question,  yeah,  yeah there was. Also a car slave trade, car genocide of the Native Americans, car bombings of Hiroshima and Nagasaki, car Charles Manson, car 9/11, car sacking of Jerusalem, and car versions of every other historical atrocity. All happened in the Carverse.

Pixar, why don't you make a film about those, you *cowards?*


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

[User] ELI5: What causes someone to look pale or lose their color when sick?

[Assistant] A lot of blood which is normally distributed equally throughout the body is being sent to your vital organs. For example, if someone is experiencing stomach pains and become pale and weak, their blood is being sent to the stomach organs to help heal the illness.


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

[User] [Spider-Man] Does Spider-Man do fast physics in his head when swinging (as he says in Spider-Man PS4) or does his spider sense help him swing?

[Assistant] Both, depending on the nature of the swing. For normal city traversal its mostly automatic, especially for a more experienced version of Spider-Man, but complex maneuvers require a more conscious effort.


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

[User] ELI5:why is the Mona Lisa so highly coveted- I've seen so many other paintings that look technically a lot harder?

[Assistant]
Five reasons:

1. The smile. It was the first painting of its kind to have someone smiling in such a way, so it was sort of a new era.

2. The brush strokes. He used strokes so small, they were damn near invisible, creating a very 'photographic' painting in a time when that wasn't really done.

3. Street Cred. Leonardo Da Vinci was an extremely talented guy, the quintessential renaissance man. He was a genius, and is thus rightly given praise.

4. Time. This painting took four years of Leonardo's life to make.

5. Subject. Nobody's entirely sure who he's portraying, which is pretty weird for portraits. Usually, portraits like this one are commissioned by the person depicted, but it doesn't appear this was for anyone but Leonardo. Is it a girly version of him? A prostitute? A secret lover? Or just something out of his head?


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

[User] [MCU] so now that the public is aware that Thor and Loki has there been a revival in Norse paganism? How have other religions reacted to the appearance of two living "gods"?

[Assistant] Scandinavia saw the rise of at least one popular pagan group in the aftermath of Thor's arrival on Earth.  This group, called the Norse Paganists, became obsessed with acquiring a staff that provided berserker strength and wanted to be gods themselves.  Phil Coulson's SHIELD team was able to put a stop to them, though.


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

[User]
ELI5: Why are ambulance rides so expensive?

The bill I received for an a mile long ambulance ride was $1,157. Mileage was $13, oxygen was $80, and medical supplies was $25, so the base price was $1000. What makes an ambulance ride $1000?

[Assistant]
You're not just paying for wheels and a seatbelt. You're paying for two trained medical people, availability of all of their equipment, a small built-in pharmacy that serves only you while you're there, a vehicle that is specialized to support all this equipment, connectivity to.the local emergency services network, access to a hospital right fricken now and no waiting room BS.

It's possibly the least over-priced part of the US medical industry.


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

[User]
CMV:Abandoning euphemisms (like pro-life and pro-choice) would make our discourse far more honest, open and ultimately more productive.

It seems the most contemptible and pathetic aspect of our discourse is our reliance on euphemism. It is hard not to sneer at the duplicity and cringing cowardice inherent in the self-bestowed titles of various political movements, like the "pro-lifers" or "pro-choicers".

Say what you mean- respectively, you're against abortion and women's ability to abort. Conversely, the latter are for the availability of abortion.

When you resort to calling yourself a "pro lifer", for example, you by implication endorse beliefs within the remit of being "pro-life" which you don't necessarily support. Pro-lifers tend not to care how many brown children are bisected by apache fire in the middle east, nor do they tend to oppose the death penalty.

But the "pro-choicers" don't get off either, because their chosen name implies all sorts of positions related to bodily autonomy that choicers do not necessarily endorse, like the right to use any sort of drug, the right to terminate the biological functioning of one's own body (suicide) etc. etc. We perhaps ought to be softer on this side of the debate, as these are positions that choicers are more inclined than others to support.

Nevertheless, there is something about the euphemistic titling of social movements centred on a single issue that retards our discourse and devalues the concepts they appropriate to their purpose, adopting whatever term they like when it becomes politically expedient and dropping it whenever it ceases to be so.

TL;DR Call yourself exactly what you are, do not mince your words, be honest with yourself and others. If you can't manage this, you pollute our collective discourse with your cowardice and spineless politicking.

[Assistant] This is simply not possible. Language is inherently loaded. As soon as you find a neutral word for something someone else will start to associate both negative and positive connotations thereby infecting the word with bias and double meaning. To expect us to "not mince words" is to pretend that language is perfect and that there are words that better reflect the truth than others. Language is an abstract way of communicating and it heavily relies on our perception of both the words used and the meaning intended.


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

[User]
[Economics] Using time as currency?

Disclaimer: I realize in hindsight that this might sound a lot like the movie "In Time", but I actually did not get the idea of using time as currency from there.

I would like to know what would happen in a world where the price of products is determined by the time it takes to produce them. For the sake of simplicity, let us imagine that the traders cannot change the price of items, they are really only worth the amount of time it took to make them. To clarify, "time" is not actually traded, but the currency would allow people to buy and sell things worth a certain amount of time. Thus, the currency would be valued by time, like a bill of 5 hours, or coins of 10 minutes.

The idea that struck me was that I thought this might be a good representation of their worth. Also, I'd imagine that (although I'm not sure how) people wouldn't gain or loose a lot of money, it would balance out, as their daily earnings would cancel with their cost of living. Then I thought about if there would be profit, or if there even could be.

If someone could enlighten me on this subject, I'd be really thankful. I have next to no understanding of economics, so please correct me where needed. Also, please add in anything that is relevant that I might not have considered yet. Below are some questions that I have.

* What are the major strengths/weaknesses of such a system?
* Would this work? Why/why not?
* Would profit exist?

I'm sure that more questions will come up when some answers start to roll in.
Thanks in advance!

[Assistant] It ignores all inputs other than time... So, if you have to pay labor it doesn't differentiate between skilled and unskilled. If some inputs are rare and expensive but easily assembled it ignores that cost.


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

[User] ELI5: Why are car crashes with airbag deployment mostly considered total wrecks?

[Assistant]
There's a certain threshold where the airbags deploy. You obviously don't want them going off when there's a low-speed collision, so only higher-speed collisions set them off.

It also happens that cars are designed to deform in order to absorb the energy of those higher-speed collisions. If the cars were solid, they would just transfer most of the energy of the collision to the occupants. By deforming, less energy makes it to the occupants.

These two things happen to have a good degree of overlapping. Depending on the specifics of a collision, you might have a write-off without the airbags deploying, or you might have the airbags deploying without a write-off.

One additional factor is that the airbags destroy a good portion of the interior when they get set off. Especially if you have full curtain airbags, basically every surface of the interior will require replacing. At that point, it's easier to just get a new car given the other damage that also happened.


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

[User]
ELI5: What is super bowl for a non american? Is it a sport or a music event? How frequently does it happen? Why everybody is talking about it?

Edit:I am from Egypt, we hardly understand how to play American Football or Baseball ... Almost no one is interested. I am serious guys! Thanks for the explanations and may the freedom force be with you!

[Assistant]
The superbowl is regularly the most watched TV program in the united states.  With 100 million+ viewers often.  It happens once a year.

It's the final game of the American Football season, not unlike the World Cup for Association Football (what americans refer to as soccer).

There is a big music event normally in the middle of the game, which is called halftime.  For the super bowl this is a huge event, but even in non-professional versions of the game (like those played between schools) there are normally halftime shows which include school bands or other things like that.  Being able to play at the super bowl (during the halftime show, or as a player) is a big deal for everyone involved.

Football is pervasive in American culture, and even people who don't follow sports are aware of what the Super bowl is, and probably even attend a super bowl party to watch the game with people who watch football more.


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

[User]
How does radioactive iodine work?

For treatment of hyperthyroidism, how does the orally ingested radioactive iodine only have an effect on the thyroid? How does it not cross to other tissue/the rest of the body?

[Assistant]
Your thyroid actively seeks to grab onto iodine in your body for its own processes.

The reason why iodine tablets are important to consume in the presence of a radiological release event is because it saturates your body with a (safe) amount of iodine such that when new (radioactive) external iodine enters your bloodstream, your thyroid doesn't pick it up because it's already "full". The result is that the radioactive version of the iodine is removed from your body as waste much sooner than it would have been, which means it spends less time irradiating your cells internally.

Radioactive iodine causes cellular damage to adjacent cells, by virtue of its radioactive nature. This can result in thyroid cancers.

Presumably intentionally ingested radioactive iodine treatment is done in dosages and circumstances that are intended to cause a specific targeted amount of damage to your thyroid, since it's going to collect there. Worst case you accidentally cause thyroid cancer (which you almost certainly will be on the watch for if you've ever had that treatment) which, if caught early enough, can be treated through a variety of means.


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

[User] [It's Always Sunny in Philidelphia] We know what happens on Mac and Dee Day, but what happens on Charlie Day (pun not intended), Frank Day and Dennis Day?

[Assistant]
Pretty much the same as Mac Day except they would do things they enjoy.

 Frank- probably revolving around drugs and whores. He probably makes the gang treat him with respect.

Dennis- lots of compliments and all around worship. He probably also tries to get them to do classier things.

Charlie- hunt for ghouls and goblins(they mention it in Mac Day)


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

[User]
Why is it so difficult to make things look random?

If you take, for example, a handful of pennies and throw them in to a corner, they'll be scattered randomly. But if you were to take these pennies and place them one at a time, it would look artificial, even if you tried desperately hard to make them look random. This may be a bad example, but the point remains the same. It may just be me, but I've always found it almost impossible to make something look like it happened naturally.

[Assistant]
It is because of a phenomenon called "Poisson Clumping" or "Poisson Bursts." This phenomenon is that is random processes often produce clumps of events. In your penny example- if you throw a bunch of pennies on the ground, the Poisson distribution will describe how they land, and for large numbers of pennies, you will expect to get "clumps" or "large groups" of pennies. You won't know beforehand where these clumps will occur, but you can expect them.

The problem is, while this is truly random- when we are trying to artificially make random distributions, we tend to avoid making groups.

Two interesting occurance of this in real life. iTunes and WW2. First, iTunes. People complained that the iTunes random shuffle was bad, because occasionally the same songs would get played in clumps- but it turned out it happened just as much as statistics predicted it would. So iTunes was changed so that it was actually less random, to avoid Poisson Clumping.

In WW2 the Germans were bombing Britain. The bomb landing locations were really pretty random, but due to Poisson Grouping the bomb landed in some clumps- which led the British to think that the Germans actually had better targeting ability than they actually did.


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

[User] ELI5: How game shows (Price Is Right, Jeopardy, Who Wants to Be A Millionaire, etc) can afford to keep giving away money and prizes every show?

[Assistant]
Shows get money from advertising and product placement.  In a regular produced show you have lots of actors.  For a gameshow you really just have the host making them a lot cheaper to produce.

Shows that give away large prizes like a million bucks use insurance.  They know that only a few people a year are going to win the $1 million.  Things like cars and TVs are off-set because the show is also used as an ad.

The Price is Right always spends a few seconds telling you about the FABULOUS NEW FUSION FROM FORD!  Ford provides the car for free or cheap because they get an ad out of it.


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

[User]
CMV: It doesn't matter who you vote for in America.

There's really only two parties, both controlled by the corporations of America, and thus all the decisions made by the president are ultimately filtered through the CEOs and heads of financial institutions. It doesn't matter who you vote for since the president is not powerful enough to make a real change in the country. Hence voting is meaningless. It's all a sideshow for the schmucks that believe in "democracy" even though America is in fact a republic.

Nothing will change in America because people keep voting for the two same parties. The only people that can change America for the better are the people themselves, not the leader. If Americans don't like military spending, then they should shame the military, if they don't like the way healthcare works, then shame the people who run the healthcare, not by voting and going around doing all the congress bullshit.

[Assistant]
All this is abstract. Let's get some specifics.

Do you really believe that if Al Gore had been elected, we would have fought the Iraq war? Do you think he would have repealed elements of the clean air act and called it "operation clear skies" as Bush did?

Do you think Ford would have let Iranian hostages linger for a thousands days without bombing, as Carter did?

Do you think Republicans and Democrats have the same chances of raising taxes on the rich?

There are major differences between candidates, parties, and platforms. These differences, from nuclear proliferation and  funding and support of other nations to research priorities like Stem cell research, effect millions of lives.

The "there's no difference between the parties" trope is more likely the result of people, preferring the lazy luxury of apathy, writing off participation in the difficult and emotionally unsatisfying political process.


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

[User]
[Transformers] Are Transformers born or made?

Are the Transformers born or made by something? We know there's been Cybertronians in the past and in the Beast Wars, it's the decendents of the Autobots and Decepticons, so are the born or made, or are all Cybertronians just always around till they die?

[Assistant]
We have seen Transformers come about through the following means:

* Built from Scratch (G1: Dinobots, Trypticon, Technobots)
* Imbued with life via a "spark" (Beast Wars, Comics, Late G1, Bay movies)
* Budding (G2 Comics)

The answer really depends on the continuity you're talking about and at what time frame within that continuity.


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

[User]
[D&D] Can an adventuring party made up of colorful, unique characters really expect fair treatment in all the different small villages they visit?

We are an adventuring company comprised of a Good aligned Drow Ranger, a gelatinous cube paladin, a Baelnorn lich wizard, the noble Prince-in-exile of the Minotaurs and me, a *totally normal* human rogue.

The other members of my party are convinced that we won't run into any major problems with the innkeepers, merchants, town guards or whoever else we'll meet on our journey (sans evildoers of course), but given how closed off the life of most peasants is, I'm less certain.  So what can we do to help smooth things over during our travels? Any advice would be appreciated.

[Assistant] Depends on the setting, really. For some settings murder-hobo squads are routine. Besides, do you, as a level one town guard, want to be the one to tell the ten foot tall cow man what he can and cannot do?


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

[User] [Dragon Age 2] I am a Fereldan mage who has become a refugee in Kirkwall. I joined the circle, but I am pretty sure like, EVERY mage in the city is a Maleficarum. And the Templars are probably going to kill everyone any day now! How do I save my skin without becoming an Apostate?

[Assistant] Sounds like you need a trump card. The Templars are eventually going to come for you, all of you, so you need some way to protect yourself. Blood magic is a great way to gain the power to protect yourself from the bloodthirsty templars. It's perfectly safe, despite what those templars will tell you.


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

[User]
How does time dilation work without a privileged reference frame?

If a traveler is moving at near light speed when he comes to a stop he sees that we have aged and he hasn't. But aren't we the ones moving according to his reference frame so when we stop why isn't he the one that's aged and we haven't?

[Assistant]
This is the actual "paradox" of the twin's paradox. If you're both moving in a straight line at a constant velocity, you both see each other as time dilated. So if you place one twin on Earth, and the other on a spaceship that flies to Alpha Centauri and back (at constant speed for each leg), then both see each other as time dilated during both stages of the trip. So... who is older than the other?

It turns out the trick is that one twin *didn't* go at a constant velocity. By turning around and coming back, he's broken the symmetry, and made himself different from the other twin. Without a privileged reference frame, there is no universal difference between "stationary" and "moving", so we can't say who is moving and who is staying still. But we *can* say who has *accelerated* and who has stayed at a constant velocity.

You can imagine that each reference frame is represented by a train moving at a constant speed along an infinitely long and straight track. Without any privileged frame of reference (i.e. ignore the track itself), there's no way to tell if your train is moving, or if someone else's train is moving, or if they are both moving. But you *can* tell if somebody has changed trains!

Relativity says that all reference frames are equally true. But if you change reference frames, then you're no longer going to get consistent results: you have to do all the maths from one reference frame. So if you add up the time dilation from the travelling twin's point of view, you get the wrong answer.

In terms of the mathematics & physics of what's going on, the equations for how time differs between reference frames doesn't only include a time dilation term. It also includes an "out of sync" term. If time is running at different rates in different reference frames, then you need another term to account for how time becomes "unsynchronised" between frames of reference.

The time dilation term only depends on your relative speed - it doesn't depend on whether you are moving towards or apart from each other, or how far apart you are. But the "out of sync" term includes direction and position. This makes everything add up consistently so you get the travelling twin ageing less without any contradiction.


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

[User] [ELI5] How does the flash in cameras damage paintings in museums?

[Assistant]
Flashes used to emit a lot of UV which damages dyes and paint. Flashes no longer emit UV so they dont do any damage.

Museums have kept this rule for two reasons:
1. Flashes are really annoying for everyone else.
2. They have a higher chance of selling their book to you if you cant take good photos yourself.


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

[User]
CMV: Calculators should never be artificially restricted in math, even on tests

Edit: wording of the title is confusing. I mean that in math classes above algebra 2, calculators should never be restricted

Restricting calculators in math class is dumb because there will never be a point in time where you have to solve something without a calculator and do not currently have one, or are without the means to obtain one. I am mainly talking about math above algebra 2, as understanding how numbers fundamentally interact with each other is important. The restrictions of calculators don't help students learn better, they just increase tedium.

In addition to this, all calculators should be able to show work when prompted, and should go through regular testing for bugs and the like. Class time devoted to teaching people how to work without a calculator should be instead be used to teach people how to use a calculator effectively.

People have access to calculators pretty much all the time, whether they be on a phone or online. When more advanced math is needed, there are online scientific calculators or you could just carry one around.

[Assistant]
I think it depends on what you're teaching, and on what kind of calculator you're talking about. Being able to use a calculator effectively sometimes means being able to work without using one at all.

If you're teaching students how to do long division, for example, then using a calculator is pointless and doesn't help the learning process a lot.

If you're teaching algebra, then it's reasonable to let students use calculators that are only able to do arithmetic, because they should already know arithmetic anyway. But they shouldn't be using calculators that can do algebra because, again, it's pointless and doesn't help the learning process.

Doing math without a calculator can be tedious, of course, but that can be said of doing any kind of work. Doing pushups can be tedious too, after all, but it's necessary for getting stronger. Watching someone else do pushups (i.e. letting the calculator do the math for you) doesn't do anything to make you stronger. Calculators, when used properly, are mostly a labor-saving device, not a replacement for the ability to do math.

The reason that it's important to be able to do certain things entirely without a calculator is because, if you can't do that, then you won't necessarily know how to correctly interpret the answer that the calculator gives you. I've seen this when grading homework assignments for undergraduate college students. You can often tell which ones used Wolfram Alpha to do calculus for them because they put down really weird (and wrong) answers involving special functions and edge cases. Wolfram Alpha itself isn't doing anything wrong, it's just that the students who use it without fully understanding the calculus aren't able to correctly interpret its output in the context of the problem that they're trying to solve. The ones who can actually do it out by hand never make this mistake.

And, really, this only becomes more important as you do more advanced kinds of math. The easiest and most reliable way of debugging advanced mathematics algorithms is to take a simple example and do it out by hand, and then compare what you're doing to what the computer is doing. If you can't do that then you're in for a bad time.


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

[User] ELI5: Why does eating expired meat make you sick even if you cook it well enough to kill all the germs?

[Assistant] Certain bacteria produce spores when they're within certain temperature ranges. Like when you cook meat and let it sit out at room temp for a while. This is when those spores go wild. When you reheat the food the bacteria is killed but the spores are resistant to cooking temperatures and will survive, eventually making you sick. In other instances you can have bacteria that grow and produce toxins. When you reheat the food, the bacteria toxins are not destroyed and can cause food poisoning.


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

[User] ELI5:Why does college cost so much in the United States while it is free in other parts of the world?

[Assistant]
It costs *something* because education beyond high school (which is paid for by everyone's taxes) is viewed as either a luxury or an investment that people should pay for themselves.

It costs *so* *much* because various government initiatives made it possible for people to borrow money to pay for it.  Generally speaking, making it easy to borrow money to buy certain things causes the price of those things to go up, since anyone who really wants it but doesn't have the cash can borrow to pay for it, so raising the price doesn't shut people out of the market.  (You see the same thing with mortgage interest rates and house prices.)  Furthermore, people justify borrowing that money because it's seen as an investment -- you'll make enough money later to pay it back, and more -- though that's not always true.


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

[User] Why does U-235 split when hit with a neutron instead of becoming U-236?

[Assistant]
>Why does U-235 split when hit with a neutron instead of becoming U-236?

It can do that too. Fission is not the only possible outcome. It can scatter (elastically or inelastically), or undergo radiative capture, or a whole host of other nuclear reactions. Each of these reactions has its own probability, and all of them are functions of energy.

But the ^(235)U(n,f) (neutron-induced fission) cross section is pretty high. For thermal neutrons, the fission cross section is almost 6 times higher than the capture cross section, so fission is about 6 times more likely.


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

[User]
Is there an official name for the hypothetical star who's supernova created the material in our solar system?

Assuming of course that all of the non-hydrogen elements or at least a significant percentage of which that created our solar system and it's sisters was generated in a single Supernova event.
Is there an official name for this hypothetical star as used by the scientific community? and if so what is it?
What would the mass of this star have been roughly? and what sequence would it have been? And by what means have we identified this?

[Assistant]
Not really, for a couple reasons.

One, the vast, vast majority of the material in our solar system is in the sun in the form of hydrogen.  That hydrogen was mostly never inside a star, though perhaps some was in a star but never fused.  So most of the material in our solar system was never in a star.

The heavier elements, like those making up Earth and other rocky planets, were created by heavy stars it's true, but not one single one.  Instead, many stars impregnate the interstellar medium with heavier elements.  Then a local cloud came together from that medium and formed our solar system.

However, sometimes a very close supernova can "trigger" a cloud to collapse and form a star, and it's thought there may have been a single local star which went nova and triggered the birth of ours.  While very little of our solar system is composed of matter from that star, there are some trace elements which came from that supernova.


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

[User]
Does physical trauma (shaking/vibration/dropping) have an influence on batteries and how long they hold their charge?

If Im tossing my AA batteries around the house before I actually use them in something could I at all be shortening how long/well they can hold their charge?

[Assistant]
Theoretically yes. A battery stores energy in the chemical bonds of the materials inside it. By moving and shaking them you could theoretically alter the properties of the chemical compounds. However, in most common AA batteries the materials are dense pastes that are tightly compacted in the steel can. Therefore, shaking them does not cause significant effect on the materials.

As an example, think of a thick liquid, for example, honey. If you shake a sealed bottle of honey vigorously for a few minutes, and then you stop, it will still be honey; it will not lose its properties or taste. You would have to use a powerful centrifuge in order to start splitting the sugars from the water contained in honey, and significantly alter its properties.

The paste that makes the AA batteries is even denser than honey, like dried up mud, and tightly packed. You would need very strong forces to alter significantly the chemical properties of the materials.

Now, lithium ion batteries, such as the ones in cellphones, are different. They don't have pastes, they have coatings in very thin copper and alumninium layers. Shaking them may actually rupture the layers, causing an internal short circuit. It is possible to damage them with enough force, but this isn't very common in the normal usage of the battery.

Battery cells of all kinds are actually tested in special shaking tables which move in all three axes (X, Y, Z) precisely to test their mechanical stability. There are international standards from ISO, IEC, IEEE, and others, which describe the characteristics of these tests. If the AA batteries and lithium-ion cells were not strong enough they would not have made it to the consumer market that we see today.


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

[User] ELI5: What makes 70mm film screenings different? (i.e. Dunkirk)

[Assistant]
For one, it's not a digital projection.  Most movies you go see in a theater are projected digitally, but if you had gone 15 or so years ago, they would have all been projected with film.  There is an ongoing debate about which is better.  Digital tends to show a cleaner picture, but the detail is limited to a certain resolution and film tends to have richer colors and blacks, but with some minor imperfections in the picture.  It's sort of similar to the debates about whether sound quality is better on vinyl records than it is on digital files.

Anyway, if you had gone to see a movie back in the day, in most cases it was on 35mm film.  Dunkirk is being shown on some screens in 70mm film which means that the individual frames are larger and thus have more detail.


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

[User]
How does vectorization work, why is it so much faster than loops?

Pretty much the title; coming from a python background for context. I understand that vectorized operations are much faster than loops, but I'd like to understand how that can be. I've never coded in a language such as C, that demands knowledge of memory management of the user - so I'm prepared for this to go a little over my head. (Additional reading material would be a plus!)

[Assistant] It's mainly a speed up from two things.  The CPU instruction pipelines do not like branches, and vectorization reduces the number that execute.  Also they tend to be very wide letting the core execute on multiple numbers at once.


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

[User]
What is the temporal scale of weather autocorrelation? To what extent is there such a thing as a "cold year" or a "warm year"?

I'm interested in to what extent temperatures in one part of the year predict temperatures in subsequent parts of the year (especially to what extent a warm spring predicts a warm summer). This should be important to several aspects of the life cycles of the insects I work with, but I can't find anything on it in the literature.

My takeaway from reading some popular science sources (e.g. weather services websites) is that a warm spring is no herald of a warm summer, and that temperatures often average out across the whole season. So perhaps there's no correlation on a two- or three-month scale, and no such thing as a "warm year" or a "cold year", other than by mere contingency.

But at the other extreme, temperature does have a certain degree of inertia - daily temperatures don't fluctuate within the entire range, but rather today's weather correlates to some extent with tomorrow's weather. Pressure systems take time to form and move around, right? So there must be some level of temporal resolution at which present temperatures correlate with future temperatures. Is it days, weeks, months?

I'd be super grateful for sources, if they're available. :)

[Assistant] The temporal correlation of 'weather' at mid-latitudes is 3-7 days and is predominantly set by the time-scale of meanders in the jet stream. The dynamic 'memory' of the atmosphere is 2-4 weeks which sets the maximum correlation time-scale for an 'atmosphere-only' planet to be about a month.  Any non-seasonal variability on longer time-scales than a month cannot be self-generated within the atmosphere and are dependent on coupled interactions with the ocean such as El Nino (and to lesser extent atmosphere-cryosphere interactions). The ocean's primary influence on weather is through the slowly evolving spatial distribution of sea-surface temperatures which sets the lower boundary-condition on the atmosphere. Predictions of ocean surface temperatures are improving but are still hampered by the small scales which need to be resolved (10s of km) and sparsity of ocean observations.


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

[User]
Why am I always depressed after big days?

Every time after celebratory events, family gatherings, nice trips etc I feel dead inside and need few days to pick myself up. Why is that?

[Assistant]
I would like to hear the chemical science behind the phenomenon. We always call it "drop".

I figure it has to do with the high amounts of serotonin and dopamine released while engaged in positive activities with people you enjoy followed by the brain's withdrawal and rebound to baseline.


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

[User] ELI5: what happens to all of the atoms in our body when we die?

[Assistant]
To many creatures people are just a walking meat pile. The only reason we don't get eaten is because we walk too fast (and our internal defense system kills anything we can't walk away from).

After death our bodies get eaten by bacteria, fungi, insects, small animals and whatnot. Our atoms eventually become atoms of animals and plants and earth and wind.


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

[User]
[Fight Club] what if Project Mayhem had been implemented during this decade instead of in the late 90's?

What would be its targets (instead of/besides credit card companies) and would it have been implemented on a global scale thanks to omnipresent internet communication?

[Assistant] Probably the NSA and similar monitoring targets. Maybe Silicon Valley and its tech giants gone wild? Facebook headquarters? Problem is, the majority of important information is backed up in multiple places (in the cloud, on multiple servers, etc.) so that whatever damage they did would be symbolic, rather than lasting and truly meaningful.


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

[User]
How did engineers/machinists create the first precise straight edge?

If I had to create a good straight edge from scratch, my first thought would be to pour molten tin on top of molten glass for a flat surface, then fold the cooled tin sheet, as it seems from experience that folding creates a straight edge, though I've never heard how precise it is.

But I assume the above process for making a flat surface may not have been known in antiquity, so I'm wondering how and if they did it.

[Assistant] If you rub two relatively flat surfaces together you end up with a flat surface. Imagine 2 pieces of sandstone rubbed together until "all" points of the surfaces are touching. "All" is in quotes because obviously there are always surface imperfections which will keep the parts separated. A straight edge is only as flat as the grain of the material. Maybe granite would be a better material. Add a small amount of grit and water between two pieces of granite and rub back and forth and in a circular motion and viola, straight edge.


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

[User]
[Blade Runner] What caused the clouds to pour heavy rain all the time?

Was there some natural diseaster that caused too much water to be released to the atmosphere, or was it caused by humans?

[Assistant] Yes, burning carbon based fossil fuels for energy over time, creates denser and denser clouds.  This has a circular impact.  So less Sunlight due to more clouds, means burn more fossil fuel for heat and energy, and the clouds get worse, less sunlight.  You start to cook the planet like a pot with top on too tight, no pressure release.  The polar caps melt, adding to even more moisture in the atmosphere.  hence the rain.


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

[User]
What would Schopenhauer have thought of Nietzsche?

Even though he would eventually reject much (most?) of his philosophy, Schopenhauer was of course a big influence on Nietzsche. My knowledge of both philosophers is largely through secondary literature, though I have read primary literature of both (Schopenhauer more though). One thing that has always struck me is that Schopenhauer's thought seems (at least in places) radically opposed to Nietzsche. Even though he was an atheist, he shows sympathy for Christian ascetics like Francis of Assisi, whereas Nietzsche of course firmly rejected asceticism. Schopenhauer says that "compassion is the basis of all morality," an idea I'm sure Nietzsche would have been loath to accept.

Schopenhauer died when Nietzsche was only 16, so we obviously can't really ever know for sure what he would have thought, but I get the sense that he would have disliked what Nietzsche had to say. However, I'm curious what any people here more thoroughly versed in Schopenhauer and/or Nietzsche think.

[Assistant]
I imagine he would have found Nietzsche's view on suffering as quite perverse. In many ways Nietzsche's defined himself as Schopenhauer's opposite for example - Schop saw life as endless suffering and therefor bad ~ Nietzsche accepts suffering is a large part of life but claims it is life-affirming and in some ways a good thing.
Nietzche takes Schopenhauers pessimistic analysis and turns it conclusions on their head.


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

[User]
Arguments against veganism

As a somewhat fresh vegan, I have been trying to search and find the best arguments against ethical veganism. The ethical vegan position seems pretty obvious and morally unassailable to me. However, it has been my experience that most of moral philosophy, especially when it comes to practical ethics, is a quagmire of uncertainty where the perfectly ethical sound position seems almost impossible to gleam. Thus, the fact that I find ethical veganism such a slam dunk position is making me unsure, but all the arguments against it that I've read or heard up until now have never really shaken the core of my belief in the argument. I should note that my ethical view is very similar and influenced by Peter Singer and William MacAskill.

I was wondering if there are any really convincing arguments against ethical veganism.
As for arguments that I've heard that have not convinced me, they include:

\- The argument that it is not feasible for people living in poorer parts of the world as of right now. (I concede this point but it does not apply to the people I believe should become vegans.)

\- That it would involve more intensive farming of the land, ending in more suffering in the long run.

\- That you are transferring your speciesism to plants and that you can't really know if plants can suffer.

I'm not really that academically trained in philosophy so I am not sure if I am able to effectively discuss any arguments presented but I would love to read them nonetheless.

[Assistant]
One fairly large missing step in the arguments for ethical veg(etarian)ism is the gap between production and consumption. To quote SEP:

>None of the foregoing is about consumption. The moral vegetarian arguments thus far have, at most, established that it is wrong to produce meat in various ways. Assuming that some such argument is sound, how to get from the wrongness of producing meat to the wrongness of consuming that meat?

I recommend reading that entire page "Moral Vegetarianism", and seeing what you think of the arguments many have offered to explain this gap.


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

[User]
ELI5: Why don't phones just take video in landscape mode even when people hold the phones vertically?

Everyone hates vertical videos, and yet the easiest way to hold a phone to take a video is by far holding it vertically.  So we wind up with tons of vertical videos.

Is there some hardware barrier preventing the software from simply taking landscape videos regardless of orientation?  Isn't the aperture on the device round?  Is this just a software oversight that everyone mysteriously has, or is there some actual hardware limitation?

[Assistant]
It's a hardware issue. The sensor in the phone that captures the image is rectangular and only oriented one way relative to the phone.

Phone manufacturers could put the sensor on some mechanism that allows it to rotate so you could take landscape photos while the phone is vertical or vice versa, but that means there's added complexity, greater chance of failure, and it would drive the cost of the phone up. Overall, it's just easier for users to simply turn their phone around.


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

[User]
[Warhammer 40k] How come Khorne is so popular?

Look, I know that in the grim darkness of the far future there is only war, but there are quadrillions of beings in the galaxy that are hardly ever exposed to war.

Suppose I'm Billy the Farmer from an agriworld who decides to join a chaos cult. What does each chaos god have to offer me? Eternal excess and pleasure. Nihilistic comfort and acceptance. Forbidden knowledge and magic powers. And...being really angry?

I get why Space Marines and suchlike would fall to Khorne, but it seems to me that an average person who falls to chaos would be much more likely to seek personal comfort offered by the likes of Slaanesh or Nurgle, than roid rage. Most people aren't really inclined to violence and murder.

So how come Khorne is one of the most powerful and influential chaos gods, if not the most powerful? For every Space Marine or hardass IG veteran who can't live without the thrill of violence, there are thousands of Imperial civilians who would rather do cocaine or wallow in filth than have to go fight someone.

[Assistant]
First of all, you have to remember the lens through which we are looking at this universe. Our focus is primarily on the armed forces of the various factions - and, in the case of Khorne, the armed forces of the Imperium of Man (Eldar are too regimented, Necrons too soulless, Tau too insignificant, and Orks too orky).

Human military forces tend towards certain ideals - honour, courage, camaraderie. Khorne offers all of these, at least at first (they rapidly spiral into arrogance, anger, and elitism). This makes him very attractive to those of a martial bent.

This means that Khorne's followers are going to be over-represented on the battlefield. Soldiers who are going to fall to Chaos are most likely to fall to Khorne; people who fall to Khorne are most likely to become soldiers.

You'll find few Khorne worshippers in the pleasure-houses or gambling dens of a peaceful paradise world, or among the schemers and backstabbers of a corrupt court, or among the farmers and physicians who struggle to sustain life on a halfway-barren planet. You'll find a few, of course, because there is courage and honour and fury and pride to be found everywhere that humanity has put down roots, just as you will find worshippers of Slaanesh and Tzeentch and Nurgle on the battlefield.

The second thing to consider is simply a matter of visibility. How do you spot the Slaanesh worshippers? They're the guys having an orgy in a secret club in a back alley. How do you spot the Tzeentch cultists? You don't, you just find their fall guys who the actual Tzeentchians (claim they) wanted you to catch anyway. How do you spot the followers of Nurgle? They're working behind the scenes in healthcare, sanitation, and food preparation.

Okay, and you know how you spot the servants of Khorne? They're the ones running at you screaming incoherently and waving an axe.

tl;dr Khorne seems more popular because he's naturally over-represented on the battlefield, and off the battlefield his followers are extremely easy to spot. Billy the Farmer probably isn't going to follow him, but theres plenty of people who will.


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

[User]
[Star Trek] Why doesn't anyone use transporter technology to make backup copies of themselves?

At one point Riker accidentally gets copied (showing you can duplicate a person) and Scotty basically preserves himself via transporter 'saving' for several decades on a disabled shuttle.

If they can do this, then why not save the last copy of people who are transported in case they die on an away mission?  If that happens then you can reconstitute them again using the saved data that you used to transport them in the first place.

And I get that the Federation has the prime directive and all, but they're hardly the only ones with Transporters.

[Assistant]
Both of the situations you describe were dangerous as *fuck*. Scotty nearly didn't materialize, and his companion died. Riker was beamed out halfway through a unique window on a hardly-understood world and *also* almost died.

What would be a much better example is Doctor Pulaski, who basically used the transporter buffer and a biological sample to reconstitute herself pre-infection by a...complicated bio-agent that was kind of stupid in general.

Even then, she *also* nearly died in transport.

You should be detecting a theme, here. Transportation almost kills people all the time. Screwing with the process will not make that "almost" any better.


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

[User] ELI5: How do I get tired from oversleeping?

[Assistant] You might be tired because you woke up in the middle of your sleep cycle. As the night goes on, the body will go through stages of sleep; and the deepest is REM sleep. That's where all your dreaming happens. An average sleeping cycle lasts approximately 90 minutes. If you wake up in the middle of one of the cycles, it can leave you feeling extremely groggy.


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

[User]
What happens if you get a vaccine for a disease you already have antibodies for?

With the Covid stuff going around, I'm sure there's some people who gained antibodies without realizing it.
Does nothing happen?

[Assistant] If you already have circulating antibodies from a prior infection (or a previous vaccine), your body would mount an immune response against the foreign antigen in the vaccine in a manner similar to how it deals with other pathogens your body encounters on a daily basis. This results in your body having greater stores of immune cells that can quickly produce antibodies against the infection. This is the principle behind "booster" shots or vaccines that are given in a series of multiple injections. It wouldn't result in any adverse effects beyond what you'd expect with a typical vaccine (that is, some injection site pain, headache, or muscle aches for a couple of days).


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

[User] ELI5: What does it take for the world to officially announce the beginning of a world war?

[Assistant]
There is no such thing as "officially" announcing the beginning of a world war. The label "world war" is applied by the press, historians and the common people when they think it is appropriate.

If you are referring to recent events, they are not at all comparable to a world war. The world's major powers are involved, yes, but they are united against a mostly regional enemy. Economies are not being mobilized, there is no conscription, freight ships are not being sunk...for the man in the street, life goes on as usual. By mid-20th century standards, it is barely a war, let alone a world war.


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

[User]
ELI5: Why do some people 'freeze' when they get scared. Shouldn't they enter fight or flight mode? What happens with your body in such a situation?

It doesn't make sense to me that when a human gets scared his whole body 'freezes'. Wouldn't it maximise your chance of surviving if you entered fight or flight mode?

[Assistant]
freezing is a form of defense. you see it commonly in rabbits and deer. a moving animal is easier for a predator to spot. by holding still, there is some chance that the predator will move on, or the prey will get more time to assess the situation.

it's obviously rather detrimental when a car is about to hit you, but we evolved with lions, not toyotas.


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

[User]
Is it possible using software to determine the hardware circuits of a computer system?

You can obviously find out a few basic things about hardware you're running with software programs; the amount of RAM channels, control operations on the microprocessor, etc, but how much further could you theoretically go in determining exactly the structure/nature of the circuits on which the software is running?

[Assistant]
Unfortunately no - and it's the same problem we have with our own reality. :)

With any instruction you execute, the response returned may only be what the emulator you didn't/ couldn't know was running wants you to know.


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

[User] ELI5: Why does the little stretch and shake that we do before or after sleeping feel good? What does it do the body?

[Assistant] When you sleep, your muscles lose tone and fluid tends to pool along your back. Stretching helps to massage fluid gently back into the normal position. It also activates your parasympathetic nervous system and increases blood flow to your muscles. It's thought that stretching may also release endorphins that help to reduce pain and enhance your mood.


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

[User]
[Marvel/DC] Would Doctor Doom be chosen to by the green lantern corps?

Do the rings choose solely on willpower or does the person also have to be good?

[Assistant]
By pure amount of willpower Doctor Doom ranks number one of all human beings native to earth. You've probably seen how he defies Purple Man's enhanced power which was able to control the whole world.

Additionally, Doom cares deeply about the well-being of the planet and it's people. He does a lot of things out of the belief that it's the best for mankind.

He might actually be a really good choice for a Green Lantern depending on when he gets the ring. If it's early enough he would probably accept his role as Earth's protector and not try to take it over to shape it to his idea of a perfect world. Maybe seeing other planets might make him reconsider his partly fascistic/extreme views.

After all, Doctor Doom (man does this name make this sound stupid) is not inherently bad. He just chose a way that's morally unacceptable for most people.


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

[User]
If the event horizon of a Black Hole is the point at which nothing can return, If a nuclear bomb is detonated 5 meters within the event horizon, would a person 5 meters outside the event horizon be unharmed?

The bomb is detonated 5 meters within the event horizon, and the person is 5 meters outside the event horizon.  Would he be unharmed even though he was only 10 meters from the explosion?
(and assuming he can keep himself from passing into the event horizon)

[Assistant] Yes. All of the radiation and hot material from the explosion *must* fall inwards. No light, sounds, or anything will go "upwards" and escape the black hole. There would be no way to tell whether a bomb had gone off or not.


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

[User] ELI5: Why do my finger tips occasionally feel like they get no traction/grip, like they're more smooth than normal.

[Assistant]
the majority of the time it is just because your hands are dry. Throughout the day, you hands naturally get some oils etc... on the surface that help you get a better grip things like paper.

That's why you often see people lick their finger or thumb to turn a page on a book.

Dry hands like this can be caused by things like taking a shower, washing your hands etc... Also the air is usually drier in the winter which doesn't help.

To prevent this you could maybe just use some moisturizing hand lotion.


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

[User] [ASOIAF] Why the wall is so damn high?

[Assistant]
Here is a little-known fact about the cold wastes. In the summer the bugs are **horrendous**

Ever been to alaska? The mosquitos don't bite you, they carry you off and eat you in their lair. Its a bird: Its a Plane: Oh fuck, nevermind, its a mosquito.

So Bran the Builder goes up north to build this wall. He knows he can keep people out by just having it 30 feet tall, he can keep giants out by making it 50 feet tall. So he gets to work making, just to be safe, a 60 foot wall. But then spring starts to hit, a relief for him and his workers until the bugs come. So many mosquitos. At this point Bran the Builder knows what he must do.

"We must protect our blood and kin to the south. We must ensure their safety and the safety of our future-born. We must keep the bugs out. Build it as tall as you can, then no more will we have to deal with the biting menace."

And thusly the wall became 300 feet tall. Never underestimate a man's hatred for bugs.


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

[User] ELI5: How is Trump doing so well in the polls?

[Assistant] Honestly. He says what a lot of people are thinking and isn't spouting bullshit lies just to get votes. Some people view complete honesty as a good trait. He's hiding nothing. He's the exact opposite of a politician.


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

[User] [Star Wars] How can the CIS Droids be a "battle hardened army"?

[Assistant]
They are battle hardened in two ways:

1. The technology has been implemented in actual fighting, so any design flaws, like overheating or weak armor pieces, and software bugs, like shooting other droids or innocent squirrels, have been worked out.

And

2. The tactics of exactly how to organize, disperse, and direct the droid army have been learned and polished by the organic commanders.

Essential when they say "Battle Hardened" they mean "Field Tested and Approved."


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

[User]
[Firefly] Does 'Earth That Was' still exist?

I get that all, or almost all the people left Earth That Was, but does it actually still exist? If there were enough people left behind that could find each other, they could possibly repopulate the entire planet again (but that's another question there). And if the series continued, would there have been a trip there if it did still exist?

[Assistant]
Earth-That-Was was still there when folks left. It just didn't have any resources left, had too many people for the environment to support, and had a climate that had been ravaged by centuries of neglect and mismanagement.

It's assumed there's none that's left on it. Some folks aren't even sure where it is.

Them of the 'verse don't have FTL. An entire generation was born, grew old, and died during the trip from Earth-That-Was to the new system.

Going back would be pointless. Even with all the terraforming tech that exists now, that wouldn't put nutrients back in the soil and it wouldn't put metal and minerals back in the ground.


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

[User]
CMV: The internet is over reacting to this United Scandle.

I seem to be missing some crucial bit of information about this United Airlines scandle. I appear to be in the minority when I say United didn't do anything to warrant this level of hatred and mocking from the internet.

Main point: United Airlines did not harm the man in question. It was the Chicago Department of Aviation. If the man had not been hurt and filmed this would not have been such a scandle. He was but, rather than assigning blame to the contractor (I want to say this department actually the under the city of Chicago, but I can not confirm that.) Everyone seems to place the blame on United Airlines.

Side points:

Bumping four passengers for airline employees is fine. I don't know if these passengers were pilots or support staff, but I am going to assume that they were essential for another flight. I am also assuming that if they (The airline employees) had not made that flight then potentially hundreds of other passengers could have been even further delayed. Evidence to suggest that they were not essential to another flight would change my view on this instance of flight bumping.

United Airlines has a pretty awful customer service record. I knew of multiple incidences before this where they HAVE LOST PEOPLES CHILDREN AND PETS.

[Assistant]
Uniteds policy of bumping passengers, while pretty much universally hated by passengers is neither here nor there. The part that is the worst is that he was ALREADY on the place. You bump someone at the gate, they understand to some degree. You bump someone after they have already waited to board and are in their seat, it's a big F U. It's rubbing it in their face that whomever else is replacing them is more deserving and important than them. This is what made United so initially hated. For most passengers, it is the fact that the people kicked off the flight waited, already boarded and got settled in before being forcefully removed was what set things off. For a society that is already sensitized to corporations screwing over the little guy and socioeconomic classes having to play by different rules. This just smacked of elitism and disdain for the every day customer.

Follow this up with the MOST tone deaf response in the world. The CEO didn't even acknowledge what other passengers were feeling. He just stuck his head and in the sand and gave a huge F U to all of the others that were outraged. The fact he called it reaccomodate and didn't even address the brutality itself, made him come across as very insincere and disinterested, which in a situation like this means it comes across as tacit approval.

Lastly, people were pissed off at the jackbooted response of the Chicago Police. Police and authoritarian brutality is a hot button topic. As such, most felt that the police were acting as United's personal jackbooted thugs, enforcing a corporate policy. Honestly, if United had just condemned their response outright. This would have quickly blown over, because the doctor had now than enough skeletons in his own closet. Instead, their failure to address what happened resulted in people feeling like United condoned what happened. Follow that with the fact it wasn't until their stock took a huge hit that they DID address it, they really dug their hole deep.


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

[User] [Greek Mythology] What were some of the positive traits of Hades, the Greek god of the underworld?

[Assistant]
Hades wasn't really intrinsically evil. He shared many of the traits of the other Greek Gods(petty, jealous, womanizing), but in terms of what you're asking for...

* When Heracles needed to retrieve Cerberos from the underworld as part of his twelve labors, he just went in and asked for him and Hades told him "yeah sure, as long as you bring him back after you're done."

* Hades was sometimes depicted as a god of wealth and precious metals.

* Hades was usually not more malicious than the other Greek gods. He was at worst stern and guarded the border between life and death carefully.

* Despite the above, he could actually be bargained with on rare occasions - the only reason Orpheus' quest failed is because he couldn't resist looking back just a little too soon.


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

[User]
[Three Laws of Robotics]I need my robot to disregard the first law

The kids in my neighborhood have come up with a new way to pass the time: They walk up to someone with a robot, and tell the robot something along the lines of "I'll kill myself if you don't follow me" or "My grandmother is dying, only you can help her!". Essentially they trick the bot into thinking it's in danger of breaking the first law, thereby ignoring any commands it is given, dropping whatever it's doing and running off with the kid. I've even heard of some of them tricking the bots by endangering their own health by eating something they're slightly allergic to.

Sometimes the bots don't come back, In my case it did. How do I stop this from happening again?

[Assistant]
You should be able to retrieve your robot's memories, which are admissible as evidence in most jurisdictions. You can sue the kids and their parents in small claims court for monetary compensation if they damage or steal your robot, and if they waste its time you can charge them for its runtime at labor wages.

That said, this is a great example of why the Three Laws are a terrible idea.


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

[User]
ELI5: Why is it louder when a bunch of people make the same sound at the same time?

For example, a stadium full of people singing the national anthem is louder than one person singing the national anthem, but they're each individually singing at the same volume.

[Assistant]
Waves interfere constructively and destructively. Think about pushing someone on a swing, when you push them the way they are already swinging they swing higher, and when you push against their motion they swing less.

Waves that encounter each other then will combine into one wave. The peaks of the sound wave from one person will combine with the peaks of other people's voices to push the combined sound louder.


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

[User]
[Star Wars] Palpatine knew of Anikans secret marriage to Padme. Had she not died, what was his plan?

Palpatine used Anakins love and attachment for Padme to seduce him to the dark side. Padme was still alive after Vader was born through his desire to save her. What if she was saved? Surely the Sith Lord could not allow his apprentice to continue to have such love for another being. Wether or not she left Vader and went into hiding, she would most likely still stand as a call back to the light for Anikan. Did Palpatine have a plan for this? Would he have her killed outright and if so how would he keep this knowledge from Vader? I suspect such an act would be the one thing which could draw enough rage for Vader to be able to defeat the new emperor.

[Assistant]
He'd almost certainly have had her killed. Making it look like an accident could be tricky, although under the right circumstances it could be as simple as sabotaging a medical droid so that its memory is wiped of all information relevant to pre- and post-natal care and psychiatric treatment.

More likely, though, he'd have her obviously murdered, and leave a trail of clues leading back to a faction or individual who he reckons could do with a bit of the old wrath of Vader.

Note that - as we saw in *Attack of the Clones* \- this method doesn't need to succeed; whether Padme lives or dies, the trail of clues will still be there. He can afford to keep arranging assassination attempts until one of them gets through, or until Vader has rage-murdered every single one of his political enemies and he's reduced to pretending the latest would-be killer was hired by that girl who turned him down when he asked her to the homecoming dance in space high school.


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

[User] Luke and Leia are switched at birth. He becomes Prince of Alderaan, she's raised on Tatooine by the Lars. How does history change?

[Assistant]
Leia has a much harder time on the farm than Luke. She's a lot more forceful and brash, and given the backwards nature of Tatooine, is probably discouraged from doing a lot of "male" things like repairing droids, shooting womp rats, and piloting. Her reaction to this is probably not to learn her place, but to rebel - hard. She runs away at fifteen years old, and thanks to her powerful Force sensitivity, becomes a hot-headed smuggling pilot. Obi-wan spends quite a bit of time trying to chase her down.

Meanwhile, Luke is learning diplomacy on Alderaan. His more reserved nature more perfectly matches with royal society, and he becomes a diplomatic force to be reckoned with, and later a senator at a very young age. Though never quite as daring as Leia, he still joins up with the Rebel alliance due to their treatment of non-Humans.

Events begin wildly diverging when the rebellion obtains the plans for the Death Star. Kenobi is chasing down the renegade Leia rather than on Tatooine, and so it's unclear where Luke's "diplomatic mission" would end up taking him. It's likely that he would be captured by Darth Vader, who would reveal his heritage to him and attempt to bring him over to the Dark Side without all of the playing around.

Kenobi catches up with Leia somewhere outside of Kashyyyk. She's hooked up with a Wookie and a smuggler by the name of Han Solo, but after Kenobi explains matter to her and tells her that he life is in danger, she explains that working for the Rebellion doesn't really interest her - unless she can get something out of it. Kenobi agrees to train her in the ways of the Jedi, and the other members of the *Millenium Falcon* reluctantly come along.


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

[User]
CMV: Business owners should have the right to refuse service whatever the reason.

When I read about the Indiana legislation that sparked from the right wing Christian bakers refusing to make a cake for a gay wedding I thought this is ridiculous they shouldn't be able to discriminate against gay people.  But then I thought, what if I owned a screen print shop and Westboro Baptist Church wanted me to print up a bunch of homophobic shirts I'd tell them to get the hell out.  Or if I was a tattoo artist and someone wanted a neo-nazi tattoo should I have to do that as well?  Even if I think the beliefs of someone else are wrong, they may hold those anti-gay beliefs just as strongly as I hold my own.  Furthermore, if we remove values and morals from the equation, what if I owned a restaurant and my crazy ex wanted to come in just to be rude could I tell her to leave and that she wasn't welcome?

[Assistant]
This is a pretty common subject here but here's the gist:

You can refuse to make a specific thing - a nazi tattoo or a hateful sign. You would refuse to make or sell that object to anyone, regardless of who/what they are.

You cannot refuse to sell the same object to different people based on their race. If a nazi came into to your tattoo parlor and order a flower tattoo from your sample book, or a WBC member wanted a T Shirt off the rack, you can't refuse to sell it to them just because of who/what they are.

It's the same with the wedding cake, unless the cake was covered in penises there is no distinction between a gay cake and a straight cake except who it is for - that's where the illegal discrimination comes from.


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

[User]
ELI5: When a car wheel rotates, does the air in the tyre also rotate?

Does the air in the tyre rotate along at the same speed as the wheel, or is it stationary, or is there some kind of turbulence inside the tyre?

[Assistant]
A good analogy would be stirring a cup of tea. The tea moves, but not at the same speed as the teaspoon.

It would be the same for the air in a tyre. Like the tea, air is a type of fluid - so the friction between the rubber and the air will cause the air to rotate, but not at the same speed as the tyre.


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

[User] ELI5: How does the witness protection program work exactly?

[Assistant]
Certain people who testify to police or in court have a particularly high risk of attracting violent reprisals from people negatively affected by their testimony. For example, someone who provides law enforcement with information regarding members of a gang.

These people and their families are given new identities by the government and moved to a different part of the country. The idea is that with a new identity, it's much harder for people who wish to harm them to track them down.

Or are you looking for something more specific?


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

[User]
Does DNA store meta-data about its history?

i.e. are there any segments of the DNA strand that might give away information about how the DNA has changed over time and, if so, how and where are these situated?

[Assistant] If you mean meta-data as in data-about-the-data way, then yes. This is called epigenetics. Generally, its used to switch off genes where they arent needed e.g. eye creating genes in your spleen. Its also possible to pass on the epigenetics effects that the environment has on your DNA though. So if a woman who is pregnant with a baby girl goes through a period of starvation or is exposed to a pathogen, this will alter the epigenetics of the eggs forming within the female fetus, causing altered gene expression two generations hence from the initial stimulus. you can see that when you test for position of epigenetic markers. There are other ways epigenetics are used but they get very complicated so Ill skip those for now.


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

[User]
[Star Trek] This has gotta be an old question. Pretty basic. So these ships routinely zip around at multiple times the speed of light...

Why does the Enterprise, or any other ship, return to a home planet that's recognizable at all?  Why are Spock's parents alive when he gets home? (y'know, on those timelines where the planet Vulcan still exists.  Or even when he travels from Vulcan to Earth and back to stop the planet from blowing up, why is his mom still sexy Winona Ryder, let alone alive?)

I understand the idea of a space warp where a ship would not actually be traveling in speeds above C, but the ships on Star Trek are often shown traveling through physical space, and just the fact that there's warp one, two, three, etc indicates that these are actual speeds, not just instantaneous point A to point B with nothing in between.

On a side note, assuming relatavistic time dilution, how quick would Captains Archer, Kirk, Picard, etc all be running into each other, going on adventures and then kicking back for some R&R on Risa or Sextillion or wherever?

[Assistant] The warp drive (the engine of the ship) and the nacelles (the wheels) create a field around the ship that warps spacetime in such a way that they can travel at speeds in excess of c relative to any point of view outside the field, but within the field they are not moving in excess of c. This is known as sub-space, and travelling like this does not induce the effects of time dilation.


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

[User]
If I had a spaceship and traveled in a straight line - would I hit a black hole sooner or later? Would I be even able to detect if I am not flying straight into one?

Let's assume that time is not important and that my speed is very high. We can imagine it as some sort of a "space jump" like in Star Trek - how would the spaceship even know if it is not flying straight to death? Is the universe so big that it has enough black holes so that the ship would hit a black hole sooner or later?

b) How could I even detect that I am not flying straight into a black hole - I know most of them can be detected because they are eating up stuff, but are there real "black" black holes?

c) part of this question is changing the black hole for a star -> obviously a star can be seen and detected easily; but is the universe so vast, that a spaceship flying straight through it would hit a star sooner or later?

I also know that flying straight in space can be pretty hard, but let's assume that my spaceship can do this.

[Assistant]
No, in fact it's almost incomprehensibly unlikely that you'd hit a black hole. Black holes are very rare and very tiny.

In fact it's incredibly unlikely that you'd ever hit anything at all.

This gets into something called "Olbers' paradox." It's a simple proposition: If the universe is infinite, doesn't every possible ray drawn from any point eventually intersect the surface of a star?

The answer is no, because of how geometry works. If the universe were *Euclidean,* in which the distance between points is a function of nothing but the coordinates of those points, then yes, eventually all rays would intersect a star. But the universe isn't Euclidean. The distances between points are a function both of the coordinates of the points *and of time.* In particular, the distances between points *increase* with time uniformly throughout the universe.

If you *froze time* and considered the universe as a "snapshot," then yes, any ray you might draw from a chosen point would eventually intersect a star. But you can't freeze time in reality. In reality, the metric of the universe is expanding, meaning a ray that propagates away from a point at the speed of light will almost certainly *never* intersect a star.

As for the other question about how you'd notice a black hole, you'd be able to see it from light-years away. Black holes found in nature are surrounded by luminescent infalling matter that emits a ton of radiation in the X-ray band. Because of these accretion discs (as they're called), black holes tend to shine like beacons in the night.


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

[User] ELI5: If pasta is made of the same things (flour, egg, water), whats the point of the dozens of shapes?

[Assistant] It's about the sauce. Sauces cling on to each shape differently. Lighter sauces coat long pastas well. Tube shaped and ridged pastas work well with thicker sauces because they can pick up the sauce better. Buttery sauces are best with filled pastas. There are many great online guides. You should check them.


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

[User]
ELI5 Why do people seem to age so incredibly fast after a traumatic experience?

For example a woman I know seemed to have aged at least ten years in a very short time after her grandchild died in an accident.

[Assistant] Cortisol, known as the "stress hormone", causes all sorts of inflammatory responses throughout the body, which contribute to the aging effect. When you add in the psychological implications of the trauma (depression, guilt, etc) that change the person's affect, the combined result is that the person seems ages older than they were.


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

[User]
Are there any factors that have actually been shown to affect which sex a baby will be when born?

I've heard of anecdotal reasons like mother's diet but have there been any serious studies on this topic?

[Assistant] There is one common proposition that sex during ovulation is *very* slightly more likely to result in a boy, while sex a few (2.5-3) days before ovulation, is *very* slightly more likely to result in a girl. This is because x sperm live longer than y sperm, but swim slower. Sex during ovulation means the faster y sperm will have a greater presence at the egg during fertilization. Sex before ovulation means that some of the y sperm will have died off, leaving a higher presence of x sperm. This is called "Shettles Method." However, remember that the odds are still very close to 50/50, and methods like this have a significant lack of non-anecdotal evidence. There is no known morphological difference between x and y sperm, according to the British Medical Journal.