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How are nutrients/chemicals in food dispersed to where they are needed in the body? | For example, how does the calcium in milk you drink find its way to enamel in your teeth, or anticoagulant chemicals in medicine reach the blood stream? | Almost everything is extracted from food in your intestine and directly transferred to blood. There are lots of blood vessels right next to your intestine that make that work.
(The only exception is fat, which is extracted from food in your intestine and transferred to your lymphatic vessels and *then* transferred to blood.)
From there everything goes to the liver, which removes a bunch of things that are toxic, dumps them into bile, which is then dumped back into your intestine and eventually excreted. After filtering, the liver transfers everything that's worth keeping into your main circulation.
(Fat is again an exception; it bypasses filtering in the liver and goes directly to your main circulation)
Once in main circulation, the nutrients are spread all over, and cells that need them pick them up as they go by. (There are lots of simple and complicated ways for cells to pick up nutrients, so there's a whole another complicated story buried in there, but that's the gist of it.) | 32 | 123 |
ELI5:Why are Hindi and Urdu considered different languages, and not dialects of the same language? | From what I can tell, most native speakers of one language can understand the other, and they share most words/grammar structures. Why are they separate languages and not dialects? | depends on who you're talking to. a linguist would tell you that they are not even dialects, but registers of the same language (hindustani). they're correct: hindi and urdu are mutually intelligible with the main differences being vocabulary.
urdu takes a lot of vocabulary from persian and arabic due to the influence of muslim leaders. hindi, however, has decided to replace this vocabulary with words coming from sanskrit.
politics play a huge role in the hindi-urdu split: urdu being the language of pakistan (despite the fact that most pakistanis speak punjabi natively, and urdu for most is a second language acquired in school) and hindi being the language of india (despite the fact that india is one of the most linguistically diverse places in the world, and english being one of the mainly used languages in education and commerce). in the last century, india and pakistan have grown to have separate identities due to religious and political reasons.
also, many hindi speakers cannot read the urdu script, and vice versa. not because they can't learn, but because they simply never did. so, in a place like canada where a lot of people speak either language, it makes sense to have one message in hindi and one message in urdu.
keep in mind that both hindi and urdu have standard forms, often taught in schools. however, people don't tend to speak standard hindi or standard urdu; instead, they will speak their own regional variant of this hindustani language. in writing, however, the standardized forms are quite common. | 15 | 21 |
ELI5 How do the medicines like paracetamol or ibuprofen work? Do they help the brain by making it ignore the pain (suppressing) or by actually fighting the cause of pain? | Ibuprofen works by stopping an enzyme from creating chemicals called prostaglandins that can cause pain and inflammation. Paracetamol does that a little bit too in your brain, but we don't completely know how it works. | 36 | 38 |
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My professor asked me for something that should be so simple that I can’t mess it up, but here we are. | Hi, all.
I’ve just completed my first class toward obtaining my master’s degree, and it went really well. This whole “being in grad school” thing is extremely new to me, so I apologize if the answer to this question should be painfully obvious and I’m just not getting it.
My professor asked me if he could have a titled copy of my annotated bibliography from a presentation I did so he can use it for reference in future classes.
Does this mean he literally wants it just the way it is except I should change the title to something more fitting than “Annotated Bibliography,” or does he want me to add a bit of context surrounding the project as well? Maybe something resembling an abstract?
I would email him and ask, but he’s busy wrapping up our final grades, and I don’t want to deter that whole process.
Thanks in advance for any answers! | Put the title of the presentation at the top along with your name and then paste in the annotated bibliography. Easy and done.
(A helpful way to start answering these questions on your own is to anticipate what the person wants it for. In this case, I’m guessing your professor wants a copy for his files, but doesn’t want 1,000 files on the desktop, all with the unhelpful name “Annotated Bibliography.“ How would you want it titled if _you_ were looking for it?) | 53 | 24 |
CMV: the gender equality activism is a sign of tunnel vision privileged and entitled communities suffer from. | Current gender equality fights are strongly focused on evening the gap in typically high tier jobs. These are available only to people from families who can afford college education for their daughters. Such families are typically, although not exclusively, white. This side of pure gender oriented activism completely neglects the inherent problem of POC access to higher education.
While many fight for a broader equality, the lion’s share of the discussion is purely focused on gender. As such, it is hypocritical for not highlighting the much bigger issue of inequality across communities rather than gender. | First of all, the gender equality movement is about a lot more than just the gender wage gap. Gender equality isn't even just limited to the feminist movement, but feminist activists fight against a lot of things, including the prejudice faced by people of colour in accessing higher education, which is compounded by gender. Just because the gender wage gap is a major issue doesn't mean that other problems within the movement aren't prominent too.
Also, the second half of your argument seems to suggest that you think gender inequality only affects the gender wage gap, which is just downright wrong. Gender plays such a huge factor in inequality and prejudice experienced by everyone, to such a deep-rooted degree that a lot of people don't even realize how confined and limited they are in their choices and lifestyle because of gender prejudices. Gender inequality and prejudice is a major, if not fundamental component of general inequality, and it is an area that has as great need to be focused on. Income inequality and race-based prejudice are not devoid of gender-based inequality.
Just because feminist activists fight against the gender wage gap doesn't mean they don't also care about other issues that involve different people. | 28 | 33 |
ELI5: What is meant by a "Negative income tax"? (xpost from r/askeconomists) | I have a fair idea how such a tax works (In theory anyway), but I'm having trouble putting it into words. I have an exam on Wednesday and may have to write a paragraph or two on the topic. If anyone here could help it would be much appreciated | Consider this example, taken loosely from Friedman's "Capitalism and Freedom."
1. Decide a cutoff income, say, $10,000 per year.
2. Above the cutoff income, taxes work as normal. You take your income, subtract $10,000, and pay the usual rate on the remainder.
* Say the tax rate is 20% and you make $110,000 per year. Your taxable income is $100,000 and you pay 20%, so your tax bill is $20,000 and your take-home is $90,000.
3. If your income is below $10,000, you receive half of the missing income as a subsidy
* If you make $6,000, then you're $4,000 short of the cutoff. You receive a check for $2,000, and your take-home is $8,000
* If you make absolutely nothing, you're $10,000 short of the cutoff; you receive a check for $5,000, and your take-home is $5,000.
* You're paying "negative" income taxes, because you're receiving an income subsidy
That's the basic idea. It's a replacement for the welfare system; instead of giving out food stamps, housing subsidies, and other sorts of aid to low-income people, we just give them cash.
| 27 | 26 |
ELI5: Why are employers the ones providing insurance under Obamacare? | In the wake of all of craziness following the Hobby Lobby ruling earlier this week, I'm very confused as to why employers are involved in this at all. Are all employers supposed to provide healthcare? Why is this even an issue in the first place?
Also, I'd like everyone to stay as politically neutral as possible, please! | The story for the current system in the U.S. has its roots in WWII. There were so many people needed for the war effort and it was difficult for companies to compete with the government's hiring. Companies increased wages to try to entice workers but the government then put a temporary ban on wage increases. The companies' work-around for this was to offer health insurance (non-wage benefits), which are tax deductible for companies, in addition to wages in order to entice workers. The employer-based system stuck and at this point it would be a monumental undertaking to switch to another system. | 13 | 26 |
Can temperature decrease in a closed system while entropy increases? | For example if I have a bowl of water at room temperature, it will slowly evaporate, will that increase entropy while decreasing temperature, or will the pressure increase keep the temperature the same? Is there some other way to do it? | A sufficiently interesting example: if you have an isolated vessel, with a wall separating it into two chambers, and you have a real (ideal doesn't work) gas in one of them and vacuum in the other, when you remove the wall the gas expands to fill all the chamber. This is called free or Joule expansion.
Entropy increases because this process is obviously irreversible. Temperature changes; for almost all gases in most conditions this is a decrease (though there are a few exceptions), in that case here's your example.
Note this cannot work with an ideal gas, as these have U = 3/2 NkT, so that since U is constant (as the vessel is thermally isolated and no work is ever performed on the gas) then also T must remain constant. | 59 | 207 |
[Marvel/DC] How does superhero marking work? | For example, I was reading a Fantastic Four comic, and Reed was eating Hulk Smash cereal. It got me wondering.
Do they have to ask for permission to do things like that? If so, how do companies get certain characters to agree to it? Maybe a guy like Superman would do it, but I doubt Batman would even respond to the request. So how would they be legally able to use his likeness to sell toys or plushies? Wouldn’t they be afraid that they’d get sued
Just curious. | Well, in order to copyright/trademark a name or likeness you either need to reveal your secret identity or have the money to hire a lawyer and set up an LLC or something to hold the trademark for you. The company you have holding your trademarks would still need to pay you in some way. So there would be a money trail to follow.
So yea, if you started selling knock off Batman stuff, you could probably be sued, but that would open the hero up to the possibility of being outed. | 26 | 34 |
ELI5:Can someone ELI5 the difference between a Will, Trust, and an Estate? | Can someone ELI5 the difference between a Will, Trust, and an Estate?
Edit: Thank you everyone for the explanation! | A will is a document that describes how an estate should be handled once the holder has died. It often will talk about how much money his wife and kids get, who gets the house, etc.
A trust is a type of account that can only be withdrawn from for specific reasons. Usually rich people make one for their kids. So if they go bankrupt and all their money gets taken, their kids still have a ton because it belongs to them. The rules vary but usually a kid can withdraw from it to pay for college and put a down payment on a house or start a business, but the dad can't withdraw from it to buy himself a boat, even though it was his money that went into the account.
An estate is everything someone owns, but usually this term is used after they died. They might own houses, cars, a business, and a bunch of cash in the bank. The estate will be used to settle any outstanding debts to creditors and then enacted according to the will of the deceased. | 28 | 30 |
Was working at Jimmy John's today when I customer came in and was severely allergic to cucumbers but could eat pickles, how's that possible? | Top clear up people saying he just said this to get us to 100% not put cucumbers on his sandwich he had us change gloves and cutting boards. Also said he used to be a manger at JJ and couldn't handle cucumbers | Food allergies are often caused by an allergic response to a protein. Proteins are very large molecules made out a long chain of chemical groups called "amino acids." These chains are "crumpled up" into a 3D shape, and the exact 3D shape is what the body recognizes as an allergen. If the protein is unfolded, then the body may no longer recognize it. If a protein is exposed to heat or to acidic conditions, like they would in the pickling process, it can unfold and lose its 3D shape. | 6,867 | 6,317 |
Has any significant problem of modern philosophy ever been "solved" in the sense that most scholars agree on one position, or is it always an ongoing argument and a multitude of opinions? | edit: thank you to everyone for your answers! Many interesting takes and references. | If you take a theory/position in philosophy X and ask "Is X true?", then that's arguably a problem in philosophy. And if X has received some amount of attention in philosophy it's a significant one. So you'd 'only' have to look for positions which are incredibly unpopular, then most scholars agree on the position that "X is false".
If you look at the often cited philpapers study, you can find a couple of positions which the editors deemed significant enough to list as an option but have less than 5% support, so presumably >95% would answer "no" to "is X true?".That would include skepticism about the external world (4.8%), idealism about the external world (4.3%), relativism about knowledge claims (2.9%), and something called sense-datum theory about perceptual experience (3.1%). | 69 | 118 |
CMV: Use of unethical research is not in itself unethical | Let us assume that someone - let's call them Dr A - conducts unethical but otherwise sound research that provides useful information or insight into a problem, say a disease. If someone else - let's call them Dr B - uses said information in their research on the disease, moving forward understanding and contributing towards a cure/treatment. Dr B conducts his research with all appropriate ethical concerns excluding the ethical concern about Dr A's research methods.
There seems to be an idea that in using Dr A's research, Dr B has somehow committed a moral wrong. This is explored in a wide range of media - Star Trek TNG and Voyager are both good examples - but while they establish why the initial research was unethical, none have done an especially good job of showing why \*using\* such research is morally questionable.
Obviously, all research should be conducted as ethically as possible, and unethical behaviour should be punished appropriately, up to and including criminal prosecution for especially egregious or inhumane behaviour. I'm even open to the idea of researchers being fired for major ethical violations, with the details of the case made public so future research institutes can see and make it harder for such researchers to be hired (assuming some fair standards are implemented). However, once that is done, why should the research itself be judged by any other standard?
The only real arguments I've been able to find that support this position are:
1. Using such research is itself a validation or support for the methods used to gain such research. This I think is a weak argument - if Dr A is criminally prosecuted and punished, and Dr C sees this, he's going to be pretty leery of replicating Dr A's methods, since he presumably doesn't want to go to prison. And to Dr A, I wouldn't imagine someone using his work is much comfort.
2. That since Dr B - and by extension, those who his work helps - benefits from Dr A's research, they are somehow culpable in Dr A's choices. This is very weak as well in my view, since Dr B, much less the other people, usually had no way to interfere with Dr A's choices, so they are apparently morally guilty by something they had no role whatsoever in or control over. It also raises the question of how far removed do they need to be. If Dr A does unethical research, which informs Dr B's research, which helps people, are the people "contaminated" by Dr A's unethical behaviour? What if there are more researchers in the chain?
I really can't see any arguments in favour of the idea of using the research being unethical. So I turn to you guys to help me fill in my blind spots. Thanks in advance! | For scientific theory to be robust, experiments which confirm the theory need to able to be replicated. It's the cornerstone of peer review, and prevents scientists from fudging their results.
An unethical scientist comfortable with torturing a particular subset of the population, could just as easily make up results to indicate that the subset is biologically inferior.
No-one would repeat the study because torture is unethical, and if you allowed scientists to use the study, then suddenly everyone thinks the subset is inferior forever, with no way to disprove it. | 13 | 20 |
How do scientists know an animal can see colors we humans can't? (And vice versa) | Yesterday I read a comment that said that shrimps can see colors humans can't see, don't know if it's true, but I wondered how they can know that, I mean, they can't see the color. And also there's the belief that dogs see in black and white.
Sorry if I'm saying bull crap :) | The number of colours we can see depend on the number of color-specific receptors we have in our retinae (cells called cones in animals). Humans have blue, green, and red detecting cones. The mantis shrimp you are referencing are known to have receptors for several more distinct colours, each with a characterized absorption spectrum (how sensitive each is to different wavelengths of light). So we can know how many different colours they can pull out of light, despite never being able to understand what those colours may look like. | 90 | 86 |
[Cyberpunk: Edgerunners] What was Lucy pick pocketing? Are those chips some form of wallets or something else? | Not sure if those were wallets... or if she's just selling implants. | Datashards containing money.
Datashards can contain all sorts of information. videos, images, schematics, braindances etc...
They are also used as a tool for holding and transferring currency. Most people have multiple slots that they can slot datashards into. One of them being a datashard they use as a wallet.
They likely don't contain the entirety of a persons savings and are more for day to day use. As a netrunner, Lucy looks up her victims information and forcibly ejects the datashards without the victims knowing. | 28 | 21 |
ELI5: Why are humans so bad at giving birth? | Women die in childbirth fairly often, even in developed countries. Without proper sterilization, babies are subject to infection at birth. Even if all goes according to plan birth is considered one of the most painful things a human goes through in their life. Why are humans so bad at reproducing? Other animals just pop out a baby and keep going on with their day. | The orientation of the human pelvis and location of the birth canal are a consequence of humans evolving to walk upright on two legs. It's not very conducive to having children, but boy don't we look cool standing up straight. | 241 | 157 |
Is the Crash Course Economics series a good way to learn economics? | I would say yes, although it will primarily help you with understanding academic economics, in that it helps you pass your economics classes, specifically in regards to the non-math based side of economics. It’s a good starting point, and they did a great job of teaching the basics while making it interesting and funny. They even do a good job of touching on political economy.
It doesn’t necessarily delve into mathematics or equations relating to Econ, but there is a good bit of topics covered through an Econ lens that you can actually learn a lot. Go in with an open mind, and expand deeper with more college level discussion when you’re ready! Good luck, and have fun. | 18 | 87 |
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In Marx’s writings, what is the distinction between concrete labor and abstract labor? Why is this is important for his larger critique of the commodity form? | What do you think? | Concrete labor is what goes on in the act of producing things. Qua concrete, it is always labor of a particular kind - harvesting, hammering, driving, data-entering, etc., and it is measured by the actual amount of time that passes during the labor process.
The most plausible interpretation of the concept of abstract labor is that it is, as the name suggests, an *abstraction* from the concrete character of various types of labor which is accomplished in the exchange relation. In an exchange society, money sets all commodities (in various proportions) potentially equal to each other. So, e.g. one pack of cigarettes = $20 = a copy of *Das Kapital.* In setting various commodities, which are products of heterogeneous labors (e.g. cigarette-rolling and book-binding), equal to each other, the exchange relation practically abstracts from the concrete, particular character of the labor that went into the production of these commodities.
Okay, but this seems a little strange - why talk about it? What's the point? Well, at least one of the things Marx wants to draw attention to here is a particular feature of capitalist society. In capitalist society, people do not consciously, collectively decide how the whole of society's labor should be allocated. Instead, private firms carry out their concrete labors, and it is only by having their products purchased on the market that this labor can be *retroactively validated* as part of the whole social labor. If the products do not find buyers, this labor will have been "socially irrelevant" so to speak. So, what Marx wants to draw attention to is that a society of generalized commodity exchange engenders a sort of contradiction between the concrete and the abstract: we have concrete private labor which, through exchange, is able to count as abstract social labor.
Ultimately, these considerations play a very broad role in Marx's thought. For example, he suggests in places that the political form of the abstract equality of persons derives from this abstract equality of labors in the exchange relation. How exactly that works is a little too much to get into here. | 33 | 64 |
[Judge Dredd] What about other, non-criminal areas of the law? | OK mods, I'm hoping that, like a Judge, you'll allow me for a bit of an indulgence. I'm making the argument that /r/AskScienceFiction can potentially expand into /r/AskSOCIALScienceFiction. And so, my question:
OK, so my knowledge of the Judge Dredd universe is limited to the 2 movies and maybe a panel or two shared on message boards. So I had a question about the comic's universe. Particularly when it comes to other areas of the law. Like clearly Dredd and his pals are all in criminal law, but are there judges for the other areas of the law, like for traffic violations, business law, family law, etc? and is it as quick and dramatic as criminal law? Like when two people are getting a divorce and they are fighting for custody of the child, does a Judge just bust into their house, grab The baby out of the crib and chuck it like a dodge ball at the parent he thinks deserves it most? | This is a list of divisions and bodies under the auspice of the Judge System in the Mega Cities:
* Street Division (normal Judges)
* Riot squads
* H-Wagon crews (aerial units)
* Heavies/Manta Tank crews (artillery)
* Vice
* Academy of Law
* Psi Division (judges with psychic powers, encompassing Exorcist Judges and the Department of Magic)
* Special Judicial Squad or SJS (internal affairs)
* Tek Division, a.k.a. Technical Division (scientists)
* "Wally Squad" (Undercover Division)
* Space Corps
* Public Surveillance Unit (PSU)
* Black Ops
* Defence Division (army)
* Public Relations Division
* Accounts
* Diplomatic
* Traffic
* Med Division
* Fire Division
* Meat Wagons (corpse disposal, often using civilian auxiliaries)
* Township deputies (mutant deputies drafted to police Cursed Earth townships)
* Holocaust Squad (teams of disgraced Judges who undertake suicide missions at times of extreme peril to Mega-City One)
Very rarely would civilians seek out Judges for civil disputes, especially when the bulk of the Judges' considerable resources are tied up in criminal cases. Even then they are several undermanned thanks to both their high failure rates of recruits from the Academy as well casualties rates for Cadets and Street Judges. | 44 | 50 |
Eli5: How do historians/scholars translate a totally unknown language when they don't know any of the words meanings? | I've always been curious about this as, to me, and my limited understanding, this sounds impossible and a recent documentary prompted the thought.
It's about the ancient sumerians ([its incredibly well done and there's not a single mention of aliens](https://youtu.be/d2lJUOv0hLA)) and apparently they had a language completely new and unique to scholars, but somehow we were able to learn really fine details in their language, like the fact that there were several different terms for things like damns, irrigation, reservoirs, etc...
How could we know that? | Most of the time they look for translations of such texts in languages they do understand.
The Rosetta Stone is an excellent example of this. Prior to its discovery archeologists and historians couldn't read ancient Egyptian hieroglyphs or script, but the Rosetta Stone contained an inscription in both ancient Egyptian forms of writing AND in ancient Greek, which is a language they DO know. From there it was all about putting the pieces together to rediscover this ancient writing system.
There are, however, some ancient languages we still have no clue how to translate. | 128 | 211 |
ELI5: Why is being inbred often associated with deformities of the body/mind/etc? | It has to do with genetics, mutations, and dominant/recessive genes. If a mutation happens in a person's DNA, they can pass it on to their children. But, if the child gets one "good" piece of DNA from one parent and one "bad" piece of DNA from the other, it's possible that the mutation won't show up or cause problems. But, if two people who are related have a child, there is a higher chance that both parents inherited a mutation from a common ancestor, and the child might get TWO "bad" pieces of DNA and end up with serious problems. | 18 | 22 |
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[Mass Effect] What are some everyday, non-military applications of the Mass Effect? | The mass effect has many applications and usages throughout the galaxy, ranging from utility, military and pleasure.
One such application is the one used on the citadel to help simulate an atmosphere on the wards. While it frequently uses oxygen reclamation to provide fresh air, the breathable air in the streets of the wards only exists up until a height of seven metres. After that, the vacuum of space exists unexposed. The only way to travel beyond the seven-metre safe zone is in a flying car.
Omnitools - whether combat-oriented or civilian models - are another application, as the mass effect is used to use moisture to refract light and produce a holographic display around the user's arm. It is also used to provide haptic feedback in computer interfaces where a mass effect field would push against the user's hand... although this requires sensory peripherals, either gloves that need to be regularly washed or small microchips implanted into the tips of fingers to interface with.
According to Cerberus Daily News, a newsfeed ran through the Mass Effect 2 title screen, there was also a form of sport called Densing that was created when element zero's market price crashed, serving as a form of Sumo wrestling. Anti-gravity chambers are also abundant in asari space and Peebee turns the evac shuttle in the ship from Andromeda into one such chamber to float about.
Finally is the primary usage in manufacturing - forging under high pressure gravity field in order to produce extremely durable metals. | 53 | 45 |
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ELI5: Why are pet fish okay living in perfectly clean, filtered water, when they normally come from natural bodies of water that are not so pure? | Firstly, because it's not just about cleanliness it's also about oxygen content. Natural bodies of water will absorb oxygen from the atmosphere, but a small fish tank, without some kind of filtration system, will end up depleted of oxygen.
Secondly, it's a specific kind of "impurity" in your fish tank that hurts the fish. Their water is filling up with their own feces. If any natural body of water were as full of feces as an unfiltered fish tank, those fish would be sick and dying too. Other kinds of impurities are more tolerable for the fish, not harming their health even though they wouldn't be good water for you as a human to drink.
Also though, natural bodies of water that become heavily polluted will eventually see the fish and other wildlife in them die. Even parts of the ocean can become so polluted that they are "dead zones" where few if any organisms live. | 131 | 112 |
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Would businesses benefit by raising wages so that workers can afford to spend more money on their products? | I heard that Henry Ford paid his employees relatively high wages for this reason. | Firms that pay businesses wages higher than the equilibrium rate is known as **efficiency wages**. Studies have shown that workers are motivated to work harder if they receive a wage higher than the equilibrium rate.
- By paying a wage above the market wage, the firm raises the costs of workers of losing their jobs because alternative jobs may pay only the market wage (think opportunity cost here).
- The increase in productivity that results from paying the high wage can more than offset the cost of the wage, thereby lowering the firm's cost of production. | 31 | 34 |
ELI5: How do games render particle effects so much faster than programs like after effects? | I understand that while games have preset effects, programs needs to calculate every particle. However the games particle effects arent the same everytime which I guess means that each particle is also calculated. How is it that a game like overwatch can calculate tens of effects more than 60 times a second while the same computer takes a minute to render a simple particle effect? | Part of it is the hardware used. Every computer has two main pieces of hardware which calculate things, graphics (gpu) and central (cpu). Each are specialized in some kind of processing and have a performance advantage at it. This is like having both a sedan and a truck. While both can take you shopping, a sedan is easier to park and the truck can carry large objects better. Going to the mall may work better the sedan and going to a home improvement store may need the truck.
How programs leverage those resources is up how they are written. More recently, programs do a better job using the GPU when available and can spread the load across both accordingly, but games surely do have on average a larger focus on the GPU than other programs. It just so happens that the GPU is generally much more efficient for particle physics.
The other part is how the particles are created and calculated. Games cheat in a lot of places to make it fast, as a stuttering image is far mor noticeable and negatively impactful to the viewers experience than cutting corners in particle calculations and only having an ‘approximate’ version of what should happen. Given that after effects and the like don’t have this real time constraint, they can take their sweet time in getting everything just right.
A really good example of where this makes a difference is in lighting. Games will do something like ‘hey here’s the sun, it’s bright, and these surfaces face the sun so they’ll be bright too’. This is most of the way there, as in an outdoor, daytime scene, the sun is the brightest object. What it misses is that all surfaces reflect light to some degree. Mirrors obviously reflect a lot, but every object you see does too. That’s why you can see it. Calculating how bright something should be based off of not only the sun’s direct light, but also the faint reflections of everything around it gets to be very complicated. If you want to get it really close to accurate, that computation takes a while. If you want it to be live, you may only get to 90% accurate. After effects will start from how accurate it needs to be and work backwards for how long it will take, where the game will effectively work the other direction and set the time you have and cut corners to get something in that time frame. | 25 | 33 |
"Don't do an unfunded PhD" - always true? | I guess I'm not the only one who has heard this piece of advice (perhaps you may call it a 'rule'): if you're not being funded, don't do a PhD.
What is the basis for this? If you can afford to do it, why not go ahead? Has anyone here self-funded their PhD?
EDIT: Having encountered a good number self-funded PhD students here in the UK, I am wondering if perhaps this is more true of US institutions. Does anyone have any insight on this? | There are exceptions to every rule (like what if you are an heir to a giant corporation, and want to study history of art for 5 years). But generally, yes, it's a good rule of thumb. If you are competitive, and the field is competitive, you probably can find a funded PhD. If you are not competitive (for the field of your choice), it's probably a good idea to become competitive before you plunge head-first into a PhD, as things are not likely to improve drastically once you are in the program. It's a big decision, for most folks. | 71 | 60 |
ELI5: How are unwitnessed behaviours (such as an adult bird building a nest the chick never saw the construction of) passed onto the next generation? | Nest building is a species-specific innate behavior, birds don’t learn how to build a nest, they’re born with an instinctual drive that lies in their genetics. It’s also why different species make different types of nests which be radically different in construction.
For a contrast, brown bears are NOT born knowing how to fish, they have to both learn from their mother by watching her, and also they develop their own unique style. Each bear fishes in slightly different ways, some like to wait under the water, others prefer to wait at the top of a fall for a fish to practically leap into their mouths, others wait behind the boil of the fall to pick up fish that failed the jump, some use jaws first and others use paws. | 9,818 | 8,267 |
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[superman] Aside from the Anti-Superman stuff, is Lexcorp a legitimate business? | Lexcorp is a large corporation with many areas of business, including construction, pharmaceuticals, military supply, and many other fields. The majority of it operates mostly within the law like any other corporation, but there are some parts that operate in shady or downright illegal areas, such as weapons sales to unfriendly nations or terrorist groups or illegal research into genetic engineering.
So the answer to your question is definitely yes and definitely no. | 123 | 139 |
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What gives things color on a molecular level? | It has to do with how compounds interact with visible light. Colors occur when a substance absorbs or refracts specific frequencies in the visible spectrum, which depends on specific physical or electronic properties of the compounds that vary from compound to compound.
Since visible light is a rather arbitrary and narrow range, many compounds don't interact with it, therefore the "default" is to reflect all of the visible light (making it appear white) or allow all visible light to go through (making it colorless). | 15 | 39 |
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Why can solar panels only convert roughly ~20% of sunlight received into energy? What will it take to increase this percentage? | I recently learned that only ~20% of sunlight received is converted into useable energy. Why is this? What will it to take to receive more energy from the solar cells?
Thanks! | Check various science sites - there is a lot of research into improving the efficiency. There are some solar cells that have achieved over 40% efficiency (although these are still pretty expensive).
BTW, even though 20% seems low, did you know that a gasoline engine only delivers about 15% of the energy available in the gas? | 10 | 33 |
How do space vehicles know how to orientate themselves? (Specifically unmanned spacecraft) | Do they use a gyroscope system? Or the planets magnetic field?
(I got curious watching a Scott Manley video on YouTube, he talked about the pitch and yaw of the recent ‘Astra’ rocket launch and I realised I’d never questioned the method - hard to get a straight-forward answer out of google) | Commonly-used sensors are: coarse sun sensors, gyroscopes, magnetometers, star trackers, and GPS receivers. Common actuators are: reaction wheels, magnetic torquers, thrusters, and (less commonly) control moment gyros.
Coarse sun sensors are simply photovoltaic solar cells. Arrange several of them around your spacecraft, and you can get an idea of where the Sun is.
Gyroscopes (aka inertial measurement units, inertial reference units) measure angular rate. There are several technologies available: MEMS gyros (which you might have in your phone), fiber optic gyros, ring laser gyros, and hemispherical resonating gyros.
Magnetometers measure the magnetic field, like a 3-D compass.
A star tracker is like a video camera that can compare its image with an internal star catalog, and so figure out where in the sky it is pointing. This is the most accurate off-the-shelf sensor in common use.
A GPS receiver tells you your position, not your orientation. But position is a good thing for a spacecraft to know, too.
Reaction wheels exert torque by action/reaction. Spin one up clockwise, it makes your spacecraft spin counterclockwise. Use several, properly arranged, and you can control all three axes of your spacecraft with precision.
Magnetic torquers are big electromagnets. Energize one, and it tries to line itself up with the local magnetic field. You can use this to exert torque on your spacecraft. Magnetic torquers aren't precise, but they are very commonly used in combination with reaction wheels in low Earth orbit.
Thrusters are rockets. Push mass out one way, the spacecraft moves the other way. You can exert both forces and torques with thrusters, so you can change your orbit as well as control your attitude. (Everything else on this list is torque-only.)
Control moment gyros (CMGs) are like reaction wheels except different. Instead of exerting torque by changing the wheel spin rate, you keep the wheel spinning at a constant rate and use a gimballed mount to change the CMG's orientation in the spacecraft. Spinning masses resist having their axis of spin re-oriented (look up "gyroscopic stiffness"), so the result is a torque on the spacecraft. CMGs are bulkier, more power-hungry, and more expensive than reaction wheels, but they provide orders of magnitude more torque. If you are very agile (like some remote imaging spacecraft) or just huge (like ISS), CMGs are worth it.
I hope that gives you enough of a start that you can get more traction with google. | 20 | 15 |
Eli5 - If a person with Leukemia donates blood to a normal person, how come the other person doesn't contract Leukemia also? | Leukemia is a bone marrow disorder. That is where the disease originates from- the over production of certain leukocytes. Most leukocytes don’t have that long of a life, so the excess WBC would not cause disease in the recipient | 61 | 33 |
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CMV: Shaming someone for a lack of empathy is just as bad as shaming someone for any other inborn trait | It seems like it isn't uncommon for people to resort to using "lack of empathy" as an insult, especially when discussing social issues. It's my understanding that empathy is largely an immutable personality trait that has little to no component of personal choice involved.
Trying to shame someone for not being empathetic is no different than trying to shame someone for any other innate trait of who they are, be it sexuality, race, or physical size.
I personally see the act as even worse when it comes up during conversations regarding social issues because it's most likely to be said by someone who would condemn insulting someone based on some part of themselves they can't control.
From a perspective of social power, I will go ahead and point out that shaming those who lack empathy is an institutionalized process that comes from the idea of empathy being fundamentally good, as opposed to it just being one aspect of the human personality.
So... CMV.
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | You can argue that almost anything is an "immutable trait," such as prejudice, tendency towards violence, crime, etc. It seems that the logical extension of your view is that we should never criticize anyone for anything even if we perceive it as bad (or criminal). Are you saying we shouldn't criticize people for being tactless, shallow, petty, greedy, selfish, or prideful? To paraphrase MLK Jr., we should judge people on the content of their character, rather than the color of their skin. You are arguing that these are entirely analogous. | 31 | 16 |
ELI5: Do college students get paid for breakthroughs/discoveries in science, archaeology, etc? | It seems quite often that I'll read an article with a statement like "Students at ____ University recently discovered a new gene" or something along those lines. Would these students get paid for discovery (doesn't have to be directly through the school, also from various organizations) or are they not compensated? | No that's not how it works really. Even professional scientists aren't explicitly paid on a "per-finding" basis. They are usually paid some salary just for doing their work on a daily basis much like most other people are (there may be other pay structures but that's not what you're asking). When a scientist discovers something it basically allows them to *publish* the findings and be the first to publish it. That allows them to add it to their credentials when they want to apply to a more prestigious job or if they are applying for what are called "grants" where you get funding from an external source other than your employer that goes, typically, directly to funding your research. This is similar in collage students - having a first finding of something adds quite a bit of prestigiousness to your credentials, allows you to publish etc. They can't apply for grants typically but they can apply to "scholarships" which are sort of similar.
In summary, typically you don't get paid on a "I discovered something" basis *directly* but it does help to get better jobs and be more prestigious. | 102 | 113 |
What makes a programming language "good" for certain tasks? | For example, I've heard that Python is a "good" language for data analysis, and C# is for building apps. Theoretically, all programming languages should be able to do the same things, so what makes one better for a certain task? Is it the standard libraries? | A range of factors, and a lot of opinion.
Some things are just hard requirements. You need to use a language that compiles to native machine code if you want to write an OS kernel. You can't really write a complete OS from scratch with no other code in Python or Javascript. Interpreted languages like that need a bunch of extra code at run time to make them work. But, you can't load that extra code without already having at least some minimal working OS of some sort. So, you will see a lot of C in OSdev. On the other hand, if you want to run code in a browser, you probably will use Javascript, because that's what browsers will run.
Sometimes it's just a totally arbitrary availability of tooling. If some wacky professor writes a really great library for doing a particular task, then whatever language they write it in can suddenly become the best language for that task. This kind of happened with Ruby when the Rails framework was released. As a bare language, it's pretty similar to Python. But for certain kinds of webdev, Ruby is much more convenient because people wrote better tools to do it in Ruby.
Performance can make a difference. Pedants will point out that a programming language isn't inherently slow. Different implementations of the same language can vary wildly. Sometimes a slow language is fast, and sometimes a fast language is slow. But in practice, Python is generally slow and C++ is fast. So, you see C++ used in a lot of high performance stuff like 3D rendering and games. (Or, at least game engines.) Maya is written in C++, Direct3D games use C++, etc. Lots of the modules that get used in a slow language like Python are written in C or C++, so you can o fast work with a slow language.
Static vs. dynamic typing, and a few other features effect the convenience of a language. Python has nice simple Syntax, dynamic typing, and a bunch of useful libraries, so it tends to be an eminently convenient language. Loading JSON into Python is very convenient because of the dynamic typing -- fields can be added to objects at run time when you load a JSON file. Doing something similar in C++ is a pain in the neck, and has to be done with a bunch of indirection, specifying some classes ahead of time, and maybe some template weirdness, depending on exactly what you want to do. So, loading some data and doing some processing (possibly using a fast module which is implemented in c++) tends to be super convenient in Python.
Static strong typing can be useful for for making big projects more reliable by writing pedantically type safe code. It's a pain to write such code, and a pain to use. But it eliminate a class of bugs that is really easy to write in Python. And, a static type language can be analyzed for likely bugs ahead of time. Python often explodes in completely unexpected ways at runtime, because of that dynamic typing you can never be 100% sure what somebody is going to pass into a certain function. With C++, passing the wrong type of object to a function is generally just a compiler error, so you can't ship a program to a user with that type of mistake in such a static types language. Ada is no longer terribly common, but it used to be used in a lot of military and aerospace projects because it is even more enthusiastic about strong and static types than C++ is.
Does this help clarify? | 34 | 17 |
ELI5: What is Stoicism? Is it like "I don't give a f**k, bring it on" thinking? | Stoicism is mainly about learning to cope. Originally it included a whole theory of the universe about fate, determinism and free will, theology... it's been called fatalistic and pessimistic. But we can adapt the main philosophy to the modern day.
Stoics believe your reaction to events in the outside world is what controls your state of mind. So it's not that you're frustrated because your boss yelled at you. You're frustrated because you think she has no right to yell at you, or because you think she was unfair, etc. The point is your own thoughts created the frustration.
Stoicism helps you to embrace the idea that things are not always going to be as you wish they were. It doesn't mean you don't care about anything. It means you develop patience to remain calm and emotionally healthy. Then, you are able to work towards making things better productively. A stoic doesn't hate, doesn't get frustrated, holds no grudges, and can never be found at the computer at 3:04AM because "someone is **wrong** on the internet". | 832 | 745 |
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If photons are smaller than atoms, why don't they pass through solid matter? | Aren't atom's mostly empty space, between the nucleus and the electrons? Shouldn't photons pass through those spaces and penetrate basically any form of matter? | The closest thing to "size" for a photon is its wavelength. Different types of light have different wavelengths: x-rays have really short wavelengths, while radio waves have really long wavelengths. Visible light is somewhere in the middle.
If the wavelength is small compared to whatever we're dealing with, then you can treat the photon like a particle - i.e. it's a "bullet" that either hits, misses, or bounces off whatever we're dealing with. Visible light is 100s of nanometres in wavelength, which is way smaller than say, a window, and so you can think of it as a bunch of light "particles" flying towards the window: some of the particles go through the window, some bounce off the frame etc.
But if the wavelength is *big* compared to whatever we're dealing with, you really need to treat the photon like a wave - i.e. instead of a bullet being fired at a solid object, imagine a bunch of objects floating around in the ocean being shoved around by a water wave. This is the case for visible light and atoms. Visible light is 100s of nanometres in wavelength, but atoms can be even smaller than 1 nanometre. So you can't really "miss" with visible light - the photon passes through hundreds of atoms at the same time. This means there is definitely some interaction going on, and so the photon can be changed a little by the atoms, and that allows you to "see" the atoms when the photon hits your eye. | 130 | 222 |
What exactly is "Information"? | In many other posts they say that information can not travel faster than the speed of light, but what exactly is information and what can be considered not information. | At its most fundamental, information is any propagation of cause and effect within a system. The degree to which the the past state of one part of the system can be known through observation at another part of the system. Effect can only propagate at the speed of light (since nothing can go faster).
Information is carried in a "signal", which is the variation of any physical property, over time, against the backdrop of random variation (entropy).
Different fields discuss information in different contexts. E.g. in physics you'll probably be talking about the propagation of cause and effect. In information theory, you're probably talking about formal logic, statistics, signalling, bandwidth, [edit: also, should include language, coding, compression, cryptography, etc.] etc. | 798 | 1,600 |
ELI5: Why do sugar granules dissolve faster in liquids when you stir them with a spoon, than just leaving it to sit? | When something starts dissolving in water, it increases the amount of stuff dissolved in that particular part of water. The more stuff is already dissolved, the less likely it is that more dissolves into it.
If you just leave it sit, diffusion is the only process that carries the dissolved molecules away so fresh water without anything dissolved can come by to pick up more molecules. If you stir, you artificially accelerate the carrying-away of dissolved molecules, making more space for new ones to dissolve faster. | 32 | 24 |
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ELI5: How do game makers know what computer specs you'd need to run the game? | My guess is that they use different PCs and make the game at different quality but that'd take too long so idk. | Games undergo an optimization process to ensure they operate reasonably well on a reasonably inexpensive machines. This involves improvements to the code of the game to make it run more efficiently and avoid unnecessary operations, as well as providing the lower-quality textures and various filters that make up the "video settings" menu in the game.
During this process they typically target a few different common specs that they want to support well - for example, many games are optimized to use about 3GB of VRAM at their highest 1080p settings, since the GTX 780 is an extremely popular card among 1080p gamers (while 4GB and more is usually necessary for 1440p or 4k.) Of course, it is also important to provide a good experience for everybody using a GTX 680, 770, or one of the various R9 AMD cards with 2GB VRAM.
CPU performance is pretty linear - it's not difficult to ensure the game runs on an i7, i5, FX-8XXX, and FX-6XXX and figure out at what point the game stops working. Most games are optimized to run on 8GB of RAM.
| 12 | 34 |
ELI5:What role does hydration play in being tired? | Water is great for moving things around in the body, such as blood. If you don't have enough water your muscles can't move quite as well, and (for a personal anecdote) you could even get a headache as well as feeling tired. | 11 | 25 |
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ELI5:Where does innate shyness come from? | Never really knew any simple scientific explanation behind shyness which is hindering a lot of people from become the best version of themselves growing up and even as adults..
Is being shy hereditary or is it developed from childhood?
Some kids start off super shy for some reason and some kids are considerably more confident than others.. Does it have something to do with someone's upbringing in their early stages in life or the environment they live in also has an influence? | This is kind of a hard thing to address because personality traits can be genetically predisposed, environmentally activated, and socially learned.
Let’s say little Jimmy is born with genes that say he’s going to be outgoing. If Jimmy were to be subject to abuse or neglect during his developmental periods, his body could actually disable these genes and reconfigure them to make him shy - this is an area of research called **epigenetics.**
From a social standpoint, behaviors can also be learned through a psychological phenomenon called classic conditioning, which is how your brain learns to relate an unrelated thing to something more relevant to you - say, you’re a prisoner and someone brings you a meal every day, but this person has a distinct type of sound when they walk. You would eventually associate this sound with food. The same concept applies to behaviors. If you’re outgoing and you’re repeatedly belittled for it, or one **significant** negative response occurs, your brain will associate extroverted characteristics with that negative response.
To sum it up in a more general way, anything psychological is also biological. Nurture (environment and social conditions) works on nature (genetic predispositions). | 17 | 30 |
ELI5: Why are there so many different bolt and screw designs (Hex wrenches, flathead, etc.) ? Wouldn't it be easier to have one universal tool? | No, All have different uses, and in turn are optimum for different types of jobs. Moreover cost can also be a driving factor for what to use. And lastly whether your screw driver, impact driver, hammer drive, etc... will slip should also be considered.
For instance Lag Bolts (Giant screws with hexagonal 'nut' ends) are great for anchoring 2x4 shelfs that will support ALOT of weight. Since they can be 3", 4" or 6" and beyond - you need to use a socket set with an impact driver to really make sure that bolt will not slip.
Alternatively, if you were framing a deck, and needed 2.5" screws Philips will work just fine - but green deck screws should be considered (costly) and the t-25 bit "star shapped" will not strip easy (and again will cost more).
Right tool for the right job, bro. | 80 | 218 |
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[Star Trek] why do the starships engage in combat from such close ranges? | I understand the federation is on peacekeeping mission and normally don't expect combat but I imagine it would pop up. | Most starfaring races in contact with the Federation tend to use phasers or similar for their primary weapons. These are unguided weapons, and given that they're essentially particle streams, they propagate somewhat slower than the speed of light.
What this means is that you have to lead your target, not shooting at where he is, but where he will be when the beam has traveled the required distance. The problem there is that as range increases, the target has more time to change course and not be where you predicted him to be when you fired the weapon.
With the kind of acceleration possible with inertial dampers, and a computer capable of carrying out a number of 'random walk' style maneuvers, it becomes very difficult to hit a ship with a phaser at medium to long range. | 64 | 82 |
ELI5: why is it impossible for animals to grow to certain sizes without collapsing under their own weight? If you just scale everything up 1:1, why can’t they just function normally at increased sizes? | Imagine a cube with each edge of length 1.
The sides have an area of 1 x 1 = 1.
The volume is 1 x 1 x 1 = 1.
Now scale it up "1:1" so all the edges are now length 2.
The sides have an area of 2 x 2 = 4.
The volume is 2 x 2 x 2 = 8.
So despite you scaling all the lengths equally "1:1" by 2.
Area went up 4 times, and volume went up 8 times.
Things like strength of bones are how wide they are, so they vary by area.
Stuff like weight depends on how much stuff there is, so they go up by volume.
And as you can see, area goes up a lot slower than volume does.
This is called the square-cube law, because the sides are squares which go up a lot slower than the volume.
Bone strength is just one factor.
Stuff like heat loss is skin area (goes up with the total area of the sides), heat generation is how much organism there is ( goes up with volume)
And many other factors like oxygen flow, etc. | 90 | 32 |
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Since both a WiFi signal and light are electromagnetic radiation, can I simulate the range of my WiFi Access Point by replacing it with a bright light in a pitch-dark night? | I would probably need to leave all doors open since the WiFi signal has no trouble to shine through them, but it seems that concrete and brick walls are opaque for both WiFi and light. | No. All materials have different absorption and scattering properties of electromagnetic radiation, and these properties are different for different wavelengths of light. Visible light and radio waves will not have the same behavior, especially since houses are such irregular objects made of so many different materials. Furthermore, you wouldn't simulate the correct power or signal-carrying properties of the light either. | 92 | 162 |
ELI5: A common model for gravity’s effect on space is a sheet of elastic material with some stuff put on it to make wells and such. But how does that apply in 3D? | The whole "rubber sheet" model is effective for the limited number of dimensions that we can visually represent. If you wanted an accurate representation of the effect of some mass (e.g. a planet) on spacetime, you would need to make in at least four dimensions (three for space, one for time). The problem is that we cannot draw a truly four-dimensional (or *n*-dimensional) picture - we exist in and directly perceive three spatial dimensions, while time is perceived as sequential differences.
The solution? We exclude something. In the case of a drawing like "the Schwarzchild radius of a black hole," this looks like a "bottomless" funnel around an infinite mass. In the rubber-sheet depiction, it appears as a depression in an otherwise flat surface. Trying to add dimensions simply does not work - even if the underlying physics is true for the additional dimensions - and so to represent a system completely we need multiple such reduced depictions. | 19 | 18 |
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If you could start your PhD life from scratch, what one thing would you do differently? | Hindsight hour! | 1. Start therapy. Mental health is the most important thing and imo the best determinant of success in grad school and in life. Also student insurance is sweet.
2. Network network network. Don't assume you will stay in academia. And don't look at the PhD as an end in itself. Think about what you want once you are done and prepare for it. You might change your views along the way but better start the process early than in the last 1 year.
3. Stick to a 9-5 routine if possible and actually socialize on days off. Don't let anyone push your boundaries. People will try to make you feel bad for not slaving away. Recognize it for the dysfunctional way of life it is. Work smart and work consistent. This is your degree, don't follow anyone blindly if you don't agree. | 305 | 302 |
ELI5: How come a round camera takes rectangular pictures? | The lens of a camera is circular, but the image sensor of a camera is rectangular, whether it is film or a digital sensor. Imagine if you draw a rectangle inside of a circle... This would be your image/picture. | 10 | 21 |
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[Economics] How have women entering the workforce in increasing numbers the past 50 years affected the economy? | I see two main effects, the increase in labor supply lead to an increase in productivity, GDP, etc., while also meaning with an increase in supply, average wages would decline since there are more available workers. I realize the more people working does cause more jobs to be created, but I'm not sure that is at a 1 to 1 ratio.
I don't have any data or studies to back this up, I'm wondering what research is out there. It seems to me that back in the 1950s, the nuclear family ideal of a man working and providing for his wife who took care of the kids was more than enough money. That seems to be much less true today.
This is based off of [a Reddit comment](http://np.reddit.com/r/TrueReddit/comments/18of5w/netherlands_women_work_less_have_lesser_titles_a/c8gkax2) | You're right about the labor supply effects, but remember that the increase in household income also led to increased demand. So quantity [of generic widgets] certainly increased, but we can't say what happened to price. | 10 | 45 |
ELI5: How Mercator Projections are better for navigation than other projections (like equal area projections)? | I've read that although the Mercator Projection distorts the relative size of continents, it is still used for navigation.
What would the same plotted course look like on the Peter's Projection versus the Mercator Projection? | The Mercator projection preserves angles in a way that navigation paths are shown as straight lines.
That makes it very practical for navigation: measure the angle on the map, take course on that direction, and you will arrive to your destination.
Preserving angles also makes the Mercator projection to preserve local aspect ratios. That means that although landmasses appear deformed if they are too far apart (Greenland is actually as "tall" as Australia, not as big as Africa), they tend to appear with more or less the correct shape themselves. This is the reason why Google maps uses the Mercator projection. | 125 | 195 |
In economic terms, what are the benefits and drawbacks of the profit motive? | I don't know if this is the question I want to ask, but I'm gonna roll with it and try to explain what I'm getting at.
In the modern economy, for the most part, the goal of any business is to generate a profit. Some care about profit maximization more than others. My perception is that, at least in some industries, profit maximization has led to negative effects on the consumer/society. News organizations prioritize sensationalism and spin because it gets them more clicks or views. Tech companies have been making their products with planned obsolescence in mind and making them near-impossible to repair, leading to an increase in electronic waste and forcing customers to buy new products cyclically, because that makes more profit than building a product that will last. Fast fashion companies churn out disposable clothing produced in sweatshops with no regard for their impact on the environment because, again, it's more profitable.
I can accept that regulation is necessary to curb these negative effects. And I don't have a problem with profit as a general rule; if a bakery makes a cake with $0.25 worth of ingredients and sells it for $5, I don't think that's necessarily a bad or immoral thing. However, I hesitate to "endorse" profit because it's clear that profit maximization can be detrimental to society in at least some important circumstances.
Rather than get into a moral or ethical debate about whether profit is "good" or "bad," I want to know what economists generally think of it. Does the profit motive lead to a more efficient allocation of resources, on-balance? In what contexts does it work? When is it inappropriate? What function does it serve in the economy? Are the examples I listed profit maximization or something else? Am I missing something important here? | First, the benefits of the profit motive: When firms are profit maximizing in competitive markets, and markets are complete, then goods are allocated efficiently. Formally, this is the first welfare theorem, and if you're interested in the details you can find proofs online or in a textbook (e.g. Mas-Colell). Informally, this is Adam Smith's Invisible Hand. The profit motive induces firms to produce goods that are desired, and produce them at low cost.
What are the drawbacks? In reality the assumptions of the first welfare theorem do not hold. You have identified several problems which violate the "markets are complete" assumption. If there are externalities without associated property rights, then firms will not internalize all the costs of their activities. Over-pollution (in some forms) is a classic case of this problem. Usually this problem would lead profit-maximizing firms to produce too much, although if there are positive externalities they might produce too little.
The second assumption is perfect competition. If profit-maximizing firms have market power and can affect the price of their goods, then they will tend to produce too little of the good.
In summary, the profit motive brings the economy close to efficiency when markets work well, but can lead to over- or under-production when market power or externalities (or other problems of market incompleteness) are large.
I hope I've answered your question. Here are a couple more to think about. Clearly, some markets are incomplete and some firms have market power, so the first welfare theorem does not literally hold. How can we solve some of the problems? Governments sometimes use regulation to do this: anti-trust laws constrain market power in some cases, and environmental regulation prevents some problems with externalities. Are there other options? If you are interested in these sorts of questions, measuring and solving these problems is one of the main jobs of IO economists. | 28 | 33 |
ELI5: What are 'fuzzy mathematics' and what are its applications? | 'Fuzzy' is a term used to indicate that you're treating normally discrete phenomenon in a continuous manner.
For example, consider classic set theory. Let's say you have a classification scheme of 'fruit', 'vegetable' or 'meat'. You look in your refrigerator and sort everything you see into one or more of those categories. Each item you sort is fully within a category or fully outside of it. If something is a 'fruit', it is 100% a fruit.
A 'fuzzy' version of this would be to permit something to only be *partially* within a category. So something might be '50% a fruit'.
In terms of its applications, that's harder to say. 'Fuzzy math' is pure mathematics rather than applied mathematics. It's an intellectual framework for discussing such phenomenon. As a result, you can describe all sorts of different systems with fuzzy math, but almost no one actually uses fuzzy math to build those systems. | 171 | 296 |
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ELI5:Could we really build Star Wars sized space ships? | Say, something that was several kilometers long and could house tens of thousands of people. Is this feasible with existing materials science?
EDIT:
Let me clarify: I'm assuming cost isn't a factor, nor is getting the material into orbit, etc. Let's just build the damn thing up there. | Simply designing and building the structure would probably be the easy part. Objects in space don't need to worry about gravity nearly as much as objects on the ground. It's sort of like a whale... a whale is fine in the buoyancy of the ocean, but stick one on dry land and they'll crush themselves under their own weight. If it will always stay in space, it shouldn't be too bad of a feat.
The bigger problems would be things like simulating gravity, propulsion and the real big one... getting that much material to space in the first place. | 89 | 147 |
How to start reading Heidegger? | After reading some of Husserl's work, I'm eager to start my Martin Heidegger studies. Is there any recommended way to start, any particular book? I can't even find a good website with the chronological guide of his works. Thanks for the help. | One could start with *Being and Time* directly, though you will want a guidebook to read alongside/beforehand. The other option is to read *Basic problems of phenomenology* and/or *History of the Concept of Time* which are two transcribed lecture-series from around the same time which cover a lot of the same ground as Being and Time, but they are quite a bit clearer. | 16 | 26 |
Could somebody explain why the US is not on the gold standard? | And for what reason it is more useful to us as a country? and perhaps what exactly our current system it? | The Gold Standard, as the name suggests meant that all money issued by the U.S government was effectively a certificate that one could redeem for a fixed amount of gold. The U.S Government could only print as much money as it had gold reserves, because every 'dollar' had to have a corresponding amount of gold stored somewhere for which it could be redeemed.
The advantage of this system was stability, and resistance to inflation. A government couldn't print absurd amounts of money and thus devalue their own currency (like the pre-Nazi German Government did) and money retains its value because it can always be traded in for gold.
There are a number of disadvantages though:
- Economists believe that being on the gold standard makes a recession much harder to escape. If your government can only print as much money as it has gold, it can't inject money into the economy during times of weakness.
- There's only a finite amount of Gold in the world. The amount of money circulating in the U.S alone right now is more than the value of all the gold that has ever been mined in the entire world put together.
- Economists believe that what you want for a currency is a slow, gradual rate of inflation because it encourages people to spend, invest or deposit their money rather than store it in a mattress. A gradual, predictable inflation rate is most easily achieved without the gold standard.
**What the U.S has now:**
The U.S currently operates what is called a *fiat currency*, which is a fancy way of saying "not tied to a specific commodity like gold or silver. Basically, the U.S dollar has value because the government says it does. The government is willing to accept these specific pieces of paper as taxes and charges.
The actual 'value' of the U.S dollar is determined by the market and the laws of supply and demand. Traders exchange their currencies for U.S dollars at the best possible rate they can get. The going rate at any given time is the value of the U.S dollar.
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Which is more important for growth in the modern economy: consumption or production? | I'm sure this question has been asked a million times by economists and many studies have been performed to try to find the answer. What do current mainstream economists believe? | Over long time horizons, innovations on the production side drive economic growth.
Over shorter time horizons, with the capital stock and state of technology basically fixed, consumption (and other components of demand) play a larger role in determining aggregate growth.
In short, to put it crudely, it isn't an either/or -- we need to understand both supply and demand. | 13 | 15 |
When will we be able to industrialize graphene and when will the consumer likely see graphene in household products such as computers? | I currently work in a research lab where several members are studying the properties and manufacturing techniques of graphene. There is a lot of research in the topic right now, and this is mostly because of increased media exposure and "buzz" surrounding the material.
The graphene that we can grow today is small and expensive, that's the bottom line. Making large scale devices of material that is incredibly delicate is hard. You may be thinking "but graphene is super strong!," and it is. But maintaining a certain phase of material at conditions we consider "normal" is not straight forward.
One leading researcher in the field is Dr. Jamie Warner at Oxford. Look up some of his stuff if you're interested in real science on the subject of graphene.
This is probably not the answer you wanted, but there is no good way of addressing this question. Often times research is non-linear. Also, we may or may not get to that point. There are other promising avenues for technology processing that we are exploring.
TL;DR: Not anytime soon. | 487 | 1,084 |
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How mixable are different types of plastic? Like PET and HDPE? | Some polymers have an affinity for each other and mix well. Polycarbonate, some styrene copolymers, and PET Mix well. This is driven by the chemical structure. Think that some are more polar, water like and others are less polar or oil like.
However most polymers by themselves are typically not mixable. When mixed they form a blend that has poor adhesion and thus poor strength. it only takes a small amount of incompatible polymer in a mixture to make the material useless. Which is why it is important to have clean recycle streams.
The outcome of a good mixture is to get desirable properties of both materials in a single material. For example high temp stiffness with rubber impact resistance.
To make them mixable the two polymers are typically reacted to together to form a copolymer that acts as a soap allowing them to mix. ABS ( LEGO plastic) is a mixture of polybutadiene (rubber) and Styrene-acrylonitrile copolymers. The rubber provides break resistance while the styrene copolymers provide stiffness.
Super tough nylon ( weed whacker string) is a mixture of nylon with ethylene-propylene rubbers that contain an acid group that reacts with the nylon’s amino group to form the copolymer.
There is a whole industry that tries to figure this out.
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ELI5: Why do some sodas (like Coke) produce a lot of foam when it's poured into a cup, from say, a can, while other sodas (like Sprite) don't produce nearly as much? | the most important factor in how "foamy" a soda acts is which of its ingredients raise or lower surface tension. Aspartame promotes the formation and persistence of bubbles, as do certain preservatives.
The combination of multiple foam-promoting ingredients and circumstance is why Diet Coke reacts so energetically with Mentos candy. | 24 | 50 |
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Why do computer parts work faster or better when they are cooler? | Circuits and wires are made of various metals, which are conductive (electricity moves through them quickly/easily). When electric current flows through a wire, some of the energy is lost as heat, causing the wires to get hotter. Heat reduces the ability of a conductor to conduct electricity, so the hotter your computer gets, the slower it gets and the worse it performs. Computers that are running are constantly generating heat that needs to be removed. That's why all computers have fans, to keep cool air moving over the circuitry. | 16 | 51 |
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In the United States, I think that the religious based marriage should be removed and replaced with secular based civil unions. CMV. | I believe that in the United States, marriage should be removed as it follows religious rules and doctrine in most parts of the US. I believe that this is absolutely in the jurisdiction of the church and should remain there, allowing churches to marry people as they deem appropriate. I believe this because of our separation of church and state.
Civil Unions that are based in secular principles should replace the marriage institution. Any adult able to consent to a contract would be able to form a union with another individual. (Or other individual**s**, but that is a different discussion.) This would grant the same benefits marriage currently has.
It may seem like just a name change, but its a fundamental shift in philosophy. Change my view? | Marriage in the legal sense is already independent from matrimony within the Christian faith and similar ceremonies in other religions. It's already possible for two individuals of opposite genders (or the same gender, in some areas) to get a marriage license - and become subject to all the legal statuses marriage entails - independent of sexual involvement, religion-based marital status, and similar factors. | 32 | 65 |
I believe that everyone is selfish and there is no true kindness in people. CMV | This could be stemmed from my poor social experiences or from what i learnt in my psychology diploma, and soon recently came to the conclusion that there is no true kindness/altruism whatever you call it.
For a behavior to happen, there needs to be some sort of motivation. Intrinsic or extrinsic, there is a need for people to behave a certain way. Extrinsic motivation is plain and simple. The most common is money. People work for money, people steal for money, people who do charity gain acceptance of society, which in turn lets them earn more from their enterprises since the company they represent is more accepted. That's what i believe.
Even if there is an intrinsic motivation, the person definitely have to do it for his or her own cause. For example, a generous person who makes self-sacrifices for others could gain satisfaction in his own mind that he's done something "good" and the social acceptance which he gets would motivate him to do more kind deeds, since society as a whole promotes pro-social behaviors.
Or someone sees an injustice and steps in for the victim. The person seeing the injustice could just be annoyed at the situation and in order to resolve the annoyance he steps in to help the weak. I would also think that that's just a method for the person to deal with some internal unsolved issues to make himself/herself feel better. For example, a man who was a bully victim steps in to fight off some bullies because he did not have the courage to stand up to them when he was younger. Because of that, he may feel a sense of accomplishment and satisfaction in himself. Thus, since there is a personal gain, I do not see pure kindness.
So basically even when someone does something good or kind, i would attribute it to his or her need to be socially accepted or the self-satisfaction, and when there's personal gain from displaying pro-social behaviors, I do not believe that people can have pure kindness. But hey, that's just my opinion man.
Edit: ok basically, I believe that there will always be personal benefits when someone does some kind deed that is beneficial to others. Without the personal benefit, nobody will do anything solely for the benefit of others.
No matter how I looked at things, I can always attribute acts if kindness with some form of personal gains.
I may not have phrased it correctly saying that everyone is selfish. I just tend to be quite avoidant at times and think the worst of people. Lol
Edit2: so many people talked about positive and negative values. So my question is: how do you determine the TRUE values of one's motivations for an action? | What about the economic principle of marginal utility?
In short, the idea goes: you buy an item -- lets say it's an ebook reader, and you have a large marginal utility (you love to read), say it has a number value of 100. What if you bought another ebook reader of the same type? Would that value still be 100? What if you bought 20 of them? Would the 20th kindle or nook be still worth 100? Probably not, right?
Well, if you do charity work for intrinsic value, at some point the marginal utility could be bordering on zero right? At some point you'd have been recognized as a very kind person in the community and everyone recognizes that -- what if you keep doing charity work at near zero marginal values? Why would you keep doing that? You have next to nothing to gain (you've already gained what you could) but you keep doing charity work. Is that not an example of selflessness?
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Why does the speed of light being constant for all observers imply spacetime is non-Euclidean? | I'm a layman when it comes to physics, so the question may be ill-formed and/or incorrectly framed. I'm trying to really grasp the nature of (flat) spacetime. I'm watching [this video](https://youtu.be/iBTez-nTKes?t=272), and she says how there's no way for the speed of light to be constant for all observers if spacetime were Euclidean.
If I take the speed of light being constant for all observes as axiomatically true, then I feel like I'm close to grasping flat spacetime, but I don't really understand why this statement has to be the case. I'm guessing there's a simple mathematical proof that shows why the spacetime is basically a series of hyperbolic contours -- can someone point me to that? | Let's say you're standing next to a railroad, and a train approaches you going 100 m/s. You see its approaching speed as 100 m/s.
Now, let's say you're on a train next to the railroad mention above, you're traveling in the opposite direction at 50 m/s. Now you see the other train approaching you at 150 m/s.
Now, let's substitute a beam of light for the first train. Standing next to the railroad, you see it approaching at 299,792,458 m/s. Next, you get on a train going 50 m/s. In this case, no matter which direction you look, you measure the speed of light as exactly the same velocity. In other words, you don't add your speed to the light speed.
So, in the first example, your frame of reference made a difference in the speed of the oncoming train (this is consistent with Euclidean observations). But light speed is always the same, regardless of the frame of reference. And this is why it is non-Euclidean.
This is not at all intuitive (but it has been verified experimentally countless times) - but it is the difference between Euclidean and relativistic observations. | 1,328 | 3,215 |
ELI5: Why does rhyming in poems and songs appeal to us? | Repeating patterns are attractive to many forms of intelligent life, certainly most mammals. See a thing, remember it, see it again and recall it. This is done with all signals, sight, touch, smell, taste, and hearing. Think about the advantage of an animal that recognizes the rhythm of a predators charge - they can run away without needing to see it. They survived and got to have kids, and some of their kids could do the same thing. This is the basic mechanics of evolution.
Animal brains only have a few main drives, survival comes first but then there are things like hunger. The animal that feels hungry will be driven to look harder for food, which may be an advantage. Hunger and pain are closely related, but what about pleasure? The opposite side, what if the animal is driven by something that makes them feel good. This seems to be something that we see in very intelligent animals - they like playing. They get positive signals that drive them towards survival traits.
Humans are smart communal creatures. We love patterns deep down in our brains so much so that we learned to play with them. We played with them so much we made music, art, and language to share what we thought and felt with other humans.
Rhyming appeals to us because it’s a game we play with patterns. | 60 | 61 |
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[Marvel] What is the difference between a dimension and a realm (examples) how are asgrad and the dark dimension different | A dimension is a physical existence separated from all others by dimensional barriers. Usually requiring specific technology to move in or out of.
A Realm is a political structure, is much the same as a nation or state. There can be more than one realm in a dimension but sometimes a realm encompasses and entire dimension, leading tot he confusion.
At times a realm may leave it's home dimension (like Asgaurd left for earth during the "Dark" Osborn period. The realm odd Asgard was in like Idaho and the dimension where it always was. | 31 | 36 |
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ELI5:How do corrective lenses correct one field of vision (nearsighted or farsighted) without distorting the range we can already see? | I am nearsighted and everything goes VERY blurry about six inches from my face and beyond. My glasses / contacts are a single prescription (not bifocals or trifocals). Wearing them I can see everything clearly. How do they let me see far away while NOT distorting my current vision? | When you are nearsighted or farsighted the lens in your eye is either too powerful or too weak. If you're nearsighted, the lens is too strong, it focuses an image too quickly so that its in front of the retina. The corrective lens diverges the light coming in more, spreads it over a wider angle, than it would be, so the too powerful lens focuses the image where it should be.
Why does this affect vision at one distance only? Because the lens of the eye is actually made to change shape and change focusing when little muscles pull on it. Your eyes change how well they focus naturally if you're looking at something near or something far away. If you're nearsighted, the range of focus you can get is all close up, and not enough far away. So corrective lenses shift the whole range to farther distances, so that you can get a more "normal" range of distances covered. For farsighted its the opposite.
The eye is designed to be able to focus on a range of distances, corrective lenses shift that range as a whole. | 28 | 73 |
We know about colour blindness, where certain colours cannot be seen properly and get compensated for by the other cones in the eye. Is there a similar condition for taste buds where people will experience vastly different flavours from a 'taste-normal' person? | There are some particular foods that are experienced vastly differently than others. Probably the most famous is that some people find cilantro to be a very favorable taste while others are almost repulsed by it, reporting that it tastes "soapy." | 35 | 46 |
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[Avatar LA/LOK] Which element do you think is the most powerfull? | In your opinion which one has the most power and most potential?
Edit: I'd say earth has a lot of versatility, but some of y'all are saying air so I agree now that I think about it you can do a lot of things with air (fly,breathe,) | Earth and metal can change landscapes and protect their practitioners.
Water can flow and crash, heal and in extreme cases control.
Fire and Lightning are said to be destruction incarnate.
But air? Well, everyone needs to breathe. Ever stop and wonder why airbenders are pacifists? | 158 | 122 |
ELI5: What’s the difference between internet browsers. Aside from appearance and customization, what causes the mechanics of different browsers to work better on certain websites? | So, technically the components of websites (HTML, CSS, and JavaScript primarily) are standardized, but it's still up to the browser makers to actually implement those standards. These standards are being updated all of the time, so some browsers that are quicker to update and designed to be fully featured (e.g. Chrome, FireFox, Edge) will support these updates while older browsers or ones designed to be light won't support these updates. A web programmer has to know what sort of features are supported while writing code in order to support their target web browsers. Sometimes programmers will target a specific browser and not update their website to work well with other browsers. | 22 | 39 |
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ELI5: Where do uploaded files go? | Okay, had a big discussion last night with 3 more friends about the nature of the Internet. Since our perceptions were a bit altered, and there where no engineers in the room, this turned into an all-out debate.
Sorry for the misconceptions, but here goes.
When you have, for example, a 2MB file in your computer (without a web connection), that file has a "physical" element right? Somewhere in the hard drive, something is modified because of that file. But, when you connect that machine to the Internet, and you upload that file, where do those 2MB go? I concluded that the Internet was like an infinite and intangible hard-drive on which infinite information could be put. But HOW CAN THAT BE? I simply have no idea what I'm talking about, I'd love for anyone to explain it for me. Like I was 5, of course.
Thanks a bunch!
**EDIT: Great and clear answers guys, I certainly appreciate it!** | Part of why you are having conceptual difficulty here (which others have addressed) is because the internet isn't just a big sea of information: it's a network of other computers. Any data "on the internet" is hosted from a specific computer somewhere. | 58 | 80 |
ELI5: Why are "verbs of being" irregular in so many languages? | In my own studies of Latin, French, and Swedish and limited forays into German and Spanish, I have not come across any languages with a verb of being that had a regular pattern or conjugation.
EX:
English: (To be) I am, you are, (s)he is, etc. I was, I shall, I will...
Swedish:(att vara) Jag ar, du ar, hon ar...
Latin: (Sum, esse, fui, futurus) Sum, es, est, sumis, estis, sunt....
French: (Etre) Je suis, tu es, il est... Je serai....
I suppose the short answer is that languages are linked (Latin to Romance languages, etc.) but why does such a pattern perpetuate? What are some languages without that? Is this linked to other language trends?
| Words that are used frequently tend to be more grammatically irregular in most languages. "To be", "to have", and "to go" are all very common words and are irregular in a lot of languages.
Languages often change by either contraction or analogy. In contraction, speakers end up saying things with different accents or speak quickly and the form of the word changes that way. With analogy, speakers copy the forms of other words (e.g., you may not know what an "estuary" is, but you know that the plural would be "estuaries" by analogy). Contraction tends to lead to irregularity and analogy to regularity. Contraction is also more common with regular words because they are spoken more frequently and as a result there is more chance for contraction and people will recognize them even when contracted. The end result is commonly used words tend to morph more often and become irregular while more uncommon words tend to stay regular. | 11 | 30 |
PhD Advisor Doesn't Let His Student Go on Internships | Okay, I recently got an internship and I need to file my paperwork which requires the approval of my advisor. Here is some background about me and my lab:
I am an international student in an US university and I started my Ph.D. in Fall 2018 and have passed my qualifiers and published a journal paper and am writing my second paper currently. I don't intend to stay in academia after graduating, and I have no work experience hence I applied for an Internship to get jobs after I graduate. It is difficult to get jobs in the US when you have no work experience and are on a visa.
Now my advisor is known for not allowing his students to go on internships. Two of my colleagues in my lab couldn't go on internships as my advisor strongly advised them not to and some of his former students didn't even apply. My relationship with my advisor is positive so far however, I am concerned as to how I can approach him about this. I will send him an email explaining my situation sometime this week as I need to keep the company informed too.
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I would like to get your input on how I should go about approaching my advisor. How I should react in case he says no. What should I say and what should I avoid. Thank you very much for your advice.
Clarification: before joining the lab I have informed my advisor that I will work in the industry and not academia. Furthermore, the funding in the lab runs out before summer and there is no incoming source of money as far as I know.
Thank you all for the responses. I appreciate them greatly.
Update: So, I spoke to my advisor, yesterday and in short he agreed to the internship under the condition that I keep working on our research. He shared his concerns with me, as about 5-6 years ago he had 2 students who did excellent work for him went on interns, one did not come back and the other came back only to graduate within a semester and did not pursue any more research work. I reassured him of my intention to return to the program, and that legally I cannot just take a full-time job after my intern is over as my visa won't allow me to just quit my program and start working for any company in the US. He agreed the intern will significantly help in my personal career growth and will save him some money as he won't have to pay stipend over the summer. While I would have preferred to work the internship alone in the summer, however, getting the research work done will be beneficial to me in the long run. He further emphasized the need to be in a strong position to graduate, by working in the summer and producing more paper I will be in a safe position and can graduate quickly in case he is unable to get funding. I agreed with his reasoning, I do want to finish my degree and achieve my research objectives without having to support myself.
Again thank you all for the kind and supportive advice you provided to me in handling this delicate situation. | It’s pretty early in the year - if you have a good working relationship w him perhaps ask him to go for coffee and ‘advice’ - explain the situation (many US faculty don’t know all the visa rules that international students deal with), and that you have been advised that this would help you post- degree, ‘but you don’t want to leave the lab short staffed for 10 weeks this summer’ — so is there a way to get work done in the spring (etc etc)
In your conversation project a belief that you both want the best for the lab *and* for you / your future - and that you need help figuring out how to do this. | 51 | 64 |
Could anybody please explain what "internalism" and "externalism" are in epistemology in simple terms? | I've read a few articles in various encyclopedias, but they seem to be confusing. Could anyone please explain in Layman's terms what "internalism" and "externalism" are in epistemology? | Internalism is the position that whatever makes the difference between a merely true belief on the one hand, and knowledge on the other has to be accessible though introspective reflection. In other words, in order for your justified belief to count as knowledge you have to be able to determine what makes your belief justified using reflection alone.
Externalism is the position that at least some beliefs that count as knowledge need not be such that their justification is accessible through reflection.
Does this help? | 12 | 20 |
Why don't waterfalls get worn down to gradual inclines? | Waterfalls form where a layer of hard rock lies on top of a layer of soft rock. The soft rock below erodes faster, creating a steep drop, sheltered by a ledge of hard rock above. Eventually, the soft rock starts to erode beneath the hard rock, creating an overhang, which breaks off when it gets too long, creating a new vertical face, so the waterfall gradually moves upstream. | 273 | 231 |
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ELI5: How are certain foods made to be “instant”? Such as instant oatmeal, potatoes, pasta, etc. | Each product is prepared in a different way, but the general strategy is this: Do most of the cooking process, then dehydrate it so it will last in a package, then package it. That way when the customer gets it, they simply have to add hot water which will rehydrate it and finish the last 10% of the cooking process. | 61 | 39 |
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ELI5: Why are some people more prone to being bitten by insects than others? | I'm currently on holiday abroad with my family.
I am being EATEN ALIVE by mozzies, while they all seem to be fine, a bite or two but nothing compared to me (I seem to look like an all-you-can-eat buffet to them). Why is this? I've heard people say that some people are 'tastier' than others - is this true? And why is this?
Thanks! | There are several factors as to why insects - such as mosquitoes - bite some people more than others.
Blood type. Mosquitoes are blood based feeders, and they prefer O type blood groups more than any other. If you are O type, you are between 50-80% more likely to be bitten than others like A,B or AB. Also, about 85 percent of people secrete a chemical signal through their skin that indicates which blood type they have, while 15 percent do not, and mosquitoes are also more attracted to secretors than nonsecretors. The reason for the preference to O type, could be evolutionary, as O was the first and oldest blood group (other types are more recent mutations), so it could just be that mosquitoes simply evolved when that was the only blood group, hence their preference to the familiar.
Carbon Dioxide. Many biting flying insects detect prey using carbon dioxide signatures. We breath out CO2 and they can detect that from over a hundred feet away. Larger people produce more CO2, and larger people tend to get bitten more. Some insect traps utilise this by burning fuel which produces large amounts of CO2, which proves irresistible to them. Pregnant women have been shown to be a particular target, this is qualified by the fact they produce 20% more CO2.
Chemical / Biochemical Markers. Sweat is another attractant, it contains ammonia, uric and lactic acid and all of these are huge attractants to biting insects. Certain bacteria secreted by humans and animals also proves to be very attractive to biting insects. Feet and ankles seem particular effective at producing bacteria that these insects enjoy.
Thermal Indicators. Insects tend to bite warmer people, this is probably correlated to sweat production too. So metabolism plays an important role.
On the whole, genetic factors seem to play the biggest role in who gets bitten and how often.
EDIT : If you don't match the profile of someone who should or shouldn't get bitten there are other factors at play. You may be a non secretor, so get ignored. There are other chemicals secreted by us that also serve as an attractant in our skin and breath, even if you don't sweat much (one for example is octenol). You may also secrete lactic and uric acid without realising it as both can be in our breath. But probably the biggest reason is microbes on the skin, we have 100 trillion of them and the types and combinations vary massively from person to person, your microbe cocktail may just be one of the unlucky biochemical markers that are attractive. | 384 | 657 |
What causes rocks to be such a wide variety of different colours instead of just grey? | Here's an [example pic](http://i.imgur.com/5yqZYLN.jpg) posted earlier in /r/pics. | Different types of rocks or minerals are made up from different chemicals. For example, an Albite Feldspar (found in the Earth's crust) is (Na or Ca)AlSi3O8 and is white or colorless unless it has impurities. It's because these chemicals can be arranged in a wide array of crystal structures (In the Albite Feldspar example this structure is called Triclinic). These structures affect the wavelength absorbance of the rock; and with it, the color we see when we look at it since it's reflecting light it doesn't absorb.
Edit: grammar | 29 | 89 |
Is usage of MIT licensed code looked down on? | Hey, a newb programmer reporting in. If I were to create a website, using someone else's MIT licensed code, would that be hugely looked down on by the programming community?
I can definitely see why it would be, but would it?
The website in question would be for my mother's friend, who wants a website for his services and I would like him to have a nice looking website, instead of the simple, dull looking shit that I know how to code. My creatings honestly look like they're from the 20th century. | Do some light research into what general licensing means. When an artist wants to use a piece of someone else's song, they pay for a license to use it.
The MIT license is a free use license. Read it carefully. If your usage fit within the license terms, which you likely will, then use it to your heart's content.
Reinventing the wheel is stupid, if it's free use it. Give credit if you want/have to.
Edit: let me add as a separate point, know your audience. If a customer sees the site looks similar they won't care. If you make a site for web developers and they see it's basically a default template, they might judge you. Audience is important. | 15 | 15 |
How far from earth do you have to be when you change from perpetual free fall going around the earth to being in zero gravity? | If such a point even exists. | It's not exactly about distance - it's about speed, or kinetic energy. But beyond some distance, the speed you need becomes very small.
If you are above escape velocity, then the Earth's gravity will never be enough to pull you back down. Even though the gravity is constantly pulling you, it gets weaker as you continue to go further away, and it never adds up to enough to pull you back.
As you go further away, the escape velocity you need to escape Earth's gravity becomes smaller. If you are 4x more distant from the centre of the Earth, you need half as much speed. On the Earth's surface, you need to go quite fast - about 11 km/s - to escape Earth's gravity, even if you don't count drag from the atmosphere. From the Moon's orbit, you only need to go 1400 m/s, or about 5000 km/h. Once you get to Jupiter or Saturn, this gets down to 100 km/h, which is much lower than the speeds that planets and moons are moving at. And once you're a light year away, the escape velocity is about 1 km/h.
This is quite a big distance. If there were no other objects in the universe, you would have to get to a significant fraction of a light year away before escape velocity gets to around walking speed. But of course, we live in a universe with other stars and planets, and these tend to move at 10s to 100s of km/s relative to each other. Earth's gravity stops being important mostly because you're closer to something else that is providing far more gravity, or you're moving so fast that Earth's gravity doesn't have time to add up to much. | 33 | 16 |
Admitted to JD-PhD —good idea? | Hi all! Looking for different perspectives and advice.
Was recently admitted to a joint JD-PhD in philosophy at the University of Michigan. I was fortunate enough to receive full funding from both the law school and the philosophy department. So, fully funded for 6 years, and could likely get both degrees in those 6 years.
The law school is being flexible about my start date, so I could essentially order the two degrees however I would like (for ex., could do the first 2 years in the PhD, next 3 in law, final in PhD, or any other combination)
Career goals:
Ideally, I would love an academic career (though I do have doubts about my ability to succeed!). I would be happy to teach philosophy in a law school, or applied ethics and some legal philosophy in a philosophy department. So long as I am doing some philosophy, I will be happy.
That said, I appreciate the idea of having a JD as a backup in case academia does not work out (I recognize the market is tough).
My questions are these: is a joint degree a good idea? If so, how should I go about structuring it? Should I be publishing in law journals, philosophy journals, or both? How would a law school view a joint degree? How would a philosophy department view a joint degree? How can I best ensure good employment outcomes? Any other things I am not considering?
I will also note that I was accepted to Harvard Law School. That is another option I am considering. | Yes a joint degree is an excellent idea if you value research and publishing. It will set you up with good options academically and in law. You should try to publish anywhere and everywhere, but if you're trying to be an academic then target crossover journals that deal with both philosophy and law.
On the other hand, Harvard Law is hard to turn down and will probably guarantee employment in law.
Either way, congrats!! These are huge accomplishments! | 39 | 37 |
GPS requires microsecond clock accuracy in the satellites but the terrestrial receiver accuracy doesn't matter at all. Why is this? | Think of it like a math problem where you are trying to solve for your coordinates (X,Y,Z)
If you know the current time, you can solve this by comparing the signals from 3 satellites, which have a known position and broadcast their current time.
It takes longer for the signal to reach you from satellites that are further than you, so you can compare the current time to the time the signal was set out and determine the distance.
Each satellite signal creates an equation involving X, Y and Z. With 3 equations, 3 unknowns, you can solve for all 3.
This would work if you had a super accurate atomic clock on board.
But you don’t.
So instead, treat the current time as an unknown variable as well. Now you have 4 unknowns. With signals from 4 satellites, you can solve for 4 unknowns (X,Y,Z,T) ..... where T is the current time. | 36 | 24 |
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ELI5: How did the nature documentary planet earth get such incredible footage ? | Are the cameras planted? Some of them it feels as if the camera was on the animal almost- it's amazing that the animals are not bothered by the cameras. | Start with really good camera's and phenomenal lenses. Add in a good documentary cameraman. Tell him to go film nature for a year.
Then trim out 99.99% of the footage and cherry pick the most amazing shots. | 28 | 17 |
Any young adult philosophy book recommendations? I work in an adolescent psychiatric inpatient unit and often certain themes arise in my groups with them. I'd love to set up a group dedicated to introducing them to philosophy and critical thinking. | All of the young people I work with have experienced significant adversity, trauma and deprivation. The psychiatric system in turn hampers them in additional ways. I'm a psychologist with limited philosophy study in my undergrad days and I think a philosophy group in addition could help them cope with the system they are in. Any recommendations would be greatly appreciated! | If you’re thinking about a novel, Sophie’s World is a great suggestion. If you want something less objective then you have to keep in mind that you’re conditioning their beliefs at that age. Nonetheless, there is The Myth Of Sisyphus by Albert Camus. | 11 | 21 |
[Star Wars] How did Darth Maul survive bring cut in half and falling down a massive pit while Qui Gon Jinn got sabered in the chest and died? Wouldn't the saber have cauterize the wound and prevented him from bleeding out long enough to get him to a doctor? | Everyone is answering with medical concepts, but there's a deeper answer: Maul was willing to tap into the dark side of the Force to keep himself unnaturally alive, whereas Qui-Gon instead accepted his death and proceeded to supersede it as a Force Spirit. | 513 | 258 |
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What does the thesis committee talk about when they ask the audience to leave the room? | In my department it is customary during the defense exam that the committee excuse the audience (these days by means of breakout rooms) at the start (before presentation ends) and end (after presentation is done) of the defense exam. They talk for about 5 min each time. I am defending my PhD soon and this issue is playing with my mind a bit more than it should. I wonder if anyone could let me know what is being discussed at these two points of time. Thanks in advance. | Most times we'll discuss your work, your qualifications, quick discussion of any unfinished business. But think of it like a wedding: "if anyone has a reason to stop this, speak now or forever keep your mouth shut." They want you to pass at that point.
Most times they just talk about what you'll be doing next and what lunch is gonna look like. | 52 | 26 |
[Mathematics]Can anyone explain the Riemann Hypothesis in the simplest way possible? | At what points does the function y= x^2 - 9 equal zero? The answer is x=+3 and x=-3. What about y=x^2 + 9? There is no real answer, but the imaginary numbers 3i and -3i solve this, where i^2 =-1.
The Riemann zeta function is a much more complicated function, where Zeta(x)=1/1^x + 1/2^x + 1/3^x etc. Zeta(2) is pi^2 /6, for example. Generally though, x can be a complex number (real and imaginary parts) and its output Zeta(x) can also be complex. There is a different form of it (an analytic continuation), if the real part of x is less than one.
Anyway, for negative even integers -2, -4, etc, Zeta(x) is zero. There are also complex numbers for which Zeta is zero, for example Zeta(0.5+i*14.134...) is zero.
The Riemann hypothesis says that besides the negative even integers, every value for which Zeta(x) is zero has a real part of 1/2. | 12 | 17 |
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[40k]Craftworld bretheren. We have conquered a Mon Keigh world. The Seers demand their subjugation instead of the usual Wailing Doom. How did we craftworld eldar handle a pacified human tribe? | By Khaine we have captured what the mon keigh called a civilized world and slain their astropaths to prevent cries for aid. However a Farseer told me that we cannot slaughter them for they will serve a role in a prophecy that will spare many of our kin many years from now. So we must lord over them.
I knew of how our wretched fallen would do but we Craftworld Eldar are enlightened. What would we do to lord over the Mon Keigh? | Use a light hand and an invisible approach. Choose there new leaders carefully and prop them up, doing as much as possible to remain unseen as you do. Once you have chosen the leaders, you must educate them and train them to seek out your goals. The project will take a great deal of time, many of there life spans and this must be accounted for. The heirs to the world must also be directed, set on a grand path which they have no choice but to follow. After a time, the future will be set in stone and need only the lightest guidance from time to time. In three to four of their generations the battle they lost will be forgotten and the leadership will seem like nothing but loyal imperial citizens when the inquisition arrives. Now on a river only a massive event can turn them from their course and you have seen success. | 20 | 21 |
If you had a properly sized lens completely free of any imperfection, could you build a magnifying glass that could see atoms? | If not, what about large molecules or cells? | No, because the wavelength of (visible) light is longer than the distances between atoms, so they cannot be distinguished are the therefore non-resolvable. 1000x magnification is about as far as light can go, which allows you to see bacteria, but not viruses.
Electron microscopes are instead used because the wavelength of electrons...or something...is short enough to distinguish between two objects at that scale. | 185 | 187 |
ELI5: Since trees grow so slow, and cutting down a tree is almost instant in comparison, how are we able to keep up with things such as paper products? | Decades ago various industries that rely on trees for materials like lumber recognized quickly and easily that although their businesses were sustainable it would require them to actually sustain them. Those industries thought ahead and began planting trees then for them to harvest now.
Most industries that rely on wood use farmed trees that are planted following every harvest and left to grow for as long as it takes. If anything, they create the problem of *too many* trees, or at least too many of the same species in one area, creating a monoculture.
The trees that are *not* being sustained are the forests that are clear cut to be used for something else, usually farmland. It's not the trees, it's the land that isn't being sustained. | 53 | 51 |
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ELI5: Why is there a European and American model for tracking major storms (hurricanes, tropical storms, snowstorms etc) and why are they always so drastically different? | For instance, the upcoming Hurricane Irma path from the EU model is saying it'll [stroll through the Caribbean with decent strength before drastically losing strength and making it's way up the western Florida coast and dying off in Mid Atlantic interior](https://www.google.com/amp/s/www.washingtonpost.com/amphtml/news/capital-weather-gang/wp/2017/09/05/catastrophic-hurricane-irma-now-a-cat-5-is-on-a-collision-course-with-florida/)
Whereas the American model it's saying Irma is gonna fuck shit up, to say the least.
Do they have different mapping techniques?
Which one is more accurate? (i.e. When it snows here Europe tends to be more accurate and drastic)
Why do we follow/use European models in America? Does Europe use or models? | Basically the algorithms used are a bit different as you can imagine weather especially on the scale of hurricanes is complex. Additionally the EU and US use different satellites to get data. In recent years the EU model has tended to be more accurate but that could be a fluke. | 25 | 42 |
Why does our immune system need one or two injections to learn to fight a new threat and many injections to unlearn to fight a perceived threat (e.g. dust mite)? Thanks | The goal of allergy shots is to slowly make your immune system switch from one type of immune response to another. In order to do that, they have to start with a super-low dose of the allergy trigger so that it flies under the radar of the allergy responders and instead gets the attention of a different type of immune cell. You slowly increase the dose of the allergy trigger to build on that process until your immune system turns down the allergy response and instead is more primed to use a different type of responder that doesn’t result in allergy symptoms. If you start with too high of a dose or jump to too high of a dose too quickly, the allergy responders will sense it and trigger an allergic reaction instead. | 1,892 | 3,298 |
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Eli5: If you can represent yourself in court, why can't you have anyone you want represent you? | I got this idea watching the episode of Married...with children where Kelly represents Al. | Well you can, but they'd have to agree to represent you, and be qualified to represent you. You don't have to be qualified to represent you, but you're a unique case... mind you a judge can still decide that you *need* representation and assign you a public defender anyway.
I mean, you *could* ask for Bon Jovi to represent you, but why would he, even if it would be allowed? | 20 | 26 |
What do you think of the tenure track system in the Netherlands? | Hello good people!
I have a few question on the tenure track system in the Netherlands, in general and regarding the new reform.
1. What do you think in general about the tenure track system in the Netherlands?
2. Would you consider it a real tenure? Like, does it give you a job for life?
3. What do you think about the new tenure track system that was adopted very recently (tenure after 18 months and promotion to Assistant professor 1 after 4 years roughly)? About the fact that you don't necessarily get an associate professor position in the long term?
4. The pay scale for professors there is super straightforward but very much lower than what you'd get in North America. Does the work life balance and tenure after 18 months make it worth it?
Curious to know what you all think. | >The pay scale for professors there is super straightforward but very much lower than what you'd get in North America. Does the work life balance and tenure after 18 months make it worth it?
This is pretty much impossible to compare. Work-life balance isn't the major issue, it is the cost of living long-term. When you don't have to save up for your future children's college, you don't have to pay for health care, child care is heavily subsidized, etc. x 100, the math regarding wages is something else.
Also, it depends on how long you plan to stay. 1 year, country A. 5 years, country B, for life, country C.
One way of looking at it is like this: Are the two countries comparably equally wealthy? If so, where do tenured Professors place as percentile of national incomes? If they are about the same, the pay is likely comparable. | 64 | 45 |
How do doctors know the prescription for glasses for babies/children who are too young to do the usual sight tests? | They can map the shape of the eye pretty easily and get about 90% of the way to knowing the prescription. Then they need feedback from the patient for the fine tuning. Babies just can’t give that last little part that doesn’t matter much. | 27 | 36 |
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ELI5: How did fruit transported from colonies to the capitals during the colonial era stay fresh enough during shipping trips lasting months at sea? | You often hear in history how fruits such as pineapples and bananas (seen as an exotic foreign produce in places such as Britain) were transported back to the country for people, often wealthy or influential, to try. How did such fruits last the months long voyages from colonies back to the empire’s capital without modern day refrigeration/freezing? | Besides what a lot of people already said (picking early, losing a lot in the process, iceboxes, greenhouses, etc.), many of those fruits were transplanted to places with tropical weather that are closer to Europe than the colonies, for example, the Canary Islands - they still grow A LOT of bananas to this day | 5,232 | 8,469 |
ELI5: How do scientists know what the global temperature was millions of years ago? | Basically they use a bunch of methods to estimate what the temps must have been like. They measure ocean sediment composition, ice core samples, pollen samples, tree rings, fossilized leaves etc.
Ocean sediments contain different levels of oxygen and different isotopes of oxygen (for example when there is more of a heavier oxygen isotope present it generally means a warmer climate).
Different layers of ice cores have different chemical compositions (including oxygen isotopes), which helps piece together what gases were in the atmospshere, and ultimately the temperatures.
The pollen, tree rings, and leaves contain indicators on how the plants did (how well they survived) at certain times/years which would be due to the different climates/weather conditions, including temperature.
EDIT: Wording | 110 | 204 |
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ELI5: Why do we get the uncontrollable urge to stretch? Why is it connected to yawning and how does it happen? | Stretching helps stimulate circulation and manage muscle tension. Likewise, yawning flexes the ear canal and dislodges excess earwax. It's kind of like an itch. The body has a maintenance issue that needs to be taken care of so the brain suddenly gets the urge to do something about it. The exact connection is complicated but it's sufficient to say your brain comes with a set of instincts on how to maintain the body. It's not complete but it helps. | 24 | 24 |
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[Star Wars] Why are other Force traditions frowned upon or ignored? | From what i've been able to gather, there are a number of Force organizations that the Jedi cannot match in both combat prowess and ability alone. Yet they get no attention even though some of those traditions are superior due to their emphasis on how to apply and access the Force? I understand that the Jedi and Sith were the first ones to be around, but is it really reasonable to say they have the best understanding of the Force - even though there are other traditions that have shown better results? | Better results is largely subjective. Different sects have different abilities, and the results are hard to compare. Aing-Tii monks, for example, aren't known to be able to use the Force in any offensive manner, but are able to transport themselves across the Galaxy with it. The Fallanassi are able to hide themselves and leave messages in the Force, but had no telekinetic ability. It's not really possible to say whether this is better or not.
As to why the Jedi are so prominent, it stems from two things: the Jedi were the most numerous of any Force-user group, and they were closely interwoven with Galactic Republic politics since the very beginning of the Republic. They gave the Republic both military and non-combat aid countless times over the millennia, and because of this are well known throughout the Galaxy. | 47 | 43 |
Most well-rounded programming language to learn? | Greetings, Lads.
I am copy-pasting this with minor edits from /r/sysadmin upon suggestion from another fellow. I would have cross-posted if this sub allowed that. Context aside:
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As of right now I am just a Help Desk tech whilst schooling for my second major (Networking first, CyberSec now). I want to make my resume more powerful and it seems like Programming might be an ideal thing to tack on to said resume.
What would be most ideal? I'm most at home with Windows (of course) but Linux might not be a bad avenue either.
I see a lot of talk about Python, and sysadmin seems to agree upon Python, Bash for Linux, or Java. Would those be the best ones to put time into? If so or if not, what are some books I could use to build said skills, or links to get the environments required, ect?
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Thanks lads. | If you’re looking at getting into Cybersecurity, you might want to focus on more scripting oriented languages. Python comes to mind as something that would bridge well for you, assuming you’ve had experience with shell scripting and what not being a networking major. Working on simple operations and syntax writing scripts first and then branching out into more of the subjective aspects, like Python’s OO aspects and stuff like MRO, would make sense as a route to take. | 15 | 25 |
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