q_id
stringlengths 5
6
| title
stringlengths 3
301
| selftext
stringlengths 0
39.2k
| document
stringclasses 1
value | subreddit
stringclasses 3
values | url
stringlengths 4
132
| answers
dict | title_urls
list | selftext_urls
list | answers_urls
list |
|---|---|---|---|---|---|---|---|---|---|
8kxme6 | What population density could t-rex realistically have had? | askscience | https://www.reddit.com/r/askscience/comments/8kxme6/what_population_density_could_trex_realistically/ | {
"a_id": [
"dzbdowi",
"dzbdprz",
"dzbes46",
"dzbf5qq",
"dzbgni1",
"dzbqtdw",
"dzbsdp1",
"dzbshpw",
"dzbtj2u",
"dzbumjz",
"dzbv1t4"
],
"score": [
3130,
93,
4,
20,
64,
3,
3,
18,
21,
4,
2
],
"text": [
"[Here's a paper from a time this was previously asked](_URL_1_). \n\nShort answer seems to be that they don't know. \n\nThere are a number of factors (prey density, metabolism, hunting strategy) that are all pretty speculative, making it difficult to get something approaching a real answer. There's even [some evidence](_URL_0_) of social behaviors - pack hunting remains a possibility. Hard to be very sure of specific animal behaviors from ~~150~~ 66 million years ago.",
"You know, I have always been a bit bothered by the ecology in Jurassic Park, especially as it's supposed to contain entire herds of sauropods.\n\nAnyway, your comparison of tigers to dinosaurs is based on the faulty assumption that they have similar metabolisms, and so require similar amounts of food. There is mounting evidence that dinosaurs had a higher metabolic rate and were more active to their reptilian ancestors, but that doesn't necessarily mean they were as active as modern mammals. T. rex is a bit of an odd example, because as Tyrannosaurs evolved and got bigger, rather than extending their growth period, they just grew faster over the same period; which implies that, at least through their adolescence, they had a fairly high metabolism compared to their ancestors. On the other hand, their sheer size at adulthood would have meant that they didn't have to spend as much energy on maintaining their body heat (if anything keeping themselves cool would have been more of an issue).\n\nThere are also several ecological factors that could foul this comparison; the density of potential prey in the region, the amount that varies across the year, the difficulty in taking down the prey, competition from other predators, etc.\n\nAs to finding mates, bear in mind that T. rex had its head pretty far off the ground, which would have made it easy for it to see and hear other individuals at a distance. Such a large animal could probably roar pretty loud if that's how they communicated, and I've read at least one paper suggesting that the need to be seen at a distance played a role in determining theropod cranial anatomy.\n\nSo in terms of your question, I don't really know, and I'm not sure anyone can make a confident estimate without knowing a good deal more about T. rex and its ecosystem.",
"You'd think someone has extrapolated this sort of data based on fossil location, rather than theoretical inferences. Not sure if fossils can congregate in a way that misrepresents geographic density?\n\n*deafened by thousands of simultaneous spectacle adjustments/throats clearings*",
"I hope it's ok to recommend a science fiction book as a top level comment. \"Bones of the Earth\" by Michael Swanwick actually looks into this issue in a realistic manner. It's not only a fabulous dinosaur fiction book, it's quite possibly the only time travel book that actually makes sense. ",
"There is an assumption here that the Tyrannosaur is a predator. While not nearly as glamorous, there is evidence the animal was a scavenger. Scavengers are more common than predators. Work by paleontologist Jack Horner sheds light on this theory. The animal could not run very quickly, so it is unlikely it chased prey like the dinonychus, etc. It had a huge nasal cavity, like a vulture. Its large body could have intimidated and run off the raptors that did the killing work for it.\n\nJack Horner looked at the population density. He found a lot more Tyrannosaur remains than velociraptor, etc. This is in line with current observations of scavenger/predator population ratios. Don’t take my word for it! Look up Jack!",
"To run with your Siberian Tiger idea, the size of their prey was also much larger, so that measurement doesn’t really work. During the period the Tyrannosaurus existed, most fauna was able to grow to greater sizes due to increased oxygen in the atmosphere, so it could be that they had a similar population density to comparable predators today. What’s more, there was also greater density in the flora of that period, which would assumedly lead to an increase in the population of prey items. \n\nAs another poster mentioned, Jack Horner studied the population density of Tyrannosaurus, and it is theorized that they were also a prolific scavenger, in which case their massive size was used more to intimidate/fight off the more agile and smaller predators that did the hunting for them. _URL_0_",
"Hey OP. I don’t want to troll through all the biz on this. I just want to say that although the siberian tiger is the world’s current biggest cat, it lives in a relatively ‘poor’ area. In that it’s a nutrient harsh environment, not alot of prey density because not a lot of edible vegetation density for that prey. Not that it minds, it’s evolved and adapted (yeah, look strong word ‘adapted’ because it’s critically endangered atm after human influence) to living in that ‘harsh’ environment. It might be that T. rex lived in a world with greater prey abundance which could mean it didn’t need such a large territory to eat in. It’s dinner might have also been far larger than it, which would put a spin on things too (i.e elephant hunting lions, giraffe eating leopards) rather than a tiger to deer comparison. I liked your question :) I do not know the answer.",
"It's an interesting idea that is actually being played out with wolves and moose. Isle Royale National Park is approximately a half million acres and has been inhabited by upto 50 wolves and 500 moose. The cycle never stabilized and is highly studied.\n\n_URL_0_",
"I don’t have anything of value to add but I just want to thank you for asking about dinosaurs!",
"In the Siberian tiger comparison, you have to remember that TRex's meat supplies were proportionately bigger. So it's not like they'd need a 10 times bigger area to get 10 times the meat for their 10 times bigger bodies.\n\nThe ecosystem had way more and bigger plants than Siberia, supporting giant herbivores for TRex to tear apart like a fat kid tears into a novelty bag of skittles.",
"Wouldn’t another factor be that the size of their prey was also pretty large. All animals were bigger back then due to the high proportion of oxygen in the air so taking their huge size relative to the size of prey available today wouldn’t work. "
]
} | [] | [] | [
[
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4108409/",
"http://earth.geology.yale.edu/~ajs/1993/11.1993.06Farlow.pdf"
],
[],
[],
[],
[],
[
"http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016574"
],
[],
[
"https://en.wikipedia.org/wiki/Wolves_and_moose_on_Isle_Royale?wprov=sfla1"
],
[],
[],
[]
] |
||
1hvbyk | why do some people cry during sex? is it biological or psychological? both? are there performance or dysfunction related to crying during intercourse? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1hvbyk/eli5_why_do_some_people_cry_during_sex_is_it/ | {
"a_id": [
"cayaf31",
"cayahk5",
"cayaj81",
"cayamqe",
"cayawm9",
"cayb2r8",
"caybhnx",
"caybmat",
"caybmzx",
"caybph0",
"caybpmu",
"caybq6i",
"cayceu8",
"caycihn",
"caygh3j",
"caympog"
],
"score": [
53,
15,
10,
20,
16,
78,
26,
4,
50,
6,
5,
6,
6,
16,
5,
2
],
"text": [
"If people do actually cry during sex, this would be difficult to explain to a five year old.",
"do you know about *consent*?",
"Sex is very emotional to some people, but you're five, you don't need to worry about that yet.",
"I've cried and laughed during an orgasm. I couldn't help it. The feelings just overtook me an apparently that was my reaction that time. ",
"Overwhelming feelings = the release of tears for some people.\n",
"I can only speak for myself, but if I cry during sex, it's because the sex is so overwhelming, both physically and emotionally, that I need a quick, accessible outlet for it. You'd think that an orgasm would be a good outlet, given the circumstance, but that just makes it more overwhelming, and more tearful. For me, I believe it's psychological. Tears are a quick and easy outlet for *any* strong emotion I have. Rage and bliss are the two big ones.\n\nThere is a huge difference between crying during sex because you don't want to be having it and crying during sex because you don't want to ever NOT be having it.",
"I've cried only after one orgasm, and that was the best of my life. It took me a few minutes to recover, so my boyfriend just cuddled me in the meantime. I think it occurred because the release of that many endorphins coupled with dopamine and oxytocin, created a huge, confused well of emotions that inadvertently came out as crying. \n\nShit felt awesome ",
"My ex girlfriend cried the first 10 or so times we had sex. Very strange to me, as I thought she might have had some kind of sexual abuse when she was younger, but she just ended up being a very emotional girl. ",
"There's no shame in crymaxing.",
"I can't really ELY5 (mostly because I dont have a full enough understanding) but this is taken from this [link](_URL_0_)\n\n\n\"Sex therapists and researchers William Hartman and Marilyn Fithian proposed a physiological explanation for the shedding of tears. They proposed that since an orgasm is triggered by deep stimulation to the uterus and strong uterine contractions, then the involuntary sobbing may be due to the vagus nerve in the brainstem being stimulated. This causes a ripple effect that triggers a cricopharyngeal reflex in the throat.\"\n\n",
"Semi-relevant: Why is it that in nearly every porn video involving an Asian female, she looks like she's crying in pain the entire time?",
"I cry sometimes, though not often. Things are just overwhelming sometimes, especially if I'm \"making love\" and not just fucking. It's emotional, and it feels good, and if it's *very* emotional and it feels *very* good, I cry. It's just because it can be so intense. So unless a person is crying because they have a traumatic memory triggered, or because they're hurt or something, I wouldn't worry about it. Just be supportive and listen and hang on.",
"My girlfriend has cried just after sex twice, it was after the best sex we ever had. During would be...strange.",
"I posted about laughing and crying during orgasm in /r/sex the other day, but this is basically what I think:\n\n\nFrom what I know of the brain (I'm in training to be a psychologist) I think it relates to the limbic system, which is the reward system of the brain. This involves the amygdala, nucleus accumbens, VTA, and pituitary gland, the last of which releases hormones like endorphins. I think the release of endorphins during orgasm mimics a lot of the same hormones that are released when we laugh or cry for joy. This helps to explain why many people also experience intense emotional reactions during orgasm. \n\n\nI think it is mostly biological. There is some \"wiring\" in the limbic system that gets linked together so that when the endorphins associated with orgasm are released they also trigger laughing or crying. As with any nature/nurture question there is some overlap. The person probably has some personality characteristics that also facilitate it occurring. Perhaps openness to new experiences, lack of inhibitions during sex or feeling comfortable enough to let themselves go during the sexual experience (keep in mind this is speculation as there is very little research to back this up). Also, it depends, if this person experiences crying in conjunction with orgasm it is probably the limbic system cross-wiring thing going on; if they experience it not connected to sensation then there may be something else happening. There could be re-experiencing past trauma, they may not want to be having sex or are feeling pressured, they could be feeling insecure, or there may be some unspoken and unresolved relationship issues that the person is thinking about. You'd have to question the person to find out. \n\n\n**ELI5 version: **Okay little guy, I don't know why you want to know about this...but you know how we have these things in our head called a brain? The brain makes up our whooole word, including how we respond to.. ah ahem...sex. Sometimes stuff in the brain gets confused so when we get that really happy feeling other feelings happen too. People shouldn't feel bad about this..There may be other stuff happening too, so people in love should talk to each other to make sure everyone's on the same page....Now uh go play with your legos, mmmkay? ",
"I get tears often when I climax, but not because of emotional reasons. You ever take a bite of food that was so delicious, that you had a visceral reaction to it? Or a piece of music that brought a tear to your eye? When I climax, it feels *so good* that my eyes are watering. It's not crying, it's literally so good, it brings tears to my eyes.",
"My wife has cried during climax twice in the 8 years we've been together. Not out of sadness or joy, just overwhelming emotion she says. I've always wondered how common it was."
]
} | [] | [] | [
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"http://www.foxnews.com/story/0,2933,340942,00.html#ixzz2YTYQ3TOl"
],
[],
[],
[],
[],
[],
[]
] |
||
1nbyhw | who owns the united states federal reserve? if it is the government, explain why we need to pay interest on the created money? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1nbyhw/eli5_who_owns_the_united_states_federal_reserve/ | {
"a_id": [
"cch6xi1",
"cch7049",
"cchansb"
],
"score": [
2,
2,
2
],
"text": [
"The Federal Reserve doesn't really have an owner. The leadership is appointed by the government, but the government doesn't claim any ownership rights over the organization or its stuff. \n\nWhy do we do it this way? Well, the Federal Reserve sets what's known as monetary policy (roughly, the policies regarding how many dollars are around), and it's very important that monetary policy be *stable*. If politicians could just print off a bunch of money to pay for things, it would be hard to trust US currency, because you'd never know when it would be devalued by a new wave of printing. The Federal Reserve makes it clear when and why they will print money, so this doesn't happen, letting US dollars be one of the most commonly used currencies in the world.",
"We don't pay interest on the money.\n\nOr rather, we do--the Fed generally gets the money it's created into the economy by buying bonds, and we pay interest on the bonds that the Fed holds--but then the Fed gives (almost) all its profits back to the government. [Last year the Treasury got $75.4 billion of the Fed's $77 billion profit.](_URL_0_) Which is only fair.",
"The Fed owns itself. It is a private bank. It has its chairman appointed by the President, and is expected to answer to the economic policy of the government but is in no way obligated to do so."
]
} | [] | [] | [
[],
[
"http://money.cnn.com/2012/03/20/news/economy/federal_reserve_profit/index.htm"
],
[]
] |
||
sodii | why fight to have student loans forgiven? | I don't understand why a lot of people want student loans forgiven. Did the government trick students into taking out loans?
It doesn't make sense to me that someone would sign something saying they would borrow money and pay it back and then get upset they have to pay it back to the point where they frame the investor as a bad person.
**edit:** Wow, I really thought there would be a clear cut answer, but it seems a lot of people have different opinions.
Findings:
- Everybody thinks that it really sucks that so many kids have so much debt and most agree that it isn't entirely the students' fault as a group that they are in such a mess (economy, social pressures, etcetera).
- Some people think if you take out a loan, you should have known the risks.
- Others respond that kids so young shouldn't be held accountable for a mistake they couldn't possibly comprehend at the time.
- The counterpoint to that is that ultimately, nobody forced anybody to go to college or to get a degree that has low job prospects.
- A response to that is that kids shouldn't have been fed the myth of a degree automatically putting you ahead in the job game.
- A big majority of people who owe student loans think their loans should be forgiven.
- People who don't owe student loans or have very little debt think loans shouldn't be forgiven or that there might be other solutions.
PraetorianXVII linked [this article from Cracked](_URL_2_) which some may find interesting.
**edit 2:** [bo1024 best characterizes my feelings about the whole thing.](_URL_1_)
**edit 3:** [monkeyballs2 makes a good point](_URL_0_) that forgiving loans might be a bad precedent to set and that it's insulting to people who wanted to go to school, but knew they wouldn't be able to pay off their loans.
**edit 4:** [There should be a line drawn between those who should have known what they were getting into and those who had a superb plan, but unforeseeable consequences squandered them.](_URL_3_) | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/sodii/eli5_why_fight_to_have_student_loans_forgiven/ | {
"a_id": [
"c4fmefa",
"c4fnm97",
"c4fnmsh",
"c4fnmxd",
"c4fnnru",
"c4fns78",
"c4fo1ak",
"c4fos6f",
"c4fotm0",
"c4foulv",
"c4fp2lh",
"c4fpfs6",
"c4fpxz1",
"c4fq5jl",
"c4fqlw5",
"c4fqro0",
"c4frwel",
"c4frwum",
"c4ft9iy",
"c4ftf6e",
"c4fv5si",
"c4fvgt6",
"c4fvkdj",
"c4fvkuv",
"c4fvos0",
"c4fw6hn",
"c4fwb6d",
"c4fy246",
"c4fy5gh",
"c4fyrj3",
"c4fzaxl"
],
"score": [
257,
89,
18,
19,
31,
13,
5,
5,
7,
2,
4,
5,
2,
7,
6,
3,
4,
3,
3,
44,
2,
5,
3,
2,
5,
5,
3,
2,
2,
2,
2
],
"text": [
"For what it's worth, I agree with you, but I'll try to explain the mentality behind it - today's 20-somethings were brought up their whole lives believing that college was the ticket to a bright future. You did decently in high school, went to a respectable college, and got a suitable white collar job that put you squarely in the middle class.\n\nForget for a moment that this mythos isn't and never has been entirely true - an English degree didn't directly lead to a job any more in 1985 than it did in 2005 - but this belief in the merits and inevitability of college has been pounded into everyone's heads over the last 20 years, leading to skyrocketing enrollment rates.\n\n...but also skyrocketing costs. Since the 1980's, college costs have risen 2-3x the pace of inflation, leaving the '00s graduates with a lot more debt burden than previous generations. At the same time, because of the recession, opportunities are much scarcer for college grads at any point in many decades. Yes, it's still more likely you'll be employed if you have a college education than if you don't, but it's also much more likely you'll be underemployed, running a register at Banana Republic instead of working in the field of your degree (that $10/hr doesn't help much when you have 6 figures worth of student loans.)\n\nSo in summary: recent grads have had the desirability of a college education driven into their heads since elementary school. They followed that advice and went to college, taking on more debt than ever before, only to graduate and find that the jobs weren't there. You mention that it's not like they were tricked, but a lot of them feel like they were. I definitely don't think loan forgiveness is the solution, but I can't blame them for being frustrated.",
"Let me try and explain it a different way. Remember when Mom and Dad bought a house that cost three times their allowance? Well Mom and Dad (as voters) complained and many plans were created to help them out of the mess they go into. They claimed that the banks lied to them, used deceptive practices, and therefore the people who took out bought houses they couldn't afford were not responsible.\n\nFlash forward to \"student loans.\" Many of the same banks use the same deceptive practices to sell loans to kids that they can't afford. These kids become adults and realize that when they were 17 (too young to vote, too young to buy a house, too young to even have a credit card) they were sold something which they could not afford. \n\nIf you sold a house to a 17 year old, would you be surprised if they regretted it when they were 27? If you were a bank selling houses to 17 year-olds would you take advantage of the situation in order to make more money for yourself?\n\nBut I think the real problem isn't that everyone wants their student loans forgiven. They would simply settle for a middle class job. 30 years ago, there wasn't this same notion of \"paying your dues\" in an unpaid internship. Unpaid internships of 2012 were once called-entry level jobs. These difficult barriers result in students taking on even more loans, and with an ever-increasing amount of kids looking for opportunities at any cost- they're taking the unpaid internships, leaving no incentive for companies to once again hire entry-level employees. \n\nSo you have a generation with huge amount of debt. Highly limited job prospects, no promise of pensions, very little health insurance- they see the deck as stacked against them. So this is why they're asking for student loan forgiveness. Unemployment (and underemployment) among people 30 and under is becoming epidemic.\n\nand I find it confusing that the same people that felt that that government owed them something for taking out their sub-prime mortgage are so confused why young people think that their loans are an unjust burden.\n\n//okay, started LI5, ended on a soap box. But there's an explanation that's a bit different than the other top level comment. ",
"It's a combination of a few factors:\n\n* A college education is viewed as compulsory by many people\n* A college education is very expensive, and loans are easy to obtain\n* Student loans are NOT forgiven in the event of bankruptcy\n* Most 18-year-olds are not sufficiently financially savvy to realize the consequences of massive amounts of debt (and overestimate the ease of paying them back)",
"Because it's the biggest drag on the housing market right now (huge amount of kids who graduated in the past 5-10 years are living with parents, and not buying homes, mostly because of their student loan debt). Some would argue that means it's the biggest drag on the economy",
"While the government did not trick students into taking out loans, when the government gave out loans so every student would have a chance, every school raised their tuition by the exact amount as the loans",
"The same government is providing relief to others like homeowners. Semi-same situation applies: investment in a home vs an investment in your future. Things didn't work out and now you are underwater with no realistic way out. Difference is: homeowners can get government assistance, and worst case, can jump ship and file bankruptcy and start fresh. You can't escape student loans.\n\nMind you, I think it should be impossible to get completely off the hook in either situation, but I do think relief of some kind should be available.",
"Because many folks believe (with corroborating studies) that it's harder to get a job good enough to pay off your loans now, because of the economy.",
"I feel like making the situation more reasonable for students is the right thing to do, but I would be kind of annoyed if there was a mass amnesty of all student debt. I worked hard in high school and college at shitty jobs while saving nearly every penny, went to a public school (it was the best school I got into, but if I had got into Stanford I probably still would have opted to go to my alma mater to save money), accepted crappy living situations and took handouts from my awesome parents and other wealthy family members + 10k in loans. I hustled my ass off to get a good job (that shit doesn't happen automatically with a political science degree) and now I've got everything paid off, and I fee accomplished. I know I started off with a lot of big advantages, but I had a lot of friends in school who were spending loan money on cars and Iphones and concerts and did poorly in school, turned down extra work shifts out of laziness... They shouldn't have to be broke for the rest of their 20's but its not fair to just erase their debt.",
"From what I understand there's a combination of things going on that make student loan forgiveness very attractive to freshly graduated, and previously graduated students. First, student loans cannot be dispersed through bankruptcy. That means that when you no longer have any money and are going deeper into debt, owing more and more, you can't get rid of it at all. There are very few things in America that have this kind of protection. \n\nNow let's put this into perspective. Teachers make relatively little money compared to say, engineers, but they fulfill a mandatory part of modern society, in that they educate our youth. The basic skills that they need are taught regularly by people that in many states have to have at least a bacholars or masters level degree to become certified. Then they have to substitute for several years before they can get into a full time position. They are choosing to become teachers. It's a choice, I get that. However, punishing them for fulfilling a necessary role in society doesn't seem appropriate to me. That's why the loan forgiveness programs are important. Without them, people that fulfill a necessarily societal role would not be able to survive under their loan debt. If they can only pay their loans, rent, and utilities, then rely on the community for food, then they're creating, arguably a net loss for the community. \n\nThere's also a mentality of sorts that comes to mind regarding this issue. The \"I got mine\" style of thinking. This can be characterized by looking at the people behind the counter at starbucks. A good friend of mine has passed the bar exam, but is still working as a barista because no one is hiring lawyers. No one can afford to sue. The economy has taken a nose dive and accordingly, the money people would spend on litigating is pretty much gone. Sure lawyer is a high power profession, but you have to work in it to be able to do anything. We could also look at doctors and see the same results. These are people that have several hundred thousand dollars in student loan debt. They're working to save lives, but are forced to carry malpractice insurance in the hundreds of thousands of dollars, pay their student loans, work shit hours, and continue their education. The American dream is viable for them, in maybe twenty years. Yet, as soon as they graduate they're fulfilling a societal necessity. They're helping keep this country running and people working. If even a fifth of their loans are forgiven that's a huge amount of money and potentially hundreds of thousands of dollars that would go back into the community rather than into the hands of a corporate giant somewhere.\n\nAnother part of this is that society right now is more service based than production based. Skilled labor jobs are disappearing. Though, there is some suggestion that manufacturing may be coming back to the US. Without some kind of higher education, technical school, what have you, most people will not be hired for anything more than a minimum wage job. Minimum wage is not enough money to sustain a household on. People that go on public assistance then cost the country a lot more than they would otherwise. This leads to another cycle. People that go on public assistance get propped up, then once they're almost ready to stand on their own the props are removed prematurely. That extra few hundred that would have gone to paying the housing costs is gone leaving the person behind on their rent again. Then once their credit tanks and they lose their job they're back on public assistance. This happens to people with degrees and to those without them. However, if you can remove a portion of the debt through forgiveness it alleviates a lot of the strains. This doesn't necessarily mean that people will be able to get off public assistance, but with a little more help it might be more viable. \n\nBasically, what I'm trying to point out is that these student loans, even when they're paid for and the person has a good job, are bad for the communities as a whole. Money that would have, otherwise, gone to businesses in the local area is being diverted to large corporations that then take the money and invest it in other big corporations. It limits the growth of the community.\n\ntl;dr: It costs more in the long run, both in growth in the community, and to the economy to not forgive the loans.",
"Let's think of it this way, I don't have loans from undergrad (I am grateful to the foresight of my family putting away money from my birth to put me in this position) *however* I do have loans for my masters which was necessary to put me on a career track, everyone talks about 100k for a degree in English which is ridiculous, if you are poor enough to need that much aid you will get grants if you are rich enough to not be able to get it you can probably afford it, plus schools that cost that much (USC, Harvard, etc) have huge endowments which allow them to give out their own private grants \n\nI personally owe about 45k for a masters in social work and am making about 53k a year\nCan I make my loan payments? Sure\nCan I pay my rent? Sure\nBut I'm 28 and the prospect of buying a house where I live is not even fathomable to me\nIf I didn't have to pay 500 dollars a month to the government it might be a slightly more realistic dream, but because I work in a particular field, for a county contracted agency, in a low income area of town, and work bilingually so I can apply each year to have 10k forgiven \nI know I signed up for the debt and am paying it dutifully back but they're also willing to look at certain careers (ie social work teaching and some others) and look at the need being fulfilled and help us out a bit",
"Bob the banker likes cookies. Bob likes cookies sooo much that he spent his entire allowance on cookie dough! But, Bob has a problem. You see, Bob doesn't know how to make cookies. Do you like cookies?\n\nBob is friends with Betty the Baker. Betty knows how to cook the best cookies in the whole school. But, Betty has a problem too! You see, Betty doesn't have an allowance to buy dough with which to make cookies. Do you have an allowance?\n\nBob and Betty work out a deal with each other. Bob will give Betty enough cookie dough so that she can make ten cookies! In return, he asks for one cookie a day for eleven days. Do you think Betty made a good deal?\n\nThe next day Betty comes to school with ten cookies. She gives Bob a cookie like she promised. She eats one for herself. Because everyone knows Betty is the best baker in school, her friends buy the remaining eight cookies from her. She makes enough money selling her eight cookies to buy dough for ten more cookies. Betty now has a successful business!\n\nNow Bob has one cookie a day, but he wants more. The only other person in school who knows how to bake is Scumbag Steve. Bob doesn't know Steve very well and hasn't tried Steve's cookies before. Betty tells Bob that Steve shouldn't be trusted. Bob is kinda scared, but he really likes cookies and Steve promises that everything will be alright. Bob trusts him and gives him enough dough to make ten cookies. Did Bob make a good deal?\n\nThe next day at school Betty gives Bob a cookie like yesterday but Steve says that he lost the dough and can't give Bob anything. Is Steve a bad person?\n\nBob is angry, and demands his cookie from Steve. Bob tells his Uncle Sam and his uncle also gets mad. Together they go to Steve's house. When Steve opens the door, Sam punches Steve, goes inside, and takes all of the food Steve has. Did Steve deserve to be attacked over a broken promise? ",
"No cuts, no fees, education must be free!\n\nIt's down to a difference in beliefs. Education is a human right, just like food, housing, and healthcare. Things like that should all be provided for on the basis of need.\n\nThe reason why we can't do that is because a small number of people are being very selfish. You know how you hate it when the big kids gang up and bully the little ones? That's what a small number of grown-ups do too. Everything is nicer when we work together and share, so when you grow up be nice and don't be selfish!",
"Studying music business know and this surprisingly adapts very well. A big concept we learn is \"But Where Do I Sign\", meaning, most artists skip reading the 30+ page contract that looks like gibberish to them. This applies to students. \n\nMost students know alot about what they are signing, yes they can read 12.5%, that's a number and yes they can read they are taking out $40,000...but they don't understand it. Or maybe they don't want to. Maybe it's that hmm well when I graduate I will be able to pay all that off easy since I'll be making way more money than that!\n\nBut uhoh! that small % they didn't realize was monthly...and now they are stuck paying interest on a balance that keeps rising! And what's this? Their position isn't starting at 60k/year or 80k/year....they are starting entry level which was a bitch to get hired to in the first place for anywhere from $10-20/hr. \nNo, noone tricked the students into anything. They just really abuse a situation, but who can blame them. How many graduates are still kids that don't take on the responsibility of paying these off? Someone got fucked. \n\nMaybe a highschool course on HOW TO DEAL WITH THE REAL FUCKING WORLD would be something greatly recommended. \n\nAnd so here is my parting advice:\n\n**TL;DR: Save money for a year or two, get financial aid and grants, and keep loans to a minimum. This will save you a LOT of money, and not fuck over everybody(yourself, the loaner, other people that will take on the burden of supporting you) just because you didn't want to do the maths and just signed for the money.**",
"Just a related PSA: \n\nThe Student Loan Forgiveness Act *is not forgiveness of loans as you think of it*. \n\nIf you get federal student loans, there are several plans to pay it back over time. One such plan involves working in the public sector, such as a teaching job, for a minimum number of years and making payments for 10 years, based on your income. After those 10 years, if you've met the requirements the entire time, the remainder of the loan is forgiven. \n\nWhat the law they are trying to pass does is increase the eligibility. You'd *still* have to make payments for 10 years, but more people who have to take a plan that is less per month will qualify. \n\nIn this sense, forgiveness is a bit of a misnomer. People will still have to pay a ton of money towards the loan, and it's 10 years of very little extra money. Some people argue that there's a big chance for fraud, but that'd be true whether the law passed or not. ",
"Because my $20k in student loans isn't shit compared to a $600,000 patriot missile. Either way I'm paying mine back and don't expect anything, but it would be nice if they re-prioritized our spending.",
"The economic side of things (which has nothing to do with whether or not loans are a good or bad idea) is that forgiving some student loans would immediately inject cash into the economy. Pay 20% of your take home pay towards student loans? If you didn't have to, you'd see 20 and 30 somethings buying more houses and starting families sooner. More house ownership equals more local government revenue. \n\nI'm not sure I'm in favor of a middle-class bailout (which is what this would amount to), but it's not just about the individual who took out loans. The benefit to the larger economy is what would actually make this happen.",
"I don't want my loans forgiven, I just want my interest rates to not exist and to not have a minimum payment be $345. At the end of me paying loans off I will have paid almost double what I took out to begin with.\n\nLike most people are saying here, as 17 year old kids I don't think we realized that with interest that 35k loan would almost double by the time we paid it off. After x amount of years of deferment, forbearances, phone calls, mailing in pay stubs, proof of employment and struggling to pay the \"minimum payment\" of $320 a month having that forgiven would be a burden of so many peoples backs. \n\n",
"I love how instead of trying to come up with solutions we just go \"well the problem shouldn't have happened and it's not my fault so, uh yeah\"\nas if the problem will somehow go away just because it isn't our fault. \n\n\n\"oh the teens were just irresponsible with taking out loans. Maybe they should have been more responsible. I was responsible. Why weren't they?\". Yeah, OK, we still have a lost generation of underemployeds with thousands of dollars in debt that's just going to get larger and have hurt the economy more if we don't do something about it. People who want student loans forgiven are at least offering a solution.",
"The real problem, I think, is the preposterously high interest rates. Right now I have loans that are upwards of 7% - and that is ridiculous. \n\nAlso, having an educated society is good for that society. Education breeds innovation which drives new economies. If we are the only country doing something (like going to space) then we have jobs that CANNOT be outsourced, because no one else can do it. Same thing for when the internet started. So, basically, we want to encourage people to be forward thinkers, and skyrocketing school costs and loan troubles are distinctives, and that's not good for us as a whole.\n\nI say the answer is providing super-low interest rate loans so that recent students can get out from under their debt and contribute to the economy more fully. ",
"Lots of good answers here. You seem to be asking whether student loans are the students' fault. Well, I just want to tell a quick story about incentives. Like a Vonnegut there are no villains in this story, just people.\n\n* **Companies.** Companies want to hire the best workers they can. If you have the choice between someone with a degree and someone without, you don't *know* who will be better. But if you have to pick, you might as well play it safe and pick the one with the degree.\n* **Government.** The government wants to have lots of college grads, because then it has an \"educated workforce\" and is \"competitive\" with other countries. But it's expensive to fund education, and politicians who overspend aren't popular nowadays. So states and feds offer loans even as they cut funding to schools drastically.\n* **Banks.** A college loan historically is a great investment. People generally (used to) graduate, get a job, and pay it back. Banks are (or were) very happy to give out these loans, and they're big loans that get milked out over many years after graduation.\n* **Colleges.** Their #1 priority is to be \"competitive\" and move up the rankings. This means expensive projects, high-profile sports and campus construction and programs; it means adding activities, building student centers, doing anything you can to differentiate yourself. But these things cost. And in a tight economy, state and federal governments aren't funding schools as much as they used to. The result is that you have to keep raising and raising your tuition. And you'll be fine, because there's still lots and lots of kids who need to go to college. So as prices go up, demand doesn't drop. So you have to keep raising those prices.\n* **Parents.** You want to see your kid be successful and get a well-paying, not too strenuous, prestigious white-collar job. That means college, no questions asked. You raise them to go to college as a given.\n* **Kids.** It's simple: do you want a job or not? It doesn't matter how much college costs are increasing or how ridiculous the loans are. There are only so many jobs out there, and for most people, you're still better off with the huge loans and the degree than without either. So what are you going to do? You don't have much of a choice. You'll pay the ridiculous costs and take the loans, cause it's still better than the alternative.\n\nI don't see anyone to particularly \"blame\" in this situation, but I do see the end result: a generation in huge debt and low on jobs. That won't be good for anyone in the next 20ish years. People seem to want to talk about who \"deserves\" what and what's \"fair\". I don't see any villains here, just a bunch of people trying to make the best of a bad situation and an end result where everyone loses, no matter who you blame.\n\nBut the question is, what do we do about this situation?\n\nAnswer: I don't know.",
"I'm sure this has been touched on, but for me personally I feel like government has pushed to cut funding on education which forces schools to charge more. Then you have the government more than willing to give as much in student loans as possible which in turn leads schools to raise tuition because they know the students will just take out more loans. Then even if you do manage to get out with lower student loans than most you're still not graduating and moving into a stable job market. Also it just blows my mind that someone could work part time and a minimum wage job, and graduate debt free only about 30-40 years ago.",
"Let's look at this from a macro point of view.\n\nCollege graduates are getting more and more underemployed. Tuition costs are rising. This is a dangerous combination.\n\nDo we want the future kids of our society to start choosing not to go to college? That's bad for the future, that's bad for our economy.\n\nThe fact that we're profiting of off the youth's NEED for education is a terrible thing. No, I don't believe all student loans should be forgiven. However, I do believe that student loan interest should be subsidized by government funding. \n\nIf I borrow $50K to get an education to be a more effective contributor to society, then I should be responsible for paying every cent of it back. However, telling me I need to pay $30K on top of that in interest with a 50% chance that my degree won't land me a job - that's a risk that many kids/families won't be willing to make. We don't want our future kids choosing to be under-educated.",
"I don't know if this idea has been put forward by any of the other comments but there is another aspect to this issue that I think may be worth discussing.\n\nWhile many young adults do go to college to get a degree in order to try and secure a job in the future, there are also those who go to college basically for the experience. These are students who undertake studies in communications, anthropology, history or english simply because it's the easiest way for them to BS their way through college.\n\nThese students rack up thousands of dollars to earn a degree in a field that really has nothing to offer them and end up being cycled into lower-income jobs. They may be college educated, but in severe debt for a degree they probably could have done without and for those, I have little sympathy.",
"Well when youre 2 years from graduating with a degree and tuition is increasing 20% each year you aren't exactly going to quit. ",
"forgiving student loans gives an unfair advantage to people who didnt pay for school, people who didn't sacrifice to pay off their own loan. lots of smart kids didn't go to school because they couldnt afford it, making it free after the fact severely fucks those people over. there are a lot more job opportunities for people with degrees, just cause the economy is shit now doesn't mean it always will be, those degrees will be plenty lucrative when the economy bounces back. There are countries where college is free for the qualified the determined and the willing. Italy has a merit based university system i admire, perhaps we should implement that. But to retroactively forgive debt is a big fuckyou to the responsible hardworking people who payed off what they borrowed. It sets a bad precedence and encourages fiscal ridiculousness. Roll back the tuitions to where they were 20 years ago if you want to help students.",
"LOL reddit thinks college kids are too immature to handle their finances but thinks the drinking age is absurdly high.\n\nNews flash people: you are an adult and you must deal with the consequences of your actions!",
"Because people always, always, always want something for free.",
"Thanks a lot for the cliffs OP, appreciated.",
"Many people are saying that the individuals taking out the loans knew the risks and should therefore be responsible everything they borrowed. This is very true. However, it should be noted that many individuals signed onto something with different expectations. I am a great example of this. I attend a professional/graduate school in Pennsylvania. During my application process we were told numerous times that the PA government provides credits to students that attend professional schools within their home state. $8000/year to be exact. Many state governments offer these to students who attend professional school in their home state. If a state doesn't have that professional school they often give hefty amounts of money for students to travel to other states as long as they come back to their home state and practice for a given period of time. Anyway, that's $32,000 over 4 years, which my degree is. Right after being accepted, we find out that legislation has changed and professional school students will only be receiving $800 dollars for the first year and $0 for every year after that. Meanwhile, students from North Carolina attending the same school are given $12,500/year as long as they go back to NC to practice for I believe 5 years post graduation. \n\nI went into school expecting $32,000 with interest less debt because I attended a school in my home state. Now I pay more than many students coming from out of the state. \n\nI'm fully aware that I'd be paying off loans until I'm in my 50's, but just not the amount it has become. And with tuition rising every year since I have started, the amount of money seems almost insurmountable. I'll take any form of government forgiveness that comes if it means not having to write a check every month for schooling I completed 30+ years ago.",
"I had to pay all mine back and it substantially limited the other things i could have done with that money for a long time. I think its absurd that people think they can wiggle out of it and make everybody else eat their irresponsibility and inconvenience. Everybody knows what borrowing means. Gotta pay it back. Don't play the dumb weakling who can't do hard things. ",
"While I'm all for forgiveness, I really believe they should make Student Loans like other debts, so if you do declare bankruptcy because of the job market and your six figure students debt, the loans go away the same way they forgave billions in dept from the housing crisis."
]
} | [] | [
"http://www.reddit.com/r/explainlikeimfive/comments/sodii/eli5_why_fight_to_have_student_loans_forgiven/c4fvos0?context=3",
"http://www.reddit.com/r/explainlikeimfive/comments/sodii/eli5_why_fight_to_have_student_loans_forgiven/c4ftf6e",
"http://www.cracked.com/blog/5-ways-we-ruined-occupy-wall-street-generation/",
"http://www.reddit.com/r/explainlikeimfive/comments/sodii/eli5_why_fight_to_have_student_loans_forgiven/c4fysui"
] | [
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[]
] |
|
1u3rv9 | why does it feel good to sleep in the fetal position decade after being in the womb? | Why do some people continue to sleep in the fetal position decades after potentially developing new sleep habits? Speaking on a personal note, I love to sleep on my side with my arms crossed in an X with my legs curled up (preferably pressed against my SO) with my feet crossed as well. I understand that our vital organs are more protected in this position, but why (or how) does this potentially effect our comfort levels during sleep?
EDIT: Please ignore the typo in the header. Should be decades, not decade. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1u3rv9/eli5why_does_it_feel_good_to_sleep_in_the_fetal/ | {
"a_id": [
"ceechng"
],
"score": [
4
],
"text": [
"It's a psychological thing; regression. The fetal position inside your mothers womb is a safe, warm time in your life so subconsciously you go back (regress) to that time of safety and so on.\n\nSource: 1 intro class of Psych last semester."
]
} | [] | [] | [
[]
] |
|
2kj389 | [Physics] Why can I hit a tennis ball pretty far with minimal effort, but I have to work a lot harder to throw it the same? | I was playing tennis earlier today, and was thinking about how the fastest serve (overhead shot) in tennis was almost 50mph faster than the fastest baseball pitch. Why, even with the same kind of ball, is it so much easier to hit the ball than throw it? | askscience | http://www.reddit.com/r/askscience/comments/2kj389/physics_why_can_i_hit_a_tennis_ball_pretty_far/ | {
"a_id": [
"clm31ru"
],
"score": [
4
],
"text": [
"2 things going on here. \n\n1. Leverage. The longer the moment arm you use (tennis bat) the more force you can exert on the ball. Ball goes further.\n\n2. Tension. Tension of the strings in the bat make for a small ammount of elasticity which work for you, in terms of transfering forces to the ball more directly. Ball goes further."
]
} | [] | [] | [
[]
] |
|
6fvmcj | feeling weak while having a cold. what causes that? | Hello!
We all have had a cold. Sympthoms vary: sore throat, runny nose, raised temperature... and above all that "general weakness" affecting whole body. I have that right now without any other sympthoms (had them before though :D), and it got me thinking: what is my body doing now, when all other sympthoms are gone? Why, altough I skipped all exercising for few days, I feel soo tired, yet not sleepy? And why does it get worse in the evening?
Cheers and thanks in advance! | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6fvmcj/eli5_feeling_weak_while_having_a_cold_what_causes/ | {
"a_id": [
"dilcw74"
],
"score": [
3
],
"text": [
"Your body is spending so much energy on fighting the cold that it doesn't spare energy for much else. A proper immune response requires a bit of energy, and fighting infection becomes job 1 (aside from breathing, heart function, etc.). Your immune system is activating chemical and cellular systems that are normally dormant.\n\nAdditionally, a raised temperature means that some regular enzymes may not work as well. Enzymes are picky about temperature. Changing from your body's normal temperature (usually 36.5–37.5 °C or 97.7–99.5 °F) can cause some enzymes to become less active, erratic, or even dysfunctional-- leading to a general feeling of lethargy."
]
} | [] | [] | [
[]
] |
|
628jaa | what causes photos of screens to look so bad? | Title, and also the way that the patterns can change when you zoom in and out of a photo | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/628jaa/eli5_what_causes_photos_of_screens_to_look_so_bad/ | {
"a_id": [
"dfkkfe4",
"dfkkiv2"
],
"score": [
4,
2
],
"text": [
"It's called the moire effect.\n\nCameras have pixels, and those pixels are arranged in symmetric rectangular grids. Displays have pixels, also arranged in symmetric grids. When those grids perfectly align, the image is fine. However, if the grid is off a little then camera pixel A sees display pixel A and a little bit of pixel B. Then camera pixel B sees display pixel B and a little more of pixel C. This small disturbance produces waves of uneven intensity in the image. Since the automatic gain control in the camera looks at the whole image, it can't eliminate the intensity waves. The result is dark bands across the camera image.",
"Photos of screens look bad because computer screens use pixels to display images. This makes them essentially an array of colored dots in a regular pattern, a grid. Digital cameras also have sensors in a grid. When you take a picture of the screen with a digital camera, it produces a [moiré pattern](_URL_0_) where the grids perfectly line up in some areas and not at all in other areas. Distance and angle of the photo affects this so that's why the pattern changes when you zoom in and out."
]
} | [] | [] | [
[],
[
"https://en.m.wikipedia.org/wiki/Moiré_pattern"
]
] |
|
4686ex | how does the conservation of mass and energy, and the expansion of the universe correlate/allow for the other? | If matter and energy can not be destroyed or created, only changed, how do we explain the expansion of the universe? I understand things are getting more spread out, but something has to be occupying all that extra space, doesn't it? As far as I knew there's no such thing as nothing. All of space consists of something quantifiable doesn't it? Also, do these conservation laws also exist for the other elements of the universe like dark matter or anti-matter?
Edit: Apparently we need Stephen Hawking himself to answer this question as there doesn't seem to be a cohesive agreement on what solution makes sense. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4686ex/eli5_how_does_the_conservation_of_mass_and_energy/ | {
"a_id": [
"d03mm6j"
],
"score": [
3
],
"text": [
"You can have nothing. That's what a vacuum is, the absence of something. While space is not a perfect vacuum, it's pretty close. So as space expands, you get a bigger vacuum."
]
} | [] | [] | [
[]
] |
|
1t4hsz | Are there any examples of a unit or part of an army effectively going rogue and that started doing their own thing? | I ask this because i'm playing a game called Spec Ops: The Line where there is a rogue battalion of the US army. It made me wonder are there an real examples of this happening throughout history? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1t4hsz/are_there_any_examples_of_a_unit_or_part_of_an/ | {
"a_id": [
"ce4csnv"
],
"score": [
2
],
"text": [
"There are many, many examples of this in Roman civilisation alone. Not to put too fine a point on it, but are you aware of Julius Caesar and [crossing the Rubicon](_URL_0_)?"
]
} | [] | [] | [
[
"http://www.eyewitnesstohistory.com/caesar.htm"
]
] |
|
28s8q6 | Rangers in history | Where there ever any rangers in history? Like Faramir and Aragorn from Lord of the Rings or Will and Halt from the Rangers Apprentice series. If you haven't heard of them basically they are exceptional archers that are superb at remaining unseen using there skills and a mottled green cloak, to be general. If there weren't any "Rangers" were there any people that were similar to them? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/28s8q6/rangers_in_history/ | {
"a_id": [
"cie4jzd"
],
"score": [
25
],
"text": [
"Well, the archetypal form of those sorts of characters certainly existed. Tolkein, as a professor of English, was very aware of his influences and what he was drawing on. The later horde of fantasy authors ripping him off? Probably less so. \n\nOne of the earliest expressions of what this sort of archetype was the Yeoman introduced in the prologue of Chaucer's *Canterbury Tales*. He is the only attendant accompanying the Knight and Squire on pilgrimage, presumably as their bodyguard since he is well-armed and they are not mentioned to be bearing weapons. Just as the Knight and Squire are idealized representations of their \"types\" ( the Knight is a bold crusader and paragon of chivalry, the Squire is a fresh-faced youth jousting for the hand of a lady), the Yeoman is an idealized image of what yeomen could be. He's very well-armed, carrying his longbow, a sword, a dagger, and a buckler. He has \"a cropped head had he and a sun-browned face,\" from working outdoors and in the forests. The Yeoman's job, in peacetime, was to administer the forests on his lord's lands. This included apprehending poachers, stopping illegal logging or grazing, and watching over the deer population. Chaucer himself was once appointed as a forester, although his position was more administrative than the Yeoman's. It's never mentioned explicitly, but it's very possible that the Yeoman accompanied the Knight on crusade or in some other war. Standard English armies of the day were made up of large archer formations protected by men-at-arms. If the Yeoman did go to war with the Knight, it's possible that he would be a captain or other officer of the archers in the Knight's retinue. From his weapons and other equipment he's carrying (peacock-fletched arrows, a \"gay bracer,\" and a silver medal of St. Christopher), it's clear that the Yeoman is economically well-off and thus the sort of person who might raise a company of archers for service in war. The Yeoman is not mentioned to be mounted, but he could certainly afford a horse if he wanted one. Mounted archers were employed by the English for rapid movement on campaign, raiding, and scouting, although for pitched battles, they would dismount and fight on foot. \n\nSo how does that connect to the ranger archetype of modern fantasy fiction? Well, the \"ranger\" concept is essentially a blending of the roles of a yeoman archer. The peacetime duties of a forester and the wartime duties of an archer are blended into one role. Faramir's rangers^1 are actually a semi-accurate depiction of how yeoman archers fought. In the fight where they are introduced, they seem to have a force of archers deployed behind a screen of infantry. Their strategic purpose, disrupting enemy movement through Ithilien, is somewhat similar to the chevauchées of the Hundred Years War. A real chevauchée would often be focused on looting undefended villages rather than getting into larger fights, but sometimes the English launched large-scale raids for the purpose of forcing the French to come out and face them in pitched battles, which is a little closer to what Faramir seems to be doing. Lacking access to Gondorian accounts of their campaigns in Ithilien, it's hard to say how exactly Faramir was going about it. The only observers are Frodo and Sam, neither of whom had a keen eye for military details. The rangers of the *Ranger's Apprentice* series are a little more fantastical, since they seem to most closely resemble a 14th century CIA than any medieval archers. Fun for telling a YA fantasy story, but not really anything historical.\n\nTo sum up, the ranger archetype in fantasy fiction is an amalgamation of several different roles a yeoman might perform. Men with experience in foresting were considered to be the best source of archer recruits for a campaign, but they wouldn't be sneaking around on the battlefield wearing some kind of medieval camouflage. In a pitched battle, they'd be fighting in formation with the rest of their company. On campaign, they might be called on for raiding and scouting duties, but that wasn't a role exclusive to men with forestry experience. So the ranger archetype has roots in literary traditions and memories of medieval English archers, but isn't really reflective of their historical reality. \n\nEDIT (footnote)\n 1: That is, Faramir's rangers as they are depicted in the book *The Two Towers*. They're pretty much all Robin Hood in the movie. "
]
} | [] | [] | [
[]
] |
|
ayrbkw | When an animal is born with two fully functioning heads, how do their brains deliberate and balance control over the body? | askscience | https://www.reddit.com/r/askscience/comments/ayrbkw/when_an_animal_is_born_with_two_fully_functioning/ | {
"a_id": [
"ei5ctb1"
],
"score": [
2
],
"text": [
"Tried a quick google for some research but couldn’t find any. I assume it’s different from person to person. It would all depend on how their brains were connected to each other and the rest of the body I would assume"
]
} | [] | [] | [
[]
] |
||
dyyww0 | cocaine | So I read the post "[ELI5 LSD](_URL_0_)" and I was curious so I searched for some other drugs on the subreddit. While searching for cocaine I didn't really find a good explanation like I did for the LSD thread.
So I am wondering... What is cocaine and what does it do to your brain when you take it, and also what harm can it do to your body after extended use? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/dyyww0/eli5_cocaine/ | {
"a_id": [
"f84iao0",
"f84kxyi"
],
"score": [
2,
2
],
"text": [
"Cocaine basically causes loads of a chemical called dopamine to be produced and this chemical is normal produced in small amounts that then produces a signal that is turned into an action the amount of dopamine affects how big the signal is. This over production of dopamine means BIG signals are constantly being made and the nervous system goes into over drive and you feel high.",
"Fun fact: Cocaine is actually a local anesthetic medically. It is used a lot in facial surgeries to stop or help slow bleeding down in the nose and throat. Pretty effective stuff considering it provides numbness and pretty strong vasoconstriction (blood vessels tighten down reducing flow). The problem is that it ramps everything up and is like snorting adrenaline. It isn't quite that powerful, but same idea mostly. This is a stress response in your body and isn't good to expose yourself to that kind of workload regularly. It also stimulates the part of your brain that is activated when you make money."
]
} | [] | [
"https://www.reddit.com/r/explainlikeimfive/comments/dymtnq/eli5_lsd/"
] | [
[],
[]
] |
|
2nsj3u | why is it that mac operating systems rarely need to be updated yet windows seemingly needs to be updated every few days? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2nsj3u/eli5_why_is_it_that_mac_operating_systems_rarely/ | {
"a_id": [
"cmgg3pt"
],
"score": [
2
],
"text": [
"OS X does need to be updated~~graded~~ fairly often. The thing is, Apple makes it a fairly seamless process. Rarely does an update require a restart, for instance, while Windows updates tend to be very intrusive. If you select autoupdate for both systems, you rarely notice an OS X update, while Windows will kick you in the face and force you to submission every time it wants to apply an update.\n\nThat, and the fact that, for many different reasons, OS X tends to be a more stable environment than Windows.\n\n"
]
} | [] | [] | [
[]
] |
||
cms57p | Why are batteries arrays made with cylindrical batteries rather than square prisms so they can pack even better? | askscience | https://www.reddit.com/r/askscience/comments/cms57p/why_are_batteries_arrays_made_with_cylindrical/ | {
"a_id": [
"ew4avkn",
"ew4f0df",
"ew4hjvx",
"ew4ic1s",
"ew4j8c8",
"ew4qlq7",
"ew58w8u",
"ew5funv",
"ew68vi3"
],
"score": [
3343,
876,
11,
3,
73,
5,
34,
9,
4
],
"text": [
"First of all, some packs are made with prismatic cells. The pros and cons of cylindrical vs prismatic cells themselves are more important than packing efficiency. Notably, cylindrical manufacturing is more mature, and cylindrical cells tend to be better (in energy density and cost per kWh) at lower capacities, which most packaged battery packs are.\n\nHere's an in-depth article on the cylindrical vs prismatic question: _URL_0_",
"Mostly historical now.\n\nOriginally many mass-manufactured batteries were made by rolling flat sheets of material, inserting a rod, and filling the space with an electrolyte. It made for a fairly simple method of manufacture and was pretty reliable. By rolling a sheet around a tube you easily got a known size without needing spacers and rods were pretty simple to extrude. You could also cast or extrude the tube pretty easily.\n\nIf you went with two flat sheets you'd need several spacers to make sure the sheet was evenly spaced all around and a flat item is less structurally-sound than a round one. Look at the strength of an arch vs the strength of a square opening. \n\nIn addition, you have the highest ratio of volume to surface area with a round container. But if you go with a sphere you lose a lot of volume when you pack them. It turns out that a great balance of volume to surface area and packing units comes from cylinders instead of spheres or square prisms.\n\nSo most battery manufacturers settled around making cylindrical batteries rather than any other shape. The exception is when you really need to maximize volume, then they go with whatever shape does that best - such as in a cell phone, you'll see that the batteries will often be a flat rectangle which uses every bit of space possible.",
"In my space, cylindricals are better suited to high temps (they don't leak as readily as pouch cells) and they are also less dense so less likely to go into thermal runaway mode when the entire battery assembly is shot or damaged. Prismatics need to be very thin to avoid the issue of thermal runaway (barring any internal chemical safety brakes)",
"I have a similar question about the cylindical vs square batter setups. Is heat dissipation part of the equation when deciding between battery shapes as well? \n\nI'm thinking about larger sized batteries that would be packing multiple batteries in series for something (like in an airplane or a car). Packing them tighter with a square prism format seems like it would be more efficient use of space, but the gaps on the cylindrical batteries would provide more airflow. I recall there were some issues with a model of airplane (early A380s maybe) that had overheating/fire issues from the batteries being packed too tightly.",
"This is a complicated question, and the short answer is that cost, safety and efficiency are almost always more important factors than effective use of space.\n\nIt almost always comes down to per-unit manufacturing costs, which includes the tooling and machines to make the product or battery or costs like reject rates.\n\nThe notable exception to this is cell phones or other personal mobile electronics where space is a factor over almost everything else.\n\nOne of the main reasons they make higher capacity and amperage batteries round is entirely due to the manufacturing process.\n\nSo, a battery like a lithium-ion 18650 or similar is really a jelly roll of thin films, gel and metal foils stuffed into a thin metal can - or even just a foil pouch. It is an extremely high precision manufacturing process, so there needs to be an exact amount of tension on the webs of different materials that come together to be wound into the spool that becomes the core of the battery.\n\nToo much tension and you can tear metal foils, squeeze out the electrolyte gel so there's not a large or safe enough gap between electrodes. Too little tension and it doesn't make full contact with itself and won't fit in the metal battery can it's designed to fit inside. (Sometimes lower capacity or cheaply made batteries have empty space in the can!)\n\nAnd in either case if you don't get it right you have a potentially dangerous cell that could fail prematurely or even go into thermal runaway and catch fire or explode.\n\nNext let's look at prismatic lithium ion and lithium polymer batteries. For most cell phone type batteries they're made with a similar wrapping and coiling process using films, gels and metal foils. Those batteries aren't actually square, they're more like squashed circles or ovals when you look at a cross section.\n\nThe machines used to make them need to carefully adjust and maintain wrapping tension as the flat or oblong battery core is wound as the tension needs are different at the ends as opposed to the flat parts.\n\nSince the bend is tighter at the ends this introduces a stress point and point of failure, and the whole wrapping process is much more technically difficult and usually more expensive on a per battery cost.\n\nSo these kinds of oblong mobile electronic batteries tend to have thicker films as a safety feature, and this reduces their capacity.\n\nSo they're usually trading some capacity for that oblong shape and increased safety, which is why round cells can actually have higher energy density per cubic foot or weight than prismatic cells.\n\nBut wait, there's more! Let's look at AA, C, D and similar type cells. This battery format goes back nearly a hundred years at this point, and started with plain old zinc-carbon dry cell batteries. They don't use a roll of films like modern batteries, they use powders or pastes in a metal or even cardboard case.\n\nBut why are they round? Mainly because it's easier and cheaper to punch, draw and make metal shapes that are round than square or prismatic shapes. These cells also are a convenient shape for many consumer devices ranging from flashlights to portable radios.\n\nModern AAA, AA, C, D cells use either cylindrical, hollow pellets of battery chemicals or liquid gels, and using round cans means that they don't have to orient parts to match a square. All the parts in the stack are round and can go right in the can without having to have a complicated machine that lines up, say, square pellets or square seals in square cans.\n\nBut wait, what about other older square/prismatic batteries like the 9V, the 6V and 12V lantern batteries? What about car batteries and lead acid batteries?\n\nIn these cases these batteries were based on older battery chemistries that were actual \"piles\" and this is where originally get the name \"battery\" because it's a battery of plates or piles. Battery meaning a group or array of identical smaller things.\n\nIn these cases they were using many square plates stacked together. In original 9V batteries it was a stack of layers in that can, and similar constructions existed in 6v and 12v lantern batteries.\n\nSide note: today many 9v batteries are actually 6 AAAA sized cells inside a can because it's just easier to make 6 round batteries and stuff them in a box.\n\nIn lead acid batteries found in cars, forklifts or older generation battery banks or backup systems, they use cast lead grid plates and battery chemistry pastes soaking in an acidic liquid or gel electrolyte.\n\nThey also made these batteries square because it was easiest to do for this chemistry and manufacturing process.\n\nSo why not use these kinds of batteries in an electric car or solar home power rig?\n\nWell, they used to, and they still do. You still find them in heavy duty applications where they need a lot of reliable high amperage power where weight is less of an issue, like a forklift or the starter battery of a car.\n\nBut they don't use them in a Tesla because the weight to power ratio is just that much higher in a bank of 18650s or similar round batteries.\n\nThere's also now a lot more economic costs in manufacturing lead chemistry batteries. There's a fuckton of regulation and mandates about battery life and recycling them and so on.",
"One thing that's not being talked about is the tradeoff between density and cooling. If you simply pack many square prisims together they can't dissipate heat properly and the battery chemistry is destroyed by heat effects. Many lithium battery chemistries are very sensitive to temperature and ideally want to be always around about human body temperature. Too cold and they don't store energy/extract energy properly and too hot and you get long term damage that greatly shortens the lifespan of the battery.\n\nIf you do use prismatic cells you want to run coolant between the thin spaces between each of your packs or use cylindrical cells and run coolant around the batteries in the form of channels.\n\nOne additional factor is the manufacturing cost. It's great if your energy and power density is higher, but if that comes at a higher manufacturing cost then it's completely moot.",
"Hi! Professional battery systems engineer here.\n\nWhat’s inside the battery is a rolled up bunch of stuff, and how much of that stuff you have drives how much energy is within a cell.\n\nNow, there are a few different ways you can roll up this stuff, but you lose some efficiency at corners and where the jelly roll isn’t continuously overlapped. As such, the more continuous the curvature, the more effective the jelly roll is - with cylindrical cells being the best, and pouch cells being slightly behind (due to separator volume to prevent shorting taking up layer space instead of dead space and a few other factors).\n\nWith pouch cells specifically, you also lose the volume where the pouch itself is being sealed, which pretty dramatically reduces best-case system energy density.\n\nIt turns out that a cylindrical cell is very mechanically stable, and also low enough energy that a single-cell failure can be contained. That’s not the case with pouch cells (worst, must be continually pressed flat) or prismatic cells (not quite as good as cylindrical cells, but don’t need to be continually pressed flat), and battery packs also need structure for the various mechanical loads they might see.\n\nThere have been plenty of good battery packs designed around every cell form factor, but once you bake in the additional structure and fire protection pouch cells require for automotive applications, and the slightly-less additional structure for prismatic cells, cylindrical cells end up having slightly better energy density in most applications (read: every battery system I’ve seen).\n\nHowever, pouch cells have a cost advantage for a given amount of energy because they’re easier to manufacture. Prismatics are more expensive than pouches but usually less expensive per unit energy than cylindrical cells. Cylindrical cells will require about an order of magnitude more electrical connections to be made, which adds manufacturing cost as well...\n\nIn short, there are a bunch of different solutions depending on which optimization parameters you care most about. Right now in the industry does not have all of the right answers, which makes it a very good time to be an R & D-focused battery systems engineer.",
"It typically depends on the application. I work as a battery systems engineer for the auto industry. We design and manufacture the lithium ion battery packs for EV, PHEV and hybrid cars. All of our auto cells are prismatic pouches, mostly because they can be engineered into neat, space saving, modules. \n\nThis is very important in cars that are being converted into hybrid and PHEV, as the new battery back must fit within the old design. \n\nTesla uses cylindrical cells because they are easier and faster to manufacture, thus allowing for more overall capacity in a shorter time. \n\nCylindrical cells are typically easier to cool off as well, because their geometry allows them to transfer away more heat. \n\nAll in all though, the same voltages and capacities can be delivered with either prismatic or pouch cells. The capacity of either cell geometry is achieved by connecting many folded cells in parallel to build up the amount of current it can discharge. Those cells are then strong in series to build up voltages. \n\nSo, the main difference between the different shapes is really the context engineering constraints.",
"Prismatics are more expensive. laminated and film products are all cheaper in cylinders: tin foil, table cloth, textiles... the machine just turns with perfect precision. You need more robots to cut and place squares on top of each other.\n\nThe cylinders are also very strong. batteries require cooling space also. \n\nIf scientists find a non-laminate-film battery, like a solid state sponge/cube, then cylindrical will become more expensive."
]
} | [] | [] | [
[
"https://www.sciencedirect.com/science/article/pii/S0378775316315981"
],
[],
[],
[],
[],
[],
[],
[],
[]
] |
||
5raunu | Were more artillery shells fired in WWII or WWI per capita? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5raunu/were_more_artillery_shells_fired_in_wwii_or_wwi/ | {
"a_id": [
"dd5ur08"
],
"score": [
4
],
"text": [
"per capita what? Per artilleryman? Per frontline infantryman? Per European population?"
]
} | [] | [] | [
[]
] |
||
5fr7ox | what causes naturally "good" or "bad" memory retention in a person and why is there a difference? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5fr7ox/eli5_what_causes_naturally_good_or_bad_memory/ | {
"a_id": [
"dami57t"
],
"score": [
8
],
"text": [
"Since you're talking about memory retention, I'm going to skip over short-term memory, which naturally decays.\n\nTo start, the idea of having a *perfect* memory is a bit of a lie. It's totally normal to not remember every little detail. Memory itself is also a bit of a lie: your brain fills in the gaps if it needs to, distorts facts or details along the way, and flat-out jettisons some information. The experience of memory is quite subjective. Someone who believes that they remember things easily, whether that's true or not (since memory is also a bit of a lie), will claim to have a great memory. Someone who is caught up in the normal blank spaces might think that they have a terrible memory, even when there are probably in the normal range. It's normal to remember some things very well, and other things not so well. In reality, most people are more or less on the same playing field.\n\nA lot of memory retention simply comes down to observations and engagement. If you aren't actively engaged in observing things around you, you aren't going to retain those things. If you're sitting in the car, staring at your phone, you aren't going to remember the scenery passing by because you aren't really even looking at it. If you look out the window and really focus on what you see, you'll remember much more of the trip. This is partially why most people remember things more easily when they write information by hand: you are engaged with the information more deeply, so it's easier to recall. There are a million little memory tricks and \"hacks\" out there, and most revolve around making information more meaningful (mnemonics, repetition, connecting details, etc.). \n\nIt's normal to forget where you put your keys (once in a while). It's not normal to forget what keys do. Problems with memory retention and recall can happen when connections in the brain start to break down, when neurotransmitters aren't quite right, when a physical traumatic injury damages the brain, etc. Here are some examples:\n\n- Mental illnesses like depression and anxiety disorders, and psychotic disorders.\n- Drug and alcohol use.\n- Poor sleep.\n- Little or no physical activity.\n- Some vitamin deficiencies.\n- Brain injuries. \n- Some medications, especially things like benzodiazapines.\n- Neurodegenerative diseases like Alzheimer's disease.\n- Other physical illnesses.\n- Aging.\n"
]
} | [] | [] | [
[]
] |
||
2qvrf5 | Why do we have primary colours? | I posted this originally in AskReddit. I was sent here.
I'm sorry for asking so many questions at once. It started with only a few but I kept going. Thanks for any help towards the answers.
Light is just a certain frequency range of the EM spectrum.
Why can it be split up into distinct colours in a prism?
What makes these frequencies special over any of the other ones?
Why are blue, red and green special in the rainbow?
Why only 3? (I know you can make all the colours from them, but I don't understand why).
Is it possible to combine IR or UV with each other, or light, to get light?
Why do we have distinct primary colours?
Is it possible to pick 3 different colours as a base for the rest? | askscience | http://www.reddit.com/r/askscience/comments/2qvrf5/why_do_we_have_primary_colours/ | {
"a_id": [
"cna0pf4",
"cna1zkp",
"cna47kp",
"cna7oaa",
"cna7sbj",
"cnaajy9",
"cnaemmc"
],
"score": [
47,
3,
3,
13,
2,
2,
2
],
"text": [
" > Why can it be split up into distinct colours in a prism?\n\nWhen light crosses a material boundary it is deflected (refracted) by a certain angle depending on its frequency. So different frequencies will be refracted in different angles.\n\n > What makes these frequencies special over any of the other ones?\n\nThere's nothing special about the frequencies. What's special about the *colors* (frequency mixture) is that they consist of only one frequency—namely the one refracted to that particular angle.\n\n > Why are blue, red and green special in the rainbow?\n\nThey aren't. It's our eyes that make them special. We have three different kinds of color sensors in our eyes, and they respond differently to different frequencies. One kind responds most to blue light, another to red, and so on.\n\n > Why only 3? (I know you can make all the colours from them, but I don't understand why).\n\nBecause that's how human vision works (see previous answer). Each color we see depends on the response from the three kinds of sensors. There's nothing particularly special about the number three.\n\n > Is it possible to combine IR or UV with each other, or light, to get light?\n\nNo, light of different frequencies won't interfere with each other. This is due to the linearity of the wave model, or as physicists like to call it: the principle of “superposition.”\n\n > Why do we have distinct primary colours?\n\nI'm not sure I understand. They can't be the same because you lose a dimension of the color space.\n\n > Is it possible to pick 3 different colours as a base for the rest?\n\nSo long as they're linearly independent. E.g. you couldn't choose something like dark red, red and light red. You would only ever be able to make different shades of red.",
"We have three different color sensors in our eyes. Each sensor is sensitive to a range of colors, but red light only triggers the first, green light triggers only the middle one, and blue light triggers only the last. So if you mix various amounts of red, green and blue light, you can produce any color.\n\nSo the three primary colors are fixed by the human eye.\n\nEdit: No, you can't mix IR and UV and get visible light. The two wavelengths of light remain separate, even if they are both in the same physical space. ",
"Hi. Good questions. The world of science has been thinking about this since Newton. I'll try to answer each one. \n\nCorrect, \"light\" is just a range of EM spectrum (about 380 to 720nm with humans) though x-rays and microwaves are also \"light\" it's just that our receptors are not sensitive to them. \n\nA prism is an optical element that refracts light (bends/slows down light). Refraction is a function of wavelength so different colors (wavelwngths) have a different exit angle. \n\nThe frequencies are \"special\" only because we can see them, as defined by the human luminance response function. \n\nIn the rainbow it's self red, green and blue are not any more special than any other color. But just to get you thinking can you figure out what colors are missing from the rainbow? (I'll get to this later) \n\nThe ability to use three primaries to create all other colors (a false claim actually) is described by the trichromacy theory of human vision. That is we have three types of cones (people with normal color vision) each with their own spectral sensitivity (intensity of response per wavelength). So the stimulation in combination of these three sensors is what allows use to view all the colors we see. So if we create three light sources that each individually excite the cones we can create all the colors within that gamut... I can go into more depth on request \n\nYou can't see IR and UV light directly. But with UV for instance other effects exist. Since UV is a higher energy \"light\" source with higher frequency or shorter wavelength it can drop some of its energy to fall into the visible domain. This is call fluorescence, which you are most familiar with under blacklights. It's also used in fabrics and laundry detergents to make your \"whites whiter than white\". This the rare case where advertising really isn't lying to you. Do to fluorescence and the stokes shift that occurs (dropping to lower energy) there is more visible light coming off of a fluorescent material than is incident upon it. That's why they are so bright and appear to glow... Another interesting fact of mixing brings me back to the question of what color is missing from the rainbow, let me answer that now... Magenta (pink). This is because there isn't a single wavelength that represents the color Magenta it is purely a color made in the mind. It occurs when both your red and blue cones (short and long wavelength cones) are stimulated with little to no response to the green or medium wavelength cone... \n\nYes it is absolutely possible to use three different primaries, but you will suffer from a different gamut, and won't be able to produce all of the colors you would like to. \n\nI also need to step in an separate the difference between additive and subtractive color primaries. Additive primaries are what we have been discussing, things that produce their own light (sunlight, tvs, lasers, etc). Red, green, and blue are the additive primaries and can be mixed to make \"all\" (not really) colors. Subtractive primaries are those that absorb light and don't produce their own (inks, dye, paint). The primaries for these are cyan, Magenta and yellow (not red blue yellow as taught in elementary school). These can be used to produce \"all\" colors in a subtractive system (think printer). \n\nLastly when we talk about red, green, and blue. Remember that these are horribly defined terms. What red, which green? They all must be spectrally defined to be rigorous. \n\nBTW I study Motion Picture Science at university, feel free to have me clarify anything :) ",
"You've tagged this as \"physics\" but in my opinion it's mostly a biology/something else question. \n\nThe idea of primary colours makes sense because humans have only three types of light sensitive cones in our eyes, each specialized to a different wavelength, which means we can see a 3-dimensional space of colours (which reduces to a 2-dimensional space when ignoring \"brightness\").\n\nThere is really an infinite-dimensional space of colours, since you can make a colour by mixing together different wavelengths from the spectrum, with an arbitrary magnitude at each point, and there's no way to reconstruct one such arbitrary colour with just three primary colours. \n\nBut since humans only care about a 3d subspace of the colours, then we can accurately reproduce all of the colours we can subjectively see with a \"basis\" of three primary colours. This is analogous to how we can represent any point in space by giving three coordinates in *any* coordinate system. \n\nTo find out how to represent some given colour with some set of three primary colours, you'd need to first work out how each of the three colours stimulates each of your three types of photoreceptor cone, then work out how the \"target\" colour stimulates each of the three types of cone cell, and then perform a \"change of basis\" allowing you to write the desired colour in terms of the \"primary colour\" basis. ",
"Do we have primary colours... or do \"we\" have primary colours?\n\nWe have become aware that various creatures perceive portions of the spectrum which we can't. Some beasts detect and discern input in the ultra-violet band; pit vipers definitely detect and act according to infrared signals.\n\nOur primary colours are demarcated by relativistic positioning within such spectrum which we perceive- but what if the spectrum were larger -or were more restrained? \n\nIMO these variations should require a spectral shift in their resultant primaries. No?\n ",
"I'd like to answer this myself as I believe I can simplify and expand the subject a bit, as this is a very close subject for me, even though there are a couple of very good answers already.\n\nLike most of us are taught pretty early in school, there are three primary colors: red, green and blue. However, what color actually is, physically, is just light. \nAs we later learn in science classes light is electromagnetic radiation, and just a small section of its spectrum. All the different wavelengths of light in this section are different colors of light. So e.g. light that has a wavelength of 600nm, is somewhat yellow.\n\nSo why some colors are primary? It's our eyes! \n\nHuman eyes have cells that are sensitive to light, the rod cells and the cone cells. There are 3 different types of cone cells and they are sensitive to different wavelengths of light, or color, as said. These colors are the red green and blue, the primary colors! By sensing these three colors, the eyes can then interpolate all other colors without having to sense all the individual infinite wavelengths that enter the eye.\n\nHowever, this is as far as I have ever heard anyone explain this system to me. And it leaves questions. \nWhy can i see yellow if the cone cells only sense red green and blue? \nHow can they interpolate new colors if they never sense the incoming light at all? \n\nSo, an in-depth explanation: \nThe cone cells don't sense only a one wavelength of light, but a small range of wavelengths. But their peak sensitivity is at a certain wavelength. The peaks are at the wavelengths of the primary colors. The three kinds of cone cells' ranges also overlap each other, so that a certain wavelength of light can stimulate more than one type of cone cells.\nE.g. if yellow light enters your eye, both the red and green peaking cone cells react to the yellow light because the range of both of them includes the yellow light wavelength of ~600nm. So when your brain detects that both the \"red\" and the \"green\" cone cells are reacting both with 50-50 intensity, it interprets that sensation as yellow.\nTake a look at this diagram: _URL_0_ It pretty well visualizes how the sensitivity range of different types of cone cells distribute on the spectrum of light.\n\nThat means also that the eye can be fooled. Think about the television. There's only red, green and blue pixels in the screen, because they are the only colors that are needed to give the impression of the full color spectrum to humans. I could make a screen that has also yellow pixels to generate yellow light, but it is not necessary, since if we just shoot red and green light to the eye with the same intensity, we'd just see yellow. We cannot distinguish \"pure\" yellow ~600nm light from light that has just red and green mixed together.\n\nThis also brings me to my favourite subject, the magenta. I started learning about this subject when I realized that there is no color magenta in the rainbow. Why?\nThis is because magenta is actually created in our brain and doesn't exist physically, at all!\nWe see magenta when equal amounts of red and blue enter in the eye. The brain then interpolates a color that is between red and blue. But as the red and blue colours are in the opposite ends of the light spectrum, there is nothing in between them in real life. So the brain makes up a color that really doesn't even exist! Amazing!\n\nTo cap it: there's nothing primary about the wavelengths of red, green and blue, it's just the way the cone cell sensitivity ranges in the human eye are. They could just as well be any wavelengths if we would have evolved differently.",
"Primary colors essentially emerge from the frequencies of light that the rod and cone cells in our eyes are sensitive to. Cone cells come in three kinds (S, M, and L) and are sensitive in varying degrees to varying frequencies of light. You can combine the stimulation of each of these types of cells to produce a three dimensional color space, which is often depicted projected into a two-dimensional diagram like the one [here](_URL_0_). The thumb-shaped area represents all the possible combinations of stimuli you might receive. It's shape can be approximated with a triangle, so \"primary\" colors are simply those colors we pick that enclose the largest possible area within it. Not \"all\" colors are produced by combining any particular three primaries, it's just good enough that it seems that way to casual observation.\n\nNote that all of this is highly tuned to the way most people's eyes happen to work. For people who are color-blind, or for animals like mantis shrimp that have a broader spectrum available to them, this whole model would work differently."
]
} | [] | [] | [
[],
[],
[],
[],
[],
[
"http://i.imgur.com/zkUzxUU.jpg"
],
[
"http://upload.wikimedia.org/wikipedia/commons/thumb/0/08/CIExy1931_sRGB_gamut_D65.png/542px-CIExy1931_sRGB_gamut_D65.png"
]
] |
|
3kni3n | Back in the days when people believed witchcraft was a real thing and prosecuted people for being witches, how could they on one hand believe in malevolent magic and yet believe they could arrest, imprison and execute a "witch" and the witch would not escape/take revenge with their magic? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3kni3n/back_in_the_days_when_people_believed_witchcraft/ | {
"a_id": [
"cuywuld",
"cuz1ccd",
"cuz8tsd",
"cuzie1j",
"cuznw3r"
],
"score": [
874,
44,
23,
4,
2
],
"text": [
"The answer lies in our conception of magic. To most people in the modern world the first image that comes to mind is Harry Potter making things fly around the room, shooting big, violent spells everywhere. Historically, this is not how witches were seen. \n\nMagic was almost always related to a relationship with the Devil, which made it inherently evil. The witches gained their power by worshipping Satan. By doing his bidding on Earth, he in turn granted them with extraordinary powers. \n\nTheir resulting magic was much more subtle. Most reports from Europe and the Americas allege that a certain person cast some magic upon a cow and killed it or caused some crops to fail. Magic was used to harm others, but not in the direct way that we often see in popular culture. \n\nTake the Salem Witch Trials, perhaps the most famous example in American history. When a few girls started acting in a strange manner, screaming and writhing to draw attention, it was assumed that people had cast spells upon them to make them suffer. The results of this case aren't really important for your question, but this would be an example of a way that people believed magic took a direct and tangible effect.\n\nArresting and executing the witches was simply reasserting God's will on Earth. The witches were under guard and were never expected to bust out riding a broom while breathing fire. The most they could do was, in a rather lengthy time, slowly poison one's soul or cause incremental physical ailments. \n\nSo, since most of the time charges instead focused on abstract allegations of sabotage and rarely human violence, they were not too worried. Most mass-hysteria episodes coincided with difficult times economically, politically, or environmentally, but it was always easier to say, \"My cow died and I hate that girl. She's a witch!\" The girl could take revenge, but it'd be rather difficult for her to find the time to slowly implement her incremental magic if she's constantly under surveillance and then burned to death. \n\nEdit: Sorry for the lack of sources and formatting, I'm a little bit new here. \n\n* Dr. Brian Pavlac's book *Witch Hunts in the Western World: Persecution and Punishment from the Inquisition through the Salem Trials* is a good overview of the topic. If you want a quick version, his website lays it out pretty well with a few FAQs. \n\nFor example, regarding their conception of magic he writes, \"Usually the danger was seen in an organized conspiracy led by the Devil. Or the concern was witches causing harm (maleficia) through spells: raising storms, killing people or livestock, and/or causing bad luck.\" As people became more and more hysterical, the government almost always stepped in to counteract the Devil's influence, so it was very much an institutionalized phenomenon. \n\nHe also briefly comments on why outbreaks occurred in some places more than others. He writes, \"Historians are still trying to explain the reasons for this great variety in witch hunting. Important factors could have been: the power of the central government; the independence of local authorities; tensions created by war, failing economies, or famine; and uncertainties about religious conformity.\" \n\nFor more info on the Salem witch trials... \n\n* The rather famous Cotton Mather left a firsthand account of the trials. He describes how New England culture understood magic and its effects throughout. For example, he wrote the following of the first case that triggered the trials. \n\n > It was not long before one of her Sisters, an two of her Brothers, were seized, in.Order one after another with Affects' like those that molested her. Within a fe weeks, they were all four tortured every where in a manners very grievous, that it would have broke an heart of stone t have seen their Agonies. Skilful Physicians were consulted for their Help, and particularly our worthy and prudent Friend Dr. Thomas Oakes,' who found himself so affronted by the Dist'empers of the children, that he concluded nothing but an hellish Witchcraft could be the Original of these Maladies. \n\nAs you can see they didn't believe witchcraft worked anything like we do today. Because of this their fear of a witch locked up in a jail cell was naturally much different than our's would be. \n\nThere are many more books on the Salem Witch Trials, and it really is fascinating to look at why the entire thing happened. \n\n* I'd recommend *The Salem Witch Trials: A Day-By-Day Chronicle of a Community Under Siege* by Maryilynne K. Roach. It's essentially a timeline of the whole thing with the historical context. It's kind of long, but very informative, and not overly academic. \n\n* For a more scholarly take try *Entertaining Satan: Witchcraft and the Culture of Early New England* by John Demos. \n",
"I have to ask a follow-up. Knowing how the \"tests\" for being a witch were tests no one could pass, for example, I have often wondered if those prosecuting witches really believed in it or was that just political rhetoric. Have we any evidence historically that the powers that be really believed in it as much as the townspeople did? Were there any prosecutors who, through their writings, let on in some way that they did not believe but were promoting an agenda of some sort?",
"I think it might be interesting to add something to the top answer.\nI'm especially addressing the period of the 16th century in northestern Italy - but many of those consideration can be extended to central Europe during the same period.\n\n\nFor many people, especially in rural communities, the belief in witchcraft was deeply connected with the belief in god; thus the practice of religion, the traditional rites and rituals connected with the passing of the seasons, the cultivation of the fields accordingly to the lunar phases, etc. were deeply blended together. To believe in god, the devil, angels was almost the same to those people as to believe in curses and charms. And practicing this kind of magic was not necessarily in contrast with the belief in god and the church for them. \n\n\nNot only there were persons believed to have those kind of powers but they believed themselves to possess the ability to do those things, at least in certain special periods of the year. You can check [this](_URL_0_) wikipedia article or rather the main source, if you have it available (unfortunately I have it only in italian), which is: \n\nGinzburg, Carlo (1983) [1966]. The Night Battles: Witchcraft and Agrarian Cults in the Sixteenth and Seventeenth Centuries. John and Anne Tedeschi (translators). Baltimore: Johns Hopkins Press. ISBN 978-0801843860.\n\n\nHere the author mainly focuses on a group of people that called themselves \"Benandanti\" which I might translate with \"the ones who walk in the good\" and claimed to fight the evil doers. Many of them were born with a caul, which was thought of as a good omen. \n\n\nIn the words of one of them (I'm quoting from the wiki page, rather than translating myself from italian, but there are many other interesting testimonies from the book if you can find the engish version):\n\n\n*I am a benandante because I go with the others to fight four times a year, that is during the Ember Days, at night; I go invisibly in spirit and the body remains behind; we go forth in the service of Christ, and the witches of the devil; we fight each other, we with bundles of fennel and they with sorghum stalks.*\n\n\nTherefore you have people testifying they were walking around in spirit to fight against devils - some of them referred to themselves as \"God's hounds\". They admitted to perform charms and to have experienced temptation by the devil in various forms. In fact many trials in the region started with genuine interest from the church into these kind of beliefs, to determine wheter these people were lunatics or really practicing some sort of magic. Anyway those beliefs appear to have been rather common and widespread.\n\n\nThose ideas survived long after the witchcraft trials ended and you can still find traces of it in local folklore. For example in many cities in northern Italy they still celebrate the new year with the burning of a straw figure representing a witch, in order to favour a good reaping season. And in italian you still say that someone is \"nato con la camicia\" i.e. born with the amniotic sac to signify that he is somewhat \"fortunate\" or even \"charmed\". Similar expressions survive in other central euroepan countries.\n\n\nThus people were actually living in a complex net of - sometimes hard to concilate - beliefs, taken in between the church and its desire to establish a moral and material authority and traditions rooted in the pagan folklore. Many tried to concilate those contrasting issues by making up a system of beliefs which included and mixed together a bit of everything. In this context putting witches to trial was a way to prevent famines, fight epidemics, avoid injuries and people percieved and used those trials in a way not much different than taking care of murderers or thieves, for the belief in these kind of supernatural forces was deeply rooted in their society.\n\n\nI hope I didn't wander too far from the original question and this might be of interest to some.",
"I've been generally under the impression that often magical activities occur b/c of some form of intoxication. (I don't have any sources, and it's quite possible that I'm talking out my ass.) Is there any validity to this? \n\nFollow-up: have there been significant periods in Western history when magic has been seen as a primarily good or helpful activity, or has it always been vilified?",
"For a book that may complicate your understanding of witchcraft, I recommend [The Night Battles](_URL_0_), by Carlo Ginzburg"
]
} | [] | [] | [
[],
[],
[
"https://en.wikipedia.org/wiki/Benandanti"
],
[],
[
"https://books.google.com/books?id=LngTuKdHLiIC"
]
] |
||
1luxq8 | how do they decide, during sports broadcasts that vary in length, which ads to play? | I was thinking of this last night during the Broncos/Ravens NFL game. The game started 1/2 late, yet they had plenty of ads to play.
Do the companies buying ads have the option to be played only if there is extra time? Are there companies that pay for particular spots of the game, like right before kick-off? Are there companies that pay for ads only to be played if they have time, and don't pay otherwise?
I looked in the ELI5 history, and didn't see any questions like this. My apologies if it is a repost. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1luxq8/eli5how_do_they_decide_during_sports_broadcasts/ | {
"a_id": [
"cc2zhfq",
"cc2zoio"
],
"score": [
2,
2
],
"text": [
"They buy ads based on when they show in the game, not for a specific time. So I may set up a deal with them for an ad at the end of the first and third quarters, plus a commercial for halftime. \n\n",
"First of all as stated by the other person ad placement is all based on point in time based on the game, not a specific slot of time during the time allotted for the game. Second if an ad is not aired the contract for that airing is nullified and no money is paid to the channel or broadcast contracts, this is because you cannot predict when ads can be aired or exactly how many ads will be aired during that 3 hour window given to the game broadcast."
]
} | [] | [] | [
[],
[]
] |
|
bk6z5l | Did medieval knights lift? | Is strength training a modern phenomenon, or have people who wanted to become strong always picked up and put down heavy things over and over? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/bk6z5l/did_medieval_knights_lift/ | {
"a_id": [
"emedv6g",
"emg3jiu"
],
"score": [
12,
3
],
"text": [
"I highly recommend [this thread](_URL_1_) by /u/knight117 and [this one](_URL_0_) by /u/kardlonoc which both deal with the question you ask. \n\n & #x200B;\n\nThe TL;DR is \"sort of\". They trained but primarily in a more functional sense. Weapons practice, horsemanship, hunting, exercises in armor etc are all demanding activites. Added to this there seems to have been a relatively widespread focus on more general fitness among knights-to-be which involved things like lifting or throwing rocks, wrestling, climbing, jumping and running.",
"I will chime in again to sort of summarize the previous topic that was nearly four years ago as /u/superplaner linked. It is a excellent source and discussion. \n\nThe source of this is this article:\n\n_URL_0_\n\nTo answer your question, yes they did. There are pictures of knights and fencers lifting stones and throwing stones as part of their practice. However lifting wasn't 'dedicated' as it is today.\n\nTo explain a good comparison is a modern day boxer, fighter or Olympic fencer to be more on point. These athletes spend a majority of their time training, a ton of time in the doing what they do and practicing but also a good amount of time on general fitness such as running, lifting, stretching and whatever else they need to do. Boxers sometimes spend more time running in training than they do boxing just to amp up their endurance. \n\nAnother good comparison is soldiers which knights were. Soldiers don't spend all their time lifting, but rather training that allows them to be well organized at all times as a group in whatever they do with some practice into shooting and CQC. \n\nTo understand that, that while there was lifting, the act of practicing swordsmanship was generally strength training enough for them and the most effective. The article points out that new soldiers would often start off with weapons that were double the weight of the normal weapons and then would switch to normal weapons for real fights. \n\nBut do understand strength wasn't the only goal but obviously to use the sword to the best of your ability. To that regard, modern day weightlifters would be stronger than most knights...in terms of lifting weights\n\nBut as cheesy as it sounds strength wasn't pure back then, strength came from wielding a weapon of some kind, be it a sword or a bow that needed to be pulled and all the techniques that came with that. \n\nWhat knights did was not pure strength training as we know it but it was done to increase the physical strength of knights to a certain degree."
]
} | [] | [] | [
[
"https://www.reddit.com/r/AskHistorians/comments/2h2kwv/did_medieval_exercise_include_pushups_or_situps/",
"https://www.reddit.com/r/AskHistorians/comments/6lhry3/how_did_medieval_knights_stay_fit_for_combat/"
],
[
"http://www.thearma.org/essays/fit/RennFit.htm"
]
] |
|
3jyrmd | what mass an object should have so objects start orbiting it? | Or the correct question would be: what mass should an object have to create a gravity?
UPD: I have additional stupid questions from me:
1. In theory, if to an object add some speed in the space, will it move the same speed for ever (if its not affected by gravity from any other planet).
2. Does the speed of radio wave differs in the space and on earth?
3. How does engine work in the space, there's nothing to draft off? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3jyrmd/eli5what_mass_an_object_should_have_so_objects/ | {
"a_id": [
"cutdtpx",
"cutdyn4"
],
"score": [
7,
2
],
"text": [
"Any object that has mass has a gravitational field. You have a gravitational field. A feather has a gravitational field. Those fields are, however, extremely weak.\n\nYou could in theory, have an object orbiting around you, but in order to do this you'd have to be very far from any larger gravitational fields (such as that of Earth) that would disrupt it. The radius within which an object can orbit a body that is itself orbiting a larger body is called the [Hill sphere](_URL_0_). It depends on both the mass of the two bodies and the distance between them. For example, Earth has a Hill radius of about 1.5 million km. Objects within that radius can form a stable orbit around the Earth. Outside that radius, the orbit would quickly destabilize and the object would end up orbiting the Sun instead.\n\nIf the Hill sphere is smaller than the size of the object (as is the case for most spacecraft in Earth orbit), then that object cannot have a satellite - the gravitational field is dominated by the mass of the heavier body.\n\nThe other constraint is the shape of the object - a spherical bodies of constant density have a gravitational field that turns out to be equivalent to a point mass. All orbits around such a body are stable. If the object is irregularly shaped, or it's mass is not distributed evenly, then orbits may not be stable, and the satellite may end up crashing into the body.",
"To answer your other questions:\n\n1. Yes, it will move forever, because there is no resistance from air or something.\n\n2. Yes, the speed of radio waves is slightly different. Radio waves are just a form of light, so radio waves move with the speed of light. As with any wave, the speed of that wave depends on the stuff it moves thru. So light thru air moves slower then light thru vacuum (= space).\n\n3. A normal internal combustion engine (as in a car) doesn't work in space because it needs the oxygen in the air. And since there is no air in space the engine doesn't work. But, if you could supply it with oxygen, from a tank or something, it will work. \n\nEdit: spelling is difficult"
]
} | [] | [] | [
[
"https://en.wikipedia.org/wiki/Hill_sphere"
],
[]
] |
|
54vs81 | why are all cells considered to be living structures? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/54vs81/eli5_why_are_all_cells_considered_to_be_living/ | {
"a_id": [
"d85d0sg"
],
"score": [
3
],
"text": [
"The cells have all the traits we associate with living things. They eat food, they procreate etc. The cells in the human body isn't all that different from the cells of single cell organisms."
]
} | [] | [] | [
[]
] |
||
1ubluu | what happens to people in colorado who were already convicted of marijuana - related offenses? | What happens to people who were convicted of something that is no longer illegal?
EDIT: thanks for the quick replies! | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ubluu/eli5_what_happens_to_people_in_colorado_who_were/ | {
"a_id": [
"cegehqb",
"cegei99",
"cegejfh",
"cegh6nb",
"cegheqt",
"ceghicu",
"ceghvic",
"cegia40",
"cegiqh8",
"cegmmw5",
"cegpfh3",
"cegss6q"
],
"score": [
185,
38,
7,
3,
31,
2,
5,
12,
14,
2,
2,
4
],
"text": [
"You serve the remainder of your sentence. The change in law does not make something retroactively legal.",
"Nothing. \n\nThey were convicted of a crime. That fact that it is legal now doesn't mean it was any more legal then. ",
"You can't change a law and have it apply retroactively in the US. The convictions still stand as the actions constituted a crime at the time.",
"regret is what happens",
"Well technically it's still illegal to buy marijuana from certain shady individuals so their convictions are valid regardless. ",
"Related to this question though is the recent grant of clemency to crack cocaine sentences by the president. Could these people seek to be pardoned/granted clemency?",
"For all you ex post facto people who say they committed the crime so they still have to do time:\n\n\"Ex Post Facto clauses \"forbid the application of any new punitive measure to a crime already consumated, to the detriment or material disadvantage of the wrongdoer.\" (Lindsey v. Washington (1937), Calder v. Bull (1798)) There is, however, no constitutional limitation on retroactive application of criminal legislation which mollifies criminal sanctions.\"\n\n_URL_0_\n\nThe Colorado Legislature decided not to include retroactive ameliorative relief in the new law. That's the only reason it's not retroactive.\n",
"If you know something isn't allowed and you still do it, there are consequences for that. Now that marijuana is legal, it doesn't mean those people didn't commit crimes",
"Several counties here (I'm in Colorado) dropped all the cases on the books when the vote passed (even before it was law), some of the more... conservative counties did not. So it was a mixed bag.\n",
"Well since marijuana is only legal through certain vendors who are licensed, one would think that people selling it illegally would still be punished.",
"Nothing. They broke the law. ",
"They are in prison for violating the law, not for posession of marijuana. They *still* violated the law, so they still have to serve out their sentence."
]
} | [] | [] | [
[],
[],
[],
[],
[],
[],
[
"http://www.jstor.org/discover/10.2307/3311149?uid=2129&uid=2&uid=70&uid=4&sid=21103214106957"
],
[],
[],
[],
[],
[]
] |
|
9e1vxu | this siphon water experiment | Hey can someone break down this experiment? _URL_0_
I understand that this is a siphon, but whats the point of using the water bottle that is filled with a bit of water? Also what forces are causing the water to be able to move from the higher cup to the lower cup and not stay inside the bottle? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9e1vxu/eli5_this_siphon_water_experiment/ | {
"a_id": [
"e5lmn3f",
"e5lnd8k"
],
"score": [
2,
3
],
"text": [
"The force causing the movement of the water is pressure and gravity. \n\nwhen you suck on a straw, you are creating a low pressure area in your mouth, this causes whatever you are trying to drink to flow through that straw, because the air pressure on the surface of the liquid is pushing down on it, and you sucking on your straw is giving it a place to go.\n\nOK, about the video:\n\nThe water in the bottle is there to start the process. It's high up, and gravity causes it to start flowing into the lower cup. As it does this, it is making more room in the bottle than it had to start. It is effectively sucking water out of the bottle. It's creating low pressure, a vacuum. This \"sucking force\" then continues to \"suck\" the water from the higher cup. This happens because of the air pressure pushing on the higher cup's water is high enough vs the low pressure in the bottle to push the higher cups water up a bit, so you get that fountain effect. Then, the water in the bottle just continues to go down the blue straw, which continuous to \"suck\" the bottle and thus the higher cups water.\n\nIf there was no water in the bottle to start with, then you really just have a straw in a cup. A weird straw with a bottle on it, but just a straw. There's no difference in pressure, so the higher cups water has no where to go.\n\nActually you CAN start with no water in the bottle, but then you have to suck on the blue straw to start the process. Get the water to hit the blue straw, then the process will become self sustaining until the water is all, or mostly all, in the lower cup.\n\nEDIT: if you got 20 min to kill, here's [cody's lab building and testing a mercury vacuum pump like in the olden days](_URL_0_). It's uses some of the same principles.\n",
"So you understand that it's a siphon. You could siphon between the two glasses if there was just a single tube.\n\nThe bottle doesn't actually change anything - it could just as easily be a rubber hose connecting the two straws. When the water drops out of the bottle, it creates a vacuum, sucking water into the bottle from the upper glass. The only reason you start with water in the bottle is because you need to have the siphon primed (full of water) in order to get it going."
]
} | [] | [
"https://www.youtube.com/watch?v=pf33oquDddw"
] | [
[
"https://youtu.be/viJ3T-1KZqY"
],
[]
] |
|
2h2tim | what is the definition of life? | Like how is it different from that thing it was right before it mutated into life? And do we know how this happened already? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2h2tim/eli5what_is_the_definition_of_life/ | {
"a_id": [
"ckourry"
],
"score": [
6
],
"text": [
"All known life has a few things in common, organisms (things that are alive) have these in common: they're composed of a cell or cells, undergo metabolism, maintain homeostasis, grow, respond to stimuli, and reproduce. There are a few things that seem to do a few but not all of these processes, like viruses, which is why they're classified as nonlife or as some kind of intermediate gray area between life and nonlife.\n\nWe don't necessarily \"know\" nonlife mutated into life sometime in the past, but we view it as the most likely scenario because we do know that the Earth once had no life, and now, today, it does have life, and also because we know the processes it would have to undergo are theoretically possible. "
]
} | [] | [] | [
[]
] |
|
pe9h9 | category theory. | A friend of mine is teaching himself category theory and tried to explain it to me, but he's much further ahead of me. Is it possible to understand it without much formal education in higher maths (I have some background in Multivar Calculus, basic linear algebra, basic real analysis, basic set theory)? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/pe9h9/eli5_category_theory/ | {
"a_id": [
"c3opsv2"
],
"score": [
3
],
"text": [
"First, let's start with a couple of examples of what math subjects are like.\n\nIn Real Analysis, we start with some set of Real numbers and first we learn some stuff about them. After we know some of their properties, we then look at functions from real numbers to other real numbers, and we begin to ask questions about these functions. For example, are these functions continuous? Differentiable? Do two functions, *f* and *g*, behave nicely under operations like pointwise addition (*f*+*g*), pointwise multiplication(*fg*) and composition (*f*(*g*(x))). Basically, the study of functions on real numbers.\n\nIn Calculus, we begin with a bunch of (usually continuous, but they need not be) functions and learn a bit about them. Then we look at these two operators d/dx and ∫*f*dx that send differentiable functions to continuous functions and vice versa. (Someone could probably point out some technicalities in that Riemann integrals can operate on piecewise continuous functions and Lebesgue integrals can even work on functions with up to a countably infinite number of discontinuities, but they would be a nerd for pointing out such petty details) Then we begin to ask questions about whether multiple derivatives make sense, whether these processes are invertible, and how the set of functions changes on each apllication(ie the set of continuous functions is larger than the set of differentiable functions, which is smaller than the set of twice differentiable functions) and so on. Basically, the study of derivatives and integrals on functions.\n\nIn linear algebra, we begin by looking at some things called vectors that live in a vector field. After learning some of the ways they interact with each other through addition and scalar multiplication, we then ask questions about linear operators that relate some vectors to other vectors so that these structures are preserved. For example, are these operators bounded? Compact? How do they behave under composition? Basically, the study of linear operators on vectors\n\nNow, if we ignore the jargon terms then all the above paragraphs are essentially the same. \n\nCategory theory then is basically doing this same process abstractly on potentially unknown objects. That is, it is the study of morphisms(a fancy word for functions) acting on objects(which live in some category, hence the name). The goal, in some sense, is to work out the least number of properties we need to know about the category to know something about the morphisms. \n\nIn turn, we might then be able to sum up many branches of math at once, and say that since both the real numbers and vectors have property A, the morphisms on these categories, functions and linear operators must have property B, and this might save us work if a new branch of math was to open up. More mathematically, it also helps highlight the similarities and differences between various branches of math, and show us deep symmetries that we didn't notice before."
]
} | [] | [] | [
[]
] |
|
2lr27z | what is/are the difference/s between the arabic, turkish and persian people? | I know it's similar to how Japanese aren't Korean and Serbians aren't Croation,I tried finding more info but every piece of info is biased. Can someone elaborate more on this info, social, cultural, geneology etc perhaps including famous empires of each race/culture and famous contributions/people | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2lr27z/eli5_what_isare_the_differences_between_the/ | {
"a_id": [
"clxd8xx",
"clxdsqo"
],
"score": [
5,
19
],
"text": [
"All of them have a different language.\n\nArabic and Persians are very much oriental people, Turks are more \"western\".\n\nArabic and Persians ancestors always seems to be in the place they live now.Turkish people ancestors are from Middle Asia.\n\nYou can find more \"sub-races\" or basically races in Turkey(so much different appeareances, like some brunette people like Arabic or some Turks like from Scandinav)\n\nAbout social in Saudi Arabia and Iran have some rules because of Islamic goverment. Womens Sexual things etc. (the mysterious ninja womens!) In Turkey this is not a rule thanks to being a secular country(this is looking to be end in few years)\n\nAbout Empires, Ottoman Empire was \"Turkish-based\"(thats not a thing after 400+ years because of the mom of the kings. they was from other races)And the Empire was ruled these people for more than +500 years.\n\n\n\nPS:I tried to explain something with a bad english pls dont mind some mistakes :)\n\nEdit:I'm from Turkey.\n",
"Turks came from the Central Asian steppe as nomadic horsemen in late 1st/early 2nd millennium, taking over what had been the Byzantine, or Eastern Roman, Empire completely by the 15th century. The first Turks were Seljuk Turks; later came the Ottomans who created an empire that ruled much of the Middle East until WW1. They spread into South-Eastern Europe also. The Ottomans and Seljuks were Muslim; earlier Turks had been pagan or Christian even. They have their own Turkish language. Turkic peoples still live in Central Asia, notably in Turkmenistan. Azeris are also Turkic culturally, speaking a Turkic language, albeit including an admixture of Persian and Caucasian elements in their ethnic make-up.\n\nThe Arabs came from Arabia, where they existed as tribes that were not unified to spread their influence until the arrival of Islam with Muhammad in the 8th century. Arab armies then spread as far as Central Asia, conquering and converting all in their path very rapidly. This empire was later fragmented and lost; however they remained a largely Muslim people. Prior to Islam they were pagans, Christians or Jews. Like Jews they are a Semitic race and consider themselves children of Abraham. The Romans had extensive dealings with them as did the Persians and everybody since. They currently occupy Arabia and large swathes of Asia Minor outside Iran and Turkey as well as North Africa. They have their own Arabic language.\n\nThe Persians's recorded history goes back much further than either the Turks or the Arabs. They are an Indo-Aryan race that originates in what is now Iran and their culture dates back to early-Classical times, when they are famous for fighting with the Greeks. At times the dominant group, and hence the name of their empire, has been the Persians, Medes or Parthians, although all groups are now merged into the Iranian people. Other Persian empires have been named after the ruling family, as per the Ottoman/Seljuk Turkish Empires, including the Sassanid and Achaemenid Empires (which were many centuries apart.) the Persians were mainly Zoroastrian until they converted to Islam. As Muslims they are mainly Shia. They too have their own Persian language. The Kurds are a Persian people, although culturally distinct from modern Persian Iranians.\n\nThere are many cultural similarities between all three cultures due to the shifting boundaries of their Empires over thousands of years and shared Muslim faith.\n\nI could go on and on, but hopefully this gives you some insight and a fairly simple précis to aid further research of your own. It's a fascinating region and set of cultures!\n\nEdit: added that Seljuk Turks were also Muslim for clarity... Turkish people were originally pagan pre-Muslim era and some Turks living in Anatolia under Byzantine rule were Christian; however, both the Seljuks and Ottomans were definitely Muslims (although this did not prevent the Seljuks from enjoying very good relations and close alliances with the Christian Byzantines at various points, in between the times they fought...) \n\nAlso added a little information about other Turkic peoples, although having done so I notice that /u/HannasAnarion has done so in greater detail below rendering my edit somewhat superfluous :)"
]
} | [] | [] | [
[],
[]
] |
|
3m8w7q | Would we really have made more scientific progress today if it where not for the decline of the roman empire and the dark ages? | [deleted] | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3m8w7q/would_we_really_have_made_more_scientific/ | {
"a_id": [
"cvd6azt"
],
"score": [
13
],
"text": [
"For one, the Roman Empire was actually not a very innovative entity. There are a few pieces of advanced technology like concrete which would not be re-discovered until after the renaissance but for the most part the Empire was simply good at achieving the economy of scale through mass deployment of capital to accomplish public works projects (i.e roads, Coliseum) using existing technology.\n\nSecond of all the Medieval era had a -higher- rate of technological advancements than the Roman period. The medieval period saw significant advances in agricultural techniques (i.e the two fields/three fields system), equipment (i.e the heavy plow, better shipping) and machinery (i.e the windmill and the mechanical clock). While they \"looked\" less impressive than the Coliseum those are in fact more important in enhancing productivity and building up the basis for industrialization (i.e the first mechanical looms in the 18th century).\n\nThe other big thing is that people have a tendency to emphasis hardware (i.e steam engines, concrete) but it was really \"software\" (i.e commercial institutions which allows capital to be routed towards industrialization) which was probably the more important factor in industrialization. \n\nLast of all it should noted that the eastern half of the Empire (Byzantium) actually did survive for another 1000 years and did not industrialize. The idea that Rome was a lost technological paradise when compare to the Medieval era doesn't hold water upon closer examination."
]
} | [] | [] | [
[]
] |
|
1iyf4t | why are black holes not infinitely bright? | If a black hole has already consumed all nearby matter and is not changing in size, wouldn't there be an angle at which incoming photons would get permanently caught in orbit? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1iyf4t/eli5_why_are_black_holes_not_infinitely_bright/ | {
"a_id": [
"cb993gc",
"cb999xr"
],
"score": [
21,
5
],
"text": [
"If the photon is permanently caught, it cannot make it to your eye.",
"I'll try to clarify what I think is the main point of confusion:\n\nPhotons are not bright in the sense that you can see one flying past you. The **only** way to see a photon is for it to collide with your retina, thus adding energy to specific molecules in your cone or rod cells, causing them to change shape and trigger an electrical impulse to your brain. Objects that look bright do so because they emit lots of photons that enter your eyes and hit your retina.\n\nThis plays into another common ELI5 question of \"could you see a laser in space\". The answer to that is no, not unless the laser hits something and some of the photons bounce off that something and into your eyes.\n\nLikewise, you could not see photons in orbit around a black hole unless they left that orbit and hit your eyes."
]
} | [] | [] | [
[],
[]
] |
|
6xeuh3 | How much does drinking a cold drink really affect your body temperature? | askscience | https://www.reddit.com/r/askscience/comments/6xeuh3/how_much_does_drinking_a_cold_drink_really_affect/ | {
"a_id": [
"dmfew0c",
"dmffokx",
"dmffy6k",
"dmfgnr9",
"dmfhigh",
"dmfhp02",
"dmfhuus",
"dmfljsr",
"dmfp3x8",
"dmfrp4i",
"dmfrwda",
"dmg482n",
"dmg5vxk",
"dmg6gct",
"dmgbxra",
"dmgc1b2",
"dmgdsyx",
"dmgeobf",
"dmkfq5c"
],
"score": [
698,
11,
14519,
47,
681,
4,
8,
28,
2,
3,
12,
2,
5,
8,
5,
2,
6,
2,
2
],
"text": [
"We can do a very(!) rough back of the envelope calculation.\n\nAssume a 100kg person (I like round numbers). Assume that they're all water, so we have 100 litres. Assume that they're at body temperature, so about 310 Kelvin.\n\nNow you drink 0.2 liters of ice cold water, 273 Kelvin.\n\nSince both are water, they'll have the same heat capacity and the end temperature will be just a simple weighted average:\n\nT = (100 * 310 + 0.2 * 273) / (100 + 0.2) = 309.93\n\nso it's almost negligible, like a 0.07 degree drop.\n\nIf you wanted to be more accurate, you could use the average specific heat capacity of the human body. I can find it via google, but that would take the fun out of computing it. You'd use a weighted average of the capacity of water (60% of human body is water) and of things like proteins, fat, bones.\n\nIt wouldn't _drastically_ alter the equation though, the fact that the drop in temperature would be small will remain. \n\nLike, let's use the factor 0.5:\n\n(50 * 310 + 0.2 * 273) / (50 + 0.2) = 309.85, so now we're looking at a .15 degree drop. Still negligibly small.",
"Your body is an active machine programmed to keep a constant body temperature.\n\nIf I throw you into a pool of cold water your body will start sacrificing blood flow to limbs in order to maintain your core temperature. Therefore any change is actively counter balanced.\n\nIf you are asking about the ACTUAL change in temperature and expecting a difference you are SOL. If you are asking how much a fews cups of cold water have on a large blob of warm water that is easy. ",
"I'm an anesthesiologist. We monitor body temperature during surgery because anesthesia inhibits your ability to autoregulate temperature. Essentially you are turned into a poikilotherm like a snake, and lose heat to the cold operating room. An inability to contract your muscles prevents you from generating heat. We have a rule of thumb that 1 liter of room temperature intravenous fluids will reduce a patient's body temperature by 0.25 degrees Celsius. We used forced air warming blankets and heated IV fluids to maintain a normal body temperature, which helps the body to metabolize medications predictably and the blood to clot properly. \n\nAfter reading comments I want to add that the reason I brought up anesthesia here is that only when you remove the body's ability to generate heat can you actually measure a reduction in temperature, unless you infuse the fluid very quickly. When we drink cold fluids, the body generates heat to correct the drop in temperature before an appreciable difference can be measured. \n\nFurthermore, there are some interesting studies out there on this. Many involve rapidly administering cold IV fluids in attempt to show that hypothermia is protective against neurologic injury in situations such as cardiac arrest. \n\nHere is one study: \n\nAnn Emerg Med. 2008 Feb;51(2):153-9. Epub 2007 Nov 28.\n\nThey infuse cold and room temperature fluids rapidly in non anesthetized patients and measure a temperature change before compensatory mechanisms (shivering) can restore the body to normal temp. This is better than my rule of thumb as it uses weight-based dosing for IV fluids. Interesting, 30ml/kg of room temp fluid reduced the body core temp by 0.5 Celsius degrees. That would be 3 liters of fluid for a 100kg (220lb) person. Cold fluid reduced the body temp by a full degree Celsius. ",
"IIRC blood temperature is \"measured\" by the hypothalamus as part of thermal homeostasis. While a cold drink won't do much to cool the whole body's water content down you do have a good blood supply to the stomach and digestive system. I'd think that the the heat exchange between blood and cold drink in there would drop the blood temperature in the short term and con the brain into thinking the overall body temperature has dropped. \n\nYou can get a similar effect by sticking ice or a cold can on your neck near the returning blood supply to the brain. You feel cooler. \n\nCourse that's like blowing cold air on the thermostat in your house. Doesn't cool the house down. Just makes the HVAC think it's not needed.",
"You can check this article on popsci: _URL_0_\n\nLong story in short: There are some heat receptors in stomach helping your body determine sweating and drinking hot beverages may freshen you since you sweat more (and if the place is windy so that your sweat would vaporize, unless you just feel hotter) and drinking cold beverages lessen your sweating after an instant cooling so it depends on the environment. If the place is chilly/windy like in front of a fan, hot drinks better. But most of the time cool beverages are the best.",
"You may have also heard that drinking cold water burns calories as that water needs to be heated to body temperature after consumption. That is objectively true. The numbers are pretty underwhelming however. It costs your body approximately 8 calories (Kcal actually) to heat 1 glass of ice water to body temperature.",
"If you drink 1000mL of 2.6°C water, your body will raise it's temperature to body temp 37.6°C or +35°C. A small-c calorie is the amount of energy required to raise the temperature of 1mL of water by 1°C, so your body will burn 35000 small-c calories to raise the water temperature (plus some extra for muscle/brain/blood stuff).\n\nThere are 1000 small-c calories in a big-c Calorie, or food Calorie. So you burn at least 35 Calories by drinking a cold liter of water. Go ahead and splurge on that [extra plain rice cake](_URL_0_) buddy, you earned it.",
"Assume beverage is 500 ml at 0 degrees C and a core body temp of 37 C and a body mass of 70 kg, 18.5 kcal will be absorbed. Assuming uniform distribution of heat with a specific heat of water, temp will drop by 0.26 centigrade degrees.",
"The body autoregulates it's temperature through the hypothalamus, so when you're hot, your body tries to cool itself off. Conversely, if you're cold (or drink something cold), the body warms itself. This happens very rapidly. \n\nI work as a provider in an ER. We see staff tell parents to take off blankets and excess clothing of children that come in with fever, with the idea being it will help cool them off. However, there are recent studies demonstrating that there was no significant difference in body temperature changes between a group that did remove excess layers vs a group that did not; the idea being that the body is purposefully heating itself to fight an infection, thus protecting itself, and does not \"want\" to cool down. ",
"probably less than 5 calories (not kilocalories) and less than 0.1 degrees change in temperatures \n\nyou have a 70kg person at 36.5 degrees celcius, even 1L of ice cold water at 0 degrees is not going to make a big difference",
"This is my fault and I'm sorry. \n\nI started the entire rumour about drinking ice-temperature water would let you lose eight pounds in a year. In the year 2000, I was a second-year engineering student and my now-ex-wife asked me the question about whether drinking ice water would let you lose weight. \n\nSo I assumed the human body was adiabatic, that the water was 0C, and that the energy required to convert that water to 37C was all provided by food energy. So m*c*deltaT, - > 4.2 * 250 * 37 = 38, 850 ~= 9 dieter's calories.\n\n365 days in a year, that's 3285 calories in a year for one glass of ice water, which is more-or-less a pound. Every glass of ice water was a pound a year, thus 8 glasses of ice water would net you a loss of 8 pounds a year. \n\nThe problem was the initial assumptions were totally flawed; I didn't know about how much waste heat the human body provides. You wouldn't lose any weight from drinking ice water because you would just emit a little less heat into the environment. ",
"Not in any way you're going to notice. Your body works hard to keep your temperature the same. If you were to drink enough cold water to change your body temperature noticeably it would be extremely uncomfortable.",
"If mean body temperature is 35 degrees Celsius and body mass is 75 kg, drinking 0.5 kg of cold water at 5 degrees Celsius will decrease the final temperature of the combined mass of 75.5 kg by about 0.2 degrees.\n\nNote that mean body temperature is not the same as core temperature (the temperature within your torso where the internal organs are); the temperature of body extremities and skin is usually lower than the core temperature.\n\nHowever this is not really realistic way to look at things because human body produces heat and the cold liquid does not and cannot immediately change the overall temperature of the body, regardless of how good a heat conductor living tissue (water) might be.\n\nA more sensible way to look at the situation is to estimate the amount of energy required to bring the cold fluid up to core temperature of ~37 degrees Celsius, which of course is exactly what happens after you drink it - the body around the cool liquid initially cools down while the water is warming, but instead of reaching a thermal equilibrium at some lower temperature, the body's thermoregulation kicks in and your body produces some extra heat to bring itself back up to normal temperature. So, the actual answer to your question is that drinking a cold drink *doesn't* really affect your body temperature, because the body keeps its own temperature at what it should be.\n\nInstead you could ask, what does the body have to do to maintain its temperature after drinking a cold drink?\n\nSo, if you drink 0.5 kilograms of water at 5 degrees Celsius and it needs to be heated to 37 degrees Celsius, the change of temperature is +32 Kelvins, specific heat of water is 4.178 kJ/(kg K), so the total energy expenditure of heating the water is 66.848 kJ, which rounds up to about 67 kJ.\n\nThis is about 16 kcal, in nutrition energy terms, so by drinking half a litre of fairly cold water you spend about that many kilocalories. Not really a big shift of balance either way.\n\nOf course, if you're drinking something else than water, the energy expenditure usually gets obliterated by the energy content of whatever you're drinking. Beer, for example can contain as much as 200 kJ per 100 ml, so a 500 ml can of beer (not quite a full pint but close enough) can contain as much as 1,000 kJ of energy, or 240 kcal if you prefer. By comparison, classic Coca-Cola contains 176 kJ / 100ml, so 880 kJ for half a litre drink.",
"Not a whole lot. For instance when donating blood or plasma you are advised not to drink anything too hot or cold before they take your temp. It will never lower it more than .5 degrees but that can make a difference.",
"I lived most my life in the South where it gets plenty hot. Drinking a liter of cold water always feels good. It keeps you hydrated, obviously. But you can feel it cooling the blood coursing through your body. So maybe not an overall temperature decrease, but a temporary cooling sensation? What say you Science?",
"Well it should be really simple. We're made of mostly water. Drinks are made of mostly water. If we're 70kg, and standing out in the sun all day so our body temperature is 39 degrees instead of 37, and we quaff 1L of ice water, an approximate calculation is simple to do.\n\n70kg@39C + 1kg@0C = (39/70) degree reduction in your temperature. You would expect to be about 38.5 degrees afterward.",
"What about drinking something cold causing other things to happen, for example diarrhea. I live and work in China and everyone always says drinking cold water will give you diarrhea and make you sick. I have always assumed it wouldn't be able to lower your body temperature that much and that cold water would only give you diarrhea if it was from a stream or lake and bacteria was present in the water. Is there any scientific evidence to suggest that drinking cold water would cause diarrhea? I've been arguing about this with my friends for years and would love some scientific evidence to prove either side",
"Thermodynamics is not my strong suit but I would assume the cold liquid would take the energy from the system (in this case, the body) and homeostasis would kick in and expend energy to bring the temperature up to normal.\n\nFor example; drink 1L of water at 7 degrees Celsius the body would expend roughly 30,000 calories (or 30 kCal) bringing the temperature of the water to body temperature (yes, I know the water is technically leeching heat from the body until they both reach an equilibrium temperature then the body expends energy bringing itself up to 37C).",
"\"When we encounter cold air or water, the lacy network of blood vessels in the skin constricts, and blood is hastily shunted to the interior. ... It's not a total gain, though, because exercise also increases blood flow to the skin, so some body heat escapes.\"\n\n_URL_2_\n\n\"Drink room temperature water for digestion, detox, and pain relief. When you drink cold water, your blood vessels shrink, and this restricts your digestion. Warm water helps break down food, aids constipation, and even helps you lose weight while improving your blood circulation.\"\n\n_URL_1_\n\n\"When you drink cold beverages your blood vessels shrink, your digestion becomes restricted and hydration is hindered.....\"\n\n_URL_0_"
]
} | [] | [] | [
[],
[],
[],
[],
[
"http://www.popsci.com/does-drinking-hot-liquids-cool-you-off#page-3"
],
[],
[
"http://www.quakeroats.com/products/rice-snacks/rice-cakes/salt-free.aspx"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"https://books.google.com/books?id=_McpDwAAQBAJ&pg=PA105&dq=cold+water+blood+vessels+drinking&hl=en&sa=X&ved=0ahUKEwjE-azwy4zWAhXG3YMKHditDBYQ6AEIOjAD#v=onepage&q=cold%20water%20blood%20vessels%20drinking&f=false",
"https://spoonuniversity.com/lifestyle/water-temperature-cold-or-room-temperature",
"https://www.health.harvard.edu/staying-healthy/out-in-the-cold"
]
] |
||
h2lqn | Is it possible to develop astigmatism over time? | I have been told since I was 12 that I was near-sighted, and I've had a handful of eye exams since then. My vision isn't that bad.. I think I recall being -2.5. I can't read the numbers on the latest prescription that was just given to me (silly doctors.. with their writing). Anyway, this entire time, nobody has said anything to me regarding astigmatism. I just went to get an eye exam at a non-profit place, since it's been a few years and I've been too broke to do it, and they were like guess what? Astigmatism. I didn't know if he was full of shit or if I'm just stupid for not asking prior to this. My dad has it. Guessing it's genetic? | askscience | http://www.reddit.com/r/askscience/comments/h2lqn/is_it_possible_to_develop_astigmatism_over_time/ | {
"a_id": [
"c1s4xlw"
],
"score": [
2
],
"text": [
"My optometrist has informed me that in more serious cases of myopia, astigmatism usually develops. I myself are about -10 and -11 for myopia, and has astigmatism (although I forgot the axes figures).\n\nThe cause of either disease has never been made clear to me, and I'd be interested to hear from a professional the reasons for it."
]
} | [] | [] | [
[]
] |
|
mos2i | Can you recommend resources that can be used to teach the Enlightenment to high school students? | I am in a credentialing program to become a history teacher, and I am putting together a unit plan for the Age of Enlightenment as a final project for a class. The unit will be about 3 weeks long for a high school class. What are some good documents, preferably short (high school, though can be longer if you could recommend a particular section of it for such a class), or other resources that I could include in a lesson or build a lesson/discussion around.
I am thinking of starting the unit out with the scientific breakthroughs (Bacon, Newton), moving from there onto social aspects (maybe part of Kant's What is Enlightenment, Diderot), into political (Locke v ~~Hegel~~ Hobbes), and then transition into the revolutions. This is, as you can see, rather vague right now so I would love to find some great resources that I can use to structure lessons and my unit around. Any ideas?
| AskHistorians | http://www.reddit.com/r/AskHistorians/comments/mos2i/can_you_recommend_resources_that_can_be_used_to/ | {
"a_id": [
"c32s45m",
"c32vb02",
"c32xa0r",
"c32s45m",
"c32vb02",
"c32xa0r"
],
"score": [
2,
2,
2,
2,
2,
2
],
"text": [
"It depends on how far you wish to go with the ideas. The ideas of Francis Bacon certainly weren't new to Europe, and he really didn't have any breakthrough with science. He didn't make calculus or describe the motions of the stars. Roger Bacon said everything he did many years before; and even he was influenced by Middle Eastern scientists.\n\nThough Diderot was of importance, he is greatly overshadowed by Rousseau and Montesquieu.\n\nLocke v Hegel is incomplete, as Hobbes was greatly against everything Locke stood for, and that's not even mentioning Hume.\n\nRussell's \"History of Western Philosophy\" is a great text on Western Philosophy, and there's quite a few sections on Enlightenment era philosophy in it that are in detail without being boring. Drawing on that should help quite a bit",
"I am posting this so I come back later but one of the best things for this, depending on your students, could be a French Revolution simulation. I will come back with more when I have not been awake for 20 hours.",
"As a student, I found this progression logical and chronological: starting with astronomy (we covered the Ptolemaic system first for background, then Copernicus, then Kepler and Galileo), using Newton as a bridge, then logic (compare/contrast Bacon and Decartes), then covering the social aspects (talking about various philosophes).\n\nWe read excerpts from Descartes' Discourse on the Method, Bacon's Novum Organum, and Newton's Principia. In small sections they are manageable.",
"It depends on how far you wish to go with the ideas. The ideas of Francis Bacon certainly weren't new to Europe, and he really didn't have any breakthrough with science. He didn't make calculus or describe the motions of the stars. Roger Bacon said everything he did many years before; and even he was influenced by Middle Eastern scientists.\n\nThough Diderot was of importance, he is greatly overshadowed by Rousseau and Montesquieu.\n\nLocke v Hegel is incomplete, as Hobbes was greatly against everything Locke stood for, and that's not even mentioning Hume.\n\nRussell's \"History of Western Philosophy\" is a great text on Western Philosophy, and there's quite a few sections on Enlightenment era philosophy in it that are in detail without being boring. Drawing on that should help quite a bit",
"I am posting this so I come back later but one of the best things for this, depending on your students, could be a French Revolution simulation. I will come back with more when I have not been awake for 20 hours.",
"As a student, I found this progression logical and chronological: starting with astronomy (we covered the Ptolemaic system first for background, then Copernicus, then Kepler and Galileo), using Newton as a bridge, then logic (compare/contrast Bacon and Decartes), then covering the social aspects (talking about various philosophes).\n\nWe read excerpts from Descartes' Discourse on the Method, Bacon's Novum Organum, and Newton's Principia. In small sections they are manageable."
]
} | [] | [] | [
[],
[],
[],
[],
[],
[]
] |
|
4sgdae | When hate crime laws are passed do they actually reduce the occurrence of that type of crime, or have virtually zero effect on the suspect's motivation to commit the crime? | askscience | https://www.reddit.com/r/askscience/comments/4sgdae/when_hate_crime_laws_are_passed_do_they_actually/ | {
"a_id": [
"d59kfb1"
],
"score": [
2
],
"text": [
"I think it just affects the punishment mostly, which in turn would affect the occurrences. \n\n It's not only to deter hate crimes, but that a hate crime is punished differently and perceived differently. They've found that hate crimes, or biased crimes, affect the community a lot more that non-binary crimes because they are motivated by different emotions. Hate crime laws protect minorities in that they KNOW that the bias was acknowledged and punished. It's essentially a specific case of assault/homicide/murder based on motivation. \n\nExample: \n\nan assault is usually categorized as a misdemeanor. In Alabama, a misdemeanor assault can be punished up to one year in jail along with fines etc. But if that misdemeanor assault charge was found to be a hate crime (motivated by race, religion, etc). There is a MINIMUM of 3 months in jail.\n\nIn Georgia, a felony assault charge is 1-20 years in jail. But a felony hate crime must be punished more severely that an assault of the same level, and the person HAS to serve at least 90% of their time before being released."
]
} | [] | [] | [
[]
] |
||
1yddbe | I'm a young Macedonian man in the Hellenic period. Why would I follow Alexander the Great to the edge of the known world knowing that death was certain? What was life like for me during Alexander's conquests? | *Clarification*: Hellenic period should be Hellenistic Period | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1yddbe/im_a_young_macedonian_man_in_the_hellenic_period/ | {
"a_id": [
"cfjk1dl",
"cfjlt57"
],
"score": [
102,
35
],
"text": [
"This is a great question and a fascinating one. It's always difficult to tell what the average person's life was like in antiquity. If you ever study Alexander's life in depth, you'll run into many unanswered questions and conflicting accounts. If a figure as famous as Alexander remains mired in ambiguity, imagine how tough it is to pinpoint the life of this \"average man\".\n\nFirst, it's reasonable to conclude that the average soldier didn't know they were going to the edge of the known world. The most they knew was that, after the Greeks were suppressed, they were headed for Asia Minor. Alexander probably didn't even know he was going to end up in India.\n\nIt's also important to note that these weren't people randomly joining up. Alexander's father, Phillip II, handed him \"the most perfectly organized, trained, and equipped army of ancient times\", according to JFC Fuller (maybe hyperbole/exaggeration but it illustrates the point well.) \n\nSecond, death was not \"certain\" any more than death is \"certain\" in any military campaign. Why does anyone do anything? Because it's a job; because there's treasure abroad; because there's honor in battle; because your culture and society expects you to fight; because you've been raised as a warrior since birth; because they were conscripted during the campaign; because they fought as allies for political reasons or as mercenaries for monetary gain.\n\nThere's thousands of reasons why someone would fight. With the dearth of primary sources (e.g. \"Dear diary, I am joining Alexander's army because XYZ\") it's difficult to pinpoint what the average soldier lived like, much less what ambiguous concepts and paradigms drove them to pick up a spear and go kill people in Asia Minor.\n\nThe primary sources we do have are often Alexander's top lieutenants talking about the man himself, troop movements in the aggregate, grand strategy, and so on. When they do address the troops, it's usually as brief as \"the troops were happy because we won\" or \"the troops were pissed for lots of reasons. Then Alexander gave a great speech that everyone loved.\"\n\nYour third question is a little easier. We know a fair amount about what life was like. For instance, Alexander had this group of elite soldiers called the Heitairoi, or the \"Companion Cavalry\". We know that they loved to do two things: Drink and hunt. Alexander himself got some pretty serious alcohol poisoning during a big party with the Hetairoi a few weeks before he died. It's hard to tell from the sources, but they certainly seem related.\n\nWikipedia is a pretty good source on the Hetairoi. This article seems moderately well sourced and accurate: _URL_0_\n\nWe know plenty aout the more technical details; equipment, logistics, and so on. The average soldier's load, for instance, was thirty pounds. Most were on foot, but the wealthier soldiers were on horseback. Most of the gear was carried by troops, rather than servants or pack animals, which meant the army was mobile and flexible (but that also means the every individual dude was humping his own gear for thousands of miles on foot). There are lots of sources about this and they're easy to find; some of my info comes from here: _URL_2_\n\nMany of these young soldiers found wives in Asia Minor, following the \"conquering\" of the Persian Empire. Some accounts suggest Alexander encouraged this.\n\nPeter Sommer's writings are highly interesting. He's not really a historian, but he replicated Alexander's journey on foot. There's a documentary on YouTube where he makes a bunch of observations about what it must've been like. You can read more here: _URL_1_\n\nUltimately, the best place to look to is the sources. The original accounts of Alexander's lieutenants have been lost, but we have five main surviving accounts based on those lost accounts: Arrian, Curtius, and Diodorus Siculus (also Justin and Plutarch but those wouldn't help answer your question at all). These are fairly cheap. They are also probably available on google scholar, perseus or some other database.",
"First of all, there have been a lot of people recently on this sub using the term \"Hellenic Period.\" There is no such thing as the Hellenic Period. Greek history in antiquity is divided into the Dark Ages, the Archaic Period, the Classical Period, and the Hellenistic Period. The Roman Period is also referred to, and the Mycenaean and Minoan Periods are often referred to, although the technically correct thing to do is to refer to them by their Helladic Bronze Age labels.\n\nOkay, got that through with. I once had a professor who explained the purpose behind war and joining an army in the ancient world with a single sentence: booty. Obviously it's more involved than simply grabbing plunder, but for an ordinary man, even for a king the spoils of war from plunder alone are incredibly vast. The study of ancient economies has shown generally that warfare was one of, if not the singlemost, important economic activity for most ancient societies at a certain level, and even past that level of development it is still of enormous importance. The promises of sharing in the spoils of war would be incredibly important for an ordinary soldier, something that is clear again and again in accounts of armies from Hannibal to Caesar and even to Xerxes. With regards to Alexander, remember that the troops of the Phalanx probably weren't paid, unlike the mercenaries in the army, until towards the end of the campaign, when they demanded from Alexander what they were due.\n\nBut I said it was more complicated than that. Well, yes, it is. But it varies greatly from place to place. The feeling of necessity to follow a strong leader in antiquity is a pretty strong one, often descending from rituals and the traditions of ancestors, i.e. you follow your leader because it's the thing to do. Members of ancient societies don't really follow the same thought processes that we might, particularly in weighing the pros and cons of a decision like this. They'd just do it because it's considered necessary. \n\nSo I said that it varies. What about Macedon? The kingdom of Macedon was extremely backward compared to the rest of the Greek world. So backward, in fact, that it preserved social customs that had been lost *in the Dark Age* or even before. Yeah, that old. That archaic. In particular, scholars often stress the degree to which the Macedonian society which Philip took over resembled that of Homeric Greece. It's an analogy that can easily be taken too far, but in many ways it's very true. Macedonian society was grounded in a highly hierarchical system of barons, lords, and vassals, and while the individual man wasn't really a serf the way he might be in the Middle Ages, he still owed direct allegiance to his lord. The Macedonians of Alexander's army serving in the Phalanx would've thought of their service more or less along the same lines as the faceless masses of men standing behind the champions in Homer. They were there because their lords had gone to war and they owed their lords a duty. \n\nThat of course isn't the only reason. Human beings are complicated, and Philip's levies were taking place at a time when he was trying to restructure Macedonian society (or at least the aristocracy) in a revolutionary way. But they're certainly very important reasons and ones that would've been foremost in the minds of the soldiers. I think the most important objection that can be made to all of this is the mutiny of the soldiers. If Macedonian society was so rigid that troops would allow themselves to be conscripted (remember that these guys aren't going voluntarily, but because their lords have conscripted them) why would they revolt? For one thing, it didn't even occur to them to revolt for years, despite all the hardships they faced. Many scholars see it as an indication of just how hard these men were pushed by the end that it finally broke out in revolt, not only against their king, but against their lords as well. It's also an indication of just how rapidly Macedonian society changed during that time.\n\nNow, I haven't really answered the question satisfactorily, and I'm aware of that. The difficulties in ascertaining a person's motives without any direct evidence are of course immense, but I what I've tried to do is steer you towards the right path in understanding the cultural and social stimuli that would've been driving these men. The best thing to do is to really acquaint yourself with the social and cultural idiosyncrasies of Macedonian society to really get a handle on the way these people thought. I recommend taking a look at Hammond--he's somewhat out of date, but his work on Macedonian society and how it influenced Alexander is quite important. "
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Companion_cavalry",
"http://www.petersommer.com/travel-writing/alexander-the-great-travel-article/",
"http://books.google.com/books?id=OiMWqRokCZ4C&pg=PA24&lpg=PA24&dq=alexander+the+great+average+soldier&source=bl&ots=mhOgLzEmRR&sig=4wDkMY4yCakAv9UOG_RPuGDGYR8&hl=en&sa=X&ei=ECMFU9DwKYrp0AGanYCIBw&ved=0CFsQ6AEwBzgK#v=onepage&q=alexander%20the%20great%20average%20soldier&f=false"
],
[]
] |
|
2vshz3 | how is my brain able to go into this zoned-out "auto-pilot" state while i'm driving, yet i get to my destination safety with no real recollection of the trip? | I'm obviously not veering all over the place or putting anyone else in danger. It's like my brain goes into it's own cruise control. What is actually going on when this happens? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2vshz3/eli5_how_is_my_brain_able_to_go_into_this/ | {
"a_id": [
"cokj9eo",
"cokjjxk",
"cokmukm",
"cokn0t2",
"cokntua",
"coknzti",
"cokocow",
"cokoxe0",
"cokpedc",
"cokq8ns",
"cokqueq",
"cokqxr2",
"coktamj",
"coktme7",
"cokviqi",
"cokw2c3",
"cokw7gv",
"cokx68c",
"cokxi29",
"coky4ue",
"coky9wn",
"col2g34",
"col2yxy",
"col37qh",
"col4pwz",
"col703i"
],
"score": [
4,
658,
2293,
10,
7,
7,
5,
2,
2,
2,
3,
3,
2,
12,
3,
3,
2,
2,
6,
3,
2,
5,
2,
4,
2,
2
],
"text": [
"It's not something you need to focus on any more than you need to focus on walking. Your brain is good at internalizing things and deciding not to remember unimportant things, so you can usually split your focus while walking biking or driving because you've had so much experience doing it that you don't need a conscious effort to keep balance when walking or follow cues from signs while driving or whatever.",
"Mostly habit and behavioral memory. You've spent a lot of time driving, so your brain knows what to expect from the experience. When what you experience matches those expectations (normal driving conditions, for instance), your brain accesses that experience and carries out whatever task you've associated with it. \n\nSo, your brain sees that you're on the road and knows you need to stay between the lines, travel at a certain speed, etc. Combine this with the muscle memory used for the physical act of driving (how you know how to keep the gas at a certain level to maintain speed without actually checking the dash), and it results in the \"autopilot\" state. \n\nWhen something *doesn't* match those expectations, like the car in front of you stopping abruptly, you'll often \"snap\" back, and your brain will need to problem-solve in real time rather than drawing on habitual behavior. \n\nI'm not a psychologist, so others please correct me if necessary. Some good discussion on this subject (if a lot more technical), [here](_URL_0_)",
"Psychologist here. This happens for essentially the same reason that you Can \"zone out\" while you're walking around, not stumbling or colliding with things. These tasks are called \"steriotypic repetitious movements\" and they are actually controlled by a different part of the brain after you've fully learned the skill! When you start to learn any skill, like riding a bike, your cortex is the part of the brain doing the work of figuring out how to coordinate your muscles appropriately. Its complicated at first, and it involves your full attention, just like when you learned to walk. However, over time your cortex figures out exactly which muscles need to coordinate in exactly the right way, and it basically \"saves\" that motion in memory. When you go to do that action again after its already been learned (or saved) a cool thing happens, the cortex isn't nearly as involved anymore, now it's more subcortical (aka below the cortex, so deeper in the brain) regions that control the movement. The result? Now you perform an action while your cortex is free to think (or not think and \"zone out\") and forget you're actually doing anything complicated at all. \n\nEDIT. Thanks for the Gold :) ",
"Look up reticular activating system. once the trip is known to you, your brain processes it without shoving every detail in front of your conscious mind, instead you only get signals for the 'dangerous' stuff. You RAS processes the minute-by-minute stuff and just dumps the not-interesting stuff instead of giving you a signal on it. (this is the same reason you don't hear all conversations in a crowded room, but DO hear when your name is said... you're RAS always alerts you when it thinks it's heard your name.)\n\nIf the conditions are unsafe of you've been startled, your RAS will suddenly become more paranoid and post signals all the way along because you're conscious mind has decided to pay attention because something is dangerous out there.\n\nOn the other hand, when you start out with a positive thought for the day and intention to have a better day, you program your RAS to look for links and associations and that's why positive mantras work to make your life better.\n\n",
"I think it's mostly that the brain discards uneventful memories. You have in all likelihood been driving safely and attentively but your brain doesn't see the need to retain the detail of yet another uneventful commute.",
"Your brain works in a hierarchical way, where visual stimulus is processed by the lower level, patterns are formed, and compared against expectations. For instance, if you see nothing but the dotted line and trees moving, those are all predictable stimuli that can be handled by the lower levels. But if something a bit unexpected happens (like a lane merge or a turn), it forms its own patterns and gets processed by a bit of a higher level. If you've seen a million lane merges, then you can still process this without it running too high up the hierarchy. \n\nIf you saw something completely unexpected at all levels, like a car coming toward you on the highway, it wouldn't be expected at any level, so no level would be able to handle it, and you would have to get consciously involved - this is when you're snapped to attention.\n\nThink of your brain like a big company, and your consciousness is the CEO. When everything's running smoothly, the cashiers and stockers can handle everything without any issue. If an issue arises, a manager or branch manager might have to get involved. But when something happens that no level of authority can handle, it gets escalated and escalated until the CEO has to get involved. \n\n",
"Consciousness it's a trick of memory. You are skilled enough in it that you don't require memory processing anymore, so you are effectively unconscious during the trip. We do not need consciousness for most activities we do.. It's just a trick our mind plays on us.",
"Your subconscious does 99% of everything for you once you've learned how to do it.",
"Ok, going to post something scary but it seemed this was the most appropriate place for it.\n\nI drive a lot. I'm not a truck driver, OTR or anything like that, but I travel for my work. Different states, different countries. I have driven on both the left and right sides of the road (where appropriate) equally well.\n\nI do the 'black-out' thing quite frequently. Long trips, or slowly sorting through traffic, etc. I drive well, I drive safely, I anticipate other drivers and have avoided numerous potential accidents due to other drivers. I have led coworkers and other drivers who can attest to my safe driving.\n\nHowever, I frequently do not remember my trips...at all. I frequently find myself at the end of a long drive, tucked into a parking space, or somewhere safe, as if I intentionally parked there. But yet I have no recollection of any of it. I may have driven past my exit, my street, or my house...or sometimes taken an earlier exit and 'camped out' somewhere. Only to wake a few hours later wondering what happened.\n\nThis seems a little more than just \"highway hypnosis\" and not just blind luck. So is there a deeper level to this RAS or what?",
"I deliver pizza but I don't go into zone out stage when working probably because it's always a different road. When driving to school and work I'm always zoning out but driving fine was actually going to post an ELI5 like this other day. So thanks OP aha",
"The autopilot feeling does not come from \"not being aware\" that you are driving. In fact you are perfectly capable driver. The difference is that your brain will not register the trip in the memory. You still see all the things that happen and can react to them - it's just that it's the same stuff again and again. Your brain does not need to encode it. ",
"I often do this, but I assume that if there was something out of the ordinary, something that caught my conscious attention, I would remember it.\n ",
"Imagine spending all your time focused on every activity you do through out the day. You would have no time to yourself and your brain would be exhausted. We naively feel like we genuinely put all of our brain power into all of our thoughts or actions when the reality is much different. Our brains prefer to be spending time thinking about other things than the action we're doing day in and day out, driving is no different.\n\nThe reason it seems so weird is a combination of two things, one is the idea that we think we have this ever present control over our thoughts and we like to we think about everything we do in detail. We don't, not in detail at least. The other is that fucking up while driving has some potentially shitty ramifications, so we value the action of driving safely and catching ourself not thinking about driving seems scary. When you realize you have probably auto-piloted to most of the places familiar to you, you begin to no longer associate day dreaming with bad driving.",
"OK I know the actual answer:\n\nThe brain, being an electro-chemical organ operates at different frequencies that induce certain states of mind. Alpha, Beta, Theta, Delta (and maybe a new one called Gamma). \n\nThese different brainwaves are responsible for different the types of consciousness that we encounter. Beta is the most common state, normal waking consciousness, where you brain is encountering something stimulating. Alpha is that point when you just begin to let go and zone out. Delta is when you are in a deep sleep and is the slowest frequency. \n\nAnd then there is Theta: \n\n > This frequency range is normally between 5 and 8 cycles a second. A person who has taken time off from a task and begins to daydream is often in a theta brainwave state. A person who is driving on a freeway, and discovers that they can't recall the last five miles, is often in a theta state--induced by the process of freeway driving. The repetitious nature of that form of driving compared to a country road would differentiate a theta state and a beta state in order to perform the driving task safely.\n\n > Individuals who do a lot of freeway driving often get good ideas during those periods when they are in theta. Individuals who run outdoors often are in the state of mental relaxation that is slower than alpha and when in theta, they are prone to a flow of ideas. This can also occur in the shower or tub or even while shaving or brushing your hair. It is a state where tasks become so automatic that you can mentally disengage from them. The ideation that can take place during the theta state is often free flow and occurs without censorship or guilt. It is typically a very positive mental state. \n\n_URL_0_",
"This shit actually scared me when I used to drive. I'd get to the school parking lot and all and as I open the car door I realize \"Holy shit I just spent the last half hour thinking about anime I could've died.\"",
"As someone living in LA, what is this auto-pilot mode you speak of?",
"Sometimes when I pull up into my driveway, I have to think if I ran any red lights or stop signs. The fact that a cop hasn't pulled me over means I'm good. ",
"An essential part of this function is managed by the Reticular Activating System, which is a primitive (like right near the brain stem) part of the brain that manages sleep/wake cycles and stuff. Rather than me typing how it works in detail I will provide you [this unofficial link.](_URL_0_)",
"I have no answer here. Just a fellow redditor who experiences this and it scares the shit out of me. For me, I can feel when I'm about to go into this \"zoning out\" mode. Its not like sleep, or hurt or any thing, its this feeling I can't describe. Whenever I feel this, I pull over and slap the shit out of myself. Other drivers don't deserve my zoned out driving.",
"No idea. I just wish I knew why I keep finding blood stains on my car after I go for a drive. ",
"Is it unhealthy that I am like this a lot of the time at all? I feel this way at the end of most days. It worries me. ",
"I don't understand the people that get so sanctimonious over posts like this. Everyone knows and can relate to what the OP is talking about. Why people feel the need to get all \"well if you're driving without counting all possible dangers, you're an irresponsible idiot\"...I don't understand. I appreciate some people have experienced an accident at the hands of ACTUAL reckless driving, but that's not what we're talking about. The pedantic opportunist levels are too damn high sometimes. ",
"There is this book called - The Origin of Consciousness in the Breakdown of the Bicamaral Brain. It's an interesting book. He talks about what you bring up. I think his argument is that mostly we *aren't* conscious when doing stuff like driving, or much of our daily life.\n\nHe takes this idea and goes off on it. Like I said, interesting book. Have no idea how accurate it is scientifically..",
"When you were a toddler you had to THINK about placing each step. Then you learned to navigate without thinking. If a cat ran out in front if you you tripped. Now that you're more practiced at walking you can chew gun and think about other things at the same time as walking AND if a cat walks out WHILE you're chewing gumwalking you navigate without harming kitty or yourself or others.\nSame as driving.",
"While the real answer is from /u/tellcastr101, I just wanted to say that good driving habits (being a good driver in general) is also a factor here. If you were a crappy driver that didn't pay attention to the road when not 'zoning out', you'd probably be in an accident by now. ",
"It's called complacency. You get so used to driving the same road every day, you start relaxing and not worrying about it and allow your brain to wander. It's so routine, you don't feel like you have to really focus on it. And it's not you doing it, but the brain is designed to automate repetitive behavior, so it happens without you even realizing. "
]
} | [] | [] | [
[],
[
"http://cogsci.stackexchange.com/questions/544/running-on-autopilot"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"http://www.scientificamerican.com/article/what-is-the-function-of-t-1997-12-22/"
],
[],
[],
[],
[
"http://www.drnowell.com/blog/2013/01/27/Q-Whats-the-role-of-the-Reticular-Activating-System-RAS-in-attention-and-focus.aspx"
],
[],
[],
[],
[],
[],
[],
[],
[]
] |
|
6hnp9r | why isn't herbalife illegal company | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6hnp9r/eli5_why_isnt_herbalife_illegal_company/ | {
"a_id": [
"dizozk8"
],
"score": [
6
],
"text": [
"Because it actually offers real products for sale whereas, pyramid schemes do not according to the US FTC (Federal Trade Commission). Therefore, it is categorized in the MLM (multi-level marketing) organizational category, which is a legal business and not a pyramid which is illegal.\n\nAlso, MLMs make money by enrolling people into their organization + selling products to those people rather than a pyramid which just makes money from enrolling people (no product to sell).\n\nThe fact that MLMs are legal though baffles me as they just take advantage of lesser people by selling them false hopes and setting them up to fail and burn bridges in their personal lives.\n\n\n"
]
} | [] | [] | [
[]
] |
||
59fyyi | How does the temperature of colder planets core relate to warmer planets core closer to closer to the sun? | askscience | https://www.reddit.com/r/askscience/comments/59fyyi/how_does_the_temperature_of_colder_planets_core/ | {
"a_id": [
"d98nx89",
"d9a00ah",
"d9bjdub"
],
"score": [
5,
2,
2
],
"text": [
"The temperature of the core of a planet will depend on several factors: leftover heat from formation of the planet, heat generated through mechanisms like friction and radioactive decay, mass of the planet, ratio of mass to surface area, etc.\n\nSo I don't fully understand what you're trying to ask, but mercury is small and has relatively little geological activity. Any heat from formation would have already been dissipated. It's estimated core temp is only around 4000 °F.\n\nVenus, the second and hottest planet, should have a much warmer core, around 10,000 °F.\n\nJupiter, the largest planet, probably has the hottest core. It emits more heat than it absorbs from the sun, and it's core temp is estimated around 50,000 °F.\n\nI don't know if that answers your question, but hopefully it illustrates that distance from the sun is not the primary factor that determines the core temperature.",
"The proximitty of the sun is not important for the core temperature. \nThe importance is the left over heat from the formation, a little bit of radioactive decay and very importantly tidal heating. The moon for example does not only affect the tides on the surface but also the earths core. This gives heates up the Earth due to friction induced by this tidal force. The same goes for other planets with moons as well. \nAll the gas and ice giants they have some internal heat source as well. This could be the continued separation of Helium and Hydrogen. ",
"First of all would point out that the outer planets are not necessarily cool and that many processes come into play resulting in no particular relationship between a planet's distance from the sun and it's core temperature. Having said this, a large factor of a planets temperature is the residual heat from formation, which is linked to distance from the sun. This heat is a result of accretional heating; potential energy of matter converts into kinetic energy as it 'falls' into the planet during formation. \n\nIn the protoplanetary nebula, before planetary formation, the solar wind erodes the inner gas cloud near to the sun. This means that inner planets are rocky and small, due to this absence of gas when they are formed, and gas giants are found farther away from the sun where the nebula wasn't blown away. \n\nThis means that inner planets tend to have less heating due to accretion as they are smaller with less matter. For example Mars has radiated it's primordial heat. Outer planets on the other hand have huge amount of primordial heat. In addition the large gas giants have a lower surface are to volume ratio, so will radiate their heat slower."
]
} | [] | [] | [
[],
[],
[]
] |
||
3jqfjx | the difference between the german chancellor and the president of germany | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3jqfjx/eli5_the_difference_between_the_german_chancellor/ | {
"a_id": [
"curfd1l"
],
"score": [
24
],
"text": [
"The President is the head of state; the chancellor is the head of the government. The head of state refers to a largely ceremonial role -- that's the person who meets other countries' diplomats and royalty, attends non-policy-related diplomatic events, and ceremonially enacts laws by signing them (without the power to veto). The head of the government is the chancellor. They have real power to enact policy, propose laws, and control the bureaucracy and administrative state.\n\nIn the US, these are unified (the President does both roles), but most countries have separated them. In England the Queen is the head of state while the Prime Minister is the head of the government; same in Japan. In Russia they have a President and a Prime Minister, with the President as head of state."
]
} | [] | [] | [
[]
] |
||
d7nap7 | why can't we live just off of sunlight energy? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/d7nap7/eli5_why_cant_we_live_just_off_of_sunlight_energy/ | {
"a_id": [
"f12g652",
"f12rptg"
],
"score": [
13,
2
],
"text": [
"Biologically? Even plants can't live off sunlight alone, and they sit around all day. They still need essential nutrients and water from the soil, despite the fact that they don't move.\n\nCold-blooded animals (like reptiles) move little and do get some energy from UV light. That's why you might see lizards sitting under a big blue lightbulb in pet stores. However they still need extra sustenance to thrive and grow.\n\nWarm-blooded animals like us humans use a lot of energy. We're constantly heating our bodies, and we move around all the time. We simply need more energy than can be collected from sunlight alone.",
"ELI5: Your body needs food, and sunlight isn’t food. Sunlight just gives plants a little help making their own food, and then we eat those things as our own food. \n\nELI’mInCollege: (Also, if someone ends up reading this that knows more about this subject than I do, please correct me). My understanding of why we can’t do it comes down to the cellular level, and the production of a substance called Adenosine Triphophsate, or ATP for short. \n\nIn very simple terms that is glossing over a LOT of other steps, your body runs on ATP, and that’s where your “energy” really comes from. Each cell produces ATP, but you have an astoundingly small amount of it in your body at any given moment - I think something like half a gram - that is also used nearly as quickly as you produce it. The average human will actually go through close to 80 lbs of it per day, but most of that weight is actually cycled in and out of your body through cellular respiration. Without ATP, you die very quickly, which is why poisons like cyanide kill you within seconds; it stops ATP production (or something). \n\nThe cellular respiration is where your question comes into play. In a normal situation, your body needs (all sorts of stuff really) to function properly, but without Carbon, Hydrogen, and Oxygen, or carbohydrates, your body can’t produce ATP. And then you die. And while sunlight is essentially the purest form of energy we can access, we can’t actually live without other stuff. \n\nIt’s a really big, really complex subject that absolutely rocks your world the more you learn about just how precarious and precise life really is."
]
} | [] | [] | [
[],
[]
] |
||
4e1eow | What are the factors affecting pressure in a pipe? | I want to investigate how the following factors can affect EITHER volumetric flow rate OR pressure OR K.E. energy loss.
My aim is to choose one of the combinations which will allow me to gather a lot of data, and thus analyse using Bernoulli's principle, Hagen–Poiseuille equation?
- Angle of bend
- Shape of outlet pipe
- Length of outlet pipe
- Number of holes (streamlining).
I need to determine how one factor can affect either volume flow rate OR pressure OR energy loss OR any other combination of the three.
___________________________________
The current combination I am considering is how the ANGLE in a pipe bend affects the PRESSURE.
Here's a pic of my experiment.
_URL_0_
Controls:
Pipe diameter
Relative height (Bernoulli's equation)
Velocity (Bernoulli's equation)
Possible problems with current setup:
- Difficulty to install the pressure gauges -still need clarification on how it will measure the pressure and possible interference with pipe flow.
- Could you let me know on other set-up suggestions?
Arising questions for investigation:
- What factors cause this pressure loss: friction? - > possible area of investigation
Thanks in advance!
| askscience | https://www.reddit.com/r/askscience/comments/4e1eow/what_are_the_factors_affecting_pressure_in_a_pipe/ | {
"a_id": [
"d1wf27q"
],
"score": [
3
],
"text": [
"So is this like a high school (college) project? \n\nFlow rate you can easily measure using a bucket and a stop watch; just wait a certain amount of time (60 seconds or whatever), then weigh the water that you've collected (or determine its volume).\n\nPressure, the two gauges will probably be fine. Maybe you could put them onto the straight piece of pipe so that you could try the experiment with different elbow pieces (45 degree, 90 degree, 180 degree). \n\n_URL_2_\n\n_URL_0_\n\n_URL_3_\n\n_URL_1_\n\n\n\n"
]
} | [] | [
"https://drive.google.com/file/d/0B55SLbVVgR4XNXJ5YnN4bEpoOG8/view?usp=sharing"
] | [
[
"https://neutrium.net/fluid_flow/pressure-loss-in-pipe/",
"https://en.wikipedia.org/wiki/Hydraulic_analogy",
"http://www.mycheme.com/calculating-pressure-drops-in-pipe-fittings/",
"https://neutrium.net/fluid_flow/pressure-loss-from-fittings-equivalent-length-method/"
]
] |
|
f2bhbh | the way i understand aging, is that cells make a slightly less perfect copy of its predecessor each time until its eventually “no good” and we just fall apart and die, if we could find a way to make cells reproduce or clone perfectly, would we be able to live forever? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/f2bhbh/eli5_the_way_i_understand_aging_is_that_cells/ | {
"a_id": [
"fhbgp44"
],
"score": [
2
],
"text": [
"That's just part of it. Aging is a complicated process with several factors at play. The ends of each chromsome, called telomeres, gets degraded progressively each time the cell divides. Eventually the degradation gets to the actual sequence you care about and the cell is no longer viable. This is a very basic biological clock for the life of a cell. But aging affects the whole organism. Cells get damaged due to all sorts of reasons, like UV from sunlight and oxidative stress from metabolism alone. And when damaged a cell often commits suicide. We don't have an infinite reservoir of cells, some specialized cells have only a limited number of stem cells. And when the we run out, renewal runs out. Besides that, you have many many processes that affect us gradually at the big picture level. Like nephrons (filtering units in the kidney) get less and less over a life time. These are relatively big structures made of many many cells so if they're gone they're really gone. Then you have things like atherosclerosis, plaques accumulating in your vessels, hardening them and narrowing them. You get strokes and ischemia and die from heart or brain issues. Or you may get proteins aggregating just due to random chance of misfolding, this happens in the brain and almost everywhere else. And we're horribly bad at dealing with aggregates so they end up killing cells and you eventually. Then you got random mutations that are bound to once hit critical genes that then cause cancer. I barely even scratched the surface here, fixing a cell by allowing it to renew its telomeres has been investigated before. But the risk of cancer is too high. And even if it wasn't, we got a million other things that are bound to go south over a lifetime. We're simply not built to forever, if you want to be immortal you have to change your body altogether."
]
} | [] | [] | [
[]
] |
||
69emit | What impact does a tsunami have on ships at sea? | Hello r/askscience.
How much would a big ocean-going vessel (say, a US navy Nimitz-class aircraft carrier) notice a tsunami in the middle of an open ocean, thousands of miles from shore?
Would it be a destructive wall of water moving rapidly towards the ship, or would merely be a (un)noticable rise of the water level which a ship could pass over?
Assume the tsunami in question is the result of an earthquake with a rating of 9.0+ on the richter scale similar to the 1700 Cascadia or 2004 Indonesia earthquakes, both of which generated massive, ocean-crossing waves.
| askscience | https://www.reddit.com/r/askscience/comments/69emit/what_impact_does_a_tsunami_have_on_ships_at_sea/ | {
"a_id": [
"dh5ysl5",
"dh5z4vb",
"dh62ong",
"dh631ez",
"dh6aeq9",
"dh6dr9x",
"dh6h956",
"dh6k3ec",
"dh6llmj",
"dh6m33r",
"dh6pl6h",
"dh6q4vm",
"dh6sum9",
"dh6to3f",
"dh6v0el",
"dh74dmj",
"dh75jvo",
"dh75qvm",
"dh772n6"
],
"score": [
4227,
443,
203,
39,
174,
216,
14,
8,
4,
3,
23,
13,
5,
4,
5,
2,
2,
9,
22
],
"text": [
"they wouldnt even notice it (they'd notice it, but not as a threat). \n\na tsunami does not really \"present\" itself as a wave until the water depth is about < 1.3x the height of the wave itself. the drag on the bottom of the ocean slows the flow and the top moves ahead and creates the circulation we see.\n\nWhen you look at a regular ocean, it looks pretty calm, but when it gets to shore, things become more violent.",
"They would see a sea swell of about a meter over several minutes fowled by a dip. Note that this is very much a slow swell. A carrier wouldn't actively notice any change. A smaller class ship such as an Arleigh Burke class destroyer would hardly notice such a change depending on the sea state. Maybe if the water was glass, but most of the time it's too choppy for such a thing. \nSource: Was mariner in SOPAC during march of 2011. \n\n Further reading: check out rogue waves. I don't know much about those, but they would probably interest you. ",
"As some other comments have said, it depends on the ship's location relative to both the coast and the depth of the ocean beneath it. Far out to sea and you wouldn't really notice, but if the ship is close to the harbor, depending on the size of the quake and the degree of uplift generated, you'd absolutely notice.\n\nFor reference, [here's a video from a Japanese Coast Guard vessel recording the Tohoku Tsunami approaching shore](_URL_0_).",
"Tsunamis have speed and amplitude. Assuming the energy of the wave stays constant, a drop in speed results in an increase of amplitude, or wave height. Tsunami speed = sqrt(gravity x water depth). So as you get to shallower waters, the speed of the tsunami will decrease, leading to the height of the wave increasing. In deep waters, the speed of the wave could be as high as 700km/h with a height of less than a meter, but can reach ~~hundreds~~ tens of meters in height when that speed is transferred into height.\n\nreference: _URL_0_\n\nedit: It would be entirely dependent on the depth of the sea at the location of the boat. Deeper than 300m depth, you probably wouldn't notice it. 50m depth, you'd get jostled around. 10m depth, good luck.",
"When the tsunami hit Japan a while ago a buddy of mine was out at sea doing research in the area. When he got back he told me about how there were these 2 massive swells of water that hit them but they didn't really think much of it until they got back to shore later that day and saw the mass destruction that the tsunami had caused. ",
"One way to think about it is that a typical wave in the ocean is generated by wind and only effects the top few meters. That can move along with the water underneath undisturbed until it hits land. Once the depth on shore is less than the wave it builds up and breaks (oversimplified here but stay with me).\n\nA tsunami involves the bottom shifting so you get the entire depth of the ocean to shift up say one meter. \n\nBig deal, a one meter wave in the mid ocean. The problem is that this wave will not stay put and now will travel at hundreds of kms per hour. Also it is not really a wave but a whole block of water from the surface to the bottom (say 2500 m) that was moved. \n\nAt smaller depths, this becomes a problem as the water wants to be 2500 m deep. All the displacement energy of the water at full depth must be absorbed so we end up with a much higher, wider wave in shallow water. ",
"I was on a WWII aircraft carrier (US) and felt significant wave action on the outskirts of a hurricane. Of course, it all depends on the position of the ship to the angle of the wave. I know Poseidon Adventure (1970s) movie was science fiction, but most ships probably will capsize if the wave hits the ship 🚢 broadside, depending on the size of both. If the ship hits the wave head on, depending on what part of the wave hits the ship, then the ship could tear apart, sink, or again, capsize. A liquid can almost be considered a moving, amorphous solid that cannot be compressed and if the wave hits fast enough, it will feel like a brick wall! ",
"Tsunamis aren't rogue waves out at sea, it's only what they approach shorelines that they grow to be vertical monsters, because that hold a great deal of energy but the energy is condensed as the depth becomes shallow.",
"In the middle of the ocean, they would barely notice it. You hit bigger swells in storms. Now, if you were in port, the water level would drop and potentially beach the ship. I know the carrier that was in Yokosuka during the 3/11 tsunami experience an immediate drop in water level by several feet and came close to dragging the ground. Had they not been protected by the bulk of the tsunami by the Chiba peninsula, they would have likely fared much worse. ",
"I heartily recommend the movie, The Wave, that is currently on Canadian Netflix. (Don't know if elsewhere). While your question states \"at sea\" I think that a tsunami caused by a rock slide would cause waves that are much less easily navigated by boats because of their intensity. There is also a great description of survivors of the Alaskan tsunami caused by landslide here _URL_0_",
"_URL_0_\n\nHere is the 2011 Japanese tsunami passing under a coastguard ship. I thin k it must have been pretty close to shore for the wave to have been that prominent. Further out from the shore they probably would never have noticed the tsunami at all. ",
"Everyone who is saying that the ship would not notice it is wrong. There might be situations where a ship does not notice anything, but there are times they do. \n\nThis is a Japanese ship hitting the tsunami a couple years back:\n\n_URL_0_\n\nThere is a very clear wall of water that was obvious enough that they started filming. ",
"In the original novel for the Poseidon Adventure. The author describe an undersea earthquake that caused a large amount of water to be displaced underneath a cruise liner. And that the ship simply fell into a giant void where water had been. I wonder how that would look like.",
"It depends on where you are. I have a close family friend who was a US Navy ship Captain in WWII. Near the end of the war his ship went over a tidal wave. He said it was no more than a minor swell due to the fact they were way out at sea.",
"At sea the tsunami is a dark line about 40 meters wide racing along at 800 km/hr, does not show on radar. Think of it as a ripple in a bullwhip until it goes into shallow water and slows down and the energy becomes waves.",
"While everyone is basically correct regarding the height of a wave in deep ocean it's also worth noting a seaworthy vessel won't capsize because of any nonbreaking wave. A kodiak going up against the physically largest nonbreaking wave will stay afloat. \n\nOnce you get into the shoals or high windspeeds generate whitecaps all bets are off. ",
"The further from shore they are (or rather, the deeper the water is, and not linearly, a complex fluid-dynamic relationship between these two factors for which \"distance from shore\" is a pretty effective heuristic), the less of a deal it is. The bigger the vessel is, the less of a deal it is (in this case, not even a heuristic, but a direct, almost-linear relationship). These are pretty direct, mathematically sound relationships. From them it is easy to infer that a Nimitz class aircraft carrier would barely register a tsunami thousands or even hundreds of miles from shore.",
"Tsunami literally translates to harbor wave. This came from fisherman who would return from an otherwise uneventful day at sea to find their town completely destroyed. Hence the idea that the wave was confined to the harbor. Obviously we know better now, but this gives you an idea of how relatively imperceptible tsunamis are while you're in the open ocean.\n\nIf you have time there is an interesting documentary about the Indian Ocean tsunami a few years ago that includes stories from people who were diving that day. They thought the currents were really strong but had no idea the reason until they returned to their resort towns to find them flattened. I can find the name if someone is interested, but I'm currently on mobile.",
"Wave seismologist here. Tsunami waves in the middle of the ocean would be detectable, however, they will not endanger any boats because they have no pitch to them. Only once they begin approaching a shoreline will they begin to pitch upwards and create a face wall. This is caused by the shallowing of the ocean bottom. The kinetic energy built up by the approaching tsunami has only 3 directions to go. Forwards, to the sides and upwards. \n\nA tsunami is caused by a massive underwater earthquake and only when the ocean floor is violently and abruptly pushed upwards. The amount of ocean floor upheaval translates directly to the force behind the tsunami. It's not the vertical height of a tsunami that causes the damage but the amount of force behind the mass of water. It's the difference between getting punched by your little sister versus Mike Tyson."
]
} | [] | [] | [
[],
[],
[
"https://www.youtube.com/watch?v=OdhfV-8dbCE"
],
[
"https://nhmu.utah.edu/sites/default/files/attachments/All%20About%20Tsunamis.pdf"
],
[],
[],
[],
[],
[],
[
"http://www.sitnews.us/Kiffer/LituyaBay/070808_lituya_bay.html"
],
[
"https://www.youtube.com/watch?v=-VcWF8dIDj4"
],
[
"https://www.youtube.com/watch?v=OdhfV-8dbCE"
],
[],
[],
[],
[],
[],
[],
[]
] |
|
ch7r9y | is there a radio frequency camera? | I just wondered if you could built a cameralike device to view radio frequency emmiting objects. Lets say in the 2,4 GHz range like wifi antennas.
I mean you could take a directional antenna and scan across the view like a radar. Or maybe use a grid of antennas and interference like Radiotelescopes do. But is there a way to focus RF and detect it with some kind of detector which works more like a photoresistor.
So you would need a RF lens and a RF detector. Does something like this exist? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ch7r9y/eli5_is_there_a_radio_frequency_camera/ | {
"a_id": [
"euq7ouz",
"euqmel2"
],
"score": [
5,
5
],
"text": [
"Yes, a radiotelescope is such a device.",
"Yes, but the resolution is limited by the wavelength. Radio telescopes use multiple dishes and interferometry for increasing resolution, but they need to scan just like single dish telescopes. \n\n[Micro bolometer focal plane arrays](_URL_0_) are becoming used for radio astronomy, but are limited to short wavelengths. Other multi-sensors like the 21cm Multibeam Receiver at Parkes have only 13 sensors which are the equivalent of pixels."
]
} | [] | [] | [
[],
[
"https://en.wikipedia.org/wiki/Focal-plane_array_(radio_astronomy\\)"
]
] |
|
8tlxuy | Can microbes ever become UV Resistant? Why or why not? | askscience | https://www.reddit.com/r/askscience/comments/8tlxuy/can_microbes_ever_become_uv_resistant_why_or_why/ | {
"a_id": [
"e1akcxh"
],
"score": [
3
],
"text": [
"It’s very possible over time the microbes in question will evolve to be more UV-resilient by upregulating enzymes associated with repairing UV-induced damage (for example, base excision repair). But there’s a limit to even the most efficient repair mechanisms. UV intensity will eventually overwhelm the defenses. So, at least imo, no. More resilient but never entirely resistant. "
]
} | [] | [] | [
[]
] |
||
6sm2a8 | why college football schools needs that large stadiums (90k+ attendance)? | Univeristies plays about 6-8 home games at home during football seasons. Some of the stadiums hosts football games from high schools or bowl ganes - but the other big ones? For 8-9 months - that large stadiums generate costs. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6sm2a8/eli5_why_college_football_schools_needs_that/ | {
"a_id": [
"dldqzfo",
"dldr132",
"dldr2xe",
"dlds1md",
"dldtgmi"
],
"score": [
5,
2,
2,
6,
9
],
"text": [
"Because each of those games brings in a ridiculous amount of money, and there aren't very many costs associated with the stadiums when they're not in use. They're mostly outdoors, so electricity usage is pretty low, and it's not like they have to pay the staff year-round.",
"Those large stadiums also generate tons of money... they build 90k seat stadiums because they can fill them up with fans paying money for tickets, buying nachos and soda inside, etc. And often the stadiums are paid for, or substantially paid for, by donations from alumni, etc.",
"It's a cultural event and an instinctual human need. The school, the football team, and the fans are all willing to pay for the stadium to sit there during the empty months because of how big an event it is. People want to be around each other, and 90+ thousand fans want to be there for the games.\n\nThere are even more extravagant examples: the Texas Formula 1 track was built for a single, once-a-year event (though it hosts smaller events when it can). There's also the Olympics where countries spend enormous amounts of money to build stadiums that will only get used once at their max capacity.",
"For a major university with a 90k+ stadium they sell tickets for 100+ a seat. Increasing your size from 60k to 90k can increase your ticket revenue by 18 million a year, maybe even more, despite the fact that a 60k stadium and a 90k stadium sit on a piece of land that's roughly the same size. If your school is capable of filling a 90k stadium they'd be fools not to have one.",
"The supply (90,000+ capacity stadia) exists because the demand exists. Some universities lose money on their football programs, but the big name ones--Alabama, Florida, Southern Cal, Ohio State, Michigan, LSU, Georgia, Texas, Oklahoma--make tons of money. Tickets sell out years in advance, for $100 per ticket in some cases. They also make tons on media deals. Most D1 colleges also have huge student bodies--30,000 or more--which means they need to give a big section to the students at a discounted rate. So they need an extra 60,000 seats to sell to alumni and the general public to make their money. \n\nYour average college football stadium is pretty old, too. The stadium at my alma mater was built in the 1920s and has been expanded since then. They're nowhere near as nice as what you'd find for an NFL or MLB team, pretty much just concrete, stairs, and some walkways with concession stands. They're almost all outdoors--I can't think of a major blueblood or semi-blueblood team that has an indoors one, in fact. So upkeep is loads cheaper than an indoor one with HVAC systems and all that jazz. "
]
} | [] | [] | [
[],
[],
[],
[],
[]
] |
|
8e4cfj | why do sound deviations from “normal sounds” like those used in horror movies and games cause a fear response in us? | Thinking of A Quiet Place and Doki Doki Literature Club; not just predator noises and such | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8e4cfj/eli5_why_do_sound_deviations_from_normal_sounds/ | {
"a_id": [
"dxs98rw",
"dxsea5n",
"dxskj8e",
"dxsleaf",
"dxsz34n",
"dxt512l"
],
"score": [
22,
7,
2,
65,
4,
2
],
"text": [
"Do you notice how they’re always minor?",
"I think i read an evolutional theory about this a long time ago. Something about sounds outside of normal background noise, especially high pitched ones, indicating a nearby predator. Sound from the predator itself or from other prey animals fleeing.",
"I watched a program on TV that said before scary scenes they use a sound below human hearing range. You can't hear it but it causes a feeling of dread for people listening to it.",
"Another factor not mentioned in the comments is that some music is different and dissonant on purpose, not fitting into the rhythm or the harmony of the normal music, making you feel a sense of unease. They feel different and wrong, like it doesn't belong there. This appears in classical music as well, but it's usually used as a passage, with complementary notes played straight after. Meanwhile, using such notes gets you ready for complementary notes that are not going to come, if that makes any sense. It's the heart and soul of horror: suspense. It the same as when in a horror movie a protag explores a dark and creepy place and you expect a jumpscare and never get one, anticipating it more and more.",
"Humans love patterns. When the Sayo-Nara scene happens, your mind is primed for the pattern of the song that's been playing for hours up to that point. But instead, the song breaks the \"rules\" for nice-sounding music that just about every song follows, such as sticking to a key, keeping a consistent timing, and playing in tune. This creates an unsettling effect. ",
"How bout those creepy clicking noises and sound effects used in Sinister, huh? I thought whoever developed the sound effects/soundtrack in those movies did a great job (with creeping people out)"
]
} | [] | [] | [
[],
[],
[],
[],
[],
[]
] |
|
6shlmz | the psychological reason people can still not believe an argument when presented with evidence. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6shlmz/eli5_the_psychological_reason_people_can_still/ | {
"a_id": [
"dld8y9b",
"dlddrki"
],
"score": [
2,
3
],
"text": [
"It's because one person's irrefutable evidence, is total bullshit to someone else. Evidence is subjective. When you say something is a fact, how often is it that you do not really know that for a fact. You are relying on \"studies\", \"statistics\", lots of things you don't really know to be true yourself, but have accepted as \"the truth\". \n\nWell if you get into an argument with someone that does not accept the word of all of those people, or their electron microscopes that allegedly show what things look like at very small scales, or other things you consider scientific fact, than they are going to be unmoved by your argument, as you are unmoved by the things they believe the truth to be. \n\nIn short, there is no universal truth.",
"It's because they believe in something else more than the validity of the argument. The argument might have flaws, after all. \n\nLet's say you think wine causes lung cancer and they think cigarettes do. If they are 99.99% sure that cigarettes cause cancer and your argument that it's caused by wine has only a 95% chance of being valid, they should rightfully (given their beliefs) ignore it. And in this case, they ARE right!\n\nSince people can have irrational beliefs that they are near-certain of, no amount of argument can change those beliefs - they always think it's more likely that the argument is wrong rather than their belief."
]
} | [] | [] | [
[],
[]
] |
||
7op85x | why is seafood much more fragrant/smelly than land based animals? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7op85x/eli5_why_is_seafood_much_more_fragrantsmelly_than/ | {
"a_id": [
"dsb9k4m"
],
"score": [
6
],
"text": [
"Trimethylamine oxide. It's odorless, but after you kill the fish bacteria break it down into ammonia. "
]
} | [] | [] | [
[]
] |
||
3gc1u6 | why does faraway smoke look like it's staying still? | For example, the steam coming out of cooling towers always looks static, as does smoke from a fire that you aren't close to. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3gc1u6/eli5_why_does_faraway_smoke_look_like_its_staying/ | {
"a_id": [
"ctwqld2",
"ctwqmyb"
],
"score": [
2,
2
],
"text": [
"The same reason airplanes look very slow. A plane flying 400 mph looks like its crawling along because its so far away. Smoke rising a mile away is only going, I dunno, ten miles per hour, so it looks completely still because of the same principle.",
"It's a phenomena named parallax, u might google it to find visual examples along with explanations (far more effective than a simple explanation)"
]
} | [] | [] | [
[],
[]
] |
|
1s2e95 | What are the earliest accounts of 'roleplaying'? I assume children always played pretend but what did adults have any kind of pseudo-D & D in the past? When did these hobbies start to become 'a thing', basically? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1s2e95/what_are_the_earliest_accounts_of_roleplaying_i/ | {
"a_id": [
"cdtb59e",
"cdticjb"
],
"score": [
23,
10
],
"text": [
"Having asked my colleagues at #Twitterstorians, they suggested the following piece, which should answer your question.\n\n_URL_0_",
"War reenactment was an early sort of 'roleplaying', where people dress in the uniforms of armies and reenact battles\n\nThere was a reenactment of the battle of Gettysburg at the \"Great Reunion\" in 1913.\n\nSource: _URL_0_\n\nIn England, the \"Sealed Knot Society\" was created in 1968 to reenact battles from the English Civil War.\n\nSource: _URL_1_\n\nMilitary reenactment as a form of \"roleplaying\" probably predates roleplaying games. \n\nOf course, participating in stage plays with an historical setting is a form of 'roleplaying' which probably predates all others."
]
} | [] | [] | [
[
"http://www.robmacdougall.org/blog/2007/05/dungeon-master-zero/"
],
[
"http://en.wikipedia.org/wiki/American_Civil_War_reenactment",
"http://en.wikipedia.org/wiki/The_Sealed_Knot_(reenactment)"
]
] |
||
6ode2m | how do it departments handle frequent cyber attacks? | Context: the director of my organization's IT department mentioned in a presentation that we encounter hundreds of cyber attacks every week (this organization is well-known globally). How is it possible that we are attacked so frequently and how do the IT folks handle it? I know nothing about CS. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6ode2m/eli5_how_do_it_departments_handle_frequent_cyber/ | {
"a_id": [
"dkgk8ag"
],
"score": [
6
],
"text": [
"Almost any publically accessible IP address is constantly bombarded by various attacks and scans. At home your router most likely protects you from a direct assault on your home computers by forbidding direct connections unless you've explicitly set up your router to allow it. \n\nSame is true in the corporate world. Depending on your organization's IT department, budget and policies they may have one more of the following\n\n* Firewalling routers that block desirable internet traffic.\n\n* Application level proxies, that check internet traffic, inspect it for undesirable content and relay it on to the actual application. \n\n* regular updating of software and applications and virus scanning\n\n* various intrusion detection systems that monitor what applications are running on various servers, a fingerprint of various files on the servers and what type of network traffic patterns those servers typically have. \n\n* Maybe even a honey pot system which can mimic vulnerable targets that appear to be easy targets. Once an attack on a honeypot is detected, steps can be implemented to block them. \n"
]
} | [] | [] | [
[]
] |
|
3aj7el | Does special relativity apply to circular velocity? | Does there exist time dilation between the earth's equator and the earth's poles? | askscience | http://www.reddit.com/r/askscience/comments/3aj7el/does_special_relativity_apply_to_circular_velocity/ | {
"a_id": [
"csdceoy",
"csddno5"
],
"score": [
6,
2
],
"text": [
"I misread your question, there is not a time dilation effect between the Earth's pole and equator. While pure circular motion should induce such dilation, the special relativistic and general relativistic contributions cancel out because the Earth buldges from centrifugal effects. Here's a more detailed overview I found from searching around: \n_URL_0_\n\n-------\n\nBelow is a discussion between the differences of say circular motion in special relativity and circular motion from gravity:\n\nYes. The math is more complicated as there is an acceleration involved. Now since we're considering orbital motion due to gravity, there is general relativistic effects as well which come with even more complicated math.\n\nSo even in situations without significant gravity, like a clock in a centrifuge, special relativity will affect clocks and distances. Most famously we have Ehrenfest paradox which shows that spinning objects cannot be rigid: \n_URL_1_",
"Yes. But you have to be more careful with the interpretation and allow for curved spacetime. \n\nImagine you are flying along the circumference of a circle with radius r. If you are slow, you will measure a circumference of 2pi * r per round. If you are fast, Lorentz contraction will kick in and you will measure a circumference of less than 2pi * r - or even zero 0, if you are a photon. But the distance to the center is perpendicular to your movement at any time, so it will be unchanged and still look like r to you. The only way to reconcile these two observations is to conclude that spacetime is curved (in your reference frame).\n\nNote: This is not full general relativity yet, since this curvature is not 'real', and it can be transformed away into a perfectly flat spacetime if you choose the center of the circle as reference frame. When there is a gravity field, there is also a 'true' curvature, in the sense that spacetime looks distorted regardless of the reference frame. \n\nAnd yes, time runs different on the equator versus the poles. First, because of the different velocity and second gravity is weaker. A related experiment was [done](_URL_0_) in the 70s. Two planes were sent around the earth in opposite directions and compared to a stationary ground clock. As expected all three measured a slightly different elapsed time."
]
} | [] | [] | [
[
"http://physics.stackexchange.com/a/126932",
"https://en.wikipedia.org/wiki/Ehrenfest_paradox"
],
[
"https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment"
]
] |
|
7x15fv | shouldnt we burn a lot of calories when eating ice cream because our body works to raise the temperature of the ice cream? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7x15fv/eli5_shouldnt_we_burn_a_lot_of_calories_when/ | {
"a_id": [
"du4n45n"
],
"score": [
5
],
"text": [
"We do burn calories when eating cold food - it takes energy to keep the body warm, and to counteract the effects of cold food - but it doesn't take that to heat up a few scoops of ice cream, especially compared to the calories you take in by eating it.\n\nFor one thing, ice cream really isn't that cold - a freezer is typically between -10 and -20 C, a fridge between 0 and 10 degrees. So compared to something out of the fridge, you don't net more than 30 degrees, and probably less, since it's warming up from the air. It will also largely melt in your mouth, which has a lot more exposure to the outside air, and it's not only your metabolism warming it back up.\n\nSecond, a single food calorie - kilocalories - is enough to raise 1 kg of water by 1 degree. Presumably, you're not eating a 1kg of ice cream at a time (if so, mazel), but let's say you've got a hearty serving of 100g. Each Calorie raises that by 10 degrees, and you're only going up 50 degrees or so. So, that's no more than six calories, tops: which you'd replenish with a gram and a half of sugar."
]
} | [] | [] | [
[]
] |
||
1rlfaw | the moral and ethical implications of genetically modifying people | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1rlfaw/eli5_the_moral_and_ethical_implications_of/ | {
"a_id": [
"cdoesf1",
"cdoksd9"
],
"score": [
3,
4
],
"text": [
"Glad there are some people out there who care. In my undergraduate degree in Biochemistry & Molecular Biology there was no bioethics course taught. We spent only one lecture in my course on Proteins touching on this subject. The reality is that we are not far from a day where we will be able to screen and prevent many diseases, as well as provide a unique map of every individual's genetic makeup which could be used to both identify and discriminate. Phenotypic variation (due to underlying heritable genetic variation) is a fundamental prerequisite for evolution by natural selection, so we should at least ask ourselves if it is a good idea to manipulate it like humans like to do to everything so much.",
"I could be all nerdy and shit and direct you to Gundam Seed, but that would waste too much of your time. Imagine this:\n\nYour friend James is perfect in every sense. He won the genetic lottery - Blue eyes, blond hair, 6'4, face to die for, amazingly healthy, and has a 12\" dick just to top it off. Not to mention, he has Einstein's IQ. \n\nJames becomes an astro scientist and builds spaceships with lasers, forcefields and warp drives on them before anyone else does. Also, he cures cancer. Go figure.\n\nOne day, some sleazy two bit journalist makes an amazing discovery; James was genetically modified at birth. All undesirable traits and genetics were removed so he could become the perfect human being. \n\nSuddenly, James's achievements are meaningless to the general population. He still produces amazing works and breakthroughs, but he is no longer one of us. He's something else. \n\nReligious people will try to kill him. He is not a product of God. He is Satan incarnate brought forth by evil scientists to disrespect God. \n\nAthiests will be jealous. Why weren't they lucky enough to be genetically modified at birth? Why couldn't they be born for greatness? Just living and dying. It's bullshit! Why should he get to be so great?\n\nYour average person won't entirely understand the issue, but get that genetically modifying anything is bad (Vegans), people aren't experiments (Right's activists), Male Privilege can now be sold in a test-tube (Feminism), We need more people like this to go fight our wars (Military). Whatever the reason, or what kind of person you are, everyone is unified in the same idea: This person should not exist. \n\nEveryone begins to hate James. He couldn't have done any of this if he wasn't grown in a lab. He's an adbomination. He must be destroyed! KILL HIM!\n\nYou, finally find out James is genetically modified to be great. You form your own decisions on the matter. \n\nOne things lead to another, James is killed by extremists. Everyone like James is killed. The people like James try to fight back.\n\n > In the end, no one wants to admit being born inferior to anyone else, but we can come up with a billion reasons as to why we're all \"equal\". When we start genetically modifying humans, we are no longer equal to each other. Equality is the social contracts that we all sign to live in peace with one another. When we start making **better** humans, that inferiority and jealousy takes over. What's the point of your own sad, pathetic existence when James over there was literally born to be better than you, and always will be, and will enjoy the success that comes easily to him, that you will NEVER obtain no matter how hard you try. \n\nThat's why. Maybe when humans are actually capable of accepting one another, we can move on as a species. Right now, it'd just end as a blood bath."
]
} | [] | [] | [
[],
[]
] |
||
392cds | why are untruthful political ads still protected under the first amendment while ads that lie about consumer products are not? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/392cds/eli5_why_are_untruthful_political_ads_still/ | {
"a_id": [
"crzrwwb",
"crzsr6x"
],
"score": [
6,
2
],
"text": [
"Most political ads are misleading, not fraudulent. They are careful not to say things which are demonstratively and objectively untrue. ",
"Well, both are protected by the First Amendment, just to varying degrees, and both only until they do--or rather, say--something that makes them *un*protected speech. \n\nPolitical speech, historically, has been given a very, very wide berth of protection by the First. The reason? A free society needs to be able to be critical of the government, those currently *in* it, and those *wanting* to be in it.\n\nHowever, patently false, injurious claims can be slanderous and libelous, and are decidedly *not* free speech. So, how do the two coexist? \n\nActual malice. \n\nThe Supreme Court ruled, in the landmark *New York Times Co. v. Sullivan* that speech becomes its unprotected forms of slander or libel when the *public figure* about whom false claims are made can prove the claims were made with *actual malice*. \"Malice\" in this context doesn't mean \"I wish to hurt you\", instead it has to do with whether the publisher of the claims either knew the claims to be false, or acted with reckless disregard for the truth. If either of those can be proven, the published claims (in this case of a political nature) are *not* protected by the First, and damages can be awarded or other penalties enacted. \n\nSo, for those \"untruthful\" political ads, the bar is set rather high for whether the statements they make cross into \"unprotected\" territory, as the need to be able to openly discuss and criticize political goings on is essential to liberty, and thus more important than the reputation of those in government, up to a point.\n\nCommercial speech (advertising) is similar: it is \"protected\" by the First so long as it doesn't cross an abstract boundary, though in this case the Supreme Court decided that the bar should be much lower.\n\nIn *Central Hudson Gas & Electric Corp. v. Public Service Commission*, the Supreme Court decided that \"commercial speech\" isn't protected by the First (i.e. governmental regulation of the speech isn't unconstitutional) when it fails what is now referred to as the *Hudson Test*, the first \"prong\" of which reads: \n\n > At the outset, we must determine whether the expression is protected by the First Amendment. For commercial speech to come within that provision, it at least must concern lawful activity and not be misleading.\n\nSo, if an advertisement is \"misleading\", it is not protected by the First, and is opened up to regulation at the Federal or State level. This boundary is quite a bit more abstract than the *Sullivan* actual malice standard for defamation of a public figure."
]
} | [] | [] | [
[],
[]
] |
||
2je13o | in the wolf of wall street, what did they do involving the steve madden stock that was illegal and how did it make them so much money? | I thought it was because they bought lots of the stock at a low price, sold lots to customers therefore inflating the price and then selling their shares and the new higher price. However later in the film Jordan states he still owns 85% | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2je13o/eli5_in_the_wolf_of_wall_street_what_did_they_do/ | {
"a_id": [
"clau9pr"
],
"score": [
4
],
"text": [
"It was a \"pump and dump\" scheme. Buy up a company that is doing terribly, talk it up like it is doing wonderfully along with faking your income reports, then sell off some shares while everyone thinks it is hot stuff. Then vanish with your gains before people discover it was all smoke and mirrors."
]
} | [] | [] | [
[]
] |
|
1su3td | why are some colour combinations painful to look at when placed alongside each other (eg. red and green?) | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1su3td/eli5_why_are_some_colour_combinations_painful_to/ | {
"a_id": [
"ce18mxn"
],
"score": [
2
],
"text": [
"_URL_0_\n\nThis kicks me right in the eye-nuts."
]
} | [] | [] | [
[
"http://static.fjcdn.com/pictures/Painful_7aa431_1008344.jpg"
]
] |
||
31ixlh | how does a knife work on a molecular level? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/31ixlh/eli5_how_does_a_knife_work_on_a_molecular_level/ | {
"a_id": [
"cq1zdlu",
"cq1zdyc"
],
"score": [
3,
2
],
"text": [
"It doesn't. Knives work on the micrometer level, either tearing out tiny chunks of the material, like a saw, or forcing themselves into, and then forcing open, gaps in it, like a wedge.\n\nThose chunks that are torn out, or those gaps that are opened, are the size of hundreds of millions of molecules, which get on with their molecular lives, so to speak, without any real relation to the bigger picture, with its knives and tomatoes.",
"it doesn't. knife works on a microscopic but non molecular level. a knife is just a wedge that's very thin. it seperates material due to force applied on a very small area."
]
} | [] | [] | [
[],
[]
] |
||
1uc1xc | How did "...berg" and "...stein" become Jewish last name suffixes? It seems like they should be universal names for Eastern Europeans. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1uc1xc/how_did_berg_and_stein_become_jewish_last_name/ | {
"a_id": [
"cegls48",
"ceglwmo",
"cegxw33",
"ceh7htd",
"cekzwxg",
"cemg78o"
],
"score": [
22,
152,
2,
2,
2,
2
],
"text": [
"Jewish names can be patronymic, matronymic , occupation or place names, or even chosen for their cadence! for example:\n\n**Patronymic**\nson or sohn, eg *Mendelssohn* - son (yiddish)\nwich or witz, eg *Stanowitz* -Son (slavic origin)\n**Matronymic and Craft**\nMan, eg *Goldman* - Gold from Golde, Man Meaning Husband of.\nMan is also used in occupation and craft names, eg **WASSER** (Water)man , meaning water carrier or **ACKER** (plow) man.\n\n**Place of Origin**\nNames ending in Y/ Ski can often be denoting place of origin, eg, *Berliny* or *Goranski*.\n\n**Common name composites and their meanings**\n\n**Stein** - Stone ,\n**Berg** - Mountain ,\n**Bloom** - Flower ,\n**Fein** -Fine ,\n**Baum** - Tree ,\n**Rosen **- Rose ,\n**Blatt **- Leaf ,\n**Zweig** - Branch ,\n**Tal **- Valley ,\n**Schmidt** - Smith.\n\nHope this is helpful. My own family name is a place name, a Y being added to their place of origin.\n\n",
"I think you're falling victim to a bit of a logical fallacy here. The \"-berg\" and \"-stein\" names have become stereotypically Jewish in the Anglophone world because many Jews have them, but by no means were these names exclusive to Jews in Europe. Fair warning, I'm not Jewish myself, but:\n\nJews did not really even have traditional surnames in Europe (again, we're discussing Ashkenazi Jews here, which is only one branch) until around the 19th Century. This started under Emperor Joseph II of Austria-Hungary, who issued something called [The Edict of Tolerance](_URL_0_) in 1782. This recognized, to some extent, religious freedom for Jews, but five years later, the Emperor also [compelled them to adopt German surnames](_URL_1_). Prussia did the same thing not long after. Then, when Napoleon took over most of Europe, he also compelled Jews in various regions to adopt surnames. \n\nThe reason many of these surnames have suffixes like -berg, and -stein isn't totally clear. Some may be because Jews adopted the surnames of the local lord of their region, many of whom had names ending like this. Others may be because Jews often were given toponymic names, because this was the most obvious option. Jewish names like Deutsch and Frank, for example, are general toponyms, but you might also get more specific like von Mises or Krakauer. Sephardic names, also, are almost entirely locality based: Silva, Navarro, etc. \n\nSince -berg often ended places that were near or associated with mountains, this is a possible origin of the commonality with Jewish names. It's also possible that since Jews were picking these out, that some of them were artificially created and just based on town or locality names, like Rosenberg or Birnbaum. \n\nSome Jews paid lots of money to have nice names, which is why you have a lot of association with gold and silver and diamonds and such. Others got new names when they immigrated from Europe to America or elsewhere and were compelled to give names at the immigration office -- this would explain names like Greenberg, an amalgamation of English and German. \n\nAlso, like anyone else, Jews sometimes took or were given names associated with their professions. So names like \"stein\" or \"Steiner\" being associated with Jews might have been because they were jewelers or stonecutters. This is also why names like Kaufmann and Marchant are popular with Jews, along with Schumacher, Gerber, Spielmann, etc. Even names like Banks. None of which, I might add, are considered at all exclusive to Jews.\n\nAnyway, I'm digressing. The simple answer to your question is that those types of endings are just stereotypically associated with Jews in the Anglophone world, probably due to so many Jews with names of that nature being prominent in show business (among other areas). But those names are also common to many non-Jewish Europeans: Stefan Edberg is not Jewish, for example, nor was [Baron vom Stein](_URL_2_), for another.",
"This might be divergent enough for a whole other thread, but what about Russified German-Jewish last names: Shteyngart (Steinhart), Vayner (Wiener), et al? Did the migration of Ashkenazi eastward actually happen after this point?",
"When the Jews were forced to take German surnames, many chose to carry their Jewish history with them in the form of cryptic alludes to the Jewish culture/religion. There are many examples with many names. Some took names that sounded similar to Jewish names and tribes.\n\n* Meier/Meyer (\"dairy farmer\"): One of the most common German names also became a common Jewish name because of it's closeness to *Meir*. An illustration is Golda Meir who was Golda Meyerson before she \"re-hebrewed\" her name.\n\n* Rubin (\"ruby\"): Similar to Ruben.\n* Selig/Seligmann (\"blessed\") for *baruch*\n* Zucker (\"sugar\") for Zacharias\n\nOthers alluded to fruits of the holy land or biblical figures\n\n* Baum (\"tree\") for Abraham, the founder of the Jewish family tree.\n\n* Teitelmann (\"Figman\")\n\n* Stammler (\"stutterer\") for Moses \n\nColors and animals were used in names according to their symbolization of Jewish tribes\n\n* Roth (\"red\") for Ruben\n* Löwe/Löw/Loeb (\"lion\") for Juda\n* Grün (\"green\") for Simeon\n\nAnd some were downright obscure, like\n\n* Maus (\"Mouse\") for Moses\n* Apfel/Epi (\"Apple\") for Ephraim\n* Oppermann/Opfermann (\"Sacrifice man\") for Cohen\n* -burg or -berg for *baruch*\n \nThe tl;dr is really: The distinct sound of German-Jewish surnames exists because many Jews tried to bring a little piece of their own culture and religion into those new, forced names.\n\n[Source.](_URL_0_)",
"Just saw this on /r/linguistics and thought of you, OP!\n\n[An interesting Slate piece on Jewish surnames.](_URL_0_)",
"I found this to be relevant to the discussion: _URL_0_"
]
} | [] | [] | [
[],
[
"https://en.wikipedia.org/wiki/1782_Edict_of_Tolerance",
"http://sh1.webring.com/people/bt/touviagoldstein/documents.html",
"https://en.wikipedia.org/wiki/Heinrich_Friedrich_Karl_vom_und_zum_Stein"
],
[],
[
"http://books.google.fr/books?id=4LssAAAAYAAJ&printsec=frontcover#v=onepage&q&f=false"
],
[
"http://www.slate.com/blogs/lexicon_valley/2014/01/08/ashkenazi_names_the_etymology_of_the_most_common_jewish_surnames.html"
],
[
"http://www.slate.com/blogs/lexicon_valley/2014/01/08/ashkenazi_names_the_etymology_of_the_most_common_jewish_surnames.html"
]
] |
||
2y51o6 | traditionally, why do conservatives support israel while liberals do not support israel? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2y51o6/eli5_traditionally_why_do_conservatives_support/ | {
"a_id": [
"cp69zdm",
"cp6a1w3",
"cp6a7pm",
"cp6bilb",
"cp6c9ix"
],
"score": [
8,
2,
8,
4,
3
],
"text": [
"Both parties in the US support israel. At this moment, however, we've got political gamesmanship. The GOP invited a foreign leader to speak to Congress in an unprecedented move, because they want to undermine the POTUS and Sec. of State's negotiating power so that they have an election item to sqwauk about. Similarly, the POTUS administration when it heard the foreign leader was coming and had set up the appointment to speak, decided to snub him because it was the other party doing the inviting.\n\nBoth Liberals and Conservatives have supported israel and the middle east peace process, back to Jimmy Carter. ",
"Traditionally in American politics there has been broad support of Israel by both Democratic and Republican politicians. The current situation is more that American conservatives and Israeli Likudniks have become very, very closely aligned, to the exclusion of some American liberal support Likud ",
"'Neoconservatism' is a branch of conservatism which deals with the creation and maintenance of popular social myths.\n\nDeveloped in response to the perceived failure of the civil rights movement to bring racial unity, the American Neoconservative movement promoted the myth of the Cowboy - that America was a heroic nation which rides in to save the day when the bad guys are all around. This myth was dependent on the existence of an enemy - the soviet union.\n\nBack in the 1970s, Donald Rumsfeld (later to be Bush's secretary of defense) sat on a special intelligence task force known as [Team B](_URL_0_). Among their findings were that the soviets had an underwater laser sensor net and directed energy weapons (eg laser beams). The later collapse of the soviet union necessitated a new lie - the idea that there is a War on Terror where America is Freedom and Terrorism is Tyranny.\n\nWhat makes these myths dangerous is that they're mostly-truths. The US does intervene positively in international affairs, and Terrorism is scary. But when we believe these things on a mythological level, where they evoke emotions in us, we can make terrible errors, invading the wrong country or escalating tensions when there could be peace.\n\nThe current leader of Israel is a neoconservative. He is facing increasing division at home due to the many disparate cultures that his people come from, and is attempting to promote the myth of the 'Bastion of Democracy', that Israel stands with barbarians at the gate under a constant siege.\n\nThe danger of this myth is that it blinds us to opportunity. Israel does have enemies beyond it's border, but when we believe on a mythological level (eg, one that makes us feel an emotion) that Israel is under siege, then we fail to notice chances to improve the situation. A permanent peace with Iran is a good example of an idea like that - Mossad has made it clear, both publicly and via wikileaks, that Iran does not have weapons of mass destruction and is not presently trying to acquire any. The peace under the current terms poses no risk.\n\nLiberals are often seen as opposing Israel because they do not support the neoconservative fantasy of the Bastion of Democracy. We believe that Israel is best served by increasing it's integration with other regional powers through bilateral trade agreements and avoiding insulting rhetoric.\n\nThere is also the ongoing humanitarian crisis in the West Bank that defies solution. The present administration in Israel has done nothing to halt the expansion of political radicals from Israel into the west bank, leading to increased violence and deteriorating chances for peace.\n\nIn short, everyone in the west supports Israel as a nation, but many believe that Benjamin Netanyahu is little more than an Israeli George Bush, crying for war on false pretenses with little regard for the innocents he destroys in the process.",
"Liberals and conservatives tend to have a very different perception of violence. Liberals tend to view violence emotionally, as a negative part of life. Conservative tend to view violent neutrally, as a regrettable part of life.\n\nYou see this manifesting in everything from foreign policy to law enforcement to gun control. In terms of Israel, what liberals see is the powerful Israelis beating up on the weak Palestinians. What conservatives see is the civilized Israelis defending themselves from the barbaric Palestinians.",
"On top of what's been said already, you may also want to look at things like this : Israel is a pretty conservative country, and since 2001 has been mostly governed by conservative parties. So it's only natural that conservatives love them while liberals don't so much. Liberals would probably love Israel if it was left-leaning. I think Clinton had a pretty good relationship with the Israeli government in the late 90s / early 2000.\n\nAlso, the conservatives are very much in an \"us vs them\" view of the situation : Israel is part of \"us\" (they're white, they're non-muslim, they have a \"western\" culture) and its neighbours are part of \"them\" (they're less white, they're muslim, they have a different culture, they're not democracies...)"
]
} | [] | [] | [
[],
[],
[
"http://en.wikipedia.org/wiki/Team_B"
],
[],
[]
] |
||
2bpzr8 | flat personal tax/consumption tax. | Here's my thinking. The tax code (in the US but I'm sure other countries have similar problems) is SO complex that a million loop holes exist. If the tax were changed to twenty pages of simple layman's jargon these holes would be closed. The economic drain that occurs as a necessity of employing so many people as tax professionals, could be put toward productive endeavors. So besides political objections, what's wrong with this plan?
Edit: Along the same lines, you could cut campaign finance law down to a single page of law. "All contributions to a campaign must be disclosed publicly." And the, literal horde, of people who works to write/understand these laws could move on to productive things. Any reason this is a bad idea? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2bpzr8/eli5_flat_personal_taxconsumption_tax/ | {
"a_id": [
"cj7r7o4"
],
"score": [
4
],
"text": [
"A flat tax is inherently regressive, and puts more of a burden on the people who can least afford it.\n\nA consumption tax is even worse, because the people who can most afford to be taxed also spend the lowest percentage of their income on essentials.\n\nA progressive income tax solves these problems, but is complex to implement.\n\nThus, we have a progressive, but complex, tax system."
]
} | [] | [] | [
[]
] |
|
5ekwie | why is audio/voice quality so bad between crucial communication lines (soldiers/police/pilots etc.) | Why in 2016 is the quality still so bad? It's like they're using happy meal toys. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5ekwie/eli5_why_is_audiovoice_quality_so_bad_between/ | {
"a_id": [
"dad76sn",
"dad85ke",
"dad8e4m",
"dadhwdn"
],
"score": [
3,
16,
5,
2
],
"text": [
"Oftentimes the audio quality is fine, but when they record it, they use a very low bitrate, which makes it sound junky. They do that to save space, obviously. And for 99.99999% of the time, that recording is archived and never heard again, so it makes sense to save as much room as possible.",
"Main reason is bandwidth - I'm not talking about the amount of data you use a month, but the range of frequencies a radio signal takes up. Soldiers, police, pilots, truckers, taxi drivers, firefighters, and lots of other businesses and professionals all want their own radio frequencies so they can communicate. \n\nAs a rule of thumb, the more bandwidth, the better the sound quality. But the more bandwidth, the fewer frequencies can be assigned to different groups within a given range of frequencies. So if the government let people have super high quality radio signals, they wouldn't be able to assign them to everyone that needed it. Instead, just enough bandwidth so they get usable quality. As the technology improves to get better sounding audio in a narrower bandwidth, regulatory bodies would rather that they fit more \"acceptable\" quality channels in a frequency range, rather than letting people have great quality channels at the expense of others who need a new channel.",
"The requirements for military or first responders (fire, police, ambulance) or for aviation are drastically different than for cell phone wireless. \n\nCall quality is based on data rates which has _some_ impact by frequency; higher frequency usually = higher data rates. Call quality is less important than other features: no call drops, much larger range (lower frequency = more range), the ability for peers to communicate directly in the absence of infrastructure (towers), ability for radio to penetrate into buildings through concrete and a bit underground (within limits). You need to have encryption and security so people/bad guys can't listen in, you need to be able to re-organize subscriber units or even your transmit/receive infrastructure on the fly. Add to all these other non-call quality requirements the fact that the amount of testing required is an order of magnitude higher - if a network switch in a GSM network gets a poorly tested firmware update and brings down a few cells, well probably not the end of the world. If a trunked radio cell used by fire/police/ambulance is out, people's lives could be at risk. If a military radio can be temporarily messed by someone's microwave, someone can't call in the evac helo or call in the cavalry. \n\nSo long as the call/transmission is clear enough to be understood, that's all that is required. Other requirements are more important.\n\nsource: used to work in emergency radios and telecomms.. a long time ago. An amusing story that sort of illustrates my point - I asked a senior design guy once \"hey, my $60 flip phone can get three days of normal usage out of this tiny battery AND it can play Tetris. How come cops still like lugging around these two pound bricks? Certainly we can make a radio that slips into a pocket?\" and he said essentially that there's a reassurance knowing that the two pound brick on your belt will _always_ be able to reach dispatch or talk to a partner... through concrete or across miles; a solid brick lends to that. Its big, you know that in a pinch if you're trapped you have a while before you have to start worry about how many bars of power you still have. John McClane didn't have to worry once about plugging in his radio. If he'd had a small cell phone sized radio, he would have had to plug it in at least once before Hans fell off the Nakatomi Tower. Also, if a cop has to take out their gun or their nightstick they have to fill out all this boring paperwork. They don't however have to fill out paperwork to take their radio off their belt. ",
"Also, going out on a limb here, they don't update their systems with the frequency that say a cellphone is updated. \n\nThey can use the old units and integrate New without having to overhaul everything provided you can make out what's being said. It's designed for brute force ugly functionality. "
]
} | [] | [] | [
[],
[],
[],
[]
] |
|
24dgze | what is a high functioning alcoholic and what is the problem with that? | The term "High Functioning Alcoholic" seems to be meaningless to me. Reading the literature it states that an HFA has
* The ability to be professional
* The ability to maintain and create relationships
* Does not display any signs of struggle in their life
* Has not gotten into trouble due to alcohol
Yet, they're still classified as an alcoholic. How can one be professional, liked, respected and have no outward signs of problems and still be alcoholic? If one is an alcoholic, but has no outward issues, what is the actual problem they have that needs to be solved? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/24dgze/eli5what_is_a_high_functioning_alcoholic_and_what/ | {
"a_id": [
"ch617zj",
"ch61ayp",
"ch63jwf"
],
"score": [
10,
2,
2
],
"text": [
"(1) They are doing a lot of damage to their liver and physical health in general - which is entirely their choice and right.\n(2) They may have underlying psychological issues which they are very good at masking, but may turn out to be a problem in the long-term (e.g. PTSD)\n(3) They may not be a High Functioning Alcoholic forever. They could get better, they could get much, much worse. Addressing the problem while they are still high-functioning is a much better option than crashing and burning.\n\n(I don't necessarily think that all heavy drinkers are high-functioning alcoholics, or that high-functioning alcoholics are in desperate need of treatment, just presenting some counter-arguments).",
" > How can one be professional, liked, respected and have no outward signs of problems and still be alcoholic? If one is an alcoholic, but has no outward issues, what is the actual problem they have that needs to be solved?\n\nBecause they're still dependent upon alcohol and thus liable to have some kind of crisis at any moment. This could be because for whatever reason they don't get their drink that afternoon. Or it could be because today is the day that they stopped being able to hold it together. They're a ticking time bomb.\n\nThe \"actual problem\" is not precisely something that they've done something bad or screwed something up, but the fact that they are at significantly increased *risk* of doing something bad or screwing something up precisely because they're drinking too much. \n\nIn essence, a \"high functioning alcoholic\" is a lucky alcoholic. They haven't had any overtly negative consequences from their drinking *yet*. But they're still drinking more than is good for them, and they are almost certain to face some negative consequences for that sooner or later.",
"Also, they are drunk when they do everything. It's a huge liability, and can be dangerous. My friend's mother was a high functioning alcoholic for many years. You know what she did? She was a registered nurse. Would you want a nurse running an IV into you with her breath reeking of vodka?"
]
} | [] | [] | [
[],
[],
[]
] |
|
49q2ua | what causes that feeling a split second before your realize you're about to have a very big accident? | Like when you're walking downstairs and miss one step and you're about to take a tumble, there is that fraction of a second where it feels like your heart is jumping into your throat?
I feel like whenever this happens I become way more alert than previously. Is there a natural way to reproduce this feeling with food or drugs? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/49q2ua/eli5what_causes_that_feeling_a_split_second/ | {
"a_id": [
"d0ttwfg"
],
"score": [
4
],
"text": [
"Its your fight or flight response.\n\nWhen you sense that you are in danger, your body releases a bunch of chemicals that prepare you to either fight the threat or run away from it. Your get more alert, stronger, faster and more coordinated to facilitate either action."
]
} | [] | [] | [
[]
] |
|
22axk7 | why is air less dense at higher altitudes? | This is probably a really dumb question so sorry in advance. I guess there are formulas which will explain this, but what properties of air make it less dense at a higher altitude? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/22axk7/eli5_why_is_air_less_dense_at_higher_altitudes/ | {
"a_id": [
"cgl1c25"
],
"score": [
11
],
"text": [
"Imagine you stacked 100 cardboard boxes on top of each other. The one on the bottom would be crushed due to the weight of the other boxes on top of it. It being compressed would cause it to become denser than the other boxes above it. \n\nReplace the cardboard boxes with air and magnify the effect. That is why the air is less dense at higher altitudes. \n"
]
} | [] | [] | [
[]
] |
|
5xq62n | Why does North Korea have such few allies? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5xq62n/why_does_north_korea_have_such_few_allies/ | {
"a_id": [
"denik7n"
],
"score": [
4
],
"text": [
"North and South Korea both claim to be the one true Korea with the other one being an illegitimate government. Historically, both sides have legitimate claims with Pyongyang and Kaeseong both being major capital cities of former dynasties during Korea's 5000 year history.\n\nAfter the Korean War, both sides attempted to claim legitimacy on the international stage through diplomacy. They would sign deals with other nations usually with the caveat that those nations not recognize the other Korea. Naturally, the Cold War participants and their allies aligned with the respective Korea's with the Third World being the toss-up countries.\n\nSouth Korea had much more recognition during the 50's and 60's due to the fact that the UN backed the South during the Korean War. In the early 1970's, North and South Korea began to talk and with that came more recognition for the North. By 1991, both Koreas wanted into the UN and were only allowed in on the condition that both of them were allowed in as separate, recognized countries.\n\nAs to why they have so few *allies*, that has to do with the collapse of communism. North Korea has mutual defense treaties with China and Russia. Previously, the Russia deal was with the USSR. At the DMZ, the northern neutral observers were from Poland and Czechoslovakia, two (now three) countries that have been part of NATO for the past 15-20 years. With the collapse of the Warsaw Pact, Soviet allies fell away leaving only Russia and China.\n\nWhy don't they get more allies? Who would want to be their ally? In the 1980's, the North attempted to assassinate the South's president in Rangoon, killing multiple people in the attempt, they blew up a Korean Air flight, and they kidnapped Japanese and South Korean civilians. In the 90's, they pulled out of the Non-Proliferation treaty and began pursuing nuclear weapons. You can look at what they've done in the last 20 years (VX nerve agent assassination in a major international airport?!?!) and draw your own conclusions as to why no one is rushing to jump on the North Korean bandwagon these days."
]
} | [] | [] | [
[]
] |
||
2mbrvd | Can there be an object of sufficient mass that light would orbit the object due to gravitional lensing? | askscience | http://www.reddit.com/r/askscience/comments/2mbrvd/can_there_be_an_object_of_sufficient_mass_that/ | {
"a_id": [
"cm33twd"
],
"score": [
7
],
"text": [
"Yes. If an object with mass M has a radius less than 3GM/c^(2), [light can circle entirely around the object](_URL_0_). The density required for this is pretty extreme; it's limited mostly to black holes."
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Photon_sphere"
]
] |
||
5nas3e | Why do European monarchs almost always have adjectives applied to their names? (i.e. Louis "the Pious" of France) | Also, is it something that was added by historians after the fact, or were they generally given during a monarch's reign? (Presumably some, like Charles the Bald, wouldn't have liked this). | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5nas3e/why_do_european_monarchs_almost_always_have/ | {
"a_id": [
"dca4oie"
],
"score": [
2
],
"text": [
"For both Louis the Pious and his son Charles the Bald, these were both names by which they were known during their lifetimes. As for Charles' opinions on his nickname, we've no record of how he felt about it, but he might well have like it and found it funny, since it's possible that it was ironic, and that he was in fact an unusually hairy man - given that we know the name was used during his lifetime and any contemporary depiction of him has a full head of hair.\n\nAs for the why, I'm not sure I can answer that one. It does help to distinguish between kings with the same name who ruled around the same time (like all the later Louis' in French history), but given that Louis the Pious was also Louis I, that doesn't really hold up. I've never read an explanation of it, to be honest - sorry!"
]
} | [] | [] | [
[]
] |
|
5ggx16 | why does american culture put so much emphasis on "moving out of the house" and being independent from one's family, when other cultures (e.g. asian and spanish) live with their extended family under the same roof throughout their lifetimes? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5ggx16/eli5_why_does_american_culture_put_so_much/ | {
"a_id": [
"das3yej",
"das4o89",
"das4rxc",
"das5tpr",
"das6080",
"das63s9",
"das6861",
"das6cb8",
"das6heg",
"das6nma",
"das6oum",
"das7ete",
"das7ruz",
"das8f3d",
"das8imo",
"das8jdq",
"das8v34",
"das8x1b",
"das8xhm",
"das8xzr",
"das8y2f",
"das8zmj",
"das95zk",
"das9659",
"das96bp",
"das96xr",
"das980v",
"das99vr",
"das9edu",
"das9f7a",
"das9keg"
],
"score": [
19,
137,
12,
12,
4,
3,
101,
61,
421,
2,
55,
7,
26,
22,
2,
5,
2,
5,
2,
2,
2,
5,
64,
2,
5,
3,
2,
3,
2,
3,
2
],
"text": [
"In this culture, It is viewed as \"the bird leaving the nest\". In a sense it reflects on the parents and how well they did preparing their children for the world. ",
"Being self sufficient is a major part of they American Mythos and cultural identity. It is the same reason that we are resistant to socialized health care and welfare programs. ",
"Because that's how you keep housing inflation and construction up. Can't have lazy kids living with mom in the basement because then our consumer based economy suffers. ",
"Those old world civilizations don't quite have the same surplus of property that we do in America. And so from the colonial days, the aspiration (or expectation in many cases) is that you become self sufficient and move out because thats what a strong individual is capable of. ",
"At some point an individual could support themselves on a single job... Now a days you need two people working full time jobs to stay above debt... \n\nIts unfortunately the same where I live in Canada too... ",
"In cultures where the family lives together, think of the family as an individual. This is where we misunderstand these cultures in things like honor killings -- it's akin to amputating a gangrenous arm for someone who lives in an individual-focused society. It's like metric, and standard societal units, where one is the individual, and one is the family. ",
"I'm spanish and that's not true. We also get out of the house when we become auto-sustainable in economic terms.\n\nEdit: by spanish I mean SPAIN, EUROPE, yeah that spot between africa and france. ",
"Some aspects of American culture are that you can strive to be/do anything you want. Another aspect to that is going out and doing it. There's a very 'can do' attitude that doesn't always fit with staying at home and perpetuating the family unit. \n\nPeople don't live in the same area (let alone the same house) their whole lives, they move to new places, explore new opportunities, and build the life *they want* for themselves. Not necessarily the life their parents (and grandparents) have laid out for them. ",
"Rugged Individualism. It's the concept Americans have hard wired in our brains. The mark of being an adult is going out on your own and providing for yourself. It's a sense of pride and accomplishment to leave the safety of your parents house and pave your own road to success. This mindset has its advantages, as well as some disadvantages. Moving out is an extension of the mentioned \"rugged individualism\" but there are several faucets to this concept. \n\n_URL_0_",
"As an American I know what you are saying. I am a country manager of oil and gas companies in the middle east. My guys buy houses to move their parents in with them. I honestly ask them WTF but that is they way they think. We GTFO as soon as we can, I joined the damn USMC!\nThis is a good question though.\nPlease ELI5",
"Isn't it (also) to do with individualist vs collectivist societies? Ie. One society views an individuals needs as most important, while the other society believes your job is to maintain a strong community.",
"Because it stimulates the economy. If everyone lived at home, that's so fewer houses, cars, kitchen gadgets, etc that would have to be sold. \n\nConvincing the populace they must be independent is how corporations sell more goods.",
"This was present in Anglo Saxon culture since the 7th century but the kids would move into a house pretty much next door so it wasn't really about independence, probably because English women had a lot of say compared to other cultures they refused to have their mother in law living in the house with them and telling them how to raise their kids (which is still pretty much what happens in many Mediterranean families). ",
"Mainly because I could never ever bring a girl to my parents house.\n\nThey would either cockblock the fuck outta me or imply that we are both sinners and going to hell before informing me that they will not tolerate that evil in their house and that if it ever happens again they'll kick me out.\n\nSo I'm basically stuck with no dating prospects until I can get out. But I guarantee they'll be nagging me before too long about why they dont have grandkids.",
"Because Asian culture benefits/ profits/ gets a sick pleasure out of enslaving and forcing their own family to do things for them\n\nEg: Carry on generations of lineage, heirlooms, superstitions, religious beliefs. Also making children follow in their footsteps due to harsh circumstances (like the economy or business ethics) or simply out of fear (God will smite them and send them to hell)\n\nYes, even wax the windows or dropping the jacket and picking it back up...\n\nAm Filipino. Can confirm",
"Because by living by yourself, you have more bills to pay, thus need to put in more hours at your job or jobs to pay for them, and get additional expenses such as hiring a babysitter for the children, or things of that nature. All of this directly benefits capitalists.",
"Canada is similar. I think it's because we have so much space and are a nation of immigrants. We're descended from people that moved far away from their families in many cases, so it makes sense that that idea is carried down a bit. ",
"Idk why but then they all complain about not having money and not being able to afford rent, bills, college debt, etc. You save thousands of dollars a month by not moving out. More people should try it (that is not moving out immediately after high school/college, not living with your parents til your 30)",
"Because we're a country of people that values self reliance, independence and individualism (often at the expense of others and the greater good..)",
"One reason among many is because it's much easier than other countries. Income is generally higher and the land space is proportionally cheaper.",
"I have spanish family - that's simply false - most people I know from Spain move out as soon as they can.",
"I'm actually in the middle of moving out of my parents house today and this is very interesting to see the different responses. I'm leaving because I just want to be out on my own. I make plenty of money to take care of myself and I just wanna do my own thing. ",
"Singaporean here, thought I wanted to share a bit about the Asian perspective on this. \n\nFYI, we're a multiracial country, Chinese, Malay, Indian and Eurasians. I'm a Singaporean Chinese (we form the majority of the population), so I can try to speak for my demographic, although some values are shared across races. \n\nWe usually stay with our parents sometimes even after we're married for a few reasons. We're only reasonably expected to move out after marriage. \n\nFirstly, houses in Singapore don't come cheap, because land space is super limited. And if you want to get government housing (from the Housing Development Board), you have to apply for that and wait years before you get the keys to your house (also you only can purchase HDB apartments if you're married). Even then, housing's still not cheap. We have financial schemes like the Central Provident Fund to help us out, but there are other issues, too. Basically, it's ~not easy~ impossible to find a house when you're a youngish adult unless your family's shitting money. \n\nSecondly, Asians value filial piety a lot (something something Confucianism). Living with your parents means you care for them. Moving out before marriage is kind of a stigma, like you're trying to get away from your parents - that sort of thing. Again, unless family is super rich and has different ideals and values, this would be different, but I'm talking in generals. Around 18 is still a very young age for us, too. As long as we're studying (and even during our first years in our first jobs), we're still our parent's children. With Singapore's focus on education, more and more of us are studying for longer periods, and slower to find jobs, especially in the current economy. Plus, all guys have mandatory national service so that's another extra 2 years staying with the parents. \n\n\nI think the main difference between my Asian culture and an American one is 1, land space and 2, different values on life. \n\nMore land space = more (financially accessible) houses. Purchasing more houses = better economy. \n\nAlso I think I saw in a few other comments about individualism. I obviously can't speak for Americans, but it is clear that Asian and American values are very different. Moving out means being financially capable and growing out of your own. It may even be filial piety in a Western sense - no longer living off your parents and being a responsible human. It seems like an important moment of being/becoming an adult. \n\nEdit: found out that you can purchase a HDB apartment if you're over 35 or your parents have passed on. Basically some other conditions to ensure that everyone has a roof over their heads regardless of financial/social disposition. And grammar.",
"In American culture it's considered a weakness to live with family above a certain age. It's really an illogical cultural conformity. Just one more thing implanted into the minds to fuel the materialistic consumerism society. However, the recent economic decline, among other things, seems to be changing such views.",
"That´s one thing i cannot understand. I am mexican, I will be living with my mother until I get married, and...\n\n\nI began providing money for the house since I was 7. Nobody can tell me I live with my mom just because a fear of independence, I lived 5 years alone and still sent money. \n\n\nI am anxious to see the answers this gets.",
"As with rugged individualism, it's a sense of ownership and permission to use mutual spaces.\n\nI've been living with my parents for 4 years, as I'm married and have 2 kids, it's getting harder and harder to find acceptable times and uses for these common areas. It makes us feel like we are unable to invite school friends over, because we don't know what mood/events my parents have going on in the common rooms.\n\n9 and 6 is where my kids are, and it's increasingly difficult to find activities that you can do in public places that still cultivate a relationship with classmates ",
"There's a lot of comments here about Old World vs New World attitudes. It's not explicitly an American thing and Most of Western Europe does also emphasise leaving home.\n\n[Here's a map](_URL_0_) showing how actually a lot of European youth does actually move out of their parents'.",
"I think you overestimate and misunderstand how people live with their family in other cultures. The idea is that you leave the house when you become an adult, go out and make your way in the world, and then you come back and take over your parents' household or you get your own place and they join you. There's a difference between you living with them and them living with you.\n\nOn the other hand, a house being tied to a family is more prevalent in \"Old World\" cultures, since that was the way things were up until urbanization skyrocketed in the early 20th century.",
"Americans can afford it. People in less prosperous countries would like to move out and live in their own home as well, but they lack the means to do so.\n\nThere's a saying in Brazil that goes \"quem casa quer casa\". People who marry want a home. That's a word play between the verb \"casar\" meaning \"to marry\" and the noun \"casa\", meaning \"house\".\n\n",
"There are many things that have shaped that aspect of American culture; I would go so far as to say that it is a relic of the quasi-religious basis for Manifest Destiny (which in fact, shaped Rugged Individualism). When the expanse of the American western frontier seemed to stretch forever ahead of mostly WASPs, the Old Testament mandate \"Be Fruitful and Multiply\" became a life goal for couples - the large family was actually useful when running a homestead. Reactively, the most significant social rite of passage was creating a new family. While today it would, at most, be considered only slightly shameful to start a new family without being able to provide (this attitude varies with age/community/location/etc - I experienced it a lot as a child in a very religious, rural part of West Virginia), at the peak of westward expansion it would likely mean death. \n\nAdditionally, there have been a variety of religious (again, mostly Protestant variations on a theme, from what I can gather) attitudes influencing the push for new couples to carry out their mating in a house other than that of the parents.\n\nSo, while I don't see these motivations as being prevalent or conscious at present, I believe they have established a pattern and a set of \"norms\" that are outdated and slowly changing.\n\nI would also add that a common \"rite of passage\" for many young adults is a complete rejection of the ideals of their parents - at least for awhile. During that period, it is good to have them out of the house :-)",
"I'll offer an explanation that is a bit more historically oriented.\n\nThe grand ol' USA is a very new country. With the exception of a few old East Coast cities, the USA is a land that was found, developed and lived in during a time of plenty. The US is basically a product of a civilization formed during industrialism, and also in the context of having an enormous amount of square feet of land per capita.\n\nThe US therefore \"grew into\" the land and the historical context that it developed into. Contrast this with anywhere in Europe or Asia, where all the nice places have towns or cities that have existed for a very very long time, and were developed with the constraints of non industrial agrarianism. Not only is the physical infrastructure there already, but the culture is ingrained.\n\nOnly a very wealthy people can have most people move out when they turn 18, and the US is fabulously wealthy when you compare it to the historical norm of the human race. "
]
} | [] | [] | [
[],
[],
[],
[],
[],
[],
[],
[],
[
"https://en.m.wikipedia.org/wiki/Rugged_individualism"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"http://brilliantmaps.com/wp-content/uploads/europe-living-with-parents.png"
],
[],
[],
[],
[]
] |
||
3ce0ew | how comic distribution works? | I got into comics in 2013, and while I only keep up with two series (Mega Man and X-Men), I'm still really confused at how comics get released, just because I go to my local bookstore every so often instead of a comic book store (which I go to once every few months). I don't understand how back issues or rarity works either. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3ce0ew/eli5_how_comic_distribution_works/ | {
"a_id": [
"csuo6kc"
],
"score": [
2
],
"text": [
"Most American comics are produced on a monthly basis, about 22 pages per month. These comics are published by a publisher (DC, Marvel, Dark Horse, Etc.) and then distributed by a company called Diamond, who pretty much have a monopoly on comic distribution. These individual issues are pretty much only sold in comic book stores, though, some book stores carry some.\n\nMonths later, these comics may be recollected into \"trade paperbacks\" which will have 4-12 issues all together. Even more issues might also be recollected into even bigger collections- the biggest I've ever heard of in a single volume is The Invisibles Omnibus, which is 59 issues in a single book.\n\nBack issues you generally have to hunt down in comic book stores or at comic conventions. Rarity is sort of pointless to track, but in short, certain first-editions of first-issues become popular collectors items. Finding non-first-editions of these first issues is pretty easy, but they aren't considered rare or valuable."
]
} | [] | [] | [
[]
] |
|
at3p9k | what causes the urge to move around after hurting yourself? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/at3p9k/eli5_what_causes_the_urge_to_move_around_after/ | {
"a_id": [
"egydkqm"
],
"score": [
11
],
"text": [
"You gotta run the pain off. For real, in the wild, if you get hurt, there's probably someone or something that hurt you and your body wants to get away from them asap so you don't sustain any more injuries. "
]
} | [] | [] | [
[]
] |
||
8gw1g2 | When the mars rover went to mars were they able to remove all bacteria and small life from it? If not could any of the bacteria be able to live in the harsh conditions of mars? And how do they obtain soil samples looking for bacteria if it could possibly be from the rover itself? | askscience | https://www.reddit.com/r/askscience/comments/8gw1g2/when_the_mars_rover_went_to_mars_were_they_able/ | {
"a_id": [
"dyf6uiw",
"dyfdc1h",
"dyfdrjz",
"dyfe0qn",
"dyff9yt",
"dyfgntn",
"dyfks81",
"dyflu1v",
"dyfngku",
"dyfowig",
"dyfqjbn",
"dyfrxfg",
"dyfwpqf",
"dyg2ivw",
"dyg6suo",
"dygh7de"
],
"score": [
5257,
8,
69,
671,
103,
49,
2,
21,
2,
2,
2,
4,
2,
49,
10,
3
],
"text": [
"Anything that is sent to Mars is thoroughly inspected, cleaned, and sanitized {[_URL_1_](https://_URL_1_/msl/mission/technology/insituexploration/planetaryprotection/)}. There are some microorganisms that can still survive a trip to Mars, such as a well-known [Tardigrade (Wiki)](_URL_0_). That's the main reason rovers avoid parts of the planet that contain water or ice - they can still carry Earth's life and contaminate it {[_URL_4_](_URL_2_)}.\n\nSo far all life-detecting tests done by rovers are interpreted as negative. If we find a sign of life on Mars, we will make sure it's not brought by us from Earth.\n\n**Edit: Answering a few questions that keep repeating.**\n\n > *Why do we refrain from contaminating Mars? Wouldn't that be an interesting experiment?*\n\nIt would be, but before we do that, we want to make sure there is no native life on Mars that we might accidentally destroy (as we often do). If we find micro-organisms there, it would be nice to study them without our own organisms getting in the way wherever we go.\n\n > *Wouldn't a manned mission contaminate Mars?*\n\nIt will. Before we can send humans to Mars we will have to modify the rules of the Outer Space Treaty. Hopefully we can find life there before we send humans. If not, hopefully the first humans will find life. If we don't, it's pretty clear there is no life there. But we will not be colonizing and terraforming Mars until this question is answered.\n\n > *Shouldn't we search for life in water-rich zones, instead of the opposite?*\n\nYeah, ideally we should, but because our rovers are not 100% clean, letting invasive life forms flourish in Mars's potentially already living waters, before we have a chance to at least send a few of them back to us, is just not worth it. On top of that, we don't need to check water contents to determine if Mars has life - the atmosphere and soil can give us enough clues to answer that.\n\n > *Don't we have the technology to sterilize things to 100%? Or are we that neglectful?*\n\nWe do have the technology, and we can use it with ease. The problem is that if you want to sterilize a circuit board, you end up frying it. One proposed idea is to build a rover on Mars with 3D printers, and sterilize all the necessary materials separately.",
"I would have to search and dig out links, sorry for that....but I remember to to read that with some of the recent Mars probes, some worker (?) broke protocol and contaminated the probe in some way, so bacteria/microorganisms made it on their way to Mars.\n\nA bit more googling brings up several articles where some argue that it's possible we already contaminated Mars, simply because it is impossible to 100% sterilize a probe before launch, only to a certain extent. Whether microbes survived, made it to Mars and are now surviving even on Mars on the probes...opinions differ. But it's possible.",
"Also, might it be a good idea to just go ahead and introduce the tardigrade and other microscopic life to mars on purpose? Assuming of course that we’re conclusively sure there’s no native life there. Life expansion might be worth it. Especially if we keep destroying the planet we live on, why not seed another? Millions (more likely billions) of years after us idiots are extinct there could be complex life on Mars. If the general point of life is propagation and survival I don’t see a downside in “accidentally” bringing microscopic life to Mars. Especially considering that the microscopic organisms that might be attached to whatever spacecraft gets sent there will be killed anyway in the disinfection process. So we’re not killing anything we wouldn’t be killing anyway. Thoughts?\n\nEdit: grammar ",
"I actually wrote my thesis along these lines\n I was studying Antarctic yeast species, which live in cold, dry environments and are exposed to incredible amounts of uv radiation. In other words, very similar conditions to space. Numerous studies have found that they in fact can survive in space, so it's entirely possible that other microbes could survive the trip to Mars. The yeast I studied ate rocks, do they may even be able to reproduce on Mars as well. We try to sanitize most stuff that gets sent to space, because on the off chance there is native alien life ( bacteria and what not) we don't want to accidently kill it off with an invasive species",
"When I was taking Microbiology a few years ago, I recall my prof talking about viral endospores that were able to survive space, essentially because viruses are dead and don't begin reproducing until they find a host. He went on to mention this could have attributed to developing some sort of basic life or foundation for life. No idea in the truth or evidence of this claim, but it's a fun idea to entertain. \n\nEdit: The theory he was speaking of is known as Panspermia, here's a link if you wanna to read up on it! _URL_0_",
"The thing that always bothered me: is the bacteria flat out removed, or are they just hoping 'killed' bacteria and small life won't factor into anything.\n\nKilled bacteria can't just break physics- it retains some mass or existence right? I mean it's why even after washing your hands you still wear sanitary gloves when bacteria is a factor that could influence something...\n\nUgh- Not quite sure I worded all that correctly.",
"This is the job of the planetary protection officer at NASA. Forward contamination, which is what you are describing, is taken into consideration during mission planning and steps are taken to mitigate it. Here is a good Wikipedia link - > _URL_0_",
"Everyone is giving great answers to your question but I just wanted to point out that saying \"the\" Mars Rover is a little unspecific. To my knowledge there have been four rovers that have successfully landed on Mars, two of which are still in active service.",
"This is actually one of the issue nasa is facing with respect to any kind of interplanetary research i.e. how to make sure not to contaminate a planet but still study it.\n\nThere are some solutions like cleaning the rovers very carefully but even those are not 100 & #37; accurate. But there will still be some left.",
"I want to add to some of the other answers. NASA has a Planetary Protection Officer, yes. But if you ask the current one if there is life on Mars she says yes, because we put it there. The sterilization process wasn't always as good or as thorough as it is now, and even now its possible some gets through.",
"Unfortunately contamination of Mars is imminent (as well as Earth with Martian life if it exists) if we are serious about colonization. Though it will be simple to distinguish the two apart genetically.\n\nAnd it's very possible that Mars still harbors microbes if life existed there before. Earth has microbes that live miles below the surface, so the only way to sterilize this planet would be to liquify the crust. It is very difficult to sterilize an entire planet.",
"NASA has a department called \"Planetary protection\" that deals with the removal of life from a spacecraft.\n\n_URL_1_\n\nThere are different levels based on where the spaceship is going. For instance, a Mars mission requires more attention than a pure space mission.\n\n_URL_0_",
"I attended a special lecture held by a microbiologist employed by NASA. His job is to sample clean rooms and stuff to be sent off world for microbes, sequence their genome, and then catalog it. \n\n1. NASA doesn't remove it all. But they write down what they didn't remove along with the genetic sequence. (See quitegonegenie's post)\n\n3. NASA checks sequences of extraterrestrial samples to the catalog of sequences created prelaunch\n\nThe problem is: if we find life, but the genome is similar to what we've catalogued, how will we know?",
"**When the mars rover went to mars were they able to remove all bacteria and small life from it?**\n\nSimply put, no. It is almost impossible to remove every single cell/spore from rovers.\n\nRovers are assembled in clean rooms \\(where the air is filtered\\), human contact is limited, surfaces are cleaned with alcohol and other harsh chemicals. Heat tolerant parts are heated to 110C \\(230F\\) and electronics are sealed. Surfaces are also regularly tested to determine bioburden levels [\\(1\\)](_URL_16_)[\\(2\\)](_URL_11_). Despite all the protocols, clean rooms are filthy \\(biologically speaking\\) and contain their own unique microbiological communities[\\(3\\)](_URL_12_)[\\(4\\)](_URL_3_). \n\nEarth life is pretty tough. Its for this reason that Martian rovers are not allowed to explore certain regions, why Cassini had to plunge into Saturn \\(To protect Enceladus and Titan\\), and why Juno has to plunge into Jupiter at the end of its mission \\(To protect Europa\\). There is always a risk that contamination may reach these planets\n\nThis idea forms the guiding principle of [Planetary Protection Protocols](_URL_15_) . This is the idea that any interplanetary missions should do everything possible to prevent contamination. Scientists spend a **long** time calculating risk of contamination into excruciating detail. NASA set a minimum risk of contamination below 0.001 & #37; and missions have to plan for 50 years after a mission ends.\n\nThe more we learn about microbes the crazier things gets and there is a lot of ongoing research into extremophiles. Microbes are really good at [stowing away](_URL_23_) on space craft. When microbes are stressed they can produce endospores\\*\\*,\\*\\* that allow them to survive the extreme conditions of space \\(massive temperature fluxes, low pressure, low nutrients, high radiation\\). We also know microbes survive on the [outside](_URL_22_) of the space station. Also, microbes from Earth have been deliberately left on the outside and have [survived for up to 553 days !](_URL_19_). So space isn't as deadly as we imagine it to be, [at least for microbes.](_URL_7_)\n\nFor the most recent Mars arrival, the Mars Trace Gas Orbiter \\(And Schiaparelli lander\\), there's a lot of info on how they minimised contamination [here](_URL_17_).\n\nSo yes, it is possible that cells may reach these planets\n\n**If not could any of the bacteria be able to live in the harsh conditions of mars?**\n\nSee [here](_URL_9_) for modern Martian habitability. This is one of the fundamental questions of Astrobiological research.\n\nThere isn't an obvious answer to this one as there are many factors.\n\nYour question is referring to **Forward Contamination**, meaning the risk of missions taking Earth Microbes to Mars. Despite the super strict cleaning protocols and rigorous mission design, there is still a risk that a microbe may reach the surface of Mars. However, once its there its problems have only just begun. Conditions on Mars are pretty tough. The main problem for microbes is the [UV radiation](_URL_6_). Simulation studies have shown that 99.9 & #37; of populations would be inactivated within a few seconds on Mars, and that within 1 day surfaces will be completely sterile\\([6](_URL_18_),[7](_URL_2_)\\).\n\nHaving said that, we know microbes are tough and there is always a risk that we don't know enough about the survivability of microbes to be sure we wont contaminate Mars. If microbes were to enter the soil, it is likely that they may be preserved from the sterilising UV radiation, \\(below the top few mm\\), and many simulation studies show microbes may survive within the soil \\([7](_URL_21_), [8](_URL_24_), [9](_URL_5_)\\).\n\nPotentially habitable regions of Mars are called **Special regions** and missions are currently prohibited from going near these regions. These regions include environments where liquid water exists and may have existed within the last 500 years [\\(10\\)](_URL_1_).\n\nIf microbes piggy backed on a rover to Mars, it is likely that the contamination would be localised to the rover and the rover would be sterilised pretty soon after landing. Sending microbes to Mars, in itself, isn't a bad thing. We just need to be sure they dont make it to the areas we know are habitable.\n\nSome may survive, but to actually be active they require habitable conditions and need to be removed from the harsh radiation environment.\n\n**And how do they obtain soil samples looking for bacteria if it could possibly be from the rover itself?**\n\nSo this is why its vitally important we do not forward contaminate Mars. An important thing to note is the majority of science is aimed at looking at evidence for past life. We know Mars was wet, warmer and had an atmosphere in its past and its much easier to identify biosignatures \\(whifs of life\\) than it is to identify something that is living, at least if we are doing it remotely.\n\nThe real question \\(as you have highlighted\\) would be is it definitely **not** Earth life. This is much harder and requires a rigorous methodology.\n\nOne way would be to identify [isotopic signatures](_URL_10_) \\(different 'versions' of the same element\\) that we find in preserved material or in potentially living materials. For example, say that we have a bunch of cells, we could see what the isotopic signature of the biomass was. This biomass would be built of either Martian elements or Earth elements \\- which each have different isotopic signatures. However, to be accurate, we would need to analyse it on Earth.\n\nIn my mind, the simplest way would be to get genetic info on the microbe. If we managed to get genetic info on the Martian microbe, it would be pretty easy to tell whether it was related to Earth life or not. However there are complications. It is probable that Earth life may be quite similar to Martian life as Earth and Mars have exchanged material over their histories'\\([11](_URL_8_)\\).\n\nUltimately all the questions you are asking are the questions that hundreds of scientists are asking themselves daily, and ultimately there is more that we **don't know** than we know. So we need to be careful. Answering the most fundamental question of 'are we alone?' requires a rigorous methodology so that we can be sure of the answer and this means preventing any form of contamination.\n\n**Extra reading \\(Some behind paywalls\\):**\n\nAstrobiology Primer V2.0 \\- [_URL_14_](_URL_14_)\n\nPlanetary Protection \\- [_URL_16_](_URL_16_)\n\nNasa Office for Planetary Protection \\- [_URL_4_](_URL_13_)\n\nHabitability on Mars from a Microbial Point of View \\- [_URL_20_](_URL_20_)\n\nTrajectories of Martian Habitability \\- [_URL_0_](_URL_0_)",
"Am I the only one that thinks it would be way cooler to throw a \"bacteria bomb\" of stuff we think might survive there, and see what happened in a few decades? \n\nYea proof of life blah blah, I just think it would be neat.",
"I want to add to some of the other answers. NASA has a Planetary Protection Officer, yes. But if you ask the current one if there is life on Mars she says yes, because we put it there. The sterilization process wasn't always as good or as thorough as it is now, and even now its possible some gets through.\n\n"
]
} | [] | [] | [
[
"https://en.m.wikipedia.org/wiki/Tardigrade",
"marsmobile.jpl.nasa.gov",
"https://www.sciencealert.com/here-s-why-nasa-s-mars-rovers-are-banned-from-investigating-that-liquid-water",
"https://marsmobile.jpl.nasa.gov/msl/mission/technology/insituexploration/planetaryprotection/",
"sciencealert.com"
],
[],
[],
[],
[
"https://helix.northwestern.edu/article/origin-life-panspermia-theory"
],
[],
[
"https://en.m.wikipedia.org/wiki/Planetary_protection"
],
[],
[],
[],
[],
[
"https://planetaryprotection.nasa.gov/categories",
"https://planetaryprotection.nasa.gov/overview"
],
[],
[
"https://www.liebertpub.com/doi/pdf/10.1089/ast.2013.1106",
"https://www.liebertpub.com/doi/abs/10.1089/ast.2016.1472",
"https://link.springer.com/article/10.1007/BF00924210",
"http://www.sciencemag.org/news/2018/03/nasa-clean-room-contaminated-fungus",
"https://www.nap.edu/catalog/24809/the\\-goals\\-rationales\\-and\\-definition\\-of\\-planetary\\-protection\\-interim\\-report",
"http://aem.asm.org/content/12/3/215.short",
"http://www.sciencemag.org/news/2017/03/uv-light-could-easily-kill-microbial-stowaways-mars",
"https://en.wikipedia.org/wiki/List_of_microorganisms_tested_in_outer_space#cite_note-:0-1",
"https://www.astrobio.net/mars/earth-and-mars-may-have-shared-seeds-of-life/",
"https://en.wikipedia.org/wiki/Modern_Mars_habitability",
"https://en.wikipedia.org/wiki/Isotopic_signature",
"https://www.space.com/6136-mars-mission-contamination-big-concern.html",
"https://www.nature.com/news/2007/070903/full/news070903-5.html",
"https://www.nap.edu/catalog/24809/the-goals-rationales-and-definition-of-planetary-protection-interim-report",
"https://www.liebertpub.com/doi/full/10.1089/ast.2015.1460",
"https://en.wikipedia.org/wiki/Planetary_protection",
"https://mars.nasa.gov/msl/mission/technology/insituexploration/planetaryprotection/",
"http://exploration.esa.int/mars/57581-planetary-protection/",
"https://www.sciencedirect.com/science/article/pii/S0019103503002008",
"http://www.bbc.co.uk/news/science-environment-11039206",
"https://www.liebertpub.com/doi/abs/10.1089/ast.2013.1000",
"https://www.sciencedirect.com/science/article/pii/S0032063312002334",
"https://www.sciencealert.com/living-bacteria-from-outer-space-found-clinging-to-iss-alien-life",
"https://www.sciencealert.com/ultraviolet-light-could-be-what-protects-alien-life-from-earth-bacteria",
"https://www.sciencedirect.com/science/article/pii/0019103563900241"
],
[],
[]
] |
||
2lirdu | how is it the island of java can support it's 140+ million people in area the size of north carolina? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2lirdu/eli5_how_is_it_the_island_of_java_can_support_its/ | {
"a_id": [
"clv8szd",
"clvcqlb"
],
"score": [
12,
6
],
"text": [
"by depending on trade for food and other resources, and coping up with less personal space. there's still some farms and forests, but yeah its hard to get away from other people.\n\nthe total north carolina population is about 10 million? heck, Jakarta (the largest city in Java) alone has 20 million people...\nsource: i live there.",
"The answer here is slums. Slums allow a very large amount of people to live in a very small piece of land. Jakarta and other cities around Java have very large slums. Also, Indonesian mothers have families that are typically large as a result of cultural circumstances and they end up cramming one another into very small living quarters. Multiply this millions of times and you have Java. The fact is that 140 million Indonesians would not fit in Java if they decided to live like Americans, Canadians, or Australians. "
]
} | [] | [] | [
[],
[]
] |
||
5gl112 | Treatment of French colonies | I have a task in school to talk about how the french treated their colonies. I have found some information, but i would like to know more | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5gl112/treatment_of_french_colonies/ | {
"a_id": [
"dat313m"
],
"score": [
2
],
"text": [
"Hey there, AskHistorians allows homework questions, but other people can't do the work for you - for the way HW questions are treated on here see [the rules](_URL_0_) and [this roundtable discussion](_URL_1_). To boil it down, you have to show that you've done some work yourself and specify the question - where do you hit the wall when using your sources? Are you looking for better ones/ones specific to a certain angle? Is there one part of your research of which you'd like to know more about? Say what you know, try to narrow down your inquiry and someone knowledgeable might help you with that. Good luck!"
]
} | [] | [] | [
[
"https://www.reddit.com/r/AskHistorians/wiki/rules#wiki_homework",
"https://www.reddit.com/r/AskHistorians/comments/4cb022/rules_roundtable_8_the_raskhistorians_homework/"
]
] |
|
64b3r5 | why is chemotherapy used the way it is? | As a general treatment of the body, rather than a local treatment of the area affected by the cancer? It just seems like if we are able to use anesthic locally, or generally, then why can't we choose to do the same with chemo? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/64b3r5/eli5_why_is_chemotherapy_used_the_way_it_is/ | {
"a_id": [
"dg0rj2e",
"dg0rqcx",
"dg10oyj",
"dg12k1v"
],
"score": [
3,
5,
2,
2
],
"text": [
"I think that is what radiotherapy is. Radiotherapy focuses on one spot but chemo kills cancer cells which are trying to spread. I could be wrong tho.",
"Chemo attempts to stop cells from dividing. Ideally the cells that stop dividing are targeted (hence the plethora of drugs for various cancers; different drugs = different targets) but because the chemistry is nowhere near an exact science, lots of other fast-dividing cells get hit too (hair, muscles, skin, white/red blood cells, etc). \n\nThe logic is that the cancer itself is a mutant, and won't survive more than 'a little while' without constantly dividing and replicating, so if you can specifically poison the body, stop cellular division for a while, and otherwise keep the person alive, the cancer will die off while (most of) the rest of the person stays alive.\n\nThink of it like having a castle full of people, and there was one group of particularly troublesome monks inside you wanted to kill off. The monks only ate apples, but your intel was shitty and you knew only that the monks ate sweet foods. You siege the castle and prevent anything sweet from getting in, sugar, fruits, plants...anything that contained or could become sugar. Many people develop scurvy and other malnutrition related problems and die off, but the monks all die too. You celebrate that the monks are dead, and get on living with whatever is left alive in the castle as the population slowly recovers.\n\nThe monks are cancer, the people are the healthy cells in the body, and everything else is the process of treating and living with the aftermath of cancer.",
"Chemotherapy can be given locally, this is sometimes done for example in the bladder for bladder cancer and by intra-arterial chemotherapy (TACE) for liver metastasis. However many times metastases are not in one place and you want to treat every metastasis, even if it is too small to be detected, and therefore systemic administration is more beneficial.",
"Cancer is particularly nasty because of its ability to metastasize. If you remove a cancerous tumor from someone there's no guarantee that you got all of the cancerous cells. Some may have escaped in to circulation and set up residence elsewhere in the body. Chemotherapy targets rapidly proliferating cells, as others have mentioned, and so it is useful to \"mop up\" these rogue cells.\n\n"
]
} | [] | [] | [
[],
[],
[],
[]
] |
|
3iho7w | Where does the church's money come from? | I understand that in the past things were different, but nowadays the roman catholic church is far from its days of glory, still it manages to fund every church around the continent? Donations can´t suffice I mean... | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3iho7w/where_does_the_churchs_money_come_from/ | {
"a_id": [
"cugmmwf"
],
"score": [
2
],
"text": [
"This goes well within the 20 year rule, you may want to ask this on a religious oriented sub, such as /r/Catholicism or /r/Christianity.\n\nAs an aside, the church can have jobs outside just being a priest. I know my local pastor is also a successful doctor, and a local brotherhood prints and publishes books, though they still use lots of donations."
]
} | [] | [] | [
[]
] |
|
6dp3y9 | what causes the cloud rings to form around and above a nuclear or thermonuclear bomb? | Example of [high-yield fusion Castle Bravo shot](_URL_0_) with rings. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6dp3y9/eli5_what_causes_the_cloud_rings_to_form_around/ | {
"a_id": [
"di4bnyl"
],
"score": [
5
],
"text": [
"The immense force of the blast creates a wave of high pressure in the air, traveling outwards from the centre.\n\nFollowing this high pressure is an area of extreme low pressure, this low pressure causes a drastic temperature drop.\n\nDropping temperature results in water in the air condensing, causing the ring of \"cloud\" that you see."
]
} | [] | [
"https://www.youtube.com/watch?v=T2I66dHbSRA"
] | [
[]
] |
|
1nreak | How did "x" become the conventional, go-to variable? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1nreak/how_did_x_become_the_conventional_goto_variable/ | {
"a_id": [
"ccldrty"
],
"score": [
32
],
"text": [
" > You'll find details on this point (and precise references) in Cajori's History mathematical notations, 340. He credits Descartes in his La Géometrie for the introduction of x, y and z (and more generally, usefully and interestingly, for the use of the first letters of the alphabet for known quantities and the last letters for the unknown quantities) He notes that Descartes used the notation considerably earlier: the book was published in 1637, yet in 1629 he was already using x as an unknown (although in the same place y is a known quantity...); also, he used the notation in manuscripts dated earlier than the book by years.\n\n_URL_3_\n\nThe book\n_URL_2_\n\nAlso check out\n _URL_4_ Earliest Uses of Various Mathematical Symbols\n\nParticularly\n_URL_0_ \n Earliest Uses of Symbols for Variables\n\n\nAnd _URL_1_\nEarliest Known Uses of\nSome of the Words of Mathematics\n\n\nSorry if answer is brief/badly formatted, I'm on my phone. "
]
} | [] | [] | [
[
"http://jeff560.tripod.com/variables.html",
"http://jeff560.tripod.com/mathword.html",
"http://archive.org/details/historyofmathema031756mbp",
"http://mathoverflow.net/questions/30307/explanation-why-x-y-z-are-always-variables/30414#30414",
"http://jeff560.tripod.com/mathsym.html"
]
] |
||
qr5s2 | Question about tooth decay and evolution. | Did humans get cavities before inventions like refined sugars? Were our teeth designed to last a lifetime without brushing and cleaning? | askscience | http://www.reddit.com/r/askscience/comments/qr5s2/question_about_tooth_decay_and_evolution/ | {
"a_id": [
"c3zs26x",
"c3zs5f4",
"c3zsn9n"
],
"score": [
2,
2,
2
],
"text": [
"Yes, we got cavities. Go google image some pics of old skulls.",
"I don't have the study in front of me, but I remember learning in college that the native Ohio river valley people had a much lower incidence of cavities during their lives as hunter-gatherers, however once they began agriculture the researchers found an enormous jump in the number of cavities due to the increase in starch and sugars in their diet.\n\nYou also have to remember the life expectancy of someone back in those days was early 40's - so a life time without brushing isn't that long compared to today.",
"I agree with Jedu. I have always wondered about this myself, but now i realize that our modern diet is most definitely the cause of cavities. Like Sid says, there probably where instances of cavities, but the advent of agriculture greatly increased their occurrence. Oh, a comment on the way you phrased your question. Be careful when you use the word designed. Evolutionary, nothing is designed. Evolution is not a linear progressive process like many people might believe. Some times we trick ourselves into thinking how great and awesome the human body is, but the reality of it is that we are not perfect."
]
} | [] | [] | [
[],
[],
[]
] |
|
2qjyz2 | (Math) Do we know everything there is to know about math? Or are there new discoveries being made in mathematics? | Do we know everything there is to know about math? Or are there new discoveries being made in mathematics? If so, what are they?
| askscience | http://www.reddit.com/r/askscience/comments/2qjyz2/math_do_we_know_everything_there_is_to_know_about/ | {
"a_id": [
"cn6s5vj",
"cn6smen",
"cn6v0ab",
"cn6v16u",
"cn6v184",
"cn6v4r1",
"cn6v5bx",
"cn6v65a",
"cn6vw4r",
"cn6xk7y",
"cn6yqac",
"cn6yqnw",
"cn6yu7v",
"cn6yvok",
"cn6yz3i",
"cn6z1on",
"cn70aoh",
"cn71a54",
"cn745h0",
"cn74x6e",
"cn75hjk",
"cn75odj",
"cn76tg8",
"cn7750y",
"cn77gbf",
"cn77qea",
"cn78qdp",
"cn79q6u",
"cn83g0v"
],
"score": [
1473,
404,
24,
10,
3,
102,
441,
14,
192,
55,
5,
28,
26,
2,
16,
8,
4,
4,
2,
3,
5,
2,
3,
3,
4,
3,
4,
3,
2
],
"text": [
"No, we don't know everything there is to know.\n\nOne good way of getting a quick view of recent advancements in mathematics is to read the list of winners of the [Fields Medal](_URL_1_) and the [Abel Prize](_URL_4_), paying attention to the citations. In general, though, recent advancements in mathematics are very difficult to understand for the layman, and I can't possibly hope to go into every one of them for you (for lack of both time and knowledge).\n\nSome very famous recent proofs of statements that are not so difficult to understand (although the proofs certainly are) were those of [Fermat's last theorem](_URL_3_), the [Poincaré conjecture](_URL_0_) and recent work on the [Twin prime conjecture](_URL_2_).",
"Wikipedia has a list of unsolved math problems. The Millennium prize was instituted in 2000--it offers a million US dollars to anyone solving any one of 7 longstanding problems identified by the Clay institute. Only one of the 7 has been solved since the prize was instituted. The following list from Wikipedia includes those as well as many others that mathematicians are trying to solve. \n\nNew problems arise as new developments in math and physics open up new directions to explore.\n\n_URL_0_",
"One problem yet to be solved is finding a rapid way to factor a large semiprime number. \n\nTwo prime numbers multiplied together makes a semiprime number. Multiplying two large primes is an easy task for a computer. Doing the reverse--taking an unknown large semiprime and figuring out what the prime numbers are--takes a very, very, VERY long time. \n\nFiguring out how to factor a large semiprimes quickly would play havoc with many forms of computer cryptography that depend on semiprime numbers being difficult to factor.\n\nEdit: used 'semiprimes' where I meant 'primes'",
"We absolutely don't know everything there is to know about math. There are still many great mysteries, and progress is being done on them all the time.\n\nWikipedia keeps some (fairly up-to-date) lists of major unsolved mathematical problems here:\n\n_URL_1_\n\n_URL_0_\n\nJust a few days ago, it was announced that a new theorem had been found about the spacing of prime numbers:\n\n_URL_2_",
"I think this question tickles the argument whether math is something to be discovered or invented. \n\nIf you're like me and believe it to be an invention, a tool humans develop to explain the universe around them, then math will continue to grow, to be invented, as long as there is still more to know about the universe.",
" > Do we know everything there is to know about math?\n\nMy goodness, no.\n\n > Or are there new discoveries being made in mathematics?\n\nHundreds of new discoveries, every day.\n\nThose math professors we all had in college generally have, as part of their job, doing research. That means they publish a couple of papers (or more) each year in research journals. The great majority of such papers are discussions of new discoveries. Multiply that by the number of math professors in the world, and then add the researchers employed by businesses (e.g., [Microsoft Research](_URL_2_)) and governments (e.g., the [NSA](_URL_1_)), along with people who just like to do math, and you get an awful lot of activity.\n\nNow, the vast majority of those new discoveries are both relatively minor and very difficult for someone outside the speciality to understand (even other mathematicians). So you won't be hearing about them.\n\nBut advances that have a noticeable impact on everyday life do come now & then. An obvious example is the encryption used on the Internet, without which sites like _URL_0_ would be impossible. This is based on mathematics that was unknown before the 1970s.\n\nIt's mostly behind-the-scenes stuff, though. For example, there is a lot of work being done in large-scale mathematical modelling. This is what makes possible modern airplanes, bridges, etc., which are all extensively modeled on computers before any physical object is built.",
"One reason people think that mathematics is \"done\" is because they aren't really exposed to much mathematics in high school that was developed later than the 1700s (if they even took calculus; if not, most of the arithmetic and geometry you learn is from no later than the 1500s). There are some exceptions to this, like matrices, but it's mostly true, especially compared to the amount of semi-recent (19th-20th century) chemistry, physics, and biology we're exposed to in high school. Think about how much science and technology have advanced since the 1700s. Mathematics has been advancing at exactly the same accelerating rate along with them. ",
" To piggyback off the OP...\n\nIs there a chance that a new branch of mathematics ever being developed like Calculus was? Or has there been new ones, but they are just so out there that the layperson would never remotely have a chance to encounter them? ",
"We know so incomprehensibly little about mathematics. We exist in a tiny island of light surrounded by a vast, dark sea of ignorance. Even a little intellectual exploration quickly uncovers problems that are far beyond our scope of reasoning.\n\nFor example, we do not know how many games of solitaire are winnable. We can use computer simulation to establish an upper and lower bound but we don't have close to the analytical tools necessary to even begin to approach an exact answer. It's been dubbed [\" one of the embarrassments of applied mathematics that we cannot determine the odds\nof winning the common game of solitaire\"](_URL_0_).\n\nSimilar, trivial examples exist all around us.",
"This is one of the most common misconceptions about math, that everything has already been discovered. Not by a long shot. The most painful example of this error to me was when a coworker, discovering I was a math major, asked, \"So what do you research? Like, a million times a million?\". > . < ",
"That is what being a mathematician is, a person who sits at the boundary of the world's knowledge and the unknown and spends their lives trying to take on the unknown. Whenever you see an academic paper in math published that is the authors implying, \"I found something that I think the rest of you haven't thought about yet.\" These papers are being published at an alarmingly high accelerating rate over the last decades. \n\nNot only do we not know everything about math, but math is so diverse and vast that even undergraduates pursuing degrees in math are publishing results. For example, even in my undergrad I spent a summer doing research under a professor in a branch of math called Combinatorics and I am one of the people published in these [collection of articles.](_URL_0_)",
"A lot of the posts here a referring to major discoveries. I just wanted to throw in some of the day to day advancements. There are rapid advancements in subfields of mathematics. Topology and nonlinear dynamics are the two I am most familiar with. In biology, modeling protein structures based on chemical properties is a major challenge. It's not just about computing power, it's about how sub structures can be pieced together. In nonlinear dynamics (my field) we're looking for better ways to find order in seemingly chaotic systems. My focus is how proteins carry messages from outside the cell to the genes and back again. We're working with old equations and anyone that can come up with better ones is going to make curing genetic diseases lots more likely.",
"If we knew everything there is to know about math (which is impossible), then nobody would be getting PhDs in math. This would be bad for me, since that's what I'm aiming to do right now.\n\nSo little math is exposed to the average person, most people associate math with arithmetic (adding and subtracting) and maybe a little elementary algebra (solve for x), and have no idea that math is an incredibly expansive and diverse field. Much of it unrecognizable to Joe Average as even being math.",
"One important thing to bear in mind is that the boundary between maths and physics is incredibly blurred, and has been for a very long time. Important developments in maths will have consequences in physics, and vice versa. I'm doing a PhD in a maths department doing pen and paper msths (as opposed to simulation), but my work is all motivated by problems in materials science, to the point I've attended conferences where all the speakers are experimental scientists. So if all of maths were to be completely understood then our understanding of the physical world would be far more complete than it is now.",
"Not only are there things we don't know, but there are also things we can't know. Whitehead & Russell set out to enumerate all possible mathematical proofs with their Principia Mathematica, and the response to it by Godel (the Incompleteness Theorem) conclusively proved that their efforts would be in vain.\n\nIntereresting side note: the fall-out from Godel's theorem eventually lead to the formal development of Computer Science (itself an offshoot branch of mathematics) by Church and Turing.",
"There are plenty of new things being done all the time! And there are still plenty of things that remain unknown, or unsolved. Look into the millennium problems. They are a series of problems in mathematics that remain unproven/unsolved but are so important that there is a million dollar prize for anyone who can solve them! \n\nMathematics is so rich. Its an artform, with active research and new questions being asked every day. Its sad, because so many think that math is just the manipulation of numbers, and that problem comes from how math is taught to us at a young age. We are taught that math is a strict rigid process, which leads us to believe that math must be complete. But this isn't true. Math is the ultimate medium of art and creativity. There is so much math that humans have mastered, so much that It would take more than a life time to learn it all... but there is still so much that is left unanswered. And that is the thrill of it all. I mean the millennium problems is a great place to look, because its a pretty good representation of the kinds of stuff we don't know... but there is far more to it than that. \n\nI'm a bit of a math nerd (Mathematical Physics major)... so if youve got any further questions I'd be happy to help! ",
"In the words of David Hilbert (one of the greatest mathematicians of the last century):\n\n\"The supply of problems in mathematics is inexhaustible, and as soon as one problem is solved numerous others come forth in its place.\"\n\nNot only have we not learnt all there is to know, we never will. It's not like physics where you could have a theory of everything.",
"I prescribe to the idea that math is not an entity but a language, so technically its whole exists in the realms of human knowledge, but it is continuously growing with human knowledge. So basically we know everything that is math right now, but not everything it could be, similar to how we know every play, novel, song, ect. that is in our libraries, but will never know every literary work that was or will ever be created or could be created. ",
"The guy who made Futurama literally created a new theorem just for the plot of an episode. It is real and checks out. It is called the Futurama Theorem. That should answer your question. Think long and hard enough and you could probably write your own theorem too if you have a master's degree in in math, or just really like math.",
"I think the best answer (if you're still watching this thread) is this [interview of John Conway](_URL_0_).\n\nThis gives the impression that mathematics usually progresses slowly, and of course that can be backed up with examples (some of which are included in the video).",
"No, we do not know everything there is to know about math. \n\nMathematics is an infinite landscape, and presently we have only mapped out a finite portion of this landscape. There are still infinitely many discoveries to be made, presuming humanity does not self-destruct.\n\nTo give you a few examples, let me focus on two popular areas where large progress has been made in recent years: Number Theory and Mathematical Physics\n\nNumber Theory: This subject concerns the study of the prime numbers, i.e., 2,3,5,7,11, ... these numbers cannot be divided into smaller units. They are the integers which act as the atoms in mathematics. The twin prime conjecture, which is currently not known to be true or false, states that there will be infinitely many pairs of primes that differ only by two. Except for one example (2 and 3) it is not possible for a pair of distinct prime numbers to be any closer than two apart. Here are some twin prime pairs: (3,5), (5,7), (11,13). Thus, the twin prime conjecture stipulates that there are an infinite number of these prime pairs that are very close together. We do not currently know whether this conjecture is true or false. Many people believe it to be true, but for no good reason (just a guess, I believe). But, very recently, based on work of a a mathematician named Yitang Zhang, we now know that there are infinitely many prime pairs which are at most 246 apart. You might call these \"prime cousins\", because they aren't quite as close together as twins, but still...they're pretty close. And we know these pairs are infinite in number.\n\n\nMathematical Physics: A famous problem in Fluid Mechanics concerns the Navier-Stokes (NS) equations, which are classical mechanics equations that govern the dynamics of incompressible fluids such as water (or liquid hydrogen, say). These equations describe how a fluid will move, given knowledge of its initial velocity. That means, based on these equations, you can completely predict the future behavior of a fluid, as long as you know the velocity of each individual water particle at the initial time when you start the experiment. Now the question for the NS equations is whether it is possible for a mathematical fluid to BLOW UP in finite time. Such a fluid would behave very strangely. The fluid would start out moving about in a very smooth way. At some later time, though, it would start to accelerate and rotate about itself very fast forming a vortex, similar to what is seen when you flush the toilet. This vortex would rotate faster and faster, eventually attaining an infinite velocity near its center, after a finite amount of time has passed. This hypothetical behavior is called a BLOW UP solution. No living person has ever designed a fluid with this behavior and it is a major open problem to prove or disprove that such a behavior is possible. Basically, if such fluids can be constructed, then we would know in some sense that the equations that govern fluids are not the correct equations to model nature, because such BLOW-UP behavior is not natural. We would need to start over and look for a more accurate set of equations to model nature. Now, unlike with the primes problem described above, most mathematicians have NO IDEA whether the NS equations can blow up. But, in a very interesting recent preprint, Terence Tao (a Fields medalist) has shown that one can build a sort of \"computer\" using water. This \"computer\" transmits information using water and water alone, and has a preliminary form of Random Access memory. We believe that this \"water computer\" might be useful for constructing a blow-up scenario. Roughly speaking one might somehow \"program\" the water to cause itself to self-destruct. This line of research is at a very preliminary stage, so it's hard to say anything definitive. But this new idea sounds cool to say the least and it gives some sense of what mathematicians think about.\n\nEdit: Updated the recent partial work on \"twin primes\" to give the more accurate number 246 for the best known gap.\n\nEdit 2: Updated a bit of the description of the NS equations.\n\nEdit 3: Another small update to NS equations. Fixed some typos too.",
"Many of the security and crypto algorithms are built on fact we dont have a simple solution to simple mathematical problems. ex: prime numbers, computation of prime factors of very large numbers (used in RSA). Solving some of these problems would mean there is requirement of advancement in computer engineering aswell which would outdate a lot of existing technologies depending on these.",
"I feel that asking this question is akin to asking a little tiny fish if it has seen the entire ocean. Assuming of course fish could talk.\n\nOur concept of what we know and what we don't know is never whole. I believe that the discoveries in math and science will keep coming until our species dies out and even then we might not scratch the surface. And yet, what we know is so immensely vast already how can we not already be scratching the surface.\n\nAs long as there are questions unanswered in math or science, there will be new discoveries. As for what they are?\n\nI'm sure someone else could give you a more specific answer but they aren't discoveries for nothing. The possibilities are probably endless. I mean, they are called discoveries after all, how can we know until they are discovered and published.",
"It is *impossible* to prove everything there is to know about mathematics and the strangest part is the fact that this has been proven by the theorems that were proven by Kurt Gödel.\n\nBasically it comes down to this is layman's terms:\n\n1.). Assume you can come up with a consistent set of rules (axioms) from which you could derive all of mathatics. If yoy have such a set of rules, there is ALWAYS going to exist a statement that exists from which you could derive from your rules that IS TRUE, but can never be proven to be true. Furthermore, if you try to add another rule into your set of axioms to prove the statement true that you can't prove to be true (but which you know is true), youll just end up creating another set of axioms from which you could derive another statement that is true and unprovable. Examples of such statements many mathaticians believe may fall into this category are extremely hard proofs like goldbachs conjecture which is pretty much believed to be true by everyone but can't be proven.\n\n.2). Assume you have a system of axioms such that all statements that could be derived would be provable. Kurt Gödel proved that such a set of rules would always be inconsistent. For example you could always derive a set of statements in math that would be the equivalent of \"the following statement is true. The preceding sentence is false.\"\n\n\nIn summary, it is impossible to know everything about math, because if you do, there are statements that are true *which cannot be proven to be true*, itll literally require a leap of faith, OR you can prove everything to be true but your rules will have bugs in them which will make them inconsistent, mea ing there exists no perfect set of rules from which you can derive mathematical truths. \n\n\nSome philosphers will argue that Gödel's theorems prove that AI would be impossible, but generally just realize that the lines between truth, math, and philosophy start to blur big time the deeper down the rabbit hole you go.\n\n",
"probably a little late to the punch, bit this is just something to think about: math is the language of the universe. your answer can be found in coalesce with the answer to this question: have we discovered the entire universe? obviously, no. we haven't even discovered our entire planet yet, and there is math to be found even in that. beyond our planet, our knowledge of physics is still limited. there are anomalies like dark matter, dark energy, black holes, and likely many errors within our current theories as well. we would have to be in a very privileged position in human history to even be able to assume that we knew everything about it (a point in history that would come in the very distant future), and even if we did have such a wealth of mathematic knowledge, that doesn't stop the fact that life is always changing, and there is math that comes with the challenges life creates. ",
"A lot of people have a very limited idea about what mathematics is: usually the notions about math don't go beyond arithmetic. But math is this sprawling enterprise and we can create new systems of math and logic at will, to explore what sorts of relationships hold and what applications may spring forth. In short, we are still actively researching math; additionally, there is no way of knowing whether math is ever \"finished.\" ",
"Not only are there things we don't know, we know that there will always be things that we don't know. Godel's incompleteness theorem proves that for any non contradictory set of axioms that is sufficiently powerful, there will be some true statements that are not provable. ",
"Not at all. Look at Fermat's Last Theorem or research Mercene primes to see how esoteric of a field it is. Only problem is that *relatively* there's not as much applications, so you don't hear about it as much as engineering. Basically most of the mathematics people are exposed to is barely the 1500s discoveries",
"I just want to comment, as has been commented elsewhere here, that every reference made to Godel's Incompleteness Theorem in this thread misunderstands the theorem. Godel's Incompleteness Theorem is about finitely axiomatizable theories of Arithmetic, which are not identical to human knowledge or all of Mathematics. "
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Poincar%C3%A9_conjecture",
"http://en.wikipedia.org/wiki/Fields_Medal#Fields_medalists",
"http://en.wikipedia.org/wiki/Twin_prime",
"http://en.wikipedia.org/wiki/Fermat%27s_Last_Theorem",
"http://en.wikipedia.org/wiki/Abel_Prize#Laureates"
],
[
"http://en.wikipedia.org/wiki/List_of_unsolved_problems_in_mathematics"
],
[],
[
"http://en.wikipedia.org/wiki/List_of_unsolved_problems_in_computer_science",
"http://en.wikipedia.org/wiki/List_of_unsolved_problems_in_mathematics",
"http://www.wired.com/2014/12/mathematicians-make-major-discovery-prime-numbers/"
],
[],
[
"Amazon.com",
"https://www.nsa.gov/",
"http://research.microsoft.com/"
],
[],
[],
[
"http://statweb.stanford.edu/~cgates/PERSI/papers/solitaire.pdf"
],
[],
[
"http://www.hindawi.com/journals/isrn/contents/isrn.combinatorics/"
],
[],
[],
[],
[],
[],
[],
[],
[],
[
"http://youtu.be/xOCe5HUObD4"
],
[],
[],
[],
[],
[],
[],
[],
[],
[]
] |
|
fqn0o | Does every neuron contain every neurotransmitter? | I have a pretty basic understanding of how synaptic transmission works and all that, but I have always wondered this. Does every neuron have it all? Or do certain neurons only contain certain transmitters? | askscience | http://www.reddit.com/r/askscience/comments/fqn0o/does_every_neuron_contain_every_neurotransmitter/ | {
"a_id": [
"c1hwvxc",
"c1hx60u",
"c1hxc07"
],
"score": [
6,
2,
5
],
"text": [
"I can answer the following question: \"Does every neuron have the genetic capability to *create* every neurotransmitter?\" **Yes** (short answer). The two main excitatory and inhibitory neurotransmitters are glutamate and GABA, which are both derived from Amino acids. In fact, almost all neurotransmitters are either derivatives of amino acids, chains of amino acids, or products created by biological enzymes (which are, themselves, created from long chains of amino acids). Cells use DNA as a template for *which* amino acids they produce, in *what quantity* those AA's are produced, and in *what order* those AA's are combined. \n\nBut that does't mean that every neuron *does* contain every neurotransmitter. Neurons are effected in myriad ways by the outside environment, and these environmental interactions influence which genes are expressed by which cells. This mechanism is what allows different cells of the developing body to specialize—into skin cells, neurons, etc. Different neurons have different ways of expressing genes, so they act differently. Therefore, I'm pretty sure that different neurons (and especially different neuron *types*) have different concentrations of neurotransmitters. It all depends on gene expression.\n\nThat was the short answer. The long answer involves a more precise definition of what a \"neurotransmitter\" is, as opposed to a neuromodulator. But short answer, **no**. ",
"Different areas of the brain create different neurotransmitters. For example, serotonin and glutamic acid are released in the hippocamus, the center of your brain responsible for converting short term memory to long term.",
"Typically one \"classic neurotrasnmitter\" is made per cell type but [not always](_URL_0_). Neurons frequently also make neuropeptides that are released into the synapse but exert their effects in more persistent, subtle ways rather than by changing membrane potential instantaneously.\n\nYou can vastly oversimplify the mammalian brain in a very general way:\n\n* Most neurons are glutamatergic and exert an excitatory effect on neurons that synapse with them.\n\n* Additionally there are GABAergic inhibitory neurons that inhibit other neurons. These are less common.\n\n* Then there's everything else such as the catecholamine and monoamine systems. \n\nAs it turns out, many of these \"everything else\" neurons are made exclusively in one organ of the brain or just a few.\n\n=====\n\n**Going further:**\n\nWhile there is more complexity and detail to everything I've said above, you can build an approximation of the architecture of the brain with this: Glutamine- and GABAergic neurons make up microcircuits, these circuits frequently operate together to integrate information. These circuits in turn regulate each other and are in part governed by modulations from additional systems."
]
} | [] | [] | [
[],
[],
[
"http://en.wikipedia.org/wiki/Synaptic_transmission#Cotransmission"
]
] |
|
9m0xgn | Would a plant/crop grow faster if it had artificial sunlight and perfect conditions all the time? | Just curious since vertical farms might be a real thing in a few decades. So they can a building that has the perfect temperature, humidity/climate for a given crop.
So could having artificial sunlight shine on the crop all day everyday cause the plant to grow faster? Or is there a maximal a plant can grow in a year? Or do plants need rest? | askscience | https://www.reddit.com/r/askscience/comments/9m0xgn/would_a_plantcrop_grow_faster_if_it_had/ | {
"a_id": [
"e7cedql",
"e7ng8kq"
],
"score": [
3,
2
],
"text": [
"It is not so much 'growing faster' but 'just growing with minimum light'. \n\nA(not very satisfactory) explanation is [airmass](_URL_0_), if a plant grows during spring in the Nordic countries with (due to airmass) only 15% of available light, then on the same area in Southern countries you have enough sunlight for 6-7 stacked layers. \n\nIndoors means better control over humidity/pest-control, day/night-percentage, change between the blue and red percentages to favour leaf or flower growth, and probably temperature changes at the end of the growth cycle to modify sugar content. \n \n\n\n ",
"Depends on the plant or crop. Many species require dark and/or cold periods (i.e. night, winter) to regulate their growth cycles: they won't bloom unless day length varies throughout the year, and thus can't produce fruit or seeds.\n\nThat can be bred out, though. Modern marijuana cultivars actually *need* 24-hour daylight: they've been so heavily selected for high resin and THC production that they crank it out as if they're always in ideal light and water conditions. If they don't get enough light, either their drug production suffers or they do."
]
} | [] | [] | [
[
"https://en.wikipedia.org/wiki/Air_mass_%28solar_energy%29"
],
[]
] |
|
g3pjxv | what does hormones actually do to our brains, how it makes us think, and if we extract all the hormone and hormone producing glands will the person be dead or lose his ability to think and feel? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/g3pjxv/eli5_what_does_hormones_actually_do_to_our_brains/ | {
"a_id": [
"fnsnhy2"
],
"score": [
3
],
"text": [
"Hormones is a functional name for dozens of chemicals that serve as messengers between organs, and mediate physiological processes. They basically change what cells/tissues/organs do by changing the chemical environment in which said cells are. If you removed all glands, yes a person would die, probably in a diabetic coma from lack of insuline."
]
} | [] | [] | [
[]
] |
||
apx17e | could an organism living in the ocean at a pressure of 5 tons/in^2 survive a hit from a sledge hammer? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/apx17e/eli5_could_an_organism_living_in_the_ocean_at_a/ | {
"a_id": [
"egbr5j7",
"egbsjbj"
],
"score": [
2,
3
],
"text": [
"It would die. Constant even pressure from all sides is not the same as non-uniform pressure hitting you from one direction, which would splatter the poor thing in the other direction.",
"You have to remember that organisms living at the bottom of the ocean are filled with water. They aren't resisting 5 tons of pressure like a submarine would. The water inside their bodies is at the same pressure as the water outside their body. So, they don't feel the pressure at all."
]
} | [] | [] | [
[],
[]
] |
||
31xmlg | how do united states defence contractors make money when they are not needed? | I searched! Don't kill me!! :)
There aren't any major battles right now (that I know of), so what exactly do companies like General Dynamics do during these times? I would assume production of their vehicles and tanks, and planes, and missiles and everything that they produce is on hold. Its not like tanks and APVs are getting blow up constantly, and its not like you can go down to the General Dynamics dealership and purchase a used F-16 or M1, where do they make their money during times like this?
Thanks! | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/31xmlg/eli5_how_do_united_states_defence_contractors/ | {
"a_id": [
"cq5xjgp",
"cq5yemg",
"cq5zd2w"
],
"score": [
5,
3,
2
],
"text": [
"Many still have personnel overseas re-building infrastructure, training foreign and US troops, and cleaning up everything afterwards. Weapons and equipment are still used and destroyed in training (things wear out or break), even in peace time. Some of them sell to foreign governments. A few do environmental cleanups, demolish unused military sites, and return polluted parcels of land to other uses. Most, if not all, are diversified enough that they still make money in seemingly unrelated things. ",
"Congressman: Looks like this war is wrapping up, we can probably wind down that airplane contract.\nContractor: This war is almost over and you're still fighting with last war's planes, surely you don't want to fight the next war with the same planes too...we'd be happy to continue work on development of the next generation of fighter jet.\nConcerned Citizen: _URL_0_",
"General Dynamics, Lockheed Martin and other contractors have several business units. Some build planes or tanks or misses but others are for IT, Intelligence or other administrative services. They diversify across multiple contract vehicles so that there is a steady revenue stream. "
]
} | [] | [] | [
[],
[
"https://m.youtube.com/watch?v=4F4qzPbcFiA"
],
[]
] |
|
2s981m | Is there a 4 dimensional analog to a sphere like a tesseract is for a cube? | askscience | http://www.reddit.com/r/askscience/comments/2s981m/is_there_a_4_dimensional_analog_to_a_sphere_like/ | {
"a_id": [
"cnney27"
],
"score": [
39
],
"text": [
"Yes, the sphere *S*^(3), which is the *three-dimensional* sphere (embedded in Euclidean four-dimensional space), is the set of points (*x**_1_*, *x**_2_*, *x**_3_*, *x**_4_*) such that\n\n*x**_1_*^2 + *x**_2_*^2 + *x**_3_*^2 + *x**_4_*^2 = 1\n\nSimilarly for higher number of dimensions."
]
} | [] | [] | [
[]
] |
||
t1u3v | As an international programmer, how do you deal with using computer science in languages from different countries? | askscience | http://www.reddit.com/r/askscience/comments/t1u3v/as_an_international_programmer_how_do_you_deal/ | {
"a_id": [
"c4itf6c"
],
"score": [
3
],
"text": [
"I am an American working for a Japanese astronomical observatory in Hawaii.\n\nAll code is in English (mostly C, Python, Java, some C++ and some Objective C). Documentation around the code may be in english or japanese. Stand-alone documentation is often in japanese only (depending on the author)."
]
} | [] | [] | [
[]
] |
||
317u8h | What would a gas giant look like from within? | Intense radiation, pressure, and winds and whatnot aside, just curious what this would be like. What would it look like? How far does light penetrate? | askscience | http://www.reddit.com/r/askscience/comments/317u8h/what_would_a_gas_giant_look_like_from_within/ | {
"a_id": [
"cq06fu7"
],
"score": [
2
],
"text": [
"\"About 500 kilometers over the dense cloud cover, we enter Jupiter’s troposphere, and keep diving. This “haze” area is filled with all kinds of odd compounds, most interestingly hydrazine and the increasingly important polycyclic aromatic hydrocarbons created by UV-blasting of methane that circulates out too far from cloud-cover. Visibility drops off dramatically until we begin to descend into the clouds themselves — then it’s basically zero.\"\n\nFrom _URL_0_\n\nAlso,\n_URL_1_\n\nIf you're into this kind of stuff, you should read Sagan's *Cosmos*."
]
} | [] | [] | [
[
"http://www.geek.com/news/what-would-it-be-like-to-stand-on-jupiter-1599006/",
"http://www.universetoday.com/113106/whats-inside-jupiter/"
]
] |
|
45sbv3 | are the black panthers a racist hate group? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/45sbv3/eli5_are_the_black_panthers_a_racist_hate_group/ | {
"a_id": [
"czzt5zy",
"czztalt",
"czztotl"
],
"score": [
2,
5,
2
],
"text": [
"That's gonna be a touchy subject and one just asking for a Reddit War. However, here is the wiki on them _URL_0_ and you make your own conclusions. Remember that when they were active it was a very different time for African Americans and they were quick to be demonized. For the record, I have no opinion on them either way.",
"The Black Panthers started as a community activist group meant to protect the Black community. You gotta remember that during that time period, law enforcement's idea of \"due process\" in a lot of places consisted of rounding up the nearest black guy and beating him until he confessed to whatever you needed. So, the BP formed to protect the black community from abuse. This protection often included armed patrols in black communities that were needed to protect innocent black folk from police. In their early days, they did a lot of positive organizing, including many social programs such as community health clinics.\n\nOver time, the group became more radical, more isolated, and several leaders turned to criminal activities to fund their activities or just line their own pockets. \n\nSo, it depends on what you're remembering. Most people who aren't black remember the crime, the corruption, and the violence. But many who are black remember that, at a time when law enforcement and many in the government were committed to victimizing the community, the Black Panthers were ready to stand up and fight back. ",
"The easiest way to describe it is that the KKK is an anti-black group, with its primary goal being the punishment of black people. The Black Panthers weren't anti-white, they were pro-black. They worked to protect and help black communities suffering from racism. They used the threat of violence to make it clear that attacking black people was no longer acceptable. But their primary actions included ensuring that poor black families were fed, serving as neighborhood watch, they protested. \n\nBut they were armed black men, and that scared people. And yes, the Black Panthers did attack white people on occasion. But it wasn't their primary goal. "
]
} | [] | [] | [
[
"https://en.wikipedia.org/wiki/Black_Panther_Party"
],
[],
[]
] |
||
l2jh9 | nominalism | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/l2jh9/eli5_nominalism/ | {
"a_id": [
"c2pd3ed",
"c2pd3ed"
],
"score": [
2,
2
],
"text": [
"4 upvotes and no comments, wtf?!?!?",
"4 upvotes and no comments, wtf?!?!?"
]
} | [] | [] | [
[],
[]
] |
||
ngcdz | Is it correct (Scientifically) to refer to Humans as Omnivores? | Not all of us eat meat, not all of us eat plants and some of us enjoy both. We've got a couple of sharp teeth for tearing meat (I assume) and some flat ones for chewing greens (I assume).
Whats the verdict askscience?? | askscience | http://www.reddit.com/r/askscience/comments/ngcdz/is_it_correct_scientifically_to_refer_to_humans/ | {
"a_id": [
"c38vm9s",
"c38wgsm",
"c38vm9s",
"c38wgsm"
],
"score": [
6,
5,
6,
5
],
"text": [
"We are omnivores by design, even if we arent all by habit. Same way that someone with backwards sleep habits would not put our status as diurnal as any different.",
"Evolutionarily speaking, we are omnivores. Biochemically, we have the means of obtaining nutrients from both plant and animal matter. Culturally, or by habit as IamPolaris_247 says, it doesn't means we HAVE to eat both, but we certainly are capable of it. ",
"We are omnivores by design, even if we arent all by habit. Same way that someone with backwards sleep habits would not put our status as diurnal as any different.",
"Evolutionarily speaking, we are omnivores. Biochemically, we have the means of obtaining nutrients from both plant and animal matter. Culturally, or by habit as IamPolaris_247 says, it doesn't means we HAVE to eat both, but we certainly are capable of it. "
]
} | [] | [] | [
[],
[],
[],
[]
] |
|
6mm2ny | What are these straight line formations in the middle of Australia and what caused them? | [This](_URL_1_) is the phenomenon I'm referring to.
The very weird straight drainage patterns it results in can clearly be seen on the [beautiful map](_URL_2_) of the continent's river basins seen on [this reddit post](_URL_0_), which led me to ask the question.
Is this natural? How did it occur? Why is it unique to that area in Australia? Does a similar phenomenon occur elsewhere on Earth?
| askscience | https://www.reddit.com/r/askscience/comments/6mm2ny/what_are_these_straight_line_formations_in_the/ | {
"a_id": [
"dk2mlwz",
"dk2nxiz"
],
"score": [
10,
26
],
"text": [
"**EDIT:** It appears, as pointed out by /u/eliminate1337, these are related to linear dunes in the Simpson Desert [(e.g. this paper discussing the formation and migration of said dunes)](_URL_1_). I've (1) seen so many similar questions about 'weird straight rivers' in various subs and (2) encountered this error in flow routing so many times processing my own data I defaulted to that as the reason. I've left my original answer for posterity as virtually any other time you encounter a similar map of colored river basins and wonder why there are odd linear features, either below is the answer or it's likely related to ['trellis drainage' patterns](_URL_0_) that result from the interaction of a river network with areas of deformed units with contrasting erodibilities.\n\nIt's a data artifact. This (and the myriad of similar maps that periodically appear on subs like /r/MapPorn or /r/dataisbeautiful) is not a map of actual rivers, but rather the result of running a flow routing algorithm on an elevation dataset (i.e. for any given pixel in a gridded dataset determining which pixel(s) are downstream of that pixel), then accumulating 'flow' (i.e. for any given pixel, summing the number of pixels that would contribute water to that pixel), and then thresholding that accumulation map (i.e. defining that any pixel that receives flow from greater than X number of pixels is a river). There are lots of different flow routing algorithms, the most common is [D8](_URL_2_) which contributes all flow from a pixel to the pixel in the 8-connected neighborhood around that pixel that has the steepest descent (i.e. is the lowest with respect to the pixel in question). Flow routing algorithms (and this is especially true for D8) do weird things in flat areas that don't actually have any clear path of steepest descent. This is often further exacerbated by a pre-processing step that happens usually referred to as 'sink filling', basically identifying local little pits that would trap flow and filling them up to the average elevation of the pixels surrounding it. Because these algorithms are also imposing hydrological connectivity (i.e. pixels that are not on the edge of the dataset or explicitly defined as the end of a flow network have to flow into another pixel) when it tries to figure out what is upstream or downstream in a totally flat area, it produces straight lines between areas that are actually channelized / actually have a path of steepest descent. What you usually want to do is mask out (i.e. set the pixels to something identifiable like 'NaN') areas of internal drainage (e.g. lakes, salt flats, etc etc) to avoid producing these artifacts. Sure enough, if you look at an [elevation map of Australia](_URL_3_), the location of the weird straight lines it the super flat Simpson desert.",
"I believe the other answer is incorrect. The algorithm is getting it right. [Simpson Desert](_URL_0_), the location of the straight lines, has very long parallel sand dunes up to 200 km long. They're up to 30 m tall, so a detailed elevation map is likely to have captured them.\n\nThe algorithm is showing where water would be flowing if there was any to speak of. It would flow through the valleys between the sand dunes. "
]
} | [] | [
"https://www.reddit.com/r/Map_Porn/comments/6m1zzs/river_basins_of_australia_in_rainbow_colours_3686/",
"https://www.google.com/maps/place/Australia/@-24.7934378,136.982672,71440m/data=!3m1!1e3!4m5!3m4!1s0x2b2bfd076787c5df:0x538267a1955b1352!8m2!3d-25.274398!4d133.775136",
"http://i.imgur.com/KOY6jss.jpg"
] | [
[
"http://edtech.mit.edu/fcgi-bin/pgt?part=1.5.1",
"http://onlinelibrary.wiley.com/doi/10.1002/2015JE004892/pdf",
"http://pro.arcgis.com/en/pro-app/tool-reference/spatial-analyst/how-flow-direction-works.htm",
"http://www.nationsonline.org/maps/australia-topographic-map.jpg"
],
[
"https://en.wikipedia.org/wiki/Simpson_Desert"
]
] |
|
1me92i | what exactly is a time share? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1me92i/eli5_what_exactly_is_a_time_share/ | {
"a_id": [
"cc8d2ug"
],
"score": [
2
],
"text": [
"It's partial ownership in a property. In a simple example, you and 25 other people would get together to buy something very expensive, like a condo that would cost millions of dollars. Then you all agree to each spend two weeks per year in the condo.\n\nThe problem with timeshares is they are almost always run by predatory management companies who have no interest but to squeeze as much money out of the tenants as possible. The industry is rife with scam artists."
]
} | [] | [] | [
[]
] |
||
1lhg87 | If dreams are memory solidification processes; What are nightmares? | From what I understand, dreams are the loose association process needed for short term memory from the day to turn into long term memory.
If this is so, or even if we don't presuppose this position, What are nightmares? What, if any, are the evolutionary benefits of them? | askscience | http://www.reddit.com/r/askscience/comments/1lhg87/if_dreams_are_memory_solidification_processes/ | {
"a_id": [
"cbzcmcy"
],
"score": [
16
],
"text": [
" > From what I understand, dreams are the loose association process needed for short term memory from the day to turn into long term memory.\n\nThis is not known to be true. Right now, we don't know what dreams are, nor what is the benefit in having them, if any.\n\nWe know that there are a number of important cognitive and physiological processes going on in the brain during sleep, including \n\n* [consolidation of particular memories](_URL_1_)\n\n* [incorporation of new memories and ideas into a broader conceptual understanding](_URL_4_)\n\n* [processing of emotional experiences](_URL_0_)\n\n* [pruning of synapses](_URL_2_)\n\n* [restoration of neuronal ATP stores](_URL_3_)\n\nThe best hypothesis we have at the moment is that dreams are probably just a conscious playback of the sleep-related tasks the brain is conducting. \n\nDreams are particularly vivid and particularly common in REM sleep, during which time brain activity is quite similar to wakefulness. It has therefore been suggested that REM sleep (and potentially the associated dreams) may represent an offline simulation of a wake-like state, allowing the brain to possibly explore new scenarios or ideas. You should note the number of qualifiers I used in that sentence. It is easy to come up with plausible-sounding hypotheses on this topic, but extremely difficult to test any of them in any meaningful way.\n\nThere is some experimental evidence that REM and NREM sleep may have different individual roles in the processing and consolidation of memories. However, that evidence is not yet strong, for the simple reason that it is difficult to experimentally manipulate the specific stages of sleep without having other effects. \n\nIt is easy to perform experiments in which people either sleep, don't sleep at all, or don't sleep enough, and these consistently show that sleep has an important role in memory processing. But it is almost impossible to perform an experiment in which you selectively manipulate just the amount of REM or NREM sleep somebody gets, because these stages usually occur in stereotypical sequence. If you mess with one stage, you necessarily mess with the entire architecture of sleep, and then it is no longer clear what aspect of the experimental manipulation caused the effect.\n\nMost studies that have linked REM sleep or NREM sleep to specific types of memory processing in humans have therefore been correlational. By that I mean they study a group of participants, and find that say those with more REM sleep on the study night performed better the next day than those with less REM sleep on the study night. That does not prove a causal link.\n\nMoreover, NREM sleep and the slow waves that occur in the brain during NREM sleep have been found to play very important roles in memory processing and consolidation during sleep, despite the fact that dreams are most commonly associated with REM sleep. Dreams do occur in NREM sleep, but they are less common and typically less vivid. It is therefore a gross error to simply equate dreams to the memory consolidation processes that occur during sleep."
]
} | [] | [] | [
[
"http://psycnet.apa.org/journals/bul/135/5/731/",
"http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824214/",
"http://www.jneurosci.org/content/30/25/8671.short",
"http://www.jneurosci.org/content/30/26/9007.short",
"http://www.ncbi.nlm.nih.gov/pubmed/21075233"
]
] |
|
2gomha | How often do electrons move energy levels? | I understand the basics of it. But what's the deciding factor in what energy level they move down to. The emissions spectrum we can see is when electrons drop to n=2 - but why does this happen in hydrogen when there is only one electron? Surely it would just drop down from wherever it was to n=1? And does it drop straight down from, say n=3 to n=1 or does it go n=3 - n=2 - n=1? Or can they go n=2 to n=3 to n=1 to n=4? I haven't been able to find an answer to this yet, I hope someone can help. It's just a little part that I don't quite get. | askscience | http://www.reddit.com/r/askscience/comments/2gomha/how_often_do_electrons_move_energy_levels/ | {
"a_id": [
"ckl4y4z",
"ckl4zkz"
],
"score": [
3,
3
],
"text": [
"This is actually quite complicated. In short, it depends on the specific atom and how its electronic structure is. It is not possible to further understand this from Bohr's model which just considers the different energy levels n=1,2,3... as you described it.\n\nTo go into a little more detail: If you calculate the possible energy levels of electrons around an atomic nucleus using quantum mechanics, you end up with an incredibly high number. You can sort those levels using not only n, but also the three additional quantum numbers l, m and s. Each of these solutions is a possible wavefunction for an electron to have. The probability that an electron will \"jump\" from energy level x to level y depends on the overlap of these two wavefunctions. The greater the overlap, the more likely is the transition (absorption and emission have equal probabilities). There are many transitions that are not possible (\"forbidden\"), most often because there is a change in angular momentum greater than a single photon can carry or some other quantity is not preserved. The fancy term for these probabilities is Clebsch-Gordan coefficients, whether a transition is allowed is determined through so-called selection rules.\n\nIt's maybe worth noting that it's impossible to calculate the transition probabilities exactly for atoms that are not hydrogen, for all other atoms we have to use numerical methods and approximations.",
"This is determined by so-called [selection rules](_URL_0_) on electronic transitions. The idea is that when a transition occurs, the emitted photon carries some unit of angular momentum away from the atom/molecule. Since the total momentum must be conserved, the resulting momentum of the atom/molecule after the transition is simply the original value minus the photon's momentum. There are further details to this, but essentially this poses an additional constraint that needs to be satisfied for any given transition, because each state has a specific energy as well as angular momentum quantum numbers.\n\nUsually the constraints are first-order and are not strictly satisfied. The \"forbidden\" transitions can still occur but are highly improbably. This means that they'll occur at a much lower rate, so the other, more favorable transitions respecting the selection rules will dominate."
]
} | [] | [] | [
[],
[
"http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hydazi.html"
]
] |
|
4w5ev1 | in the restaurant industry, why do prices increase from breakfast through lunch and into dinner? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4w5ev1/eli5_in_the_restaurant_industry_why_do_prices/ | {
"a_id": [
"d6449ye",
"d644qug",
"d644xre"
],
"score": [
7,
5,
2
],
"text": [
"I'm not sure about breakfast, but my first guess would be that most breakfast ingredients are cheaper. \nAs for lunch to dinner, the basic answer is portion sizes. Even ordering the exact same entree, if you order from the lunch menu, your potion will be smaller than if you order during dinner hours. I've worked in kitchens/restaurants since I was 15, and this is what I've always found. ",
"It's a combination of higher cost of dinner ingredients, and supply and demand. Unless it's a niche restaurant that primarily serves breakfast, restaurants generally bring in more customers during the evening hours when dinner is served. In order to take advantage of this increase in customers, as well as to avoid depleting resources, prices are generally increased. ",
"Pricing is part of marketing. Prices are lower during hours where the restaurant wants to attract more customers.\n\nSource: I am not from the restaurant industry but I do marketing for my company."
]
} | [] | [] | [
[],
[],
[]
] |
||
5ync4i | how is exercise an anti-inflammatory? | Specifically, what does exercise do to the body that reduces inflammation? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5ync4i/eli5_how_is_exercise_an_antiinflammatory/ | {
"a_id": [
"deredm6"
],
"score": [
3
],
"text": [
"Think of inflammation as coming in two different flavors. \n\nAcute inflammation is temporary and strong. It breaks down your body in a temporary way and when your body is done repairing itself, you just made it stronger and better than it was before.\n\nChronic inflammation is a different beast. It's asymptomatic. You don't know you have it and you can't feel it. It's little but it sticks around and quietly, slowly just breaks down your body. Without it getting stronger at all. It happens so slowly your body doesn't really react. It makes it weaker over time and harms your body.\n\nThey aren't 100% sure why, but exposing yourself to acute inflammation *consistently* over time, reduces your levels of chronic inflammation. There are a lot of theories for why that is, involving stress reduction and various hormone levels. But study after study shows that it is true. \n\n "
]
} | [] | [] | [
[]
] |
|
n52ae | What is going on inside a battery to establish the potential difference that causes electric current to flow? | I'm taking an electricity and magnetism course, and its clear that some sort of work has to be done in the battery to cause current flow, but we've just accepted that it happens and moved on with circuit analysis. But I'm curious to know what the chemistry is that allows this to happen. | askscience | http://www.reddit.com/r/askscience/comments/n52ae/what_is_going_on_inside_a_battery_to_establish/ | {
"a_id": [
"c36b0jt",
"c36b0s9",
"c36eej1",
"c36fyn5",
"c36b0jt",
"c36b0s9",
"c36eej1",
"c36fyn5"
],
"score": [
2,
5,
4,
2,
2,
5,
4,
2
],
"text": [
"The difference in potential for molecules to donate/receive electrons. Some molecules are great proton donors, while others are great proton acceptors. When put in two different cells bridged by a salt bridge, the electrons will flow from the Anode (-), to the Cathode (+) end.",
"See [galvanic cells](_URL_1_).\n\nBasically, you have two [half cells](_URL_0_) that, when put together, undergoes a spontaneous reaction. Instead of letting that happen, you insert your load in between the electrodes such that in order for the spontaneous reaction to occur, the electrons must flow through the path that _you_ want, converting the chemical potential into useful work.\n\nIt's similar to an internal combustion engine - you a combustion reaction that is spontaneous, and it will just go its merry way. Instead we have to put some sort of obstacle - a piston - such that the expansion of gases is harvested as useful work.",
"There are better explanations on here, but hopefully this is a quick and dirty summary:\n\nRedox reaction = reaction where electrons are transferred.\n\nHere's the one commonly found in alkaline batteries:\n\n(Zn + 2OH- → ZnO + H2O+ 2e-)\n(2MnO2 + H2O + 2e- →Mn2O3 + 2OH-)\n\nSee how it's in two halves? That's because they're separated by a membrane, usually just a special kind of paper.\n\nNotice what's common between the two reactions?\n\n(Zn + **2OH-** → ZnO + H2O + **2e-**)\n\n\n(2MnO2 + H2O + **2e-** →Mn2O3 + **2OH-**)\n\n\nSo we have one reaction (Zinc oxidizing) that eats hydroxide and produces electrons. The other reaction (Manganese reducing) eats electrons and produces hydroxide.\n\nInside the battery, these two half-reactions cannot continue without the products of the other. They feed each other. There's one last part:\n\nRemember that paper membrane? It's preventing the two halves from touching each other. (The zinc is a plug in the center, wrapped in paper, then smeared with a manganese paste)\n\n\nWhen you touch a wire from the positive to negative sides, you allow those electrons to finally touch each other, so the reaction can progress.\n\nBUT WAIT! How do they swap hydroxides without touching? Here's the brilliant part: both halves are doused in KOH, a strong base. (Hence the name \"alkaline battery\") What do strong bases have? HYDROXIDE.\n\nSo the paper prevents the halves of the battery from short-circuiting, but the hydroxide easily moves through the paper and transfers the other half of the reaction.\n\nTada! Ain't it beautiful?",
"Here's more like an ELI5 version:\n\nMetals will dissolve almost instantly in water, as easily as salt or sugar crystals. Weird, eh? Usually textbooks don't stress this simple fact. But there's more to it...\n\nMetals are composed of positive metal atoms (pos. ions) immersed in a \"[fluid sea](_URL_2_)\" of movable electrons. Whenever metals dissolve, the water attacks the surface and drags metal atoms out into the liquid. These atoms leave their outer electrons behind in the \"electron sea\" of the metal. Positive metal ions diffuse out into the water. Positives are leaving, and this means that the metal surface becomes strongly negative. And this means that the corrosion process halts almost instantly, since positive metal ions can't break the attraction of the rapidly increasing negative charge on the metal surface. Metals *would* dissolve as easily as salt or sugar crystals, but only if the rapidly increasing negative charge wasn't sucking all the positive ions back in.\n\nThe upshot: if metal touches water, the water becomes strongly charged positive, and the metal becomes equally charged negative. The opposite charges are mostly found in a nano-thin \"[Helmholtz double layer](_URL_0_)\" where the water is touching the metal. The voltage between the water and metal, called the [Absolute potential](_URL_1_), is around three to five volts, and is different for different metals. If anything should cause this voltage to reduce, then the metal surface will rapidly dissolve. And if something should increase the voltage, then the solid metal will attract dissolved metal ions and grow larger (electroplating.)\n\nWhat's a battery? It's two different metals touching the same body of water. A water electrode touching a metal electrode is called a \"half cell.\" If two pieces of different kinds of metal are contacting water, two half-cells are present, but with a common water electrode. Their voltages won't be the same with respect to the water. And if they ever touch each other, a very large flow of charges will begin. Try connecting those two hunks of metal with a wire, and one will rapidly dissolve, since its usual strong charge has been lowered, and the water can again attack it and dissolve the surface. What drives the process? Water. H2O molecules physically surround each metal atom and violently yank it out into the water, producing an outward flow of both atoms and a flow of positive charge as well. Water dissolves metal, but it also carries away a current of positive charges away from the metal. Batteries are powered by the same nano-level electrical forces in water which tear salt or sugar to pieces: a polar solvent attacking an ionic crystal, plus thermally-driven diffusion where a dense concentration of atoms in solution will spread outwards. All these phenomena and events can be collected under the notation of balanced reaction equations. But to really grasp what's going on, it's better to think in terms of dissolving, highly charged conductor surfaces, and metal chunks which mysteriously become electrically charged every time they touch water.\n",
"The difference in potential for molecules to donate/receive electrons. Some molecules are great proton donors, while others are great proton acceptors. When put in two different cells bridged by a salt bridge, the electrons will flow from the Anode (-), to the Cathode (+) end.",
"See [galvanic cells](_URL_1_).\n\nBasically, you have two [half cells](_URL_0_) that, when put together, undergoes a spontaneous reaction. Instead of letting that happen, you insert your load in between the electrodes such that in order for the spontaneous reaction to occur, the electrons must flow through the path that _you_ want, converting the chemical potential into useful work.\n\nIt's similar to an internal combustion engine - you a combustion reaction that is spontaneous, and it will just go its merry way. Instead we have to put some sort of obstacle - a piston - such that the expansion of gases is harvested as useful work.",
"There are better explanations on here, but hopefully this is a quick and dirty summary:\n\nRedox reaction = reaction where electrons are transferred.\n\nHere's the one commonly found in alkaline batteries:\n\n(Zn + 2OH- → ZnO + H2O+ 2e-)\n(2MnO2 + H2O + 2e- →Mn2O3 + 2OH-)\n\nSee how it's in two halves? That's because they're separated by a membrane, usually just a special kind of paper.\n\nNotice what's common between the two reactions?\n\n(Zn + **2OH-** → ZnO + H2O + **2e-**)\n\n\n(2MnO2 + H2O + **2e-** →Mn2O3 + **2OH-**)\n\n\nSo we have one reaction (Zinc oxidizing) that eats hydroxide and produces electrons. The other reaction (Manganese reducing) eats electrons and produces hydroxide.\n\nInside the battery, these two half-reactions cannot continue without the products of the other. They feed each other. There's one last part:\n\nRemember that paper membrane? It's preventing the two halves from touching each other. (The zinc is a plug in the center, wrapped in paper, then smeared with a manganese paste)\n\n\nWhen you touch a wire from the positive to negative sides, you allow those electrons to finally touch each other, so the reaction can progress.\n\nBUT WAIT! How do they swap hydroxides without touching? Here's the brilliant part: both halves are doused in KOH, a strong base. (Hence the name \"alkaline battery\") What do strong bases have? HYDROXIDE.\n\nSo the paper prevents the halves of the battery from short-circuiting, but the hydroxide easily moves through the paper and transfers the other half of the reaction.\n\nTada! Ain't it beautiful?",
"Here's more like an ELI5 version:\n\nMetals will dissolve almost instantly in water, as easily as salt or sugar crystals. Weird, eh? Usually textbooks don't stress this simple fact. But there's more to it...\n\nMetals are composed of positive metal atoms (pos. ions) immersed in a \"[fluid sea](_URL_2_)\" of movable electrons. Whenever metals dissolve, the water attacks the surface and drags metal atoms out into the liquid. These atoms leave their outer electrons behind in the \"electron sea\" of the metal. Positive metal ions diffuse out into the water. Positives are leaving, and this means that the metal surface becomes strongly negative. And this means that the corrosion process halts almost instantly, since positive metal ions can't break the attraction of the rapidly increasing negative charge on the metal surface. Metals *would* dissolve as easily as salt or sugar crystals, but only if the rapidly increasing negative charge wasn't sucking all the positive ions back in.\n\nThe upshot: if metal touches water, the water becomes strongly charged positive, and the metal becomes equally charged negative. The opposite charges are mostly found in a nano-thin \"[Helmholtz double layer](_URL_0_)\" where the water is touching the metal. The voltage between the water and metal, called the [Absolute potential](_URL_1_), is around three to five volts, and is different for different metals. If anything should cause this voltage to reduce, then the metal surface will rapidly dissolve. And if something should increase the voltage, then the solid metal will attract dissolved metal ions and grow larger (electroplating.)\n\nWhat's a battery? It's two different metals touching the same body of water. A water electrode touching a metal electrode is called a \"half cell.\" If two pieces of different kinds of metal are contacting water, two half-cells are present, but with a common water electrode. Their voltages won't be the same with respect to the water. And if they ever touch each other, a very large flow of charges will begin. Try connecting those two hunks of metal with a wire, and one will rapidly dissolve, since its usual strong charge has been lowered, and the water can again attack it and dissolve the surface. What drives the process? Water. H2O molecules physically surround each metal atom and violently yank it out into the water, producing an outward flow of both atoms and a flow of positive charge as well. Water dissolves metal, but it also carries away a current of positive charges away from the metal. Batteries are powered by the same nano-level electrical forces in water which tear salt or sugar to pieces: a polar solvent attacking an ionic crystal, plus thermally-driven diffusion where a dense concentration of atoms in solution will spread outwards. All these phenomena and events can be collected under the notation of balanced reaction equations. But to really grasp what's going on, it's better to think in terms of dissolving, highly charged conductor surfaces, and metal chunks which mysteriously become electrically charged every time they touch water.\n"
]
} | [] | [] | [
[],
[
"http://en.wikipedia.org/wiki/Half_cell",
"http://en.wikipedia.org/wiki/Galvanic_cell"
],
[],
[
"http://en.wikipedia.org/wiki/Double_layer_(interfacial)#Electrical_double_layers",
"http://en.wikipedia.org/wiki/Absolute_electrode_potential",
"http://en.wikipedia.org/wiki/Sea_of_electrons"
],
[],
[
"http://en.wikipedia.org/wiki/Half_cell",
"http://en.wikipedia.org/wiki/Galvanic_cell"
],
[],
[
"http://en.wikipedia.org/wiki/Double_layer_(interfacial)#Electrical_double_layers",
"http://en.wikipedia.org/wiki/Absolute_electrode_potential",
"http://en.wikipedia.org/wiki/Sea_of_electrons"
]
] |
|
1a9uld | What causes the dark coloration around anuses? Poop? Friction? Is it just the same process that darkens genitals and nipples in puberty? | askscience | http://www.reddit.com/r/askscience/comments/1a9uld/what_causes_the_dark_coloration_around_anuses/ | {
"a_id": [
"c8ve9eq"
],
"score": [
3
],
"text": [
"Similar threads - [1](_URL_0_), [2](_URL_1_)"
]
} | [] | [] | [
[
"http://www.reddit.com/r/askscience/comments/scm1m/why_is_some_peoples_genital_skin_several_shades/",
"http://www.reddit.com/r/askscience/comments/x5ryb/why_do_your_genitals_tan_or_at_least_are_darker/"
]
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.