query stringlengths 20 300 | positive listlengths 1 1 | negative listlengths 1 1 |
|---|---|---|
Is there any kind of consensus as to why the Olmec colossal heads look like Africans? | [
"Something to keep in mind is that you are comparing contemporary population phenotypes to those in the past. A lot of the diversity you would have seen in the past no longer exists for a multitude of reasons we can only guess at. Just think of the amount of time between when they were carved and now. That's ~3000i... | [
"I forgot to say, two books to check out: Yuri Slezkine's *Arctic Mirrors* (thoughtful, academic) and Bruce Lincoln's *Conquest of a Continent* (readable, entertaining, somewhat sensationalist)."
] |
Does the hydrogen electron move in a Sine wave shape? | [
"The bound state wavefunctions for the hydrogen atom look like [this](_URL_1_). There are some pictures [here](_URL_0_)."
] | [
"I think you're confused by the fisher projection. All horizontal bonds project toward the viewer (by definition). If you want to visualize what happens when you rotate bonds, I would suggest that you use solid wedged bonds and dashed wedged bonds."
] |
Why would there be fish in a lake not connected to anything? | [
"Well considering fish don't spontaneously appear, it's only one of two options: 1. They were put there at some point in the past 2. A source of water that contained fish was connected and allowed a small population of fish to migrate to that lake"
] | [
"Quoting [Wikipedia](_URL_0_) (a bit naughty, but it's a nice way to express what I think): > The proposed theory is inconsistent with quantum mechanics and critics have ruled it out on those grounds. Which is essentially saying what you pointed out, yes. If what they're doing is as easy as it sounds - just runnin... |
Droughts and icecaps | [
"Just because it isn't raining on you doesn't mean it isn't raining somewhere else. Moisture in the air also does not automatically equal rain. That would be humidity. It takes other weather patterns, frontal systems, etc to determine when and where rain falls from the sky."
] | [
"Global Warming is a misnomer, it is really Climate Change."
] |
Unit analysis of miles/gallon. Isn't that an inverse area? | [
"No, the miles and gallons are in different contexts. You are not physically spreading a gallon of gasoline over a distance, in which case yes, you would be left with an area. The actual units are: gallons of gasoline, and miles driven on asphalt."
] | [
"Depends on what you're analyzing and who you ask. The real question is how much are you willing to spend to stop a single person from dying. And that changes. A lot of times it's cultural, but I believe it's mostly done in reverse. Come up with a proposal that can save lives, work backwards to figure out the cost ... |
Why does hot water feel nice, but hot air makes me feel like dying. | [
"The main difference is that hot air is causing you to sweat and dehydrate wherever it touches you. You're turning into a piece of human jerky."
] | [
"We have separate sensors in our skin for sensing hot and cold temperatures (known as thermoreceptors). These sensors will get activated at specific temperature ranges (i.e. cold temperatures for cold thermoreceptors and hot temperatures for hot thermoreceptors) and the activation of these separate receptors is how... |
What is a "nominee company" operated by a law firm? | [
"> Company formed by a bank or other fiduciary organization to hold and administer securities or other assets as a custodian (registered owner) on behalf of an actual owner (beneficial owner) under a custodial agreement. Basically an organization formed to control assets on behalf of their true owner. So rather tha... | [
"You mean **AWARDS**, right? Most anticipated game award could be some of them. Don't need a release for that one. :) The others are because the award judges get advanced near-complete versions of the game to experiment with. They get to see the in-game graphics, try to play it, and so on to allow them to get enoug... |
How is mimicry/camouflage selected for, and how can it become so accurate? (Owl faces in moths/butterflies, walking sticks, leafy seadragons, etc) | [
"Take your basic butterfly, add a pattern that varies with each individual, eat all the ones that look the least like the target pattern, and what's left over will have patterns that are less likely to be eaten. Repeat for generations and you get closer and closer to perfection."
] | [
"In addition to the obvious fossilized skeletons, many other kinds of fossilized dinosaur remains have been discovered. In particular, there are a number of fossilized imprints that give broader hints to what dinosaurs looked like. E.g., see [this](_URL_0_) picture of a Sinosauropteryx, with clear feathers along it... |
What is an RSS feed? | [
"Some websites that update (webcomics, blogs, etc) have something called an RSS feed, which you can view in an RSS reader. With an RSS reader you can subscribe to sites with an RSS feed, so that you just have to go to your reader to see all the updates you care about and you don't have to go check them all individu... | [
"Radiolab does a really good job of explaining it like I'm 5: _URL_0_"
] |
English currency (the old system) | [
"_URL_0_ As to why, its the same reason a foot is 12 inches instead of 10. At the time it was developed, the primary difficultly in any numerical system wasn't converting between units, it was measuring those units, so it was easier to use a number system that divides in halves, thirds, and quarters easily."
] | [
"It's how poor students would pay teachers many years ago. Before schools were publicly funded, families had to pay for their kids to attend school. This resulted more in a barter system where kids of farmers would pay with apples or frequently potatoes."
] |
18th century Clothing, names and description. | [
"Most of the \"proper\" names are French, the fashion came from France, and since most of the elite spoke this language (a bit like English now), they rather had no problem with naming their clothes in French ;). So, although the names of these things are usually existent in English, French names are much more prec... | [
"Follow up: what materials were used in the construction of various homes/commercial properties? And who constructed them - did they have architects, etc for homes of regular folk? Or did poor people build their houses themselves?"
] |
In my 5th grade understanding of economics, if someone loses a dollar, someone else gains it. If this is remotely true, how did the world collectively lose a trillion of dollars in 2016? | [
"Because no one literally lost the money, but rather the things they owned lost value. If you have a pipping hot pizza you could probably sell it to someone for $10. If you dropped it on the ground, no one will buy it. The pizza lost value."
] | [
"You have a lemonade stand. You sell it for 50 cents a cup. One day you find out it's going to be very hot outside and people are going to want more lemonade. You figure you can get away with selling it for a little more since the demand is there. So you start charging 80 cents. You notice that the number of people... |
Why can juicy fruits like watermelon be grown in regions of the world that have horrible water pollution, but it doesn't seem to affect the people who eat it? | [
"Plants absorb water through ultra-fine membranes made of plant tissue. Some chemical pollutants can indeed get in and poison the plant. But the most common pollutants we worry about in our water -- things like bacteria -- are way too big to make it in through that membrane."
] | [
"The better part of what you call \"taste\" comes from your nose. In order to better appreciate a taste, you must isolate it from everything around it. A clean glass has no odor. Put your nose in a red solo cup for a moment and appreciate the chemical aroma inherent in the vessel. Now grab a plastic cup that's bee... |
What excludes us from perceiving the 4th dimension? | [
"There is as of yet no evidence that a fourth spatial dimension exists. We cannot perceive that which doesn't exist."
] | [
"That would depend on who and when the determination was made, and the intelligence of the being to recognize the evidence. For example, lets assume all visible signs of human activity were non existent, would some future being recognize our existence because it found evidence of plastic in the genetic code of fish... |
Do electrons/energy build up at the entrance to the resistor? | [
"Voltage builds up, current (actual electrons) does not. Think of it this way: Just because there is a dam doesn't mean the steady-state flow of the river is different. If the damn tried to slow the flow of the river (too much), the river would crest the dam and it would catastrophically fail. Voltage is the height... | [
"Back in the cold war days, many small \"bug\" radio transmitters in Britain worked by rectifying BBC Radio 1, a powerful radio station that blankets that nation. Instead of trying to incorporate and hide a battery, spies would run a little wire out from the bug to pick up tiny amounts of power from the aether. The... |
What common medieval fantasy tropes have little-to-no basis in real medieval European history? | [
"One medeval trope I was disappointed to learn was false was that of the cozy inn, [this post better clarifies the reality of travel lodging in the middle ages.](_URL_2_) As for warfare in England in the early middle ages, most soldiers who possessed horses would ride them to the field but dismount and form a shiel... | [
"People do [try and salvage ](_URL_10_) shipwrecks in the Mediterranean. There is an abnormally high number of potentially valuable sunken ships in that area, given its long history of being sailed. In the context of the Greek shores, described above, government regulations have banned salvaging activity. This crea... |
Taking away Watergate, how is/was Nixon regarded as a president? | [
"You seem to forget one of the most controversial events of his career: the secret and illegal bombings of Cambodia, who during this time was neutral. Just putting that out there."
] | [
"Besides the ethnic clensing of the Kurds and Shia Muslims? He invaded Kuwait, a small country bordering it and it forced NATO to respond."
] |
Are there any "nice" viruses? | [
"Bacteriophages can be used to treat bacterial infections, but phage therapy hasn't really caught on. Viruses can also be used to deliver genes in gene therapy."
] | [
"The people don't make money off the adds themselves. They make money when say your typical 70 year old grandma or 5 year old kid click on the ad and download (and install) the program. Once installed these programs take all kinds of personal information (including credit card numbers) and can actually take control... |
How do they "estimate" how many people were at events? | [
"A photo is taken. Within the photo a fixed size is determines, like 5x5 feet. Within the square the number of people are counted. Then the total area being measured is divided into similar squares and the number of people in 1 square is multiplied by the total number of squares."
] | [
"You know how apps require permission for your location? It's like that. GPS networks process information from other users currently stuck in traffic. In some cases, like Google Maps and Waze apps, the permission for your location is exactly the reason they are so accurate for traffic."
] |
Why are the lower back muscles so much easier to hurt compared to other muscles in the body? | [
"Every set of muscles has an opposite set to pull your skeleton back in place--biceps/triceps, quads/hamstring, etc. The opposite of your back is... your abs! I learned this the hard way when I pulled my back out lifting a dehumidifier. I was always a gym rat, weight training, etc., but the chiropractor sent me to ... | [
"There is a back door into every house. People put alarms all over their house. Have a key? You can get in the front door. When you need to break in you use the back door. Now only bad people use the back doors. So when someone comes in the back door, the alarm goes off. Your crack is a bad person, technically. He ... |
Front page posts and their karma. | [
"In short, Reddit manipulates the votes as a measure of spam protection. The ratio of upvotes to downvotes doesn't change, but the bots don't know if they are actually influencing the votes. It's called [vote fuzzing](_URL_2_). [Also](_URL_1_). Now, more specifically, to answer your question, [here is an article](_... | [
"I don't have a great explanation for this, but it's called frisson. Check out /r/frisson for more info."
] |
When and why did Christians stop warring with one another? | [
"If I can ask a question, at which point does a war stop being a religious war and start being a different sort of war? Even during religious wars religion was not the only motivating factor and there were certainly political reasons for going to war, such as the acquisition of land, wealth, etc. I ask because if ... | [
"hi! Could you clarify the scope of this question? Are you mainly asking about practices in Scotland / the British Isles roughly around the Civil Wars, or landowners anytime anywhere? [hint: [say the former](_URL_0_) ]"
] |
Why do beans make me fart? | [
"Think of nutrients as lego sculptures. Some are simple and easy for you to take apart, but sometimes they're really complicated and you have to ask your brother to help you take them apart. Beans have nutrients called complex oligosaccharides that are like really complicated lego sculptures. They're really hard to... | [
"Association. The body knows what is about to happen when you are rushing towards a toilet and begins to prepare."
] |
when you go to a different country you exchange money from your country with this country's money. What is done with thr money from your country? | [
"The same thing we did with the money except reversed. So instead of exchanging to their money on arrival, they exchange it back to people leaving."
] | [
"When you die, and you are health(ish) the morgue will give your body to an institution, such as a university or a hospital, that then will use your body to learn more about how living people's bodies work. I had the \"privilege\" of seeing a cadaver (a donated body) at a local university and they basically used it... |
Why Was There So Much Popular Outrage About the Tea Act of 1773? | [
"It was designed to prop up the East India Company which was floundering financially and burdened with eighteen million pounds of unsold tea. This tea was to be shipped directly to the colonies, and sold at a bargain price. The Townshend Duties were still in place, however, and the radical leaders in America found ... | [
"Hi there -- while we've approved this question, we would like to remind potential respondents of our [current events](_URL_0_) (AKA \"20-year\") rule -- it's fine to discuss events through 1997 (inclusive) and their effects, but not events after 1997. Thanks!"
] |
how much force did i have to break a car window with my head? | [
"Warning, such head trauma can be life-threatening, even after a few days. If you haven't seen a doctor, please see one."
] | [
"If it’s a novel including a monster, wouldn’t you just make the acid to be able to go through anything just like in Hollywood? It also depends on the acid. Some acids are stronger than others. Hydrofluoric acid (HF) attacks the components of glass, so that is something that you could possibly use in your novel."
] |
What makes inflation so bad? | [
"It benefits people with debt (their debt is worth less) but screws over people with savings (because their savings don't necessarily rise with inflation). Also, wages are sticky- it takes a while for them to catch up to price changes."
] | [
"if 1+1 is 2, why can't I have ice cream for dinner?"
] |
How do one start to code advanced programs? | [
"Big programs are build incrementally, in small steps, one small feature at a time. A game isn't made as a whole in one big step, but as a collection of many individual systems that get iterated on a lot. Game (and game engines) are usually made this way: * create a program that opens an empty window * make the pro... | [
"Here's how I did it. Read a few articles every day. If something interests you, crack open Wikipedia and read more background on it. Ask questions to well-informed people in your life (or online). And get your information from multiple sources, I can't emphasize this enough. I usually use the New York Times, The E... |
Why do clear crystalline things (salt, sugar) appear white when all together? Verses clear when you look at the chrystals alone | [
"Every time a light ray hits a boundary between transparent materials, some of it passes through and some of it reflects back. (You can see through a window, but you can also see your reflection in it.) Both the reflected and transmitted light rays change direction based on the orientation of the surface. So if you... | [
"Pretty much all complex food tastes different in different conditions. Since much of our 'taste' is actually smell, I suspect that a huge amount of it depends on the proportion and composition of the volatile components. (this is certainly true for wines - consider how big of a difference temperature and glass sha... |
It's a commonly known fact that metals oxidize, but is it possible for them to ____-dize with other gases? | [
"The term \"oxidize\" to a chemist does not necessarily mean that the material is reacting with oxygen. It means that the material is participating in a chemical reaction in which it becomes positively charged (or more positively charged than it was in the first place). Since oxygen is the most plentiful substance ... | [
"you need oxygen/fuel at a minimum ratio to combust. There is little or no oxygen in the gas canister."
] |
can anything be changed due to the marches? | [
"Indirectly, yes. The hope is that by participating in the marches, many people who were not politically active will become more politically active -- they will be connected and feel like there are things they can do to make a difference, and so they will do them. This may include contacting their congressional rep... | [
"Talk to your representative and lay out your concerns. My understanding is that calling, and calling often, is the best tactic, as it's the only way where you absolutely *know* you have their full attention, even if for that brief moment. Or, you know, do what nobody actually does; pay attention during the various... |
How come the Earth's age is determined from the age of it's meterorites? Couldn't The meteorite be much older than the Earth? | [
"Last year I visited the NC Museum of Natural Science and I touched a meteor on display described as *older than the solar system.* It took a moment for me to understand the concept. [Here's an article about rocks *older than the sun*](_URL_0_)"
] | [
"Crashing huge chucks of ice into Mars was also part of the terraforming recipe in Kim Stanley Robinsons Mars trilogy. It has occured to me that adjusting the orbit of a comet to crash it into a planet could be easier than doing the same thing with an asteroid. If a number of large flat mirrors could be put into so... |
Was there any attempt (other than Alaska) for Russia to have an overseas empire? | [
"I would not say the Russian state itself, but some Cossacks leased some land in Djibouti from an Afar sultan and then came by ship to set up a colony. They named it New Moscow, and it only managed to exist for a single month before getting driven out by the French."
] | [
"Hi, I've approved the post, but just a note to you and potential respondents: this subreddit has a 20-year rule against discussing current events, so any answers will have to cut off at 1997. If you're looking for answers that can include 1998-2012, do consider x-posting elsewhere, eg. a foreign affairs sub like /... |
Has a federal judge ever found a sitting US president in contempt of court? | [
"Yes, Bill Clinton in 1998 in relation to the Paula Jones lawsuit (I'd go into details, but that would violate the 20 year rule). Otherwise, no president has been held in contempt by a federal court."
] | [
"I am not sure this question is quite a fit for this sub. The first part certainly is, but generally /r/askhistorians isn't where an analysis of modern politics, even in relation to historical politics, is made. /r/AskSocialScience might be a better place to try! That said, at least in regards to the political atmo... |
How did they animate and edit movies decades ago? | [
"Film guy here. Movies were edited by watching different reels on a machine that looks like this: _URL_0_ which lets you play and listen to different clips and/or the whole assembled movie. Film Footage was cut apart and taped together with blades and special tape with a device that looks something like this: _URL_... | [
"My guess? When you're dealing with a lot of makeup, prosthesis, special effects its easier to hide flaws. You can see acne under makeup in high def, you couldn't really see that back in the day. Just a guess."
] |
My toddler likes to play with my glasses, and it got me thinking. How do doctors determine babies need glasses? | [
"There are basic vision screening tests for infants, Toddlers can take modified versions of adult vision tests using simple charts (sometimes with illustrations instead of text). _URL_0_"
] | [
"> \"Traditional\" estimates based on slow, reptilian growth rates, combined with the enormous size of dinosaurs, led scientists to conclude it could be up to several hundred years. [Source](_URL_1_) [Source 2](_URL_0_) So, traditionally, age estimation was based on modern-day analogues of dinosaurs. However, \"gro... |
Why are grown men attracted to "My Little Pony". | [
"I actually did a Powerpoint presentation about this very subject (in Spanish). There's lots of different factors. Many in the 18-35 age range see the show as nostalgic to shows they used to watch when they were children. They appreciate the art style, themes, and different character personalities that are exhibite... | [
"You know how people thought there's some angry god that throws lightning bolts when you do or don't do something? Well people are afraid of things they don't understand."
] |
What percentage of military conflict since World War 2 has involved the United States? | [
"Firstly, we cannot really accurately list all military conflicts. It's such a broad concept, and can include everything from border wars to drug wars. After some research, I do have some numbers though. But, according to _URL_0_, there have been \"over 250 major wars\" since 1945. So, we'll use that number. Of all... | [
"May want to look into General Jimmy Doolittle. After his famous raid on Japan he was promoted to Brigadier General (skipping full Colonel) and sent to command the 15th Air Force in North Africa in Sept 1942. Then after a promotion to Major General to Italy to command 15th Air Force in Italy with command over the e... |
Why do depictions of religious figures generally (in the UK at least) portray them as white people, when they would have been black? | [
"What color is the skin of most of the people who make and utilize those drawings? Theres your answer"
] | [
"Setting aside the terminology of \"race\", it's entirely down to selective pressures of the different environments. In equatorial regions where the sun is plentiful, having a lot of melanin is useful in protecting against cancer. The further north/south you go from there, the less sun there is, so having less mela... |
Would it be easier to build higher buildings if they were shaped as pyramids or would it cause more problems due to the wind etc? | [
"Not science disclaimer: This is not science. Land is sold by the acre which is surface area. The whole point behind very tall buildings like the Burj Khalifa is to maximize *that* patch of planet that it is built upon. When the design constraints begin at the very bottom, the only choice is to go up. Pyramids ha... | [
"We do. For instance, any dam on a river that generates electricity is utilizing gravity to get the job done. The trick is, we're letting the water cycle do the heavy lifting of moving an object 'uphill' (our river water). So there's still an energy input, it's just that we humans don't have to supply it. If we wa... |
Why is lead so dense but so soft, aluminium so light but also soft, but then tungsten is very dense but incredibly hard and titanium is so light but also really hard? | [
"So, an important concept here is the lattice structure. You can imagine this as just how the atoms are stacked, so, for example you could have a cubic lattice where every atom is located at the vertex of a cube. You could also have some sort of hexagonal structure (imagine stacking oranges). All sorts of structure... | [
"Thermal conductivity. Essentially the pillow is at room temperature, but your head is typically ~20°F warmer. Heat, much like a gas, always tries to hit equilibrium (everything at the same temp.) As such. The pillow will absorb the heat from your head. Now here's where the claim comes in. Different materials will... |
The James Webb Space Telescope is incredibly precisely made. But it will be mounted on top of several tons of rocket. How do they make sure it doesn’t get warped in flight? | [
"Very careful simulation based on testing data. Engineers have experimentally gathered data about all the different materials used to make the telescope. This data includes failure points given applied loads, vibrational frequencies, etc. They can use this along with a computational model of the sattelite to predic... | [
"The Vomit Comet (and similar services) as well as wires and camera tricks."
] |
What happen if an astronaut becomes really ill on the ISS? | [
"All astronauts are trained medics and have a hospital's worth of medicine and basic surgical equipment onboard. They've practiced mock procedures guided by doctors on the ground but to my knowledge no one has ever gotten hurt/sick enough to warrant that nor the extreme solution which is to evacuate on a docked cap... | [
"Many international flights have layovers in countries not in the intended destination. Instead of forcing all of these passengers to first be cleared with the government of the layover country, which is time consuming and costs money, they simply designate an area for these people to board their separate flights w... |
Why are Nigerians involved in so many scams? | [
"They're poor, they often speak English, they have internet access, and there's little effective enforcement in Nigeria."
] | [
"\"Just about everyone here\" Where is \"here\" for you? It sounds like your question's premise is based on a small sample set based on personal observation. Before your question is addressed, you should be making sure the premise is valid..."
] |
Why are comments being locked and deleted around the discussion of the events in Germany on New years Eve? | [
"Because people feelings are more important than your sister getting a bad touch on her front butt from 50 strangers and getting her candy stolen"
] | [
"Dublin Regulation is an act regulating how asylum claims are handled. TL;DR: First country an asylum applicant enters handles the problem. It's failing couse it would strain countries reciving the weave of migrants like Greece or italy"
] |
How long would it take to travel to Alpha Centauri, both WRT an observer on the spaceship and an observer on earth? (Assuming constant acceleration of, say, 10m/s^2, and ignoring earth's gravity). What would be the effect of space time dilation for each of the observers? | [
"The relevant equations can be found [here](_URL_0_), where I assume that the acceleration you refer to is what the spaceship feels (\"proper acceleration\") which is actually distinct from coordinate acceleration in any reference frame. Plugging in for a 4.37 lightyear trip (and using the acceleration 1.03 lightye... | [
"It's only that simple when acceleration is constant. Under that assumption, your question really boils down to \"why is the integral of x^n proportional to x^(n+1)?\" (I'm going to assume that, as an engineering major, you at least know basic calculus.) If your position (or displacement) is a function of time, x(t... |
The persistence of end-of-the-world claims. | [
"Y2K was not \"abruptly canceled\". It was prevented, through an incredible amount of work. We saw it coming, and we fixed it, with millions of hours of coding and bug-fixing. The cost of all the work to prevent the problem is estimated at over $400 billion in today's money."
] | [
"There isn't any downside to saying the sky is falling. Politicians aren't vying for the votes of economics professors, they are vying for the votes of people who don't have the willingness to look up the numbers themselves."
] |
Why do people think chiropractors are a wasteof time? | [
"Chiropractic therapy has historically been influenced by incorrect ideas about how the body works, and there isn't much solid evidence that it *does* anything."
] | [
"\"Just about everyone here\" Where is \"here\" for you? It sounds like your question's premise is based on a small sample set based on personal observation. Before your question is addressed, you should be making sure the premise is valid..."
] |
Why are some states deciding to constitutionally ban gay marriage if gay marriage isn't legal there anyway? | [
"If it's constitutionally banned, then the state's courts can't declare that discriminating against gay marriages is illegal. So if a constitutional ban is passed, and the federal government does not require states to allow gay marriage, the only way to get gay marriages legal would be through another constitutiona... | [
"Primarily because one party (GOP) supports industry and business in general, which includes oil. Petroleum products are used in all sorts of functions in our everyday lives in ways that you may not even be aware. So the burning of these fossil fuels is what has been found to cause climate change (according to clim... |
What is the HIV "cure" | [
"This will have to be like you're five, because that's the only level at which I understand it. There is a very rare mutation that makes some people (like 1 percent) highly resistant to HIV infection. They simply lack the major chemical gateway through which the virus enters your cells. (Apparently not having this ... | [
"Yes, there are a few in the pipelines, the oldest research is around phage, or phage technology. This was started in Russia and according to wikipedia is was researched and still is from as far back as 1922, I remember reading about in the 90's. Still haven't heard of anything commercial though - _URL_0_ There are... |
If renewable energy is the future, why haven't we put solar panels on every household? | [
"Cost. Solar panels are still more expensive to make and install vs. tapping into existing infrastructure. Also, anywhere without good sun exposure will get crappy use from solar panels. The need for a second, backup source of power for extended periods of time would, effectively, make it cost more to do solar tha... | [
"It's way, way, *WAY*, too expensive. The power plant alone would probably be more expensive than the entire lifetime cost of an average bulk carrier. Not to mention the insane mess of regulation that is involved with running a nuclear reactor. Basically, big ships run on bunker fuel, and bunker fuel is ludicrously... |
Do we currently have the technology to build any kind of starship to get an adequate number of humans to another star system? | [
"If we posit that the entire planet makes such a thing a top priority, then maybe. Almost certainly the propulsion method would be nuclear fission based or nuclear explosive based (either nuclear salt water rocket or Orion style nuclear pulse propulsion). Beyond that it'd probably be a rotating ring structure to ge... | [
"If by \"we\" you mean Americans, not much. The CDC is controlling the two citizens that are infected closely, and our climate and lifestyle isn't really conducive to spreading the infection. If you mean everyone on earth, a little more, bit still not much; ebola doesn't spread as easily as a lot of other diseases,... |
How do "Are you a robot" codes work? | [
"One thing robots are not very good at yet is analysing pictures and reading whatever text might appear in these pictures. This is especially true when the characters are warped and some random shapes and lines are added into the mix. So the basic idea behind CAPTCHAs is simple: if you can correctly read the charac... | [
"Answering the first part of your question: _URL_0_ _URL_1_ _URL_7_ _URL_3_ _URL_5_ _URL_6_ _URL_2_ _URL_4_"
] |
Would my air conditioner work more efficiently if I misted water over the outside part that disperses the heat? | [
"Yes. By a lot, if you are in a dry climate. Water is very good at taking energy out of the air. This: _URL_0_ will explain it in detail, and commercial (industrial for sure, have not seen one for residential use) examples are abundant of water cooled air conditioner coils."
] | [
"Just because it isn't raining on you doesn't mean it isn't raining somewhere else. Moisture in the air also does not automatically equal rain. That would be humidity. It takes other weather patterns, frontal systems, etc to determine when and where rain falls from the sky."
] |
What happens when the speed of light is altered? | [
"The speed of the light is not altered; rather, the path is altered to be longer. It travels farther through some mediums than others, and even through the same medium at a different temperature (diffusion above a fire, for example)."
] | [
"Lengths can only contract, they can never be made *longer* than the proper length, in special relativity."
] |
What happens to the brain during sleep deprivation? How bad is it to regularly pull 'all-nighters' or use stimulants to stay awake? | [
"Shortwindedly, your astrocytes are not restocked properly and you lose cognitive faculty temporarily. Your brain starts micro-sleeping after a few days of deprivation, and you will lose consciousness (not consciously, though) for up to five minutes at a time in order to compensate for the lack of REM sleep. In sho... | [
"Ahoy, matey! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: What happens when medication expires and what determines the date of expiration? ](_URL_2_) 1. [ELI5: What happens to medicine that is past its expiration date? Is it stronger, weaker, or different somehow? ](_URL_5_) 1. [ELI5: Why ... |
When the WWII ended, the German citizens had been supporting National Socialism for over a decade. How did teenagers and young adults raised in that ideology deal with having to suddenly "forget" about 10 years of massive indoctrination? | [
"[A study by economists Nico Voigtländer and Hans-Joachim Voth](_URL_0_) shows that the Germans who grew up as children during the Nazi regime (1933-1945) and were consequently exposed to anti-Semitic ideology in schools, in the (extracurricular) Hitler Youth, and through radio, print, and film, were much more anti... | [
"Because when you are younger, everything is theoretical. It is easy to condemn the rich or successful business owners when you don't know any. It's also easier to argue for distribution of wealth when you don't have any. People in general look out for the class they are in, and their friends are in. In general peo... |
Is it possible to workout so much in space that you lose neither muscle mass or bone density? | [
"The current recommended training regime of astronauts on ISS will keep most of their muscle mass and bone density or even increase them in places. There is still some refinements needed to make it perfect as there is some issues with bone density in the pelvic region as the astronauts do not balance enough when th... | [
"Hi, this question was asked not too long ago, I recommend you check out this link: _URL_0_ That should answer your question. In short, I believe you would nut suffer from dehydration in the traditional sense, but various other problems arise, which I suggest you explore that link for more info."
] |
What is the weird feeling in your jaw when eating something sour? | [
"That's your salivary glands secreting extra saliva to \"dilute\" the sour food. They kind of go into hyperdrive so they hurt..."
] | [
"Envision jello on a plate. Now envision hairs are growing out of the plate and in to the jello, and the jello is topped with small pebbles that are stuck to it. If you tilt the plate, the weight of the pebbles being pull ed down by gravity causes jello to skew, bending the hairs inside in that direction. That is h... |
Why is it acceptable to display the confederate flag. | [
"It doesn't symbolize slavery, it symbolizes rebellion. People who fly it generally do so because it represents the rights of the states over the federal government, and general down-south values mixed with some anarchist sentiment. The meaning of a symbol is dependent on who uses it, and why."
] | [
"The popularity of comic book characters and acceptance of the geek subculture, mainly. people aren't scared to show that they enjoy these things anymore."
] |
How come you can give a person any number and they can iterate forwards or backwards on demand but with the alphabet most seem to only Have a few fixed points to start from and can't as easily go backwards | [
"Because the order of the letters are completely arbitrary. And there are many more letters than there are digits. Numbers are systematic. You *learn* to count by memorizing only 10 different digits, then use a simple system to make more numbers. Counting backwards is just removing 1 over and over again. For the al... | [
"Because what you think is the \"previous page\" isn't. In many cases, when you click on a link to a page, it redirects you to another page. Often this happens so fast you don't even realize it. Let's take three web pages: * Page A - Contains a link to Page B * Page B - automatically redirects to page C * Page C - ... |
why cant the american government just print the money they need to pay off their debt? | [
"[**Search before submitting**, especially when asking about current events. The search box is in the upper righthand corner of the page.](_URL_0_)"
] | [
"Not enough energy to. It's like lighting a match in a snow storm and expecting it to melt everything. Sure, the match is hot, but theres a lot more cold than there is hot."
] |
Why do rats get cancer very often? | [
"If you are referring to lab rats used in cancer studies, then they are specifically genetically created to get cancer. If they don't we give them cancer. Its not a pretty process, but we need to test cures on living creatures, and its a lot of paperwork killing people with failed cures. As far as I know normal rat... | [
"\"Everything changed for me\" \"I'll never forget the day that everything tadted like tofu. Everything tasted like nothing.\" Source, wife who went through chemo last year. Tastebuds are fast turnover cells that regenerate and die quickly. Chemo kills the tastebuds before they can develop and mature. What taste ... |
Why do I have the urge to sneeze when I look at the sun or a bright light sometimes? | [
"It's called the photic sneeze reflex and it is surprisingly common. It's not known to be related to any significant medical issues or benefits, so not much effort has been put into researching it. Multiple explanations have been proposed to explain this phenomenon. The explanation I've heard the most relates to t... | [
"Our brains didn't evolve with cars in mind. They evolved with, like, being hunted by a jaguar (or whatever) in mind. So your brain doesn't know what to do with a car. It thinks hey, we're sitting, our body's not really doing anything physical, there's very little activity or stimulus... this seems like a good time... |
why do states like alabama not have a lottery | [
"I don't know this to be true, but it's probably BECAUSE of the casinos."
] | [
"Costs money to build and maintain the facilities, some countries don't feel like taking on the burden of that cost."
] |
Why are Criminals given multiple life sentences? | [
"Because one is charged and judged for each crime - not all together. Best example: Someone in jail (life sentenced) murders. Now he will have a new court case + judgement"
] | [
"It's similar to the way 125% subprime mortgages spread (without getting into the debate about whether that caused the recession) - you get a few groups who think a similar way, with broadly the same ideas, motivations, worldview, that sort of thing, and when one of them comes up with a policy that fits those ways ... |
If I peeled a bunch of fruits but never picked them off the vine/tree, would the skin grow back? | [
"hi production horticultrlist here. no the exocarp (peel) of a fruit will not grow back, but it will (plant depending) attept to form a scab to protect undeveloped fruiting bodies. most mature fruit will likely rot. any specific plant you had in mind when you asked?"
] | [
"[This was asked before](_URL_0_) [Heres a formal academic article that really tackles the question.](_URL_1_) Short answer: they very likely didn’t. They viewed the Liver as an organ that was connected to wisdom or the soul (or both). They likely viewed his liver being gored at everyday and yet regrowing as symbol... |
the churches stance on evolution and the universe? | [
"Which church? There's literally thousands of them. Assuming you're talking about the Catholic Church, they are on board with evolution, although I don't know the official stance on the size of the universe."
] | [
"A big one is, well, most of the bible. Was there a united monarchy? If so, what did it look like? Is there something behind the Exodus narrative, or is it a myth to give the Israelites a history separate from the other Canaanite groups?"
] |
Why do tatoos last for ever? | [
"That isn't strictly true. Not all cells will be replaced by new cells. For instance, the neurons you're born with are the ones you're going to die with. The skin itself does replace itself very often, or at least the very top layer called the epidermis. The dermis, under the epidermis, is where tattoo ink goes. Ho... | [
"The ink is injected deep into your skin, so it's below the layers that rub off."
] |
How does marijuana keep you relaxed if it increases your heart rate? | [
"Heart rate and blood pressure only increase in the short term immediately after inhalation (which to me points to oxygen deprivation due to smoke), and actually lowers heart rate and BP as the cannabinoids hit your systems, which combined with the memory fogging effects (you forget your worries man) leads to relax... | [
"I'm sorry that I'm no expert, but I remember reading about this the last time a similar question was asked: _URL_0_ Basically, you percieve time faster after your run because of endorphines released during the work out, which means that the music seems slower. This is apparently also why a lot of rock musicians pl... |
What happens if the President and Vice President are both assassinated, and the current Speaker of the House is not a natural born citizen? Does the presidency skip SOH, or do we get a president who is an immigrant? | [
"It would just move down the line of succession. The line is ordered by position, but it skips those who are ineligible. If the Speaker of the House is ineligible, then the job goes to the President Pro Tempore of the Senate. Currently, it is Orrin Hatch."
] | [
"Iowa and New Hampshire host the earliest presidential primaries. Winning Iowa and/or New Hampshire means starting off the race for the party nomination with plenty of momentum and validation of your campaign. Plus, in the lead-up to the election, political pundits need something to talk about, and the kick-off of ... |
Why do people always want the newest available thing, whether it be a gadget, vehicle, tool, toy, etc? What theory or concept is this? | [
"Because people want to show off and maintain or increase their social status (or 'importance' of the group). People like to feel important and they more so like to feel better than others, especially their peers. So they try to show off by buying trinkets and new tools. This is partially evolutionary. The need to... | [
"Inflation. Let's put it this way, in America it used to be that you could buy a steak dinner for let's say $5. Then today that same steak dinner would cost $50. How much we pay for things, and how much we get paid has increased slowly over time. In other countries, it has increased way faster, so something that us... |
Why do we call 'w' double u, but 'm' not double n? | [
"because the original symbol was. UU and then became VV. M predates N as a letter."
] | [
"> Many domain names used for the World Wide Web begin with www because of the long-standing practice of naming Internet hosts (servers) according to the services they provide. A server could also support things such as email (*_URL_13_*), file transfer protocol (*_URL_11_*), newsgroups (*_URL_12_*), etc. [Wikipedi... |
How do fish food companies make any money when one little container lasts so long? I have a container of betta fish food that has lasted through two fish and almost 2 years and there is still more than half. | [
"Companies like that usually have many different sorts of products."
] | [
"1. A \"feeling\" of being full is a type of phenomenon known as a qualia, which by its very definition lies outside of the realm of objective scientific measurement. 2. If a creature does not possess a physiological mechanism to let it know that its stomach is reaching capacity, limit the desire to eat, or otherwi... |
When filling something with an air compressor, does the rate at which it fills decrease as the pressure increases? | [
"Yep, you're quite correct. Once the pressure in the object reaches the same as the maximum pump pressure, there would be no flow at all. If you then gave the tire a good squeeze, air would flow back through the compressor until the pressure equalised again."
] | [
"Products should never get cheaper unless the technology/process to do so allows. If you could buy a car today for $10k or buy a car tomorrow for $9k which would you choose? This is what causes the death spiral, basically people stop buying things today so they can get it cheaper tomorrow. Our economy relies on pur... |
Swamp gas explosions | [
"Depending on the environment around a swamp, sometimes there is just enough heat, oxygen, and fuel to allow for a smoldering fire to start under, and even spontaneously explode beneath the surface of the swamp! In regard to if you threw a lit match into the middle of a swamp, it would all depend on where the match... | [
"I grew up in the South. Oftentimes as evening set in, and humidity rose, the radar towers would show false echoes really close, just like in your picture."
] |
If a planet farther away from Earth had the qualities of Earth, would the planet be able to support other life forms?? | [
"One of the \"qualities\" of Earth that allow it to support life is its relatively moderate temperature range. This is possible primarily because of where we orbit in relation to our Sun, the so-called \"habitable zone\" outside of which life as we currently understand it simply can't exist. So if a planet were of ... | [
"If you have a 30W light bulb right in front of you and a 100W light bulb on the other side of the football field, the 30W bulb will appear *much* brighter because it's so close. By the time the 100W bulb's light gets to you, it's scattered so much that there's barely anything left to come straight at you. Stars ar... |
Why is it so difficult to desalinate water? | [
"It's hard to do because the molecules that make up salt are extremely tiny and can slip through all but the most extreme filters. That leaves you with two options: 1) boil the water into vapor to leave the salt behind. 2) force the water through an extremely fine membrane to filter the salt out. Option #1 requires... | [
"Costs money to build and maintain the facilities, some countries don't feel like taking on the burden of that cost."
] |
What's the difference between a bank and a credit union? | [
"A credit union is a cooperative. I paid 5$ to be a member of mine. The members own the company. They hire staff to run it. Theres are regular CA meetings when major decisions are made. Once a year the overall dividends (profit) is shared between all members. I make about 300$ a year this way."
] | [
"This CGP Grey video does a really good job of explaining it all. _URL_3_"
] |
Is the cosmic microwave background visible in every single direction? And how do we know it is what we say it is? | [
"Yes, it's not just visible in every single direction but it is the most perfectly uniform natural blackbody observed across the entire distance of the universe > And how do we know it is what we say it is? I don't understand the question. We know what it is because we measured it with several telescopes"
] | [
"This question is pretty tough to imagine. Here's something that might help: Imagine you live on a [Möbius strip](_URL_0_). You're facing straight down at all times. You leave a ghost image of yourself as you go around the strip. Travel fully around and you get back to where you started, still looking the same way.... |
If you close your eyes and push on your eyeballs, you see colours and oscillating patterns. Why is this? | [
"> Are the rods and cones in your eyes also sensitive to pressure increases somehow? That's it. It is one of many examples of neurons receiving non-standard stimulation and responding. Other good examples include the \"hotness\" of peppers and \"coldness\" of menthol: both are temperature sensations set off by chem... | [
"[This figure should help explain it.](_URL_0_) A shows 4 waves each with different frequencies and C shows what you get when you combine those waves together. (Ignore B and D). A combination of different sound waves creates a single wave with a unique pattern. So instead of a speaker moving in and out by same amou... |
What stock trading move do Eddie Murphy and Dan Aykroyd pull in the end of Trading Places? | [
"What they did was [short selling](_URL_1_). They shorted the orange juice prices, knowing that the crop was abundant and that prices would plummet. The way they primed the pump for this exploit was to provide false information about the scarcity of the orange crop to the old bad dudes. When the old bad dudes thoug... | [
"Investopedia has a good example that makes it pretty clear: \"(the adjustment needed for the exchange rate) so that an identical good in two different countries has the same price when expressed in the same currency. For example, a chocolate bar that sells for C$1.50 in a Canadian city should cost US$1.00... |
Why is sauce more likely to go bad when you put it in the fridge while it's still warm than if you let it cool before putting it in there? | [
"In addition to what's been said: The portion that has cooled acts as an insulator for the middle. This means the middle stays warm enough to act as an incubator for all sorts of bacteria."
] | [
"It means that physics, as we know it now, is actually a low energy solution to a more general high energy theory. The common analogy is the ferromagnet. Above a high temperature (the Curie Temperature) the magnetic domains are all randomly aligned. But as the ferromagnet cools, the solution will snap into an align... |
- Since we can't bring up the Titanic, is it possible to preserve it? | [
"RMS Titanic is not just a shipwreck: it's a resting place for dozens, if not hundreds, of passengers that went down with the ship. Doing anything to the Titanic at this point is equivalent to messing with a grave. RMS Titanic has been preserved in many ways: books, television shows, movies, etc. Artifacts from the... | [
"[Voyager 2](_URL_1_) passed by decades ago and studied it in some detail but not as its own mission. There have been a few proposed missions (see farther down on the page) designed to study the atmosphere/weather, the rings, the moons, etc. Really it just comes down to funding for planetary science and what the c... |
What is the resolution of the human eye? | [
"There is no one answer. It depends on a vast number of factors, including ambient light level, how long it's been since the ambient light level changed at all, what it is you're trying to resolve, and of course huge variances from person to person. But the rule of thumb for a person with perfect normal-range visio... | [
"Pictures on TV screens and computer screens are made from a whole bunch of teeny-tiny dots of lots of different colours. More dots, all jammed really, really close together, means the picture looks better. 'Cause the dots are less noticeable. And there's way more details. That's hi-def. More dots."
] |
Why does viewing porn tend to make people horny, but watching someone eat doesn't make people really hungry? | [
"Clearly you've never watched *Diners, Drive-Ins, and Dives* late at night."
] | [
"I just explained this in another thread, but essentially it is called the \"Bernoli principle\" and like others have pointed out, it has to do with pressurized air. When you pucker your lips, air is pressurized as it leaves your mouth. When it leaves your mouth, it expands into the air and as it expands it absorbs... |
Why doesn't the army use the same camouflage used if hunting? | [
"Because deer notice things differently than people do."
] | [
"In a way, you have answered your own question when you link to the EMS article. Radio and light are simply two different sections of one continuous energy spectrum. If a media broadcaster were to send out signals in the visible spectrum, it would no longer be \"radio\" but visible light, and it would appear to you... |
Can a person who was born both deaf and blind communicate and be aware of their environment? And how? | [
"> Anne Sullivan arrived at Keller's house in March 1887, and immediately began to teach Helen to communicate by spelling words into her hand, beginning with \"d-o-l-l\" for the doll that she had brought Keller as a present. Keller was frustrated, at first, because she did not understand that every object had a wor... | [
"It depends on the job. You can't get a job as a truck driver and then demand that they don't make you drive for work. If you get a job where driving is not an important part of the work, there are probably reasonable accommodations that can be made. For example, if you got a desk job doing data entry, providing yo... |
Police officer vs Sheriff | [
"In most states in the U.S., Sheriffs are elected officials - people vote on the Sheriff for each county. Sheriffs are in charge of organizing and directing law enforcement activities for that whole county, which includes any law enforcement outside of city boundaries that have their own police, or coordinating iss... | [
"Follow up question: Aside from who was doing the courting, is there any major difference to how a Prince would be spending his time?"
] |
At the cellular level, what is happening when we get callouses? | [
"The friction causes the strateus corneum to develop."
] | [
"Because your body doesn't fully heal. It covers the area with tough collagen fibers, and the skin tissue does not grow to replace it."
] |
Why did the sr71 need to leak fuel on the ground due to expansion joints, but newer high speed planes like the f22 don't? | [
"The whole 50 years of technological advance nonwithstanding, the real answer is: The F22 is no way as extreme as the SR71, it can use regular fuel and don't need Titanium skin to deal with +300C temperatures. The SR71 fuel was used as coolant and lubricant, too."
] | [
"I'm familiar with this behaviour in blackbirds in the UK. It sounds as though the birds you describe are doing the same thing. You have correctly identified that not all birds do this - different species have typical responses to threats and flying fast and low is one such response. Unfortunately for the bird it i... |
Why does inbreeding create defects? | [
"We're carriers of genes with mutations (defects, in this case); this mutations however, oftenly don't show any sign. Since relatives share a higher proportion of their genes than do unrelated people, it is more likely that related parents will both be carriers of the same recessive gene, and therefore their childr... | [
"Those 2^n people are not all unique - one person can take up many \"slots\". Let's say your parents were third cousins. That would mean they share 2 of their great-great grandparents. Those 2 people are 4 of your great-great-great grandparents, appearing once on your mother's side and once on your father's side. ... |
Does the half life of a proton go up every year since we have never seen a proton decay? | [
"Our best guess at the half-life of a proton is infinite until we have reason to believe otherwise. If in reality protons decay and we don't know about it, the half-life is some extremely high number. It doesn't change, we just don't know what it is."
] | [
"The expansion of the universe is completely unrelated to the human perception of time. Perception of time is a very popular topic in many undergraduate and graduate university classes. The expansion of the universe is attributed to some unknown \"dark energy,\" whereas the human experience of time is just that: hu... |
How is the brain able to visualize rotations? | [
"Brains easily perform many, many tasks hat are difficult for computer. Take that we know brains are optimized for pattern-finding. Consider intelligent life forms have to interact with a real 3-world and real time. Which means they can check their expectations. Testings a supposition is as simple as rotating an o... | [
"Just like how we learn to walk by putting one foot in front of the other as babies/toddlers. Eventually your motor functions get so good at these \"menial\" tasks from repeating them so much that you don't need to think about every individual step, just where you want to end up. I'm no expert though."
] |
In carbon dating, why do we assume that the ratio of Carbon 14 and 12 in the atmosphere has always been the same? (or for the last 60,000 years) | [
"We dont, but if you would have an item that gathered carbon out of the atmosphere for the last few thousands years you could check how the ratio was changing. We use very old trees to do that, the oldest living one is around 6000 years old and It's a bristlecone pine. Also antarctic ice could be used to further an... | [
"> Why do doctors use 5 year survival rates for cancer? Is it because cancer rarely re-occurs after 5 years? Is it because cancer often comes back after 5 years? It gives a good indication of if the treatment will effectively extend the patient's life. Something like a year would be too short and a decade too long.... |
What history is known about pre-colonial North American Indigenous Societies? | [
"Your \"bit of a broad question\" has a bit of a broad answer! Broad questions are hard to answer. You might like to dive into the FAQ page [\"Americas Before Columbus and Native American History\"](_URL_2_) with dozens of discussions, though many of them are post-Columbus. You might also be interested in the AskHi... | [
"Try ask in /r/Archaeology and /r/AskAnthropology/. Those are the best groups to ask these type of questions."
] |
The Boltzmann brain theory | [
"The 2nd Law of Thermodynamics (which for our purposes says that the disorder in an isolated system can't go down over time) is statistical, not absolute. Over extremely large spans of time, the possibility of a fluctuation from a disordered to a more ordered state in any particular region approaches 100%. An etern... | [
"There is a controversial claim that a cold spot in the CMB (Cosmic Microwave Background) may be evidence of a parallel universe: _URL_2_"
] |
Can you catch someone by jumping after them out of an airplane? | [
"Yes it is possible, thanks to the air. The terminal velocity of an object depends on it's orientation as this affects the air resistance. Whilst falling, a skydiver can expose more (or less) of his body to the air, thereby altering his air resistance and therefore terminal velocity. i.e. a person will fall faster ... | [
"You're seriously overthinking this. If you know the initial velocity, you know the initial kinetic energy. If you know the current velocity, you know the current kinetic energy. Any difference between the two must be what's gained in gravitational potential, which you can then plug into the formula to solve for al... |
why do toenails grow slower than fingernails? | [
"Cool question! I'm going to make a guess that it has something to do with humans and pre-humans using their hands to grab, pull and otherwise interact with their surroundings, only occasionally stubbing their toes. If my dogs nails grow too long sometimes she will scratch things just because (or that's what it loo... | [
"The Theory of relativity. The same reason time seems to pass In a blink when you're enjoying a night with friends, yet seems to last an eternity during the last 10 minutes of work."
] |
Why don't your stomach contents come out of your stomach when you're upside-down? | [
"Long science words: gastroesophageal sphincter. Like you're five: the bottom of your esophagus closes up like a butthole to stop food from coming back up your throat."
] | [
"Get a protractor, tape or glue a straw to the straight edge, and tie a weighed down string to the middle. When you get on the plane, look down the straw at a star that you can easily pick out from the night sky (hope you're travelling at night!) and is viewable from both hemispheres, and mark where the string hang... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.