title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why are some roads made from concrete/cement rather than asphalt? What determines whether it should be one or the other? Why do a lot of the cement roads have grooves in them?"
] | [
false
] | null | [
"Cement roads are significantly more expensive. Asphalt is the cheaper option and actually has a better safety rating due to more traction. The grooves are used for better road traction or to extend the life of the road surface."
] | [
"Concrete roads are much more durable. For high volume roads where closing it to repave is a massive ordeal, concrete becomes the vastly superior option. In the long run, this makes concrete cheaper than asphalt."
] | [
"Asphalt is cheaper but concrete typically lasts longer. Usually a life cycle cost analysis is performed based on traffic loads to see what is cheaper in the long run. Other factors can come into play -high volume truck routes usually need concrete vs a residential street where road noise is a factor will usually f... |
[
"What is stopping this ball from falling?"
] | [
false
] | Playing in the bath with my baby. This cup full of water seems to exert some kind of suction on the ball. The ball is plastic and hollow. What is counteracting the force of gravity? | [
"Air pressure.",
"When the ball tries to drop, it increases the volume of the inside of the container. There is no new material getting in, so the pressure must drop (the same amount of stuff in a larger volume.) As the pressure drops, air from outside the container tries to rush in. It pushes on the container... | [
"Thanks for the answer!"
] | [
"Yes. Imagine an extreme of a bowling ball. It would pull down and make a pressure drop till air snuck in and broke the seal"
] |
[
"A follow up on neutrinos."
] | [
false
] | null | [
"Basically, everyone is still pretty sure that something is wrong with the OPERA experiment (including the OPERA people) but nobody really knows what.",
"It would take other neutrino experiments around the world observing the same result to really shake things up."
] | [
"Okay, that works for me. Thanks. "
] | [
"Up in the air."
] |
[
"[Evolution question] Why, after many generations of evolution, do two species established from the same ancestors become unable to reproduce together?"
] | [
false
] | I'm using the example of Darwin's finches. Unless this video is incorrect, it explains that the two "new" species of finches that derived from the original became so different that they were unable to reproduce together. How does this work? Video for reference: | [
"Consider the ",
"Dobzhansky-Muller model of speciation",
". Let's reduce the whole organism to two proteins, A and B, that MUST work together properly for the organism to survive. We start with one population. Due to stabilizing selection, neither A or B can change very much in the population, so everything... | [
"Outside of very large mutations such as an extra chromosome or something, it is generally a gradual change."
] | [
"Outside of very large mutations such as an extra chromosome or something, it is generally a gradual change."
] |
[
"A lot of cold and flu medicines (e.g. Lemsip) contain caffeine. What are the benefits of including caffeine? and what are the physiological involved?"
] | [
false
] | null | [
"Primarily, it combats drowsiness in medicines that boast that they are non-drowsy."
] | [
"Caffeine has a potentiating effect on painkiller and paracetamol in particular. ",
"http://www.ncbi.nlm.nih.gov/pubmed/10963764"
] | [
"In fact, caffeine is a vasoconstrictor (causes contraction of blood vessels) that reduces sinus congestion."
] |
[
"Are 'smart' people just able to recall information better and faster than 'dumb' people or is there more to it?"
] | [
false
] | [deleted] | [
"First you have to define what you mean by smart and dumb. If you mean, as you said, the ability to recall information then that's just a function of how much information you've taken in",
"If you mean intelligence, then that has more to do with the ability to learn. For example somebody with a high IQ (150) but ... | [
"Seconding the fact that you have to precisely define \"smart\" before you can make any sort of comment about it. There are many different ways to consider someone smart.",
"Some people have better memories, some people are able to connect information better to solve problems, some people see patterns more easily... | [
"Hi there!",
"For psychologists and neuroscientists, intelligence is assessed by a number of given tests that we think is representative of intelligence.",
"Most of the theories behind it will agree on the fact that \"intelligence\" as we measure it is: part \"cristallized intelligence\" (knowledges, measured b... |
[
"Do you trust the expiration dates on your purchased foods?"
] | [
false
] | Some time ago, several of us cleaned out a house to prepare it for being sold. We generally divided up the stuff, including the "unexpired" foods. One of us demanded that everything be thrown out if it's expiration date had passed. To some extent, I believe these dates are set by marketing types to increase sales - for... | [
"Most of them are shorter than strictly necessary to reduce the probability of the product going bad within date, and the company getting sued."
] | [
"It depends on the product you are talking about and what you mean by 'expired'. Do you mean the quality (taste) of the product is bad, or if by consuming it you get sick (the product is bad for you). Those might entail two different \"expired\" dates. Expiry dates are set up so that most of the products will expir... | [
"Actually, I was referring to the date printed on the packaging. I do realize that some foods do change over time (for instance, foods that contain oils) as the ingredients break down; and I do realize you can't calculate exactly when a product will become less than satisfactory, and the company would want to \"ex... |
[
"Explain something awesome about your field of study."
] | [
false
] | null | [
"(not a mod) This is a bit off topic, and we try to avoid open-ended questions like this here. ",
"But try ",
"/r/askscienceama",
". Find a post there that you are curious about and ask the same question. It's an AMA forum, so go for it."
] | [
"Klenow is correct, while interesting, we discourage posts like this and I removed it. All the best!"
] | [
"Okay, thanks anyway!"
] |
[
"We know the Earth is not perfectly round. Why do we not ever see it in any photos?"
] | [
false
] | Is it just to negligible? | [
"The difference between the equatorial diameter and the polar diameter of the Earth is only about 0.3%. This is too small to notice by visual inspection of a photo."
] | [
"In other words, if you have a fairly standard \"web resolution\" 1000x1000 pixel photo of the Earth on your screen, the difference is three pixels or so."
] | [
"This is a demonstration that the Earth is round, the OP asked why we don't notice that it is/isn't PERFECTLY round, i.e. why don't we notice that it's an oblate spheroid and not a perfect sphere. The answer, as ",
"/u/Rannasha",
" said, is that it's only 0.3% oblate."
] |
[
"How is the width of the blade of a wind turbine optimized?"
] | [
false
] | The blades of a wind turbine are so skinny and I was wondering why! I'm sure there's a perfect balance between wide with capturing more energy and skinny which reduces wear over time and decreases weight but I'm curious as how these two come into conjunction | [
"The skinnier the better. An important measure in the performance of an aerofoil is the aspect ratio; its span divided by its chord (length by width) roughly. The higher the aspect ratio the greater the potential lift to drag ratio. This latter ratio is important, because lift is what you want and drag is what you ... | [
"That is what I was referring to too; width is what aerodynamicists call chord, the distance from leading to trailing edge.",
"A blade with longer chord will have more drag which is detrimental to performance."
] | [
"Oooh, so that must be why glider plane wings are so long yet thin, thanks for such a detailed explanation."
] |
[
"What is cuteness aggression and what purpose does it serve?"
] | [
false
] | [deleted] | [
"According to the study that coined the term \"cute aggression\"",
", the phenomenon may be a coping method to vent the feelings of extreme giddiness and elation that come from seeing something that is extremely cute.",
"This has not been confirmed, however, only suggested as future research by the team that in... | [
"That feels correct. Like the issue is that my emotional energy has to go somewhere, and since I can't cuddle the kitty, I need to use a large burst of energy doing something."
] | [
"It may also have something to do with the need to \"reset\" emotions to a more personally appropriate level. As with the OP, he's comfortable in a \"manly man\" role, which \"shouldn't react to cute things\". He may use cute aggression to regain a congruent self-image. "
] |
[
"What exactly are tensors?"
] | [
false
] | I recently started working with TensorFlow and I read that it turn's data into tensors.I looked it up a bit but I'm not really getting it, Would love an explanation. | [
"The word \"tensor\" is overloaded in mathematics, statistics, and computer science. In this context (TensorFlow, and data science more generally), tensor usually just refers to an array of numbers (which may be higher dimensional than a vector or a matrix, which are 1- and 2-tensors, respectively). This is similar... | [
"The other explanations given here are good, but some historical context might help. The word \"tensor\" was originally used to describe the stress forces (e.g., the tension) experienced in a material at each point. Picture a tiny cube with 6 surfaces. On each surface, there are three forces acting: a perpendicular... | [
"Pedantically, I'd like to point out that the thing you described is actually a tensor field - physicists just call them tensors because they're lazy."
] |
[
"How practical is harvesting geothermal energy as a significant renewable energy source?"
] | [
false
] | null | [
"It really depends on where you are. ",
"Iceland",
" generates about a quarter of its electricity from geothermal - but it's also a really volcanically active region."
] | [
"The ",
"Philippines",
" is another example of a country with a decent percentage (Wiki says 17%) of its electricity generated by geothermal plants (and about 24-25% of its electricty by ",
"hydroelectric plants",
"). "
] | [
"Yep. Note that the Philippines lie in the Ring of Fire on a tectonic boundary, and are quite prone to volcanos and earthquakes, and whatnot."
] |
[
"How much progress has been made in identifying the \"missing\" carbon sink in the last few years?"
] | [
false
] | I remember from an undergraduate ecology course I took in 2012 that there is an apparent deficit between projected and measured CO₂ levels in the atmosphere and oceans. As I understand it, these projections were based on known and predicted amounts of CO₂ emissions from both anthropogenic and nonanthropogenic means as ... | [
"I assume what you're talking about is the fact that when calculated individually, global carbon fluxes into and out of different carbon reservoirs were not adding up to equal the observed atmospheric changes (i.e. we should find that dAtm/dt = dOce/dt + dTerrestrial/dt + dHuman/dt).",
"I can't remember the origi... | [
"If I understand the passage in section 2.5.1 correctly, it seems like they have deliberately rolled any missing components and biases into the land sink term, and justified that by comparing the result against a dynamic model of global vegetation. ",
"SLAND = EFF + ELUC − (GATM + SOCEAN).",
"Thanks for this."
... | [
"Off topic or unsubstantiated comments are hidden by a bot or the moderators but still show in the count until they are approved or removed. "
] |
[
"Why didn't the European settlers of America contract terrible diseases?"
] | [
false
] | As most of us know, when European settlers came to America, they brought with them diseases, such as smallpox, that created epidemics among the Native American population. Why didn't these settlers succumb to similar epidemics that the Native Americans had built immunities to? | [
"As far as I know, diseases like that did not exist very much in the Native American population. Europe was a great breeding ground for multiple reasons: It had a denser population that the Americas, diseases that started as isolated cases were quickly spread by war and trade, and the Europeans also used more domes... | [
"These explanations are spot on."
] | [
"There's some decent evidence that syphilis was originally a new world disease, actually."
] |
[
"What are the chances that probes that were sent out of the solar system, like the Voyager-1, will hit a space body, and how long would it take until they crash into something?"
] | [
false
] | [deleted] | [
"The odds are so low and the time-scales so long that the universe gets ",
" before the odds become reasonable.",
"So, a star system is utterly dominated by its star - not only is the Sun 100x larger in surface area than Jupiter, it also has 1000 times the mass and hence much stronger gravity. So you're much mo... | [
"That is correct - they will coalesce into a new (probably elliptical) galaxy, but very few (if any) stars will actually collide."
] | [
"That is correct - they will coalesce into a new (probably elliptical) galaxy, but very few (if any) stars will actually collide."
] |
[
"How is the temperature of objects like the ISS or a space walking astronaut regulated without anything to transfer heat to."
] | [
true
] | [deleted] | [
"It's liquid cooled with ammonia.",
"The ISS has aluminum radiators mounted to it. Convection is obviously a very potent form of heat transfer, and isn't an option in space, but heat is still radiated into space in the infrared part of the spectrum without it.",
"If you look ",
"here",
" you can see them be... | [
"This is correct. To add to it, there are also very strict requirements regarding how much heat stuff built for ISS is allowed to generate. "
] | [
"Well the idea is that while space is cold and the ISS can be very hot, there's no way to take the heat from the ISS and put it into space through conventional means. ",
"The reason that you feel cold when you're outside on a cold Winter's day is that the air is touching your body and you're heating the air. Simi... |
[
"Why do people revert to their native tongue/accent when they're very angry?"
] | [
false
] | null | [
"In my opinion, when you're angry and speaking, the emphasis is more on getting all of the words out as fast as possible to convey your emotion. No matter how fluent you become, a second language introduces a barrier and requires a certain amount of decision-making and focus, especially where grammar is concerned.... | [
"This doesn't answer your question, but I see nobody answered so... I don't think what you say is exactly like that. I have lived in different countries, speaking different languages, and I tend to swear in the local language. Even when I'm alone, or back in my home country... This happens also to people I know who... | [
"Maybe not so scientiffic, but I have talked to one person doing this and he said \"To show that I was being serious\".",
"\nTo back it up by some science, in \"Understanding the Mysteries of Human Behavior\" book, there was a topic suggesting that a lot of people get angry when they feel they're not taken seriou... |
[
"Is it true the fastest exit direction from our galaxy is toward Polaris?"
] | [
false
] | My dad told me this the other day and, if it is true, it seems like a remarkable fact. I haven't been able to support it with anything other than that the galactic plane is roughly 63 degrees and earth's axial tilt is roughly 28.5 degrees, which is nearly orthogonal if both tilts were in the same direction. | [
"If by fastest exit direction you mean a direction perpendicular to the galactic plane, then no.",
"The angle between the Earth's orbital plane and the galactic plane is 60.2°. A path perpendicular to the galactic plane would have to make a 29.8° angle with the Earth's orbital plane. But the Earth's axis is tilt... | [
"There is no reason for these planes to align."
] | [
"That's completely negligible. The galaxy rotates once in 200 million years (at the orbital radius of the Sun)."
] |
[
"What causes \"red-eye\" on photographs? And why does it affect some people and not others?"
] | [
false
] | [deleted] | [
"It's a reflection of the flash off the retina at the back of the eye. ",
"http://en.wikipedia.org/wiki/Red-eye_effect",
"It can vary in different people because of the makeup of their retinas. Some people have more or less melanin in their retinas, making them more or less susceptible to red-eye. It also depen... | [
"also it is a very directional affect. if someone isn't looking directly at the camera the light won't be reflected back at the camera."
] | [
"Some people are just more or less sensitive to light than others. If you aren't as sensitive, your pupils won't constrict as easily."
] |
[
"Why do I like music? Why do I like to dance?"
] | [
false
] | Viewed objectively, music is a very strange phenomenon. If I came from another planet to earth, I would find it very odd indeed that a semi-regular wave of air when formed into very specific patterns, would cause humans so much pleasure. I would be even more bewildered to notice that at nights, they often gather and f... | [
"It seems you have questions that half of the music cognition and psychology world is actively probing. Obviously I don't have your answer-- no one does at this point. I have a few points I'd like you to ponder once I'm not sitting in the longest meeting of my life, so I'll return to edit this reply in several hour... | [
"Science has answered some pretty complex social behaviors, so why not this one? It's certainly not simple to apply the scientific method to near universal behaviors like our appreciation for music, as it's not feasible or ethical to test every hypothesis out there. But often you find rare individuals born with a... | [
"Hearing is not a necessary faculty to have a valid musical experience.",
"I look forward to hearing more about that."
] |
[
"Quantum entanglement and Einstein"
] | [
false
] | From some reading about I've been doing I understand that when the spin of an entangled particle is altered, the other entangled particle's spin is also changed instantly. But didn't Einstein say that nothing (including any information) could travel faster than the speed of light? Does this still present a problem to p... | [
"No. Entanglement doesn't work that way. It's more like cosmic bookkeeping.",
"Entanglement more or less says, well... imagine you have two quantum coins A & B, each in a superposition of both heads and tails. So now it seems like there're four possible observations: HH, HT, TH, HH.",
"Entanglement is basically... | [
"I kind of makes sense.",
"So when you change the state of your coin, am I right in thinking that an observer observing the second entangled coin can't tell that the first coin has changed state?"
] | [
"Correct. Entanglement effects are generally observed by, after the fact, bringing the entangled objects (or data about them) together.",
"(So if the observer has access to data about ",
" coins, then they can see the difference. Also, really, once either observer makes an observation of their coin, they're ess... |
[
"If I were to bring a full can of soda on a dive in the ocean, how far down would I have to go before the can ruptures/collapses?"
] | [
false
] | Hi AskScience! I was having an argument with my friend about at what depth a can of coke (or some other soda) would collapse due to the pressure of the water pushing against it. He reckons it wouldn't last past 30 metres, but I think it would last considerably longer. When I say full, I mean a regular unopened can, so ... | [
"Yes, only the little bit of gas in the can would compress an appreciable amount. Open a can, squeeze the sides until the soda just starts to overflow. That's how much the can would be crushed at extreme depths."
] | [
"Yes, only the little bit of gas in the can would compress an appreciable amount. Open a can, squeeze the sides until the soda just starts to overflow. That's how much the can would be crushed at extreme depths."
] | [
"The internal pressure of soda cans is around 30 psi. At 20m that pressure would be equal on the inside and outside."
] |
[
"How do hot objects cool off in vacuum?"
] | [
false
] | As I understand it, high-energy matter cools off as the energy is transferred into adjacent, lower-energy matter. But if this is all there is to it, objects in vacuum would not lose energy... | [
"They can emit photons, for one. Energy can bump electrons to higher energy states. Upon relaxation they emit a photon (e.g. in the IR). No mass loss, just energy from the system."
] | [
"No mass loss, just energy from the system.",
"That is the same thing. The photons have no mass, but as they carry energy away from the object, the object looses mass equivalent to that energy."
] | [
"Black body radiation. The Sun technically is in a vacuum."
] |
[
"Does preventing evaporation on canals and reservoirs increase the ambient dryness/negative environmental impact overall over the long term?"
] | [
false
] | I've been looking at things like using and other man made structures for water, in addition to technology just meant to reduce evaporation. I see a bunch of figures like "decreases evaporation by x%" and it's being peddled as a solution to water crisis in dry areas (now made dryer due to climate change). What I don'... | [
"I think you are underestimating several very large quantities. Surface area of the earth covered in water, volume of the atmosphere, the amount of water in the atmosphere at any given time, and the sheer amount of energy striking the surface of the Earth every second. These are big, huge, human-brain-defying conce... | [
"Great explanation. I also want to add the amount of moisture in the air, even on clear days, is massive. Really massive."
] | [
"Rain clouds are born in the ocean",
", not over the land.",
"Rain in California originates in the Pacific Ocean. ",
"Irrigation channels are tiny compared to the ocean. Those channels barely affect the local microclimate near the the channel; they don't significantly impacting soil moisture more than a few... |
[
"When a black hole is formed, what happens to the matter that was crushed to create it?"
] | [
false
] | null | [
"Well it's not 100% sure but basically that matter is the black hole, it's what is creating the huge gravitational forces that are pulling more stuff to it. The matter basically becomes super dense but it doesn't disappear."
] | [
"Doesn't it all end up in the zero volume singularity at the center of the BH ?"
] | [
"It's not actually a zero volume singularity, that just wouldn't make any sense in physical terms. As you may know, atoms normally are 99.999% empty. There's a tiny nucleus in the center, and some electrons waaay out there. In a black hole, the gravity becomes so strong that it tears up this normal structure of ato... |
[
"What is the estimated computational power required to simulate a planet, system, galaxy, or universe?"
] | [
false
] | This would include simulation of everything from atoms to life. Obviously current computers will never be able to do this. But would quantum or DNA computers be able to handle it? | [
"It depends how much detail you would want in the system. Simulating down to particle scales for only one fundamental particle would take computational power on the scale of the universe itself. To simulate even a few dozen particles grows this bound exponentially as you have so simulate an N-body problem for all... | [
"There are a couple answers:",
"It's impossible no matter how small the simulated object or how big the computer. The universe is probabilistic, not deterministic, so you can't simulate it and expect the simulation to produce the same results as the universe. ",
"Ignoring the above, informationally speaking, it... | [
"According to ",
"this",
", the information content of the human brain is around 10",
" bits. That's a lot of bits. A back-of-the-envelope guesstimate is that there are around 10",
" or so bits in all the digital hardware on earth. "
] |
[
"What does the G tense in the Einstein field equation stand for and why does it have two other variables assigned to it?"
] | [
false
] | I recently encountered the field equations of Einstein as I was inquisitive about the expansion of the universe. Unfortunately for me I dont have an in-depth of physics (yet). I am a high school student. I was able to understand most of the variable components of the formulae but I have trouble understanding the G and ... | [
"G and T are 4x4 matrices, and the two letters (usually mu and nu) indicate an element of the matrix, the mu'th row and the nu'th column (or vice versa). I'm going to use superscripts instead of subscripts and ab instead of munu. G",
" is more often written as R",
" - Rg",
" . T",
" is the stress-energy ten... | [
"This is a great answer, I just have to nitpick. ",
"G_ab and T_ab are (0,2) tensors, not 2x2 matrices. G",
" and T",
" are (2,0) tensors. Since they're in these forms, we can represent them as a matrix (G _ab) and its inverse (G^ ab), but that's not actually what they are. ",
"This is especially apparent w... | [
"Tensors seem like pretty arbitrary objects if for higher dimensional tensors, they can never be represented with any numbers."
] |
[
"Why did you become a scientist?"
] | [
false
] | Scientists of reddit, how did you make the decision to become a scientist? I just completed my sophomore year of college and I am studying astronomy-physics. Often, I am asked how I chose this path. Usually, others wonder why I didn't enter engineering, a path with much more job security, etc. While I have answers to t... | [
"The short answer is that I had a pile of questions. When I went to find the answers, it turned out no one had answered them, so I figured I had to do it myself. And here I am."
] | [
"I entered the field of neuroscience mostly because I checked the wrong box on a form once. "
] | [
"Lack of foresight. :-)"
] |
[
"Are all of the fossil fuels on and in earth made up of carbon dioxide that was once in the atmosphere?"
] | [
false
] | I know that this may seem like trolling, but it is something that I have been thinking about since the 3rd year of my science degree. As this is such a politically charged subject, I want to make it clear that I am not trying to dispel human-caused climate change, but ask a question that I came up with while I was pond... | [
"Short answer: yes.",
"Way back (4 billion + years ago) the atmosphere was 25% CO2. The CO2 dissolved into the oceans and then formed carbonate rocks. From there it worked its way through rocks, soil, and life, to eek back into the atmosphere just barely.",
"For perspective, C is distributed on our planet like ... | [
"Must fix second link!"
] | [
"the atmosphere hasn't seen CO2 like this for awhile, and back when it was last like this, the earth was quite different.",
"My standard post on this (should not be taken to reflect any exact CO2 percentages - )",
"St. Louis during a period of a high-CO2 atmosphere - ",
"http://www.scenicreflections.com/files... |
[
"Under what conditions does a flamable vapor cause and explosion rather than just burn? (I'm thinking of the Buncefield Disaster)"
] | [
false
] | I've been watching the video of the Buncefield disaster and I was just wondering: if the gas was collecting around the bottom of tank 912, why didn't it just burn? What caused the explosion? Edit: sorry, title should read "cause explosion" | [
"In the same way you have the fire triangle, you also have the ",
"dust explosion pentagon",
". Gaseous fuel is a little different from fuel droplets or dust, but the same idea applies. You have well mixed fuel and air, which makes for a very fast reaction, and you have confinement that allows pressure to ris... | [
"This is a very good answer, the explosion pentagon is the ugly brother of the fire triangle. One quick nit pick though.",
"In the case of gasoline pooling in a tank, the mixing would probably be mostly from diffusion.",
"Buncefield happened when a gasoline tank over filled and spilled down the side. The vapor ... | [
"Thanks for the correction and extra insight!"
] |
[
"How do chemists dispose of the chemicals they make?"
] | [
false
] | I always wonder after watching clips where chemists create cool chemicals, and particularly when they make poisonous/dangerous chemicals, how they dispose of it afterwards. | [
"In all labs I've worked in, both academic and industry, chemical inventories are required as part of the environmental health and safety (EHS) plans. There are state and federal laws and they are often written to match international guidelines. Typically chemicals are reused if possible since they can be expensive... | [
"I'm honestly interested in how the companies the chemicals are given to dispose of them, whether they are recycled in some way, just stored indefinitely, etc."
] | [
"I'm honestly interested in how the companies the chemicals are given to dispose of them, whether they are recycled in some way, just stored indefinitely, etc."
] |
[
"Why is heart cancer so rare?"
] | [
false
] | Edit: Thank you all for your thorough answers. This is something I've wondered about for a long time. | [
"Heart cells are not rapidly dividing and regrowing. \nCancer is usually present in areas where there is rapid regrowth and rapid dividing. \nAlso a person with heart cancer would not live long, it would cause conduction abnormalities and improper pumping. \nFor cardiac cancer where it is a met, the heart is a diff... | [
"That is correct, it rarely happens to neurons. But the brain has a number of celltypes that surrounds and support neurons, most brain cancers originate from those. "
] | [
"That is not completely accurate. The lining of the stomach does in fact get replaced but not to prevent damage from acid. Damage from acid is reduced and prevented due to the secretion of alkaline mucous from the lining of the stomach.",
"But with that said, stomach cancer isnt unheard of, and the rates are actu... |
[
"If humans were much smaller, (think Gulliver's Travels), would we have achieved moon walks/flight/internet? (X-post from /r/HistoricalWhatIf)"
] | [
false
] | null | [
"Before considering the difficulties of tiny boats crossing the ocean, the possibility of us evolving to the current mental state is quite low, because our predators wouldn't just be large mammals, but most of the animal kingdom. Rodents, insects, birds would all hunt the tiny us.",
"edit: mental state, not metal... | [
"Do you mean mental?"
] | [
"\\m/n",
"yes, that was a typo, mental, not metal."
] |
[
"Any beer drinkers/developers here? How exactly do those variously shaped glasses, cans, and bottles enhance the taste/aroma of certain beers?"
] | [
false
] | Many beers are served in their own distinctively shaped glass at the bar. It is said the narrowness or wideness of the glass affects the taste. Even on cans like Coors "wide mouth" can or miller lite's "vortex bottle" claim to enhance the flavors. Do these really affect the taste or is it simply marketing gimmicks? | [
"A wide opening at the top of a glass allows you to smell the beer more, which will enhance the flavor, whereas drinking straight from a can has you smelling the aluminum. Thicker walls (or even a stem) where you grasp the glass will minimize heat transfer from your hand into the beer, helping to maintain temperat... | [
"True, I do prefer drinking from glasses because I can smell the beer more.\nAnd I guess that's why some cans come with special lining and wide mouths; to maintain temperature and try to increase the aroma.",
"Now what's your take on miller's vortex bottle?"
] | [
"Vortex bottle is pure gimmick. As is the vented can.",
"Glass shape has an effect. Different glasses are used for different effects regarding aroma, carbonation and head retention, and pure aesthetics. This link explains some glassware shapes: ",
"http://beeradvocate.com/beer/101/glassware"
] |
[
"What causes the Congo River, the deepest river in the world, to be so deep?"
] | [
false
] | It's over 750 feet, how did it become so deep? And why aren't other rivers so deep? | [
"It's an interesting question that I couldn't find too much info on, but the best explanation comes from this ",
"paper (key bit is on page 463 in the 'Incision of Zaire Channel' section for those who can get past the paywall)",
". This paper is largely focused on the continuation of the canyon in the offshore ... | [
"That's the part of the canyon cut across the continental shelf mentioned in both my answer and the linked paper."
] | [
"Thank you for the awesome answer! So has to do with the sea level and lack of sediment, generally. You described it as a canyon, and it really is that, a canyon. I mean 750 feet down is very deep.",
"In central Texas, a river would likely never get this deep because we have limestone/granite close to the surface... |
[
"How do things like leaf bugs or certain lizards develop such accurate camouflage? How is the image of the leaf/tree bark etc. transmitted so accurately through genetics?"
] | [
false
] | Example: | [
"in general, camouflage morphologies arise like any other aspect of development. The DNA sequences that mediate them primarily arise in the regulatory elements of genes controlling development rather than at the level of the protein sequence. This then results in alteration of when and where certain genes are expre... | [
"Imagine if every year every man on Earth who didn't look like Clint Eastwood was executed. Pretty soon most male humans are going to be looking like Clint Eastwood, or humanity is going to go extinct. With animals that use camouflage for defense every single tiny increase or decrease in effectiveness is rewarded b... | [
"Thanks! So I guess it's more of a hit and miss thing with the patterns. That's kinda cool."
] |
[
"Why do IC engines produce low torque at low RPM?"
] | [
false
] | A typical NA IC engine generally has a symmetrical torque curve peaking in the middle of the rev range. The reasons for reduced torque at high RPM are clear to me - air flow restrictions, increased friction - but at low RPM I'm less certain. I know heat loss and exhaust resonance play a role, but this does not seem suf... | [
"Losses are part of the equation, but also consider energy input. You can burn a more or less fixed amount of fuel in a piston stroke. At lower RPM, less fuel is being combusted, so less energy is available to be captured as torque."
] | [
"It's a matter of optimization.",
"A combustion engine must be designed around a specific peak efficiency speed, which involves, among other things, timing, valve lift, combustion chamber geometry, and bore/stroke.",
"The further you get from that target speed, the less optimal the burn will be -valves might be... | [
"I think you're discounting how big of an effect the heat loss is. ICEs regularly dump on the order of 60% of the energy into the radiator.",
"To quote Internal Combustion Engines - 3rd Ed - Ferguson & Kirkpatrick: \"Engine performance maps generally have a single-valued minimum brake specific fuel consumption op... |
[
"Common cold and Coronavirus"
] | [
false
] | If someone in my household catches the common cold, does that mean: - they have not been practising social distancing? Or - they have not been washing their hands regularly? Or - someone else in the household has not been following the rules? If someone catches the common cold, could they just do easily have caught Cor... | [
"Short answer: if someone gets a communicable disease then they acquired it from another person. Social distancing and masking have drastically reduced normally seen levels for respiratory diseases.",
"This decrease has been seen in the Southern hemisphere regarding influenza numbers:",
"https://www.cdc.gov/mmw... | [
"Different viruses are different. Rhinoviruses (responsible for many colds) are more table on surfaces than coronaviruses and not well blocked by masks, while coronaviruses are. ",
"We detected coronavirus in respiratory droplets and aerosols in 3 of 10 (30%) and 4 of 10 (40%) of the samples collected without fac... | [
"I want to continue wearing a mask in shops in years to come, I think it is good to keep germs from spreading to others. Only thing is it only works if others around us do the same. Japan apparently wear masks when they're sick, it seems like common sense when you think of it.",
"I haven't caught a cold this yea... |
[
"What are the issues with geothermal power?"
] | [
false
] | Seems to me that a lot of power generation is done with a heat source driving a steam generator of some sort (coal, natural gas, nuclear, some solar) so why don't we use the heat of the earth to generate power? Would digging a hole towards the mantle just create a mini volcano or something? | [
"No one has mentioned induced seismicity yet. Earthquakes. Injecting water into the Earth's crust can alter the pore pressure of faults, causing small earthquakes. In Switzerland recently earthquakes related to a geothermal plant were so persistant and disruptive that the project was cancelled. The earthquakes in t... | [
"Geothermal fields do not last forever. One is essentially pumping water into the ground and harvesting hot water/steam; the inputs and outputs are connected by fractures in the hot rock. Over time the hot rock will cool to a point where it is no longer producing steam, requiring that new wells be drilled. In addit... | [
"Availability. ",
"Most of the populated areas of the world sit on the Earth's crust where it is too thick to reasonably access geothermal power. We could generate it in the locations it is available, but our transmission grid just isn't really up to the task of getting the power to the people, it's one of the ... |
[
"What is the name of the lab equipment where people stick their arms through holes in a panel of glass into gloves fitted to the glass to inspect something infectious?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"Your question is either commonly occurring or has been recently posted on ",
"/r/AskScience",
". It may also be answerable using a Google or Wikipedia search.",
"To check for previous similar post... | [
"You answered the question perfectly. Haha"
] | [
"Glad I could help"
] |
[
"What function does natural oil have as a part of the eco-system?"
] | [
false
] | Thank you for the answers. After some googlefu I found a couple of threads that asked a similar question: | [
"One might make the argument that it was, until modern day, an effective carbon sink. Given the theories on the origin of hydrocarbons (anaerobic decomposition of oceanic micro-organisms ",
"https://en.m.wikipedia.org/wiki/Fossil_fuel",
") that process may have removed some CO2 effectively from the atmosphere. ... | [
"The ecosystem?",
"There is a fauna of methane-consuming archeans and microbiota which depend on hydrocarbon seeps and emanations for survival. There also are some symbiotic macro-biota which host methanogens and are also dependent on naturally occuring hydrocarbons.",
"see:",
"https://link.springer.com/artic... | [
"I mean the latter. "
] |
[
"If our solar system was inside a nebula, would we know it?"
] | [
false
] | null | [
"Yes.",
"When we look at other stars and galaxies, that light has to travel to our telescopes through all the intervening interstellar medium (ISM) and, for extragalactic sources, the intergalactic medium (IGM). While the IGM consists almost entirely of a plasma of super-low-density ionized hydrogen and helium, t... | [
"The nebula would heavily extinct optical light, although infrared from other stars would still get through, as well as microwave and radio waves. The science of astronomy would probably have a very delayed start, since here on Earth we didn't even discover infrared radiation til the 1800s (though it was predicted ... | [
"I think the question is asking, if the Sol system were inside a dense nebula, say the Pegasus, would we know that there is more universe outside? Douglas Adams addresses it in Hitchhiker's Guide to the Galaxy, but his rendition is hardly scientific."
] |
[
"How is lepton flavor conserved in oscillating neutrinos?"
] | [
false
] | lepton flavor is conserved. Then how is it that neutrinos oscillate between the 3 flavors without breaking the law of flavor conservation? | [
"lepton flavor is conserved",
"It's not. And you found out why not.",
"If you try to apply this to e.g. a muon to electron+photon decay you get absurdly small branching fractions (10",
" or so, theorists don't bother calculating it more precisely because it's zero for all practical purposes)."
] | [
"It's the probability of this decay happening (relative to the sum of all options)."
] | [
"could you explain what you explain what you mean by branching fractions?(the original question is answered, thank you)"
] |
[
"Question about smoke"
] | [
false
] | [deleted] | [
"http://i.imgur.com/4jp17.png"
] | [
"That's nice, but I was a little disappointed when I figured out that it's a fan, not a smiley face."
] | [
"Have you ever used a bong?"
] |
[
"Why don't Chess AIs like AlphaZero always lead with the same opener?"
] | [
false
] | After watching a couple of videos of AlphaZero (Google's new AI) playing against Stockfish (the previous Chess AI champion), I noticed that AlphaZero played different opening moves each time. See versus . Why does this occur? Wouldn't the AI prefer to always start with the same optimal move? | [
"There are a few reasons:",
"The AI's evaluation function (i.e. the function which estimates how good a move is) might return the same, or very similar, values for multiple moves. In that case, the final choice might appear to be random. There may or may not be a pseudo-random number generator involved; sometim... | [
"Apparently Deep Blue was fine-tuned for Kasporov, but computers are now so good that these techniques are unnecessary. No human will ever beat a modern chess engine."
] | [
"Do the AIs have any sort of function that evaluate a player's history of playing (if it was someone who was famous). "
] |
[
"If gravity is composed of gravitational waves and if nothing can get out of a event horizon, how comes a black hole has gravity if its waves can not escape its event horizon?"
] | [
false
] | null | [
"There is a large difference between a gravitational wave and an arbitrary gravitational field configuration.",
"So the basic answer is that",
"If gravity is composed of gravitational waves",
"is a false premise. This is also where the difference between real and virtual particles lies in QFT, though that is ... | [
"Here is an analogy which can actually be made precise.",
"Imagine you have a bathtub filled with water and you take the plug out (also to get to the correct idealization you need to imagine you either have an infinitely large bathtub or you are refilling it without disturbing it as it drains). There will be a vo... | [
"Here is an analogy which can actually be made precise.",
"Imagine you have a bathtub filled with water and you take the plug out (also to get to the correct idealization you need to imagine you either have an infinitely large bathtub or you are refilling it without disturbing it as it drains). There will be a vo... |
[
"Would a 100Mt underwater nuclear detonation create a tsunami, if so, how big would it be?"
] | [
false
] | The 5Mt underground caused a seismic shock of ~7.0 on the Richter scale, but no tsunami. In of the test you can see quite a large area of the ground being lifted up to 25ft directly above the blast. The video also mentions that the ocean floor near the blast was raised by 4-6ft. According to wikipedia the earthquake th... | [
"2011 Tōhoku earthquake and tsunami",
"This earthquake released a surface energy (Me) of 1.9 ± 0.5×10",
" joules,[51] dissipated as shaking and tsunamic energy, which is nearly double that of the 9.1-magnitude 2004 Indian Ocean earthquake and tsunami that killed 230,000 people. If harnessed, the surface energy ... | [
"Very interesting, and surprising how little the blast would do. Though I wonder if Mehaute et. al. also considered nuclear explosions beneath the sea floor. If the sea floor suddenly rose a few meters as in the Cannikin test it would be more analogous to the movement of the sea floor during a thrust earthquake."
] | [
"There are going to be a lot of other things that will affect this, like depth of denotation, geography of the ocean floor, temperature, distance to nearest landmass, etc.",
"But for comparisons sake, let's look at the Indian Ocean Tsunami of 2004. While the surface energy was only 25 Megatons, the total energy o... |
[
"How long is a second?"
] | [
false
] | IIRC, for measurements like the kilogram we base it off the number of atoms of a specific element. How exactly do we come up with a uniform version of a second, since time is kind of more abstract than mass. | [
"It was originally 1/86400 the length of a mean solar day, however it was redefined such that a certain microwave emitted by Cesium atoms has an exact frequency.",
"The kilogram however is just the mass of a brick in France."
] | [
"A second is 299,792,458 meters long."
] | [
"There are actually 40 cylinders around the world that are used as the standard for the kilogram. Problem is, the mass keeps changing for all of them."
] |
[
"Is it common to have a different hair and facial hair colours?"
] | [
false
] | For example, I have brown hair and red facial hair, and I haven't really seen this before, so I was just wondering if this was more common than I thought. | [
"Hey, I have the same exact thing! ",
"Dutch by-chance?"
] | [
"German here. I see that in a lot of people from all over and it's always a red beard or a patch of red beard (that looks seriously weird) with a different hair color.",
"I found this:",
"Q: Why do so many men, despite hair colour, have ginger beards?",
"A: Beard hair is quite different to head hair; it is co... | [
"I have brown hair. My beard has grey, blonde, red, and brown in it. pretty much have every natural color on my body."
] |
[
"Which would be easier to build: A particle accelerator or a fusion reactor?"
] | [
false
] | Just out of curiosity, asking for a friend;) | [
"It depends on the technical specifications of the machines. You can build very simple accelerators or reactors in a garage.",
"Your reactor will not be anywhere near break-even, and your accelerator will not be particularly useful, but you can build them."
] | [
"Given that you can make a particle accelerator with some wire, magnets, and a power source, I'd say a particle accelerator. Also old fashioned CRT TVs are basically little particle accelerators."
] | [
"Building a device that causes fusion is pretty straightforward too: ",
"https://en.wikipedia.org/wiki/Fusor"
] |
[
"How can mirrors exist at all? Aren't all surfaces 'rough' at a molecular/atomic level?"
] | [
false
] | [deleted] | [
"For a mirror to work well, it just needs to be smooth on the length scale of the wavelength of the light it is supposed to reflect. Have you ever seen a ripple on the surface of a pool being reflected by the wall? The wave gets reflected just fine even if the surface of the wall is rough, because the roughness is ... | [
"For macrosopic phenomena, treating EM waves as classical waves is always the right thing to do. Trying to think about what happens with a single electron and photon is impossible. Thinking about constructive and destructive interference is really hard to do in the QED photon picture. IT is not impossible, we know ... | [
"You're right that a key factor in the performance of a mirror is the roughness of the surface compared the the wavelengths of the light it's reflecting. But your mental picture of what's going on is a bit off. What are these empty spaces between the atoms? Since,as you correctly note, photons interact with the ele... |
[
"Is there an objective way to measure pain?"
] | [
false
] | I imagine if there would each person would be given some values that determine their resistance to pain since some of us feel pain less than others, each one is different. How would you even go and quantify these things? Maybe the electrical signal is different depending on how you precive that pain. I found it really ... | [
"Pain is, by definition, a subjective experience. So no, there is no objective way to measure pain. If we could objectively measure pain, that would imply we had a full understanding of the biological mechanisms which give rise to the sensation of pain in conscious minds. We don't."
] | [
"I meant the electrical pulses of your brain, if we can somehow measure them maybe we'll see a pattern between pain precived by others"
] | [
"I don't think so at all; the way your brain interprets pain varies wildly person to person. Think about this: even your own brain, not comparing it to anyone else's, interprets electrical impulses that are supposed to be \"painful\" varies wildly situation to situation and in ways that are very hard to control. Yo... |
[
"How does my cat know to look me in the eyes?"
] | [
false
] | This may be dumb, but I find myself fascinated each time my cat seems to seek out my eyes when looking at me. Perhaps it's just my face she's looking at, because that's where the sounds come from? Or is eye contact just some innate, unspoken form of communication between animals in general? Thanks! | [
"Hi Kikujiro,",
"Dr. Nick Dodman (no, not the guy from the Simpsons), wrote a brief on cat communication by eye contact and blinking. ",
"This article",
" contains an abstract that is of relevance to your question.",
"tl;dr: \"On the aggressive end of ocular signaling is the stare. An irate cat will transfi... | [
"Closed for long periods of time... your cat is asleep, leave her alone!",
"Actually it means that if you poke it, it wakes up and makes a cute little mrrr"
] | [
"Well the question as stated can be broken down into:",
"A) \"Is it because that's where sounds come from?\" (No.)",
"B) \"Or is eye contact just some innate, unspoken form of communication between animals in general?\" (Yes, and specific to cats, see my answer.)",
"To answer your questions, briefly, based on... |
[
"Is the moon coming constantly a little bit closer to earth? If yes how long would it take to fall onto the earth?"
] | [
false
] | null | [
"Nope! It's actually getting ",
"farther away",
" by about 4 centimeters per year.",
"EDIT: Thanks!"
] | [
"You need to put backslashes before your end parentheses. You wrote",
"[farther away](https://en.wikipedia.org/wiki/Lunar_distance_(astronomy)#Tidal_dissipation)\n",
"which gave you \"",
"farther away",
"#Tidal_dissipation)\". You should have written",
"[farther away](https://en.wikipedia.org/wiki/Lunar_d... | [
"This will continue until Earth is tidally locked with the moon and the moon stays in the same part of the sky constantly.",
"It would continue until then if left alone. But it would take much longer than the Sun has left, so what will probably happen is it will move away until the Sun expands into a red giant, a... |
[
"What would it take to make a virus like Ebola or HIV airborne?"
] | [
false
] | On a molecular level, what evolution/modification/engineering would it take to make a virus like Ebola or HIV airborne? And if this was developed, what would be the easiest way to spread it to eliminate most of humanity? :) | [
"I think there already is at least one strain of ebola that is airborne, but is harmless to humans. Ebola Reston or something. Thank you Hotzone."
] | [
"Ahh so it's a trade-off between duration of infection and severity of infection?",
"Would it make sense to try to engineer a virus with less immediate effects to be more lethal or to engineer a virus such as ebola to have a prolonged duration of infection (but still with the same rates of mortality)?"
] | [
"Ahh so it's a trade-off between duration of infection and severity of infection?",
"Would it make sense to try to engineer a virus with less immediate effects to be more lethal or to engineer a virus such as ebola to have a prolonged duration of infection (but still with the same rates of mortality)?"
] |
[
"Elucidating Particular Neural Pathways through Early Gene Insertion"
] | [
false
] | I was reading up articles on tinnitus and it seems like there are a lot of theories but no concrete neural correlate has been elucidated. This has got me thinking, is it possible to inject certain cells at a particular period in embryonic development with a gene that helps code for something that can help with imaging,... | [
"Yes. This is a fairly standard technique, although not quite as easy as 'injecting' a gene. ",
"for complex organisms like mice, it gets decidedly harder to distinguish fine grain detail relative to something simple like a worm.",
"The basic idea is that you generate chimeric mice by injecting transgenic embry... | [
"Thanks for your reply. I see what you mean here. It wouldn't really help to have a chimeric mice though, as some neurons will be expressing one gene and other neurons expressing another, giving an incomplete picture. I guess what we need to to is introduce a mutation specific for neurons very early on in embryogen... | [
"It wouldn't really help to have a chimeric mice though, as some neurons will be expressing one gene and other neurons expressing another, giving an incomplete picture. I guess what we need to to is introduce a mutation specific for neurons very early on in embryogenesis so that all cells carry that gene, but only ... |
[
"Are we (humans) as physically (superficially) diverse inside as we are outside?"
] | [
false
] | [deleted] | [
"I heard an interesting stat recently, which is that if an anatomical feature is present in 40% of the population, it's included in anatomy textbooks. This means that 60% of people could not have a thing at all and it will still be included in a textbook. There are, for instance, lots of muscles like palmaris longu... | [
"Palmaris longus is basically useless. It's used for tendon grafts sometimes with no ill effect since its purpose is unknown and there are no adverse effect on the patient's health."
] | [
"I know you were not specifically asking about this, but since I am currently since I am currently studying this it was too tempting to not mention it. It is becoming increasingly more evident that everyone has a unique microbiota (term used to define the microscopic organisms within the human body) fingerprint\", ... |
[
"When sitting in a not warm room, what makes me sweat after playing an intense game of StarCraft 2?"
] | [
false
] | I've heard somewhere a long time ago that you burn calories when you sweat. Someone please explain this to me like i'm five. (No, im not gonna use that subreddit) | [
"When you are stressed, your body produces more of the so-called 'fight or flight' chemicals, which prepare your body for an emergency. These chemicals raise your blood pressure, increase your heart rate and make you sweat more. "
] | [
"This is correct. When in a stressful situation, your sympathetic nervous system is activated. This is the \"fight or flight\" branch of your nervous system, and causes all sorts of things throughout your body to occur, such as sweating, increased heart rate, increased blood pressure, increased respiratory rate, ... | [
"Thanks for adding on, I wasn't aware of all the details"
] |
[
"Calculating distance by sound with no known point or origin."
] | [
false
] | Hey , I was wondering about why sight is our main sense. It occurred to me that one of the reasons must be because we are able to calculate distances by triangulating. Regardless of this being a valid point or not, would it be physically possible to calculate distance to a sound without knowing it's origin? I.e., it is... | [
"http://en.wikipedia.org/wiki/Animal_echolocation",
"\n",
"http://en.wikipedia.org/wiki/Human_echolocation"
] | [
"I was wondering about why sight is our main sense. It occurred to me that one of the reasons must be because we are able to calculate distances by triangulating.",
"Sight is one of our adaptations that we share with most if not all diurnal animals. Our ability to perceive still objects as three dimensional is ba... | [
"Isn't it simplest to just say the Sun putting out tons of very strong light that reflects off everything is why light waves much better than sound? ",
"There is no strong consistent sound source that bounces off everything as there is usually for light. Sure a radar-like echolocation could be used (and is used... |
[
"Now that they've found the Higgs Boson, what will they be using the LHC for?"
] | [
false
] | I am under the impression that, while the LHC is used to pry into other matters, it's primary focus has been the search for the Higgs. Now that has been found, I've read many articles where physicists state that this is likely the last big discovery to be had in particle physics. I doubt that means exactly that nothing... | [
"First off, the Higgs boson hasn't been discovered yet. A particle that is consistent with a Standard Model Higgs boson has been observed, but the first order of business for the CMS and ATLAS collaborations at the LHC is to study the properties of this particle in more depth to see if it fully matches up with the... | [
"You look at the decay products and what their angular distribution is."
] | [
"You look at the decay products and what their angular distribution is."
] |
[
"Why do I feel tired if I've slept 8-9 hours in broken intervals?"
] | [
false
] | A lot of times I feel sleepy at around 7 or 8 pm, and I'll fall asleep. I'll sleep for, say, 3 hours and wake up. Then I won't be able to sleep again until 3 or 4 am, at which time I sleep until about 9 am. But when I wake up, I still feel really tired, even though I've slept at least 8 hours total. Why? | [
"The amount of sleep you get doesn't really matter, if the quality of said sleep is poor. In order to get good rest, you need plenty of deep sleep. ",
"Sleep Stages",
" By splitting up your 8 hours into chunks, you are interrupting this sleep stage cycling, and possibly preventing yourself from getting enough... | [
"Why do I feel tired after getting 8 to 9 hours of sleep, and I am forced to yawn every 5 minutes? "
] | [
"why do you claim the deep sleep is the most important? everything ive read says the light REM phase is the only important one or at a minimum, the MOST important."
] |
[
"When two unrelated people look a lot alike, do they actually a more similar genome than average, or are their similar looks completely coincidental?"
] | [
false
] | null | [
"Seems to me like you purposely ignored the wording ",
" spirit of OP's question just so you could answer something.",
"What about the specific similarities? Any two people from the same ethnic background share the genes relating to that ethnicity. But what about when someone looks like the spitting image of To... | [
"There's a big difference between races and ethnic groups. That study showed that race alone isn't a good indicator for genetic similarity, but geographical/ancestral history - ie ethnicity - is. ",
"Link for those curious",
".",
"A Xhosa isn't genetically similar to a native Somali, but ",
"/u/gatherinfer"... | [
"It is ok to drink too much on Saturdays, just start in the early morning so by the afternoon you are acclimated to the drunkenness."
] |
[
"What is the step above single-cell? Are there any 2-cell organisms? Any 5-cell organisms? 10-cell?"
] | [
false
] | null | [
"There are bacteria and fungi which are found in clusters of cells: 2, 4, 8. There are also organisms that can regulate their transition from a single to multi cellular, these are thought to be a potential link between single cells organisms and the regulation of cellular organization. ",
"https://news.berkeley.e... | [
"Yup, as asked, two cell organisms come next. Though they are not classified as bicellular organisms by some, (some say that they are joint unicellular organisms) I would say that if they are codependent, they are bicellular."
] | [
"The definition of multicellular organisms is that the organism is divided over population of cells in which each population is doing a specific function for the organism's survival.",
"Bacteria aggregate together as colonies / biofilms all the time, they are even sometimes conjoined together (cocci bacteria for ... |
[
"As a child, I always heard that spider webs are extremely strong. I often heard it said that a spider web the thickness of a #2 pencil, and large enough length wise, would be strong enough to stop an airplane in mid flight. Is this true? What would it take if not?"
] | [
false
] | null | [
"Well, the answer really depends on the type of plane that we're talking about.",
"There are two factors to consider. ",
"First, would such a thread of silk have high enough tensile strength to hold against the thrust of the engines. The Rolls Royce Trent 1000 turbojets on the Boeing Dreamliner can produce up t... | [
"The toughness is the area under the curve of the Stress/Strain plot. I approximated it as a triangle: (1/2 * height * width). Height is 1.3e9 Pa, Width is 30% extension (0.3)."
] | [
"I recall reading that scaled up spider silk would not be as strong because the thicker material would not be able to shed the heat from its deformation and would break because of that."
] |
[
"How is excess protein stored in the body?"
] | [
false
] | Both fats and carbohydrates are stored as fat in the body. What about protein? Is it also converted to fat? | [
"Excess protein is not stored. It is simply excreted as waste.",
" In fact, excessive consumption may cause, over time, bone density loss and kidney stones.",
"Also carbohydrates are actually not only stored in fat. Liver and muscle tissue store glucose in ",
"long chains called glycogen",
"."
] | [
"Unfortunately, no. The previous response was a little oversimplified. What is excreted when you consume excess protein is the Nitrogen component of the amino acids (in the form of urea). The remaining carbon backbone can be oxidized or converted to glucose/fat, depending on the amino acid. (Some amino acid backbon... | [
"The proteins don't just get excreted, intermediary metabolism is a little more complicated than that. The gist of it is that proteins - or the amino acids they are consisting of - lose energy to your system, be it over gluconeogenesis or production of acetyl-CoA. Excess proteins (excess over the \"storage capacity... |
[
"Why is Methane such a powerful greenhouse gas when it's absorption spectrum for terrestial radiation seems so narrow?"
] | [
false
] | So I've recently come across these graphs on some of these global warming conspiracy websites. They seem to show that Methane has pretty small absorption peaks in the terrestrial radiation spectrum compared to something like CO2 or water vapor. Since it's also much less prevalent in the atmosphere it seems unintuitive ... | [
"Good question. Two-part answer, but first an important background concept: greenhouse gases only absorb certain wavelengths of light, and each GHG is active in a different set of wavelengths. ",
"1) The more of a greenhouse gas you add, the less effective it becomes. Once you've added enough to strongly absor... | [
"It seems that it’s both due to the absorption in the more energetic part of earth’s spectrum as well as the propensity for methane to produce other greenhouse gases such as water vapor and CO in the upper atmosphere, where they normally would not be concentrated otherwise. While water vapor has a higher degree of ... | [
"So one way to reduce the radiative forcing of methane would be to... add more of it.",
"Yes, but more is always worse: it just gets ",
" worse the more you add.",
"Is there any remaining \"window\" in the spectrum where a hypothetical gas would have an enormous forcing?",
"Yes. In particular, there are ga... |
[
"Why is a birthrate of 2.1 for a country important for its economic growth? Why wouldn't the correlation be that economic growth leads to population growth?"
] | [
false
] | null | [
"In developed countries, a fertility rate of 2.1 children per woman is necessary to maintain population at a given number. In less developed countries, and countries with female infanticide, the fertility rate must be higher than that to maintain population.",
"Fertility and economic growth are not well correlate... | [
"economic growth spurs population growth",
"It can go both ways, ",
"depending on the stage of development the country is in",
".",
"Early economic growth tends to focus on reducing the death rate by stabilizing the food/water supply, reducing infant mortality, and eliminating preventable deaths through dis... | [
"So let's see if I remember this correctly..",
"economic growth spurs population growth",
"It's the other way around - families in poorer societies have more children. Imagine, for example, ghettos and such. There are several factors and I don't remember them all, but it has mostly to do with family support - a... |
[
"how our brain/eyes distinguish a blurred picture from a not focused object ?"
] | [
false
] | null | [
"Your eyes are focused on the plane of the picture (which the brain does automatically and knows fairly accurately based on not only visual cues but also on proprioceptive feedback from the the relevant muscles ) but the picture isn’t sharp. Contrast detection is one of the main feedback mechanisms in focusing but ... | [
"Context clues. Your brain knows it's looking at a picture based on your current situation or experience (image is on a flat piece of paper held by your own hand, for example). It also knows if you are looking out into the world and constantly changes the eyes' focus based on what you want to pay attention to - it ... | [
"The complexity is impressive. Thank you for the answer :)"
] |
[
"Why do thicker strings (of a guitar) produce relatively lower frequencies?"
] | [
false
] | I am aware that thicker strings have greater mass and thus make the wave travel slower. As wavelength is constant, frequency must decrease. But why exactly does a thicker string make the wave travel slower? | [
"You kind of answered it, more mass means less vibration due to the tension and mass combined versus air resistance and drag will create harmonic pitches much lower than a thinner one if tuned to a proper or standard tuning.",
"Also thin strings tend to be single strands or smaller coils on a smaller string. Thus... | [
"Lot of wrong answers in this thread. You're right, thicker strings cause lower frequencies, and it's because the wave speed is slower. ",
"If you think about this it makes a lot of sense. A string is much like a spring attached to a mass, hitting it will cause it to oscillate but that oscillation frequency will ... | [
"Thank you!! So I am right to say as wavelength remains constant, frequency will decrease because velocity (vibration speed) decreases?"
] |
[
"Where does the energy go in a solar cell when it is disconnected?"
] | [
false
] | In a diesel generator, if you increase the load, you have to supply more fuel to keep the engine-generator turning at the same speed. Accordingly, if you electrically disconnect the generator, the engine has to burn less fuel or it will overspeed. With a solar array, if E amount of energy is hitting the panel, some is ... | [
"The temperature of the solar cell would be higher from the insolation. Due to the higher temperature there would be more heat transfer (the energy that would have been converted to electricity) to the atmosphere in the form of IR and conduction and convective heat to the air around the cell."
] | [
"No, this would mean that it would work like a capacitor, storing energy"
] | [
"It either ends up as heat, or re-emitted as narrow band IR at the wavelength of the cell's band gap.",
"The heat answer is pretty straightforward, so I'll describe the other half of the answer.",
"A solar cell is basically just a big flat ",
"PN junction",
" diode. Any semiconductor diode, in fact, will ha... |
[
"If, theoretically, you were in an infinite sized room, and there was complete darkness. If you lit a candle, how far away would you have to be from this candle before you couldn't see it?"
] | [
false
] | [deleted] | [
"You're basically asking what the limits of human vision are. And you're in luck, there was a ",
"paper",
" published this summer answering that question (",
"summary here",
"). The tl;dr of the paper is that the human eye can detect a single photon. If it happens to be one of the 10% of photons that enter ... | [
"The illuminance of a candle (1 candela or 12.6 lumens) from a distance of 1 meter is 1 lux. That of the dimmest stars typically visible to the naked eye on a dark night (magnitude 6) is 8e-9 lux. So we just need to know how far away the candle needs to be to be as bright as a 6th magnitude star.",
"By the invers... | [
"I work in a photonics lab where we make novel detectors based heavily on how the human eye works. Let me tell you, nature is really freaking good at its job haha. These types of detectors (hetero-photo-transistors, if anyone is curious) are super hard to tune but I guess if you put enough space junk in a big open ... |
[
"What does a baby think when people talk to it?"
] | [
false
] | null | [
"During the first year or so they respond to the tone of voice rather than actual words, and I read somewhere they can recognize their mothers voice almost immediately. To infants, words just sound like a run on sentence of gibberish. "
] | [
"I'd imagine much the same as you do when you hear a foreign language. Over time, you'll pick out individual words and start making correlations to their counterparts in the environment. Until then, it's just nonsense. "
] | [
"Is this speculation? We should try to stick to actual studies of infant thought processes here."
] |
[
"Do any animals have 360 degree vision?"
] | [
false
] | null | [
"there are a couple of sharks i know of that do, scalloped hammerhead and bonnethead."
] | [
"Don't they have ",
" 360 degrees?"
] | [
"im sure thats it but the books ive read have said the do have 360. they are old books so"
] |
[
"I am swimming in a pool of water on the moon. How will the lower gravity affect the way I can swim?"
] | [
false
] | Assume I am in a 1 atm chamber so I can breathe freely and there is a large pool. Does the lower gravity change the rate at which I would float and sink in the water? Would the pressure of the water as I go down be affected such that I could dive deeper or swim up to the surface faster or more easily? EDIT 1: I just wa... | [
"pool story, bro."
] | [
"100% correct. The difference in buoyancy is 0 because density doesn't change. "
] | [
"yes on a high gravity planet you would accelerate much faster."
] |
[
"A quick question about magma"
] | [
false
] | Does magma flow beneath the Earth's crust in currents like the jet stream does above ground? | [
"The mantle is not magma though, it is solid."
] | [
"It does not. Magma is a much more local phenomena associated with local melting events (i.e., subducted crust at a subduction zone)."
] | [
"The important thing to realise about magma is that the biggest continuous volumes of it you find are in places such as chambers below supervolcanoes. Even then, if you consider the Yellowstone caldera, much of the volume is actually discontinuous, with separate parts of the chamber not directly interacting with ot... |
[
"How does your body know when to stop adding more blood after you donate or lose blood in an accident?"
] | [
false
] | [deleted] | [
"There are what are known as feedback mechanisms that control this. Here is a webpage with some details: ",
"http://www.merckmanuals.com/home/blood-disorders/biology-of-blood/formation-of-blood-cells",
"Here is an excerpt that explains a bit about how the body regulates how much of each type of blood cell to ge... | [
"I did not know that it was the bone marrow that produces the cells, I thought it was the kidneys all along. Thanks, I learned something today."
] | [
"Low levels of oxygen in blood lead to increased production of erythropoietin by the kidneys, which leads to an increase in production of red blood cells in bone marrow",
". "
] |
[
"Why are we the only country who has been to the moon?"
] | [
false
] | [deleted] | [
"lots of countries have been to the moon, though with robots.\nthere is no scientific or economic benefit of putting a person on the moon\nthe reason America did it was to boost national morale and spirit and what not\nthere is little motivating factor in being second"
] | [
"This is from 2006: ",
"China Plans To Land On Moon By 2024",
"."
] | [
"Additionally, there was a lot of scientific benefit when we did it, but it is superseded by the data we got and freely share and by the work now done by robots."
] |
[
"How did the hubble space telescope not move when talking this photo?"
] | [
false
] | In regards to this post. You would think that some sort of gravitational force would distort the photo and it would be blurry considering it was pointing at the same direction for 4months. Don't know if I'm posting this in the correct sub-reddit. Hope you guys could help =) | [
"The telescope did move. It was in orbit. It was kept pointed on the same area of the sky. At that distance, the difference in the angle from which the area is viewed when the hubble is on one \"side\" of the earth versus another, and even the much larger movement of the earth itself and the sun relative to the cen... | [
"Hubble is on a 97 minute orbit around the Earth, and it's not really possible to take images exposed for that long. I've never used HST, so I don't know the exact details, but I know you run into problems with the Earth getting in your way, pointing too close to the Sun, hitting the South Atlantic Anomaly, and all... | [
"The dark area was not close to the Moon, that's just for size comparison. It's actually in the constellation Fornax, in the southern celestial hemisphere."
] |
[
"If space is expanding, why has the Big Crunch been discredited?"
] | [
false
] | null | [
"Because we have an accelerating expansion, meaning that there must be a dark energy or similar component. ",
"Dark energy accelerates the expansion while matter slows it down. Moreover, the expansion itself dilutes matter and makes its density smaller while dark energy stays the same.",
"Therefore the expansio... | [
"Therefore the expansion certainly never stops accelerating, therefore it never slows down.",
"That conclusion doesn't necessarily hold. There are definitely models, which fit the data, in which the acceleration is just transient, and at later times the expansion decelerates. For example, this could happen if the... | [
"Yes, I was restricting myself to P = w ρ models."
] |
[
"How can a candle make oxygen?"
] | [
false
] | I was watching a show on submarines and they mentioned a chlorate candle that when burned release oxygen in emergency situations. My whole like i’ve known candles / fire to oxidize or use up oxygen. How can this candle generate oxygen? | [
"Chlorate candles, or oxygen candles, consist of multiple substances.",
"One of which is sodium chlorate (NaClO3). If you heat sodium chlorate to a sufficiently high temperature, it falls apart into NaCl and O2, producing oxygen gas.",
"The other component of an oxygen candle is something that can produce the r... | [
"You’re right, it does use some of the oxygen to burn. But these “candles” contain their own oxygen in the form of sodium or lithium chlorate. When heated, it breaks down into a salt and oxygen gas. Some of the oxygen is used to continue the burn, but there’s far more than can be used by the amount of fuel in the c... | [
"Since you are interested in submarines: There are some excellent videos on YouTube (channel SmarterEveryDay). In the most recent one, he explains how they generate oxygen also including these oxygen candles. The other commenters already did a great job. The videos might help visualizing it though.."
] |
[
"What are you favorite home physics experiments for kids?"
] | [
false
] | I guess a bit of Archimedes in the bath might work for younger kids. I remember looking at sunspots with binoculars and tracing paper. Anyone got some other fun experiments? | [
"Found him! This is the guy that's been wasting all that Helium."
] | [
"There is a fun one for pressure/temperature. Take a soda can & put a bit of water in the bottom. Boil the water by heating the can on the stove. Using tongs, submerge the top part of the can, upside down in a bowl of ice water. The can will collapse. There are some other fun ones, too, but my kids are ready for st... | [
"I built a small battery powered motor with my dad from a kit when I was a kid. I am 31 now and still remember it. It helped me understand electricity from a young age. "
] |
[
"How can the 1 ton Curiosity rover move if it generates only 120 watts of power (~2 lightbulbs)?"
] | [
false
] | The answer may be very obvious, but I was looking into the Curiosity rover, and I came across this info from NASA/JPL (sorry for the mobile link) I thought most lightbulbs were like 60 watts. How can a one ton rover move with the power of just two lightbulbs? Even with reduced gravity, that seems exceptionally low. | [
"I'll throw this in just to put some things into perspective...",
"You don't need a lot of power to move something heavy if you move it slow enough using gear reduction. You could lift an elephant by yourself if you had an apparatus that was strong enough and gave you enough mechanical advantage. You would just l... | [
"I can't find any literature about Curiosity's power consumption, but, like you, I intuitively suspect that more than 120W is needed to push that thing over a sand dune. If that's the case, then the answer is ",
"the rover's Li-ion batteries.",
" The RTG charges these batteries when the rover is resting. When m... | [
"Curiosity might only generate about 120 watts of power, but according to its specifications, its maximum operating speed is 90 meters per hour, which converts to about 0.056 miles per hour, which isn't fast by any means. It's got plenty of power to do this. Also remember, not all of the generated power goes into l... |
[
"Why do rivers \"meander\"? If they carve through rock/soil given ample time, shouldn't they be straight lines after awhile?"
] | [
false
] | This has always made me ponder...Why do rivers continue to take such convoluted paths to their destination? | [
"It's just an outcome of fluid dynamics in a confined channel with an erodable substrate.",
"Rivers are not perfectly uniform structures; due to local geography, geology, or simple vegetation growth you will get faster bits of flow and slower bits. So let's say we start with a perfectly straight channel, but it i... | [
"Yes, this correct. ",
"See here for a nice demonstration."
] | [
"That's a significant over-simplification bordering on just being wrong. There are a number of internal feedback mechanisms that determine the shape/size/placement of river meanders far more than regional slopes and rock features do."
] |
[
"Would it be possible for a human to live without drinking water?"
] | [
false
] | I was reading about animals who drink very little and get their hydration from eating certain things. Would it be possible for a human to do this? If so, what sort of lifestyle would they need to live? | [
"Animals that drink very little water tend to have kidneys that are specially adapted to conserve as much water as possible (read about juxtamedullary nephrons vs. cortical nephrons). Humans aren't as adapted to this, so you'd have to be consuming a ton of high-water foods. Cacti, fruit, and such."
] | [
"Good question. Caffeine and alcohol are both diuretics of course, but there must surely be a minimum concentration of either below which the additional water makes up for the diuretic effect.",
"The diuretic effect of alcohol is also dependent on your level of hydration, so a very dehydrated person might gain mo... | [
"To be fair, an IV drip is the trivial solution to the problem..."
] |
[
"What Does Sagittarius A* Look Like?"
] | [
false
] | Suppose we were able to exist at a safe distance from Sagittarius A*. Perhaps we are in Carl Sagan's Ship of the Imagination. What would we see? What about various distances? Do the stars that orbit it move fast enough for us to see with the naked eye? Is there visible matter surrounding it? What would such a hol... | [
"Well - most things are really a matter of perspective, and it all depends on where you are when you're looking. The black hole itself isn't that far across, at least in cosmological terms. Estimates vary, but it might be as small as 24 million km across: on the range of a very large star, and within the orbit of M... | [
"The movie \"Interstellar\" comes close to an accurate visualization of a black hole. They used equations given to them by physicist Kip Thorne. They stopped short of being as accurate as possible to make it look good in the movie. But for your purposes the black hole shown in \"Interstellar\" may work for you.",
... | [
"I tracked down an article that said one of the collection sites is near one of the poles and the info can't be flown out until October.",
"Bill"
] |
[
"How does docking something to ISS doesn't change its trajectory? Shouldn't the momentum from docking space craft \"move\" to ISS?"
] | [
false
] | I'm not a flat earther, just curious. | [
"It does affect the orbit of the ISS. However, before docking the space craft will adjust its velocity to be almost exactly the same as that of ISS. So when the docking takes place, the net momentum that the space craft adds to ISS is very small, especially given that the station is much more massive than the craft... | [
"Many people think the ISS happily sits in orbit like our moon, but the ISS is in a low earth orbit and is thus not very comparatively stable at all. It already has to deal with much greater forces than those applied to it by a docking space craft (such as atmospheric drag and gravity). Its orbit is maintained with... | [
"A spacecraft with a mass of ~10 tonnes that docks to the ISS with 400 tonnes at a speed of ~0.02 m/s changes its motion by ~0.02 m/s * 10/400 = 0.0005 m/s. That makes its orbit deviate by no more than 45 min * 0.0005 m/s = 1.4 m. That's way smaller than the physical size of the ISS. It's completely negligible. Fo... |
[
"What is biologically happening when we drink from a straw?"
] | [
false
] | If I were to stick a straw in powder and "drink" it, I'd choke. I think it's because my lungs are opened to the powder. But why don't I with liquid? Is it something we learn as a child to "close up the tube" when we feel a "vacuum" with liquid through a straw? Is there a certain "pressure" that our bodies automatically... | [
"If I were to stick a straw in powder and \"drink\" it, I'd choke. I think it's because my lungs are opened to the powder. ",
"Nope, you can get powders into your mouth through a straw. You choked on the sugar because, as you said, it was an accident. You weren't intentionally sucking it in, so your body was not ... | [
"How unusual is this ability? I assumed it was how infants forced milk from their mother's breast. Is this not true for other mammals?"
] | [
"I don't have any specific numbers for you, but ",
"most adult carnivores",
" cannot. Dogs and cats being familiar examples."
] |
[
"What is the max speed a car can go to reach its best MPG?"
] | [
false
] | I would like to know at what speed a car must be going to hit the best MPG, where if you were to go any faster your MPG would decrease due to wind resistance. I am aware this will vary between car sizes and design, but what factors would come into play to find out the answer? i.e. an equation with explained variables.... | [
"This is a question that is most easily solved by practical application.",
"Install one of those nifty little things that measure fuel use / speed, and write down a log of how much the car consumes at same speed in different gears, make a graph, and ",
" you've got the numbers."
] | [
"HOW you drive is far more important than HOW FAST you drive. If you accelerate heavily, your fuel economy goes out the window. Minimizing braking also helps, because you are coasting more often. ",
"This",
" graph shows you how fuel consumption increases with power and rpm... But this is a WOT dyno pull. ... | [
"I'm not a physicist or mechanic, so here's some very relevant links. The first is a longish howstuffworks explanation and goes through some basic math. The second is a subsection of a wikipedia page which refers to a study where this was empirically measured for a few cars, and there's a graph.",
"http://auto.... |
[
"Since Japan's Earthquake tilted the Earth's axis by centimeters, how does that affect GPS calibration?"
] | [
false
] | null | [
"For regular purposes, nothing has to be changed. GPS satellites are just orbiting atomic clocks that broadcast the time. Your GPS unit triangulates your position based the signals from a few of these satellites, and then puts the dot on a map with the same datum. Only surveying-grade GPS units care about determ... | [
"That is not the main reason you need four. The main reason is that you have to solve for an unknown error in the clock at the receiver side."
] | [
"In addition to the OPs question, I would also be interested in knowing exactly how we were able to determine so precisely how the axis was shifted. Does anyone know this?"
] |
[
"Why does my lazy eye become 'lazier' when I'm tired?"
] | [
false
] | null | [
"Lazy eye is \"amblyopia\", and it happens when the brain favors vision from one eye over the other. There are several possible reasons for the brain to choose vision from one eye and ignore information from the other, but these essentially are due to one eye having clearer vision compared with the other (such as i... | [
"I have it too. I think the technical term is strabismus. From what I can tell, the dominant eye is stronger than the weak one and the muscles that help the weaker eye track with the dominant eye get flat out tired and can’t keep up anymore. Sometimes you can reset it by closing your dominant eye for a few seconds... | [
"It is called a decompensating phoria. Your eye muscles work hard to keep your eyes pointing in the same direction. As the day goes one, some individuals may find it harder and harder to keep the eyes pointing the same direction. Therefore they are decompensating. If a person already have an eye that point in t... |
[
"Why does semi-dry soil absorb water better than very dry soil?"
] | [
false
] | As a home gardener I encounter this a lot. If I go a few days between watering plants, the water absorbs fairly quickly into the soil. But if I've been a bad gardener and let the soil dry out completely before watering, the water just sits on top without absorbing into the soil. Why? Wouldn't the rate of mass diffusion... | [
"It's due to surface tension. When the earth is very dry, the surface tension prevents the water being absorbed for a short time, so some might pass through all the soil and not be absorbed. But if the soil is already a little damp, the surface tension is already broken.\n",
"http://en.wikipedia.org/wiki/Surface_... | [
"My guess is surface tension. If it is dry then the water is repelled from the soil and just hits the spaces rather than coating. Semi-dry/damp has enough that the surface tension is broken.",
"Wouldn't the rate of mass diffusion of water into the soil be proportional to the difference in water concentrations bet... | [
"Gotcha, thanks!"
] |
[
"turning a desert into a forest"
] | [
false
] | [deleted] | [
"There are more factors besides precipitation that determine whether an area is a forest or a desert. Odds are the prevailing climactic factors would limit the success of such a forest unless you kept pouring water on it from an external source."
] | [
"so things like soil composition ? "
] | [
"The entire area, are there winds that blow to a mountain range where the evaporated water can condense, rain down and return to your Desert.",
"If there is no way for the water to return the area will dry out when you stop providing water. It is speculated that the Olmec and Mayan empires fell because a strong e... |
[
"What defines the edge of a flame? Why is the edge visually distinct, and what keeps it from expanding into the surrounding air?"
] | [
false
] | null | [
"Flame is really incandescent gas -- that is gas that is hot enough to glow (see black body radiation). The \"surface\" of the flame is the surface where the temperature drops below the limit above which the black body radiation happens in visible spectrum."
] | [
"No. Flame isn't ionised, it's usually just heated up carbon that is glowing an hasn't reacted with oxygen yet."
] | [
"No. Flame isn't ionised, it's usually just heated up carbon that is glowing an hasn't reacted with oxygen yet."
] |
[
"Why is a Gaussian \"bell\" curve showing normal statistical distribution the shape that it is? What formulæ or proofs define its shape?"
] | [
false
] | null | [
"What is the Gaussian Curve and why is it important?",
"Aside from popping up in many contexts, which justifies it's study, it doesn't really tell us why we should care about, it turns out that there is a mathematical reason why it is important: The Central Limit Theorem.",
"The Central Limit Theorem says that ... | [
"The Gaussian distribution is the function f(x) = e",
" up to some normalization constants and translations. I don't know if that answers your question. There are some special properties of that function that give you the nice properties of the Gaussian distribution (e.g. the 'central limit theorem'), but it beco... | [
"It sounds like what you're really looking for is ",
" the function f(x) = e",
" shows up when we average \"nice enough\" independent random variables, as opposed to some other function. If you want to know, the details are in the proof of the central limit theorem: ",
"https://en.wikipedia.org/wiki/Central_l... |
[
"Is it possible within our lifetimes that we will be able to resurrect previously extinct species using surviving DNA samples?"
] | [
false
] | I'm not exactly talking about Jurassic Park here (though that would be awesome and at the same time terrifying), I'm talking about species that have recently become extinct (the , for example) where we possess "fresh" DNA samples. If it's not possible, what are the main factors preventing it? (limited bioengineering ... | [
"A team of Russian and Korean researchers are working on this",
"As mentioned in the article, Japanese researchers want this to happen within 5 years. Absolutely possible within our lifetimes. "
] | [
"I think there's research going into mammoths, but I'm not sure. I remember reading something about researchers looking into reviving mammoths, if anyone knows anything more, it would be appreciated"
] | [
"This is likely in the future, but maybe not within our lifetimes. It depends on the amount of effort (and money) put into research in this area."
] |
[
"Receding hairlines, why? and is it becoming more prevalent"
] | [
false
] | Im only 20, hair started falling at about 18. I live with 5 other guys and I've noticed all but one of us has at least a bit of a recede and I notice many blokes at uni with recedes but Ive only recently noticed in people this young I usually associated it with people much older, like my dad only started receding when ... | [
"You are in the great company of the incomparable Patrick Stewart, who lost his hair at 19.",
"http://www.youtube.com/watch?v=pXOK-ZVJMaU"
] | [
"Protip: Magnum is only effective in preventing hair loss through ",
"direct physical contact",
"."
] | [
"You noticing the increase in prevalence could possibly be a result of you being surrounded by people this age at uni. It would no doubt be an interesting study though."
] |
[
"Will a fighter pilot's height decrease due to the g-force they experience?"
] | [
false
] | [deleted] | [
"Hämäläinen O, et al. Spinal shrinkage due to +Gz forces, 1996",
"Found this article and it agrees with what you said. Weightlifting doesn't permanently decrease height, so I wouldn't expect temporary +Gz to either."
] | [
"Hämäläinen O, et al. Spinal shrinkage due to +Gz forces, 1996",
"Found this article and it agrees with what you said. Weightlifting doesn't permanently decrease height, so I wouldn't expect temporary +Gz to either."
] | [
"This is also why you likely have to adjust your car’s rear view mirror in the morning and when leaving work.",
"in reference to the OP’s question, ejecting from a fighter jet will definitely cause spinal compression beyond the norm."
] |
[
"Naked singularities, how can such a concept exist?"
] | [
false
] | Trying to wrap my mind around these things gives me a headache, how can a singularity exist without an event horizon? What made people come up with this concept in the first place? I mean, the entire fact that a singularity exists means that it MUST create an event horizon? It's like trying to imagine the Sun existing ... | [
"Naked singularities are solutions to the equations of general relativity, just different solutions than the ones we usually talk about. When people describe black holes, they usually stick to the simplest example, the Schwarzschild metric. This assumes the angular momentum and net charge are both zero. In reality,... | [
"You are right that you can escape the ergosphere, but that is because the ergosphere lies outside the outer event horizon. "
] | [
"No, there is an outer ergosurface, an outer event horizon, an inner event horizon, and then an inner ergosurface. See ",
"figure 1 here",
"."
] |
[
"Does a stationary object emit gravitational waves?"
] | [
false
] | I know technically and ideally that objects that aren’t accelerating and are in an inertial frame do not emit gravitational waves, but does this take into account all the vibrating molecules in the object? If it is above 0K and has more than one atom or molecule in it, wouldn’t an object like that be able to emit these... | [
"In principle, yes, thermal fluctuations will cause gravitational waves to be emitted, just as the same fluctuations will cause electromagnetic waves to be emitted. For example, in his GR textbook, Weinberg computes the total power emitted through gravitational waves by the Hydrogen plasma in the sun's solar core. ... | [
"10",
" Watts is surprisingly high. The Earth/Sun system emits about 200 W."
] | [
"I haven’t seen this calculation, but I assume that like blackbody radiation this power is spread across a wide range of frequencies compared to a rotating system, so it might be harder to detect. "
] |
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