title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"There are thousands of seemingly isolated bodies of water all throughout the planet which happen to have fish in them. How did they get there if truly isolated?"
] | [
false
] | null | [
"Massive floods",
", ",
"changes in river flows",
", ",
"freak weather events",
", ",
"historically very different climate",
" with larger or interconnected lakes."
] | [
"Do birds have some role?"
] | [
"There are some fish whose eggs can tolerate drying out. Killifish of the genus ",
"Nothobranchius,",
" for example, are a seasonal fish which live in temporary pools. The eggs survive in the mud when the pools dry. In captivity, killi breeders have to mimic that dry spell in order to get the eggs to successful... |
[
"Does your vision's depth of field change with your pupils' level of dilation, as in photography?"
] | [
false
] | I've been wondering this since I got into photography. With a camera lens a wider aperture corresponds with a more narrow depth of field. Do human eyes have a narrower depth of field at night (for example) because the pupil enlarges to allow more light in? | [
"Physically, I'm sure it does. However, physiologically I think the eye is designed to focus on relatively small areas. Which means that while the light may be focused correctly, the rods and cones don't have the resolution to make use of that information. "
] | [
"Perhaps, but if so, it wouldn't make much difference. At night (or low light conditions in general), there isn't enough light for the cones to function, and cones are responsible for most of our visual acuity (ability to see detail)."
] | [
"Yes, they do. You can test this out on a sunny day: everything will be in focus (assuming your eyesight is sharp)."
] |
[
"Question about how Stem Cells work?"
] | [
false
] | [deleted] | [
"With a few caveats, every cell in your body has the genetic material required to recreate your entire body exactly. This is your DNA genome contained in \"all\" (the vast majority) of your cells. However as you develop, different chemical signals communicate to different groups of cells that they need to activate ... | [
"Stem cells do have the ability, albeit to a certain medical practice. Like CharlesOSmith said above, the stem cells would respond to the signals released by their neighboring cells, and they in turn \"fill in the gap\" and respond appropriately. But this is where it gets a little tricky...",
"If you wanted to us... | [
"Stem cells do have the ability, albeit to a certain medical practice. Like CharlesOSmith said above, the stem cells would respond to the signals released by their neighboring cells, and they in turn \"fill in the gap\" and respond appropriately. But this is where it gets a little tricky...",
"If you wanted to us... |
[
"How does the brain know how much pain to feel?"
] | [
false
] | Example: Why does getting a limb chopped off hurt more than a paper cut? | [
"Pain is an experience that is heavily modulated, processed, and interpreted before getting to the part of your brain that goes \"Oww\". Some structures that are understood to be critical in this function are the ",
"periaqueductal gray",
" and the ",
"rostral ventromedial medulla",
"."
] | [
"Do nerve receptors send a different strength of signal for differing amounts of pain? Or is there something else going on here?",
"Thinking about it now it may be the quantity of nerve endings in pain?"
] | [
"If I remember anything from my physiology class, I believe there are different types receptor that are at different depths in the skin. The stronger the stimulus the deeper it would go therefore activating the deeper receptors. I would agree that more never endings that are stimulated would increase the pain respo... |
[
"What is beyond the edge of our universe?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"This question is based on fundamentally flawed premises. Please conduct some background research and revise your question if you wish to resubmit.",
"As far as we know the universe has no edge. It is ... | [
"So if it´s closed onto itself, what is the current theory as to what lies beyond it?"
] | [
"If it is not infinite there is no need for something to be \"outside\". See ",
"this answer",
" from our FAQ. ",
"This one",
" could also be useful."
] |
[
"About to get a demo confocal microscope in our lab. Any suggestions for some fun/interesting things to do with it?"
] | [
false
] | [deleted] | [
"Do tissue Fluorescenct staining (avoid green channel due to auto-fluorescence) and do a Z stack on it. Many can do a 3D modeling after the Z-stack.",
"Also see how many antibodies you can do at once. (violet, Dapi, green, yellow, red, far red, far far red) without bleed through, but you might need conjugated ant... | [
"If you're in a neuro lab, doing some cell fills and taking a z-stack of a well-filled cell to turn it into a 3-D image leads to spectacular images."
] | [
"These guys",
" in my old honours lab do some pretty cool live cell imaging of endocytosis-related pathways. Watching a cell swallow something, and then have the endosome mature and change colour as it matures into a lysosome is pretty cool."
] |
[
"What do people mean when they say things like \"math is the language of the universe\"?"
] | [
false
] | [deleted] | [
"I'll try to convey to you why I think the statement is true. This is a very popular sentiment because of what is now called ",
"The Unreasonable Effectiveness of Mathematics in the Natural Sciences",
". It's an article published in the sixties but the sentiment goes farther back.",
"In summary: In our attemp... | [
"Mathematics is the language by which we make qualitative statements like \"gravity pulls things together\" into quantitative statements like \"F = ma = G(mM)/r",
"By using quantitative statements, which relate physically measurable quantities to one another, we can develop theories and make predictions from them... | [
"anti-electron (another solution to the equation)",
"I'm sure this is an offensively simplified version of what happened, but did Dirac's equation have something like a square root which resulted in \"+/- n\" which led to the theory of antimatter? ",
"Because that's fucking cool beyond belief."
] |
[
"Why does a hair sometimes suddenly sprout in places where there is no hair?"
] | [
false
] | I had a single hair grow underneath my collarbone, and the surrounding area is completely hairless. This hair was also really strange: it was completely white, significantly thinner, and very long compared to the rest of my body hair. This has happened before on my foot (the top of my foot), although it wasn't quite as long, and after I pulled it out (more than a year ago), no hair has ever grown back there. I'm not really familiar with how hair follicles work, so if someone could explain that, it would be greatly appreciated! | [
"A hair follicle has multiple kinds of cell involved. There are cells that product the keratin follicle itself, cells that give the hairs its pigment, cells that sweat and secrete oils for the hair, and cells that pull the hair up. \nAll hair follicle units are developed more-or-less at birth. Their turning on-and-... | [
"C'mon people! Only 16 down votes? You can do better than that!!"
] | [
"You can't explain that."
] |
[
"What percentage of our own galaxy have astronomers cataloged? How are names for stars selected?"
] | [
false
] | null | [
"Names for stars are generally given by their constellation and then a greek letter corresponding to how bright they are in that constellation (so Alpha Centauri is the brightest in Centaurus). Stars that aren't part of a constellation are generally given names corresponding to the order in which they were catalogu... | [
"The USNO B catalog (the largest to date) contains about 1 billion stars and galaxies. There are roughly 300 billion stars in our galaxy, so we've cataloged about 0.3%. You can see about 6000 stars with your naked eye from a dark site with no moon. The vast distances, extinction from interstellar dust, and the fac... | [
"Most names are selected as their \"brightness\" in the constellation. IE \"Alpha Orionis\" would be Betelgeuse. However, it should be noted that the star of the highest magnitude in Orion, today, is Rigel. ",
"Most stars have names that catalog their brightness in a certain constellation. That makes them easy to... |
[
"Can a virus mutate to be less deadly?"
] | [
false
] | [deleted] | [
"Sure. A virus’ “goal” is to survive and multiply, not kill. That could mean that it becomes less deadly, so people take it less seriously and spread it more easily. If the virus is too deadly, the host could die before passing the virus on. This is why ebola is not a huge widespread problem compared to COVID-19–it... | [
"Virulence factors are genes that give pathogens their pathogenic properties. These include genes that allow for attachment or invasion of cells, or productions of toxins.",
"Pathogens can mutate to be less virulent, as mutations can be deleterious to an organism. Mutations are random, and the effects of mutation... | [
"Pathogens that are most deadly are often not a good survival strategy. A pathogen such as the common flu can be spread among many people because people with the flu often still go about their daily business, shedding more viral particles and exposing more people to these particles than they would if they were bedr... |
[
"Will it ever be possible to measure the true size of an electron?"
] | [
false
] | null | [
"The electron is governed by quantum mechanics, for which we need toss the concept of \"size\" in the definition we know it traditionally. ",
"Consider the following scenario: Before you've made a measurement on the position of the electron, it's in a superposition of various position states. Making a measurement... | [
"Quantum Mech is not an easy subject. If you get confused by it, well, so does everyone. Atomic and subatomic world is probabilist. Things aren't in a certain place, they can be somewhere and somewhere else at once. So how can you know something about it? You know where it most probably is, where it is ",
", and ... | [
"Could be worth mentioning that this is true for elementary particles only. For composite particles, such as a proton, it gets more complicated because of the interactions between the quarks and gluons it is made of. Thus it does not behave as a Dirac-Delta function in high energy experiments. "
] |
[
"Are there any experiments I can do myself to prove Einstein's STR?"
] | [
false
] | null | [
"That's a good idea, but now I have to prove to him that the decay rate of muons isn't what it seems and that it should be shorter.",
"See what I'm getting at? \nCan STR be shown and explained plainly so anyone can understand, or is a certain leap of faith required until people's brains become accustomed to a dif... | [
"That's a good idea, but now I have to prove to him that the decay rate of muons isn't what it seems and that it should be shorter.",
"See what I'm getting at? \nCan STR be shown and explained plainly so anyone can understand, or is a certain leap of faith required until people's brains become accustomed to a dif... | [
"That's the problem. My grandfather's life revolved around the Bernoulli equation, he designed water pumps all his life and had a tenure at a construction engineering college here in Croatia and he is convinced that he knows everything there is to know about energy. And from a classical standpoint maybe he does, bu... |
[
"If blood cells don't have DNA, how do the police use blood for genetic testing?"
] | [
false
] | null | [
"Mature red blood cells don't have a nucleus (thus no DNA), but white blood cells do."
] | [
"If I recall correctly, red blood cells don't have nucleuses in order to carry more oxygen. Blood cells themselves don't reproduce. They are produced from bone marrow. "
] | [
"And you don't need very much DNA for genetic testing so the small proportion of white blood cells is enough. "
] |
[
"Just found out I have to drink Barium for a CT on friday. Is Barium actually safe to drink?"
] | [
false
] | null | [
"Barium is not radioactive. It is used because it is opaque to x-rays and isn't poisonous like Lead. Please speak with your doctor about associated risks and any other questions you have. They really are the best resource for this as we can't give you advice about your medical situation. They will be able to tell y... | [
"Yeah, I realize nobody can give medical advise online, and I wouldn't really take it. I'm not looking for medical advice.. just facts about the liquid barium, trying to understand what the possible risks and what to do afterwards. My doctor won't be there, it's a radiologist and I'm not admitted to a hospital, my ... | [
"We really can't give you that information. Do a web search on it, there's patient information readily available. Search WebMD or The Mayo Clinic's site. "
] |
[
"Is required delta-v to reach mars polar and equatorial landing sites different?"
] | [
false
] | My intuition tells me it harder to land on pole vs equator. But hence I can't find definitive confirmation (also, I don't have skills to make calculations...), maybe I'm wrong on this. Or maybe the difference is totally insignificant. So: I am trying to understand if, lets say, 1000 kg of cargo needs exactly the same amount of fuel to safely land on poles vs equator. And if not, whether the difference is more like 0,5% (rather insignificant) or closer to 5% (significant). | [
"Not significantly, no.",
"In terms of the orbital insertion, hitting Mars in the first place takes enormous precision, and changing the target from the equator to the pole is a rounding error in fuel usage. Mars and Earth both orbit the Sun in ",
" the same plane, but there are small variances, so it's a toss ... | [
"As the other person said, we aren't going to save in heat shield by using a more efficient aerobreaking anyway.",
"For reference, if you aim at the pole, you will have to kill 200-300 meters per second more. That's very insignificant compared to 10+ kilometers per second that you need to kill anyway. It's 2-3%, ... | [
"However, if we could calculate the thickness of heat shield our vehicle was going to need, with the same kind of accuracy as we can budget our propellant, then we could save a few kilos by landing with the planet's rotation. I have no clue if we can do this today, but my guess is no."
] |
[
"What would happen to my body if I were somehow physically prevented from urination/defecating?"
] | [
false
] | null | [
"In that case, I'll cover the defecation side!",
"Essentially, what we're looking at is bowel obstruction. We can categorise it by the cause (mechanical obstruction, non-mechanical obstruction), or by the location (small bowel, large bowel, or outlet). ",
"One way to think about it is that the bowel is a hollow... | [
"I will cover the urination side of this question. ",
"There are two main categories of urinary obstruction. There is acute urinary retention (all of the sudden not being able to pee) and there is chronic obstruction (narrowing making it harder to pee for a long time). ",
"In the presence of acute urinary rete... | [
"The sodium would be an issue. But the potassium would be the real problem....",
"You wouldn't excrete potassium, it would go up and it would cause arrhythmia's and death"
] |
[
"Is there any evidence that ancient humans might have danced or sang to impress a mate?"
] | [
false
] | null | [
"What do you mean by ancient humans? We know modern humans do this. Dance and (less frequently) song are used in courtship rituals across virtually all cultures, throughout history; and therefore certainly humans have been doing so at least since the start of recorded history, and we have no reason to believe it's ... | [
"Maybe the user is referring to the Homo genus or even Hominidae when we were (closer to) animals and less self-reflecting in our decisions and actions."
] | [
"Don’t even some birds dance for a mate?"
] |
[
"Can equations that model motion (eg. F=ma) be derived from first principle, ground-up?"
] | [
false
] | null | [
"It depends on what you take to be your \"first principles\". If you take F = ma to be a first principle, then there's not need to derive F = ma. If you take the principle of stationary action to be a first principle, then you can \"derive\" F = ma from that."
] | [
"Sorry, it’s hard for me to explain what I mean. I mean to say that, F = ma isn’t true per se. Wouldn’t you say that the most accurate form of F=ma for, say, a person pushing on a block, would be a direct solution for all the interactions between each individual molecule/atom? If you get what I mean"
] | [
"F = ma applies for classical, nonrelativistic systems. You can modify it to include relativistic effects, but to treat quantum systems, you have to fundamentally change the way you do things."
] |
[
"Why isn't the steam released from nuclear reactors radioactive?"
] | [
false
] | So unless my understanding on how the reactors work is wrong, don't they use the radioactive material to create steam to turn the turbines? Wouldn't this cause some radioactive material to be released with the steam? | [
"Massive oversimplification, but:",
"A.The fuel is clad in tubes, so there isn't any direct contact between the fuel and the cooling water. ",
"B. the cooling water isn't directly turned into steam. It is kept under pressure to prevent it from boiling.",
"C. The superheated cooling water is pumped through a h... | [
"Now to complicate things a little.",
"You described a PWR but some of the US plants are BWR where your point \"B\" is not applicable. The fuel heats the water at a lower pressure (still ~1000psi) which directly becomes steam and then runs a turbine.",
"Additionally, sometimes fuel leaks (and steam generators ... | [
"In a boiling water reactor, where the steam we send to the turbine comes from the reactor, it is radioactive. There are trace amounts of fission products and other activation products, but the majority (95%) of the radiation in the steam is from nitrogen-16, which has a half life of 7 ish seconds. ",
"N-16 makes... |
[
"My mom always says \"if women ran the world there would be no wars\". From Cleopatra to Thatcher, how many female leaders have started wars and how does it compare to male leaders (in percent)?"
] | [
false
] | null | [
"This is a very broad question. Percentage of male leaders, across the world and over the course of 2000 years that have started wars vs women who have started wars? Would anyone be able to calculate that, even just focusing on major powers and not the thousands of piddling principalities that have existed in that ... | [
"Additionally, we need to consider the fact that women rose to power in the classical and middle ages almost entirely in periods of time of incredible instability and conflict; otherwise a male heir would be more likely. From this, many of the female leaders are cast into war almost upon taking the throne. ",
"Ex... | [
"..but a problem you'll run into when learning about historical powerful women is they're never really portrayed in a positive light..",
"Can you give scientific evidence that powerful women are \"portrayed in a negative light\" more than their male counterparts? ",
"I haven't read about a single powerful leade... |
[
"I just received a telescope and discovered that it is not sighted correctly. How do I fix this?"
] | [
false
] | null | [
"Try ",
"r/astronomy",
". They are usually very helpful with this sort of question. "
] | [
"You need to be more specific. Read up on telescope collimation."
] | [
"Some more information would be helpful, but I assuming that what you mean is that when you look through the finderscope that is not what you see when you look through the optical tube eyepiece.\nIf that is so, you will need to adjust the finderscope. Focus the optical tube on some faraway object during the day. Th... |
[
"How can Rabies still exist and be as prevalent as it is, if it's lethality is 99.99% and it's disease cycle is relatively short?"
] | [
false
] | null | [
"Because rabies can infect a lot of different animal hosts, many of which can live a long time or indefinitely after being infected. These are known as reservoir hosts because they provide a stable source for infections of more susceptible hosts. Reservoir hosts for rabies generally include Carnivoran mammals (racc... | [
"Most human to human cases of rabies over the past decade or so have been a result of organ/tissue transplants!",
"https://pubmed.ncbi.nlm.nih.gov/20205588/",
"https://pubmed.ncbi.nlm.nih.gov/28411355/",
"https://pubmed.ncbi.nlm.nih.gov/27331337/",
"Dogs are also the most common vector species in human infe... | [
"Besides what others have said the cycle in humans is only short once symptoms appear. You can be infected for months before you become ill. Once symptoms show you have maybe a week to live, a little longer if you're lucky. Depending on how you define \"lucky\" since your existence will be torture."
] |
[
"\"Try to drink your juice or smoothie straight away. After 15 minutes, light and air will destroy much of the nutrients. \" What is happening here?"
] | [
false
] | null | [
"Any antioxidants will quickly degrade if they react with oxygen in the atmosphere -- it's their job to sweep up excess oxygen ions to prevent them from oxidizing other molecules. Vitamin A, vitamin C, and melatonin are some major antioxidants that come to mind."
] | [
"Isn't the oxygen introduced when it's blended? Why would ingesting it make a difference? The process would continue regardless I would think "
] | [
"There is only a limited amount in the blender and only a short period of exposure. Also, atmospheric oxygen is O2 so it's not as quick to react, but it will eventually. If you leave it sitting out then there is more time for oxygen to work its way through the mixture. I don't know exactly how long it takes to h... |
[
"Magnetic Spin of Electron, +1/2 or -1/2, does one state have a lower energy?"
] | [
false
] | Let's say a subshell is half-filled, will the electrons have a magnetic spin number +1/2? Or can they all have -1/2? Do atoms have a preference of + or - here? Is the +1/2 or -1/2 purely a conventional thing? Or is there an empirical way to look at a single electron and say, that's UP! Thanks Edit: Thank you all for taking the time to answer my question, it has answered clearly AND I learned something! Upvotes for all! | [
"There is also a slight difference in energy of spin up and spin down states of electrons in atoms compared to the spin of the nucleus. Since the nucleus produces a weak magnetic field of its own, the electron spin direction that is anti-aligned with the nuclear spin will be slightly lower energy.",
"This is the ... | [
"There is also a slight difference in energy of spin up and spin down states of electrons in atoms compared to the spin of the nucleus. Since the nucleus produces a weak magnetic field of its own, the electron spin direction that is anti-aligned with the nuclear spin will be slightly lower energy.",
"This is the ... | [
"This effect also comes into play in couplings observed via nuclear magnetic resonance. "
] |
[
"How does muscle atrophy occur among bed-ridden adults but new born babies that keep lying down for most of the day build muscles good enough to help them stand up?"
] | [
false
] | null | [
"I seem to recall a study, done many years ago, in which some college athlete volunteers (all presumably in good physical condition), were paired with infants and asked only to \"mirror\" the babies' actions. At the end of the day, the athletes were totally exhausted."
] | [
"I seem to recall a study, done many years ago, in which some college athlete volunteers (all presumably in good physical condition), were paired with infants and asked only to \"mirror\" the babies' actions. At the end of the day, the athletes were totally exhausted."
] | [
"There's a similar thing floating around Facebook now where a dad mimics his daughter's movements. It would kill me to keep up with even a tiny infant!"
] |
[
"Why does squinting improve my eyesight?"
] | [
false
] | null | [
"It has more to do with excluding the high-angle light rays from coming into your eye. Those are the ones that are the most out-of-focus. Cutting down the iris towards a pinhole with your eyelids will cause things to be more in focus. "
] | [
"I don't see how this can be correct. For a squint to affect the view of objects in the distance in this way, the eyelids would have to at least partially cover the pupil. Mild squinting doesn't do this, as one can confirm by looking in a mirror and squinting a bit. ",
"I believe that the stress you are putting... | [
"While we're on the topic, does it actually negatively affect your vision?"
] |
[
"Why is it that if I squeeze an \"empty\" plastic bottle with water droplets covering its inner surface, that the water droplets do not change?"
] | [
false
] | [deleted] | [
"You could do that if you had a good way to force the air to do it. The trouble is that as you squeeze the bottle and put a pressure on the system, the air reacts and tries to exert this pressure back- but it does so from all directions equally. If you could force the air to put all the pressure on a droplet on o... | [
"In many cases, when you squeeze the bottle, what you're squeezing most is the air in the bottle, which is a reasonably compressible fluid. Water is generally considered an incompressible fluid, so when you put the two together, your compressible air is going to compress instead of the droplets, which aren't going... | [
"Pretty much. The air exerts a pressure on the surface of every droplet, but the droplets are really quite resistant to compression.",
"http://en.wikipedia.org/wiki/Properties_of_water#Compressibility",
" starts getting into exactly how poorly this fight will go for the air in the bottle. That section mention... |
[
"Are calories calculated the same for animals as they are in humans?"
] | [
false
] | [deleted] | [
"Calories are measured by burning a food in something like a liter of water and seeing what the temperature rise of the water is. Caloric qualities of a food are independent of who or what is going to it eat it. "
] | [
"Calories are measured by burning a food in something like a liter of water and seeing what the temperature rise of the water is. Caloric qualities of a food are independent of who or what is going to it eat it. "
] | [
"Calories are a unit of energy. One thermodynamic calorie is the amount of energy that heats one gram of water by 1° C: 4.1868 joules. The calories that you see on nutrition labels are actually kilocalories (4,186.8 joules), labeled \"Calories\" for historical reasons.",
"An easy-to-measure upper bound on the amo... |
[
"How common is it for animals to starve to death in the wild?"
] | [
false
] | I've always wondered if it's a common thing or not. As in they starve simply because they failed to find food not because of human involvement | [
"Well, listening to BBC Radio 2 this morning, they were discussing the \"chubby squirrel epidemic\" seen this winter. Temperatures have been mild and thus there has been an overabundance of food for the squirrels. As a result, we have fat squirrels this year. A representative from the Wildlife Trust came on as a gu... | [
"In temperate areas, it is extremely common for animals to starve to death during winter. It probably ",
"occurs most often",
" in fishes, then dinosaurs (birds), then mammals. With some species, u",
"p to 90%",
" of the individuals die as a direct result of starvation."
] | [
"Watch some national geographic... it is extremely common.",
"Very few populations are stable, and instead have repeating patterns of highs and lows.",
"For instance a high population of deer can cause a low population of wolves to rise, and as they mature, they overhunt the deer, resulting in many of the wolve... |
[
"Why do we presribe prednisone instead of prednisolone?"
] | [
false
] | Why does prednisone exist? Why would you prescribe it? Prednisone is converted by your body to prednisolone (active form). This conversion is so efficient that a 25mg tablet of prednisone is equivalent to 25mg prednisolone in a healthy individual. In people with hepatic insuffiency, the conversion is less effiecent and prednisolone is a preferred drug. Why do we still bother with prednisone? Are their any benefits for prescribing prednisone? | [
"Mostly it's because prednisone is cheaper. ",
"As you say, they have similar biological effects in most cases. Prednisolone is available in some forms that prednisone isn't, such as eyedrops, but outside of those special cases they are pretty much equivalent. ",
"They are even the same age, both having been in... | [
"pharmacology aside, there's a lot of potential reasons",
"method of delivery? prednisone comes in tablets, prednisolone seems to only be available as a liquid -- i suspect liquids and syrups are more annoying to transport, dose correctly, etc.",
"cost? per mg, prednisone seems to be less than 1/5 the price ($0... | [
"These are called “prodrugs” and there are many other examples of this. There are a few reasons why prodrugs are used. Sometimes it’s just more cost effective. But a more interesting application is its use as an extended release version of the drug that can’t be tampered with. Often times the drug is broken down in... |
[
"How does deep oil well drilling work? Is the pipe the same diameter all the way down? Why doesn't friction impede progress?"
] | [
false
] | Saw a news article today on a new 7000 ft below sea floor record for drilling. This got me to thinking: how is it possible to overcome the friction between the pipe and the material being drilled through over long distances? Does the entire pipe consist of the same diameter, and is slowly being pressed into the earth? Or is there a technique where smaller diameter pipes are used? | [
"The diameter of the bit is larger (about 2-3x) than the diameter of the pipe. The \"walls\" of the hole and inside of the drill pipe are pumped full of drilling fluid that reduces friction and heat as well as holds the pressure of whatever you are drilling in to below the surface of the hole (preventing a blowout)... | [
"The amount of power that a rigs topdrive (engine that pipe is connected to and spins) is enormous in comparison. Where I am from it is typical to drill 5000m holes (half straight down and then kicked out on a long 90 degree turn). Depending on the rock formation you can drill 100m/h or 0.01m/h. As the bit wears do... | [
"The part I'm still having trouble understanding though is how friction between the pipe and the surrounding rock doesn't keep it from spinning after getting to a certain depth. That has to add up to a point where the force necessary to keep the pipe spinning is equal to the power output of the engine driving it?"... |
[
"Would it be possible for something to exist that actually repelled space/time as opposed to attracted it like normal mass? What would be its characteristics?"
] | [
false
] | Like a reverse black hole maybe? something that would kick away from it anything that came close? I would think that such a thing would also be invisible or maybe even narrowly reflective as it shot back light that tried to approach it. | [
"I don't think you've asked this question in a way that other people understand. What do you mean by \"space/time\" here? Because I don't think most people think of mass as \"attracting space-time\". I think some people might say something more like \"mass attracts mass, with large masses, and repels mass with t... | [
"i said 'space/time' for completeness i guess since both are tied together but i suppose it makes a bit more sense if you take 'time' out of it."
] | [
"Do a google for kirkwood gaps. ",
"If you imagine mass as creating \"gravitationally attractive valleys\" in space/time, then kirkwood gaps are \"gravitationally repellent mountains\" created by the opposing masses of Jupiter and the Sun. ",
"Good enough?"
] |
[
"how long after I \"die\" would my mind stop working?"
] | [
false
] | null | [
"I don't think you are dead UNTIL your mind stops working. "
] | [
"Just to be more specific, your explanation pertains to the brain not the mind. Although observations highly suggest that the two are very closely related, it's still uncertain what will happen to the mind after brain damage as the mid is not directly observed. One may still choose beeline that the mind is independ... | [
"Just to be more specific, your explanation pertains to the brain not the mind. Although observations highly suggest that the two are very closely related, it's still uncertain what will happen to the mind after brain damage as the mid is not directly observed. One may still choose beeline that the mind is independ... |
[
"Evolution: Can a creature's traits change during it's lifetime?"
] | [
false
] | [deleted] | [
"Epigenetics",
" is not exactly what you're asking for but it might interest you."
] | [
"Many animals have fur coats that change in thickness and color to match the seasons, like an ",
"arctic fox",
" (first one I thought of).",
"Or an example closer to home: If a human moves from a cloudy place to a sunny place, you get a tan (bodily adaptation to account for local environmental conditions)."
] | [
"No, an animal cannot change its traits within its lifetime (nor pass those traits on to future offspring) unless it is an animal that is already adapted to a changing environment where it changes it coat colour depending on the seasons (arctic fox mentioned below, hares - the ones we have in canada do this too). "... |
[
"Are computers just as efficient as electric heaters if you want to warm up a room? Does all of the energy used end up as heat or does a tiny bit used in calculations?"
] | [
false
] | null | [
"Here are relevant questions. Hopefully they are helpful.",
"[1]",
"\n",
"[2]",
"\n",
"[3]"
] | [
"in computers, there are often moving parts, as well as lights, that translate energy into things other than heat, so literally, no. \nbut i think the heart of your question is what the actual energy requirements/release of computing itself are. and this is where i start to speculate a bit, but i believe that the a... | [
"This is not correct. The fans eventually stop when you turn off the computer and is turned into heat by friction. True for all moving parts. The light from display hits the environment and turns into heat as well. If you have windows, a tiny bit of light might escape that way. "
] |
[
"What is the smallest planet/moon that still has a detectable magnetic field?"
] | [
false
] | null | [
"I just want to add that two kinds of magnetic field exist. \nIntrinsic magnetic fields and induced magnetic fields.\nMercury, Earth, Jupiter, Saturn, Uranus and Neptune have intrinsic fields. It is usually due to them having metalic cores. (Iron for Earth and Mercury and metalic hydrogen for the giants.) \nThey sp... | [
"Better to ask: which planet or moon is the smallest - the EM field is everywhere and of course anything with an electric charge (protons and electrons) interacts with it at some level.",
"I'm going to take some liberties here, and talk about detectable ",
" effects that can be detected by near-Earth instrument... | [
"Thanks for such a detailed answer!"
] |
[
"Light from distant stars and galaxies reaching earth?"
] | [
false
] | null | [
"I have no idea what you are trying to say."
] | [
"Understandable. I can try and do it step by step. A galaxy would take at least 13 billion years to get 13 billion light years away right?"
] | [
"Actually with the expansion of the universe it could look like a galaxy is 20 billion light years away even tho the universe is only 13.7 billion years old. ",
"See our in FAQ for more info: ",
"https://www.reddit.com/r/askscience/wiki/astronomy/theobservableuniverse"
] |
[
"\"Blood Doping\" is when professional athletes artificially increase their number of red blood cells to gain endurance. If this helps, why wouldn't the body naturally have that higher blood count?"
] | [
false
] | null | [
"To add to what has been noted so far adding additional Red Blood cells to the human circulation system introduces certain health risks. It increases blood viscosity and decreases cardiac output and blood speed. It can increase the risk of stroke, heart attack, phlebitis, and pulmonary embolism. ",
"even when sol... | [
"Producing red blood cells takes energy, so your body only does it when it detects that you need them. This regulation process is relatively slow. One of the ways that blood doping works is that athletes put themselves in situations where this natural production of blood cells (hematopoiesis) is stimulated, then ha... | [
"To add many of the components of blood cells, and the degradation of blood cells are toxic and pro-inflammatory (ex. heme). "
] |
[
"How does interferential current, used on the body, cross in the middle, instead of forming two parallel currents?"
] | [
false
] | [deleted] | [
"I can't be authoritative on the effectiveness of the treatment -- just on the physics. The idea is to make two ~4kHz A.C. signals interfere, producing heterodyning at the right frequency (~10 Hz) to muck about with the nervous system. If the two voltages are applied across the body (e.g. the \"carrier\" is from ... | [
"Thank you very much! I guess I'm really just asking a more basic question, however. The desired effect is to create a point in the middle where the currents cross. The current from one lead travels only to its corresponding lead (far). Why does it do this instead of going to the other lead (parallel formation in... | [
"Current spreads out as it travels through a resistor with spatial extent.",
"Even if it didn't, when the two signals are in quadrature (90 degrees out of phase) the shortest conductive path goes right through the centerpoint a couple of times per cycle: when one pair of electrodes is at full voltage and the oth... |
[
"Can you get cancer if you eat cancer tissue of an animal?"
] | [
false
] | null | [
"Transmissible cancers do exist. Probably the most famous one is the kind that causes ",
"Tasmanian devil facial tumor disease",
", which is transmitted by direct contact between individuals. However, almost all transmissible cancers only affect animals within a particular species. The only evidence I was ab... | [
"No. It's technically possible to get certain types of cancer from another humans under very, very rare circumstances (via organ transplants rather than cannibalism). Cancer spreads effectively because the immune system cannot tell the difference between your normal cells and cancerous ones; the body would recogniz... | [
"Wanted to add this ",
"sexually transmitted cancer in dogs",
"."
] |
[
"can you recommend an intro anatomy textbook?"
] | [
false
] | I start medical school in September, have never taken an anatomy course, and want to play a little catch-up to the rest of the field. Recommend a good textbook, AskScience! | [
"Netter's is the best IMO. Awesome diagrams and clear illustrations. "
] | [
"Seconded. Netter is just an atlas though, not a text."
] | [
"I used Gray's Anatomy when I took anatomy in med school. It was a good book, explained things well."
] |
[
"Woken up so suddenly that your body \"wakes up\", but you yourself don't? What is this phenomenon?"
] | [
false
] | null | [
"If this is true, it sounds like an extended state of sleep walking. Sleep walking occurs when the brain is in a disassociated state shifting to/from waking/sleeping. Basically, the whole brain does not wake up--part of it can remain in sleep signal patterns. ",
"Severity and symptoms of sleep walking differ betw... | [
"Well, any abnormal movement/actions during sleep are considered parasomnia. I did a big research project on it back in my abnormal psych course. Basically, this is a whole big web for abnormal sleep behavior (and will probably be reclassified with the next DSM comes out). Anyhow, sleep walking can be a relatively ... | [
"Really? This is very interesting. And you say you've seen stranger things? Any examples?"
] |
[
"What is the driving force for osmosis?"
] | [
false
] | I have been taught that osmosis is driven by the molar concentration of solutes in a solution across a selectively permeable membrane. Pretty basic to me. What puzzles me is how there is no relationship between osmotic pressure and size of the solute since osmotic pressure is a "colligative property". I've been told that cells can reduce osmotic pressure by combining many molecules of glucose into one large molecule of glycogen, for example. How is this possible? | [
"All colligative properties are manifestations of entropy and the second law of thermodynamics. That is, they neglect all enthalpic contributions to the effects (these lead to deviations from ideal behavior). ",
"Osmotic pressure derives from the driving force of a solution to become more dilute, because spread... | [
"To further this wholly correct point - osmotic pressure depends on the concentration of particles in solution. It doesn't matter what those particles are. So if you take 100 glucose molecules and combine them into a single glycogen molecule, you have gone from 100 particles to 1 particle in solution. The osmoti... | [
"So is osmotic pressure a physical pressure?"
] |
[
"Do photons (and other C travelers) experience an acceleration to C or is the velocity instantaneous?"
] | [
false
] | Or does it not even make sense to define an acceleration to such things? If so, why? For examples sake, say I have an interaction that results in an emitted photon, at what point is it traveling at C? And where does this energy to travel such speeds come from, simply from the system as it goes to ground state which in turn is the energy to fuel the emissions? How can that be enough? | [
"There is no acceleration, because photons always travel at c. This is just an intrinsic property of massless particles in general.",
"And where does this energy to travel such speeds come from, simply from the system as it goes to ground state which in turn is the energy to fuel the emissions? How can that be e... | [
"Just to add, the frequency of the photon/wave is dependent on the energy the photon carries, via planck's constant. Furthermore a photon does have momentum, which is related to the frequency and thus the energy of a photon. Therefore if a photon were to hit a surface after being emitted, and is adsorbed, it will g... | [
"It doesn't seem like anybody has actually answered you. The momentum of a photon is proportionate to its frequency, instead of its mass and velocity, both of which are constant.",
"I'm sure you are familiar with E=mc",
" but you might not realize that that is not the complete equation. It is only the part that... |
[
"Is it probable that the solar panels from the Mars rover get cleaned by a storm or anything else?"
] | [
false
] | [deleted] | [
"Yes - actually, this happens quite a lot, and this is part of why Spirit and Opportunity lasted for so long. The Martian wind partially cleans the solar panels, so although they quickly became fairly dusty, they still ran fairly decently for quite a long time."
] | [
"Especially Opportunity! That little rover belongs in the Mars Museum of History when we build it. That was by far the best bargain we US taxpayers ever got."
] | [
"Yes. They didn't think this was possible when they launched Spirit and Opportunity but quickly discovered it did actually happen which is why those plucky little bots kept going for so long",
"It's not a perfect solution because the robot has to recharge it's batteries during the day and conserve power at night ... |
[
"If Prince Rubert's Drops are stronger than steel, can we make materials using the same idea?"
] | [
false
] | I know they are very fragile since they detonate if you break the tail, but could we make something using the same tension idea? | [
"We do it all the time - that's exactly what ",
"tempered glass",
" is. Some everyday examples: the side and rear windows of your car, most windows in commercial buildings, and a lot of glass baking dishes. ",
"They have the same failure mode as Rupert drops, as a small crack will cause them to fail all at on... | [
"As an aside, shattering is not a bug but a ",
" of tempered glass. A million tiny shards are much safer than a few big ones. In my town you're not allowed to put untempered glass at floor level in a house for this reason.",
"Bonus: if you wear polarized sunglasses you might have noticed a diamond pattern on ... | [
"Bonus: if you wear polarized sunglasses you might have noticed a diamond pattern on the rear windshields of cars. This is caused by the grid of compressed air nozzles that blow on the glass to temper it.",
"Hah, that explains that. I thought it might've been an artifact of some sort of coating process."
] |
[
"Can complex or imaginary numbers be irrational?"
] | [
false
] | I know that imaginary numbers and real numbers are different sets with no intersection, and rational/irrational numbers are are a subset of real numbers. That leads me to believe that there are no irrational numbers, but would the square root of negative pi or pi times i be irrational. Also, could complex numbers with an imaginary part be irrational, like e + i? | [
"I know that imaginary numbers and real numbers are different sets with no intersection",
"I suppose by \"imaginary numbers\" you mean purely imaginary numbers, i.e., complex numbers of the form z = b",
" with b real. If so, then z = 0 is both real and purely imaginary.",
"and rational/irrational numbers are ... | [
"smallest subfield that contains the ",
" numbers and the imaginary constant ",
"I assume the bolded word is a typo for \"rational\"?"
] | [
"Ah, yes, thanks. Otherwise the field would just be all complex numbers. D:"
] |
[
"Do you have a preferred lung/kidney?"
] | [
false
] | I know it sounds weird to ask, but I was wondering since we have a preferred hand/eye/foot, does our body prefer our organs as well? Are there any parts of our body that get preferred that you wouldn't think would? | [
"Every two or so hours your body switches which one of your nostrils is “dominate”. The majority of the air you inhale goes into one nostril or the other. Cover one nostril and breathe in through your nose, then cover the other. One will be significantly easier to breathe through."
] | [
"No, the body works at the same time both lungs and kidneys functioning to work together for efficiency and efficacy. If only one worked at a time or back to back then it would take a while to start up again. The lungs would develop atelectasis from not being filled and empty, decreasing the amount a person can bre... | [
"Outside of some pathology, no. Your body does not use one lung or kidney more than the other. Your lungs basically operate on pressure differentials - when you inhale, it expands your lungs, reduces the pressure inside the lungs, and atmospheric air rushes in towards that low pressure area - unless you can selec... |
[
"how would you explain x^-1 and x^1/y?"
] | [
false
] | How would you explain taking a number to the negative power? I don't understand how that would be the reciprocal of x!! I also don't get taking a number to the reciprocal of something like 4 how is that the square root of 4? | [
"Well, for the first one think about it this way. If you multiply two numbers with the same base raised to an exponent, you simply add the exponents: a",
" * a",
" = a",
" Now what happens if you divide by a? Lets say a",
" / a = a",
" But that's exactly the same thing as saying a",
" * a",
" = a",
... | [
"In general, x",
" * x",
" = x",
". Following this, whatever you define x",
" to be, it should satisfy x",
" * x",
" = x",
" = 1, but then x",
" = 1/x just by manipulating that equation.",
"Similarly, in general you have (x",
")",
" = x",
" , so whatever you define x",
" to be, it would be... | [
"I like this approach, called ",
". ",
"First, I show students 5",
" 5",
" and 5",
" We discuss what it means to go 'up' a power - to multiple by 5. So what does it mean to go down a power? It means to divide by 5. ",
"So now we have: ",
"5",
" = 125",
"5",
" = 25",
"5",
" = 5",
"5",
" =... |
[
"Can someone please explain the Ecliptic Coordinate System (Heliocentric)?"
] | [
false
] | To practice my coding, I wanted to write up a very rough, very basic navigational computer type program that would track the orbits of every planet. Given a time, a destination, and point of origin, the program would report back the distance between the two points. I understand there are various coordinate systems for tracking celestial bodies, but decided on the heliocentric ecliptic coordinate system because it made the most sense to put the Sun at the center of the map. I don't understand how positions are given, however. Could someone please explain how the coordinates are read/determined? Or point me to a simpler method of tracking the planets' positions? Thank you! | [
"Elliptical is fine. Since you're doing heliocentric, your focal point is the Sun, so just assume everything is orbiting on separate planes. If you want to really get an exact estimate each time without adjustments, do the Lambert's method or the Gauss method. Lambert is when you know the distances."
] | [
"I don't understand how positions are given",
"Could you please be more specific about this point?",
"I assume you're asking how to convert angles and radii to x,y,z coordinates. Take a look at ",
"spherical coordinates",
". In your case it may be simplified if you consider one plane at a time, so you can j... | [
"Ultimately I'm not sure how to plot the other planets. Since I'm going heliocentric, I imagine the sun is at coordinates (0,0,0). If I then wanted to plot Mercury on this virtual map, how would I do that?",
"Ideally I would like to turn this into a simulation of some sort where I could keep adding data on othe... |
[
"Is there any way to predict when a particular star will go supernova?"
] | [
false
] | I'm curious if the nighttime sky will be lit up with the beauty of a supernova within my lifetime. Is there any way astronomers can predict (within a certain time frame) when a star will go supernova? | [
"Betelgeuse in the Orion constellation is about to/already gone supernova. It's only about 700 lightyears away, and is predicted to go within 10-1000 years. This means it could go within our lifetime, and may have already, the light just hasn't reached us yet. When it does it'll basically be a second moon in terms ... | [
"Do you have a citation for 10-1000 years? Wikipedia says \"Betelgeuse is expected to explode as a type II supernova, possibly within the next million years.\" The other four top google results of \"Betelgeuse Supernova\" also give million year ish predictions."
] | [
"It seems the 10-1000 years was anecdotal, I'm sure I remember seeing it somewhere, but nevertheless, ",
"Dr. Brian Cox on Betelgeuse",
", this was from a recent live stargazing thing he appeared on, and I would be inclined to trust what he says as a reputable source, plus it's the BBC, they're generally reliab... |
[
"How much of the current climate trend is actually due to humans? Aren't we coming out of an ice age, and this would naturally change the climate in its own?"
] | [
false
] | null | [
"Our current data and models suggest that ",
" of the temperature change over the past 100 years is due to humans.",
"We are not \"coming out\" of an ice age: the last ice age ended 12,000 years ago, and these warm periods typically last 8000-15,000 years. So we're probably nearer to the end of a warm period t... | [
"Thank you. I have secondary questions now, not sure if that's allowed but whatever. I've heard this argument made recently; how much of an effect on the current extreme weather, at least in America, is due to ocean currents like El Nino? Or is it mostly the slowly changing climate causing more and more extreme wea... | [
"The climatic maximum was roughly 7000 years ago, so without human influence, we should be cooling and approaching glacial conditions again."
] |
[
"In simple language, what's the distribution of mass of a galaxy (i.e. % of total mass as a function of radius)? I actually googled an article on the topic (see text) but it's too technical for me and I'd appreciate a simple explanation."
] | [
false
] | The article: | [
"Look at the bottom panel of Figure 2 on that page - I've rehosted it ",
"here",
".",
"This gives mass as a function of radius for a galaxy. The radius is in kiloparsecs, where a kiloparsec is about 3000 light years (in astronomy we tend to prefer parsecs to light-years). The mass is in 10",
" solar masses.... | [
"There's still dark matter in the centre - there's actually a higher concentration there than in the outer parts - but there's an even higher concentration of visible \"baryonic\" matter which dominates there.",
"Most of the baryonic matter (stars, gas, & dust) is in a disc. The density of this stuff is quite hig... | [
"There's still dark matter in the centre - there's actually a higher concentration there than in the outer parts - but there's an even higher concentration of visible \"baryonic\" matter which dominates there.",
"Most of the baryonic matter (stars, gas, & dust) is in a disc. The density of this stuff is quite hig... |
[
"How come light that comes from other stars is not scattered ?"
] | [
false
] | So i was thinking that if light from other stars can take light years to get to earth how come it reaches us? Why don't other planets or other stars come in the way and scatter it? or does light travel straight through objects? | [
"Space is empty. Really, really, really empty. The average cubic kilometer of interstellar space in the galaxy has maybe a nanogram of matter in it, and outside of galaxies we're looking at an even lower density, by a factor of a million or so. Planets and stars are utterly tiny. Even when Earth and Mars are at the... | [
"You're not quite fathoming how huge and precise \"unfathomably huge and precise\" is."
] | [
"Stars are much bigger than planets; so even when a planet ",
" get in the way, it only blocks a little bit of the light—not enough to tell with the naked eye. But very sensitive telescopes can detect the difference, and that’s actually one of the main ways we find planets outside the solar system."
] |
[
"If I squeeze a bottle of water in space, what would happen to the bottle? Would it become reinflated like it would on Earth due to displacement of liquid with air?"
] | [
false
] | [deleted] | [
"You mean an open bottle than you empty by squeezing the water out? There would be no difference in space, the bottle will go back to it's original form due to elastic deformation of the plastic. It has nothing to do with pressure from inside (because there is not pressure difference between inside and outside the ... | [
"This was the answer I was looking for. Thank you, the question has been on my mind for the past few days."
] | [
"We you squeeze a bottle on ear you are pushing out a large fraction of the air inside. In the vacuum of space the bottle would actually move back to it's original form faster as it wouldn't have to suck air inside to keep its internal pressure balanced with the external pressure because there would be no external ... |
[
"For psychologists... what exactly do you do?"
] | [
false
] | null | [
"I'd refer to my response. You're asking why can't the entire discipline of psychology be replaced simply with neuropsychology. Similarly, one can ask why can't biology be replaced with physics or chemistry. It's a different scope of things, and you can't always stick a simulation into a computer when you're dealin... | [
"While a valid question, I suspect this post is more appropriate at AskAcademia or AskSocialScience. I spent a year studying psychology and I too, had the same questions and doubts before I moved onto biology. At the time, psychology as a discipline was too amorphous and abstract for me.",
"Now with a few years m... | [
"Group therapy is a world away from 'just talking' with friends and family, and has different effectiveness. Just because disorders have biological correlates doesn't mean the biological approach is the best. Psychology also has nonclinical applications. ",
"Psychoanalysis was applied philosophy in Freud's time, ... |
[
"Are there scientists that study other scientists?"
] | [
false
] | null | [
"A number of anthropolgists did a study of physicists at the Large Hadron Collider by embedding themselves in the population:",
"http://www.nature.com/news/2010/100324/full/464482a.html"
] | [
"I know a guy doing a PhD in Philosophy of Science. I don't understand it, but basically he studies flow of information between scientists and how different factors such as reputation, impact of work etc.. control the flow and direction of fields and research. Really confuses me to be honest. "
] | [
"But who studies the scientist studying scientists?"
] |
[
"How do the Japanese Snow Monkeys dry off without dying once they leave the hotsprings?"
] | [
false
] | [deleted] | [
"The snow monkeys (macaques) have a thick layer of fur close to the skin that effectively protects it from getting wet. If you watch them climb out of the hot springs they’ll often shake the water off the fluffy outer fur and then they’ll be essentially dry."
] | [
"Of course they do. They also feel cold too, which is why they hang out in the hot springs.",
"Their fur is designed to prevent them from staying wet and becoming popsicles in the cold weather when they leave the hot spring."
] | [
"Their real issue with the cold is not getting dry, but staying warm at night while they sleep. They sleep in the trees, and if they can’t find a group to huddle with they freeze to death."
] |
[
"Did neanderthals breed with homosapien?"
] | [
false
] | [deleted] | [
"A similar question was just asked a few hours ago, but I will answer yours with the same answer I gave the previous OP. The simple answer for you is yes, certain populations of humans (non-african populations) and neanderthals interbred and yes these offspring were fertile because we still have 1-5% Neanderthal DN... | [
"This observation has prompted the hypothesis that whereas female humans interbreeding with male Neanderthals were able to generate fertile offspring, the progeny of female Neanderthals who mated with male humans were either rare, absent or sterile.",
"Or there could have been a small number of matings and the mD... | [
"Or the small amount of neanderthal DNA could be explained by a common ancestor. There are many unknowns. The point is that evidence to date points to human-neanderthal hybrids being: infrequent, not ubiquitous across the two species, and probably infertile in some cases. Which indicates that hybrid vigour was low,... |
[
"How exactly did we determine that a mole = 6.02214179(30)×10^23?"
] | [
false
] | null | [
"The Avogadro constant is defined by ",
"NIST",
" as 6.022 141 29 x 10",
" mol-1. It is the relationship between constituent particles of a substance and the mass of said substance. ",
"The way we \"determine\" the value right now is making the assumption that an Avogadro's number of Carbon 12 atoms weights... | [
"I was under the impression that, as OrbitalPete said too, Avogadro's constant is defined as the number of atoms in 12 grams of carbon-12. Which means that it's not defined as any specific number but instead measured. And the number you have is an accurate measurement of that. Even the page you linked gives the unc... | [
"NIST is a defining body for the constant. Of course, NIST did not just make the number up. If you search their bibliography, you can find 69 citations that reference the word Avogadro. It is a highly measures constant, but at some point, someone has to define what the value is. NIST defines the value based on the ... |
[
"What determines a \"match\" for a kidney transplant?"
] | [
false
] | I figure that blood type plays a huge rope but im sure there are other factors too | [
"Blood type and the HLA (human leukocyte antigen) alleles. HLA is expressed on all cells and is recognized by your immune system to distinguish 'self' and 'non-self' cells. HLA locus can vary between individuals and are more likely to be a match the closer related you are i.e. direct siblings, parents.",
"general... | [
"Hi, I work at a histocompatibility lab. tinyping, cmuadamson, JStanton617 are all correct. I just want to elaborate a bit more. ",
"In our lab, we do genetic testing to see what HLA alleles the patient and donor have. To evaluate compatibility, we look at a total of 10 alleles (A, B, C, DR, DQ). The patient can ... | [
"Some alleles of the HLA are more common than others. If you have more common alleles you may find a match in 1:10,000, while others with rare variants could be up to 1:500,000"
] |
[
"Why do low pressure areas form at warm places if pressure is directly proportional to temperature?"
] | [
false
] | null | [
"You're referencing the ideal gas law. We use that law in a lot of our derivations for the behavior of the atmosphere, but you should remember local regions are not constrained to a constant volume. Subsequently, sometimes our observations are somewhat counter-intuitive.",
"In regards to your question, I usually ... | [
"The volume of the air increasing due to the higher temperatures will mean that there will be less of it above you. The air cant keep going up the atmosphere forever so it'll move aside and you'll end up with less air in total above you."
] | [
"To add to the other comments, wheb people talk about \"volume\" in this context they are referring to molar volume, or the volume per mole of gas. This is like a sort of inverse density. If we consider the ideal gas law, PV= nRT, we can divide both sides by n to get PV/n= RT. This form has a number of advantages- ... |
[
"Given what we know now about the coronavirus how big a role does asymptomatic transmission play in spreading the virus?"
] | [
false
] | [deleted] | [
"It’s been difficult to separate “asymptomatic” from “presymptomatic” and “mild symptoms”. The latest review I’ve seen determined that careful tracking found symptoms in most patients, with just 15-40% being completely asymptomatic (",
"Estimating the extent of asymptomatic COVID-19 and its potential for communit... | [
"asymptomatic spread can be dangerous in the sense of ",
"- psychologically people think \"oh I don't have it, lets go party\" and this causes spikes which we witness when people organise huge events like a 400 guest wedding",
"- if you are careless and assume \"I will just avoid sick looking people\" you are j... | [
"well, first you need to separate asymptomatic cases from \"currently asymptomatic\" cases. It's turns out that the peak of the infectivity for symptomatic cases is 2 days before symptoms onset. ",
"It's also starting to become clear that people that will never experience symptoms ",
" will infect less people. ... |
[
"[Medicine] What is special about peanuts that make some people extremely allergic to them?"
] | [
false
] | Why are some people allergic to peanuts in particular? Why is ingesting a peanut to these people akin to ingesting poison to others? | [
"Peanuts contain high levels of several heat-stable proteins, collectively known as Ara h proteins (from the scientific name ",
"), that can act as antigens. Some people develop IgE antibodies against these antigens, which causes a peanut allergy. Sources: ",
"https://link.springer.com/article/10.1007/s11882-01... | [
"If the antigens are proteins, why can't some people with peanut allergies eat peanut oil fried foods? Are there traces of the protein in the oil?"
] | [
"If a chemist were to purify peanut oil it would be tolerated by an allergic person. Peanut oils that are comercially available are not \"pure\" and contain trace protein contaminants that are enough to trigger anaphylaxis."
] |
[
"In a desert, what is under all of the sand?"
] | [
false
] | I've always wondered, in stereotypical deserts with plentiful sand dunes, how deep does the sand go? And what's under the sand? Water? Dirt? Stone? | [
"I'm going to focus on the Sahara, because that lets me crib from ",
"this comment",
" I made a year ago. You can apply this same stuff to any desert, though!",
"First, I'm required to point out that deserts like the Sahara, contrary to popular belief, are mostly ",
" covered in sand dunes. ",
"Here's a m... | [
"This is a great answer! I love that you punctuated it with links and relevant images, it really helped me visualise what you were talking about."
] | [
"I've noticed my sugar do that when I pack it too tight. It got all chunky and not flowy"
] |
[
"Could the red tint of Europa's ice be cause by biology? Could this be confirmed without taking samples?"
] | [
false
] | null | [
"Possibly, this is an example on earth",
"http://en.wikipedia.org/wiki/Blood_Falls",
"It could just be minerals of iron in the ice, which don't have to come from a biological source at all. "
] | [
"Good info, thanks. With the imagery/data we have - would NASA be able to tell the difference? Would some kind of spectra analysis help? I find it kind of mind blowing that maybe the surface of this moon is stained with life and we might not even realize it."
] | [
"It is indeed interesting, I can't wait until they send a probe to some of the moons of Jupiter and Saturn that can send back some good data.",
"As for being able to tell the source of the iron etc, I don't think that any imaging techniques or spectroscopy that could determine that. It can tell you what is there,... |
[
"Why are bodies of water (such as lakes or ponds) calmer at night?"
] | [
false
] | I walk my dog around our complex's pond every morning and night, it seems a regular occurrence that the water is choppy during the morning/day and clear as glass at night. When I think about it, I've noticed this on lakes too (grew up living next to one). Is this just my imagination or is there some real science behind this? | [
"Its when they are sleeping. J/k. To really answer this question, you want to know what causes waves, and that is wind. So you then need to ask what causes wind... but here is my late night answer.",
"Waves are caused by winds blowing over the water. (we will leave out tidal forces for this discussion). During th... | [
"Wow, I totally overlooked the concept of heat causing wind (which obviously causes waves). Such a simple answer that I feel embarrassed for asking now!",
"I wouldn't be surprised to hear there are other minor forces at work here too, but I'm pretty satisfied with this answer assuming it's truly the primary fact... | [
"As an addition to this. At night, it tends to be less windy the closer you get to the ground. Wind closer to the ground tends to find it origin in temprature differences on the ground, and wind higher up is due to pressure difference on a more grand scale. That's why windturbines even work at night, when it seems ... |
[
"If energy can't be created or destroyed how much energy is there in the universe?"
] | [
false
] | Is there a way we could estimate this value ? | [
"It is not actually necessarily true that energy can't be created or destroyed (which, in more formal language, is the statement \"energy is conserved\"). While we can often define something called the \"total energy\" for a system, in doing so we're making certain technical assumptions about it (specifically that ... | [
"Lawrence Krauss explains a little bit about this in laymans terms in his book 'A Universe from Nothing'. Something something about how the total energy of space increases as space itself expands, and ultimately how he believes it is possible for something to originate from nothing because of quantum mechanics.",
... | [
"According to current theories, the total energy of the universe may be zero.",
"http://www.lifeslittlemysteries.com/1224-total-energy-universe-zero.html",
"http://en.wikipedia.org/wiki/Zero-energy_universe",
"http://www.astrosociety.org/pubs/mercury/31_02/nothing.html"
] |
[
"How did the icecaps end up so much higher than ocean level?"
] | [
false
] | null | [
"What do you mean exactly? If you're talking about sea ice, it's floating in the water just like and ice cube in a glass of water. If you're talking about continental glaciers, they form not from seawater but snowfall accumulated over many thousands of years."
] | [
"The latter, oh that's so obvious now that you said it..."
] | [
"There's a caveat to that, however.",
"East Antarctic ice fields are many thousands of feet above sea level, supported by very thick and strong cratonic crust. In West Antarctica, however, the earth's crust has undergone rifting and thinning, is no longer able to support the weight of its icecap, and has slowly s... |
[
"Using dry ice to chill a drink?"
] | [
false
] | [deleted] | [
"I think there won't be a problem CO2 is used to carbonate drinks anyway. There are even DIYers who used dry ice in sealed containers to carbonate a whole bunch of weird things like fruits. ",
"The only risk is over chilling your drink and giving yourself brain freeze. You would also have to wait for all the dry ... | [
"here's",
" the tutorial. Imagine pieces of fruits that fizzes in your mouth like alkazelsers."
] | [
"Please explain carbonated fruit"
] |
[
"Does cooking meat for too long lower its nutritional value?"
] | [
false
] | My ex refused to use a crock pot because she was convinced that simmering meat for 8 hours broke down the proteins in it to the point that they were damaged in some way and less healthy than meat cooked in a more traditional way. Is this nonsense? | [
"Proteins are broken down in the digestive tract anyway. Generally you don't absorb intact proteins but rather the individual amino acids they are composed of.",
"For this reason the denaturation of proteins during cooking is not a problem at all. On the contrary, it will aid in their digestion.",
"However, if ... | [
"Actually, studies have shown that yes, cooking does break down proteins, but this actually allows humans (and mice) to absorb more usable energy from cooked meat. I believe the theory is that you don't have to spend as much energy digesting, and the proteins are more readily taken-in. In an experiment with mice, r... | [
"I think this answers it pretty conclusively. Thanks!"
] |
[
"endangered species solution?"
] | [
false
] | null | [
"Komodo dragons actually have a ZW sex determination system, that is, females are ZW at the sex determining locus, while males are WW. In this case, females produce a haploid egg, then the chromosomes double to produce a male that is homozygous at every locus. Any recessive deleterious alleles are going to show u... | [
"Chromosomes which determine gender are not universal. XY is limited to most mammals.",
"Many cold blooded (though cold blooded is a bit of an outdated term, that's another question) animals are either hermaphroditic or have gender determined by environmental factors. Because they have no sex chromosomes it's m... | [
"Irrelevant question: are the chromosomes actually in a shape which looks like a Z or W?"
] |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"I see allot of questions unanswered, and it bothers me is this usual?"
] | [
"How much energy do typical fast-breeder nuclear reactors produce compared to water reactors? Is fuel conversion a tradeoff for lower energy output, or are they just 'better' overall?"
] | [
"No, flamethrowers need oxygen to burn. It might be possible to find the right exothermic mix that replicate what a flamethrower does but a regular flamethrower wouldn't work. It would just squirt fuel around."
] |
[
"Where is everything?"
] | [
false
] | null | [
"I concede that it's a philosophical question, but don't you consider where all things must be?",
"That isn't a philosophic question, it is a semantic one."
] | [
"I think it really is more of a philosophical question. Sure, anything that exists is somewhere, but likewise, that place is only there because it exists. I'm really not sure that is a question that HAS an answer beyond the tautological one: Everything is where it is. Just being makes it there. To think that all th... | [
"Observers moving at different velocities can't even agree on the spatial location or velocity of other objects.",
"You're really talking about philosophy, not anything relevant to science."
] |
[
"Ask Anything Wednesday - Engineering, Mathematics, Computer Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"On the I.S.S. they are continuesly learning about space agriculture. I know that NASA has been doing experiments and trials with soils and different types plants.\nMy questions are, has NASA looked into self contained and sealed hydroponics systems? Other than no gravity and the proper seal of the fluids, what wou... | [
"You might be interested in ESA's ",
"citizen science hydroponics programme."
] | [
"It still looks in in infancy stages and 5 years no updates. And isn't lettuce not very nutritious."
] |
[
"Is there a physical Limitation on how dense we can store data on a HDD Platter?"
] | [
false
] | Ok, from my understanding, correct me if im wrong, we are currently reaching the physical limitation of cpu transistors. But what about good old HDD's? They seem to manage to cram more and more data onto 1 platter, but is there a phyical limitation on how much information we can store on 1 platter? | [
"A key limit in magnetic storage is that random thermal energy alone can alter the magnetization of suitably small crystalline regions (grains, which constitute magnetic domains). Near this limit, we can no longer depend on the information persisting over the necessary operating time. This is discussed well ",
"h... | [
"is there a physical limitation on how much information we can store on 1 platter?",
"Of course. There is only a finite number of atoms in the readable part of a HDD platter, so even if we could assign one bit per atom (and we are very, very far from that) the storable information would still be finite (albeit en... | [
"A steady temperature alone is enough to randomly erase the data over time, if the grains are too small. So you could keep the hard drive at a consistently lower temperature. I don't know if this has been implemented in applications. You also look for materials that exhibit ",
"as high magnetization as possible",... |
[
"how does chirality come into play when manufacturing pharmaceuticals?"
] | [
false
] | I understand what it is I just dont get how a mirror of a molecule would come into play. are they connected? do they come in pairs and the other molecule has to be flushed out? does it just happen by accident that a molecule chiral partner slips into the mix and isnt easily spotted because of its likeness? please explain. | [
"not quite, it's the difference between generic drugs and the brand's 'new and improved' drug -- eg omeprazole vs esomeprazole"
] | [
"If a molecule has two chiral forms (enantiomers), laboratory synthesis will generally make a 50/50 mix of the two. That's just how it happens, because they're so similar. The R and L enantiomers have identical chemical properties across the board, and can be very difficult to separate.",
"It's only when you get ... | [
"Pharmacy student checking in. There are many many chiral drugs. Ibuprofen (Advil) is a great example. Advil's S enantiomer is more biologically active, but the R enantiomer is not toxic and is actually converted to the S enantiomer ",
", so Advil is sold as a racemic mixture because while chiral molecules can be... |
[
"My cooler is half full with a mixture of 50% ice cubes and 50% cold water. I want to add more ice. Should I drain the water first?"
] | [
false
] | This dilemma has plagued me since my freezer/fridge died a couple of weeks ago. Does the cold water help or hinder the future longevity of the coldness? | [
"The water definitely helps. Water has a really high specific heat. This means it can absorb a lot of energy without changing temperature much. Either way, you are going to lose ice at roughly the same rate (if we're talking about an ideal theoretical cooler). But at once all your ice melts, if you didn't drain the... | [
"I have had the same dilemma. I think the answer is this: ",
"If the food is from the freezer (T< 0C), empty the water. If it is from the refrigerator (T> 0C), keep the water.",
"The water/ice mixture is going to tend to keep everything at a temperature of 0C. If your goal is to keep the temperature less t... | [
"Yes, but air is such a terrible heat conductor compared to water. This is what mainly leads to my dilemma. "
] |
[
"Are there any known cultures where it is or was common to practice sex openly in front of others, including children?"
] | [
false
] | null | [
"You're thinking of the ",
"Etoro",
", a tribal group located in Papua New Guinea. "
] | [
"I am not so sure about this one. Our anthropological sources, who were mainly missionaries or 'proper' 19th century men, were not so keen on recording sexual practices, and if they did, they often did it with an exotic message in mind (to show how 'uncivilised' or different other peoples were).",
"I read that in... | [
"Could you post a source for this?"
] |
[
"With the introduction of vaccines, even if a variant isn’t strictly “covered” by the vaccine due to changes in proteins, would there be enough “training” of the body’s immune system on how to deal with a corona virus that the body would be more efficient if infected later?"
] | [
false
] | At the start of the Pandemic, a lot of the concern was about the novelty of the virus and the fact that the majority of humans would most likely not have contacted a coronavirus and so the body wouldn’t know how to efficiently “fight” it This is often cited as why the flu is no longer (generally) as bad, due to “people” having seen some form of flu at some point in their life. | [
"Short answer: Yes",
"Long answer: Probably",
"When you get exposed to an antigen (by getting infected or by getting a vaccine), your body generates B cells (generate antibodies) and T cells (recognize and kill infected cells). ",
"I'll focus on B cells: ",
"First, there will be a B cell that, just by rando... | [
"I would imagine it depends on the mutations that occur.",
"There are hundreds of \"variants\" since small microbes like viruses replicate so often. Mutations occur inevitably. I think its a matter of the spike protein of the virus and if that mutates.",
"Antibodies attach to the spike on the surfaces of viruse... | [
"Lovely analogy.",
"What people don't realize is that antibodies bind to their targets partially even if they aren't a perfect match, but are close. Effectiveness fades gradually before it falls off a cliff to 0.",
"Now if a mutation causes the virus to bind to ACE2 more efficiently, enter the cell more quickly... |
[
"If plants use water to produce oxygen, does that mean that over time the total amount of oxygen on earth slowly increases?"
] | [
false
] | As I understand it, photosynthesis in plants convert water to oxygen, and it converts carbondioxide molecules into sugar molecules. Plants don't actually convert carbondioxide into oxygen. The carbondioxide gets converted into sugars, which when the plants decay actually put carbondioxide back in the air, or which will end up in the ground. . So, considering that, does that mean that over time the total amount of oxygen on earth actually increases? Bonus questions: - What does this mean in terms of climate? - Does this mean that the earth's atmosphere slowly gets thicker, or does oxygen simply float out into space? | [
"Oxygen does increase over cycles, but then it falls back down.",
"In addition to producing oxygen by taking in carbon dioxide, plants ",
" animals take in oxygen and produce carbon dioxide through cellular respiration.",
"This process creates the compounds we use for energy storage.",
"Um, neither. To prod... | [
"The atmospheric balance is dynamic - it can and does change over time. However, there are various processes in action, some of which tend to stabilise atmospheric concentration and others that exacerbate it.",
"In the first instance, plants are one stage of a cycle. While plants do create both oxygen and sugars ... | [
"On a geologic time scale, yes, but it depends on the system and what is present to use, sequester, or release oxygen. There are many ways that the system is in flux, take a look at the ",
"Great Oxygenation Event",
", about 2.4 billion years ago. Bacteria slowly started to \"poison\" the atmosphere with oxygen... |
[
"Is the universe as a whole \"heating up\" due to the stars everywhere outputting tons of energy (radiation, solar winds, supernovae)?"
] | [
false
] | Also, might this explain the accelerating expansion of the universe? ("dark energy") | [
"The universe is actually cooling, not heating up. Energy is conserved. Neither created nor destroyed. If you take a constant amount of heat and spread it over an increasingly large area, the temperature everywhere is dropping.",
"Also, might this explain the accelerating expansion of the universe? (\"dark ene... | [
"You can have a closed system heat up. Say I'm in a closed system and I have a match and some flammables. When I light the material on fire, the closed system will heat up. Energy is still conserved."
] | [
"You're thinking of a closed system that has a fixed volume. Not a system that's expanding.",
"The heat you see at any one point will go down as the energy-density drops. And density drops when volume increases."
] |
[
"Why do we use three phase instead of two phase?"
] | [
false
] | I understand why we use three phase electricity instead of 4,5,6 etc but why don’t we use 180 degree shifted two phase systems? Thanks in advance | [
"The main benefit of 3-phase power is that the available power is never 0. ",
"A 180-degree shifted 2-phase system would actually be very similar to the 1-phase system that most household outlets provide. One of the downsides of this is flicker. Electric devices must contend with short periods of no power ",
... | [
"120 times a second, actually. The wave crosses the x-axis twice from crest to crest."
] | [
"In a 3-phase wye system, the neutral current is theoretically zero if each phase is loaded equally, ie ",
"sin(a) + sin(a + 120°) + sin(a + 240°)",
" is 0 for all a.",
"This is not true for 90° 2-phase, and 180° 2-phase has no inherent ",
" information that would compel a motor to always spin a certain way... |
[
"Scientists always say that most of the stars today were created when bigger stars died. I always thought bigger stars died when they ran out of hydrogen, where does the hydrogen for the new stars come from then?"
] | [
false
] | Thanks for the answers in advance, I am really curious since this question popped up in my mind several times over the last few months! | [
"Stars aren't created from the 'ashes' of dead stars. All stars pretty much form the same way: from collapsed clouds of hydrogen gas, which is itself left over from the big bang. ",
"These gas clouds get 'enriched' (or 'polluted,' depending on how you want to look at it) by the heavier isotopes/metals produced by... | [
"I would like to add that a star does not fuse ",
" of the hydrogen in it. In fact only the material in the core is fused. As the hydrogen in the core runs out they begin fusing heavier elements, which makes the star hotter inflating its size significantly. The outter layers of the star will eventually be shed... | [
"Most of the hydrogen in a star is only used for its weight, which enables the fusion in the stellar core."
] |
[
"Why did nucleosynthesis in the early universe allow neutrons to merge quickly with protons, but not allow protons to merge with each other?"
] | [
false
] | At the time, was the pressure and temperature too low for this to happen? | [
"Two protons merging forms Helium-2, which is very unstable and nearly always decays back to two protons. There is a (very) small chance that helium-2 might decay to hydrogen-2 (deuterium), which is stable. (This decay is what powers the Sun, incidentally)",
"Deuterium is stable, but only just and at temperatures... | [
"I think it's because ",
"p + p -> d + e",
" + ν_e",
"Is a weak-mediated process, while ",
"p + n -> d + γ",
"Is EM. So it's many, many times faster. I think this is the main factor.",
"Primordial nucleosynthesis happens a while after the decoupling of the weak force, so weak interactions have already b... | [
"Exactly the response I was looking for. Thank you very much. Also, do we estimate the time to be 17 minutes due to the expected conditions at the start of the Big Bang and extrapolate the conditions in which nucleosynthesis would occur and thus the time?"
] |
[
"Where does the energy for osmosis to work come from?"
] | [
false
] | null | [
"There is ",
" in having a membrane separating two compartments with a concentration gradient, and that's where the energy comes from."
] | [
"Indeed, a system where both compartments have equal concentration has higher entropy than one with a concentration gradient."
] | [
"Just wondering, would it have anything to do with entropy?"
] |
[
"Why do red letters on a blue background seem to shimmer or flash when viewed in peripheral vision?"
] | [
false
] | I have a t shirt that’s deep blue but has crimson letters on it. When I look directly at it nothing seems unusually but I’ve noticed that when it’s in my peripheral vision like when I’m using my phone for example, I notice the red letters seem to jump around and kind of flash when my eyes move. What’s causing this? I thought it might have to do with chromostereopsis but I was hoping someone might be able to give me an in depth explanation. | [
"Your peripheral vision is constructed by a bunch of very quick motions of your eyes. Your visual processing filters these motions out of your perceived vision, giving you the experience of a contiguous visual field.",
"When your eye darts over to look at red text on a blue background, it struggles to focus enoug... | [
"This seems to me to be less about psychology than about optics. Red and blue light have different focal lengths, which is why our eyes exhibit ",
"chromatic aberration",
" when looking at red things on blue backgrounds. You know how on a prism, red light bends the least and blue light bends the most, and all t... | [
"When you look at how a prism splits light, blue and violet light bends significantly more than red. In fact, as far as visible colors go, red and blue have just about the most difference in how much they bend. (Only violet bends more, but the way we typically make colors that simulate true violet is by blending re... |
[
"If you had to cross a desert by foot, would it be better to walk or run?"
] | [
false
] | null | [
"First, the math:",
"s = speed",
"g = grade",
"Oxygen consumed during walking = .1s + 1.8sg + 3.5",
"Oxygen consumed during running = .2s + 0.9sg + 3.5",
"Basically, those formulas show that walking on a flat surface is much more efficient than running on a flat surface.",
"Our oasis is six miles away, ... | [
"I was referring to your body's water. Please note I'm not a desert survival guy, I'm a physiology guy. The math says walk, so I would walk."
] | [
"take it slow and conserve your water",
"By \"conserve your water\", do you mean that you should ration whatever drinking liquids you have? Or are you saying conserve your ",
" water by exerting yourself as little as possible?",
"I've always been told to ",
" ration drinking fluids, but rather to drink whe... |
[
"Do lab workers/scientists have the option to take home lab rats as pets instead of euthanize them?"
] | [
false
] | I guess this can apply to psychology as well. Obviously you wouldn’t want to take home lab rats who’ve had regions of their brains ablaised or their neural circuits significantly impacted for purposes of the studies. But for studies that don’t require you to modify their brains, why do they have to be euthanized afterwards, and do the scientists/lab workers have the option to take them home as pets after the study’s conclusion? Are there safety and ethical concerns even with Wistars, Sprague-Dawleys, and Long-Evans? | [
"In all of the research protocols I’ve seen they call for euthanasia as the endpoint. My lab has to euthanize our mice because they are all transgenic. They wouldn’t necessarily cause any extreme changes if they were exposed to the wild population, but there are definitely strains out there that would!"
] | [
"Depends on the experiments conducted and the breed, but generally yes. I even know some students that adopted rats from neuroscience labs.",
"In Germany it is not allowed to take transgenic rats home. Also some experiments require the scientists to kill the rats for further testing of some organs.",
"Although ... | [
"I also wonder how mice/rats kept in sterile conditions would do when exposed to microbes when brought home. Certainly there immune systems would have been impacted in some way."
] |
[
"Which is the stronger bond for platinum: oxygen or nitrogen?"
] | [
false
] | Would the oxygen bonded to platinum be displaced in the presence of nitrogen? | [
"If by Nitrogen you mean N2, then no. Molecular Nitrogen is fairly inert compared to Oxygen and from my quick research it doesnt seem to react much with Pt. Platinum will react with Nitrates (XNO3) to form Platinum Nitrate (Pt[NO3]4) but that decomposes into ",
"Adam's Catalyst",
" which is PtO2, leading me to ... | [
"This is correct. Oxygen is more electronegative than nitrogen, meaning it will form a better bond"
] | [
"Electronegativity is very important, but oxidation state is important too. So a not particularly electronegative element like Chromium can become a powerful oxidizer if you get it into a very high oxidation state."
] |
[
"How true is it that biology reduces to chemistry..."
] | [
false
] | Which reduces to physics, which reduces to mathematics? And math's axioms can't be proven. If this is true, does the scientific method change from top to bottom? | [
"Physics doesn't reduce to math, physics is described by math, as are chemistry and biology. Mathematics doesn't rely on the existence and characteristics of the universe, whereas sciences do."
] | [
"I wouldn't say that physics reduces to mathematics. While physics is more or less just applied math, math by itself doesn't have inherent 'meaning'. I don't say that to demean math but the mathematical concepts are only applied to model the physics, not as the underlying reason for physics. Math is also used in th... | [
"I think OP is talking about ",
"this",
" XKCD comic."
] |
[
"How flat is it possible to make something?"
] | [
false
] | And if scientist and engineers came together to try and make the flattest, straightest table (1 meter long) possible, would it be closest to absolutely flat, or the curvature of earth? | [
"\"Graphite sheet\" = graphene, a single atomic layer of carbon. It is theoretically very flat, but practical considerations come into play. It adopts the morphology of the underlying substrate. ",
"Producing a 1mx1m sheet of graphene is, currently, totally unfeasible."
] | [
"\"Graphite sheet\" = graphene, a single atomic layer of carbon. It is theoretically very flat, but practical considerations come into play. It adopts the morphology of the underlying substrate. ",
"Producing a 1mx1m sheet of graphene is, currently, totally unfeasible."
] | [
"50 micrometers is considered large and beyond 1mmx1mm is currently unfeasible. Sure you can make larger but then you start introducing grain-boundaries and all sorts of other defects that destroy the ballistic transport properties that make graphene so interesting."
] |
[
"Would it be possible to utilize Earth's magnetic field (possibly at the magnetic north pole?) to propel, or significantly aid propelling, a spacecraft into a near-orbital trajectory?"
] | [
false
] | null | [
"Such hypothetical / speculative / open-ended questions are better suited for our sister-sub ",
"/r/asksciencediscussion",
". Please post there instead."
] | [
"How could I reword this to fit this sub? I am legitimately looking for an answer, not just Karma. I wanted to post it here because you all have millions of members willing to answer while discussion has 57k, and I would very much like to get plenty of good answers."
] | [
"All people who have flair here have flair there as well. That sub is especially designed for discussion-based and speculative questions."
] |
[
"What is the latest in Classification?"
] | [
false
] | I am a hs science teacher going to teach the unit on Classification. Right now our 15 year old textbook teaches Kingdoms as Animalia, Planta, Protista, Fungi, Archaebacteria, and Eubactera. I know that this field is always changing but also heavily debated. I sort of feel bad teaching something that is no longer relevant, but at the same time there isn't really a consensus I can find to show what is the newest. I definitely teach that it is a man made science and not perfect but... | [
"I don't know the answer, but thank you for working so hard to provide the best education you can. Reading that there is a teacher who puts this amount of effort into their work made my day, from the bottom of my heart, thank you."
] | [
"Teaching classification is always hard - I try to use Kingdom/Phyla when I can, but also like to use Domains (Eukarya, Bacteria, and Archaea) and Clades to indicate related-ness between and among organisms. The Protists are the hardest to keep track of since they're always regrouping them, so I teach them as auto... | [
"Monera....well at least I'm lucky we've moved past that. We had some faculty using that forever as well. Plus I saw that Chromalveolata may not be valid anymore - instead now Discicristates (I think)?"
] |
[
"Given that our vision is based on the reflection/refraction of light and light cannot escape the event horizon of a black hole, will we ever be able to capture in image past the EH or of an actual black hole?"
] | [
false
] | [deleted] | [
"No. We will never capture an image of what lies beyond the event horizon.*",
"We may capture an image of a black hole, though, which includes the event horizon.",
"* There is no confirmed information that negative energy is a practical quantity that can be used to access a black hole, even if it has been theor... | [
"I don't even think you can take a picture of anything that has gotten close enough to the event horizon for light to not be able to escape",
"That is the very definition of the event horizon. If light can escape, you are outside it. If it cannot, you are inside it. There is no outside where light cannot escape."... | [
"No known mechanism exists to convey information from within an event horizon to outside, including the sort of information we'd use to produce any image."
] |
[
"Is it physically possible to create a square wave (sound)?"
] | [
false
] | The speaker cone moves in and out corresponding to positive and negative amplitude. In a square wave, it instantaneously jumps from +1 to -1. Is there a way to create this sound pressure wave (not necessarily with a speaker)? And as a second question, could our ears even hear it given the fact that the timpanic membrane has to make the corresponding movement? Thanks | [
"To create a perfect square wave, you'd need a contribution from all possible frequencies of sine waves. But any real source has some finite range of frequencies (a \"bandwidth\") that it can properly produce.",
"So you can never get a perfect square wave, but you can get arbitrarily good by increasing the bandwi... | [
"Right, but not",
"all possible frequencies of sine waves",
"You'd need all the odd harmonics of the fundamental frequency. "
] | [
"We can never create a perfect square wave, if that's what you are asking, in the same way that we can never draw a perfect circle. "
] |
[
"Some prime numbers, like 5, can be factored with complex numbers. Are there any prime numbers which can't be factored ever?"
] | [
false
] | If we allow factors from C instead of just R, 5 = (2 + i) * (2 - i). A little googling led me to a funky idea called "gaussian primes", or numbers which are prime on the complex plane. Many of the real number primes seem to lose their primeness once complex factors are involved. My intuition is that if you add another plane, j, many more of the primes on C and R will become factorable. Even more once you add k,l,m,n, and so on. Are there any "super primes", which won't factor no matter how many dimensions you add? If so, do they follow any patterns? Or, is the only way to tell them apart a brute force search? If not, how many dimensions do you need to make all of R factorable? what about all of C? | [
"Firstly, when you talk about factoring, we're not doing it in R, we're doing it in Z which is the set of integers. It doesn't make much sense to talk about factorization in R because there are no primes in R because every nonzero number in R is invertible and it only makes sense to talk about the primeness of numb... | [
"You can't build quarternions or octonions in this way. In a way, I wouldn't consider them number systems at all because of this. And the fact that they tell us ",
" information, about rotations and such, without giving us any new arithmetic information about the integers would seem to suggest that they are more ... | [
"The Gaussian integers are the ring generated by Z and sqrt(-1). If you instead generated it by Z and sqrt(3), you'd be able to factor three. And if you just use all the reals, then there are no primes and everything is factorable. Every number is divisible by every number except zero."
] |
[
"Why are some CDs unable to remove something that has been burned onto it?"
] | [
false
] | null | [
"Precisely that. A laser heats a dye and permanently alters its reflectivity, \"burning\" the information into the physical structure of the disc."
] | [
"This gives a fairly simplistic yet accurate description of both the answers you're seeking."
] | [
"but how come some CDs can be altered?"
] |
[
"Is there actual benefit to breathing in 'fresh' air as opposed to sitting in a room?"
] | [
false
] | null | [
"Air pollution in homes can be much worse than outdoor air. So, depending on the air quality in your home or building, it can probably be argued that you lower your overall health risks by spending more time outside. Note that pollen and fungi levels tend to be higher outside than inside. ",
"From: ",
"http://w... | [
"Engineer from a Consulting firm here. We do building construction all the time. Particularly, I am in charge of HVAC, piping, and fire protection design for projects of various types including; institutional facilities, commercial buildings, medical campuses, educational facilities, laboratories, and government fa... | [
"Germ theory was pretty revolutionary. The whole idea of tiny animals that make you sick can take a little getting used to. I'm not trying to defend her for ignoring the science, I merely suggesting that it's a little unfair to judge her by todays standards. Some people think the Higgs boson doesn't exists, and som... |
[
"Is there a genetic basis behind genius-level intellect?"
] | [
false
] | Has research discovered any specific genes or alleles that are correlated with a higher level of intelligence? If so, have they been able to pair specific genes/alleles to specific skills (ie. math, visual-spatial awareness etc.)? | [
"Intelligence is a ",
": meaning that a LOT of genes contribute to your intelligence (there are also environmental factors but because you asked we will concentrate on genetic ones). Intelligence is also hard to measure and that field has all types of complexities of its own to deal with.",
"That said, there a... | [
"China is actually trying to find this out now, much to the chagrin of the remaining research community.."
] | [
"Awesome thanks, I'll give the article a look"
] |
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