title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"A question about SETI: Assuming that there were actual signals out there - How could we possibly hope to detect them?"
] | [
false
] | I mean, think about how electromagnetic radiation gets exponentially weaker as it propagates away from the source. Now think about nebula, gravitational bodies, interstellar dust, asteroids, and every other obstruction between here and the next hundred light years. There's plenty to mix up and scatter whatever origin... | [
"It doesn't get exponentially weaker, it goes as 1/r",
" until you start looking at absorption from gas and dust.",
"We can detect radio signals from space, for instance from pulsars or from the CMB.",
"The thinking is that if there are civilizations that are communicating across vast distances, they are usin... | [
"I think that the answer might be that we don't necessarily expect to find a signal - but if we did, it would be quite something! So we look. Chances are we'll eventually get better at it if we keep trying.",
"Note also that the intensity only decreases as the square of the distance if you're emitting in all dire... | [
"Note also that the intensity only decreases as the square of the distance if you're emitting in all directions. Directional radiation is much less lossy.",
"Not true. ",
"Free space path loss",
" is a fixed value for a given frequency over a given distance, regardless of antenna gain. If your antenna has g... |
[
"Are human beings still selectively evolving to get rid of vestigial or unwanted traits/diseases? Or has modern society and modern medicine ensured that those traits & diseases will continue to get passed down through our progeny?"
] | [
false
] | [deleted] | [
"The genetic code keeps changing, mixing up, taking on mutations, but features only get knocked out if they prevent individuals from having offspring. There's no reason to not have male nipples because they take little energy to produce and they don't prevent mating. Also, if a man didn't have nipples, a woman migh... | [
"There are also a lot of things that we generally think of as 'undesirable traits' that can actually be useful which is why they persist: ADHD (seeing/hearing everything), nearsightedness (social behaviors and reading emotions), even sickle-cell anemia (malarial resistance). It's not as simple as 'if we don't have ... | [
"unless there's a strong selection pressure happening (selective breeding), traits generally randomize. If a certain trait (e.g. reproductive tract malformation) results in you not reproducing that's a pretty strong selection pressure, and generally is reduced in the population. ",
"This is not true of all trai... |
[
"Why is it that during kidney transplants the recipients kidney is often left in place if it's not causing any issues such as high blood pressure or infection. Would it do any harm to remove it?"
] | [
false
] | null | [
"Wow, so you just add in another connection to whatever the kidney connects to, wild"
] | [
"Wow, so you just add in another connection to whatever the kidney connects to, wild"
] | [
"How does attaching another kidney not crowd the other kidney out?"
] |
[
"Why are most planetary bodies/the asteroid belt/kuiper belt aligned very similar orbital planes?"
] | [
false
] | Am I mistaken or is there a reason? | [
"The most accepted idea for the formation of a solar system begins with a big cloud of gas/dust that has some angular momentum, and as it contracts due to mutual gravity it starts to spin faster, and the spinning spreads it out into a disk, ",
"like this NASA animation",
". I always imagine it like a ball of pi... | [
"Thanks, that clears it up nicely."
] | [
"Well, the solar system is hypothesized to have formed from a ",
"nebula",
". Nebulas are just irregularly-shaped clouds of gas, and the gases (mostly hydrogen with some helium) are under the effects of gravity so they slowly move towards the center of mass. As they fall towards the center, the individual clump... |
[
"How to detect cancer"
] | [
false
] | If cancer cells have to "recruit" blood vessels to feed them, couldn't we do a whole map of the blood system regularly and just check for differences in the blood vessels to find areas where those vessels have be recruited to feed cancer cells? | [
"I see where you are going with this but there are several problems with your idea. First, it isn't cancer cells that do this \"recruitment\" but rather tumors that do it. A cell here or there has sufficient nutrients to where it does not need a new blood supply to meet it high metabolic demands. It is when you ... | [
"a whole map of the blood system",
"sounds incredibly expensive... maybe someone with some insight into medical imaging could expound on this? "
] | [
"So is there a way to screen for cancer?",
"I ask because my neighbor went to the doctor 2 weeks ago for headaches and was just diagnosed with a brain tumor, so the question that's obviously been on my mind is was there a way he couldn't known before this?"
] |
[
"How do we have pictures of our own galaxy?"
] | [
false
] | null | [
"I believe the most accurate representation was published during the 212th American Astronomical Society meeting in St. Louis, Mo. NASA's Spitzer Space Telescope was used to obtain Infra-red images of the galaxy, and scientists determined that The Milky Way is a 'Barred Spiral Galaxy' with 2 major arms and 2 minor ... | [
"I believe the most accurate representation was published during the 212th American Astronomical Society meeting in St. Louis, Mo. NASA's Spitzer Space Telescope was used to obtain Infra-red images of the galaxy, and scientists determined that The Milky Way is a 'Barred Spiral Galaxy' with 2 major arms and 2 minor ... | [
"A nice animated gif",
" created by the UCLA Galactic Center Group showing the stellar orbits of the stars at the center of our Galaxy revolving ",
" fast around some unseen object. A simple application of Kepler's Laws reveals the object at the center to be of the order 4 million solar masses. The best evidenc... |
[
"Is Adaptation a direct result of Intelligence, or is the relationship more complicated than that?"
] | [
false
] | null | [
"Again, I don't know what she means by that. How are you measuring and defining intelligence? What does it mean to adapt? I'm not sure I understand what the picture you are describing looks like or what someone is supposed to do with it. Do you mean that you are still able to read a sentence if you replaced all the... | [
"What do you mean by adaptation? Adaptation to what?"
] | [
"They were pretty general about it. It's why I think they oversimplified."
] |
[
"Are there any quadrinary star systems? (4 stars in an orbit)"
] | [
false
] | null | [
"Yes! I think the record is currently ",
"seven stars in one system",
".",
"The way it works is that only binary-like orbits are stable, ",
" you can nest those binary-like orbits. So if you have two stars in a close binary, you can have another star orbiting at a large distance from those two, and have a t... | [
"Additionally, the brightness of a star (during the main sequence) is very sensitive to its mass. A star that's twice as massive is much more than twice as bright. So a more distant massive star in your star system could be as bright as or even brighter than the Sun you primarily orbit around. There really are a lo... | [
"When you talk about these various orbits, what are we looking at in terms of distance from the other stars? In other words, if you were on a planet in one of these systems, would you see multiple suns in the sky ala' Tattoine, or would the other stars be so far away, that they would just show as really bright star... |
[
"If lightning tries to find the quickest and shortest way from the skies to the ground, why does it squiggle so much?"
] | [
false
] | null | [
"Lightning does not follow a pre-existing path of least resistance. Air is incredibly resistive, and cannot carry any significant amount of current. The only way to make it conductive is for it to be ionized, which lightning does by itself in the early parts of the strike. So it's not following a path of least r... | [
"It doesn't find the shortest or the quickest, it 'finds' the path with least resistance. Because electric currents in ionized gases are complicated that path won't necessarily be the physically shortest route.",
"In reality the current takes all paths, with the vast majority traveling along the first ionized pa... | [
"This is wrong. The return stroke comes from the ground up, as you said. But the large zig-zagging branching structures that come down from the cloud and make up the strike are totally visible before the return stroke happens. And, lightning doesn't follow the path of least resistance: it creates it. Air is so ... |
[
"Do Alzheimer patients realize they have Alzheimer?"
] | [
false
] | I don't know if there are multiple stages of Alzheimer, but I'm talking about the more serious cases here. I've known an old lady who often wouldn't even recognize close relatives anymore. What is the thought process of someone in this situation? Have there been any studies on this? Do they think they're meeting comple... | [
"You're asking a bunch of questions, so I'll try to answer them in sequence.",
"1) Patients realize they have Alzheimer's until late stage. At that point, they may or may not realize that something's wrong with them. They tend to recognize that they're in a hospital or not in their own home, but they don't kno... | [
":( Because there's not a lot to be done in this disease, regular scans aren't really indicated. Mostly, people complain to their doctors in the pre-AD stages, something called \"mild cognitive impairment\". Frank AD can't be diagnosed from that, though. Neurologists will try and rule out other diseases and med... | [
"Wow.. thanks, this was really informative.",
"What are ways to detect onset of AD? Can regular MRI scans spot any degeneration? "
] |
[
"When it’s said that the mantle is fluid, how fluid are we talking here? What kind of texture is it?"
] | [
false
] | null | [
"The mantle is best visualised as a crystalline rock, which is hot - and therefore plastic - enough to deform at the rate of a few mm per year.",
"To give it numbers, the upper mantle has a viscosity of about 2.8 × 10",
" ",
"https://earth-planets-space.springeropen.com/articles/10.1186/s40623-019-1014-x",
... | [
"It's all about timescale. If you tried to hit it with a hammer you'd be happy to call it rock. ",
"It's a fluid on geological timescales. It's a solid at short timescales."
] | [
"Correct me if I am wrong here but isn't the convective timescale of the mantle around 100 thousand years? The convective turnover timescale essentially gives you a timescale in which you can treat the mantle as fluid."
] |
[
"Nitromethane Model Fuel Evaporation"
] | [
false
] | I use nitromethane fuel for RC models. The fuel is a mix of methanol, nitromethane and oil. I understand from reading that this fuel evaporates over time. However when the bottle of fuel is left in storage it begins to create negative pressure in the container, pulling the walls in (plastic bottle). If the fuel is e... | [
"Yes, if the fuel was evaporating inside the bottle then the pressure would increase. If you put any liquid into a closed container some of it will evaporate until the partial pressure of that component in the gas phase matches the vapor pressure of the compound at the given temperature. The only cases where ther... | [
"Interesting. I don't mix the fuel myself, it was purchased this way. Also, the bottle is just a standard gallon jug, i suppose its possible that some materials could diffuse through.\nNow that the jug has collapsed (just slightly, but visibly) if I were to move it to a place that was consistently 10 degrees F wa... | [
"Likely the 10 degree increase would push the walls back out, but that depends on a few things. The more headspace (gas) in the bottle, the larger the volume change will be from Charle's law. If the bottle is mostly full of liquid then the thermal expansion will be minimal.",
"It is likely the vapor pressure of... |
[
"How does the internet work and how replaceable is it?"
] | [
false
] | [deleted] | [
"The Internet is just an idea, the idea is to connect computers so that they can share data in real time. How it is done now is via packets of data that are switched and routed to their destination. It is part optical and part electrical. The idea will not be replaced and the implementation is being constantly impr... | [
"It's very possible - what we know now as the \"Internet\" was originally called \"Arpanet\". Both are basically a switched network that interconnects locations for the exchange of information. ",
"Arpanet",
" was originally created for use by Government Agencies and Learning Institutes. ",
"The latest chan... | [
"Even if the grid is the future, it still follows the basic principles of the internet. At least at the idea level. It's not about how the packets are passed, it's more about the ability to share information. ",
"The fundamental principle of what the internet is today (ignoring all the suppression) is the ability... |
[
"How do computers simulate probability distributions?"
] | [
false
] | null | [
"So the probability density function (PDF) for your random variable X is P(x) = (1/σ√(2𝜋)) exp(-(x - µ)",
"/2σ",
"), where P(x) is the probability density for X = x (mean = µ; standard deviation = σ). The associated cumulative distribution function (CDF) is",
"F(x) = 1/2 [1 + erf(x - µ)/σ√2] ,",
"where e... | [
"And when an analytic transformation is not available, you can use the acceptance-rejection method to draw values from an arbitrary probability distribution."
] | [
"Upvote. Generically: find a random number between 0 and 1, and then find the inverse CDF of your distribution at that number."
] |
[
"How do chromosomes identify their partner chromosome after mating?"
] | [
false
] | When a sperm cell fertilizes an egg. How does the male chromosome 7 know to attach to the female chromosome 7 to make a chromosome pair and not chromosome 8, 9, 10 etc. How does Y know to attach to X as well, since they aren't even similar in length? | [
"We are still learning the details of the cellular and molecular machineries involved in both somatic (matching chromosomes pairing in almost every cell of the body) and meiotic (matching chromosomes pairing during the development of germ cells) homolog pairing. Interestingly, aside from genes involved in pairing (... | [
"Chromosomes don't attach in the traditional sense, it's local sequence homology that drives transient interactions. There are a lot of structural proteins that stabilize this interaction (",
"synaptonemal complexes",
" being well-known), and more are found every day. "
] | [
"microtubules keep track of which female chromosome is which. this is why when you suck out the female chromosomes and put another 13 in, the fertilized egg doesn't develop right, because the microtubules get broken when you just swap chromosomes like that."
] |
[
"Gravity is described as bending space, but how does that bent space pull stuff into it?"
] | [
false
] | I was watching a Nova program about how gravity works because it's bending space and the objects are attracted not because of an invisible force, but because of the new shape that space is taking. To demonstrate, they had you envision a pool table with very stretchy fabric. They then placed a bowling ball on that fabr... | [
"I found ",
"this",
" video to really help explain how gravity changes the paths of objects, I think it's particularly effective because he demonstrates it as a bending of space and time, not just space, and is able to do so by reducing it down to only 1 spatial dimension. "
] | [
"You can visualize what this guy is talking about by considering straight lines on the surface of a sphere. Remember the surface of the sphere is the space you have to work with, so a \"straight line\" means the line you'd follow if you were an ant on that sphere that's walking straight forward without turning. I... | [
"XKCD brings up the same objection. ",
"http://xkcd.com/895/",
"The real answer is that gravity doesn't just bend space. It bends spacetime. Spacetime is really tough to wrap your mind around as the time dimension acts qualitatively differently than the space dimensions. However, objects in free fall move in a... |
[
"How is a virus \"born\"? I am under the assumption that viruses are not alive, so do they reproduce? How does one come into our world?"
] | [
false
] | See title. Thanks for the answers! | [
"The replication point has been made here already, but that does not explain how viruses \"come to be\". ",
"For that I give you this",
"http://www.biology-direct.com/content/1/1/29",
"TL;DR Ancestral viruses evolved in a pre-cellular environment as selfish genetic elements and adapted to prokaryotic and euka... | [
"Not all viruses integrate into the host's DNA, and some viruses carry their own transcription machinery (such as reverse transcriptase) but most do use the cell's. They also use host cell energy and nutrients to reproduce."
] | [
"This is the most on-point answer. Further recommendations: Vincent Racaniello's ",
"blog",
". For the emergence of viruses see ",
"this",
" page, specifically the evolution and emergence section. ",
"This",
" page talks about viruses in the context of the tree of life. I also highly recommend Vince... |
[
"Why is TESS exciting?"
] | [
false
] | TESS the transisting exoplanet survey satellite is scheduled to launch soon, what are the benefits of TESS compared to other planet hunting hardware and when should we expect to hear about it's first discoveries? | [
"Scientist at <famous CS research institute> here,",
"The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey of the solar neighborhood, TESS will monitor more than 200,000 stars for temporary drops in brightness c... | [
"It will miss some, the only way to avoid that would be to launch enough copies of TESS that the entire sky could be simultaneously monitored. Given a long enough time though it shouldn't really matter, unless the planet's orbital period is exactly the amount of time it takes you to come back to that patch of the ... | [
"Followup question: How will TESS avoid missing transits when it's looking the other way?"
] |
[
"A couple questions about the big bang..."
] | [
false
] | So.. I have been wondering about the age of the universe. I often hear that the universe is around 14 billion years old. If I understand correctly, we were able to calculate the age of the universe once we determined it was expanding. Although many navel gazers still seem to think the big bang came from a singularity, ... | [
"More than that, by all accounts nothing that hypothetically \"existed\" or \"occurred\" before the start of the Big Bang can have had ",
" effect on anything that exists now, ever has existed, or ever will exist."
] | [
"I … didn't actually understand that.",
"I did see the word \"intuition\" go by, though. Stop that, right now. Your intuition has been finely honed over decades of falling out of bed, peeing and dropping things. It is ",
" when you're studying things that are completely outside the realm of human experience."
] | [
"I … didn't actually understand that.",
"I did see the word \"intuition\" go by, though. Stop that, right now. Your intuition has been finely honed over decades of falling out of bed, peeing and dropping things. It is ",
" when you're studying things that are completely outside the realm of human experience."
] |
[
"It is possible to slow a photon down to the point where it can be easily observed?"
] | [
false
] | Maybe freeze it? | [
"How are you planning on \"observing\" it?"
] | [
"Light travels slower, not individual photons. In a dense material, the photons that make up the light we see are constantly hitting atoms and being absorbed/emitted and changing directions because of that. But they all go at c between collisions. And not in a straight line. Therefore the light is slowed, but not t... | [
"It is absolutely 100% not possible to slow a photon down. There is no situation in which a single photon will not be traveling at c."
] |
[
"Symmetry breaking and forces"
] | [
false
] | [deleted] | [
"So if it weren't for the spontaneous symmetry breaking of the Higgs field, the W and Z wouldn't have mass and there wouldn't really be any difference between the EM and weak interactions.",
"The W and Z wouldn't even exist if not for the Higgs field; nor would the EM and weak interactions. It's more like what th... | [
"So if it weren't for the spontaneous symmetry breaking of the Higgs field, the W and Z wouldn't have mass and there wouldn't really be any difference between the EM and weak interactions.",
"The W and Z wouldn't even exist if not for the Higgs field; nor would the EM and weak interactions. It's more like what th... | [
"This was very helpful, thank you!"
] |
[
"What happened to me?"
] | [
false
] | null | [
"That's not a normal reaction to caffeine. It should have just made you more energetic, but energy drinks are crap. They're a ton of things that are bad for you in a can. You could have reacted to any number of things in it. ",
"Have you had caffeine (like in strong tea, coffee, or a regular soda), or any sort of... | [
"Have you had caffeine (like in strong tea, coffee, or a regular soda), or any sort of energy drink since?",
"Yes, and I have had no ill effects.",
"If all of your panic attacks have only come when drinking caffeine, I'd say it's a bad reaction to the stuff, and to just avoid it. If they come at other times, to... | [
"My son drank way too many energy drinks at an outdoor concert once - they were giving them out free, and I didn't notice. ",
"He ended up in a panic attack he described like that. We chalked it up to too many people, brand new situation, and too many energy drinks. It hasn't repeated since. He even mentioned wha... |
[
"Can SpaceX's rockets travel faster than the speed Earth orbits the Sun?"
] | [
false
] | [deleted] | [
"If Earth moves 30km/sec, everything else on Earth moves also 30km/sec. If you launch a rocket from Earth it will have this 30km/s velocity by default + anything you give it by burning propellants. ",
"The velocity needed to escape Earth's gravity is called: Escape Velocity! ",
"https://en.wikipedia.org/wiki/E... | [
"I feel like everyone should be required to player Kerbal Space Program for a few hours.",
"Can SpaceX's rockets travel faster than the speed Earth orbits the Sun? ",
"The short answer is yes. ",
"You have to remember that we are all traveling the same speed as the Earth, and when we launch we do so to the Ea... | [
"Obviously I'm not used to thinking about mechanics in space, so for some reason I didn't realize we would still maintain the 30km/sec even after the velocity needed to escape Earths gravity. ",
"If you want to get a feeling for this, i suggest you watch ",
"this video",
" explaining the basics on orbital mec... |
[
"In solids, is heat conductivity related to the speed of pressure (sound) wave propagation?"
] | [
false
] | From what I understand, sound waves typically propagate faster in a solid when compared to a gas. I was curious if there is a relation between wave-propagation and heat-conductivity in solids. What got me thinking about this was how some of the best insulators are extremely low density solids, and how sound waves usual... | [
"It's a complicated question that may has different answers for different materials (and indeed for different processing methods for a given material), but in general the speed of sound is not inherently related ",
" to thermal conductivity (though both of them increase with increasing elastic modulus).",
"But ... | [
"Pretty much, yeah. The vast majority of the bulk volume of an aerogel or similar insulating material is - you guessed it - air. That's why their lower limit on thermal conductivity is the thermal conductivity of air."
] | [
"Interesting! Thank you for the reply. ",
"So if I'm picturing this right, the structure is more of a network \n",
"(sort of like this)",
"\nof solid mass conducting the heat, with fewer volumetric pathways for the heat to flow. Is that the gist of it?",
"I'm realizing I was more interested in the nature of... |
[
"If someone has sleep apnea and they get knocked unconscious, will they die in their sleep?"
] | [
false
] | null | [
"That's why I'm asking. If you're unconscious, can your body wake you up?"
] | [
"First, I think you might have a Hollywood-esque picture of what it means to get knocked unconscious. Getting knocked out so hard, that you are unconscious for several hours doesn't really ever happen, except for a large trauma (f.e. car accident) which will almost always lead to significant brain damage in any cas... | [
"Sleep apnea does not kill you. It merely wakes you up lots during the night as you struggle to breath. You choke a bit, wake up a bit and start breathing again and then go back to sleep. ",
"The issue is not death, just a really shitty sleep. The breathing machines merely help the sufferer breathe better so his ... |
[
"How does Titan maintain its thick atmosphere?"
] | [
false
] | Most planets or moons with dense atmospheres (Earth, Venus ect) have strong magnetospheres which prevent the atmospheric gasses from being stripped away by solar winds. However Saturn's moon Titan has no real magnetic field of its own Yet it maintains a rich atmosphere. So how does the moon maintain this thick atmosphe... | [
"Solar wind and insolation are much less strong at Saturn's distance from the sun, and temperatures are relatively low there.",
"For a much more detailed explanation, just read the wikipedia entry at ",
"http://en.wikipedia.org/wiki/Atmosphere_of_Titan#evolution"
] | [
"Just a minor point: Venus does not have a strong magnetic field at all and there are no other moons with significant atmospheres. Only the earth matches the description you are putting forth of a body with a magnetic field which protects its atmosphere."
] | [
"couldn't one say that the magnetospheres of the gas giants protect their atmospheric gasses from being stripped by solar winds? "
] |
[
"What exactly will happen when you swallow a piece of chewing gum?"
] | [
false
] | What if i become lazy, so instead of finding a piece of paper to throw away my chewing gum, I just swallow it? Is there any consequences? | [
"It will not be broken down slowly over time... it will pass, just like most other indigestible materials (like fiber or coins), in stool- mostly unchanged."
] | [
"It will not be broken down slowly over time... it will pass, just like most other indigestible materials (like fiber or coins), in stool- mostly unchanged."
] | [
"You can't digest it. It passes through he digestive system and gets thrown out normally.",
"It is not recommended for very young kids to chew gum, as swallowing a lot of chewing gum can block a small intestine and create problems."
] |
[
"Are hydrates mixtures or compounds?"
] | [
false
] | I hope it doesn't sound like an idiotic question because I am truly confused. I realised I could argue that it can be a mixture, and a compound. For example, an anhydrate can absorb water from the atmosphere to form a hydrous salt. Water that is absorbed does not form chemical bonds (I am not particularly sure about th... | [
"If we use anhydrous copper (II) sulfate, and add water, it'll form copper (II) sulfate pentahydrate. H2O forms a dative covalent bond with copper. Doesn't heat break the dative bond? "
] | [
"A \"dative covalent bond\" is what's more commonly known simply as \"coordination\", and really a \"covalent bond\" in the usual sense of the word. It's in no way fundamentally different how water molecules coordinate in solutions.",
"But isn't it a chemical bond? Compounds are formed when they undergo chemical ... | [
"In inorganic chemistry, the water becomes part of the crystal.",
"Source: ",
"http://en.wikipedia.org/wiki/Hydrate"
] |
[
"Can a laser be white"
] | [
false
] | I know that lasers are of a specific wavelength, and white light is all colours combined. But I believe there is a way to combine multiple beams. If a white laser was created, would it be any stronger than a single laser of the same power as the combined? | [
"It cannot, for the reasons you mentioned. You could focus multiple lasers onto a single spot, but it wouldn't be a white laser, it would be several laser beams."
] | [
"It looks like those were actually separate lasers that focused together.",
"http://www.iqsdirectory.com/copro/66111-the-cooke/"
] | [
"To my knowledge, you can't build a laser cavity to be simultaneously resonant at all the frequencies associated with \"white light\". Do you have a paper or citation describing the construction of the HeCd laser you're referencing?"
] |
[
"Why do my actions or others actions in my dreams/imagination favor doing things facing left rather than right?"
] | [
false
] | null | [
"We can't really comment on anecdotes / isolated incidents without resorting to speculation which we try to avoid."
] | [
"It’s every thought I have involving an action, not really isolated. Unless you mean isolated as in this is the first time you’ve heard of something like this"
] | [
"We can't answer questions about why something specific happens to you in particular."
] |
[
"AskScience AMA Series: I'm Dr. John Troyer, Director of the Centre for Death and Society at the University of Bath and I'm here to talk about death, dying, dead bodies, grief & bereavement, and the future of human mortality. Ask Me Anything!"
] | [
false
] | Hello Reddit, my name is Dr John Troyer and I am the Director of the at the University of Bath. I co-founded the website (@DeathRef), the (@FutureCemetery) and I'm a frequent commentator for the BBC on things death and dying. My upcoming book is Technologies of the Human Corpse (published by the MIT Press in 2020). I'l... | [
"I’m a librarian with no medical and minimal scientific training. My community is yearning for a chance to talk about Death, so I’ve been hosting monthly Death Cafes so that the adults in my area have a safe place to come talk about all topics death. As a medical professional, is there anything you think laypeople ... | [
"As someone who has devoted their professional life to the subject, how do you, personally, feel about your own aging and eventual death?"
] | [
"How do I most effectively donate my body to “science”? I don’t want to be in a body brokers warehouse waiting for a knee to get lopped off for a conference. That’s valid, but that has become a pretty shady business, right?"
] |
[
"The universe appears to still be expanding at an accelerated rate, but is it only because we are seeing the universe in a past state? (MIC)"
] | [
false
] | This seems like a simple explanation, but I'm wondering, if just maybe, that this mayhave been overlooked by scientists. To clarify my question in the title, I'm asking that since light takes time to travel, is it possible that not enough time has passed since the big bang to be able to observe the universe in it's cur... | [
"http://www.livescience.com/16367-nobel-physics-universe-expansion-accelerating.html",
"Bascially, they are expecting even the furthest objects to be closer than they are. They are already specifically looking for the furthest objects so they have included your concern.",
"THere is no known mechanism that would... | [
"I'm asking that since light takes time to travel, is it possible that not enough time has passed since the big bang to be able to observe the universe in it's current state - possibly in a state of deceleration?",
"No. It's not the age of the object emitting the light that is the question -- it's the light itse... | [
"Oh........",
"Thank you for taking the time to thoroughly disappoint me. I knew I most likely wasn't right but I had no idea how hilariously wrong I was. I guess if I knew there were different types of expansion I wouldn't even have asked. ",
"Is there any chance that something like redshift should be revisite... |
[
"If virtual particles are appearing and then annihilating themselves constantly where is the energy from the matter antimatter collision?"
] | [
false
] | null | [
"Virtual particles don't literally exist. There are no physical particles being created out of the vacuum and annihilating."
] | [
"OK but something is happening. There is a disturbance in space right? Like the Casmire effect is a real thing and people think that black holes will evaporate as a result of virtual particles right?"
] | [
"OK but something is happening. There is a disturbance in space right?",
"No, there is not dynamical process happening.",
"Like the Casmire effect is a real thing and people think that black holes will evaporate as a result of virtual particles right?",
"The Casimir effect and Hawking radiation are effects of... |
[
"I know that perpetual motion shouldn't exist, but super-fluid fountains?"
] | [
false
] | is an example of one. I do know understand where the energy is lost. | [
"Wikipedia",
" says:",
"If a capillary tube is placed into a bath of superfluid helium and then heated, even by shining a light on it, the superfluid helium will flow up through the tube and out the top as a result of the Clausius-Clapeyron relation.",
"So it's very likely that the energy required to do this ... | [
"The only truly closed system is the entire Universe."
] | [
"Ah, didn't see that. Hard to imagine that it gets enough heat to offset the energy given off though."
] |
[
"What's in old gold tooth fillings/crowns besides gold? Why aren't they pure?"
] | [
false
] | A relative gave me some old gold tooth fillings they had lying around and asked if I would be willing to melt them down and purify them at the assay lab I work at. When I got them it turned out to be three gold fillings, two crowns and a gold bridge. I wrapped the whole mess in lead foil and cupelled in a 1700F furnace... | [
"Gold by itself is pretty malleable. Alloying it with other metals can increase it's hardness, which would be valuable to keep the crown from deforming while chewing. Poking around, it actually looks like standard practice. Many metal fillings today are made by alloying some noble metal (Gold or Platinum which have... | [
"Adding to this is the old cliche of biting gold coins to see if they're real. If real, they dent. Thus why you wouldn't want pure gold filling or replacing things you use for biting.",
"A question I'd like to add onto this now is why use gold at all in the first place? Certainly there was a more common and more ... | [
"Pure gold is extremely brittle and has low tensile strength. Jewelry and fillings are usually made of a gold alloy to increase the strength and durability of the piece.",
"The other metals are probably silver, platinum, palladium, tin, and maybe copper."
] |
[
"Why do so many things follow Normal Distribution?"
] | [
false
] | Many things in nature and economics seem to follow a Normal/Gaussian distribution. Is there a reason for this? | [
"This is a good question so I would be interested to hear how other people answer.",
"As I understand it, one of the reasons it is so common is because of the central limit theorem, this tells us that any set of measurements of independent, identical distribution will converge to a normal distribution if you have... | [
"Yes, it is the Central Limit Theorem. Your explanation is almost correct. You do not need lots of independent measures of the distribution. The measure you are taking needs to be the sum (or mean) of a lot of independent factors.The variance of each factor needs to be under some sort of control (there are formal l... | [
"As ",
"u/Robo-Connery",
" mentioned, the primary answer is the central limit theorem. To expand on that a bit: When your result comes from a single random variable, it can have all sorts of probability distributions: a die has a flat distribution for any integer between 1 and 6, a single pixel on your camera h... |
[
"Can organ recipients donate organs?"
] | [
false
] | If a recipient chooses to become a donor, can the organs they received be reused when they die? Edit: If organs can be donated on, how long can it be donated. Is there a specific time after which the organ will fail? | [
"Usually they only redonate an organ if the first recipient died shortly after receiving it - I don't know exact specifics, but it would be a scenario in which the organ was transplanted in a last ditch effort to keep someone alive that failed, which I think is at most a few weeks. I looked at some papers real quic... | [
"sometimes diseases aren't OF an organ, but still affect that organ. so replacing won't help stop the disease, but will prolong life/health."
] | [
"I didn't know that new organs could become damaged from the disease, too. I would assume that the reason organs were replaced would be to stop the disease. Is this not always true?"
] |
[
"In the vacuum of space, would I be able to turn around?"
] | [
false
] | Say a human is in the vacuum of space and is somehow alive and all is good. They're stationary and just floating there. If that person is facing a certain direction, would they be able to move to face another direction? Like twist their body to face behind them? | [
"Yes. ",
"Check out this video of it being done"
] | [
"You should be able to swing your arm around, and the rest of your body will spin in the opposite direction, until you stop moving your arm. ",
"This is basically how satellites control pointing (attitude). They have momentum wheels that spin. Spin it in one direction and the rest of the satellite spins in the op... | [
"Aha! \"He can't change his angular momentum but he can change his body position\" is a lightbulb moment for me!"
] |
[
"How do drugs get into the brain?"
] | [
false
] | [deleted] | [
"Most drugs have structures that are incredibly similar to natural neurotransmitters! Not to get too into the organic chemistry but serotonin and LSD share the same indole rings. In essence, because of their similar structure, LSD can pretend to be serotonin and affect the same pathways and receptors. To get into t... | [
"this is a great answer. I would also just like to add that the way the drugs get into the receptors via the bloodstream which is why all routes of administration (the way to take the drug) can affect how long it takes for a drugs effects to kick in. Which is why snorting things like cocaine and smoking drugs like ... | [
"Good catch! After some research, I found that the exact mechanism isn’t quite known (or at least there are no publications). LSD and other illicit substances are especially hard to research as they require special permits. However, it’s hypothesized that LSD travels through the choroid plexus epithelium. ",
"htt... |
[
"Are there underwater waves?"
] | [
false
] | Sound waves take place through out their medium as compression waves, but the waves in the ocean, which seem to also be dealing with a physical medium are only readily visible at the top layer. Is there a manifestation of the same physical force that generates tidal waves, but under water? And if they exist, what dif... | [
"Sure, they are called ",
"internal waves",
", although that is a broad term and they have many other names and sub-categories as well. There is a section of that article that nicely discusses how they differ from normal waves. They can be somewhat hazardous too - for example, the sinking of the submarine USS T... | [
"Internal waves are a key component of mixing across the pycnocline as well, since they break when they interact with bottom topography (much like surface waves) and their energy is dissipated through the water column. The mixing rate often goes up substantially in the vicinity of seamounts, ridges, and other bathy... | [
"Yeah, everyone has their own (usually strong) opinions about it. I absolutely agree it's speculative, which is why I said 'attributed to' and not 'caused by'. It at least shouldn't be hard to imagine how a submarine operating at max depth could run into trouble if an internal wave dropped its depth further, which ... |
[
"If SARS-CoV (2002) and SARS-CoV-19 (aka COVID-19) are so similar (same family of virus, genetically similar, etc.), why did SARS infect around 8,000 while COVID-19 has already reached 1,000,000?"
] | [
false
] | So, they’re both from the same family, and are similar enough that early cases of COVID-19 were assumed to be SARS-CoV instead. Why, then, despite huge criticisms in the way China handled it, SARS-CoV was limited to around 8,000 cases while COVID-19 has reached 1 million cases and shows no sign of stopping? Is it the v... | [
"SARS-CoV-2 is worse than SARS-CoV because, paradoxically, it’s not as bad. SARS tended to have a faster disease onset and be more severe, so you had far fewer infectious people with mild or no symptoms walking around spreading the disease. In fact much of SARS spread was in hospitals, rather than on the street. T... | [
"This is also why Ebola isn't and can't really become a huge problem in an educated populous with access to health care.",
"By the time people with Ebola are infectious, they are vomiting, having diarrhoea, and bleeding. Not likely to be around people. You also have to come in contact with those body fluids in or... | [
"Angiotensin-converting enzyme 2 (ACE2) is the receptor that both SARS-CoV and SARS-CoV-2 bind to. The (S) spike glycoprotein that binds to ACE2 is slightly different in both viruses and this results in different binding affinities.",
"\"Recent studies have found that the modified S protein of SARS-CoV-2 has a si... |
[
"What happens at the microscopic level when you cook food?"
] | [
false
] | Would it be accurate to say that cooking breaks down complex chemicals in food so that our bodies can use it better? Like an external first stage of digestion, of sorts. | [
"cooking, in the general sense, is the application of heat to a mixture. basically what you're doing is increasing the rates of some reactions that begin when your different ingredients come into contact with each other and providing the activation energy necessary for other non-spontaneous reactions to begin. the ... | [
"Interesting. So cooking doesn't necessarily have the purpose of changing the molecular complexity of food so our bodies can better utilize its nutrients? I guess baking wouldn't make breads more simple, but what about roasting vegetables or browning meat? "
] | [
"Browning foods is the ",
"Maillard reaction",
" - it's very complex and all the reactions that occur is not elucidated yet.",
"It doesn't necessarily make it better to utilize nutrients."
] |
[
"What would gravity be like in an infinite space, which held effectively infinite matter?"
] | [
false
] | For context, discussion on my DnD group about the elemental planes and what the physical properties of those planes would actually be like, assuming they were plausible. The lore in-game says that these planes extend infinitely with the primary matter that consitute that plane (air, earth, water, etc). We debated wheth... | [
"One thing to point out is that \"infinity\" in physics is almost always shorthand for a particular limit towards infinity. Many physical paradoxes can be solved by reducing a problem to a finite version and then taking a limit, but the result will often depend on how exactly that limit is taken. It often occurs wh... | [
"This answer is exactly what we were looking for, thank you!"
] | [
"This is a good answer, but I disagree with the part where you say:",
"And as you have pointed out, the gravitational force on each such piece of matter is balanced out in all directions so as to create no net force.",
"This is implicitly invoking an additional assumption that most physicists assume isn't true ... |
[
"Would the \"naked body scanners\" be useful for veterinary medicine?"
] | [
false
] | One of my friends just lost one of their pets because a Vet visit missed a laceration that later became septic/abscessed. Would something like the "naked body scanners" the TSA likes so much be useful for vets? If it goes through clothes, would it not let them get a good view of the skin and any hidden wounds that may ... | [
"The airport scanners use mm-wave (sub-THz) radiation. This radiation is non-ionizing, so it is completely safe. Therefore, you don't have to worry about using lead shielding of any kind. When used for medical imaging, it is capable of differentiating tissue types from one another, rather than just bone-not bone. T... | [
"They already have \"better\" tech for actual soft tissue injuries like sonic imaging or even MRI.",
"I was thinking something like this would allow an easier external search for injuries.",
"Last time I had to take my cat to the vet for a bite the vet had a hard time finding the exact injury because his fur i... | [
"I very much doubt it. They were designed to be used en masse without much discrimination. Because of that they aren't very accurate, and are prone to incorrectly imaging the subject. Medical scanners capable of seeing soft tissue details need to be much more precise (higher radiation levels) and carefully operated... |
[
"How do electromagnetic antennas work?"
] | [
false
] | I understand how basic electric circuits work, but I don't understand when and how conductors would radiate energy via EM waves, versus simply radiating it away as heat (i.e. acting as an ohmic resistance). Does it have to do with the length of the conductors in the circuit? The frequency of the signal? Furthermore, w... | [
"The electrical signal passes through an oscillator, which produces a wavelength. The wavelength is passed onto a conductor (i.e. Coax cable, which carries the wavelength to the antenna. The antenna is tuned for the systems wavelength, and passes the signal onto the atmosphere. The reverse is true of the receiver. ... | [
"Imagine electromagnetic energy radiating from the base of an antenna as a wave. If the antenna is of a complementary length (relative to it's physical wave length) there is limited reflection from the tip of the antenna (the power of the wave doesn't reflect back into the base of the antenna). This causes positiv... | [
"I understand how basic electric circuits work, but I don't understand when and how conductors would radiate energy via EM waves, versus simply radiating it away as heat (i.e. acting as an ohmic resistance).",
"Think of the magnetic part of the Electromagnetic (EM). Magnetism does not need a conductor. So all tha... |
[
"Is there a specific range before we loose contact with the voyager?"
] | [
false
] | Also, is plasma the only thing we're reading off of it? How would that help us understand more about the universe? Sorry for any awful grammar. | [
"I'm not gonna do the math, but give you some useful terms to learn more about the effects involved. Both Voyager probes are similarly constructed and much of this is generic anyway, so it applies to more than just the Voyager I probe which has been in the news lately",
"Radio waves will keep traveling forever, b... | [
"It comes down to an information theory question. At some point, the craft will get far enough away that we can no longer practically demodulate the signal due to physical limitations in terrestrial radio hardware. In theory we could keep building larger and larger dish antennas, and then cryogenically cooled dish ... | [
"Yeap, both Voyager probes will hit the power limit long before we have to worry about distance and how to overcome it in terms of communication. As far as I know, by 2025, Voyager will be unable to power any of its scientific instruments. I certainly hope that it reaches the Oort cloud, although it would take the ... |
[
"Theoretically if there were 6 black holes making a cube shape that blocked off all entrances and you went into the empty space between the black holes (without getting sucked in) what would happen to space and time around you and outside of the theoretical black hole cube?"
] | [
false
] | For a better understanding of the question let's say it's a hollow sphere composed of black holes. This sphere is completely encapsulated and blocking off the outside universe. Otherwise great answers! I'm humbled for everyone who has taken interest and time to provide insight. | [
"If the black holes were close enough to block off all exits, they would have overlapping event horizons and immediately merge into one huge black hole, with you inside that black hole."
] | [
"So im a little late. All these answers here are not very satisfactory. You can in fact have a region of space that is blocked off from the rest of the universe due to a lattice of black holes surrounding the region. One of my friends phd thesis was on this exact topic. And heres one of the papers that describes th... | [
"How would the 2 singularities communicate to each other that their event horizons are touching? ",
"And why would the horizons touching cause the singularity itself to merge?",
"edit. The wiki seems to indicate the event horizon radically deforms into an X shape shared among the 2 black holes, but they continu... |
[
"What specific type of continuum is the concept of Space-Time?"
] | [
false
] | I know I'm out of my depth, but what label would be correct? For example, is it a homogeneous decomposable continuum? | [
"The word \"continuum\" classically refers to the set of real numbers (the real number line). If you pick any two real numbers ",
" and ",
", there is always a third number ",
" between ",
" and ",
". But there's more to it than that! (That property would also describe the rational numbers, which are not ... | [
"All of science is about using models to describe the natural world. So in the context of science, there is no difference between the statements \"spacetime is a manifold\" and \"spacetime is conventionally modeled as a manifold\". Perhaps in the context of philosophy we can ask whether our models imply anything ab... | [
"We don't know the \"true\" nature of the world. That is why we use mathematical models to study and understand it. Their value is defined only by whether they are useful, and this model of spacetime is VERY useful.",
"The \"true\" nature of the world is a subject for philosophy, not science."
] |
[
"How would you determine Chlorine ion concentrations instead of Hydrogen ions?"
] | [
false
] | I've only learned how to do H+ concentrations in class so far, and I was wondering how I would determine the ion concentration of a mixture (with known molar concentrations) with Chlorine ions instead of Hydrogen? Am I missing something simple? x.x | [
"Well, you didn't give much detail, but based on that, I'm assuming this is for a gen.chem course. And based on that, I'm assuming you're adding HCl to water. In that case, for every H+ ion you're adding to the water, you're also adding Cl-, so they'd be equal (since this is a strong acid and you'd have complete ... | [
"Start from the basics. What is concentration? It is mols of solute over liters of solution. The two mixtures you are given both contain chloride ion. You are given the volume of each, as well as the means to find the number of mols of chloride in each.",
"That should be vague enough to just point you in the ... | [
"Sorry, I didn't want to give the exact question because I want to learn how to do it and not have it done for me. It's actually from my sister's college chem class: \"what's the concentrations of chloride ions in a solution made by mixing 115.0 ml of 2.00 M barium chloride and 250.0 ml of .450 M sodium chloride.\"... |
[
"What exactly happens when a computer \"freezes\"?"
] | [
false
] | null | [
"Any one of a number of things could be happening, but they all come down to one particular general thing: The computer has become stuck in a state from which it cannot escape. I would say \"an infinite loop\" but sometimes \"a very, very long loop where nothing much changes\" also counts.",
"For example, somethi... | [
"This is a very good explanation.",
"Couple of extra points in my opinion/experience:",
"Another hardware example (rather common) - Hard disk defects (bad sectors, controller failures, etc). Say you have a defective external hard disk thanks to bad sectors (on the physical hard disk surface), which have affecte... | [
"It's the operating system kernel that will try to work around the issue in the first example. When a problem like that appears and the kernel can not fix it it will crash the computer on purpose to protect the data in the computer as it can no longer guarantee its correctness.",
"On Windows this will manifest it... |
[
"Can meat get cancer? Could it still be eaten? Would the meat taste different?"
] | [
false
] | I don't mean does meat cause cancer in humans I mean can say cow or pig meat get cancer and is that still edible with proper cooking | [
"Yes and yes, and maybe. Cancer can happen with any kind of cell. Skin cancer, bone cancer, organ cancer. You name it. Muscles can get cancer and animals aren't immune. There are many different types of cancer and the results are different. ",
"Eating meat that is cancerous shouldn't taste much different than nor... | [
"There is really no reason to.",
"We can stimulate healthy muscle cells to grow as well and people won't be lining up to eat cancerous meat."
] | [
"Follow up question, then since cancer meat is edible could we cultivate it and live off the cultivar? Similar to how some cancer cell lines get cultivated by biotech companies?"
] |
[
"Considering the importance of the moon to earth would it not be equally important to look for planets with moons to effect tidal conditions as it is to look for planets with water when searching for habitat planets?"
] | [
false
] | Edit: Habitable. Sorry | [
"We don't start by saying \"let's search for planets with water\", we find all the planets we can, and later we hope to be able to look at these planets in more detail and determine what their properties are.",
"There's also the question of how difficult it is to determine if a planet has water vs. if it has a mo... | [
"Maybe an astronomer [in training] can tell us how hard each of those is.",
"Happily!",
"Water - the way you'd detect this is through infrared absorption in the planet's atmosphere (or possibly emission). Whilst the main part of the planet blocks all light, its atmosphere will block only certain parts of it, de... | [
"I suppose we do find all of the planets we can but the tip of sword in the search tends to be \"is there water there?\" because that would seem to indicate the appropriate temperatures. But depending on where you think the origin of life was on earth, the tide of that water could be equally important and no one se... |
[
"Why do so many species have a rare chance of producing an albino “version”?"
] | [
false
] | What I meant was why is it so common that so many different species are able to produce a rare albino version. Like do they all share a specific gene that changes? | [
"Well, in a way yes. Albinism is caused by a malfunctioning gene that produces melanin, and since most species have melanin in their system, they do have the gene that codes for the synthesis of it. Since apart from pigmentation, this gene doesn't exactly affect anything else, it's one of the few \"bad\" mutations,... | [
"To add to this, we often use albinism in research when we want to test our ability to modify different parts of a genome as it's pretty easy to spot a success. Additionally, some of the most common lab strains of model organisms (BALB/c mice, Xenopus, etc) are albino, so it might appear like the incidence is highe... | [
"thank you! just what i was wondering."
] |
[
"Given current technology and information, what will ultimately be the death of our solar system?"
] | [
false
] | Bonus questions: How long would this method take? | [
"The Solar System will die when the Sun becomes a red giant star whose outer envelope reaches as far out as Venus, or perhaps even the Earth. Even if the envelope doesn't reach the Earth, the immense radiation given off by the Sun in this phase will eliminate all life on the planet. The Sun will then transition to ... | [
"Whoops! I forgot to answer your bonus question!",
"As far as we can tell, the age of the Sun is about 4.6 billion years. This is about half-way through its total \"main-sequence\" lifetime of about 10 billion years. After that, the Sun will enter the red giant phase and be a red giant star for about 2 billion ye... | [
"These cold white dwarves have a name - ",
"black dwarves",
". The universe isn't old enough for any to exist yet. "
] |
[
"How does water dissolve an ionic compound?"
] | [
false
] | Crash Course is saying that the ionic compounds polarity breaks apart hydrogen bonds in the water, which causes them somehow to dissolve the ionic compound? (The explanation given makes no sense). On most other websites I hear that waters polar bonds attracts ionic compound atoms towards it, breaking those bonds apart ... | [
"If you just have a glass of water, the water molecules are continuously hydrogen bonding with one another. (This is the reason why water has such a high specific heat - additional thermal energy is needed to break the hydrogen bonds.)",
"If you add salt (NaCl) to the water, then instead of hydrogen bonding with ... | [
"Random question: Why does salt water and actual salt taste the same? If salt water is simply Na+ and Cl- Ions, and salt is NaCl, why do they taste identical? Or is it that NaCl is ionized by your saliva as well?"
] | [
"Saltiness is a taste produced primarily by the presence of sodium ions. Other ions of the alkali metals group also taste salty, but the further from sodium, the less salty the sensation is. A sodium channel in the taste cell wall allows sodium cations to enter the cell. ",
"So, yes, it's the ionized Na+ ion that... |
[
"Blizzard in the NE (Nemo): Would anyone mind discussing its potential impact in a manner free of media sensationalism?"
] | [
false
] | I live in the NH and they are basically saying we are going to get hit very hard. The media is perpetuating this as well. What are the facts? | [
"The national weather service puts out official forecasts, on their ",
"site",
". You can drill down and you are looking for the forecast discussion like ",
"this one",
" for the ME/NH area.",
"They are generally hype free. With ",
"this",
" message about Katrina being the closest they get to weather ... | [
"Depending on where exactly you are in New Hampshire, you could easily see between one and two feet of snow. At the same time, it will be very windy during the height of the storm, so there will be a great deal of snow blowing around causing whiteout conditions, and making travel dangerous if not impossible. Depend... | [
"I know I'm late to the conversation, but essentially what happened was a combination of two storms. Low pressure systems mean bad weather to meteorologists. One low pressure system developed to the west, being fed by cold air coming down from Canada. This system strengthened as it passed over the Great Lakes ar... |
[
"Could You Blow a Small Speaker (e.g. an iPhone Speaker, Computer Speaker) By Covering It Up Air Tight while Playing It at Full Volume?"
] | [
false
] | I was out golfing with my friend the other day and I was playing some music on full volume on his iPhone 5 when we started to come close to the guys ahead of us. So to be courteous I plugged the speaker with my thumb to cut the music off and then I turned the volume down and took my thumb off. He then got all pissed at... | [
"I think he believes that the increase in air pressure generated by the speaker would be enough to rupture the membrane that makes the sound.",
"When in reality, the maximum change in air pressure associated with a sound wave is very small. A jack hammer at 1 m from the source, which is about 100 dB, has a pressu... | [
"there are really two ways to blow a speaker,",
"Undersized amplifiers or a amplifier being pushed too hard will produce \"clipping\" Clipping is when the AC waveform gets its peaks cut off (or clipped)and the amp starts producing DC voltage instead of a AC sine wave. you now have a prolonged burst of DC voltage ... | [
"i've heard a common reason speakers blow isn't because the speakers can't handle the amplifier's size, but because the amplifier is too small and thus you think it can be turned all the way up and it will clip, creating a large square wave that the speaker tries to replicate but can't. any truth to this?"
] |
[
"Could enough of something with a low pH dissolve anything?"
] | [
false
] | [deleted] | [
"Not really. Acids just don't eat stuff indiscriminately. It's always a specific reaction, and there's always something resisting that reaction. Think of it this way - even for the most aggressive substances we handle, we have vessels that can contain them. Pure acidity isn't that destructive in the first place. It... | [
"Not necessarily. pH doesn't tell the whole story when it comes to the reactivity of acids with other materials. There are many materials that simply don't react with acids at all."
] | [
"Probably not. From my understanding for something to dissolve it is dependent on wether it can form intermolecular forces with the other molecules surrounding it. So for example sugar, it is able to form intermolecular forces with surrounding water molecules which allows it to dissolve in water However, oils canno... |
[
"How did our universe become so organized?"
] | [
false
] | this question pertains to entropy in the early universe. as i understand it, entropy is the habit of particles to move from organized to disorganized. from order to chaos. we know that entropy always increases, and can never be reversed. knowing this, when our universe was young how did any form of organized structure ... | [
"Or gravity along with other natural functions of physics."
] | [
"A \"random and chaotic\" gas is only a maximal entropy state in the absence of gravity. If you include gravity, then you'd have to include that in the measure of entropy. I saw a talk by Roger Penrose in which he suggested that black holes are the maximal entropy state of a given volume of space and thus tell us t... | [
"The error in your question is that you're taking entropy to mean \"disorder\" which is not entirely correct. If that's all it was, then you'd say \"of course a planet, a solid spherical object, has more order than a big cloud of gas, so it must have less entropy\". But entropy is better described as an inverse m... |
[
"Are there any domesticated species whose wild precursor still remains a mystery?"
] | [
false
] | I’ve read about how many of our domesticated crops can be traced back to the wild plant they were most likely first bred from. Are there any that scientists have been unable to identify thus far? Perhaps because the precursor is now extinct or lost or been overtaken in all its habitats by the domesticated breeds? I ima... | [
"Can you elaborate on citrus fruits? I was under the impression that we know all our cultivars are variously descended from pomelo, citron, mandarins (not the kind in stores), and papedas."
] | [
"It is also unclear which of the wild tomatoes the domesticated variety is descended from. And the answer maybe be most of them as wild and domesticated tomatoes readily hybridise"
] | [
"Just looked this up, you're correct and the information I was working from was just very out of date. "
] |
[
"What did our evolutionary ancestors do for hygiene, such as showers, brushing teeth, and cutting hair and nails?"
] | [
false
] | null | [
"Look to our evolutionary closest relatives, like chimps and orangutans.\nA huge difference between humans and our evolutionary ancestors is the food we eat, particularly cooked food and sugars. Our ancestors didn't eat that stuff, and therefore didn't have the same issues with oral hygiene.\nBathing? Live near wat... | [
"Our ancestors didn't eat that stuff, and therefore didn't have the same issues with oral hygiene.",
"Been watching a lot of old episodes of \"Time Team\" (the old British archeology show) and it is interesting to see that some of those old skeletons really did have very nice teeth. ",
"One of the comments made... | [
"I'm surprised that nobody has mentioned scraping!",
"Okay, we think of the ancient Greeks as being beauty-conscious and pretty clean, right? Well, when they weren't bathing in water they would ",
" themselves clean, using a tool called a strigil. It's basically a knife. They kinda kept themselves oiled up most... |
[
"Does gender matter in organ transplants?"
] | [
false
] | Say someone gets a liver transplant, and that person is a woman. Are the chances of her body rejecting the organ higher if the donor was male rather than a female? | [
"Gender has little to nothing to do with organ transplants, far more important is the similarity of the donor immune system antigens to the patients. It's important that the patient has as little a response to the donor organ as possible. This is determined by HLA type matching, this is a genetic test that essentia... | [
"When talking about bone marrow transplants, yes.",
"Chances of a GvH (graft versus host) reaction are higher if the bone marrow donor is female and has been pregnant a sufficient number of times. In the instances where we can choose, we pick a male over a female donor.",
"The reason this happens is because we ... | [
"Women who have been repeatedly pregnant have been exposed to more different HLA antigens, when compared to a transplant/transfusion naive man. It happens that HLA class I is the main determinant of cellular rejection (which is becoming rare thanks to modern immunosuppressive regimes). Therefore, multiparous women ... |
[
"Is there the same amount of water on Earth today as there was when the Earth was created?"
] | [
false
] | [deleted] | [
"Far, far more important than water molecules leaving the planet, or addition of water through asteroids and comets, is that water is incorporated into the rocks of oceanic crust in massive volumes over time (metasomatism). This is why you get volcanic arcs above subduction zones, which account for a very sizable p... | [
"More or less, water molecules can leave and arrive earth through the atmosphere, humans can do various chemical reactions turn some other material into water or visa versa, but overall the level has remained pretty constant.",
"Should also be noted when the earth was created it was a big ball of molten rock, so ... | [
"Your professor is right. Due to ocean currents, upwelling in the ocean brings water up from the depths. This water, now on the surface, begins to play its part in evapotranspiration, which travels into the air, rises, condenses on cloud condensation nuclei (CCN) to form clouds, then travels to land where those clo... |
[
"We hold our eyes closed, or hold our eyes open?"
] | [
false
] | How do we know? | [
"The orbicularis oculi muscles contract to close the lids. The palpebral portion acts on its own when you are closing your eyes to sleep. The muscles that contract to open the eyes are the levator and meuller's muscle along with relaxation of the orbicularis. So opening and closing of the eyes require both relax... | [
"Not possible to relax both sets at the same time because of the anatomy, one set flexes as the other relaxes. Similar to when you flex the biceps brachii to bend your arm at the elbow, the triceps brachii relax and vice versa. "
] | [
"Not 100% sure, I've seen open, closed, and in between upon death, but I believe the mechanism of death and other present pathological processes (increased intracranial pressure, neuropathies) play a role in which set of muscles loses the most tone and therefore will dictate what your eyes will do. ",
"Side note:... |
[
"Weapons-grade uranium vs weapons-grade plutonium: what's the difference?"
] | [
false
] | What's the difference between WG Uranium and WG Plutonium? For example: how many kilograms per kiloton are needed? Availability? Warhead size difference? Which might be better suited for a "suitcase nuke"? Etc. (I'm going to use this for a story, for you curious folks.) | [
"Well first off, one is uranium and one is plutonium, they are different elements. WG uranium is typically called highly enriched uranium (HEU). Technically anything above around 20% U-235 is highly enriched and theoretically can make a fission weapon. In reality, when talking about weapons grade uranium it will... | [
"I'm curious about this advanced gun type, what exactly differentiates it from the original gun type? "
] | [
"Modern advances. You need to fire the two halves of the pit very quickly and accurately. Modern machining is needed along with modern explosives to get the required velocity."
] |
[
"In special relativity, what causes length contraction?"
] | [
false
] | As I understand it, everything in the universe is constantly moving through spacetime at . Objects that are stationary in space (relative to the observer) are moving at full speed through time, and objects moving through space must necessarily move slower through time to maintain constant velocity in spacetime, hence t... | [
"This animation might help",
"."
] | [
"To maintain the balance that time dilation offsets. ",
"The muon decay experiment is the best way to understand how they go hand in hand. Muons have lifetime of a certain amount. Without SR they wouldn't reach or very few would reach earth from the sun. ",
"However people measured a lot of muons reaching earth... | [
"http://en.wikipedia.org/wiki/Lorentz_contraction",
"Everything you need to know to answer your question is right here",
"EDIT: After I posted this, I wanted to show you this: ",
"http://en.wikipedia.org/wiki/Ladder_paradox",
", which is really cool if you have never seen it."
] |
[
"Why is it so important to stay awake after sustaining a critical injury?"
] | [
false
] | I actually joined reddit a couple months back to ask this very question. User docmedic replied that "it greatly increases your chance of going into a coma, if not dying." Why? I am aware that the body's processes slow down during sleep, so wouldn't going to sleep help a seriously injured person by acting as a "hibernat... | [
"I'm a former EMT-B with wilderness medical and disaster response training. My last refresher course was about 3.5 years ago, and all of my certifications expired last June. This is a rather long response to the question, but I hope it's interesting.",
"Once upon a time, doctors noticed that head injury patients... | [
"As a neurological intensive care nurse, I can tell you that we keep patients awake primarily to monitor neurological status. That is in the neuro ICU though. In other ICUs, they monitor your stability with frequent vital signs (as do we) but also by periodic checks on your level of consciousness, which is direct... | [
"English isn't my first language so I had to google noogie. I can now confirm that a sternum noogie does indeed hurt. Even when giving it to yourself.",
"Really informative answer, and I especially appreciated the explanation of how this belief came to be."
] |
[
"How did we acquire the knowledge / understanding of the \"structure\" of atoms or the behaviour of sub-atomic particles that we currently have?"
] | [
false
] | [deleted] | [
"Most observations are a form of \"bouncing stuff off crap and seeing how it bounces back.\" Even when you're looking at the world around you, you're bouncing visible-energy photons off of things and how those photons come back into your eyes lets you \"see\" the world around you.",
"Well for atomic and subatomic... | [
"One should also mention the quite cool story about the Zeeman effect, after the discovery of which Lorentz was able to establish a formula for the the ratio of the mass of the hydrogen nucleus (proton as we know now) to electron mass, which was subsequently measured by Zeeman, all within one month!",
"This is de... | [
"And how did you know that an atom contains electrons in the first place?",
"So this is a very interesting historical episode.",
"J.J. Thomson gets the credit for \"discovering the electron\" but it's more complex than that. Thomson was using a common physics tool of his day, the cathode ray tube, to create lit... |
[
"Does the location of a pipe outlet in a full dam affect the water pressure in the pipe?"
] | [
false
] | We have a small dam which is used to feed a pipe running down the section to provide water for gardening and other uses. Intuitively, I feel that putting the outlet to this pipe at the bottom of the dam (i.e. as far underwater as possible) would create the highest amount of pressure due to the added weight of the water... | [
"The amount of waterflow is dictated by the pressure difference between inlet at outlet",
"By placing the outlet at the bottom, you add more weight to the water column in the pipe. However, the water coloumn of water over the outlet also adds pressure, so the pressure difference is the same whether you choose an ... | [
"The pressure at the garden will remain the same with the pipe at the bottom or top of the dam. (the height of the water above the pipe does not change either way). Placing the pipe near the surface will just limit how much water is available."
] | [
"https://en.m.wikipedia.org/wiki/Hydraulic_head"
] |
[
"How is the mass of a gas measured?"
] | [
false
] | [deleted] | [
"What do you know about this gas? There are constants used to figure this out, but we need more information. If it's lighter than air, you're really measuring how much lighter it is rather than how much heavier it is. Follow?"
] | [
"The balloon experiment would work fine for a gas lighter than air since you (presumably) know the volume of the balloon and you can work backwards from the buoyant force (force pushing up) to find the mass. Alternatively if you know what gas you're dealing with you can just use pressure temperature and volume to ... | [
"The \"air in a balloon\" experiment is only accurate if the gas has equal or greater density than the surrounding air.",
"Measuring the mass of a gas lighter than air is actually pretty simple. Basically, we have a number called the Gas Constant R (you can check it out ",
"here",
") that creates a relationsh... |
[
"Why don't human \"polar bears\", who dive and swim in ice water, get hyperthermia?"
] | [
false
] | I saw this youtube on the reddits of and sent it to my father, who is a Red Cross instructor. He asked how this man does not get hypothermia, especially if a person is wet and standing outside with no clothes in the cold, and than dives back into ice water. I don't have an answer for him. Is there some special regional... | [
"probably you mean hypothermia, as in a low body temperature. Hyperthermia would be overheating.",
"That video was less than two minutes long, meaning this guy did not spend a long time under water or wet. Hypothermia isn't an immediate thing. You are talking about cooling down the core body temperature a larg... | [
"Additionally, the ",
"mammalian diving reflex",
" basically transforms your body as you hit the water -- our heartbeat slows, capillaries restrict, etc. It's good for letting mammals stay underwater (and in deep pressure), but would also assist in not freezing to death as well."
] | [
"Wow TIL.",
"However, wouldn't a reduced amount of blood flow be disadvantageous in cold weather? From what I understand, warm blood flow is a good thing."
] |
[
"What happens, phisically, to all the alpha/beta particles and neutrons that are stopped by a radiation shield?"
] | [
false
] | null | [
"These are all probabilistic, so not every event will happen in the same way. So I'll just describe the ",
" for each.",
"Alpha particles undergo many small-angle scatters off of ",
" atomic electrons, eventually slowing down, grabbing onto two electrons, and simply becoming a neutral helium atom. Alternative... | [
"Yes, the buildup of hydrogen and helium gas inside materials can cause all kinds of undesired changes to its material properties.",
"It’s an issue for things like structural steels used for reactor vessels, which are subjected to huge fluences of neutrons over their lifetime. (n,p) and (n,α) reactions are consta... | [
"An alpha particle is two protons and two neutrons, thus it's a helium nucleus."
] |
[
"Is it possible to insert a drug into a virus and have it spread like influenza?"
] | [
false
] | Would people get the accompanying symptoms of the drug as well? Does the type of drug make a difference? If so, on what level? | [
"Yes. Viral vectors are used all the time in research. Basically what happens is that you cut away the \"bad\" part of the virus' DNA and then recombinantly add in whatever gene you want, without altering the virus' structural and replicative genes. By using different genes, or by inserting different DNA into your ... | [
"Yes. Viral vectors are used all the time in research. Basically what happens is that you cut away the \"bad\" part of the virus' DNA and then recombinantly add in whatever gene you want, without altering the virus' structural and replicative genes. By using different genes, or by inserting different DNA into your ... | [
"Thanks for the response and moderation, much appreciated. Regarding the side effects though, I know that many drugs come with some ridiculous ones, would they be retained as well? Would things like fatigue, nausea, blurred vision and other such effects be present?"
] |
[
"When doctors are drawing blood, is there an advantage or purpose to drawing from a vein instead of an artery?"
] | [
false
] | [deleted] | [
"1) You'd generally have to dig deeper into the skin to find an artery. Veins are very close to the surface of the skin, while arteries are more buried.",
"2) Blood in arteries has higher pressure, which makes messing with arteries much more dangerous to your health (higher risk of excessive blood loss)."
] | [
"The major reason is that veins are usually closer to the surface than arteries and thus more accessible. Arterial draws are only used for obtaining arterial blood gas (ABG) measurements and for certain medication infusions. ",
"Edit: Forgot a word"
] | [
"(Surface) Veins are also far larger than arteries, so they are a lot harder to hit."
] |
[
"Can't see the LCD screen of my synthesizer on stage with polarized sun glasses."
] | [
false
] | The screen of my synth is a one color screen ( ). I just bought these expensive RayBans that I'd like to wear while performing. The only way to describe what it looks like when I look at the screen is that it looks "cross-hatched"...almost like all of the pixels on the screen are turned on (not black). If I put a piece... | [
"Any additional filter will only block more light.",
"This is wrong. If you insert a 45 degree polarizer between two orthogonal polarizers, more light will pass through the system. It makes for a ",
"great optics demo",
" and it's actually strongly related to how our friend's LCD display works. "
] | [
"This is an awesome real-life problem involving polarization. If I ever teach, I'll be sure to use it.",
"So, LCD screens work by altering the polarization of incoming light and reflecting it back out. When it's reflected back out, the light is horizontally polarized. I know this because sunglasses are vertically... | [
"The same place you get anything these days",
"."
] |
[
"How can astronomers tell what a planet is made of when they are many light years away?"
] | [
false
] | I was looking at various pictures such as and and had two questions. How can scientists tell what a planet is made out of when they are millions of miles away? Also, how are scientists even able to see the planet? I understand telescopes are powerful enough, however in the vastness of space, don't other things get in t... | [
"I remember learning about the atomic signature from cosmos, the tv series, how the spectrum of an object can be used to determine what elements it is made of.\nThe spectrum is the array of colors (the rainbow) that is presented when the light passes through a prism, when magnified, the spectrum includes dark lines... | [
"They are extrapolating from the fact that that 55 Cancri is a carbon-rich star system. (Ours has relatively more oxygen and silicon.) If the planet is mainly carbon, then, based on the measured density and temperature, they speculate that it is largely diamond. This is a bit more speculation than I'm comfortabl... | [
"Spectroscopy. If you can observe the absorption spectra of a planet or star, you can tell what makes up the planet."
] |
[
"Are there any animals that have showed signs of being ticklish?"
] | [
false
] | Or are humans the only species that are ticklish? | [
"Rats, apparently : ",
"http://neuroskeptic.blogspot.com/2009/08/tickling-rats-for-science.html?m=1"
] | [
"Dog paws are ticklish! "
] | [
"Seriously? Cats."
] |
[
"Do gravitational waves weaken over distance?"
] | [
false
] | And, in case they do, what are they interacting with that weakens them? | [
"Far away from the source they weaken with an inverse distance square law for their power and an inverse distance law for their amplitude, just like all other waves - as the wave spreads out over a larger volume the intensity goes down.",
"There is a non-zero interaction with matter that can reduce their intensit... | [
"Basically, gravity waves can induce tidal forces in matter. This can heat up the matter, transferring energy from the gravity wave, and into the matter."
] | [
">There is a non-zero interaction with matter that can reduce their intensity",
"What form does that post-interaction energy take? "
] |
[
"Why does it matter when I eat my meals?"
] | [
false
] | It is common knowledge that you should eat larger meals earlier in the day and smaller, healthier meals later in the evening. says "Your metabolism slows down towards the end of the evening and is less efficient at digesting foods." My question is why does it matter when I eat my meals if I consume 2000 calories per da... | [
"It may be common knowledge where you're from, but I know at home in Paraguay (and I'm pretty sure most of Latin America) people have pretty large meals late at night. Meal times vary from culture to culture, at home I can distinguish five meals a day that the average person has (at least in the city):",
"From my... | [
"In terms of thermodynamics, sure it doesn't matter. But the process is not that simple. The machinery has quirks. My understanding is that the recommendation of a large meal in the morning is due chiefly to the fact that you haven't eaten all night. Consider: When you eat at noon for lunch, and your last meal of t... | [
"Funny, I've noticed the exact opposite; if I eat a big breakfast, I've just consumed a large amount of calories, meaning i have less to \"spend\" for the rest of the day. This might be OK if it was offset by not wanting to eat from that point on, but I don't notice any particular appetite suppression that lasts m... |
[
"Why is the range of the strong and weak nuclear interaction so small compared to the infinite ranges of the other two interactions?"
] | [
false
] | I've tried researching it a bit on my own, and it seems like it has something to do with the mass of the force carrying bosons, i just dont really understand how. | [
"The weak force has a range on the order of 10",
" meters, because the W and Z bosons have very large masses (around 90 MeV/c",
").",
"The strong force is different, because the gluons are massless. But it still ends up having a short range in practice, because of confinement. The energy that it would take to... | [
"The potential energy of interaction which is mediated by a particle of mass m is generally proportional to a function of the form exp[-mr]/r, in units where c and ",
" are 1.",
"For a massless particle, you get a 1/r potential energy, like gravity and electrostatic interactions. But if m is not zero, then you ... | [
"Thanks for replying! I was however also wondering why the large masses of the W and Z bosons make the range of the weak force so tiny?"
] |
[
"Why do I get itchy when I take my preworkout drink?"
] | [
false
] | [deleted] | [
"do any of them have a high amount of niacin in them? old trick I learned long ago was to buy niacin from a health store a take a couple any time I wanted to appear \"sick\"... they make your skin feel itchy and look splotchy for a short while after taking them. perfect for getting out of school or church or what... | [
"It's called ",
"paresthesia",
". The beta alanine found in many workout drinks can cause it, as can high doses niacin."
] | [
"Possibly Beta Alanine. Also, have you considered asking ",
"/r/Fitness",
"?"
] |
[
"Do people who look young for their age live longer?"
] | [
false
] | null | [
"Here's a news article discussing this: ",
"http://news.bbc.co.uk/2/hi/health/8411329.stm",
"Essentially, it appears that yes, younger appearing people do live longer, could be due to their telomeres (a part of your genes) replenishing better, or it could be that older looking people have lived a hard life. K... | [
"An article I cited below essentially had a \"Guess the age\" contest with twins, and some would look younger than others, as judged by a jury of your peers, so to speak..."
] | [
"I'm 35 and get asked what school (college) I go to all the time. Honestly the most awkward element is dating. Women my own age look so much older than me on the flip side women that look closer to me in age are so much younger I have a hard time relating to them. Full disclosure I have had some cosmetic surgery... |
[
"Could an HIV+ person receive organ donations without risk of rejection?"
] | [
false
] | My understanding is that organ rejection occurs when the body's immune system attacks the new organ thinking it's an invader. But people with HIV that has progressed enough don't have much of an immune system. So could you give an HIV+ person a new kidney or liver without having to worry about rejection? This is hypoth... | [
"While there may be less of a chance of having an immune response, that doesn't mean there won't be one. Doubt you are going to find many people with no immune system left and even if you did, they would probably not live very long with one that doesn't work at all."
] | [
"My guess is that there would be a much greater risk of infection due to the procedure than rejection of the organ itself. "
] | [
"There is still an immune response with T-cell counts >200, anything below that and you are diagnosed with AIDS. It is highly unlikely that someone would receiving an organ transplant with a T-cell count <200, the risks of surgery would be immense and the first priority would probably be stabilizing the immune syst... |
[
"Are venomous and poisonous animals immune to their own venom or poison?"
] | [
false
] | Like if a rattlesnake was injected with rattlesnake venom, would it undergo the same effects on it as it does to other creatures. | [
"Cobra envenomates itself, develops abcess",
" (Contains mild pictures of the snake's wounds)"
] | [
"Interesting, Thank you"
] | [
"I have seen rattlesnakes envenomate themselves by accident, and die hours later."
] |
[
"What defines the edge of the observable universe?"
] | [
false
] | Why is some of the universe observable and the rest not? | [
"Because the Big Bang happened a finite time ago and light has a finite speed. That means that a lot of faraway objects just haven't had time to send light to us.",
"The Universe is roughly 13.7 billion years old. That doesn't mean, however, that the observable Universe is 13.7 billion light years across. That wo... | [
"13.7 billion light years in radius. Sorry if I was unclear on that. Does that answer your question?"
] | [
"It wouldn't, it would have radius 13.7 billion light years. I think this was just a typo."
] |
[
"If the Sun instantaneously disappeared, we would have 8 minutes of light on earth, speed of light, but would we have 8 minutes of the Sun's gravity?"
] | [
false
] | null | [
"Some previous threads about this:",
"1",
"2",
"3"
] | [
"Yes."
] | [
"And if you don't mind, to short circuit any of the debates that often follow, I'd like to clarify what I think you mean by this for others:",
"Gravity is the effect of matter traveling through a curved space. But in order to know how that space curves, we need to know the distribution of mass, energy, momentum, ... |
[
"What would the shadow of a black hole look like; a perfect sphere, blobby, or something different?"
] | [
false
] | null | [
"A non-rotating black hole with nothing around it appears as black disk, with some light distortion around that disk. For a rotating black holes (in practice they are all rotating) it gets more complicated, ",
"here is a simulation",
". If there is material near the black hole then things get even more complica... | [
"Again, my apologies.",
"I understood your answer to describe what a ",
", as opposed to what a ",
"."
] | [
"Right. And the moon doesn’t emit any light itself, yet casts a shadow onto the Earth during an eclipse. (Yes, I know it reflects light, this isn’t a perfect example)",
"So dude is asking, what the shadow of a black hole would look like, say, if the moon passed in front of the sun, and the moon were a black hol... |
[
"Is the Irish Blood Transfusion Service lifetime ban on blood donations from gay men scientifically justified?"
] | [
false
] | This debate is going on in re the IBTS donation ban for any man who has had sex with a man. The guidelines have a 12 month ban for men who have sex with prostitutes etc vs lifetime ban (see page 12) --You must NOT give blood for at least 12 months after you last had: • Sex with anyone who has: - HIV - Hepatitis B - He... | [
"While this question is a \"hot button\" issue in the realm of politics, this, like all questions in ",
"/r/askscience",
", must be answered by expertise or sources. Political opinions are not acceptable answers. "
] | [
"Quotations from the Canadian Medical Assn Journal (Wainberg et al., 2010: vol. 182 no. 12, pp 1321-1324):",
"\"With the development of more sensitive tests for detecting HIV, the potential occurrence of a false-negative result is now remote, since the system no longer relies exclusively on the enzyme-linked immu... | [
"I can't speak to the validity, but it's not limited to the IBTS; ",
"the American Red Cross has a similar restriction",
". ",
"The section it's under in both places implies that it's due to HIV transmission risk. "
] |
[
"When I look at a word, why do I automatically read it?"
] | [
false
] | When I look at a word, I automatically read it. Why is it that I cannot not read a word if I look at it? | [
"Going a step further, I occasionally read words without knowing where they are. It happens most often when walking down a grocery store aisle, surrounded by words and packaging in my periphery. A word will pop in my head that I know I've \"read\" but it takes a couple of minutes of looking to actually find the wor... | [
"Happens to me too then I spend the next 30 seconds looking for the word. "
] | [
"Does this apply to other objects? If I see an apple, I find it difficult to not see it as one."
] |
[
"Is there a chemical that produces heat when compressed?"
] | [
false
] | I don't mean those ones that they use in hot'n'colds, I mean one that just releases extra excess heat when put under pressure, but not extreme pressure? More like 100 ish lbs | [
"Ever use a pump to inflate a tyre? I've given myself small burns by underestimating how much heat was released by gas compression. When you release the pressure, the gas cools, like when using a spray can - it can also get very cold.",
"Different gasses will change temperatures at different rates when pressurise... | [
"Is this correct? My understanding is that when a gas exapands it draws in energy from the surroundings. Which is why its previous vessel cools down like how you mentioned the can getting cool, but the gas itself gained energy. Meanwhile, a gas compressor is used in AC units to force the gas flowing through the lin... | [
"Anything with a negative jt coefficient will get colder when compressed, eg nitrogen and hydrogen over their relevant temperature ranges.",
"http://en.wikipedia.org/wiki/Joule-Thomson_coefficient"
] |
[
"How do we get Vitamin D from the sun? Is it like photosynthesis in any way?"
] | [
false
] | null | [
"Photosynthesis is a process where photon is captured and its energy transported across a chain of molecules for the purpose of storing the said energy. This process is well-controlled at various steps, and organisms have evolved over the years to use the best spectrum of light available.",
"In humans the majorit... | [
"Yes, lack of sunlight and a source of vitamin D will certainly make you deficient. Rickets comes to mind as a result",
"To answer your original question, sunlight absorbed by the epidermis, vitamin D precursors produced and absorbed in blood stream eventually make their way to Liver, and on to your Kidneys wher... | [
"Just to stress Calcium's importance a little more: it's essential to the coagulation cascade and proper clotting when you bleed."
] |
[
"Why does the shadow of a bottle of water show up as a \"dark\" shadow even though water is clear, and the bottle is clear."
] | [
false
] | Context: I was holding a bottle of water and looked down at the shadow of it and it was showing up as a "shadow" and not like I expected. The shimmer was showing up on the ground, but the shadow was basically like if I had motor oil in the bottle. Weird question, but it doesn't make sense to me. | [
"A bottle of water is basically a sort of misshapen lens. If you take a proper lens and try the same thing, you'll see it casts a shadow except where it's focusing light. The light that would shine where the shadow is has been diverted to the bright spot. The effect is just less obvious for the bottle, because i... | [
"This is correct; the vast majority of the light is in fact making its way through the bottle without being absorbed, but it comes out going in lots of different directions.",
"As an experiment, take a pair of regular glasses (preferably low power, like reading glasses). Unlike a bottle of water, glasses deflect ... | [
"I didn't notice that before, but after your reply I see what you mean. That's pretty cool. "
] |
[
"With ionic radius, I know how to compare an ion to the neutral atom and how to compare isoelectric ions but how do you compare ions of different elements that are not isoelectric?"
] | [
false
] | null | [
"I saw a YouTube video comparing ",
"I- Br- Ga3+ In+",
"What rules did they follow to order them smallest to largest?"
] | [
"Hi AtenderhistoryinrusT thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one o... | [
"‘Chemistry’"
] |
[
"If a photon's frequency determines its color, how does combining colors work?"
] | [
false
] | My understanding of light is that the frequency determines color. But if you shine a green light and a red light at a (white) wall, it appears to us as yellow. Are both green and red photons being reflected and processed by our eye somehow? Or, maybe if both green and red photons hit the electrons in the wall, then ... | [
"Your eye has different ",
"cones",
" for different colors, so the actual 'merging' is done in your brain. ('color' is ultimately defined perceptually, since what we call a 'color' doesn't always correspond to specific wavelengths, as you seem aware)",
"Two-photon absorption (and emission) does exist. But it'... | [
"Oh, I know this one =) There are some wavelengths (like for example some specific shade of yellow) that are indistinguishable from some combination of wavelengths (like, some specific combination of green and red wavelengths). They would be different light beams in the sense you could distinguish them with instrum... | [
"As some of the other comments have pointed out, color is a psychological phenomenon, not a physical property of light. So whenever you're talking about how color perception works, if you're going to do it properly, you need to be careful not to talk about colored photons or colored light waves. Light doesn't have ... |
[
"Why does gravity affect matter and light so differently?"
] | [
false
] | So gravity is not really a force. It is actually the bending of space around one mass, and another mass continuing to go in a straight-bent line-curve in this warped space. If you look at a black hole, all the stars behind it seem clumped together because the black hole bends the space around it, and at the event horiz... | [
"They get affected the same way. A proton passing by a black hole wouldn't get sucked in if it was passing by quickly enough. The only thing affecting the deflection is that light is travelling faster than those objects. "
] | [
"But if a proton passes a black hole, it doesn't just get deflected a little, it gets sucked in.",
"No, generally not. Black holes are tiny things and they are not cosmic vacuum cleaners. Only protons (and photons) that are directed exactly at the hole will be absorbed. All others will have their trajectories def... | [
"Light that is headed into the black hole will get absorbed just like a proton headed into the black hole will.",
"It is only photons and protons that are headed PAST a blackhole that get deflected."
] |
[
"How do genetic engineers fine tune gene expression?"
] | [
false
] | Hey , could you help me understand some about genetic engineering? I think I understand the basic processes of inserting genes into organism and getting them to produce new proteins and the like from the new code, but from what I've read that's really only the beginning. As I understand it, the modified organism is pro... | [
"your title ask for fine tuning but your question asks for maximising protein production so for briefness I'll focus on that.",
"Gene expression is dynamic; however, there are a number of \"housekeeping genes\" which are constitutively expressed - ie. expressed in all/most circumstances. The promoter of a houseke... | [
"This is the correct answer.",
"\n Can just add in that it is possible to knockdown expression of genes being expressed using systems such as siRNAs."
] | [
"transcription factors, promoter sequences, can use some gene silencing techniques to downregulate any conflicting proteins "
] |
[
"How can particles collide, if they do not have a definite position when unobserved ?"
] | [
false
] | I thought particles are more like probability fields, how can they collide at a definite position then ? | [
"Yes, in quantum mechanics you only have probabilities of saying where a particle is, although that's not to say it's equally likely to be everywhere/anywhere.",
"The term 'scattering' is what's usually used rather than 'collision'. Because it's not like hard spheres colliding; elementary particles have no volume... | [
"(by which I mean, have a probability of having been in the exact same spot at the exact same time)",
"I barely know a thing of Quantum Mechanics, but isn't that the exact opposite of what Pauli's exclusion principle states, in the case of two fermions scattering?"
] | [
"In the strict sense yes they can't exist in the exact same eigenstate but they can still overlap very heavily."
] |
[
"Why can the gravity of black holes extend outside of their event horizon?"
] | [
false
] | Well, if nothing can escape a black hole, how come gravity can? Yes, I understand that mass bends space, and what we sense is the curvature of space created by a black hole. However, that curvature travels at the speed of light, not faster, right? So how can it exit the black hole then? | [
"Gravity isn't \"escaping\" a black hole; the spacetime produced by a black hole has a certain curvature, and the effects you're talking about, such as the formation of an event horizon, are effects of that curvature. So it's a bit silly to talk about those effects without there being any curvature. Gravity doesn't... | [
"Ok, so changes in gravity, not the gravity itself propagates at the speed of light. That's fine, but it doesn't explain the problem. Because what if someone were to create a micro black hole, that just pops into existence? The change in gravity would have to propagate outwards, but at the same time it can't move f... | [
"To use an analogy, picture a marble gently placed upon a sheet of tissue paper. While it does not sink instantly, shortly thereafter it will indeed sink, causing the tissue paper nearby to be drawn down, sloping towards the weight. if you roll another marble along the tissue, the curve will affect its motion. S... |
[
"What exactly is the Navier-Stokes millennium problem trying to solve?"
] | [
false
] | I just took fluid mechanics 2 and I saw that there was a millennium problem regarding the Navier-Stokes eqn. Can someone elaborate on what it involves? | [
"It's a physics problem. Kinda. When you combine a bunch of known physical laws, typically expressed as differential equations, and apply them to fluid flow, you get the Navier-Stokes Equations. A solution to the Navier-Stokes Equations then represent a possible way that fluid can flow. These equations are applied ... | [
"Just wanted to say what an excellent response."
] | [
"With CFD you're still chopping the flow domain into very fine discrete chunks and solving for them, and even the highest resolution CFD methods (direct numerical simulation) the length scale of these chunks is appropriate for modelling the smallest length scales of turbulence but still far larger than the atomic s... |
[
"Could i survive without drinking?"
] | [
false
] | I know what you're thinking. You're thinking 'No, dumbass'. But aren't some foods so rich in water that you could eat them as a substitute? Here's a thought experiment: Imagine I'm escaping, on the run in a foreign land. There's nothing to drink, but cucumbers growing everywhere, cucumbers as far as the eye can see, an... | [
"It would work.",
"Here's a big ol' database containing nutrient values, including water per serving: ",
"http://ndb.nal.usda.gov/",
"Don't see apples on there, unfortunately, but oranges have about 88gm of water per 47 calories, so if you ate only oranges and ate a 2000 calorie diet, you'd get about twice as... | [
"You would get full on cucumber or most other \"watery\" foods before you had adequately hydrated your body. But, theoretically it is possible if you ate those foods every 1-2 hours, continually keeping your stomach full.",
"EDIT: After some research, it seems as if the average human can comfortably hold about 33... | [
"Polar bear liver is very high in vitamin A-- it's meant as an example that there are foods where the amount of water you could get out of them is limited by something other than too many calories. In the case of polar bear liver, it's too much vitamin A."
] |
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