title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
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[
"AskScience AMA Series: I'm Gary Marcus, co-author of Rebooting AI with Ernest Davis. I work on robots, cognitive development, and AI. Ask me anything!"
] | [
false
] | Hi everyone. I'm Gary Marcus, a scientist, best-selling author, professor, and entrepreneur. I am founder and CEO of a Robust.AI with Rodney Brooks and others. I work on robots and AI and am well-known for my skepticism about AI, some of which was featured last week in Wired, The New York Times and Quartz. Along with E... | [
"How much of the predictions about AI are just speculation and how do the predictions of experts with a great deal of knowledge on the topic differ from the speculations of the general public? Do you think we even can predict future technology accurately, or there's just enough people making predictions about the f... | [
"My feeling that most talk about AI in the long term is speculation, and what Ernie and I focused on instead in the short-term: what are the strengths and weakness of current technology, and what could be done to improve that technology. We can see quite clearly why current machines can't for example, read, and why... | [
"Learn to code, perhaps starting with Python, and learn machine learning. And play with hardware (Arduino) is a good place to start. When he is a little older, apply for an internship at robust.ai :)"
] |
[
"How can I cook with chemistry?!"
] | [
false
] | Does anyone have the steps to brew coffe via a chemistry set, or how to make DI water at home with a chemistry set? Or cook or do anything kitchen wise with beakers, flask, burners and SCIENCE! | [
"Molecular gastronomy\n",
"http://en.wikipedia.org/wiki/Molecular_gastronomy"
] | [
"Some interesting molecular gastronomy techniques I've experimented with: ",
"Let me know if you'd like to hear about any of these in more detail. There are lots of more advanced techniques in MG that require fancy equipment and reagents (vacuum chambers, liquid nitrogen, water baths, centrifuges, etc.)."
] | [
"You can chemically cook fish by soaking it in lemon juice for about a day. I can't explain how it works, but the acid somehow chemically breaks down the fish in the same way cooking does.",
"And if you were ambitious, you could technically make DI water by burning hydrogen, and capturing the water vapor that is ... |
[
"Yesterday when I reached my destination with my car I noticed I was carrying a bee in it the whole time(I had the windows closed).Could this bee survive hundreds of miles away from its nest or is it doomed to die?Any chances it could be \"adopted\" by another nest?"
] | [
false
] | null | [
"Solitary bees are other species than social bees, such as the honeybee. They make it on their own by definition.",
"And about being adopted by another nest, I've got no idea how easy it is for a bee to locate an unknown hive. If your \"lost bee\" would find one, she would most likely be chased away by the guard ... | [
"What are \"newborn adult\" bees?"
] | [
"As it said in the last post, the newborn part comes from the bee emerging from the pupae. The bee has essentially just been born.",
"The adult part is from the fact that the bee has now entered its adult stage where is it fully formed.",
"Hence newborn adult."
] |
[
"Is it possible to know if a hash function can have collisions just by observing its algorithm?"
] | [
false
] | [deleted] | [
"All hash functions have collisions: when you try to assign a fixed number of values (let say, 2",
" for SHA256) to an infinite number of possible inputs, the hash values must repeat.",
"The important question in hash function research is: is it ",
" to find a collision?"
] | [
"Note that I was talking about hash functions that can hash an infinite set."
] | [
"No. Cryptographic hash functions and encryption ciphers are designed so that the output has a uniform distribution (it looks like random data).",
"If the output were so non-uniform that even a general purpose compression tool could reveal information, that would be very embarrassing!"
] |
[
"How do bats and other creatures that hang upside down for prolonged periods not risk their blood rushing to their heads?"
] | [
false
] | null | [
"A fair question to you would be \"how do humans stop blood from pooling in the feet?\" We'll get to that later, but a safe guess would be 'the same way but upside down'.",
"Normally, arteries lack valves to stop backflow - pressure is high enough that blood does not return. Veins, on the other hand, do; when o... | [
"The basic thing though is that compared to humans, bats are tiny. The pressure differential between whatever end it's up or down is going to be minimal. Compare that to humans, where if we're standing up the static pressure differential can be on the order of some 3psi just due to gravity."
] | [
"That's a great point too! It helps the fact that bats do still have several adaptations not found in other mammals to mitigate the stress of being upside down. ",
"For example, holding a rat upside down for a period of an hour will almost certainly be unhealthy for it."
] |
[
"How is there still radioactive carbon on earth when the planet is 4.5 billion years old? What new sources of radioactive elements are there besides cosmic dust?"
] | [
false
] | [deleted] | [
"This is almost totally incorrect, at least when it comes to C14. The OP is right, if all we had was primordial C14, then it would have decayed far beyond any measurement by now. C14 dating is considered impossible for objects older than ~50-60 thousand years because of this. 4.5 billion years would be beyond unrea... | [
"Yes. A big source is cosmic rays creating neutrons in the atmosphere. Those neutrons combine with N-14 to make C-14 and a proton. A large amount of C-14 was also created due to all the nuclear testing done."
] | [
"Yes. A big source is cosmic rays creating neutrons in the atmosphere. Those neutrons combine with N-14 to make C-14 and a proton. A large amount of C-14 was also created due to all the nuclear testing done."
] |
[
"When/Why did humans start cooking food?"
] | [
false
] | [deleted] | [
"The first fire users were Homo erectus, not our species. Evidence of Homo erectus using fire and cooking begins around 1 MYA ago.",
"Humans are considered to be any member of the genus Homo. So Homo erectus was by definition human, but you need to keep in mind this is not modern man (no vocal cords, and much sm... | [
"If you don't find an answer here, be sure to also check ",
"/r/AskAnthropology"
] | [
"Im not sure if there was a definitive time when it happend in our social evolutiuon, from what I have read the proccess of man altering food began with small steps, simillarly to leaving fruits in sunlight and letting them dry. Intresting question though, I would love to hear someone with more knowledge on the sub... |
[
"Do different plants have preferences for different wavelengths of light?"
] | [
false
] | [deleted] | [
"As Dpgg94 said, some plants absorb different wavelengths, but you can tell that isn't true of most plants because, if they absorbed different wavelengths, then they wouldn't look green.",
"Somewhat unrelated, but there was a 'futurist' post that suggested plants in the future would be black i.e. would utilise al... | [
"No, the red and blue wavelengths are optimal regardless based simply on the structure of the chlorophyll itself. Specific slight modifications in chlorophyll can produce a number of complementary compounds and accessory pigments. For example, chlorophyll a differs from chlorophyll b only in one formyl group. A sma... | [
"/r/Futurology",
" could be called /r/IGuessIMeanItsTheoreticallyPossibleBut"
] |
[
"Are there any cells in the body that lack endoplasmic reticulum?"
] | [
false
] | null | [
"You would be correct in that assumption, though remnants can remain in red blood cells. All your other cells would contain a ER seeing as they are metabolically active and producing proteins."
] | [
"Yes, osteocytes have both a nucleus and ER"
] | [
"Yes, osteocytes have both a nucleus and ER"
] |
[
"Why does being nervous cause certain side effects?"
] | [
false
] | Why when someone becomes nervous they might sweat, shake, blush, stutter, etc? | [
"Yes. This can be more broadly described as increased activity of the sympathetic branch of the autonomic nervous system. "
] | [
"Nervousness triggers the release of adrenaline, it stimulates the body's \"fight or flight\" response. Your body is experiencing the same physiological response that it would get if about to run away from a sabretooth tiger. Of course, since there are none of said tigers around, many times that adrenaline has nowh... | [
"What do you mean by \"has no where to go\"? It will always act on adrenergic receptors when it is produced..."
] |
[
"What do we mean when we say light \"wave\"?"
] | [
false
] | We always see this 2d drawn "up and down" trough vs peak type of wave. But is some sort of particle ("light") zigging and zagging up and down as it travels forward? How does it know what "up" is? Is it random? I think of double slit interference patterns when I think of this. The pattern is always horizontal. So ... | [
"We always see this 2d drawn \"up and down\" trough vs peak type of wave. But is some sort of particle (\"light\") zigging and zagging up and down as it travels forward? How does it know what \"up\" is?",
"Pay attention to what the \"up and down\" axis is whenever you see the graph. It does not denote any actual ... | [
"But is some sort of particle (\"light\") zigging and zagging up and down as it travels forward?",
"Light has the properties of both a wave and a particule.",
"However, when you start representing it as a wave, you should stop representing it as a particule. ",
"In the double slit experiment, for each point o... | [
"A wave does not necessarily correspond to motion back and forth. I'll give you a simple example. Stand in a doorway and put your hands on either side of the door jamb, so that the palms of your hands are pressing together. Now press first with your right hand, then with your left, then right, then left. If you do ... |
[
"How did the Apollo spacecrafts get past the Van Allen Radiation belt?"
] | [
false
] | Had a family friend tell me about this and I wanted to know if you guys have the answer to this . | [
"Quickly. They did not dilly dally, they did the lunar insertion burn from below the belts in Earth orbit and hauled butt through them. They also angled the trajectory intentionally to miss the worst of the belts on the way to the Moon.",
"Even so there are accounts of the astronauts being able to close their eye... | [
"Quickly",
"This is the important bit. Even though they passed through a very high-radiation environment, the missions themselves weren't particularly long. Astronauts on long-term low-Earth orbit missions (Skylab, Mir) received as much as 10 times the radiation dose that the Apollo astronauts did simply because ... | [
"They just went through them. The radiation levels in the Van Allen belts aren't generally intense enough to cause immediate harm to a human. It's probably not an area you'd want to hang out in, but the Apollo spacecraft passed through the belts in less than an hour on their way out to the moon, and avoided the a... |
[
"Why does dopamine and other \"feel good\" chemicals actually feel good? Why is our brain happy when it experiences these chemicals?"
] | [
false
] | null | [
"Dopamine is not really a \"feel-good chemical\". ",
"Opioids, endocannbinoids, and GABA fit that description better",
". Dopamine is used in the brain to help you exploit the resources in your environment. ",
"It does this by coding for reward expectations",
" (\"I expect a small reward for opening the fri... | [
"If you prevented dopamine signals from occurring in a rat, it wouldn't be motivated to seek out an available source of food. But if you put the food in its mouth, it would happily eat it.",
"I kind of feel like this already"
] | [
"That strongly suggests depression. Probably worth investigating. Please. "
] |
[
"What would happen if your body was submerged in a chamber of water and that chamber changed velocity very quickly?"
] | [
false
] | I'm having trouble wrapping my mind around this question. If I were basically in a capsule filled with water in a vehicle which ran in to a wall, would my organs still jam against my bones? I would think that since the body is around the same density as water, it would not move too much relative to the container. But t... | [
"During ",
", you'll experience ",
"While increasing G-force, what is being multiplied is the weight of the water above and below you.",
"Under one G-force, a ten-meter water column weighs the same as one atmosphere.",
"For every N G-Forces, that water column will exert N Atmospheres of pressure. plus the 1... | [
"What makes your body continue to move forward and not, say, some other water molecules in the tank? Your body is about the same density as the liquid surrounding it, so I still don't understand why it would behave differently during the acceleration than the fluid in the container."
] | [
"You would still move relative to the container. When the container hits a wall, its motion is suspended and it immediately stops moving. Since the container is filled with water, water has nowhere to go and stops moving as well, essentially acting as a rigid body (like a box, meaning it doesn't change shape or any... |
[
"Why does my dark gray shirt light up like a light bulb in Lazer Tag?"
] | [
false
] | [deleted] | [
"One(or more) of the chemicals in the short has a property called ",
"Fluorescence",
". It could be the detergent, however I lean toward cotton."
] | [
"It's been washed with \"Optical white\" - it's an additive that's used in detergents for white clothing.",
"Under normal circumstances, it reacts with the small part of daylight that's UV, downshifts the light, and emits white light. That makes the clothing look whiter than white.",
"Under pure UV, with no vis... | [
"It could also be that in order to get the gray coloring in your shirt, the manufacturer used both black and white fibers. Thus, the white fibers react to the black light in the facility. "
] |
[
"All objects in a black hole reach the singularity in finite time, yet the singularity is not within spacetime and is infinitely far from the event horizon. How does something travel infinite distance in finite time?"
] | [
false
] | Where am I wrong? I'm guessing saying the singularity is infinitely far from the event horizon is wrong in some way, but I've heard it is not contained in the topography of spacetime and is essentially infinite in distance. | [
"A few points to be made here:",
"The singularity is not an infinite distance from the event horizon. In fact, the distance is not even well-defined. Yes, it's a rather unsatisfying answer, but that's that. The only really meaningful quantity in this context you can talk about is the proper time it takes for an i... | [
"The solution is not valid for all time. Note the singularity at ",
" = 1/",
". Since the solution must be valid at t = 0, we see that the solution is valid only for ",
" < 1/",
". That's exactly what my point was. Beyond some finite time, the model breaks down."
] | [
"The equation ",
" = ",
" is a separable ordinary differential equation whose solution is ",
"(",
") = ",
"/(1 - ",
"). The acceleration is ",
" = dv/dt = 2r*dr/dt = 2",
". So the particle moves under the influence of a cubic force law."
] |
[
"When a person gets stomach flu (viral gastroenteritis) or food poisoning, what exactly is happening in the body that causes stomach cramps?"
] | [
false
] | Title really says it. Quick Google searches simply list stomach cramps as a symptom, but what exactly are they? What's happening in the body that results in a stomach cramp? Do they serve a purpose in the sick/healing process? Or are they just a painful reaction to the sickness? | [
"The body says “damn I gotta get this out of me”. \nThe body also knows that the GI tract is basically a long tube so it increases peristalsis (the normal contractions of the stomach and intestines). This increased peristalsis really gets going, causing cramping. ",
"Also as a general thing of infection, inflamma... | [
"I’ve seen this described as: If the caboose of a train (food in your stomach) has a bomb (spoiled food or toxins from a pathogen), the whole train needs to start moving faster to get the bomb out of town (your body). ",
"Since muscles are what moves that “train,”moving faster can cause cramps, just like quickly ... | [
"There are 2 aspects at play here. ",
"Microorganisms and/or their toxins do their actions on stomach cells and cause cellular destruction, which creates pain that is perceived as stomach cramps. ",
"The destruction causes inflammation of the stomach mucosa. The afferent portion of the vagus nerve will be stimu... |
[
"How long does muscle memory stay built up?"
] | [
false
] | How long is muscle memory retained if something is given up for a period of time? Also how much practice do you need to put into an activity each day to maintain muscle memory? | [
"I'm sorry to say that I have a feeling some other users that have already replied to you have come here to speculate without knowing much about the topic at hand. ",
"First things first - it's most definitely, in any case, ",
" \"just like any other memory\". ",
"Squire and Zola (1996)",
" offer a very sim... | [
"But do those pathways in the neurons for that task degrade over time more than neurons innately degrade or something?"
] | [
"I do not do sensorimotor research, which means I don't have insight in current research trends and conventions in that domain. Furthermore, you asked a very delicate question (we're talking about things ",
"2-3μm",
" in size, that is take 1mm, divide it into 100 equal parts, take one of those parts, and divide... |
[
"My SO has narcolepsy and I've been trying to do research but I was wondering if anyone could tell me if there is a specific term for someone who doesn't go through the stages of sleep properly."
] | [
true
] | [deleted] | [
"When a ",
"narcoleptic",
" falls asleep, they generally experience the REM stage of sleep within 10 minutes; most people do not experience REM sleep for at least 90 minutes.",
"Another instance during which an individual may progress directly to REM sleep is that which follows protracted sleep deprivation, a... | [
"This is correct. ",
"When someone is tested for narcolepsy (and other sleeping disorders) they measure how fast you go into REM sleep. ",
"If you show symptoms off all other characteristics of narcolepsy but do not show signs of fast transitions into REM sleep, they can not officially diagnose you as \"narcole... | [
"Narcolepsy has a wide range of symptoms and varies from person to person. I was hoping that ",
" particular symptom had a name."
] |
[
"Which model of evolution is more accepted by the scientific community: gradualism or punctuated equilibrium?"
] | [
false
] | null | [
"Both are extremes; the reality in most cases lies between them.",
"In general, an population of organisms will fairly quickly (in geological timescales) reach a point where it is as adapted to its environment as it can be, and it will settle into a niche. At that point, large scale changes aren't likely to happ... | [
"I thought both were accepted...",
"Take a look at the ",
"Escherichia coli long-term evolution experiment",
". E-coli were shown to have adapted for cell size gradually, and 1 strain evolved the ability to use citrate to perform aerobic respiration."
] | [
"Why is it an either or scenario? Mutations always happen as cells and organisms grow and divide. However, environmental selective pressures are always changing. If the selective pressure were always the same then you would expect that most populations would look pretty homogeneous and this is only true for extreme... |
[
"How are skeletons dated, and is it accurate?"
] | [
false
] | null | [
"There are several answers here already pointing out that bone can be dated directly by ",
"C dating (and in terms of its accuracy, you might check out several questions and answers in our ",
"FAQ",
" which deal directly with this), though it is worth noting that because of the relatively short half life (com... | [
"I'm sure you've heard of carbon dating, correct? All living things absorb carbon from their food/environment. Among which, includes radioactive carbon-14. This carbon-14 has an extremely long half life and, when we die, we stop absorbing it and what we've absorbed starts to decay. we can use our knowledge of how l... | [
"No it wouldn't. Although it probably would make it harder to determine the baseline, ie the original ratio of stable/unstable isotopes. I remember one creationists who was saying that before flood there was much higher concentration of oxygen and dinosaurs who came off the noah ark after the flood had so much diff... |
[
"What is happening, physically and computationally, to my computer as it degrades over the years?"
] | [
false
] | [deleted] | [
"A lot of people are giving very valid answers about software bloat, disk fragmentation, and so on. These are the most likely culprits. However, I wanted to add a few points about how physical hardware can degrade. Modern hardware is becoming increasingly sophisticated at dealing with marginal conditions which m... | [
"I can answer the computational/software part of the question.",
"There are a couple reasons why over time your computer appears to be \"slowing down\" with regards to how long it takes to load, how high settings you can use, etc.",
"MSConfig",
"defragmentation",
"There are likely other parts of the OS/soft... | [
"Also, programs get bigger, and take more resources than they did before. Check out steam for example. It updates every day. Steam used to be a super lightweight program years ago, now it's a full fledged entertainment portal. Also, even older games' system requirements change over time. Heck, even windows system r... |
[
"How have continents survived plate tectonics for this long?"
] | [
false
] | If plate tectonics "recycles" the Earth's crust by subsuming and melting down plates, and then generating new material elsewhere, how the heck have the continents/plates as we know them survived so long? I remember seeing a map of Pangaea breaking up (something like this: ) and being amazed that basically every recogni... | [
"What am I missing here?",
"What you are missing is that we have 2 types of crust: continental crust and oceanic crust. For some reason, the first couple of times we stare at those animated maps you mentioned, our mind plays a trick on us as we focus on the familiar continents, but completely ignore the volumes o... | [
"Indeed, ocean plate is much ",
" than continental plate (but the continental plate is normally thicker)."
] | [
"Thank you for the great reply. I think I get it, but just to confirm: So each tectonic plate is made up of a lot of weak-ass material that gets destroyed like it's nothing, and that weak-ass material also happens to be all underwater. The strong stuff that lasts through aeons (only losing tiny, tiny chunks at a ti... |
[
"If Venus and Earth are approximately the same size, why is Venus' atmosphere so much thicker?"
] | [
false
] | I'd heard years ago from a forgotten source that the reason is because of the fact that our moons mass is particularly high compared to ours (highest ratio in the solar system) and that over time the moons gravity had pulled a lot of our atmosphere out into space where it dispersed. When I mentioned this in a discussio... | [
"Most of Earth's CO₂ is bound in the carbonates (such as limestone). When CO₂ dissolves in water, it forms CO₃²⁻ anions, which react with several metal cations to form insoluble carbonate minerals, such as limestone or dolomite.",
"When you heat carbonate minerals, the CO₂ is released, and carbonates turn into ox... | [
"Venus has a runaway greenhouse effect - the key word being \"runaway\". As an atmosphere gets warner, it's able to hold, e.g., more water vapor - which in turn increases the effect further. Venus probably had liquid water on the surface for the first few hundred million years, but it's believed to have completely ... | [
"This is the correct answer. Everyone else is way off point. ",
"In fact, it's possible that Venus being slightly closer to the Sun meant slightly higher temperatures, which shifted the Carbonate-Silicate cycle towards production of carbon dioxide over carbonates, which then initiates the runaway greenhouse and s... |
[
"What is anatomically different about women that makes them so much more flexible than men?"
] | [
false
] | I am aware that woman have much less muscle tissue than men in general so that must help contribute to the flexibility as there's less 'muscle belly to soften' so to speak. So what other reasons are there for their flexibility? Is it the shape of the bones? And if so, what's exactly different? Especially in regards t... | [
"Flexibility trades against muscle strength. Men are very capable of becoming ",
"contortionists",
", but doing so places limits on how much muscle they can possess. Similarly, women who build up a lot of muscle lose some flexibility. Olympic sprinters of both sexes are rather inflexible. Note the rarity of bul... | [
"Female pelvis is shaped differently to male melvis, (although really I should say there is a spectrum of gynoid to android pelvises, where men and women can be anywhere on it but whatever..)",
"http://shs.westport.k12.ct.us/forensics/11-forensic_anthropology/forensic_skeletons/pelvis%20by%20gender.gif",
"shows... | [
"I see. That makes sense. I suppose also that the more muscle someone has, the more scar tissue that may be built up within it, causing the muscle to act more like leather rather than rubber. Then I also suppose that \"muscle knots\" become more likely as well within large muscle bundles that don't allow full ra... |
[
"I've read that water is \"incompressible.\" Are there any properties of water in the deep ocean that are different from what's in my glass?"
] | [
false
] | null | [
"I think it's important to clarify that \"incompressible\" is an engineering assumption. You can think about what engineers do as taking all possible equations and throwing irrelevant ones out to get at the core of a problem to be solved. Throwing out a perfectly valid equation or term because you know, or claim to... | [
"Have there been any experimental attempts to compress water, e.g. with incredibly powerful machinery?",
"Water is compressed all the time in hydraulic systems (at least those that actually use water) and the like. It just doesn't compress very much. In terms of exploration of the properties of water at differe... | [
"Nothing is truly incompressible. Things like diamond and steel are much harder to compress than water. It's called incompressible only because we are comparing it with gasses which have orders of magnitude lower resistance to compression (technically referred to as the bulk modulus). Some properties are different,... |
[
"If light and sound propagate in waves that result in constructive and destructive interference, does gravity behave the same way?"
] | [
false
] | null | [
"Constructive and destructive interference are a general wave phenomenon. They can happen with any kind of wave."
] | [
"That's what I thought. So, with gravity, what happens at the points of interference?"
] | [
"It's the exact same thing with any kind of wave. The total amplitude is reduced in a region of destructive interference, and the total amplitude is increased in a region of constructive interference."
] |
[
"What makes a person naturally stronger than others?"
] | [
false
] | Is it testosterone? What other factors affect a person's physical strength besides strength training? | [
"Heritability",
" is a technical term which refers to the extent with which a trait (such as height, weight, strength, eye colour etc) is under genetic control. So a trait such as eye colour is 100% heritable, whereas traits such as preference for horror films is not heritable at all. Many traits fall somewhere i... | [
"From a physiological point of view, several factors affect strength, which should be defined as the maximum voluntary torque that a person can produce at a joint (let's say elbow flexion for our example)",
"There are others, but these are a few major factors"
] | [
"That would be my right arm, due to performing repetitive tasks with a mouse at work. It was extremely bad. I almost got something called frozen shoulder because I was keeping that arm so still and tucked close to my body to prevent pain. Then I wore my arm brace too long, my muscles in that arm atrophied, which ma... |
[
"AskScience AMA Series: We are Drs. Brandy Beverly, Kimberly Gray, Pauline Mendola, Carrie Nobles, and Beate Ritz. We study how environmental factors, like air pollution, affect child health and development. Ask us anything! #WomenInScience"
] | [
false
] | When most people think of the "environment," they may think of green spaces, buildings and sidewalks, and air and water. In the context of child health, environment includes conditions in the womb as well as situations that exist before conception. Managing environmental factors and exposures before, during, and after ... | [
"Hi, this is Beate. Yes, there are studies of the human microbiome and neurodevelopment - especially in autism spectrum disorder where it has been shown that the microbiome of autistic children is different from children who do not have autism spectrum disorder. There is, however, a lot we still need to learn abou... | [
"Hello again!",
"Has any research been done on environmental pollutants and the human microbiome, particularly on dysfunction (neuro or otherwise) that may be related to disruption of the microbiome?",
"Thanks!"
] | [
"Hello, I (26F) am currently working on my MPH with an environmental health focus. I would like to focus my career on the climate and health issue. Do you recommend continuing to get my PhD? Do you have any other advice for females starting their careers within this field?"
] |
[
"When an airplane is flying a few miles high does it matter which direction the earth is spinning underneath?"
] | [
false
] | [deleted] | [
"The plane is always in the Earth's rotating reference frame. It was rotating with the Earth when it took off."
] | [
"Well you could argue that there are some air currents that are caused by the coriolis effect due to earth's rotation, that actually affect the speed at which planes travel (jetstream for example), but since OP did not seem to take thins that serious you are correct."
] | [
"The Earth spins to the east. Looking down onto the North pole from a position in space, it spins anticlockwise.",
"The rotation of the planet will not case a major problem for aircraft as they are 'connected' to it via the air. It is a problem for spacecraft as the Earth can rotate independently, some of the ear... |
[
"At what scale is the universe expanding?"
] | [
false
] | I understand (more or less, a lot less) that the universe isn’t expanding “into” anywhere, but where within the universe is the expansion happening? Is the space between atoms, or the subatomic particles comprising atoms increasing? Are the particles themselves getting bigger? (Compared to what?) Am I getting bigger? (... | [
"At what scale is the universe expanding?",
"On the scale of a few megaparsecs, which is approximately the scale of a galaxy group.",
"For example, all of the ~80 galaxies (mostly dwarf galaxies) in our ",
"local galaxy group",
" are gravitationally bound to each other and will eventually merge into a singl... | [
"This is awesome, thank you for the thorough, fascinating answer!"
] | [
"Thank you for sharing your astonishingly comprehensive knowledge of this!"
] |
[
"A candle gives off infrared light, and can be used as a stand-in for the Wii horizon sensor. Can a LCD screen on a phone do the same thing?"
] | [
false
] | I guess it boils down to : can a LCD emit light outside of human visual range? | [
"Could you make an LCD that emitted infrared light? Yeah. Does the screen on your phone? I doubt it; they're designed to output as much energy as possible in the visible spectrum; specifically, for each individual pixel you want all the energy to basically be in a very narrow frequency range. Emitting energy in IR ... | [
"Most LCD screens use cold cathode flourescent backlighting or white LED backlighting. This is essentially a blue/violet narrow spectrum light (based on either the design of the LED or the materials used in the CCFL) that excites some yellow/green phosphors to cover most of the visible spectrum. I don't believe tha... | [
"Thanks both you. Im regarding this as solved. Too bad, I was wondering if I could make an app that acts as a tv remote using IR."
] |
[
"If I bend my third (middle) finger under and lay my hand on a table, why can't I raise my fourth (ring) finger up, but I can raise the others?"
] | [
false
] | I have tried to figure this out reading about hand anatomy and physiology but nothing serves to explain this seemingly antagonistic relationship. Could anyone share any information to explain the mechanism of this phenomenon? Thanks askscience! | [
"I easily can. "
] | [
"So why doesn't it work conversely? If you keep the ring finger down, the middle finger easily lifts."
] | [
"So why doesn't it work conversely? If you keep the ring finger down, the middle finger easily lifts."
] |
[
"Sound question"
] | [
false
] | Assuming the microphone that captures the sound of Big Ben is 1metre away from the bell, and that the sound is broadcast live without using satellite to a listener 2000km away, how far away would I have to stand before the radio listener hears the sound before I do? | [
"Radio waves travel at the speed of light, so if we assume that signal transfer from the microphone to the radio receiver is instantaneous, and that travelling 2000km for light is (nearly) instantaneous, then as long as you stand more than 1m away from the bell, the listener should hear it before you.",
"In reali... | [
"We can make some broad assumptions, however, and come up with some rough numbers:",
"Geosynch satellite delay is 250ms round trip. ",
"Sound travels about 85m in 250ms. ",
"So, if the person standing in front of the clock is closer or equal to 85m, they will most definitely hear the clock ",
" the satel... | [
"Not to mention that we don't know how far the radio listener is from their radio."
] |
[
"Why did convenient traits that are seemingly unnecessary for survival, such as eyelashes, evolve?"
] | [
false
] | [deleted] | [
"I think you're talking about sexual selection (as opposed to ecological selection) which is a sub-section of natural selection."
] | [
"There are several reasons we have retained hair above the eyes in the form of eyebrows. One is that they protect our eyes from dirt and sweat (similar to eyelashes), but they also help with social interactions and communication. Facial expressions are very important for humans and eyebrows make the muscle movement... | [
"To us - eyelashes might appear trivial because we now have other methods for compensating loss of eyesight.",
"But back when we were hunter-gatherers, a deterioration of your eyesight because some crud got in and caused an infection or you didnt blink in time to protect your cornea from a foreign object would ha... |
[
"How come there's a Amoeba with 200 times larger gene set than humans?"
] | [
false
] | Amoeboid: Genome comparison: I thought larger the genome = more complex the species. Is that not the case, or is Amoeboid really more complex? | [
"Eukaryote researcher here.",
"The ",
" lifeform is far less complex than a human, even though it carries far more genetic code.",
"A larger amount of genetic material ",
" of greater complexity, but does not ",
" it. Note also that a great degree of ",
" can be had from a very small set of instructions... | [
"This is fall-out from the widely publicized ENCODE papers released last year. It's wrong. In fact, since the term \"junk DNA\" was originally coined by Ohno (1972) to refer to non-coding DNA of unknown function, much of the 98% of the human genome that is non-coding is \"junk\" by definition, since we don't know w... | [
"Kolmogorov complexity isn't that useful of a metric for quantifying the \"complexity\" of a DNA sequence. Consider these two sequences:",
"1) atgggtgcga gagcgtcagt attaagtggg ggaaaattag atgcatggga gagaattcgg ttaaggccag ggggaaagaa aaaatataga ctgaaacatc tagtatgggc aagcagggag",
"\n2) ggattataac ttaaagcaag ctagctc... |
[
"Apart from the Sun, what is the Earth's second foci for its elliptical orbit?"
] | [
false
] | I've recently learned about ellipses, and a little about their functioning. For a body to orbit elliptically, it needs to have two focus points, one being the Sun. From my (limited) search online, the Earth's second foci is an empty point in space, devoid of any physical object. But I really can't get an intuition for ... | [
"It's just a point in empty space. There's not really anything special about it. ",
"Now for why. In all honesty, I think you're asking the wrong question. I would ask this: why does something need to be there? Yes, the second focus is a \"special\" point associated with the orbit, but so are the center and the e... | [
"The focii are points such that (distance to focus 1)+(distance to focus 2) is constant. The difference between the focii is that when the orbiting object is nearest the first focus (the Sun) it is going fastest, but when it's nearest to the second focus it's going slowest. ",
"This gif",
" shows the motion of ... | [
"Isn't the second focal point within the sun itself?",
"I read somewhere that the Earth's elliptical orbit is very close to a circle. If scaled down to 400 metres diameter, the longer axis would only be 1 mm longer than the shorter one."
] |
[
"Is an invisible material physically possible ?"
] | [
false
] | [deleted] | [
"Yes, it is possible to a certain extent.",
"Scientists are currently working with \"metamaterials\" which are usually composed of metals and ceramics. ",
"Scientists are making small things appear and disappear but for an invisibility cloak which is seen in Harry Potter - We are a long way from.",
"The Army ... | [
"We also have glass and air, lots of thing don't interact very well with some frequency of light without having to invoke dark matter or even things like neutrinos. He's not asking about a transparent material, he's asking about a cloaking material for an opaque object, which is not related to dark matter. "
] | [
"Object made invisible to microwaves.",
"http://www.businessinsider.com/microwave-invisibility-cloak-2012-11",
"https://en.wikipedia.org/wiki/Metamaterial_cloaking#Metamaterials_and_transformation_optics",
"The invisibility cloak from japan. It's just a projector and a cloth nothing that spectacular.",
"htt... |
[
"Is there a reason why anaerobic respiring organisms never acquired the ability to use the citric acid (TCA) cycle?"
] | [
false
] | [deleted] | [
"The TCA cycle would not help anaerobic respiration. It is mainly used, in aerobic respiration, to convert more NAD and FAD to NADH and FADH2. In anaerobic respiration those have no use. In aerobic respiration they are where most of the energy comes from. So adding the TCA cycle to anaerobic respiration would be ba... | [
"It's a very tricky thing to ask for why an organism evolved a mechanic or did not evolve one. The answer is always a very unsatisfying \"the selection pressure and random mutations led to this being an optimum evolution path at the time\". So the answer here is that there exists a niche where there is significant... | [
"Oh I should have clarified. Anaerobic respiration isn't fermentation. Anaerobic respiration is found in some organisms that can use an electron transport chain that ends in a non-oxygen terminal electron acceptor. In either case, NADH is used in fermentation and anaerobic respiration pathways. Fermentation relies ... |
[
"Is water the only substance with a neutral pH? If not, do other neutral liquids have similar or wildly different chemical properties from water?"
] | [
false
] | in chemistry we learned how special water is, but in such a large universe there must be other compounds are similar. also,mare there areas with lakes that have basic pH? I know acidic lakes can result from pollution, what about basic? | [
"First of all- you will be hard pressed to find a sample of water that is a perfect pH 7. ANY impurities will throw it off. The acidity of water will depend on where you live. Even distilled water is rarely a perfect pH 7 due to dissolved CO2 and other gases. ",
"There are, however, solutions that are a perfe... | [
"First, almost all water on earth is basic (typically pH 8ish) due to dissolved minerals.",
"Second, the specialness of water largely arises not from it's neutral pH but from its properties caused by hydrogen bonding."
] | [
"The definition of pH is based on water as the solvent. I believe you ask about solutions with a solvent other than water, but something that produces H",
" . These are called protic solvents, ammonia is perhaps the most popular one, but the determination of pH in such solutions gives limited information. For an ... |
[
"Are there any other species of animal that are divided into different races or something biologically equivalent?"
] | [
false
] | Dogs come to mind, but they were artificially created. | [
"All organisms have varying levels of diversity on all levels. Diversity between individuals within a population, and between populations. It is important to note that speciation is not a singular event, but the accrued genetic differences between populations, typically divided by some type of barrier, over time. I... | [
"SuperKingdom, Kingdom, Phylum, Class, Order, Family, Genus, Species, ",
" Anything in the variety category are variants of a single species. E.g., Northern Flickers (a kind of wood pecker) have red- and yellow-shafted varieties. ",
"However, it's worth noting that humans ",
" have varieties. Races are ge... | [
"Yep. Without interbreeding between the populations, they would have inevitably become more and more distinct from each other, and at some point be considered separate species. This would have taken hundreds of thousands or millions of years though."
] |
[
"Is there a theoretical limit to the resolution/level of detail that a telescope could achieve, current technology notwithstanding?"
] | [
false
] | If some alien civilization 500 light years away had a powerful enough telescope, could they see what, for example, my roof looks like? What are the factors that limit the level of detail? I have no idea about the way light travels, etc, but I got to wondering, looking up at the sky the other night, if it was possible a... | [
"Every telescope (and microscope) is ",
"diffraction limited",
". This relates the aperture of the telescope to the angular resolution. This means larger mirrors (telescopes usually use mirrors and not lenses) can resolve objects further away. If we are not limited by technology and we could build telescopes o... | [
"Imagine you had a big reflecting telescope, with a mirror the size of the Earth. You'd get amazing resolution. Now start covering up bits of that mirror with tape, until you're left with just two uncovered spots on the opposite sides of the mirror. The resolution will stay good throughout this process, but you'll ... | [
"How exactly interferometry is used to \"increase\" the size of telescope?"
] |
[
"Is the second human kidney a redundant system?"
] | [
false
] | I just read that one kidney would be perfectly capable to function properly without the second one. Why did evolution give us a redundant organ? | [
"Bilateral symmetry. Same reason why we have two lungs.",
"The bottom line is that having two kidneys isn't bad. It doesn't hinder you, so it slips right through natural selection like smoke through a screen door."
] | [
"Firstly, it's important to note that evolution does not necessarily produce the \"best design\". Other creatures have their fair deal of vestigial organs. An example in humans would be our ear muscles... they are pretty useless but yet we still have them.",
"However, it's not hard to see why two kidneys are more... | [
"Oh ok, so that's what I was doing wrong."
] |
[
"Can we imagine time?"
] | [
false
] | null | [
"If you can imagine something moving or changing does that count?"
] | [
"But then you'd be imagining motion through space but not necessarily time"
] | [
"Motion is change over time. "
] |
[
"When I cook bacon (100 calories) and drain the grease (1-2 Tbsp), the bacon is now 100-x calories, where x is the calories of the grease, correct?"
] | [
false
] | I'm trying to count my caloric intake as closely as possible, and wanted some verification regarding my question because I can find calories in bacon on the package and bacon grease calories on the web. The packaging I assume states the bacon calories along with its fat, but when cooked down, I assume it loses a hefty ... | [
"Yes, but honestly you should count them anyway because calorie counts tend to be on the low end for all foods you eat throughout the day. Keeping it in will probably bring you closer to an accurate number of calories."
] | [
"Inaccurate sure, but that's not a one-sided bias."
] | [
"calorie counts tend to be on the low end for all foods you eat throughout the day.",
"Citation? Or do you mean personal bias and not FDA mislabeling?"
] |
[
"If gravitation propagates at the speed of light, then isn't the Sun actually pulling the Earth from where the Earth was 8 minutes ago? What physical consequences does this have?"
] | [
false
] | null | [
"This is a surprisingly subtle question, that has been answered best in a paper by S. Carlip, found ",
"here",
".",
"In short, the force on the Earth points toward the Sun's current position, not its position 8 minutes ago. This can be seen from simple symmetry arguments, and is referred to as the ",
".",
... | [
"No, the explanation only works if the star is moving at a constant velocity. If the star suddenly moves it is no longer in an inertial reference frame."
] | [
"Perhaps I'm not grasping the concept very well, but doesn't that suggest a possible form of instantaneous transfer of information over long distances faster than light? ",
"In your scenario where the sun was the moving object and earth was stationary, lets say the moving sun suddenly changed its trajectory to t... |
[
"How did Apatosaurus and other long-necked dinosaurs sleep?"
] | [
false
] | null | [
"We really have no idea since no one was there to see, but what we can do is observe modern long neck animals and try to come to a conclusion on how they may have done it.",
"Giraffes sleep by curling their necks and using their own bodies as pillows. Like this ",
"http://static.neatorama.com/images/2013-05/bab... | [
"Have you never seen giraffes in a ",
"neck fight",
"?",
"Sleeping is the least of their worries."
] | [
"I really hope that I am not breaking a rule, but I'm pretty sure ",
"swans sleep with their heads tucked back"
] |
[
"Why does heat seem to intensify smells?"
] | [
false
] | [deleted] | [
"The actual mechanism behind smelling something is a compound coming into contact with the olfactory receptors in your nose. This typically requires these compounds to be airborne to be inhaled. At higher temperatures, molecules evaporate and become airborne more readily, thus there would be more molecules in the a... | [
"Vapourisation or sublimation, yes. If the compounds are not directly coming from something from sublimation or vapourisation, then they are being formed in the environment. The smell from sulphur is actually hydrogen sulphide, and heating the environment could increase the reaction rate to form hydrogen sulphide s... | [
"Vapourisation or sublimation, yes. If the compounds are not directly coming from something from sublimation or vapourisation, then they are being formed in the environment. The smell from sulphur is actually hydrogen sulphide, and heating the environment could increase the reaction rate to form hydrogen sulphide s... |
[
"Does the mass of a black hole increase by any appreciable amount by absorbing photons?"
] | [
false
] | We all know that light cannot escape from black holes. Over the course of tens/hundreds/thousands of millions of years, does a black hole absorb so much light that its mass could measurably increase? | [
"The mass of the black hole will increase by exactly the energy of the light absorbed, divided by c",
". This is just conservation of energy combined with E=mc",
" for the black hole.",
"I did a very VERY rough estimate for the total mass gained by the supermassive black hole at the center of the Milky Way (S... | [
"Way more than a skyscraper, way less than the moon. Apparently (after looking it up) it's on the order of the mass of the water in a large lake (think Lake Michigan)."
] | [
"Mass doesn't matter. In physics, you follow the energy. Photons may not have ",
" mass, but they do have energy (all kinetic). E=mc",
" is a convenient conversion, and can get you the mass equivalent of any amount of energy (and vice-versa). But the full form of the equation is:",
"E",
" = (mc",
" )"... |
[
"Do any animals have family relationships that last into adulthood?"
] | [
false
] | After a baby animal is all grown up and left the parents' care, do any of them continue to maintain ties with their siblings or parents? Do any of them treat siblings/parents differently (e.g. less likely to compete with them for mates, cooperate more)? Are there any animals has a family structure that continues unti... | [
"Most animal group dynamics operate off of something called inclusive fitness. If an animal demonstrates altruism (risking its own fitness (survival and reproduction for the sake of another)) or not usually depends on what percentage of its own genes that other individual (the one that they might display altruistic... | [
"Yes, all eusocial (truly social) species, especially the hymenoptera (ants, wasps, bees), and the eusocial mole rats. If you're thinking of vertebrates, there are tther social species that form long familial relationships well into adulthood, like wolves, lions, hyenas, African wild dogs, and all the herding ungul... | [
"Yes, in certain species. There are numerous mammal species that live in groups and maintain at least friendly/tolerant relationships with their parents, but some bird species do as well! ",
"Florida Scrub Jays",
" are probably the best example: they have extremely tight-knit, long-lasting family relationships... |
[
"If all the water in the atmosphere condensed into liquid form and became water, how much would sea levels rise?"
] | [
false
] | [deleted] | [
"The mean ",
"mass",
" of water vapor in the atmosphere is estimated as 1.27×10",
" kg",
"\nSince about 3.6x10",
" m",
" of Earth's ",
"surface",
" is covered with water, and water's density is around ",
" 1000 kg/m",
" this means a rise in (1.27/3.6)x10",
" m = 3.5cm would occur, if all the a... | [
"Water's density is ~1000 kg/m",
" ",
"So you are off by 10",
" The "
] | [
"Would the increase in surface area covered by water by increase of water level be too minimal to not have an effect on this level of accuracy?"
] |
[
"Why will the James Webb Space Telescope put so far out in Space?"
] | [
false
] | i read that the JWST will be put near the Lagrange point L2, that is a position where the gravitational forces of both Earth and Sun keeps the Telescope at the same distance to both Earth and Sun throughout the year. what's the benefit of this? spitzer and hubble took nice photos too, and were located much much closer ... | [
"Hubble was put in a particularly low orbit so that crewed maintenance missions could reach it. However, there are costs to this. You have to design your telescope to be maintainable, and given the costs of the extra design and the costs of crewed spaceflight, it may almost be cheaper and easier to just replace one... | [
"Yes, JWST will have reduced sky access due to the need to keep the telescope in the shade. The mirror and telescope are all fixed with respect to the sunshield (after deployment anyway), the whole spacecraft moves to point the telescope. This means that that the telescope can't observe objects in the Sun direction... | [
"Spitzer was actually on an Earth trailing orbit, much further away than JWST will be. It was about 265 million km away from the Earth when it was finally shutdown. Kepler was also on a similar orbit, but as it was launched later it wasn't as far as Spitzer. Spitzer required this distant orbit because it was shown ... |
[
"Does Halley's comet get smaller after each orbit?"
] | [
false
] | If the tail of the comet is all the melting ice and dirt then should it be getting smaller. Or does it gain more ice and dirt as it flies back into deep space? Edit: I misspelled tail | [
"According to ",
"this",
" paper, the mass of Halley's Comet is 2.2e14 kg, and the mass lost in the '1910 apparition' the comet lost 2.8e11 kg. ",
"At that rate, Halley's Comet will run out of mass in about 60,000 years, but it will mostly lose its volatile ices, leaving a rocky asteroid behind, so it is lik... | [
"From my understanding, comets shrink over time if their orbit goes into the inner solar system. The ",
"comet tail",
" is a result of solar radiation from the sun, blasting off material from the comet. Just like ",
"this",
". This would lead me to believe that material is left behind by the comet after eve... | [
"Yes over time comets lose mass as their ices are sublimated away by the heat of the Sun. This also blasts a lot of dust away to form the comet's tail. Larger boulders and heavier dust grains often fall back to the surface though since the gas pressure lifting them isn't enough to overcome their weight. Most comet... |
[
"Given recent developments in our understanding of water/ice bodies on Mars, is it possible that we could one day be surprised by Martian fossils? Or do we have reason to believe that Martian life would be limited to microorganisms?"
] | [
false
] | I keep reading about Martian water, ice sheets, Lake-Superior-sized deposits of H2O, et cetera, fascinating stuff, and I'm wondering- is it possible that we Earthlings could send astronauts to the Red Planet, to ultimately discover fossils of extinct Martian flora & fauna? Or, if we can eliminate this possibility, how? | [
"It's not ",
" (because that's a pretty high bar to clear) but I'd say it's very, very unlikely.",
"The reason is time. Multicellular life didn't become common on Earth until 500-600 million years ago (EDIT: ",
" showed up on Earth very early. But it consisted of microorganisms). There are a very few possib... | [
" seems to have showed up on Earth very quickly, but took a very long time for animals and plants to appear. ",
"Look at the diagram on ",
"this pdf",
". The leftmost set of bars is Earthly geological eras, the one just to the right is Martian eras. Earth had a proper crust by the start of the Archaen, Mars... | [
"Is it possible that Mars had cooled and was able to support life while Earth was still in it's cooling period? "
] |
[
"What's the smallest form that one pound on Earth takes?"
] | [
false
] | [deleted] | [
"Gravity at the core might be zero, but the pressure of the upper layers of the planet, which ",
" being pulled down by gravity, would still be extremely high. That's the important bit."
] | [
"Ahh yes! Looks like I was the one who misspoke..."
] | [
"Sure, if you throw one of those elements into the core of Jupiter or something it'll get much denser, but in terms of their solid metallic form under Earth atmospheric temperature and pressure, those are their densities."
] |
[
"Where do the particles being smashed together at the CERN Large Hadron Collider come from?"
] | [
false
] | I'm imagining a small opening where a guy in a white lab coat is pouring a bowl of some substance inside. Where do the particles really come from? | [
"I think it might be ",
"this bottle of hydrogen gas on the left",
"."
] | [
"tl;dr: Bottles of gas and chunks of lead.",
"The LHC collides two types of particles - high energy protons and lead nuclei. This is simply hydrogen and lead with electrons stripped off in an initial ionization chamber before being injected into the system of accelerators that is the LHC.",
"The interesting pa... | [
"It's just ionized hydrogen and lead, nothing fancy."
] |
[
"Can you make a \"soap bubble\" underwater? That is, a water-filled bubble with a thin, non-water liquid membrane separating it from the surrounding water?"
] | [
false
] | So a soap bubble is a pocket of air surrounded by a thin membrane of soap and water, separating the inside air from the outside air. Is it possible to do a similar thing underwater, where it's water instead of air inside and out? What non-water liquid would work as the membrane? It would be fun to make a device that ca... | [
"Yes, it`s called an ",
"antibubble",
". A liquid sphere encapsulated by a membrane of gas in another liquid.",
"-Guy who used to study bubbles for a living."
] | [
"No.",
"No it doesn't."
] | [
"Bubblologist."
] |
[
"Why can't we vaccinate for STDs?"
] | [
false
] | As a youth we are given many vaccinations (Polio, Mumps, Measles, Hepatitis, etc.) that prevent us from getting diseases later in life; why can't we do the same for things like Chlamydia, Gonorrhea, Herpes, and other sexually transmitted diseases? | [
"it's an obligate parasite,",
"Amazing how much so. It can't produce its own ATP, and thus depends on its host's cells for ATP."
] | [
"it's an obligate parasite,",
"Amazing how much so. It can't produce its own ATP, and thus depends on its host's cells for ATP."
] | [
"We can now use the ",
"Gardasil vaccine",
" against certain strains of the ",
"HPV virus",
" which causes genital warts and cervical cancer (and also other less common cancers). "
] |
[
"How far could a colony ship capable of a constant 1 g of acceleration travel within on lifetime?"
] | [
false
] | Say the emdrive magically works and we're able to make it millions of times more efficient than we ever dreamed, to the point that it can provide 1 g of acceleration to a large spaceship powered by nuclear reactors. How far could the spaceship get to (and stop, not just fly by) within the lifetime of the passengers? | [
"See ",
"my recent post here",
". A spacecraft that is capable of maintaining a 1g proper acceleration can easily travels tens of billions of light-years within a passenger's lifetime. Earth would be long dead though. ",
"A proper acceleration of 1g for a substantial distance is far beyond what current techno... | [
"Nothing you describe violates any physical law, only current capabilities of engineering. There may also be some other undiscovered mechanism that would allow such travel. So my original statements seems correct."
] | [
"A proper acceleration of 1g for a substantial distance is far beyond what current technology is capable of",
"It's far beyond what a rocket is capable of, regardless of technological level. You can't get effective exhaust velocity faster than the speed of light, so the mass ratio of the rocket must be astronomic... |
[
"Calculating the temp for pyrolysis (in vacuum) for a given polymer."
] | [
false
] | This is my epoxy: I am heating it in a vacuum after it has set. I would like to know how of a high of a temperature it can reach before the organic components begin to decompose/degrade. The sample will be heated for eight hours. I thought this would be a simple, measurable material property, but it seems like most of... | [
"Probably have to go about it experimentally, via DSC or DGTA."
] | [
"This although if you only need a rough estimate there have been tons of studies done on the thermal stability of BPA type epoxies."
] | [
"Good point, DSC should tell me exactly what I need. Thanks!"
] |
[
"Why can't we just look up at the moon with a telescope to where the astronauts landed to disprove conspiracy theorists?"
] | [
false
] | [deleted] | [
"The unfortunate truth is that even if you could organise guided tours of the landing sites, you wouldn't convince the conspiracy theorists. The fault is not in the data but in the psychology of these people. ",
"A conspiracist is not motivated by the objective evaluation of evidence, but rather by their cynicis... | [
"http://spaceinfo.com.au/wp-content/uploads/2011/09/apollo_12_575.jpg"
] | [
"The moon is very far away, and even a good backyard telescope will not be nearly powerful enough to see details like the flag or moon rovers. ",
"However, we already have reflecting plates that were places there by the Apollo astronauts that we can shoot lasers at to determine distances etc. We've been using the... |
[
"What exactly is happening when you get the \"wind knocked out of you\"?"
] | [
false
] | [deleted] | [
"If what i've learned is correct \"getting the wind knocked out of you\" does indeed have to do with the diaphragm being impacted. When hit hard enough the diaphragm begins to spasm and contract, instead of expanding and contracting along with the rhythm of your breath, leaving you with a harder time breathing in p... | [
"When your wind is knocked out, it usually means your diaphragm has gone into spasms (usually from a blow to the stomach but sometimes can be psychosomatic or caused by excessive shallow breathing) and can't draw air into your lungs."
] | [
"The nerves that control breathing have been hit and it takes them a few seconds to start working properly again I've heard."
] |
[
"Why are some lakes clear and others murky?"
] | [
false
] | Even if the water is still. Won't all the sediment settle to the bottom eventually and become clear. | [
"Sediment isn't the only thing that colors water. Tannins, such as from trees, can contribute to the brown color in water, which is what forested lakes tend to be more brown but mountain lakes at elevation where trees don't grow are more clear."
] | [
"Uhmmm actually ",
"u/SheBeast14",
" was right and you are wrong.",
"\"These tannins can leach out of the plants. The water in the soil becomes rich with tannins and seeps into the ground water or drains into lakes and streams. These waters become brown in color and look like tea.\"",
"https://www.fs.fed.us... | [
"I worked as a pond and lake manager for a couple years. One of the main things we focused on was the transparency of the water. If the water was too clear then algae and other weeds would grow. In order to keep the water clean it had to be a certain level of opaque. ",
"The opacity of the water is caused by the ... |
[
"In terms of circular motion, why doesn't the moon crash into the Earth?"
] | [
false
] | null | [
"http://en.wikipedia.org/wiki/Newton's_cannonball",
"Imagine a cannon atop a very tall mountain. Due to gravity, the cannonball falls toward the Earth. What if you fired a cannonball fast enough such that the curvature of the Earth was a factor - so that when it fell 1 meter, the Earth had curved away from it 1... | [
"To add to max's point, think about the international space station... Earth's gravity is ALMOST as strong at it's altitude as it is down here at sea level... it stays in orbit because it is flying at around 17k mph and thus constantly \"freefalling\" over the edge."
] | [
"To add to max's point, think about the international space station... Earth's gravity is ALMOST as strong at it's altitude as it is down here at sea level... it stays in orbit because it is flying at around 17k mph and thus constantly \"freefalling\" over the edge."
] |
[
"Heavy Ion fusion experiments"
] | [
false
] | Does anyone know about this? There is no Wikipedia page on it yet, could someone explain what it is and how promising this might be? | [
"Go here:\n",
"http://hif.lbl.gov/",
"They have a good explanation during the slides under Fusion tutorial. Just want to say that the US just cut most if not all funding for heavy ion fusion. "
] | [
"Well that depends on who you ask. Half the NIF people say it is for power and want to build LIFE. I think it is more of if you are a physicist or an engineer for what answer you get."
] | [
"I believe it does have merit for stockpile stewardship. It is not easy getting high energy density conditions and that area of plasma is still not well understood. I have the same feeling for it, its mission was originally just stockpile stewardship but then it changed to include achieving ignition. It is an am... |
[
"What implications would there be if the world spun in the reverse order it does now?"
] | [
false
] | [deleted] | [
"The Earth is revolving around the sun approximately once every 365 days. ",
"If the Earth didn't rotate at all, the sun would still rise and fall as the Earth went around it making a full year a single 'day'.",
"If the Earth is rotating in the same direction as the revolution, it does not have to go all the wa... | [
"Do you mean if it spun that way from the getgo, or if it randomly switched directions today?",
"Anyway, the sun would go from West to East, and the solar days would be about eight minutes shorter."
] | [
"Also - hurricanes would spin clockwise in the Northern hemisphere",
"New age books would be talking about the dawning of the 'Age of Taurus' as the Earth would precess in the other direction, which would mean that the musical ",
" would sound completely different."
] |
[
"Is there a solid substance anywhere on earth that cannot be melted?"
] | [
false
] | It might be a dumb question but I always wondered if there was a substance known to man that can withstand any amount of heat. | [
"There's no possible configuration of matter that can withstand \"any amount of heat.\" Enough heat, and even protons come apart.",
"Plenty of things can't be melted, though. You can't melt paper."
] | [
"Fine print: some ",
"refractories",
" have higher melting point than diamond, by ~200K.",
"Bonus fun fact: diamond has the best heat conduction of all solids. So if you have a 1m thick block of diamond, and place one edge at 3810K, it's ",
" not safe to touch the other side in a second or two. (In fact, ... | [
"So there are a couple of points to this.\nMelting is turning from solid to liquid, and there are a number of substances that skip a liquid phase, for example dry ice.",
"You are talking more about substances that cannot changed from their solid state. As far as i know diamond is going to have the highest meltin... |
[
"With all these new cases of measles, if the virus mutates, can people who have already been vaccinated become susceptible?"
] | [
false
] | With every case of measles, the chance of mutation exists. I know that every virus has a different mutation rate, how high is measles compared to other diseases like chickenpox? When the new cases pop up, do they test that strain against the one used to make the vaccine? How exact do the antibodies given in the vacc... | [
"The same question was asked last week. Is some meme going around claiming this is a concern? It really isn't. It's a theoretical issue, but in practice measles simply doesn't mutate that way. ",
"First, remember that this may seem like a large epidemic to us, but it's a tiny, tiny fraction of the enormous, world... | [
"I don't know if they are, but probably; that's the sort of thing that surveillance programs do as a matter of routine. (",
" The ",
"CDC Measles Lab",
" talks about serological testing, which means looking for vaccine reactivity.)",
"The epidemiology of the latest outbreaks argue very strongly that the vac... | [
"Thank you so much. I searched in the sub for mutations and measles and nothing came up and the CDC website didn't have a concise explanation. Do you know if they are testing the current cases against the vaccine strain?"
] |
[
"How difficult is it to provide cell service on underground services such as subways?"
] | [
false
] | If we can have cell assisted Internet access on above ground services like trains why can we not do the same underground? | [
"Very good question. It depends. If you put your transmitter above ground, it is almost impossible to get the signals deep underground and it would be a waste of energy to try to. If you put transmitters inside a tunnel you can actually reach quite far with them because the signals would reflect a lot. So we could ... | [
"Korean subway lines have full 4G coverage, it's definitely possible."
] | [
"In Boston we have cell antennas",
" in the underground sections of the subway. There's a hiccup when transitioning from above/below, but otherwise it's pretty great. Boston has a much smaller system than, say, NYC, so it's a lot easier to cover, but it shows that it's possible."
] |
[
"What are these things that i keep finding on the beach?"
] | [
false
] | null | [
"Probably not",
"Those rocks used to have agates in them. Because the agates are harder than the surrounding rock, they don't wear down as fast. As the rock around them is worn down by the surf, they eventually break free, leaving these cavities. Sometimes you can find ones that aren't completely freed, and th... | [
"Looks like a rock that used to house coral."
] | [
"Sorry, but I don't buy into the agates idea. At least one rock looks like very weathered coral. What beach are you collecting these on?"
] |
[
"How do astronomers gauge whether or not a planet is habitable?"
] | [
false
] | I live with a man whom has no faith in science, I cant explain it very well too him, so please scientists, please tell me, How do we tell wether or not a planet is habitable? How does the craft that has been sent into space help? and everything else. Thankyou in advance. | [
"based on the star it orbits, how hot it is and the atmosphere of the planet, they can tell whether certain things could be on the planet.",
"There is a specific region of space specific to ever star that water can be on the planet or not. ",
"As we know it all life needs water ( not saying life couldn't form w... | [
"Thanks!"
] | [
"Baldrad covered the basics, but I would like to expand. The region he referred to is called the ",
"circumstellar habitable zone",
", or 'Goldilocks zone'. It is a region in which a planet with sufficient atmospheric pressure can have liquid water at its surface. This is a function of the stars mass and abs... |
[
"What is the estimated depth of the liquid water oceans on Titan?"
] | [
false
] | [deleted] | [
"Hi, this is my research field.",
"As a reminder, Titan has two kinds of liquid geography. There are ",
"\"lakes\" or \"seas\"",
" of methane and ethane that sit on its icy surface, which are fairly shallow (about 100 meters) and small (about the size of the North American Great Lakes).",
"But this questio... | [
"We have no idea. ",
"The pressure probably isn't a problem: the pressure near the bottom of Titan's ocean is similar to the very deepest places we've found life inside Earth's crust. ",
"But we know very little about what kinds of energy sources life could use for metabolism in that ocean -- that is, what co... | [
"We have no idea. ",
"The pressure probably isn't a problem: the pressure near the bottom of Titan's ocean is similar to the very deepest places we've found life inside Earth's crust. ",
"But we know very little about what kinds of energy sources life could use for metabolism in that ocean -- that is, what co... |
[
"Does anyone know of a scientific guide to yoga for beginners? (or have any tips for getting the most out of non-spiritual yoga?)"
] | [
false
] | null | [
"There's that book Anatomy of Yoga."
] | [
"This website",
" has a lot of beginners yoga videos that aren't very \"spiritually based\". They mostly just talk about being aware of your body, so that you can focus on your form. "
] | [
"Good site thanks!"
] |
[
"From my 12 yr old while watching the Nova Kilauea episode: If I threw a rock in the lava coming out of the volcano, how long would it take to melt? Or would it?"
] | [
false
] | We were watching, he asked, and I got curious, too! How long would it take? Or is the lava cooled enough that it doesn't have enough heat to melt rock? Or does it depend on the type of rock? | [
"This is a tough question. Geologists have argued about it for years!",
"First, do you mean lava or magma? Lava is magma that is erupted. The difference is important for two reasons...",
"1) Basaltic lava is generally the hottest kind of lava. It is about 1200 C maximum when it erupts. Even basaltic lava cannot... | [
"When rocks melt they do so incrementally and gradually; most rocks are made of several minerals, all of which have different melting points, and the physical/chemical relationships controlling melting are complex. As a rock melts, its volume changes. When enough rock is melted, the small globules of melt (generall... | [
"Knowing this, would it be considered feasible to fly aircraft with payloads of rocks to help slow the flow of lava, to give potential evacuees more time to escape?"
] |
[
"Why is the most common psychological side effect \"suicidal tendencies\"?"
] | [
false
] | I know there's an aspect of confirmation bias here, but it seems like more often than not a side effect of various drugs is "suicidal thoughts or tendencies." Why is this such a common side effect? Is there some aspect of brain chemistry that makes us susceptible to it? Why aren't there side effects like "Sudden insati... | [
"This can be a side effect of anti-depression drugs. We are not sure of the exact mechanism, but here's the current thinking. ",
"The most severely depressed patients often have suicidal thoughts already. When treatment begins, the patient may start to have more energy and motivation first, days or weeks before t... | [
"Holy shit. I can't read."
] | [
"I would call \"nausea\" far more common. But it's not nearly as sexy, so you probably don't notice it."
] |
[
"What affect does the quantity of injuries have on healing time? For example, would a paper cut take longer to heal if I had a broken Jaw at the same time?"
] | [
false
] | Edit: First gold, thank you kind stranger. | [
"A fun bit of trivia:",
"In polytrauma injuries involving a traumatic brain injury and bone fracture, the fracture may actually heal at a faster rate than the same fracture alone. The mechanism is currently not well understood, but some researchers speculate it's related to enhanced macrophage mobilization.",
"... | [
"Common to have multiple injuries, like in the surgical ICUs from traumas. Healing comes down to infection control, nutrition (usually the issue) and rehab.",
"With large body surface area burn patients, very hard to feed them enough, even with a feeding tube 24 hrs a day to meet calorie requirements to heal.",
... | [
"A distal injury won't affect another injury until it begins needing more resources than the body has to distribute - take burns for example. ",
"If you had a burn on your hand all sorts of plasma and proteins and immune related cells would be rushing to the site (some already there) causing both local inflammati... |
[
"If you can convert kinetic energy into heat energy, how could the universe experience a heat death if supermassive objects like black holes or dwarf stars would constantly be attracting other bodies via gravity?"
] | [
false
] | I don't know if that makes sense, but if a star were to eventually burn out and turn into a white dwarf or neutron star or something of that sort, its gravity would be around the same right? Wouldn't objects in their vicinity be affected by the gravity and therefore have kinetic energy constantly? | [
"I don't know if that makes sense, but if a star were to eventually burn out and turn into a white dwarf or neutron star or something of that sort, its gravity would be around the same right?",
"Technically no, a solar-mass star would shed about half of its mass in the process of becoming a white dwarf, but I don... | [
"A star burning out and turning into a white dwarf or neutron star will have less mass, and therefore less gravity, because it has lost energy (and therefore mass) through radiation, and mass (and therefore energy) through winds. But that is not really related to the answer to your question. The short answer is the... | [
"Gravity doesn't give anything kinetic energy, it just changes the ANGLE at which it's traveling. At no point in this is energy added. If the object suddenly hits something and it's velocity relative to the object it's orbiting reaches zero then it will have no kinetic energy and from that point on it will fall int... |
[
"Why do we lose consciousness when exposed to high levels of radiation?"
] | [
false
] | For the most part, I feel I have a cursory understanding of why the other systems and organs fail in such a circumstance. But most of the info and stories I've looked up also mention the victims fainting or losing consciousness minutes or hours later, but never explaining why. | [
"Large, acute doses of radiation can affect the central nervous system. You'd already be experiencing other symptoms of radiation sickness by this time because the central nervous system cells are among the most robust when it comes to radiation exposure. But a high enough dose can affect it the same as any other... | [
"How does it do this?",
"Is it just the physical breakdown of the nerve cells? Or is there something more \"mechanical\" about it? Like some sort of systematic interference or something?"
] | [
"Neurotransmitters are constantly created, excreted, absorbed, and broken down. This is a natural part of a neurons function. If a high enough dose of radiation was experienced, it could damage almost any part of the neuron. For instance, it could damage the cells function by damaging the genes responsible for crea... |
[
"Elemental half life is always quoted as a constant for a particular isotope. Why doesn't it vary with temperature, for example?"
] | [
false
] | null | [
"Generally, what's happening in the nucleus is pretty independent of what's happening on the atomic level (imagine a tennis ball in the center of an inflated beach ball. does the bouncing of beach balls affect the tennis ball in the middle?). The exception is electron capture or inverse beta decay, which depends on... | [
"Could you elaborate on the temperature dependence of electron capture and the inverse beta decay? At least in a solid the temperature associated with the fermi level is orders of magnitude above the phononic temperature. ",
"I am sure I am missing or confusing something here but I would not have thought that the... | [
"It does, the effects are usually very small and are highly dependent on the isotope. The variation of a half life can occur for isotopes that undergo electron capture decay or internal conversion. These forms of decay depend heavily on electrons. So modifications to the chemical environment or the electron shel... |
[
"How do proteins, RNA, etc. organize and interact with each other within a cell?"
] | [
false
] | Based on my biology classes from high school, it seems like cellular processes often depend on many different molecules coming together in a particular way. For instance, to translate mRNA, ribosomes need a specific tRNA for each of the codons, and protein complexes are made of several proteins that come together in a ... | [
"you are correct it is over simplified. For one many of those videos show only the specific molecules they wish to highlight and leave the area around them empty, giving the impression of vast open spaces. In reality there are millions of these molecules all closely packed together with other molecules. They bump a... | [
"In cellular scale, the microtubules form a transport network which can move vesicles, cell organelles and chromosomes in quite a coordinated manner, however pretty much everything else happens in completely chaotic way due to thermal motion.",
"The molecules are just randomly vibrating, bounching and flying aro... | [
"Aren't the dipole interactions effective over \"large\" distances, a few times the molecular size? They don't have to actually touch to be draw to each other."
] |
[
"why is the sexual peak for women so much later than for men?"
] | [
false
] | null | [
"Is \"sexual peak\" even a legitimate theory?"
] | [
"but why?"
] | [
"There are many intelligent reasons for biological processes, no reason why anyone would be \"lolling\" here either"
] |
[
"Why don't we lose our fingerprints when we skin our fingers?"
] | [
false
] | I recently had an incident where I skinned my hand on some concrete and it's currently healing. The new skin is pink and tender, but it has the same print pattern as it's always had. How are these ridges the exact same? | [
"Hello,",
"Dermatoglyphic patterns come from a deep layer of your skin: the ",
"papillary region",
". Your incident must have skinned your fingers superficially (only the epidermis) if the pattern comes back."
] | [
"Exactly right, some organised crime groups have been known to put their fingers in acid to dissolve their fingerprints, leaving a smooth layer ",
"EDIT: here is a source i found with relevant and further information, ",
"http://usatoday30.usatoday.com/news/nation/2007-11-06-criminal-extreme_N.htm"
] | [
"Fingerprints isn't entirely genetic - the environment of the womb has great influence in how they form during fetal development. That's why identical twins have different fingerprints."
] |
[
"Does higher octane/premium gas actually cost more to produce? What makes it so much more expensive?"
] | [
false
] | [deleted] | [
"The higher octane is a premium though. It is actually less combustible allowing it to be compressed further before ignition so it can be used in higher compression engines.",
"It does cost more to refine, but not as much more as the higher price tag."
] | [
"They don’t tune there compression ratio they have knock sensors and they increase there ignition advance"
] | [
"They don’t tune there compression ratio they have knock sensors and they increase there ignition advance"
] |
[
"Does getting rid of mucus (coughing or nasal) help decrease your time of sickness (cold or flu/covid)?"
] | [
false
] | I wonder if spitting it out you get rid of some portion of the virus or if it's just your body trying to make it easy on you, but the virus stays unaffected. Is there any advantage to force coughing it out etc? | [
"1) It's not like, by spitting it out or blowing your nose, you're reducing your virus load - like it's a tank of gas you're trying to empty. That's not the way it works.",
"2) It may be helpful to get rid of excess mucus and prevent further congestion and other problems - like an ear infection. ",
"Ear infec... | [
"If there is mucus in your lungs, coughing it up absolutely helps you breathe easier. A dry cough doesn't do anything, but a wet cough improves your ability to breathe. Which you might have experienced in the past with coughing up mucus and feeling better. ",
"https://www.pnas.org/doi/10.1073/pnas.1817484115"
] | [
"Vomiting/diarrhea has various causes - one of which is to eliminate bacterial toxins (not necessarily the bacteria or virus itself). In some cases, the virus/bacteria/parasite is encouraging you to vomit/diarrhea to help it spread easier (norovirus, vibrio, cryptosporidium, etc.).",
"So not necessarily to help ... |
[
"Are there tornadoes in Europe?"
] | [
false
] | Might be a dumb question. I don't recall hearing about them outside of the US really. That could say more about American media than anything else... | [
"Yes. In fact, per unit area, the UK gets more (reported) tornadoes, whirlwinds and waterspouts than ",
" any other country in the world*. The difference is that we don't have the big open plains environment that allows truly massive storms to develop, so what we get are usually no more than an F0.",
"In the US... | [
"In fact, per unit area, the UK gets more (reported) tornadoes, whirlwinds and waterspouts than anywhere else in the world",
"This is a common misconception: sure, yes, if you break it down by country Britain ",
" have the highest numbers of (",
"it may actually be the Netherlands",
"), but that's because y... | [
"Yes, it might sound pedantic, but I'm not trying to be, I think it's an important point: tornado alley is far bigger than the entire UK, so it's a much larger area that also gets more tornadoes per area. Saying the UK gets the most tornadoes per unit area than anywhere else is really not correct at all."
] |
[
"Do wireless chargers use energy when not charging a device? If so, what form of energy is the electrical energy converted to?"
] | [
false
] | In regards to the law of conservation of energy, what form of energy is the magnetic energy made by a wireless charger when not charging transformed into? Heat? | [
"Does the device feel warm? If not, it will not waste much energy. \nHeat will always be a component of the lost energy, but in this case, a portion could be transmitted as electromagnetic waves (similar to how sunlight transports energy) ."
] | [
"Wireless chargers use different techniques to achieve a tightly coupled inductive field. Yours is a very good question, that if I understand correctly, is about how the transmitter and receiver communicate in order to start charging. Answer depends on which of the interoperability standards is used, but in general... | [
"Most of the wireless chargers detect presence of receiver or if it is fully charged.",
"As such it would not transmit power anymore.",
"However, the power would be converted into heat in the coil and into em waves emited into space. They will be eventually absorbed by things and converted into heat too."
] |
[
"How do interplanetary spacecraft radiate the heat from engines/electronics in a vacum, so they don't overheat?"
] | [
false
] | null | [
"They radiate heat as electromagnetic waves.",
"http://en.wikipedia.org/wiki/Thermal_radiation",
"Some small spacecrafts are designed to radiate heat from the spacecraft's body. But when they are larger, or have too much heat to reject, they may need dedicated surfaces for that. Radiators are usually painted wh... | [
"Engineering student here. All heat is dissipated through radiation in a vacuum. Most surfaces on space equipment are coated in a material that has a very low absorptivity and consequently high reflectivity (assuming transmissivity is 0) That is one of the reasons the colors of the space shuttle and space suits are... | [
"Thermal management is a big deal for spacecraft. All spacecraft radiate their heat away, some in different ways than others.",
"One of the simplest and oldest systems is to use \"louvers\" which are basically like window blinds. Since it's typically the electronics on the interior that build up heat if you put a... |
[
"How long after death does all electrical activity in the brain cease?"
] | [
false
] | null | [
"There’s multiple definitions of death, and it actually varies by area. Most definitions look at cardiac death and brain death. Cardiac death is when there is no heart beat. Without blood flow delivering oxygen to the brain neural activity stops in minutes. ",
"Brain death is defined by certain testing parameters... | [
"Somewhere in the 10-20 minute range, and a little age dependent. In a newborn or very young mammals, even 12 minutes of complete asphyxation does not kill any brain cells. But 20 minutes is typically irrecoverable. I suppose that just being irrecoverable does not mean all activity has ceased, but if you added anot... | [
"I don't know for sure. But, it could be. ",
"Tunnel vision is common during hypoxic situations. Temporal lobe seizures can cause religious delusions. Put those together and you might get the sort of experience you are alluding to."
] |
[
"Why do lionesses leave the safety of the pride to give birth?"
] | [
false
] | null | [
"One of the major causes of cub mortality is from infanticide by male lions during a pride takeover. Very young cubs (e.g. a few weeks old) are far more likely to be killed by a male lion during a takeover compared to a ",
"cub that is a little bit older",
" (Pusey & Packer 1987). When female lions retreat to g... | [
"do females in a pride that is doing well and has a strong male defender(s) give birth closer to the pride because they aren't as worried about a possible intruder male? ",
"Unfortunately specific details such as these are difficult to answer - lionesses are so elusive when they have newborns that they are diffic... | [
"Thank you for your reply. So, as another question, do females in a pride that is doing well and has a strong male defender(s) give birth closer to the pride because they aren't as worried about a possible intruder male? Or do the females instinctively prepare for the worst and always assume another male may attemp... |
[
"Would we be able to detect our own radio bubble?"
] | [
false
] | [deleted] | [
"The Murchison Widefield Array is a brand new radio telescope in the middle of nowhere, Western Australia. Because it's in the middle of nowhere, they're able to include the FM radio band in the range of frequencies they're sensitive to. ",
"However, they noticed that the moon was unusually bright in the FM rad... | [
"And Proxima Centauri is (just) 4.24 light years away. Signal strenght 70 light years away would be 0.02% from what it's in Proxima Centauri (calculated in my head, might be wrong)."
] | [
"I have seen a few shows talk about this (on the Science channel and what not) and they said the radio signals would be far too weak for something to pick them up after so many light years. I can't recall the exact number but hopefully someone can give it to you. But the signal gets weaker the further from the sour... |
[
"If you put an extremely powerful speaker underwater, can it turn it into steam?"
] | [
false
] | I know that you get longitudinal pressure waves from sound, but does that sound even heat the water up? | [
"Yes, you can induce cavitation with intense sound radiation. Here's a video: ",
"https://www.youtube.com/watch?v=qGSioE58YjA",
"https://www.youtube.com/watch?v=ZakZQ5lNL3c"
] | [
"If you think speaker induced cavitaion is cool, google the 'pistol shrimp'.",
"It's main method of defense is to strike with its claw so fast that it creates a hugely powerful cavitation bubble ahead of it."
] | [
"Actually, pistol and mantis shrimps are very different and are only very distantly related. They're in fact two different taxonomic orders, decapod and stomatopod, respectively. "
] |
[
"What is the resistivity of a superconductor above it's critical temperature?"
] | [
false
] | [deleted] | [
"For traditional superconductors, the resistivity above the critical temperature is whatever it is for the base material in the normal phase. This usually has either a constant dependence on temperature (disorder limited) or a T",
" dependence (e-e scattering limited).",
"When a superconductor goes back to its ... | [
"To answer your additional question, regarding the current quench: the bulk of the cross-sectional area of a superconductor isn't actually superconducting. There are small strands or strips of superconducting material housed in substantially thicker copper coils (this, in turn, is housed in a structural frame, com... | [
"It depends on the superconductor. Generally it increases with temperature from that point.",
"Example: ",
"http://jpsj.ipap.jp/news/jpsj-nc_35-fig2.gif"
] |
[
"is there a theoretical limit on the magnification provided by telescopes?"
] | [
false
] | Or, does light have a 'resolution limit' as we try to look at smaller and smaller objects from greater and greater distances? Suppose we had an absolutely telescope, that magically scaled up to whatever size was necessary to get a good view of the target, whether that was a radius of 1 million miles, 10,000 AU, 5 billi... | [
"Yes. There is very much a resolution limit on telescopes, as there is on every optical system. It's called the ",
"diffraction limit",
", and for ",
"telescopes",
" it's (1.22 * wavelength)/telescope diameter.",
"As you can see, the ability to resolve two separate sources is inversely proportional to the... | [
"Putting aside the fact that such a phenomenally large device might collapse under it's own gravity, the universe is \"only\" 93 billion light years in diameter. Honestly I have no idea what you'd theoretically be able to resolve because most of the imaging equations assume that your system is smaller than, say, a ... | [
"This is a very hard question. The basic elements of telescope imaging are well understood. Those contain information about maximum resolution. We use tricks though. We can put a telescope 600 AU out from the sun and image things behind the sun in its Einstein Ring. Multiple telescopes can work in conjunction. It m... |
[
"If heat makes things expand then how is it used for shrink wrapping things?"
] | [
false
] | null | [
"Heating shrink wrap takes advantage of the thermoplastic memory of the film. Imagine the polymer chains are like spaghettis, when you make shrink film you stretch the polymers out until the spaghettis are straight, then you freeze them solid. When you apply heat, it softens the polymer and allows them to stretch b... | [
"Cool thanks! "
] | [
"Whether something expands or not with temperature change is a material property; there are many materials that shrink when heated or expand when cooled. ",
"Not the best example since there is a phase change and the molecular structure is physically altered, but water expands when it freezes.",
"I can also de... |
[
"Is the entropy of the universe increasing monotonically?"
] | [
false
] | I've heard statements like "systems tend to progress in the direction of increasing entropy" when dealing with the second law of thermodynamics. The use of the word 'tend' implies to me that the universe's entropy could decrease for some period of time, so long as it is statistically outweighed by the overall increase ... | [
"Source: ",
"Wikipedia: Entropy",
":",
"\"Statistical mechanics demonstrates that entropy is governed by probability, thus allowing for a decrease in disorder even in an isolated system. Although this is possible, such an event has a small probability of occurring, making it unlikely.\""
] | [
"As I mentioned below, hikaruzero's wikipedia link disagrees with that statement. Do you have a source to back that up?"
] | [
"The second law of thermodynamics is a statistical law, not a fundamental one like, say, conservation of energy. The entropy of an isolated system, could, in principle, \"magically\" decrease due to a random fluctuation, but the bigger the system, the less likely this is. For the entire universe, the probably of th... |
[
"Does the heat from other stars affect our temperature on Earth?"
] | [
false
] | Just came to mind. Would be interesting to know | [
"Technically yes, since energy is arriving on Earth, but the effect is negligibly small. A quick approximation is \"how bright is a moonless night compared to daylight?\" That gives you a zeroeth order idea of how much of a difference it makes. There are other things to include if you really wanted to, like light i... | [
"A way that stars affect our weather is via the effect of cosmic rays on the formation of clouds. This research topic is still early, but it looks like high-altitude clouds can be triggered by cosmic rays. How those high clouds affect weather is less clear (eg, do they block incoming sunlight or do they trap outg... | [
"Yes, because all the light that we can see is essentially radiation. However, the only way to measure by how much it heats would be to analyze the ALL amount of radiation/light hitting the earth from all the stars out there. If we were to do this, we would come up with such a small number that perhaps even our mos... |
[
"What would happen is the core stops spinning? I just saw several news articles that the earths core has stopped and maybe reversing. If it doesn’t reverse what happens and if it does reverse what happens?"
] | [
false
] | I just saw several news articles that the earths core has stopped and maybe reversing. If it doesn’t reverse what happens and if it does reverse what happens? | [
"Ok, so to start, the paper that sparked this is ",
"Yang & Song, 2023",
". ",
"To back up though and provide some context, there has been a long-standing suggestion that the Earth's inner core \"super-rotates\" meaning that the solid inner core spins ",
" faster (in an angular rotation rate sense) than the... | [
"Damn! This guy super-rotates. Thank you for the awesome explanation!"
] | [
"Thanks for your great explanation. Unfortunately this is another case of the media being unable to interpret a scientific finding and then over simplifying it to a sensational level."
] |
[
"Why is fresh water used for hydraulic mining?"
] | [
false
] | Live in Alberta, Canada; generally don't mind the oil mining activities here, but this makes me scratch my head. Would it not make more sense to use salt or recycled water, rather then wasting our fresh water resources? | [
"salt water is highly corrosive, it would destroy almost all of the equipment that they use. "
] | [
"fresh water ",
" recycled water. There's no such thing as wasting it; our used water goes into a treatment plant, then into a river and then back into our water supply. It's a closed system, doesn't really matter at which point you extract water for mining or something else. Using waste (gray) water for mining w... | [
"the problem starts when you break that cycle. in some use cases your fresh water leaves the \"fresh water cycle\" and ends up in the sea. then it becomes salt water and is basically lost (for now...). ",
"this happens a lot with agricultural use where water evaporates and rains down somewhere else into the sea. ... |
[
"Are new fossils in the process of forming, and if so, why can't I find anything about them on Google?"
] | [
false
] | I understand that fossilization is rare, but there should still be millions of skeletons in the process of fossilizing right now all around the world. I can't seem to find anything about these in-process fossils. You'd think there'd be a whole field of science dedicated to studying these specimens. Is there? Also, my G... | [
"There is a huge science that studies in-process fossils. It is called archeology.",
"I say that because \"fossil\" is a rather arbitrary term for remains over about 10,000 years old. Fossilization itself doesn't take very long, at least not in geologic terms. There are a few exceptions, but anything over 10,0... | [
"Archaeology is the study of human-related remains. I guess what I'm asking is, where are all the buried fish, whales, birds, lizards, rats, etc., that are under a layer of sediment but not yet completely fossilized? I would assume they'd be at the bottom of lakes, rivers, oceans, and in mudslide and sandstorm area... | [
"Maybe kouhoutek meant ",
"paleontology",
"."
] |
[
"Could someone explain the Independent Component Analysis method?"
] | [
false
] | I am aware of the complex explanations but a simpler layman style explanation would be much appreciated :) | [
"Asking the stats folks at ",
"/r/statistics",
" might be a good idea."
] | [
"Hmm must drop a cross post there too I guess. Thanks mate."
] | [
"Is this similar to \"principal component analysis?\""
] |
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