title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Is there such a thing as a \"bad dog\"? (assuming the owner is a good person)"
] | [
false
] | [deleted] | [
"If you look at pure breed working dogs, such as collies or retrievers, they were explicitly bred for particular temperaments and it shows."
] | [
"If you look at pure breed working dogs, such as collies or retrievers, they were explicitly bred for particular temperaments and it shows."
] | [
"Yeah. Just like you can have human sociopaths, you can have canine sociopaths too. This is the only reason I'd ever consider buying a purebred dog; their personalities tend to be a lot more predictable."
] |
[
"Why can feathers/skin/scales become colors that normal hair can't?"
] | [
false
] | Birds can have feathers that are vibrant, reptiles can have skin/scales that are different colors as well. Mammals are fairly plain and drab because normal hair doesn't seem to have as wide of a variety of color available. Why?? | [
"The big gatekeeper is the blue components of color. The methods of getting blue pigment are very limited in nature, many of the creatures that look blue are actually not that color from pigment but instead from small scale structures that interact with light. ",
"That said, asking \"why\" with any biological/evo... | [
"What we see as color is not what other animals see. So while we may see a deer as brown, a vulture could see it as rainbow (ok not that extreme but you get the point). ",
"Another point is most color in the animal world is used for something, either sexual selection, danger sign, or hiding. ",
"Larger animal... | [
"I get it but some others might not get how you transitioned. The change was from 'Why are mammals boring?' to 'Why DON'T mammals have interesting color schemes?'",
"I assume that that is what you are getting at, amiright?"
] |
[
"What neurological differences are there in a crow's brain that allow it to have such high intelligence for its size?"
] | [
false
] | null | [
"Cognitive science is really only just getting to the meat of this area. For a long time people didn't really accept that birds could be intelligent, because they do not possess a neocortex. Later they argued that there must be mammalian like neural structures to allow such intelligence. That wasn't right either.",... | [
"The amygdala has no role In higher reasoning in any species. I mentioned cognition because I studied this topic (and wrote a paper on it) from a cognitive behaviour point of view. Animal behavior and neurology and cognition are becoming more bound together as our understanding of brains grows. It's important to be... | [
"Do you know if this applies to the parrots as well, i.e. the other group of birds with high intelligence? The African Grey in particular would probably be a good example."
] |
[
"What is the relationship between (tensile) strength and hardness?"
] | [
false
] | Iron rod is stronger than glass. But one cannot make scratches on glass surface as easily as on iron rod, hence glass is harder than iron rod. It is said that when glass shatters, it is not because of its poor strength, but because of a powerful shockwave passing through it. But then, why doesn't the same happen with i... | [
"Usually strength and hardness show positive correlation.",
"It is said that when glass shatters, it is not because of its poor strength, but because of a powerful shockwave passing through it.",
"Not really. Glass breaks when it's strength is exceeded, just like any other material.",
"But then, why doesn't t... | [
"I found the last part difficult difficult to understand when you say brittleness is not same as weakness.",
"Yes, it's a common misconception, but maybe thinking about the diamonds are extremely hard, tough, and strong, yet brittle, may help. It may also help to think about what a ",
"fractured ductile specime... | [
"Thanks for the item by item answer. I found the last part difficult difficult to understand when you say brittleness is not same as weakness. I know tensile, compressive, shear strength. What is bearing strength as an fourth type of strength? Is brittleness a fifth type of strength? Or has brittleness nothing to d... |
[
"Just bought a geiger counter and am not sure how to make sense of the results it gives me."
] | [
false
] | null | [
"0.26 uSv/h is normal background radiation",
" so your readings are below what could be considered normal. There is nothing to worry about. Use that table as a guide to what radiation levels are dangerous, but I promise you that you will not detect any unsafe radiation levels from Japanese tea."
] | [
"thanks so much! Glad to hear your are confident about this. "
] | [
"Generally radiation is the easiest thing to detect (as you have found out). Everybody along the chain from the grower to the distributor in your country can easily check for radiation. Additionally, any radiation which finds its way on to tea will be dust which falls on to the leaves. This dust will be washed off ... |
[
"Why do I get erections from things that don't sexually arouse me?"
] | [
false
] | null | [
"While I can't vouch for everything, morning wood is a fairly common phenomenon. The exact cause of it is not yet understood, but its known to be strongly associated with REM. Interestingly enough, this is what lead Freud to (erroneously) assume that all dreams somehow have sexual content. "
] | [
"Strange, from what I remember- REM sleep is also associated with nightmares and more negative dreaming. You'd think that negative dreams wouldn't get you aroused. And, from what I remember from psychology- REM sleep is fairly early in your sleep cycle so, does morning wood stay up till then?"
] | [
"SCIENCE!"
] |
[
"Van DeGraff Generators and their voltage, how can I check it?"
] | [
false
] | Does anyone know a good way to measure the voltage difference of the ball of a Van DeGraff and a ground? I'm a physics teacher trying to give my students a feel for what this idea of voltage means to them. I've tried using a straight voltmeter, but it seems to be giving me voltages that are too low. Why is this not ... | [
"One possible way could be to measure the maximum length of a spark generated by the Van DeGraff Generator, and based upon the dielectric breakdown of air, approximate a voltage."
] | [
"A rule of thumb picked up while I was in college (tending to our University's Van de Graaff) is that the insulating capacity of dry air is 20kV per inch. This is very dependent on he amount of moisture in the air though. I am also a high school physics teacher and would be curious to see you get anywhere with the... | [
"Interesting idea. I may try that and give it to my AP students as a practice problem/lab."
] |
[
"Does Mars' axis tilt? Does Venus'?"
] | [
false
] | So... History Chanel the other day. This documentary (and others) keep saying that our big Moon keeps Earth's axis stable, preventing our planet from tilting. And here's my question: Does Mars' axis tilts constantly? Does Venus' ? | [
"Mars has an axial tilt of about 25 degrees, a little more than earth's.",
"Venus has an axial tilt of 177 degrees...which is another way of saying it has a tilt of 3 degrees, but spins backwards relative to earth.",
"But the real question is how they vary over time. The earth's tilt doesn't change by much mor... | [
"It's not really my field (I do physics, but not astrophysics) but a little searching got me here:",
"http://en.wikipedia.org/wiki/Axial_tilt#Long_period_variations",
"This section seems to answer your question somewhat. "
] | [
"It does. Thank you."
] |
[
"Are any objects black across the entire EM spectrum?"
] | [
false
] | You have objects like coal or asphalt that are black in the visible light spectrum, and things like sunscreen that are "black" in the UV spectrum. Are any objects or materials black across all spectrums? If not, what sorts of things have the highest coverage? | [
"It's difficult to find very-wide-range spectra for substances, because no instrument covers the whole range from gamma rays to radio waves. But carbon black (easily made by holding a piece of metal in a candle flame is pretty damn near pitch black from the ultraviolet through the near infrared. It should also be... | [
"Pretty much everything else appears in some form as they have a temperature and therefore a radiance. ",
"Everything that absorbs radiation will also emit radiation. This ",
" to absorb it. A perfect black-body, an object that absorbs all incoming radiation, will emit the most radiation possible as thermal rad... | [
"Haven’t quite looked into Hawking Radiation yet so apologies and thanks for the info! "
] |
[
"Cumulative Distributions: tool for business?"
] | [
false
] | In my work, I am often presented with claims of the following sort, which are intended to influence me: “50% of our customers account for over 80% of our sales!” I resist this influence, because the economist in me appreciates this as potentially nothing more than a natural feature of a “normal” distribution, and not r... | [
"You have the right idea - you want to plot the ",
"cumulative distribution function",
" (CDF). However, for this to work, you will need \"X% of customer accounts for Y% of sales\" for the range of (X,Y) you're interested in. Having only one of these statements will only give you a single point. We all know ... | [
"Thanks, but believe it or not, I gathered this from your earlier point about this being an empirical distribution, rather than one with an underlying shape. That is, I think if I assumed that the underlying distribution must be Normal, for example, given these properties, I might be able to come up with some sort... | [
"Thanks, this is great! A very clear and concise explanation of how I ought to think about it, even though I don't have enough info to get me there. "
] |
[
"Does a cancerous cell still does it job as a cell i.e would a cancerous kidney cell still filter blood?"
] | [
false
] | null | [
"Sometimes. Cancer cells are generally bad at their jobs.",
"Melanocytes make melanin, a pigment that gives skin color. Most melanomas are dark-colored from overactive melanocytes that are still doing their job, albeit in a disorganized out-of-control fashion.",
"Some melanomas are depigmented. These look more ... | [
"This is the best answer. Cells that sort of do their job are termed well differentiated (they are different from other cells because they do something specific) and are frequently less aggressive (because they are less dissimilar to normal cells).",
"Poorly differentiated cells do very little that cells of their... | [
"Usually not. Cancerous cells do not mature as normal cells do. In early stages, it sometimes appears as dysplasia. ",
"Cancer cells are usually derived from progenitor cells ('stem cells' which are slightly more specific) required for tissue renewal. Occasionally, one will undergo mutations which allow it to ev... |
[
"How and why does the human body develop a tolerance for drugs and/or alcohol? Do other species do this?"
] | [
false
] | null | [
"The reason is different for every type of drug. For alcohol, the body starts producing more of the enzyme that breaks alcohol down so as to remove the poison more quickly; for opiates, the brain starts to reduce it's own production of related neurotransmitters to adjust for the over-activity from the drugs; and s... | [
"And to answer the second half of his question, yes, the same thing happens in other species. The vast majority of our enzymes are found in the same or very similar form in other animals."
] | [
"Just an interesting note, the human body also develops a tolerance to context. For example, if a heroine user always shoots up in the same place, his/her body compensates for the context of the place. The body becomes conditioned to the place that the drug is usually taken. The body strives for homeostasis and rea... |
[
"Do frequent small earthquakes decrease or increase the chance of a bigger earthquake?"
] | [
false
] | I live in LA and there has been 2 mild earthquakes in the last 2 weeks. | [
"You have to keep in mind that even if small earthquakes decrease the chance of a bigger earthquake you'll most likely still need a lot of them to make an impact. Try the ",
"calculator provided by the USGS",
". If you input earthquakes with magnitudes 7 and 5 in the boxes you'll see that a 7 is 100 times ",
... | [
"This is true. However, strain can also be released aseismically. According to this paper in Geophysical Research Letters:",
"Aseismic slip and fault-normal strain along the central creeping section of the San Andreas fault",
"Up to 32mm/yr of creep along a 170km section of the San Andreas fault is accommodat... | [
"Another geology type person here. This comment is right. Yes a small earthquake releases energy, but it can also transfer strain onto another part of the fault or another fault system. \nSo you can dissipate the energy of a large earthquake with several small ones, however a small one can load more energy elsewher... |
[
"Where does the energy go when particle-antiparticle pairs spontaneously appear and annihilate?"
] | [
false
] | Still trying to wrap my head around Hawking Radiation, but I was wondering about those particle-antiparticle pairs that are spontaneously appearing. If they appear and annihilate (elsewhere in space, not related to black holes), wouldn't that release energy? I thought energy could not be created, but wouldn't the annih... | [
"The energy doesn't go anywhere, because there was zero energy to begin with and zero energy after.",
"The particle-antiparticle pairs you're referring to are called ",
". They aren't real particles, and they don't actually exist. They're mathematical tools that are used in calculations, but they fail to have m... | [
"So this story about virtual particle paris spontaneously appearing and annihilating each other is not real? What is actually happening then that this story needs to be told? How does Hawking Radiation work? What about the Casimir effect? Is that related?"
] | [
"Physicist here. I'm going to disagree that virtual particles are just a mathematical tool. Scientifically, if you have a model with players in it like these virtual particles, and it is the only model that gives strong agreement with experiment, then it is customarily the scientific stance that the model is presum... |
[
"How, on a physical level, do transistors/vacuum tubes work, and how do they produce logic gates?"
] | [
false
] | [deleted] | [
"Electrons are charged particles, and in a vacuum tube, they are the only particles available to move. If there is a positively charged plate, the negative electrons will move towards the plate, the electron movement is called current. the Tube is now conducting. ",
"If the plate is then charged negatively, the n... | [
"This diagram might be helpful: ",
"https://www.elprocus.com/wp-content/uploads/2012/09/MOSFET-BLOCK-DIAGRAM.png",
"Essentially, when a voltage is applied to the gate of a transistor, an electrical path is cleared for electrons in the substrate below the gate, allowing current flow between the source and drain ... | [
"While on the right track 'attracting negatively charged electrons' you're closer to describing accumulation mode. NMOS transistors operate by inversion - pushing positive charges away. The actual charges available come from the source. Wikipedia does an ok job Showing. This is a difficult topic for me, and I have... |
[
"Does the tissue from a transplant retain the DNA of the donor or change to that of the host?"
] | [
false
] | I was thinking about this the other day and my girlfriend and I were arguing about it. When, for example an organ such as a heart or a kidney is transplanted into a host, will a biopsy of the cells after some time show cells with the host's DNA or the donor's DNA? Related, are the cells that replace the cells in the or... | [
"There are some exceptions of tiny fractions of cells, but by and large, the organs remain the donor's DNA. There's some evidence that recipient cells can (at very low frequencies) also contribute to the new organ. Renewal of the organ typically comes from the donor cells, not from the recipient. That's why pati... | [
"They are different. Typically people don't receive whole blood anymore, only the plasma or red blood cell fractions, which contain no DNA and no replicating cells. Red blood cells aren't really cells per se, but more like sacks of hemoglobin. ",
"In cases where people do get whole blood, the donor DNA persist... | [
"what about blood transfusions?"
] |
[
"A question from my five year old: \"How does a seed know to start growing when it is planted instead of in the seed packet?\" I was explaining well enough, but couldn't answer exactly what triggers the process."
] | [
false
] | null | [
"Not a complete expert on this, but the topic you want is ",
"seed germination",
". The dominant factor is water, I believe you can actually germinate a lot of seeds in a cup of pure water. Some species care more about other factors, like temperature and light. You could try doing an experiment with your child ... | [
"Noting the previous answers of water, there is also a question of light. Specifically seeds have what's known as Phytochrome which is a light-sensitive. Germination will still take place in the absence of water - the seed has enough 'food' within it to establish a root before it takes in water from the surroundi... | [
"Yeah, in the case of domesticated crops, moisture, and to an extent, temperature, is going to be the main factor. I could go on for way to long on this...Something that might be fun would be to fold a paper towel, get it wet, layout some seeds on it (lima beans, or some other large-seeded plant are better for the ... |
[
"If super novas can be brighter and more powerful than other supernovas, how exactly is it that they can act as \"standard candles\" for gauging distance and such?"
] | [
false
] | Came across this video describing a supernova that was recorded as being 10 times bigger and 500 times brighter than any previously known supernova. I always heard that we use supernovas to gauge distances as they can act as "standard candles" when charting the universe and our galaxy. But if supernovas can vary in bri... | [
"The short answer is that there are different types of supernova. The type Ia supernovae are the kind used as standard candles. They only come from very particular circumstances: binary stars where a white dwarf is absorbing matter from its pair. It's actually not derived from a core collapse, unlike other phenomen... | [
"Consider the following:\nThere are different types of supernovae (SNe). While there have been attempts to use a variety of them to measure distances, only those of spectral type Ia are considered reliable standard candles. These SNe show a characteristic light curve, no hydrogen lines and an overabundance of silic... | [
"Yes! Cepheids and RR Lyraes are two types of variable stars with known physics whose inherent brightness can be determined. Cepheids' brightness can be known by the rate at which they pulse, and RR Lyraes all have the same brightness (from what I remember)."
] |
[
"Does a burnt out light bulb consume power?"
] | [
false
] | Let's say you have a lightbulb in a lamp. You turn the lamp on, but the light bulb is burnt out (for whatever reason a lightbulb burns out), does energy still get consumed? | [
"I'm assuming you are talking about a tungsten filament light bulb. The answer is no.",
"This is because tungsten filament completes the circuit between a positive and negative lead (bear with me AC people). If the light bulb burns out, its caused by the tungsten filament breaking. If the tungsten filament is ... | [
"It depends what type of light bulb you are using. For an incandescent, the answer is a completely negligible amount. The break in the filament will have a very high resistance, so very little current will flow at all.",
"Fluorescent lamps, on the other hand, have some form of starter. This might be a heated anod... | [
"It produces heat, so there is definitely power being consumed."
] |
[
"Do you accelerate when moving north/south?"
] | [
false
] | I might come off as a bit stupid for asking this question, but intuitively I can't help but tell myself that it makes sense. For instance: I live in the northern hemisphere. When moving southward, shouldn't I technically be accelerating eastward? As I move closer towards earths axis of rotation (equator), my perpendicu... | [
"If you travel North in the northern hemisphere coriolis acceleration will try to push you East. You will therefore need to lean left very slightly to counteract it.",
"Think of a ball on a string being swung round in a circle. As you walk North you are moving closer to the Earth's axis. This is similar to the st... | [
"I'm sure the force would be incredibly insignificant (when it comes to actually 'feeling' it), although I wonder whether it would be relevant at much higher velocities?",
"To address this point, you can quite easily calculate the coriolis acceleration yourself. But the ",
" is that the only system you will com... | [
"Rossby Number is given by ",
"u/fL",
" (where again, u is the velocity, f is the coriolis parameter and L is the length scale of motion) and if the Rossby number is much greater than 1, the coriolis acceleration is not important.",
"Thinking about the convective flow of solid rock in the mantle... it seems l... |
[
"Does salt change the surface tension of water?"
] | [
false
] | Sea water Vs. spring water | [
"Yes, it increases it by 1.64 units per molar concentration. Average ocean seawater is about 0.6 Molar NaCl.",
"This table shows the increase for various other salts in solution.",
"http://www.kayelaby.npl.co.uk/general_physics/2_2/2_2_5.html",
"Look near the bottom of the page for the table headed \"Surface ... | [
"Yes, it causes an increase in surface tension due to a negative surface excess.",
"In more detail: the charged ions don't accumulate at the air-water interface due to an image charge at the interface. This means that creating more interface is unfavourable, as creating new interface would require moving the ions... | [
"Are you actually referring to surface tension, or are you taking about density (aka why can you float in the see but not the pool). ",
"The salt dissociates in water and the ions disrupt the normal packing of water molecules. They actually cause the water molecules to pack more tightly due to the water's attract... |
[
"Can the yield strength be greater than the ultimate tensile strength for some materials ?"
] | [
false
] | So I am studying materials engineering and came to think if ait is possible or exists a material that have a yield higher than it's ultimate tensile strength according to an . I know that the true curve will always show that strength increases along the curve due to strain hardening effect. | [
"When a material reaches its ultimate stress it will break, which makes it impossible to talk about a material having anything beyond that point. I don't believe that looking at the engineering stress-strain curve changes this fact.",
"What does exist are materials that do not yield (or yield very little) before ... | [
"I searched into the subject and found out some polymers can have a UTS lower than their yield on an engineering stress strain curve due to necking right after the yield."
] | [
"Or is their yield the same as their UTS ?"
] |
[
"Can you harness energy from sound?"
] | [
false
] | null | [
"Sure. Imagine a passive microphone or speaker. A sound wave strikes the speaker membrane, and causes it to move. The back of the membrane has a permanent magnet attached to it. The membrane casing has many coils of wire running through it. Once the magnet is moving, then you're creating ",
"electromagnetic ... | [
"You can, for example using piezoelectric materials.",
"However, a method to do that sufficiently efficient (both in terms of energy yield and cost) to have real world applications has yet to be found.",
"http://www.sciencedaily.com/releases/2008/12/081201162127.htm"
] | [
"I sat in an interesting seminar by a micro fluidics researcher that showed how piezo electric device can be used in \"lab on a chip\" devices to separate and identify bio molecules indicative of certain infections or illnesses. It was really interesting and he had a video of the stream of a sample of blood in a pr... |
[
"Can we use our own poop to make methane-biofuel?"
] | [
false
] | That would make things super efficient. Thanks for telling me I'm an idiot in the following comments. | [
"We can, and to an increasing extent, ",
" doing so. Search for 'biogas'."
] | [
"No, most plants just vent it. It takes a relatively large and purpose-built plant to make it economically feasible to collect and sell the gas."
] | [
"Searching \"Biogas\" will help you out, but I can give you a quick run down of the process of biogas, methane (CH4) production. Methane is generated by ",
"methanogenic",
" (methane generating ",
"archaea",
"). Methanogens utilize the products of ",
"fermentation",
" ,principally hydrogen gas and carbo... |
[
"WIMPs, how do they work?"
] | [
false
] | How do WIMPs work? I read that they are comprised of both matter and antimatter. How can that be, and how would it be formed naturally if it's constantly obliterating itself whenever it touches another WIMP? | [
"No, you were misinformed if you were told they were made of matter and antimatter. ",
"WIMPs are matter but a form of matter that interacts due to gravity (and the weak force) but not due to other forces. We thus distinguish it from normal matter - the stuff of planets, stars gas clouds, etc - which interacts du... | [
"WIMPs are matter but a form of matter that interacts due to gravity but not due to other forces. ",
"Surely WIMPs, by definition, also interact with the weak nuclear force."
] | [
"Yes. Facepalm. Idiocy on my part."
] |
[
"If all electrical activity in the brain ceases, even for a second, can the brain \"start\" again? Or is the person effectively dead?"
] | [
false
] | null | [
"All electrical activity could stop for some period of time and a person would not die. The first things to kill them would be heart/lung failure, because neurons in the medulla control these organs. The cessation of electrical activity (firing of neurons) would not be the ",
" cause of death.",
"Information in... | [
"That is a truly fascinating question, and actually the basis of an inside joke that I started in my lab :) ",
"Because of course, your consciousness is just as profoundly interrupted when you go to sleep! ",
"Is it the case that every time you go to sleep, ",
" die and a pretty-much exact copy of you (who is... | [
"This is a good, basic response, but your question has interesting neuro-philosophical questions about consciousness that run in parallel with it. Namely, with the understanding that consciousness arises in the brain, what would happen if a person were brought back from the dead after having all electric activity i... |
[
"Why have so many more planets been discovered in 2014 compared to past years?"
] | [
false
] | [deleted] | [
"You're talking about ",
"this graph",
". And there wasn't any particularly huge breakthrough, it was sort of an issue of semantics.",
"In short: the Kepler telescope team has a planet detection pipeline that searches the data for planets. The pipeline has found on the order of 4000 'planet candidates' so far... | [
"Well at 5 sigma, you'd expect about 1 in 2 million planets to actually be false positives that somehow managed to pass your tests anyway. Since that number is much higher than the total number of planets found, we can say with pretty high confidence we're sure that they're all planets.",
"At 3 sigma, it's about ... | [
"Case closed! Thanks so much for your informative answer. "
] |
[
"Why do hotspots form distinct volcanoes?"
] | [
false
] | Pretty self explanatory - why do hotspots form separate, distinct large volcanoes rather than a continuous stream of smaller mini- volcanoes that form a ridge if the hotspot is constantly extruding magma? (Yes im aware a hotspot doesnt actually extrude magma, just couldnt find a better way to put it) | [
"There are a few things to consider. First, is that if we look trails of volcanoes formed by hotspots, in many cases they do form (at least in small parts) things like ridges, e.g. if we used the classic ",
"Hawaiian-Emperor seamount chain",
" as an example and consider the bathymetry, we can see sections where... | [
"There's a self-reinforcing feedback at work. As the hot spot heats the overlying crust, the crust partially melts, creating a porous region that melt can rise through. The hot melt follows the \"path of least resistance\", and as it rises it delivers more heat along that path, melting it further and creating a m... | [
"It is like having a blow torch and a metal sheet if you slowly and erratically move the metal sheet you will get random holes in the sheet where the torch was there long enough to completely melt the sheet to create a hole."
] |
[
"If you were traveling at a supersonic speed towards a sound source, would the sound appear to be going in fast-forward?"
] | [
false
] | null | [
"Yes, this is a product of the Doppler shift. You know, the \"ambulance siren has a higher pitch when it's approaching you, and a lower pitch after it passes?\" Same thing, only now the ambulance is stationary, and you're moving. ",
"The equation is pretty simple in theory, ",
"f_obs = f_source (v_sound ± v_obs... | [
"And, perhaps even more amusingly, if you're moving away from the concert at Mach 2, you'll actually hear the song in reverse, Satanic messages and all.",
"This needs to be clarified. If they were playing the song before you started passing them, you'll be catching up to the previously emitted sound waves, and by... | [
"And, perhaps even more amusingly, if you're moving ",
" from the concert at Mach 2, you'll actually hear the song in reverse, Satanic messages and all."
] |
[
"Doesn't the idea of spontaneous creation go against the laws of thermodynamics?"
] | [
false
] | "Because there is a law such as gravity, the Universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the Universe exists, why we exist. It is not necessary to invoke God to ... set the Universe going," - Stephen Hawking That doesn't seem right to ... | [
"I think what Hawking means is that our universe obeys a rule by which energy causes measurements of distance and time to change, and those measurements of distance and time cause energy to flow in a certain way. That system will spontaneously evolve from a high energy density state into our present state. And it d... | [
"But gravity did?"
] | [
"Because thermodynamics is a statistical science applicable to closed systems with conservation laws."
] |
[
"Is there any possibilities of having non-spherical planets out there?"
] | [
false
] | null | [
"We live on a not-exactly-spherical planet",
". The earth is spinning, which has squeezed it slightly, into an oblate spheroid. It is possible that there are planets that are spinning faster and are flatter.",
"However, one of the defining features of a planet is that it is so massive its own gravity has pulled... | [
"It would if the material strength of whatever it was made out of was not strong enough to withstand it's own gravitational force. ",
"However, I would think a civilization advanced enough to make an Earth sized cube-planet, would also be advanced enough to make it out of something that stays a cube."
] | [
"What if some advanced group was able to create am Earth sized cube. Would it's gravity eventually pull it into a \"sphere\""
] |
[
"Is there any difference in later life between people born by C sections, or Natural births?"
] | [
false
] | For example do people born naturally live longer, or have less chance of disability? | [
"Children born by c-section are slightly more likely to be hospitalized for infection, up to age 5. Not sure if this was studied for other causes of morbidity, or to older children or adults.",
"https://obgyn.onlinelibrary.wiley.com/doi/epdf/10.1111/aogs.13371"
] | [
"There is a fair amount of research linking C section births to increased allergic sensitivity. The womb is a sterile environment, but vaginal birth exposes the child to vaginal microbes that (along with microbes on the mothers skin picked up after birth) quickly establish an infants initial microbiota. There are d... | [
"Do children who are born naturally get a stronger immune system from all the waste they encounter on the way down?"
] |
[
"What is a zero-gap metal?"
] | [
false
] | I am doing a research paper on carbon nanotubes for a physics class and Wiki says that a multi-walled CNT will behave like a zero gap metal since the inter-layer distances of individual CNTs is approximately the same as the gap distance between layers of graphene in graphite (since a MWCNT is just rolled up graphite an... | [
"I think 'zero gap' refers to the ",
"band-gap",
" being very small. This means there is no gap (difference in energy) between the valence electron band and the conduction electron band. As a result, the material (MWCNTs) should conduct electricity very well."
] | [
"Nanotubes are very much like graphene or graphite, but the fact that they're rolled up means they have different (periodic) boundary conditions. While graphene and graphite are zero bandgap materials, sometimes nanotubes DO have finite bandgaps because of these boundary conditions -- it depends on the way they're... | [
"To elaborate a bit, for insulators there is a large band gap: it requires a lot of energy to get an electron to delocalize from an atom. For semiconductors, the gap is small: electrons can be easily forced over it. For metals, the valence and conduction bands are sort of smeared together and electrons move freely.... |
[
"Why does being infected with vaccinia virus vaccine protect you from Smallpox but doesn't protect you from other \"pox\" such as chicken pox?"
] | [
false
] | Due to my career field I was recently given the vaccinia virus because I was told it's a more "mild" form of small pox, this peaked my interest and I learned the difference between vaccinia and variola virus(small pox) but could not find an answer to my question in regards to the varicella virus (chicken pox). I probab... | [
"Chickenpox is caused by the varicella zoster virus and smallpox by the variola viruses. Vaccina and variola are poxviruses, varicella zoster virus is not - so it is not surprising that vaccina immunization will not confer any immunity to chickenpox.",
"\"Pox\" is an old term dating from the time before we had ... | [
"So the old insult of \"pox on your family\" was just a curse in the literal sense of wishing highly infectious skin lesion causing disease upon another and not any specific disease?"
] | [
"Quoting online etymology dictionary:",
"pock (n.) Old English pocc \"pustule, blister, ulcer,\" from Proto-Germanic *puh(h)- \"to swell up, blow up\" (source also of Middle Dutch pocke, Dutch pok, East Frisian pok, Low German poche, dialectal German Pfoche), from PIE root *beu- \"to swell, to blow\" (see bull (... |
[
"How do waves differ from our dimension in the 2nd and 4th dimensions."
] | [
false
] | null | [
"Care to elaborate a little?"
] | [
"We don't exist in three dimensions. We exist in four: three of space and one of time. The four dimensions are just numbers that act as coordinates to describe the position of something in spacetime. That's all there is to dimensions. Therefore, electromagnetic radiation also exists in four-coordinate spacetime... | [
"There's actually more to it than just that. Mathematically, we represent electromagnetic fields by a tensor-valued function. The tensor aspect means that to specify the electromagnetic field in one point of space-time, you need to specify 16 numbers (although because of antisymmetry of the tensor and other reasons... |
[
"What is the theoretical limit of CPU speed?"
] | [
false
] | When it comes to speed we say speed of light is the limit. In similar fashion what would be the maximum of speed of a CPU if only restricted by speed of light? What would be the maximum FPS a video camera can capture pictures? | [
"The maximum computational power of a computer which is self contained is Bremermann's limit and is about 1.36 × 10",
" bits per second per kilogram of computer."
] | [
"No, pretty much every generation of cpu I've seen has a had at least a slightly higher clock speed, even the most recent ones."
] | [
"I'd like to know what our current best cpus come out at in these units."
] |
[
"Do goosebumps appear in the same location every time?"
] | [
false
] | Say you are cold and have goosebumps on your arms. The next time you get goosebumps on your arms will the individual ‘bumps’ be in exactly the same place? | [
"Goose bumps are formed when a tiny muscle at the base of your body hairs contracts.",
"This means that the bumps will appear in very similar places every time. It probably wouldn’t be the exact same every time because there’s no guaranteeing that every muscle will be contracted every time. It will probably be ve... | [
"And what that muscle is for is raising your body hair to better protect against cold, or to make you look bigger in a conflict situation. It's just that our hair is no longer very useful for either purpose."
] | [
"yes they form where the papilla is under the skin which is a small muscle that will pull the hair up. The patterns may change after a few years if the regeneration changes the position slightly and there may be different pattern of hair recruitments but you can't have goosebumps where there is no hair follicle. th... |
[
"This may be a stupid question, but what defines GMO. Is it simply changing a plant through cross pollinating (at its simplest level) such as Mendel, or does GMO mean laboratory tested and genetically altered through a laboratory?"
] | [
false
] | null | [
"You can read some of the history of it here: ",
"https://www.fda.gov/downloads/Food/IngredientsPackagingLabeling/GEPlants/UCM537311.pdf",
"In brief, it's a bit of an arbitrary semantics issue. As far as United States government agencies are concerned, all \"traditional\" techniques for altering a species are n... | [
"Here's the Canadian definitions:",
"Genetically Modified:",
"An organism, such as a plant, animal or bacterium, is considered genetically modified if its genetic material has been altered through any method, including conventional breeding. A \"GMO\" is a genetically modified organism.",
"Genetically Enginee... | [
"So essentially all modern crops are GMOs by that definition. Nice. Keeps it simple. "
] |
[
"Why do many poisonous household substances advise that you should not induce vomiting if you accidentally consume them?"
] | [
false
] | I've noticed that most bottles marked poisonous around the house advise that "if accidentally consumed, do NOT induce vomiting." Why is this the case? It seems to me that if you unintentionally swallowed drain cleaner, you'd want to get it out of your system as quickly as possible! On the other hand, are there any comm... | [
"It turns out there are very few situations when inducing vomiting would be indicated. The American Academy of Pediatrics no longer recommends that syrup of ipecac be kept in the home, and says that any you have should be disposed of. If emptying the stomach is needed, it will be done in the emergency room.",
"Ma... | [
"Might be worth mentioning. In cases like this, if at all possible, make sure the container to whatever was ingested travels with the patient to the ER so that the medical staff can see exactly what is in it. "
] | [
"The advice to drink milk is not applicable in all cases.",
"If a person has ingested poison, ",
" give them anything else by mouth unless instructed to do so by Poison Control, EMS, or another medical professional.",
"Always call Poison Control first. They may even advise you not to drive to the ER, but to s... |
[
"How can open source encryption software actually keep information safe?"
] | [
false
] | If a piece of software is open source, then the encryption method must be known. Would it not be much easier to crack the encryption? | [
"Knowing ",
" a lock works, doesn't automatically give you the key.",
"For example, if a safe maker describes the ",
" inner workings of a safe, that might convince both buyers and safe crackers that its security is solid and not possible/easy to bypass using common safe-cracking techniques. ",
", explainin... | [
"Fundamentally, software is math. And there are some mathematical operations which are much easier in one direction than in the inverse direction. For instance, finding a derivative f' given f is often much, much easier than finding the antiderivative f given f'. ",
"Similarly, factoring is easy in one direction,... | [
"You might know tons about combination locks, but that doesn't mean you have the combination, you'll still have to try each one. Similarly, knowing things about RSA or another encryption scheme doesn't help as much as you'd think."
] |
[
"Why do some birds hop while other birds walk?"
] | [
false
] | [deleted] | [
"A ",
"Stanford essay/paper",
" (not sure? It's from the 80s) stated this:\n\"When unconstrained by such a narrow perch [previously discussing a telephone wire], many birds walk or run using the alternating strides typical of most bipeds. Others, particularly small, arboreally inclined species, commonly hop. It... | [
" layman here. Since there are no answers yet, I thought I might offer at least something.",
"This article is relevant: ",
"http://www.reinhold-necker.de/seite10.html",
"Going by the reasoning presented on that page, one explanation would be that a) walking while head-bobbing, and b) hopping, are two differen... | [
"I have anecdotal evidence that playing Pokemon as a kid makes you more likely to add the 'd'. The \"Pidgey\" effect."
] |
[
"Why does heat excite atoms?"
] | [
false
] | So when a substance is heated, say water, its molecules gain energy. The molecules can gain enough energy to change state. But why does heat push the molecules' electrons to other orbits? I know of the Arrhenius equation and the like but why does heat do this? | [
"Well, 'heat' is really all forms of energy in the matter. (Usually subdivided into translational kinetic energy, rotational/vibrational kinetic energy and the electronic energy, although others exist) At 'ordinary' (below a few hundred C) temperatures and with most substances, the electronic states aren't involved... | [
"But why does heat make things move faster?"
] | [
"That question makes no sense. What exactly is it that you think 'heat' is?"
] |
[
"'Super-Earth' and 'Super-Jupiter' are terms I've read to describe exoplanets. What would a planet the size of Saturn be called?"
] | [
false
] | [deleted] | [
"To answer your specific question, people will refer to a \"Saturn-sized planet\" or the like, but you don't hear of a broad class of \"exo-Saturns\" mainly because it would be cumbersome to have so many subcategories in common use. Saturn is a gas giant, and so is Jupiter. Why bother with extra categorization when... | [
"There is also the \"hot Neptune\" category."
] | [
"A gas giant"
] |
[
"How are bodies identified through dental records?"
] | [
false
] | To me if you haven't had anything done to your them, teeth seem quite uniform; how are they different enough to be used to identity bodies? | [
"Having the dental records is, of course, key. If they don't exist, or the police can't locate them, there is nothing to match against.",
"But, if somebody dies in a fire or some-such, and the police are able to find dental records for the person they assume the body is, they can take X-rays of the teeth and com... | [
"Thank you, are teeth that different from person to person that there's never multiple possible identities?"
] | [
"How about date discrepancies? If dental records pre-date considerable dental work like implants or extractions, is it safe to assume that dental records may be different enough to not match?"
] |
[
"Are there viruses that you don't become immune to after recovering?"
] | [
false
] | [deleted] | [
"Are there viruses that you don't become immune to after recovering?",
"Yes. But the vast majority of viruses do produce an immune response. With some you lose immunity after a few months and others it last your entire life.",
"How common are they? ",
"Not very common like 97% of viruses has immunity response... | [
"It should be mentioned that “no evidence of immunity” doesn’t mean that people are or aren’t immune. It just means that they don’t have concrete scientific data proving immunity or not. Basically they’re just still figuring it out.",
"Edit: and iirc, humans can become immune to most other corona viruses, so it ... | [
"If you recovered on your own then you have immunity. Otherwise, you wouldn't have recovered. How long that immunity lasts depends. For most viruses immunity is going to exist, to some extent, for longer than 6 months. Some viruses mutate quickly, like the flu; this is why people need a new shot every year. For the... |
[
"Why does 9 degrees celcius feel warm in the winter but feels cold in the summer."
] | [
false
] | And please don't just say "It feels colder in comparison" because I know. There has to be some physiological response, and that's what I'm interested in. Thanks! | [
"You have several types of nerves in your skin. The ones for heat can become desensitized. When you take showers, you may have to turn up the heat of the water at some point. This is because your nerves became acclimated to the hotter than usual temp.",
"\nThis is what happens in the summer. Your skin gets used t... | [
"I am guessing wind chill plays a roll in that."
] | [
"Same things happens with other sense too, such as scent, hearing, and proprioception."
] |
[
"How different are we physiologically from humans ten thousand years ago?"
] | [
false
] | Do we have roughly the same intellectual capacity? | [
"By 8000 BC, people were already spread out across the globe. People were living in Central America.",
"You can take descendants of those people from Central America and they can have children with people from Southern Africa whose ancestors never left that region since the dawn of mankind.",
"Those children ca... | [
"I'm sorry, what? Do you have citations for any of this? Especially:",
"most anthropologists agree that human intelligence is on the decline"
] | [
"I'm sorry, what? Do you have citations for any of this? Especially:",
"most anthropologists agree that human intelligence is on the decline"
] |
[
"Is it (theoretically) possible to create a spacecraft with artificial gravity that does not rely on the craft itself spinning to generate it?"
] | [
false
] | null | [
"The most feasible \"artificial gravity\" method is having the ship slowly accelerate up to it's top speed, turn it around, and slowly decelerate back to rest. This would have the exact same effect as gravity does and could be done with today's technology."
] | [
"No, by turn around he means turning the face of the ship around so that the rockets burn in the opposite direction for deceleration as you go to the target. If you constantly accelerate at 1G, you would have to decelerate at 1G halfway through the trip anyway in order to slow down enough not to pass your target."... | [
"Oh, I obviously read that wrong. Yeah that does make sense, but that still wouldn't work for a standing or idle state. That's more what I was questioning, the consistent generating of uniform gravity at all speeds."
] |
[
"Was the super massive black hole at the center of the Milkyway ever anything else?"
] | [
false
] | null | [
"The origin of the super-massive black hole at the centre of the Milky Way (and most but not all other galaxies) is still a bit of a mystery.",
"Clearly, the general ingredients are there: typically galaxies are much denser in the middle (even without the supermassive black hole), and if you have enough stuff in ... | [
"I will point out that there are theories there used to be Supermassive Stars of over 100,000 solar masses that directly collapsed into a Black Hole.",
"EDIT some links:",
"https://astrobites.org/2014/03/21/a-new-way-to-die-what-happens-to-supermassive-stars/",
"You can Google \"super massive stars\" and find... | [
"Was this because the original, progenitor stars were zero-metallicity and just largely composed of hydrogen and some helium?",
"I think I remember reading that it takes a lot more pure hydrogen to collapse into a star than when there are metals involved, so the original stars were much larger and short-lived. ",... |
[
"How does the body make more blood after you finish bleeding?"
] | [
false
] | As somebody who gets a lot of bad nosebleeds, especially during the winter, I've lost a lot of blood this way, and I've always wondered how more blood gets made once the bleeding stops | [
"Blood cells mainly are made by cells in the bone marrow, in the middle of your long bones (like your arm and legs). There, you have a large \"bank\" of stem cells which are always dividing to make red cells, whitening cells and platelets. This process is pretty constant, but if you have a sudden loss of blood, lik... | [
"Our red blood cells are constantly dying and are replaced at a steady rate by the blood cell producing tissue in our bone marrow. We make about 10",
" new red blood cells a day. If you lose a larger amount of blood, say from a wound or from donating, your kidneys detect this and release a hormone called erythrop... | [
"Hematopoietic stem cells in your bone marrow differentiate into myeloid and lymphoid progenitors. Myeloid progenitors differentiate into monocytes, granulocytes, megakaryocytes, and **erythrocytes**. Immature erythrocytes enucleate and complete their differentiation into mature red blood cells. This constantly hap... |
[
"Do astronauts experiencing weightlessness feel like they're falling?"
] | [
false
] | [deleted] | [
"Right, the experience you're probably imagining is the a combination of feeling weightless and feeling the air rush past and into you. The astronauts obviously only feel the first of those two. ",
"Weightlessness and freefall aren't merely related. They're the same thing. "
] | [
"If you mean to ask \"would my stomach by lurching the same way as it does during the few seconds of a skydive\", then yes, yes it will. The training aircraft used to get people used to \"zero-g\" operations is not called the \"Vomit comet\" for no reason.",
"http://en.wikipedia.org/wiki/Reduced_gravity_aircraft... | [
"Yes, that is exactly what they are doing. They are falling in such a way that they miss the ground and keep falling in a circle."
] |
[
"Is there a maximum energy of a photon?"
] | [
false
] | I've done a bit of googling, and found that as a photon's wavelength approaches a Plank Length, quantum gravitational effects need to be taken into account, and we have no way of understanding these at the moment. So does this mean that we are currently unaware a) whether there is a limit and/or b) what happens to a ph... | [
"While a theory of quantum gravity is not well-understood, I believe it is pretty much fully accepted that a photon with a Plank-length wavelength would be so energetic that it would ",
"create a black hole",
", so yes, this sets a limit on the energy of a photon."
] | [
"While your assumptions and other things that are being said here may be correct, it is important to remember that the Standard Model is only an effective theory that cannot be assumed to be correct in energy regions that are well outside the what has been explored experimentally so far. Anything involving the plan... | [
"Thanks for the link"
] |
[
"Why Exactly is it so Computationally Expensive to Calculate the Shape of Proteins as they Fold?"
] | [
false
] | I have a Bachelor's in Computer Science. I was having a conversation with a Ph.D. Paleontology friend today about computational modelling of how genotype relates to phenotype, and using those models as a way to predict what evolutionary changes (for instance, drug resistance) might be possible for a given species. My f... | [
"I work with protein modeling systems for drug design and protein structure prediction. If you want the detailed math, the computational dilemmas and ",
"supercomputer build structure",
", we are going to have to wait for a computational person to chime in, but I can break down the system for you to give you an... | [
"Well, the problem is in some sense, NP-hard: ",
"PDF link",
"."
] | [
"My p-chem professor discussed a similar topic except it had to do with determining the products and energies of a relatively simple chemical reaction. To model this you would use a simplified equation because the actual equation had something like 200 factorial mathematical elements. A protein can contain thousand... |
[
"Could small arms ammo and batteries be affected by a \"strong\" enough EMP?"
] | [
false
] | If telegraph lines once were "fried" by such, would it be reasonable to conclude that primers in small arms ammo could be "set off" by a strong enough emp? Have no idea about the batteries, just thought I'd throw that in, too. | [
"I cannot speak of the effects of an EMP on a battery, but the effects on small arms ammo would be insignificant. Ammo is discharged by physically striking the primer at the rear of the cartridge, which then (via chemical reaction as a result of the shock of impact) detonates to ignite the smokeless powder (modern ... | [
"My numbers are way off. I meant to say a microwave is 700 W, not 700 MW, and then went on writing an explanation based on 700 kW for some reason. 700 W/0.1m",
" gives 7 kW/m",
" That's a factor 0f 1000 less than the EMP. Though this is short lived, 1000 ns, so i still doubt the ability to destroy ammo or batte... | [
"Pardon my speculation, but I thought I'd share how a battery might be affected...explaining how unlikely it actually would be affected.",
"The battery requires a path of finite resistance between its terminals to provide energy from its internal chemical reaction, so unless the EMP somehow changes the conductivi... |
[
"Does fluorescence have to involve UV light?"
] | [
false
] | I'm doing some work regarding fluorescent microscopes and for some reason I cannot get a point to make sense to me. I get the principle of fluorescence: high-energy (short wavelength) light is absorbed by a molecule and re-emitted as lower-energy (longer wavelength, visible) light. I work in microbiology and we use flu... | [
"Is it because fluorescence doesn't need to be strictly UV, which perhaps is too arbitrary to form a clear distinction?",
"There are fluorescent dyes that can be excited by visible light, and even ",
"near-infrared fluorescent dyes",
" for medical imaging. ",
"Part of the point of your specific mildly toxic... | [
"Most likely, the light source your microscope uses emits a broad range of light, including into the dangerous UV sections. The microscope uses filters to remove all those other wavelengths down to the just the 470 nm wavelength you're describing here, which is actually used. However, the presence of that light sou... | [
"No, fluorescence does not need to involve UV. ",
"What fluorescence involves is:",
"A material with a large gap between two groups of energy levels. That is, there's a group of ground energy states an electron can occupy. Then there is a gap in energy that an electron cannot occupy. At at a higher energy than ... |
[
"What are the real risks of occasional cigar/pipe smoking?"
] | [
false
] | Up front: I'm an occasional smoker (strictly cigars and pipes, no inhalation except for secondhand). I've tried researching the real risks of once-a-day, or less-than-daily cigar / pipe smoking, and I've found a few studies that address cigars and pipes specifically, but no real data on the risks of low-level smoking... | [
"Your tongue, cheeks, gums, and throat can all get cancer. I would assume these risks apply the same as for other forms of oral tobacco use.",
"no real data on the risks of low-level smoking",
"I haven't seen any either, but I don't have access to academic databases anymore."
] | [
"Agreed, except that the density of carcinogens and exposure time is far lower with a cigar than with chewing tobacco. ",
"That's not to say it can't happen, but chances are lower."
] | [
"You're still getting some down your lungs, but compared to cigarette smoking I suppose the risks should be miniscule.",
"Also cancer in mouth and throat-areas, but it's usually not half as bad as getting it in your respiratory tracts or lungs."
] |
[
"Help me and my friend settle this argument!!!"
] | [
false
] | He claims that the fact that we can only see the top part of a ship on the horizon is due to Earth's curvature. I think that even at such distances (assuming the furthest human eye can see is 10-20Km) the curvature only translates to a few centimeters vertically which cannot be differentiated by the human eye at that d... | [
"You can approximate how much the height changes due to curvature by",
"(distance to object)",
" / (8*radius of earth)",
"For 10 miles, this comes out to about 16 feet, rather more than a few centimeters.",
"Looking out to an ocean, the horizon you see is actually only about 3 miles out. Past that, ships st... | [
"He claims that the fact that we can only see the top part of a ship on the horizon is due to Earth's curvature.",
"Let's work it out. Here is the equation for the horizon point:",
"First, we need the Earth's radius in feet. It is 3958 miles * 5280 feet per mile = 20,898,240 feet. Call this ",
".",
"To comp... | [
"What is the triangle you are using trig on?",
"I made another calculation. ",
"Here is a diagram",
".",
"Theta is .09 as you found, R is the radius of the earth, then x is R cos Theta, and the height difference will be R - x = R (1 - cos theta). Google tells me this is about 7.8 meters. Plugging 20km into ... |
[
"What happened to CERN Project ?"
] | [
false
] | null | [
"What do you mean?"
] | [
"Did they failed, what are the results etc. General information "
] | [
"CERN is a 60-year-old organisation which has provided facilities for tens of thousands of scientists to perform hundreds of experiments over the decades.",
"If you want general information, this is where to start:",
"\n",
"http://home.web.cern.ch/about",
"Do you have a specific experiment or analysis in mi... |
[
"Does lightning cause a power surge or does re-powering something cause the power surge?"
] | [
false
] | I guess I should phrase my question differently, does lightning go hand and hand with a power surge? Here is a scenario, lightning strikes a building but not directly, this lightning strike causes the power to go out among other electrical failures. Can we say that the reason the power went out was due to the lightning... | [
"The reason power can go out in the event of a lightning strike is definitely due to the lightning strike itself. Basically, a lightning strike causes a massive ",
"voltage spike",
" in any nearby wiring, which is accompanied by a surge in current (because, in the simplest case of a pure resistor, voltage and c... | [
"Where the Lightning hits there may be a spike. At the same time breakers will momentarily open to prevent it from spreading to other parts of the grid then will reclose. "
] | [
"Electrician here. If your power goes out from a strike its most likely your part of the grid is down. A lot of systems will try \"booting\" your area back up (switching a disconnect remotely) and if there is a fault they send out service guys to fix the line. Otherwise your main breaker might be tripped but most l... |
[
"Are there any insects that can hunt in packs, similar to mammalian predators?"
] | [
false
] | Further clarification available about this question, if requested. .. watching a very strange movie, figured it was worth a shot. | [
"So, ants, but those feel more like a swarm than a pack.",
"Hornets raiding a honeybee hive",
" looks more like it.",
"On the other side of the spectrum, some species of spiders are known to form communal webs, ",
"for example",
"."
] | [
"The Australian huntsman is a spider which is close to what you're looking for. They live in colonies, and rather than using webs to trap, they actively hunt to acquire prey, and even share food. The paper \"Sociality in a bark dwelling huntsman spider from Australia\" covers their behaviour in depth"
] | [
"Absolutely, yes.",
"For years, I was petrified about any amount of contact with snakes. Someone bought me one as a gift, largely because I was afraid and my ex-friend thought it would be funny. ",
"With her life depending on me, I had to cope with the fear, learn how to care for her and eventually I was able ... |
[
"Is there a way to \"see\" beyond the observable Universe?"
] | [
false
] | I understand that the observable universe is simply light that has had time to reach us, and that without such we cannot really observe outside of it. I was wondering if there's any theoretical means by which we can extend our vision, so to speak? | [
"No. That would require something to propagate faster than light, and nothing we know of does that. The closest thing we can do is see the effect of as-yet-unseen objects on what we can see, so it's a sort of \"seeing by proxy\" effect. Dark flow is an example of this."
] | [
"No. That would require something to propagate faster than light, and nothing we know of does that",
"I just want to make a tiny correction in your terminology: no ",
" can propagate faster than the speed of light.",
"Under certain circumstances, it is possible for \"things\" to exceed this ",
".",
"For e... | [
"No information can travel faster than the speed of light.\nThus it is structurally impossible to gather any information from the \"unobservable\" universe."
] |
[
"Can we determine, solely by examining the ear of an animal, the range of frequencies that the animal can hear? Or, how much more information do we need?"
] | [
false
] | [deleted] | [
"Good question. I don't think there is anything about the outer ear morphology that you can look at and then guess what frequencies an animal can hear, but I may be wrong. However, it's fairly easy to determine the range of frequencies an animal can hear and there are many methods to do it. For example, you can put... | [
"That is actually a wonderful question. I would suspect so, based on the ear, the size of the ear canal and an estimation of the size of the cochlea and inner ear bones."
] | [
"I think this kind of information is derived more from direct testing by sweeping through frequencies and gauging reactions than by looking at the ear itself. "
] |
[
"How does compressing files (zip files etc) work?"
] | [
false
] | It's my understanding computer files are ones and zeros...how can that be compressed and then uncompressed? | [
"Let's forget the binary code for a minute and just talk about ways to compress things.",
"Let's say that you're talking to someone over the phone, and you want them to write down the letters \"AAAABBCCCCCCCCCDDDDDEFFFFFFFF\". You could say the whole thing out, but you could also simplify it: you could say \"4 A... | [
"For lossless compression, you can basically observe repeating patterns of zeroes and ones. Then, you note what they are and replace them with something shorter in the actual data.",
"Purpose-specific compression (think FLAC or PNG) algorithms take advantage of certain patterns inherent in the type of data they t... | [
"He was downvoted because he didn't need to post at all. If you don't want to answer, don't answer. Many people post questions here in the manner of asking a friend, rather than googling. "
] |
[
"What is thought to have stabilized earths magnetic field?"
] | [
false
] | From what I understood in a lecture, Earth's poles were constantly shifting throughout the Cretaceous but then they became fixated? | [
"I'm a graduate student in earth science, but I'm studying glaciology, not geomagnetism. Nonetheless, I'll give this a go:",
"The Earth's magnetic field is caused by convection cells in the liquid iron/nickel outer core. It is not known (at least by me) what causes reversals, but my understanding is that they a... | [
"From what I've researched it seems as though it is thought that due >to the high pressure of the core some atoms lose their electrons and >the said electrons flowing around the core create the magnetic field >on earth. I'm just not sure why it focuses more at magnetic poles >and what causes reversals.",
"That's ... | [
"Thanks for the quick response! I understand how the magnetic field is formed and that it isn't truly fixed (I apologize for the poor wording in the dexcription) but my real question is what causes these reversals or \"fixations\". \nFrom what I've researched it seems as though it is thought that due to the high ... |
[
"Can rain evaporate before it hits the ground?"
] | [
false
] | If it's raining on a hot day for example | [
"Yes, this is a relatively common occurrence, especially in hot desert areas, but can happen pretty much anywhere on earth. It is usually visible as a phenomenon known as ",
"virga",
", looking like wispy, feathery streaks below the base of a thicker cloud. ",
"This page has a number of great photo examples",... | [
"It is! If you look at a radar, and the radar is suggesting rain, though you see none at the ground, that’s usually because of virga. The radar beam usually intersects the cloud thousands of feet above ground level, depending on distance from the radar."
] | [
"I didn't know it was that common, thanks!"
] |
[
"Is a completely electric jet engine possible?"
] | [
false
] | Given that a jet engine works by the compression of air, adding fuel which is then ignited to rapidly expand the air out the back, could an engine be built (if a way to provide the necessary electrical energy was available) using an electrical arc to expand the air. If so, how much electrical energy would be needed? | [
"I wholeheartedly disagree with your assertion that a high bypass turbofan is not a \"jet engine\", by the definition of a jet engine being an engine that generates thrust via jet propulsion, it absolutely is a jet engine.",
"A high bypass turbofan still generates a jet of air to produce thrust, the first stage f... | [
"We'd run into the same mass/energy density problem we have with electric cars, but much sooner due to the higher energy demand to fly something through the sky and the extreme sensitivity of those objects to having extra mass. ",
"Electric cars have limited range because batteries simply cannot store the same am... | [
"Yes, but you need a tremendously energy dense source of electricity. Jet engines are used in aircraft because they are very lightweight and use a comparatively small amount of fuel per unit of mass flowing through the engine. With current technology, it would be a wasted effort. You could potentially make one o... |
[
"Which uses more energy to maintain a constant freezing temperature: an empty freezer or a freezer full of food?"
] | [
false
] | Also, how does periodically opening the door of the freezer affect the answer? What should you do if your goal is to save money in energy costs? | [
"I am pretty sure an empty freezer and full freezer use the same amount of energy ",
" you never open the door. Once you open it having things in the freezer is the way to go because air escapes. The new air will be warmer than the air that left, so the freezer will have to cool it back down. If you have more ite... | [
"Thermodynamics! Definitely one of the trickier topics from my physics days, but let's see what we can do here.",
"So since your question says so, we're going to assume that the freezer is already at a temperature of about -10 C. So, does it take more energy to maintain this temperature if the freezer is empty or... | [
"Yes, of course...\nAn empty freezer has far less heat capacity... Less capacity to \"store\" thermal energy which must be removed by the fridge.",
"And, yes, if the freezer has perfect insulation, (which is impossible) it will require zero energy to maintain low temperatures whether it is filled or empty."
] |
[
"If you put all the black holes of the universe on one side of an imaginary scale and all the rest of the universe on the other side, then which side has more mass?"
] | [
false
] | null | [
"The non blackhole side. There are several hundred billion stars in a galaxy, the lightest of which have a mass of around 1/10th of our Sun, overall the total mass of our galaxy is nearly a trillion times the mass of our Sun. In comparison, the supermassive blackhole at the center of our galaxy weighs only around 4... | [
"And that's before you add another 400% to the non-black hole side for dark matter."
] | [
"Dark matter means something very specific, not just \"all matter which doesn't give off light,\" so we don't include black holes when we talk about the amount of mass in dark matter."
] |
[
"What actually causes the heat during a fever?"
] | [
false
] | I don't mean specifically what causes you to get sick and get a fever, but what reaction from the infection or antibody buildup is causing your body to heat up? Thanks and I hope I made that clear. | [
"When you get an infection, several things happen to allow the immune system to function and kill the bacteria which is causing the problem. One of the first things that happens is that the tissue gets inflamed (red, swollen and painful). This inflammation is caused by immune cells releasing small chemicals called ... | [
"Please see this link, it explains quite well the different types of pyrogens and how they work:\n",
"http://en.wikipedia.org/wiki/Fever#Pathophysiology"
] | [
"not mentioned here is that there is a benefit to fever - increased immune activity. that is why low-grade fevers (99F area) are actually best left \"untreated\" as they arent all that damaging and aid in immune activity. high grade fevers can cause a variety of other problems (delirium, etc) and should be treate... |
[
"Permanent nerve injury?"
] | [
false
] | null | [
"Hi Shrodingers_Dog thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the... | [
"I'm more of asking for others experience, or scientifical advice about the nerves in the body and how they repair themselves. Do nerves in the foot regenerate? Is there a time frame for your body's nerve repair? How long generally before nerves repair themselves. I know you all aren't my doctor. I'm just looking ... | [
"Sorry we do not give medical advice on this sub. Please speak to your doctor."
] |
[
"Do continuously mutating viruses like the common cold waste B cell memory 'space' in our bodies or otherwise dilute our immune system in some way?"
] | [
false
] | My understanding is that a B cell remembers a specific pathogen, so I am assuming most pathogens you have ever encountered have B cells made for them hanging out where they might some day be needed. Are there a limited amount of these cells (or total cells?) you can have in your body? Like, does having 30 different ver... | [
"Medical student here,\nAnd no there is no space ‘per se’ of Memory B cells. ",
"Anytime our bodies get new infection that is otherwise unknown before and once we recover, or when get vaccinated, ‘new’ Memory B-cells are formed. Those new memory B-cells are made relatively in few numbers initially but if we get r... | [
"Both, they float around in our blood all the time as well as are present in special areas all over our body, more like at entry defense points, like working closely with gatekeepers which are our T-Cells and APC cells. \nAs far as limit is concerned, let me just paint a picture, just in a cubic millimeter of bloo... | [
"It's not like all the memory B cells that get produced during an immune response stick around forever, they will be \"recycled\" in a way, leaving a small population around in case another antigen of that type comes along. The rate of B cell creation is also slowed during a healthy state, and only ramps up during ... |
[
"How does an MRI machine image the inside of your body?"
] | [
false
] | I'm a senior biochemistry/biophysics undergraduate, and I'm taking a class on protein structure determination. Part of this is NMR and I've learned all sorts of stuff about bulk magnetization, relaxation time (T1 vs T2), pulse sequences, product-operator formalism, spin-echo and the like. I have no idea how this techn... | [
"The main gist behind it is frequency and phase encoding. Your body exists in 3D space - so that's three axes we have to take care of. For the purposes of definition, we'll define the head-foot axis as the z-axis, which is usually the axis of the B0 field. Left and right of the patient can be called x-axis, and ant... | [
"Well, you have all the tools for understanding of NMR, so it should be relatively simple to explain MRI. Are you asking how T1 and T2 images are weighted? Or how signal is localized on an image? Or which pulse sequences allow for rapid acquisition?",
"For how scans can be weighted, ",
"this article",
" does ... | [
"I'll add a few more details about resolving the \"scrambled signal\", since the receiver is going to get the combined signal from each point in the x-y plane you chose with slice selection. First of all, only the slice you selected is excited, so you won't get signals from anywhere else.",
"Now, if you only loo... |
[
"Is there any long term possibility of containing (or hopefully reversing) the ecological contamination of the Great Lakes?"
] | [
false
] | I've read around a bit, but I haven't found a really satisfactory answer. Is it possible for us to reverse the effects at some point, or are these invasive species here to stay? I know that one of the solutions is to prevent the dumping of ballast tanks in the Lakes. Are there others that might be more effective at rid... | [
"New ballast regulations (33CFR151 for the US)the requirement for vessels to maintain a ballast water treatment system/ alternative management system have been in place for awhile mainly to combat invasive species; although some vessels are still able to do a traditional ballast water exchange. As far as combating ... | [
"I assume that's still a huge issue then.",
"Ballast water regulation on the Great Lakes is tricky. Canada follows the International Maritime Organization rules, but the US follows its own USCG & EPA rules. IMO allows for water disinfection (neutered organisms) , but the USCG requires sterilization (door nail dea... | [
"Department of fish and wildlife, and local agencies would be best at answering about introducing other species to environments. I briefly worked with them on two occasions (Lake Erie and straight in Washington) during such processes, but can not speak to the actual research/impact it has had in those environments.... |
[
"Would a full nuclear exchange between all countries who have the capability really be able to kill off every human on the planet?"
] | [
false
] | I understand it could if say the earth's entire nuclear arsenal was aimed at doing that but if the nuclear countries simply attacked other nuclear countries or countries they are at war with. Wouldn't people survive on Easter island, in the heart of the Sahara or maybe some uncontacted tribe far away from civilization.... | [
"Consider that people could hide out and not know that World War II was over... for ",
". The Earth is a big place, with lots of hidey-holes. There are lots of strategically unimportant islands and mountains, deserts, ships at sea, etc. People would survive."
] | [
"Radiation doesn't really work that way. So no."
] | [
"Yeah, those models basically went into the bin in 1992, after they were used to generate predictions of a regional (maybe even hemispheric, I forget) climatological apocalypse after the Gulf War."
] |
[
"If you can add spin to a black hole by slinging matter into it, doesn't that violate the viewpoint of an external observer never seeing the matter pass through the event horizon?"
] | [
false
] | null | [
"In the reference frame of a distant observer, the state of all matter that falls toward the event horizon becomes part of the event horizon."
] | [
"You can't observe an event horizon, so it's pointless to talk about it. Instead, what you do is characterize the matter that falls and that gets emitted back out via a scattering matrix."
] | [
"So, would you start with an event horizon where things dropped into the black hole would just redshift and fade, but after slinging in enough mass to make the thing spin you'd have a slightly oblate event horizon where things dropped in would be dragged along with the rotation while redshifting and fading? Sorry,... |
[
"Are there any bacteria that use the body's inflammatory response against it?"
] | [
false
] | I'm curious as to whether there are any specific kinds of bacteria or other infectious species that can trigger an inflammatory response and then benefit from it. Furthermore, what are the disadvantages of the human body's inherent inflammatory response? | [
"Let's start off by saying that in general the body's inflammatory response is a very, very good thing. Sometimes it can be problematic as you see with people with severe allergies to peanuts, some autoimmune diseases etc. But for the most part it's good and the inflammatory response usually mops up some infectious... | [
"Just want to add for the HIV section that HIV doesn't only replicate in CD4+ T-cells. It replicates in many CD4+ cell types including dendritic cells, monocytes etc."
] | [
"Did not know that. Thanks for the additional info!"
] |
[
"Assuming abiogenesis is correct, how does gravity come into play in the development of life? Is Earth a \"gravity sweet-spot\" for life?"
] | [
false
] | null | [
"I'm not an expert, but as far as I can remember all the experiments in space we've conducted regarding plants, animals, spiders, that sort of thing living in differing gravity levels, all have thrived just as much as we have.",
"In addition to that, the less massive an object is the less it is affected by gravit... | [
"For abiogenesis it would play a role in the kind of atmosphere. Too light and you don't have oxygen or water, too heavy and you don't get liquid water. So that is a sweet spot of sorts.",
"For the rest of life of course it plays a role in everything. Body sizes, flight, largest organism, etc. "
] | [
"If life demands a specific value of gravity, it will only form on those planets capable of harboring it.",
"\nIf Earth did not meet those criteria, life would not have formed on Earth.",
"\nIf life did not form on Earth, we would either not be here to contemplate how precise Earth's conditions are; or we would... |
[
"What's the difference between the piezoelectric effect vs what we know about time crystals?"
] | [
false
] | I just read this article about in a children's crystal growing kit. As described in the article, time crystals change their state when "exposed to an electromagnetic pulse". Since minerals like Quartz also change state when exposed to a electromagnetic pulse, how are they different? Is it just the arrangement of the mo... | [
"All oscillators without an external source of energy are lossy. The oscillation will die down with exponential decay, taking some number of cycles for the amplitude to decay by half. A good oscillator might take hundreds or thousands of cycles for that to happen, but it will stop if left on its own.",
"Electroni... | [
"Once the time crystal is \"kicked\" as you stated, does the ocilation occur indefinitely without another kick? Or does the crystal require a re-kick after a while?"
] | [
"Once the time crystal is \"kicked\" as you stated, does the ocilation occur indefinitely without another kick? Or does the crystal require a re-kick after a while?"
] |
[
"Is the effect of electric field extending to infinity like the gravitational field? If no, to what distance do they extend?"
] | [
false
] | [deleted] | [
"Yes, in theory the electric field has unlimited range. However, there's a fundamental difference between the electric field and the gravitational field and that is the presence of two opposite charge polarities and the mechanism of \"screening\" that is a result of this.",
"When it comes to gravity, the \"gravit... | [
"There's the noise floor to contend with. The EM field is excited by all moving charge carriers the number of which is.. substantial, so even outside of the screening and field loss with distance concerns getting swamped in other field excitations is a major real world problem."
] | [
"Because that information never left. It was never lost behind the event horizon. For the same reason you can see the gravitational \"Charge\" of the black hole in its mass.",
"You can think about this in a bunch of ways.",
"You never see the Charge enter the event horizon. The Charge gets stuck on the horiz... |
[
"Fluid dynamics question about a vacuum vehicle."
] | [
false
] | [deleted] | [
"Short answer: building a teardrop-shaped vehicle is more efficient than any other kind because it has the least amount of drag. ",
"Wikipedia article on how shape impacts drag coefficients",
"Longer answer: If you've got some vehicle that you want to make go forward, you need some driving force. You explode ... | [
"That does help a lot.. I'll even forgive you for that Burning Man jab! ;) ",
"I didn't realize that skin drag (I think I've also heard that referred to as surface adhesion) was so significant.. I assume it's still secondary to 'form drag' though.",
"So disregarding skin drag for a moment.. and refining the sha... | [
"Or I suppose a teardrop toroid would be closer to ideal:",
"http://i33.tinypic.com/2lxgl1d.jpg"
] |
[
"Do manual transmissions or automatic transmissions get better gas mileage? Why?"
] | [
false
] | I hear manual transmissions used to be more efficient, but that modern automatic transmissions have improved to the point that they're equal or better. Is this true? Why is one or the other more efficient? | [
"There is a couple reason for this.",
"Until rather recently manual transmission generally had more forward gears for the same application vs an automatic transmission, a 5speed manual vs 4 speed auto or even a 3 speed auto. Having 1 or 2 more gears means the engine rpm can be minimized or better optimized for c... | [
"Last part is actually the opposite. Auto stop/start on non-hybrids first came only on manual transmission cars (earlier in EU markets as manuals are more common, or dual clutch transmissions which are mechanically the same as manuals for purposes of this question) because the time it takes to clutch in and move th... | [
"Until the advent of partial and fully locking torque converters in automatic transmissions the manual transmission was often more efficient. This is due to the waste energy spinning a torque converter and slipping vs the direct coupling of a clutch.",
"As said in other posts gearing and number of gears also add ... |
[
"Is it possible to trap light in a hollow ball whose inside is made out of mirror?"
] | [
false
] | Say you have a ball which can be opened. Inside the ball is purely mirror. You put a flashlight that is turned on inside and you close the lid for a million years. The flashlight will have run out of battery long before then. Within the ball, will the light just keep bouncing forever? Now after a million years, someone... | [
"Mirrors don't reflect light perfectly. With every \"bounce\", part of the light is absorbed instead of reflected and the reflection loses some of its intensity.",
"Regular everyday mirrors will top out at about 90% reflectivity. That means that 10% of the light intensity is lost with each bounce. If the distance... | [
"I picture someone trying to close a hole in a ball really, really fast."
] | [
"Lots and lots of misinformation in this tread... ",
"Gallileo did ",
" try to measure the speed of light with a stopwatch. First of all, there were no stopwatches at the time. ",
"What he recommended was having two people with lanterns facing each other, the first person lift the veil, then when the secon... |
[
"Is radiation from Cell phone andTelivison masts harmful to health?"
] | [
false
] | [deleted] | [
"The answer is no, as far as we can tell. There haven't been any studies showing that they are harmful, nor is there a currently known mechanism for it to be harmful.",
"Thats assuming, of course, that you're not sitting right next to the transmitters for long periods of time."
] | [
"No."
] | [
"There are certain types of radiation that are harmful to human cells. Particularly, high frequency radiation like gamma waves or x-rays can cause an atom in your body to lose an electron. If that atom is in a DNA molecule, bad things can happen and you can have a mutation. ",
"The radiation emitted for cellph... |
[
"Why is AC better for long distance power transmission?"
] | [
false
] | null | [
"It comes down to : AC was easier to generate and easier to get to high voltages using transformers. You could then transmit the same amount of power at higher voltages and lower currents. ",
"Joule's law tells us that loss is directly proportional to the square of the current. Thus buy increasing voltage and low... | [
"When transmitting long-distance you want high voltage and low current to minimize parasitic/heat losses and increase efficiency. AC is prevalent because it's very easy to shift AC voltage levels via a transformer, not because it has some inherent advantage over a DC system.",
"High-voltage DC power transmission... | [
"DC is better for long distance power transmission. There are lots of losses when using AC for transmission. AC is easier for stepping the voltage up and down."
] |
[
"Since humans shed the top lay of dead skins cells everyday, why dont scars and tattoos disappear much faster?"
] | [
false
] | null | [
"They can divide a finite number of times, so yes. But tattoos also fade over time (years)."
] | [
"Not all your cells replicate and are replaced."
] | [
"But aren't all the other cells in the body also being replaced on a regular basis? "
] |
[
"Is there a science about knots and what gives them their strength?"
] | [
false
] | null | [
"Well, there are multiple ways to answer this. Yes, scientists (generally, material engineers) study physical tying knots. There are multiple studies that I'll link to. As for strength, that's a big question. Friction/surface area, material, and use all factor into strength. According to one source (2), one of the ... | [
"Contrary to popular belief, knots weaken the rope in which they're made. A lot of this probably falls under materials science."
] | [
"how and why do electrical cords get tangled?"
] |
[
"If a black hole were moving through the earth, would it experience friction?"
] | [
false
] | null | [
"I don't understand what you're arguing for. The question is a random hypothetical question and you're trying your hardest to restrict the hypothetical question in a way where nobody can learn anything"
] | [
"If a Black Hole dropped through the Earth from the North Pole to the South Pole, it would gobble up a lot of matter. Since momentum must be conserved, the speed of the BH must change, even though it might be to a tiny extent. You could regard the net force that causes that to happen as a kind of friction.\nHow muc... | [
"You're making a lot of assumptions. If we could place a black hole of arbitrary initial mass and velocity at an arbitrary location with respect to the Earth, it could come out the other side (or more likely, pull the Earth into itself) with a considerably different trajectory."
] |
[
"What is it about oak that makes it the choice for distillers to age their liquors in barrels made out of it?"
] | [
false
] | null | [
"Going to do some educated speculation on this.",
"First thing to remember is that oak flavor in wine and whiskey is a happy coincidence. Until industrialization the only way to store liquids in any significant way was in barrels. They didn't have stainless steel tanks or kegs and there was no real way to make pa... | [
"No kidding, I'd love to taste the differences. There's got to be a micro distillery somewhere trying this. "
] | [
"No kidding, I'd love to taste the differences. There's got to be a micro distillery somewhere trying this. "
] |
[
"Is it possible for organic matter to get trapped in extrusive igneous rock?"
] | [
false
] | I've been trying to find an answer for this in scholarly sources, but am having trouble tracking down anything discussing it in detail. The most I've been able to find is people noting that organic matter usually ignites on contact with lava, which is obviously true, but I'm curious what happens if it is not able to bu... | [
"Depends a little bit on exactly what you're interested in. I.e., are you asking about fossils broadly defined (where typically the original organic components are not preserved, but the original structure of an organism is to varying degrees through various fossilization processes) or are you more specifically onl... | [
"There are known occurrences of methane inclusions (after all organic carbon) in igneous rocks, however with rather a non-biological origin, but that are the results of the reaction between hydrogen gas and inorganic carbon (graphite). Also, there are described zircons with inclusions of graphite (per se inorganic ... | [
"There's a pumice mine near Los Alamos NM where you can find ",
"carbonized wood fragments",
" in the lower beds of the ",
"Bandelier Tuff",
"."
] |
[
"Why isnt subpixel rendering used in games?"
] | [
false
] | Subpixel rendering is a method that takes into account the actual physical position of RGB elements (subpixels) in the display to increase the apparent resolution beyond the physical one and decrease aliasing when rendering computer fonts, also known as ClearType or FreeType. The results look good (just look how nice t... | [
"So, subpixel rendering works great for black text, or generally any black-and-white images with hard edges. For color images, which usually do not have clearly defined edges, it's not so handy. You tend to see a lot of artifacts in the image. Also there's the problem of properly detecting the pixel geometry of ... | [
"You can actually see these kinds of artifacts in the last two pictures ",
"on the page he linked to",
". The subpixel-resized picture has color fringing on the front grill leg and edges, the window's center divider and whatever that pole is leaning against it, and the gate at the end of the path. The bicubic... | [
"Generally every step in the render loop of a 3D engine is optimized to balance the visual benefits with the computational steps required. By only dealing with pixel level anti-aliasing, they are able to get essentially the same level of smoothing each frame while only needing to compute 1/3 of the values.",
"Thi... |
[
"Can someone explain how we intend to use the silicon sphere to calculate what a kilogram is?"
] | [
false
] | Last night I saw a video explaining that scientists made a silicon sphere to define what a kilogram is, but I really don't understand how that would work. Can someone help me understand? Thanks. | [
"I believe it involves setting a value for Avagadro's number (like they set the speed of light). You then have a sphere of silicon with known atomic mass (kg/mol) and known number of moles (from geometry). It'd be an easily recreatable standard, no need to visit France to get the kilogram standard."
] | [
"Yeah. And then adjust the definition of the kg to match the size of the sphere needed, so the sphere ",
" one kg by definition. (and the old kg is now +/- some small value)"
] | [
"Units of measurement are arbitrary. With a bit a juggling around, you can show that by setting 7 properly chosen units (see this ",
"article",
") all other units are set; that is to say, with the value of those seven base units you can calculate the value of all other units. 6 of those seven units are chosen a... |
[
"Is it true that if you are insane, you do not know it?"
] | [
false
] | I've heard from different sources (research papers/documentaries/etc.) that if you are indeed insane, you do not realize it and you think yourself perfectly normal. Is this true? | [
"This is not true. Plenty of people with mental illnesses are aware of it. If you search reddit AMAs, you will find a couple from people who have schizophrenia and are completely aware that they way they experience the world is not the way others experience it. There are, of course, some people who are extremely me... | [
"We are all insane, and should all be a little more humble.",
"No we are not.",
"You can walk around with all of the delusions and quirks you want, if they are not interfering in your ability to live a normal life, and they don't pose a risk to you or others, then they don't meet the criteria for a mental illne... | [
"We are all insane, and should all be a little more humble.",
"No we are not.",
"You can walk around with all of the delusions and quirks you want, if they are not interfering in your ability to live a normal life, and they don't pose a risk to you or others, then they don't meet the criteria for a mental illne... |
[
"Do we all begin life as females ?"
] | [
false
] | My lunch table got in this topic today and no one really had an answer for it. Do we all begin life as females ? in our mothers wombs ? | [
"No and yes.",
"No, as a human, your DNA is either XX (female) or XY (male). You get an X gamete (egg) from your biological mother, and an X or a Y gamete (sperm) from your biological father. Occasionally, there will be a genetic anomaly of XXY or XYY.",
"Yes, all zygotes/fetuses ",
" female at first, because... | [
"Yes, ",
".",
"A better way of putting it is this: female is like the 'default' sex, and male is like a mutation. You can live with just one X chromosome (and you will be female) - you cannot live with just a Y chromosome. The Y chromosome is there to make male adjustments to the default female model."
] | [
"yeah this guy has it, physically? yes, but on a basic level, you don't become male in the womb, you always are, it just takes time for you to develop into one."
] |
[
"Does the brain increase in temperature when thinking more?"
] | [
false
] | I understand that the brain cools itself down through the ears and head, but what if it didn't have this cooling system? Would the temperature change at all or does all the energy of thinking just go into thinking itself? | [
"brain cools itself down through the ears",
"Where did you hear that one? While the body cools itself down through the skin, and ears have skin, there is no special relationship between the brain and the ears.",
"Your fundamental question is: does the brain increase in temperature when we are thinking more. Tha... | [
"Hey, that's cool! The brain is actually very sensitive to temperature, if you let your core get down to 35 or up around 39 you will not think that well. Few other body organs are as sensitive. You could make a good argument there is strong evolutionary pressure to maintain brain temperature that drove skull thickn... | [
"There are tow jumps in your logic here; First, that heat=friction. All the major chemical reactions in the active brain are exothermal: membrane currents, oxidation reactions etc... The second is just a rewording of the first one, but involving muscles."
] |
[
"How / Is domesticated behaviour carried into genes ?"
] | [
false
] | Most dogs are friendly to humans. I assume this comes from a long term mutually beneficial relationship since prehistoric era. How that familiarity is passed through generations (if it is) ? Is every dog a "subwolf" that need to be updated through training that Human is the alpha etc... Or they already "know" us and ar... | [
"The short answer is that nobody will give you a list of friendliness or domestication genes (sections of DNA). What we see is a pattern of domestication over many generations; humans would selectively breed the friendlier or less vicious wolves and gradually the dogs we know today were born.",
"This was done in ... | [
"You've actually asked a very good question, to which we don't have a good answer (yet). Is behavior encoded in genes? Yes, certainly. You only need to look at the animal world to see that. There are many, many cases of animals (and insects) that grow up without a paternal figure (who aren't raised by parents, ... | [
"Yes domesticated behavior is genetic. ",
"Maybe dogs aren’t the clearest example. So let us look at sheep. Domesticated sheep exhibit “flocking behavior” when they are alarmed. Wild sheep instead flee and disperse. Most of them escape the predator, some are killed, some are hurt or “lost” (doesn’t really apply i... |
[
"What difficulties would a woman have (if any) giving birth in a microgravity environment?"
] | [
false
] | A quick search came up with some studies that had rats being born in space, but they focused on fetal development. I was wondering about a Hunan actually giving birth in space. For the purpose of the question, imagine that a very rich woman wanted to be the first to give birth in space and she paid a crazy amount of mo... | [
"I would imagine that she would first need to be tethered, of course, to a delivery table. And while I don't know the specifics of gravity affecting the delivery process, since there is no empirical evidence existing on a zero-gravity birth, we don't really know how big a role gravity plays in the birthing process... | [
"The biggest issue I think of would be all the fluids. There is no way to have enough suction to keep the fluids from getting in the way. If you tried the hoses would be in the docs way. They need as much visibility as possible. They use extremely bright halogen lamps from the ceiling focused on the vagina to see c... | [
"Interesting. I wonder if it would be easier for the woman to have a cesarean? I assume a surgical procedure like that would be quite difficult in microgravity though."
] |
[
"Is it true that it is illegal to own pure moondust in the USA?"
] | [
false
] | On Page 171 of the popular book "Moondust" by Andrew Smith, he states: By US Government decree, no one is allowed to own pure Moondust, not even astronauts. Is that true? If so, why? | [
"It is illegal to own rocks or dust originating from the moon - if they were brought back by the Apollo missions. This law was enacted, I believe, to curtail a market for genuine samples which had escaped the government's possession. Apparently dust samples had been taken from astronaut's suits during inspection, a... | [
"It belongs to the government of the USA, as it funded the missions there to collect it."
] | [
"That must really be something, even if it is only a tiny speck. The only time I've ever seen a moon rock there was about 2 inches of glass between me and it. Still, it was a moving experience.",
"But I fear that moon rock is not the most expensive substance on earth. Antimatter, produced only in large particle a... |
[
"Can researchers to discover the possible long-term side effects of a potential COVID-19 vaccine in juat a few months of study? If so, how? What steps can be taken to mitiage those side effects?"
] | [
false
] | null | [
"Would you direct me to where I can find an answer to my question?"
] | [
"Would you direct me to where I can find an answer to my question?"
] | [
"4 days ago ",
"https://www.reddit.com/r/askscience/comments/jrv59s/is_there_any_concrete_evidence_that_any_currently/"
] |
[
"Why does heat from a star lose intensity over a distance despite being in a vacuum?"
] | [
false
] | How does the light energy dissipate and what is it absorbed by? | [
"There's more surface area if you draw a sphere 1 lightyear out from a star than 1 meter out from a star, right?",
"So each bit of surface area is going to get a bit less heat, because there's a finite amount of heat being spread over a larger area.",
"Make sense now? ",
"Edit: Reversed the distances in my c... | [
"Absolutely. Thanks for the reply."
] | [
"Exactly. Think of it like this: you have a space heater in the middle of a large empty room in your house. The closer to the heater, the warmer you are. The farther away, the colder it is. There is more area.for the heat to disperse the farther away it moves from the source. "
] |
[
"Does the size of a star affect the size of the planets that can form around it?"
] | [
false
] | null | [
"It's mostly random how it starts but anything 2m from the corona for example will immediately get torn apart both by coronal mass emissions and by gravity.",
"It is mostly the stellar wind that results in a pushing of the protoplanetary disc from the host star not magnetic realignment events. More massive stars ... | [
"Star mass only really effects the probability of a planet of a certain mass being formed. ",
" ",
"We expect that lower mass objects are more common and so there is no theoretical reason to believe and star has a lower mass limit. At the opposite end of the spectrum, we have observed giant planets around M cla... | [
"Not the size but the size and at a certain distance.",
"The planets are formed when the accretion disk that forms around a star starts the come together.",
"It's mostly random how it starts but anything 2m from the corona for example will immediately get torn apart both by coronal mass emissions and by gravity... |
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