title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why is my frosted notebook cover transparent when close to an object, but opaque at distances?"
] | [
false
] | I was in class and I realized that as I opened my notebook cover, the text underneath became rapidly out of focus. The cover to the notebook is a frosted plastic. When the cover is closed and the plastic is directly above the text, everything is easy to read. Once the cover is a distance of a few centimeters from the p... | [
"Imagine two of the letters that are near each other each producing two light rays at a slight angle to each other (like a <, but with a much smaller angle, coming out very near perpendicular to the page). These rays hit the plastic, and are scattered a bit (the frosting effect). Now, if the distance between letter... | [
"the cover refracts light at different angles (most likely due to surface roughness). thus, at close distances, rays aren't bent much, but when the distance between the medium and the subject are increased, increased refraction blurs the image."
] | [
"Why then, is it a function of the distance from the object, but not of the distance from the observer? Sorry, my optics knowledge is REALLY fuzzy (no pun intended)."
] |
[
"I don't understand how a microwave can cook food at different rates of speed if briefly stopped."
] | [
false
] | If I microwave hotpocket #1 for four minutes it will come out lava. If I microwave hotpocket #2 for two minutes open the microwave check the hotpocket and cook it for another two minutes to will come out warm but not lava. These are hypothetical examples. | [
"Most microwaves basically cook at full blast. The different heat settings you can set cause the microwave to take breaks at intervals like the break you gave your hot pocket at the two minute mark. This allows the hot and cold parts of your food to interact with each other longer; the cooler parts get more time ... | [
"I think he was asking why nuking something at full blast (say 750w) at 2 minutes, two times, with a small break in the middle doesn't make it as hot as nuking it at full blast (still 750w) for 4 minutes straight."
] | [
"I have a purely speculative answer. This is mostly story telling, but it does agree (except with one caveat at the end) with what I know about how microwaves work.",
"Microwaves work on the principle of dielectric heating. Essentially what you're doing is rather than making molecules vibrate faster (which is wha... |
[
"What is the 4th dimension and can you possibly explain it in layman's terms?"
] | [
false
] | I am not sure what category this falls into, but I think physics or mathematics are the closest ones. EDIT: Thanks for all the answers and thanks for making things clear to me, especially you | [
" fourth dimension isn't a thing, though I suppose time is often referred to as the fourth dimension.",
"You should just think of dimension as \"the number of pieces of information needed to uniquely specify a point\". So to uniquely specify a point in physical space, you need three pieces of information (for exa... | [
"Instead of thinking of \"the fourth dimension\" as a place or as time (although it's often, not incorrectly, used to refer to time), think of the number of dimensions as characterizing how many ",
" you can go.",
"In our spacetime, we can uniquely locate an event by where it happens and when. So how do we do t... | [
"Are there continuous bijections from ",
" to ",
" ? I didn't think so. There definitely aren't from [0,1] to [0,1]",
"In any case, vector space structure is more natural to think about for a definition of dimension. I can get into an explanation of Hausdorff dimension if necessary.",
"EDIT: Actually it's a... |
[
"How bright is humanity's electromagnetic footprint today, on all parts of the spectrum?"
] | [
false
] | One way we might detect life on an exoplanet might be the EM radiation that it emits from artificial sources. So to an outside observer, what regions of the EM spectrum would we be emitting and how would the radiated power compare to other objects in space? | [
" The electromagnetic 'footprint' of humanity, as you call it, is pretty much nothing when compared to the sun. ",
" This is probably the hardest question on askscience I've tried to tackle in a long time, so let's go on an adventure :D",
"For reference, the power output from the sun is about 3.9 x 10",
" Wat... | [
"I was under the impression that our TV and radio broadcasts became sufficiently powerful to ",
" out of the solar system some time around the start of World War 2. I understand that the sun outshines anything we could ever send in visible light, but aren't the bands we used for communication used precisely beca... | [
"Is that to say that from that distance the light from the Sun would block out the ability to see Earth or was that just in terms of the electromagnetic footprint? The quality/capability of the telescope aside.",
"Well it's going to certainly depend on the quality of the telescope (and the distance to the aliens.... |
[
"If I have a string that is one light year long"
] | [
false
] | [deleted] | [
"Assuming the string is rigid (no elasticity), the speed of sound. If it's elastic (stretches), then I think it depends on the modulous (Young's? Help me out, materials science ppl)"
] | [
"Good enough - no need to talk about young's modulus, just speed of sound is correct. "
] | [
"Right. The rate at which the \"stretching\" travels down the material is the speed of sound in that material."
] |
[
"How is nutritional caloric content calculated? Particular with regard to items which the human digestive system doesn't break down/get energy or nutrients from"
] | [
false
] | When calculating the caloric content of foods, do the calories contained in substances indigestible by humans count? How is the caloric content of food calculated in this regard? I am familiar (more or less recall) the chemistry concept of caloric content based on the energy released as it heats water of a known volum... | [
"The standard energy densities for macronutrients take digestibility into account. In general, the digestive system is highly efficient (~95%), but there are additional adjustments for fiber (only about 2 kcal/g are available out of the theoretical 4.2 kcal) and protein (there are substantial losses due to incomple... | [
"Another question, what is up with zero-Calorie \"energy\" drinks? A Calorie is a unit of energy, what gives?"
] | [
"many of them contain caffeine, taurine, and vitamin B which lend themselves towards being the \"energy\" aspect of the energy drink.",
"Also, zero-calorie means that there are fewer than 5 calories per serving, so they might have an unreported gram of sugar in there too. "
] |
[
"What is at the center of the Milky Way galaxy?"
] | [
false
] | null | [
"Yes. Also the one recently discovered wasn't recently discovered. It was known to be a black hole for some time, but researchers just now managed to create an image of it, the first ever picture of a black hole.",
"There's plenty more on this subject in the recent AMA thread with the scientists that created this... | [
"Sagittarius A*, a supermassive black hole with a mass of approximately 4 million times that of the Sun."
] | [
"So this is a totally different black hole that was just recently discovered?"
] |
[
"Why do our eyes turn red when there is a camera flash?"
] | [
false
] | [deleted] | [
"Your pupil is transparent and only looks black because it is the only point of entry for light in the eye. It's similar to standing outside of your house in the daytime and trying to look inside one of the windows while the inside lights are off.",
"A camera flash increases the light intensity and allows a more... | [
"it's the flash reflecting off your retinas"
] | [
"Because the red light is the result of the reflection of it off our retinas"
] |
[
"Why exactly do the tectonic plates move in different directions?"
] | [
false
] | I fully understand that tectonic plates are just pieces of crust that move because of the convection cells of lava and rock beneath the surface moving them towards a certain direction. But my question is do the different convection cells all move in different directions, what determines that? So for example, the Indo-A... | [
"There are a few different forces driving the motion of tectonic plates.",
" is thought to be the main one. The part of the plate that is subducting is old, (relatively) cold, making it dense, making it sink in the mantle. It pulls the surface part of the plate along. Like a tablecloth sliding off a table because... | [
"The other answers are good, but I think they leave out an important point that would help you understand plate motion. ",
"Because the earth is a sphere with a curved surface rather than a flat disc, plate motion is better described as a rotation, rather than linear movement from one place on the planet to anoth... | [
"I would run \"tectonic plates convection currents\" through a google image search for a visual stylised 2d representation of what is going on. Broadly speaking what is happening is this:",
"Its all very circular, with the mantle processes driving the movement of the plates, and sinking plates driving the mantle.... |
[
"Topographers: how is topographical data stored?"
] | [
false
] | null | [
"Digital topographic data largely comes in one of two types, point clouds or rasters. ",
"Point clouds are what the name implies, i.e. \"clouds\" of individual points represented by x, y, z coordinates. These are typically raw data, i.e. points represent individual returns from some electromagnetic radiation boun... | [
"since the raster maps are usually projections from straight upwards, you can't have overhangs or -laps in them whereas point cloud can have these"
] | [
"Rasters are relatively easy to work with, largely because there are so many tools designed for image analysis/manipulation. Point clouds are a bit more niche. Both tend to be dealt with in GIS because in almost all applications, topography data that are not tied to their geographic coordinates and projection are u... |
[
"Was cold dark matter always cold, or was it hot in the early universe?"
] | [
false
] | If the latter, at what point did the HDM turn into CDM? | [
"Assuming thermal production: It was hot in the early universe and cooled in the same way everything else did - from the expansion of the universe."
] | [
"For thermal pair production the temperature needs to be in the same range as the mass (kT ~ mc",
") or higher*, which implies the particles are relativistic at that time. As the universe expands pair production stops, things cool down, and interactions get less common as the particle density goes down. The decou... | [
"When we speak of CDM are we referring do the particle being non relativistic at present time or already at time of decoupling?"
] |
[
"How can time pass differelty for 2 objects in relative motion if it doesnt depend on the sign of the speed?"
] | [
false
] | [deleted] | [
"You have described the ",
"twin paradox",
". The resolution comes in the fact that the two twins cannot continuously stay in two inertial frames if they ever want to meet up again - someone must turn around.",
"Also, keep in mind that this is for kinematic time dilation only. The main reason for the time dif... | [
"The time dilation in the movie was provided by the force of gravity of the black hole, not the landing process. Gravity acts locally like an accelerated frame (see the Equivalence Principle).",
"For example, we are currently experiencing a small amount of gravitational time dilation just by sitting here on Eart... | [
"I understand its a movie, but one thing I was wondering that I haven't found much discussion on. Wouldn't the ship that is trying to land on a planet that is effected by time dilation as much as the one in Intersteller have to accelerate to incredible speeds in order to land. My understanding of relativity is th... |
[
"Paradox in the speed of light?"
] | [
false
] | null | [
"When you're talking about special relativity (which is this field), you need to be careful about who's observing what.",
"Imagine we have two people, A and B. A is sitting in a spaceship floating in space, and B comes rocketing by at constant velocity. Suppose that they also each have one of a pair of identical ... | [
"Any discussion of this should mention that there's no such thing as a photon's reference frame. ",
" if you're going to write things like \"the photon in its own reference frame.\""
] | [
"Thanks, good point. I should've made this clearer."
] |
[
"If I took a spoonful of matter from a neutron star and moved it away from the star, would it expand or stay compacted?"
] | [
false
] | Pretty much the title. A how and why would be pretty cool | [
"It would explode and fly apart. It's super hot and the only reason its stuck together is the total gravity of the entire star."
] | [
"how hot are we talking?"
] | [
"That depends on if it's newly formed or not, they emit so much energy within a few years they're sitting at around 10",
" or rather 1,000,000 (one million degrees kelvin) which is about 1799540.33 fahrenheit ",
"when they're just born it's closer to 1,000,000,000,000 one trillion degrees kelvin, or 1.79 trilli... |
[
"Hey AskScience, what's your reaction to Roger Penrose's \"The Emperor's New Mind\"?"
] | [
false
] | I've finished reading it, and it was pretty tough going at times, despite my familiarity with most of the physics involved. I know that people who believe in "strong AI" and think the "singularity" will occur around 2030 have strong misgivings about the idea that consciousness cannot arise out of a sufficiently complic... | [
"I read tENM and first half of SotM ~10 year ago.",
"My thoughts? I really liked his 2 page with the three way test showing Bell's theorem. ",
"Thought he presented interesting, but unproven hypotheses that QM plays a large role in consciousness and that human thought can't be replicated algorithmically with ... | [
"I read the sequel to \"The Emperor's new mind\"; \"Shadows of the mind\", in which he puts forward an extensive argument for why true intelligence and free will can’t be emulated with anything short of quantum computations. AFAIR, all of it is based on the assumption that all that a human mind is can not be simula... | [
"Oh hey, this is my field, sort-of (quantum chemistry applied to biochem). Quantum mechanics ",
" play a role in biology, via chemistry - which is intrinsically quantum-mechanical (something non-chemists just don't seem to know). These are considered 'trivial' examples of QM, since they're entirely to be expected... |
[
"If alcohol is a toxin, does that mean that inebriation and the after-effects of drunkenness is basically the body's response to a poisonous substance?"
] | [
false
] | null | [
"I don't feel you've had a very good answer here at all.",
"Alcohol is a toxin but like most (all) toxic substances toxicity is a function of dose. By and large irregular, moderate inebriation is not sufficient to bring on most of alcohol's toxic effects (damage to the liver, heart, pancreas, increased cancer ris... | [
"The withdrawal hypothesis for hangovers has very little evidence to support it. ",
"The acute hangover effects are now known to be because alcohol disregulates cytokine release. Sufficient cytokine release brings on nausea, headaches and fatigue in people",
"There are long term neurological effects for heavy d... | [
"How can you call methanol, CH3OH more complex than ethanol, CH3CH2OH? My understanding is methanol is far more poisonous because it's ",
" and doesn't break down as easily as ethanol."
] |
[
"Why does a spacecraft re-entering the atmosphere appear to be 'on fire', then when it gets closer to earth the 'burning' stops, even before parachute slowing?"
] | [
false
] | null | [
"In the outer atmosphere, the atmosphere is very thin and therefore causes a lot less air resistance, allowing the craft to achieve much higher speeds. As it reaches the denser atmosphere, it still has the previous speed but is now experiencing greater atmospheric friction, causing the hull to heat up and start glo... | [
"It's the effect of shockwaves. As the spacecraft that comes back from orbit is moving through the atmosphere it has to push air out of the way. Any moving object will push air in front of it, and cause pressure waves to propagate; but in this case, as the vehicle is much faster than sound, it moves faster than the... | [
"Thank you. Does terminal velocity play a part?"
] |
[
"Is the nucleus of an atom a sea of quarks without clear boundaries between protons and neutrons?"
] | [
false
] | I am aware of the quantum stuff that means we can't know exactly where the protons and neutrons are but that's not what I mean. Since both are made of quarks, ups and downs I think, are the quarks just all together in one big soup instead of being bonded to two others like in diagrams? | [
"No, it’s more of a sea of nucleons/quasiparticles (nucleon pairs, alpha clusters, etc.). It’s not simply a homogeneous sea of quarks."
] | [
"Every nucleus has a well-defined A (mass number). That’s the total number of nucleons that make it up. It’s not necessarily trivial to partition them into clusters. For example, certain states in carbon-12 are well-represented by clusters of three alpha particles. Other states in carbon-12 might be better describe... | [
"So when you say \"sea\", are we talking a concrete number of particles? Like \"48\"? Like \"roughly 3 million\"? Or is it really just a noisy mess of an uncountable amount particles bouncing around randomly (aside from some rough clustering or something)? "
] |
[
"What is the temperature of steam off the surface of boiling water?"
] | [
false
] | Realistically when I boil water, can the steam go over 100C? | [
"For the most part, steam immediately above the surface of boiling water will be exactly 100C, or whatever the boiling point is at your particular air pressure. The steam will be in thermal equilibrium with the liquid water, so it won't exceed its temperature.",
"If you want to get steam that is hotter than 100C... | [
"Yes, if the lid forms an airtight seal. If the steam periodically lifts up the lid fully, you can divide the weight of the lid by the surface area to get the difference in pressure with the atmosphere. (If the lid is partially lifted up the pressure doesn't support the whole weight, so the calculation is a bit mor... | [
"Which is how automatic rice cookers work... By detecting the increase in temp when the liquid water is all gone. "
] |
[
"Assuming all else equal, why do women find it harder to get pregnant as they age?"
] | [
false
] | I know a couple of my friends (late 20s - early 30s) are finding it really difficult to conceive, and now they are taking herbal tonics to try to "produce more sperm or make the womb 'fertile ground'". Some have even taken 1-2 yrs just to conceive. But yet, some of my friends (between 19-23) can conceive without battin... | [
"While I agree with your stance on alternative medicines, your response isn't helpful or constructive."
] | [
"Women's eggs form before they are born. A 32 year old woman's eggs are older than she is (her age goes from her birth). Those eggs have been sitting there \"cooking\" for a long time. In contrast a man's sperm is just weeks old."
] | [
"Panzer is correct when they say that women have a set number of eggs throughout their life and as they age this decreases. However that directly doesn't affect their ovulation, which is the real problem when discussing pregnancy.",
"There are two main reasons why the older a women is the more difficult it is to ... |
[
"If I was floating in the vacuum of space and I threw a credit card or a rock by me, would it orbit around me like a moon?"
] | [
false
] | null | [
"Let's just say it's you and the card/rock, nothing else. If your mass is, say, 100 kg, and you are a sphere of radius 30 cm, then the escape velocity for a particle on the surface of your body is about 200 μm/s.",
"When you simply let go of an object, you don't let go of it perfectly. You give it some velocity, ... | [
"To put 200 μm/s in perspective, an object that can travel about an inch in 2 minutes and 7 seconds."
] | [
"That's not true. Although it's common to treat objects as point masses when dealing with gravity, this only works for objects that are reasonable approximations to spheres. For a more complicated object, you have to include higher order multipole moments, and the solutions you get for the motion of the orbiting bo... |
[
"How to determine if someone has received a vaccine?"
] | [
false
] | Noticed a news report today about a state of emergency being declared in New York because of a measles outbreak. In the article it mentioned that “Rockland County, on the Hudson River north of New York City, has barred unvaccinated children from public spaces after 153 cases were confirmed. Violating the order will be ... | [
"Yes, you can. Basically, they draw blood and then put bits of virus/etc. in the blood sample and test to see if the immune cells react by producing antibodies.",
"However, usually they just ask parents to provide official forms signed by their doctor that they've received the vaccination."
] | [
"It is directly determined by how well immune cells can remember it, which in turn depends on the nature of the specific virus. Some viruses are harder to generate effective immune responses against than others. People can also be genetically better or worse at generating immune responses to certain viruses.",
"I... | [
"Thank you! Do you know why some vaccines last longer than others? Does it have to do with how well immune cells can remember it, or is it more about the nature of the specific virus?"
] |
[
"What really causes death when you die of \"old age\"?"
] | [
false
] | I've wondered if there are specific organs/body function which tend to just fail when you are old or if it's rather a general weakness your whole body can't deal with | [
"The term \"death from old age\" itself isn't very scientific, as it can point to death from any number of causes, which may be associated with aging. ",
"As people age, we begin to see deficits in cellular function throughout the body. Normal, healthy cells which have been isolated from patients tend to reach a ... | [
"Doctor here. Couldn't compete with ",
"/u/Kegnaught",
"'s response, but more simply: death from \"old age\" is a layman's term. When we sign death certificates we try to put in a cause of death that is more specifically proximate: in my experience, most often kidney failure. When you get very weak and frail yo... | [
"Thanks very much for your explanation! Seems like aging processes are far more complex than I imagined... "
] |
[
"Sometimes if I open a non-.txt file in Notepad, I see what appears to be a collection of random characters. What exactly am I looking at?"
] | [
false
] | null | [
"You're looking at the content of the file converted into readable characters. For example, let's say you open a ",
".exe",
" file in Notepad. You'll see a lot of seemingly \"random\" characters, which appear to make no sense. However, what you're seeing isn't designed to be displayed as text. Instead, it i... | [
"Fun fact: All executable files in Windows, and in MS-DOS before that (all .exe, .sys, .dll files, etc.) start with two printable characters: \"MZ\". You will see them if you open the file in Notepad or a hex editor. Why? Because the Microsoft developer who created the file format in the early 80s was named Mark Zb... | [
"All files on a computer (be they text, programs, images, or whatever) are a stream of bytes. Each byte is a value from 0 to 255.",
"On their own, bytes are ",
" but they aren't ",
" [1]. To be useful information, you need to ",
" the data in the correct way. Depending on what your binary file is, the corre... |
[
"Does salt accelerate rust formation?"
] | [
false
] | null | [
"On plain carbon steel and irons yes very much. Especially salts with chloride. ",
"Oxidation (rust) by itself on steels and irons is self limiting. The oxide layer prevents more oxygen from getting to the pure Fe. Chloride fucks up the formation of iron oxide films and constantly exposes fresh Fe to the environ... | [
"One of the most important conditions is also abundant free oxygen which, in reaction with water, can form iron oxy hydroxides (rust).\nIf you have a sunken ship lying in the oxygen poor deep sea then it takes couples of decades for it to break down. And even then (in case of the Titanic) it's mostly driven by anae... | [
"If you mean salt in an aqueous solution, yes very much so. Corrosion is an oxygen-reduction reaction, this process involves a transfer of electrons. Therefore, the presence of salt or electrolytes in water increases the electrical conductivity of the water and thus accelerates and promotes corrosion. ",
"This i... |
[
"Why did CPUs stopped at around ~3-4GHz?"
] | [
false
] | null | [
"That top answer gives part of what is happening, but doesn't put it into the right context for a layman.",
"There is nothing magical about the number 3-4 GHz. IBM developed a part which exceeds that (",
"http://en.wikipedia.org/wiki/POWER6",
").",
"What is happening is as much limited by economics and eng... | [
"See:",
"http://www.reddit.com/r/askscience/comments/ngv50/why_have_cpus_been_limited_in_frequency_to_around/",
"\n",
"http://www.reddit.com/r/askscience/comments/y8anh/why_do_i_have_cpu_with_8_3_ghz_cores_and_not_1_24/"
] | [
"Why? Clock speed is an arbitrary and not particularly good measurement of usefulness, just like the number of I/O ports or the number of cache lines. Computers are tools just like cars, hammers, and guns; designing and building them is particularly capital-intensive too. Bringing a CPU to market is a hundred-milli... |
[
"Is it possible that two people have the same fingerprint? Or at least that they're undistinguishable?"
] | [
false
] | I know that every kid in elementary school learns that every human has a unique fingerprint, easily distinguished from other's but there isn't an infinite number of patter on a tiny fingertip, is it? So is there a chance that two humans actually have fingerprint that e.g. the police could mix up? | [
"As far as we know, fingerprints are unique, but they can be very similar. Especially when you consider the fact that the latent prints found at a crime scene are often just partial prints that are smeared, smudged, and missing information, it's certainly possible that a false positive could occur. Most famously an... | [
"To add to this, it might be useful to understand how fingerprints are formed. When an individual is still a foetus inside their mother's womb, they are very subject to pressure. When the baby makes contact with anything, be it through their fingers touching or their toes, the resulting pressure forms \"friction ri... | [
"Interesting topic. Hope this helps."
] |
[
"What do different refractive indecies affect light?"
] | [
false
] | null | [
"Hi TheDiamondOr1 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 f... | [
"Physics"
] | [
"'Physics'"
] |
[
"What exactly does blood type mean?"
] | [
false
] | Does your blood type affect any aspects of your personality, physique, health....etc? | [
"You need to understand two concepts for blood type:",
" are special immune proteins that float in the plasma of the blood and attack foreign particles (anything that doesn't exist in the body itself). ",
" is a general term that signifies what the antibody is attacking. ",
"On our red blood cells some of us ... | [
"There are 8.\nA+\nA-\nB+\nB-\nAB+\nAB-\nO+\nO-",
"which, by your nomenclature, would be ARh, A, BRh, B, ABRh, AB-, ORh, O. The nomenclature is different because people noticed the difference for the A/B/O types first. A and B are co-dominaint, and O is recessive to either A or B (or AB). Rh is only relevant du... | [
"Haha I was waiting for someone to bring up the Bombay type. I'm not sure that Bombay type will make a lot of difference for anyone practicing outside of India, it's more a curiosity for most non-medical personnel practicing outside of the area but yes you are absolutely correct. They will show up as \"O\" on a ty... |
[
"Does nicotine have any merit as a pharmaceutical drug?"
] | [
false
] | [deleted] | [
":",
"Nicotine, as well as other nicotinic drugs, may provide useful therapeutic treatment for a variety of cognitive impairments including those found in Alzheimer’s disease, schizophrenia and attention deficit hyperactivity disorder ADHD . We have found that nicotine skin\npatches significantly improve attentio... | [
"According to many current studies the process for such gastrointestinal diseases as ulcerative colitis can be inhibited by the use of nicotine. Patients with ulcerative colitis who stop smoking have a substantial increase in flairs. The use of patches and a reintroduction of the habit see an immense reduction as w... | [
"http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2014383/"
] |
[
"Since the Earths orbit is elliptical shouldnt the seasons be slightly shorter or longer?"
] | [
false
] | Does the elliptical orbit cause a sort of "slingshot" effect that increases acceleration? I've noticed that spring and fall seem to last a bit longer but that could be due to geographical location (Massachusetts) | [
"Earth’s orbit is technically elliptical, but only barely. The difference between its maximum and minimum distances to the sun is only ",
"about 3%",
". That’s not enough to significantly affect the seasons."
] | [
"The main cause of seasons is the earth tilting on its axis when the northern hemisphere tilts away from the sun that's when you get winter because the days get shorter and the sun's rays have to travel longer through the atmosphere. I'm not aware that the distance from the sun has too much bearing on this."
] | [
"I think the other answers have misunderstood your question. Earth’s orbital speed at perihelion is about 3.4% faster than at aphelion (30.29 km/s vs 29.29 km/s), using values from ",
"this Wikipedia article",
". This has a small but significant effect on the time spent in each part of the orbit, but if you loo... |
[
"Does the ring around Saturn actually have an effect on the climate of Saturn?"
] | [
false
] | null | [
"This is currently not well known, but is a very active area of study.",
"The rings cast a fairly significant shadow on the planet",
", meaning there's less sunlight absorbed in the winter hemisphere than would happen without them. However, it remains unclear how important that sunlight is to the climate.",
"... | [
"Just being in a lower energy state doesn't produce any energy (remember, energy's never \"produced\", only transferred). ",
"When the hydrogen and helium are mixed, they are in a higher-energy state than when they are separated. It's very similar to holding a ball up in the air and letting it fall. The ball i... | [
"Never have I seen this concept so well explained! Thank you very much!"
] |
[
"Seeing colors from a black-and-white strobe?"
] | [
false
] | Today I was in the showers at the gym - white tiles on the walls - and one of the overhead lights was flickering. After about five minutes, all of the sudden my vision became overlaid with red and blue spots and lines. It went away pretty quickly if I looked at the better-lit half of the room, and would start again whe... | [
"You probably experienced a ",
"Fechner color effect",
" similar to ",
"Benhams's top",
". It's not really understood, and vision scientists have long debates about both what's happening and where it's happening.",
"Try buying or making a Benham top. They're really amazing to see IRL.",
"My guess is tha... | [
"I'll definitely have to check out the Benham top. Thanks for the answer!"
] | [
"No problem. Cool observation!"
] |
[
"Is it common for other animals to have their closest biological relative be as distant as chimpanzees are from humans?"
] | [
false
] | Chimpanzees are the closer to humans than any other extant species in terms of shared DNA and where they would fall on a taxonomy chart. But just looking at the two species, they seem to be very, very different. Is the biological distance between humans and chimpanzees as wide as it seems when compared to the distances... | [
"The bigger reason for the perceived difference is that the other, closer groups to modern humans are extinct. Humans and chimps diverged between 4 and 13 million years ago. So broadly speaking, the answer to your question is no, it isn't particularly common for a species to have its closest extant relative be in a... | [
"Thank you, this was a great answer.",
"The aardvark is so lonely! And is exactly what I was looking for. That and ",
"the answer to your question is no, it isn't particularly common for a species to have its closest extant relative be in a different genus",
"that part are the kind of thing I was hoping to le... | [
"Keep in mind that a taxanomic genus is a wholly human construct and we have no consistent (objective) definition of how far apart two species must be before they should be considered to be in different genuses.",
"Chimps are in a different genus to humans for a combination of reasons: historical, scientific uti... |
[
"Why does Ethylene Glycol freeze at -12.9 °C, water freeze at 0 °C, but the mixture of the two freeze (depending on composition) below -60 °C?"
] | [
false
] | Maybe I am remembering college wrong, but shouldn't the freezing point end up somewhere between the two individual freezing points? | [
"I will take the liberty of changing your example, to make it more illustrative. Suppose you mix water and dimethyl sulfoxide (DMSO), instead of ethylene glycol. DMSO has a freezing point of +19°C. Thus, if your memory was correct, mixing DMSO and water should result in a freezing point ",
" than 0°C (but lowe... | [
"The phenomenon is known as ",
"colligative properties",
", specifically ",
"freezing-point depression",
"."
] | [
"You may find this of interest as it gives a pretty good explanation of what goes on when you cool and freeze a mixture.",
"https://www.uwgb.edu/dutchs/Petrology/beutect.htm"
] |
[
"How effective is CPR if applied immediately after cardiac arrest?"
] | [
false
] | So, according to the statistics, the vast majority of patients don't make it, despite CPR (<5 percent survivors), and I wonder if that's the case because it's simply administered too late to be effective. Are the chances significantly higher if emergency measures are taken immediately? | [
"One way to look at this is to compare the survival rates of cardiac arrests which happen outside of hospital compared to those that happen within the hospital. Although the in hospital population may be sicker, it is also reasonable to assume that CPR will be started sooner, and be more effective, for an in hospit... | [
"It depends on the cause of the arrest and the comorbidities.",
"If somebody is having myocardial ischemia which triggers ventricular tachycardia, CPR (with defibrillation, the most important step) is very effective. Of course this needs to be followed with opening the blocked blood vessels, or it will return.",... | [
"One has to take into account the quality of CPR given, which in most cases is atrocious. In areas where serious efforts to improve CPR have been taken, the survival rate is much higher. Seattle regularly reports survival rates which double or triple the national average. "
] |
[
"I want to get back into shape. Is it better to workout over a period of couple hours with short breaks or is it better to work out over a short period of time until you are exhausted?"
] | [
false
] | I've seen some articles and studies that cover the efficiency of long and short workouts but I can't find them now. To explain the title: I am wondering if it will be more efficient to go "all out" for 15-30 minutes until I am exhausted and can't move a muscle or if it's better to work out over a longer period of time ... | [
"Your question would be better asked in the ",
"fitness subreddit",
"."
] | [
"Thanks."
] | [
"I can't speak as much on physically which is more effective at burning calories, but research shows that people trying to get back into shape have much higher success rates, and keep weight off better, when they break their exercise into small 15-30 minute daily routines, rather than long sessions.",
"Long sessi... |
[
"Is earth's electric potential growing or decreasing?"
] | [
false
] | [deleted] | [
"The larger the Earth's net charge gets (whether + or -), the more it repels particles of the same charge and attracts ones of opposite charge. This has the effect of lowering the charge again. It's a self-regulating system."
] | [
"OK, so I didn't know anything about this question beforehand but found it interesting so googled it a bit and you are not the first one asking it. I found these two questions on stackexchange: ",
"http://physics.stackexchange.com/questions/91556/is-the-earth-negatively-or-positively-charged",
" and ",
"http:... | [
"It should be, although it's difficult to measure or calculate"
] |
[
"[Weekly Discussion Thread] Scientists, how do you stay motivated?"
] | [
false
] | This is the twelfth installment of the weekly discussion thread (we took a break last week due to Curiosity landing) and this weeks topic comes to us from the suggestion thread (linked below). Topic: What about your science keeps you motivated on a daily basis? Or more generally, how do you stay motivated while researc... | [
"I work in theoretical high energy particle physics: coming up and evaluating theories for new physics beyond the standard model, comparing their predictions to data from the Large Hadron Collider, etc. ",
"I personally get a big kick out of solving tricky technical problems, which our field has aplenty, and unde... | [
"I hate not knowing. All the motivation I need."
] | [
"As a cancer researcher I try to focus on the fact that my work may one day improve the lives of people suffering for an absolutely disease. I think in general focusing on how your research will improve humanity can be a great motivator; especially when things can be frustrating or certain political aspects of res... |
[
"Why are earthworms more prone to going on the sidewalk during and after rain?"
] | [
false
] | I have noticed they also like to go on the sidewalk in the morning, too. Why is that? | [
"Apparently there are two theories on this, but the both theories are based upon the fact that earthworms do not have lungs to breathe, but rather they breathe through their skin, in a process called diffusion. For diffusion to occur, the earthworm’s skin must be kept moist, so they release mucus to keep their skin... | [
"To elaborate on the drowning bit: earthworms can breathe oxygen through water just as well as air. Worms can live days or even weeks in water. If the oxygen content of the water is low they will drown but rainwater would be oxygen rich."
] | [
"Isn't drowning just a fancy word for asphyxiation in a fluid?"
] |
[
"How can 2 things traveling away from each other at the speed of light both be traveling at less than (or equal to) the speed of light?"
] | [
false
] | So if the "speed limit" of the universe is the speed of light. And all speed is relative. Then what is the relative speed of 2 objects traveling away from each other at the speed of light? surely that's 2x the speed of light? How can that be possible and since its probably not, how am I wrong? | [
"Speed does not merely add linearly. It adds according to ",
"this equation",
", which means thats no matter how fast the two objects are going, they will never appear to be going faster than the speed of light.",
"In your case, each object will see the other object as traveling at the speed of light. "
] | [
"Let's deal with things moving at speeds v very close to the speed of light, but not quite there (just because it's easier to work with). Here's the subtle difference. ",
"Suppose you have two cannons which shoot out people moving at v. You point them in opposite directions and fire. Now in your frame of referenc... | [
"Thanks to the Lorentz transformation, lightspeed isn't additive in the way you're suggesting. Special relativity can be strange and almost illogical at times."
] |
[
"Why are some animal droppings always in such uniform shapes and sizes?"
] | [
false
] | Why do animals, for example a rabbit have such uniform shaped and sized droppings? They look like raisins. Do they have a cookie cutter in their bums? | [
"In the colon there are band-like structures called taenia and out-pouchings of the colon called haustra. There are varying numbers of taenia along the length of the bowel and also between species. As liquid is absorbed from the colon the faeces begins to take shape and the number and size of the taenia and haustra... | [
"Wow can't believe someone got back to me after three days. Very thorough response. Thank you"
] | [
"Hullo, you are welcome! I was struggling to get out of bed and go running and writing that answer gave me a whole 5 extra minutes of excuse!"
] |
[
"Why does a human body has the need to throw up when it is aware of something disgusting?"
] | [
false
] | [deleted] | [
"The Psychology of Revulsion"
] | [
"This is only from a quick read from Wiki but:\n\"The central nervous system mediates vomiting that arises from psychiatric disorders and stress from higher brain centres\". In this case the stress of being surprised and hit in the face, the need to understand the situation quickly in order to deal with it would ca... | [
"Other answers are correct. Here is a shorter answer: vomiting is a simple attempt to discard things that might be poison, and the controls are not very precise."
] |
[
"How is the Sun's corona hotter than the photosphere?"
] | [
false
] | [deleted] | [
"We're not sure",
". "
] | [
"That's probably the best answer, although we're fairly certain that it has something to do with magnetic fields.",
"Magnetic fields, on the other hand, is the astrophysicst's ultimate cop-out answer. "
] | [
"Thanks, guys. It's good to know that we're just still working on the answer."
] |
[
"Why do the sex of the parents matter in creating a liger or tigon?"
] | [
false
] | A is a cross between a male tiger and a female lion. A is a cross between a female tiger and a male lion. As you can see, these two animals look different. Ligers are much bigger. Why would switching the breed of the parents cause such differences? | [
"Great question! This is what I've been trying to address for my PhD dissertation.",
"Short answer: it's probably something to do with genomic imprinting, but the X chromosome plays a big role in all species tested so far.",
"Long answer: There are actually many mammal hybrids that show growth patterns similar ... | [
"Dang! How long have you been waiting for this particular question to crop up?"
] | [
"I was always taught it was just a naming convention for hybrids: first part of the name is from the male and second is from the female. Is this just not true or oversimplified?",
"Also, I'm a semester away from an undergrad in Conservation Biology and am looking at Hybridization as a possible area of research fo... |
[
"Why is New Horizons not flying closer than 7750 miles from Pluto's surface?"
] | [
false
] | Wouldn't flying closer yield more/better data/pictures? | [
"because 7750 miles is extremly close for a planetary flyby. there is the chance that any closer would cause the ship to go of course due to the gravity of the planet, or that a slight miscalculation would place the ship closer than expected. the windows of tolerence would then be smaler as to not allow the craf... | [
"it's final goal is the Kupier belt. placing it in orbit would mean it needs a lot of fuel to slow down and then even more to escape the gravity of pluto again. just not feasible."
] | [
"What will it visit there? "
] |
[
"Why are there states of matter (like solid, liquid, etc) instead of just smooth gradient from solid to gas?"
] | [
false
] | null | [
"There's a number of things to consider with this. The existence of discontinuous phase transitions can be predicted by characterising (or grouping) the states of matter by their symmetries. A gas has continuous translational symmetry while a solid crystal doesn't. So if you want to transition from a solid to a gas... | [
"To complement \\u\\Appaulingly's excellent answer, succinctly: The constituent molecules are either fixed in place or they're not (classic distinction between solid and liquid). The surface tension is either positive or it's not (classic distinction between condensed matter and gas).",
"Edge cases: Maybe many of... | [
"What about that drop of pitch that seems like a solid but it dribbles a bit once every 20 years?",
"See the very last part of my comment. The pitch is an amorphous solid or equivalently a very viscous liquid and so you can transition between them via a second order glassy phase transition (continuous phase trans... |
[
"Where do the symbiotic bacteria in human gastric systems come from?"
] | [
false
] | So, I understand that we have quite a few different little microbes that we co-exist with, like the various bacteria and such in our intestines and gastric systems. My question is how do these things get there? Do we carry the genetic information to create them in our genes? Are they passed from mother to child duri... | [
"We don't completely know. Yet. As unwarranted_happines mentioned, we do know that some of it comes from the mother. The birth canal is certainly not sterile, and if the baby is born via a vaginal birth, that can be the \"start\" of colonization. Breast milk is also not sterile, so if the baby is breast fed, th... | [
"Twin studies actually formed the basis for most of todays human microbiota/biome studies. But to my knowledge, those studies are based on twins who lived together for at least their biological formative years. The problem with the \"separated at birth\" idea is that we don't know which portion of the environment... | [
"Before birth, the gut of a fetus is sterile - no bacterial colonization (and human cells do not possess genes to create bacteria). Shortly after birth, bacteria colonize the newborn gut. Studies like ",
"this one",
" and ",
"this one",
" suggest that the majority of newborn bacterial strains are acquired... |
[
"How much of a humans diet is made up of bacteria? Cheese & yogurt, plants and animals?"
] | [
false
] | null | [
"My i also add chemistry and medicine?"
] | [
"My i also add chemistry and medicine?"
] | [
"Hi ",
"/u/MeanderingWarrior",
" ,",
"Unfortunately Reddit only supports one flair per submission. Sorry!"
] |
[
"How can we see the bigbang's light if, as matter, we go slower than the light it emits?"
] | [
false
] | null | [
"Thank you"
] | [
"Thank you"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"/r/AskScience",
"To check for previous similar posts, please use the subreddit search on the right, or Google site:reddit.com",
"/r/askscience",
" ",
"Also consider looking at ",
"our FAQ",
... |
[
"Can we align the direction of an atom's electrons?"
] | [
false
] | , it is stated of the magnet's construction: In a magnet it is the unpaired electrons, aligned so they spin in the same direction, which generate the magnetic field. Is it not true that our understanding of electrons has progressed to the point where we now know that they are quantum variables, that they are mathematic... | [
"Atoms are quantum systems, but the directions of the spins of an ensemble of atoms follow some probability distribution. If you make the external magnetic field very large or the temperature very low (μB/kT >> 1), then the majority of the atoms in your sample will have they magnetic dipole moments aligned with the... | [
"If you cool you magnet from above the Curie temperature in zero field, each atomic spin wants to align with its neighbours. However, since your magnet is pretty big, you will get multiple domains aligned along different directions.",
"The way you can magnetise a magnet (i.e. make its magnetic domains align) is e... | [
"It's a little to misleading to say the electrons \"spin in the same direction,\" electrons don't \"spin\" as a verb, they ",
" spin, which is a property. Spin does not refer to the electron orbiting around the atom or spinning around its own axis, it is a quantum of angular momentum that an electron possesses, t... |
[
"Is there a textbook on special relativity?"
] | [
false
] | null | [
"Yes, absolutely there are many excellent texts.",
"You say you understand calculus, set theory, vectors, etc. So that's great. I'd absolutely recommend learning a bit of linear algebra before attempting to touch special relativity. There's a lot that won't be necessary - singular value decomp, jordan form, et... | [
"There are tons of books.",
"The final chapters of Kleppner & Kolenkow, ",
" do a nice job of introducing special relativity. Purcell's ",
" (vol. 2 of the Berkeley series) has the most easily acessible introduction to how relativity plus electric fields leads to magnetic fields.",
"Taylor & Wheeler, ",
... | [
"Thanks for the help. I should have mentioned that I understand Linear Algebra quite well, as well as PDE's, tensors, ect. I am an engineer, after all. I guess I just assume everyone knows what math engineers know."
] |
[
"Does the colour of clothes you wear affect whether or not you attract insects?"
] | [
false
] | Well? | [
"some (many) insects LOVE yellow! We used yellow plates filled with ethanol to catch insects in the field. Our prof assured us that the yellow plates work much better than other colors.\nAlso I've made the experience myself that yellow stuff tends to attract more insects than lets say brown stuff.",
"A quick goog... | [
"It isn't just flowers insects are attracted to. I live in a temperate region, we grow a lot of crops. Many crop pests must find the crop each year (because they \"hibernate\" somewhere else or just move up from the south). They also often rely on color for this. Insects like aphids will fly more-or-less randomly t... | [
"Insects that do like these colors are usually ones that flowers want to attract, and as we know flowers give themselves bright colors and even \"landing pads\", black lines pointing to the center of the flower, to grab the attention of pollinators. They can't always tell the difference from you wearing a bright, f... |
[
"Do local sea levels in the ocean change with the seasons? In other words, is there a \"tidal\" high and low that is driven by temperature instead of the moon?"
] | [
false
] | The ocean's mass will remain about the same, I understand that. But water's density is a function of temperature, so given a difference in the temperature of a region of the ocean in winter and a region of the ocean in the summer, the density of the ocean will vary. Assuming the following conditions (one being ocean in... | [
"Surface temperatures ",
"don't really change that much",
" either - maybe 40 degrees F / 22 C in a strongly seasonal place like Wood's Hole. This is because the ocean is an incredibly good heat sink.",
"The seasonal swings are also more or less confined to near the surface. Seawater is densest around 4 C. Wa... | [
"First of all, where are you getting these numbers? 32 degrees C is almost body temp and 80 degrees C is almost boiling. Your densities also don't match what I looked up for both 80C and 80F",
"Second, you can't really work out new radii like that for spheres. Using a very simple approximation of the Earth as a p... | [
"As noted by the others, ",
"1) your estimates of sea surface temp are mostly likely meant to be Fahrenheit and are a pretty extreme (unrealistic) seasonal change for any one location and ",
"2) the seasonal cycle in temperatures only really stays within the ocean mixed layer (top ~50 meters or 150 feet of the ... |
[
"Why do some people have straight creases on the insides of their forearms, even though they aren't fat?"
] | [
false
] | A couple of my friends and I have a straight line on both forearms near the "elbow pit" (related I found online). Thing is, neither of us are, or ever were, fat enough to have fat folds in that area, and there is no way to bend our arms in such a way that the crease starts to wrinkle/fold. Is this a lasting result of b... | [
"I have it too. No idea why."
] | [
"There is no published scientific research suggesting hypotheses that could explain this phenomenon, nor can I think of a means to test any such hypotheses that one could propose."
] | [
"I was formerly fat (320 @ 5'6\") and I ",
" have one. "
] |
[
"Could you imagine an equivalence between mathematical models and computer models in natural science?"
] | [
false
] | I have found myself fiddling with the idea of representing what we know about our physical universe in computational terms. I'm not talking about adding the governing equations to a program, or monte-carlo simulation, no I'm thinking about representing it in a pure object-oriented way. Say you define some objects, that... | [
"I'm not quite sure what you're talking about, but maybe you'd like this article:",
"http://arxiv.org/PS_cache/arxiv/pdf/0903/0903.0340v3.pdf"
] | [
"I think I get what you are saying... but I'm not sure how useful it would be.",
"\nThe major issue with this is that it would rapidly become far too computationally intensive to be of any use.",
"\nFor any system of interacting 'objects', the time taken to simulate them will rise with roughly the square of the... | [
"It sounds like you are describing a discrete event simulation. They've been around for a while; Simula67 was the first Object-Oriented language, and it was designed to do simulations of object interactions. I'm guessing this is not interesting to you though. However, if you would like to see something interesting,... |
[
"Where does it go?"
] | [
false
] | When a living organism dies, where does the energy dissipate too? Can someone give a detailed explanation of the process? | [
"The energy? If you mean the heat, it dissipates into the surroundings. If you mean the chemical energy in the molecules that make up the organism, then those are incorporated, digested and used by whatever decomposes the body. This, also, eventually will end up as heat energy. If you mean something else, then ... | [
"The actual energy goes into the ground, while the organic remains will nourish other organisms that will be lucky enough to stumble upon the remains. Quite beautiful if you ask me.",
"Neil De Grass Tyson had something very interesting to say about this ",
"video"
] | [
"The energy is in the form of electrical chemical bonds throughout their body, and those bonds get broken as things, mostly bacteria, eat the organism."
] |
[
"When a rocket lifts off, is the entire weight borne by the nozzle assembly?"
] | [
false
] | If so, what specific part of the nozzle(s) bear the weight? How big is this connection compared to the bell of the nozzle? And due to acceleration, do G-forces cause the weight to be greater than the rocket weighs at standstill? | [
"Yes, the entire weight of the rocket (and extra based on the g-force) is borne by the engine bell and combustion chamber. One way to look at the force generated by a rocket engine is to look at the pressure of the gasses in the combustion chamber and in the engine bell, sum them up, subtract the external pressure,... | [
"If you ever first get a look at an engine, the top of the combustion chamber is incredibly beefy, and there's a very, very strong u-joint (or sometimes just a hinge, depending on the configuration and control strategy) that attaches it to the rocket structure."
] | [
"however, one has to be very careful to make clear that this is mostly ",
" forces .. in other words, engine is pushing against the stack, and thats much easier to bear without squishing, while the same forces if they were ",
", equivalent of say lifting the rocket upside down by grabbing the nozzles, would qui... |
[
"What is stopping the vacuum of space from pulling everything off of the earth?"
] | [
false
] | [deleted] | [
"The Earth has a gravitational pull due to its collective mass. Vacuums are the absence of particles and do not have a force associated with them. Perhaps you are thinking of opening a box full of air in a vacuum and all of the particles escaping. That's because the pressure inside the box is forcing the particles ... | [
"In the case of things on the surface of the earth, they are surrounded by gas from all sides except on the bottom, so the end result is that gas (atmosphere) on the top side pushes them towards the side with no gas (bottom side), resulting in what we call atmospheric pressure.",
"This is not correct. Atmospheric... | [
"Vacuum doesn't pull on things. It's gas that pushes on things, and if you have gas on one side of a thing (for example, atmosphere pushing on liquid in a glass) and less concentrated gas on another side of a thing (for example, on the end of a straw that you are sucking on), then gas will push the thing from the s... |
[
"Why, in times of life-threatening danger, do humans oftentimes have more fright about siblings or loved ones over their own safety?"
] | [
false
] | From an evolution point of view to, me, saving themselves would increase their fitness and their ability to reproduce successfully. | [
"Taking care of others is selected-for, from an evolution standpoint. As a species that has only one incapable offspring per year, the mothers and fathers that chose to \"drop everything and run\" in the face of danger simply didn't pass on their genes.",
"Since we see this affection in many lower mammals, from ... | [
"This is largely what the book \"The Emperor's Embrace\" is about (emperor penguins). Note, a lot of that book is wild speculation, but some of it is still quite sciency. There are probably better resources but I'm not expert.",
"Reproducing successfully means that one's offspring need to reach maturity, not just... | [
"Hi! Welcome to ",
"/r/AskScience",
"!",
"In this subreddit, we enforce a policy where top-level comments (direct replies to the original post) must be factual answers to the question, preferably with citations, or follow-up questions.",
"Check out the sidebar and ",
"guidelines",
" for more information... |
[
"[Physics]What is Quantum dot?"
] | [
false
] | What makes them so special? How are they created? How do they work? What are the future applications for them? Just interested in everything about them! Thanks. | [
"Basically it's a small...thingy where electrons are confined and can't escape. They are usually made of tiny (nanometer sized) crystals of materials like silicon or cadmium. Electrons within the dot can have different energy levels, like electrons around an atom. That's why they're often called artificial atoms. T... | [
"Thanks a lot, that was really useful!"
] | [
"Too add more on the fluorescent properties, quantum dots have a wide absorption spectrum, high quantum yield, narrow emission spectrum, and is resistant to photobleaching. This makes it either a good energy donor for FRET, or a superior fluorescent label over organic fluorophores. One unique characteristic is that... |
[
"Why are Herbs tasty? No plant benefit..."
] | [
false
] | After making an awesome curry tonight, I was wondering why some plants have flavors that we find palatable. Fruits I understand - consuming them potentially spreads the seeds, but I can see no evolutionary benefit to Thyme, Rosemary, Mint, etc. I'm sure the percentage of 'tasty' plants to 'non-tasty' plants is tiny, bu... | [
"The main factors break down like this:",
"Some of the tastes we like mimic more dangerous tastes This is especially true of some of the more pungent and/or bitter herbs, where the taste is fairly similar to what you'd get if you ate other plants that are poisonous. In general, animals will avoid those, but hum... | [
"Those are both true, but the phrasing of the initial question made me think he wanted the logic that applies where neither of these are the case."
] | [
"Those are both true, but the phrasing of the initial question made me think he wanted the logic that applies where neither of these are the case."
] |
[
"Can Moons Have Rings?"
] | [
false
] | null | [
"If they can, they'd be very short lived. Rings require a very stable orbit, but with moons, the gravitational effect of the planet is stronger on one side of the moon than the other. This will distort the ring orbit, and without the stability, the debris that makes up the ring will either crash into the moon or ... | [
"Rings require a very stable orbit, but with moons, the gravitational effect of the planet is stronger on one side of the moon than the other.",
"This answer is not quite correct. The same reasoning would say that planets cannot have rings, since the Sun's gravity is stronger on one side than the other, destabil... | [
"I love how you explained this and how it sounded in my head when I read it. "
] |
[
"why don't women get facial hair like men?"
] | [
false
] | null | [
"Androgen levels in men and women differ, and there are areas on the body that are more sensitive to androgens that have hair growth in the same areas in men and women (armpits, genital area). Men produce more androgens. Dihydrotestosterone (DHT) is in much higher concentrations in men, which is mainly responsible... | [
"So it's not \"like men\", since it's vellus hair, not terminal hair. ",
"The difference is testosterone. "
] | [
"So it's not \"like men\", since it's vellus hair, not terminal hair.",
"They get terminal hair too. Some women grow more than others, but you don't see it because they wax, pluck, or shave it off."
] |
[
"When did humans start to use names to refer to each other?"
] | [
false
] | I am asking in the context of the tradition of passing down names and using first and last names or middle names. | [
"I'm going to have to disagree with your reasoning.",
"Names are a part of language: a referent that points to a single individual and can be used in that individual's absence to refer to him/her and only him/her. This sort of behavior more or less requires long-term referential processing (that is, being able to... | [
"No one knows, but you can narrow it down a little.",
"50,000 years ago there was relatively modern behavior, so it is likely earlier than that. Anatomically modern humans were around 200,000 years ago, so I suspect it was earlier than anatomically moderns. The Neanderthal-anatomically modern human ancestor was a... | [
"My guess is: as soon as we started using language. I find it hard to imagine that our ancestors, living in small communities where personal relationships were everything, could have had any significant period where they had words for ",
" without having words for individuals."
] |
[
"How many parameters are needed to describe the complete state of a photon? For a beam of photons?"
] | [
false
] | I was reading today in Slashdot about (optical) Orbital Angular Momentum being used to encode information on a light beam to acheive incredibly high data throughput rates . I had never heard about OAM, and it occurred to me that light might have a few more properties than I had really thought about. So, how much infor... | [
"Direction of propagation is part of the wave vector. Beyond that your reply is somewhat misleading since it implies that there are only 3 parameters (2 if you had lumped in propagation direction with wave vector). It's true a photon can be described using only the wave vector and it's polarization state, but I t... | [
"For a beam, at least in X-ray optics, we usually use energy/wavelength, divergence, intensity per unit area at a given plane, and coherence. ",
"The coherence has two parts, temporal and spatial; the temporal (or longitudinal) coherence is a measure of the monochromaticity, whereas the spatial (or lateral) coher... | [
"No. ",
"http://en.wikipedia.org/wiki/Photon#Physical_properties",
"A photon can be described entirely by its wave vector, polarization state and direction of propagation."
] |
[
"How can astronomers differentiate spectroscopic red shift and the expanding universe red shift while looking at a star?"
] | [
false
] | Just came to my mind. It might be two completely different things tho. | [
"We don't. Motion is motion, and all you can record is the velocity in the direction of your line of sight. Locally, peculiar motions of objects vastly dominate the Hubble flow, but at greater and greater distances, motion from the expansion of the universe builds up and dominates local motions. The Hubble constant... | [
"Awesome thanks :)"
] | [
"70 km per second per MEGAPARSEC",
"To be fair, though, a megaparsec is really not that big in the cosmic distance scale. It gets you out as far as only the very closest galaxies (Andromeda, M33) in our local neighborhood. The closest galaxy cluster is 16 megaparsecs away."
] |
[
"Are emotions a possible requirement for an organism to have human level intelligence?"
] | [
false
] | null | [
"Emotions are not only a possible requirement for an organism to have human level intelligence, they are ",
" for for an organism to have in tact reasoning and successful decision making. Individuals with damage to critical \"emotion\" centers of the brain can no longer live normal lives due to impaired reasoning... | [
"All of those things you just listed are behaviours. Ergo, it is a behavioural motivator.",
"But I think we're using different definitions of intelligence. Intelligence is simply the capacity for more complex reactive behaviour. So more intelligent creatures, like humans, can do more complex things like learning ... | [
"What I am proposing is that an emotion is a precursor to any set of behaviors, intelligent or not. An emotion is characterized by its physiological profile. The body reacts in a certain way, and it expresses the emotion in a very concrete and measurable way. To be sure, some components of the emotion process are n... |
[
"Is there such a thing as UVC-resistant bacteria?"
] | [
false
] | Most news articles about harmful bacterial evolution talk about antibiotic resistance. Is there a similar danger to using UVC to disinfect things, developing bacteria that is impervious to UV damage? Is there something similar for hand sanitizers (alcohol)? | [
"You mean like ",
"? Yep, there's such a thing. Fortunately, not all bacteria are dangerous to humans.",
"https://www.newscientist.com/article/2252786-radiation-resistant-bacteria-could-survive-journey-from-earth-to-mars/"
] | [
"You can still kill it with UV, you just need more of it. In this particular case the bacteria only survived when largely shielded from UV:",
"Although the bacteria in the outer layer of the clumps were destroyed by the UV, these dead cells seem to have shielded the bacteria in the innermost layers, which survive... | [
"An organism that is resistant to UV or alcohol needs expensive mechanisms to resist those broad spectrum hazzards. Those organisms would put a lot of energy into being resistant to those dangers, and would have less resources allocated to rapid reproduction or to evade the immune system.",
"Antibiotics usually ... |
[
"How is it possible for a plane to fly when it is upside-down?"
] | [
false
] | I know that the wings of a plane are airfoils, which causes slower moving air under the wing with a higher pressure to force the wing up. I don't get how an airfoil that is upside-down can still keep a plane in the air. Edit: thanks for everyone who replied! | [
"While wings do typically have camber (the curved shape that causes air over the 'top' of the wing to move faster than the bottom, resulting in a pressure differential providing lift), this is a relatively small component. The biggest contributor to lift is the simple fact that air hitting an angled wing on the lea... | [
"I upvoted your answer to the OP, but I'm downvoting this because bdunderscore is perfectly correct at the level of discourse that I think is appropriate given the OP's level of understanding. You are both correct, and though bdunderscore is simplifying a bit, I think this allows him to offer a bit more insight tha... | [
"A nice, clear post. Here's a nice link about lift from nasa (",
"http://wright.nasa.gov/airplane/lift1.html",
") it's basically what bdunderscore said but it's from nasa, with pictures of the Wright plane, and therefore better ;)",
"It's probably worth adding that many aerobatic planes do not have cambered ... |
[
"Is there something comparable to blood types in other species?"
] | [
false
] | null | [
"There are not just \"something comparable\" to blood types in other species, there ",
" blood types in other animals. ",
"According to a FAQ from the UC Davis vet school",
", blood types (and resulting transfusions) work pretty much the same way in dogs and cats as in people, although they don't have compati... | [
"No, not at all. I mean they aren't compatible with humans. There are many different forms of blood-type ",
" in the animal kingdom. Humans largely share our blood type system with great apes and primates, but not with mammals as distant as canines. ",
"Blood types were actually discovered as a result of experi... | [
"I'm slightly confused by your answer. When you say that they don't have compatible blood-types, what exactly do you mean? Do you mean that you couldn't do something such as a blood transfusion between two dogs? "
] |
[
"If the Internet could be wholly redesigned from the ground up, what standards, protocols etc. would be implemented differently?"
] | [
false
] | null | [
"Assuming we know what we have learned from this internet, DNS would certainly be up for major overhaul.",
"The DNS protocol is responsible for a ridiculous percentage of DDoS attacks because of the quantity of poorly configured open resolvers and the design of the protocol itself, which makes it trivial to spoof... | [
"If we were starting from scratch, we would almost certainly skip ",
"IPv4",
" entirely and go straight to ",
"IPv6",
" or some variant with an equally large address space.",
"4 billion IP addresses must have seemed like an endless supply back in the 80's, but in the last few years we've finally started r... | [
"We'd build in connection level encryption for a start.",
"SMTP would have authentication.",
"DNS would be fixed to prevent spoofing.",
"HTTP(S) is an amazing success that works astoundingly well, so I hope we'd keep that. "
] |
[
"Does drinking alcohol have any effect on the gut microbiome?"
] | [
false
] | null | [
"I'm a science writer who wrote a textbook on gut microbiota & diet with a dietitian and microbiologist... we recently did a quick summary of the effects of alcohol on the gut (see the end of the newsletter):\n",
"https://us19.campaign-archive.com/?u=238be946e37df7502dcf28e29&id=5640bf33be"
] | [
"Thanks, very informative"
] | [
"I don't know specifically about gut microbiome effects, however, I think that pretty much everything you consume has some sort of effect on your organs. Maybe we could ask a more specific question.",
"\"Does alchohol consumption decrease biodiversity in the human gut?\" \nMaybe even more specific for this one."
... |
[
"Will the virus causing COVID-19 disappear/go extinct after everyone gets the vaccine?"
] | [
false
] | [deleted] | [
"Unlikely? It would require mass universal vaccination AND for there to be no zoonotic hosts - no animals that can carry the virus. We were able to eliminate smallpox because there are no animals that carry it. Diseases that have animal reservoirs will pop up again whenever vaccination rates drop below the required... | [
"It is very unlikely SARS-COV-2 will go extinct. It is well documented that many different animal species like cats, dogs, bats, pangolins, minks and more can be infected and transmit the virus. Here's a ",
"USDA report",
" on animals they've identified in the US that were positive. It's impossible to vaccinate... | [
"Smallpox is not really a good comparison, since smallpox had no known animal hosts and was very easy to diagnose and track overall. SARS-CoV-2 has many known animal reservoirs and can be very difficult to track. I think it's entirely possible for us to eradicate a virus like smallpox today, and in fact we're extre... |
[
"How do scientists know that they are assembling dino bones correctly when they often have only a few to go by?"
] | [
false
] | Has anyone ever done an experiment with modern bones to see how close they can get it with only a few frags of bone or mixed bones. I'm pretty skeptical that you can construct an entire animal from only a few broken and mixed up bones. | [
"You'd be surprised by how similar vertebrate skeletal layouts are. This, combined with the wealth of knowledge paleontologists draw on in order to compare the minutiae of a fossil specimens, means relatively few clues will give away details about how the species lived and what other species it resembles"
] | [
"Because even in the most ancient of reptiles ",
"the knee bone is connected to the thigh bone,",
" the Thigh bone is connected to the hip bone, the Hip bone connected to the back bone, the Back bone connected to the neck bone and the Neck bone connected to the head bone. "
] | [
"It's pretty rare to find the entire skeleton all laid out although that does happen at least some of the time for partial or full fossils embedded in sedimentary rock's especially.",
"Beyond that, they can actually look into the fossil to see where muscle and ligaments attached and get an estimate of how large t... |
[
"What controls organ regeneration and why can't humans do it?"
] | [
false
] | null | [
"The human liver can regenerate.",
"The liver is the only human internal organ capable of natural regeneration of lost tissue; as little as 25% of a liver can regenerate into a whole liver.[14] This is, however, not true regeneration but rather compensatory growth.[15] The lobes that are removed do not regrow and... | [
"You're partly right in that stem cells are a good starting point, but complexity is a big deal. As you suggest stem cells can become other types of cell, but need to be properly guided however the level of nuance required for that is not something we're even close to. Remember that human development takes a near m... | [
"Myostatin is just one of very very many growth factors. There's factors for everything. There are two problems with using these guys:",
"In my research I have seen problems with both; for the former, neurons will grow to where the growth factor is and won't leave that area, just squiggling around for a bit. For ... |
[
"If Jupiter was a rocky planet instead of a gas giant, how difficult would it be to land a rover there with the much higher gravity?"
] | [
false
] | null | [
"I obviously should wait for proper authorities to jump in here but from a basic science background it would seem to me that it just wouldn't be possible to have a 'rocky' mass of those dimensions. The pressure alone would produce exotic states.",
"It would depend on the composition of the rocks of course but pha... | [
"This is not the answer you are looking for, but here is a discussion of one hypothesis -- that it would turn into a star.",
"Jupiter's density is 1.33 g/cm3, iron is 7.8, so if it were a solid ball of iron it would have a mass under 10x its current mass.",
"This site says 75+ times bigger to become a star.",
... | [
"The problem on Venus is more the heat, isn't it?"
] |
[
"What happens inside the digestive system when a lactose intolerant person consumes dairy?"
] | [
false
] | null | [
"Your gut just lacks the enzymes to process the lactose, the bacteria that then meet the undigested lactose produce a bunch of nasty byproducts as they make efforts to devour the sugar. They produce lots of gas and the bacteria for the most part can't really handle it so the material just kinda gets shoved along th... | [
"Most mammals, including most humans, stop producing lactase, a pancreatic enzyme that splits lactose (milk sugar) into a glucose and galactose after they are weaned. So lactose intolerance is the normal state. When lactose is consumed, it remains in the lumen of the bowel where it osmotically attracts water leadin... | [
"Well...that's how it expels it, gas forces fecal matter to move at a more rapid pace and to be pushed towards the exit. Also, as ",
"/u/alanmagid",
" mentions, lactose pulls water from the bowels causing it to further accelerate along. ",
"Basically it's like using a high pressure hose to clean a clog from a... |
[
"If I brew coffee with twice as much water but the same amount of grounds, how much more (if any) caffeine will be in the resulting pot?"
] | [
false
] | My intuition says it would contain somewhat more but less than twice as much caffeine. Is that right? Does anyone have a better idea of where in that range you would fall? | [
"It will have almost no effect on the amount of caffeine in the water. Caffeine has a very high solubility in water, especially hot water, so the limiting factor isn't the amount of water used, but the amount of coffee grounds added. Even at room temperature, one cup of coffee with its ~100 mg of caffeine is only... | [
"Partially. Espresso is a smaller volume of water being used to extract a \"normal\" amount of coffee, but one requirement of espresso is the pressure this extraction is done under (~9 bar). These conditions do result in a higher caffeine density than a drip coffee, yes."
] | [
"So is it correct that a cup of espresso is just less water run through a normal amount of ground coffee, which therefore comes out stronger?"
] |
[
"If a new Hubble Telescope was to be designed today, how much more powerful could we make it?"
] | [
false
] | [deleted] | [
"The detectors being used by JWST are a pretty significant difference too. Hubble uses CCD technology, specifically ",
"SITe 2048x4096 sensors",
"(pdf) produced by Scientific Imaging Techologies (in its newer sensor packages). This is a ",
"backthinned CCD",
" with ",
"quantum efficiency",
" over 80% ... | [
"The Hubble Space Telescope has actually been refitted several times in its life, so it's not just using the technology from its original designs in the 80s and its launch in the 90s. So it's not completely old technology.",
"That said, we don't need to be theoretical about the comparison, because its successor i... | [
"The main limiting factor is the size of the primary mirror. This was determined by what would fit in the Space Shuttle's cargo bay. Spy satellites have a similar size mirror (although curved differently for a smaller field of view).",
"The instruments are built with an extremely long lead time and are not off-th... |
[
"In winter, why don't lakes freeze through?"
] | [
false
] | Even if there are many consecutive days of sub-zero weather? | [
"Water has many unique properties, but one of the most important is the fact that the solid form is less dense than the liquid form. [This happens because the volume of the solid is greater than the liquid, due to the bonding as a result of the chemical structure.] The effect of this is that when some water freezes... | [
"In the mountains many do. Kills all the fish."
] | [
"So if it's a big deep lake and really cold weather, it just doesn't have time to freeze through in a typical winter?"
] |
[
"Why does the body use RNA?"
] | [
false
] | When DNA is translated why is RNA used it seems like it would be easier to just use a copy of DNA and not have to have both "T" and "U" and only have to worry about having "T". Or am I missing some important reason as to why RNA is a better option to use? So instead you would have mDNA and tDNA and rDNA instead of mRNA... | [
"It's not \"super obvious\" and kudos to you to wonder about this instead of just taking it for granted!",
"There's a concept called \"RNA World\" where the genetic information was stored in the form of RNA and would resemble what you speculated in the question. However, RNA molecules are not very stable and some... | [
"You have to think about how large a single DNA molecule (a chromosome) is in comparison to the size of a gene that is getting transcribed... it would be an extreme waste (energetically inefficient) to transcribe all that genetic material (millions of base pairs long) for a gene encoding a protein that’s only a few... | [
"Gotcha so it seems the theory is because the use of RNA evolved before DNA? and why reinvent the wheel (switch over to DNA) when you can just continue using what you already have?"
] |
[
"Why is forward, but not lateral, neck immobility a sign for meningitis?"
] | [
false
] | When considering meningitis, doctors check if a patient can tilt his head forward. Why is the forward movement (chin to chest) an indicator for meningitis but other neck stiffness (inability to turn or tilt head to the sides) is not? Disclaimer: of course the question arose from personal interest, but I have already be... | [
"Meningitis is an irritation of the coverings of the brain, called the meninges. Forward neck movement will cause the meninges to stretch and because they're irritated, it will cause pain. Lateral head movement doesn't cause a significant stretch on the meninges and won't cause the same neck pain. ",
"Think of it... | [
"Meningitis is an inflammation of the meninges, the membranes covering the brain. Any pressure or force applied to the meninges will hurt so the dorsal neck musculi get rigid to counteract any lenghtening movement of the membranes.",
"This is not limited to neck, for example there is the Laseque test in which one... | [
"I think you meant Kernig's sign. The Lasegue test, aka Straight Leg Raise, is diagnostic of spinal stenosis. "
] |
[
"During early ambiogenesis is there really a need for stable lipid bilayer enclosures or can they extremely dynamic?"
] | [
false
] | My basic conception of early ambiogenesis is that early nucleotides were free floating in the "soup" and dynamic lipid bilayers would be rapidly forming and falling apart spontaneously. So the early life would basicly be more akin to a viral soup then a cellular soup with the nucleotides only transiently existing wit... | [
"I am not a biologist, but here are my thoughts. Hopefully someone more knowledgeable on the topic will come along. ",
"There would need to be some sort of a boundary. It wouldn't necessarily have to be made of lipids perhaps it could be as simple as small pockets in a rock (really getting outside my area of expe... | [
"I am not entirely sure how to interpret your question. Ill give it a few stabs and hopefully something will hit the target. If not, feel free to keep asking or maybe somebody has a more helpful answer. Number 1 may be a bit hard to understand -- it certainly is hard to explain, but if you ever take a high level th... | [
"Abiogenesis?",
"Firstly, there are fossils of cellular structures from 3.5 billion years ago, so millions of years.",
"Secondly, are you asking what the overall order of molecules evolution is? *NA, proteins, lipids? One point that is missing concerns the nature of the cell boundary : it is possible that it wa... |
[
"VSEPR theory: T-shaped?"
] | [
false
] | [deleted] | [
"The repulsion between a lone pair and a bond pair is stronger than between two bond pairs. With trigonal planar each lone pair is at 90 degrees to three bond pairs. With a T-shape, each lone pair is at 90 degrees to two bond pairs, but is at 120 degrees to the remaining one. The average distance between bond pairs... | [
"Also, if you accept that d-orbitals are too high in energy to participate in bonding for main group elements, you cannot fit four unshared electrons in one p-orbital (that would be left over if the three sp",
" orbitals were occupied), so the unshared electrons must occupy sp",
" hybridized orbitals. "
] | [
"With a T-shape, the lone pairs are 120 degrees away from one bond and 90 degrees away from the other bond. With a trigonal planar shape, the lone pairs are 90 degrees away from every bond. This ends up being more significant to the shape than having the lone pairs 120 instead of 180 degrees away."
] |
[
"What does Accutane do to get rid of your acne?"
] | [
false
] | null | [
"The simplest explanation I can provide (since I'm on my phone), is that it basically stops the production of the oils in your pores that causes breakouts. Everyone's pores produce oils, its when they are over-produced that pores become clogged and inflamed. Due to the way it works, you will have very dry skin (buy... | [
"It works by reducing the sebum(oil) production by your skin, which otherwise fills the pores, becoming blackheads. If these become infected, they become spots. I don't know enough about dermatology past this. For your red skin though, get a chap stick and a moisturiser and use it daily or more regardless of how dr... | [
"Accutane = Isotretinion",
"I would recommend reading the wiki article, ",
"http://en.wikipedia.org/wiki/Isotretinoin#Mechanism_of_action",
"It is informative and all that good stuff. I too used Accutane, did the job and some other stuff. Be careful with it and if you get depressed during the treatment, tell ... |
[
"Why do mice experience senescence at such a greater rate than humans that their lifespan is almost around 1/40 of ours?"
] | [
false
] | It's not as if they have 40 times the metabolism, or that their cells divide 40 times faster than ours. Do they really accumulate free radicals, plaque, and genetic mutations at 40 times the rate we do? (thanks to Avedomni for rephrasing the question) | [
"Because of natural selection. ",
"It sounds like you are familiar with the idea that aging is the result of a cumulative physiological process, but that is not necessarily true. The current thinking is that aging is imposed by evolutionary pressures.",
"Here's a good ",
"talk",
" that gives a brief overvi... | [
"There's probably a lot of truth to that, but here's a paper dealing about the contrasting view--that metabolic activity has something to do with it. Just for balance. I'm not sure I agree with Rose on everything, but the flies are certainly cool.",
"edit: forgot the link like a fool\n",
"http://jeb.biologist... | [
"Mice do not appear to accumulate mutations at 40 times the rate as humans, nor do they accumulate that many more free radicals. ",
"Beyond that, I think ron_leflore is on to something. If you think about mice in the wild, it's unlikely they'd live that long, so the fact that they can even live 2 years in a lab... |
[
"Do the spinning wheels on a vehicle create centrifugal force?"
] | [
false
] | I know that all rotating circular objects create some kind of centrifugal force but do the spinning tires on a car play any part in creating the grip to keep it grounded? Does the force generated vary at different velocities? Do engineers know when and how to utilize these forces in designing vehicles and tires? | [
"do the spinning tires on a car play any part in creating the grip to keep it grounded?",
"It's the friction between the rubber and the road that creates grip. The friction is due to the weight of the car. The centrifugal force doesn't add any extra grip.",
"Does the force generated vary at different velocities... | [
"Thanks. Got the answers I wanted :)"
] | [
"Not that simple, there is such a thing as centrifugal force.",
"If a rotating object is being pulled towards the axis of rotation by centripetal force, why does it not accelerate towards the axis? There must be a component of force opposite to centripetal force pulling directly away from the axis of rotation...... |
[
"Why are our veins asymmetrical?"
] | [
false
] | I would think that since most things in our bodies are symmetrical, that our venous channels would be as well. I was looking at my arms today and found it strange that my veins are quite different in each forearm. Does this have something to do with development, or are veins just formed randomly? Do our veins change lo... | [
"Veins aren't exactly formed randomly, but there are random elements in how they are formed. Identical twins will have different vasculature, for example.",
"This is because the body doesn't have a blueprint in the traditional sense, it is procedurally generated. Limb buds set up gradients of hormones that tell b... | [
"I've never heard the term \"procedurally generated\" to describe human embryology and vascular formation. That's incredible. "
] | [
"That's why the human genome is only three gigabits in size. You only need that and a bootstrap platform to build a human."
] |
[
"Can I say that future points downwards?"
] | [
false
] | Suppose a 2D flatlander orbiting the earth aligned in a plane perpendicular to its velocity. Can I say that his future points in the direction of his velocity? If thats's the case, then his velocity is already pointing somewhat towards his earth-facing direction (a direction he can point towards in his own sense if he ... | [
"But the flatlander doesn't have a downward to point in, in the sense you're using down. Just the same way, if we assume your analogy is sensible, then we'd not be able to point in the direction of our past. But the analogy itself doesn't make a whole lot of sense since you're just pointing in the direction the f... | [
"Uh.",
"I don't exactly understand what you said, but the future usually points futurewards. It can't point downwards, just like \"right\" can't point downwards.",
"And I don't think time can be \"aligned\" with spatial dimensions.",
"/layman"
] | [
"...what? I don't follow your line of thought."
] |
[
"How does the human body digest water?"
] | [
false
] | I vaguely remember learning that the colon plays a key role in absorbing water, but I feel like I am misremembering something. Surely water doesn't travel through the entire body before being absorbed...? Also, are any chemicals involved in the digestion of water, such as stomach acid? Thanks in advance. | [
"When you talk of the digestion of water are you referring to how it enters the body? e.g. through the intestines.",
"I don't know of any mixing of chemicals with water. What I do know is that the water is absorbed through the intestinal walls using osmotic pressure gradients. ",
"It is A LOT more complicated t... | [
"Correct me if I'm wrong, but i think water is absorbed via diffusion not osmosis. It doesn't actually pass through the semi-permeable membrane of the cells, rather it is absorbed paracellularly passing between the intestinal cells. The concentration gradient you described is certainly the mechanism by which this g... | [
"Although that's an impressive figure, roughly 7-8L of fluid will be absorbed in the small intestine before it gets to the ileocaecal valve. so in fact the colon only contributes ~15-20% of the daily GIT absorption of fluid"
] |
[
"Since both a WiFi signal and light are electromagnetic radiation, can I simulate the range of my WiFi Access Point by replacing it with a bright light in a pitch-dark night?"
] | [
false
] | I would probably need to leave all doors open since the WiFi signal has no trouble to shine through them, but it seems that concrete and brick walls are opaque for both WiFi and light. | [
"No. All materials have different absorption and scattering properties of electromagnetic radiation, and these properties are different for different wavelengths of light. Visible light and radio waves will not have the same behavior, especially since houses are such irregular objects made of so many different mate... | [
"I can highly recommend this set of blog-posts on the matter. Basically, the first post uses an approximation and simulates WiFi-signal using ray-tracing, while the second solves the more rigorous Helmholtz equations and the third gives you an app to do the same thing for you (which I haven't tried and therefore ca... | [
"Ray tracing is only an approximation, and it doesn't handle things like wave interference or diffusion. That's OK for the things that ray tracing is used for, like images with reflective surfaces, but it's going to be a pretty bad approximation when you try to use it to model something like wifi in a house.",
"(... |
[
"Do any plant cells undergo apoptosis in a similar fashion to animal cells?"
] | [
false
] | null | [
"To add about the damage to DNA and tumors: many plants are polypoloids, meaning they have multiple copies of their chromosomes creating redundancy if one set fails. With this 'backup' the need to kill off a cell is greatly reduced."
] | [
"To add about the damage to DNA and tumors: many plants are polypoloids, meaning they have multiple copies of their chromosomes creating redundancy if one set fails. With this 'backup' the need to kill off a cell is greatly reduced."
] | [
"also also, plants are generally way simpler than animals and can usually function pretty well even if they develop tumors - trees with massive growths can still function normally (and will produce beautiful burled wood when they're felled). since they don't really have a recirculating blood/circulatory system it's... |
[
"With satellite imagery, have we discovered every mass of land on the face of the earth?"
] | [
false
] | Or are there still islands out there in the sea we have not discovered? | [
"Islands are still ",
"being discovered",
" and will constantly be discovered (and lost) due to natural forces like erosion, ocean level changes, volcanic eruptions etc. "
] | [
"There's a good Magic School Bus episode regarding volcanic island formation.",
"https://www.youtube.com/watch?v=D-JnSEPTlvc"
] | [
"And some of the islands we thought existed never did ",
"http://www.huffingtonpost.com/2012/11/24/sandy-island-doesnt-exist_n_2184535.html"
] |
[
"How did the Ash tree develop a seed pod that could flutter down to the forest floor? How did it know what the best wing design was?"
] | [
false
] | [deleted] | [
"It didn’t know.",
"Survival of the adaptor. Random genetic changes and also response to environmental factors over eons caused the changes. Each incremental change enhanced that genetic line’s survival and gene proliferation."
] | [
"It doesn't know. Seeds naturally vary, however slightly, in size, shape, mass and so on. This is partly due to their genes which, thanks to sex, they all have different sets of. Some varieties are, for whatever reason, a little more likely to germinate and survive to create seeds of their own. Their seeds will hav... | [
" stated, there is no \"why\" to evolution. In fact, some evolutionary traits aren't 100% positive, and are inefficient, like RUBISCO's oxygenase activity. Complete evolutionary flaw."
] |
[
"What happens if an anti-proton collides with, say, a normal neutron?"
] | [
false
] | [deleted] | [
"If they react, at low energy, the most probable result is hadronization into pions. For example, π",
" π",
" is a reasonable product. ",
"This happens, intuitively, if the two pair of corresponding quark antiquark annihilate leaving the resulting energy to the remaining antiup-down pair, which is a π",
" m... | [
"Most likely they will scatter electromagnetically (Rutherford scattering) being like-charged."
] | [
"Most likely they will scatter electromagnetically (Rutherford scattering) being like-charged."
] |
[
"Do point-like particles have hawking radiation at their Schwarzchild radii?"
] | [
false
] | I know we've done some expiriments hinting towards stable or at least meta stable protons but is it possible? Intuitive logic tells me all the fermions would evaporate rapidly and none of us would be here but I'd love some other perspective. | [
"This is an area where the lack of a theory of quantum gravity is important. In theory an electron is a point-like particle, so it should have a Schwarzchild radius that is perhaps larger than it's physical radius (which is effectively 0). In reality though quantum effects dominate at such small scales and the resu... | [
"In reality though quantum effects dominate at such small scales and the result is that you don't end up with a black hole.",
"Well, to be a bit more precise, I would say that the result is that you don't end up with a ",
" black hole. It is possible that all \"fundamental\" particles are extremal black holes, ... | [
"In theory an electron is a point-like particle, so it should have a Schwarzchild radius that is perhaps larger than it's physical radius (which is effectively 0).",
"The schwarzchild radius for an electron mass is like 10",
" m, way way less than a planck length (even though the schwarzchild metric doesn't wor... |
[
"what causes stiffness rather than soreness after physical exertion?"
] | [
false
] | null | [
"Drink more water."
] | [
"i down bottles of water the whole day. but i didn't ask to stop it, I want to know the science."
] | [
"Ah gotcha. My mistake."
] |
[
"How does Ampicillin act as a substitute for Penicillin?"
] | [
false
] | What are some reasons that say Ampicillin would be much more effective than Amoxicillin? Could this effect be even more pronounced when used in conjunction with Penicillin? Can drugs be exponentially effective? | [
"Both act via inhibition of transpeptidase, which is needed for bacterial cell walls. However, ampicillin's structure makes it more effective against Gram-negative bacteria than penicillin (Gram-negative bacteria tend to be more virulent). Due to this, they would be about equally effective against Gram-positive org... | [
"Ampicillin and amoxicillin both go after the same enzyme that builds the bacterial cell wall. Both these drugs are members of the penicillin class of antibiotics, and as such there would be little benefit in combining them UNLESS there is resistance to one and not the other. Bacterial resistance is accomplished in... | [
"UNLESS there is resistance to one and not the other",
"Ampicillin and amoxycillin are essentially interchangeable, resistance to one usually assumes resistance to the other"
] |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"Theoretically, just barely crossing the equator is enough to change the direction of the Coriolis Effect, with the Coriolis Force equal to exactly zero at the equator.",
"Realistically, though, the Coriolis Force is so minimal when you're incredibly close to the equator that it's essentially impossible to detect... | [
"Helium was also first discovered as an unknown spectroscopic line in the Sun's coronal spectrum during the eclipse of 1868, initially misidentified as sodium. By 1871, this unknown element was dubbed helium because of the Greek word for the Sun, \"helios\". It wasn't isolated in the lab until 1895."
] | [
"The Coriolis Effect: Is there a fine line where in one location a vortex is spinning clockwise and if you move a certain amount of distance (either north or south) your outcome can change to counter-clockwise (or vice-versa)? In other words, what is the shortest distance between the northern and southern hemispher... |
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