title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Can animals tell the difference between babies and adults of different species?"
] | [
false
] | And if they can, do they treat them differently? | [
"Yes. And the reason is for survival.",
"Many species will prey upon the young of other species. There's some species of eagles for example that prey on penguin chicks. Lions will go for elephant calfs and not the adults, etc, etc. But, there are instances where a species' adult will be preyed upon and not the yo... | [
"The OP asked, I answered. I attempted to hit what they were asking to the best of my ability. It's a given that species with a lower cognitive ability wouldn't have the ability to do so. But, there's evidence of parental ability in species of insects (many species of carrion beetles, ants, bees, etc) and in fish. ... | [
"Yes. And the reason is for survival.",
"No. What difference does it make for a fly to tell a young dog from its mother. Would a fish bite the bait of a kid and not of an adult fisher?",
"\"Animals\" is a bit broader then just mammals and birds. People tend to forget."
] |
[
"How does salt bring out sweet flavors in many food?"
] | [
false
] | null | [
"The best answer out there is a little different than that mentioned in other comments... and that's probably because this mechanism was just published this spring. The other ideas you'll here about (blocking bitter receptors... etc.) were the hypothesis out there from before we learned this new piece of info.",
... | [
"I soak pineapples cubes in salt water. The result is that it removes the sourness in the pineapple and it tastes sweeter. How is the sourness removed? I thought it might be because salt somehow neutralize the acid, but I am not sure."
] | [
"Alton Brown (who is the Bill Nye of food) has almost an entire episode about it. Here's the link to the relevant part to answer your question: ",
"http://www.youtube.com/watch?v=dXmzef_vzJI#t=6m50s",
"(Paraphrased) The salt blocks the bitterness taste receptor, which brings out flavors that would otherwise be ... |
[
"Can mosquitoes drink blood that's pooled on the ground or on someone's skin, or do they need to pierce the skin of a live human or animal?"
] | [
false
] | I'd kind of think the latter, because if they could drink blood that was just sitting there, you'd hear about huge clouds of mosquitoes forming around crime scenes! Or have I just not seen enough crime scenes? | [
"They do not have to pierce the skin of a live animal, but in laboratory settings, that's the most frequent feeding route because the animal provides a constant \"renewable\" source of blood.",
"However, there are some issues with using live animals, mainly IRB approval and the cost of maintaining animals. So, pe... | [
"I don't know if mosquitoes ",
" eat spilled blood, but spilled blood coagulates very quickly, so the changes in things like viscosity may make it a bad meal. It's also possible that mosquitoes don't see blood on its own as a meal, they see the animal as a meal."
] | [
"Good point, I hadn't considered that the mosquitoes might not realize that blood is what they're drinking! Reminds me of me and my brothers complaining to my mom: \"There's no food here! Just ingredients!\""
] |
[
"Is it possible for nerves to cause you to shake violently, almost seizure like?"
] | [
false
] | Last night I had a bit of a scare which caused my friends to call 911 for me. My legs started shaking extremely violently, I was extremely dizzy and my heart was beating at about 250 bpm (chest felt like it was about to explode). Since the paramedics were coming from out of town they sent the local fire department ahea... | [
"Well, how else do you think you move if the nerves are not involved? Do you mean the nerves by themselves without input from the brain?",
"Was this a panic attack by the way?"
] | [
"By nerves alone I mean that I had no, or very little, control over it.",
"I'm not sure what it was and neither did the paramedics. It all started happening after a fit of coughs."
] | [
"I see.",
"Well there certainly are some occasions where nerves can do things without conscious input. ",
"For example the reflex reactions - which I ",
" bypasses the brain altogether but you'd have to check that on Wiki. You heart is another example.",
"I'm afraid I don't know enough about it to comment o... |
[
"Does Sodium react to moisture in the air?"
] | [
false
] | null | [
"Yes. Sodium metal is stored submerged in oil to prevent it from reacting with moisture in the atmosphere."
] | [
"The sodium metal reacts with the moisture in the air. When you drop it in water the reaction is more spectacular. NaOH and H2 is formed. The reaction is very exothermic this heat can ignite the H2. \nNa + 2H2O --> 2NaOH + H2",
"Video of reaction: ",
"https://www.youtube.com/watch?v=dmcfsEEogxs"
] | [
"Yes, you have to store sodium metal in oil, and fresh cut sodium metal will be shiny but tarnish quickly."
] |
[
"Help me work out this simple physics thought-experiment. I'm confounded."
] | [
false
] | Suppose you have a friend with a helicopter and a very long length of rope, lets say 1000 meters. Your friend takes the chopper into the air 1001 meters and hangs the rope out of the window, so that the end of it is almost touching the ground, but not quite. Now your friend takes a knife and cuts the rope. Of course... | [
"Your mistake is that when the rope is cut there is nothing holding the bottom up. The bottom layer is being held up by the layer just above it, and so on back to the top. The top layer starts to fall, which allows the next layer to start to fall, and so on until you get to the bottom. This process takes time, acco... | [
"The bottom of the rope is not hanging in the air because of the force at the top of the rope. If you for a moment think of the rope as a series of massless springs connecting a bunch of little spheres holding the mass, then the lowest mass will be suspended due to the spring just above it. This spring is connected... | [
"The bottom of the rope falls at the speed that sound travels through the rope.",
"Or, since the speed of sound solid a weird way to explain it... The end of the rope starts falling when the reverberations from the top of the rope reach it. ",
" happens instantaneously. An easy way to think about this is a 1 li... |
[
"I don't think I've completely grasped the Twin Paradox"
] | [
false
] | So assume twin A stays on the planet and twin B goes on the rocketship. Upon returning, twin B will be younger than twin A. First of all, if all frames of reference are equal, why isn't symmetry preserved? From B's perspective does it not look like A is moving really fast away from the rocketship and then coming back a... | [
" Yes, it is because he must accelerate, but it's not quite that the acceleration makes him younger. Consider this:",
"The \"paradox\" is usually stated as \"from B's point of view, it is A that goes away riding the earth and comes back. So A must be younger than B, but both inertial frames must be valid, so the... | [
"Yes, the acceleration accounts for the difference.",
"\"Have the same age\" doesn't have an obvious meaning since the twins are separated by space. But once they were going the same speed neither would observe the other's clock running fast or slow.",
"What he sees will be determined by the direction of travel... | [
"Thanks for the answers. The article was helpful.",
"Just a clarification on the 3rd question (justkevin said the same thing):",
"Does B see things moving on Earth really fast on his way back as an effect of \"sort of a Doppler effect\" (don't know if Doppler effect applies to light as well) AND time dialation?... |
[
"How do ancestry DNA tests determine where your ancestors were located?"
] | [
false
] | Considering most of the human race died before DNA testing, how can we reference where our genes came from? | [
"My understanding is that ancestry DNA companies use databases of genetic markers/sequences which have been identified to be common in certain groups/regions. For example, they have the DNA of a bunch of people in China and they find genes that occur with high incidence in that population and decide that it is repr... | [
"The problem of under-representation in sample sizes specifically with 23 and me has been more of a problem for people of non-European descent. I got tested and when I looked at the sample sizes for the reference populations, they are as follows:",
"European: 6842",
"East Asian and Native American: 1368",
"Mi... | [
"They test people who live in an area and insist that they've always lived in that area. ",
"They then compare that data with samples from people who are \"trying to find their roots!\" and see where the similarities lie. ",
"As you can imagine, this kind of relies heavily on the people living in an area being ... |
[
"Does cooking food decrease its nutritional value? How significantly?"
] | [
false
] | My health-freak (but often mis-informed) parents were talking about how different methods of cooking an egg can affect the amount of nutrients left after cooking. Apparently boiling an egg destroys all the nutrients, where a poached egg cooked at a lower temperature would retain more. After challenging them with the la... | [
"This guy claims that women on raw diets cannot conceive because of inadequate calories. F'shizzle! -- ok overstated. I'm so used to bad logic here on reddit. -- He claims that normal fertility is an enormous problem for raw foodies. I dont think this is true. (I dont have time to research it but I'm sure.)",
"th... | [
"This guy claims that women on raw diets cannot conceive because of inadequate calories. F'shizzle! -- ok overstated. I'm so used to bad logic here on reddit. -- He claims that normal fertility is an enormous problem for raw foodies. I dont think this is true. (I dont have time to research it but I'm sure.)",
"th... | [
"Chinese medicine suggests we eat mostly cooked food. I read Bob Flaw's book \"The Tao of Healthy Eating\". I own it and it is also on googlebooks where you can read 'almost all' of it.\nIt says that cooking makes the nutrients more available. The only nutrients in the food that count are the ones that you absorb."... |
[
"Why does gallium have such a low melting point?"
] | [
false
] | I tried to find this online, but only could find stuff essentially saying that it just does. I don't really know too much about it. Any help would be appreciated! | [
"From an simplistic/observational standpoint, it's because of the unusual structure of solid gallium. The atoms form pairs (dimers) which are strongly bonded to each other (distance of 2.4 Å, about the same as in metallic aluminum), but weakly bonded to other neighboring atoms (2.7-8 Å distance). For this reason, i... | [
"This is perfect! Thank you very much. I had read the wikipedia article and wasn't able to find a very helpful answer."
] | [
"I am not a chemist, but your question might be too specific. For example, why not mercury or any other material? In some ways your question is actually \"What determines melting point?\" But I do realize your main interest is probably why there is a difference between gallium and its neighboring elements.",
"Wit... |
[
"People always talk about the sun cooling and dying, but what about Earth? Is the centre of the Earth cooling? If so, how long before we feel the effects, and what would those effects be?"
] | [
false
] | How much does the geothermal energy within the Earth actually affect us, up here on the surface? What will happen as it disappears? Will continental drift slow down over time? Or just stop when some threshold is reached? Obviously the timescales will be very long - but I'm assuming that the Earth will cool well before ... | [
"If the oceans boil off, where will it go?",
"In the short term, as it starts evaporating it will produce a steam atmosphere, which will result in a runaway greenhouse effect. Water vapor is a greenhouse gas, so adding more raises the temperature further, leading to more evaporation, etc.",
"In the long term, t... | [
"substantial atmospheric ablation by solar wind.",
"To be clear, though, this would not happen on Earth.",
"Even if/when Earth eventually loses its magnetic field, our planet still has enough mass to hold onto its atmosphere. Just look at Venus, which has a very similar mass to Earth, no permanent magnetic fiel... | [
"You feel the effects every single day. The cooling of the outer core is what results in the geomagnetic field. If the cooling slowed then this can shut off the dynamo (similar to what may have occurred for Mars)."
] |
[
"Is there really even an \"arrow of time\" at all?"
] | [
false
] | If space and time are spacetime, and any object is describable not just by its location in three dimensions, but also by its state in time, then time definitely exits objectively. But, does time actually "move" along in a "direction" outside of our own experience? Is an "arrow of time" an actual property of that dimens... | [
"[... continued from the OP]",
"Without being long winded about evolution and natural selection, it's sufficient to say that something that exists persists while it exists while something that doesn't exist doesn't persist. That's a tautology. And something that perpetuates its existence, perhaps through replicat... | [
"It seems like you didn't actually read my post. Was it too long? I tried not to ramble."
] | [
"First, you've got basically the right picture of objects in spacetime (the idea is usually referred to as the object's/particle's ",
")",
"Second, you haven't removed the need for the arrow of time. As you said,",
"As it happens, entropy is a process that makes any \"later\" slice of the 4D time \"shape\" f... |
[
"Briefly, how do Loop Diuretics deal with Hypertension?"
] | [
false
] | Im extremely sorry if this is the wrong place to ask such a question, but I'm doing a project based on loop diuretics and for a brief introduction I wanna word it as simply as possible how Loop Diuretics deal with Arterial Hypertension. Thanks | [
"The main action of loop diuretics is to inhibit the sodium-potassium-2 chloride symporter in the loop of Henle. This transporter normally brings Na-K-2Cl back into the renal tubule, so inhibiting it causes these ions to remain in the lumen (where the to-be urine is). In the body, water tends to follow ions (sodium... | [
"Not exactly because in this example the water is just remaining with the ions (It’s already filtered out of the blood).\nNormally the ions are re-uptaken by active transport and the water follows by osmosis.",
"Osmotic pressure is the pressure needed to stop the water having any movement at all across the semi-p... | [
"Thanks a lot!! Just one more question, would that tendency of the water to follow ions be better \"scientifically\" described as osmotic pressure or is it different things we're talking about?"
] |
[
"If someone was poking my internal organs, would I feel anything?"
] | [
false
] | Let's say that I am due for sugury and they've cut me open, if I'm awake and not in extreme pain, then would I feel the surgeons messing woth my internal organs? | [
"Thank you :)"
] | [
"Thank you :)"
] | [
"perhaps post that to ",
"/r/anecdote"
] |
[
"Can oral vitamin B12 work effectively if taken sublingually?"
] | [
false
] | null | [
"Oral absorption of B12 is variable and requires several cofactors to transport it across the intestinal mucosa. A sublingual formulation may increase absorption a little, but clinical evidence is really inconclusive on that. \nIf you have a deficiency your best option is to get your levels up to the normal range v... | [
"Absorption of vitamin B12 requires \"intrinsic factor\", secreted by the parietal cells of the stomach. Since it is water soluble, it is somewhat difficult for it to be absorbed through the cell membrane, which generally doesn't allow water soluble compounds to pass through.",
"So sublingual absorption either wi... | [
"Sublingual B-12 is available over the counter widely. Under the tongue, it dissolves in saliva and is swallowed. Little absorption through the lingual mucosa occurs. For people with B12 defiency due to gastric surgery, PPI usage, or advanced age where intrinsic factor is lacking, IM injection is requred."
] |
[
"Have we already observed a moon with a submoon? Is this even theoretically possible?"
] | [
false
] | null | [
"It is possible but would need quite weird conditions to be stable over a long timescale. We have created spacecraft that orbit the Moon (not stable over a long time) but didn't observe anything like this in nature. As rough guideline you want all distance ratios to be large: The moon should orbit very close compar... | [
"There are at least 4 Moons in the solar system that could host a submoon (or moon-moon). Our own moon is included.",
" ",
"These submoons could in fact have stable orbits although they may not be dynamically stable. It is important to note here that if something is dynamically stability it means that the orbit... | [
"Our moon has 4 inclinations where an object can stay in low lunar orbit pretty much indefinitely. They’re at 27, 50, 76, and 86 degrees inclination and are referred to as frozen orbits."
] |
[
"How is DNA interpreted?"
] | [
false
] | I've been trying to find out about the mechanism which interprets or compiles DNA. As I understand it, DNA is a strand of G's, C's, A's and T's, which are interpreted by some mechanism. This seems to suggest that there is some sort of underlying formal language, with a grammar. Not only would the grammar determine what... | [
"Ok, I'll try answer this to the best of my knowledge. ",
"DNA - at face value looks more like a random assortment of G, C A and T. But in actual fact, there are particular patterns (sequences), which form these things called \"open reading frames\" (ORFs). In these open reading frames, we have particular sequenc... | [
"There's not really a grammar that says some strings make sense and others don't, but there are start and stop codons that begin and end translation of mRNA by a ribosome. A ",
"ribosome",
" is an assemblage of large proteins that produces other proteins using messenger RNA (mRNA) produced from DNA.",
"mRNA i... | [
"Let's start off at the beginning. DNA is copied into a very similar RNA and then 'translated' into a protein.",
"DNA -> RNA -> Protein.",
"Proteins are structures that are able to perform most of the tasks a cell needs. It might be more useful for you to think of DNA/RNA in this way - it's sort of a LEGO const... |
[
"How small can a nuclear bomb be and still have explosive power?"
] | [
false
] | [deleted] | [
"There are physical limitations to how small you can make a nuclear bomb. The major one is the ",
"critical mass",
" of the fissile material. This is on the order of 10kg for Plutonium warheads and higher for uranium. The critical mass is the absolute minimum amount of material you need for a spontaneous nuc... | [
"There was also the ",
"Davy Crocket",
", which weighed about 23 kg. At the time, it was practically the smallest the U.S could make a nuclear warhead. "
] | [
"This needs to be emphasized heavily. Critical mass is not a fixed, magical property — it dependent on specific circumstances. There is no single critical mass value for any given material; they depend on geometry, density, the presence of moderating materials, the presence of reflecting materials, etc. (Which is w... |
[
"How is it possible to find the brain speed (of a person) for reacting to certain fast-thinking situations?"
] | [
false
] | null | [
"Can you give an example of what kind ot situation you have in mind and what you mean by \"brain speed\"?"
] | [
"There are two primary ways. ",
"The first is behavioral, like measuring reaction time. Of course this includes many processes like time to process the stimulus, time to make a decision, issuing of motor command, execution of motor command, etc. The usual way to separate out these processes is by comparing reacti... | [
"Situation - when you have to react fast eg. You see a snake in front you. Brain speed - the speed that the brain uses to process certain information from the outside world, and gives a reaction/feedback."
] |
[
"With regards to a falling mass, do forces multiply (or otherwise dramatically increase) when a fall is arrested in stages? (Free fall, resistance, free fall, resistance.)"
] | [
false
] | This question stems from a controversial topic in regards to rock climbing safety, however, I am just curious about the theoretical physics behind this. Here is a non-climbing example of what I'm wondering about. Assume all ideal conditions. (No wind resistance, weightless chain, etc.) Also, I apologize that this is a ... | [
"Momentum is what you want to look at here:",
"When the first anchor becomes taught, the momentum will be ",
"When that anchor breaks, the climber enters free fall again, falling another [2D+d] until the remaining anchor catches, when the momentum becomes",
"In comparison, with only the secondary anchor the m... | [
"Alright, I follow along pretty well here! I do think, however, you made a small mistake. The additional fall distance of the second fall should just be 2d, rather than [2D+d]. When the top anchor fails, the amount of slack rope introduced to the system is of length 2d. Also, the fall from the peak point to the lo... | [
"You're right, I misread that (and also accidentally some math). That changes those equations to",
"P1= m(0 + 2g(2D))",
" = 2m(gD)",
"P2= m(v1",
" + 2g(2d))",
" = ( (P1-A)",
" + (4gd)m",
" )",
"Px= m(0 + 2g(2D+2d))",
" = 2m(g(D+d))",
"Which means my previous scenario [P1 ~ A] would be that the ... |
[
"The sun's companion star: Any validity at all?"
] | [
false
] | A brief Internet search turns up not much science, and a reddit search I only see sparse mention where it didn't get much attention so I'd guess not but thought I'd ask if there is any factual basis for the idea of our sun having a companion star? The extinction "theory" being the basis for this idea doesn't really see... | [
"not inherently.",
"While I don't buy into the idea, because there's a lack of evidence... there are certain types of celestial bodies which wouldn't necessarily show up on WISE. A red Dwarf would ",
" show up on WISE, however a brown dwarf may not. ",
"Technically a brown dwarf isn't a star as much as a fa... | [
"Thanks for the replies, I had read the wikipedia and it seemed to indicate there is no real significance to the idea, but it also didn't clarify it as a total crackpot theory, which is what it seems like at this point."
] | [
"\"March 14, 2012, the entire catalog of the WISE mission was released.\"",
"I guess the absence of it in that report makes it pretty clear..."
] |
[
"Could sand be made into glass by a hot enough explosion?"
] | [
false
] | Would it be possible with the technology/bombs that any country has to turn regular beach/desert sand into glass after an explosion? Has it ever been done before? Do you think it will be possible in the future? *Edit: I apologize in advance if this isn't the right section (Chemistry) I'm not a big science guy. | [
"Even lightning can form glass tubes of sand",
". ",
"Don't apologize for not knowing stuff, OP. This is why this subreddit exists, and we all should promote the will to learn more. (Scientific literacy makes the world amazing I think). "
] | [
"Libyan Desert Glass",
" (LDG) is thought to be formed millions of years ago by melting of desert sands by air-burst or perhaps overflight of a large meteor."
] | [
"Yes, it's been done before",
"."
] |
[
"Could human beings inhabit a nuclear submarine if it were in space?"
] | [
false
] | Obviously, there would not be a system for propulsion or any kind of flight navigation. But in my amateur unknowledgeable mind: The interior of a submarine is airtight and pressure resistant (to a degree I imagine) and I would also imagine some sort of radiation shielding is present in some way due to the reactor tha... | [
"nuclear sub engineer here. All the shielding necessary for a nuclear sub is provided by the metal vessel the reactor is in. which is only a few inches thick a most, there's not plates of lead or any other moderator. The outside of the hull is just high strength steel.",
"Because a submarine is underwater sub cr... | [
"Space is by definiton colder than seawater, but given the fact that it is a vacuum, there would be almost no low energy particles to transfer heat to. "
] | [
"Nuclear subs use sea water to cool their reactors... if you managed to put one in space you'd have a nuclear meltdown OR have to turn off the reactor which would leave you without power in relatively short order and therefore without air (dead)."
] |
[
"Why do humans need to maintain a core temperature of 98°?"
] | [
false
] | [deleted] | [
"Actually it's a range from 92F to 101F, or 33C to 38C.",
"An upper limit of 111F or 44C is set by the denaturation of proteins. Proteins have to maintain a certain 3-dimensional shape to work properly. High temperatures unfold proteins rendering them inoperable.",
"A lower limit of 82F or 28C is set by the che... | [
"The rate of chemical reactions is dependent on the frequency of collisions/interactions between different molecules, which is dependent on the speed of molecules aka the temperature of the material. However, higher temperatures also require a lot more energy to maintain, and extremely high temperatures can result ... | [
"The upper limit is the same for all animals, but cold-blooded animals, or ",
", have multiple enzyme systems that operate over different temperature ranges, so their body temperature can go lower and they can still move and their heart can still beat.",
"The cost of this system is a much larger genome than a h... |
[
"Can plants survive without Oxygen (O2)?"
] | [
false
] | A friend and I have been debating this for a while and he swears he is right because he has a degree in Biology and I only have a degree in Communication. I would really love to prove him wrong. So, can plants survive in air without O2, or in air with just CO2? | [
"So is it possible for them to be in a sealed container with access to light with no Oxygen to begin with and then respire off their oxygen byproduct? Or is some oxygen absolutely necessary? Would the type of plant make a difference?\nThanks for the reply, even if it is proving me wrong :)"
] | [
"So is it possible for them to be in a sealed container with access to light with no Oxygen to begin with and then respire off their oxygen byproduct? Or is some oxygen absolutely necessary? Would the type of plant make a difference?\nThanks for the reply, even if it is proving me wrong :)"
] | [
"\"You absolutely cannot grow a plant from seed in those conditions\"",
"This is not nessisarily true. Many seeds contain the nessisary nutrients to grow to quite a large size before needing any input at all (though, H2O is almost always required) It is hypotheticly possible that after this point the plant could ... |
[
"Why do some some grand unification theories, such as the SU(5) Georgi–Glashow model and SO(10), require proton decay to be true?"
] | [
false
] | null | [
"Grand unification combines the strong, weak, and electromagnetic forces into a single master force. Doing this requires embedding the known forces in a larger structure, and that larger structure is going to create processes that would not exist without unification (if you don't have something new, all you have i... | [
"From the ",
"Wikipedia article on proton decay",
":",
"Some beyond-the-Standard Model grand unified theories (GUTs) explicitly break the baryon number symmetry, allowing protons to decay via the Higgs particle, magnetic monopoles or new X bosons with a half-life of 10",
" to 10",
" years.",
"It's also ... | [
". You might think of it as a corollary or consequence of the totalitarian principle, rather than a restatement of it.",
"In order to satisfy the relevant conservation laws, decays typically have additional degrees of freedom for energy to occupy. For example, many decays look like a single particle decaying in... |
[
"How biologically important is intelligence? Is it, in any sense, an inevitable consequence of life?"
] | [
false
] | By "intelligence" I mean what we typically deem as human intelligence--in general, things such as technology and written/spoken language. As I see it, though intelligence has certainly helped increase the stability of our ecosystem dominance, it's not a necessary component of a successful top-tier predator in an ecosys... | [
"Richard Dawkins likes to point out that intelligence cannot be that important relative to other evolutionary novelties (such as eyes, limbs, a sense of hearing etc). Things like eyes have evolved independently multiple times, while the type of intelligence you are talking about (or anything close to it) occurs onl... | [
"Wouldn't our hands have played a big part in our intelligence actually being useful? It seems to me it was our intelligence and dexterity combined that allowed us make the wide variety of tools, shelters, and clothing and become so adaptable to different habitats and food sources.",
"I can't see any of those cre... | [
"The most biologically important traits are those that increase sexual reproductivity. Intelligence may be an important factor in survival for some species, but there are plenty of organisms that seem to get by just fine without it. It is probably helpful (to reproduction) to a certain extent in some environments... |
[
"Why are some artificial flavors totally different from the flavors they are trying to emulate?"
] | [
false
] | For example, "grape" flavored candy tastes nothing like real grapes, ditto "watermelon" or "strawberry" flavored candies. However, some artificial emulations of certain flavors (like Harry Potter Jelly beans) can be really spot on. Why is this? | [
"Flavor profiles are normally based upon many different flavors working together, there is not really one thing which makes vanilla taste like vanilla. However in most cases anything which is made to taste like vanilla is acheived using the chemical Vanillin ",
"Chemical Structure",
" which is a simple example ... | [
"Artificial flavors are essentialy one or more chemical mixtures. Those mixtures while mimck the \"main\" flavor aren't complex enough to add the \"dimension\" real food has",
"Real food however has far more factors that alter its age(e.g ripeness) so the two can never quite be the same",
"And if you are intere... | [
"The flavour of a food might consist of hundreds of molecules, which makes it near impossible to mimic. There are some flavours, that mainly consist of one molecule and are therefore quite easy to mimic. vanilla (vanillin) comes to mind first, but also stuff like cloves (eugenol) or almonds (benzaldehyde)."
] |
[
"Why are the reproductive organs the same as excretory organs? Is there a logical reason behind this?"
] | [
false
] | null | [
"Discussed earlier",
". Also ",
"reddit search",
" sucks, use ",
"google like this",
" instead."
] | [
"not at all"
] | [
"Sorry, serious answer this time: Nope. Bacteria help you digest your food, there are more bacteria in your bowels than there are cells in your body. "
] |
[
"How do you reconcile Time with Relativity?"
] | [
false
] | So I have learned that time changes based on the speed you are traveling. The faster you travel the slower time passes. How does relativity play into this. If I pick different vantage points I can arbitrarily change the rate at which time passes for an object. From a point on earth a jet carrying a clock travels at mac... | [
"To describe the passage of time in relativity, you must treat time as a coordinate in the same way that we treat the 3 spatial dimensions as a coordinate. This allows us to talk about intervals in a 4-dimensional spacetime. ",
"Classical mechanics describes the evolution of mechanical systems in a 3D Euclidian... | [
"You're pretty much confused in all the right places. Time in relativity is pretty nonintuitive at first, but the end result is that for objects moving very quickly, absolute time and simultaneity just don't work."
] | [
"If I change my vantage point to the sun",
"Keep in mind that you cannot physically do that! A physical observer has to accelerate (decelerate) to do that, and that influences the passage of time.",
"This has been tested and verified in practice"
] |
[
"If the earth developed as it was, without something like our star dying to interfere with this, would the earth eventually lose all its oceans due to under-sea volcanoes creating new land masses?"
] | [
false
] | If so, how long would this take? And is there more land mass than there was back when there was the super continent Pangaea? It makes sense to me, since there are relatively new islands and what not being developed as we speak by volcanoes under the sea. Though there may be some form of land mass reducing thing I don't... | [
"The diameter of the Earth doesn't change, and the volume of water doesn't change, so the water just moves around as land masses move around."
] | [
"Land masses are destroyed by erosion and by subduction, where a colliding continental plate is forced it into the mantle where it melts 100km below."
] | [
"yes. Of course the oceans could shrink while getting deeper, but probably not. You lose land mass to plate tectonic collisions, for example India colliding with Asia raised the Himalayas. These collisions crunch land masses together, raising mountains but diminishing the total area covered by land. Similarly, ... |
[
"How does data compression work?"
] | [
false
] | I am always fascinated that you can take a file and shrink it to a smaller size. What exactly is the mechanism that operates in this process that allows preservation of detail with less? And if so, does this mean there are redundancies or something extra that's not needed? | [
"Alright, I'll use the \"zip\" compression scheme:",
"It is inevitable that there will be repeats within a data set, and because any repeat will be the same set of 0s and 1s we can [usually] reduce bit count by referring back to the first instance for each subsequent instance. We can demonstrate this with some l... | [
"All in all, compression usually makes things smaller but can make things bigger.",
"Fun fact for people interested: it's impossible to create a functional compression scheme that will compress every input given to it by at least 1 bit."
] | [
"Here's the simplest idea that will sort of explain it:",
"Let's say we have a file that looks like this:",
"\"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000... |
[
"What were the biggest topographic changes on earth in recent times?"
] | [
false
] | And what was the cause? | [
"I'd say massive sea-level changes and modification in coastlines and ice-cover during the end of the ice-age, a mere 10000 to 12000 years ago (Not even 1 tenth of a million years!!!). ",
"We went from a map like ",
"this",
", with ice sheets about 2 kms thick reaching as far south as Long Island and land bri... | [
"This is a little tricky to answer without a better sense of what you mean by 'recent times'. If recent times means recorded human history then the biggest topographic changes would likely either be various anthropogenic activities (e.g. strip or pit mining, subsidence from groundwater extraction, etc) or abrupt ma... | [
"Following up on ",
"/u/Gargatua13013",
" you could also argue that the biggest topographic changes might be associated with enhanced submarine volcanism driven by the transfer of water mass from the ocean to continental ice sheets. There have been a couple of fascinating papers lately hypothesizing that abyssa... |
[
"How does smell work?"
] | [
false
] | On the most basic level I understand that receptors in our nose identify matter at the molecular level, but I'm confused about the nature of that matter. For example, I have a tuna fish sandwich on my desk. I can smell tuna fish as soon as I enter the room. So my nose has detected something in the air. My question is, ... | [
"This has been asked ",
"countless times",
". ",
"This one",
" has a fairly good explanation.",
"All that is required is that the molecule that your nose detects has some vapour pressure at room temperature - for example, ethanol or acetone are liquids at room temperature, yet we can smell them (quite str... | [
"Tuna fish doesn't exist as a gas, and as you point out, tuna is not a definable molecule: its composed of trilllions and trillions of molecules which you could classify in to hundreds of thousands of different types, to the least. Of those, some types of molecules are volatile, meaning they easily get vaporized wh... | [
"Thanks. I searched for my question, but that one didn't come up because ",
"."
] |
[
"Cosmic rays can sometimes cause soft errors on computers by flipping bits. Can alpha particles affect our brain as well?"
] | [
false
] | [deleted] | [
"Alpha particles would generally be stopped by skin, if they even got that far. Gamma rays would penetrate, but memory in the brain is a different mechanism. For one, brain memory seems to be 'holographic' in that it can often be reconstructed after damage to a single cell or portion of the brain. Enough gamma t... | [
"Perhaps I'm incorrect on the type of particles, as I'm just repeating what I've read/heard. ",
"Whatever type of particles these are, they're able to penetrate through buildings and metal server cases, so I imagine they can penetrate skin or bone as well, but I could be wrong."
] | [
"Cosmic rays are very-high-energy gamma. Depending on energy, they could go completely through a person, like an x-ray. It really is not a particle like alpha or beta would be, but might still cause a computer to flip a bit. "
] |
[
"Why can't we used donated pancreases to cure diabetes?"
] | [
false
] | We can use donated organs to cure so many other diseases why wouldn't transplants cure diabetes? | [
"Huh? I don't understand your question, my boyfriend went through a pancreas transplant and now is not diabetic. It was fairly recent and still has some immunosuppressives, but over all he has way more energy (he also got a kidney).",
"If the question you are asking is about donations and why there are no pancrea... | [
"Pancreatic transplants can only be used for type 1 diabetics (people who don't make insulin). T1 diabetes is an autoimmune disease; your immune system attacks the beta cells in your pancreas, leaving them unable to make insulin. Insulin is needed to stay alive so type 1s have to take insulin via shots or a pump to... | [
"Just curious, but what did they tell your boyfriend about the long-term success of the pancreatic transplant? From what I've read and the people I've known who have had pancreatic or islet-cell transplants, T1s always end up on insulin again because of the autoimmune nature of the disease. "
] |
[
"When I look up at the night sky, how far back in time and I truly looking?"
] | [
false
] | So I was about to make a showerthoughts post about "when I look up at the sky I am essentially staring millions if not billions of years into the past" but am I? I understand the basics of light speed, kind of(a star 7 million light years away. When it shines we get the light 7mil years later and as we get it the star ... | [
"Hi ",
"/u/Leftys-Wheelchair",
", ",
"I like this question. I'm going to run a little wild with it.",
"\"when I look up at the sky I am essentially staring millions if not billions of years into the past\" but am I?",
"With your naked eye, the most distant ",
" you can see is probably ",
"Andromeda",
... | [
"Main sequence stars are expected to have a lifetime of roughly 10 billion years. Because the relative distance between us and the furthest stars in the Milky Way (~50,000 light-years) is much smaller than the age of the most common star types, it's very likely that the stars you see in the sky are still there.",
... | [
"How far can your ",
" eye see?",
"The answer is ",
"2.54 million light years",
", in the constellation of ",
"Andromeda",
".\nSuppose you're not looking there. You could be south of Tasmania, Australia, where it is below the horizon. It could only be above the horizon in the daytime at the time of year... |
[
"Is there a 1 to 1 ratio of electrons and protons in the universe? If not, then what is an estimated ratio between the two?"
] | [
false
] | null | [
"Up to our knowledge universe is electrically neutral.",
"Up to our knowledge there is no stable mass of antimatter in our current universe. ",
"Up to our knowledge proton and electrons are the stable charge charged particle. ",
"So the answer is yes"
] | [
"There are still processes that can change the number of electrons without changing the number of protons. \nE.g. annihilation of an electron-positron pair. ",
"So not exactly 1 to 1."
] | [
"As far as we know total charge is neutral, however, muons, mesons, positrons, etc. can all also carry charge. Furthermore, neither electrons nor protons are conserved quantities in scattering. So in principle their number is potentially in flux, as there are other particles that can be holding their charge at any ... |
[
"Electron Configurations & the Pauli Exclusion Principle - How can an atomic orbital (p,f,d etc) hold more than two electrons if the electron has only two spin modes?"
] | [
false
] | Do the other quantum numbers come into play to allow non-S orbitals to hold three or more? I'm definitely missing something here, it seems like what I've read about the PEP doesn't line up with, well, the entire periodic table. | [
"Why does the orbital angular momentum (L) for the Z axis get its own Q#? Tough luck for the X and Y axes?",
"The Z axis choice is arbitrary. It would be equally valid to choose to project the orbital angular momentum onto X or Y instead. ",
"But the whole reason one projects the vector in the first place is th... | [
"PEP only applies if fermions have ",
" the same quantum numbers. There might be a lot of them for a given specific system. The letters s, p, d, f refer to the orbital angular momentum quantum number. Principal quantum number (read ~energy level), z-component of orbital angular momentum, spin angular momentum, nu... | [
"Yes, for a closed system, quantum or not, the total angular momentum is a conserved quantity (which is a consequence of the rotational invariance), so you would not see a spontaneous spin flip. ",
"However, if you project the spin along an orthogonal axis by measuring it, and then perform another measurement alo... |
[
"Quantum Tunneling (calculations)"
] | [
false
] | in graph, it shows that the probability of transmission through a rectangular potential barrier equals 1 when the particle energy is slightly larger than the potential barrier. Is there a way to calculate the minimum value for E or E/V0 (when T=1) in terms of the other variables? I tried rearranging equation from page,... | [
"This smells of homework"
] | [
"T = 1 when the sine term is 0, so, given that",
"k = sqrt(2m[E-V",
"])/h",
"T = 1 when",
"(a/h) * sqrt(2m[E",
" - V",
"]) = npi",
"or, more cleanly,",
"E",
" - V",
" = n",
"pi",
"h",
" / 2ma",
"are the allowed energies for 100% transmission. of course, \"h\" should be \"h bar,\" I'm jus... | [
"Shouldn't that be",
"k = Sqrt[2m(E - V",
")]/hbar",
"so that",
"E = n",
"pi",
"hbar",
"/(2ma",
") + V",
" ?",
"After all, you only get 100% transmission when E>V",
" which isn't guaranteed by your expression."
] |
[
"What would happen when light reflects off of a mirror, if the mirror was artificially heated to have a higher net energy than the particle does?"
] | [
false
] | Would the particle receive the energy during the reflection, or would the additional heat make no difference? (my "guess" is that it would be impossible to heat something to a high enough temperature for it to retain it's ability to reflect, and instead the mirror would fail.) Apologies if my question is phrased poor... | [
"What do you mean \"higher net energy\"? The total heat energy in a given mirror is typically much higher than the energy of a given photon in the visible spectrum."
] | [
"I can't think of any reason why a hot mirror would reflect \"more\", and I'm fairly certain it doesn't, but that doesn't mean that the heat energy is trapped. Any object, even in a vacuum, will give off heat in the form of black-body radiation."
] | [
"My question is based out of reverse engineering the terminology behind what occurs on an atomic level for the act of reflection. For example, if you had a \"perfect setup\" of an entirely enclosed dyson sphere that was reflective, and the star was then \"shut off\". As I understand it, the light would then be re... |
[
"Why does sticking a finger or toothbrush in the back of your throat trigger a gag reflex but swallowing food doesn't?"
] | [
false
] | I was attempting to brush my tongue (to no avail), and this question popped into my head. What makes our throat more sensitive to one thing passing through than something else? | [
"Once you initiate swallowing your brain suppresses your gag reflex."
] | [
"What bodmon said is correct. I just want to add that the swallowing reflex is one of the most amazing things I've learned about the human body. It takes such coordinated effort for the body to do such a task that most would view as basic and uncomplicated, but it is far from it. If you ever have the time, learn... | [
"I'll bet all these deleted comments were really funny. "
] |
[
"I have a problem with a center of mass height in a car calculation."
] | [
false
] | null | [
"Check my work to be sure, but I think the formula is wrong. I haven't traced the entire thing through, but looking at one step (after 2.31 up to 2.32).",
"h = R + [ (a1*Fz1 - a2*Fz2) / mg ] * cot(theta)\nh = R + [ 2*(Fz1/mg)*L - a2) ] * cot(theta)\n",
"Substituting a1 = L-a2, Fz2 = mg/2-Fz1 into the first equ... | [
"In the long term, formulas are pretty useless without understanding where they come from. Following through the derivation yourself and finding where the error is will help you a lot more than plugging numbers into something you don't understand and will never remember."
] | [
"I followed through from their working on the second page, and the second simplification for ",
" is wrong: the factor of 2 in front of ",
" shouldn't be there, and ",
" should be divided by two. Unfortunately that correction doesn't give you their answer of 34 cm, however. Given this obvious error, it's poss... |
[
"How are psychological traits passed down between generations?"
] | [
false
] | Examples of the types of traits that I'm referring to: People have a preference for providing resources to their closest genetic relatives (children, siblings) over more distant relatives (nephews, cousins) and non-relatives. This make sense because doing so helps their closest relatives survive and reproduce and pass... | [
"Okay, there are still so many unknowns about this. We haven't been able to really identify any genes that are related to intelligence or to particular preferences. Especially since a similar genotype can produce radically different phenotypes in different environments => see ",
"http://en.wikipedia.org/wiki/Diff... | [
"We don't even have a comprehensive understanding of which area of the brain does what. We don't even know if feelings are expressed by discrete localized areas, or by tons of areas working together in a specific sort of fMRI \"fingerprint\" way. Overall, I think the field has a ways to go before we can start makin... | [
"I'm not sure of the specifics (not in science) but there are a lot of psychological studies done with identical twins.",
"http://www.mendeley.com/research/differences-sport-performance-personality-traits-between-pair-monozygotic-twins/",
"There is one of the most recent examples that shows though they possess ... |
[
"Why is too much salt bad?"
] | [
false
] | I googled it. Read about the sodium-water balance. Does this mean I can eat salty snacks (in excess of the recommended daily intake) and drink water to compensate? How are recommended daily intake amounts set if everyone drinks different quantities of water? | [
"Excessive sodium is generally bad because it can put strain on the heart and throw out the balance between sodium and potassium (both of which are used in neurotransmission). Excessive sodium is often the cause of muscle cramps (hence why eating high potassium foods can help).",
"It’s also not a good idea to sup... | [
"Well, be careful basing your choices on a quote from a doctor by a patient with memory issues. Lol. But that’s what I understood. Check in with your own doctor, but understand that there are nuances based on what’s happening for each individual patient."
] | [
"I have a physical condition that is benefitted by intaking large quantities of salt. I asked my cardiologist if this was bad for me as the going thing has been low salt for decades. He said that a certain, small subset of the population has sodium dependent heart issues that led to the blanket recommendation. I ag... |
[
"How is light crude oil turned into gasoline?"
] | [
false
] | Let's say I get myself some light crude oil by using (Page 13) in a homemade rig, how would that be produced into gasoline for vehicles? Or would I just be better off selling the crude oil to refineries? | [
"Crude oil consists of many heavy and light hydrocarbons. Refinement separates the hydrocarbons in the oil into the hydrocarbons of the same type. There is not ONE process used to refine crude, but a multitude of processes to separate the different parts - vacuum and atmospheric distillation separate the hydrocar... | [
"Even as a chemical engineer, I wouldn't be attempting ",
" like this at home..",
"Flammable hydrocarbon vapour at 350 deg. C at >12MPa isn't the type stuff you want anywhere near the things in life that you value..."
] | [
"not a great image, but:",
"http://www.phaster.com/_peak/oil_refiner_fractioning_column.gif",
"Also this one: ",
"http://i.imgur.com/y0Fo0y9.jpg"
] |
[
"How do we stay in contact with Voyager?"
] | [
false
] | How do we keep in contact with the voyager which is currently 12 billion miles from earth? Also what kind of information are we looking to receive or receiving at the moment? | [
"Radio. Specifically the ",
"Deep Space Network",
", using enormous (70 m diameter) radio dishes. For communicating with Voyager they use an extremely strong transmitter (up to 400 kW), for listening to the data from the spacecraft they use highly advanced low noise amplifiers (which can record individual radio... | [
"According to DSN Now, transmission to Voyager 1 occours at 159 bits per second. At a constant rate of speed, it would take ~2.91 days or 69.88 Hours to transfer the data (5 MB), assuming that rate of speed was maintained perfectly. ",
"http://eyes.nasa.gov/dsn/dsn.html",
"\n",
"http://www.calctool.org/CALC/... | [
"Several times per week, the DSN antennas capture signals from the two Voyager spacecraft, which are exploring the edge of interstellar space. Their signal has a received power 20 billion times weaker than that of a digital wristwatch. (NASA/JPL-Caltech)",
"So what's the bandwidth for that? How long would it take... |
[
"Someone told me that ethanol takes more fuel / energy to produce than it provides. Is this true? Please explain."
] | [
false
] | Followup, if this is true then why do we produce it? Thanks! | [
"Ethanol from corn is not carbon neutral. The oil powered farm equipment and the oil based fertilizer and the fossil fuel energy of production all add up to more energy than burning the ethanol gives back. Basically, we are converting oil into ethanol."
] | [
"Do you have a source for this? I'm not saying you're wrong, but I have a source that disagrees with your statement. I would like review more data though, if you have any.",
"http://www.wired.com/autopia/2011/06/five-ethanol-myths-busted-2/"
] | [
"...for now. There's a ",
" of research into sustainable bioenergy sources going on right now. ",
"Just a few examples:",
"Wisconsin",
"Michigan",
"Start ups"
] |
[
"Does competition drive down diversity in an ecosystem? If so, why?"
] | [
false
] | I read an article recently about two types of fish in a lake. One lived in the shallow portion of the lake, one in the deep. After crawfish were introduced to the ecosystem, the two fish interbred and competed, to their detriment. The abstract for the article stated, in a way that implied that it was a known fact, t... | [
"When you have multiple organisms competing for the same resources in the same environment (i.e., the same niche), the organism with the higher fitness will become more dominant, and either a) niche partitioning or b) extinction of competing organisms will occur. Assuming the latter occurs, in this way competition ... | [
"Can you explain why it's counterintuitive to you? Do you mean that it seems to like competition should increase diversity or have no effect? Or just that there's no intuitive outcome to you at all.",
"There's actually lots of ways to think about how competition might affect communities. Competition is necessari... | [
"Why not link the article? There could be a host of reasons why it would be to their detriment or benefit, and we can only answer if we know the specific example. You might not be interpreting the paper correctly. ",
"Two different species interbreeding and the two species competing are very different things. It'... |
[
"How are cell samples maintained to ensure quality over years or even decades?"
] | [
false
] | There are multiple samples of cells that are used for research that were harvested years and years ago. How are we certain that these are of appropriate experimental quality, especially when we know that telomeres on cell DNA degrade after repeated divisions? What methods are employed in preservation and quality contr... | [
"In much newer reserch it is a requirement for publishing a paper involving work on cells, that the identity and quality of the cells is somehow confirmed. To some extend this can prevent mistakes from happening, such as mixed up cell cultures or cells infected with a pathogen. The quality control can be performed ... | [
"https://www.atcc.org/support/faqs/2f03c/ATCCs+use+of+passage+number+and+population+doubling+level+PDL-110.aspx",
"Most widely used cell lines can be purchased from ATCC. They try and limit cell passages and grow up a lot of it at first and slowly use that stock up. Cells that have been passaged many times time... | [
"I was aware of the cancer strains being used, but use of a virus to indefinitely promote division is a new concept for me. It makes sense, considering that a virus will alter DNA in a host cell.",
"Thanks for the response, that was great "
] |
[
"Are there any quality studies that demonstrate a vegetarian or vegan diet promotes greater health, longevity, and disease prevention over an omnivorous diet?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"Some of the most commonly seen mistakes are listed in our ",
"guidelines.",
" under respective fields."
] | [
"Can you elaborate on the \"fundamentally flawed premise\"?"
] | [
"When posing a scientific question, it's best to leave conclusions out of the title, all it ends up doing is starting a rebuttal first instead of starting with information. A good question along these lines would be \"Is there a specific diet that is 'optimal' humans?\" If you end up making a new question, let me k... |
[
"What would happen if I heated something to the temperature of combustion, but kept it in an oxygen-free environment?"
] | [
false
] | If anything | [
"This depends on the 'something.' If it is a material that already contains oxygen, then you can get pyrolysis of the material as the chemical bonds can change. Most of the time you wouldn't see a change with the exception of melting or any normal breakdown of the something (see: pyrolysis). Combustion, by defin... | [
" has a proper definition, in that it's a reaction involving some type of fuel, typically a hydrocarbon, reacting with O2 to make stuff like CO2 and water, depending on your reactants. If you heat up a hydrocarbon without any O2 present, you can still get chemical reactions and changes, you just won't get the usual... | [
"Lots of chemical reactions can occur at relatively high temperature and of course vary depending on the composition of the environment. For example, in the deep sea, the maximum observed temperature of hydrothemal vents is around 420C, far above what could be a combustion temperature. The exchange reactions betw... |
[
"Hypothetical question regarding the abundance of resources on distant planets (for a writing project of mine)"
] | [
false
] | [deleted] | [
"Abundance of diamond would be very good for building/industry (hard, durable, high thermal conductivity). Maybe a high abundance of uranium 235 would be handy, since this is the uranium isotope that's used in fission reactions. On Earth about 0.7% of natural uranium is uranium 235, the rest is uranium 238 which ca... | [
"The resources on earth roughly reflect the conditions required to make said resources. Any elements with mass up to iron can be created in the core of stars. Any elements heavier than iron must be created in supernovae, and thus are fairly rare in comparison (gold fits this bill). Then factor in the decays of some... | [
"You and 2x4b get upvotes for awesome responses. I kind of figured water was a must, I was just going for speculation on how different societies would use different resources given that they had an abundance of them. Hypothetical as hell, but I still think it could lead to some fun and interesting speculation. ",
... |
[
"Is the moon Titan losing its atmosphere, and if so, at what rate?"
] | [
false
] | I heard that Titan's moon is losing its atmosphere, as in the Wikipedia article, "Because N2 is the primary component (98%) of Titan's atmosphere, the isotopic ratio suggests that much of the atmosphere has been lost over ." How does this loss of an atmosphere compare to other planetary bodies in our Solar System, such... | [
"Only some lighter compounds are lost, since their kinetic energy (or colloquially, 'heat') can exceed the gravity holding them to their planet/moon and thus the escape velocity, allowing it to escape. Other factors like solar wind can also contribute to this phenomenon.\nThe heavier compounds/element (like nitroge... | [
"What proportion of Titan’s atmosphere by mass are these “lighter” compounds? Also, is this why Mars has very little atmosphere?"
] | [
"I'm not sure about the exact data of titan, but since it's mass is small (cuz it's a moon) and it's been 4.6 billion years since the planets formed, chances are almost all of the light gases and escaped. And since gravity is weaker there even some of the gases we consider heavier (is there any oxygen left?) may ha... |
[
"How did wings evolve?"
] | [
false
] | I understand the basics of evolution, a creature is born with a unique disposition which proves to be better for the species and the rest die off. Features such as hands and arms take millions of years to evolve because a creature's disposition is usually only very small. What I don't understand is how the stub of a wi... | [
"You have to understand that arms (or forelegs) came before the wing. The wing contains the same bones as an arm and hand, and are modified from this, the wing didn't start from a stub.",
"This article contains several theories of how wings might have been used before they were used to fly: ",
"http://en.wikipe... | [
"This kind of makes one wonder what all possible evolutions have not happened simply because they would require too many steps which are not favored for survival."
] | [
"I answered a similar question before, so here is my answer from then. It's a two parter, having to do with the evolution of feathers as well as wings: ",
"It is true that adaptations have to be advantageous throughout an organism's evolutionary history, even when the structures are half-baked. I can give two exa... |
[
"Do the storms on large perpetually storming planets ever interact with their moons?"
] | [
false
] | Could a storm on Jupiter ever build up enough electric energy to cause an interaction with one of it's close-orbiting moons? Could a larger similar planet ever do so? | [
"In respect to the first question, no. The distance between Jupiter and it's closest moon, Metis, is nearly 80,000 miles. This is roughly 1/3 the distance between Earth and the Moon, and if you were to go to scale, do this. For Earth and the Moon, position a globe and a whiffle ball 30 feet apart. This is ~250,000 ... | [
"the gravitational attraction between those two objects would be strong enough to pull the moon in, or fling it away (due to instability of an orbit that close to a planet).",
"Where are you getting that from? The stability of orbits does not change with distance until you're approaching the event horizon of a b... | [
"Slightly different question: Would storms on perpetually storming planets have tides due to their moons' influence?"
] |
[
"The Hawking radiation explains the loss of mass in a Black Hole with antiparticles getting sucked in. Wouldn't on average the same amount of particles fall into the black hole too, thus negating the effect?"
] | [
false
] | [deleted] | [
"Particles vs antiparticles does not matter at all. It's completely unrelated to Hawking radiation. You can also use particles which are their own antiparticles, like photons.",
"The point is energy. The particle right inside always has ",
" total energy, because the negative gravitational potential energy just... | [
"No, not exactly, the difference in potential energy between two close points is the gravitational force, not tidal forces. The gravitational field at the surface of the black hole, corrected for redshift, is called the surface gravity, is proportional to 1/M, and the temperature of the BH is proportional to that."... | [
"So do bigger black holes evaporate slower because the difference in gravitational energy between the two particles at the event horizon is lower? (Tidal force basically) "
] |
[
"Are genetically-altered heroes, such as Spider-Man, the Hulk, and the X-Men, still considered human?"
] | [
false
] | null | [
"If they could produce a fertile child with a human of the other sex they'd still be considered part of the human species."
] | [
"OK. Spider-Man has, depending on the writer, been able to successfully mate with Mary Jane, but other times their child has had some complications and been unable to survive. I suppose it depends on the story for him, then."
] | [
"This question is better suited to ",
"/r/asksciencefiction"
] |
[
"What is the strongest proof of liquor in which ice cubes will float?"
] | [
false
] | It was recently brought to my attention that . What is the maximum concentration of ethanol which will let ice cubes float? Put another way, what molarity of ethanol solution has density equal to that of ice cubes? | [
"Wikipedia is great for this sort of information.",
"Properties of aqueous ethanol solutions chart",
".",
"Density of ice and water plot",
".",
"If I'm reading things correct, water ice at 0 °C has a density of 0.917 kg/m",
". At room temperature, a 50% ethanol solution has a density of 0.91546 kg/m",
... | [
"Edit: Wait, you meant ",
" concentration/",
" proof, right? You must have, or else the question makes no sense.",
"Ice cubes will float in zero-proof liquor (i.e., water). They apparently will not float in 200-proof liquor (i.e., pure ethanol). So there is some ",
" concentration of ethanol, i.e., some ",
... | [
"Gosh, I went and confused myself after I had already given him the right answer! Maximum to float == Minimum to sink, duh.",
"TL;DR: I should sleep more."
] |
[
"Humans rear their children for considerably longer than the rest of the animal kingdom. Assuming education is not a factor, is 16-20 years of child rearing needed for our species?"
] | [
false
] | Not sure how else to phrase it. | [
"Well this is a bit more complex than one would first expect. In general we see that in primates infants can typically survive on their own just before or around the onset of weaning (about the age of 1). This means they have learned enough skills to be able to survive and navigate their social and natural environm... | [
"YES! I can finally talk about orangutans. As cebus_capucinus mentioned this is likely a cultural factor. I would say that upon sexual maturity most animals are independent. In primates they typically disperse from their natal group at sexual maturity.Humans are very different in that much of our neurological devel... | [
"In traditional societies children transition into adult roles much more smoothly. Since they don't have either formal education nor jobs, most of their activity blends quite nicely with that of adults. So when you see 13 year olds married and with children you're shocked and wonder how can they possibly manage to ... |
[
"Can heat travel in a vacuum?"
] | [
false
] | [deleted] | [
"Yes. Heat travels in 3 forms: conduction, convection, and radiation. The first two require a medium. The last -- radiation -- does not. That's the way we feel the heat of the sun -- by its light.",
"With regards to coating mirrors in a vacuum -- the tungsten element is usually heated electrically inside a va... | [
"Upvote for ASCII Art!"
] | [
"Radiated heat goes trough a vacume, also how to you think the suns heat got here?"
] |
[
"Do all objects have color? Can atoms be different colors?"
] | [
false
] | null | [
"Not everything has color in the strictest sense. Color is just the interaction of atoms or molecules (and their electrons) with photons that have a certain range of energy. We tend to narrow this definition as the interaction with light in the visible frequencies. If an atom or molecule can absorb or emit a pho... | [
"Yes. Everything with charges can interact with photons. "
] | [
"Thanks! So basically, everything has \"color\" meaning that everything has the ability to interact and absorb/re-emit photons?"
] |
[
"How exactly did comets deliver 326 million trillion gallons of water to Earth?"
] | [
false
] | Yes, comets are mostly composed of ice. But 326 million trillion gallons?? That sounds like a ridiculously high amount! How many comets must have hit the planet to deliver so much water? And where did the comet's ice come from in the first place? Thanks for all your answers! | [
"When thinking about this, it helps to remember that the Earth essentially started out as two asteroids colliding and sticking together to form one bigger asteroid. That then hit a third asteroid to make it slightly bigger... and thousands of collisions later you've built up something roughly the mass of the Earth.... | [
"Thanks for your answer! It makes a lot more sense to think that comets were actually involved in Earth's ",
"."
] | [
"if you look at all of Earth's water put into one sphere, it's not (relatively) that big.",
"http://img.gawkerassets.com/post/8/2012/05/global-water-volume-large.jpg",
"Edit: I realize this graphic has its issues. I believe that is all the surface water. And thank you for the Gold."
] |
[
"Could use of underarm deodorant lead to a strain of antibiotic-resistant bacteria?"
] | [
false
] | I understand that a lot of body odor is, in part, caused by the bacteria that colonize our armpits. I gather that one of the ways underarm deodorant works is by killing those bacteria. Less bacteria, less stink. I have also heard that using antibacterial hand soaps may not be a good idea because it could lead to str... | [
"The vast majority of commercial deodorants that I'm aware of use alcohol to temporarily kill bacteria. This is a pretty effective combination in concert with regular soap. As deodorants do not use any common compounds used as medical antibiotics, there is no concern over development of antibiotic-resistant bacteri... | [
"So, does this apply to hand sanitizers too? Since they primarily use alcohol, there is little risk of antibiotic-resistant bacteria?",
"What is in antibacterial hand soap that is risky? Couldn't we just formulate that with alcohol, too?"
] | [
"There are three things going on in soaps and hand sanitizers.",
"So hand sanitizers don't cause issues with resistance unless they contain antibiotics -- and that would be ridiculous, since they already have alcohol."
] |
[
"Do magnets ever run out of energy?"
] | [
false
] | null | [
"If a magnet is stored away from power lines, other magnets, high temperatures, and other factors that adversely affect the magnet, it will retain its magnetism essentially forever."
] | [
"So do you mean if nothing outside acts on it, it will stay the same?"
] | [
"pretty much. But that's not likely so it will probably slowly deteriorate through interaction with other stuff."
] |
[
"Why don't electrons cross the plates of charged capacitors?"
] | [
false
] | So I'm taking physics now and I still have trouble understanding this. If there is an electric field across the plates, why wouldn't the electrons just cross the space in between the plates instead of going the long route on the wire to the opposite plate. I'm also confused as to why one plate is positive and the other... | [
"Some small amount of current leaks across the dielectric in a capacitor. But if it's designed well, that will be a small effect.",
"The plates have opposite charges because opposite charges attract. If you place a positive charge on one plate, it will induce a negative charge on the other."
] | [
"The electrons don't cross because there is no path for them. The dielectric is an insulator. If the rated voltage is exceeded beyond some safety factor, there will be breakdown of the insulation, and current will flow.",
"The capacitor has to be charged by a power source which has a potential difference on its t... | [
"The air (or dielectric) is an insulator, which allows an electric field (a voltage gradient) to form across it, but not allow any electrons to cross it.",
"However, if the field is higher than the 'breakdown voltage', then you get a spark across the dielectric (kinda like how lightning works)"
] |
[
"Why isn't Mars' magnetic field as strong as Earth's?"
] | [
false
] | null | [
"Its not big enough to form a decent core, and the pressure/temperature at the core is insufficient to melt. To form a magnetic field on terrestrial planets, you require a spinning molten metal core (iron-nickel for Earth). Venus for instance, while being very similar in size and internal structure (same thickness'... | [
"No, it would be about 94.5% of Earth's gravity.",
"Centripetal acceleration is rω",
", and acceleration due to gravity is 9.8 m/s",
". The equatorial radius of Earth is 6378km, and if it was rotating at ω=2π/(6 hours), that's 6378 km × 4π",
" / (36 hours",
") = 0.54 m/s",
".",
"So, with a 6 hour day... | [
"What I am wondering is how does the inner core of the Earth still rotate to create this dynamo effect? I mean, friction between the crust and the core should have neutralized any initial momentum after 4+ billion years. Which force is keeping the inner core of the Earth moving?"
] |
[
"Have we no viable alternative to the use of gunpowder in conventional firearms?"
] | [
false
] | My (very) basic understanding of the use of gunpowder in a conventional firearm is that fundamentally, a certain number of powder grains are packed into a shell, above a blasting cap, and on top of that sits the bullet itself. Is there no alternative to the use of something as inconsistent as gunpowder and its grains? ... | [
"Gunpowder hasn't been used in modern firearms for about 100 years, it was replaced by Cordite from the late 19th Century, then by a mix of other propellants from about ww2 onwards.",
"If you mean no alternative to chemical propellants, then although there are designs for railguns or gauze guns, there isn't viabl... | [
"*Gauss. As in magnets. Gauze is the medical stuff (yes, that's the technical term. stuff.)\nBut yea, the Navy is actually working on getting rail guns on their ships. Not exactly hand held, but its there."
] | [
"Power isn't the problem, A big old bank of capacitors hooked up to a nuclear reactor, or an efficient large diesel can charge it up pretty quick. Its the massive damage done to the rails with every firing."
] |
[
"How fast does time travel in the void between galaxies."
] | [
false
] | Ok, so the stronger a gravity field, the slower time becomes: in the center of a black hole it is relatively stationary, compared to time's flow through Earth's gravitational field. What if there is no gravity at all? The further you get from any source of mass, the faster time would travel, right? If you park yourself... | [
"Gravitational time dilation is proportional to √g",
" , and g",
" is roughly 1-2U/c",
" in a gravitational potential U. The difference in gravitational potential between here and your space station is ",
"dominated by the gravitational well of the Milky Way",
", and is about 7x10",
" c",
" .",
"Thi... | [
"He's referring to the fact that, in GR, spacetime is generally a curved manifold, and so it's impossible to define a globally inertial frame of reference. You then need to specify an entire coordinate system, which means that one individual's trajectory is insufficient to define velocities globally. Basically, onc... | [
"To agree on two events being simultaneous, two observers need to look at each other and agree they're both sitting still. If one starts moving and the events are repeated, the observers won't both say the events happened at the same time anymore. ",
"Location doesn't matter as much as how things are moving... |
[
"I noticed there was a Tuberculosis vaccine listed on the CDC website. Is there any reason why it is not widely used in the USA?"
] | [
false
] | is the link in question if you're interested. | [
"It doesn't work very well.",
"However, a US Public Health Service trial of BCG in Georgia and Alabama published in 1966 showed an efficacy of only 14%,[7] and did much to convince the US it did not want to implement mass immunization with BCG. A further trial conducted in South India and published in 1979 (the \... | [
"This has good intentions but isn't entirely accurate.",
"A simple Mantoux test has fairly strict guidelines for size within North America, and an average test, even with the vaccine, should be <10mm. If the induration is over 10mm in these individuals, they are considered likely to be infected and tested furthe... | [
"This has good intentions but isn't entirely accurate.",
"A simple Mantoux test has fairly strict guidelines for size within North America, and an average test, even with the vaccine, should be <10mm. If the induration is over 10mm in these individuals, they are considered likely to be infected and tested furthe... |
[
"What are virtual particles and what evidence do we have for their existence?"
] | [
false
] | I've read a lot about black holes over the last few years, and one of the stranger things I read was due to half a randomly spawned being excited by losing its mate over the event horizon. Now, there is suggesting that the speed of light in a vacuum may be off due to the light quanta temporarily becoming a virtual elec... | [
"Virtual particles do not exist. They are a calculational technique. Quantum field theory can be formulated without reference to virtual particles. For example, Hawking radiation can be calculated with virtual particle methods, but it can also be calculated via tunneling. Hawking radiation is a trusted result n... | [
"From Professor Matt Strassler's Blog:",
"\"The term “virtual particle” is an endlessly confusing and confused subject for the layperson, and even for the non-expert scientist. I have read many books for laypeople (yes, I was a layperson once myself, and I remember, at the age of 16, reading about this stuff) and... | [
"As you are well aware in QFT you integrate time from -infinity to +infinity for any given process. This basically means that you assume that the initial particles in your calculation never interacted before and that your final particles never interact again. If any of these particles interact again (or prior), t... |
[
"How much energy does it take to go against the strong force of a nucleus and “unbind” it. For example if I could grip an atom could I rip it apart with my bare hands like I can rip apart a group of magnets? How much stronger than electromagnetism is the strong force and....."
] | [
false
] | Are there ways to increase the strength of the strong force like we can make magnets stronger or weaker? | [
"Atomic binding energies are on the scale of eV, while nuclear binding energies are on the scale of MeV. So it takes about a million times more energy to break apart a nucleus than to break apart an atom.",
"Are there ways to increase the strength of the strong force like we can make magnets stronger or weaker?",... | [
"The binding energy of a single helium nucleus is 28.3 MeV, which is equivalent to 4.534×10^-12 joules. If there was a way to grip a single atom, then you could definitely exert enough force to rip it apart with your hands.",
"But lets bump up the number of atoms to a 'real world' amount. Let's take one mole of h... | [
"Where does strong force comes from? I know gluons quarks together but what are gluons exactly and what gives them this power to hold things together? \nThey way that I see today’s particle physics, is a field of observation more than really understanding. We can predict, observe and describe what happens at subato... |
[
"I know of absolute zero at -273.15°C, but is there an absolute hot?"
] | [
false
] | null | [
"We don't know if there's a maximum temperature.",
"In certain models -- string theory is one of them -- there is a maximum temperature called the ",
". This arises because the number of possible high energy states increases sufficiently fast that as you put more energy into the system, it gets spread out over... | [
"The Planck temperature is 1.42 x 10",
" K.",
"At this temperature, the radiation emitted causes quantum gravitational effects. Lacking a unified theory of quantum gravity, our understanding of physics breaks down at or past this point."
] | [
"Very simply, think of it like wind resistance.",
"The Higgs field is like the air, and the massless particles are regular objects.",
"Do you HAVE wind resistance? Like, were you born with it? No. If you start moving really fast, you'll get some though. And different objects will have different amounts of wind ... |
[
"Do we know what kinds of possibilities exist for sky / atmosphere colors on other planets?"
] | [
false
] | I know that on Earth, our sky is blue (and the sun looks yellow or red) due to . Is Raleigh Scattering most dominant on Earth, and less of a factor on planets like Mars, where the atmosphere does not appear blue? Is there a name for the dominant process that leads to Mars's brownish sky? Furthermore, do we have any way... | [
"Mars' sky is a different colour due to the amount of dust in the atmosphere. Dust particles are bigger than air particles and so scatter light differently. This scattering can be described by ",
"Mie theory",
" but doesn't work entirely as dust particles aren't spherical. There are a number of approximations t... | [
"All of the visible spectrum should be available in theory. Because the particle sizes in the atmosphere are on the order of the wavelength of light (hundreds of nanometers), the color of the atmosphere is highly sensitive to the specific size/shape of the particles. This same property is what allows us to make th... | [
"Thanks so much for the helpful reply!"
] |
[
"How small can sound waves be and what's the smallest thing that produces a sound?"
] | [
false
] | Perhaps an ill-conceived question, but on a drive today me and my gf were talking about the sound that insects make and what we might hear had we sensitive enough hearing to detect the sounds of their body movements. | [
"Basically, once the sound level drops below the level of brownian noise (which is ever present due to thermal agitation of atoms), it gets very difficult to distinguish any sound source from the background.",
"You could definitely hear sounds that insect movement makes (you can pick it up with microphone) with s... | [
"I'm not sure that Brownian Motion really comes into play here. That would be significantly below the sound intensity of the background noise levels of our bodies. This background noise is primarily a result of blood flow.",
"Brownian Motion is more important to audio amplifiers, in which it is responsible for th... | [
"Well, the question was more of a \"if our hearing was much more sensitive\" type.",
"Of course acoustic Brownian noise rarely plays a role, but it is still a problem of you manage to eliminate all other sources."
] |
[
"Why don't the holes in the mesh of a microwave let out radiation?"
] | [
false
] | I'm thinking the effect is similar to a Faraday Cage, but I just don't understand why the wave doesn't weave in between the holes. Can anyone help me out? | [
"Microwaves are electromagnetic radiation, of a specific wavelenth. It is the same as light or X-Rays, just different \"size\". Look for \"electromagnetic spectrum\""
] | [
"Microwaves are electromagnetic radiation, of a specific wavelenth. It is the same as light or X-Rays, just different \"size\". Look for \"electromagnetic spectrum\""
] | [
"The wavelength range used for microwave ovens is 7.5 cm to 15 cm. The holes in the mesh are way smaller than that, around .5 cm diameter. "
] |
[
"If we found an organism claimed to be an alien, what would be the biological markers we could check to verify it is extraterrestrial, as opposed to a hitherto unknown terrestrial species?"
] | [
false
] | null | [
"It is technically possible that some sort of strange life arose independently on earth, and if it did it would be very difficult to distinguish from an alien. We could guess based on where we found it and how suited it was to its environment, but I can't think of any way of knowing for sure that it came from a dif... | [
"this one's REAL tricky...",
"an organism with some truly funky biology not shared with any organism anywhere on this planet MIGHT YET BE terrestrial -- multiple, very different things qualifying as 'life' may have formed via abiotic genesis multiple times on this planet",
"on the other hand, an organism with i... | [
"Does it have DNA and if so, is the code the same as a terrestrial organisms? If so, very unlikely to be alien. Add a quick check for the presence of highly conserved proteins like cytochrome c, if that is there and the same, definitely not alien."
] |
[
"Do synthesized flavors really have something in common with real \"juice\" flavors ?"
] | [
false
] | Recently I had some kind of lollipop with orange flavor, It tasted not a bit like a real orange but my brain has kind of accepted that it represents orange flavor. So my question: Are in synthesized flavours some kind of "patterns" of the real flavor or did some company tried over some time to create a tasty flavor whi... | [
"Are in synthesized flavours some kind of \"patterns\" of the real flavor or did some company tried over some time to create a tasty flavor which they just named \"orange-flavor\" ?",
"Both. The flavor of real fruit is causes by hundreds of chemicals. When a company wants to imitate a flavor they'll figure out wh... | [
"True. It seems that chocolate doesn't have one overwhelmingly dominant flavoring compound, which is why all artificial chocolate tastes like butt."
] | [
"Much of your perception of taste is actually related to smell. While the conventional belief that your tongue only detects sweet, salty, sour, and bitter (there are actually a few receptors on your tongue), and that they occur in specific areas (they are fairly evenly distributed over the tongue) is untrue, you c... |
[
"The lowest recorded temp. in modern history (−89.2 °C) was below the sublimation point of CO2. During colder eras, were polar regions laden with dry-ice? How did the deposition of CO2 into the polar regions affect atmospheric composition woldwide and how extensive were the dry-ice sheets?"
] | [
false
] | [deleted] | [
"I don't want to rain (CO2 frost) on the parade here but Vostok Station (where that temp was recorded) is at an altitude of 3,488 meters (or 11,444 feet) and ",
"this site",
" describes \"atmospheric pressure here is very low comprising 624.2 hPa on average for a year.\" ",
"So about 62% of standard temperatu... | [
"The sublimation point is defined for a pure compound at atmospheric pressure. As CO2 in the atmosphere is far from a pure compound (0.038 volume%), it will sublime at a lower temperature. To be precise, the temperature at which the vapor pressure is equal to the partial pressure in the atmosphere. I can't be bothe... | [
"Partial pressure of CO2 on Mars is about 600 Pa, which gives a sublimation point about -125 C. It gets to a low under -150 C at the poles, which is why the Martian ice caps do have dry ice. ",
"The north polar ice cap has only a seasonal covering of dry ice, but at the south pole the dry ice layer is 8 meters th... |
[
"Will a 12v electrical system work underwater?"
] | [
false
] | A few years ago I remember watching an episode of scrap heap challenge. On it that built some vehicles out of scrap that would run underwater. I vaguely remember that they were told that the 12v system would work underwater. So tell me, what will happen is I obtain a 12v sealed lead acid car battery and a 12v light bul... | [
"It depends on the conditions of the water. For de-ionized water, there will be almost no electrical effect on the circuit. I'd hazard that most taps have sufficiently low ionization that tap water won't do that much.",
"What if we were extreme and tried sea water? The resistivity of typical ",
"seawater",
" ... | [
"To be fair, dunking the wire in water will probably increase its current carrying capacity by a huge amount, since you're now immersing it in a much better cooling fluid than air."
] | [
"The only major risks are water leaking into the battery, and corrosion. electricity takes the path of least resistance, and even in salt water, it is much easier for charge to flow through wires connected to the terminal, through the light-bulb, and back to the battery than to arc through the water. "
] |
[
"Do we have the technical ability to implement accountable and secure voting in elections via the internet? What challenges have kept this from happening so far?"
] | [
false
] | [deleted] | [
"We have billions of financial transactions taking place every day over the internet. I don't see why would implementing an online voting system be very difficult. "
] | [
"Fundamentally I think your question is more a political science one than a computer science one. As others have mentioned, if people were perfectly trustworthy, then a secure voting system would be possible.",
"However, a computational security model can only take you so far. Ultimately you have to have a person... | [
"Voting and online banking have ",
" different requirements. In banking, you need to prove who you are, to show that money which you legally control should be transfers to some third party. While there are privacy issues, it is of the essence that the bank knows (at a minimum) who you are and how much money nee... |
[
"Every once in a while I notice a group of about 100 crows flying in formation around the same parking lot at the same time (5pm). At the same time, they all start squawking and find a lamp post or tree to sit on. Then a few minutes later they all start flying again. What are they doing?"
] | [
false
] | null | [
"Likely it is due to collective behaviour of the flock itself. ",
"Studies have shown",
" that bird flocks move in unison more as a matter of necessity rather than due to individual preferences (in absence of a single alpha). Models like the one in the paper I linked are ways mathematicians try to analyze and p... | [
"Could you maybe source some of that? I mean I know they're smart, but 7-10yo?"
] | [
"They may be gossiping.",
"Crows are among the smartest animals in the world, believe it or not. And they can get pretty social. With gatherings that big, I assume they are sharing information with eachother - where good food is, warning other crows about people that have been hostile towards them, sharing tricks... |
[
"How do popularity metrics like \"karma point\" systems influence social behavioral patterns in humans? Are there studies with interesting results that suggest that relationships exist between scoring trends and specific social behavioral patterns in representative populations?"
] | [
false
] | This one feels like a longshot. Not even sure this is qualified for this subreddit...let's see what happens. | [
"The general consensus I've seen in ToR is that karma acts as mainly an incentive to post things that most people will agree with. ",
"Karma really shouldn't be quite like that, because according to reddiquette you're not supposed to vote based on opinion, but just from what I've seen I think that in most large s... | [
"You might want to ask in ",
"/r/theoryofreddit"
] | [
"Limiting the subreddits on your main reddit also helps."
] |
[
"Why was it evolutionarily advantageous for some species of hippopotamus to evolve to whales?"
] | [
false
] | null | [
"From your phrasing I think you may have a misunderstanding of the evolutionary process. Hippopotami did not evolve into whales, rather both hippopotami and whales have a common ancestor. ",
"The ancestors that did become whales found it advantageous to be come more and more dependent on the aquatic environment -... | [
"Sorry about the late reply. I just remember this question from my Bio Final this semester. It was a phylogenetic tree that had Hippo as the main \"trunk\" and whales as the most current, shortest branch. Maybe my understanding is incorrect, but they way it was illustrated made it seem like Hippos WERE the commo... | [
"To elaborate on D_I_S_D and zerobinary, think about it like this: long ago, there was an animal that perhaps had some features of what we now call whales and hippos. That animal kept reproducing, as all successful life does, and its offspring kept slowly changing. Some offspring changed in ways that kept them suit... |
[
"Can matter hold charge in a vacuum?"
] | [
false
] | It's my understanding that charge is held by objects from the insulation of the atmosphere. If there is no atmosphere then what is stopping like charges from repelling one another? Also if this is true, then why is a vacuum considered the ideal insulator for a capacitor? | [
"Cathode ray tubes in old televisions and vacuum tubes or valves in old amplifiers (and some industrial radio equipment and analog computers like the one that broke Enigma) have current flow through a vacuum using the Thermionic (or Edison) Effect. ",
"By heating a wire, electrons can \"boil\" off the wire, and f... | [
"analog computers like the one that broke Enigma",
"The \"",
"Bombe",
"\" used to break Enigma was not an analog computer. It was an electro-mechanical Enigma simulator. ",
"The first digital computer, ",
"Eniac",
", did use vacuum tubes. ",
"BTW many people still use vacuum tubes without realizing it... | [
"Thanks, the lack of conductive channel is how I saw the atmosphere as an insulator. My followup question would be why heating is necessary if it's in a vacuum. If there's a completely resistant free path way (vacuum) between the cathode and anode then shouldn't the electrons flow the second there's any type of vol... |
[
"Is it possible for a virus to not have any antigens, and therefore be ignored by the immune system?"
] | [
false
] | Is this possible? Are there viruses like this already, or do all viruses require antigens to function? | [
"That's only true if you consider the gut and skin to be inside the body, which really isn't the case. (Of course, it is true that gut and skin microbes are partially exposed to the immune system, though in a strongly tolerizering context.) There are very very few viruses that live inside the body, where they are ... | [
"Immunodominance can also play a role within specific antigens. For example, PCV2 does a clever little thing. It has an immunodominant epitope that does stimulate an immune response, but it produces non-neutralizing antibodies. Sometimes these are referred to as decoy epitopes. In situations like that, epitope sp... | [
"Immunodominance can also play a role within specific antigens. For example, PCV2 does a clever little thing. It has an immunodominant epitope that does stimulate an immune response, but it produces non-neutralizing antibodies. Sometimes these are referred to as decoy epitopes. In situations like that, epitope sp... |
[
"It seems that cases of indigestion, GERD/reflux, and heartburn are commonplace compared to being seemingly rare 20+ years ago. Is this true? If so, why?"
] | [
false
] | It seems that as a 37 year old, growing up, I rarely heard of GERD and reflux. Nowadays, it seems so common. Why is this the case? | [
"There has been an increase in prevalence:",
"https://www.ncbi.nlm.nih.gov/pubmed/23853213",
"It's not that prevalence was non-existent before. Gerd has always had a high prevalence. Increases in obesity have almost certainly contributed to a higher prevalence recently. "
] | [
"It's exactly as you said: you rarely heard of it. It's not that it was less common before, you simply heard of it less. Today, with better communication and widespread knowledge of GERD and heartburn, people are capable of recognising and talking about it more. "
] | [
"Increases in obesity have almost certainly contributed to a higher prevalence recently. ",
"Can vouch for that. After the last 20kg were dropped I no longer needed to regularly take a PPI(nexium)."
] |
[
"Why do the bottoms of some clouds look flat?"
] | [
false
] | null | [
"You are probably referring to the Cumulus clouds. They are in fact the top of a column of warm air which is rising because it's less dense than the colder one. As the air raises, the air pressure decreases, and the temperature also. As it gets to a certain height, the water is not soluble anymore and it condenses ... | [
"FWIW, this question has been asked dozens or more times in this forum over the past few years. Here are a few links to previous threads on the topic",
"http://www.reddit.com/r/askscience/comments/2c84a0/why_are_clouds_flat_on_the_bottom/",
"http://www.reddit.com/r/askscience/comments/296m7m/why_are_the_bottoms... | [
"An easy way to think of it can with out going through the physics is; Air parcels can be unstable or stable, and when they are unstable clouds form. Imagine this like a ball in a bowl, if it is stable and the ball is kicked, then the ball will go up the sides and come back down. Now if it is unstable that bowl is ... |
[
"Is spicy food spicier for blind people?"
] | [
false
] | Seeing that their other senses are heightened | [
"Several studies have shown that blind people do not have heightened senses compared to people with normal vision.",
"I actually could only find one study on short notice, but I am quite certain there are other studies demonstrating that blind people do not have heightened senses.\n",
"Study",
", "
] | [
"While researching the above facts, I found some studies that might contradict my earlier claims. It could be that the age at which somebody goes blind might have an effect on the development of their other senses.\nThis ",
"study",
" found an increase in white matter (myleinated axons and glial cells-the axon ... | [
"Is the sense of taste heightened in general for blind and deaf people? "
] |
[
"What happens if the angle of attack of an airplane is not adjusted for earth's curvature during a flight. Stall or equilibrium?"
] | [
false
] | I am assuming the pilot, or the autopilot, has to adjust the angle of attack (or whatever the correct term is) to keep an aircraft at a constant altitute, due to earth's curvature. In absence of that adjustment, does the aircraft stall or eventually come into an equilibrium state as the atmosphere gets thinner. | [
"It will stall eventually. In practice, the aerodynamics and controls are such, that the force of gravity and the air pulls it into it's current angle of attack. Holding the angle of attack constant in the inertial frame through the curvature of earth requires activity adjusting the angle of attack."
] | [
"With control surfaces fixed with constant throttle, any plane will fly at a constant altitude with a constant pitch until it runs out of fuel.",
"That pitch will be constant to the horizon, the curvature of the earth is cancelled out by flight dynamics.",
"The pitch isn't ",
" constant, it oscillates at two ... | [
"I am assuming the pilot, or the autopilot, has to adjust the angle of attack (or whatever the correct term is) to keep an aircraft at a constant altitude, due to earth's curvature.",
"This first assumption is wrong. A pilot or autopilot does not have to take into account the earth curvature. ",
"In absence of ... |
[
"Would a planet-sized ball of liquid water in space have a solid core of \"hot ice\" the same way Earth's inner core is solid?"
] | [
false
] | Earth's inner core is solid because of the immense pressure, and Jupiter's core is theorized to possibly be liquid and maybe even solid metallic hydrogen. Would water form this sort of pressure-induced solid state at the core of a planet-sized ball of water? | [
"At high pressures water will form a solid at any temperature. Wikipedia has a rather detailed phase diagram for water:",
"http://en.wikipedia.org/wiki/File:Phase_diagram_of_water.svg",
"Of course the specifics will vary; it'd be very unlikely for a planet to form exclusively from water, so getting a water-only... | [
"This isn't true. The phase diagram you link to stops at temperatures far too low to be relevant to planetary interiors. A better one would be ",
"http://math.ucr.edu/home/baez/cavazzoni_ice_phases.png",
"Note that the specific boundaries here are a bit outdated, but it's accurate enough for our purposes.",
"... | [
"what does metallic ice look like and do?"
] |
[
"I suffer from Aggressive-Obsessive Obsessive Compulsive Disorder, please help me."
] | [
false
] | null | [
"This breaks Reddit’s rule against ",
"medical advice",
".",
"Please see our ",
"FAQ."
] | [
"Oh, sorry. I'll take this down immediately."
] | [
"That's ok, it's been taken down already by our system. Honestly I'd think seriously about contacting a doctor or medical health professional. If money's an issue, try to find some local groups/hotlines or support services. Perhpaps the good people over at ",
"/r/mentalhealth",
" might be able to point you in t... |
[
"Can an object look as if it's travelling faster than light if it's heading toward you at near the speed of light?"
] | [
false
] | Let's say there's an alien spaceship which is going to do a fly-by of Earth at 90% light speed. If it's first detected at a distance of 20 light minutes by observers on Earth, then by the time that light made its 20 minute journey, the spaceship itself will have covered 90% of the distance (18 light minutes), and will ... | [
"The alien spaceship would appear stretched out over the distance of roughly 18 light minutes when it is at 2 light minutes away, and the stretched out spaceship would appear to be traveling at 90% the speed of light.",
"Edit: Actually, scratch that. It seems there is more at work then just the stretching as mo... | [
"Against what I thought originally, I'd have to say yes, it would look like they are approaching you at greater than c. In attempting to disprove it I made this chart and started with their speed as 1/2c :",
"From the final two rows we can see that the ship has appeared to move 10 lm in 10 min or exactly the spee... | [
"An observer from earth would see the ship's clock slowed down by a factor gamma and an observer on the ship would see clocks on Earth slowed down by the same amount.",
"I need to get my head around the rest of the problem before I can answer it but my instinct says there is no way you can see an object as moving... |
[
"Is there a maximum voltage obtainable by simply stacking transformers one after the other?"
] | [
false
] | What stops me from stacking 10 transformers which each multiply the voltage by 100, getting a compounded 10 fold increase in voltage, with an initial voltage of 1 V, each electron would get an energy increase of 10 eV, easily surpassing the LHC, so what stops this from happening? | [
"Darn physics. Again.",
"First you'll need to account for different levels of isolation. At high voltages it gets hard.",
"Next - internal resistances. Once your current is down to a few uA that pesky 0.05ohm inherent resistance suddenly spoils the party. Not much left to drive the next stage.",
"Also you are... | [
"Extremely dangerous. One cool trick is to denature the proteins in your retinae, skin and subscutaneous tissues and induce fibrillation."
] | [
"Extremely dangerous. One cool trick is to denature the proteins in your retinae, skin and subscutaneous tissues and induce fibrillation."
] |
[
"Smallpox is officially eradicated, and IIRC, even the lab samples have now been destroyed. Are we \"getting close\" with anything else -- specifically, polio and tuberculosis?"
] | [
false
] | I can't recall the last time I heard about a case of polio; and I'd say the same about TB but there are adverts on TV that warn about TB as a side effect -- which is a completely separate question. I also know that malaria programs are making good progress, but they're a long way from "eradication in the wild". Thanks! | [
"The Smallpox virus samples ",
" been destroyed:",
"Since 1984, the Centers for Disease Control and Prevention (CDC) in the United States and the State Research Center of Virology and Biotechnology VECTOR in Koltsovo, Russia are the only two labs authorized by the WHO to hold stocks of live smallpox virus.",
... | [
"We have also eradicated Rinderpest.",
"The next best candidate is probably polio - types 2 and 3 are basically no longer present in the wild. Only Type 1 polio is still endemic to a couple pockets, but it's been hard to get good numbers in the past two years, and some areas have had lower vaccination rates. We... | [
"TB is far from eradicated.",
"~1.5M deaths per year. It was the most common infectious-disease cause of death worldwide until the Covid pandemic (and it will be again, after the Covid pandemic)."
] |
[
"Why does the Panama Canal have locks?"
] | [
false
] | More directly, why are the ocean levels different on either side of the canal? It seems that the ocean would eventually smooth itself out, barring tides, and I don't think the tides are nearly influential. Or are the locks just to get over the terrain of Panama herself? | [
"Found a thread on another forum ",
"here",
", answering this exact question. There is height difference on the terrain to overcome, the oceans actually have different tides that have an impact, trade winds cause a buildup of water on one side, and some more minor impacts as height of the geoid on either side o... | [
"There is a lake (",
"Gutan Lake",
") used as part of the canal which is above sea-level. They use the locks to lift boats up to the lake. So, basically, it's to get over the terrain."
] | [
"The locks were mostly to get over the terrain. Also the US engineers figured out they could get a whole big section of the canal for free by damming the Chagres River to make a giant lake, Lake Gatun, where boats can travel and pass each other with no effort. This solved the need to dig this portion, and also solv... |
[
"What makes cancer immunology treatment so ineffective?"
] | [
false
] | I read that editing immune cells and reinjecting them into the body only works in about 1 in 5 patients. So what exactly makes it so ineffective? | [
"First thing, \"cancer immunology treatment\" encompasses many, many things ranging from the well established (like IL-2 administration, which is usually used in combination with other therapeutics) to the recently adopted (like CTLA-4 or PD-1 blockade, which were approved in in the last 3 years) to the highly expe... | [
"I would also add tumor heterogeneity to the answer. ",
"Tumors can be highly heterogeneous on a microscopic level. They feature a broad range of different cell types: Cancer stem cells (that may or may not exist, depending on the cancer entity) can reproduce and spawn progenitor cells which may differentiate int... | [
"The answers so far look good. I'll just add 1 little thing. One of the hallmarks of cancer, as outlined in this ",
"landmark paper",
", is that the tumor population can either evade or suppress immune intervention, meaning that the cancer could be suppressing attempts at immunotherapy."
] |
[
"Are there any long-term studies where intelligence is selectively bred in animals?"
] | [
false
] | I read an article about the breeding of foxes in Russia over the last century to make them more docile and domesticated for fur production. -Have any scientists tested animal's intelligence (say a rat that learns mazes well) and then bred the smartest specimens selectively across many generations? I guess rats becaus... | [
"Yes! Selection for increased learning has been demonstrated in a number of experiments in that poster child for evolution, Drosophila (fruit flies). ",
"Here's",
" an excellent comprehensive review of these experiments."
] | [
"Is there something I am missing that would make this difficult?",
"The biggest issue is that selective breeding tends to get exactly what you select for, and not what you think you're selecting for. You'd need to figure out how exactly to measure general intelligence.",
"This is a very difficult problem, so so... | [
"http://en.wikipedia.org/wiki/Tryon's_Rat_Experiment",
" ",
"\"maze bright\" rats were a business jargon thing for a while, silly really!"
] |
[
"Is fusion with Bose Einstein Condensate possible?"
] | [
false
] | I was reading how BEC makes a sort of matter laser and I was wondering could this be used in fusion seeing how when the atoms are super coooled they clump? | [
"if you're referring to nuclear fusion, then probably not. When you read that atoms \"clump\" in bose-einstein condensates, that doesn't mean that their nuclei are fusing. It means that the atoms are in what is called a degenerate ground state. That means that all of the atoms in the condensate occupy the same q... | [
"Sadly no. The moment anything approaching a fusion reaction occured, the BEC would be instantaneously heated above 0K and the degenerate state would collapse.",
"It is possible to crush matter together in order to force it to fuse by something approximating the same method (ultra cooling by lasers) but instead ... | [
"What about using degenerate matter and degeneracy pressure to create the pressure not necessarily the 10 million degrees for fusion?"
] |
[
"How much would it cost to get a 1lb satellite into orbit to give the internet a continuous video feed of the entire Earth?"
] | [
false
] | null | [
"There's really two questions here: how much would it cost to launch a minimal satellite to generate a video feed, and what is the definition of \"minimal satellite\"? Typically, launch costs are ball-parked according to mass in the range of about 10,000 to 15,000 USD per pound, but that's assuming a normal-sized ... | [
"I think the point to which RRC is objecting is that ",
"one-pound satellite that's anything more than a hunk of inert metal?",
"To properly shield, power, store and transcieve data, provide orbital correction, etc for all under a pound would be a huge undertaking."
] | [
"Sorry. Stupid Wild-Assed Guess."
] |
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