title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"When an Iconic satellite (Hubble, ISS) is at the end of its life cycle, could we launch it passengerless into a stable orbit such as those of comets?"
] | [
false
] | null | [
"If we could \"ignore cost to a degree\" ? No. The cost would be really too high.",
"If we could totally \"ignore cost\" ? Yes. You could accelerate the object so it's orbit becomes really elongated, but it still wouldn't have the orbit of a comet. If you want your satellite to have a comet-like orbit, you'll hav... | [
"If you would burn toward prograde at the periapsis you could fairly easily put the hubble in an eccentric orbit. That would let it stay up for quite a bit longer, but eventually it would fall back to earth because the periapse would still be at its original altitude. The ISS is very massive and would require man... | [
"Well I figured that with a very high apoapsis, it would take some time for the atmosphere to decelerate the satellite enough to make it burn. Plus, if we have enough fuel to put a sat on this kind of orbit \"for fun\", we probably have enough to circularize the orbit."
] |
[
"Is it more fuel efficient for a car to accelerate more before going up a hill or maintain a constant speed before and during the climb?"
] | [
false
] | I believe constraints would be required. So, let's say I restrict my speeds to be in a certain range, for example: between 20mph and 40mph. | [
"I have hauled logs off highway for many winters where my average gross weight per load was around 78,000 kgs (170,000lbs). Since fuel was my biggest expense I have spent many hours comparing my fuel consumption to varying driving habits. Over the years I have noticed that by following the following rules I can s... | [
"This is a great practical answer, but:",
"One gallon of gas has enough energy to create 10 horsepower in an internal combustion engine.",
"No: horsepower is not a unit of energy. One gallon of gas standardly contains about 114000BTU - that's 28,743 KCal, or 120M Joules, or 33KWh",
"Diesel engines can achieve... | [
"Actually, it gets more complicated than that, because it may be still more efficient to let yourself slow down somewhat as you climb the incline, because the force being used required of your engine to maintain a given speed on an incline is not the same as the force required of that same engine on a level surface... |
[
"If the difference between the cells in our body is not the DNA that they contain but rather their genetic expression of that DNA, do we have a way to measure or examine that expression?"
] | [
false
] | null | [
"Yes there are many ways, measuring gene expression is done all the time in the lab and is a fundamental part of just about any genetics or molecular biology research. It's also used in medical diagnostics, for example, ",
"tumors are sometimes screened to see what genes they are expressing",
" as this can hel... | [
"Now maybe you want to now the principle behind the majority of these methods ?",
" ",
"Gene expression",
" is done in 2 steps. First, the ",
" (transcription). Then, ",
" (translation); which are the molecules that actually do stuff in the cell. Even for the most expressed genes, there's only a few copie... | [
"Good summary, but I would add some techniques to the list:",
"Gene Chips",
" allow you to convert the abundance of specific RNA molecules into red/green fluorescent intensities. ",
"RNA sequencing",
" is mentioned above, and allows you to measure a large subset of the RNA produced by sequencing millions of... |
[
"Do organisms with shorter lifespans and greater reproductive rates evolve \"faster\" than others? Does this have anything to do with why amphibians show mutations from environmental contamination faster than we do?"
] | [
false
] | null | [
"Yes. The faster the reproductive cycle the faster evolution occurs. Every time a species genetic code is duplicated there are mutations which cause evolution. Whether it is a mammal, insect or bacteria the faster the genetic code can be passed on the faster evolution can occur.",
"A great example of this is g... | [
"http://mblogs.discovermagazine.com/loom/2012/03/14/fifty-seven-years-of-darkness/",
"Evidence"
] | [
"A strange result is that over geologic time, rates of evolution for different groups are generally similar.\nThis is rates measured in units like ",
"darwins or haldanes",
".",
"Rates in darwins and haldanes are surprisingly consistent for various groups (this has mostly been studied in mammals, but other ve... |
[
"Practical to reduce A/C load on engine by changing pulley sizes?"
] | [
false
] | I have a old Opel Astra 1400 '96 with an after market A/C. It puts so much load on the (small) engine that I basically cannot use it, unless I'm going downhill. I'm considering changing the engine pulley on the A/C drive belt to a 50% larger pulley size, to reduce the drag on the engine. I know this would be at the expense of less effective cooling, but it's either that or nothing. Will this reduce the effectiveness to much? Or have other practical downsides? | [
"Sounds like a reasonable modification to me. I would check the high and low side pressure after the mod to see if it's still reasonable. if the pressure is too low, you may have to modify the orifice tube (if it has one) to get the pressure differential back up due to the decreased flow."
] | [
"also, just an afterthought. does it happen to run ok when your engine is above idle but bog down during idle? normally a/c systems are supposed to open up the IAC to compensate for the increased load of the compressor. if it's an aftermarket system this may have been left out."
] | [
"There should be a wide open throttle switch which cuts the compressor off during WOT. Newer cars use the throttle position sensor position to do it, but you could mount a microswitch if none exists. "
] |
[
"What would happen if you took a chunk of bismuth into a room with an active MRI machine? Would it fly out of your hand and be shoved against the wall?"
] | [
false
] | null | [
"That's a great answer, but to the wrong question. He's asking what happens to bismuth in a very strong magnetic field...."
] | [
"All MRI are always active. The only times that an MRI's magnet will turn off is because something has gone wrong and it has enter a quench on its own, it needs to be moved and the magnet is progressively weakened or turned off, or it is done in order to save someone's life. Under normal operating procedure the mag... | [
"I just had an MRI yesterday, and the noises involved seemed to indicate it was not always active.",
"These are the gradient coils, which are switched on and off to create images in the X, Y and Z directions.",
"The static field, B0, is never turned off. You may have noticed the very large door that keeps the s... |
[
"Is it possible for something like Olympus Mons to form in Earth-like conditions?"
] | [
false
] | I was thinking about this and I am quite curious if something like Olympus Mons could form here. (Not really an exact replica, but somewhat similar with some changes.) The characteristics I am thinking about is pretty much a stationary plate, a powerful hotspot (similar to the Hawaiian hotspot) and a stable crust (a thick craton) for such a volcano (more like a really high plateau) to stand on with minimal sinkage. The conditions met would not really exist on Earth at some time or another, but the closest thing to that, in my opinion, is the Tibesti mountains in Africa, where a hotspot underneath the Saharan Meta-craton produced a few volcanoes. Could it exist in some form and, if so, what process would lead to that and how would it form? | [
", not without fundamental changes to the tectonic regime, lithospheric structure, and the surface conditions (i.e., atmosphere, hydrosphere, erosional mechanims, etc.) to the point where Earth really wouldn't be much at all like Earth.",
"To dive in more, ",
" You hit on some of the big ones, but it requires a... | [
"It would still have to form on a craton on a plate that remained fixed in an absolute reference frame for the time period and you're still running up against all the myriad of surface processes that will effectively limit the height/mass of the edifice. I.e., virtually all of the criteria are unlikely to be satisf... | [
"The big problem is CrustalTrudger's point 4. If you put a huge weight on the lithosphere it bends downwards, with the underlying asthenosphere being pushed to the side. The oceanic lithosphere under the Hawaiian islands is bent down by about 3 km, making the mountains 3 km lower than they would otherwise be.",
"... |
[
"Why do we use water in steam based energy production instead of alcohol?"
] | [
false
] | [deleted] | [
"Never underestimate the power of \"because it's cheap\".",
"Plus, water has a really high thermal capacity, which means that in a typical cycle a LOT of energy can be moved around with relatively little of it. Typically power cycles are limited by the temperature anyway (can only get so hot in your turbine befor... | [
"1)Alcohol is flammable. A leaky pipe or fitting could cause an explosion. ",
"2)At high temperatures alcohol can pyrolize and convert to a range of other compounds such as acetylaldehyde, methanol, carbon monoxide, ethane, hydrogen, benzene, and carbon char or soot.",
"You don't want your boiler pipes to clog ... | [
"Mercury has lower specific heat by weight, but better specific heat by volume and a higher boiling point. There was an era early in the history of electricity production when mercury turbines were favored.",
"Ammonia has a lower boiling point than water which is useful if your heat source isn't very hot. It is a... |
[
"If the Moon was created by an asteroid hitting the Earth, why didn't Earth get knocked out of its orbit around the Sun?"
] | [
false
] | [deleted] | [
"(Very) roughly, the earth's mass is 6E24 kg and the moon's is 7E22 kg, so roughly a hundred times more massive. To continue with the truck analogy, if it's a 3-ton pickup truck, it's like throwing a 60 pound rock at it. Yes, that's a big rock, but it won't do anything noticeable to deviate the path of the truck."
... | [
"Because the earth is a whole lot heavier than the moon. Even an asteroid large enough to crash and knock out a moon-sized piece of the Earth would barely change the orbital speed of the Earth. Think of it like standing on the highway and throwing a rock as hard as you can at an oncoming semi-truck. Then you wonde... | [
"Riiight, I was thinking volume instead of mass. Thank you both for clearing it up for me!"
] |
[
"What can be heard in a heartbeat?"
] | [
false
] | I'm trying to model the sound of a human heartbeat. I'm surprised at how little hard information I've been able to dig up on what is in the sound of a normal heartbeat. I know a resting rate is around 60-80bpm, a normal systolic/diastolic ratio is 1.5, with 1.56 indicating high blood pressure -presumably lower for low blood pressure? how low? - and does the ratio increase with rate?. I was surprised to learn that there's such a thing as a too regular heart beat, so theres an optimal level of variance - but what is that level? - and what kind of variance? - gaussian? bimodal? ; Then there's all the other sounds. I can find plenty of information on pathological states, but that's not what I want. In recordings of normal heartbeats I can pick out the "S3" and "atrial" sounds - but what is the normal range of timings and amplitudes for them? (beyond just "kentucky" and "tennesee") ; Looking at a spectrum of a normal heartbeat I found what look like about 7 more-or-less regular small peaks. Could they be just artefacts of the recording, or do they have names? - thanks [EDIT] - thanks to all who replied. is a handy animation that links a lot of heart stuff together. | [
"Video describing an EKG--needed for fundamentals and if you're anything like me, a visual cue for this is absolutely necessary",
"This is what you're looking for in terms of time frames. Everything is in milliseconds so you'll have to convert according to your needs in order to maintain the proper ratios. EKGs a... | [
"Oh, I see. Here's a ",
"paper from 2006 that says",
":",
"There are currently no widely available large scale databases for development or evaluation purposes; the Johns Hopkins Cardiac Auscultation Recording Database is an excellent resource for research purposes, although it contains predominantly pediatri... | [
"Thank you! - lots of good information there, and I think I have plenty to go on now.",
"This is just for an art project - I'm making stochastic generative sounds one of which is a heartbeat, but coming from a science background I want to make it accurate enough that a doctor could hear it and say - yep, that sou... |
[
"Is it possible to form metallic bonds between Uranium and Sodium?"
] | [
false
] | I was having a discussion about inner transition metals with a friend of mine, our class won't be covering them much if at all, so naturally we want to know more about them. We found that metals can bond with other metals through metallic bonding. So we are curious. Can a metal with a low melting point such as sodium bond with one with a melting point nearly 5x higher such as Uranium? What would happen if you attempted to bond Sodium and Uranium? | [
"Yes, there is nothing preventing alloy formation between low and high melting metals. You can even make alloys with mercury, which we call amalgams. There is apparently documented evidence that a sodium-uranium alloy exists, though I can't find any information on its properties. It's possible that the informati... | [
"The properties of elemental sodium are nothing like those of ionic sodium, so there is little basis for comparison there. Sodium cooled reactors, just like most modern generation systems, are better at handling catastrophic failure than previous rector designs. For example, the Fukushima incident likely wouldn't... | [
"Kind of, there really is no draining out of water in any kind of water reactor unless something has gone very wrong.. The issue is that if the pumps stop working, the water gets superheated and can rupture containment.",
"There is no \"solution\" in a sodium reactor. The coolant is literally molten sodium meta... |
[
"Is thorium a viable option for supplying energy in America?"
] | [
false
] | I recently saw about thorium power, and it seems to suggest that thorium, if given enough support by the US government, could solve all our energy problems (I'll believe it when I see it). Physics/chemistry/energy experts, is thorium as good as this documentary suggests, or does this documentary contain some BS? | [
"http://www.reddit.com/r/askscience/comments/psu63/whats_the_truth_about_thorium_reactors_and_why/",
"http://www.reddit.com/r/askscience/comments/mz8pr/what_are_the_downsides_to_a_molten_salt_thorium/",
"http://www.reddit.com/r/askscience/comments/lmnep/ive_heard_all_about_the_positives_of_thorium/",
"http://... | [
"To summarize the content from those links:",
"I suppose that these arguments are valid, but they don't seem particularly strong to me. (In fact, I would say that any armchair scientist/journalist could come up with a similar list of criticisms with only a minimal amount of research.)",
"For example, the first... | [
"The Guardian article (from The Ecologist) is very misleading. Here is debunking:\n",
"http://energyfromthorium.com/rees-article-rebuttal/",
"IEER \"factsheet\" is also very misleading and full of inaccuracies. Debunked here:\n",
"http://energyfromthorium.com/ieer-rebuttal/"
] |
[
"Could Facial Recognition software work without a database?"
] | [
false
] | null | [
"You seem to be asking two different questions. The answer to your main question is yes -- that's what your camera / phone do... (for facial detection that is)"
] | [
"I don't understand what you're trying to ask... Can you rephrase?"
] | [
"I don't understand what you're trying to ask... Can you rephrase?"
] |
[
"Harmonics discussion: am I severely mistaken?"
] | [
false
] | Really sorry if this is the wrong place to post this. I was commenting on a post explaining what pythagorean tuning was, but the author of the music in the post insists that lowering the reference pitch by a few Hz affects the scale. Harmonics are just a ratio, correct? So lowering the reference pitch by a few Hz should lower the whole thing relative to the reference, and the ratios between the harmonics/notes should be the same, right? Am I mistaken, or is the author of this music mistaken? He or she keeps claiming they are an engineer and thus have a better understanding of harmonics than me, but then I find that this reddit user actually reposted our entire conversation to website, which didn't give me much faith in his scientific knowledge. However, I'm not one to commit an fallacy, so I would very much like to know if it is my understanding that is flawed, and if someone could correct me if it is. | [
"Though the harmonics of a fundamental are always going to be integer multiples in frequency, you can freely and arbitrarily select which fundamental frequencies you want to construct music out of. There is a widely used standard for what the fundamental frequencies should be, but it seemed like the gist of the au... | [
"Having read the conversation, I'm pretty sure the author's (wilfully or otherwise) misunderstanding what you say as commenting on whether or not Pythagorean tuning is different from equal temperament, which it obviously is.",
"You can change the reference frequency at will with no mathematical effects on the har... | [
"Yes, that's what pythagorean tuning is (differently spaced notes) - I fully appreciated this part. I was saying to the author that the fundamental frequency (432Hz) is arbitrary, and simply shifts the rest of the scale accordingly. "
] |
[
"Lets say we have a gear. If it's spinning at a high RPM, what direction do the particles want to travel?"
] | [
false
] | [deleted] | [
"If you imagine that all of the particles in the gear suddenly became \"unstuck\" from one another, the particles would move continue moving in the direction they were moving just before they became free to fly about (they would move along with the arrows seen in ",
"this picture",
"). Particles close to the ce... | [
"Read up on ",
"centripetal force",
"."
] | [
"This, not directly out from center."
] |
[
"During transformation, in genetic cloning using bacteria plasmids as vectors, do bacteria take in the new plasmid while their plasmid exits?"
] | [
false
] | The bacteria used in cloning already have plasmids from my understanding. And when we insert a genetically altered plasmid, say for insulin production, and we instigate a transformation reaction the bacteria takes in the new plasmid. What happens to their old, original plasmid? It would be odd if they had two distinct plasmids, or at least I would guess it would be inefficient at producing insulin(in this case) | [
"Why do you use wild type e.coli? I thought labs tended to just use mutants "
] | [
"Why do you use wild type e.coli? I thought labs tended to just use mutants "
] | [
"Yeah, we use strains that are 'competent,' that is, they are already very good at taking up plasmids (under the right conditions). Specifically, a commonly used strain (dh5 alpha) was modified at the genetic level; genes encoding endonucleases (that chew up exogenous genetic material) and recA (involved in geneti... |
[
"Does adiabatic warming occur when air descends in the Earth's polar cells?"
] | [
false
] | If adiabatic warming occurs when air in a Hadley cell descends, would it not also occur when air descends in a polar cell? If not, why? | [
"Sure! Sinking air warms by compression, so air sinking at the poles is warmer at the surface then where it began in the upper troposphere. This also causes a drop in relative humdity and produces clear skies. That is a big reason why both the north and south poles have arid climates."
] | [
"I see! So said air must be ",
" cold just before descending. Thank you!"
] | [
"The adiabatic warming is the reversal of the adiabatic cooling that happens when the air first rises net gain if you look at it over the whole cycle.",
"Now if you are loosing moisture then you get warmer air that is the effect that produces your Föhns and similar hot winds."
] |
[
"If you think you've been exposed to a virus, would changing you living habits (e.g. fasting, reducing all sugar intake to almost none, or putting a bunch of secondary molecules like berberry into you system) do anything to inhibit viral reproduction or spread?"
] | [
false
] | null | [
"You know what you call traditional medicine that has shown to be effective in scientific studies?",
"Medicine. Traditional medicine is what is left over.",
"So traditional medicines are not the kind of medicines you are going to get scientists to give you a scientific opinion about in a subreddit called AskSc... | [
"Cutting your immune system off from what it needs to try and fight off anything is a bad idea."
] | [
"No. Viruses do not metabolize, they hijack existing cells, and you have plenty of those. So you are not going to \"starve\" the virus...if anything, fasting or changing sugar intake would probably just depress your immune system and make things worse.",
"I don't know anything about burberry, except it is sold ... |
[
"I had orange juice in a stainless steel water bottle, with a plastic lid. It sat in my hot car for 2 days. When I brought it inside to clean it, the cap shot off (like a champaign cork). Then inside, was a bunch of fog, and the bottle got really cold. What happened?"
] | [
false
] | null | [
"The orange juice fermented. Over those two days it built up a head of CO2 pressure.",
"The vapour and cooling are a product of rapid decompression."
] | [
"homebrewer here, two days in a warm temp op is very lucky the cap didn't fail"
] | [
"Some sort of decomposition is likely the cause of increase in gas pressure. Fermentation is the most likely cause due to high sugar content of orange juice. I am impressed that the plastic lid managed to contain such a high gauge pressure that would allow you to notice a temperature change, but it's certainly no... |
[
"How long would it take two bowling balls (one metre apart from each other) to collide in empty space?"
] | [
false
] | How long would it take two bowling balls (one metre apart from each other) to collide in empty space assuming they had no previous velocity? In Universe Sandbox 2, they only take about a day to collide. Would this actually happen? | [
"We can just use Kepler's third law to find the period of the motion, from which we can get the collision time. No need for any fancy calculations, or any need to approximate the acceleration as constant (because it most certainly is not). But if you want to solve the problem from first principles...",
"Put the c... | [
"This is a second-order nonlinear differential equation and I'm not aware of an analytic solution",
"The energy is a first integral of the motion, giving you an equation for conservation of energy. The resulting first order differential equation is separable and can be solved via a simple trigonometric substituti... | [
"This is a second-order nonlinear differential equation and I'm not aware of an analytic solution",
"The energy is a first integral of the motion, giving you an equation for conservation of energy. The resulting first order differential equation is separable and can be solved via a simple trigonometric substituti... |
[
"Why do infants lose certain abilities around 6 months old, such as distinguishing between different language sounds and different primates' faces?"
] | [
false
] | null | [
"It depends on who you ask. There are two major accounts:",
"The critical period hypothesis posits that humans have enhanced sensitivity to certain contrasts (typically linguistic, but you've noted some others as well) that goes away as we age. This is usually held to be a maturational process, and it follows tha... | [
"I think a more general description might be that infants don't know what features / dimensions are relevant for discrimination / tasks / living / survival. ",
"An interesting example of this might be a gradual loss of mirror symmetry invariance which seems to happen as we learn how to read. For most objects in t... | [
"I'm not sure I follow your question, so I'll take both of the interpretations I see.",
"In one sense, one might worry about the brain \"filling up\", like a sponge that cannot retain any more water. We don't have good evidence for this being the case, and I think it's unlikely because the amount of neurons and p... |
[
"Exactly how does water temperature affect Dissolved Oxygen?"
] | [
false
] | I heard in class that the temperature of water can affect its ability to hold dissolved oxygen, How that that work? | [
"Temperature effects the amount of any gas that can be dissolved in water. When oxygen dissolves in water, intermolecular forces between the water and oxygen \"hold\" them together. As the water-oxygen solution gains energy, heat, the bonds between gas and water break, releasing the oxygen."
] | [
"Thanks, good to know"
] | [
"It's worth adding that heat actually tends to make solids dissolve better and gas dissolve worse. This is because gases want to be more spread out than liquids, and heat increases this. Meanwhile, solids want to be less spread out than liquids, and heat makes them spread out better."
] |
[
"Is the imposter syndrom more common among people who are a minority in their job?"
] | [
false
] | null | [
"Imposter syndrome is common for those that come from families of over achievers. It occurs in both women and men, as well as all races. However, it's more common among minorities. So, to answer your question, yes. Here's more info if you'd like to have a look: ",
"http://www.apa.org/gradpsych/2013/11/fraud.aspx"... | [
"I believe, generally, being white is a statistical predictor for more academic achievement in the north american education system. While it is a statistical correlation (and admittedly we can't say for certain) this is likely due to white people being statistically more likely to be financially secure/having paren... | [
"I believe, generally, being white is a statistical predictor for more academic achievement in the north american education system. While it is a statistical correlation (and admittedly we can't say for certain) this is likely due to white people being statistically more likely to be financially secure/having paren... |
[
"Do animals have dopamine and serotonin?"
] | [
false
] | null | [
"Yes the whole animal kingdom has dopamine. There is even one report that sponges (which don't have a nervous system) have dopamine, yet its function in sponges are not known.\nThere is dopamine in jellyfish, hydra or corals. Because of this we know that the emergence of dopamine as a neurotransmitter goes back to ... | [
"Dopamine also plays a huge role in regulating your movement. Parkinson’s disease is caused by low levels of dopaminergic cells in your basal ganglia (very primitive portion of your brain that controls movement). I couldn’t imagine any kind of animal with a brain (these structures are very evolutionarily old) not h... | [
"A neurotransmitter is a substance that helps neurons (hence the first part of the name) to cross the gap to the next neuron and transmit (hence the second part of the name) information.",
"Plants and fungi don't have neurons at all."
] |
[
"If the sun were to disappear for 10 seconds, what (if anything) would happen hear on earth?"
] | [
false
] | null | [
"I think the idea was what would happen if the light from the sun were prevented from reaching the Earth for 10 seconds and then uninhibited afterwards. Although I suppose I'm interested if the rapid removal of the sun's gravitational pull would have a significant effect, but you seem to be saying that somehow not ... | [
"I think the idea was what would happen if the light from the sun were prevented from reaching the Earth for 10 seconds and then uninhibited afterwards. Although I suppose I'm interested if the rapid removal of the sun's gravitational pull would have a significant effect, but you seem to be saying that somehow not ... | [
"This question will always be a bit ill-defined, since there is no physical way to make the sun disappear for 10 seconds. But we can speculate, assuming that we could use Newtonian gravity equations and that no extra violent radiation was produced by the sun popping in and out of existence. Let's start with gravity... |
[
"Why is Iron the first element whose fusion does not create energy?"
] | [
false
] | It's always said Iron creation signals the death of star due to this property, what is it about iron that makes it the tipping point? | [
"At first the nuclear strong force holds the nucleons together, but adding more makes the electric repulsion from the protons more and more significant, and iron's the point where it balances out and adding nucleons takes more energy than it releases."
] | [
"This isn't wrong, exactly, but it is a very simplistic explanation. Nuclear binding is far more complicated than coulomb repulsion vs strong force attraction. "
] | [
"Can you please elaborate a bit further? "
] |
[
"Why are we not acidic?"
] | [
false
] | From my understanding, we are almost entirely made up of proteins which are chains of amino acids. If that is true, then why is our pH 7.35-7.45 rather than <7? | [
"The pH of what? We have a wide range of pHs in our body. Do you mean our skin? Our skin is actually acidic, if just mildly so. Same with hair. Blood is slightly alkaline. Stomach is obviously acidic (stomach acid). Saliva and urine changes depending on diet. Gotta be more specific if you want a good scientific ans... | [
"Take a human, stick it in a blender until all the bits blend together into a human smoothie, then measure the PH of that"
] | [
"The \"acid\" in amino acids refers to the carboxylic acid on the C-terminal side of the backbone, but doesn't actually mean the amino acid has acidic properties, it's just a naming convention. Most amino acids balance out around 7 because in water, the carboxylic acid will give up a proton while the N-terminus sna... |
[
"If no elephant was alive today and the only record we had of them was their bones, would we have been able to accurately give them something as unique as a trunk?"
] | [
false
] | Edit: To clarify, no fossils. Of course a fossil would show the trunk impression. My reason for asking this question is to understand when only bones are found of animals not alive today or during recorded history how scientists can determine what soft appendages were present. Edit 2: from a picture of an elephant skull we would have to assume they were mouth breathers or the trunk attachment holes were the nose. From that we could see (from the bone) that muscles attached around the nose and were powerful, but what leads us to believe it was 5 foot long instead of something more of a strong pig snout? Edit 3: so far we have assumed logically that an animal with tusks could not forage off the ground and would be a herbivore. However, this still does not mean it would require a trunk. It could eat off of trees and elephants can kneel to drink provided enough water so their tusks don't hit bottom. Edit 4: Please refrain from posting "good question" or any other comment not furthering discussion. If this gets too many comments it will be hard to get a panelist up top. Just upboat so it gets seen! Edit 5: We have determined that they would have to have some sort of proboscis due to the muscle attachments, however, we cannot determine the length (as of yet). It could be 2 foot to act as a straw when kneeling, or it could have been forked. Still waiting for more from the experts. I have been told that no matter if I believe it or not, scientist would come up with a trunk theory based on the large number of muscle connections around the nose opening (I still think the more muscles = stronger, not longer). | [
"I recently made a post about elephant skulls as well (after having the OP post in my thread, I thought I would contribute here):\n",
"http://farm3.staticflickr.com/2718/4378175875_61dc2b8fdd.jpg",
"That's the skull of an indian elephant. I suspect that with such a large entrance way for the bone, we could susp... | [
"I often wondered the same about a sperm whale. ",
"http://www.whalesongs.org/cetacean/sperm_whales/sperm_skeleton.gif"
] | [
"We have indeed found ",
"preserved mammoths",
"."
] |
[
"How do scientists measure extreme depth without sending in people/robots?"
] | [
false
] | Assuming that a person had access to equipment and resources, how would they measure the depth of a hole? Is there a limit to how deep people/drones/robots could travel into it safely? How would you measure how deep it was long past that point? | [
"I'd send a sound wave down and measure when the echo came back. Know the speed of sound, depth = echo time * speed of sound / 2. 2 for down and back. SoS = 340 m/s. You could probably measure the echo to somewhere around a millisecond, so accuracy on the order of a meter. ",
"https://en.m.wikipedia.org/wiki/Echo... | [
"Same method also holds for finding the depth of surfaces within the lithosphere. ",
"https://en.wikipedia.org/wiki/Reflection_seismology",
"Also ... we're ",
" sorry about autotune..., a spinoff from this technology."
] | [
"Also ... we're really, really, REALLY sorry about autotune..., a spinoff from this technology.",
"Looks like some post-doc became angry cause he never got a tenured position. So he became a super villain who created an infernal machine and throw it on the world ;) "
] |
[
"Did Newton know his theory of gravity was incomplete?"
] | [
false
] | Did Newton realize his theory of gravity was incomplete in that it did not take into account time distortion caused by gravity? If not that specific did he know something was wrong but did not know what? | [
"Yes. He knew he did not understand the mechanism behind gravity, and was uncomfortable with the fact that there was action at a distance. In his 3rd letter to Bently in 1692 he wrote.",
"\"It is inconceivable that inanimate brute matter should, without the mediation of something else which is not material, ope... | [
"precession of Mercury ",
"The Newtonian Mechanics of gravity are an excellent approximation of General Realitivity when the curvature of space time is small, but loses precision as the curvature increases. When mercury passes closest to the sun (the perihelion) this error causes the orbit of mercury to precess ... | [
"Can you elaborate on the precession of Mercury anomaly? I would think that bodies on the scale of planets would confirm Newton's laws perfectly. "
] |
[
"CN IV AND VI evolution?"
] | [
false
] | Why did abducens(cn 6) nerve evolve to control just the lateral rectus and trochlear nerve(cn 4) controls the superior oblique when occulomotor nerve(cn 3) controls all other muscles of eye movement | [
"Short answer: we don't know.",
"Longer answer: the layout of the cranial nerves only makes any kind of sense once you realize all vertebrates are just modified fish. It seems like the cranial nerves used to just be like the spinal nerves, with a dorsal and ventral branch, with the ventral branch mostly innervat... | [
"I just want to mention that simple and rationally satisfying explanations for evolutionary modifications that we observe today may not always be possible. We aren't always able to infer all the evolutionary pressures that these modifications underwent over hundreds of millions of years. Also remember that evolutio... | [
"The link is broken. But that rationale sounds weak - why would a separate nerve improve either response time or control? Is there actual evidence that the lateral rectus response faster or with greater precision than the rest of the oculomotor nerves, either in humans or other species?"
] |
[
"How does anesthesia \"tax the body\"?"
] | [
false
] | I recently had surgery and the doctor recommended spinal painkiller instead of general anesthesia due to the latter being very "taxing on the body", and that it takes a while to recover from it. Why is this the case? | [
"I am an anesthesiologist.",
"Many of the medications we use to induce or maintain general anesthesia impair your body's ability to maintain physiological homeostasis: You are unable to normally compensate for drops in blood pressure, you lose the ability to maintain your own temperature, you can't regulate the ... | [
"To add to this excellent explanation. It is mostly the surgery that taxes the body by causing the release of inflammatory signals. The anesthesia itself, if done right and in a reasonably healthy person, is not all that stressful. A spinal block helps deaden the inflammatory response to surgery significantly, whic... | [
"During general anesthesia, you are put to sleep, paralyzed, and then have a breathing tube inserted. You remain paralyzed with the machine breathing for you. ",
"During the surgery, your body can still react to the procedure. You don’t feel pain, but it knows that parts are being cut/sewn/burned etc. but it can’... |
[
"How do we know about the evolutionary history of jellyfish?"
] | [
false
] | Wouldn't their squishy bodies just disintegrate into nothing long before we could ever find them? | [
"It is important to understand that the ability to directly study the DNA of currently living creatures is beginning to have a huge impact on our understanding of evolutionary history. At one level, scientists can now test for a fairly limited number of DNA \"markers\" in a large number species in a group like jel... | [
"Source?",
"In my Fossil Records class we learned that there weren't many jellyfish fossil records compared to other organisms due to the fact that the jellyfish had no \"hard parts\". Typically these hard parts became mineralized, particularly in trilobites. Which is why we have more trilobite fossils in compa... | [
"Source?",
"In my Fossil Records class we learned that there weren't many jellyfish fossil records compared to other organisms due to the fact that the jellyfish had no \"hard parts\". Typically these hard parts became mineralized, particularly in trilobites. Which is why we have more trilobite fossils in compa... |
[
"Why do wind farms use the horizontal axis blades that have to face the wind instead of vertical ones that capture wind in all directions? (Examples in comment)"
] | [
false
] | Traditional horizontal axis Rarely used vertical axis I’m assuming it has to do with efficiency but does anyone know actual ratings? What’s the most efficient vertical turbine and how does that efficiency compare to traditional ones? Is it half as efficient? Is it better than half? When is a vertical a better option? Thanks! | [
"Axial wind turbines are significantly more efficient. That means for the same size of tower and same weight of turbine you'll get more output while producing less drag force on the tower.",
"For axial turbines the efficiency is around 35-45% while for vertical wind turbines the overall efficiency is 15-20% at be... | [
"One more thing to add on this: your original question states that vertical axis turbines capture wind from all directions. That’s not true. ",
"As other users have noted, axial turbines turn to capture wind from any direction. The problem with vertical axis turbines is that each blade gets pushed by the wind for... | [
"My guess as an engineer who deals with different kinds of turbines would be that it would be hella expensive to manufacture, install or fix compared to the marginally better performance RELATIVE to what is already in use and production. Would it perform better? Probably. A lot better? Probably not. "
] |
[
"How and why do exothermic reactions release energy?"
] | [
false
] | null | [
"The ionization potential is the energy it takes to remove (or really move to an infinite distance) an electron from an atom/molecule in vacuum. The electron affinity is the energy gained by adding an electron to an atom molecule, from having been infinitely far away.",
"does this mean in order for a reaction to ... | [
"What about during Ionic Bonding.. aren't electrons transferred from Cation to Anion? I can understand that they electron simply spends more time on the anion side but when they break up in a solution lets say.. does the electrons still go back and forward between the two ions?"
] | [
"Ionic bonding is an old and rudimentary model of chemical bonding that works for some situations, but it isn't close to what's actually happening. There is no cation or anion in an ionic bond, electrons are actually always shared when there's a chemical bond, you have a contiguous region of electron density betwee... |
[
"Why are \"x\" and \"y\" the two primary variables in most of algebra?"
] | [
false
] | On a 2d graph, the axes are always labeled either x or y, as well as many problems being "solve for x" or a basic linear equation of y=x, yet unless you substitute y for f(x), why dont people use "a" and "b" or even "y" and "z"? Who came up with "x" and "y"? | [
"If you don't get an answer here, you can also try ",
"/r/askhistorians",
", ",
"/r/math",
", ",
"/r/historyofscience",
", or ",
"/r/philosophyofscience"
] | [
"Thanks"
] | [
"Here's a video from the Today I Found Out youtube channel on the subject. ",
"https://youtu.be/cz9q2xa9Wkw"
] |
[
"What would the night sky viewed from a planet in the middle of a dense star cluster look like?"
] | [
false
] | I was reading the APOD (astronomy picture of the day) description from July 5 2013 and started wondering what it would be like to be on the night side of a planet in NGC 6752, a globular star cluster only 100 light years in diameter with over 100,000 stars. How bright would it be at night, assuming an earth-like planet orbiting a sun-like star with no moon? | [
"However, if you were in the middle of a globular cluster, the average spacing between stars is much less than 1 light year, so you would have both a drastically increased number of visible stars in the sky as well as much brighter stars. ",
"Bad Astronomy",
" calculated that the visible stars in the night sky ... | [
"The sky will be a lot more illuminated during the night and perhaps it'll be somewhat easier to see during the night. In fact, some figures put the sky to be brighter than a full moon near the center of a cluster. This has an interesting effect of illuminating everything but only casting light shadows because the ... | [
"The distance between stars in globular clusters is still immense, on the order of ",
"about one light year average between stars.",
"The closest stars to earth are ",
"roughly four times that",
" (we're not in a star cluster)",
"In short: They night sky wouldn't look that much different. Stars 1 light ye... |
[
"Why is a mylar blanket (first-aid blanket) effective against hypothermia/heat loss?"
] | [
false
] | How can something so thin and flimsy be so good at keeping heat where it is? | [
"This is exactly it! The space blanket is also waterproof, which helps keep stuff warm and dry. There's a reason why it's thin and flimsy, though! As a former Army medic, one of the biggest limitations we have in the field is space and weight. A space blanket is terrifically small and light for what it does, which ... | [
"This is exactly it! The space blanket is also waterproof, which helps keep stuff warm and dry. There's a reason why it's thin and flimsy, though! As a former Army medic, one of the biggest limitations we have in the field is space and weight. A space blanket is terrifically small and light for what it does, which ... | [
"Beside the noise and tearing issues, you usually want your blankets to let some air through to allow evaporation so you don't get all wet from your sweat and breath."
] |
[
"How do you find the Electronegativity difference between three or more elements?"
] | [
false
] | For example, what is the electronegativity difference for Acetone(CH O)? Are there two different answers? 0.4 for C & H, and 1.0 for C & O? Which one do you choose? | [
"I might not understand very well the question but if you are trying to find an electronegativity for a compound to try to assess if it would attract electrons I think there are other factors that would affect this.",
"I would say that depending on the compound. In the case of CH2O, which would be formaldehyde, y... | [
"You're trying to apply something from a binary system to a bigger system. I assume you're trying to find the dipole moment of a molecule. In a biatomic molecule, (A bonded to B) you can just say the potential difference is that of A minus that of B. Bigger molecules require a lot more math per atom.",
"If you're... | [
"This is wrong.",
"Electronegativity is ",
" the pull an atom has on the electrons in a covalent bond with another atom. So, in reality, an element does not have one standard electronegativity, and its measured electronegativity will vary based on what it is bound to. We can't talk about the electronegativity... |
[
"Does the gravity pull that causes the tides lead to a change in an objects weight? (e.g. high tide 50 kg, low tide 49.5 kg?)"
] | [
false
] | Obvious title is obvious. ninja edit: Object's | [
"Yes, though the effect is tiny. Since the force of gravity is directly proportional to mass and inversely proportional to distance squared, ",
"the effect is roughly one part in 300,000."
] | [
"(e.g. high tide 50 kg, low tide 49.5 kg?)",
"It is exact opposite. Moon also pulls you.",
"Longer version: When on same side than Moon, you (and water) are being pulled more than the rest of the Earth since it is further away from the Moon. When on opposite side, you (and water) are being pulled less than the ... | [
"Weight = Mass * Acceleration of Gravity, where weight and mass are written in the same unit (e.g. kg)- right? "
] |
[
"Are there any factors that have actually been shown to affect which sex a baby will be when born?"
] | [
false
] | I've heard of anecdotal reasons like mother's diet but have there been any serious studies on this topic? | [
"There is one common proposition that sex during ovulation is ",
" slightly more likely to result in a boy, while sex a few (2.5-3) days before ovulation, is ",
" slightly more likely to result in a girl. This is because x sperm live longer than y sperm, but swim slower. Sex during ovulation means the faster y ... | [
"There's some evidence that women in less than well-fed circumstances (so not quite starving but not far) give birth to a higher proportion of girls. This is a variant of the \"Trivers–Willard hypothesis\", but the general feeling is that daughters represent a more guaranteed chance of having grandchildren, versus ... | [
"I suppose that in the end it's most beneficial for a species overall to produce an equal number of males and females, therefore creating the highest number of mating couples.",
"Of course not all species have a single mate for life, especially humans, but starting with a 50/50 ratio is the best starting point."
... |
[
"Can Nuclear Reactors Become More Fuel Efficient?"
] | [
false
] | I'm trying to gauge whether demand for uranium will increase in a more or less linear manner with an increase of the number of reactors (and demand for energy), or whether technological advances in reactor design could result in greater fuel efficiency and therefore steady or even declining demand for uranium even as more reactors come online. So, is the amount of energy released directly linked to the amount of fuel present, or is it possible to do more with less? Thanks for any replies! | [
"Can Nuclear Reactors Become More Fuel Efficient?",
"Definitely. The question is really do we need them to be?",
"Almost all the reactors in the world are \"once-through\" Light Water Reactors ",
"(LWR)",
". Their designs are simple and they are cheap to build and run. They work by fissioning the U-235 in e... | [
"Not a fan today, I could be convinced in the future.",
"The most important difference is that EPR reactors are here now, we are building them they have advantages over Gen 3 and gen 2 reactors but they aren't future tech and so don't have some of the advantages that gen V+ have.",
"LFTR have an extremely aggre... | [
"There are also even more capable designs such as the canadian advanced CANDU reactor which can burn completely unenriched, nautral uranium. No plans to build one as of yet.",
"Just to clarify: (nonadvanced) CANDU reactors that burn natural uranium have been around for a long time."
] |
[
"Why can we still hear the cosmic microwave background? How much longer will we be able to hear it? The big bang was almost 14 billion years ago, how can we possibly see something from that long ago given that it no longer exists?"
] | [
false
] | null | [
"One thing that tends to confuse people here is picturing the Big Bang as an explosion from a point. Currently, the universe appears to be infinite in size, and so it's better to picture an infinite universe where everything has just been getting further apart from everything else in every direction. The universe s... | [
"We receive the photons forever because the universe is infinite. The photons were released over a fairly short period of time, but in an infinite universe, there are infinite ",
" for when those photons will reach us.",
"Right now we are receiving photons that have travelled about 13 billion light years over a... | [
"We don't hear it, we see it. It's photons. It's still around because the universe has a non zero temperature. The temperature has decreased as the universe has expanded and will further decrease in the future, and the thermal radiation of the universe (CMB) will shift further to longer wavelengths, which at some p... |
[
"What do wild animals die from mostly?"
] | [
false
] | [deleted] | [
"That's how I want my obituary to read: \"died from inadequate fitness to circumvent the circumstances of his death\" "
] | [
"Your question needs to be scoped. ",
"What do you mean by \"animal\"? Chordate? Animalia? Metazoa? Eukaryotes?",
"What do you mean by \"mostly\"? Are you asking about the circumstances under which the largest number of individuals cease life-sustaining function? Are you asking about the circumstances that arre... | [
"I don't think it is necessary to be so pedantic. It is reasonable to assume that a layperson is referring to animalia, and the scope of answers they are expecting is something like: disease, killed by other animals, starvation, environment. ",
"We can roughly divide environments, so that may a good place to star... |
[
"Are epigenetic changes passed on mostly through the matrilineal line?"
] | [
false
] | [deleted] | [
"This is in reference to maternal imprinting, which is one of the sole examples of a truly epigenetic trait passed across generations. In imprinted genes, DNA accumulates methyl marks that can regulate the locus. Histone marks are really not epigenetic in the trans generational sense as the marks are removed during... | [
"Mostly, but there is alot we don't know it seems that epigenetic information carried by parental sperm chromosomes can cause changes in gene expression and development in the offspring. ",
"https://www.nature.com/articles/s41467-019-09141-w",
" . Also Mitochondrial DNA is epigenetic."
] | [
"My guess was that it was because the mother carries the foetus for nine months so, and I know Reddit doesn’t like a Wikipedia reference, but i looked on there and found this on the ",
"Transgenerational epigenetic inheritance",
" page:",
"During fertilization the male and female gametes join in different cel... |
[
"What else do electrons interact with besides protons?"
] | [
false
] | I know that electrons are attracted to protons, and together they form matter. But, from my understanding, matter makes up a very teeny tiny percentage of space. I'm curious to know if electrons have a wide variety of interactions with other things, and we only know about matter because that's the only interaction that actually produces large clumps of stuff. In other words, do electrons exhibit this really great range of behaviors, and the fact that it also takes part in making matter is just a small part in all of that? | [
"Well technically, the electrons don't interact with the protons directly. Electrons interact with ",
" (electromagnetism) that then interact with protons. Electrons also interact with W",
" and Z",
" bosons in particle decays. While it seems like a bit of pedantry, it's really the key to your question. Becau... | [
"Dunno how I missed that. Sorry."
] | [
"They also interact gravitationally, a fact particle physicists often forget."
] |
[
"What would happen to an electron and proton in a vacuum?"
] | [
false
] | I know that they would accelerate towards each other due to the electromagnetic force. But, what happens once they become very close, to the point where they reach their highest velocity? Would they collide, with the kinetic energy accumulated in the acceleration being used to form a chemical bond (making a hydrogen atom)? If they would stick together and make a hydrogen atom, how does that entire process not lead to an increased entropy of the universe? | [
"The entropy has increased, because they have emitted photons."
] | [
"You get hydrogen."
] | [
"Right, but then the entropy of the system has decreased. What would account for the overall increase in entropy of the universe should this process occur?"
] |
[
"I'm ex-military, and today when playing a new first person shooter, I swear you, I smelled gunpowder. What causes that, and how does it work?"
] | [
false
] | null | [
"Mostly priming, which is how we humans relate on thing to another. This is the reason why for instance if I say \"red\" you might think of blood or a firetruck and so on. Because you're so used to smelling gunpowder after a fired shot your brain expects it to happen again so much that you actually believe you can.... | [
"Isn't this a textbook case of Classical conditioning? Operant conditioning is about an individual's behavior, whereas this seems to be a case of OP connecting two stimuli: combat, or gunfire or whatever being associated with the smell of gunpowder"
] | [
"This is a reminder that anecdotes (i.e., \"me too!\" answers) will be removed. Please keep answers scientific and well-sourced if possible."
] |
[
"What are any current \"embarrassments\" in Science?"
] | [
false
] | I was watching this Lawrence Krauss lecture ( , great lecture by the way), and he mentions that at one time in our history we knew the Earth was at least 4 billion years old, but the universe was estimated to be younger. So, this was embarrassing that the Earth was older than the universe. My question is: what current big contradictions, if any, exist in Science? I know there are several "theories of everything" which contradict, but no one is claiming that we can really estimate which is true or false (otherwise there wouldn't be competing theories for the same thing). An example would be if rock dating techniques disagree on something nontrivially, different ways to measure the mass of a proton disagree wildly, etc. Thanks! | [
"The predicted vacuum energy density from quantum field theory is 107 orders of magnitude greater than the observed value. This is the most embarrassing prediction in the history of science."
] | [
"We don't know how supernovae actually explode... computer simulations can't make them explode for whatever reason.",
"Despite many many years of studying the problem, we still don't have a really good grasp of star formation."
] | [
"I work in star formation, and the problem with the small-scale modelling seems to be that ",
" has any idea what to do about the magnetic fields. ",
"Most conferences I've been to about this always have the magnetic fields folks saying \"seriously, you need to include these\", then the rest of the time is spen... |
[
"What do we mean when we say something \"died of old age\"?"
] | [
false
] | [deleted] | [
"Dying of old age is certainly not a medical term. It means that the person or animal died of natural causes that are related to the natural aging of that species. usually related to some kind of cardiac or organ failure. Everybody dies of something, however, usually if the person is at, or past their normal life e... | [
"Cells in our body are constantly carrying out various functions. These functions are energy intensive, create waste and in general are quite tough on our various organs. On top of this, we are constantly getting external damage from the environment: UV light, toxic material, bacteria and other microorganisms. ",
... | [
"How does age make our organ's fail?"
] |
[
"Are there any documented cases of evolution where there has been speciation?"
] | [
false
] | I have a religious but otherwise very reasonable friend and I have finally piqued her curiosity with evolution, specially since she is studying medicine and we have been discussing the pharyngula stage, vestigial features, etc. The thing is she says she accepts microevolution, but she does not believe two species can come from the same ancestor (it's the old "it's not evolution, it's adaptation"). I looked around but couldn't find any. Any ideas? Thanks! Edit: Thank you very much for your responses! I will read these myself and share it with some other friends, as well. AskScience Rocks! | [
"Well, I was going to post a giant list, but it was over the word limit... so start here:",
"http://www.scienceforums.net/topic/13511-observed-speciation/"
] | [
"Ring species",
" are great examples of speciation in progress ",
".",
"Wikipedia: Speciation",
" also gives examples of observed speciation."
] | [
"This is one of the more famous ones ",
"(Lenski)"
] |
[
"What color are the eyes of an albino person?"
] | [
false
] | The iris, pupil and sclera, please. I'm doing a and the internet confuses me as to what color I should do the eyes. | [
"Usually it is pale blue, though this may vary as a function of the type of albinism. ",
"The Wikipedia article on albinism",
" has some more info."
] | [
"Here's an example image",
".",
"The sclera should still be white.",
"The iris of an albino person has an extremely low melanin content. In normal lighting conditions, this results in a pale blue or gray color. However, if the light is bright enough, such as in bright sunlight or a flash photo, you get the ... | [
"Yes I've gathered that I just needed to know a more specific description that focuses on the eyes only. Though someone helped me out I appreciate the fact you took the time to answer! Thanks :)"
] |
[
"How does gum disease have any bearing on the heart?"
] | [
false
] | Why am I increasingly seeing articles saying that if I don't keep my gums healthy, I might be susceptible to heart diseases? | [
"To sum up the last few decades of research, what was found was a certain group of ",
" called ",
" could be cultured from the valves and myocardium of patients with endocarditis, which is an infection of the interior surface and valves of the heart. Interestingly enough, these were identical to some of the ",
... | [
"It is also theorised that long term inflammation can worsen atherosclerosis and promote blood clotting which can contribute to the more common types of heart and vascular disease. "
] | [
"Infection in one's gums can enter the blood stream and travel to their heart infecting the heart valves."
] |
[
"What do muscle knots actually look like?"
] | [
false
] | I have always wondered what the muscle actually looks like when you have a "knot". I'm aware they are contractions in muscles, but it's not the whole muscle contracting (right?), so what does it really look like? | [
"http://www.t-nation.com/img/photos/06-150-training/image009.png",
"This is similar to a picture out of a physiology book that I had in massage school. "
] | [
"Here's a larger image in colour: ",
"link"
] | [
"yes the term \"toxin\" is terrible, but in an area of muscle that is in constant contraction (or stuck closed {see full response below}) there is reduced blood flow. thereby the chemical bath at the site is stagnant. ",
"prostaglandins and histamines (and the rest of the compounds the regulate emigration of neut... |
[
"Would it be possible to create a synthetic agent to replace our Myelin Sheaths?"
] | [
false
] | I've been wondering about this for a while. Since it appears that our Myelin Sheaths are the source of numerous complications yet crucial to our survival, would it be possible to create a synthetic agent that performs the essential functions we require while avoiding generally negative effects? I'm quite sure that the answer to this isn't an encouraging one, but if such an undertaking was possible, we could circumvent a lot of the factors that prevent Neurogenesis of the CNS, and certain Diseases - such as MS, Myelitis, or Polyneuropathy - could be confronted in a new way. | [
"Purely synthetic? Most likely not as the scale and \"installation\" process would be major hurdles. Bio-synthetic? Maybe. The myelination process involves two types of glial cells. One of them takes care of the peripheral system, the other the central system. Producing, maintaining, and adapting myelin is an ... | [
"This is only complicated by the fact that myelin sheaths are not continuous along the length of the axon - it's actually a bunch of sheaths separated by small gaps. These gaps are necessary to keep the action potential traveling down the neuron.",
"Because of this, a completely synthetic myelin analogue would re... | [
"Whilst studying glioblastoma multiforme in my last job, I seem to recall reading that the myelin sheaths do more than just insulate the neurons - they also provide other support functions for the otherwise encased nerves. ",
"That's been a while though"
] |
[
"How strong would a vacuum's suction need to be to start pulling hair off of a Person?"
] | [
false
] | [deleted] | [
"One thing that you must understand is that there is no actual \"suction\" from a vacuum. What you are experience is the PUSH of the air trying to get into where the vacuum is. So even if your whole body was in a vacuum, you wouldn't pull the hair off anything."
] | [
"Somehow I find this relevant:",
"http://www.youtube.com/watch?v=ORalNaAokYA",
"But seriously, I'd imagine it'd have to be something at least industrial strength."
] | [
"Vacuum is a vacuum. There is nothing in a vacuum so you can't make it a stronger vacuum by making it have less stuff, because there is nothing to take away. Because there is nothing at all in a vacuum, then there isn't anything in there that would be doing the sucking either. It's the non-vacuum that does the push... |
[
"How old can a tree get in a perfect environment?"
] | [
false
] | If there are thousand year old trees in non- perfect conditions how old can a tree get if it gets everything it needs to live, | [
"Tree age is limited more by the stability of their telomeres. As plants age, the telomeric caps that stabilize the ends of their DNA will inevitably degrade, causing DNA damage.",
"Another factor with negative effects on plants aging indefinitely is DNA damage itself. A classic cause of this is UV damage from th... | [
"Assuming you mean they keep growing:\nTheoretically you would reach a point when the tree needs so much water (more so than evapotranspiration can provide) that the tree would stop growing and then stabilise staying at that point indefinitely.\nAssuming you mean that it grows to a certain point and then stops, it ... | [
"One of the things that makes plants so special is the fact they can be polyploidy (they have more than the two sets of alleles), which is usually fatal/causes serious mental difficulties in humans. Another is the fact that when they grow they grow a stable structure (has you tried flexing a thick tree branch) as o... |
[
"Is a sperm getting to the egg first actually a result of it carrying better genes than slower sperm?"
] | [
false
] | From a layman point of view, the quality of the genetic material being carried seems as though it would have little effect on the sperms ability to move. Exactly how much if at all does the cargo affect the vessel? | [
"One of the big things is that it's not only speed, but luck as well. The fastest sperm may go the wrong direction, may not be able to penetrate the egg before another sperm does, or just plain old not survive the trip. Speed may help the sperm, but it isn't the deciding factor."
] | [
"Thanks for this very scientific answer."
] | [
"Thanks for this very scientific answer."
] |
[
"How physically damaging(if at all) is our increasing dependance on wireless technologies?"
] | [
false
] | null | [
"In terms of the internet, specifically things like google, our brains are actually evolving in such a way as to crave \"instant gratification\" (finding the answer to your question via google instantly), and we are less capable of spending time reading through large articles. This also affects our writing abilitie... | [
"There are two kinds of radiation. Non-ionizing and ionizing radiation. Ionizing radiation is dangerous, because it has the ability to destroy molecules(e.g. DNA) in your body. This is what causes cancer in people who has been exposed to radioactivity(nukes, power plant failures or medical device failures, and so o... | [
"First thing, \"radiation\" is essential to our lives; the most common form we think and talk about is light. Light and wireless signals are the exact same physical phenomenon, except that each has different wavelengths. ",
"However, that's not to say that some forms of electromagnetic radiation might not be harm... |
[
"Why does the hair on our body seem to stop at a certain length while the hair on our heads grow continuously?"
] | [
false
] | null | [
"All hair grows for a certain amount of time, stops for a period, then falls out. The cycle repeats. Changing the amount of grow and dormant times gives you the difference between scalp hair and arm hair. This basically gives all hair a maximum length and the hair that remains a constant length has a short enoug... | [
"Head hair has a max length as well. Some people just can't grow hair past their shoulders. Some can grow it three yards long. Even though there's a big range it does taper off eventually. "
] | [
"This is true, but this also raises the question, why does the hair on different parts of our body fall out at different times? And regardless of race or gender, why it that only the hairs on our head get the longest growth period before falling out?"
] |
[
"Does blowing on your food actually make it cool down quicker?"
] | [
false
] | null | [
"You're moving the heat away from the food faster than it would normally would, so yes."
] | [
"The air you exhale is still colder than the food, and you're also pushing the colder air from the environment over it as well. Food cools down by transferring its heat to the air around it. The greater the difference between the temperature of the air and the temperature of the food, the faster this heat is tran... | [
"Great answer! Thank you! "
] |
[
"What do the scientists/physicists expect to find when they ramp up the energy of the LHC to 13 TeV?"
] | [
false
] | I assume it is new particles that are not part of our current Standard Model? | [
"A very interesting question, bmp91. ",
"There are several topics that scientists are trying to clear up by means of the LHC. \nI'll list a couple.",
"By increasing the energy of the accelerator, scientists are hoping to come close (though how close that's up to some debate) to the amount of energy that was aro... | [
"There are absolutely no indications that SUSY particles should exist. It is just aesthetically pleasing to some.",
"The chance of the LHC producing any mini-black-holes is basically zero. There is no indication that general relativity should break down at the ~10 TeV scale. Much MUCH more energetic particles hit... | [
"The presence of a supersymmetric model would solve theoretical issues regarding the value of the Higgs boson's mass, it makes the problem of quantum field theory easier to analyse and is necessary for the string theory (which of course it's not proven itself)."
] |
[
"Steel rod to mars vs the speed of light?"
] | [
false
] | Hi, I remember reading this passage in the "Feynman Lectures", where Dr. Feynman describes an experiment in which a theoretical metal rod of length equal to the distance between mars and earth is arranged between mars and earth. Then the "rod handler" on earth gives the rod a push upwards. So the question posed is, will the rod instantaneously move backwards on Mars? He then proceeds to say that actually the movement will be felt roughly after the time it would take for sound to propagate from earth to mars i.e. at the speed of sound. This is because the atoms in the rod actually propagate their position at the speed of sound. My question is, if this were true, how is supersonic travel possible? won't there be a scenario where the atoms in the components of the aircraft won't "catch up" because the propagation of the new positions is slower than the actual speed? Won't the aircraft disintegrate? | [
"The super-sonic aircraft is an example of (nearly) ",
"rigid-body motion",
". Note that this page says:",
"Even though such an [prefectly rigid] object cannot physically exist due to relativity, objects can normally be assumed to be perfectly rigid if they are not moving near the speed of light.",
"Which m... | [
"My question is, if this were true, how is supersonic travel possible? won't there be a scenario where the atoms in the components of the aircraft won't \"catch up\" because the propagation of the new positions is slower than the actual speed? Won't the aircraft disintegrate?",
"You're mixing up reference frames ... | [
"5100/62 = 822.6 ms. ",
"Your computation is completely off.",
"62m / 5100ms",
" = 0.012 s "
] |
[
"Do deaf people with dyslexia have a hard time understanding sign language?"
] | [
false
] | Sign language involves interpreting language using visual interpretation, so would dyslexia make that difficult? Or does sign language go through a different path in the brain? PS not sure which flair is most suitable - sorry if it's a bad choice! | [
"Sign language makes sense if you reverse the image like a mirror. ",
"",
"I'm not too familiar with neurolinguistics, but I believe signed language is processed through the same area as spoken language (Broca's area). I'm not sure where dyslexia occurs in the brain."
] | [
"Aren't there some signs that are identical except for which hand is used?"
] | [
"No, at least not in ASL or a few other sign languages I know. Right-handed people sign opposite of left-handed people, so the signs are not easily confused. The only time this changes is when the signer is indicating something on their left or right, this would be the same for every person signing in that directi... |
[
"Before modern dental hygiene, did everyone have terrible breath all the time, or do our mouths stay pretty clean when not eating so many refined carbs?"
] | [
false
] | null | [
"Dental Hygienist here: Refined sugar has more to do with caries (cavities) than bad breath. Interestingly enough, caries used to be a disease of the wealthy because they were the only ones who could afford refined sugars, but now it is seen more in the poor because of poor education and it is cheap.",
"\nPeopl... | [
"Cultural anthropologist here:\nPeople have been using things to clean their teeth for much of human history. Two things that were prevalent all over the world were cloth and sticks. Tooth cloths and tooth powder have been used in Europe for hundreds of years (possibly longer, but cloth rots and doesn't turn up i... | [
"The interesting thing to consider, in this case, is whether the OP means bad breath or bad teeth. The two are certainly linked, but not until the advanced stages of gingivitis or ANUG.",
"If we're talking bad breath, then onions and Garlic were peasant foods. Meats (for peasants) were a delicacy and eaten very r... |
[
"Did cocoa trees, coffee plants, and tea plants all evolve the production of caffeine independently, or do they share a common ancestor that made caffeine?"
] | [
false
] | Also, are there many other plants that produce caffeine that may not be edible or that are less common? | [
"They evolved caffeine production independently. This is an example of convergent evolution, whereby different species develop similar characteristics independently. The caffeine sources even vary--seeds, leaves, etc. The chemical structure of caffeine isn't the most complex.",
"http://sierram.web.unc.edu/files/2... | [
"As elsjaako pointed out above, both ",
" and ",
" share a common ancestor in a monophyletic group. It would seem more likely that their ability to produce caffeine enzymatically is an example of parallel evolution, not convergent. It is likely their common ancestor produced xanthosine or xanthine (purine deriv... | [
"This is likely the most correct answer. To corroborate your point I ran a sequence alignment on the caffeine synthase of black tea (Camellia sinensis) and coffee (Coffea arabica). The proteins are clearly homologs, with a 37% identity match along amino acid sequence (55% similarity when using BLOSUM62 and default ... |
[
"Why is there a positive correlation between population density and the murder rate?"
] | [
false
] | I posed this question before in AskSocialScience. Curious to see what sort of answers I'll get here. | [
"Other factors play into this: Per Capita income, racial percentages, gun laws, guns per capita, and other variables that need to be controlled in a model for this. ",
"Personalities clash, resources become scarce, relationships are complex. People, like most animals respective to their species, are not happy pen... | [
"It seems obvious to me: the greater the population density, the more people you interact with over time. Each such interaction has a non-zero ",
" of leading to you becoming the victim or perpetrator of murder. Too-frequent interactions may increase that chance, as each interaction is a potential source of stres... | [
"This is a good question! To work out the answer though, first we need to understand why people murder in the first place. Different countries will have different statistics (which indicates how closely tied these questions are with cultural practices), but in a western country, many murders are committed as a resu... |
[
"Is there any matter inside a black hole?"
] | [
false
] | I know that as things head into a black hole, spaghettification occurs. I know these tidal forces are enough to tear the bonds between atoms. And, to the best of my knowledge, since the gravity is practically infinite, I assume it is enough to tear apart the bonds within the atoms as well leaving only the fundamental particles. So, assuming I haven't made a mistake yet, would these fundamental particles be 'torn' apart as well? I'm not sure how they would be torn apart... maybe converted into pure energy? What would this 'energy' manifest as? : Thought of a follow up. I've read that black holes preserve information. If my presumption is true, how would the information survive and be reconstituted in any plausible sense? | [
"how would the information survive",
"When particles fall into a black hole they cause deformations/oscillations of the event horizon surface. So the information about them is not lost in a sense that it will be able to affect outgoing particles (Hawking radiation), for example. "
] | [
"It depends how you define \"matter\". If by \"matter\" you mean anything that has rest mass, then the answer is yes: but you wouldn't say that the black hole ",
" matter, rather that it ",
" a type of matter.",
"A more restrictive definition would be to insist that matter has to be something made of fermions... | [
"Black holes are superdense collections of matter."
] |
[
"What will happen here on earth when Betelgeuse goes supernova?"
] | [
false
] | null | [
"It'll be about the same relative size as the moon",
"I don't know what you mean by this. The brightness would be the same. You can determine the brightness from the distance modulus. I couldn't grab the absolute magnitude of a Type-II, but for a Type-Ia it is about -19. At a distance of 200pc, this would be a... | [
"Its too far away to have much of an effect on Earth. We will be able to see it clearly night or day as it is already an extremely luminescent star. Damage wise gamma rays will be sent out but because of its axis, we won't get hit by the intense gamma ray burst."
] | [
"My thoughts exactly."
] |
[
"Why are the blades on hole punches a concave shape?"
] | [
false
] | null | [
"A blunt tip doesn't punch effectively, especially for multiple sheets. A convex tip punches ragged holes and doesn't remove the material, just pushes it aside. A concave point reliably cuts the material away neatly, and also provides a thinner \"edge,\" making it easier to punch multiple pages at once."
] | [
"a sharp object can hurt you and a blunt object can't",
"Are you volunteering to test the latter hypothesis? I can help you."
] | [
"The same reason for why a sharp object can hurt you and a blunt object can't. The pointy part of the concave blades will provide the power to puncture the thick layer of paper. Cutting the rest of the paper is easy work after that. "
] |
[
"Where do atoms get their energy from? Or more specifically, why do they seem to have an infinite amount of energy?"
] | [
false
] | So I've understood since I was young that atoms are always moving, and the speed at which they move determines their state (solid, liquid, gas). What I never even thought to ask was how the atoms kept moving! So if you have a solid object, let's say a bouncy ball, and the ball is comprised of constantly moving or vibrating atoms, where does this energy come from? And why doesn't an atom's energy ever run out? If you throw a bouncy ball, every time it bounces it transfers some of its energy to the surface it comes in contact with, eventually losing the required amount of energy to continue bouncing. So why do atoms bounce around at a constant and infinite pace? | [
"Well, the reason a bouncy ball stops moving after some time is, that is loses energy to its surroundings; mostly in the form of heat.",
"On a microscopic scale, however, heat ",
" the movement of atoms. Thus Atoms cannot lose energy to their surroundings, except by transferring it to other atoms (or emitting i... | [
"No, tiny balls which are bouncing around randomly are already at their most disorganized state, so you can't \"disorder\" them any further. You can only increase or decrease their average velocity (heat it up or cool it down).",
"Entropy increases when you decrease or remove differences in energy. To stay with t... | [
"Exactly. One important distinction between heat and macroscopic movement though is that heat is random motion whereas macroscopic movement is ordered (everything is moving together). Because many more disordered states exist when compared to ordered states, you can expect that over time ordered motion (like a bo... |
[
"Do People who fast regularly have lower risk of diabetes ?"
] | [
false
] | People who fast regularly like religious people have a lower risk of being diabetic, is that true? Being at a high risk of diabetes I'm trying to avoid as much risks as I can and i dont mind fasting but my mom wanted to know more about it so can someone please let me know.. Thank you | [
"Yes, it lowers the risk of type II Diabetes. ",
"Type II diabetes is caused by ",
"insulin resistance",
". Insulin is a hormone that makes cells take in sugar from the blood. Insulin resistance means that the same amount of insulin will now lead to a reduced uptake of sugar from the blood. At first this is n... | [
"Does genetic predisposition towards developing type II diabetes confer any survival advantage in parts of the world where starvation is rife? I notice there appears to be a strong correlation between the prevalence of type II diabetes and such countries.",
"If starvation strikes, are you more or less likely to s... | [
"There have bin several theorys why people become Typ2 diabetic form: to much calories, to cells are overfiled by constant glucose exposure, to desensitisation of the insulin receptors by constant insulin exposure.",
"in theory people that fast will have lower caloric intake, burn the glucose in the cells and red... |
[
"Is the moon really going to escape our view/orbit after a long enough period of time?"
] | [
false
] | If so, what are going to be the effects on earth's tide? or other impacts? | [
"Correct. As with many things, the real universe comes along and ruins the theoretical scenario."
] | [
"Yes. Tides will diminish. It's possible that the core will cool and the that will cause the magnetosphere to shut down and stop protecting the earth from the solar winds. Also the moon stabilizes the earth's axis. With the moon gone, seasons would become less predictable and more extreme."
] | [
"It's important to note three things here.",
"1.) The moon won't escape its orbit completely. The moon is gaining the energy required to move into higher orbits through tidal forces which slow the Earth's rotation. Thus, once Earth is tidally locked to the Moon, the Moon will stop receding from Earth.",
"2.) Th... |
[
"Are OD 6+ goggles strong enough to safely build/play with \"DYI blu-ray laser pointers\"?"
] | [
false
] | null | [
"Wolfram alpha is doing that calculation with the base e logarithm, not base 10.",
"Here is the corrected version.",
"Though are you sure that you can get 2 Watts from a 405 nm diode? When I was into lasers, the most that I heard people doing was 500 to 600 mW. Have people found sources of more powerful diodes?... | [
"Optical density of 6 means that the intensity is reduced by a factor of 10",
" This is overkill unless you plan on working with lasers with hundreds or thousands of Watts of power.",
"The optical density that you want depends on the power output of the laser. Usually, you want the goggles to reduce the power t... | [
"So I did that and assuming 2W, I got 5.9999 (6+ OD). Did I get something wrong?",
"http://www.wolframalpha.com/input/?i=-log%28.005%2F2%29"
] |
[
"How is feline leukemia contagious but human leukemia isnt?"
] | [
false
] | null | [
"It sounds like you're thinking of feline leukemia virus, which is a virus that causes leukemia. As a general rule, cancers including leukemias are not contagious, but if they are caused by a contagious virus, cases of cancer will spread. This is analogous to HPV in humans, which is sexually transmitted and causes ... | [
"Humans have a version called human T-cell leukemia/lymphoma virus (HTLV) that causes T-cell leukemia and other conditions."
] | [
"Feline leukemia is caused by a virus so it can be spread like any other virus leukemia in humans is not caused by a virus. The exact cause in humans is not known but is related to genetics and not a virus so It can not be spread."
] |
[
"What is the difference between anti matter and negative matter?"
] | [
false
] | null | [
"If by \"negative matter\" you mean \"stuff with negative mass\", we're not sure if such a thing can even exist. Antimatter has positive mass."
] | [
"Could black holes be made made of negative mass?"
] | [
"Black holes, as we know them, have positive mass."
] |
[
"For how long can you survive hanging upside down?"
] | [
false
] | null | [
"I can't see any way of getting a definitive length of time, unless you actually hung someone upside down and waited for them to die. ",
"Human beings aren't meant to go about their lives upside down, and I believe that eventually, doing so would prove fatal- the heart would be overworked from trying to pump bloo... | [
"I believe that eventually, doing so would prove fatal- the heart would be overworked from trying to pump blood up the length of the torso and legs, ",
"I doubt it. The heart already has to pump that blood up the length of the torso and legs, after all, because the blood has to get from your toes up to your head... | [
"Doesn't the human heart work differently in terms of capacity for blood in than it does for blood out? It might be optimised for bringing deoxygenated blood up from your feet rather than sending oxygenated blood down.",
"Blood goes in, blood goes out never a miscommunication."
] |
[
"Are there any animals that have symbiotic parasites and evolved under the expectation of the parasite's presence?"
] | [
false
] | For a hypothetical example, if an animal that used to have a type of skin but a parasite replaces it with better skin so the animal stops growing the skin over generations. Probably not skin specifically but anything in general! | [
"Yeah, pretty much all multiple Cellular organizms. It is hypothesized that the mitochondria, during ancient Cellular development, was a bacteria that was engulfed by a cell. The bacteria adapted to its new environment and began being useful to its host. As a result the cell began feeding the bacteria and eventu... | [
"Mitochondria",
" could be an example. It has been proposed that they were once an energy-stealing parasite that now is a critical part of cellular function. The exact details of the original role of mitochondria isn't certain, though, so it may have been simply symbiosis rather than parasitism. This all happened... | [
"Humans are symbiotic with our gut bacteria, but it's a mutualistic symbiosis rather than a parasitic one, as both host and bacteria benefit. Humans get enhanced nutrient extraction, immunity, and ",
"MANY other effects",
", while the bacteria get food and shelter in our intestines. Normally mutualistic gut bac... |
[
"At what point in human evolution did we develop a dominant hand? Is this a trait found in other primates as well?"
] | [
false
] | null | [
"Scientists (myself included) are still trying to figure this out. The current evidence suggests Neanderthals exhibited handedness and it appears to be roughly the same ratio as most modern humans: ~ 90% right handed. However, hand preference, that is consistently using one hand or the other for a particular behavi... | [
"Most hypotheses associate handedness with either the 1) evolution of bipedalism or 2) increased task complexity (e.g. tool use). Some also elicit language as a selective pressure. There is decent evidence for the first two hypotheses so it’s hard to tell which is better supported. ",
"I should note that there is... | [
"is there any indication as to why we did? i would think that being ambidexterous would give a greater advantage both in hunting and in daily tasks."
] |
[
"Why does depression cause brain atrophy in certain regions?"
] | [
false
] | Is it reversible? | [
"Why? Lots of reasons. Is it reversible? Partly.",
"The evidence comes mostly from rodent chronic stress models and clinical postmortem studies of depressed subjects, where neuronal atrophy is most notable in the prefrontal cortex (PFC, executive functions and cognition) and the hippocampus (memory, especially sp... | [
"So drugs like SSRIs can potentially reverse the brain degeneration induced by depression, right?",
"Can the cognitive decline be naturally reversed as well if the patient gets better by other means (e.g. psychotherapy) with the passage of time? Or is this effect exclussively caused by pharmaceutical treatments?... | [
"They can, and this is proposed as an important part of their long term benefit, but their direct role in increasing monoamine action (serotonin, epinephrine, dopamine) is also obviously crucial.",
"I don't know if psychotherapy/CBT have been proven to reverse it, but they are, in my view, extremely important in ... |
[
"What food doesn’t come indirectly or directly from soil?"
] | [
false
] | The FAO has a statistic that 95% of our food is either indirectly or directly from soil. My lab mate and I are scratching our heads trying to think of foods that don’t come from soil and we thought y’all might have better ideas than us. | [
"Anything harvested from the oceans would fall into the 'not directly or indirectly from soil' category."
] | [
"The major biomass production in the oceans is pelagic and entirely independent of the ocean floor."
] | [
"Surprisingly, it isn't, I would have thought the same. I suppose that even societies deriving a majority of their protein from seafood still derive the majority of their overall caloric intake from grains.",
"https://www.who.int/nutrition/topics/3_foodconsumption/en/index5.html"
] |
[
"How worried should I be by recent articles about arctic methane?"
] | [
false
] | So I've read this recently: I was aware of arctic methane as an issue before now but this article seems to suggest that it's a lot worse than it was expected to be. I'm generally very skeptical about science reporting which declares how astonished researchers are as they tend to be bunk, but I don't have any expertise that would let me judge it in this area. So, how bad is it really, and should we be any more worried now than we were (say) six months ago? Edit for clarity: I'm aware of why arctic methane release is a bad thing. My question is whether the claim that it is currently being released in unexpectedly high volumes is accurate | [
"Sorry, but I have to nit pick you . . .",
"Global Warming (aka Climate Change - the more politcally correct term)",
"Yeah, no . . . global warming is the observed phenomenon that the global mean temperature has been increasing over a long period of time. Global climate change is what results from the change of... | [
"climate change was inevitable",
"Well, yes and no. To some extent, the climate is always changing. The sun is getting incrementally brighter, our orbit changes its eccentricity, obliquity, and precession so gradually that over human lifespans it's unnoticeable, etc. ",
"But the current climate change (i.e. mut... | [
"It depends if you believe in global warming or not.",
"In my opinion, Global Warming (aka Climate Change - the more politcally correct term) is a very very very real situation. It probably can be concluded that the methane was released due to the permafrost melting. Immediate concern can be raised considering th... |
[
"How does frame of reference in physics being arbitrary reconcile with kinetic energy being proportional to square of velocity?"
] | [
false
] | I'm having a difficult time reconciling my understanding of kinetic energy being the square of the velocity with my understanding of frames of reference being arbitrary. So given some frame of reference, say a spacestation traveling through a starless void at a speed signficantly less than the speed of light, a spaceship with mass of 1 Kg (guess it's a small ship) traveling at exactly the same speed (0) has 0 J energy of kinetic energy. If that ship speeds up to 1 m/s, it should now have 0.5 J of kinetic energy. Presumably this means that it fired its thruster for some length of time. Now if the spaceship doubles its speed, it's now going 2 m/s but its kinetic energy will have increased to 2 J. Did it need to 'expend' 3 times at much energy from it's thrusters to get to this speed? Now I run into the problem that I thought frame of reference is arbirary. What if we instead start with the moving 1 m/s frame of reference? Does it take less fuel for the spaceship to change speeds if we change our frame of reference? What am I missing here? | [
"Those are great questions, because they show that you're engaging with the concepts and trying to apply them in different scenarios to work out the consequences. Very good.",
"There's a couple of things to work through here. The first I want to to point out is that while energy is famously ",
", it is not ",
... | [
"Thanks! This whole answer really helped reconcile these concepts for me. I love this way of thinking about it.",
"What changes, depending on how you chose your frame, is how that kinetic energy is distributed between the [ship and exhaust]."
] | [
"This increased efficiency of conversion to kinetic energy is called the “Oberth Effect.”"
] |
[
"Why can't we produce milk or honey synthetically? What's so special about cows and bees?"
] | [
false
] | null | [
"I'll answer this for honey, though the answer for milk is probably pretty similar. What is boils down to is that ",
"honey",
" is a complex mixture of ",
"carbohydrates, proteins",
", ",
"acids",
", and ",
"organic volatiles",
". ",
"We don't know every molecule in honey, and we don't know exactl... | [
"For solidarity (and to piggy back this comment). Milk is an incredible complex mixture. Just milk fat alone contains approximately 400 different fatty acid species, which makes it the most complex of all natural fats ",
"Source",
". "
] | [
"Honey was ",
"? Yuck! "
] |
[
"How do icebreaker ships work?"
] | [
false
] | null | [
"Modern ones are designed to 'ride up' onto the ice and then break it with their immense weight. Specially shaped bows (and sterns, for some that can go backwards), of course."
] | [
"They break the ice with their weight. The bow is shaped like a spoon and allows the ship to slide on top of the ice and the weight of the ship pushes and crushes the ice downwards. Some ice breakers have big water tanks that allow swinging on the top of the ice, helping to break the ice below. Air can also... | [
"So you're saying they...cut through the ice?"
] |
[
"Can anyone help with questions about brain tumors?"
] | [
false
] | I am currently writing a story in which the protagonist has a benign brain tumor. From what I've read online, they are generally easy to deal with, but can be dangerous if they are in certain parts of the brain. I haven't been able to find out which locations are more dangerous than others in regards to this type of tumor. Additionally, in the interest of plot development, I wonder if there is a specific location where a tumor (or the removal of a tumor from this location) could cause mental instability, enough so to have the person committed to a mental institution. I don't want to make the character an invalid, so I'm not sure if this is an option or not. Any information or help with this situation would be greatly appreciated. | [
"A \"benign\" brain tumor will have varying effects upon a person depending on what area of the brain it's in. Much of our understanding about which parts of the brain control specific functions is due to case studies where individuals have had damage to those areas of the brain. For example, quite a few people hav... | [
"Brain tumours aren't easy to deal with generally; it does depend on location and type. For example, glioblastoma if left untreated can kill within around 4 months. As for location, a tumour of the brainstem (brainstem glioma), or a tumour of the cerebellum (medulloblastoma); both of these tumours are highly malign... | [
"Interestingly, I found two separate case reports of psychiatric illness seemingly arising as a result of a right intraventricular meningioma:",
"http://www.ncbi.nlm.nih.gov/pubmed/10085187",
"http://www.med.ucla.edu/modules/wfsection/article.php?articleid=120",
"These two seemed not to be invalids, even afte... |
[
"Looking at the position of the Sun provides a useful measurement of time during the day. Can I do the same by looking at the moon at night?"
] | [
false
] | There was full moon yesterday and it occurred to me that I should ask this question on before I fell asleep again. Is there a way to deduce an approximate time (like "it's around 23:00 o'clock in the evening") by looking at the position of the moon during nighttime? I'm not afraid of using additional information, like the date or a few memorized numbers. | [
"There are methods based both off of the moon and off of the stars.",
"The moon method is based off the fact that the part of the moon that is illuminated by the sun reveals where the sun is. The offset between the Moon and the Sun's apparent position is caused by the orbit of the Moon around the Earth, so the of... | [
"I have estimated absolute times and times till sunrise/sunset/moonset many times, and its a fun trick. The error is quite large though (+ or - 1 hour). But I think there is comparable error when I do this with this sun. ",
"First estimating the hours till sunset with the sun:",
"So if you assume the sun is dir... | [
"Depends on the phase of the moon. If it's a full moon, the sun and moon are at opposite sides of the sky from each other, and the moon acts as a marker for where the sun is below the horizon (though you have to take your latitude into account and what season it is).",
"Alternatively, if the moon is in a half or ... |
[
"How does the process of creating the COVID vaccine differ from the process to create the flu vaccine each year?"
] | [
false
] | Are they the same, similar or completely different? | [
"There isn't \"the\" COVID Vaccine. There are many different kinds of mechanisms. The vaccines from Moderna and Pfizer are for example both mRNA Vaccines whereas Astazeneca's is based on an Adenovirus. Other manufacturers may also use different methods. So it may be easier to explain the machanism for the flu vacci... | [
"There are Covid vaccines being developed that do use the traditional chicken egg method due to cost. One them currently under trial is ",
"NDV-HXP-S",
"."
] | [
"I'm not really sure why the go to comparison is for flu with covid. There are plenty of other vaccines that most people receive that are more what covid vaccines are going for more similar results to. A big thing with covid is that we don't need the vaccine to predict and protect against every strain of coronaviru... |
[
"Questions about quantum entanglement"
] | [
false
] | Alright, my layman's understanding of quantum entanglement is that particles can interact physically even when separated by an arbitrary distance. What kind of particles can we observe entanglement with? What kind of physical state changes can occur? What can we do to cause a state change? Is the change instantaneous? If so, how does the "information" about the state change travel faster than c? | [
"Is this one of those quantum things humans just don't readily understand?",
"Basically, if you mean that it's something non-intuitive based on our classical understanding of the world. It's a biproduct of quantum superposition, i.e. Schrodinger's Cat.",
"Using the cat analogy, imagine you've got a Schrodinger'... | [
"I'm having a hard time wrapping my head around how it's instantaneous without some kind of \"communication\" at c between the particles",
"My understanding is that it's not that there's no \"communication\" between the particles, it's that it's impossible to transmit information this way because we can't control... | [
"Experiments are typically done either with the spin states of electrons or the polarization states of photons. With electrons they're forced into a specific state by a varying magnetic field, with photons it's with optical components like filters and mirrors. The change is instantaneous but no actual information i... |
[
"Do Mantle Plumes Originate From the Core-Mantle Boundary?"
] | [
false
] | [deleted] | [
"The science behind mantle plumes is a little uncertain because we are making inferences about what's happening thousands of kilometers beneath the surface, which unavoidably introduces some error. There are some things we can know about that depth pretty well, but it obfuscates many things too.",
"It is, however... | [
"Not to mention that seismic tomography imaging of plumes has a pretty significant ",
"error"
] | [
"Cavanical has a great explanation. One major field of research is figuring out the density differences between the different layers of the mantle. Check out this ",
"figure",
" As you can see, a plume coming from the core mantle boundary would have a very hard time breaking through the transition zone equally,... |
[
"Does light change colour when passing through a medium?"
] | [
false
] | I'm learning about light, reflection, refraction and similar topics in Physics. The textbook says: where n = absolute refractive index, c = speed of light in vacuum, λ1 = original wavelength, λ2 = refracted wavelength. The book uses this to explain how light disperses into colours as it passes through a prism, which I mostly understand (because speed of light in a medium depends on frequency), allowing each colour to have it's own distinct refractive index. My question is: If , doesn't this suggest that the wavelength is changed quite significantly as the medium changes? For example: red light has a wavelength of about 700nm, if it passes through a glass with n = 1.5, the equation suggests it has a new wavelength in the medium of about 466nm; a significant change in colour. In other words, does this mean that the red light that exits a prism was a different colour before entering the prism, and has been shifted to a shorter wavelength by refraction? | [
"You are correct that when light crosses from one medium into another, the wavelength changes. And the amount of change is determined by the refractive indices of both source and destination medium.",
"However, the velocity of the light is also changed by the same factor in this transition. What remains constant ... | [
"The wavelength of light (in most normal situations, as long as there are no nonlinear elements present) only depends on the medium the light is currently in, not where it has been previously. So if light has a wavelength of 500 [nm] in air, and it passes through a cup of water, it will have a wavelength 376[nm] ",... | [
"You are write, the important quantity is the energy of a photon. The other parameters are derived from energy and possibly depending on the medium but the energy doesn't change. ",
"To expand a bit, the photon energy can change when entering non linear propagation regimes. Usually this requires high intensity (i... |
[
"If you could detect and measure Hawking radiation, could you tell what was inside of the black hole?"
] | [
false
] | null | [
"If information is to be conserved (a principle known as unitarity) then the information brought in that everything that fell in, and then stored in the black hole, must then be all contained in the total Hawking radiation emitted by the BH in its whole lifetime, after it's evaporated completely.",
"If you had pe... | [
"A system can be in many possible states; to each you can assign a value for the entropy. Amongst all states of a system with a given energy, there is one with higher entropy than all the others. It's not too hard to prove this is actually the state of thermal equilibrium.",
"Entropy can be understood as the lack... | [
"the interior and surface of the black hole, according to the complementarity principle, are the same thing, just two different perspective on it. That's the magic of holography. There is information in the black hole, and you either picture it as being encoded in a membrane on the horizon, or equivalently in the 3... |
[
"What causes the rebound when a star collapses on itself and goes supernova?"
] | [
false
] | null | [
"There are two reasons behind it.",
"First is the immense shock wave in the core of the star due to the incoming matter smashing against the core. This shock wave slams against the collapsing matter which slows it down separately. This means less energy is required in order to reverse the matter and send it spewi... | [
"It's essentially a bounce. The matter collapses inward, and the rapidly intensifying pressure in the core causes (in most supernovas) the matter to be converted to neutrons, and then the rest of the infalling material will be pushed outward."
] | [
"So someone should probably correct me, but I think the implosion creates both high intensity energy that can escape the massive gravitational pull while simultaneously creating the excessively dense materials that then further collapse in.",
"Like imagine smashing a raw egg in your hand. The dense shell will cr... |
[
"Are our oceans getting saltier?"
] | [
false
] | I was reading some other post about how the hotter weather means that the air can also hold more water, and this is also why storms are getting stronger because of the higher amount of water that needs to be dumped. So my question is, since storms are also getting bigger, and more and more seawater is evaporating, is the amount of salt being left behind increasing? | [
"The most notable change has been the intensification of the water cycle and resulting gradients. At a local scale, salty regions become more salty and fresh regions become more fresh. Example papers on the subject: ",
"1",
" ",
"2",
"A significant problem is that we don't actually have reliable ways to m... | [
"Due to global warming and melting polar ice caps, it is assumed that oceans will become more dilute and less salty.",
"I would say both will happen. As usual, we can only, and should, measure and monitor salt concentration to establish which effect is greater."
] | [
"Salt in the oceans have reached a near-equilibrium state. Salts react with ocean minerals at roughly the rate that they are added due to runoff. There are a few other processes that salt is removed from the water, but reacting with minerals is the major one. For this reason, the salt content of the oceans stays re... |
[
"How do I answer this question about evolution? I've hit a wall with him"
] | [
false
] | This is a conversation on Facebook that's gone on to nearly 100 posts... His latest one is: "evolution is concerned with expressions of the various traits of living things. how can anyone profess a proper understanding of the expression of traits without understanding what's doing the expressing. Darwinian evolution solves this problem by saying there is nothing being expressed except random chance, which. when taken to its logical conclusion states that we are simply self-replicating self-perpetuating chemical chain reactions, which of course doesn't explain consciousness, laughter, pain, emotion, et al. this of course means that we have no free will as well. it can't possibly be correct. this brings us all the way back around to the original topic which is the absurdity of not "believing" in Darwinian evolution (as opposed to some other form), which all i'm trying to impress upon is not that absurd. You derided an agnostic mathematician simply because he considers himself a creationist, and has found unlikely allies within the religious communities. i just wanted to point out that there is likely a lot more to changes in life forms over time than the academic theory of evolution gives it credit for. i certainly don't have any of the answers myself, just a lot of unanswered questions." I'm like hitting my head against a wall here. I have a degree in Science so I've taken courses in Biochemistry, Molecular & Cellular Biology, Organic Chemistry, Chemistry, Microbiology, Biology, etc -- but I just don't know where to go from here. | [
"how can anyone profess a proper understanding of the expression of traits without understanding what's doing the expressing. ",
"DNA codes for proteins",
"expressed except random chance",
"Not random chance. Variation with selection.",
"we are simply self-replicating self-perpetuating chemical chain reacti... | [
"I have no idea what that person you are arguing with is saying. If there is an attempt at a logical argument in there somewhere, it did not succeed."
] | [
"This guy obviously isn't interested in discussing science if he is using terms like \"spark of like\" or \"elan vital\""
] |
[
"How do living organisms interpret DNA?"
] | [
false
] | So if I have some sequence of DNA that we know will produce a certain chemical in a bacterium for example how does the sequence get interpreted? My assumption is that for all organisms the same DNA will produce the same results. Is it possible to take any piece of DNA and using the rules of interpretation figure out what it does. Imagine I then had to translate this to programming code how would it be done? | [
"Basically, a segment of DNA gets translated to RNA, which is a similar molecule with a slightly different structure. Then, the RNA goes through an organelle called a ribosome where it is transcribed into a protein. Each set of three genetic letters adds an amino acid to a protein, and a protein is a chain of amino... | [
"To answer a couple of your other points:",
"1) In general yes, DNA from one organism will be expressed in the same way in another organism. This principle is at the cornerstone of genetic engineering. For example, a while ago I inserted a a sequence of DNA from P.falciparum (a single-celled eukaryotic parasite... | [
"Good answer! I just have one thing to add about protein structure:",
"X-ray crystallography is the go-to method right now for determining the three dimensional structure of a protein to near-atomic level resolution. While you need a good x-ray source for data collection, the actual solving of a structure can be ... |
[
"What are the evolutionary ancestors of spiders?"
] | [
false
] | How did spiders get from non-web building creatures to web builders? | [
"The first creatures we classify as \"aracnids\" come from the late Silurian.",
"Trigonotarbida",
" is the earliest aracnid we have in the fossil record.",
"Spiders themselves generally are very mysterious in the fossil record because they are extremely poor specimens for fossilization so little is really kno... | [
"I didn't want to have to type this all out on reddit, so I wrote it on paper and here's the link to a picture of it. ",
"http://imgur.com/wMkUcW1",
"But like what has been said, spiders are fairly mysterious when it comes to evolution and what not due to the lack of fossils to be able to accurately place them ... | [
"There is a Cambrian thingamajig called ",
" which is believed to be somewhere along the common original stem to proto-arachnids, sortof a common ancestor to spiders, eurypterids and eventually scorpions. ",
" was a marine nektonic to benthic predator which may have relied on pursuit.",
"Between these and the... |
[
"If air can both heat things up (friction) and cool them down..."
] | [
false
] | [deleted] | [
"Air/wind doesn't have any special heating/cooling properties. It follows the same laws of heat exchange equilibrium that everything else does: If you put something a room with warmer air, it'll get warmer. If you put something in a room with colder air, it will get cooler.",
"But your car engine has something in... | [
"which is created because of friction (?).",
"Note that many things that go wicked fast (as in an atmospheric entry) are heated not because of friction but because the air is compressed into a hot ",
"shock layer",
" in front of the object."
] | [
"The speed is never \"too high to disperse the heat cloud\". The heat cloud is going to get dispersed no matter what. It's just a matter of putting in more heat (via friction) than you're taking out (via dispersion), and the exact point at which this happens will vary with the situation for objects that produce hea... |
[
"What would life be like if our planet was tidally locked?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"/r/AskScienceDiscussion",
"Please see our ",
"guidelines.",
"If you disagree with this decision, pleas... | [
"I guess the wording was a little vague, I didn't mean to ask how life would adapt to such conditions but rather, what the consequences would be if earth were to become tidally locked tomorrow? Would the dark side freeze and sunny side fry?"
] | [
"Hypothetical or \"what if\" questions like that would still be better off in ",
"/r/asksciencediscussion"
] |
[
"Why do my sister's eyes change color when she cries?"
] | [
false
] | null | [
"I have no rhyme or reason to give you, but pics would certainly be nice."
] | [
"Sorry, but we don't allow questions like this, for reasons that I think were best explained ",
"here",
". As such, I've removed it."
] | [
"Whoops! My bad "
] |
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