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[
"How to Catalysts Actually Work?"
] |
[
false
] |
I'm a high-school student and the common definitions say that that they aren't used up in a reaction, as seen when writing the reactions. But there are simulations online often depicting the catalyst combining, even have if not permanently, to the reactant molecules. And surely, the enthalpy 'hill' on a graph can't just be magically shortened without breaking the laws of thermodynamics. I would like to have a more thorough explanation than just "it makes a reaction go faster"
|
[
"They make reactions go faster ",
" providing a different way to get from A to B.",
"In many cases the catalyst gets \"consumed\" in one step and then \"produced\" again in another, so the net effect is that the catalyst is not used up, but they are very much a part of the reaction.",
"The enthalpy hill doesn't get magically shortened -- instead the reaction pathway takes an alternate route that inherently involves shorter hills."
] |
[
"They serve as an intermediate step in the reaction, then restore themselves to their original form afterwards. ",
"Exact mechanisms are probably around second year university chemistry level (typically with understanding chirality as a prerequisite), but you might find ",
"https://en.wikipedia.org/wiki/Hydrogenation",
" useful, particularly 40% through when hetrogenous catalysts are discussed.",
"Edit: Also ",
"https://en.wikipedia.org/wiki/Haber_process",
" for a practical application. 1% of world energy consumption is used in this process."
] |
[
"Does the catalyst consist of the same atoms after being consumed and reproduced?\nIf not, could this be used to replace isotopes or radioactive particles in molecules?"
] |
[
"Does Proxima Centauri have it's own solar system? If so what might it look like?"
] |
[
false
] | null |
[
"Though Proxima Centauri ",
"has been searched for planets",
", none have been found (yet). However, Proxima Centauri may be in a triple star system, with two stars orbiting each other from a small distance - Alpha Centauri A and B - and Proxima Centauri orbiting that pair from a great distance. We have found an Earth-mass planet orbiting ",
"Alpha Centauri B",
"."
] |
[
"A point that bears repeating as we continue to discover more planets is that ours is the only \"",
"solar system",
"\" since our star is Sol. Other systems are called \"",
"star systems",
"\" or \"",
"planetary systems",
"\"."
] |
[
"This.",
"Also, in that case, OP could have just used \"system\". "
] |
[
"Is there any data to show/explain trends in food allergies? Wheat, Nut, and so on - has there been an increase in afflicted people?"
] |
[
false
] |
Just something my friends are chatting about - that it's strange how there's a lot of people afflicted with allergies to some of the most common food products - is there a reason for this?
|
[
"This",
"00523-X/abstract) is the study Got-Engineers is referring to. The researchers took a historical look at stored blood from military people, tested it for Celiac disease, and compared it to a cohort of current military people. They did see an unexplained significant increase over 50 years in the number of people who have/had celiac disease. To the best of my knowledge, we still don't know why this is. The article has been cited ",
"112 times",
", so perhaps a follow up exists in there.",
"As for actual food allergies, no one really knows. It could be better diagnosis. It could be something to do with the hygiene hypothesis. It's like a combination of factors.",
"EDIT: This is what the first link above should be: ",
"http://www.gastrojournal.org/article/S0016-5085(09)00523-X/abstract"
] |
[
"This article: ",
"Recent advances in coeliac disease\n",
" mentions an important point that celiac disease is now diagnosed using more sensitive factors like a positive serology, whereas before it relied on symptom occurence.",
"Edit: I believe there are studies that support a positive trend upwards that account for improved diagnosis and awareness if someone would like to include those."
] |
[
"While your 2006 paper is correct, the 2009 paper (whose link doesn't seem to want to work), used seriology equally across both the historical blood samples, and from the modern cohort. So it really is a possible case of more people having celiac disease."
] |
[
"How fast are the molecules moving?"
] |
[
false
] |
How fast are the molecules moving around in say a glass of room temperature water? Could this be measured or visualized by adding food coloring? It seems like its not that fast.
|
[
"A general average temperature for a gas of molecules with mass M and temperature T is the square root of 3kT/M, where k is Boltzmann's constant. This works out to a few hundred m/s for air.",
"Liquids are a bit more complicated because the molecules interact, but a water molecule might, on average, go about 50 microns in a second."
] |
[
"Well, it's a bit more complicated than that. It's actually diffusion. So even though the molecules would be moving faster than that, they keep bumping into each other, so the average velocity is actually zero. That number is basically how the average ",
" distance a molecule travels in a second."
] |
[
"edit: I ignored boiling which was kinda dumb. The post holds for any gas, though.",
"Good question. I went way over length as usual, but if you want any clarification feel free to ask. To answer the question, we need three ideas:",
"The equipartition theorem",
"The Boltzmann Distribution",
". ",
"Diffusion",
" ",
"The wikipedia articles are linked, but I'll touch on the good bits briefly.",
": All systems (a molecule, a cup of water, etc.) have ways that they can store energy. For example, you can pick up kinetic energy by translating, or by rotating. In 3D there are 3 different directions in which to translate and 3 different directions in which to spin. The equipartition theorem says that at equilibrium, ",
", and is related to the temperature of the system. If you go to the wiki link you’ll see that each way of storing energy holds on average (k)(T)/2, where T is the temperature and k is some constant. Add up the energy from up/down motion, right/left motion, and forward/back motion and your total kinetic energy is 3(k)(T)/2. See if you can work backwards to iorgekefld’s result using that tidbit. So, if you give me a room full of gas and a thermometer, I can tell you the ",
" speed at which the molecules are going up and down, side to side, forwards and back, and spinning in each direction. I can do this without making a single individual measurement, because of the laws of statistical mechanics. By the way, the number you get out for water is ~640 m/s",
": The EPT tells me the average speed at which things are zooming around, but it doesn’t tell me anything about how that average is formed. For example, the sets {1,2,3,4,5,6,7,8,9} and {5,5,5,5,5,5,5,5,5} certainly look different, but their averages are the same. One has a wide spread, and the other has a narrow spread. For our cup of water or room full of gas, what does the spread of speeds look like? Well, it turns out the spread is given by the Boltzmann distribution, which you can see in the wiki link. It’s a bell shaped curve which is fat around the center (the ",
" speed given to us by EPT) and narrow at the extremes. What this means is this: in your cup of water, the average speed of a molecule is ~640 m/s. You’ll find lots of molecules going 630-650 m/s, fewer going 650-700 m/s, far fewer going 700-1000 m/s, etc etc. The further you move away from the average (either faster or slower), the fewer molecules you’ll find.",
": So, we know your water molecules are moving around 640 m/s, and while some are a bit faster and some are a bit slower, our cup is only 7 cm across so surely if we followed a single molecule it would by zipping around the cup like mad, smashing into the walls thousands of times per second, right? Well, not quite. The molecules are moving quickly, but they’re packed quite densely so they’re constantly smashing into one another; they never have a chance to move far before they have a collision and zip off in some other direction. Since there are neighboring water molecules in every direction, we’d expect the single molecule we’re following to not move at all! If it’s equally likely to get smashed up as down, left as right, forwards as back, then we must (on average) stay put. You’re stuck inside a mosh pit and surrounded by guys that are all the same size. However, if we don’t care about what direction we’re going and only about the distance from home we’ve traveled, you’ll see that a molecule does actually wander over time due to random fluctuations in the speeds of its smashing neighbors. This poor explanation, but a really good illustration is dropping some food coloring in a very still liquid. You’ll initially have a small dark spot where all the food color molecules were deposited, but over time the spot will widen and get lighter since they’re getting smashed around by neighboring water molecules. The center will always stay the darkest since on average, the",
" displacement is zero due to the symmetry of the system like we said, but over time the dot will get more and more spread out. The speed at which the dot ‘spreads’ is closer to the 50 micron/s that iorgekefld was talking about, but the actual speed depends on some further factors. ",
"TL;DR : The average speed of molecules in a cup of water is given by the EPT and is roughly 640 m/s at room temp. Not all molecules have the same speed in a cup of water, and the spread of speeds is given by the Boltzmann distribution. Molecules are constantly getting smashed around by neighbors in a liquid or gas, and have zero displacement on average. However if you only care about how far from the starting point they move, you’ll notice motion of a speed scale much, much slower than 640 m/s."
] |
[
"Is there any scientific evidence to support being born gay?"
] |
[
false
] |
before i start im pro same-sex marriage. but the question i have is if there is any evidence that you are born gay Vs being nurtured into it by your environment. i ask this because from an evolutionary perspective it doesn't make any sense. so have there been any cases of identical twins being born, however one being gay and the other being straight. Or any studies of children born in certain environment and the number of homosexuals who come out of those environments.
|
[
"I feel the need to chip in here, partially because the hand-waving, \"anything is possible\" nature of many evo-devo arguments drives me nuts, but mostly because I feel as though we need to define terms better.",
"\"Gay\" is not a scientific term, any more than \"rich\" is. Homosexuality is certainly a phenomenon, as is wealth, but just as many unrelated factors interact to determine your final level of wealth, many factors (some genetic, some developmental, some cultural) interact to determine your eventual partner preference, which itself can be fairly complex. In my experience, while most people consider themselves simply \"gay\" or \"straight\" with respect to self-identification, the details of their sexual behavior and impulses are much more nuanced. For example ",
"one study found that homophobic men are more likely to become aroused when exposed to homoerotic imagery",
". While this result shouldn't be interpreted as proof that \"homophobes are secretly gay\" (because, again, the term is too vague to be meaningfully useful in a scientific context) it ",
" raise the possibility that, under different circumstances (different upbringing, different culture, different ",
" exposure) they may have been more likely to self-identify as gay in adulthood than others.",
"With respect to evolutionary fitness, this ",
"indelicately titled summary",
" provides what strikes me as the most plausible explanation presented to date. Specifically: A kin group in which (a) some members turn out gay but (b) other members of the opposite sex display greatly increased fertility will propagate itself, despite the \"non-participating\" members. In other words: A gene that makes men more fertile but women more likely to be gay (or visa versa) can break even or be a net positive.",
"That said, mistrust anyone trying to tell you a \"just-so\" story trying to lay out an evolutionary argument based on social constructs. As it happens ",
"\"heterosexuality\" is as much a modern concept as \"homosexuality\" is",
", so people who think they can easily intuit prehistoric social norms is probably deluding themselves.",
"The bottom line is this: Some people are \"born gay\" insofar as they never experience sexual attraction towards the opposite sex, and some \"choose to be gay\" because they experience attraction to both and decide based on their experiences to self-identify as gay. Others choose to be straight, or bi, or something else. The only ",
" approach that makes sense is to honor the label an individual chooses for themselves, because the science points squarely to partner preference being a nuanced continuum.",
"EDIT: Wrote \"in vitro\" instead of \"in utero,\" now fixed."
] |
[
"wikipedia's article provides a good primer on the topic",
" ",
"So far, the current belief is that it isn't ",
" genetic, but genes enter into it at least partially. The other factors seem to be stuff like conditions in the womb.",
"As for evolutionary stuff...scientists think it is actually beneficial in a non-obvious way, sort of like how sickle-cell anemia is linked with malaria resistance.",
"The so-called 'gay uncle' theory posits that people who themselves do not have children may nonetheless increase the prevalence of their family's genes in future generations by providing resources (food, supervision, defense, shelter, etc.) to the offspring of their closest relatives."
] |
[
"It's too good of a post not to read in full for anyone who deliberately clicked the link."
] |
[
"What happens to sound energy in space?"
] |
[
false
] |
Since sound doesn't travel in space, what happens to all of the energy that would be sound waves? Do they just not produce sound initially? For example, if I could just shout in space, what would happen to my shout?
|
[
"The energy would just bounce around in the medium for a while, diffusing into a very low thermal energy. Back to the visor, initially the sound would make it vibrate like a speaker. But the sound waves would go back and forth, weakening due to damping effects and getting scrambled by continual reflections from the inner surfaces of the visor. This mechanical motion would eventually devolve into simple thermal motion of the molecules in the visors, which would dissipate as photons into space, but some of the energy would also dissipate from the visor into the helmet.",
"There's not a lot of energy in sound, though. Here's ",
"an analysis of how long it would take to yell to heat up a cup of coffe",
":",
"In other words to heat up a quarter liter of coffee 50 C it would take:\n1 year, 7 months, 26 days, 20 hours, 26 minutes and 40 seconds"
] |
[
"The energy of sound only exists in a medium. If you could shout in space, that would assume you had air in your lungs. If you were in your space suit and shouted, the sound would be audible inside your suit, and the vibrations would be readable from the outside. But if your visor was vibrating from the sound of your shout, it wouldn't have anything to vibrate against on the outside, so the sound wouldn't propagate."
] |
[
"so in short, sound vibrates the last medium it can reach and then just vibrates until it dissipates? "
] |
[
"During short term periods of carbohydrate overfeeding, what happens to the extra glucose that the body can't convert to fat with de novo lipogenesis? Does it get urinated out?"
] |
[
false
] |
I'll set up the situation specifically: Person A eats at a caloric deficit, and keeps carbohydrates low (<30g/day) for 6 days. On the 7th day they eat 200% of their body's energy requirements in carbohydrate (starch/glucose) over a 24 hour period, while keeping protein at 1g/lb, and dietary fat to 10-12% of the calories they have ingested. This person is strength training, and is at a normal bodyfat percentage (Let's say 15%). They resume their carbohydrate restricted diet in the days that follow the overfeed. Now let's talk theory. Keep in mind I am a layman, and this is only what I've picked up from internet research. Hopefully someone here can chime in with an educated perspective: At this point there is a bunch of glucose in the body. It is being converted to glycogen and stored in the muscles and liver. Theoretically speaking, the body hasn't had time to ramp up de novo lipogenesis since the overfeed occurred over such a small window. Additionally, while fat oxidation has been sufficiently suppressed via increase carbohydrate intake, the subject isn't taking in any substantial dietary fat in the days that follow that would cause significant weight gain. So here is my question: What happens to the glucose after the overfeed? The muscles and liver are saturated. The body's resting metabolic rate is higher, sure, but not enough to account for ALL of the excess glucose in the subject's system. DNL hasn't ramped up and isn't converting a significant portion into bodyfat. So where does it go?
|
[
"How short a timeframe are we talking about here? After feeding blood glucose levels peak for about an hour before it goes down as it is being metabolized.",
"Most likely the excess gets passed out through the urinary tract. The blood has to keep its solute content constant, after all, so it will dump the remaining sugar into the kidneys. That is, assuming your cells are not longer taking up glucose fast enough. we know excess glucose is released through the urine in diabetics, so that's my best bet.",
"[caveat: I have a biochemistry book in front of me and it's blank on this issue] "
] |
[
"You don't have to be diabetic to pass glucose in the urine. if you dump enough glucose, your blood sugar spikes beyond what the kidneys can reabsorb. you only have so many glucose pumps in the nephrons; when they cannot pump all the glucose back to the blood, you lose it in the urine. My A&P instructor related a story about eating an entire batch of chocolate pudding right before his football physical, resulting in this phenomenon. (he is not diabetic, but his urinalysis showed glucose.) "
] |
[
"You don't have to be diabetic to pass glucose in the urine. if you dump enough glucose, your blood sugar spikes beyond what the kidneys can reabsorb. you only have so many glucose pumps in the nephrons; when they cannot pump all the glucose back to the blood, you lose it in the urine. My A&P instructor related a story about eating an entire batch of chocolate pudding right before his football physical, resulting in this phenomenon. (he is not diabetic, but his urinalysis showed glucose.) "
] |
[
"Are there any gross evolutionary pressures still acting on the human species?"
] |
[
false
] |
According to video, there aren't. I'm a little sceptical on this one..
|
[
"Yes I agree and would say that the video is misleading. These should thoroughly answer your question:",
"http://www2.yale.edu/eeb/stearns/pdf/PNAS-2009-ByarsEtAl.pdf",
"http://www.anthro.utah.edu/PDFs/accel.pnas.smallpdf.pdf",
"http://www.facstaff.bucknell.edu/jvt002/BrainMind/Readings/Laland2010.pdf",
"Also, something easier to read: ",
"http://www.time.com/time/health/article/0,8599,1931757,00.html"
] |
[
"Evolution is the change in allele frequency over time. This will happen with or without natural selection through drift. So yes, we're still evolving.",
"Are we still influenced by natural selection? Yes, in many ways. Our blood types (",
"Duffy group",
"), disease risk (",
"Parkinsons?",
") and lots of others (",
"ATP6",
").",
"Here's a review from 2006 in Science (",
"link",
")."
] |
[
"What I don't understand when it comes to natural selection is that for a genetic trait to be transmitted, or not, only counts if the organism has been successful in reproducing. So how could we become immune to disease that hit us in late ages, when we are not reproducing anyway, like Parkinson, Alzheimer, some forms of cancer etc?"
] |
[
"Why is space expanding?"
] |
[
false
] |
What causes spaces to expand, how does it expand and why is it doing it?
|
[
"Broadly speaking, there are three relationships at work. They all boil down to something that ",
" and ",
" very much like pressure.",
"Seal up a box full of air and apply heat to it. What happens? The pressure inside the box goes up. If the pressure goes up ",
" the walls of the box will literally expand; the pressure will push them apart.",
"That's how metric expansion works, except there's no box.",
"The geometry of spacetime is proportional to … well, to a variety of things. But from the cosmological perspective — where we ignore gravity — we can consider three.",
"First, there's the density of cold energy. \"Cold,\" in this context, means non-relativistic stuff, like galaxies and you and me.",
"Next, there's hot energy. \"Hot\" means relativistic, or having much more kinetic energy than mass. Light is hot energy; so are neutrinos.",
"Finally, there's dark energy. Dark energy is the intrinsic energy of the vacuum.",
"Cold energy is related to the inverse ",
" of the scale factor. In other words, you can imagine — and I must emphasize, this is an ",
" — that cold energy exerts a pressure on space, and that pressure is proportional to the inverse third power of the scale factor of the metric.",
"Hot energy does the same thing, only the something-like-pressure it exerts is related to the inverse ",
" power of the scale factor.",
"And dark energy? That's constant. Over all time and space, it never changes. It's like filling a box with air, then magically expanding the box to many times its original size. What happens to the air? Well, it becomes less dense, obviously, because the same amount of stuff now fills a larger volume. Which means the pressure inside the box goes down, right? Not with dark energy. Fill the same box with dark energy, magically expand the box, and the energy density inside it stays exactly the same, meaning the effective pressure on the walls of the box stays exactly the same. (Only, again, there's not actually any box.)",
"At different scales, each of these three terms will dominate the others. When the scale factor is very small, hot energy dominates, because the inverse fourth power of something small is bigger than the inverse third power of something small. But as the scale factor increases with time, one-over-the-fourth-power falls faster than one-over-the-third-power, so hot energy ceases to dominate and cold energy becomes the most important term. As the scale factor continues to go up, eventually both hot energy and cold energy exert \"less effective pressure,\" sort of, than dark energy does, because even though dark energy's contribution is very, very small, it's constant over time and space.",
"Right now, we're either in or transitioning into the vacuum-dominated epoch. Meaning either metric expansion is already dominated by dark energy, or it will be in a few dozen billion years. (The data are a bit ambiguous on that point, since obviously it's not a hard cut-off but rather a gradual change over time.)"
] |
[
"That's not the reason. It would expand without vacuum energy as well, just not accelerated. It would even expand if it was empty and negatively curved."
] |
[
"I'm afraid this is one of those questions where we can't give a better answer than \"That's just how it is.\"",
"It's a consequence of general relativity. You can derive the Einstein Field Equations from a set of assumptions, and if you do all the math, it turns out that the universe must expand. Einstein couldn't believe it at first as well and artificially modified his equations so that they allow a static solution and regretted it later after they found physical evidence for the expansion.",
"Whether he regretted it because he made an ad-hoc modification to the math without physical motivation or because he missed the chance to predict the expansion is up to the interpretation of the reader."
] |
[
"It took a couple of billion years for cyanobacteria to convert the atmosphere into current state. How long will it theoretically take animal life to convert it back considering deforestation etc. Is it even possible? Very interested in gas exchange rates."
] |
[
false
] | null |
[
"The oxygen cycle is a self regulating feedback loop.",
"Too little oxygen, animal life declines and uses less, and eats fewer plants, causing levels to rise.",
"Too much, you get more animals, and things start to catch on fire, bringing levels back down."
] |
[
"Thanks."
] |
[
"Does anyone know the approximate size of early cyanobacteria?"
] |
[
"Would a preserved brain have a consciousness?"
] |
[
false
] |
Is it possible to preserve a brain so that brain activity continues? If so, would there be any type of consciousness even without a body or senses? I've had nightmares where, in them, I'm trapped alone in my own thoughts for an eternity without any senses.
|
[
"I am a programmer who has done a lot of thinking about the brain and artificial intelligence.",
"I don't really buy the idea that the human brain is as unfathomably complex as everyone makes it out to be. I think that the commonly made comparisons to ultra-powerful computers refer to the difficulty of simulating a brain at the lowest level of molecules and their interactions.",
"I think that once the brain is understood, it will be possible to simulate it on a more abstract, symbolic level with far less computing power. Such a simulation will be a faithful re-creation of the brain's processes, while leaving out some low-level failure modes such as cancer, aging and Alzheimer's.",
"It's kind of like the difference between building an atari 2600 emulator by simulating all of the atoms in each original microchip and wire, vs. simulating it at the level of digital logic. Since we completely understand the functioning of the electronics, we can abstract them out of the simulation. We lose the ability to simulate hardware failures (heat, electromigration, corrosion, brittle plastic, etc.), but for most purposes a symbolic emulation is sufficient, and far more efficient."
] |
[
"Well, I'm no biologist, that's for sure. I don't want to minimize the difficulty of figuring out the brain or minimize the efforts of the researchers. The task of completely discovering and specifying the brain's processes is certainly the hardest part of the job.",
"I am aware of the massively parallel nature of the brain, and the large number interconnects. My contention is that most of the complexity does not need to be emulated in order to produce a useful and accurate simulation.",
"The design of the natural brain is the result of having to meet a lot of requirements that we don't have to meet. Thus we can use a different, more efficient design. For example, it has to be a structure that can be grown from DNA. It has to utilize a chemical energy source. It has to be robust enough to last 100 years and it has to tolerate a large number of random component failures.",
"In designing a simulated brain, we can sidestep all of those requirements. ",
"One approach to simplification is to break the problem into segments. For example, a normal computer program could grow a brain, determining all of it's connections in advance. I'm pretty sure that the physical connections are mostly static, and only the level of transmission changes regularly.",
"Once the structure is determined, it could be compiled and downloaded into a highly specialized circuit (e.g. an array of FPGAs) that is designed for efficient, massively parallel execution.",
"Part of the process of creating a simulation is determining what exactly your goals are. If the goal is to create a detailed and perfectly accurate simulation of all of the physical properties of the brain, then that is probably impossible. But if the goal is to create something that produces the same outputs when presented with the same inputs, then there is no reason to stick with the same messy architecture that nature evolved.",
"Personally I believe that simulating a consciousness is going to be more difficult than simulating the processing. I think it's widely understood that babies develop intelligence by interacting with their environment and processing the feedback (taste, touch,etc.) that they receive.",
"Until we can develop an artificial body that can taste, smell, touch, see and hear for the artificial brain to reside in (or a suitably accurate simulation of such a body and it's environment), it's unlikely that we could create anything resembling a human consciousness. But that's a different problem from simulating the brain itself."
] |
[
"10 000 bits is roughly 1.2 kilobytes, 1200 bytes, that's not much. But your brain doesn't do math with 1200 byte long numbers (universe doesn't contain that many particles!). Every neuron has hundreds of inputs, but those don't add to the \"bitness\" of a neuron. It's just a flawed comparison made to impress people.",
"I agree with aerobit, it won't be so hard to emulate storage/executional structure of a brain in the near future (as in, host neural networks of comparable size). It would be significantly harder to figure out the ",
" structure of our brains. I imagine it's akin to hundreds of megabytes of spaghetti code without any comments, patterns or sane logic behind it. It'll probably take a lot of research just to scan the neuron map, then much more to figure out how it works."
] |
[
"Why does inbreeding cause genetic abnormalities?"
] |
[
false
] |
I've always heard with inbreeding, there are higher risks of abnormalities. Why is that?
|
[
"Normally get two slightly different copies of your genome from your parents. If one has a minor fault in a gene often the other copy works fine and compensates. With inbreeding you get identical copies (you loose heterozygozity), so any fault will be present in both copies and will cause problems. "
] |
[
"This. One more relevant thing to note is that we all carry a bunch of these minor (or even major) faults, they just don't do (usually) any damage as long as the other copy is fine (they are recessive). So for two people who are unrelated, the likelihood of them having a fault in the same gene is pretty low, and their kids will probably be healthy. In inbreeding, the likelihood of both father and mother having the same fault is increased, increasing the risk of a child being born with no working copy of the gene."
] |
[
"For example there is a family that has some kind of genetically caused sickness which transferred to family members in no regular way (like every 2nd person has it). So the chances that the baby of brother and sister of this family will get these mutated genes from its parents is much higher that if there is just one person having the mutated genes. Since they are not very often dominant genes the chance to get the \"normal\" genes from the family outsider is higher.",
"I hope this is kind of understandable :)"
] |
[
"Given enough time, is it theoretically possible to travel to the centre of the universe? Would it be different from any other point? Noticeable older perhaps?"
] |
[
false
] | null |
[
"There is no center. The universe is likely infinite in extent, or else finite but unbounded. Either way, no center. See the FAQ for more."
] |
[
"So would there be a bit of universe that is older than any other bit of the universe? I'd settle for going there. "
] |
[
"No, the whole universe is the same age."
] |
[
"Does our subconscious constantly run certain \"subroutines\" (for lack of a better word)?"
] |
[
false
] |
My office is two doors down from my supervisor's. I've noticed that, while at work, my brain subconsciously listens for him to say my name in conversations with others and I start actively listening to what's being said after my name is mentioned. I think this is probably the case with our names outside of this situation but this was where it became very obvious to me that I was constantly (and unknowingly) listening for it. Are there certain situations or conditions that our subconscious brains are always watching out for that we're not consciously aware of? If so, how many have been discovered?
|
[
"Yes, it is constantly carrying out check-ups of your surrounding, and associative memory is always on the go, deducing what is happening. Type 1 process are automatic and involve no cognitive strain. You should read Daniel Kahneman's 'Thinking, fast and slow' for superb insight into all of this. You will really enjoy it."
] |
[
"Thank you all for your answers. They were very helpful. And thanks to acetylserine for the suggested reading. I'll definitely give it a look."
] |
[
"No, not in the way you're describing. What are you describing, though, is called the ",
"Cocktail party effect",
" (note, that this term is used in multiple fields with different properties). ",
"There is no real \"subconscious\" or \"subroutines\" as the terms are used. But those terms describe what the field of cognitive psychology and cognitive neuroscience study."
] |
[
"When measuring nutritional information and suggested serving size, is that including the empty space inbetween that food in a half cup measurement?"
] |
[
false
] |
What I'm trying to figure out: Example - When I look at the side of my box of Cinnamon Toast Crunch, the suggested serving size is 3/4 cup at 130 calories. Is that 3/4 of a cup as if I had just scooped up 3/4 out of the box? Or is it 3/4 of a cup of cinnamon toast crunch that has been ground up and is filling all space withing that 3/4 of a cup? Sorry if this is the wrong subreddit, I just thought their might be some nutritional scientists kicking around! Thanks
|
[
"Seems like this is a perfect opportunity for you to do your own measurements. The label includes a mass as well (usually says \"per 3/4 cup (100 g)\" or something.) If you have a kitchen scale, you can scoop your own 3/4 cup and weigh it."
] |
[
"It is 3/4 of a cup as if you had just scooped up 3/4 cup straight out of the box."
] |
[
"There are soooo many instances on askscience where I just want to tell the person...\"JUST GO DO IT!!!\" I'm always worried about down votes because its askscience, not doscience...or some such nonsense. I applaud and upvote you rupert1920."
] |
[
"Why do particles (photons, electrons) interact only with themselves in double-slit experiment?"
] |
[
false
] |
If a particle is an excitation of a field, what is the nature of this excitation that it knows which whole it's a part of? As in "oh, look here, seems this part of field excitation is a part of my probability density distribution function, let's subtract/add to it". Normally, when I throw two stones into a pond, created waves will interact, even though both come from different stones.
|
[
"I can make the experiment in non-ideal environment at home, using a laser and 0.05mm graphite from mechanical pencils. Still, as I understand, for some reason the photons are \"forbidden\" from interacting with other photons, happily interacting with themselves."
] |
[
"There you go:",
"http://www.youtube.com/watch?v=ZXyxnxnWAAQ"
] |
[
"In that case I think the coherence of the light would ensure they mostly interacted with themselves; as far as I am aware other frequencies ",
" occasionally interact but at a level you would be unable to detect with such a setup."
] |
[
"Are more calories burned in hot or cold weather?"
] |
[
false
] |
[deleted]
|
[
"Sports Science in-training here. You burn more calories in cold weather because your body needs to work a little harder to keep your core temperature up. Ever heard of turning down the heat to lose weight? When you shiver you are using ATP (muscle energy currency in plain simple English) and when ATP is used a by-product is heat. When your muscles work, they are also producing heat - so when it is cold and you are shivering you are basically burning fat because your body is attempting to keep itself warm. Hot weather requires you to hydrate more to replace fluids, and makes it harder to actually exercise due to the heat. Your body's natural response when it gets too hot is to cramp up - it's way of telling you to slow down. "
] |
[
"Just to make it clear so someone won't kill him/herself.",
"If you are fat and you try losing weight by staying cold, you are a fat idiot."
] |
[
"You're always \"burning calories\". About 2000 per day."
] |
[
"Why are diseases such as Alzheimers and Creutzfeldt-Jakob non-treatable? What is the best method of prevention?"
] |
[
false
] |
My understanding is that rouge, denatured proteins aggregate and deposit within specific tissue. As with AD, amylod-B deposit into brain material and the byproduct is linked to dementia is not well understood. What would be the best Chem/biochem solution to prevent aggregates from occurring in-vivo?
|
[
"First, I'll answer the question you didn't ask but everyone is going to answer. Alzheimer's and CJD are probably not closely related diseases. CJD is a prion related disease, caused by a build up of a more stable foldings of naturally occurring proteins that auto-catalyze (i.e., make more of themselves). ",
"Alzheimer's tends to be used as a blanket diagnosis to describe neurodegenerative symptoms while the patient is alive (the same way we say we have the \"flu\" even if we didn't actually get tested for the influenza virus), because the presence of the disease can only be confirmed if an autopsy finds B-amyloid plaques and tangles. Few patients agree to this test.",
"The exact mechanisms of these diseases is not understood. ",
"But the actual question you asked isn't about that at all, it's about if we can break down (denature) the target proteins. This has a few problems:",
"1) It's unclear if the proteins in question are causes or effects of neurodegeneration. They may be a by-product or waste product. Breaking them down would thus have no impact on arresting the progression of the disease. It would be like washing away the ashes of a house fire.",
"2) It's unclear how these substances would be delivered. Most molecules do not cross the blood-brain barrier, and both of these disease begin fairly deep in the brain. ",
"3) Compounds that denature proteins (surfacants and detergent), denature proteins. It's unclear how you would explain to a detergent that it should breakdown the b-amyloid but not the rest of the brain.",
"On your prevention question: ",
"CJD",
" avoid prion-infected human byproducts. ALZ: dunno."
] |
[
"Nobody knows really. Genetics appears to have an effect so start by not being related to anyone who developed dementia. Insulin-like Growth Factor (IGF) appears that it may play a role but the literature is somewhat evenly divided showing it is both neuro-protective but also induces amyloid deposition. So there is clearly some, yet to be understood, role for IGF. ",
"IGF promotes amyloid protein metabolism:",
"https://www.ncbi.nlm.nih.gov/pubmed/20139073",
"https://www.ncbi.nlm.nih.gov/pubmed/19167357",
"IGF as neuroprotective:",
"https://www.ncbi.nlm.nih.gov/pubmed/11205145",
"https://www.ncbi.nlm.nih.gov/pubmed/22621285"
] |
[
"With respect to treating CJD, as I understand it, the main problem is developing a method that targets the PrP",
" (abnormal) proteins while ignoring the PrP",
" (normal) proteins. Given their only difference lies in their structural conformation this is a difficult problem.",
"On a more banal note, as with many rare diseases, the main barrier to developing a treatment or cure is the lack of an economic incentive."
] |
[
"To what extent do massive asteroid impacts effect the tectonic plates?"
] |
[
false
] | null |
[
"Hey, we check all posts before releasing them onto the sub and yours got stuck for too long. Would you mind resubmitting? It may take a couple hours to get released. If it doesn't show up again, please reply here or send us a modmail. Sorry about that!",
"Also, \"effect\" in your title should be \"affect\". No big deal, but you'll get a bunch of corrections if this goes out on the sub so I thought I'd let you know before you resubmit."
] |
[
"Haha, I agonized over effect/affect because I knew I would get a ton of corrections. Somehow those 2 words are the only ones in the English language I can never remember the difference between."
] |
[
"A good rule of thumb is that \"effect\" can't be a verb."
] |
[
"With a lot of misinformation being spread, how are we certain this is delta that is causing the rapid uptick?"
] |
[
false
] | null |
[
"https://covid.cdc.gov/covid-data-tracker/#variant-proportions"
] |
[
"So In essence my assumption is correct. Due to sequencing we confirmed there was a mutation. We have confirmed that the mutated strain of the virus is present in the US. The change of behavior in the statistics then confirm that it is spreading. ",
"It’s unfortunate that people prefer to argue against this when simple logic can look at empirical data and confirm that it makes sense. Evidence is only necessary when it fits their narrative."
] |
[
"It's like standing in a blizzard and saying it isn't snowing."
] |
[
"Why do scientists think spaghettification is real if there is no friction in space?"
] |
[
false
] | null |
[
"Spaghettification has nothing to do with friction, it’s about tidal forces. You are not a point mass. If you’re in a situation where gravity is much stronger at your feet than at your head, you’re not going to be accelerated uniformly."
] |
[
"I understand that gravity is stronger at my feet than my head. But it still doesn't make sense to me that I would spaghettify. If I attach a rubber band to the wall and pull it, the rubber band will stretch. But if the rubber band is not attached to anything and I pull it it will just move instantly however I pull it. My body parts are all attached to each other and the gravity is presumably pulling me into the black hole and I am free-falling towards it. If there is more gravity on my feet why wouldn't that just accelerate me?"
] |
[
"There's a nice animation ",
"here",
".",
"If you consider the pieces of mass that make up your body as separate, it's easier to visualize. The fact that they're actually attached to each other to form a larger body doesn't change the way that gravity acts on each individual piece of you."
] |
[
"In 2005 the UN said that by 2010 there would be 50 million climate refugees. Why were they wrong?"
] |
[
false
] | null |
[
"The figure seems to come from ",
"this",
" publication.",
"That publication (which was published in 2008, as the cached page clearly shows) claims \"There is a serious potential for future conflict, and\npossible violent clashes over habitable land and natural resources,\nsuch as freshwater, as a result of climate change,\nwhich could seriously impede food security and poverty\nreduction. An estimated 25 million people per year already\nflee from weather-related disasters; global warming\nis projected to increase this number to some 200 million\nbefore 2050, with semiarid ecosystems expected to be the\nmost vulnerable to impacts from climate change refugees\n[Global Chapter 6]\"",
"The publication that is a summary from contains the 'global chapter 6' in question. There we find:",
"\"An estimated 25 million people per year already flee from weather-related disasters and global warming is projected to increase this number to some 200 million before 2050 (Myers 2002); semiarid ecosystems are expected to be the most vulnerable to impacts from climate change refugees (Myers, 2002)\"",
"The Myers paper is \"",
"Myers, N. 2002. Environmental refugees: A growing phenomenon of the 21st Century. Phil. Trans. R. Soc. Lon. Biol. Sci. B 357: 609-613",
"\"",
"Reading that paper, I don't see much that looks incorrect so far as I know.",
"In fact, based on available evidence, I'd say it seems likely that there are quite plausibly 50 million people who might be termed 'climate refugees' under the above definition.",
"The Anthony Watts-sourced garbage makes a big deal about a couple of islands with a total population of less than 2 million people, but fails to mention the fact that the areas covered in that map contain ",
" of millions of people.",
"50 million people is about 3-5% of the population of China. Given that the map includes large, densely populated sections of Asia (including densely populated parts of China, India, and the Philippines), what on Earth makes you† think we'd necessarily be hearing about them? Especially when there are already hundreds of millions of internal migrants in countries, who not-infrequently live in a near-refugee state.",
"How much do you hear about the 1/3 of New Orleans population that didn't return post-Katrina, or the refugee-like conditions many of them lived in for ",
" after Katrina? This was ",
". It was a fairly major city. And yet, we still heard very little about it. And you expect us to hear about 50 million poor people scattered around the globe, whose existence is a statistical statement and are, individually, indistinguishable from the people they're surrounded by, among the 2+ billion poor people in the world?",
"†I say 'you', but I don't mean ",
" personally. That was a generic 'you'."
] |
[
"I would not describe the Katrina outflow as \"climate refugees,\"",
"I wouldn't either, and in fact, I wasn't (I thought I'd made this clear when I wrote the post, but re-reading it, I can see how perhaps I wasn't clear enough on this point). I cited them as an example of people in a major first world country, from a major city, who were reduced to, essentially, refugee status for years, in some cases perhaps lasting up until the present, and whom we didn't hear about after the first, roughly, year.",
"If, even in a case that hits this close to home, we stop hearing about them (even when it was initially a major news story) after such a small fraction of the time during which they were refugees, what on Earth makes someone think we'd hear about a somewhat-randomly-distributed 2.5% of the people living on less than the equivalent of $1/day? Especially when it's rarely possible to be able to attribute any ",
" refugee to climate change. We can say, statistically, that increases in the frequency, duration, and severity of droughts are a result of climate change, but we cannot say that one specific drought is because of climate change. The same is true of nearly every condition which could produce climate refugees."
] |
[
"I was more interested in what facts led them to come to this conclusion and what has changed since then? I'm asking out of genuine curiosity, not because I want to promote some sort of agenda. I remember that report in 2005 and I was worried, but by 2010 I had forgotten about it entirely."
] |
[
"How would the night sky look if we could see the whole electromagnetic spectrum"
] |
[
false
] |
This is sort of a question relating to how the night sky is dark and not full of light. If humans could see the full electromagnetic spectrum (or at least more than what we are able to see normally) what would the night sky look like? Or even how would the world appear to us? Although I am not sure this has been tested before but hopefully you guys can give me some answers :)
|
[
"Unfortunately our atmosphere is opaque to most frequencies that we can't see. There are notable exceptions (radio):\n",
"http://en.wikipedia.org/wiki/File:Atmospheric_electromagnetic_opacity.svg",
"Here's a hint at what things would look like from space:\n",
"http://www.armaghplanet.com/blog/image-of-the-month-andromeda-through-different-eyes.html"
] |
[
"Something like ",
"this",
"."
] |
[
"Please keep wild conjecture at a minimum"
] |
[
"Why does the polynomial x^5 - x + 1 = 0 have no exact solution?"
] |
[
false
] |
I just saw that mentioned the fact that this polynomial only has an approximate solution, not an exact one. However, when I rearrange the equation into x - 1 = -1/x and graph the two individual functions (you can use ), the "approximate" solution of -1.167... is where these two functions cross. Since they are both continuous, differentiable, and cross at this point, why is this only an approximate solution?
|
[
"This is actually a fascinating question, with an even more fascinating answer. First off, it is important to note that there is a real solution to that equation. There are also four other complex solutions that you would expect by the fundamental theorem of algebra. ",
"The real question here is, why can you only approximate the solution. First, off, let's note what tools we have to work with. We start with the rational numbers (fractions). The operations we can use are +,-,*,/, and radicals. But since we have all the rational numbers to use, we can ignore - and /.",
"Note that for linear equations, we don't even need radicals to solve them. We just need multiplication and addition. Let's look at a quadratic, x",
" - 4x + 2. This has roots 2 + sqrt(2), and 2 -sqrt(2). (Note the symmetry between the two). We can find the root easily with the quadratic formula. Isn't an easy formula for the cubic, but there is a straightforward process that always works. There is also one for quartics (degree 4). But once you get to degree 5, there are only special cases where you can express an exact solution using radicals. The reason why you can't is actually very elegant and brings together many different areas of math. It's called Galois Theory. ",
"I'll try to convince you that the roots of some polynomials are fundamentally different. So if you look at the quadratic example above, you can notice that the only irrational number we used was 2",
". If we augment the rationals with this number, we create a new set of numbers where we can solve that polynomial. In fact, this can be done for any polynomial by simply augmenting the rationals with certain numbers. It turns out that these augmented sets are something called a ",
".",
"Lets take another example, x",
" - 2 =0. Well, x",
" = 2",
", so the roots are +/- 2",
" and +/- ",
" 2",
". If we add ",
" and 2",
" to the rationals, we can make another field. Now picture these roots on the complex plane. The 4 roots lie on the x and y axes, like a baseball diamond. ",
"I hope someone gets to this because here's the coolest part. Imagine 4 people running around in a baseball diamond. Suppose you want to advance all the runners, just multiply all the roots by ",
". Let's say you want to swap home plate and second base, take the complex conjugate. You can also imagine a physical square that you can rotate and turn upside down. You can move the vertices but only in certain ways. What if you wanted to swap 1st and 2nd base and leave everything else the same? Well you're out of luck. There's no convenient operation that lets us do that. To contrast, you can have a polynomial (x",
" - 10x",
" +1) with roots sqrt(2) +/- sqrt(3) and -sqrt(2) +/- sqrt(3). In this case the only possible permutations are swapping any two pairs of roots. You can't do a rotation. ",
"So, how does this all relate to there not being a general solution to quintics? Well you can see that radicals can be organized in certain ways, and there will be symmetries that arise from how they are arranged. You can nest radicals inside each other in very complicated ways, but there are limited number of symmetry groups that can arise from this. In order to generally solve a degree n polynomial, you have to allow for all possible symmetries on n roots. This is called the symmetric group S",
". It is very large and contains n! elements. Once you get to S",
". It is \"too big. \" Radicals alone cannot express the full range of S",
". I hope that gives you some intuition as to what is going on. ",
"This was a very informal explanation, so feel free to ask me questions. ",
"*typo"
] |
[
"I think this stems from a misconception of what an \"exact solution\" is in this context. ",
"Does the equation x",
" - 2=0 have an exact solution, in your opinion ? ",
"You will probably answer : Well of course it does ! It's the square root of 2 !",
"But think about it, the square root of 2 is ",
" as the solution of this equation, isn't it ? So it seems that we are going in circles here ... We say that there is an exact solution to this equation, simply because we gave a name to that solution.",
"But actually, the square root of 2 is a irrational number. So one could argue that this is not an \"exact\" solution. For example, we cannot give its decimal expansion, or write it as a ratio of two integers. But the square root is a relatively simple function, so it's in our arsenal of \"elementary function\" because it is used everywhere. In a way, we consider that sqrt(2) is \"exact\" because we are used to it.",
"Now, let's talk about the interesting part. We define square roots as solutions to equations of the form x",
"-a = 0. Simply using square roots (and + , -, * / ) , we can also express the solutions of all quadratic equations, with the good old ",
"quadratic formula",
". ",
"We can also define cubic roots as solutions of equations x",
"-a = 0. And again, simply using square roots and cubic roots, we can express the solutions of any cubic equation, using the more complicated ",
"cubic formula",
"Same thing with quartic root, and ",
"quartic equations",
".",
"But when you arrive at degree 5, something strange happens. You can of course define fifth roots as solutions of the equations of the form x",
" - a = 0. But now, this becomes insufficient to express the solutions for ",
" quintic equations. This is exactly what the Abel-Ruffini theorem is saying.",
"It's basically saying that if you want to express the solutions to ",
" quintic equations, you need more than just square, cubic, quartic and quintic roots. Some equations have solutions that cannot be written only with these things (like the one you gave in the title). You actually need to use a ",
"Bring radical",
", which is a function defined almost exactly as the fifth root except that it's the solution to the equation x",
" +x + a = 0.",
"And so you can get the \"exact\" solution to any quintic equation, by using usual roots and Bring radicals.",
"Going in degree 6 and higher, you will need even more additional building blocks to express solutions."
] |
[
"The solution is definitely an algebraic number but it is not an \"algebraic solution\" in the sense of having a closed form algebraic expression. The alternative terminology that I see in other discussions of the Abel-Ruffini theorem is \"expressible in radicals\" etc. which to me is a little more clear in its distinction from whether the solution is an algebraic number."
] |
[
"If we know what kind of bacteria causes the majority of cavities, why don't we just make an antibiotic that targets them and distribute it like a vaccine at a doctor's office?"
] |
[
false
] |
[deleted]
|
[
"Antibiotics that target a specific bacterium are tricky. There are a small handful that have been demonstrated, but very few, and only for research purposes. Even then, it's more of a \"kills bacteria x very efficiently, while y and z will mostly survive\" deal.",
"The reason is, simply, how targeting can be done. You basically pick a trait or property of that bacterium - for instance, it has a lot of receptors for a specific sugar molecule, or the cell wall is negatively charged, or something. You target that property, by for instance attaching the respective sugar to a drug molecule, and hoping that most of the dose gets taken up by your target. Some will be uptake by other cells though, as there is almost never a completely unique expression or trait.",
"Also, most of these types of drugs are too expensive, and not specific enough, to be commercially feasible.\nThus the various broad spectrum antibiotics, and the range of somewhat specific antibiotics that each address a niche family or group of bacteria.",
"Beyond that, antibiotic resistance is a huge problem with overuse. Basically, let's say your antibiotic is super effective, kills 99.9999% of the target bacteria. The remaining 0.0001% is the group that was more resistant, for whatever reason. That is the group that also starts to become dominant, as we kill off the less resistant ones. Eventually, your antibiotic is no longer effective for that bacteria!",
"This is why we have had to formulate so many modified versions of penicillin, to keep coming up with something new that still works.",
"Generally speaking, it is best to limit antibiotic use to cases where it is really necessary. While you can certainly argue for it's use against cavities, it would not be a one time (or sporadic) thing like vaccinations but a regular treatment, like mouth wash. That sort of high volume, high frequency usage would give us dental versions of something like MRSA very quickly! "
] |
[
"/u/rlgl",
" answered the question \"why don't we just make an antibiotic that targets them?\"",
"The kind of bacteria believed to cause ",
" of cavities is ",
"mutans Streptococci",
", but they don't cause ",
" cavities. There are also some respected researchers that think the role of mutans streptococci in cavities has been exaggerated by old research methods. So, even if we could kill all mutans streptococci with some kind of drug that doesn't exist yet, the other bacteria that can cause cavities would move in and take the place of the mutans streptococci.",
"To make matters worse, bacteria on teeth live in biofilms that are naturally resistant to antibiotics and physically difficult to remove. Even if the magic antibiotic is very effective, you might have to take it for months in order to get to all the bacteria deep down in old biofilms. Then you kiss your grandma and ",
" you're colonized with mutans again because over 50% of the population has it in their mouth all the time."
] |
[
"That might work. Maybe. But that branch is still new, and bacteria can become resistant to phages just as much as to antibiotics. Again, sort off."
] |
[
"Why do astronauts breathe 100% oxygen?"
] |
[
false
] |
In the Apollo 11 documentary it is mentioned at some point that astronauts wore space suits which had 100% oxygen pumped in them, but the space shuttle was pressurized with a mixture of 60% oxygen and 40% nitrogen. Since our atmosphere is also a mixture of these two gases, why are astronauts required to have 100-percent oxygen?
|
[
"It's actually not a biology reason but an engineering one. Humans can breath pretty much ok as long as the oxygen pressure is around what we are used to. For example at 1 atmosphere of pressure we have about 20% oxygen in air. The trick you can do it lower the pressure and increase the oxygen content and people will still be fine. With pure oxygen you can comfortably live with only 30% of sea level pressure. This is useful in spacecraft because lower pressures mean lighter weight systems. ",
"For Apollo (and Gemini and Mercury before them) the idea was to start on the ground with 100% oxygen at slightly higher pressure than 1 atmosphere to make sure seals were properly sealing. Then as the capsule rose into lower pressure air the internal pressure would be decreased until it reached 0.3 atmosphere once in space. However pure oxygen at high pressure will make a lot of things very flammable which was underestimated by NASA. During a ground test a fire broke out and the 3 astronauts of Apollo 1 died burned alive in the capsule.",
"At lower pressures this fire risk is less of an issue but now pure oxygen atmospheres have been abandoned in most area of spaceflight. The only use case is into spacesuits made for outside activities. Those are very hard to move into because they basically act like giant pressurized balloons. To help with that they are using low pressure pure oxygen.",
"EDIT: ",
"u/aerorich",
" has",
" good info here on how various US spacecraft handle this."
] |
[
"Very interesting, thank you for the great answer!"
] |
[
"Great answer by ",
"u/electric_ionland",
", I'd also like to point out that by using one gas, you only need one gas tank, not two. You don't need complicated mixing/regulating hardware to mix in nitrogen for breathing either. Saves weight and complexity. Apollo continued using pure oxygen, even after Apollo 1. Source: ",
"https://www.popsci.com/why-did-nasa-still-use-pure-oxygen-after-apollo-1-fire/"
] |
[
"How far from the coast must one go inland for ground water to be drinkable (not saltwater)?"
] |
[
false
] |
So I'm watching HBO's "Rome" and there's an episode where the protagonists are stranded on an atoll/small island without water. It made me curious if there's a minimum distance from the coastline/radius of an island that would make water from the ground drinkable and not too much like salt water to be harmful. Is there a point at which the ground filters the water enough to be safe? Would it be too far inland to be practical to dig?
|
[
"Groundwater can actually be fairly unintuitive, but one possibly illustration of the situation is ",
"here",
". In this case, you could dig for water basically anywhere on the island, and find some fresh water. For any given island, the shape of that freshwater bulb under the island will be controlled by a number of factors, like the hydraulic conductivity of the soil, the presence or absence of aquifers in the rock under the island, the amount of precipitation the island receives, and the state of surface conditions controlling how much rain infiltrates into the soil to become groundwater in the first place, instead of becoming surface runoff.",
"Really, without studying the specific island in question, there's no reasonable way of answering the question with much accuracy. "
] |
[
"Excessive pumping of limited freshwater supplies will cause saltwater intrusion. The salt flows in to replace the vanishing fresh.",
"This means places that have been lived in for a while near the ocean get progressively worse. "
] |
[
"I'm definitely not an expert on the topic, but your question reminded me of the existence of submarine springs. These are freshwater springs that emerge off the coastline in saltwater. I seem to recall hearing that ships would sometimes use these springs to replenish their supplies, the difference in density making it possible to raise a bucket of fresh water out of sea water. ",
"In any case, ",
"here",
" is a page from the U.S. Geological Survey containing a picture showing the Floridian aquifer system and how a submarine spring might be tied in. This would seem to suggest that there is no general minimum distance inland to reach freshwater and that the locations of water are more dependent on local geology."
] |
[
"Years are ~365.2564 days long. We have leap year, but are we accounting for that .0064 at all?"
] |
[
false
] | null |
[
"The rule for leap years is actually quite complicated. A year is a leap year if 1) it's divisible by 4 (e.g. 2012 is a leap year), 2) it's not divisible by 100 (2100 won't be a leap year) or 3) it's divisible by 400 (2000 was a leap year).",
"In the end, it's more precise than 365.25 and we have several thousands years before we need to correct it."
] |
[
"Fun fact: We had a leap second earlier this year which practically broke the internet. "
] |
[
"There is also the ",
"http://en.wikipedia.org/wiki/Leap_second",
" of which there have been 25 since 1972 which are used to keep time-of-day in sync with the earth's (surprisingly very slightly irregular) rotation."
] |
[
"What is the average density of the universe, or in the case of an expanding universe, an equation for the average density?"
] |
[
false
] |
Finite amount of matter / Size of universe. Lets break out the scientific notation! Feel free to stray from kg/L if it makes things easily :)
|
[
"First, there is no reason to suppose that either the amount of matter or the universe is finite.",
"That said, the density of the universe appears to be around ",
"10",
" g/cm",
"."
] |
[
"Thanks for the response! Do you care to elaborate on any assumptions or estimates this number caries with it? The reason I ask is because of the preface you gave before answering. Thanks!"
] |
[
"As a mathematician, I would like to point out that there are perfectly reasonable ways to deal with this using measure and coarse geometry. In the limit, large balls in ",
" are half even. Similarly, in the limit, large balls in the universe have average density 10",
" g/cm",
" as stated."
] |
[
"Why is it that when walking down a busy street with earphones in..."
] |
[
false
] |
Whenever I walk down a city street with headphones in, and a very loud sustained external noise is happening (say a bus or truck starting to move at a green light, or whatever), you can turn the music all the way up and it doesn't hurt your ears (even though you still can't hear it) but as soon as the truck or bus pulls away and it gets quite again your headphones (still at their highest setting) all of a sudden become deafeningly loud and hurt your ears?
|
[
"In music production, we have something called ",
"Dynamic Range Compression",
". What it does is essentially taper off the loudness of a sound after a certain point. In other words, it applies a rule like \"any loudness above 6db will be cut in half, such that each decibel you add to the input only adds half a decibel to the output\". To put it one final way, any loudness past a certain thresh hold is \"squeezed down\", so that it doesn't exceed that thresh hold by quite so much.",
"Why is this relevant? Because you have a system like this embedded in your ear to begin with. So when the noise you hear becomes too loud, your ear responds by lowering the overall perceived level. There's a description of the specific biological happenings ",
"here",
", paragraph 2.",
"Another thing that's worth noting about dynamics compression (if you're not familiar with music terminology btw, 'dynamics' basically means 'volume level') is that it's not instant, it takes a moment to \"kick in\". So your ear will respond to a continuous noise like a loud guitar better than it will to an intermittent noise, like somebody hitting a snare drum really loud every 10 seconds. Your ear adjusts to the guitar, but it can't adjust to the snare. This isn't 100% relevant, but it's interesting to know.",
"So you see where this is going. When the truck drives by, your ears enter their defensive crouch, bracing themselves for the loud noise. Once it's gone, your ears relax and you're back to hearing things at normal volume.",
"At this point you may think \"well why doesn't my music being so damned loud keep my ears in defensive crouch mode?\". ",
"Well, your ears are still compressing some, but the overall volume is way less than when the truck was there, so you'll get less compression. The trick is that the sounds you're hearing have a lot more mid and treble in them, which are way more obnoxious frequency ranges to the human ear. So even though the overall level is quieter in absolute volume, the volume has shifted into these more painful ranges while the compression has relaxed. So while the overall level has decreased, the mid and treble levels have actually increased, and you get ear pain."
] |
[
"Wow, this is awesome. Thank you."
] |
[
"It could also have to do with the two tiny intrinsic middle ear muscles: tensor tympani and stapedius dampening the truck noise and then relaxing making the music blare. This is just a guess. "
] |
[
"Why are solar panels glossy? Isn't the goal to absorb light and not reflect it?"
] |
[
false
] | null |
[
"A surface being glossy instead of matte doesn't change the total amount of reflected light very much. Solar panels actually only reflect a tiny fraction of the incoming light, about 1-4% depending on the coating. The sun is so bright that it's enough to notice, but a vast majority of the energy is actually being absorbed."
] |
[
"The cells themselves are usually matte in appearance, but they're also fairly fragile. That means that usually, manufacturers try to find something protective to put over the cells-- but it needs to be simultaneously sturdy, cheap, and very transparent. So there's typically a layer of glass over the top. ",
"Since physics is mean, and nothing is ever perfect... even very good glass with multi-layered optical coatings to reduce reflection will still reflect a little of the light, and appear glossy. Better than having the panels all die in a storm, though... they last for multiple decades, which is long enough to almost guarantee they'll see at least one hailstorm in their lifetimes."
] |
[
"A matte surface scatters light, meaning it would be less than great with all incident angles of light. With a smooth surface, most light is allowed to pass through. ",
"Compare it to a pane of clear glass versus a frosted glass for a shower door. Most of the light can pass straight through clear glass, but the frosted - matte - finish scatters light as it passes."
] |
[
"How are memories formed and stored in the human brain? How does information go from \"pattern of electrochemical activity\" to \"hard\" storage?"
] |
[
false
] |
I've heard that memories are solidified during sleep: does this mean that information is sitting in "RAM", so to speak, until then? And is this why we get tired? Are there specific structures that contain memories, or are they distributed throughout our neural net? A combination? Can we detect changes as memories are formed using an MRI or other instruments?
|
[
"There are multiple views on the answer to this question.",
"First off, memory Is also consolidated while awake, but sleep does have a significant effect, especially on episodic and semantic memory.",
"As for your specific structure question, there is an ongoing debate between the sparseness hypothesis and the distributed hypothesis on how memories are stored. Put simply, the sparseness hypothesis states that certain cells, or groups of cells, fire in response to certain stimuli (2). The most extreme finding in this line of research is probably the ‘discovery’ of a “Halle Berry” neuron in a person, which fired only when the stimulus was a picture of Halle Berry. ",
"However these findings seem to be exceptional, and most researchers tend to believe that memory is stored in distributed networks. This hypothesis states that the memory of a stimulus is stored in a pattern of firing over a group of neurons. In this sense there is not much difference between ‘hard’ storage and electrochemical activity. There are factors that can moderate the firing rates of individual neurons, such as attention and Long Term Potentiation (1) (3).",
"Higher level theories try to explain the consequences of these theories. The most dominant position nowadays is that information on a stimulus/event is stored by taking into account it’s relation with other stimuli/events (network and association models). Here too, there is discussion about whether the basis of this categorisation is abstract/prototypical or on basis of concrete examples. ",
"http://jn.physiology.org/content/95/2/1078",
"\nArticle showing that individual neuron activity can be moderated by attention ( a high level factor)",
"Quian Quiroga, R., et al. (2007) Decoding vidual inputs from multiple neurons in the human temporal lobe J. Neurophysiol. 98: 1997-2007.\nArticle reporting neurons in the visual area of the brain that fire for very specific stimuli.",
"http://www.jneurosci.org/content/34/14/4801",
"\nArticle on long term potentiation in the hippocampus. Interesting because it describes cellular and resulting behavioral changes in mice."
] |
[
"There's a phenomenon in the brain called ",
"Long Term Potentiation",
" which essentially causes synapses in the brain to fire more easily when they are used frequently. There's some speculation that part of how memory works is from LTP. This is due to the fact that the hippocampus (a structure associated with memories) \"replays\" synaptic patterns that occurred during the day while you are sleeping ",
"[source]",
". Hippocampal replay and LTP are thought to contribute to the reinforcement of certain \"circuits\" of synapses used - causing patterns of electrochemical activity to be more likely to occur again if they frequently occur. ",
"[link]",
".",
"Your brain doesn't really undergo any major structural changes during learning or memory so science thinks currently that memory may come from changes to synaptic strengths through LTP. Though really much of science is uncertain to what extent it contributes.",
"Edit: Please someone correct me if I'm mistaken - its been over a year since taking neuroscience in University."
] |
[
"We really aren't very close to knowing how memories are formed or represented in the brain. We can't really observe the scale at which memories are formed, possibly in large part due to the gaps in resolution of the techniques we have for detecting brain activity. ",
"We can measure activity of 10s or 100s of neurons (albeit probably not in a human) using probes, and we can measure activity (or something like activity) of millions of neurons using neuroimaging techniques like EEG and fMRI. It seems that memories are stored diffusely across the brain, and we really don't have a technique that can pick up activity at very fine spatial resolution across the entire brain."
] |
[
"With a big enough optical telescope could the human eye perceive an \"astronomy picture of the day\" deep space object in full technicolor glory?"
] |
[
false
] |
With a big enough optical telescope (on earth or in space) what would a human see when looking at an object like I understand at a superficial level how astrophotography works (collecting photons over time, lucky imaging etc.) but I'm curious what the upper limit would be for someone looking through a telescope could see. If (say) a human was looking through a 10m telescope, could they see delicate colors and structures?
|
[
"Those are not \"real\" colors. Several images are taken with different filters with only allow specific wavelengths, which are then combined and colorized with a computer. ",
"Here you can see the data for the picture",
" and the Hubble website has a ",
"very nice interactive tool",
" which does a better job explaining how the filters and colors work than anything I could type here."
] |
[
"You can definitely see some colors. The ",
"Orion Nebula",
" can be seen as clearly blue through even a small telescope in the 8-inch range. One can discriminate between redder and bluer objects in many cases. If you put an eyepiece on a 2.4-meter telescope, your eye would probably be able to tell that the middle of that field was blue and the outer parts redder. But you wouldn't see it in such high resolution (since that's Hubble).",
"A lot of the false-color images also use narrow-band filters which pick out specific emission lines such as H-alpha or OIII.",
"One thing I like to remind people is that color itself is just a human perception, and we really can't see the full spectrum in its true glory. So if the images from APOD and elsewhere are more colorful than what we'd see, in one sense it's because telescope filters are better at discriminating between wavelengths than the human retina is."
] |
[
"The problem is not merely a lack of light-gathering power (although that does contribute, since our color-sensitive cones are not as sensitive to faint light as the monochromatic rods are), it's the way that the human retina sees color. ",
"Cone cells have three different wavebands which they can detect in",
", and these wavebands overlap significantly. Objects with a continuous spectrum are pretty much fated to appear to us as being somewhere on a spectrum of red/white/blue.",
"Compare the retina's response function to the ",
"Bessel Filters",
", or better yet the ",
"Hubble WFC3 filters",
" or the ",
"Sloan Digital Sky Survey filters",
"and you'll see a key difference-- the astronomical filters only start overlapping where both their responses are down to 50% or so, giving much better wavelength discrimination (also, having more filters helps dramatically). Different filters don't really impinge on each others' wavelength territory much either. Human retinas also lack ",
"narrow-band filters",
" to detect spectral line emission, which is responsible for most of the colors you see in images of nebulae.",
"Frankly, if billionaires want to see with all the colors of space, they'd be better off investing in some ",
"bionic eyes",
" and then looking through a telescope."
] |
[
"What is and isn't possible with a DDoS attack and counter-attack?"
] |
[
false
] |
got me curious. I understand the basics of a DDoS attack, and what it is, but I have no knowledge of details and what is/isn't possible. Could Anon have actually done anything, or are they full of baloney?
|
[
"For curious people in this thread, here's a quick intro to denial-of-service attacks.",
"Denial-of-service (DoS) attacks are attacks intending to exhaust targets of some resource. For example, on many Unix machines, running the infamous shell one-liner ",
":(){:|:&};:",
" will cause the system to lock up; the command asks the shell to create a process which has the single task of making more copies of itself - the system promptly runs out of PIDs.",
"Distributed denial-of-service attacks (DDoS) are DoS attacks performed by multiple attackers. For example, the classic SYN flood is one such attack. When computers initiate a TCP connection, the client sends a SYN packet; in response, the host sends a SYN/ACK packet; when received, the client sends one final ACK packet to initiate the connection. In a SYN flood, multiple computers send SYN packets to a target machine, which sends back SYN/ACK packets, which are never responded to. The target, quickly enough, can't keep up with all incoming requests, and will start to bounce legitimate traffic.",
"DoS attacks are versatile. One fascinating approach is to spoof a return IP address and do a DNS lookup; for sending a handful of bytes out, the DNS server will dump kilobytes of data on your target. There's a whole wide world of ways to DoS someone.",
"DDoS attacks are often facilitated by botnets; thousands of machines controlled by a command-and-control (CnC) server, often over IRC. ",
" Depending on how the Lizard Squad structured their attack, Anonymous could have been responsible for ending it. I wouldn't put it past them to take credit where credit isn't due, but I wouldn't say they aren't responsible either."
] |
[
"Thanks, this is much more helpful."
] |
[
"Yes it is possible.\nBy flooding a certain ISP's backbone with another DDoS attack, you can cause the current DDoS attack to be rerouted. ",
"An example...\nSay Person A is DDoSing a server in the US. Person A is renting a Russian Bot-Net. The Bot-Net is primarily European. There are only a few interconnects between NA and Europe. Person A's traffic is going through Link A but is not saturating the link.",
"Person B wants to redirect the traffic from Link A to Link B. Person B also has a Bot-Net. Person B can then flood many different points along the line to cause some of the traffic from the first attack to take a different route.",
"This in general something cyber terrorists can do. The internet is built of pipes. If you fill one, it goes to the next one. If you know what you are doing you can redirect an attack given that you have enough resources."
] |
[
"Interesting little experimental probability vs theoretical question that occurred to me."
] |
[
false
] |
While I was flipping a coin to decide between Beef-Broccoli and Beef-Fried Rice, when a question occurred to me.(I know it's technically more of a mathematical question) I know that the more trials you do in probability experiments, the closer your experimental probability gets to equaling your theoretical probability. But my question about that is this: wouldn't it take less trials if your theoretical probability was closer to 0% or 100%. So following this reasoning, would it take the MOST trials in a 50/50 thing for your experimental to equal your theoretical?
|
[
"Your question setup is a not very clear. You're basically talking about building a binomial or an approximation of a normal distribution. But I don't see why things are 0% or 100%. There is no such thing as \"most\" trials. You can keep going and flip that coin forever.",
"Can you clarify what you mean?"
] |
[
"I've gotta run (literally, it's time for my run), but I threw this together with a quick Matlab script to show you how the probability converges to its expected result for a fair coin (p = 0.5) and an unfair coin (p = 0.9).",
"Link",
"The top plot is the running average of each coin. The bottom plot is the difference between the expected probability and the running average. Where the bottom plot \"bottoms out\" is where those two numbers matched and the plotted number should have been zero, which won't show up on a log plot.",
"If you have any questions just ask and I'll get to them when I get back."
] |
[
"yeah that was pretty unclear....I'll just explain with an example. Say you're flipping a coin, obviously there's a theoretical 50 percent chance of it landing on heads. However, in an actualy experiment, if you only flip the coin 5 times, it may turn out that heads only came up 30% of the time instead of fifty. I was told that the more times you flip the coin (the more trials), the closer your experimental results will get to matching up with your theoretical probability. I.E. if you flip the coin five million times, you may get heads 48.9% of the time, and if you do it five trillion times, you may get head 49.999% of the time, etc...",
"So my question was, this: say it took you 500 tries to get the heads exactly 50% of the time; wouldn't it take less tries to match a smaller OR larger theoretical percentage? In other words, in terms of how many experimental trials it's going to take to match a theoretical probability, 50% is the worst possible theoretical to use. ",
": t = |50-theoretical|",
" are absolute value signs by the way, and t is just a random variable i picked. ",
"The smaller t is, the more trials (flips of the coins or what have you) it's going to take to match the theoretical probability. Is this true? ",
"sorry, that was not at all concise...."
] |
[
"How can yeast produce THC?"
] |
[
false
] |
I recently came across article and was curious. How is this possible. Can yeast be made to produce any chemical compound?
|
[
"Disclosure: I know one of the members of the company profiled, though we've never talked about this work.",
"This is done by introducing biosynthetic enzymes into a yeast. If the pathway that a plant uses to make the compound is known, you can clone the genes, insert them into the yeast, and then make sure they have the appropriate conditions to grow and produce the compound. ",
"You need to make sure the metabolic pathway you're using takes take a metabolite that yeast normally have (eg. glucose, amino acids). You also have to go through a lot of steps to optimize the conditions, because the introduction of a new metabolic pathway can be disruptive and make the yeast sick. So sometimes you will also have to figure out ways to compensate for the new metabolic burden you've put on the yeast. ",
"This has already been shown to work for the antimalarial ",
"artemisinin",
" and some ",
"opiods",
", there's no reason to think that THC would be too much different.",
"Edit: grammar"
] |
[
"yeast and E. coli are by far the most heavily utilized organisms for engineering - theoretically, with the right enzymes, any compound can be produced metabolically by the organism. The difficulty lies in finding the correct combination and sequencing of said enzymes to achieve the desired product. Many companies are already producing engineered strains of yeast and E. coli to make everything from diesel fuel to anti-malarial drugs - so to answer your question, theoretically yes, practically no. It's one thing for a process to be possible, it's entirely another thing for it to be cost-effective on a manufacturing scale. That will always be the final concern - and in biology, scale-up of a laboratory experiment is never a simple as building a bigger tank."
] |
[
"I too love the gene gun because of its simplicity but check out crisper."
] |
[
"Could you use liquid nitrogen to clean up an oil spill?"
] |
[
false
] | null |
[
"Chemistry major. Nope, the ocean's temperature is generally warm and really hard to change, so the cost would be enormous! Also, you can't just drop it from a chopper, because it would evaporate into the air. "
] |
[
"It might freeze some parts of the oil, though I don't really see how it fixes the problem. It still has to be removed. "
] |
[
"It might freeze some parts of the oil, though I don't really see how it fixes the problem. It still has to be removed. "
] |
[
"why do some people sweat more than others? does sweating a lot or a little have any pros/cons to one's health?"
] |
[
false
] | null |
[
"Sweating is a means to lower your core body temperature. Sweat is mostly water, but contains some minerals and urea. You sweat when you work out because the exertion causes heat, and your body attempts to normalize it's core temperature by shedding warm water. As sweat appears at the surface of your skin, it begins to evaporate which cools your skin temperature as well.",
"If you're a heavier person, you may sweat more as you are better insulated, and the body has to work harder to maintain it's temperature.",
"Sweating is also a common response to nervousness and stress. You can tell the difference by how you're sweating. If it's just your palms, armpits, and forehead, it's probably stress related. If it's everywhere, it's probably heat related."
] |
[
"Speaking from a biological standpoint the more diverse a species is the more likely is it able to adapt and survive in a changing environment. ",
"Imagine a case where people who are able to sweat more may have an easier time surviving in very hot conditions because they can lower body temperature faster than those who don't. ",
"On the flip side those who don't sweat as much may be at another advantage because they can conserve water in their bodies and are less likely to become dehydrated if water is not abundant. ",
"There is no overall goal that evolution gravitates to. Different versions of the same trait (heavy sweater vs light sweater) in a species might give the species an advantage in a particular circumstance that increases the overall survival of the species. ",
"Hence I don't think it matters if you sweat more or less. Sure you might have to change more shirts (I know I do) but these days technology and deodorant have made the effects of these differences pretty benign. "
] |
[
"As a heavy sweater please answer this."
] |
[
"Is it possible to make an alpha particle gun?"
] |
[
false
] |
[deleted]
|
[
"so would it be possible to create an alpha particle-emitting device that could disrupt things like computers?",
"Easily. Just buy 10,000 smoke detectors, extract the Americium-241 from each, and put the result in a shielded container with a controllable port. I emphasize that I'm not actually recommending this.",
"Also, I understand there are precautionary steps to correct bit flips but what if the alpha particle (or enough alpha particles) prevented this from happening?",
"Obviously a sufficiently high alpha radiation level would overwhelm any error-correction methods in place. Most error-correction methods have well-defined limitations -- they can correct a one-bit error, or a two-bit error, but not more than that. So if the interference level is high enough, all such methods will fail."
] |
[
"to follow on here, alpha particles are practically trivially stopped by any material. They can only travel a few cm in air, and get stopped by paper, tissue paper even."
] |
[
"I was only wondering if it was possible or previously attempted.",
"It has been -- ",
"David Hahn",
", the so-called \"Nuclear Boy Scout\", did it pretty much as I described above."
] |
[
"Is there a means to recover astronauts during spacewalk accidents?"
] |
[
false
] |
During extra-vehicler-activity is there a real risk of an astronaut becoming stranded/seperated from the space station?
|
[
"NASA astronauts on ISS always maintain some sort of tether to the station",
"Though note that in the past there have been some ",
"untethered spacewalks"
] |
[
"The risk is extremely low. NASA astronauts on ISS always maintain some sort of tether to the station to prevent that from happening. Additionally, they always wear the SAFER equipment on their EVA suits. This is a small set of thrusters which would allow them to return to the station even if for some reason their tether failed and they drifted away."
] |
[
"Well there is a risk, but the astronauts' space suits include an emergency jetpack called ",
"SAFER",
" that they could use to rescue themselves. It's based on the older ",
"Manned Maneuvering Unit",
", used during the Shuttle era, which was more of a general-purpose device for flying out away from the Shuttle to help capture satellites.",
"The MMU was first tested on the Skylab space station, along with a few other concepts, but I just learned there was an even earlier concept that was supposed to have been tested ",
"on the Gemini 9 flight",
" but they couldn't get it to work. So thanks for the question because I learned something too!"
] |
[
"If the earth was placed at the border of our universe (some planet must have ended up there?). Will half of the sky be completely black?"
] |
[
false
] |
Or what will we see or be able to measure from the other side?
|
[
"The observable universe — which is often what people mean when they say \"the universe,\" and that ambiguity of terminology causes a lot of confusion — is simply a sphere centered wherever the observer in question happens to be. The radius of the sphere is a function of the age of the universe. Every point that lies within the sphere is sufficiently close to the observer that light has had time to reach the observer from that point in the time that the universe has existed.",
"So if you could magically teleport yourself (and your telescope, of course) to a point at the very edge of the observable universe as seen from Earth, you would find yourself at the center of a sphere of stars and galaxies that looks entirely similar to what we see all around us. You'd be seeing stars and galaxies that no human has ever seen before, because light hasn't had time to reach us from those stars and galaxies since the beginning of the Big Bang, but other than that, there'd be nothing particularly interesting about your view.",
"This raises the obvious question: If light cannot yet have reached us from those places, how can we know what you'd find there? Well, the honest answer is we don't. Not for sure. But it follows logically from the assumption that the laws of physics are the same everywhere. The technical term for this is ",
" Wherever you go, the same basic laws of physics apply.",
"The reason we have stars and galaxies ",
" is because the laws of physics caused them to form out of the soup of matter that emerged from the early stages of the Big Bang. Those same laws of physics apply ",
" so it follows naturally and inevitably that there will also be stars and galaxies wherever you go.",
"Of course, it's technically possible that the laws of physics are ",
" the same everywhere. But in many centuries of people observing the universe on scales both large and small, there's never yet been any evidence at all that the laws of physics aren't translationally invariant. So while it's an assumption, it seems to be a pretty darned safe assumption to make."
] |
[
"There's no answer in that case. There is no border of the universe."
] |
[
"Yes, there's copious data. Let me see if I can put it in terms that don't make you want to set yourself on fire. Apologies in advance if this ends up being too elementary for you.",
"There's this phenomenon called cosmic microwave background radiation. As the name implies, it's microwave radiation, and as the name also implies, it's a sort of background noise. If you have the proper kind of antenna to pick it up, and you point that antenna at ",
" part of the sky, you find the same frequency distribution and average intensity of radiation coming at you.",
"It was something of a mystery when it was first discovered. A couple guys at Bell Labs named Wilson and Penzias were doing something wholly unrelated to astronomy using a particularly sensitive radio antenna. In order to get good data from their experiment, they needed to eliminate ",
" sources of noise. Except they found they couldn't. No matter which way they oriented their antenna, they picked up a sort of low-intensity microwave \"hiss.\"",
"Unknown to Penzias and Wilson, it had been predicted some twenty years earlier that the universe might be filled with a low-intensity background radiation that was emitted during the early stages of the Big Bang. At that time, some astrophysicists were getting ready to search the sky to see if they could detect this background radiation … only to discover that the guys at Bell Labs had already found it.",
"(If you want to think of the cosmic microwave background as being the light that came into being when God said \"Let there be light,\" you won't be too far off, really.)",
"We flash forward now to the end of the 20th century. A lot of detailed observations of the cosmic microwave background had been made, and preparations were underway to launch a space probe beyond the moon to study it very closely. The idea was to look at the whole sky, a tiny patch of it at a time, and measure the intensity of the cosmic microwave background coming from the direction of that patch of sky. It was believed at the time — and this turned out to be true — that mapping the ",
" of the cosmic microwave background — that is, the way the radiation varied in intensity depending on which direction you looked — could tell us a lot about the early universe, as well as the geometry of the universe as it exists today.",
"That space probe, which was originally called Explorer 80 but was later renamed the Wilkinson Microwave Anisotropy Probe after a cosmologist who passed away, collected data for seven years. Every year or so, the data was collected and subjected to intense scrutiny. The more data that got collected, the more the picture of the cosmic microwave background came into focus.",
"What we found — and this really only happened in the past five years or so — is that the cosmic microwave background is ",
" uniform. Like astonishingly uniform. If you modeled the cosmic microwave background as a bowling ball, with little bumps on the surface to represent \"hot spots\" of higher intensity and little depressions on the surface to represent areas of lesser intensity, the distance between the highest and lowest points on the bowling ball would be smaller than the diameter of a virus particle. It's ",
" uniform.",
"This raised about as many questions as it answered. How could the universe have been in thermal equilibrium three hundred thousand years after the Big Bang started? At that time, the universe was expanding — that is, all distances were increasing with time. Points that now lie on the opposite sides of our observable universe should've been so far apart at that time that they ",
" have been in thermal equilibrium, due to the finite speed of light. It just didn't make any sense.",
"Well, of course, it does make sense. It just requires that we change our model of the evolution of the universe. It's now believed that instead of expanding gradually, at a more or less steady pace, the early universe expanded ",
" rapidly for a very brief time. Because all distances were much smaller before this period of ",
" as it's called, it was possible for the entirety of what is now the observable universe to have reached thermal equilibrium. So when matter and electromagnetic radiation decoupled some three hundred thousand years later, and the light we now call the cosmic microwave background was emitted, it was emitted from a soup of matter and energy that was of a uniform temperature throughout. Or so nearly uniform that the total variation in the light was extremely small. That's what makes the cosmic microwave background look so very close to uniform to us now … and it also explains why the universe looks homogenous and isotropic in all other respects as well, with matter and energy being evenly distributed through the whole volume of the observable universe and all.",
"So the upshot was that these observations of the cosmic microwave background were consistent with a universe that's ",
" less dense now than it was once thought to be, and ",
" more dense in the past than it was once thought to be. The more we observe — and there's a new space probe called Planck out there right now, collecting more data — the more our observations converge toward the predictions of a model of the universe that's infinite in extent, spatially flat and that underwent a brief period of inflationary expansion early in its history. This is ",
" different from the \"finite but unbounded\" model that prevailed during most of the 20th century, which in turn was very different from the \"steady state\" model that prevailed before that.",
"Science, as they say, marches on."
] |
[
"If you were tumbling in space and closed your eyes, would you still experience the sensation of tumbling/dizziness?"
] |
[
false
] |
If you are experiencing microgravity, and are lacking a visual frame of reference, would your body have enough (for lack of a better word) context to realize that it's tumbling? Would you feel dizzy? Would the small amount of gravity present be enough to trigger some sort of up/down frame of reference? What would be happening in your inner ear?
|
[
"I suspect the answer is yes because there is still an angular momentum imparted on your body. For instance, if you swung a ball around attached by a cord and then let go of the cord don't you expect the ball to move away from you?",
"So as you tumble the fluids in your ears would still want to keep at rest which means they would be pinged against one side of whatever cavity they were from.",
"It'd be different than if you were in gravity since as you tumble through gravity your fluids are constantly getting pulled in different directions but I suspect you'd still feel off even in space."
] |
[
"Yes. The previous poster is correct. It has nothing to do with gravity and everything to do with the conservation of angular momentum. Inside of the petrous portion of your temporal bone (a very bony portion of your skull) are three circular canals, unoriginally named \"the semicircular canals\" (known from now on as SCCs). These canals are filled with fluid and fine hair-like projections that sense the motion of the fluid within them. The reason you have three canals is because they are oriented orthogonally to each other to detect rotation in each of the three spatial dimensions. When the body (more specifically the head) rotates, the fluid in these canals remains at rest momentarily before accelerating due to the friction that exists between it and the walls of these canals. This acceleration of the fluid bends the tiny hair-like projections that line these canals, which fires off a nervous signal to to your brain that can roughly be interpreted as \"hey we're rotating in this direction\". ",
"It's an exquisitely sensitive system and has more importance than immediately meets the eye. For instance, as you read this sentence, try swiveling your head up/down and side-to-side. Notice how your eyes remain focused on the text? This is because their is a reflex-like pathway that connects the signals from the SCCs (more specifically the entire vestibular system of the inner ear) to the cranial nerves that control the movement of the eye. This reflex is so essential to our interaction with the environment, that it is impossible to ignore. Indeed, should you close your eyes and try rotating your head, you'll notice your eyes still remain fixed and midline even if you aren't looking at anything. ",
"But back to the original question. Or sensation of rotation, or tumbling, occurs when the fluid in the SCCs begins to move due to our heads rotation. Feeling dizzy, which can be better defined as perceiving rotation when your body is in fact at rest, occurs when the fluid in the SCCs continues to rotate after the body has stopped moving. In much the same way that hot-coffee will continue to rotate after you have stopped stirring it, the inertia of the fluid in the SCCs will cause it to continue to flow through the SCCs after you have stopped moving. This is why there is a palpable delay in the spinning sensation you experience on a merry-go-round. You get on, perceive an initial increase in rotation, reach an equilibrium point where you no longer feel you are rotating, then become dizzy once the merry-go-round has stopped. In space it would work much the same way. As you began to rotate due to an external force you would become very dizzy, but assuming your rotation reached a steady velocity, you would eventually stop feeling dizzy. You would continue to feel the outward force caused by your bodies inertia as it rotates (much as you feel the mass of an object youre rotating on a string as it pulls outwards), but strictly from an inertial point of view you would not continue to perceive rotation. I should add though that our bodies sense of rotation and movement, a complex concept known as spatial orientation, relies on more than just our inner ear, but our vision and higher cortical thought processes as well. And assuming that you weren't blind and could see the stars rotating in your field of vision, you would feel extremely disoriented and might become nauseous :) ",
"tl;dr: our bodies ability interpret angular momentum is complex and you should probably just read what i wrote. "
] |
[
"One should be very careful about guessing how the balance system behaves, because much of it is highly non-intuitive. For example, I have visited the Royal Air Force medical something-or-other department, where they have a little machine they put their pilots in for training and tests. It is basically a chair in a completely black box, which can be spun around one end (where the pilots feet are). They spin you around, not particularly fast, mind, and it is completely black inside, except for a couple of lights in front of you that they ask you about. ",
"Now you might expect the pilot to get dizzy in this arrangement, but what actually happens instead is that the pilot cannot feel the rotation at all, but their estimate of where the horizon is goes downwards.",
"This happens, because the rotation is not felt, but the acceleration (push in the back) due to rotation ",
" felt. This acceleration vector (or push, if you will) gets added to the gravitational vector, which the mind interprets as gravity coming from a different direction.",
"They use this to demonstrate what happens to a pilot flying low-level through cloud or fog. If this pilot turns on his afterburner to get out of there, the acceleration causes him to miscalculate where the horizon is and fly the plane downwards towards the ground.",
"Based on this experience, I would guess that dizziness relies partly on the inner ear and gravity, and partly on visual cues. So I am not convinced that you would get dizzy in microgravity with your eyes closed.",
"In summary though, I think your best bet is to ask an astronaut."
] |
[
"What is the differerence between phonetics and phonology?"
] |
[
false
] |
[deleted]
|
[
"Try ",
"r/linguistics",
" for this question."
] |
[
"Phonetics is the performative aspect of language (the sounds you actually produce) while phonology is the study of the sounds that you recognize mentally.",
"For instance, in English we make no distinction between aspirated and unaspirated consonants (you can tell if a consonant is aspirated by putting your hand in front of your mouth as you say it. If you feel a puff of air, it's aspirated). In your brain, there's no distinction between the [k] sound in \"cat\" and \"skin\". This is because they are phonologically the same in English. ",
"Now put your hand in front of your mouth and say \"cat\" and \"skin.\" You'll notice that the [k] in cat is aspirated and and the [k] in skin is not. This is the phonetic difference. "
] |
[
"does askscience have linguists to answer questions about language? I know there are one or two people who field answers to neuro-ling and computational ling, but I noticed language questions here tend to get inundated with speculation/lay-man answers, rather than the viewpoints of actual language scientists."
] |
[
"Is there an empirical method to calculate the surface area of an irregular solid?"
] |
[
false
] |
Archimedes (apocryphally, at least) provided us with an empirical method of calculating the volume of an irregular solid using water displacement. Is there any analogue for surface area? It would be nice if there were a method that doesn't rely too much on technology (I kinda want something that could've been produced by the Greeks), but I'm interested in any solution that doesn't use any kind of calculus / convergence of approximations arguments. If there is no analogue for surface area, is there some kind of proof or heuristic argument that there can be no such method?
|
[
"You could take a can of paint would form layer of certain thickness, submerge the object in thispaint, take it out, and see how much paint is missing. Divide by thickness and there you have surface area.",
"This would rely on the paint consistently forming layer of specific thickness, and while it's roughly true for all paints, it's not ever gonna be exact.",
"Mathematically, even if you had ideal paint, you also run into the problem caused by the shoreline paradox. You cannot compute shoreline of any real object. Similarly, surface area would be subject to changes as the thickness of your paint varies, ultimately requiring infinite amout of paint for paint that has no thickness.",
"Mathematically, this is best explained as shoreline having dimension higher than 1 but lower than 2. Length applies to 1-dimensional things, area to 2d objects. Similar to shoreline, any real object would not have 2d surface, it would be slightly nudging towards 3d with small cracks and such, not enough for it to be volume, but enough to cause shoreline paradox to be relevant."
] |
[
"Apply a layer of spray adhesive to an object of known surface area, such as a cube of 1 cm on all sides. Put a known mass of fine sand in a tray. Roll that sticky cube in the sand until no more will stick. Measure the new mass of the tray of sand. That gives you a rate of that sand sticking per square centimeter.",
"Now repeat that process with your irregular object. The \"rate of stick\" and the change in mass of the tray of sand will yield a pretty good but not perfect surface area. I bet it's +/-5% or something."
] |
[
"Chemical reactions that happen on the surface of the object (e.g.: corrosion), would release energy as a function of the surface area.",
"Heat transfer by conduction is also a function of surface area, although creating an ideal scenario is difficult considering complex convection in the surrounding fluid. It may be a good enough approximation though, especially where the solid and the surrounding fluid have greatly different thermal properties."
] |
[
"If all galaxies are moving away from each other how is it that the Andromeda galaxy will collide with our own galaxy?"
] |
[
false
] | null |
[
"The average trend is that galaxies are moving away from each other. On small scales (e.g. nearby galaxies), your normal motion through space (from gravity etc) is in some sense \"stronger\" than the expansion of the universe, and so on a small scale you can get galaxies moving in all sorts of directions relative to each other. We even have galaxy clusters where a hundred galaxies orbit around a common centre."
] |
[
"Whoops, I misread your question! So the Local Group is part of the Virgo Supercluster (but ",
" the Virgo Cluster, although that's the main component of it - i.e. we're in New York State, but we're not in New York City), but I'm not sure if we're bound to it or not. I'm looking up some papers to check.",
"Edit: Okay, ",
"found the answer",
". So if you look at things with classical physics, then you would think we are bound to the Virgo Supercluster, because its recession velocity (~1000 km/s) is less than the classical escape velocity (~2000 km/s) - i.e. we're not moving away from each other fast enough to counter gravity. However, with dark energy we now know that the expansion rate of the universe is increasing, and that means our recession velocity will continue to increase, and we'll never merge with the Virgo Cluster.",
"What I originally wrote:",
"The Local Group is only a \"group\", which means it's way smaller than a \"cluster\". The Local Group is basically the Milky Way and its satellites, the Andromeda Galaxy and its satellites, and a few random field galaxies like Triangulum.",
"A galaxy cluster is a pretty densely packed collection of galaxies, often enough galaxies that there's a sort of \"structure\" to the cluster - e.g. a ball with galaxies more densely packed in the centre, and getting fewer galaxies as you move outwards.",
"For example, Abel2744 is ",
" with ",
"loads of galaxies",
" - it's a much bigger bound structure than our Local Group."
] |
[
"The entire Local Group is gravitationally bound as far as I know. Is that the largest bound (i.e. it will not eventually become unbound due to the expansion of space on any reasonable time scale) structure we're part of?"
] |
[
"How big is a bit(or storage unit) on a hard drive ?"
] |
[
false
] | null |
[
"I'm pretty sure you mean the ",
" size of a bit. i.e. the amount of magnetic material required to represent a bit. For example, a floppy disc, which stores data on a linear track, has 686 bits per mm. Hard drives can store somewhere from 300 - 600 Gb / in",
" and flash memory can reach ten times that density."
] |
[
"awesome thanks! "
] |
[
"The bit is the smallest unit of memory storage for computers. Compared to the memory a computer has, it is tiny. For example, let say you have a hard drive with a space of 8 Gigabytes. 1 gigabyte is equal to 2",
" bits or 8,589,934,592 bits. So compared to the rest of the hard drive, one bit is about 100 billionths of the total space on that 8 GB hard drive. "
] |
[
"Has there ever been an observed impact of a meteor hitting the moon?"
] |
[
false
] |
Would a significant (but not catastrophic) impact be observable from earth with the naked eye?
|
[
"Yep, they've even been caught on video. ",
"This one",
" was apparently as bright as the North Star, so it'd be easy to miss if you weren't already watching closely.",
" Way back in 1178 a bunch of monks watched in awe as the moon writhed and spat out sparks and flame, which may have been a meteor impact responsible for the ",
"Giordano Bruno impact crater",
"."
] |
[
"That's awesome. Thanks."
] |
[
"There does seem to be a distinct lack of other expected evidence for that theory, though (as per the linked page) - no other witness records of the event, nor any records of any subsequent meteor storm as debris should have entered Earth's atmosphere.",
"A coincidental Earthly meteor does seem more likely. I wonder if atmospheric refraction from heated air could have caused \"the Moon [to throb] like a wounded snake.\""
] |
[
"When a black hole 'dies' what happens to its mass?"
] |
[
false
] | null |
[
"That's not quite right (sorry to T.S. Eliot). The black hole radiation does start out to be fairly minimal, and stays small for quite a while. The temperature of a black hole is inversely proportional to its mass, and the power emitted in Hawking radiation is inversely proportional to the (mass)",
". So most of the evaporation of a black hole is a slow, slow process, but the very end of the black hole's life sees a dramatic burst of Hawking radiation."
] |
[
"I think you misunderstand Hawking radiation.",
"A black hole does not suddenly explode into Hawking radiation. It gives off very little radiation and this radiation causes the black hole to lose mass. After enough time, all the mass has been carried away and the black hole ceases to exist. Evaporation is a better term for this process than collapse which implies some sudden event (even though at the very end it goes quite fast).",
"However, even a relatively small black hole (one solar mass) has a life time much (much, much, much) longer than the age of the universe."
] |
[
"The Hawking radiation evaporation of a black hole is a slow process. Black holes go out not with a bang, but a whimper."
] |
[
"Why is the oort cloud spherical while the rest of the solar system flattened itself out into a disk?"
] |
[
false
] | null |
[
"So the Oort cloud is big, and its formation history and evolution is not fully understood. ",
"Check ",
"this picture.",
" The Kuiper belt is barely visible in that picture - the inset shows Pluto's orbit. My point is that the Oort cloud covers a vast expanse of space, extending almost halfway to the Centauri system. ",
"You'll also notice in that picture there is a sort of flattened disk in the middle. That's the inner Oort cloud, or Hills cloud. So part of the Oort cloud does form a disk. Your question is more specifically about the outer Oort cloud.",
"So why isn't the outer Oort cloud spherical? I think it's fair to say that its formation history is not fully understood. The outer Oort cloud could have formed long ago and remained relatively similar in shape for a long time (perhaps by capturing lots of small planetisimals on oblique orbits when the solar system first formed), or it could require steady replenishment by bodies being ejected from the inner cloud in 3-body interactions.",
"The short answer to your question is just that the outer Oort cloud is sparse and far from a major source of gravity so it has a much much longer timescale for flattening to a disk. Compare that to the timescale for gravitational disruption by distant bodies. The further they are from the sun and planets, they less force they experience which would pull them into a disk. The farther from the sun, the more weird gravitational perturbations from distant stars they experience. "
] |
[
"So why isn't the outer Oort cloud spherical? I think it's fair to say that its formation history is not fully understood. ",
"Well, it's not like we don't understand anything about it.",
"The working hypothesis is that it was created when small icy planetesimals were flung out on very long orbits by gravitational scattering events with the giant planets (mostly Jupiter). Since these scattering events can happen in any direction, it ends up forming a sphere of scattered icy bodies.",
"This sphere of bodies scattered by giant planets is pretty well reproduced in most simulations of solar system formation."
] |
[
"can it be that Oort cloud is our solar system in forming stage? that eventually in few million years it will be disk like inner Oort cloud? "
] |
[
"Why do tropical cyclones migrate polewards?"
] |
[
false
] |
I know it is a way of heat transfer, but what makes it move polewards?
|
[
"This is actually due to an effect called the Corolis effect. Its all to do with the fact that the hurricane wants to travel in a straight line but its instead sitting on the surface of a rotating body (in this case the earth). ",
"Its a bit like you sitting on a rotating childs roundabout and throwing a ball out from you, it'll go in a straight line to anyone not on the roundabout but appear to you to curve up. ",
"http://en.wikipedia.org/wiki/Coriolis_effect",
" probably explains it better than I ever could."
] |
[
"I understand Coriolis effect, but I don't know what makes it move in a straight line towards the poles in the first place."
] |
[
"This is not correct.",
"The poleward migration of a tropical cyclone is due to ",
"Beta drift",
". If a hurricane were traveling purely zonally, it wouldn't experience any poleward Coriolis deflection."
] |
[
"If a person is unconscious on a spinning object, will they wake up dizzy or not?"
] |
[
false
] | null |
[
"There is a lot of ambiguity in your question in regards to how the object is spinning, but I will phrase my answer to address that.",
"If the object is spinning in such a way that the person in the same setup would be dizzy if they were awake and had their eyes closed for a long time, then they will also be dizzy during the setup you described.",
"Basically - your balance organs are working even when you sleep. Whether they are recognized by the brain during unconsciousness is more difficult to answer and is likely to be dependent of the cause of unconsciousness.",
"But once awake and assuming that the person is in a \"normal\" state, the balance organs definitely work.",
"Dizziness like this comes from situations where your senses provide conflicting information to your brain. This can be because your eyes see a different movement pattern than your head experiences (which explains why some people get dizzy during movies) or because your balance organs (one set in each ear) provide conflicting information (so one organ says you are spinning in one direction and the other says you are spinning in another direction or not spinning at all)."
] |
[
"When you wake up, you'll have gotten used to the spinning platform (I assume constant angular speed) so you might get dizzy if/when you see beyond the platform, which then isn't spinning. The equilibrium organs think you're not spinning while your eyes tell you you clearly are, so you might get dizzy from that. ",
"Personally I only get dizzy when stepping of eg. a spinning chair. Here the situation is slightly different. So first you along with the fluid in the semi-circular canals is spinning at the same speed, so no response. When you step of you will very quickly slow down and stop spinning, whereas the liquid in the semicircular canals moves much more freely and takes longer to slow down, during this time you'll feel that you're accelerating rotationally counter to the earlier direction, because the fluid is now rubbing against the sensory hair-like cells on the inside of the semicircular canals. This will continue for a while until the liquid slows down and stops. ",
"Another thing you'll also experience is involuntary saccades, that is eye movements that are trying to retain your gaze at one location, but because they rely on sensory input from the equilibrium organs, which are sending wrong signals, from the perspective of another person it looks like your intermittently glancing to your side."
] |
[
"The thing to add here is that the balance organs don't detect absolute rotation or translation to that fact, but rather rotational or translational acceleration, so it's not so much consistent long spinning motions in films that result in conflicting signals, but rather the quick twists and turns. Here you expect a signal from the equilibrium organs to confirm what you just saw, and when this doesn't come, some people experience dizziness."
] |
[
"Is the genotype a phenotype?"
] |
[
false
] |
I can select for specific individuals with a desired genotype by establishing their genotype in the lab and then removing all of those individuals who don't have the correct genotype. This even though selection is traditionally supposed to act on a phenotype. Does this mean that an organism's genotype is in fact a phenotype? Does this distinction matter at all when discussing the practical theory of evolution, mathematically or otherwise? I'm interested if such a seemingly philosophical question might have actual implications in the history of the understanding of evolution.
|
[
"Those terms were coined about a century ago, back before we had any idea how genetic information was transmitted. Back then, the only reliable way to get the genotype of an animal was after the organism had given rise to a few generations of controlled breeding. ",
"There are exceptions to this, though. Imagine you have a simple inheritance gene with a recessive allele (the classic, unrealistic yellow peas thing). If you see an organism with the phenotype associated with that recessive gene, you can immediately derive some partial and useful information about its genotype. You know it has two \"yellow\" alleles, its parents had to have certain alleles, and its progeny will have certain patterns. It's not complete, but it is useful.",
"But that was the exception, not the rule. Originally, \"genotype\" referred to the genealogic information about an organism. It was information outside of the individual organism. Phenotype referred to physical characteristics, things that were measureable.",
"Today, the meaning of \"phenotype\" hasn't really changed, we're just able to measure a lot more stuff than just the color of the pea. Now, we know that the DNA sequence AAGATTAGGAA is associated with this allele, and if we see it, we can make predictions about the parentage and progeny.",
"As a result, the meaning of \"genotype\" is now often used to refer to \"what alleles this organism has\" as a kind of shorthand. This isn't necessarily a bad thing, but it can be a source of confusion when using the old definitions and rules.",
"So try to think of genotype in its original sense; information outside the organism, something somewhat abstract. Genotype is something we assign to it. We can derive it from phenotype, but it is separate.",
"So in answer to your question, the genotype is not a phenotype. But the PCR you do to genotype your animals is also not a genotype. It's a phenotype from which you can derive partial (but useful) information about the genotype. "
] |
[
"When you remove subpopulations of a certain genotype from a larger population in the lab, you are acting as an exogenous agent of selection within your system. You should ",
" interpret this experiment through the lens of Natural Selection; you have replaced Natural Selection with artificial selection (i.e. selectively removing specific genotypes). ",
"The definition of a phenotype refers to the biological manifestation that a specific genotype produces; a genotype is the DNA sequence of the gene that produced the phenotype. The influence of Natural Selection has nothing to do with the biological definition of these words. The easiest way to think of this is the \"one gene = one trait\" perspective: there is a gene for blue eyes, and a different gene for brown eyes. These genes are similar, but distinct. The sequences of the two genes are their genotypes; the different traits (brown/blue eyes) are the phenotypes. Keep in mind this is an abriged description, but sufficient I believe.",
"Although the hypothetical you describe should not be used to study Natural Selection's influence on certain phenotypes, there are certainly valid scientific applications for genotype-specific isolation of cells/organisms (e.g. ",
"investigating the role of clonal populations in certain types of cancer",
")."
] |
[
"Phenotype is best defined as being any trait that is not genetic material per se. The distinction matters because the genotype is what is transmitted to the next generation, not the phenotype.",
"When selection acts on a particular phenotype, there may or may not be a genetic basis to that phenotype. We often think of selection as acting on particular traits, but ultimately what matters is genetic variance for fitness. You might be able to select for a particular genotype in the lab (a kind of artificial selection), but what ",
" selection can act upon is genetic differences in reproductive success.",
"That said, some phenotypes can be pretty close to the genotype. For example, in some microbes selection has acted to reduce genome size, so in a way it's acting directly on the genotype. But what selection really sees is the difference in reproductive success, i.e. individuals with smaller genomes can replicate them faster and leave more descendants."
] |
[
"Why does peanut butter glow in the dark? (and other nuts)"
] |
[
false
] |
When shining a blue/violet/UV laser on peanut butter it exhibits brief but noticeable phosphorescence, usually a yellow or green color. Evidence: I previously posed this question to " " BBC podcast, but I disproved their answer (they said the peanut oil was simply fluorescing which is false) tested items are as follows glowing: not glowing: Camera info: Olympus Air, 14-42mm F3.5 ISO12800 Expo1/4s Edit:formatting
|
[
"Peanuts absorb at 365nm and emit \"delayed luminescence\" at peak wavelengths of 440-460 nm, as ",
"this paper",
" puts it. They state that delayed luminescence is a general phenomenon in living biological systems, and may last between 10",
" and 10s (they cite some studies in the alga ",
"). However, they don't speculate about the origin of this. These numbers fit with your UV/blue laser, but the emission is more in the bluish range than green. Interestingly, they showed that peanuts contaminated with the fungus ",
" emit weaker delayed luminescence (but stronger fluorescence at the same wavelengths). ",
"Peanuts contain a vast gamut of phenolic compounds, which do absorb in the UV range (",
"see this dissertation about peanuts",
"). The peak absorbance depends on the compound, but ranges between 220nm and 340nm. The phenolic content of peanuts also increases after thermal processing, due to breakdown of larger compounds into monomeric forms. This could explain the increase in intensity you see in peanut butter versus peanuts. The predominant phenolic compounds in peanut kernels were found to be free and bound forms of p-coumaric acids.",
"This study",
" has a detailed analysis of absorption and emission of trans-p-coumaric acid. Absorption peak ranges from 290nm - 350nm and emission peak ranges from 410nm - 450nm, depending on pH and solvent. There is greater fluorescence in aqueous solvents compared to organic solvents (10-fold greater quantum yield). However, there is no mention of long-lasting luminescence or phosphorescence.",
"It's likely that a mixture of phenolic compounds in their biological environment leads to different absorbance/emission properties than one compound in isolation. Based on your list, one could go through the compounds identified in the various species, and figure out which ones are particularly abundant in the luminescent and missing in the non-luminescent samples. The best overviews I found were ",
"here",
" and ",
"here",
", but they do not go into much detail of particular phenolic compounds. I found several papers where they looked at one particular fruit, but no comprehensive comparisons.",
"tl;dr: probably phenolic compounds, which also differ between species"
] |
[
"I think we'll need some ",
"NIST standard reference peanut butter",
" to make sure any experiments are controlled appropriately..."
] |
[
"the plastic does not change the effect, i would have shined the laser on a spoon of PB but this was just cleaner "
] |
[
"Why can OLED tvs be so thin compared to a LED tv?"
] |
[
false
] |
Ive looked up some stuff on OLED and what amazes me is how thin they can be. Is this because of the organic layer and why does the organic layer work this way?
|
[
"LCDs can be made very, very thin as well. It just hasn't been a real selling point outside of the phone and laptop universe. But in the phone world, there's essentially no difference in thickness between OLED or LCD phones, and televisions made to chase maximal thinness would be very close as well.",
"But stripped down to their absolute essentials, an LCD display with an LED backlight (which is what I assume you mean by \"LED\") requires those two layers-- one LED layer that is the light source, and the LCD itself, which acts like a changeable color filter on top of it to turn it into a picture.",
"An OLED has only the single layer-- the LED light source itself. It does not have the additional LCD layer on top of it. The picture is made up of a grid of tiny little OLED lights that are individually addressable instead of requiring the filter."
] |
[
"LED TVs aren't LED TVs, they are LCD TVs with LED backlights. LCD TVs require two layers, an LCD layer which allows or blocks light through individual pixels, each of which also have a color filter. The LCD layer passes through the light from the LED layer behind it.",
"An OLED display is a true LED display, each pixel is an individual colored LED capable of being adjusted in brightness. This has two advantages. One is that only light emitted by the display is created by the display, instead of having lots of light created by a backlight that is often absorbed within the display (creating heat and power inefficiency). The other is that because it's only one layer it can be very thin. An OLED display can be as thin as the LCD layer alone of a display, which is much thinner, doesn't require any diffusers and whatnot, doesn't require extra wiring, etc."
] |
[
"The light source gets moved to the side in that layout, but the light still essentially comes from the back. In addition to the diffuser you mentioned, there's a light guide and a reflective layer. The light has to be behind the LCD whether the source is there or not, so there will always have to be some sort of optical mechanism to make that happen."
] |
[
"Where in the atom is the Higgs boson located?"
] |
[
false
] | null |
[
"The Higgs boson is a ripple in the Higgs field. Making such a ripple requires a lot of energy, but the flat \"pond\" that is the field is always there."
] |
[
"Not at all, pretty much. The Higgs field on the other hand is everywhere"
] |
[
"Doesn’t the Higgs field need a Higgs boson to exist? Or am I misreading that?"
] |
[
"Reflected light from a colored object?"
] |
[
false
] |
From my understanding, when I shine a white light on a green object the atoms electrons 'absorb' the energy as the light has the same resonant frequency as the electrons which allows for the max amount of energy transfer. This means that the colors(wavelengths) other than green are absorbed the most while the green light is reflected.(If this is wrong please correct me) My question is, by what mechanism is the green light reflected from the object, is it reflected by the electric field of the atom? Is it absorbed and re-emitted? Does it undergo some sort of scattering, if so what one?
|
[
"It depends on the object. Absorption and re-emission in a random direction (scattering) is the most likely case.",
"The electric field of an atom doesn't do anything - electromagnetic waves don't interact with electromagnetic fields directly in a way relevant in everyday life situations."
] |
[
"No. In a classical model the incoming light moves electrons around which then leads to emission of electromagnetic waves again. There are electric fields in the material, but it is misleading to say that these fields would reflect the radiation."
] |
[
"Isn't the electric field created inside the material responsible for reflection from a dielectric surface, as well as from a metallic surface?"
] |
[
"Let's say I get punched in the head and suffer brain damage. What, exactly, is happening inside my head?"
] |
[
false
] | null |
[
"Well, to be honest, that depends on what actually happened inside your head. Every brain injury is not the same and the differences can be quite significant. "
] |
[
"I think it's important to note that is but one possible mechanism of brain injury and may not be the case in all instances of head trauma."
] |
[
"The acceleration of the skull causes it to impact the brain, damaging the brain at the site of impact (or general direction of where the punch came from). A secondary injury could occur at the opposite side of the brain, which is where the \"rebound\" occurs. That's known as ",
"coup contrecoup injury",
"."
] |
[
"Why is it that water expands when it freezes rather than contracting like most other substances?"
] |
[
false
] |
[deleted]
|
[
"Nice to see this question again, I've struggled with it for a few weeks in highschool. So nice to help someone out with it.",
"Ok so, (almost) everything has three phases depending on the temperature and pressure it is in. Namely; Gas, liquid and solid. ",
"This is illustrated very well in something called a phase diagram.\n",
"Normal material",
", ",
"Water",
"Now if you look closesly to these two diagrams, then you will see that water behaves oddly near the transition of liquid to ice. \nWhere the line that separates them leans to the left, rather than to the right. This might seem trivial but you have to look at what this means. ",
"If the line leans to the right, the it means that at high pressure, a liquid can be compressed into a solid, which makes sense as it is a more compact form. \nWhen the line leans to the other side however, this implies that if you compress an icecube, it will become a liquid. (which should shock/confuse you)",
"As this means that ice is not the most compact form water can reside in. ",
"Now this is all because of a very special characteristic of water, namely the fact that it can form hydrogen bonds (you might want to wiki this term). \nAnd these hydrogen bonds cause the ice crystal to form in a very spacious way, taking in a lot more space than a solid without hydrogen bonds would. ",
"Ice crystal",
" ",
"CO2 crystal",
"As you can see in these two crystals. \nAnd this is why water expands when it freezes, the crystal lattice is just very widely spaced. (This is also why ice floats on water, because its density is lower)",
"Hope this was a bit clear :P"
] |
[
"The hydrogen bonding network is the reason it forms this structure."
] |
[
"The molecule H2O has a bent shape due to the number of leftover electrons on the oxygen. Picture a V with a 105 degree bend, the middle being oxygen and the two ends of the legs being hydrogen. This bend cause one end of the molecule to by negatively charged (the oxygen) and the other end to be positively charged (the two hydrogens). When energy is taken from the molecules, or they are cooled down, they start to lose kinetic energy causing them to slow down. When moving at a slower rate the positive ends line up with the negative ends of other h2o molecules causing what is called a hydrogen bond. These hydrogen bonds keep the molecules farther apart from either other and more organized than when they are moving freely. When the molecules are farther apart they take up more space per number of molecules which results in a less dense substance."
] |
[
"Where does wind start?"
] |
[
false
] |
I'm fairly sure most energy on earth comes from the sun or our superheated core, but where does the energy for wind come from?
|
[
"All wind is due to to pressure and density differences in the air between different places. These pressure and density differences happen due to temperature differences: the sun heats different parts of the earth by different amounts (so-called ",
"differential heating",
") on both large and small scales, both of which are responsible for why the wind blows.",
"On a large scale, the round shape of the Earth means that ",
"the tropics get more energy per unit area than the poles",
" because sunlight hits the surface at different angles. The temperature difference between the equator and the poles creates and ultimately the ",
"jet streams",
", which ",
"power most of the storm systems",
" (and therefore wind) on a global scale.",
"On a small scale, the different substances found on Earth's surface (soil, rock, water, vegetation, etc.) all have different properties (such as ",
"reflectivity",
", ",
"emissivity",
", and ",
"heat capacity",
") that cause them to reach different temperatures under the same sunlight. For instance, the air above hot asphalt on a summer day will become much warmer than the air over a nearby lake. These temperature differences result in density differences due to the ",
"ideal gas law",
" (warmer air under the same pressure must be less dense), and the cooler/denser surrounding air will push it up and out of the way, creating wind. As a specific example, this is the mechanism that drives the ",
"sea breeze circulation",
". "
] |
[
"Sudden wind gusts are caused by a few different phenomenon, but the most common is just plain old turbulence. For almost every layer of the atmosphere, except for just above the ground, wind speeds are relatively constant over short periods of time (in other words, they aren't \"gusty\"). Friction in the ",
"planetary boundary layer",
" (the layer of air closest to the ground) means that the wind above Earth's surface is almost always going to be stronger than the wind near the surface, where people spend the majority of their time. This means that there is a region of high wind speed flowing over a region of relatively low wind speed near the ground. The boundary between these two regions is inherently unstable, which results in turbulence. This turbulence has the consequence of sending some areas of high-velocity wind down towards the ground.",
"Here is a simulation that probably gives the best visualization of this phenomenon",
". In that video, high winds are marked in red, and light winds in green and blue. You can see that as time goes on, areas of high winds are brought down to the surface due to the turbulent motions of the boundary layer, causing what we know as a \"gust\" of wind. The updrafts and downdrafts I mentioned in my top-level response can also serve to bring these higher winds down to the surface if they are present."
] |
[
"What accounts for small gusts of wind we feel as opposed to large steady movements of air? "
] |
[
"How high off the ground do you have to be in order for there to be no bugs?"
] |
[
false
] |
[deleted]
|
[
"Very interesting article, thanks for that. Whelp, so much for my brilliant plan for high-altitude insect-free camping."
] |
[
"This one",
" claims a single termite found at 19000 feet, the highest we've found an insect."
] |
[
"The height actually changes with the temperature and seasons. There was actually this village on a mountain that was just above this line. Global warming later caused the line to rise, thus allowing the mosquitoes and other insects to survive.",
"As for the approxamate height, I'm not quite sure. I am pretty sure it would have to be pretty chilly though."
] |
[
"Krebs Cycle: Where does the extra oxygen come from in the oxaloacetase+Acetyl CoA-->Citrate step?"
] |
[
false
] |
I am in a high school biology class, and I was studying the krebs cycle specifically tracing the oxygen through the cycle; in my textbook the diagram shows acetyl coA donating one oxygen to Oxaloacetate, which already has five, and then becoming Citrate, which has 7. Where is this mystery extra oxygen coming from? What am I missing?
|
[
"Good catch - this step in the process is catalyzed by the ",
"Citrate synthase enzyme",
". While enzymatic reactions are more complex and beyond the scope of your question, it is essentially an ",
"Aldol Condensation",
". Which is one of the more painful common reactions that most first year O-chem students will be forced to memorize. But to answer your question - the extra O comes from H20. So the the full reaction is more like ",
"acetyl-CoA + oxaloacetate + H2O → citrate + CoA-SH",
"Which is another thing you'll notice in Biochemistry compared to Gen Chem or some O-Chem - in those fields it is important to pay strict attention to stoichiometry and tracking every atom and molecule, in Biochem you can assume every reaction is taking place in water, so H+, -OH, and H20 are freely available and aren't tracked as closely."
] |
[
"Like you said, one of the oxygens comes from the acetate group. The other comes from a water molecule. ",
"The reaction, catalysed by citrate synthase, is a multi-step reaction, ",
"as seen here.",
" As you can see, in that last step a water molecule is added and the CoA is released. The actual mechanism here is slightly more involved, whereby a molecule of water loses one of its protons, leaving behind a negatively charged OH",
" which has a lone pair of electrons that attacks the carbonyl group of the intermediate and causes CoA to be released. The OH is then added onto the molecule and citrate is formed. ",
"To simplify it a bit, ",
"this diagram",
" nicely shows where each of the two extra oxygen atoms come from by having them as different colours. "
] |
[
"Thank you, I especially appreciate the diagrams!"
] |
[
"If something/someone could be inside the very center of the planet, would gravity pull the object/person outward from all directions? How would it be different from being in Space without any gravity?"
] |
[
false
] | null |
[
"This entry in the FAQ",
" is what you're looking for."
] |
[
"If you ignore the immense pressure, it would be identical to being in orbit. You would be weightless."
] |
[
"I've been subscribed to this sub from the get go and I never saw that FAQ... Well, my day is booked."
] |
[
"What are rocks made of?"
] |
[
false
] |
Like, i know it sounds dumb, but I dont really know what they would be made of. Like, if I look at a diamond, I know it's carbon. If we talk about air, ik its oxygen, nitrogen, etc, etc. But what are rocks made of?
|
[
"At the shallowest level, rocks are made of ",
"minerals",
", i.e., a naturally occurring chemical compound with a well defined crystal structure. As that definition implies, minerals are made up of elements, so this means that rocks are also made up of elements, but we tend to define them in terms of the minerals that comprise them, i.e., the type of rock is usually based in part on its mineralogy, specifically which minerals are present and in what relative proportion and in part on its formation mechanism, e.g., is it an igneous rock (crystallized from a melt), a sedimentary rock (either precipitated from water or formed from broken up bits of other rocks), or a metamorphic rock (a rock whose minerals have undergone chemical changes in the solid state in response to elevated temperature/pressure to the point where the structure of those minerals or their arrangements within the rock are fundamentally altered). ",
"We can walk through a tangible example. Let's consider a ",
"granite",
", a common intrusive igneous rock (i.e., it crystallized from a melt beneath the surface). The main minerals that make up a standard granite are ",
"quartz",
", ",
"alkali feldspar",
", and ",
"plagioclase",
". The chemical formula for quartz is simple (SiO2) but both alkali feldspar and plagioclase are characterized by what we call ",
"solid solution",
", meaning that they can have a slightly variable chemical composition, but generally alkali feldspars are made of Si, O, Al, and variable amounts of Na, Ca, and K, and plagioclase is made of Si, O, Al, and variable amounts of Na, and Ca. In terms of what makes a granite a granite, as opposed to say a syenite or granodiorite (other intrusive igneous rocks with vaguely similar compositions), we can define this in terms of either the proportions of the constituent minerals (e.g., using a ",
"QAP",
" diagram) or geochemically (e.g., in terms of the relative weight percent of the rock made up by SiO2 vs Na2O + K2O, like ",
"in this diagram",
"). The other thing that makes it a granite, as opposed to say a sandstone with an identical chemical composition and/or mineralogy, is the formation mechanism, i.e., that it crystallized from a melt at depth. ",
"Circling back to the original question, the example highlights that rocks (e.g., our granite) are made of minerals, but since minerals themselves are just chemical compounds, we could say rocks are mixtures of (typically more than 1 - though you can have 'monomineralic' rocks) chemical compounds."
] |
[
"The ten most common elements in the rocks of Earth's crust are oxygen, silicon, aluminum, iron, calcium, sodium, magnesium, potassium, titanium, and hydrogen. Sulfur is also a notable element.",
"The atoms of any individual rock are organized into mineral crystals, in which the atoms are arranged in a regular, repeating lattice that makes a crystalline solid. Different minerals are defined by their chemical composition and structure. For example, the mineral quartz is made of silicon and oxygen (SiO2) and the mineral calcite is made of calcium, carbon and oxygen (CaCO3). ",
"Rocks are aggregates of mineral crystals. Sometimes the individual crystals are large enough to see with the naked eye, giving the rock a spotted or striped appearance, but many rocks of uniform color have individual crystals too small to see without strong magnification."
] |
[
"Thank you for writing this"
] |
[
"Why do people only have 10 seconds of useful consciousness at high altitudes when most can hold their breath for at least 30 seconds?"
] |
[
false
] |
On average people are able to hold their breath for 30 seconds, but in the event of rapid decompression at high altitudes (40,000ft) they will become useless after just a few seconds. Why is this?
|
[
"That's only at like 45000-50000 ft where the air pressure is close to 2-3 psi. You can't hold your breath because your lungs and throat and such can't deal with the 12-13 psi difference. Time of useful conciousness decreases the higher you go. Around 15000 ft it's like 30 minutes.",
"Add on that since the concentration of O2 in your blood which was about even with that in the air in a pressurized cabin, or on supplimental oxygen is now greater than that in the low pressure air and breathing is actually removing O2 from the blood in your lungs, not adding it."
] |
[
"The higher up you go the thinner the air, therefore the lower availability of oxygen. ",
"If you're on Mt. Everest and take a deep breath, oxygen still comprises the same 23% of air that it does at sea level, but there is only 1/3 the air pressure over all - that means there is only one third the number of all (including oxygen) molecules, so you're only getting 1/3 the oxygen. ",
"Your lungs work because there is a particular oxygen gradient across the membranes of your alveoli/blood capillaries. They're designed to work well at a certain air pressure and thus a certain number of oxygen molecules bing-bonging around in your air sacs, but when you deviate from that (i.e. sea level to say 10,000 ft) all bets are off. Its a little like trying to mash your car's brakes when you have a leaky brake system. Might still work but nowhere near as well.",
"So, if you take a big breath and hold it at sea level, you still start off with a certain total overall amount of oxygen - 23% at ~100 kpa. When you take a big breath and hold it on Mt. Everest, your lungs start off with 23% of ~30 kpa. So if normally you could hold your breath for 60 seconds at sea level, I'd expect you to only be able to hold your breath for 20 seconds on Everest."
] |
[
"Sure. The time of useful conciousness is an estimate after all. You can probably function perfectly fine at 15000 ft if you take time to adapt to altitude or are reasonably fit. ",
"But you take an average person who lives around sea level helicopter them up to the peak and drop them off in a T-shirt and shorts and ask them to take a Math test they aren't going to be having a good time.",
"Useful conciousness is also expected to mean useful in the sense of flying an airplane. Like you might still be able to operate it, but might end up ignoring warnings or drifting off course, or not noticing your altitude isn't right.",
"Check out here for the table I was using btw: ",
"https://www.skybrary.aero/index.php/Time_of_Useful_Consciousness"
] |
[
"Can we breed giant insects?"
] |
[
false
] | null |
[
"There is the factor of ",
"structural integrity.",
" where ants would not be able to support themselves as well the size of elephants. ",
"Then what do your giant insects breath in our relatively low oxygen world?"
] |
[
"Insects are limited in size by the amount of oxygen in the air. \n",
"http://www.aps.anl.gov/Science/Highlights/2007/20070808.htm",
"I am not sure why Frank was down voted. "
] |
[
"Maybe they thought I was being dismissive of OP,",
"\nI will admit that the second part of \"what would they breathe?\" was based on the attached article of being attacked by giant insects, and was thus questioning, to continue the conversation, how would they fare when released out of their high concentration breeding farms.",
"Or maybe they were downvoting me thinking I didn't understand that ancient \"bugs\" were big, and thus had different \"structural integrity\" (I couldn't think of a better word, but it seemed to fit the scenario) than modern bugs have. ",
"Or maybe they were just meanies? People down vote for various reasons.",
"I too have thought of this same question when TIL'd that O2 is a size determinant. But figured that the above mentioned physics was keeping them small. "
] |
[
"Is the \"teen\" stage that humans experience (heightened hormones, erratic) present in other species? Does it play any role in nature?"
] |
[
false
] |
I'm just wondering if this stage of development that we've labeled the teen years is unique to humans, or a process in multiple species. If the "teen years" are present in other species, do they play any significant role in nature?
|
[
"In my physiology and neurobiology classes class we briefly discussed the endocrine system. The take home from combining both courses is this: we experience very strong hormonal stimuli almost every second of everyday. Our brains sort through and prioritize these signals.",
"When we become teenagers we see changes in these hormone levels and our brain is not able to adapt (filter) these signals efficiently. This causes abberent behaviour as one gives in to hormonal rather than societal (thought through) responses. As the thalamus learns to properly transmit signals, the frontal cortex takes over. ",
"Think of this like being blinded when you go from low light in a movie theater to outdoors. The sensory experience is too much for you to comprehend the situation. Instead of taking minutes to adjust, you take years to adjust to the flucuating hormone levels. ",
"This behavior can be seen in many animals, one example being dogs. ",
"I am sure you have seen or at least heard of dogs humping everything in sight. One solution is to neuter the dog which decreases and stabilizes hormones. The other option is to wait it out. With enough time, hormones level out, better filtering occurs, and the dog conforms to societal standards (less leg humping).",
"Many animals have 'rules' which define their 'societies.' Any hormonal stimuli in opposition to this would result in 'teenager syndrome.'",
"Tl;dr: Probably.",
"Sorry for spelling and grammar, I'm not sober and on my phone."
] |
[
"Yes, in my opinion.",
"In my own research of birds, namely American crows, we've noticed juveniles will do all kinds of crazy things. They'll often play with one another, have relationships that get them \"in trouble\" with parents, and much more.",
"When first-time \"teen\" parents are nesting, it can also be a bit erratic. Females will call ",
" from the nest for food without having much reason to do so, but they may also build terrible, poorly thought-out nests that blow away or collapse."
] |
[
"Dogs certainly do go through the \"question authority\" phase (which is pretty important to guide them through correctly, especially for more wolf-like breeds, both because this psychological change is more pronounced in them and because they are more dangerous), when they switch away from child-parent relationship with the owner and try to establish their place in the grown-up pack hierarchy.",
"Source: \"Man Meets Dog\" by Conrad Lorenz, which I strongly recommend as it explains a lot of stuff, and not only about dogs. Also the dude had several \"pet\" wolves."
] |
[
"What exact does a blood thiner do?"
] |
[
false
] |
Is it the same thinning as say, paint thinner? That is to say, in a medical sense, what does a thinner even do? Can other bodily fluids be thinned? Lastly, what measurables in the blood can be affected the most by blood that is overly thinned? Thanks.
|
[
"Hey, I study one of these! There are two main types of blood thinner, and I will summarize the activities of both.",
" block the clotting cascade - a sequence of events leading to blood clotting and recruitment of platelets, which are essentially cells which are meant to clot over wounds. These include:",
" - a protein which binds and turns off certain pro-clotting proteins.",
" and its derivatives, which are chains of sugar. Heparin binds antithrombin III and brings it close to the pro-clotting proteins - sort of like a handcuff between them, if you will. ",
"More on both it and antithrombin III here.",
" and its derivatives, one of which is warfarin. These function by preventing vitamin K from being converted to vitamin K epoxide, a form of vitamin K which is necessary for certain pro-clotting proteins to function. ",
"More here.",
" attempt to interfere with platelets' ability to bind each other rather than the cascade that initially signals them to form clots. These include:",
", which interferes with the ability of platelets to take fats and turn them into thromboxanes - molecules which, when the platelets secrete them, causes platelets to glop together.",
", which bind the protein thrombin and keep it from activating fibrin, a protein which links platelets together. It is also the target of antithrombin III, as seen above.",
"Lacking time, I won't describe some of the others; a good list of antiplatelet drugs, with their mechanisms of action, can be found ",
"here",
". The ones I've listed are the most common, however. The takeaway message is that most inhibit the ability of platelets to be activated (ready to bind each other) or interfere with proteins that help link them together."
] |
[
"So what would determine whether to use an anticoagulant or antiplatelet medication? I notice Aspirin is OTC while heparin and coumarin are prescription, so would I be correct in assuming that anticoagulants have a much higher capacity to prevent clotting? "
] |
[
"Many clinical trials have been done to determine which medications we would use in which circumstance. With these drugs you have to balance the risk of a blood clot and the risk of bleeding, as these \"blood thinners\" increase your chances of having internal bleeding such as from an ulcer. Many clinical trials have been done and are STILL being done to determine if the risks of drugs such as aspirin outweigh the benefits.",
"For example, in atrial fibrillation we use a score known as the CHADS2 score, which determines your risk for getting a blood clot. If you score is 1 or less, you are put on aspirin. If your score is 2 or more, you are put on warfarin. ",
"Another case is when someone gets a stent placed in one of their coronary arteries. Patients without atrial fibrillation are typically put on a combination of aspirin and clopidogrel (or another thienopyridine) for a certain period of time depending on what time of stent you get. For patients who have problems with their stents closing off or getting a clot, we may add another drug drug known as cilostazol, which also prevents platelets from clumping up but also expands blood vessels.",
"As for strokes, as long as it wasn't due to something with your heart (such as atrial fibrillation), you're typically only put on aspirin. If someone fails aspirin therapy we typically put them on a combination of aspirin and dipyridamole (acts similarly to cilostazol).",
"Typically, the thrombin inhibitors, the factor Xa inhibitors, and warfarin are reserved for patients who have a higher risk for developing a clot, while aspirin, the thienopyridines (clopidogrel), and cilostazol are for lower risk patients."
] |
[
"What things are humans surprisingly good at compared to other animals (besides the obvious)?"
] |
[
false
] |
The Obvious: Tool-building (opposable thumbs) Logic Language
|
[
"I have heard long distance running. Can anyone confirm or deny? (phone surfing - unable to provide links/sources). "
] |
[
"There's ",
"good evidence",
" that our sense of hearing is more sharply tuned than that of other animals - i.e., if you play a tone at frequency ",
" and another at ",
", the smallest ",
" at which we can distinguish the tone as a different note is smaller than it is for other animals. There's some speculation that this difference is responsible for our ability to have complex languages."
] |
[
"Why would I want to take the saddle off my woman just to see her glow? Do you have any idea how hard those are to get on? Not worth the effort.",
"(it's not a top-level comment, be gentle!)"
] |
[
"I have a few problems when waking up, but only in certain conditions."
] |
[
false
] |
[deleted]
|
[
"Sounds like you are pinching your nerves.",
"Regardless personal medical advice is not allowed on reddit."
] |
[
"Don't sweat it. Laws and good medical practice make it unwise to try and diagnosis over the internet, but I can guarantee you would benefit from seeing a doc to go over sleep hygiene with you and check your blood pressure and such to ensure nothing more serious is going on."
] |
[
"Please keep discussion:"
] |
[
"Found a gif on front page - Why does tape make fogged glass clear? (gif inside)"
] |
[
false
] | null |
[
"Frosted glass scatters light because the surface is rough, so you get diffuse scattering, where light coming through the glass is redirected to random directions. The result is a blurry image.",
"Tape can fill in these surface imperfections and provide a smooth interface for light to pass through."
] |
[
"To elaborate a bit, there is still a rough surface between the glass and tape just like there is between the glass and air. The difference in index of refraction glass to tape is much less than glass to air so the light does not get redirected as much."
] |
[
"The fogging is caused by a very fine roughness on the glass - picture many tiny hills and valleys. When you apply tape, it \"fills in\" the valleys, making the surface smooth and reducing the blur. ",
"Kinda like how if there's rocks at the bottom of a fish tank, you can pour in water to eventually get a flat, even surface (the top of the water)."
] |
[
"Does speaking a different language affect non verbal comunication?"
] |
[
false
] | null |
[
"Different cultures have different sets of non-verbal communication techniques and are connected to the language. Simple example: I can say thank you in English without moving by body but I can’t say it in Japanese without my body reflexively adding at least some bowing motion (slight downward nod of the head for example)."
] |
[
"To avoid redundancy, I'd add that in addition to the cultural influence on non-verbal communicative gestures, there is a bevy of research suggesting that the language one speaks influences how one thinks (Sapir-Whorf Hypothesis). This could, transitively at least, affect non-verbal communication."
] |
[
"I'm half American and half Danish. I've lived in both countries and speak both languages. When I speak English I'm more animated (I talk more with my hands). My impression is that Americans are more animated in their expressions than Danes are.",
"Until I read your comment I never thought about my gestures being tied to the language I choose to speak. But now that I think about it, I think they are."
] |
[
"White flakes from melted ice in Texas. What is it? (xpost from answers)"
] |
[
false
] |
This has fascinated and terrified me for years. What is it? I never finish a glass of ice water (on the rare occasion that I use ice) because of the flakes creepily waiting for a passport to my mouth at the bottom of the glass. I have seen this in no less than 3 different households in 3 different cities from 3 different freezers, all in the state of Texas. At we determined that it is minerals from the water that are forced out of solution when the water freezes. Is this correct? Is there any way of knowing minerals?
|
[
"http://en.wikipedia.org/wiki/Calcium_carbonate"
] |
[
"Uh... any way to get a picture that's in focus?"
] |
[
"\"More than 85% of American homes have hard water...Hardest waters (greater than 1,000 ppm) are in streams in Texas, New Mexico, Kansas, Arizona, and southern California.\""
] |
[
"Are there any previously thought finite resources we've been able to synthesize? Any that we might be able to in the future?"
] |
[
false
] | null |
[
"Taxol comes to mind. The original production required extraction from the plant at such low yields that demand would have pushed the tree to extinction. They then figured out how to make it from the needles instead of bark, then a total synthesis, and now it is grown in fermenters. ",
"Insulin would be another example."
] |
[
"It isn't quite the same as regular gasoline, but \"fossil\" fuels can be produced from biological products now: ",
"http://en.wikipedia.org/wiki/Biofuel"
] |
[
"They can also be synthesized from water and CO2 from the atmosphere, if you're willing to spend to energy to do it."
] |
[
"Why doesn't gas build up in our bladder?"
] |
[
false
] |
Since it can build up in our intestines and produce farts, why is there no build-up in our bladder?
|
[
"Well...the bladder is also topologically on the outside of the body."
] |
[
"Well...the bladder is also topologically on the outside of the body."
] |
[
"That would imply that there's bacteria in your bladder that are digesting your urine and producing gas. It's bad enough that bacteria cause UTIs when they infect the bladder/urethra."
] |
[
"Do you really piss away multivitamins?"
] |
[
false
] |
I've read too many conflicting articles on the subject. Are multivitamins worth taking, or do you piss them away?
|
[
"Even if you eat crappy foods, as long as you're getting things like vegetables and what not (IE not surviving off twinkies and coke), you still aren't going to need a vitamin supplement. ",
"And to answer the OP: Yes, you are literally just pissing away money when you take one. If you just ",
" to take one, don't pick one of those jam packed vitamins with tons of weird stuff, because the only vitamins that you store to any great degree are K, A, D, and E (the lipid soluble vitamins; also the vitamins you can OD on); the others are water soluble (mainly the B vitamins) and aren't stored at any appreciable levels. Instead, pick something like Calcium, because Calcium is used ",
" in the body. But that said, you retain about 99% of all your calcium in your body and you only absorb about 1% of calcium from your meal, because that's all you really need to replace the 1% you lost in urine. So it's quite pointless to even take a calcium supplement, useful as it is, because your body conserves so much of it on its own. It'll either just piss out the extra calcium that it doesn't need, or store it in your bones. ",
"There's another school of thought where you're actually doing some 'harm' to yourself in that some metabolites are only actively excreted in the kidneys (vs being filtered in the plasma filtrate and excreted that way). ",
"This is done by transport proteins and it's a very non-selective process. So that toxic metabolite you have left over has to utilize the same pathway as that harmless metabolite you have left over. Too much of the harmless and the toxic won't be able to escape as well. ",
"They utilize this same concept with some of the more quickly metabolized drugs. They'll basically give two drugs at the same time: the active drug (X) that actually does something and an inert drug (Y) that is purely there to compete with X for transporters in the kidney so that it's not eliminated in the urine as quickly. "
] |
[
"Multivitamins are worth taking if your normal diet is lacking in the vitamins that your body needs.",
"Basically, they are (like the label says) a supplement. I found that when going on one of my \"once in a while\" healthy binges eating fresh salads, fruit and the like, that my urine also came to a very saturated vibrant color even though I was drinking loads of water.",
"While not medical advice, I would say: If you have a crappy diet, taking them won't hurt and your body will probably pull out what it needs, but if you go out of your way to eat good food, chances are you won't be getting as much use from them."
] |
[
"It becomes more dangerous in vitamins you don't piss out easily, namely the fat-soluble ones. A, D, E, K all are not excreted from the body as easily and can build up to dangerous amounts. Fortunately, (or unfortunately, as this is one of the major factors causing vitamin deficiencies around the world) they also do not absorb as easily."
] |
[
"Why are metals found in veins/lodes rather than all mixed together?"
] |
[
false
] |
Liquid magma erupts from the mantle to become crust. Why isn't the crust well-mixed? Why are veins of precious metals, rare earths, actinides, etc, found in specific locations? If these veins are actually remnants of meteorites, which are remnants of supernovae, same question. Why would they clump together by element (or by series) out of energetically churned plasma?
|
[
"Only a few metals are found in their metallic state (gold, silver) - the rest are found as minerals. As to why they are in veins, super hot water from deep under dissolves the metals or minerals, the water percolates up and cools and releasing the metals. As the water squeezes though narrow defects and holes to get up, it drops its load along those narrow tracks - resulting in veins of metal"
] |
[
"This topic is actually rather complicated and depends on multiple factors and I will simplify this a lot.",
"\nFirst of all; not all elements behave the same. For each mineral that is forming from a magma, every element has a specific partition coefficient. That means that the longer a magma evolves (meaning forming minerals and cooling down), the more its primordial composition is altered. Therefor, the erupted lava is often does not directly show the composition of the mantle. In that also plays the factor of melting partition coefficient. If you have a solid and melt that (remember, the mantle is not liquid!), you will melt only certain minerals and therefor get a specific element pattern for these melted minerals.",
"\nIf we then look at all these precious metals, we can see that their partition coefficents are generally rather low for all the typical magmatic minerals. Therefor, when the magma cools down, these incompatible elements will be enriched in the liquid. If you have e.g. a granitic intrusion, you can get so far that you basically only have \"vapour\" left; all the other stuff is mineralised. This vapour now (together with the overall intrusion) create a lot of stress on the surrounding country rock, which can result in cracks. If these cracks form, the overall pressure is reduced, and all the vapour can escape. This is called \"first boiling\". This vapour is now actually an extremely corrosive fluid, that can massivly alter the surrounding rock, however more importantly; it is enriched by all these incompatible elements. These are \"solved\" in the fluid due to its high temperature. Imagine you bring water to 90°C and toss so much table salt in it that the equilibrium is reached. Now you cool the solution down to...let's say 20°C. Now of course the equilibrium constant has changed and solid salt can be found in the water. This is of course only an analogy, but in a way, all the veins form in a similar fashion. We call these pegmatites, when they are specifically bound to a intrusion. Another case how we can form veins is e.g. the bulk of mineralisations in central Europe. Due to old mountain building events, there were a lot of deep-seated faults there. When the Alps began to form, this resulted in a lot of stress in the back country and some of these faults were reactivated. Now you had \"crevasses\" into great depths and then more or less similar thing happened like with the pegmatite; reduction in pressure lead to the formation and \"degassing\" of fluids, forming veins.",
"As for the REEs; these are more often than not directly bound to the magma/lava; meaning that these (often extremely old) magmas were so enriched with these elements, that they formed specific minerals.",
"\nTherefor the concept that the veins are remnants of meteorites is kinda wrong. Yes, basically all elements are results of supernovae and the agglutination of meteorites lead to the initial \"enrichment\" of these elements. However, our earth's crusr today is vastly different from the primordial earth. The only thing that is mostly similar to that of our early earth is the material from Mid-ocean ridges. However, if we compare them to the material of condrites (actually earth was formed from chondrites, not meteorites), we can see that these are still different."
] |
[
"Thank you friendly Kentucky miner."
] |
[
"The NPR population visualization video is great. Please teach me about a more detailed version of the model used in that video."
] |
[
false
] |
The video represents global population as flow into (births) and out of (deaths) containers representing major world population regions. As an engineer this was immediately recognizable as a "salt-tank" problem that we all learn about in our differential equations class. I began to think about other factors that could be modeled in this system. The most interesting that I thought of would be total wealth. If I wanted to add the total wealth of that population as a "salt" flow, how does it then look? What interesting things have we learned by looking at it this way? What are other interesting ways to make this model more comprehensive? (for example, representing carrying capacity as the size of the container, as illustrated near the end of the video). I'm assuming that this analysis has been done and re-done by many folks, but I don't even know what field of science that would be or where to look for more information.
|
[
"It was a very neat demonstration, and yes - it did remind be of the \"draining tank\" problems we all see in DiffEq.",
"The problem with using 'salt concentration' as an analogy to wealth is that the salt concentration would be homogeneous throughout (whereas wealth is certainly not equally distributed throughout a population), and 'wealth' doesn't necessarily 'die-off' as people die (it can be inherited, for example).",
"Just a though, but what might we model if the tank were shaped as a cone, with the fluid level 'height' an indicator of some quantity..."
] |
[
"Ah yeah. I remember those assumptions now.",
"Hmm, so the height. ......scribbling......scribbling....",
"So..the volume is the population, and the height increases as the volume increases, but at a slowing rate based on the angle of the cone.",
"So perhaps it could represent something that a population consumes. It consumes a lot as the population gets started, and consumes more as the population grows, but the consumption per individual decreases as population grows.",
"I guess instead of consumption of something, it could just as easily represent production of something.",
"OOOOOhhhhh, it could be some sort of productivity measurement. As you have more people trying to do one thing, you need (arguably) more people supporting that effort in less direct ways.",
"Hmm, did I take that too far? ",
"Thanks for the response!"
] |
[
"Like the quantity of dirt required to add the incremental height to a hill versus a mountain. The height is productivity and the dirt is the population."
] |
[
"How much energy is being wasted on useless flash banners and ads?"
] |
[
false
] |
I recently read an article that described chrome to be the first browser that stops rendering flash animations that are in other tabs/not in screen. Since flash is quite an intense program for the CPU, how much energy is being wasted on flash animations? i dont mean youtube videos, but ads, banners and other spam. And, as a next question, in how many avarage powerplants / windmills could we express this?
|
[
"As a software engineer, I don't think you're going to get an accurate answer. There are simply too many factors to take into account. Here are a few:",
"I could go on for a while. I'm sure someone more informed can give you a number, but I would be ",
" surprised if it's remotely accurate. Heck, I would be impressed if someone could give you an accurate number for the energy wasted on flash ads in a local library, let alone the world.",
": grammar & spelling."
] |
[
"That requires the initial assumptions to be of reasonable quantities. I'd love to be proven wrong, but the scope just seems a bit too crazy for an accurate answer. I wouldn't even know where to begin. "
] |
[
"There is also the extra energy used in all of the extra network requests that take place. Those transit a half dozen routers at a minimum. Add the energy used by the ad servers. Then there is the cost of the CDNs for lower latency. Then the ad brokers, who run high speed auctions for your eyeballs when you load the page."
] |
[
"How can water be heavier than the respective elements that make it up?"
] |
[
false
] |
So I understand basically that electrolysis of water splits water into its base elements of Hydrogen and Oxygen, but how can combining them create something that is heavier than the sum of it's parts? How can both Hydrogen and Oxygen be lighter than water if they make up water? Edit; Wow, this has been really eye opening to how little I understand chemistry. Thanks everyone that replied and I'll definitely be trying to learn more.
|
[
"Water actually weighs very slightly less than its constituent parts. Bound states are lower energy than unbounded states and this is manifested as a slight defect in mass. This is why you must put energy into the system to break it apart."
] |
[
"Oxygen has a molecular weight of 16. Hydrogen has a molecular weight of 1. Water is H2O, so 2 H, and 1 O. 16 + 2x1 = 18. The molecular weight of water is the sum of the weights of its constituent parts. What's the problem here? "
] |
[
"Maybe the confusion is that water is a liquid at room temp while H and O arent?"
] |
[
"What does the vy stand for in the name of the largest known star: vy Canis Majoris?"
] |
[
false
] | null |
[
"Variable stars inside a constellation boundary, like Canis Major, are given a prefix to distinguish them from regular, constant stars, like Alpha Canis Major (Sirius). The Roman alphabet is used, and if not enough letters available, two letters are used."
] |
[
"Just to expand on this, the system is much sillier and backwards than what was described above, all because the system doesn't start with the letter A.",
"The ",
" variable star discovered in a constellation boundary is given the letter ",
", and single letters continue to be used for ",
" through ",
". Now we're out of single letters (though note we haven't used A through Q).",
"The next one is ",
", then ",
", continuing through ",
". The convention now becomes to never use a \"decreasing\" letter sequence, i.e. never having an earlier letter after a later letter. The next one is ",
" (not SR as one might expect), then ",
" through ",
", and so on until you reach the sequence ",
", ",
", ",
". And now we've reached the end of the alphabet. But we haven't yet used the beginning!",
"So the next one in the sequence is ",
", then ",
" through ",
", ",
", etc. until you reach ",
" (after which point you'd be back to RR which we've already used). Except you skip any designations that have a J in them, presumably because J and I look too similar."
] |
[
"As if astronomy wasn't interesting enough on its own you all had to go in and create bizarre taxonomies. I realize in science you're often describing before you're explaining as knowledge progresses but can't we just hit a reset button and all agreed to start over on these at some point? Think of the students, for Zodiac's sake!"
] |
[
"question about osmotic pressure in a U-shaped tube."
] |
[
false
] |
I would have a hard time explaining the demonstration, so i have included a picture. for the water to diffuse through to tube to achieve equilibrium, it seems to me that it must fight gravity to ascend the originally hypertonic side of the tube. my question is, where does the energy for this come from? surely it takes energy to fight gravity and produce osmotic pressure. my best guess would be the kinetic energy of the water molecules, which is what allows for diffusion in the first place. can someone help me out with this?
|
[
"Things in nature like to be equal. Osmotic pressure is a manifestation of this tendency. The difference in concentrations creates a pressure, I am unsure about the nature of this pressure. I'm sure you are familiar with the equation for calculating osmotic pressure. I'm not too keen on formatting, and will probably make it look ugly if i try to include it here. However it may arise, this pressure is exactly equal to the pressure exerted by the increased water level in the animation. The difference in height of the two columns can be producted together with the density of water and the acceleration due to gravity to obtain the hydraulic pressure. By definition, these two quantities are the same."
] |
[
"i think i understand all of this, but it just seems to me that some force must act on the solution to create this hydraulic pressure. creating a difference in water level must take some energy. where does this energy come from?",
"edit: to clarify, this is sort of a \"conservation of energy\" question rather than one of why equilibrium is achieved."
] |
[
"i did not know that a concentration gradient has potential energy. the way you put it makes sense. "
] |
[
"How can sexual dimorphism exist even though offspring of both sexes inherit genes from both parents?"
] |
[
false
] | null |
[
"In humans, for example, males have an X and Y chromosome with different genetic information. Only one of those gets passed on (Y to male children, X to female). See here: ",
"https://en.m.wikipedia.org/wiki/XY_sex-determination_system"
] |
[
"But doesn’t the Y chromosome have almost no genes on it at all besides the one that makes you male? So how can these complex traits be inherited through the Y chromosome?"
] |
[
"Focusing on humans: the Y chromosome does have relatively few genes compared to the X, but even a single mutation in a single gene (and not just on the Y chromosome) can have profound effects. In this case, a ",
"single gene on the Y chromosome",
" controls the development of testes which in turn produce testosterone which is what primarily determines secondary sex characteristics."
] |
[
"How does a pop-fliter for a microphone work?"
] |
[
false
] | null |
[
"A pop filter blocks the flow of air from your mouth to the microphone, thus reducing \"wind noise\" caused by exhaling. ",
"Since its not a significant barrier to pressure waves it achieves this with little or no attenuation of the sounds you intended to make. "
] |
[
"Popping and clipping at two completely different things. You can have a pop without clipping and you can clip without a pop. ",
"There is no breaking up of sound energy with a pop filter, whatever that means.",
"A pop filter is not a compressor. It does not change how sound is presented to a mic, whatever that means. "
] |
[
"Popping and clipping at two completely different things. You can have a pop without clipping and you can clip without a pop. ",
"There is no breaking up of sound energy with a pop filter, whatever that means.",
"A pop filter is not a compressor. It does not change how sound is presented to a mic, whatever that means. "
] |
[
"What is the maximum resolution for optical fiber bundles (like the ones in endoscopes)? Could one, say, make a 20 MP \"noodle lens\" for a smartphone camera? What would be the caveats (e.g. thickness, color fidelity)?"
] |
[
false
] |
EDIT: pointed out that I misused the word "lens", since fiber bundles only transmit the light. It would require an additional lens in order to focus light. My question is more about the "noodle" part rather than the "lens".
|
[
"I don't know any specifics here, but when using a fiber bundle as a simple optical path (rather than transferring digital data), you get one pixel per fiber. I highly doubt 20 MP is possible at a practical diameter.",
"More importantly, though, a fiber bundle is not a lens; it doesn't focus light, it just transmits it. You'd still need a lens on the front, so I don't see any advantage of introducing a fiber bundle into the system at all."
] |
[
"A stop is a unit of measurement of exposure in photography. Each stop gives half as much, or twice as much light as the next, the name is derived from the stops on a lens aperture control ring, which control an iris inside the lens, used to give depth of field. Without an iris, camera lenses have very shallow depths of field, making focusing difficult. ",
"As the iris aperture is made larger or smaller, it changes the amount of light sent to the film, or sensor. Smaller aperture = less light, more depth of field."
] |
[
"A company called NPC used to make a Polaroid back for 35mm cameras, and they solved the problem of getting the plane of focus out of the body of the camera and back onto a sheet of Polaroid by using a block of optical fibres about 6-7mm thick. Worked okay, was a bit softer than your usual Polaroid, and lost about a stop of light on the way, but good enough to check lighting, exposure etc. "
] |
[
"What exactly are quantum computers and what are their functions?"
] |
[
false
] | null |
[
"A quantum computer is a device that exploits one or more quantum mechanical phenomena in order to perform information processing.",
"The fundamental unit of classical information is called a bit, and a bit can be in one of two states, 0 or 1. It's possible for the computer to measure which of these two states any part of it's memory is in.",
"In contrast, the fundamental unit of quantum information is the qubit. A qubit can exist in a whole range of state a|0> + b|1>, where a and b are complex numbers whose square moduli sum to 1. This is known as a superposition of the two computational basis states |0> and |1>. A quantum computer (under the most popular scheme for quantum computation) can't in general find out exactly what states its qubits have, but it can perform measurements on them which in general give probabilistic answers, where the probabilities depend on the quantum state. For example, we can ask the a qubit in the state a|0> + b|1> the question \"are you in state |0> or in state |1>?\", and we will get the answer |0> with probability |a|",
" and |1> with probability |b|",
" We could alternatively ask it if it belongs in any other orthonormal basis of states, which for these systems are a pair of states which are orthogonal to each other.",
"To try to put things simply at the expense of accuracy, being able to perform a computation using a superposition of states allows the computer to run faster in many circumstances. For example, let's assume we're trying to find a good item for a database and we have a quantum circuit that can, if we give it the label of an item, test if the item is good. If we give it a superposition of all the labels, our circuit can in some sense test them all at once. However, the challenge is then to get the information out of the state, since as I mentioned before we can only perform probabilistic measurements.",
"Entanglement, which is the property that measurements on one particle have an effect on its entangled partner, is vital for quantum computation schemes to work but its importance is a little more tricky to explain, I think.",
"This unsorted database search (called Grover's algorithm) is helpful in a vast number of situations from optimisation problems to cryptocurrency mining. We also have some other helpful quantum algorithms, such as Shor's prime factorisation algorithm which helpfully breaks RSA, a popular and often-used cryptosystem."
] |
[
"You need to jump through a few hoops because quantum gates have to be reversible, but yes, you can do any classical computation on a quantum computer. If quantum computing ever becomes possible and economical, I would expect it to always be coupled to a classical processor and employed whenever a task would benefit from quantum speedup."
] |
[
"The idea is that the measurement problem only affects the readout and that when the qbits interact with each other, they're not restricted in the same way.",
"A larger system - like one with more qbits - will also have a larger number of orthogonal states - n qbits can have 2",
" orthogonal spin states."
] |
[
"Is the energy the Earth receives from the sun constant?"
] |
[
false
] | null |
[
"Are there any noteiceable differences in weather or temperature, for example, on earth due to this?"
] |
[
"What you are asking is primarily driven by the angle at which the sun shines on the earth (i.e. different seasons). The differences in solar intensity due to distance from the earth are negligible for weather systems (long-term changes can have impact on past/future climate systems though)."
] |
[
"No. The sun goes through a 22-year cycle in which its magnetic field gradually flips. Sunspot activity is highest during the middle of this process, and during that time the sun puts out slightly less energy.",
"The Earth also has an elliptical orbit, meaning that it is not always the same distance from the sun, and the amount of energy received scales with distance."
] |
[
"Would it be possible to make a magnet in the form of a hollow sphere where the north is the outside and the south is the inside?"
] |
[
false
] |
I Assume it would require a tiny hole somewhere to be able to put something inside it to create the polarization of the magnet?
|
[
"No. Or more precisely, you can, but the magnetic field wouldn't leave the magnet. One way to prove the problem is the ",
"shell theorem",
". You have a spherically symmetric magnet, so the total pull from it if you're outside the magnet is the same as if it were concentrated in a point, in which case north and south would counter out and it would just be a point. You could also show the problem with ",
"Gauss's law for magnetism",
". The total magnetic flux going through a closed surface is zero. So if you build a sphere around the outside of the magnet, there must be a total of zero magnetic flux going through it, and since it's symmetric there must be zero flux through every point. So there's no flux on the outside of the magnet."
] |
[
"It wouldn't leave the outer sphere, but that may not be the point. We have all kinds of uses for capacitors, which act very much the same."
] |
[
"Yeah, the magnetic field is within the shell of the sphere but could also be set up on concentric spherical shells."
] |
[
"How do wasps communicate with each other?"
] |
[
false
] |
I live in Berlin, Germany, which every year in August becomes the wasp Mecca of the universe... I've noticed when sitting outside enjoying my sweet Rosinenschnecke that a lot of time can pass without any wasps attempting to feed on my delicious pastry. But once one stumbles upon it - beware - 5 or 10 of her friends will be arriving shortly. Do wasps (outside the nest) really have a means of communicating with one another and calling others when they've found a tasty food source? If so, how?
|
[
"You probably already know that honeybees communicate the location of food sources to their nest mates via a dance-like sequence of movements, known as waggle dance. Other bees use variations of that. Wasps inform their peers of the existence of nearby food by drumming their abdomen. Wasp considers your food delicious goes back to its nest and drums its abdomen letting others know there is delicious food around. This is possibly what is happening in your case.",
"https://www.sciencedaily.com/releases/2018/05/180515113553.htm"
] |
[
"Thanks,now i'l imagine a wasp rubbing her belly and drumming mettalica boom boom boom food heere time to paaaaarty."
] |
[
"imagine when you had to give directions, you had to do it in a rhyme.",
"\ngoogle maps would be interesting"
] |
[
"Why do many substances appear as white powders?"
] |
[
false
] | null |
[
"Most compounds are insulators, which means they have a band gap greater than 3-5 eV. (Visible light is around 1 to 3 eV) insulators cannot absorb visible light, because their band gap is greater than the energy of visible light, so they transmit that light. Large crystals of insulator see clear, like glass. When they are grounds into a powder, they scatter all wavelengths of light, and appear white."
] |
[
"i dont think spirit of the question was \"why do these powders appear white?\", but \"what is it about these chemicals that make white the most common color for certain powders?\"",
"one refers to the light spectrum, the other to chemical composition",
"i only post this because im a little curious myself"
] |
[
"Colour of a substance depends on the chemical structure, or crystal structure of the substance.",
"If the structure absorbs certain wavelengths of light, and reflects others, you will see the reflected wavelengths (only if they are in the visible spectrum, ~400-700 nm)",
"You see a lot of white solids because they don't absorb light in the visible spectrum, they reflect them. The combination of all visible wavelength is white.",
"Hope that helps. "
] |
[
"What percent of mental illnesses cannot be treated/managed?"
] |
[
false
] |
Basically the title, what percent of mental illnesses cannot be reasonably treated or managed and are just too extreme for any kind of normal living or recovery?
|
[
"This is a bit of a hard question to answer from available data. The basic concept of treatment resistance has seen a lot of research, and we can talk about that, but it takes a much higher symptom burden to cause the kind of impairment you're talking about. Some examples of what we do know:",
"*A manufacturer's trial of an antidepressant (using healthier/younger people with major depression only) will typically show about 1/3 of patients on the drug having a full remission of symptoms, 1/3 improving significantly, and 1/3 not getting better. In a study like STAR*D which took a much broader sample of more chronic/less-healthy people with multiple diagnoses, that might be closer to 1/4+1/4+1/2. This is for initial treatment; another chunk will respond to a second antidepressant, with a steeper fall-off for trials 3 and 4. This supports one common definition of treatment-resistant depression as having failed two adequate trials of antidepressants (that is, fair dose and long enough.) ",
"https://pubmed.ncbi.nlm.nih.gov/8827185/#:~:text=In%20summary%2C%20treatment%2Dresistant%20depression,for%20at%20least%206%20weeks",
".",
"*About 20% of patients with OCD don't respond to standard psychotherapy/medication. ",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5310107/#:~:text=Around%2020%25%20of%20patients%20do,been%20tried%20in%20resistant%20patients",
".",
"*Perhaps 30% of patients with schizophrenia don't respond to standard antipsychotics; of those, 60-70% respond to clozapine (so let's say 10-15% are left.)",
"*Response to standard treatment for anxiety disorders: 60-90%. ",
"https://www.nature.com/articles/4001852",
"So if you guessed that for many disorders, about 20-30% of people won't respond to a couple of first-line treatments, you'd be in the ballpark. That's where we take things up a notch. Electroconvulsive therapy, despite its reputation, is safe and highly effective (70-90%) in treatment-resistant depression. Newer treatments like ketamine and TMS can also have meaningful benefit. Likewise, the treatment options for OCD can get a lot more involved, including targeted brain surgery in extreme cases. ",
"That said, we're still just talking about inadequate response to available treatments. \"Just too extreme for any kind of normal living or recovery\" is a lot stronger than that, and more what we associate with certain forms of severe mental illness. Many people who receive no treatment or have suboptimal response still function well enough, or have periods of symptoms followed by improvement.",
"Practically speaking, non-response is often less relevant than inadequate treatment and suboptimal response. If a patient has managed to start receiving care and receive two adequate antidepressant trials, that's farther than a lot of people ever get. A tiny fraction of the patients who could benefit from ECT ever receive it."
] |
[
"There are a ton of factors at play but those unhoused neighbors constitute the large majority revolving door of psychiatry. Sadly, I'd imagine a good proportion of them could become medically stable if there was a good public safety net and public (mental) health was dealt with appropriately. If you think about all the ways they're disadvantaged (homelessness, poverty, food instability, medical problems, drug problems, legal problems, ...) even getting these individuals on a medication regiment – which often times takes titrating and even adjusting over months of regularly taking the meds – is next to impossible. ",
"There are some programs to meet these needs but they're hard to get connected to and all the problems above make it that much harder - most of them involve meeting individuals directly in the community. There's solid evidence now that providing free housing lets a ton of stuff fall into place (employment, sobriety, treatment & engagement). Best case scenario they get plugged into all the services they need and turn things around. That's sadly fairly rare. More often you get people who connect for a few months and then fall off for a variety of reasons (heuristically drugs and crime, usually to obtain drugs). Unfortunately and depressingly, the legal system houses tons of these individuals. Worst case scenario they die: killed by police, OD, physical health complications. ",
"One of the most profound moments in my training was when I almost stepped into human feces walking to the public hospital where I was working, and instead of thinking \"this is so gross,\" I thought something along the lines of \"that person must be in such a bad place to have to do this\"",
"Most places have community resource teams that can help if they're alerted. Here's SF's: ",
"https://sfmohcd.org/homelessness-support-and-resources"
] |
[
"This is a very informative response; thank you.",
"I've always wondered: I live in San Francisco and (not to get too graphic or sensationalistic) there are a number of (apparently unhoused) people dissociated who basically walk around all day yelling. What are the ranges of outcomes for someone in a situation like that?"
] |
[
"Do we create light?"
] |
[
false
] |
[deleted]
|
[
"[...] present since forever via energy transfer [...]",
"You're on to the right idea here. Everything that we experiences follows the laws of conservation of energy. That is, energy is never lost, it only changes forms or is given from one system to another.",
"With regard to light, the energy is being taken from your laptop battery and being converted into light via one of various possible processes. The light is simply photons (sub-atomic particles) being emitted with some energy. These photons have a certain wavelength and frequency due to their energy levels. We observe photons at these wavelengths as visible light."
] |
[
"not only your laptop.... but you emit light believe it or not... you emit a form of light in the infrared spectrum (we cont observe it with the naked eye).. you constantly emit light, and that light will escape into the universe and will probably interact with something else... maybe the telescope of an alien astronomer o.O"
] |
[
"It is assumed that the big bang was incredibly bright on all wavelengths and extraordinarily hot as well. Now that atoms are stable these days, and microwave background radiation is rather cold.. It would be much much less."
] |
[
"If there is no change in the environment of a species, is there an impetus for an organism to undergo evolution? (For example, tardigrades, who can survive in extreme conditions?)P"
] |
[
false
] |
[deleted]
|
[
"You're asking if there's evolution in the absence of natural selection. Yes, there is. ",
"Natural selection is the best-known driver of evolution (to the point that it's often confused with evolution), but even Darwin figured out ",
"sexual selection",
", and since the 1960s we've known about ",
"neutral genetic drift",
" as drivers of evolution. ",
"(I suppose you might argue that sexual selection involves the environment changing, since other members of your species are part of the environment.)",
"(In reality, since organisms are rarely if ever perfectly adapted to any environment, even in a completely unchanging environment there will still be natural selection toward adaptation, potentially in multiple different directions.)"
] |
[
"Indeed, over very long time scales organisms will in principle reach an \"equilibrium\" between drift and selection: drift increases the frequency of deleterious mutations, and selection decreases them. This is also one of the reasons the distribution of mutational effects itself changes over time. If an organism is poorly adapted to its environment, random changes are more likely to be beneficial than if it's already well adapted (in some cases beneficial mutations can actually be ",
" common than deleterious ones).",
"One way to think of this is that populations generally don't spend much time at a fitness \"peak\". They may cluster around it, or they can follow a path \"around\" the peak. The average distance from the peak will be somehow determined by the mutation rate and the population size. There's a statistical mechanical analogue: a system's mean deviation from its lowest-energy state is governed by the shape of the potential function acting on it, as well as the temperature. These are roughly analogous to mutations and drift, respectively: see ",
"Barton and Coe (2009), \"On the application of statistical physics to evolutionary biology\"",
" for more."
] |
[
"Evolution occurs due to selection pressure, which means that the species is in some way resource-constrained. Under selection pressure, the species may adapt to use the resources more effectively.",
"So in order for evolution to not occur, the species would have to be under no selection pressure. That means not only that it was in an environment that was not changing, but that there were no other species that would compete for resources, no variations in resource supply (for example, climate-related changes in nutrient availability), no disruptions in resource supply (for example, natural disasters), ",
" that the organism was already perfectly adapted to that environment. ",
"I am not sure what you meant by \"no change in the environment\", but I think it doesn't all of those requirements."
] |
[
"Scientists, tell us your science related mysteries?"
] |
[
false
] | null |
[
"Hi 12thman-Stone thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the following flair categories and contain no other text:",
"'Computing', 'Economics', 'Human Body', 'Engineering', 'Planetary Sci.', 'Archaeology', 'Neuroscience', 'Biology', 'Chemistry', 'Medicine', 'Linguistics', 'Mathematics', 'Astronomy', 'Psychology', 'Paleontology', 'Political Science', 'Social Science', 'Earth Sciences', 'Anthropology', 'Physics'",
"Your post is not yet visible on the forum and is awaiting review from the moderator team. Your question may be denied for the following reasons, ",
"/r/AskScienceDiscussion",
"There are more restrictions on what kind of questions are suitable for ",
"/r/AskScience",
", the above are just some of the most common. While you wait, check out the forum \n",
" on asking questions as well as our ",
". Please wait several hours before messaging us if there is an issue, moderator mail concerning recent submissions will be ignored.",
" ",
" "
] |
[
"‘Chemistry’,’astronomy’,’physics’"
] |
[
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"guidelines",
"/r/AskScience",
"If you disagree with this decision, please send a ",
"message to the moderators."
] |
[
"Does your metabolism slow down as you age and if so, how?"
] |
[
false
] |
The recent "How did you get fast?" ask reminded me of something I've wondered about: It's commonly accepted that your metabolism slows as you age, and it is often treated as a phenomenon apart from changes to lifestyle and behavior. However, if someone maintained the same level of activity, ate the same diet, and exercised to retain the same lean muscle mass, would they still experience a slowing metabolism? If so, wouldn't that imply that our bodies become more efficient as we age? I.e., able to do the same work with less energy.
|
[
"The age-related decrease in BMR is almost entirely explained by the loss of lean body mass. Once LBM is controlled for, the effect of age seems to be minuscule. In ",
"this study",
", age explained only 2% of the observed variation vs. 63% for LBM."
] |
[
"Well yeah, slightly lower. \"Significant\" in this context refers to statistical significance, not the magnitude of the effect. The 6.3% figure is relative to the ",
" variation after the effect of LBM had been removed. So overall it's still just ~2% of the total.",
"The factors underlying individual differences in BMR are somewhat mysterious, but I think it's safe to say that the body doesn't arbitrarily waste energy. The discussion section of ",
"this paper",
" lays out some theories that could explain the age-related slowdown."
] |
[
"Growth requires additional energy, so, relative to their size, kids have a higher metabolic rate than adults. But adults burn more calories overall because they are bigger."
] |
[
"if an airplane wing can take X amount of load, would a 2:1 scaled down version of said wing be able to take X/2 load, or is this not a linear relation?"
] |
[
false
] |
my intuition tells me this should be X/2 but my intuition (as a product design engineer) also tells me that there might possibly be some kind of relations that would alter these specifications a bit. I have no idea how to google this question because I don't really know what kind of typical set up or problem I am looking for. I'm not lazy, so any general guidance and pushes in the right direction are welcome, as long as I can somehow figure out the answer. Thanks!
|
[
"The simple answer is, planes that are smaller will take higher loads, relative to their size, than larger planes. According the the square-cube law:",
"\"",
"\"",
"This is part of the reason why ants can lift many times their own weight."
] |
[
"So if we scale the plane with a factor 2, we have to divide the volume (and therefore approx. the weight) by 8 and the wing area by 4. So the formula is: (original weight / original wing area) * (4/8). The factor 1/2 seems right if all other factors stay the same. (please correct me if I'm wrong)",
"However, if you include velocity in this story, other factors play an important role. You wouldn't put a giant Airbus engine on an rc plane. The rc plane will probably fly a lot slower. ",
"The ",
"lift formula",
"#Lift_coefficient) is: L= 0.5",
"v",
"Lift is quadratic in the velocity of the plane. This means that you will need a greater wing area to lift the same weight. Also, the factor Cl (liftcoefficient) is dependent on the wing profile (not a problem to keep the same as the original), the angle of attack (also not a problem to keep the same) and the ",
"Reynolds number",
". The Reynolds number is again dependent on the flight speed.",
"a lot can be told about that factor Cl, but I don't think it's of a big importance to the question."
] |
[
"This sort of dimensional analysis is extremely useful in prototyping and testing concepts using scale models. To get a decent understanding of the aerodynamics of a plane using a scale model, for example, you can (as you mentioned) scale the power to get an 'equivalent' speed, but you can also change the density of the medium through which it's flying! Same with boats; hydrodynamics of scale models of seafaring shapes is often done in different fluids than fresh or seawater to account for the different scales.",
"It's been a long time since I studied this, but it was one of the more fascinating parts of my early physics education in college!"
] |
[
"what's inside a black hole?"
] |
[
false
] | null |
[
"There's two sides to this question: What the math says, and how we interpret the math.",
"The math says that inside the event horizon, there is a dimensionless point of infinite density that we call a singularity. The problem is though: How do we interpret this when thinking about physical reality?",
"Well... the real answer is that we can't interpret the math into something that we can truly understand. We don't know what happens in the interior of a black hole. But even more, we can't know. There is no way that anything within a black hole can interact with anything outside a black hole. There is no way to send any information from the inside to the outside of an event horizon.",
"So from our perspective, the interior of a black hole doesn't exist. There is no way for it to interact with us. We can't know what's inside it, so the question actually moot.",
"You can interpret the math any way you like. That's as close as you're going to get to knowing what's inside.",
"My view: It literally doesn't exist. Of course, this depends on how you define 'exist'... but then we're arguing philosophy, not science."
] |
[
"My view: It literally doesn't exist.",
"Would your view change if you were an observer falling into a black hole? Would you cease to exist the second you crossed the horizon, or would your interpretation of the mathematics suddenly change?"
] |
[
"Ahh! and now we get into the subtleties of it all.",
"This is where the apparent paradox of causality violation arises with black holes. How can someone fall into a black hole in their own reference frame, but someone far away observe that it takes forever to cross the event horizon? Well, the answer is that what they both observe is unique to their reference frame. Basically, what exists relative to the observer depends on their frame of reference.",
"This of course lends itself to certain definitions of what exists means. In my case, exist means \"able to interact with.\" Why? Because if we can't interact with it, we have no way of knowing it's there. Thus, it basically has no effect on us.",
"The second you try to define 'exist' in a more abstract sense, you lose the specific threshold of what it means to exist. And then this becomes a purely philosophical debate.",
"We're not even sure the laws of physics as we know them hold inside an event horizon... but it doesn't matter, because nothing inside the event horizon can interact with anything outside the event horizon.",
"So my short answer:\nExistence depends on perspective and your definition of it. If I'm outside the event horizon, then the interior of a black hole doesn't exist. If I'm inside... well, then ... I guess it becomes a throwback to Descartes: \"I think therefore I am.\"",
"In the end, it becomes a question of philosophy and definitions."
] |
[
"It seems like a lot of species' natural poisons are actually just blood coagulants. Are there many examples of poisons that target other functions?"
] |
[
false
] | null |
[
"Blood targeting poisons are known as hemotoxins, there are also neruotoxins, cytotoxins, and myotoxins. Neurotoxins target the ability of nerves to function. One common target of neurotoxins is acetylcholine function, interruption of which results in loss of muscle function. Neurotoxins can lead to loss of motor function, sensory function (such as blindness), paralysis and death by asphixiation, . Cytoxins directily assault cells, through a variety of methods. One common way is to damage cell membranes, causing severe and indiscriminate necrosis. Myotoxins are similar to cytotoxins in that they cause necrosis, but specifically target muscle fibers. This may lead to paralysis and asphixiation (not to mention getting eaten by the animal...) The damage caused by cytotoxins and myotoxins can also indirectly harm the victim. The sudden increase in waste from necrosis can cause other organs to fail, especially the kidneys.",
"You should not that many poisons are ",
" lmited to just one of these categories. For instance, the spitting cobra's venom has both cytotoxic and neurotoxic affects. Don't get any in your eyes!"
] |
[
"Are you talking about Komodo Dragons?",
"Bacteria transferred from an animal's mouth to a wound are not a toxin themselves, but can produce their own toxins."
] |
[
"do those categories include a bacterial toxin, like those lizards (that I cant remember the name of?)"
] |
[
"If there was a bag of 10 balls, 9 white and 1 red and 10 people including you has to pick one randomly and who gets the red ball wins, does it matter what order you all pick, or is it better to go first or last with probability?"
] |
[
false
] | null |
[
"It doesn't matter.",
"The first person to pick has a 1/10 (10%) chance to win. So he has a 9/10 (90%) chance to not win. That means that the second person to pick has a 9/10 (90%) chance to get his turn (which only happens if person 1 doesn't win), but if he gets his turn he has 1/9 (~11.11%) chance to win. That means his total chance to win is 9/10 * 1/9 = 1/10 (10%).",
"Person 3 only gets his turn if both 1 and 2 don't win. That means that the chance that he gets his turn is equal to 1 minus the chance that either player 1 or player 2 wins. That means: 1 - (1/10 + 1/10) = 8/10 (80%). At that point, he has a chance of 1/8 to pick the correct ball, so his total chance of winning is 8/10 * 1/8 = 1/10 (10%).",
"You can extend the same line of reasoning for the other players and find the same outcome, 10%, for each."
] |
[
"It should be noted that it ",
" matter if people put the marbles back into to pot after they draw and the game is stopped once someone wins (sampling with replacement)."
] |
[
"Yes, because there's a chance that the game could end after the first pick, but because of the replacement every person has the same chance to win if they do get a pick. "
] |
[
"Will it ever be possible to create a direct image of an extrasolar planet in the same way we can view, say, Mars or Jupiter?"
] |
[
false
] |
I know that there has been some amazing images of extrasolar planets, such as those around HR 8799 by the Keck Observatory using motion interpolation. But, is there any possibility of acquiring an image in visual light - so that you could say "It's green" or "It's blue". Thank you!
|
[
"Will it ever be possible to create a direct image of an extrasolar planet in the same way we can view, say, Mars or Jupiter?",
"That's a tough question. I would say, yes. But the real question is the timescale. ",
"Most of the really incredible images of ",
"Mars",
" and ",
"Jupiter",
" were taken by orbiters (in this case Viking 1 and Juno respectively). When you look at the telescope images of ",
"Mars",
" and ",
"Jupiter",
", even by our best Earth-based telescopes (such as Hubble), they are significantly worse than those taken by orbiters. Even a planet within our solar system such as Pluto can be extremely hard to image from Earth - ",
"this was the highest resolution photo we had of Pluto",
" until ",
" when New Horizons did its flyby. SO in terms of imaging exoplanets by Earth-based observatories, there are some ideas in the works, but to really get a decent image, you need to get closer. This was the idea behind ",
"starshot",
", just accelerate a single chip camera to some relativistic speed so you can at least get close enough to something to get an image. But getting any kind of probe out to an exoplanet likely won't happen within our lifetime. It could be centuries or millenia before we get images from a probe. But assuming humanity keeps pushing and we don't get wiped out by some asteroid, war or plague, our grandchildren might see it. ",
"In terms of stuff within our lifetime, there are some ideas out there. Most of them involve just making the aperture bigger using inflatable lenses, ",
"constellations",
", ",
"bigger constellations",
"), ",
"deep space constellations",
", or ",
"graviational lensing",
") as a way to funnel more light into the optics. Some of these methods might yield images good enough to say \"it's green\" or \"it's blue\", and maybe even get an image roughly to the level of that pre-2015 pluto image. Using new types of ",
"hyperspectral cameras",
" we could even determine the chemical composition of the exoplanet to a surprising degree of accuracy (enough to even say whether there is water, oxygen or even signs of life). But in terms of actual images, we're going to be very limited in resolution. ",
"Telescopes can only get you so far. The best way to get good quality images of something is to go there and take pictures."
] |
[
"Pluto is roughly 1/2000 of a light year from us. So to view an exoplanet 50 LY away with the very blurry resolution of the image you link to would need an aperture 100,000 times the Hubble. Roughly 200 km. That's quite some constellation. I see formidable obstacles to doing optical interferometry over distances of hundreds of km!"
] |
[
"The hard part about interferometry is you need to be able to align things to within a fraction of a wavelength. Comparatively easy at radio frequencies, virtually impossible at optical wavelengths unless the telescopes are immediately adjacent to each other (large binocular telescope as an example)."
] |
[
"On the nature of 'time'."
] |
[
false
] | null |
[
"...perception of time ",
"You have to choose your words carefully here. An observer's perception of their own time never changes. What happens is that if you look at another observer moving at a large speed relative to you, all processes in that observer's frame (like the ticking of clocks and all biological functions) will occur slower than identical processes occurring in your frame.",
"It's very important that you can never notice anything different about time in your own frame, since one of the principles of special relativity is that all observers are equivalent, so you should not be able to tell if you are moving or not in any absolute sense."
] |
[
"You original question was a \"why\" question. The answer to a \"why\" question depends on what kinds of reasons you're looking for. If you're looking for a mathematical explanation the answer is that the universe (ignoring gravity for simplicity) appears to look like a 4-dimensional world which has a Lorentz symmetry as opposed to a Galilean symmetry. Galilean symmetry is the intuitive symmetry we expect where clocks that move relative to each other tick at the same rate and where there is no maximum speed. This happens to not be the real symmetry of the universe, and in fact Galilean symmetry is an approximation of Lorentz symmetry for speeds much slower than the maximum."
] |
[
"Thank you for that. I realise that 'perception' may carry certain baggage with it. Just to clarify, at the moment it is my intention to only be referring to particles during this series of questions."
] |
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