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What units are color charges measured in? Also, what is the formula for the force exerted between charges in the strong force, assuming it's small enough to write type in a comment? The color charge of the strong force is quantized, and you generally work in units where the color charge of each particle is 1. Unlike in electromagnetism (gravity), you never have macroscopic charges or currents (masses) where you might want to define a unit where the elementary charge is not equal to 1. At low energies, the strong force between two particles actually increases with distance F=-k d. That means that the potential energy increases as particles move apart. If you keep pushing them apart, they eventually get enough energy to form a particle-antiparticle pair that neutralizes the color charge of the two particles. Therefore, the strong force effectively acts only over short distances (otherwise it basically neutralizes itself through particle creation), and exhibits confinement which prevents particles with net color from existing on their own.
When two particles get too close together why don't they launch themselves due to their gravity? Your example gif violates conservation of energy. Very likely, your simulation is running into problems due to the diverging forces as the particles approach one another. In reality, if two particles with only an attractive gravitational force were to go straight into one another, they would become faster as they approached one another due to the increasing force of attraction. Their velocities would become (which any numerical simulation will struggle with) as they passed through one another. They would then slow down as they moved away from one another, such that the video would look identical going forwards or backwards. In reality, there are other forces at work, e.g., the electromagnetic force.
Why do we not see deadly mutations of 'standard' illnesses like the flu despite them spreading and infecting for decades? This is written like it's coming from an anti-vaxxer or Covid denialist but I assure you that I am asking this in good faith, lol. We do. The flu has been around so long though that most of us acquire immunity from our mothers to specific strains and have partial immunity from that to help fight against other variants. There are now many, many strains of the flu, some more dangerous than others. An example; "The 1918 influenza pandemic was the most severe pandemic in recent history. It was caused by an H1N1 virus with genes of avian origin. Although there is not universal consensus regarding where the virus originated, it spread worldwide during 1918-1919. In the United States, it was first identified in military personnel in spring 1918. It is estimated that about 500 million people or one-third of the world’s population became infected with this virus. The number of deaths was estimated to be at least 50 million worldwide with about 675,000 occurring in the United States." https://www.cdc.gov/flu/pandemic-resources/1918-pandemic-h1n1.html Many strains are fairly weak against an immune system that even has partial immunity, but when one pops up and has everything just right it can do some serious damage. Even today, although not as common, people can be hospitalized and/or die from the flu Edit: honestly what I found most shocking about that is how much the world population has increased in 100 years...
How fast do shooting stars go? Typically tens of kilometers per second. The minimum is 11 km/s (Earth's escape velocity) and while there is no hard maximum something faster than ~70 km/s is extremely uncommon.
How does human brain differentiate timbres of sounds? Consider a speaker, all they do is produce waves that correspond to whatever you are listening to. Our brain is the thing that decomposes this complex wave into different parts and enable us to percieve multiple timbres. Do we know how this works? I guess we have a biological Fourier transformator inside ourselves. The cochlea is a long bone in our inner ear. Different sections of the cochlea respond to different sound frequencies. These are then interpreted by the auditory nerve. So, in essence, you’re right as one could consider the cochlea a physical implementation of a frequency transform.
Do dogs get any benefit from fans? I've always been told that dogs do not have sweat glands. It is also my understanding that fans do not cool you down, but remove perspiration and that is what gives fans a cooling effect. None or all of this may be true, just wondering if pointing a fan at my dog while the A/C is out is doing her any favors. I also want to add that you can simulate the effect of sweating for your dog by periodically spraying a fine mist of water on its fur. (Also, dogs do have sweat glands, but only in the nose and paw pads. Humans, on the other hand, have sweat glands all over their body. Thus, sweating is a primary mechanism of temperature regulation for humans, but not so for dogs. It's not that dogs don't sweat at all, it's just that they don't sweat enough. Panting and blood vessel dilation are primary mechanisms for a dog.)
Why neuroimaging is not used for mental disorder diagnosis? Why do we still use questionnaires rather than brain imaging to detect mental disorders? Questionnaires seem likely to be affected by biases one has, whereas brain imaging would be more objective measure of the disorder, as I understand. For example in ADHD, as I understand, there are well-documentated differences in the prefrontal cortex, for which diagnosis could be made. I imagine that with neuroimaging we could help people before their life starts to fall apart before they have to come to the realization that something is truly wrong. We could also decrease misdiagnosis. Whenever I have filled a questionnaire, often recent events would create a huge variety in how I would respond to a question. Sometimes I would have extremely positive outlook, sometimes not. Sometimes the question can be interpreted in multiple ways, and then you have to figure which answer to answer. It seems to me that undiagnosed or misdiagnosed mental disorders impact one's life much more than likely costs of the better precision of diagnosis. So why neuroimaging is not the first step in disorder diagnosis? Is it less reliable than I believe it is? Is it expensive, if so, how much more expensive is it? Is it still unproven? There isn't always a one to one relationship between brain and behaviour. It's a lot messier than it seems. Yes, a certain set of behaviours may present a characteristic pattern of brain activity that may be significantly different from 'normal' activity. For example, there have been reports about hyperactivity of the basolateral amygdala in people with anxiety disorders compared to the general population. However, dysregulation within the amygdala have also been related to numerous other psychological disorders including OCD, PTSD, borderline personality disorder, depression, etc. In a sense, at this stage, it's not entirely a precise method as it doesn't really tell us much until the individual (or relatives) reports that they are indeed experiencing the specific symptoms of the hypothesized disorder. That is, the psychological and behavioural manifestations to the individual is more informative and significant when diagnosing and treating mental disorders, beyond brain activity/anatomy representations. I understand that self-report questionnaires will always have some bias involved. Whether it's about how it is interpreted, the current mood of the individual during reporting, or overall how they perceive their own experience. That's why heavy reliance on self-reports would be a mistake on the practitioners end. Other assessments are often involved if they are considered relevant including interviewing and cognitive tasks which tap into constructs such as concentration, processing speed, language, and reasoning capabilities.
How do we really know what our own galaxy looks like? So? We can use wavelengths other than visible to peer through gas clouds and the like and then find distances using parallax and other techniques to create density maps of the stars in our galaxy based on these we can make a map of what our galaxy looks like Edit: /u/OverlordQuasar pointed out redshift is useless this close to use and parallax is a much more effective means of measurement
If a brown dwarf is as hot as a cup of tea, what would prevent us from going right up to it and scooping out a bit of "star stuff"? Relevant link: I'm going to assume you have some way of getting to your brown dwarf and back. There are two obvious approaches for collecting a sample from something like a brown dwarf. The first is to treat it like landing on a planet: fly down, hover, collect your sample and fly back up. The problem is that stars have very, very high surface gravity, so you'd need extremely powerful rockets and lots of fuel to pull this off. I don't know anything about brown dwarfs in particular, but this paper suggests they have surface gravity on the order of 30 g's. The other option is to do a hyperbolic fly-by and skim your sample off the star's atmosphere. In principle this doesn't require any extra fuel because the star's gravity does all the work for you. The problem with this idea is that at apoapsis, you'll necessarily be traveling at or above the star's escape velocity. Assume a surface gravity of 30g and the same radius as Jupiter. Then the escape velocity is about 300 kilometers per second. To a first approximation, air resistance is proportional to the square of your velocity, so the probe would have to withstand incredibly high temperatures from frictional heating.
When power-cycling a device, does keeping it off for 30 seconds actually make a difference? I've always been told to reset devices like modems and routers by switching off and waiting 30 seconds before switching back on. Does it really matter? Does something actually happen during those 30 seconds? Rarely, it can. It allows time for capacitors to discharge and for SRAM to lose its contents. These days, pretty much all devices have good power-on reset circuits (usually built into the microcontrollers or processor supervisors) so no more than a second or two is necessary.
How does gravity slow time? This explanation bothers me. It doesn't actually explain anything. I know it is a standard physics introduction to GR explanation. It is what is taught. It is, however, junk. Special Relativity Twin Paradox - fine. Then we pack the vague stuff into acceleration at the end and pretend we've understood something. So... The returning twin has barely aged because 'acceleration', while the at home twin has aged 8 years. What if the round trip was sixteen years (by stay at home clock)? The acceleration phases would be the same - so where does the 8 year difference (from the previous thought experiment) come from? What if the trip out was 30,000 years - 60,000 round trip (by home clock)? It still takes the two identical sets of acceleration/deceleration (start, mid point stop and start back, end). How can the same acceleration/deceleration cycle on each of these trips account for the different ages of the twins (8, 16, 60,000 years)? The true problem has been swept under the carpet. There is no genuine explanation or understanding being provided.
How does my TV know which pixel to light up? It seems the internet is filled with explanations as to how a pixel works but no explanation regarding how the TV knows which to light up. I imagine new TVs have an easier explanation than the old cathode tube TVs. I would like an explanation of both please. Edit: Thanks for the replies...regarding the CRT, how can two magnets control 100,000 of electron at a time. If you have an animation i think that would be very helpful. These explanations are simplified, but should help. A CRT has an electron gun in the back. Somewhere between the electron gun and the screen, there are two electromagnets. The electromagnets should be perpendicular to each other. Since the electrons that are fired at the screen are charged and moving, it will be affected by magnetic fields. By altering the strength of the two magnetic fields, you can steer the electrons to the correct spot on the screen. For an LCD/LED TV, there's usually an active-matrix style (formerly, passive-matrix) addressing scheme. The TV has a certain resolution - and hence, a certain number of rows and columns. Each pixel exists at the intersection of a row and a column. You can picture these as a grid where the rows are on top and the columns are on the bottom, with the pixels in between. In order to have current flow, you need an electrical path - so to have current flow through a particular pixel, its row has to be activated, and its column has to be activated simultaneously. Only one row and one column can be on at a time, corresponding to a single pixel. The other pixels in that row don't have active columns, and can't turn on. The other pixels in that column don't have active rows, and also can't turn on.
Do gases have surface tension? For example there are two gases in a container and one of them is heavier/more dense and will therefore collect on the ground, is there some kind of surface tension where the gases meet? If yes does this have any relevance? Not really, and spontaneous stratification of gases is not as common as you might think. At least, not at normal gravity. Essentially, if it's a gas, it's doesn't have surface tension. Surface tension derives from the persistent attractive forces between molecules. Gases are defined by their complete lack of intermolecular forces, at least in the ideal case. Even under non-ideal conditions, the attractive forces present are not long-lived, and wouldn't give rise to anything resembling surface tension. In your example, if you did have two truly stratified gases, the only barrier to them mixing is the need to lift the heavier gas to a higher elevation to make room for the lighter gas.
How do we know how long Jupiter's storm has been going? We don't really, we just know for sure that it's been observed since 1830. There are observations of a spot from the 17th and 18th centuries but those may have been a separate storm, since there's a gap of about 100 years between those observations and what we know to be the modern great red spot. If it's the same storm it's been going for more than 300 years! If it's not, it's been about 190.
Was the Sahara ever underwater? Was what we now call Sahara underwater/part of an ancient sea/ocean? Yes and no, but . The Sahara is a massive region and parts of it have not always been on the same continent. It is roughly composed of the West African Craton and the Saharan Metacraton along with smaller later uplift and convergence zones such as the Atlas Mountains and the Mountains of the Eastern Desert . These smaller uplift regions at the edges of the African plate are relatively recent and are among the most complex systems on the planet. They contain a mishmash of oceanic crust remnants from the Tethys Ocean , volcanic formations and a host of deformed strata from various origins. The main part of the bedrock of the Sahara consists of the two cratons. The cratons are very old very stable parts of the lithosphere and have not been under any form of ocean possibly since their differentiation from oceanic crust at the start of plate tectonics. The West African craton came together some 2Ga ago (2 billion years). The Saharan Metacraton is even older. The Saharan Metacraton may have been partly and temporarily covered by the Pharusian Ocean some 700Ma ago, although most certainly most of that ocean will have consisted of oceanic crust created during rifting. So while yes, you can find ancient sea/ocean floors in the Sahara, nearly all of the Sahara consists of stable continental crust and volcanic formations. If we include inland seas and lakes the story gets considerably more complicated. The Sahara's climate has varied greatly over the course of geological time. A detailed answer is impossible (it would fill several volumes). Yet very recently geologically speaking the Sahara was indeed much wetter than it is today, during the African Humid Period between 16,000 and 6,000 years ago, see this map . During that time vast areas of the Sahara were submerged beneath the Mega Chad paleolake which reached all the way to the Bodele Depression . Additionally large lakes or lake existed in what are today the Algerian-Tunisian chotss Melrhrir, Gharsa, Djerid, and Fejej (west to east). Whether the Qattara Depression was flooded at that time is unknown but given the literature available to me it does not seem likely. The river Nile also seems to have created mega lakes in the region earlier during the Pleistocene (see here ).
Does anyone know how solar panels handle applied pressure? I'm working on an underwater glider and am researching various types of solar panels as a potential option for power. One of my concerns is with semi-flexible solar panels. I'm having a hard time finding data on whether those solar panels can handle pressure up to 300 meters below sea level. Thanks in advance for any help/answers! Your best bet is to design the panels to be inside a transparent hull. Also, there is very little light below 200m, so solar panels would be mostly worthless. May be even higher depending on the absorption spectra of water and the spectra used by the solar cells.
How fast could a rock planet spin before centrifugal force started doing strange things to it? Assuming similar mass and composition to Earth. Edit: strange things like becoming noticeably oblate, or becoming unstable. I assume if a rock planet was spinning fast enough if would fling itself apart. Edit 2: Maybe a better question: what would happen to the Earth if its rotation was gradually sped up. Well, as you might know, centrifugal force is already acting upon our own Earth. It causes the earth to 'flatten', causing more mass to be prevalent around the equator. In the study of the Earth's gravity field (or any planet's gravity field, for that matter) a first approximation of this gravity field would be a 3D sphere. Where the intensity of the gravitational pull decreases as the radius of this sphere increases. However, in real life we notice that due to the flattening of the earth (known as the J2 effect, extremely detailed explanation of one of the representations of the Earth's gravity field here. ) the mass density is larger around the equator, distorting the gravity field. Please note that the gravity field is also disturbed by other things, like mountains, large bodies of water etc. This effect is very important in spaceflight. When a satellite you're designing is supposed to go over a certain point close to the equator, it will receive an extra acceleration in the north direction is it is approaching the equator from the southern pole. Logically, it would also receive a southward acceleration when the satellite has passed the equator. You can imagine that when a celestial body that has a large enough mass to form an approximately spherical body, and you would increase its angular velocity, the planet would flatten out even more, until the planet is turning at such a large angular velocity that gravity and molecular attractional forces cannot hold the matter together. However, increasing the angular velocity the size and mass of a planet is going to require a large amount of energy. I do not have enough knowledge of atmospheric behavior to tell what would happen to the atmosphere at these large numbers of angular velocity. But: Most planets in the universe are formed by condensing gasses/particles held together by gravity. These particles are much more likely to 'fly away' when the angular velocity is too high than solid matter. These particles 'flying away' reduce the junior planet's angular momentum (when the particles that have flown away are not being considered anymore), if the junior planet expands again to its original radius, the velocity is smaller (due to conservation of angular momentum) and might be small enough for the gravitational forces to start forming a rocky-type planet. And thus it is quite unlikely that you will find solid rock-type planets being formed while turning at immense rotational velocities. Per illustration of the earth's rotational velocity: Consider the earth rotating and a person of 100kg standing at sea-level: This person would experience a force of 3.39 newtons, or an acceleration of 0.0339 m/s. This is much larger than the standard 9.81 m/s of acceleration you experience from gravity itself. A mere 0.35 percent of the gravitational acceleration. For anything 'strange' to happen, it would need to spin at a much larger rate
Do contact with the virus work as booster shots for vaccinated/recovered people? Kind of. The shot results in a predictable dose of antigen exposure, response, and zero risk of actual infection. An exposure to the virus will absolutely provoke a response that will have a “booster” effect, but how much of a response will vary tremendously based on the nature of the exposure, and there’s obviously a risk of infection. Even asymptomatic infections cause tissue damage in lungs, so one would want to avoid that, if possible. The booster effect exists in both cases, but they are not equivalent in safety, magnitude, or consistency.
Superfluid vs Hydrophobic material. What would happen if you had a container (say a fishbowl) made of a hydrophobic material and then filled the container with a superfluid? No specific kind of superfluid. Would the superfluid still seep through or would it maintain the shape of the container? It's important to note that the behaviours we commonly associate with hydrophobicity apply mainly to water. A hydrophobic surface is generally nonpolar and creates a large surface area without hydrogen bonds, so it's entropically favourable for water to avoid wetting the surface and bead up instead. Superfluid liquid helium, for instance, doesn't form hydrogen bonds and therefore wouldn't interact with a hydrophobic surface like water in any case. A superfluid's ability to "seep" through a container relies on the existence of (even small) pores in that container. If there are no openings for the atoms to pass through, the fluid won't seep.
Why do we become physically tired after a day of mental or emotional exertion? It makes sense to me that a body would become tired after a day full of physically demanding tasks, like hiking or swimming. But what is the science behind us becoming tired after a day of emotional trials? For instance, if I receive bad news during the day or have a very up-and-down experience hearing about a family member's condition in the hospital, at the end of the day I feel as tired as I would if I had run for a long distance or something. Does worry or panic or just a lot of thinking lead to a fluctuation of hormones that make me tired or something? Pretty close. It's the third stage of the General Adaption Model. Here's a nice graphic if anyone's interested 1) Alarm - adrenaline is released eliciting a fight-or-flight response due to some stressor. This is when cortisol is first released. 2) Resistance - body tries to adapt to stressor, and more cortisol is released. If the stressor persists (like a looming important test), the body starts to deplete its resources. 3) Exhaustion - exactly what it sounds like. This is probably what OP is referring to. All of the body's resources are depleted. Because of this, the body's functions can't return to normal until resources are replenished. If it persists, this can lead to immune suppression, ulcers (as a result of immune suppression), and increased risk of cardiovascular disease and diabetes. This is due to high levels of cortisol, a glucocorticoid produced by the adrenal glands that sit just above the kidneys. One of the functions of cortisol is to keep blood sugar levels up so that the body has the resources to adapt to the stressor, but if these remain elevated for too long, it causes problems like insulin resistance and increases chances of type 2 diabetes developing. Long term exposure to high cortisol can also suppress reproductive functions because if someone is in a stressful environment, it probably isn't the best situation to have offspring. This is why some women can skip cycles when under severe stress. During my undergraduate physiology lab, we actually took spit samples throughout the semester so we could do a lab practicing using an Enzyme-Linked Immunosorbent Assay (ELISA), which was completely new equipment for our lab and was awesome to be the first to use it. You could actually measure cortisol spikes before rounds of tests. The only not fun part was actually transferring the saliva from the small tubes into the tray the ELISA used (guess who has two thumbs and pulled that shitty job, that's right, this guy). Hope that elaborated enough and answered questions. TL;DR It's the third stage of General Adaption Syndrome called the Exhaustion Phase.
Are there any materials that like ice are less dense when solid than when liquid? I'm generally thinking human comfortable temperature and pressure ranges, but any info on this would be much appreciated, thank you! The words you're looking for are elements vs compounds (chemicals made with more than one element). A molecule is just two or more atoms joined and without charge. An element is a group of the same "type" of atom. For example: Nitrogen gas (N2) is a molecule consisting of two atoms of nitrogen. It's an element (because it only has nitrogen). Nitrous oxide (N2O) is a molecule consisting of two atoms of nitrogen and one atom of oxygen. It's a compound because it's two different elements. As to answering your question: I suspect that there are numerous compounds that have this property. However, it's easy to look up the density and properties of elements at various phases as they're well documented in reference tables.
Are there any major concerns of Maslow's Hierarchy of Need's? Is it still a good model? This idea was published within Maslow's theory of motivation in the 1940's. 75 years later, does it still hold water, and is there a better well supported idea that is relevant to how motivation of humans along this same vein? It is important to note that Maslow's (1943, 1954) five stage model has been expanded to include cognitive and aesthetic needs (Maslow, 1970a) and later transcendence needs (Maslow, 1970b). Psychologists now conceptualize motivation as a pluralistic behavior, whereby needs can operate on many levels simultaneously. A person may be motivated by higher growth needs at the same time as lower level deficiency needs. Contemporary research by Tay & Diener (2011) has tested Maslow’s theory by analyzing the data of 60,865 participants from 123 countries, representing every major region of the world. The survey was conducted from 2005 to 2010. Respondents answered questions about six needs that closely resemble those in Maslow's model: basic needs (food, shelter); safety; social needs (love, support); respect; mastery; and autonomy. They also rated their well-being across three discrete measures: life evaluation (a person's view of his or her life as a whole), positive feelings (day-to-day instances of joy or pleasure), and negative feelings (everyday experiences of sorrow, anger, or stress). The results of the study support the view that universal human needs appear to exist regardless of cultural differences. However, the ordering of the needs within the hierarchy was not correct. https://www.simplypsychology.org/maslow.html
Imaginary numbers are visualised as being on a number line perpendicular to real numbers. Does another type of number exist on a number line perpendicular to both (z-axis)? I remember seeing years ago in maths class. My question is, does another class of numbers exist on the number line in the 3rd dimension? Extending this idea, how about four, fifth, and nth dimensional number lines? I hope I'm making some sense! Well, R is a pretty well-defined and commonly used three dimensional number system. In general, you can define a vector space (over the reals) that has as many dimensions as you want/need, and these are all going to be isomorphic to R (mathematically this means that, in all important senses, they are identical). If you're primarily interested in properties this is usually the kind of structure you work with. The nice thing about complex numbers, quaternions and octonions (vector spaces of dimension 2, 4, and 8 over the reals) is that they have a nice (multiplication) structure as well; there is a consistent way of multiplying two, say, quaternions together and getting another quaternion. This is mostly missing from the other vector spaces; in R you still have the cross-product, but it has some undesirable algebraic properties like sometimes x = even if neither nor were zero. (We would say that R with the cross-product "has zero divisors" which is bad from an algebraic standpoint.) The problem with zero divisors is that you can no longer divide! For instance, in my example above, I know that and are both non-zero, but if I try and divide the expression x = by , then I get = / = which I know isn't true. Complex numbers, quaternions and octonions all allow division though; this is why dimensions 2, 4, and 8 are in some sense "more special" vector spaces than dimensions 3, 5, etc.
Is there any scientific reason to be worried about the calcification of the pineal gland? I hear a lot of pseudo-science people claiming that the calcification of our pineal glands is responsible for a myriad of problems. At first I didn't even believe that the pineal gland calcified, but apparently it often does, seen in x-rays: . I'm really curious what/if there are any consequences to this. Does this inhibit pineal gland function? Is this why we tend to produce less melatonin as we age? ( .) Even though the reasons behind calcification of the pineal gland seem not to be completely understood at this point, it is widely accepted that this does, in fact, happen. This paper from 2004 links decreased melatonin production in the pineal gland with the onset and progression of Alzheimer's disease. It suggests that not only does melatonin deficit strongly affect the ability of AD patients to maintain normal circadian rhythms, it also suggests that a deficiency in melatonin's antioxidant properties may speed the progression of AD. To address the link between the decrease in melatonin with calcification of the pineal gland, this 2007 study correlated increased nighttime calcium levels with decreased nighttime melatonin content. An even more recent study from 2008 found that Alzheimer's patients have a smaller ratio of uncalcified pineal tissue to calcified than patients with other forms of dementia, with depression, or control subjects. Alzheimer's patients also had a higher degree of calcification in the pineal than did other subjects. Degree of calcification was correlated with the individual's ability to produce melatonin. Alzheimer's patients notoriously have decreased melatonin production, and thus, disrupted sleep cycles. Anyway, yes, it appears that there is a link between calcification of the pineal gland over the life span, decreased melatonin production with increased calcification, and pathologies associated with decreased melatonin.
Is there a maximum size or volume of a single bubble under water? How does type of gas or fluid affect bubble size? What about other environment variables, like depth or temperature? A large enough bubble won't be stable because drag force isn't distributed evenly across it's surface. A small bubble withstands that deformation with surface tension, but once a bubble gets large enough then drag will rip the bubble apart into smaller bubbles. A similar phenomenon happens with drops of water falling through the air. You can't have one giant drop, it'll break up because of drag forces.
How does a hurricane affect life underwater? Obviously, hurricanes are big news for life on land, but what kinds of things go on underwater? Do animals retreat? Do coral reefs just hope that they don't break apart? Or is life below the surface oblivious? There was a post yesterday asking this question with regard to marine life. The conclusion was that some marine life can sense fluctuations in the pressure of the water (which alerts them that there is a storm). Sharks do this and since they want to swim in a certain pressure, the reduced pressure under a hurricane, causes them to swim deeper. http://www.telegraph.co.uk/earth/earthnews/3337163/Sharks-could-warn-of-storms-claims-research.html It seems likely that other organisms of similar complexity would also have there share of evolutionary tricks.
If Gravity Keeps Large Objects Spherical, What Keeps Things On The Atomic Scale Spherical? Pretty much as the title says. I'd guess electromagnetic forces, but then I thought about neutrons...So I'm confused. The nuclear strong force pulls neutrons and protons together to form an atom's nucleus. Just as with gravity on the macro scale, the force binds them tightly together. A sphere is the most efficient/tightest configuration to pull them all together, so that is what shape is formed.
How does soap work? And why is it seemingly so effective against essentially everything? Soap. What is it made of? What is the cleaning element? Why does it cut through oil so well but it needs to be added to water? etc... Soap is an amphipathic material, otherwise known as a surfactant. That is to say, it is composed of molecules that have an ionized and unionized end. The uncharged portion of the molecule will "stick to" other uncharged, or hydrophobic materials, primarily dirt and oils in the case of soap - the result of a statistical force favoring a more disordered state. The charged, hydrophilic ends then are attracted to water. As water runs over an area lathered with soap, water pulls on the surfactant, which is "sticky" to the oils and dirt, taking them with it. So the soap being pulled away by water pulls the dirt away as well. Soap is produced by subjecting fats to potassium hydroxide or sodium hydroxide - this ionizes the glycerol end of the fatty acid chain, and leaves the rest of the chain unaffected. The latter is hydrophobic, the former hydrophilic.
Is there a direct correlation between star size and average planet size? I know that there is a maximum size of a planet, due to the fact it will collapse under its own weight. But does a stars size/gravity have an affect on it's planet formation? I don't have a whole lot of time right now, so maybe someone will come fill in the gaps here. But yes, given the information we have right now, it seems like bigger stars can make bigger planets. Jupiter-mass planets are much rarer around smaller stars than they are around solar mass stars. And stars bigger than the sun seem to host more and bigger giant planets. The general reasoning behind this is that small stars have smaller proto-planetary disks. There's just less stuff around to make planets out of, so it's tough to get enough of it together to form Jupiter-type planets. Neptunes and Earths are much more common around the small stars, and that generally seems to be as big as it gets. Meanwhile the bigger stars have bigger disks with more material, so gas giants (and lots of them) can form pretty easily. This wiki page summarizes bits of it. Just reading the introduction to this paper (it's only 1 page) gives a decent summary too.
If there are an infinite number of prime numbers, why can it not be proven that there are an infinite number of twin prime numbers? I was just watching a video about primes and twin primes, and it was said that there is no proof that there are an infinite number of twin primes. Why is that the case? If there are an infinite number of prime numbers, then shouldn't each prime number have a twin being the next prime number above it, with the chain going on infinitely? Sort of like a weird inductive proof? Twin primes are not a prime and the next prime above it. Twin primes are prime numbers that differ by 2. So, for example, 11 and 13 are twin primes, 17 and 19 are twin primes, but 37 and 41 are not. We do know that primes get, on average, sparser as one gets to larger and larger numbers. As you say, whether there are still an infinite number of cases where the next prime is just 2 greater than the previous prime remains an open question, but recent progress has shown that there are infinitely many primes separated by 246 or less.
Do people who live in the desert have less oxygen to breathe than people who live in the woods? I understand that plant life converts carbon dioxide to oxygen, but I wonder if the extreme locations can create a measurable difference. Furthermore, I wonder if this difference can have any effect on humans like differences in altitude can. Air on Earth is fairly well circulated. There's about the same amount of oxygen in most places. However, if you live at altitude, the lower air pressure and density means that less oxygen makes it into the body. People who live at altitude for many generations (such as in Nepal or Peru) have adaptations like more hemoglobin in the blood to help compensate.
Why haven't species developed more eyes? It may sound like a stupid question but it seems odd to me that so many animals have only two eyes. I know a lot of herbivores have developed eyes on the side of their head to allow them to see predators from behind them, why haven't they just developed eyes on the back of their heads, so as not to have decreased visibility in front of them? Species don't develop new traits specifically to accommodate some need. Mutations are entirely random and only "stick" if it increases survivability long enough to become homogeneous among the population.
AskScience AMA Series: We are geoscientists, emergency managers and communication specialists working on the ShakeAlert earthquake early warning system in CA, OR and WA. Ask us anything! We are geoscientists, emergency managers and communication specialists working on the Pacific Northwest ShakeAlert earthquake early warning system in CA, OR and WA. We're here to raise awareness and answer questions about the new early earthquake warning system, earthquakes and Pacific Northwest hazards in general. We'll be on at 11-2 PST (2-5 ET, 19-22 UT), ask us anything! Usernames: , , The public alerts via WEA ( Wireless Emergency Alert Systems) are not including a countdown to when shaking is expected to arrive. There are a variety of reasons for this including uncertainty in in the travel time of earthquake waves through the rock between you and the earthquake and the fact that even the early "P" wave that triggers the system can be damaging when close in to a large earthquake. Technical users and licenced app developers can incorporate countdowns that are calculated assuming a average travel time for the "S" waves that are usually the first arriving damaging waves and your distance from the origin or "hypocenter" of the earthquake. The "quake alert usa app" does provide a countdown to subscribers. Bill Steele ,University of Washington, PNSN
Why can't they just stop diverting the rivers so as to replenish the Aral sea? This is something that has bugged me about the Aral sea since I learned of what the soviets did to it. I understand the water is still being used for agriculture in Kazakstan and Uzbekistan, but the devastation of losing the 4th largest lake in the world would seem to me to outweigh that. Am I missing something here? They just had a "Global Disruptive Tech Challenge 2021: Restoring Landscapes in the Aral Sea Region" in April, but none of them discussed even partially returning the rivers. In short, because the economies of Kazakhstan, Uzbekistan, Turkmenistan, and Tadjikistan are all heavily dependent on the agriculture made possible by the irrigation projects, inefficient as they are/were. This discussed in virtually any paper proposing solutions to refilling the Aral Sea, i.e., that the economic and societal fallout of ending all of this agriculture are not offset by the ecological or economic benefits of refilling the Aral via this route. For complete discussions check out Badescu & Schuiling, 2010 , Micklin, 2014 , or Micklin, 2016 . In the published literature (including some of the above), there are certainly solutions which involve modifying the irrigation and agriculture (e.g., trying to make the irrigation more efficient so less water is lost, switching to less water intensive crops than rice or cotton so less water is needed) with the goal of delivering more water to the Aral through its original sources. However as discussed in the linked papers (and others), it's not a viable solution now, ~60 years after these projects started, to simply upend the economies of 4 countries by stopping the diversion completely.
Does probability still exist if the results are already determined? One way to consider this is that probability is a measure of the uncertainty that a person has in the outcome. From your point of view, you have no information and the chance is 50%, but from the point of view of someone who knows where the price is, there's no uncertainty. Or rather, the entropy of the results you expect is related to your uncertainty. You have 1 bit of uncertainty and the person who knows the answer has 0 bits.
What causes different materials to expand or contract at different rates? Recently finished the thermodynamics unit in physics, and wanted to know what causes different materials to expand or contract at different rates? Does it have anything to do with the heat capacity, or are they two separate things? (I am aware that it is called the "coefficient of linear expansion" btw) Intermolecular bonding energy. Heat is atomic kinetic energy, right? Well, if a material is bonded to itself really strongly (tungsten), it will take a lot of energy (heat) to force them to spread out. If they are weak (plastic), they will spread out a lot further with application of the same amount of energy.
Is there a difference between "strong" and "tireless" muscle fibre on a biochemical level? In other words: Is there a difference between the muscle fibre you would find in a marathon runner's calves and the one in a weigthlifter's biceps/triceps? If not, what determines these two attributes? Relatedly, how would "pumping" 0.5 kg weights for long periods of time affect one's ability to do pull ups (i.e. straining the same muscle group with forces of wildly different magnitude). Muscles consist of several types of muscle fibers. The ratio of different types varies with exercise and function of the muscle. Two main types of muscle fibers are glycolytic (aka fast twitch), which are not very efficient, but are very fast to respond; and phosphorylative (aka slow twitch), which are very efficient, but not very fast to respond. Generally speaking, muscles that are exerted over extended periods of time (for example, your back muscles, which work all day and night) will preferentially use glycolytic fibers, because efficiency is paramount for muscles with long periods of utilization; meanwhile, muscles that are exerted in short and fast bursts will preferential use phosphorylative fibers, because speed is more important than efficiency for those muscles.
It seems like a tail would be a useful appendage. Why did humans lose theirs? I understand that it originally helped with balance and mobility, and I'm guessing that those tasks were taken over by higher brain function and leg muscles, but wouldn't I be even more balanced and mobile with a tail? Seems like it'd be an evolutionary advantage to have one.
Why is Tritium so ridiculously expensive? I am a huge fan of self-powered radioluminescent light sources powered by tritium like keychains. For a long time I have been wondering why isn't there anything more powerful (like a flashlight) since such keychains output is something like couple hundred microlumens. After a quick web search I found out that tritium price is in the range of 30.000 USD per gram making it one of the most expensive substances on Earth. I would like to learn why is that so. From what I understand tritium is produced as a waste product in heavy water moderated reactors in quantities exceeding commercial demand and that it can also be made from lithium (which is a common and cheap metal) by neutron capture. Is it so difficult and expensive to separate tritium from deuterium in reactors moderator? Is it so difficult to insert a lithium rod into an ordinary nuclear reactor in order to irradiate it with neutrons and then extract resulting tritium? I wish to understand difficulties behind tritium production and where does the high cost come from. a.) It's got an expiration date. You've got a half-life of about 12 years, which means that you constantly need a new supply of it, and that any light is going to die, and any manufacturer is going to need to anticipate a continuing production line, not just buy up a lot at once. b.) It's not naturally occurring - all tritium comes from nuclear reactions, so there's no source of it out there to be cheaply exploited, you need to contract with a nuclear plant. c.) It's radioactive - on its own, it's not especially dangerous, but if it's inhaled or consumed, it can hurt people, which means that the costs of storing it, shipping it, and working with it are much higher. d.) No economies of scale - since the entire marketplace of tritium is pretty small, and the process to create it is pretty specialized, you don't get to spread the fixed costs over a lot of products. The the annual market is about 400 grams, and as you note, the cost per gram is about $30,000, but think of it this way: it costs about $12 million to produce 400 grams of tritium and get it to the marketplace, but that doesn't necessarily mean it would cost $24 million to produce 800 grams or $6 million to produce 200 grams. It might cost $11 million just to get tritium out there, and after it's set up, then maybe each additional gram is fairly cheap. But you gotta start somewhere. So it might be that all the tasks involved are scalable, and tritium could get much cheaper if there was demand. But getting started is so expensive, and demand is pretty small, so it's a niche product.
Will a person burn more calories a day by living in a colder environment? Yes. Your body uses more energy to generate heat and so you lose more calories. This is why when people go to the arctic and antarctic they have pretty extreme diets which include things like eating whole sticks of butter.
Why do flu vaccines need to be adapted to the latest variation but not others such as MMR or chickenpox? In other words, why do you need a new vaccine each year for Flu but for many you get it early on and are set? If it is a matter of flu viruses mutating, why isn't that the same case for other diseases? Does flu mutate faster? The influenza virus (an orthomyxovirus) is indeed more likely to mutate, due to its segmented genome. These segments are far more likely to undergo reassortment through high-frequency recombination, resulting in genetic shifts (which are responsible for pandemics). At the same time, there are also genetic drifts (which occur through genome mutations that also occur in other viruses) due to the error-prone viral polymerase. some more info here, but unfortunately in Spanish only.
Why can't we see the Pacific Garbage Patch on satellite pictures? We've all seen pictures of the patch like and of the Great Pacific Garbage Patch. We've also been told it covers an area twice the size of Texas. Something isn't adding up though because if an area twice the size of Texas were as dense with trash as those pictures, it would be blatantly obvious on satellite pictures of the earth. When you look at said pictures of the ocean, there is clearly no brown patch twice the size of Texas in the middle of the ocean. What is going on here? Are the pictures of the patches just particularly dense, and relatively small, sections? The overwhelming majority of plastic in the ocean garbage patches are broken apart to millimeters in size from friction and sun weathering. You will not see this plastic from a boat, much less from space as it's essentially a transparent density. The pictures you are linking to are generally from debris which can easily get that dense if near a large population center. Out in the ocean, things are different. 88% were less than 10 mm in largest dimension, and most had characteristics suggesting physical deterioration such as brittleness, rough edges, or cracks. It is likely that plastic pieces ultimately become small enough to pass through the 335-μm mesh net used in this study - (Law, et al.) The plastic from say a milk jug is still there, but now in smaller bits. In the North Pacific central gyre, there is about 5 kg of plastic for every square kilometer of open ocean, this was measured to be six times more plastic by mass than plankton in the same region. The plastic can stick around for awhile because of the ocean's currents. The dominant clockwise gyral currents also serve as a retention mechanism that inhibits plastics from moving toward mainland coasts. A recent surface current modeling study simulated that most of the particles from our sampling area should be retained there for at least 12 years - (Moore, et al.) Moore, et al. A Comparison of Plastic and Plankton in the North Pacific Central Gyre . . 2001. Law, et al. Plastic Accumulation in the North Atlantic Subtropical Gyre . . 2010.
Why is there suddenly static on my car's radio when I'm close to a bus? I've noticed this happening, when city buses get closer my radio fritzes out and turns to static. Think about the radio signal your car is receiving. When next to a bus, the signal reflects off the bus and instead of having f(t), you now have f(t) + α f(t-δ). With a bus, the coefficient α should be close to -1, because a bus (presumably metal) is much more dense than air. So what you end up getting is something that looks like f(t) - f(t-δ), which in essence cancels out your signal and you get static.
Would taking cooked meat out of the fridge, warming it, and then putting it immediately back in the fridge make it go bad? My mom has always told me not to do this, but I'm not sure if it's true. If it, what's the reason behind it? I have a bowl of ground meat that I just warmed and I decided I didn't need it now. I'm not sure whether i can just stick it back into the fridge while it's hot or if I should wait! Meat in your fridge contains pathogenic microorganisms. They divide very slowly (if at all) in the cold fridge, but much more rapidly at room temperature. Air in your kitchen also contains pathogenic microorganisms, some of which would grow rapidly on nutrients they can extract from meat. These pathogenic microorganisms can hard you in two different ways. Some of them, when ingested, will divide in your body and make you sick. These are typically killed by proper cooking. Some of them secrete toxins that make you sick, and those toxins can persist long after the microorganisms stop dividing or die. These toxins may or may not be destroyed by cooking. So, every time you warm meat up, you give the pathogens in it — as well as any that might land on it — a bigger opportunity to grow and secrete toxins that might harm you or kill you. On the other hand, most of the risk of those pathogens and toxins is mitigated by properly preparing the meat. So if you re-heat the meat to a proper meat cooking temperature later, you will probably be OK. But if you just re-thaw it and eat it, you are putting yourself at higher risk of food poisoning. How high that risk depends on a variety of things, including whether the meat was properly prepared to start with, how long it was left out before being initially refrigerated, as well as how long it was out before being subsequently refrigerated. In short: you mom isn't wrong, but you might be OK. I definitely wouldn't make a habit of it.
Interesting math problem that's driving me crazy There is a random whole number of indeterminate length in front of you. You can only see the ones column (last digit) of it. How can you determine what this number is? You can perform any mathematical manipulation to it, but you will always only be able to see the ones column (even if it becomes a decimal, you will only see the ones column). Apparently the solution is relatively simple and uses basic operators (+, -, *, /, %, etc.) but I haven't figured it out yet. Count the number of times you have to subtract 1 until 0 in the visible column is followed by 1 rather than 9? Works only if the starting number is positive, so doesn't fit everyone's definition of "whole number". I am not a mathematician.
Could Earths atmosphere become Venus-like? Is it a real threat? Yes. We think that Venus got the way it is because the temperature increase due to being closer to the Sun is just enough to drive the carbonate-silicate cycle in the other direction to what it is on Earth, and preferentially create carbon dioxide over carbonate rocks. Earth has an enormous amount of carbon trapped in carbonates and if the temperature of planet increase enough, it's possible that the same thing could happen - those rocks would be weathered and the formation of carbonates would not happen as readily, leading to the release of carbon dioxide, which acts as a greenhouse and increases the temperature more. If you get into this kind of effect it is called a positive feedback, and the raise in temperature will only serve to raise the temperature more. At some point you would get the oceans boiling off, and since water vapour is also a greenhouse gas, this would make things even worse. So yes, it's possible, but would take hundreds of millions of years and would most likely be quite a gentle increase in temperature until some 'inversion' point was reached where the positive feedback took over. Some people think the warming we see at the moment will eventually give way to a cooling period and potentially even an ice age (with these kind of cycles definitely happening in the past) but in truth we don't know enough about climate forcing to predict which way we'll go. There's a lot of comparative planetologists that look at current Venus and Mars as potential end-states of Earth's future climate.
What spesific mechanism stops one lump of matter from occupying the same space as another? Looking at different pictures made by electron microscopes got me thinking, matter looks solid enough but physics tells us its 99% nothing. So then, what stops my glass when put on the table, from ever so slightly occupying the same space as the table? Thanks in advance. G The facile answer is "electrostatic repulsion" between the electrons in matter - but that isn't really the case, since most atoms and molecules are, on the whole, electrically neutral - as would be a mix of nuclei and electrons all crammed into the volume of a normal molecule. Really it's the fact that electrons are a special kind of quantum particle called a "fermion" (after Enrico Fermi). Fermions have a weird symmetric property that prevents any two of them from occupying the same quantum state. The weird property that it takes 720° of rotation to bring a fermion back to its original pre-rotation state. That is weird because we're used to the idea that after only 360° of rotation any system looks just like it did before the rotation. Here's how that works: Rotating a single fermion (like an electron) by 360° has the effect of multiplying its wave function by -1 everywhere. Bizarre but true -- it takes 720° (two full rotations) to see the fermion exactly the same way. I won't get into why in this post, it just is. A system of fermions has the opposite symmetry of a single fermion - rotating the two fermions together by 360° has the effect of multiplying the total wave function by 1 everywhere, since you get a factor of -1 for each of the two particles, and (-1)(-1) is just 1. But two particles in have the same wave function as a single particle in that state, multiplied by 2. So if you start with two electrons in exactly the same state, and rotate the system by 360°, one method of reasoning gives you a factor of -1 and the other a factor of 1 in front of the wave function. The only way they can both be right is if the total wavefunction is 0, since (-1)(0) and (1)*(0) have the same value. That means the wavefunction to be 0 everywhere, which means the probability of ever finding two fermions in the exact same quantum state is always 0. That in turn means putting two electrons into the same location in space requires exciting one to a higher energy state to make their two wave functions slightly different. Exciting one of them costs energy, which acts like a repulsion -- if it costs a lot of energy to put two molecules in exactly the same place, then you have to supply that energy by pushing hard if you try to compress them together. Fermions are counterintuitive and bizarre, but without them there would be no solid matter - bosons, the other main kind of quantum particle, are more gregarious and matter would tend to condense into very dense blobs rather than remaining relatively spread out. The Universe would be very different, and probably wouldn't contain people. : You can't put two electrons into the same place without exciting one by giving it more energy. That effect, not electrostatic repulsion, is what keeps electrically neutral atoms from occupying the same space.
A meta-science question. Wherever you are in your career, has your H.S. education been predictive your career in science (e.g., your ability or interest in science)? Specifically, what role have your H.S. math & science classes played in your career in science? I'm especially interested in this after seeing , which I highly recommend. I'm an un-natural example, I graduated from a Technology magnet high school with a concentration in chemistry, I was the first declared major in my college class, majoring in chemistry, then went to grad school in chemistry, and I now work as a chemist. So yeah...I've known I wanted to be a chemist since early on in high school. A good friend of mine graduated from a Waldorf High School, pretty much the opposite of me, in which science class was "let's go look and the flowers, how about writing a poem about the flowers." He's now a chemistry professor at one of the best liberal arts schools in the country. So draw your own conclusions.
Questions about the phylogeny of Echinoderms... re-evolution of radial symmetry? Homologous structure to Chordates? Wikipedia doesn't really clarify their phylogeny too well. Looking at a tree of life of the phyla of Animalia, it would imply that Echinoderms like starfish branched from Chordates relatively recently compared with the advent of bilateral symmetry, which is common to most Animalia phyla. However, Echinoderms for the most part have 5-point radial symmetry whereas Chordates are bilateral. I have two questions in this: first, are echinoderms indeed descended from a bilateral common ancestor of most of the bilateral phyla, and if so why and how was it evolutionarily advantageous to redevelop radial symmetry or by what mechanism was it redeveloped? Second, somewhat unrelated: chordates mostly have 5 appendages: two front legs/arms/fins, two hind arms/legs/fins, and a head; is this a homologous arrangement to the 5-point symmetry of many echinoderms or was it a separate development? Thanks for any and all clarification! Hi, Developmentally, echinoderms start as bilateral organisms; check out these echinoid larvae. The pentameral symmetry shows up as they grow up. Keep in mind that pentameral symmetry also is fundamentally bilateral - the bilateral symmetry group is within the pentameral one. There are also tri-radial early echinoderms. Some echinoderms can also rarely have more than 5 limbs, suggesting that the pattern of developmental repeats is a matter of having the right amount of a chemical (I can give a reference if you want to read about some crinoids that demonstrate this). There are of course plenty of echiconderms that have secondary bilatteral symmetry; holothurians, irregular echinoids. Why was it developed? I don't think there is a good known answer to that. Why is it beneficial? Because it is omni-directional. 5-limbness in chordates is neither homolgous or similar beyond the superficial to that in echinoderms.
How does the body eliminates fat tissue? I have been changing my life style, eating habits and exercising more. And it made me wonder, how does my body eliminates the fat issue previously stored? It depends on what you mean by fat tissue. Your fat, like the fat in your belly, is made up of huge adipocytes 100x+ more voluminous than fibroblast cells. These adipocytes are tethered together and packed densely with capillaries and larger vessels wending through. When you lose weight due to exercise or eating habits these adipocytes shrink in size (they're undergoing lypolysis). Basically, the lipid they've been storing is being burned up, so they shrink. If you continually run a calorie deficit then eventually, and here the research is incomplete, your fat cells will decrease in number as well. The thought is that there is a certain turnover rate of fat cells, atomic labeling studies show ~10% of adipocytes turn over every year. So, unless they are replaced at the same rate, you will eventually decrease the number of adipocytes you have. Eating certain foods, and having a calorie excess, can lead to more pre-adipocyte stem cells to decide to differentiate into adipocytes. Just so, if you're running a deficit fewer pre-adipocyte stem cells will differentiate into adipocytes. So, over time, you'll lose cells naturally and they won't be replaced if you are restricting your calorie intake. So you lose fat by the cells shrinking, and by the cells dying.
How rigorous is the science behind programs like p90x and Insanity? I'm trying to start a new workout plan, and I'm wondering if programs like p90x and Insanity were conceived through real scientific method, or if they are just using guys in lab coats to sell a product. You should probably be aware that the state of exercise science is pretty crappy. It's easy to blame scientists for this (and, to be sure, in many ways they to blame), but a great deal of the crappiness also comes from the difficulty in securing funding, finding willing subjects who will conform to the demands of the study, and control for a large number of confounding variables. Factors like this are why coaches often don't take peer-reviewed exercise science literature seriously. Essentially no workout program is designed by "science", unless by "science" you mean decades of trial-and-error combined with anecdotal evidence and folklore from hundreds or thousands of coaches and athletes, often with some attempt to tie it to theory or an understanding of anatomy and adaptation. This is often termed "bro-science". In some cases it is far superior to the real science in the field. Circuit training programs like p90x and Insanity are not magic. If you're completely unadapted strength-wise, you'll get stronger. Your metabolic conditioning will improve. You'll probably shed body fat. The basic principle underlying short, intense workouts (and their superior utility relative to long, low-intensity cardio-fests) is well attested both in the scientific literature and in bro-science. Beyond that, it's hard to say what'll work for you. Exercise programming, by its very nature, is something very individual. Pick something you like and stick with it.
How does a buried seed know where "up" is? First of all, a seed has a plumule (plant shoot) and a radicle (roots). They grow due to a hormone called auxin. High concentration of auxin in the plumule increases the plasticity of the cell wall and leads to an increased cell elongation. For example, if the plumule were to grow horizontally, gravity pushes down the auxin to the lower cell wall. This causes the lower cell wall to increase in plasticity and increases elongation of the cell walls while the upper cell walls grow with a normal elongation. Because the lower cell walls have a higher elongation, this causes the plumule to bend and grow upwards. In the radicle, the same thing occurs. However, in the radicle, a high concentration of auxin decreases the cell plasticity and cell elongation. This causes the the top cell walls to grow with normal cell elongation while the bottom cell walls grow with decreased cell elongation, making the radicle bend and grow downwards into the ground Heres a diagram which makes it easier to understand
Why do so many people need vision correction, while animals seemingly don’t? There is currently a myopia epidemic. Here's a general article with some stats: https://www.aao.org/eyenet/article/facing-the-myopia-epidemic And here is an older Nature piece: https://www.nature.com/articles/519276a You can find many more by googling myopia epidemic or by searching this sub for myopia. We don't really know why it is happening. There is some evidence that being exposed to sunlight when young is a factor (in preventing onset), but nothing conclusive.
Why do a lot of the Earth's peninsulas seem to point the same direction? The broader point is that there is no geologic reason for peninsulas pointing a particular way. That there happens to be more pointing one way (which is again, actually arguable and also gets into how big a landform allowed to be while still calling it a "peninsula" which does not have a formal definition in terms of size) is random.
are black holes super cold? My thought was black holes are so powerful that nothing escapes so they must be very cold. Secondly if some heat escapes does escape does that mean the area around a black hole is Super hot? Thank you for your answers. The temperature of a black hole (due to Hawking radiation) depends on its mass: the more massive it is, the colder it appears to be. Astrophysical black holes are quite cold; a black hole with 5 times the mass of the Sun is about 10 K, meaning that radiation is entirely undetectable. Tiny black holes that could conceivably be created by high energy cosmic ray collisions would be much hotter and evaporate very quickly.
What process does a Quantum computer undergo, at an atomic level, to "read" Qubits, and how do the Qubits collapse into the state which solves the task? I'm doing a project on Quantum Computing and I've hit a bit of a wall when it comes to Qubits being in the "right" state as it were. As an example, if a Quantum computer were asked to find the two prime factors of a number (like in decryption/encryption), how would the Quantum computer read the selection of Qubits to give the correct solution? The only way I can think of this happening is to have a selection of logic gates that somehow collapse the Qubit into the correct state when observed; however, I'm not too sure how this actually would work with Qubits. Any overview/condensed answers would be as much appreciated as those which go into a more atomic/chemical depth about how it would all physically function. Cheers! I am not entirely qualified to answer this, so please correct me if I'm wrong and I hope someone answers you more in depth. You need to keep in mind that collapsing a quantum state is done with respect to a basis, but that doesn't mean that you create the state out of nowhere, the system already is in a given state, which will be the result of whatever calculation/gates you've done, and that is the "correct" state, the task is solved through the interaction of quantum states, no collapsing involved! So what you need to do is read out the final state the system is at after all calculations have been done. As to how that's done, it depends on the system and what is used as qubits, there's spin qubits, qubits made of pollarized light etc. Usually you just need to use the tools and measurements available to you in the experimental set-up to try to find out information about the state of the system. For example, when it comes to using electrons spins as qubits, Loss & Divicenzo proposed getting the electrons into a quantum dot with a given set of magnetic properties so that it would be influenced by the electron spin, and then you would measure the magnetization of the whole dot. Similarly, you can measure the current that flows through the system which is usually heavily affected by the spin state of the electrons, or the charge distribution, and figure out what state the system must be in for that to happen. So, generally from what I know, you don't just simply collapse the system by measuring it directly, you just create an experimental set-up where by measuring properties of the system, you can reverse engineer the quantum state it is in. Again, the in depth explanation about how that's done would depend on what is being used as qubits, how the computer is designed etc, there's tons of papers that focus on understanding how different qubit states affect physical measurable properties of the systems just to help create different trustworthy read-out options.
Why does adding an iron core to a coil increase the flux density? So the current in the coil generates a magnetic field. Why does adding an iron core to the centre increase the flux density? I know it's something to do with the generated magnetic field reinforcing the domains that reinforce the field, and shrinking those that oppose it. But I don't exactly know what that means. What is a domain? A domain is a chunk of matter inside a body whose component atoms have their electrical spin aligned in the same direction. Meaning, if you were to rip out that chunk of, say, iron from the whole, it would act as a magnet. Normally, any given piece of iron has many domains, all going in different directions, not one strong enough to expand and magnetize the whole. But when you expose the iron to a strong magnetic field, individually each atom moves to align its spin with the field. On a higher level, this causes the domains to shift, align, and merge into one, giving you a temporary magnet. Since this new magnet has its own magnetic field, the result inside the coil is an increase in the intensity of the magnetic field at each point, or an increased flux density on the whole.
For the vast majority of Earth's history, there was no life on the surface. What did the landscape of the Earth look like before plant life, or land animals? This is a strange question, but it's bothering me. I don't think I've ever seen an artists impression/depiction of what Earth's surface has looked like for most of its lifetime. I remember in Walking with Monsters they depicted it as a dry, desert, arid landscape. What would it have looked like? If the Earth was stripped bare, would the rocks be grey? Yellow? Brown? Would it be dusty, muddy, or sandy? It's actually a really fascinating question and gets at the myriad of ways plant and animal life (and especially plants) influence the processes active at the surface of the Earth. This is a pretty cool review (but short) article on this subject, which touches not only what we (generally) think landscapes looked like before land plants, but also how the evolution of different broad categories of organisms changed processes and thus landscapes. The view of an arid landscape isn't quite right (at least not everywhere), but things would have looked quite different. Without plants to stabilize river banks, most river networks were big, broad networks of streams, the closest analogues being 'braided rivers' we see in the modern in areas with high sediment loads. In some places, the view of arid landscapes aren't too far off as 'aeolian' deposits (e.g. large dune fields, etc) are also quite common in rocks of the age from before land plants. For me, one of the most interesting tidbits is that generally before plants and significant terrestrial microbial activity, chemical weathering was thus extremely minimal, which meant that you see almost no fine grained material (i.e. muds) or clay minerals. The disclaimer here being that I study much younger landscapes (well, younger geologically speaking, 5 Ma is damn young on a 4.6 billion year timescale), so someone more familiar with the Archean and Precambrian rock record might have more things to add.
Would shooting a grenade actually cause it to detonate? Sorry in advance if this is the wrong sub, but it's something you always see in movies or video games, but how accurate is that? I know some explosives, like C4, will only detonate if the right detonator is used, is the same true for grenades? This is not 100% correct, it is possible to detonate a Grenade but one would have to hit the grenade in one of two places. The primer under the cock striker which is under the spoon, or with a strong enough bullet to hit the lead azide or Mercury fulminate in the blasting cap in the center of the main explosive. May take a few shots but it works. This technique is called Smud. But to in crease the chances we used high explosive incendiary rounds that detonate on impact. I used this multiple times on IED's when I suspected a set up to kill the operator. And it is fun
Do the large numbers of holiday lights this time of year have a measurable impact on the brightness of the US at night as seen from space? I think this is hard to judge because most of the images where you see a map of "lights" of the US or world or other country are usually done in upwards of 200 passes of the satellite. this means that it'll more than likely take longer than the christmas season to complete. if it could be done in a night I believe there would be a difference in the light maps. P.S. sorry everyone hijacked your question with power consumption facts. WTF mate.
Are there any harmful effects of drinking vitamin B12 energy shots? Today I was ID'ed for buying one of those vitamin B12 energy shots (like the "5-Hour Energy" drinks). This really caught me off guard as I've never been ID'ed for purchasing energy shots before. (Mind you, I can count the number I drink in one year on one hand) I assume the motivation to keep energy away from minors is to protect them from potentially harmful effects of ingesting too much caffiene, amongst other stimulants. But AFAIK the main component of energy is a massive dose of vitamin B12 (~8000% the recommended daily dosage); energy otherwise lack the stimulants that drinks like Red Bull or Monster contain. My limited knowledge of biology tells me that my body will discard any excess vitamins in urine after my body has "used up" what it needs, so there is no harm done in drinking "too much". Am I seriously off here? Seems to me the abuse of energy shots don't pose any serious risks the way energy drinks do. Is there some sort of legitimate reason to control the distribution of energy shots to minors? I believe the distinction is that vitamin B12 is water-soluble, so it makes its way out of the body easily in the form of urine. Whereas something like vitamin A is fat-soluble, so the body cannot discard it as easily. I'm no expert though, my knowledge is limited to first-year biology.
Before things like electric drills, welder machines, forklifts, excavators etc. became widespread, how were major factories and ships etc were built? Even at the pictures of factories from 1890s, there seem to be very big moving metal machinery, and I just wonder how they made it and put it there. They had hand powered drills, steam powered drill presses, and sometimes just poked holes in red hot iron on the forges. They could hammer red hot pieces of metal together to weld, or as in ships, riveted them together. They had ramps and hoists to do the work of forklifts. They had little excavators ( tumblebugs ) to drag behind horses, or even had thousands of men hauling off buckets of dirt to replace excavators.
What does askscience think of the e-cat? The e-cat (Energy Catalyzer) is supposedly a Low-Energy Nuclear Reaction build by an Italian inventor, Rossi. It has gained some credibility this week by running three hours sustaining it self and generating an even amount of heat with no signs of decrease. Description from : The Energy Catalyzer (sometimes shortened to E-Cat) is an apparatus built by inventor[1] Andrea Rossi,[2] with support from his scientific consultant, physicist and emeritus professor[3] Sergio Focardi. The 2009 patent application[4] claims "a method and apparatus for carrying out nickel and hydrogen exothermal reactions," with production of copper.[5] Although the patent cites previous works on cold fusion,[6] one statement by Rossi asserted that it is not cold fusion, but rather LENR, Low-Energy Nuclear Reaction.[7][8] Claims of a similar system, but yielding considerably less power, had previously been advanced by Focardi et al.[9] According to Focardi, "the hydrogen is heated at a given temperature with a simple resistor. When the ignition temperature is reached, the energy production process starts: the hydrogen atoms penetrate into the nickel and transform it into copper.”[10] The device has been demonstrated to an invited audience several times, and has been commented on positively by Bologna physics professor Giuseppe Levi, and by the Swedish technology magazine Ny Teknik, together with the online publication New Energy Times. However, Ny Teknik and the New Energy Times, together with other sources, have since published less favourable reports - with Ny Teknik pointing out apparent flaws in the science involved in testing, and the New Energy Times going as far as to assert that Rossi's claims may be fraudulent. According to Rossi, commercial application of the device will begin in October of 2011. Snake oil? What would it mean if it is real? Here is a link to Here is a I know we've discussed it a million times, but I'm having trouble finding old discussions on the matter, so I'll just go ahead and summarize my usual arguments here. They don't have open-box demonstrations, so who the hell knows what they're doing. Without reproducibility it's not science in the classical sense. I understand their perceived need for protection for their idea, but until the effect can be independently verified and reproduced, it's not a part of public physics knowledge. Which then leads into a discussion of whether science is a public vs. private concept, and a particularly interesting argument someone gave me about secret cryptoanalysis studies and whether that counts as science even if it isn't publicly disclosed and peer-reviewed. They don't have a good proposal of what's physically happening. Fusion requires two nuclei to overcome their mutual repulsion to then form a lower-energy bound state. Without a good explanation of how this happens, I remain skeptical at best. To date, they've only self-published an explanation, and haven't published in a peer-reviewed source. Again, without open-box knowledge who the hell knows what's going on. I would be skeptical, extremely skeptical. If they can make more energy than it costs to produce the energy, even if it's not fusion, then they'll make money, and that's fine. But I doubt it highly. Right now it's a magic trick ("an illusion, Michael"). It's a black box where they claim magic happens and energy is produced.
Does light lose speed after reflecting of objects? It doesn't lose speed, light always travels at the same speed, but, even for a perfectly reflecting mirror, it does lose energy. When a photon reflects off a mirror it undergoes a change in momentum (momentum is directional so the photon leaves with a momentum of opposite sign). Due to conservation of momentum, the mirror must gain equal and opposite momentum. If the mirror does not have infinite mass then this change in momentum must result in a corresponding energy change. From conservation of energy, this manifests itself as a drop in the photon energy and thus an increase in its wavelength. In other words, a red-shift. I discussed exactly how the mirror gains energy in this post , including a rough calculation of how big the effect is, for those that are interested. I have also had about a half dozen comments asking how something with no mass can have momentum so my reply is: Momentum being a property unique to things with mass is only true in newtonian physics. In special relativity everything with energy has momentum. A photons momentum, since it's rest mass is 0, can be calculated from the simple expression p = E/c, in the direction of propagation.
How can exoplanets in systems whose planes do not allow transits visible to earth be detected? Wikipedia lists astrometry and thermal imaging as being the two methods that don't require earth to be within the system's plane, but they are very limited in comparison to transits. Are there any promising methods that may eventually allow reliable detection of exoplanets in systems whose planes don't align nicely with earth? I imagine only a very small percentage of systems' planes allow allow transits observable from our system. If all systems were aligned such that their exoplanets were observable by transit, what's an estimate of the increase in detectable planets that would occur? That is, what percentage of exoplanets that would otherwise be detectable are expected to exist but are undetectable because of the angles of their planes? There's a lot more methods to detect exoplanets. I'll summarize them : For further reading see : https://exoplanets.nasa.gov/alien-worlds/ways-to-find-a-planet/ (you can see exact detection statistics here) and http://www.mpia.de/homes/ppvi/chapter/fischer.pdf
Mutation in a Multicellular Organism Hi team, I've asked . So I likely have some misinterpretations which confuse both. I'll try to be clear. I'll probably get a lot of the technical terms wrong; I've only studied biology to grade 11 and some armchair reading. By all means use the correct technical terms, but please be patient with me. My understanding is that there is a process (Mitosis?) by which a multicellular organism (MCO) replaces cells in its body with other cells in its body. So... while the cells that make up your stomach lining or brain (for example) have the same genome as the cells in your stomach lining or brain did ten years ago (unless you're 8), they are physically different cells. It seems that many errors (mutation) during mitosis are either killed off (usually by apoptosis?) or become cancer. But surely there must be some mutations that slip through and are either benign or - rarely I would guess? - favourable to the organism. So... what happens if the mutated neutral or beneficial daughter cell then becomes a parent cell? Is it possible for two (or more!?) slightly different genomes to exist within the same 'organism'? What would prevent such a being from being classified as symbiotic? Maybe I have it all wrong... But I tried to find this online and I could not. I would guess that everyone does have subsets of cells with a slightly different genome due to mutation. Every mole probably has a slightly different genome. The genetic term for this is 'mosaic.' Probably what separates them from being called a different organism is the inability of the cells to replicate outside of the host, as well as perhaps the similarity between the genomes of the cells. You could even further ask whether cancer could be considered a parasite. It wouldn't surprise me if there was a large difference between a cancer cell's genome and the host genomes, larger than the difference between some species. But again, the cancer can't replicate outside of the host or spread between people, which is what I think limits whether it is considered a separate life form. Some cancers are transmissible though, among Tasmanian devils. Normally you can't catch someone else's cancer because you recognize the cells as foreign, like an infection. But there are so few Tasmanian devils that they are all very immunologically related so they can catch each other's cancer. Some people have proposed that a human cancer cell line (HeLa) that can be propagated in lab culture constitute a new species. However the scientific community has generally not been very accepting of this train of thought.
According to Relativity, how fast would I need to travel before my mass was sufficient to collapse into a black hole? According to relativity, your mass at speed is higher than your rest mass, and as you approach the speed of light, this mass increases exponentially. Assuming I'm 70kg and was able to move without a craft or anything of the sort, how would I work out how fast I would need to travel before the Schwarzchild Radius of my body increased to beyond myself, collapsing me into a black hole? My apologies if I'm spouting utter nonsense- Just an idea that occurred to me, and I wanted to know if it was (hypothetically) possible. This is one of the reasons people don't use this outdated increasing mass idea anymore. Your mass is your mass; it doesn't change or increase as you get to higher speeds. And good thing, too, because one of the fundamental tenets of relativity is that as long as you're moving at a constant speed, you might as well be at rest. You're always moving at near the speed of light with respect to reference frame, so it would be very odd indeed if you spontaneously turned into a black hole!
How much of a disadvantage was Russia's high latitude for the USSR's space program? As I understand it, there is a benefit to launching spacecraft from a location near Earth's equator. Russia, however, is no where close to the equator. Would this have made it significantly more difficult for the Russians to make it to the moon? or would the difference be negligible? Baikonur is 46N. Canaveral is 28.4N. That means that Canaveral is whipping around at (cos(28.4)-cos(46)*40,000km/24hr faster, or about 335km/hour faster. Low Earth Orbit is about 28,000km/h. There is a difficulty that you tend to get a more tilted orbit which changes the places you might land.
Is more energy used in running a distance rather than walking the same distance? I'm not really sure about this. But I thought since the same mass is transported the same distance, than the same of work is done. It depends on the speed you are travelling. At around 5 or 6mph I think it is more efficient to run than walk. This is why speed walkers burn so much more energy than runners. http://sprott.physics.wisc.edu/technote/walkrun.htm
Considering its solid core, why is Saturn referred to as a gas giant rather than a rocky planet with immensely thick atmosphere? Can you "fly through" a gas giant? Than you for your time and answers. Our gas giants are referred to as gas planets because the vast majority of their mass is composed of materials found as gas on Earth. In reality all four have large non-gaseous regions in the center. Jupiter and Saturn are large enough that the pressure increases steadily until the hydrogen enters a supercritical state and behaves more like a molten metal than a gas. Uranus and Neptune are smaller and colder and likely have pressurized water-ammonia "seas" deep beneath the clouds. So no, you could not fly through them. In our solar system there's a clear difference between rocky planets and gas planets since there's a huge mass jump from Earth to Uranus. We've never observed a planet in the 5-10 Earth mass range to see how it behaves.
How do wifi signals work? I know the router emits the signal. How does this signal travel? It's it affected by mediums such as solids and liquids? The physics of Wi-Fi relies on the same principles as any other radio device. When an electrical current is passed through a long wire, such as an aerial, and this current is reversed in direction very quickly, it produces electromagnetic waves that propagate away from the aerial with the same frequency. These waves are just like visible light but of a much lower frequency. The range of frequencies that we label as microwave and radio have properties that make them ideal for broadcasting data, be it TV signals or Wi-Fi. Some materials that would be opaque to visible light frequencies are near transparent to these frequencies, while the larger wavelength allows the signal to diffract around larger objects. So in short, yes they are affected by objects and materials but one of the many motivating factors in the choice of the Wi-Fi frequency is how transparent the walls of your house will be to the signal, for example. The signal is received in a similar way to how it is broadcast. The same kind of antenna used to produce the signal will also be sensitive to receiving such a signal. The electromagnetic waves will oscillate the electrons in it, in the reverse process of generating a wireless signal by oscillating the electrons with an alternating current.
How small can an object be in space and still support an atmosphere? I'm assuming it would not only require enough mass but maybe a magnetic field too. Could a large asteroid potentially have a very thin atmosphere? Thanks. For gases to stay over geological timescales the escape velocity must be a large multiple of the typical thermal speed of particles. For the lower size limit you want a slow thermal speed - cold and with heavy gases like xenon. If you are fine with very thin atmospheres then asteroids could have atmospheres if far away from a star. At 100 K, xenon typically moves at ~100 m/s, an escape velocity of 500 m/s (Ceres) would give it some survival time but with significant losses. A bit more mass or a bit lower temperature and you can keep it over geological timescales. The vapor pressure of xenon at 100 K is very low, however.
What happens when I skip a meal? Why some people appear to be unfazed, while others feel bad almost instantly? Thank you, it seems I was missing something during my reading, and now it all makes sense! Brain not having enough energy takes care of the headache part of your explanation, but where does the physical weakness come from? Muscles should still be able to use fat for energy, as they have nothing to do with ketogenesis, right? One post below, you mentioned glycogen levels. Can the amount of stored glycogen vary greatly (say 1.5x or more) between people? (Assuming all of them are getting their carbs, of course.) And to clarify further: I'm not talking about the sensation of hunger. If I'm engrossed in something, it's quite possible for me to skip a meal and only notice it by the secondary symptoms that I should be hungry.
Is it possible for radio waves to be created by red shift and gamma rays with blue shift? Some context on how I came to think of this, I was learning some stuff about emission and line spectra and how they can be used to determine the elements in a star. Later on in the lesson it was explained red shift effects the colours seen and red shift needs to be taken into account. That got me wondering surely red shift (and blue shift) can be so extream that the waves can be radio or gamma waves. Is it even possible for the wavelengths to be larger than radio waves or smaller than gamma waves. all EM is the same stuff, really. if you're in a spaceship cruising at relativistic speeds toward a radio source, the waves are blueshifted. how much it shifts depends on relative motion. also photos exiting a gravity well redshift, and blueshift when they "fall" toward a massive object. wavelength is variable beyond what you study in class, but you'd need longer and longer antennae to detect infraradio.
How similar is reading notated sheet music to reading the written word? I help teach children music literacy (specifically on-staff notation for piano students). I often read articles about different ways to enhance this process for them, and I also occasionally read articles about teaching literacy in general to children. Some are very practical tips from fellow teachers, some are academic research. What I would like to know is, is it possible to take research on teaching general literacy to children and apply those findings to teaching music literacy? Are the brain processes for reading a book aloud similar to reading a piece of sheet music and performing it? Apologies if the flair isn’t quite right. I’m not actually sure what kind of question this is! I found this interesting article on musical dyslexia that I think answers your question from a neurological perspective. https://neurosciencenews.com/musical-dyslexia-17971/amp/ They are different. Apparently reading music activates a few of the same parts of the brain as reading written words but they are mostly built on different neural networks. Reading the written word relies on connecting the occipital love to the centers of our brain involved in speaking and processing oral language. Reading music appears to involve a lot more of the brain including regions that have nothing to do with oral language. A person could have dyslexia in reading the written word but still be able to read music and vice versa.
Why does your heart rate decrease when you hold your breath? Wouldn't that make your heart work harder? I cannot seem to comprehend this phenomena. I'm not sure why this is but on a related note, if you keep your mouth closed and try breathing out then your heart rate will increase due to increased pressure in the chest ( http://en.wikipedia.org/wiki/Valsalva_maneuver ).
How do astronomical observatories make self-positioning? If they have static "earth" coordinates, do they consider tectonic plates movement? If they constantly calculate their coordinates what points they use for the references? What the coordinate system do they use and where is origin of this system? Hello, amateur astronomer here. I agree with my learned geologist friend that the baseline is where we know where to expect celestial bodies. This can quite easily be calculated using historic movements whilst factoring in other variables such as gravity of nearby bodies. On a far grander scale they use very distant quasars and pulsars as they don’t “move” as much m much relative to the earth and are extremely bright. Any movement they do have can be negated by calculating the distance (redshift etc) and therefore calculating the rate of which it is moving away (inflation) from us. NASA uses this technology I believe, in conjunction with various other methods.
How Can Drugs Affect You for 12 Hours? I take Dextroamp ER which has effects that last for for 12 hours. How does this happen? Wouldn't my body digest it before then? Also, how does the effect stay consistent for such a long time? Drug metabolism , includes two basic premises. Pharmacokinetics and pharmacodynamics which describe how drugs react within the body. A drug that is absorbed into the blood stream quickly may have a very long half life within the body because the enzymes and processes that break it down are in short supply, or very slow within the body. The ER on drugs, or sometimes XR means extended release, and thus they are typically released more slowly into circulation through a special enteric coating, which helps ensure there is a more stable level of active drug in the bloodstream for longer. Some drugs don't require this, because of their slow metabolism within the body however.
In the Scientific American of 1863, it's claimed that if the sun were made of coal, it would only last 5,000 years. Given our present knowledge, how accurate was their estimate? In this month's Scientific American, in the "50, 100 & 150 Years Ago" section, there is this excerpt from August 1863: The Sun "If the sun were composed of coal, it would last at the present rate only 5,000 years. The sun, in all probability, is not a burning but an incandescent body. Its light is rather that of a glowing molten metal than that of a burning furnace. But it is impossible that the sun should constantly be giving out heat, without either losing heat or being supplied with new fuel. Assuming that the heat of the sun has been kept up by meteoric bodies falling into it, and proof has been given of such fall, it is possible from the mass of the solar system to determine approximately the period during which the sun has shone as a luminary. The limits lie between 100 millions and 400 millions of years." The speculation on the sun's source of fuel was interesting enough, but I also thought their 5,000 year coal estimate was interesting. Presumably they had a decent idea of the sun's mass, but how accurate was their estimate of the sun's energy output? Given today's knowledge, how fast would the sun exhaust its fuel if it was made of burning coal? Of course, that's setting aside the physics of whether a sun-sized lump of coal like that would be stable. Coal's energy density is 24 megajoules per kilogram according to Wiki. I'm going to neglect the mass of the oxygen required to combust the coal. (1 solar mass) x (24 MJ/kg) / (1 solar luminosity) = 4000 years So their estimates of coal's energy density (which will vary depending on the type of coal, so who's to say mine is more accurate than theirs) and/or their estimates of solar luminosity were a little bit off, but still pretty reasonable.
If a wooden structure (let's say a log cabin) is adequately protected from moisture and things like termites and fungus, could it last indefinitely? (Let's say 100,000 years.) True, but I think that was the gist of the question, i.e. under what circumstances can wood be preserved, and for how long? Here is a fairly-recent story about a mummified forest found in the Arctic that's between 2 and 10 years old. Note that it's a , not forest - this is still the original wood, not minerals or other material that has taken its shape. In this case, the preservation was so complete that even and are being recovered intact. As kermityfrog noted, the primary reason this wood hasn't decomposed over that astounding period of time seems to be that it was very quickly covered over by landslides, and thus more-or-less protected from exposure to air and light, thereby preventing oxidation.
Do people’s core personalities change as they get older, or do they just mature and adapt? This may not be the right sub for this question as the anecdotal/speculative answers so far illustrate. So in recognition of the theme of the sub, but without the knowledge to comment on the quality of the sources, here are some studies and articles about studies that I got on a quick google of the topic: APA, 2003: Personality changes for the better with age APA, 2016: Personality Stability From Age 14 to Age 77 Years NPR, 2016: Personality Can Change Over A Lifetime, And Usually For The Better Greater Good, 2018: Can Your Personality Change Over Your Lifetime? LiveScience, 2020: Does your personality change as you get older?
Am i right for a Masters Degree in CS? What will it take? I just finished college (Information Technology degree) and I'm in the process of evaluating my options. I really enjoy my field and I couldn't picture myself doing anything else but so far, I've had terrible experiences working in the private sector and I've always wanted to devote myself to research and apply my knowledge to an interdisciplinary area. I may have the opportunity to get a scholarship to study a Masters Degree in Computer Science but I don't know if I've got what it takes for it. Any advice from my fellow redditors? MS in CS degree holder here. What would be your end goal after getting another degree? If you want to do research, a masters degree will open up some opportunities but not nearly as many as a Phd. Also, keep in mind CS research is essentially applied mathematics research. IT has absolutely nothing to do with Computer Science. What is the most advanced math course that you had?
What is loop quantum gravity and how does it differ from String Theory? I'm only in my sophomore year in high school, and they don't teach particle physics here at my school. I've read some books on String Theory, but recently I came across "loop quantum gravity" and I don't really understand what it is. This is difficult because, according to general relativity, gravity is not a force. Instead, it's a property inherent to space itself. I dont know why these kind of statements are so popular.. You can describe gravity with a spin-2 force field. It is just that at a classical level the geometric description is much more appealing. The problems from quantizing gravity stem from the fact that the corresponding couplings are non-renormalizable (of course there are also other problems like that the absolute energy scale matters, vacuua in curved spacetimes,.... ).
Do I really need special eyewear for viewing an eclipse? Why/why not? The optics part of my physics series was a bit rushed, but I reckon with some thought I could understand why it's damaging (or why it's not) Yes! I posted this link in another thread: NASA - Eye Safety During Solar Eclipses They have this part in bold: The first paragraph discuses why. "Even when 99% of the Sun's surface is obscured during the partial phases of a total eclipse, the remaining photospheric crescent is intensely bright and cannot be viewed safely without eye protection [Chou, 1981; Marsh, 1982]."
What are the processes in warm blooded creatures that regulate body temperature so precisely? That just tells me it's generated in deep organs and lost to the environment, I was looking for a bit more depth than that. Besides it doesnt address how the body so finely tunes it's temperature.
Do multiple wounds take longer to heal than a single one? Assuming several things: 1. all the wounds are exactly the same in type, size and depth 2. there's no underlying infection 3. blood supply hasn't been compromised (either due to the wound or due to the person's hand's arterial supply) 4. the general condition of the hands are the same, eg no skin disease on one hand compared to the other Then yes, they will heal at the same rate. Healing is based on a lot of things including clotting factors and platelets (the things that form scabs), fibroblasts (which are cells that produce the scars) and blood supply (which is how the clotting factors and fibroblasts arrive at the site of injury) so the main factor is the blood supply This is very simplified but the main gist of it is there
Would burning alive be excruciating or would shock/adrenaline block most of it? I've had a pretty natural fear of burning alive (dreams about it and such) and seeing stuff like the woman killed in the elevator this week is deeply disturbing. Having had small burns before I know how painful even second degree burns can be. My question is would it hurt that badly all over your body the whole time or would the pain mostly be blocked? Obviously it wouldn't be pleasant but surely it can't be as bad as I'd think, right? My intensive care unit treats burns, so we see the pretty bad ones; usually anything from 30% upwards. People with big burns are often not screaming with pain, for several reasons I think; full thickness burns are not painful as the nerve fibres have been destroyed but its very unusual for someone to have just full thickness burns. Most injuries will have superficial and partial thickness wounds as well and these are certainly incredibly painful. A massive shock response probably dulls the pain, and of course when I see the patients they have usually already been seen by first responders and given analgesia. The recovery period can take months - just to get out of the ICU and involve many operations as well as multiple dressing changes and various horrible complications. The patients will spend nearly all of this time on a morphine infusion. A really big burn is just a terrible thing to to endure, and to recover from.
What did the ice front look like during the ice age? Would it appear as a wall of ice or more of a gradual slope that you could walk on. Are there any modern day places that might look similar? It would have looked like the end of modern-day glaciers. In fact, they were glaciers at the ends. In fact, we are still in the ice age today, as there are still significant parts of the earth covered by ice.
Do butterflies remember being caterpillars? Yes and no. Butterflies don’t have a complex memories that humans have, so no they don’t remember being caterpillars. However, caterpillars can be trained to respond to stimuli and they will remember how to react to that stimuli when they’re butterflies. So no they can’t remember being caterpillars, but they can remember stuff they learned while they where caterpillars
Did Marie Curie ever wonder if the radiation she was studying was dangerous? Both Curies were plagued by ailments—burns and fatigue—that, in retrospect, were clearly caused by repeated exposures to high doses of radiation. Both, too, were resistant to the suggestion that their research materials caused their ailments. https://www.smithsonianmag.com/history/madame-curies-passion-74183598/
Any evidence for fertile hybrid origin for Homo sapiens ? There is increasing evidence being reported in the scientific literature of fertile hybrids forming new species for both plants and animals. Orchids of the genera and , rodents , Frogs , Guenon monkeys to name a few examples. A common theme reported is that fertile hybrid formation seems to be associated with ecotones, zones of overlap in species that once had ranges completely separated. Fertile hybrids can result where there is a wide difference in number of chromosomes between parent species. This leads up to my OP question, is there any evidence to suggest that modern humans, , has origin as a fertile hybrid species of two proto-human Hominid species that once had allopatric distribution that over time came to overlap, I assume in Afirica ? EDIT TO OP: Looking at a few Hominid timelines, and assuming can be traced back in time ~200,000 - 220,000 years as suggested from genetic studies, there are a few possible paths for a fertile hybrid origin: 1) 2) 3) 4) 5) others ? There is definite evidence that we cross bred with Neanderthals, it’s quite clear in our DNA. I don’t believe there’s evidence that we are the product of two separate species producing a third, it’s mostly just our ancestor species gaining genetic information from others as we progressed.
If something was on fire in a fridge that could go to extremely low temperatures and it kept getting colder. Is there a lower temperature limit where the fire can no longer exist? Do note, however, that different reactants can ignite at different temperatures. Foof for example: "Being a high energy oxidizer, dioxygen difluoride reacted vigorously with organic compounds, even at temperatures close to its melting point. It reacted instantaneously with solid ethyl alcohol, producing a blue flame and an explosion. When a drop of liquid 02F2 was added to liquid methane, cooled at 90°K., a white flame was produced instantaneously, which turned green upon further burning. When 0.2 (mL) of liquid 02F2 was added to 0.5 (mL) of liquid CH4 at 90°K., a violent explosion occurred."
"There is no cure for smallpox, but vaccination can be used very effectively to prevent infection from developing if given during a period of up to four days after a person has been exposed to the virus." How does a vaccine work AFTER being exposes? How can giving you more of the virus prevent it? Thank you for your submission! Unfortunately, your submission has been removed for the following reason: We do not debunk or vet theories or offer peer review on /r/AskScience . For more information regarding this and similar issues, please see our guidelines . If you disagree with this decision, please send a message to the moderators.
Why are nuclear fusion explosions not 100% symmetrical? Please see photos in comments as an illustration of my question Explosions aren't completely symmetrical for the same reason that no cut cube of steel is perfectly cube-shaped. The mechanical limitations of how we make stuff will always result in imperfections. There's also the "imperfections" in how the nuclear reaction won't advance through the reacting material with 100% effectiveness or efficiency. A few atoms slow on this side and a fizzled out proton on that side means that the initial ball of plasma won't be a perfect sphere. And that's entirely ignoring the fact that all of those explosions were subject to Earth's gravity as well. If you're talking about the blobby nudules out the side of those plasma balls, those are guy wires evaporating. Many of those nuclear devices were detonated in place sitting on a large metal structure to suspend them several dozen feet above the ground. Guy wires were used to keep them standing straight. Because the matter in the wires is much thinner and easier to heat than the structure, they evaporated quickly in the first moments of the detonation.
It is estimated that there are between 1-10 quadrillion ants on Earth. How did we come to that number? Count/ estimate the number of ants in individual colonies of particular species. Count/ estimate density of colonies of each species in different environments and ecosystems. Multiply everything out by the measured area of those different environments and ecosystems on the planet.
If the electromagnetic force overcoming the "strong force" is responsible for decay -- why do unstable isotopes with a small nucleus decay? Sorry for the dumb question, I am just trying to better my understanding of physics but I am not very well educated. Specifically, I understand that say, when uranium 235 is hit with a free neutron, the Uranium 236 isotope fissions, because its nucleus is bigger than the distance that the strong force is capable of exerting, (about the diameter 2.5 protons?), so the electromagnetic force therefore has enough energy to pull the deformed nuclei apart -- but what is causing unstable isotopes, say carbon 14, to decay, when their nucleus is so small? Writing this out, I'm thinking that my understanding of the "strong force" is totally wrong... surely it doesn't have the kind of centre of "force" that idea of competing forces seems to imagine... I really don't understand where the strong force between the nucleons in the nuclei exist... is it between the individual particles themselves? So I guess I'm trying to find out the relationship between the stability of isotopes to the proton/neutron ration, and how this relates to the strong force/electromagnetic force equilibrium that I was under the impression sort of holds an atom together? Not all decays of unstable nuclei are due to the electromagnetic force overcoming the nuclear force. Your example of Carbon 14 decays via beta emission, and the weak force is responsible for beta emission. Other nuclei decay by emitting alpha particles (He nuclei), which involves the alpha quantum tunnelling through the potential barrier of the nuclear force holding the nucleus together. Only very large nuclei decay via spontaneous or induced fission. The nature of Nuclear force itself comes from all of the nucleons continuously exchanging (virtual) mesons. As for the stability of isotopes, generally proton rich nuclei will decay via beta + emission, and neutron rich nuclei will decay using beta emission. Alpha emission is related to how tightly bound the alpha particle formed in the nucleus is due to the nuclear force potential barrier and repulsion from EM force.
Are there clear examples of self-destructive behavior, similar to alcoholism or overeating, in other species? This question arose out of a discussion of alcoholism. Essentially, do other organisms eat, drink or otherwise over-indulge themselves to death? Laboratory rats were given unlimited access to intravenous cocaine hydrochloride or heroin hydrochloride. Animals self-administering cocaine quickly developed a pattern of episodic drug intake, with periods of excessive cocaine self-administration alternating with brief periods of abstinence. Subjects allowed continuous access to intravenous heroin showed stable drug self-administration, with a gradual increase in daily heroin intake over the first two weeks of testing. The general health of the animals became markedly different: those self-administering heroin maintained grooming behavior, pretesting body weight, and a good state of general health; rats self-administering cocaine tended to cease grooming behavior, to lose up to 47% of their pretesting body weight, and to show a pronounced deterioration in general health. The mortality rate for 30 days of continuous testing was 36% for animals self-administering heroin and 90% for those self-administering cocaine. These results suggest that cocaine is a much more toxic compound than heroin when animals are given unlimited access to intravenous drug. http://jama.jamanetwork.com/article.aspx?articleid=399323
Why does your nose run when eating something spicy? “Gustatory rhinitis” affects many people after they eat hot or spicy foods. When a person eats these foods, a nerve called the trigeminal sensory nerve is stimulated, which causes the nose to run. A person may prevent gustatory rhinitis by avoiding trigger foods. Release of histamine, a nonspecific immunity mechanism to external stimulus.
Changing the speed of light Changing it by 1% would probably not affect life a great deal, but it really depends on how you accomplish this. The speed of light may be derived as, for instance, a function of vacuum permeability and permittivity. Is it increased by 1% by changing each of those slightly? If so, perhaps this isn't very important to life. However, what if one is changed a lot, and the other changed a lot in the other direction? The difference could still be 1% in the speed of light, but whilst also significantly changing the properties of many materials. This could clearly affect life (and everything else) a great deal. Similarly, making the speed of light instance would affect life in a manner entirely dependent on how you achieved this. The Universe would have to work in a significantly different way to allow it.
What would happen if you light a match on a gas planet? Nothing. On Jupiter, Saturn, Uranus, and Neptune there's no oxygen (O2) to sustain combustion. I doubt your match would even light in the first place. Oxygen binds very readily with hydrogen and carbon to produce water (H2O) and carbon dioxide (CO2), which are more stable than diatomic oxygen. I only know of one mechanism cable of producing an atmosphere rich with diatomic oxygen, and that's photosynthesis.

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