title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How did our ancestors survive before glasses?"
] | [
false
] | [deleted] | [
"You're thinking of life expectancy ",
", which is not the same as one's total ",
". ",
"It's simply a myth that people didn't get old in ancient times. It's a myth that possibly originates in a confusion about ",
" lifespans. In those times, infant and child mortality was extremely high, so the total ",
... | [
"Let me ask you a similar question: what happens to animals with bad eyesight? Birds, predators, or rodents with bad eyesight? Either the eyesight deficit is severe enough that it results in their death (as other posters have said) or the deficit is not severe enough to affect survival. ",
"Now the question is: h... | [
"One thing that I am surprised has not been mentioned yet - Myopia is more common in societies that do close work as children. ",
"Here is ",
"a source",
" (I am sure someone else can find a better, or even refuting source) that shows that children who do lots of close work (reading, writing, etc.) developed... |
[
"Could solar panels have an effect on the average climate temperature"
] | [
false
] | Do solar panels produce heat or do they reduce heat due to absorbing light? | [
"Solar panels absorb heat. But the electricity they make will end up being converted into back into heat eventually. "
] | [
"I see thanks "
] | [
"Although solar panels absorb photons from the sun that typically would have dissipated as heat in the earth's environment, the proportion of earth's surface area covered in solar panels is so small that the effect is negligible."
] |
[
"If the higgs field is what gives thing mass, is there a field that gives things charge?"
] | [
false
] | I saw a similar image to where they said mass increases to the right and charge increases towards the top (doesn't work entirely but sort of)(in one of those videos explaining the higgs boson). They also said something along the lines of "mass is a property given by the higgs field". And so I wondered if there is some ... | [
"The electromagnetic field, which is quantized as the photon."
] | [
"Simply put, no. The value of the electric charge is put in by hand in the Standard Model. It is not generated by a field.",
"It is true that there is an electromagnetic field, but this field only carries the forces between charged particles; it does not generate the charge in the first place."
] | [
"To understand the distinction, it is important to understand how the Higgs mechanism gives particles mass. A particle like the electron gets its mass from the product of two terms: the strength with which it interacts with the Higgs field, and the value of the Higgs field that fills space.",
"The first of these... |
[
"Why do our hair colors change (greying/white hair) when we grow older or are stressed?"
] | [
false
] | I've always wondered about this phenomenon. It seems kind of odd that people grey as they grow older as hair does not seem, to require a lot of energy to maintain. Can someone explain why this happens? And how does stress factor into people greying faster? | [
"According to a recent article in the Federation of American Societies for Experimental Biology (sorry, no link, subscription site):",
"Oddly enough, your follicles produce three things simultaneously: melanin, which gives your hair its natural colour, hydrogen peroxide (as part of the follicle's normal oxygen in... | [
"How come there isn't some way of shampooing with catalase to stop the formation of peroxide?"
] | [
"Primarily because catalase is an intracellular enzyme and needs to be in the cells producing the keratin/melanin at the base of the hair shaft. The hair is being produced by the follicles deeper in the scalp, so the catalase enzyme can't get down to where it would need to be effective. Also, it's a LOT cheaper t... |
[
"Why didn't the human ribcage evolve to to completely surround our torso?"
] | [
false
] | Our backside seems well protected, but our stomach and other organs don't have that protection. What gives? | [
"Evolution doesn't perfect living beings, it just optimizes them for reproduction. Basically, if a better ribcage doesn't result in more babies, it doesn't get passed on. An unprotected backside results in fewer babies, so those with protected backside pass on those genes."
] | [
"I believe that if the entire torso was surrounded and bound by a \"full\" ribcage it would cut down on the ability of the ribcage to expand fully during the inhalation and exhalation cycle. Biomechanically if the rest of the spine was connected dorsally and ventrally by more ribs, lateral movement and rotation wou... | [
"Plus it allows for the expansion of a woman's belly... reproductive efficiency, if people did evolve the \"full ribcage\" you want it would stop woman from being able to bear children efficiently."
] |
[
"Question of Genetics/Evolution?"
] | [
false
] | null | [
"In other words, if a homogeneous culture such as Iceland were moved to the equator, even if they continued the \"pure\" blood line, they would adapt/evolve to their environment and gain darker skinned mutations over a very very long time, even if the original gene (which allowed for/was caused by the mutation in h... | [
"First there is no such thing as pure or homogeneous in genetics. Every population has genetic variations between individuals. Otherwise everyone would look like identical twins.",
"When some people in Iceland moved to Ecuador evolution will favor slightly darker skinned individuals. Also in time some mutations w... | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"/r/AskScienceDiscussion",
"Please see our ",
"guidelines.",
"If you disagree with this decision, pleas... |
[
"Do the vaccines prevent Covid from damaging your brain?"
] | [
false
] | null | [
"It’s well known that COVID infection can lead to mental issues, and even apparently mild infections can lead to long term lingering mental problems.",
"The presence of numerous psychiatric symptoms are also highlighted in many reviews ... The most frequently disclosed are low mood, mood swings, hopelessness, hei... | [
"We are not going to know the answer to that for decades. I personally have gotten back to normal after a month in the ICU back in April (pre-Vaccine); but I'm participating in five studies working frantically to try and answer exactly that question. For now? We just don't know."
] | [
"I have one important question that I’d like answered. Does this said damage repair itself over time, do you ever get back to baseline, like pre Covid? Asking in general, like a normal healthy persons body."
] |
[
"What exactly happens when you get the wind knocked out of you?"
] | [
false
] | Have had it happen a few times to myself as a kid or adult playing sports. Basically after watching that video, it made me think what exactly is going on internally that makes you not able to breath? | [
"It hurts to get hit in the abdomen."
] | [
"It hurts to get hit in the abdomen."
] | [
"Your diaphragm is temporarily paralyzed so your lungs can't expand/contract normally."
] |
[
"Is it actually possible to discover an element that \"isn't found on the periodic table\"?"
] | [
false
] | That line, which occurs in basically every sci-fi movie involving aliens ever, always bothered me. My high-school-science understanding of elements was that their identity is determined by the number of protons, and at some point too many protons = instant decay into smaller elements. That gives us a pretty limited ran... | [
"Well, we need to wait for theory to catch up. You're right that all that defines an element is the number of protons in its nucleus. We haven't ever created anything with more than ",
"118 protons",
" yet, and they're all just temporarily named for the Latin version of the number of protons.",
"Our simulatio... | [
"The main argument is whether the \"island of stability\" will be \"relatively stable\" as in lasting for days/years/long enough to use them for whatever, or \"relatively stable\" as in \"oh wow, this one lasted for a whole minute! That's millions of times longer than that other isotope did!\". Mostly depends on ... | [
"It's written as a way for \"scientists\" to express that something is completely alien, written by people who haven't had chemistry since high school. ",
"For one thing, in theory the periodic table expands as necessary. When I learned it, there were only 108 elements \"on the periodic table,\" though the tables... |
[
"How can a person have ADHD AND Schizophrenia when they’re believed to have opposite ‘causes’?"
] | [
false
] | ADHD is believed to be caused by a lack of dopamine (and/or noradrenaline) in the brain. Schizophrenia is believed to be the excess production of dopamine, the opposite. So how can somebody have both? Could it be that those who have both produce an excess amount of dopamine, but not enough noradrenaline (another cause ... | [
"I don't know how much agreement there is on the dopamine assumptions here. The causes of schizophrenia remain very much a mystery beyond \"probably associated with this increasingly long list of genes\" and although anti-psychotic medications and anti-ADHD medications frequently target one or several of the multip... | [
"The leading theory on the mechanism of adhd is more to do with dopamine receptor level or function, than not having enough dopamine itself. ",
"Another theory is that the molecule that transports dopamine doesn't work effectively or there isn't enough produced.",
"Schizophrenia is theorised to be due to neural... | [
"Re: Adderall induced psychosis.\nIn most cases it tends to happen when a person takes too high of a dosage and doesn't get enough sleep.",
"Some times it occurs if the person is on other medication as well. Such as SSRI or antidepressants.",
"But this can also happen as a quirk of a person's mental health at t... |
[
"Does the IFR of an infectious disease change with time?"
] | [
false
] | null | [
"It can change significantly once better treatments are discovered. For example, the fatality rate for HIV was nearly 100% before antiretroviral therapy was developed. Now it is a manageable chronic infection. You also have to take timing into account, as well as age groups. With COVID for example the fatality rat... | [
"Yes it does imagine this oversimplified situation. A disease kills 10% of people who have a gene which makes them susceptible while just infecting everyone else. At first it kills 10% of people but after it's killed 50% of the people with the gene it now only kills 5% of the total population."
] | [
"Absolutely correct. These situations are mind bogglingly dynamic with many thousands of variables affecting outcomes."
] |
[
"What natural phenomenon used to occur back in prehistoric times that we wouldn't see now?"
] | [
false
] | null | [
"There are doubtlessly quite a few, here's a start:",
"Komatiitic flows",
". These are a type of volcanic flow involving low-silica magnesium-rich lava. Komatiites had a distinctive composition, were high-volume, very high tempearture and low in volatiles. They used to produce large sheets and are associated wi... | [
"Coal formation.",
" It can still happen, but the Carboniferous era was pretty much a one-shot deal for producing useful amounts (>90% of total reserves) of high-quality coal.",
"Lycopsid trees (which incidentally look like something by Dr. Seuss) had just invented lignin, a major polymer in modern wood. It too... | [
"Extremely large lakes held back by continental ice sheets (Lake Agassiz, etc.), and catastrophic flooding related to the draining of similar lakes (the great Missoula floods that created the scablands of Washington).",
"https://i.ytimg.com/vi/xOqy_IeQ6b0/hqdefault.jpg",
"https://en.wikipedia.org/wiki/Missoula_... |
[
"How much power does a charger plugged into a wall use if any at all?"
] | [
false
] | No device plugged in. | [
"Depends on the quality and design of the particular charger. A good design with quality parts will sip so little power that it's essentially nothing, a bad design can have substantial draw and just dumps the power into the room as heat.",
"To get a very rough idea of how much energy is drawn, touch the charger ... | [
"Wouldn't going by the Watts in, Watts out measure be a good way to see how efficient it is under 0 load as well? If it takes in 20 watts under max load and outputs 15 watts (like my tablet charger) that means it is of high efficiency to begin with. If it is something like a lot of laptop power bricks where they ca... | [
"The operating efficiency isn't necessarily correlated directly with the standby draw, but it would be pretty funky to find a design that is efficient in one case but not the other. ",
"If it is something like a lot of laptop power bricks where they can take in 250-300 watts and only output 90 (hp laptop brick)"... |
[
"Why is it that there is no planet that orbits the sun in the opposite direction to the other planets?"
] | [
false
] | null | [
"All the planets in our solar system would have emerged from what's called a 'proto-planetary disk'. This was a fairly flat disk of gas (largely H and He) and dust (solid stuff, including rock-making stuff and, at farther distances, solid ices). The planets inherited how they orbit from the direction in which the d... | [
"Here's a good video using a rubber sheet to simulate a gravity well: \n",
"Gravity Visualised (Youtube)",
"At around 2:45 the teacher adds a bunch of marbles in opposite directions, and through collisions they self-select one direction to orbit the well. As other commenters have mentioned, this happens because... | [
"The tl;dr here is that almost everything in the solar system is spinning because the matter it is made of was always spinning in some small way. That kind of momentum doesnt just go away. There is no force that makes planets rotate or orbit — it's just the energy from the formation of the solar system still being ... |
[
"Why do states of matter exist?"
] | [
false
] | I can't seem to find a straight answer as to why distinct states of matter with boundaries (boiling point, melting point) between them exist and not a continuum of states. I'm guessing it has to do with specific bonding energies and such and it makes sense when you think of say a solid structure breaking up to form a ... | [
"This is a really good question, and ultimately comes down to the concept of ",
"criticality",
". Criticality in day-to-day systems such as liquids and gasses is quite complicated, but the idea can be understood fairly well with a simpler system, the Ising model of ferromagnetism.",
"The basic idea of the Isi... | [
"When you have a collection of matter, there exists different types of interactions between the constituents of that collection. For example gravitational attraction, coulombic interaction, spin-spin interactions, etc. All of these interactions have a characteristic energy associated with them, and furthermore, eac... | [
"Tell me again how this is not a continuum.",
"You can lead a horse to water...",
"I think the problem is that while your answer is technically correct and perhaps appropriate for a well informed audience, it misrepresents the important aspects of what happens in large interacting systems. There are ",
" chan... |
[
"What is Area 51?"
] | [
false
] | null | [
"Area 51 is a facility in the United States for testing military aircraft."
] | [
"Does it has anything related to programming?"
] | [
"No."
] |
[
"Why do software updates require me to restart my computer/phone? Why can't the update install properly with the device turned on?"
] | [
false
] | null | [
"In 99% of cases, they don't, except in a couple of specific cases.",
"Your computer is currently running a bunch of software, which we'll divide into two major sets. For example, you'll have your web browser, email client, music player, chat clients and other stuff running. These programs are so called \"user mo... | [
"Some operating systems, such as Linux, can update all software without restarting. Windows hasn't had significant market pressure (the driving force behind it's progression) to gain this ability. While rebooting can be disruptive it is a quick and easy method to supplant new code and dependencies while ensuring th... | [
"Memory management is a weird one in this case. Most of the memory management is done by the runtime that is used by the program (i.e. libc). This is a shared library that is loaded by each program when it starts, and provides a bunch of useful functions to the program. Most of these just really streamline the inte... |
[
"Why do we see intricate patterns when pressing down on closed eyes?"
] | [
false
] | [deleted] | [
"The photoreceptors in our eyes normally respond to light wavelengths. However mechanical forces can also slightly activate these same photoreceptors. So by pressing on your eye, it activates the receptors so you see “lights” just as if light was causing you to see lights"
] | [
"Could it damage your eyes as well? I used to do that all the time when I was a kid in class because I was so bored. I would open my eyes again and my eyesight was all wacky until it went away."
] | [
"OK, thanks for this response. I was always scared that I messed up my eyesight and that I was gonna go blind. Well here I am now wearing glasses but it is most likely that I have glasses because it runs in the family lol. "
] |
[
"Statistical polls vs. election results."
] | [
false
] | [deleted] | [
"Statistics like these can be very misleading. It depends on the area they polled, the economic group, age group, ethnic group. The odds D would win are very hard to determine due to a very small amount of info. They would need to do a broader poll for the best results. I know you're in Iceland so maybe there aren'... | [
"It has been too long since I took a statistics course in college, so I'm not going to make a fool of myself and explain it incorrectly. But ",
"here",
" is a reference that might help!",
"Perhaps a kindly statistician will come by and offer his/her input!"
] | [
"It has been too long since I took a statistics course in college, so I'm not going to make a fool of myself and explain it incorrectly. But ",
"here",
" is a reference that might help!",
"Perhaps a kindly statistician will come by and offer his/her input!"
] |
[
"If the Moon is slowly moving away from us, what will happen to the Earth when this actually happens?"
] | [
false
] | It seems the moon is moving farther and farther away from the Earth every year. When the moon is no longer in orbit, what will happen to the Earth and the moon? | [
"The Moon will never leave orbit. Its track widens at a rate of only a few centimeters per year, and given current rates of change, the Earth will become tidally locked with the Moon (keeping the same face constantly toward each other) long before it can to leave orbit. At that point its orbit will stop expanding, ... | [
"Ok so no death caused by the tides running amok. But definite death by a bloated sun. Gotcha!"
] | [
"The bloating sun is only the first of our concerns, i for one want to see the andromeda collision. "
] |
[
"Why do propeller planes often have their wings located above the fuselage while jets have the wings located in the middle or below the fuselage?"
] | [
false
] | null | [
"These are called \"high wing\" and \"low wing\" designs, respectively. There are plenty of both low-wing and high-wing variations of small prop planes, but jet airliners are almost always low-wing. There are a lot of reasons why an airplane might use one or the other; I'll give a few examples.",
"Part of it simp... | [
"Also, high wing designs are often popular in smaller propeller aircraft, thus resulting in the two following points.",
"2.Small a/c often fly off-field ( that means they land on random roads and clearings) and a high wing helps avoid collisons with road signs, fences, rocks, bushes, small annoying children, most... | [
"This is a super thorough answer, but I just wanted to contribute that there are quite a few exceptions to OPs stipulation.",
"The B52: ",
"https://upload.wikimedia.org/wikipedia/commons/d/d0/Usaf.Boeing_B-52.jpg",
"The B17:\n",
"http://www.warbirdsnews.com/wp-content/uploads/X-Boeing-B-17-Aluminum-Overcast... |
[
"Did the Fukushima meltdown in Japan cause any far-reaching damage? Was the ocean poisoned, has it affected any other countries?"
] | [
false
] | My friend claims that the meltdown essentially poisoned the whole ocean, and that fish everywhere are diseased... Also, we in America have reason to fear the effects of the meltdown. Currently, I don't believe we have any reason to fear -- in regards to nuclear exposure or whathaveyou. Please inform me. | [
"I would start with the World Health Organization Preliminary Dose Assessment on the Fukushima Accident and the events that transpired as a result of the 3/11 earthquake",
". In terms of worldwide, they clearly state that committed doses are very low outside of Japan. For thyroid, the worst dose is to infants nea... | [
"Doses from nuclear accidents often depend heavily on the various factors. The type of reactor, nuclear material in question, wind direction, wind strength, wind stability, etc... \nIn general, doses from nuclear accidents tend matter most to those very near the reactor and downwind due to airborne gamma doses. ",
... | [
"Thanks for the reply."
] |
[
"If I set my water temperature to 50 deg celsius and have a shower why does the bathroom fill with steam, as this is half of the boiling point?"
] | [
false
] | null | [
"Boiling and evaporation are different processes. Evaporation can happen at any time from the ",
" of the liquid, while boiling is a bulk process where all the liquid may turn to gas. This is why you get the bubbeling when boiling, as gas bubbles are formed below the surface and rise. ",
"Evaporation increases ... | [
"Technically what you are seeing is not steam, but still liquid water. Actual steam (as in, water gas) is invisible. Google is being unhelpful in finding the standard image reference, but if you get a kettle really boiling you will see an inch or so gap between the spout and the clouds. That gap is steam, the rest ... | [
"That's for example the same reason why your washed clothes actually dry as well. And I might add that if u for example freeze your wet clothes and put them out in the Winter, they will be dry at some point in time although it might take a while. As far as i remember the correct term was sublimation."
] |
[
"What compels a liquid to be relatively incompressible?"
] | [
false
] | When I learned about phases, I learned the good ol' rule of thumb that solids are of constant shape and volume, liquids are variable shape and constant volume, and gases are of variable shape and volume. While what I've since learned of the molecular lattice that comprises a solid seems to account at a high level for a... | [
"The interaction between molecules can be thought of as a short range attraction (1/r",
" and a really weak repulsion (1/r",
" This is due to the fact that molecules have a dipole electrical moment (e.g. water has more negative charge towards the oxygen and more positive towards the hydrogens). In equilibrium, ... | [
"They still have an induced dipole moment.",
"http://en.wikipedia.org/wiki/London_dispersion_force"
] | [
"How does this apply to liquids which do not have a dipole electrical moment?"
] |
[
"How absorbent is our skin?"
] | [
false
] | I know it has to be somewhat absorbent since our fingers get all wrinkly if they stay in water too long. But what's the level of absorbency? | [
"Not my field, but I ",
" taken painter training. Pretty much ANYTHING that gets on you will absorb through your skin to a degree, especially organics. For example, if you get oil-based paint on yourself, you do ",
" want to use paint thinner to get it off because your skin WILL absorb it, and you WILL cause yo... | [
"Your dead skin layer (Stratum Corneum) is basically a keratin layer that is great for keeping out small particles (microbes, dust, dirt, etc). When it comes to things like water, it's fairly resistant (when you get into a pool your body doesn't absorb water until your cells start popping) up to a point where (I b... | [
"DMSO ",
"http://en.wikipedia.org/wiki/Dimethyl_sulfoxide",
" can act as a transdermal shuttle."
] |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"Yes. NASA has planned both a ",
"flyby",
" and ",
"lander",
" mission for Europa. Since it takes years both to design a mission and then fly to Jupiter, it will be quite a while before we see the results of either mission (assuming funding continues). ",
"Currently, various companies are working on a des... | [
"He sees the object appear green. The reason for that is that while the wavelength of the light gets shortened, the frequency remains the same. The reason that wavelength changes is because the speed of light in water is lower than in air. Frequency doesn't change is due to the simple fact that when waves cross med... | [
"Are we planning any missions to explore Europa or Enceladus, the two ice moons with potential subsurface oceans?",
"Edit: Post Cassini missions to be more specific"
] |
[
"If a star’s color is determined by it’s temperature (the bluer the hotter) then why aren’t any stars for an example green or purple? (Only red, orange, yellow and blue)"
] | [
false
] | null | [
"Light from a star is combination of light of many wavelengths. A hotter star produces more low-wavelength high-energy photons, which are more on the blue/violet/ultraviolet end of the spectrum. However, it also produces lots of infrared/red/orange/yellow/green photons. The colour you see is a mix of all these wave... | [
"Here",
" is a nice pic from Wikipedia showing the colour of an idealised black-body as a function of temperature. While the sun is not an idealised black-body it is very close. This image shows that no star could ever appear green as a function of temperature."
] | [
"Yes. The ratio of intensities across the visible range approaches a constant as the temperature goes to infinity. Things keep getting brighter, but the color impression (if you are sufficiently far away to not damage your eyes...) doesn't change any more."
] |
[
"Are drugs addictive in nature or does the addiction depend on the individual consuming it?"
] | [
false
] | null | [
"Well both really. Addiction can be based on a feeling that someone or animal gets from consuming drugs so it's psych0logical that they want and strive for that feeling so they keep taking drugs. But also it can be physical as you in keep taking pain killers and your body gets used to having the dose and you eventu... | [
"Read this and ask a more specific question, that is simply too broad ",
"http://en.wikipedia.org/wiki/Substance_dependence",
" . "
] | [
"To elaborate on this, the body and brain will attempt to maintain homeostasis. So when the drug stimulates a particular receptor or process, the receptor will often be downregulated, less of the neurotransmitter involved will be produced or countervailing processes will be enhanced to compensate. As an example, al... |
[
"What are some of the harmful off-target effects of CRISPR gene editing?"
] | [
false
] | null | [
"That just means that it can cut DNA that it isn't instructed to cut by the guide RNA. Off-target is literally saying it has its effect (cutting DNA) on the wrong 'target'."
] | [
"Normal CRISPR-Cas9 has guide RNA ",
"that gets specificity",
" from the PAM, the base seed sequence (about 11 nucleotides out of the 20), and the upstream sequence (remaining 9). However, 1-2 nucleotide mismatches in the upstream sequence are tolerated by the system, and can result in cleavage. ",
"So when d... | [
"What could be some factors that interfere with the precision though? Normally I would think about CRISPR as having a surgically-precise \"targeting system\" for DNA sequences."
] |
[
"Does your blood type affect your health in any way (except in the case of transfusions and transplants)"
] | [
false
] | For instance, gives you a resistance to certain diseases? Certain drugs are more or less effective? Anything else? (I know those with sickle cell anemia are more resistant to malaria, but it's not a blood type and it's a disease in itself) | [
"Superb answer, very informative, should be used as a model answer.",
"Another interesting area is haemotology and the different risks for venous clots according to blood type ",
"http://www.ncbi.nlm.nih.gov/pubmed/21103665"
] | [
"Superb answer, very informative, should be used as a model answer.",
"Another interesting area is haemotology and the different risks for venous clots according to blood type ",
"http://www.ncbi.nlm.nih.gov/pubmed/21103665"
] | [
"There may be some relationship between A-antigens and influenza, B-antigens and gram-negative bacteria. ",
"Wiki: ABO blood group system"
] |
[
"What makes some people faint at the sight of blood? For that matter, what makes people faint because of things they see?"
] | [
false
] | null | [
"Here is one cause of fainting.",
"http://en.m.wikipedia.org/wiki/Vasovagal_response",
"Specifically \"simultaneous enhancement of parasympathetic nervous system (vagal) tone and withdrawal of sympathetic nervous system tone\" which leads to a precipitous drop in blood pressure which causes a standing person to... | [
"To further add to this description, a basic grounding in physiology might help.",
"The general concept is that your sympathetic system is responsible for maintaining your body when you are active, whereas the parasympathetic system relates to your body at rest.",
"What does this mean exactly? When you are act... | [
"The evolutionary (ultimate) explanation is that a decrease in blood pressure at the sight of one's own blood decreased the likelihood of bleeding out. Those of our ancestors who had this adaptation (of a decrease in blood pressure at the sight of their own blood) had more offspring than those who did not."
] |
[
"Which circumstances must be present to have a tidal locked planet/moon?"
] | [
false
] | I just watched the newest video of were they say, that planets which circle red dwarfs in an inhabitable distance would be too close to the star and therefore tidal locked, just like the moon is tidal locked to our earth. ( ) So, which circumstances must be present, that such a tidal lock develops? Why are for instance... | [
"When the bodies orbit close together, tidal forces are stronger and locking is easier. Small, irregular moons far away from their planets don't get locked as these forces are much weaker (and probably disturbed by other moons). See Wikipedia for a longer explanation with examples ",
"https://en.wikipedia.org/wik... | [
"So first: your picture of Himalia is actually a picture of Iapetus, a moon of Saturn (and is tidally locked).",
"Second, in the case of both Himalia and Phoebe, they both orbit quite a bit farther from the planet than the larger moons. Unlike gravity, the tidal force scales as the inverse of the distance ",
",... | [
"While it is true that a planet in the habitable zone around a red dwarf star would end up tidally locked to the star, that planet could be a gas giant and have its own moons. One of those moons, if it is large and has its own atmosphere, could be habitable as its proximity to the planet would at worst have it tid... |
[
"Can erbium be used to stop a nuclear reaction?"
] | [
false
] | I saw on periodicvideos that erbium is a nuclear poison. It was described as killing any nuclear fission dead. If that is true, at what scale can it do this. Is it possible to produce a sort of safety kill switch for nuclear reactors? Or is the amount of erbium required just too massive? Or is there a reaction that mak... | [
"The particular situations you're referring to (fission reactors or weapons) rely on chain reactions involving neutron-induced fission. Neutron-induced fission reactions often release more neutrons, which can further cause more fission, and so on.",
"If you are able to remove neutrons from the system, for example... | [
"Short answer, poisons do work and are used to control and stop nuclear reactors. Erbium can be used. Other poisons are more common."
] | [
"Boric acid, more specifically. Borax generally refers to sodium tetraborate."
] |
[
"Question about working in the space program"
] | [
false
] | [deleted] | [
"I have a physics degree (BS) and work in the space program, so I can probably give you an idea of what to expect. The most important discriminator here is whether you want to actually work in physics research or intend to use the degree as means to access a career in the space field. The former is quite limited, ... | [
"You can get involved with various space telescope programs with a physics background. Engineering might be better for your aspirations, particularly aerospace engineering. That's not to say that you can't do it with physics, of course. Does your school have an engineering physics program?"
] | [
"I know this is a vague answer, but NASA is huge and has people working in many, many different fields. As you study physics, you will probably be attracted to one specific area or another, and whatever it is, NASA will probably have some research in that area.",
"I would strongly encourage you to apply for an in... |
[
"What theories present in Walking with Dinosaurs have been debunked by now?"
] | [
false
] | null | [
"Hi tjoolder thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follow... | [
"Paleontology"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"If you disagree with this decision, please send a ",
"message to the moderators."
] |
[
"How much force is behind a gasoline explosion at five feet, and what would it do to a human?"
] | [
false
] | null | [
"Cars don't explode like they do in the movies. It's actually pretty hard to have a gasoline explosion with a car because gasoline has to be in it's vapor form to burn, mixed with air in the right proportions (there's a range: upper and lower flammability limits). Really, the only way to get close to a Hollywood st... | [
"The first link below details blast effects, building damage, injuries, levels of protection, stand-off distance, and predicting blast effects.",
"http://www.fema.gov/pdf/plan/prevent/rms/426/fema426_ch4.pdf",
"The second is a masters thesis about blast profiles and two primary methods of determining them, revi... | [
"There's a mythbusters where they do this exact set up with different chemical reactions at different distances and also underwater. From what I remember being underwater past 10 or so feet with a gasoline explosion you'd be fine, so the movies are actually true to a point. I don't remember the exact science but I ... |
[
"Why does rocking make people sleep faster/better?"
] | [
false
] | I always have the best naps when I'm on a rocking chair or on a boat, is there some sort of chemical released in the body when moving back and forth in a wave-like motion? | [
"Hey guys, please only post if you have relevant experience and can answer follow up questions!"
] | [
"As far as I know there is no neurotransmitter directly released by rocking your body, nor by any simple physical movement of the body.",
"It is thought that rocking back and forth mimics what our parents may have done (rocking us as infants) and thus is a learned association. Learned associations are very common... | [
"I've actually read about this while I was studying hypnosis.",
"What I know about this is merely the physical process, so I don't know if any sort of chemical is released to the body",
"While you rock a person it creates a loss of equilibrium, this loss of equilibrium makes the person relaxed and makes it easi... |
[
"[AskScience AMA Series]: I AMA late-stage Ph.D. student in management, with research interests spanning intelligence and personality testing in selection, interviewing, newcomer socialization and early turnover, and job attitudes. AMA"
] | [
false
] | My opinions may be somewhat personally biased (like my beliefs about nature/nurture in intelligence), but I am familiar with the literature and will try to present both viewpoints where appropriate. Consider my field the intersection of psychology and business, describing/explaining/predicting/controlling cognitions at... | [
"What do you think about personality questionaires, Meyer-Briggs for instance?",
"Any opinion on the Peter principle or Parkinson's laws?"
] | [
"I am for them as a selection measure, but not the Meyers-Briggs. As noted in another comment it:",
"a) forces people into dichotomous personality \"types\", rather than allowing for within-trait variation on a continuum, which treats meaningful variance as error. This is problematic, because a 49% score on extra... | [
"I'm pretty interested in I/O psychology but as an undergraduate im still conflicted as to what I'd like to study in grad school. Any readings you can recommend to me to get an in-depth description of your field?"
] |
[
"Need help identifying this fungi/mold/spore thing."
] | [
false
] | [deleted] | [
"My notpron skills tell me it is ",
"Rhizopus oligosporus",
". Aww, they're ",
"adorable",
". "
] | [
"Good try, but that image is labeled incorrectly. That's not what ",
" actually looks like, ",
"this is",
"."
] | [
"It looks to be some kind of a bread mold thing. I'll have a look through my copy of Mushrooms Demystified, but its going to ask me for microscopic evidence.",
"It looks kind of like maybe ",
", as I'm guessing it should be something familiar or important. I'm too tired to track down an exactly matching pic rig... |
[
"Why does the water froth and bubble when I'm cooking pasta and leave the top on the pot?"
] | [
false
] | [deleted] | [
"When you're cooking pasta, some of the starch and protein in the flour comes out into the cooking water.",
"The surface tension of the water is increased by the addition of starch and protein from the pasta, so the bubbles formed by violent boiling don't burst as quickly, and the froth forms. As the froth forms,... | [
"The pressure increase from an unsecured lid is trivial; it's why the lid bumps and rattles at a boil."
] | [
"Is the froth (which is made from protein if i understand you correctly) stabilized by the higher air temperature with the lid on? (like when baking a baiser) "
] |
[
"How do bacteria and other microscopic organisms become anti-biotic resistant and what happens if one becomes completely resistant?"
] | [
false
] | Bacteria and other microscopic organisms become resistant to different types of antibiotics. Is it possible that there will be no more treatments and bacteria will become completely immune? If so, are there anyways to reverse what has happened and the bacteria again becomes susceptible to antibiotics? | [
"Most antibiotics act by binding and inhibiting the activity of a specific bacterial enzyme. This requires the antibiotic to diffuse through the surface of the cell and reach its target enzyme. Bacteria can resist the effects of antibiotics through a number of mechanisms. Some common mechanisms are:",
"1) The ... | [
"recombination ",
"Prokaryotes do not have recombination. ",
"due to recombination [...] mutations occur",
"Mutations and recombination have nothing to do with each other. Recombination shuffles alleles, decoupling them, and allowing selection to happen on individual genes, rather than whole chromosomes. ",
... | [
"\"is it possible that there will be no more treatments?\"",
"Even if bacteria become completely resistant to all known antibiotics, we can still probably treat them with a bacteriophage - a virus that kills bacteria. It was used in the past as a therapy, particularly in the Soviet Union I believe, and presents s... |
[
"What is caffeine used for in the organisms that produce it?"
] | [
false
] | null | [
"The coffee tree uses it as a poison. Caffeine in high doses is lethal which is why the coffee tree produces it. We are able to consume coffee due to our enormous size. The tree uses is as a deference mechanism against insects which are incredibly tiny, making the caffeine an effective bug repellent. "
] | [
"Caffeine in plants acts as a natural pesticide, it can paralyze and kill predator insects feeding on the plant. High caffeine levels are found in coffee seedlings when they are developing foliage and lack mechanical protection In addition, high caffeine levels are found in the surrounding soil of coffee seedlings,... | [
"Worldwide popular psychoactive drug caffeine is a plant alkaloid, and also a vasoconstrictor in humans. Caffeine (1,3,7-trimethylxanthine), among other methylxanthines, is a known pesticide, and this is thought to be its natural function in plants In humans, the stimulant effect is caused by caffeine’s ability to ... |
[
"What is the most primitive organism that can get addicted to drugs?"
] | [
false
] | [deleted] | [
"I love this question because it allows me to post the following paper:",
"Time flies like an arrow. Fruit flies like crack? by J Hirsh",
"As opposed to the human population, addiction to drugs of abuse is not a great problem in insects, at least as far as we are aware. Nonetheless, the fruit fly, Drosophila me... | [
"Yes but organisms need a certain level of complexity to be addicted (not just dependent). They need to be able to perceive the lack of the thing they're not getting and want it which is a question of consciousness, and also need enough neural complexity to sensitize to the substance. If you're a squid with one neu... | [
"I'd would assume it extends downwards on the size scale as well. The smallest living organism that can be addicted to a substance is likely only limited to our delivery and measurement tolerances.",
"Addiction is essentially just leveraging natural impulses after all isn't it? It's been over thirty years since D... |
[
"How do supermassive black holes reach their size?"
] | [
false
] | Let's make a few presumptions: Black holes are remnants of massive stars. The Eddington limit states that a star can only reach a few hundred solar masses at max. A "newborn" black hole would only have a few hundred solar masses at max. So the only way for supermassive black holes to reach their size would be to consum... | [
"So first of all, this is an active area of astrophysics research and no one knows the full answer, but we ",
" know a lot more than you assume.",
"First of all, we see black holes merge, quite regularly in fact!, thanks to the gravitational wave detector called ",
"LIGO",
". ",
"The first such merger wa... | [
"This was super helpful for me, thanks!",
"It's super crazy to know that we just flat out don't understand how black holes can bypass the parsec problem, I hadn't heard of that!",
"Are you aware of current research around this subject?"
] | [
"The simplest solution is to introduce a third black hole. This allows for much more complex gravitational dynamics including (rare) scenarios where two of the BHs get put onto a close orbit (from which they can then lose energy via gravitational waves) while the third gets slingshotted away.",
"Alternatively, yo... |
[
"Would gravity alone make the planets face themselves with the same side towards the sun? (Like a ball on string)"
] | [
false
] | My understanding is that if you rotate an object around a certain axis outside that object (orbit) then it tends to face the same direction towards that axis. Also common experience with a ball attached to a string tells me that it should behave this way since there's only one force acting on it (as gravity acts on the... | [
"This is an effect called ",
"tidal locking",
" and yes, gravity alone is responsible for this. It is a little like a ball on a string, actually.",
"As two objects attract each other, it can create a small elongation of a planet or moon towards the acting body. In exaggeration, think of the moon being pulled ... | [
"The effect starts immediately, yes. It, however takes time as tidal locking is applying a torque to the planet, thats all. This torque alters the rotation speed of the planet slowly to match its orbital speed. The same way a car applies torque to its wheels, it doesn't mean that the car immediately reaches its top... | [
"Thank you! Sounds like you'd also agree with this sentence - \"If the bodies of the solar system were set up with just orbital speeds (no spin) they would always point (face) to their nearest attractor (neglecting the other gravitational forces)\"\nIf so then do the astronomers count the spin of the body as zero o... |
[
"Does the perceived size of the moon actually increase as it moves from the horizon to overhead? Or is it just an optical illusion?"
] | [
false
] | I'm in a bit of a bet with my wife. She swears the moon is bigger in the sky when it's near the horizon and gets smaller as it gets higher. I've told her it's the same size, but only looks bigger because of the difference in perspective. Once it is higher up, there is more empty sky surrounding it which makes it seem s... | [
"You win the bet. The moon does ",
" larger to the eye near the horizon, but it's an illusion. Images like ",
"this one",
" allow a direct comparison of the apparent size of the moon at different points above the horizon and show that it's constant. "
] | [
"Yeah, but there's no correlation between its apparent size and position in the sky."
] | [
"The Moon illusion is an optical illusion which causes the Moon to appear larger near thehorizon than it does higher up in the sky. This optical illusion also occurs with the Sun andstar constellations.",
"https://en.m.wikipedia.org/wiki/Moon_illusion"
] |
[
"What is the responsible thing to do with the Hubble Telescope when it is decommissioned?"
] | [
false
] | Should we disassemble it and bring the pieces back down to earth to avoid wasteful debris in space? | [
"That's really not an option. There are essentially two choices:",
"1: De-orbit the telescope so it falls into the atmosphere and burns up in a controlled way. The mirror is large enough that it will survive and reach the surface of the Earth, so you don't want it coming down somewhere you can't control. ",
"2:... | [
"I feel compelled to add, that Hubble is still an active observatory and continues to produce world class science. It's probably going to operate through at least 2025, and might go longer. It's our best window to the ultraviolet spectrum and that capability will not be superceded or replaced until AT LEAST 2040. I... | [
"No, not yet, but it is fully expected to (I hear). It entered safe-mode because of a coding error in some new routines they are using to prolong gyroscope life, using 3 gyros to slew the telescope and then 1 to keep it pointed. They've identified the problem, and will fix it soon."
] |
[
"Why humans and most living things on earth are symetrical? (2 legs, 2 arms...)"
] | [
false
] | I mean, even my nose and mouth are right in the middle of my face, not on a side, why is that? | [
"Now that that's out of the way, there are multiple ways to approach this question. One interpretation of your quesiton would be, ",
" My hunch would be yes, but first let me take another angle at it, based on evolutionary history.",
"Most animals that you can think of (fish, birds, worms, spiders, humans, etc.... | [
"To add to this, a ",
" of cephalisation seems to be the reason that ",
" organisms (",
") do ",
" show this type of symmetry - they are either ",
" or ",
".\n",
" is like a ",
", the animal is ",
", regardless of where it is cut from. Scientists think that this may be advantageous for sessile org... | [
"Simply put, symmetry in development is easier to regulate than asymmetry. When cells start to differentiate, they do so based on concentration gradients of various signal proteins. So if signals are produced from the center of an organism, a single genetic network is all that's necessary to create symmetrical body... |
[
"Is the danger of loud noise related to absolute noise or noise above ambient white noise?"
] | [
false
] | I got to thinking about this because I got an air cleaner fan and now need to keep my computer volume at a higher level to get the same amount of noise when the white noise from the fan is also going. Does white noise cancel out the dangerous effects of sound or does it add on or do nothing? For a practical example, ... | [
"Sound doesn’t cancel out like that. If you have your music louder to hear it over the white noise, then the music is actually louder. ",
"In a shooting range adding a loud white noise generator would just raise the ambient sound level. Or if it was louder than the gun shots, would mean everyone would need to wea... | [
"It is the absolute pressure of the sound that damages your body. Not the relative amount. For instance adding 10dB of extra sound to a 100dB existing sound would make the absolute sound level 110dB. Shortening your allowed exposure time from 15 minutes to less than a minute. But at those danger levels, your ears w... | [
"Thanks! "
] |
[
"How does the drug Adderall calm and let an ADHD patient focus?"
] | [
false
] | null | [
"\"ADHD drugs fall into a class of medications known as stimulants. ADHD stimulants boost levels of two neurotransmitters, or chemical messengers in the brain, known as dopamine and norepinephrine. Dopamine is thought to play a role in memory formation and the onset of addictive behaviors, while norepinephrine has ... | [
"As a follow up, why does Adderall/Ritalin seem to calm down people with ADHD but speed up people without it?"
] | [
"Amphetamines help anybody focus. "
] |
[
"What exactly would I need to do to turn heat into electricity?"
] | [
false
] | null | [
"You can do it directly with the ",
"Seebeck Effect",
" using a ",
"Thermoelectric Generator Unit",
".",
"The difference in temperature between the hot and cold side of the panel directly outputs electricity. This is one of the ways they generate power on deep space probes. They use a ",
"radioactive is... | [
"A ",
"steam turbine",
" with an ",
"electric generator",
" would be a good start.",
"The heat is fed to a body of water in order to produce steam, which is fed into the turbine where the steam pressure forces the turbine to rotate and this rotation is what makes the generator generate electricity.",
"T... | [
"First, you need a hot thing ",
". Heat's not enough: there must be a temperature difference to extract energy. This is the #1 problem that trips up amateur energy inventors.",
"Second, there are two basic strategies: ",
"a) If you heat and cool a gas it will expand and contract: you can use the gas pressur... |
[
"Do extended-release pills release medicine at a constant rate, and how can they stay \"inside you?\""
] | [
false
] | I'm taking plenty of meds right now. One is a 12 hour pill. 1) Do pills release at a constant rate, or is it something changing like an exponential decay? 2) How do pills stay "in you" for 12 hours? Wouldn't your digestive system have expelled it by then? | [
"I'm having difficulties finding a specific reference for you, but the complete digestion process normally takes longer than 12 hours, I'm finding references up to 75 hours but 24-48 hours for an adult is expected.",
"Time release pills are designed to take a while to decay, this is usually a rate dependent on th... | [
"Source",
": The pills often are made out of very slow dissolving materials or have tiny holes that the medicine can leak out very slowly. Others, like ",
"Adderall",
" have the drug in different salts which metabolize at different rates. Normally, when a drug is digested, the concentration of the drug in the... | [
"Wikipedia drugs pages have a side panel that can include \"half-life\". Many of the slow release drugs have a half life of 2 days or more, so that the concentration builds up over days, not hours. The level of drug presumably still oscillates, but there is no drug-free period. (You can often change the most-drug-... |
[
"Have whitening toothpastes improved measurably in recent years, or is it all hype?"
] | [
false
] | Has the effectiveness of whitening toothpastes improved measurably in recent (or not so recent) years, or is it all hype? What, if any, ingredients are responsible? | [
"Dental researcher here. Whitening toothpastes ",
" help. The abrasives only remove surface staining. The problem is that yellowed, deeply stained teeth have the underlying dentin as the problem. You need to penetrate all the way through the enamel layer, between all of the hydroxyapatite prisms to get to the den... | [
"Here in Australia, there's a consumer group called Choice that often reviews, compares, and calls out bad products (to paying customers, so as to remain neutral) in a clear and methodical (if not scientific) manner. They recently did a release that was on the news: ",
"http://www.smh.com.au/lifestyle/beauty/whit... | [
"All toothpaste is abrasive, that's how it cleans the teeth. You can actually use toothpaste as a polishing compound. "
] |
[
"Hypothetical question regarding genetics and ageing"
] | [
false
] | Hi again, Been reading ageing and found that as we age, DNA mutations/damages accumulate from sources like free radicals, oxidative stress, UV rays, carcinogens, radiation, endogenous damage (replication errors, synthesis errors), etc. The average lifespan of an organism is dependent on how efficient and extensive DNA ... | [
"Aging (I won't give in to your British spelling!) is remarkably complex and many unknowns still exist. There is a lot of aging theories that are DNA damage-centric, which is a definite core component to what's going wrong.",
"One of the core things going wrong in aging is your stem cell populations accruing too... | [
"Hello! Thanks for the reply!",
"I haven't heard much about the ",
"stem cell theory of ageing",
" and the linked Wikipedia article is rather short as well. I was not aware the \"main theory\" for why hair goes grey is due to loss of stem cells. However, I am very interested in this and would like to know mor... | [
"You'd probably get more in-depth answers from someone in the stem cell or aging field, but I'll do my best.",
"[",
"http://en.wikipedia.org/wiki/Adult_stem_cell](This",
" article) is a good start to see all the main types of adult stem cells. You have these populations all over where large-scale cell growth... |
[
"How does moment of inertia mesh with inertial reference frames?"
] | [
false
] | Disclaimer: I am not a physicist, or a scientist of any kind, it's just something I'm fascinated with. I just haven't been able to wrap my mind around this question. I don't need the math, just the concept that explains it. In physics, I understand that there is no privileged frame of inertial reference. You can pick a... | [
"Rotating frames are not inertial. If you review the theory you'll see the transformations between inertial frames do not include time-dependent rotations.",
"Moreover, this has nothing to do with inertia of any kind, and so with the moment. This is pure kinematics."
] | [
"Thanks! If I'm reading you right (I'm a complete noob at this), then the answer to this question:",
"Does the concept of inertial reference points even work with rotational inertia?",
"... is \"No?\""
] | [
"You mean angular velocity, not rotational inertia. Inertia has units of mass, it's not what you want. In that case, the answer is no."
] |
[
"What is the current state of light based computing? What are the problems holding us back?"
] | [
false
] | I know the idea of light based logic has been around for decades and researched for just as long, but I hear little about it. With Moore's law starting to get caught up in physics problems, it seems like the logical way forward. Has light based computing even been prototyped? Is there no currently visible way forward? ... | [
"I don't know what the current state of doing actual computing with light is. I suspect \"far off. Very.\"",
"However, the field of silicon photonics is heating up like crazy right now. The distinction here is that we're only talking about the communications tech between the standard silicon chips, not changing h... | [
"A couple of critical issues with optical computing that rarely get mentioned:",
"Photons are huge compared to electrons, and generally the devices that manipulate them are bigger than the photons themselves. A MOSFET for manipulating electrons can have a gate dimension of 0.5 nm and still be much bigger than the... | [
"The problem with using light to do computing is basically ",
"\"fan out\"",
". How many follow on gates can you drive with the result of a given logic operation. This problem partly became the reason ",
"tunnel diode logic",
" never took off in the 1960's. Even though it had the promise of gigahertz clock... |
[
"Were there enough complex elements in the universe to support life 15 million years after the big bang?"
] | [
false
] | There's an currently posted over in suggesting that 15 million years after the big bang, the CMB would've been around the right temperature to support life throughout the cosmos, even on planets far away from their star. There's a lot of layman speculation about whether other conditions necessary for life such as compl... | [
"No. As dullertap said, stars didn't even form until ~200 million years after the big bang. Even then, there was only Hydrogen and Helium. All other elements are created by the processes within stars or during a supernova eruption.",
"The first generation of stars went supernova and spewed forth a variety of elem... | [
"There were no stars at 15 million years after the big bang so there certainly would not have been any planets that would be capable of supporting life as we know it. The first stars were formed ~200 million years after the big bang. ",
"Source: ",
"http://starchild.gsfc.nasa.gov/docs/StarChild/questions/quest... | [
"TH OP's article has speculated that the CMB would be at the correct and reasonably narrow temperature range for water to be liquid at around 15 mill years ABB (after the Big Bang). But this particular factor in the creation and/or sustenance of life is just one of many. Oxygen possibly existed at that time but in ... |
[
"Sunrise temperature dip?"
] | [
false
] | So my co workers & I watched the sun come up this Morning and observed the normal 5-10 degree drop & subsequent rebound of the temperature. After a little discussion it became clear no one has a good answer as to why this occurs. So my question is why does this happen? | [
"Radiational cooling of the atmosphere and ground has the most effect on the drop in nighttime temperature. The decrease in temperature continues for a short amount of time after sunrise because the input of energy from the sun has yet to equal the loss of energy from the ground and air. The temperature will begin ... | [
"Thanks it was my best guess I'm glad to know I was on the right track:)"
] | [
"I don't know, but I will hypothesize.",
"I think the air at higher altitudes is heating up first due to the way the sunlight hits the atmosphere. This causes the air to rise, pulling the air below it up to fill the void. Then, the air on the ground around you (to the west I guess) would move in to fill the air ... |
[
"Are the ideas behind the Singularity at all legitimate?"
] | [
false
] | I know that there is no definitive answer, but are singularitians complete jokes to all real scientists? Ive been reading Kurzeil's book and it seems sensible to me, but for all I know its the same thing as people fifty years ago predicting that we would live on the moon. I would love to hear some personal opinions fro... | [
"Read Scott Aaronson discuss it ",
"here",
", with Eleizer Yudkowsky chipping in on the comments section. Pharyngula is ",
"quite harsh",
" in its criticism of Kurzweil's claims.",
"While 'real scientists' might accept the possibility of a singularity, it is such a distant possibility with so many uncontr... | [
"My opinion is that Kurzweilians are afraid of death. ",
"The \"Singularity\" is a joke to nearly every scientist I know. With a rare occurence of \"eh, maybe someday?\""
] | [
"The only thing we can reliably predict about the future is that people will be just as gullible there.",
"What pisses me off is that this guy speaks as some sort of authority... on the future. What the hell? Is this like some sort of... reality sci-fi for people?"
] |
[
"When light strikes a metal, a photon can excite an electron to leave. Does the metal ever run out of electrons?"
] | [
false
] | null | [
"No. While releasing more and more electrons, the Fermi level will become lower and lower, because the electrons with largest kientic energy will be ejected. This increases the work function of the metal until the energy of one photon is not sufficient to excite another electron to the vacuum level. At this point y... | [
"Yes, this is called the photoelectric effect; Albert Einstein won the Nobel Prize in physics for understanding it. It is the basis for solar power, although photovoltaics is a bit more complicated than the photoelectric effect.",
"If too much charge is removed from a solid, the remaining charges start to repel ... | [
"I agree with him by saying that a Coulomb explosion will happen before the metal runs out of electrons. The smaller the particle (metal cluster) the more likely a Coulomb explosion becomes because the free energy difference of lattice formation is smaller compared to a bulk metal.",
"edit: I just did a little bi... |
[
"Is it possible for a living organism to evolve in a different wavelength from visible light?"
] | [
false
] | null | [
"It would have to be ",
" transparent to visible light. That's so implausible we can dismiss it out of hand. The glass in your windows is very, very transparent, but you don't have any trouble seeing it."
] | [
"This question has been removed because highly speculative in nature. Exceedingly imaginary hypotheticals often invite non-scientific speculations.",
"For more information regarding this and similar issues, please see the ",
"FAQ."
] | [
"Well, nature has gotten sort of ",
"close",
".",
"Problem is, a lot of the things animals need to be made of happen to reflect visible light."
] |
[
"How to find x,y,z rotations between two given coordinate frames (or planes)?"
] | [
false
] | null | [
"The rotation matrix that maps between these coordinate systems is given by ",
"R",
" = ",
" • ",
"’",
",",
"where ",
" is the unit vector in the i",
" direction in the unprimed coordinate system, and ",
"’",
" is the unit vector in the j",
" direction in the primed coordinate system."
] | [
"Sorry, what are i and j? x and y? "
] | [
"i and j are indices that represent x, y, and z."
] |
[
"Why can foxes eat raw chicken while we cant, and how did we eat meat before we could cook it?"
] | [
false
] | the title says it all | [
"People don’t get sick every time they eat raw meat. We cook food to mitigate that risk, and it helps with nutrient absorption. I met a health inspector who said he’d rather eat raw chicken than unwashed vegetables."
] | [
"Also, foxes don't store the chicken in the fridge for a week before they eat it. Eating a freshly killed chicken is a lot less dangerous (from a food poisoning perspective) than eating a chicken breast that's been sitting around for days."
] | [
"It is very unusual for a disease to be transmissible between species. Humans have made many dangerous diseases that are transmissible between species from centuries of living in close proximity to domesticated animals.",
"It should be noted that decaying meat is dangerous because of decomposers like botulism tha... |
[
"How do Sperm Whales find Giant squid?"
] | [
false
] | They dive to extreme depths to find the squid but how do they actually locate them? Do they use sonar or smell or some other sense to hone in on them? I imagine its pitch black down there and the ocean is huge so it blows my mind they are able to survive off such a strange and hard to get to diet. | [
"They don't solely eat giant squid- from what we can tell, they require about a ton of food per day, so they eat all kinds of fish and squid. That being said, giant squid are obviously the most well known prey item for sperm whales as far as humans are concerned, and likely a very desirable one for the whales, sinc... | [
"Wow, that’s just amazing."
] | [
"It doesn't hurt that we think large deep-sea squid like the giant squid and the colossal squid are actually remarkably common.",
"Judging by how many squid beaks we find in the stomachs of almost every whale that's ever been cut open, the whales clearly don't have a hard time finding the squids."
] |
[
"Is there a way to calculate the amount of heat energy released during the oxidation of a certain amount of a certain substance?"
] | [
false
] | null | [
"enthalpy data is tabulated, if you know the combustion reactions of interest, you can work out the theoretical energy released by looking at the weighted sum of products and reactants.",
"practically reactions don't go to completion, so in a real scenario you would expect to typically get less.",
"all of this ... | [
"Are you trying to calculate ab initio or through experimental methods? There are ways to do both, but experimental will likely be a lot more accurate. Some form of calorimetry might be your best bet."
] | [
"Yes, scientists have tabulated the energy released in kJ/mol or kJ/kg. Of course, variations in pressure, temperature, solvent and solute impurities, radiation, magnetic fields mean the value is never perfect, but for engineering/practical purposes it's good enough."
] |
[
"When you drop a pebble in water, you hear a sound wave, and you see ripples along the surface. Is the distance between the ripples on the surface the same as the wavelength of the sound wave?"
] | [
false
] | null | [
"What you hear is the soundwave as it travels through air. So it will have a different wavelength vs. traveling through water.",
"The waves you see are not indicative of the sound's wavelength. It is a physical reaction to the pebble breaking the water's surface and displacing water in a cycle."
] | [
"The ripples you see on the surface of the water are not sound waves - they are ",
"gravity-capillary waves.",
" It is entirely different physics which govern them (gravity, surface tension) so there is no reason for them to by synced with the sound waves in either the water or the air."
] | [
"Interesting question, and as others have pointed out, the answer is no. The mechanisms which create the ripples are different from those that create the sound. When a rock drops on the surface of a body of water, it will create three distinct sets of waves. The ripples are the gravity-capillary waves that another ... |
[
"What (if any) differences exist between delta-9 THC derived from conventional sources vs delta-9 THC derived from hemp?"
] | [
false
] | The past couple years, delta-8 THC was being screwed as a legally produced alternative to conventional delta-9 THC products. Recently, I've seen new products marketed as containing delta-9 THC, somehow legalized under the same provision. What's the difference between this hemp-derived d9-THC and traditional d9-THC? Is ... | [
"No one seems to be answering your question, so let me provide some context: The reason D9 edibles are now legal is because those edibles are technically under the legal limit of 0.3% D9THC.",
"Some opponents say that the law also specifies that these hemp products must not be \"intoxicating,\" but obviously you ... | [
"This goes even farther with edibles. As it is.3% by weight per the federal Farm laws including hemp regulation. Therefore you can make an edible that weighs 5g that has 15mg D9. Which is more than enough to get the occasional user pretty high. It usurps states rec and med laws a bit, but who cares. I think there i... | [
"it is a super petty legal distinction. If you were to eyeball a hemp plant and a marijuana plant the \"lay person\" could not tell the difference. Untrained law enforcement cant tell the difference either and just think you have weed on you. They are two different plants but part of the same Cannabaceae family the... |
[
"Is there anything you can wrap around a magnet to block the magnetic field?"
] | [
false
] | [deleted] | [
"Magnetic shielding is made of materials with high magnetic permeabilities, like iron."
] | [
"Nuclear magnetic resonance spectrometers (and magnetic resonance imagers) use a main superconducting electromagnet coil to generate a huge magnetic fields. Some of these instruments use \"active shielding\" which is a another superconducting magnet wound in the opposite direction to the main coil. This gives an op... | [
"Yes, mu-metal is often used to sheild equipment that is sensitive to external magnetic fields"
] |
[
"Do freeze-dried fruits have the same nutritional value as fresh fruits?"
] | [
false
] | Are freeze-dried fruits less nutritious than fresh fruit? Is there any kind of damage that the freeze-drying process does? I'm not talking dried, sugared fruits, I mean just pure fruit freeze-dried. | [
"This question depends heavily on how one defines ",
". If you mean specifically the inorganic mineral content, then the answer is flatly yes, freeze-dried fruits have the same inorganic mineral content as fresh fruits. On the other hand if you are more interested in the content of various organic compounds in ... | [
"No. Only the water is sublimated. ",
"Imagine the evaporation of spilled orange juice, which contain lots of water soluble compounds and works well as an analogy to our dried fruit. Even at normal atmospheric pressure the water will eventually evaporate, leaving behind a sticky mess of what had been the water... | [
"Couldn't removing water also remove some of the water soluble vitamins?"
] |
[
"As the solar system orbits the galactic center, why does it have a helical precession?"
] | [
false
] | null | [
"That's not ",
"precession",
", precession happens to a spinning body. The Earth spins, it's an oblate spheroid with water and a Moon, so its rotational axis rotates with a 26,000 year period - that's precession.",
"The solar system bobs up and down through the galactic plane over a period of 60 million years... | [
"The reason it bobs is that the mass in the Galaxy is located not just in the center, but throughout the disk. So when the Sun is in the midplane of the Galaxy, it's at a lower gravitational potential than when it's above or below the midplane. When it's out of the midplane, the disk pulls the Sun back toward it, c... | [
".",
"I don't know why this keeps coming up, but there seems to be a large segment of the occult/conspiracy subculture that has become very fixated on this idea. Planets orbit around the Sun. The Sun orbits around the center of the Galaxy. It makes absolutely no difference whatsoever",
" what the orientation of... |
[
"Why do humans feel hot/heat up when we exercise?"
] | [
false
] | Whenever I'm running, after about 30 minutes I feel so much hotter than when I started. Is my body actually heating up, or am I just feeling hotter? Also, why is this happening? Wouldn't this mean that we're inefficient at converting energy into momentum? Is there an evolutionary significance to this? Thanks! | [
"Cellular respiration is exothermic, meaning that the process of supplying energy to run a cell releases energy. When you exercise, your muscle cells do a lot of respiration to produce the chemicals that cause muscles to contract, and that contraction in turn is exothermic. Essentially, cell respiration is a very s... | [
"Like most physical processes, moving your muscles produces waste heat, which increases your temperature. ",
"Yes, we are not capable of 100% efficient transfer of energy into momentum; neither is any other macro-scale physical process in the universe."
] | [
"In order to maintain your body temperature you begin to sweat, as the evaporation of sweat lets you cool down. Yeah, you are getting really a bit hotter while doing sports.",
"As to efficiency: Your body gets more efficient in doing certain processes warm, than doing them at his normal temperature. Warming up be... |
[
"What drives the molecular change in catalytic enzymes?"
] | [
false
] | The example I'm specifically thinking of is the F1 domain of the ATPase, which creates ATP from the proton motive force. The translocation of protons causes rotation of the the F1 domain subunits. Which drives a conformational change between tight, loose, and open binding conformations and these have different affiniti... | [
"tight conformation the ADP & Pi ",
"That's pretty much the idea. The ADP and Pi are pushed so close together (in just the right conformation) that they can't help but react. "
] | [
"yes, the energy transmitted from the PMF via conformational changes is what forces the atoms past the small energy barrier - it is almost like snapping together building toys (K'Nex, Lego, etc)",
"edit: not all enzymes function in this fashion; they are many, many different protein-catalyzed reactions"
] | [
"Chemical reactions ",
" occur by molecules bumping into each other; pushing them into each other is not very different. (which you can also do at the macroscopic scale; some reactions require high pressures)"
] |
[
"Why do dogs chase their own tails? Do they not realize its part of them?"
] | [
false
] | null | [
"There was not a single meaningful sentence in that entire article (this is not exaggeration). That is ",
" piece of garbage and \"woo\" I have ever read. In no conceivable way does it belong in ",
"/r/askscience",
". "
] | [
"There was not a single meaningful sentence in that entire article (this is not exaggeration). That is ",
" piece of garbage and \"woo\" I have ever read. In no conceivable way does it belong in ",
"/r/askscience",
". "
] | [
"You piqued my curiosity so I moseyed on over to JStor/Pubmed/Google and looked for papers on cats/dogs and consciousness and didn't find anything useful. The behavior of cats/dogs suggest (strongly) that their tails are used in emotion and base feelings that can comprise the subconscious.",
" It follows that the... |
[
"My seven year old asked this: if Mercury suddenly didn't exist (for example if it were towed away from our solar system somehow) would that have an effect on the Earth?"
] | [
false
] | I'd like to expnad on this question. Would the removal of any of the planets would have an effect on Earth. Obviously, removing the Moon would have drastic consequences - but do the other planets and asteroids have much effect on Earth's orbit? Also kind of related: could we ever mine enough material from the Moon or t... | [
"Gravitationally not really, since Mercury is pretty small and pretty far away (the far away part being most important). Doing some back of the envelope calculations, the gravitational acceleration of Mercury at Earth's average distance from it is about 10",
" g. That's ",
" of the acceleration from gravity at ... | [
"I'm sorry, but isn't that acceleration relevant when we talk in astronomical time?"
] | [
"Not exactly, because on astronomical time scales you're still dealing with astronomical distances. Even 100 m/s is pretty minuscule when you have to travel distances in space."
] |
[
"During embryogenesis how do cells know where to go and what to differentiate into?"
] | [
false
] | How does an individual cell know where it should go, what all proteins it should produce, when and along which axis it should divide and when it should die(if required)? Was this perfected with trial and error during evolution? Can we study how multicellularity evolved by looking at how a zygote becomes a multicellular... | [
"This is a GIGANTIC QUESTION. Let's see...\n1. An individual cell knows what to do, in general, from a combination of internal (cell autonomous) and external signals. Cells, when made from parental cells through mitosis, can have different proteins within its cytoplasm and nucleus than its sister cells through diff... | [
"Thanks for the answer. During cell division how is it determined which cell gets what all components of the parent cell? "
] | [
"So, except for some cases (like the formation of a human egg), one daughter cell doesn't get ",
" the components of the parent cell. Rather, it gets a different concentration of something compared to the other cell. That something could be:\n-mRNA\n-transcription factor(s)\n-signaling molecule(s)\n-etc.",
"For... |
[
"If dopamine is released into our brains when we eat foods we like, what is released when we eat foods we think taste bad?"
] | [
false
] | null | [
"I believe what matters more is the specific pathway in the brain which is activated. ",
"Dopamine is a neurotransmitter associated with the Ventral Tegmental Area and Substantia Nigra, which have a couple major projections. One of those projections is called the meso-limbic tract, which communicates pleasure sig... | [
"I don't believe what ",
"/u/badasswizard",
" said is correct. GABA is an inhibitory neurotransmitter, which I would take a guess at saying that it inhibits the activity in the amygdala due to it's anti-anxiety properties (of GABA and GABAergic drugs such as alcohol and benzodiazepines).",
"But to answer your... | [
"One easy way to think about this that doesn't require explaining multiple different pathways within the brain (which are definitely important but needlessly complex in this case) is to think in one level above the neurotransmitter level. As has been mentioned previously, the effect of dopamine is entirely dependen... |
[
"What kind of experiments do astronauts do in the ISS?"
] | [
false
] | null | [
"Come on man, first result from googling 'experiments on ISS.'",
"http://en.m.wikipedia.org/wiki/Scientific_research_on_the_International_Space_Station"
] | [
"Eh well now at least you can post a more specific question if you'd like."
] | [
"fuck. thank you though"
] |
[
"Why isn't the Sun Blue?"
] | [
false
] | [deleted] | [
"There are two things going on here.",
"The peak in color associated with the temperature of something is given by Wien's displacement law:",
"https://en.wikipedia.org/wiki/Wien's_displacement_law",
"If you plug in the temperature of the surface of the sun, 5777K, it says the peak should be at about 500nm, wh... | [
"The flame example is misleading you a bit. It is true that hot gas molecules don't emit a smooth blackbody spectrum, because the emission spectrum of an object is the product of the ideal blackbody spectrum and its absorption spectrum. Many people forget about the second part, i.e. Kirchhoff's law of thermal radia... | [
"Not quite! Scroll down to the bit on the frequency-dependent formulation in the wiki page you linked. The constant there doesn't fit c=fλ with the Wien's law constant.",
"The deal is that for the power/flux/intensity distribution, you're really plotting dP/dλ, where P is your power or whatever. If you plot dP/df... |
[
"Have we ever had any evidence that light travels faster than 299,792,458 m/s?"
] | [
false
] | null | [
"Well, a lot of physics experiments are capable of testing the speed of light, insofar as they would go haywire if the speed of light changed. So, basically any optics experiment that anyone is doing anywhere. And if the speed of light changed suddenly, we'd also see an alteration in the apparent motion of the plan... | [
"There have been plenty of attempts to detect light or anything else traveling above ",
", but no solid evidence has ever been found of anything doing so."
] | [
"Thanks! What's the most recent test?"
] |
[
"How common are diamonds really?"
] | [
false
] | I hear a lot on Reddit about how diamonds are actually fairly common, but are marketed as being rare and special in order to command higher prices - much higher than the value added by mining, refining, cutting etc (which I imagine is significant in itself - after all, an uncut diamond just looks like a cloudy rock). I... | [
"I think diamonds are rare in any sort of absolute sense. From wiki, 26 (metric) tons of diamonds are mined annually (valued at about $9 billion) and about 100 tons are synthesized yearly with a total of 900 tons of diamonds mined in human existence (and as 1 ton of diamonds can make 5 million 1-carat diamond ring... | [
"Try not to use lmgtfy in this subreddit. (His link is a google search of \"de Beers Monopoly\")."
] | [
"Try not to use lmgtfy in this subreddit. (His link is a google search of \"de Beers Monopoly\")."
] |
[
"Do consuming meat with cancer have any effects on human body?"
] | [
false
] | Is there any after effects in consuming meat or fish that has a tumor? | [
"There is no evidence at all to suggest it would in humans. Moreover, there's little to no theoretical basis to suspect it would either. As far as we're concerned, it's just the same old bit of meat to be broken down and digested.",
"Cancers ",
" be transmissible, however - even when eaten. Tasmanian devils are... | [
"Late to the show, but Devil Facial Tumor transmits because of MHC ",
"downregulation",
" that prevents the Tasmanian devil’s immune system from recognizing and destroying the foreign cancer cells. In the lab, we can engineer that immune evasion by directly impacting immune system development. We use that to gr... | [
"So is limited genetic diversity the reason that it's a problem in Tasmanian devils?"
] |
[
"Do satellites orbiting the earth have to compensate for the sun's gravity?"
] | [
false
] | null | [
"I'm assuming that you are using the word \"compensate\" to describe controlled maneuvering or station keeping, since satellite orbits are inherently affected by anything in the universe with mass -- some more than others... ",
"Orbits are commonly described and predicted by varying fidelity of propagators, a few... | [
"Yep. It's also worth mentioning that the deviations caused by the Sun's gravity might be small compared to those caused by atmospheric drag, the moon's gravity, the Earth's oblateness, or even by solar radiation pressure. Which factors are most impactful depends on the specific orbit (altitude, orientation, etc) a... | [
"Acceleration due to gravity of earth (or any object very near the earth) due to the sun is 0.0006g. That would be a rounding error compared to the acceleration due to gravity of a satellite due to the earth itself."
] |
[
"Is our solar system in a group of other stars of approximately the same age?"
] | [
false
] | Since our sun and solar system was formed from a massive cloud of swirling dust and gas, are we aware of other stellar 'cousins' (relatively) in our same part of the Milky Way. Have astronomers been able to identify a batch of stars born about when our Sun was. It seems most of the 'Goldilocks' planets are locates qu... | [
"Short answer - we have \"cousins\", but they're not likely to be near us anymore, and not particularly good candidates for Earth-like planets.",
"A molecular cloud might form hundreds of stars all in one spot. As the radiation from the stars dissipates the cloud, you're left with an \"open star cluster\".",
"H... | [
"Thank you for your excellent and very informative reply."
] | [
"To answer the 1st question, if there are other stars around the same age as our sun; yes, there are. All stars in the same star class (If I remember correctly, our sun is a G type star) should have similar ages. There are lots of stars in that same class \"near\" us. (i'm talking under 100 light-years, still far, ... |
[
"If a gorilla lifted weights, would it improve its physique?"
] | [
false
] | Why do humans need to lift weights a lot to look strong, and gorillas can naturally strut around with muscles? | [
"It is almost certain that Gorrillas and other similarly muscled primates have large muscles because of their different hormone profiles. I searched for a citation that specifically talked about Gorilla hormones but came up lacking. However, ",
"here is a study along similar lines",
" that discovers a mutation ... | [
"Natural bodybuilders are bodybuilders who aren't using any performance enhancing drugs. Or at least, they're able to pass the best tests we have for detecting PEDs :)"
] | [
"The comments here that suggest that Gorillas have a lot of muscle because of their physical activity are way off the mark. The assumption underlying these responses is that Gorilla's muscles are essentially the same as ours, but they just use them more and thus they grow to such sizes.",
"Yes - this is absolutel... |
[
"How small of an object can an electron microscope detect?"
] | [
false
] | Would it be able to see specific atoms, molecules. Bonus Question: What is the smallest electron microscope that can be built while maintaining its primary function? Is there a way to develop nano cameras that can help us see what happens at the molecular level? | [
"The reason that electrons are used is that they have a much smaller wavelength than visible light, so can give a higher resolution. You can detect anything on the order of nano-meters or so, (so yes, we can see molecules) but this does vary depending on the method used, ie; scanning, transmission, etc. "
] | [
"There are actually various types of electron microscopes. By around 100,000x magnification a standard Scanning Electron Microscope tends to get a bit blurry, so it can't image down to the level of atoms. But the center image ",
"here",
" is probably a Transmission Electron Microscope image, and those dots are... | [
"Interesting site ",
"http://scaleofuniverse.com/",
"Zoom in enough and it gives you a visual display of how small the optical vs the electron microscopes can see."
] |
[
"Why can you cause a more forceful impact if you \"flick\" your finger as opposed to simply extending it?"
] | [
false
] | Is it something to do with muscle tension? The thought entered my head and it's been bothering me all day. | [
"This is really a mix of biology and physics...Basically, F = ma (force = mass x acceleration). When you are flicking your finger you build up maximum muscle tension before the finger begins to move giving it maximal acceleration also maximizing the force. When you extend your finger the acceleration is less becaus... | [
"A flick has more momentum then a slow extension, if you finger collides with something it will impart some momentum to that something. So if you flick something there is more momentum to impart during a collision than if you have a slow extension. (The physics term for this is impulse)",
"Or are you asking what ... | [
"I was asking more about the kineseological difference, which ",
"/u/KarlOskar12",
" explained. Thanks, though!"
] |
[
"Tar/asphalt being liquid, How come roads don't repair themselves."
] | [
false
] | I assume because it takes to long. So, if left long enough would it fix itself and how long would it take. | [
"The asphalt binders used in modern flexible (asphalt concrete) pavements are very viscous at the normal temperatures that the pavement was designed for. Also, the asphalt binders themselves make up only a small portion of the volume of the pavement, with the vast majority of the material being aggregate.",
"Pav... | [
"Given enough time could it fix it's self, It was that tar drip experiment that got me thinking about it, even if it took 20 years, Would a crack seal?"
] | [
"Well, as you may remember from that experiment, the flow rate is ",
" slow. As well, ~95% of the material is aggregate although I must admit to insufficient materials knowledge to really know how that would affect flow. Perhaps another with expertise can help here.",
"Still, I think it is fair to say that crac... |
[
"Why was the gold rush specifically located in north western United States and not north eastern?"
] | [
false
] | null | [
"The Gold Rush was actually primarily in the southwestern US. The reason is quite simple. The Rocky Mountains have a large number of rich gold deposits. Similar gold deposits are not as common in the eastern US.",
"Also, the term Gold Rush was coined to describe the increased migration of people to both mine t... | [
"It has to do with where gold forms; usually at tectonic boudaries. ",
"/u/Gargatua13013",
" mentioned a few in Canada associated with ",
"greenstone belts",
". There was also a gold rush in ",
"North Carolina that started in 1799",
". Romarco Minerals owns a gold property in South Carolina known as th... | [
"Indeed - and interestingly enough, the very same prospectors who outlined the gold play in California also were involved in most of the other plays as well. The Lode gold deposits around Virginia City, Nevada, were found by prospectors on the way back from California.",
"It's always a bit fun to be on site at a ... |
[
"In the ISS, how do astronomers keep the station clean?"
] | [
false
] | Dust (food, human dead cells...) stay in there. Do they "hoover" the environment? Which technologies do they have to do it? | [
"They have filters that scrub particles from the air, and they also have (what must be an oddly ironic name considering what is on the other side of the walls), a vacuum. ",
"Astronaut #1 : Hey, where did you put the vacuum?\nAstronaut #2 : I left it outside.",
"EDIT: Found YouTube clip .. ",
"https://youtu.b... | [
"First of all, thay are astronauts and cosmonauts. ",
"Cmdr Chris Hadfield and some other crew membwr explianed ir in one of NASA youtube video that they clean themselves periodicly to cause less dead skin, sweat. And hair loss. They eat food through packages or in liquid form. And what ever leftover floats thay... | [
"I just visited the European Astronaut formation centre in Cologne recently and they mentioned cleaning the ISS as a regular, planned activity. Excess dust is hazardous in such environments and the task of cleaning is taken quite seriously.",
"Don't quote me on it but I remember something like a full day a week g... |
[
"If the Universe is an outdoor pool, is the CMB the pool walls or simply the edge of a sphere within the pool corresponding to our 13.8 bn years eye sight? Could there be many such spheres in the pool, none of them seeing the actual pool walls?"
] | [
false
] | The heart of my question is the cosmic microwave background (CMB). I know what it is (thank you Internet), but what does it represent? Is it the end of what we see, or an actual border (but then: a border of what?). If it's just the end of lightspeed vision, could there be a number of universes happily dangling around ... | [
"This is actually a very good question with not a simple answer.",
"Here is a graphic",
" of the history of the Universe. Between the beginning and the region marked \"Afterglow Light Pattern\", the universe was opaque to light. Any photons emitted by matter were almost instantly reabsorbed by other matter, so ... | [
"Thank you very much for taking the time to write this; I enjoyed reading it. I think the main part I missed was that looking far away also means looking back in time. If we have a (radio?) telescope powerful enough to look as far as possible (well, not \"look far\" but \"receive from afar\"), then we see the first... | [
"\"This does not give me information on what else is in the pool, or whether there is a pool at all.\"",
"Exactly! we just can't tell, maybe we will never be able to.",
"There are some studies looking for patterns in the CMB that might indicate a collision with other spheres, but nothing conclusive (or even per... |
[
"How is original antigenic sin a negative for the host?"
] | [
false
] | [deleted] | [
"Provided the original epitope remains a part of the mutated virus (even in a lower percentage of the viral protein expressed) then a secondary response will always be faster than the initial infection response. I mean to say that T memory cells will respond more quickly to a previously encountered Ag than an initi... | [
"Great this made the most sense, thanks! "
] | [
"No, if the original epitope could no longer be recognised then an immune response would have to be raised against whatever epitopes were now present. That is how pathogens that rapidly change their surface proteins avoid the immune system. "
] |
[
"If a light is shined through purple tissue paper, does the light shining through the paper have increased energy because it's purple?"
] | [
false
] | This question came up in my AP Chemistry class, and I couldn't give a satisfactory answer | [
"No, if you shine white light on an object and purple light is transmitted that means several colors have been absorbed by the object. In the case of purple it would likely be the lower energy visible wavelengths (green through red) or maybe just green through orange with some red left over. Overall there is less... | [
"What about blue light? Would that increase the energy level?"
] | [
"Without looking at the actual transmission or absorbance spectrum it is hard to say exactly what the paper does. It could just allow through purple wavelengths (around 450 nm), or purple and blue and red, or red and blue, or anything in between. If it is letting out something that looks purple to us it likely ha... |
[
"Why does a body orbiting another body lose energy, getting ever so slowly closer to each other?"
] | [
false
] | [deleted] | [
"I think you're greatly overcomplicating things by trying to think of everything in terms of particle exchange, which really isn't that useful a way to think about physics unless you're trying to calculate how particles scatter off each other.",
"Consider the electric field of a charged object, both close to and ... | [
"If your assertion is that gravitational radiation has no energy, that's simply incorrect."
] | [
"If your assertion is that gravitational radiation has no energy, that's simply incorrect."
] |
[
"In theory, is the number of elements infinite?"
] | [
false
] | I know that there are 98 naturally occurring elements, but more have been artificially produced. I do realize that most of the synthetic elements are very unstable and decay almost instantaneously, but is there an upper limit on the largest atom physically possible? | [
"Some versions of the nuclear shell model, which describes the various nuances and patterns of stability and nuclear structure do predict 'islands of stability' away from the main stability line. In some instances these are in the super heavy region, though there is inevitably going to be a practical limit. In theo... | [
"Depends by what you mean exactly by \"physically possible\". Does it mean \"has a half life longer than 5 minutes\"? If not, then what?",
"Anyway, guessing at what you actually mean, then no there is not an upper limit except in practice. As the electrons in the various quantised energy shells get further away f... | [
"There is a limitation caused by the diminishing effect of",
" the residual strong force/nuclear force",
" as nuclei gets bigger. Any atom larger than lead is unstable as far as we know.",
"At distances larger than 0.7 fm the force becomes attractive between spin-aligned nucleons, becoming maximal at a center... |
[
"What is the minimum mass required for a celestial object to become spherical in shape?"
] | [
false
] | Moons, planets, and stars are usually spheres and many asteroids tend to be big rocks. How massive does an object have to be before nature makes it a sphere? And why do large masses become spherical? | [
"AFAIK the smallest ",
" moon in the solar system is Mimas (about 3.8 x 10",
" kg), although it slightly tidally distorted ovoid by Saturn's gravity.",
"Planets are round because their gravitational field acts as though it originates from the center of the body and pulls everything toward it. With its large b... | [
"Yes presumably, but putting number on it is difficult (read: I don't know how to do it). The amount needed will depend upon material properties (icy bodies are less strong than rocky), planetary temperatures (radioactive heating promotes flow), etc."
] | [
"I guess that ",
"water droplets",
" count as objects too. In this case I guess it's mostly surface tension holding the droplet together, not gravity."
] |
[
"Before there were beds, where did bedbugs live?"
] | [
false
] | Did they come from outside? Also, why have they made a "comeback" after being pretty rare for so long? I got curious after living in LA and encountering them in about every cheap hotel and friends house I stayed at... | [
"Bedbugs have ",
" to feed on human blood, while we sleep. ",
"Bedbugs were originally bat bugs. Their ancestors lived in caves, on bats (where most of their kin still live), and when our ancestors moved into caves, they jumped down onto us. A few found us where we slept. Those that did prospered on our blood ... | [
"There used to be a class of pesticides in common use in the US that effectively controlled bed bugs (and lice and scabies) for the majority of the 20th century. Those chemicals were banned due to human and environmental side effects, and so now those bugs have made a major comeback. ",
"You've got some facts mi... | [
"On one hand, that's super creepy...on the other it's also super interesting.",
"Slightly worsened by the fact that they are ",
" the worst thing to feed on us or live on us...but hey, I'm all for showing some bugs the world. "
] |
[
"Why didn't Tevatron see conclusive evidence of the Higgs?"
] | [
false
] | I'm writing a report on the Higgs evidence. I have seen data that suggests Tevatron ruled out a Higgs with mass roughly 157 to 180 GeV. If this is true, why couldn't Tevatron see significant evidence of a Higgs with mass ~126 GeV? Surely this lower mass would be easier to create and therefore easier to rule out? A sour... | [
"The answer to your question is contained in ",
"this",
" plot. Between 157 and 180 GeV the higgs is massive enough to begin decaying to WW and ZZ, which are a much easier to identify signature than when the higgs decays to bb."
] | [
"To use a familiar (if technically incorrect) term, the problem was its signal-to-noise ratio. The Tevatron has a much lower peak luminosity compared to the LHC; ",
"this abstract",
" states that \"an excess of [background] events\" prevented them from establishing the 126 GeV Higgs to a 5-sigma certainty.",
... | [
"As far as I know, the lower limit comes not from the Tevatron but from the e+e- collisions at LEP2. ",
"Also, you are correct that the Higgs production cross section (essentially the probability of producing Higgs bosons) depends on the center of mass energy of the collision (see for example table 1 in this pape... |
[
"Apart from Pluto being small what made them decide to change the status of the planet?"
] | [
false
] | null | [
"The same thing that happened last time planets got demoted.",
"Back in the early 19th century they discovered 4 of some of the largest asteroids, and they called them \"planets\". This situation persisted for nearly 4 decades, but then they started discovering more asteroids. First a few, then after a couple yea... | [
"This situation persisted for nearly 4 decades",
"It was a little over 5 decades. Ceres was discovered 1801, but the term \"minor planet\" didn't come into fashion until 1854.",
"Charon and Triton were members of a large family of TNOs.",
"To be clear, Triton probably was a member once, but has since been cap... | [
"Answer compiled from Wikipedia articles on ",
"Pluto",
", ",
"IAU definition of ",
" and the ",
"Scattered Disc",
":",
"After 1992, Pluto's status as a planet was questioned following the discovery of several objects of similar size in the Kuiper belt. In 2005, Eris, a dwarf planet in the scattered d... |
[
"Are the effects of gravity instantaneous across the universe?"
] | [
false
] | Please correct me on any of the following if I am wrong: Let's say I convert some energy in to mass. Before it was mass, it did not have any mass, so it did not have gravity, nor was it affected by gravity. After it became mass, it does have gravity. Are the effects of the "new" gravity that this mass created prevalent... | [
"No, changes in gravitational fields propagate outward at the speed of light. This is most directly verified by ",
"measuring changes in Earth's gravitational field due to the sun versus the sun's position in the sky",
". It can also be inferred astronomically, for example due to decays in pulsar orbits from gr... | [
"That's what light is: a propagation of electric and magnetic fields."
] | [
"Because that's how fast information can propagate in this universe."
] |
[
"How would a space elevator tether actually be put in place?"
] | [
false
] | Most people know the basic idea of a . I've never actually read anything on how they'd get the cable in place though. "Dropping" it from the space end seems like it would be overly expensive, you'd have to launch all of the cable up there first. Also once it starts skimming the atmosphere that would cause all sorts of ... | [
"I think this is probably one of the (many) problems that currently makes space elevators impractical. My thought is to start by launching a rocket into geosync orbit carrying a spool of small cable and then using a projectile of some sort to launch the end of the cable back to Earth. Once it's back on Earth, you c... | [
"Several issues exist with the concept, one being that the cable has to be incredibly strong and there has to be a lot of it. I remember seeing a documentary which calculated the strength requirements which could be met by some advanced materials (not in the quantities required yet currently). ",
"Cheap launch co... | [
"Strong enough and light enough. That would have to be one hell of a rocket to haul it in to space, not to mention the aerodynamics of the tether. ",
"I know we don't have the proper material yet. People are saying carbon nanotubes are close but not quite good enough. I was just curious about the construction ... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.