title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"[Biology] Pouyannian mimicry: How do plants evolve to mimic members of the animal kingdom?"
] | [
false
] | I did what little research I could without a background in biology, outside an intro course in my undergrad. I would really appreciate if a botanist could break this science down. | [
"The key thing here is that evolution is not directed, it's not like the plant is thinking, if I look more like that insect, it will be attracted to me, and then spread my pollen for me.",
"The mutations to the plant are random, some mutations result in a flower that more closely resembles an insect (shape, color... | [
"Same concept. Nothing directs a walking stick to look like the tree its crawling on. But somewhere back ages ago the insects that had these chance mutations that made them look like a part of that tree were less likely to be detected by predators (or more likely to sneak up on prey) and, therefore, more likely to ... | [
"So do animals just so happen to resemble leaves or twigs as well? This is all just natural selection and not an emerging field of study? I can accept this answer, but it's not that satisfying. "
] |
[
"What would happen if you actually did eat those \"do not eat\" silica gel packets?"
] | [
false
] | null | [
"Most likely: nothing. The silica gel itself is inert and nontoxic. It is placed in the bag of food to help reduce moisture/humidity which may spoil said food. It is marked with 'DO NOT EAT' because it is a non-food item mixed in with food items, and may also present a choking hazard. ",
"Given the fact that the ... | [
"”Most likely: nothing. The silica gel itself is inert and nontoxic.”",
"”If anyone does accidentally ingest a packet, a call should be placed to poison control”",
"I think you captured the reason OP is asking this quite accurately, how can it be harmless, yet require medical attention?"
] | [
"Well, anytime anyone ingests (accidentally or intentionally) something they shouldn't, poison control should be called. That's just the protocol, at least in my area. Sometimes it's for documentation/epidemiological data reasons, other times its to confirm appropriate management or correct prescribed therapy. Ofte... |
[
"Do galaxies have an electric current?"
] | [
false
] | Stars are electric objects. The have magnetic poles. Do galaxies have magnetic poles and a current of interstellar electricity charging the sun by flowing down the spiral arms of the milky way? | [
"Stars are electric objects. ",
"I guess that's not wrong but not how I would put it. It has currents which generate the magnetic fields but it's not strongly charged.",
"Anyway, galaxies do have magnetic fields (see a recent ",
"image",
" by Planck of our own galaxy) but these are extremely weak in compari... | [
"Right I'm not talking about a cosmic thunder bolt. But a current moving in a uniform direction among the galactic arms"
] | [
"Right I'm not talking about a cosmic thunder bolt. But a current moving in a uniform direction among the galactic arms"
] |
[
"Does chlorine that settles in to ground when irrigating lawns or draining swimming pools degrade into something else, or remain unchanged?"
] | [
false
] | I work in water utilities. 99% of residents in my city irrigate their lawns with city water, and we like chlorine to be 1.8-2.1 in this city. All run off from irrigation and when people drain pools and the like seeps into their lawn, and all water eventually makes it to the lake system. It's common knowledge here that chlorinated water once "filtered" through ones lawn removes nearly all the of the chlorine from the water by the time it makes its way back into our lake system. So my questions is, does all that chlorine sit in the ground unchanged? Or does it eventually degrade into something else? | [
"Chlorine gas is very reactive and can oxidize most organic matter it comes in contact with. It does not stay chlorine for very long in an high-organic load environment such as soil. The chlorine in treated water will gain two electrons from something in the environment and become two chloride ions (Cl-)."
] | [
"Lawns are foolish, as far as that goes.",
"Usually, yea. The firebreak concept they originated from is still relevant in the rural areas around me, though. Ur seen houses saved from wildfires by a decent lawn. "
] | [
"Using potable water in this way is foolish but universal. Lawns are foolish, as far as that goes.",
"Chlorine atoms are very reactive and exist as hypochlorous ions in water. They react with organic soil molecules, forming hydrocarbons and similar chemicals. Some will evaporate as Cl2 gas into atmosphere. "
] |
[
"Of the infectious diseases that were the leading causes of death in the 1850s, which ones are now easily curable and which are still dangerous?"
] | [
false
] | I found this display at a science museum in San Diego which showed the leading causes of death in 1850, all infectious diseases. If I (a 20-something woman with normal medical history) were diagnosed with any of these tomorrow morning, will I survive and/or be cured? Which of theses diseases are still a real threat? | [
"Some of these are single infections, while others are diseases with multiple infectious causes. I'll address them one by one. ",
"TB: Quite treatable with a multi-drug regimen, although antibiotic resistance is increased in parts of the world. Still a huge killer worldwide, but in the developed world, you should... | [
"depends on where you live. If you are in a developed country those are mostly treatable. In an developing country not so much. TB is now drug resistant and may be the biggest threat. Malaria also can be drug resistant is remains a major threat to people world wide. whooping cough, diptheria, pneumonia, are vaccine... | [
"Malaria.",
"\nIn reality it is the most dangerous disease around. According to the WHO, in 2020 there were an estimated 241 Million recorded cases of malaria and this resulted in some 627,000 confirmed deaths. Yes, it is treatable and yes you can take anti-malarial medication before travel, but these are only 93... |
[
"Is it better to drink something hot or something cold when you have a sore throat?"
] | [
false
] | I've been drinking hot tea all my life and found out all my friends eat ice cream. | [
"I believe that warm drinks have been shown to ameliorate common cold symptoms. The ",
"website for Cardiff University's Common Cold Centre",
" looks to have some interesting information along these lines.",
"EDIT: for ease (please see the page linked-to above for references though):",
"Any form of hot drin... | [
"Interesting. This confirms my anecdotal evidence.",
"When I get a cold I like to go to the local Vietnamese place and get a big bowl of spicy soup with some hot tea with lemon and honey. Always makes me feel better."
] | [
"Yeah i've heard that hot drinks, spicy food, lemon and honey are all (independently) good for colds, so you've pretty much hit the motherload there.",
"Incidentally, i believe, and it never ceases to amaze me, that honey was used as a basic antiseptic (edit: antibiotic?) by the Vietnamese when performing surgeri... |
[
"Have extremophiles always been extremophiles?"
] | [
false
] | That is, are the ancestor of those bacteria and other weird lifeforms that live in the harshest environments on earth extremophiles as well or did all extremophiles evolve from organism that lived in more friendly environments? How much do we even know about extremophile evolution? | [
"We know a little about extremophile evolution by tracking the 16S ribosomal RNA in different species (or similar techniques). This allows us to map the phylogeny of different species, and so far seems to point at the fact that the oldest living organisms we know of were some kind of thermophile (heat loving).",
... | [
"There are many schools of thought. Some people think that the chemical environment of the warm \"smokers\" (i.e. not necessarily the black smokers people normally connect with undersea vents) was itself how life arose, with a natural proton gradient created by the reaction of seawater and rock allowing the first m... | [
"Isn't there a school of thought that says life first organized in the high energy environment of hot water \"smokers\" and only after some types developed mutations that allowed them to get energy from sources other than hydrogen sulfide reactions did life populate other environmental niches around the globe? ",
... |
[
"How long would it take after a vaccine for COVID-19 is approved for use would it take to make 250 Million doses and give it to Americans?"
] | [
false
] | Edit: For the constant hate comments that appear about me make this about America. It wasn't out of selfishness. It just happens to be where I live and it doesn't take much of a scientist to understand its not going to go smoothly here with all the anti-vax nuts and misinformation. Edit 2: I said 250 million to factor out people that already have had the virus and the anti-vax people who are going to refuse and die. It was still a pretty rough guess but I am well aware there are 350 million Americans. | [
"Usually the regulatory hurdles would be large. If you do the discovery, optimization, process development, risk assessments etc. and then start your clinical trials with what you've got, you've already chewed up a lot of time. If you're confident you could start manufacturing (and in my opinion this would be fairl... | [
"The Bill and Melinda Gates foundation is ",
"funding initial construction of ",
" 7 vaccines ",
".",
"Edit: wording; many factories are built for each vaccine"
] | [
"Here's a good peer-reviewed perspective piece from Amanat et al. in Immunity published April 6th.",
"30120-5) They outline many challenges with developing a vaccine for SARS-CoV-2, including but not limited to:",
"Bao et al., 2020",
"current Good Manufacturing Practices (cGMP)",
" ",
" ",
"I highly enc... |
[
"Is it possible (ignoring heat), to make a light bright enough to shine through solid things like sheet metal or wood?"
] | [
false
] | null | [
"It gets exponentially harder with thickness. For example, suppose you have a sheet of paper just thick enough to block half the light. Two of them will block 3/4ths of the light. Three would block 7/8ths, etc. How many sheets thick is a block of wood? A block of wood would be like a ream of paper, and block about ... | [
"If you could create a light source strong enough sure, the only problem is that with the technology we have right now, it would create enough heat to cause spontaneous combustion. ",
"Theoretically yes, a strong enough pinpoint light source would be able to shine through any material, but the amount of energy in... | [
"I mean theoretical possible."
] |
[
"What volume of outer space would you need to inhale to take a single breath?"
] | [
false
] | Of course, outer space is very much devoid of oxygen, but if you were to take an average breath, what volume of outer space would you need to suck up each time? | [
"I will read your question as \"Given the ratio of the gas densities in interstellar space and on earth, what volume of space contains the same number of molecules as your lung?\" in order to give an order of magnitude estimate.",
"Assume your lung volume to be about 2 liters, give or take.\nOn earth under standa... | [
"yes, as a rule of thumb 75% H 24% He and the rest heavier elements. (Except when you run into an asteroid, perhaps even with an iron core. That would not be a pleasant encounter for your ramjet)"
] | [
"Guessing it would be mostly hydrogen that floating around. There have been theoretical designs for spaceships that use electromagnetic scoops to collect ions for a drive. This frees them from having to carry mass to be expelled for thrust. I do recall Robert W. Bussard's original estimates (1960) for the availabil... |
[
"How can the Casimir effect come from harmonic oscillator ground state energy if the latter is arbitrary?"
] | [
false
] | In many explanations of the Casimir effect (e.g. or Casimir's original paper ) it is argued with the ground state ("vacuum") energy of harmonic oscillators. In fact the quantization of the classical harmonic oscillator has an ambiguity which leads to an arbitrary ground state energy (see e.g. chapters 6.3 and 6.4 or (if you're able to read german) chapters 4.4 and 4.5). For relativistic theories it is even necessary to have E_0 = 0. | [
"That derivation of the Casimir effect is simplified with the assumption that the fine structure constant is infinite, which allows it to be derived much more easily. A full derivation considers the relativistic van der Waals attraction between two real plates, which is more complicated and less handwavy: ",
"htt... | [
"I think it is actually pre-dated by a van der Waals argument ( just reading Casimir's first paragraph in the link you posted). I think it is an example of how a handwavy explanation is presented so often that people mistake it for the real thing, sort of like how Hawking radiation comes from particle-antiparticle ... | [
"Baez writes about it here:\n",
"http://www.obscure.org/physics-faq/Relativity/BlackHoles/hawking.html",
"\"...this argument also does not correspond in any clear way to the actual computation. Or at least I've never seen how the standard computation can be transmuted into one involving virtual particles sneak... |
[
"A few questions regarding light and the effect it has on how we view things"
] | [
false
] | Assuming faster-than-light travel was possible: Person A is travelling from Earth at 0.9c, would they see any events happening on Earth occur very slowly? Person B is travelling from Earth at c, would events on Earth appear to have frozen? Person C is travelling from Earth at 2c, would the events on Earth appear to be in reverse, and in real-time motion? Person D is travelling Earth at c, would events on Earth appear to be happening twice as fast? | [
"Only your first questions is answerable- and you are correct, a person traveling towards the Earth would see events on Earth taking place slowly (according to what you mean by very slowly- the gamma factor would 0.9c is 2.2, so things would appear to be moving at about half speed). ",
"The problem with your othe... | [
"No, general relativity does not allow for paths which travel faster than c. "
] | [
"i was told that faster than light travel is possible, but crossing the threshold towards lower than the speed of light or vice versa is impossible. Is this true?"
] |
[
"Why don't contacts for people with astigmatism come in small steps along the axes?"
] | [
false
] | Looking into contacts and I have relatively bad astigmatism. The optometrist said that contacts come in steps of about 5 degrees, 10 degrees for the less severe. Why is that the case? I can tell a very clear difference of 1 degree in my spectacle prescription, will I be able to get good contacts? | [
"The fundamental problem is the cost of maintaining inventory.",
"A prescription for a person without astigmatism just has a quantity of correction in diopters: +1.5 or -4.5 or whatever. So if a contact lens manufacturer does these in .5 diopter increments, and covers from -10 to +10, they'd have to stock 21 size... | [
"Because these are not made custom for you. They're stocked in a warehouse, and doing 1 degree increments would mean stocking fifty thousand different prescriptions instead of five thousand prescriptions. That's the fast answer I buried in too much text above. :)"
] | [
"My question is more focused on why they don't do smaller increments for the axis? I'm not concerned whether or not they have to order my prescription in, more why they can't do it in 1 degree increments instead of 5-10? Maybe I misunderstood my optometrist?"
] |
[
"Could mining asteroids for water have a negative effect on the ecosystem/environment"
] | [
false
] | With the idea of mining asteroids for resources becoming a reality would introducing more water into the environment have a negative impact? Since the water that's been on the planet has pretty much been the same throughout history can it even be predicted what the effects would be? | [
"Would you be surprised to learn that the ",
"mass of the asteroid belt",
" is about the same as the ",
"mass of the oceans on Earth",
"? The former is only 25% more mass.",
"Now how much of the asteroid belt is actually water? The majority of the asteroid belt is ",
"carbonaceous chondrite in compositi... | [
"Is it really becoming a reality?"
] | [
"apparently there are a few companies working towards it. one is heavily financed by the creators of google and james cameron. i read an article earlier today about how a passing asteroid on friday has 400 Billion $ worth of resources that were mostly water on it. "
] |
[
"Why do I remember trying to fall asleep, but not actually the falling asleep itself?"
] | [
false
] | Pretty much title. | [
"I had [what I assume was] a lucid dream once as I was falling asleep. It felt like I was being sucked into a black hole and sounded like bullet trains whizzing passed my ears. I joked to my roommate that this is why people don't remember falling asleep, it's traumatizing. He's in medical school, so I expected his ... | [
"Because it's a different state of consciousness - your brain activity switches to a resting state and you aren't able to form memories or experience things in a way that's meaningful to you. The electrical activity of the brain actually changes when you switch from waking to sleep states (doesn't turn off, but cha... | [
"Very interesting. Thank you."
] |
[
"Is a rubber band really a single molecule?"
] | [
false
] | I read it and just would like a clarification and perhaps a little more explanation. Thanks! | [
"It's a bit of a grey area. You start with individual polymers, which are all their own molecules, then you bind them together in ways that are not entirely dissimilar from the way different atoms in a single molecule are bound. So you sort of end up with a molecule-of-molecules, in a sense.",
"Chemistry is far m... | [
"I'll attempt to clarify because it could be slightly misleading to simply call it a single molecule.",
"Rubber begins as a mass of oriented polymer chains which are free to slide past each other. These don't have particularly good material properties, it's like trying to pull on a clump of spaghetti. It's like a... | [
"You never drop that on their asses?"
] |
[
"What makes an object sharp? How does it cut or pierce through other objects?"
] | [
false
] | I never understood the concept, so I’m not sure if this is a stupid question or not. Update: Right now I’m busy with lectures, but I’ll read the comments afterward. Update: wow, didn’t expect this many people to comment. Thank you everyone for answering my question! | [
"As ",
"u/fael_7",
" said, a sharp edge basically concentrated the force applied. If you weigh 60kg and walk on your toes in sand, you will leave deeper footprints than if you walk on your entire foot, right?",
"Same idea, basically. If you apply an equal force using a sharp point it edge compared to a blunt ... | [
"This gif might help understand what is happening.",
" In the case of that image it is a blade slicing through steel when viewed through an electron microscope.",
"It is actually quite interesting what is happening here. As you can see the edge of the blade at this scale is actually surprisingly rounded. There ... | [
"If this localized pressure can break the material (either on a macroscopic scale by separating individual pieces or segments, or on a molecular/atomic scale by breaking bonds)",
"This is where I get confused. Take the specific example of using a kitchen knife to cut an onion. I am assuming that it is 'cuttin... |
[
"Could a planet orbit the sun on a vertical plane as opposed to the horizontal plane of the other planets?"
] | [
false
] | I am not sure of terminology, but assuming that all the planets are on the same horizontal plane could another planet orbit on a vertical plane? | [
"Bet of a mess here so I'll make a bit of a tl;dr top-level response:",
"Planets form in a flat plane because they all form from a disc of gas.",
"But if you somehow got a planet in vertical orbit ",
" the gas disc had dissipated, it should continue quite happily, and there are indeed small objects in the sol... | [
"No, electron orbits are not supposed to resemble those of planets. Someone else can likely answer this better, but electrons do not act like planets partly because they have both particle and wave-like properties. ",
"An electron's orbit can be characterized better with the atomic orbital model, which predicts... | [
"How come electrons circle the nucleus at vertical angles then? Aren't their orbit supposed to ressemble that of planets?"
] |
[
"Keep hearing that we are running out of lithium, so how close are we to combining protons and electrons to form elements from the periodic table?"
] | [
false
] | null | [
"I work for one the largest lithium producers and refiners. We certainly don’t think lithium is running out. We get a lot of ours by drying brine combined with earth in old volcanic zones. The left over salts have a decent concentration of lithium. This helps avoid so much mining too, but there are a couple lithium... | [
"Lithium is the 25th most abundant element on earth. It's contained in the earths crust at concentrations of about 25mg per kg. i.e. There's ",
" of lithium around, it's just really spread out. We are not ever going to \"run out\" of lithium. What we're having trouble with is sources of highly concentrated, cheap... | [
"We can and do use nuclear reactions to produce specific isotopes of specific elements, however it's very expensive, and generally not commercially viable except to produce radioactive nuclides which can't be found in nature (for medical purposes, experiments, etc.)."
] |
[
"How does diamagnetism, paramagnetism, farramagnetism fall into the spectrum? or do they fall into the spectrum?"
] | [
false
] | null | [
"What's \"the spectrum\"?"
] | [
"The electromagnetic spectrum."
] | [
"I see. They don't really fall into the spectrum - the electromagnetic field created by a magnetic material is defined in terms of its static magnetic moment. So there's no radiation at work here. ",
"Alternatively, there's a sense in which you can interpret static electromagnetic fields as a zero frequency (or i... |
[
"Hey AskScience, give me your best shot for an intergalactic positioning system."
] | [
false
] | The universe is a big place. Say, I want to meet you at a certain moon of a certain planet of a certain star of a certain galaxy at 15.00h tomorrow (local time) and that moon moves thausands of kilometers until then in respect to a eg. a sol centered coordinate system (like this one: ). I would either have to give you coordinates where I will be at that time relative to eg. our sun / the earth, or you would have to have some navigation computer that can be given some coordinates (of even unknown objects) and translates them into "real" coordinates for any certain time. What information has to be contained in such coordinates that can predict where that thing will float around in space for any given time? How do (real world) star charts encode star information? x,y,z relative to us at t-zero, plus some kind of interpolation function where that thing will be later? Wouldn't that be really unwieldy for a moon of a planet of a star in some distant galaxy? | [
"Actually, its not that hard to interpolate where planets/the sun are going to be at any given time, since gravity is a pretty easily predicted thing. In fact, we have GPS satellites buzzing in all different orbits at any given time, and yet we do a pretty good job of keeping track of where all of them are.",
"O... | [
"an intergalactic inertial reference frame...",
"The CMB would be perfect, no?"
] | [
"Radial velocity is from redshift, angular is from position snapshots. The mass is less precise, you get it by comparing with better known objects of similar nature, which boils down to using the spectrum."
] |
[
"Why do we have such effective antibiotics but no true equivalent for viruses?"
] | [
false
] | Are viruses that much harder to treat or is it just that there has not yet been the "penicillin - moment" equivalent to antivirals? Edit: Wow! Post is an hour old and already has several awesome answers. Thanks everyone! I feel better having learned something today. I'll definitely be visiting more often; lots of interesting posts to read! | [
"It's mostly metabolic. Bacteria are living cells with DNA and metabolic enzymes. They can live and divide on their own like other one cell organisms. This gives antibiotics a method of attacking the bacteria- interfere with, or \"poison\", the metabolism and you can kill them.",
"Viruses are packets of DNA that ... | [
"Good Question. Killing viruses and bacteria are very different propositions. Viruses are small proteins with a little bit of genetic material (and sometimes enzymes), whereas bacteria are prokaryotic cells. Killing viruses is harder than bacteria because for most viruses, you need to break their capsid (strong pro... | [
"It's the equivalent of saying \"this\". All posts should contribute meaningfully to the thread. If you find a post enlightening or educational, I would direct you to the lightbulb to the left of each post."
] |
[
"How do you calculate the distance of stars etc from Earth?"
] | [
false
] | null | [
"Supernova in general are not the same intensity. A particular type of supernova - Type IA, which are hypothesized only to occur in binary star systems where one star is a white dwarf, produce a consistent light curve which can be used along side of a measured light curve to figure out the distance to the galaxy in... | [
"Astronomers are able to calculate the distance from earth to a celestial object through a method called Parallax. Astronomers record the position of an object in the sky on two different nights (it's easiest when the time intervals are half a year apart). Then, since we know the diameter of the orbit the earth tak... | [
"I've heard of parallax, but I find it interesting that supernovaes are generally the same intensity."
] |
[
"Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology"
] | [
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! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"Hare's checklist includes a lot of things that are very common and not so worrisome on their own--this includes stuff like impulsivity, irritability, promiscuity, irresponsibility, and proneness to boredom. Few of us have never bought something we didn't need on a whim, or said something in annoyance or anger. Qui... | [
"There are numerous pathogens that cause upper respiratory infections (URIs). In an otherwise healthy individual, the pathogen is most commonly a virus, and sometimes a bacterium.",
"Some pathogens (but not all) produce characteristic smells. For example, a tell-tale sign of Streptococcus infection (strep throat)... | [
"Hi! I was wondering some things about psychopathy. Robert Hare mentioned in an article that there is a test for it and that everyone exhibits some bit of it. I was hoping you guys can shed light as to what a mild version of psychopathy looks like. Is racism or general prejudice a part of that? "
] |
[
"How far is the horizon from a human point of view?"
] | [
false
] | null | [
"When you are on a sphere of radius R and look out to the horizon from a height h, the distance to the horizon is sqrt{2Rh}.",
"For a typical person, this is about 3 miles or 5 km, if you're just standing up on the Earth.",
"This site",
" has an online calculator that tells you how far away the horizon is as ... | [
"Well, on a good day, the sun can be seen with the naked eye, and that's over 92 million miles away."
] | [
"Well, on a good day, the sun can be seen with the naked eye, and that's over 92 million miles away."
] |
[
"Fingerprints: What is the evolutionary reason and do any other mammals have then besides primates?"
] | [
false
] | Seriously, what is the point of the pattern on our hands and figerprints. Why did this happen? | [
"Fingerprint grip theory rejected",
"BBC article that doesn't fully reject the notion of improving grip for specific surfaces, but seems to reject the \"improved grip\" notion in general.",
"\"Ennos believes that fingerprints may have evolved to grip onto rough surfaces, like tree bark; the ridges may allow our... | [
"Grip. Without them, we wouldn't be able to grip objects we're holding nearly as well. They're random patterns, which makes them great for identification, but that isn't their primary function."
] | [
"I didn't say we couldn't grip, I said we couldn't grip as well as we can with them. It's an improvement."
] |
[
"Physiology Blood type question, how can universal recipient receive any type of blood and universal donor can donate to any blood type without the transfused blood cells being attacked and destroyed?"
] | [
false
] | Explain why a) the UNIVERSAL DONOR can donate red blood cells to any of the blood types and b) the UNIVERSAL RECIPIENT can receive red blood cells from any of the blood types without the transfused blood cells being attacked and destroyed. | [
"Blood type describes the type of antigens (structures used in immune system response) found on a person’s red blood cells. The letters (A, B, & O) refer to sugar-based antigens. There are A antigens and B antigens. We use type O to refer to blood cells with neither A or B antigens. The plus/minus (Rh D) refers to ... | [
"Note that this all refers to just the packed red blood cells without the blood plasma. If you just put whole blood from a type O person into a type AB person, the red blood cells in the transfused blood won't be attacked but the A and B antibodies in the plasma will attack the native red blood cells.",
"So, to m... | [
"You've gotten a few detailed answers here, but the short is whole blood is no longer transfused regularly. Instead we transfuse blood components (red cells, plasma, platelets, etc). If you transfuse whole blood there will be some degree of reaction unless donor and recipient have the same blood type (and even then... |
[
"Does running on an inclined treadmill involve significantly more work than running on a flat treadmill?"
] | [
false
] | Conventional wisdom says yes. Even calorie burn estimators say you use a lot more energy on an inclined treadmill. But there's no net displacement in opposition to gravity. I guess you could theoretically be slightly elevating your body with every step and then be slightly lowered by the machine on the back-step, but it seems like the mechanics of running are such that you're mostly only beginning to support your body weight against falling when your foot is out in front of you with the majority of the propulsion occurring only after your front foot is nearly under you. Plus it just seems like your body would kind of naturally move differently when not required to actually combat gravity by climbing from a kinesthetics standpoint. I guess this would ultimately depend on an individual's gait, which can be pretty idiosyncratic. Is running/walking consistent enough of a movement to draw conclusions based on physics? If not has there been any statistical study of this question? (Couldn't figure out how to add a second flair.) Are all of those treadmills that say you're burning like 50% more calories on the incline mode full of shit and just using numbers based on actual uphill running? Or is there a legitimate scientific basis for those kinds of claims? | [
"gravity isn't the only force you have to work against, there's also the force stopping gravity from plunging you straight through the treadmill, into the ground, and down towards the core of the earth. This is called the \"normal force\" - always pushes in a direction \"normal to\" (ie, at right angles to) the sur... | [
"I'm not sure what you are confused about, no offense. It is demonstrably true that running up hill requires more work than running on a flat surface. Why would an inclined treadmill be any different?",
"Or is the key to your question in the use of the word \"significantly\"? As in, can a treadmill incline enough... | [
"Yeah, but balls are fixed (more or less) rigid structures. It doesn't really take any energy to keep a ball from collapsing on a flat surface, but it also can't alter its shape and center of gravity to keep from rolling on a slope. Humans do have to use energy to maintain muscle flexion to stand upright, but they ... |
[
"straw in a glass of water"
] | [
false
] | so me and my friends couldn't agree on why water stays in a straw when it's in a cup of water and if you cover the top and lift the straw, the water stays in the straw but falls out when you let go of the finger at the top of the straw. so I just thought I'd ask reddit to see what the correct explanation is? since I've seen several different explanations on the internet and from person to person. edit: i guess i'm having trouble figuring out the forces at work here, the water stays in the straw means there's an upward force counter acting gravity right? and that force is gone once i let go of my finger? what is this upward force? i kinda get surface tension but how come gravity is not able to overcome surface tension if the finger seals the straw but can when i let go of the finger? | [
"No, when it is that big the surface tension is not strong enough to hold the water together."
] | [
"Pressure and surface tension.",
"The water can't fall out all together as a whole because air has to take it's place, and air can't get into the straw while the top is held.",
"The water won't fall apart and fall out drop by drop because there is surface tension holding it together."
] | [
"Would it work with a giant straw? Say 50ft long with a 5ft (circumference) opening?"
] |
[
"Why is raw chicken considered more dangerous than other raw meats?"
] | [
false
] | Or maybe it's just poultry in general but why is it generally forbidden to eat chicken that is in any way raw? Raw fish is eaten all the time and its acceptable to eat meat that is somewhat raw in the middle. Is there just a stigma to chicken meat that has made it seem more dangerous or are chickens (and their eggs) simply more receptable to harmful bacteria? | [
"This is true for the most part; Chicken carcasses are disemboweled by a high speed automated machine which often rips open the intestines of the poultry, releasing fecal matter into the birds' body cavities.",
"Furthermore, in post-processing the chickens are often mass-chilled in a huge bath of chlorinated wate... | [
"This is true for the most part; Chicken carcasses are disemboweled by a high speed automated machine which often rips open the intestines of the poultry, releasing fecal matter into the birds' body cavities.",
"Furthermore, in post-processing the chickens are often mass-chilled in a huge bath of chlorinated wate... | [
"that's...disgusting"
] |
[
"If the mass and size of the universe are plugged into the schwartzchild radius, it’s a black hole. Why is this brushed off as a coincidence?"
] | [
false
] | null | [
"It's not a coincidence, it actually means that our universe is flat! If you take the ",
"Friedmann equations",
" and compare the Schwarzchild radius for the mass contained within the Hubble length to the Hubble length, you will find that they are equal for a flat universe. This doesn't mean that the universe i... | [
"It doesn't. The Schwartzchild radius based on R=2GM/c",
" is 2x10",
" meters while the radius of the observable universe is 4.4x10",
" meters.",
"Also the Schwartzchild radius has a restriction of non-rotation which I don't know/can't speak to if that is present.",
"Edit: The numbers I found to do the ma... | [
"That's because the definition of the mass contained within a hubble sphere is based on the critical density i.e. the density required to halt expansion.",
"Any higher density should result in stuff being pulled back together. ",
"Some searching shows that our universe is approximately the critical density mean... |
[
"How can the universe be 93 billion light years across and only 13.7 billion years old?"
] | [
false
] | null | [
"Please see the FAQ"
] | [
"It's the first one under the Astronomy section."
] | [
"It's the first one under the Astronomy section."
] |
[
"Has there ever been a moment in time where the human population on Earth was lower than previously? Is the birthrate enough to outnumber the deaths of wars and pandemics?"
] | [
false
] | Further, does this fluctuation have any adverse effects? Given the finite size of this planet, would there be an ideal population size? I'm sure there's plenty of room with how we are currently building upward and the eventuality of humans developing outward into the ocean. Before those next advancements, I'm curious. These questions stem from recently reading discussions involving global fertility rates, global temperature increases, the continued spread of disease, and an alleged increase in deaths resulting from a natural disaster. Thanks in advance! Note: Repeat submission due to not flairing the post, as per the rules. Anthropology seems to fit, and I'm curious what folks who work in that field have to say in response to these questions. | [
"Both World Wars led to significant decreases in total population. ",
"Do you have a source for this? AFAICT, there was no period during the 20th century when total world population was in decline. Yes, the growth rate was significantly reduced during the world wars and the Spanish Flu pandemic, but did not dro... | [
"It's believed that, about 70,000 years ago, the ",
"Toba volcanic eruption",
" caused a dramatic climate disruption that wiped out much of the human population, reducing the total number to 3000 to 10,000, producing a genetic bottleneck."
] | [
"Both World Wars led to significant decreases in total population.",
"No, they led to decreases in worldwide growth rate but not a decrease in population."
] |
[
"In a really long line, if the first person moves forward, what's the average time until the last person moves. (That is, what's the speed of wave propagation in queues)?"
] | [
false
] | I was waiting in a long line (queue) at a theme park yesterday and started wondering: how long does it take from the time that the first person moves until the opening gets to me and I can step forward? That is, what's the speed of wave propagation in queues? I'm picturing waves of people moving forward though the line, and it's kind of a neat image. I've tried Google searching a bunch of related phrases but haven't turned anything up. Surely someone has measured this. Although I can't really think of any practical implications. Any ideas? | [
"Slower if the people have luggage. But it doesn't always propagate as neat wave either. I don't think you can assign a meaningful single number to it."
] | [
"If it were a line of heavy railway carriages connected by springs, then it would be a perfect wave.",
"Humans of course have personalities and make choices, but you can make an average model of how they will react.",
"Perhaps ",
"https://en.wikipedia.org/wiki/Crowd_simulation#Crowd_dynamics",
"would give y... | [
"There are too many variables. Cell phones, number and types of luggage or number of items each add to the complexity of moving the queue as well as transaction times.",
"Realistically, we've all been stuck in lines that barely move while adjacent lines sped along. The trend in efficiency seems to be a single l... |
[
"How does general air traffic deal with orbital space launches?"
] | [
false
] | Is this a predetermined window around launch areas, or is it easy enough for general air traffic to pick up on any orbital bound satellites or spacecraft so that it may be avoided? | [
"Generally speaking, any time there is a rocket launch occurring there will be a temporary flight restriction (TFR) places within 20-50 nautical miles of the launch site prohibiting air traffic from entering. Those TFRs are published by the FAA at all sources that a pilot should be expected to check before embarki... | [
"Prohibited airspace is temporarily declared around the launch site by the FAA.",
"This information is made known to pilots by notices called NOTAMs (Notices To Airmen)."
] | [
"That's pretty fascinating. Thank you."
] |
[
"How radio (and wifi) waves don't interfere with each other and send the same information to every location?"
] | [
false
] | Picture: Mainly I don't really understand how radio waves work. I presented several question here, in order for you to help me understand, but the big question is " " Let's start with location - PC1 (the black one) receives data from the router (the red one). This can also apply to FM radio. If I move my laptop, I still receive the same data, so there are waves of information everywhere - but each second it transmits different data, meaning that near the transmitting station, there is a different data that the one that had to travel all the way to the other end of the room/house/street. So why moving the receiver doesn't disrupt the signal? Now look at the blue waves - they hit the wall and get back to the receiver ( waves do get projected from walls right? Well I don't know about wifi, but there are different types of waves right? ) so the receiver gets at least 2 different signal at any given time. Shouldn't it also disrupt the signal? If we talk about a wifi for a second - in every part of the room there are different set of "1"s and "0"s, and it received "1"s and "0"s simultaneously from all the wall projections. Additional info: I was radio specialist in the army in my country, was AP physics in high school and currently doing computer science major. So I do now understand that specific topic, but I do have some background if you don't want to ELI5. : Well this is a hard question to write without a picture so I did some horrible job with paint ( I don't have Photoshop on the pc ). | [
"Wow great question. ",
"First, off you are correct, signals do bounce off the room and you receiver is obtaining multiple copies of the signal. And because the wavelengths are so small (WIFI is less than 3 cm), a small very fast change could absolutely destroy your packet. ",
"The solution is primarily ",
"c... | [
"So why moving the receiver doesn't disrupt the signal?",
"The speed with which you move the computer or receiver is small compared to the speed of light (how fast radio signals travel) so it doesn't noticeably affect the timing of the arrival data.",
"Now look at the blue waves - they hit the wall and get back... | [
"Wow - this and the other two replies made so much sense. Thank you very much. Now I understand that it's actually a negligible problem, so my reasoning was correct, just not up to scale. And that there is also math included that helps figure out the real signal without the noise.",
"Thank you for your answer."
] |
[
"Can electromagnetic forces also cause spacetime frame dragging? Like what one would observe a few miles from a magnetar?"
] | [
false
] | Could extremely strong rotating magnetic fields cause spacetime distortions or frame dragging? | [
"Yes, electromagnetic fields deform spacetime. Everything that has energy density (and/or momentum density or momentum flux) contributes to curving spacetime. This is quantified by the stress-energy tensor T, which sources the curvature in Einstein's field equation",
"[; G_{ab} = 8\\pi G_N T_{ab}. ;]\n",
"where... | [
"I wish I could understand what I just read"
] | [
"Equations"
] |
[
"Can the Large Hadron Collider be used to make new elements?"
] | [
false
] | I know that the GSI Helmholtz Centre for Heavy Ion Research uses an accelerator to produce these elements, but I doubt there is any accelerator out there that is bigger than the LHC and would be able to smash more elements together. | [
"Hi Apollo, in it's current configuration, the answer is yes and no. I'll explain the no first:",
"No, because the LHC operates energies that are too keep nuclei intact. The normal way to create heavy elements is to slam two lighter elements together. If you were going to take the 7TeV proton beam or the 3.5TeV l... | [
"So what your saying is that the LHC is just too powerful? "
] | [
"Yes. When the ions in breeder reactors collide, they act similar to balls of putty hitting each other and merging. There are some simulations you can look up. ",
"In the LHC, they act more like water droplets hitting one another. There is so much energy that instead of the nuclei fusing normally, the individual ... |
[
"Does the weight of all the paint added to an aircraft over the course of its life significantly change its max payload and/or fuel burn rate?"
] | [
false
] | null | [
"Yes, it does. For that reason, you don't just paint over an old paint job on an airplane. You stip it down to the metal, then prime and paint again.",
"I always thought it was pretty smart of American Airlines to go with the \"bare aluminum\" look for their planes - think of all the poundage they saved!"
] | [
"A quick search on it gave me \"up to 1100 pounds on a 747\" on some airline forum. ",
"The same forum also said that AA does not in fact save any money. Yes they get better mileage, but they spend more on corrosive treatment for their planes. In the end, I would call it same same. "
] | [
"Did it give any numbers or say if it was relative to current fuel cost? With the price of oil up where it is these days, I would estimate that the better mileage is worth the cost."
] |
[
"What kind of bacteria would grow in the glass of water I leave by my bed overnight?"
] | [
false
] | Is it a harmful amount by the time I wake up and need a sip of water. Assume average temperature is 10 degrees Celsius, in the range for bacteria growth. | [
"The use of chlorine and chloramine in drinking water render it free of pathogens at the point of delivery (your tap); other areas use ozone, which does not have as strong a residual effect. These products are added in order to get rid of potentially pathogenic organisms; much of the rest of the world does not enjo... | [
"Take two bottles: just open one and do with second one as suggested above.",
"And compare."
] | [
"Backwash bacteria from your mouth.",
"Don't believe me? Got any partially consumed bottles of water? If not, drink half a bottle as you normally would. Sit it in your hot car for a week. Open the bottle and take a whiff... GAG."
] |
[
"What is the universe expanding into?"
] | [
false
] | null | [
"If I open in browser on my phone in new version I still see the FAQ in the sidebar and can access it. I'm using the rif app and it works fine there as well... weird... would you mind please sending a modmail describing your setup (mobile, new version, etc.) and what it shows when you try to access FAQ. Someone wil... | [
"Please see the FAQ"
] | [
"The guidelines and FAQs pages say they are no longer being updated and are blank."
] |
[
"How does potassium get from food to a cell?"
] | [
false
] | What happens once food enters the intestines, what process recognizes potassium? How does the potassium move from the intestines to a cell in your finger that needs it? | [
"There are quite a few points I wish to supplement / correct.",
"I believe the Hydrochloric acid helps to 'ionize' the potassium (K+) and other ions from however they were stored in the food. For example, NaCl (table salt) would be ionized to Na+ and Cl-, with the help of this highly acidic environment.",
"Pota... | [
"There are quite a few points I wish to supplement / correct.",
"I believe the Hydrochloric acid helps to 'ionize' the potassium (K+) and other ions from however they were stored in the food. For example, NaCl (table salt) would be ionized to Na+ and Cl-, with the help of this highly acidic environment.",
"Pota... | [
"Thank you! That was great! "
] |
[
"What do atoms look like?"
] | [
false
] | [deleted] | [
"Their shapes are difficult to calculate and even more difficult to visualize. ",
"Here",
" is a nice image of several states of an electron in the simplest kind of atom (Hydrogen, with a single proton and a single electron). The state of the electron is like a 3D dimensional \"cloud\", with the density in a... | [
"All of those are \"hydrogen-like\" configurations where there is only one electron. It works for any size nucleus, but when there are more electrons they start to interact with each other and it gets very complicated."
] | [
"http://blog.everydayscientist.com/wp-content/uploads/pentacene-AFM.png",
"On the bottom left is an atomic force microscope image of a pentacene molecule. You can see that the atoms are arranged similarly to the chemical diagram. It's not actually a picture of atoms though, it's a map of how much attraction the m... |
[
"What is used as nutrition to cultivated cell meat? And how much antibiotics is used?"
] | [
false
] | Where does the nutrition to the cells come from. And can you avoid using antibiotics completely | [
"You can avoid antibiotics, but most tissue culture uses some. It is really difficult to do industry-sized cell culture without antibiotics.",
"Also, they use fetal bovine serum as a nutrient, which is essentially baby cow blood, so it isn’t vegan and isn’t very sustainable at this point. Maybe someday they can a... | [
"To elaborate, fetal bovine serum (FBS) is added to the medium primarily due to its concentration of growth factors (encourages growth) and globular proteins (amino acid source). It is typically only a small fraction of the volume of most media. ",
"Most of the culture's metabolic need is provided by the glucos... | [
"Thank you"
] |
[
"If you are traveling at speeds close to the speed of light, would you disrupt the motion of things nearby?"
] | [
false
] | If you are traveling through space at a speed very close to the speed of light, would your mass increase to a such a level that it would begin to disrupt the motion of other bodies nearby? Like, if you whizzed through our solar system is there the potential to throw the orbits of planets off kilter? | [
"Rather, when something going really fast crashes into something else, it has a momentum that is greater than just the product of its mass and velocity. This new ratio of momentum to velocity is what was called \"relativistic mass.\""
] | [
"This is a very widespread misconception. In actuality, there is no such thing as relativistic mass. So the answer to your question is a simple, unadorned \"no.\"",
"The mass is invariant between frameworks, but that does ",
" mean that the gravitational force is independent of velocity. You then have to use ge... | [
"This is a very widespread misconception. In actuality, there is no such thing as relativistic mass. So the answer to your question is a simple, unadorned \"no.\""
] |
[
"Since our stomach acid is a strong acid, when we drink water does it react with that acid and form H3O+ in our stomachs?"
] | [
false
] | null | [
"The stomach acid is already a watery solution and dissociated. The H3O+ is already there."
] | [
"What is stomach acid actually?",
"Hydrogen-Chlorine(HCl)?"
] | [
"Yeah, HCl at a pH between 1 and 3."
] |
[
"Could you dry wet clothes very quickly by generating a vacuum around them?"
] | [
false
] | And if you built a machine that could do this, would it be more energy efficient than a tumble dryer? | [
"You can, but you will still need to add additional heat to dry them quickly. As the water boils at the lower pressure, heat is removed from the clothes and remaining water. Since the heat of vaporisation of water is much higher than the heat of fusion, the remaining water will quickly freeze in the clothes. Additi... | [
"water boils at low pressure."
] | [
"Yes you can, and I suspect that it would not. It takes a lot of energy to draw a vacuum."
] |
[
"Is it possible, under special circumstances, that noble gases could be forced into molecules?"
] | [
false
] | Basic chemistry courses always state that noble gases don't create molecules with other atoms, but I know in higher levels of chemistry there is a little wiggle room to the rules. An example I always refer back to is that pH can be outside of the 0-14 scale, it's just not told to basic chemistry students. | [
"Yes, it is possible. It's hard but not impossible to get a noble gas to make a bond. Generally you accomplish this by bonding with an element like Flourine.",
"An example is Argon Flourohydride, which decomposes at -256 C (i.e. 17.1 K). See its wiki page ",
"here",
". Also notable is the stable but incre... | [
"Yes, xenon in particular has a number of compounds. XeF2, XeF4, and XeF6 are all possible and (relatively) stable. The basic hybrid orbital theory (\"octet rule\" and such) that is taught in introductory chemistry is not sufficient to explain these compounds, but suffice to say that when you're taught the ",
" m... | [
"As the others have said, noble gases can form a number of compounds, which are usually pretty reactive. As a rule of thumb, the heavier the noble gas, the more compounds it forms. While He, Ne and Ar extremely reactive molecules, Kr and Xe form a number of relatively stable compounds. ",
"KrF",
" for example i... |
[
"Why do plants need mitochondria?"
] | [
false
] | If plants can produce ATP in chloroplasts, why do plants have mitochondria? | [
"They produce ATP in chloroplasts, but they ",
" use aerobic respiration! Excess oxygen is released as a waste product, but they have no trouble using some of it again in the mitochondria."
] | [
"Also think about seeds, when they germinate they are not yet photosynthesizing and are still able to perform complex molecular tasks in order to establish. Another example would be the pollen tube, it needs to grow through the style to the ovary without photosynthesis."
] | [
"I'm glad to hear you are enjoying your plant classes, plants are truly wonderous. I highly recommend you learning about fungi as well, they rock :D"
] |
[
"Is advertising effective on people with disorders such as aspergers?"
] | [
false
] | null | [
"Depends upon which advertising strategy they're using, the severity of the specific deficits of the person, and what method was used (internet banner ad, mail, TV commercial, etc.). What specifically did you have in mind? We might be able to link it to a cognitive strength/weakness and help explain why it might or... | [
"The kind of ads i had in mind were things like beer commercials which show people having a good time or doing something funny followed by the product name."
] | [
"Well, anything that's going to be a 'bandwagon' approach isn't going to work subconsciously, most likely because of a lack of social identification with the people involved. But I'm not an Aspie and I can tell you that those types of commercials don't work with me, either. :)",
"Now, would they remember the prod... |
[
"How do we know for sure the Mariana Trench is the deepest point in the ocean?"
] | [
false
] | null | [
"We have a low resolution survey of the entire ocean floor. That constrains pretty well what the overall topography is like, and certainly the very deep sections are incredibly restricted in location - they're all related to subduction trenches. Whether the Challenger Deep is the very deepest section or not is a bi... | [
"Like where?!"
] | [
"I don't know Pacific bathymetry well enough to say I m afraid. There may not even be any plausible candidates. "
] |
[
"Question about Curiosity mission and space probes"
] | [
false
] | While I'm absolutely thrilled at the successful launch of such a high profile mission, I can't help but have some doubts about its ultimate goals. Doubtless some great science will be done and new discoveries will be made. However if we're going to be looking for evidence of life wouldn't the resources be better spent on sending a mission to Titan, Europa or Enceladus? Are there any practical reasons why we haven't sent probes to these moons? Do we simply keep sending probes to Mars because of proximity and technological limitations? | [
"Well, there's a mission planned for Europa in 2020 and a probe landed on Titan in 2005. It's not like 100% of planetary exploration is devoted to Mars."
] | [
"There are some daunting technical challenges with reaching the liquid part of the ice moons. I'd like to see a 2 component mission with an impactor followed by a autonomous ROV-type sub, coupled with an orbital telecom relay. A bit like the way we've handled the Deep Impact program on Tempel 1. But you'd have to s... | [
"Europa in 2020 ",
"Ganymede too!"
] |
[
"Can someone explain chalcophiles to me?"
] | [
false
] | I completely understand how certain elements will preferentially form ionic bonds and enter the rock phase as lithophiles. I completely understand how other elements will preferentially form metallic bonds and enter the iron core as siderophiles. The distinction between ionic and metallic bonding is clear enough. But what is it about sulfur? Why do certain elements “love” sulfur but not oxide or silicate anions? What characteristic of the sulfide bond makes metal-sulfides behave different from ordinary ionic compounds? Does it have to do with sulfide being a larger, “softer” (more polarizable) anion than oxide? | [
"Yes, it's basically polarizability. See: ",
"https://en.wikipedia.org/wiki/HSAB_theory"
] | [
"Thanks."
] | [
"Thanks."
] |
[
"If a human settlement is established on Mars, would the lower gravity make pregnancy/childhood difficult or impossible?"
] | [
false
] | Once a human has developed to a certain point on Earth, then I could see them going to Mars and surviving, but until that point it seems that lower gravity could adversely effect embryological development and/or a newborn's development. Besides just muscular/skeletal development, are there other vital biological processes or structures that are dependent on a certain amount of gravity for proper functioning? | [
"There's a good ",
"review",
" of pregnancy in microgravity. Pregnant rats have produced relatively normal offspring in microgravity, though with reduced weight and bone calcification."
] | [
"Mars has gravity rather than microgravity, it is just significantly less than here on earth. The studied aspects of animal fertility and birth so far suggest that those cycles on mars will be less risky than in space however there will still be moderate to significant adaptions in physiology to martian gravity. In... | [
"Gravity actually has a large influence on our physiology. Astronauts who have been in a gravity-less state for a few months have to \"rehabilitate\" for a significant period upon return. Our bodies are very strong at adapting, and no (or lesser) gravity means you're using muscles a lot less than here on earth, mak... |
[
"[Biology] How do animals, both mammal and non-mammal handle eating active, living prey?"
] | [
false
] | As a human, I can’t imagine eating an entire living organism whole, and NOT experience severe indigestion. What with it still alive, for a time, in my stomach wiggling about. So how do animals tolerate this? | [
"I amby far not a professional so I will delete this answer when somebody with more knowledge will answer but nearly no animal eat active living prey.\nThe only animals I can think of who eat a whole animals at once are snake, some birds and fish. (If you have any other example I'm interested).\nSnakes usually kill... | [
"Baby eels in Japan, baby octopus in Korea, maggots from casu marzu in Sardinia, grubs, ants, shrimp in China, oysters, sea urchin ..."
] | [
"Tbf I think humans are the species that eats most other species alive.",
"What makes you think that? I cannot imagine having eaten anything alive - besides accidentally swallowing a tiny fly."
] |
[
"Is this Russian methane release as ominous as it sounds?"
] | [
false
] | [deleted] | [
"It's Arctic methane release. Your title made it sound like the Russians are releasing it."
] | [
"There is already ",
"a discussion",
" on this on ",
"/r/askscience",
" ",
"I think that ",
"things_break's reply to limitnz",
" does a good job with this."
] | [
"FWIW, TIL that there are estimated to be ",
"1.3 billion cattle in the world",
", so a few billion tones is a few annual-world-cow-outputs (or, ",
", as we like to call them around here)."
] |
[
"Is it possible to achieve a temperature higher than the temperature of the surface of the sun using a system of lenses only using the energy of the sun?"
] | [
false
] | Every sun ray has an energy of E=v*h. By focusing all the rays emitted by the sun to a single point on earth, would it be possible to achieve a temperature of over 6000K? | [
"No you cannot make something hotter than the surface of the sun by focussing sunlight onto something.",
"What you do when you focus sunlight is basically increasing the apparent object size of the sun for the object being irradiated. (This is called the ",
"brightness theorem",
")",
"In the extreme case, y... | [
"But every object radiates some energy: the hotter it is the more energy it radiates. So it will reach a temperature such that it loses as much energy because of its thermal radiation as it gets from the Sun (if there isn't any convection or conduction). Since it loses energy in all directions, the best you can do ... | [
"You can increase the intensity at the target, but you cannot increase the brightness of the source.",
"To illustrate why: Say you have a source of roughly 2cm at a meter distance. The angle from which light is reaching the target is roughly one degree. If you now put a convex lens between target and source you c... |
[
"Is there any liquid lighter than air?"
] | [
false
] | Is there any liquid (or even a solid) that, under room temperature and standard pressure, has a lower density than air? I'm studying engineering, first year, and I was asking myself this question while learning physics :) | [
"No. The particle densities in a gas are far below anything that can be achieved in solids or liquids, in which intermolecular bonds are important."
] | [
"The answer is the same but the question removes the constraint of air being the gas."
] | [
"The answer is the same but the question removes the constraint of air being the gas."
] |
[
"Does the last rep of lifting weights help more than the first?"
] | [
false
] | Basically what I mean to say is: do the harder reps later on of the same weight provide more value than the first/easier ones? edit: I guess by "provide more value" i mean help you build muscle more. | [
"'stimulate muscle growth more effectively'"
] | [
"They'll definitely have an answer, but it won't fulfill the same criteria of scientific supportedness."
] | [
"Citation? Wouldn't it make more sense that later reps break more fibers? If you have a partially broken muscle then those fibers are not working, correct? So you have an effectively weaker muscle at the last reps meaning more exertion is required to complete the rep. Wouldn't this mean that the fibers are under mo... |
[
"What does one mean by positive and negative approach in quantum theory?"
] | [
false
] | null | [
"any updates on this question ??"
] | [
"any updates on this question ??"
] | [
"any updates on this question ??"
] |
[
"Preparing figures for publication?"
] | [
false
] | [deleted] | [
"When I first started publishing I worried about this stuff too. I brought up the issue to my adviser. His response was, \"just ignore it and we'll deal with it if they ask.\"",
"I ignored the rules, the journals never cared (like you mention, the dpi was always high enough)."
] | [
"It's a fine way to deal with it. I used to be the managing editor of a scientific journal. When I took it over, the instructions for authors still reflected the requirement for old-fashioned hand-drawn figures that couldn't be easily resized, or had to be photographed and resized at great expense. I guess other jo... | [
"It's a fine way to deal with it. I used to be the managing editor of a scientific journal. When I took it over, the instructions for authors still reflected the requirement for old-fashioned hand-drawn figures that couldn't be easily resized, or had to be photographed and resized at great expense. I guess other jo... |
[
"Can the Sun be used in gravity slingshot maneuvers to propel probes to neighboring stars?"
] | [
false
] | Assuming we can develop a probe that can survive and fly above the Sun's atmosphere, could we use the Sun in a gravity slingshot maneuver to help propel a probe to a neighboring star? says that something outside our solar system could use the Sun in a gravity assist, but doesn't talk about something inside using it. This implies we'd need black holes or neutron stars to achieve relativistic speeds. So the follow up question is: could we use our sun repeatedly to attain relativistic speeds? | [
"This would work in theory, but you'd need a huge amount of propellant and a relatively small spacecrat.",
"The problem is, to get to the sun, you have to scrub off the 30km/s orbital velocity of the Earth. There are two ways you can do this. ",
"Use a series of gravitational assists from Venus and Mercury to s... | [
"It might be useless to use the Oberth effect near the Sun with the delta-v we have in space craft right now. But if we're talking about going to neighbouring stars then I think we can assume that we have a whole lot more delta-v available. And we don't need all that much more for the Sun slingshot to be effective.... | [
"The speed of Solar Probe Plus is purely from falling towards the Sun from the orbit of Venus. Venus provides the gravity assist to get into that orbit, but the rest is just an effect of its new orbit around the Sun."
] |
[
"Is it possible for a planetary body or a star to have a spiral orbit instead of a planar ellipse/orbit?"
] | [
false
] | Title. | [
"Planets will (insanely slowly) radiate energy through gravitational waves, spiralling into the star. So you could say they all have spiral orbits. But insomuch as you can approximate gravity using Newton's law of universal gravitation, the planet will always move in a conic section. Namely an ellipse, parabola, or... | [
"Does this count?",
"\n",
"https://en.wikipedia.org/wiki/Apsidal_precession",
"\nThis motion happens for a number of reasons including third body interaction, tidal or rotational perturbations and famously general relativity."
] | [
"AFAIK the earth's orbit around the sun is 'spiral' moving \"'Nth to Sth\" (up and down?) of the suns equator and back again every 33,000yrs or so",
"IIRC It's often when the earth is at it's farthest distance away from the sun during one of these periods that ice ages have occurred"
] |
[
"How do islands get internet?"
] | [
false
] | null | [
"Mostly via cables that run over the sea or ocean floor. The same way that we connect the Americas to Eurasia.",
"Smaller islands, where it's not worth the investment to lay cables will use some form of satellite internet."
] | [
"Smaller islands, where it's not worth the investment to lay cables will use",
"Or radio lines on the surface. If there's a line of sight (with towers), microwave links is a good alternative. This is used for instance on offshore installations in the north sea."
] | [
"Just to quibble a bit with your last sentence - photons are much better. That's why most new backbone is fiber and not copper."
] |
[
"Why do some people who contract infections show no symptoms?"
] | [
false
] | How are some (most) cases of influenza, etc asymptomatic? Does this mean the body has fought and removed the virus without giving symptoms? | [
"Almost all symptoms of a infectious disease is caused by the immune systems response and not the pathogen itself. The objective of an infectious pathogen is to actually remain undetected by the immune system as the more pathogenic it is, then the less likely it will be able to reproduce and infect another host, as... | [
"Is not having symptoms (w/o vaccination) identical to having been vaccinated? Is it immunity or just not having pathological readtion "
] | [
"There are two parts of your immune system; the innate and adaptive immunities. When you get sick the symptoms you see are primarily caused by the innate immunity which is your immediate reaction to infection.",
"But when you get vaccinated, you're introducing your immunity to a weakened pathogen so you'll techni... |
[
"Poison Control Education for 8th graders. Any ideas? [X-Post r/AskReddit]"
] | [
false
] | I have the duty of coming up with some sort of presentation regarding 'Poison Control' to a group of 8th graders. So far I have a few ideas on what I want to talk about, but I definitely need more and some type of activity or worksheet. My ideas so far include The dangers of mixing bleach and ammonia products How taking too much Tylenol (acetaminophen) can be very dangerous Inhalants such as Pam can coat the lungs and cause suffocation Not to 'warm up the car' with the garage door shut Burning 'pressure treated wood' in the house can cause a release of toxic gases, including arsenic. Consuming large amounts of orange juice can cause hyperkalemia (intro into how large amounts of 'benign' substances can be harmful) Flee/Tick collar are not for human use. Warfarin = Rat Poison (Dose makes the poison) I am trying to stay away from any anti-drug stuff. I have the bit about inhalants, and tylenol, but I feel like those relate to house-hold poisons more so than other drugs. If anyone has any other ideas on things people may not realize are dangerous, please I am open to suggestions. (I am partnering with Poison Control and have looked at everything they have to offer.) Thanks everyone. [X-Post from AskReddit] I did not receive much input there and am hoping you all have some ideas. | [
"Warfarin = Rat Poison (Dose makes the poison)",
"Eighth graders won't have any idea of what Warfarin is. I doubt many college students would either. ",
"Use water. Same concept, more relateable. "
] | [
"It sounds like you have a great cross-section of common things that can be dangerous if used improperly. I might also bring up antifreeze (which is sweet) and some shampoos as being toxic is used improperly. I would also talk about carbon monoxide broadly (e.g. from a broken furnace), in addition to specifically i... | [
"You should make them all memorize the poison control center hotline #. (800)222-1222"
] |
[
"If the universe and our solar system are in motion and subject to shift over time will this eventually affect the accuracy of our modern calendars?"
] | [
false
] | If our universe and solar system are expanding as so many sources put forth will the fact that we have a static calendar eventually become an issue? Will adjustments need to be made at some point in the coming centuries? | [
"Actually, the Solar System isn't expanding - the overall expansion of the universe has to compete with gravity, and gravity wins on all but the very largest scales. Even nearby galaxies have \"peculiar velocities\" which differ from Hubble expansion, due to interactions with our galaxy and others. There's a bit of... | [
"Even though the expansion of the universe isn't a factor as Dannei stated, Coordinated Universal Time (UTC) is updated from time to time with leap seconds to adjust for uncertainties and changes in the rotation of the earth. "
] | [
"Thanks much for the explanations. Interesting to think about individual solar systems held together by the glue of gravity whilst the rest of the universe expands. I'd love to know more about the history of the mathematics and science that went into the creation of the modern (adjustable) calendar. "
] |
[
"How do kangaroo foetuses know where to go?"
] | [
false
] | I have just seen that a month after conception, the baby kangaroo is essentially born where it weighs around 1 gram. It then climbs up to the mothers pouch, where it remains for 3 months. How does it know that it needs to climb upwards, or that it needs to find the pouch? In fact, how does it even know about the pouches existence? Thanks :) | [
"Not sure about kangaroos, but possum mothers use their spit to slick down a line of fur leading from their uterus to their baby-holding area. The possums then crawl up there since it's the easiest way to go."
] | [
"Same way human babies grow and learn to crawl, then walk themselves and same way birds know how to build nests without ever being taught how to",
"Its instinct and intrinsic preprogrammed brain functions that these birds and kangaroos are doing. You can have 10 baby animals and 10 mothers yet each will know who ... | [
"Fascinating. Restating the question: How does the mother possum know to do this?"
] |
[
"Are there extinct subatomic particles?"
] | [
false
] | Or are there elements that don't exist anymore? If a lot of crazy things happened around the time of the big bang, and that was an insanely long time ago, does that mean there could be elements or particles that no longer exist? | [
"There are many particles that were produced in abundance in the early universe, but which are very rare today. Matter we see today is primarily made of electrons, up quarks, and down quarks; we also see light (photons) and neutrinos.",
"But there are all sorts of unstable particles that we can create in the lab... | [
"Not in the way you are thinking about them, no.",
"Particle physics may change at different energy scales, but that has not changed. In other words, as soon as we reproduce interactions at that energy scale, we reproduce the exact same physics that existed when that was the average energy scale of the universe."... | [
"the laws of physics are founded upon the belief that physics is the same everywhere and always has been with relatively little evidence (a small segment of time in an extremely small patch of space)",
"This is simply not true. We have evidence from spectral lines, the cosmic microwave background, studies of sup... |
[
"How accurate/accepted is my physics professor's assertion about the passage of time?"
] | [
false
] | I am a college student and one of my courses this semester is an intro to college physics. My professor has a tendency to break off from discussing vectors into tangents on various topics including metaphysical ideas and advanced (I think very advanced, but painted in broad, vague strokes) physics. When speaking on the topic of time recently he asserted that the modern thinking is that, contrary to the way people typically think of time - fluid and infinitely subdividable - there is a extremely small but finite (I think he spouted off a number in teerms of nano seconds) period of time beyond which time cannot be subdivided for the sake of describing rates of change in the universe, because no change occurs in the gap. If this is a real theory hopefully it will ring some bells. Can anyone speak to the validity of this idea? | [
"Perhaps he was referring obliquely to the ",
"Planck time",
"?"
] | [
"Well, as you can see ",
"here:",
"The resulting candidate for a theory of quantum gravity is Loop quantum gravity, in which space is represented by a network structure called a spin network, ",
".",
"One of the theories for quantum gravity (Loop quantum gravity) use the idea of quantum time. But it's one o... | [
"I also believe that is most likely what he was referring to, given he seems to be saying that it is rather meaningless to subdivise it any further, rather than say that it can't be."
] |
[
"Perfect hollow spherical mirror. Let some light in, what happens?"
] | [
false
] | null | [
"Well your question answers itself, a perfect mirror will not convert any light into heat but such a mirror will never exist."
] | [
"If the shell was thin enough and you waited enough time, the photon could quantum tunnel it's way through the shell and escape."
] | [
"Try a search",
"."
] |
[
"Ugh, boring question: when sucrose is dissolved in water, does it disassociate into fructose and glucose, or stay as sucrose?"
] | [
false
] | null | [
"Yes. The acid catalyzes the reaction that breaks the bond between the fructose and glucose rings. This takes sucrose, which is prone to crystallization because it is very pure, and turns it into a mixture of sucrose, fructose, and glucose, which is much less prone to crystallize out. ",
"Adding invert sugar (... | [
"If you look closely at the ",
"glycosidic bond",
", you'll find that it is an ",
"acetal",
". As acetals are labile in acid, the hydrolysis rate depends on the acidity of the solution. At pH 7, it occurs very slowly - ",
"half-life of about 500 years",
" (Figure 2)."
] | [
"Is that why some cooks add lemon juice when dissolving sugar to make caramel?"
] |
[
"Why are aluminium foils so used in physics experiments setups and what for?"
] | [
false
] | Very often, when visiting labs, or on pictures in articles, I've seen parts of experimental devices wrapped up with aluminium foils. Here is I randomly found with google. What is it for, and why aluminium? | [
"I work with many clean systems and vacuum systems, and I use aluminum foil because it's cleanable and doesn't leave lint. It also stays in place over an opening without needing a string tie or something, and actually has quite a bit of strength if you use the heavier stuff. ",
"I also use it to wrap pipes that n... | [
"Most aluminum foil you buy is actually rolled two sheets at a time, and it has a bit of oil or lubrication between them. It doesn't matter at all for people at home, but with clean parts it's unacceptable. We buy foil made specially without lubrication on it. For critical parts, you clean it with a solvent and cle... | [
"SPX_hbar mostly touched on this, I'm going to rephrase what s/he said and expand a bit.",
"In our lab we have a lot of vacuum chambers that we need to use with very low pressures inside. One of the things that makes chamber pressures worse is water -- water has a very high vapor pressure at room temperature, bu... |
[
"How would air get trapped in a solid crystal?"
] | [
false
] | Currently on the front page is a gif of a quartz crystal which contains a pocket of water. The pocket of water also contains an gas bubble. How is it possible that such a formation could form? | [
"Inclusions of water in crystals such as quartz frequently contain a small bubble. The bubble commonly contains water vapor, but can also contain other gases such as CO2 or natural gas. The inclusions of water plus vapor generally form because of some growth defect during the growth of the crystal as the crystal pr... | [
"Could you link to the gif? I've seen gifs of a very large, but fake inclusion. They made it by taking a big quartz crystal and using clear epoxy to make fake fluid filled inclusions."
] | [
"Just google fluid inclusions for images. Fluid inclusions in quartz that show the behavior described above can be created artificially in the lab in an epithermal cell, i.e. a device that can be heated and pressurized in the presence of an aqueous solution of silica. While \"fake\" they just look like inclusions f... |
[
"How common is our Moon's orbit which causes it to always show us the same face to Earth?"
] | [
false
] | As stated in the title, is it common for other planetary moons to show the same face to the body they orbit? If not, are there any theories as to how our moon's orbit evolved as such. If so, what causes this to happen? | [
"It's quite common, essentially all the large moons in the solar system are tidally locked to their planet. It's not a random occurrence, it happens because the gravitational gradient from the planet exerts a drag on the rotation of the moon that gradually slows it down until its rotation and its orbit are in synch... | [
"They do! In other solar systems. Most of our planets are too far from the sun for tidal locking, but Mercury has spin-orbital resonances such that it experiences three days every two years.",
"These guys",
" managed to calculate a temperature map of an extrasolar planet using clever spectroscopy and found that... | [
"Why don't planets suffer the same effect from their sun?"
] |
[
"What does the top of a lightning bolt look like?"
] | [
false
] | Since the lightning bolt isn't actually attached to anything and the top of it is hidden in the clouds, I was wondering what the upper edge/boundary of a lightning bolt is shaped like. Is it just a mass of electricity? Does it fade into nothingness near the top? I can't quite picture how the source would appear. | [
"So essentially there's an avalanche of electrons that starts at the cloud and propagates towards the ground. ",
"Does this help your explanation a bit? After reading your reply it instantly reminded me of this gif."
] | [
"When it touches the ground there is a trail of ionized air (from the avalance) connecting the charged cloud to ground. Current can then flow en masse through the ionized path and you get the main flash"
] | [
"If the bolt is directed from the cloud to ground, it will fade into nothing. I'll try to explain why with a simplistic description of lightning. The lightning bolt is essentially an arc that propagates from cloud to cloud, cloud to ground or ground to cloud. Let's assume cloud to ground. You have a build-up of... |
[
"Does rain fall in a pattern?"
] | [
false
] | null | [
"If you're asking does rain fall in a pattern on the ground in your front yard, the current consensus is maybe, but not significantly for most applications. While there will be a distribution of drop sizes (i.e., basically a bunch of small drops and exponentially less large drops), these drops are traditionally as... | [
"The rain may seem to come in waves due to the wind gusts often occurring in downpours. There's also likely turbulence based clustering that you see, especially near the surface and in intense rain. In stratiform situations (think steady rain all day) these \"waves\" of rain are likely less prevalent due to less ... | [
"What about in 3D space? It often seems in downpours that the rain is coming in waves. Is this my imagination, of an actual phenomenon ?"
] |
[
"Is there any correlation between eye color and light sensitivity?"
] | [
false
] | I have very dark (almost black) eyes and am very sensitive to light. I basically have to wear sunglasses any time i'm outside. Is this at all because of my eye color? | [
"Well, sensitivity is somewhat dependent on your medical history etc. But it is a fact that people with lighter eyes allow more sunlight to pass through the eye itself and so are at a greater risk of problems associated with uv exposure. People with dark eyes absorb the light and so are less likely to feel these ef... | [
"But it is a fact that people with lighter eyes allow more sunlight to pass through the eye itself and so are at a greater risk of problems associated with uv exposure. People with dark eyes absorb the light and so are less likely to feel these effects.",
"That's definitely not what my optometrist said when I ask... | [
"True true, i asked my optometrist that as well and you are right. Perhaps I phrased my answer poorly. My comment was regarding the iris, which is the colored muscle of the eye which influences the contraction/dilation of the pupil itself. The retina doesn't have color per say. The retina is the back of the eye and... |
[
"Does fusion occur inside black holes?"
] | [
false
] | I understand that fusion only occurs under extreme temperature and pressure. So this got me thinking; does it also happen in black holes, where there is astronomical amounts of gravity? | [
"No, and I don't think anybody can explain it better than our 'own' ",
"RobotRollCall",
"."
] | [
"You are way past fusion even before you get to a black hole. Precursors to black holes are usually neutron stars (unless the original star is more than 3 stellar masses which is enough to collapse it directly into a black hole). ",
"Neutron stars are already so dense that their gravity has gone beyond the limit ... | [
"Not just atoms, gravity in a black hole is so strong that nuclear particles like protons and neutrons can't exist - gravity overcomes the forces that maintain their structure. It's the breakdown of this subatomic structure that leads to the final collapse to a black hole."
] |
[
"How do surgeons remove an entire tumor without leaving microscopic pieces/cells which can cause a relapse?"
] | [
false
] | null | [
"Leaving microscopic pieces and cells is a known problem, and in fact surgery itself can in some circumstances trigger metastases since cancerous cells are relesed into circulation: ",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5380551/",
"Its a known problem and active field of research. Obviously the goal ... | [
"They don’t. Cells can have escaped and lodged elsewhere. That’s why many tumor removals are followed by chemo or the equivalent for that cancer. And why many times, that cancer comes back but in a secondary area."
] | [
"That's what happened to me. Fortunately my doc ended up getting it all eventually."
] |
[
"Why galaxies are flat? Why there are no spherical galaxies but only disc shaped galaxies?"
] | [
false
] | Gravity should be same in all 3 dimensions then why galaxys are flat , and we don't see a sphere with a black hole at the centre and stars revolving around it around the whole sphere, why disc shape? | [
"There are spherical galaxies! We call them \"ellipticals\" though - they have a bit of angular momentum, so they tend to be somewhat \"smushed\" or \"stretched\" spheres.",
"There is nothing stopping stars from orbitting all over the place - and when disc galaxies merge, often the stars get so stirred up that it... | [
"Interestingly enough, dark matter tends to be in a big sphere surrounding and encompassing the galaxy it's part of. And due to this, we suspect that it does not interact with itself either! It's also why it's probably best labeled as 'Dark Gravity'."
] | [
"If it falls into a black hole yes, it's never coming out. But it's much less likely to fall into a black hole than normal matter.",
"When matter (both normal and dark) gets pulled into a back hole it only rarely gets sucked straight in. It first gets captured by the gravity well and starts orbiting the black h... |
[
"What 'green' technologies are barely helpful/harmful to the environment?"
] | [
false
] | I read an article a few years back in PopSci that mentioned hybrid cars not being that good for the environment when you look into the creation of nickel batteries. The idea was that a Prius has to drive 100,000 miles to make up for the carbon footprint of it's creation. So I'm curious what 'green' technologies are we being sold that are not helpful to the cause or worse hurting the cause. | [
"Biodiesel made from corn is a huge waste."
] | [
"Analysis on the problems inherent with biofuels - \n",
"http://www.unep.org/resourcepanel/Publications/AssessingBiofuels/tabid/56055/Default.aspx"
] | [
"Many forms of recycling are not actually beneficial, depending on the process used, type of material, distance to treatment plant/source for new version, etc."
] |
[
"What defines flavor? Why do some people find things pleasing and others not?"
] | [
false
] | null | [
"Sight and hearing come from well studied receptors that work along easily measurable physical scale, i.e. light and sound frequency. ",
"However, for taste and olfaction there are are thousands of receptors each keyed to different molecular structures that don't follow patters (at least not in the way light does... | [
"huh, that's too interesting. I think I might give these a go."
] | [
"huh, that's too interesting. I think I might give these a go."
] |
[
"Could we ever bring back a long extinct species from prehistoric DNA?"
] | [
false
] | What is the most likely method that Humanity will find/recover prehistoric DNA? Is there any chance of recovering the DNA of even a simple organism or spore from amber? | [
"Japanese, Russian and South Korean scientists are currently attempting to clone a Mammoth.",
"http://www.telegraph.co.uk/earth/wildlife/9139976/South-Korean-and-Russian-scientists-bid-to-clone-mammoth.html"
] | [
"There is a group making mammoths again."
] | [
"The answer is probably not. There are a few people who have claimed to be able to recover tiny snippets of DNA from insects preserved in amber, but those claims have failed many attempts to repeat their findings. DNA just doesn't last that long, even if it's preserved in amber. And amber is probably the best-ca... |
[
"Will water boil faster if it's moving?"
] | [
false
] | Boiling water is when it's molecules move really fast right? So if the water is moving and rippling would it boil faster? Also is that the reason the oceans don't freeze? Because they are always moving? | [
"Truthfully, shaking boiling water will cause it to boil slightly faster, due to the shock waves passing through it. The decreased pressure during rarefaction will speed up boiling at that point slightly. It's insignificant, though. The added energy from shaking is also negligible.",
"Also is that the reason the ... | [
"Why do you think it is trolling?"
] | [
"Why do you think it is trolling?"
] |
[
"Is it possible for a mountain to escape the atmosphere?"
] | [
false
] | null | [
"In general, no, or at least not without a very improbable atmosphere.",
"This is a little difficult since one has to define some threshold where the atmosphere ends, when in reality atmospheres don't have a sudden cutoff like that. However, the height of both atmospheres and mountains scale by the same factor: g... | [
"In general, yes. On Earth, no.",
"Mountains' height is limited by the strength of gravity, the shear strength (or compressive strength, depending on geometry) of the rock, and the density of the rock. So on Earth, the maximum height for a mountain is roughly 10 - 15 km. If this mountain is already on a high plai... | [
"The idea that the difference in gravitational acceleration between Earth and Mars is the sole driver for the difference in the maximum height of mountain ranges is pervasive, but also not quite right. Of equal (and perhaps larger depending on the relative differences) importance is the fact that the support of mou... |
[
"What is it about having extra stores of fat on one's body that makes it so unhealthy?"
] | [
false
] | There are many studies that show that being overweight increases risks of all types of diseases. But is it really just having extra fat on one's body that leads to increased health risks? Or could it be some other factor, like overweight people eating less healthy foods? I don't really see why just having fat on your body would inherently be bad. It's just stored energy, isn't it? | [
"One issue is that the extra fat can deposit in arteries. This can lead to several health problems, the most obvious being heart attacks from blocked arteries."
] | [
"Visceral fat responds more to glucocorticoid with lipolysis, and releases more FFAs into circulation, which is thought to contribute to insulin resistance. It also produces a number of cytokines that have systemic effects both on the endocrine system (along the lines of metabolic syndrome) as well as vascular sys... | [
"Additionally, visceral adipose tissue appears to have greater proportion of activated immune cells that contribute to chronic, low grade inflammation, which is associated with many comorbities of obesity. Additionally, adipose must be substantially vascularized, which leads to a greater work load on the heart, eve... |
[
"Is the number of faults on Earth's surface generally an increasing function of time?"
] | [
false
] | As time is measured over billions of years? Would this also apply on exoplanets? | [
"Interesting question.",
"While new faults are occasionally created, most fault motion (earthquakes) occur along already existing faults.",
"So new faults are occasionally added, but old ones are also removed through subduction and erosion. Quite what the balance is I'm not sure, and certainly there are many an... | [
"most fault motion (earthquakes) occur along already existing faults.",
"I second this. The Earth's crust is permeated with faults, and when a new deformation process begins it usually just reactivates and then modifies pre-existing structures. ",
"My instinct would be that the number of faults on a geologica... | [
"This may be correct near the surface, particularly where an existing fault line is a zone of weakness which releases stresses intermittently. However, if there is mineralisation associated with a fault, it could become stronger than the rock in which the fault first formed. "
] |
[
"Why is it so unbearably uncomfortable when a body part \"falls asleep\"?"
] | [
false
] | null | [
"5) The brain perceives this situation as that horrible and unique tingling sensation everyone hates, rightfully so.",
"FTFY"
] | [
"5) The brain perceives this situation as that horrible and unique tingling sensation everyone hates, rightfully so.",
"FTFY"
] | [
"Haha, indeed. I'd like to add that the \"pins and needles\" effect is called paresthesia. Thought it would be appropriate to mention that here. "
] |
[
"How would the drake equation be affected if one were to consider AI to be an Extra Terrestrial civilization?"
] | [
false
] | I was meditating on the words of Carl Sagan when I started thinking about robot civilizations. Would it be possible for an intergalactic species to contact us via robotic spacecraft? If so, would this have a functional impact on the fraction fc? (the fraction of civilizations that develop a technology that releases detectable signs of their existence into space ). | [
"I think you are over-thinking this? I mean, yes, if we had some knowledge about the proportion of civilizations which developed and sent out robotic spacecraft, then we could incorporate that into our calculation of fc. But we don't. We don't have any data on fc, because we don't know of any alien civilizations, s... | [
"You can read up on the Fermi paradox. Self replicating machines basically throws a curve ball. We can reason that an intelligent species would eventually create self replicating machines to explore the universe. From the speed they replicate at and the age of the universe, it can be reasoned that self replicating ... | [
"great question. but i think that for an artificial life-form to have been created, an actual thinking life-form had to emerge in order to create it. so for this secondary life-form to contact us it would be less likely than the drake result."
] |
[
"Why is gravity often considered to be the weakest of the fundamental forced when its effects can be felt so far away from the source?"
] | [
false
] | How is gravity weaker than say the electromagnetic force? Jupiter is far more influenced by the sun's gravity than the sun's magnetic field. Why do scientists mean when they say gravity is the weakest? | [
"It's weaker in the sense that if you take two charged particles (let's say two electrons), the electrical force between them is much much stronger than the gravitational force between them. Both forces act according to the same general form (they fall off as 1/r",
" and they are proportional to the respective ma... | [
"Easiest test, Hold a pin with a magnet above the floor. In so doing, the electromagnetic force of the magnet in your hand is able to resist the gravitational force of the entire planet earth pulling on the pin. ",
"Similarly, you have two 1 gallon jugs of water, sitting one meter apart. The repulsive force of th... | [
"As for strong and weak nuclear forces, those only act over small scales."
] |
[
"Does mammals have menopause like humans? And do they have sex \"for fun\" even after they ate unable to reproduce?"
] | [
false
] | null | [
"Only primates, mostly old world primates (great apes, macaques, baboons), can be generally said to \"menstruate\" (here's a few papers about the evolution of menstruation: ",
"1",
" and ",
"2",
") so only they would have the possibility of going into menopause. It seems like the research has mixed results ... | [
"Bonobos have orgies to resolve conflict between groups. I believe this frequently includes homosexuality. (EDIT: homosexuality --> nonreproductive sex.. I'm not sure if this is what you're wondering, but hopefully it helps!)"
] | [
"IIRC only Orcas are known to undergo menopause. Dunno about their sex lives afterwards."
] |
[
"How can a part of the brain be simultaneously less active and more connected?"
] | [
false
] | A lot of research about the effect of psychedelics on the default mode network shows in the default mode network but between the default mode network and other nodes or networks (and sometimes more connectivity between nodes in its own network). How can a part of the brain be simultaneously less active more connected? Doesn't connectivity imply activity? I've Googled this, because it seems like it should be a simple answer, but I can't find anything. | [
"Brain connectivity can be structural or functional.",
"Structural connectivity usually uses DTI to map the white matter pathways to see how much white matter connects various regions. This is not directly related to activity.",
"Functional connectivity uses fMRI, EEG or the like to see what the *correlation* i... | [
"Thank you. I hope a clarifying question is alright:",
"So when two areas have high functional connectivity, it's possible for that connectivity to be negative? Activity in one area goes up and activity in another area goes down (maybe because one area is inhibiting the other or for some other reason, I don't kno... | [
"Thank you so much. That really helps."
] |
[
"Can I use my regular sunglasses to see the transit of Venus?"
] | [
false
] | [deleted] | [
"If you read the article you linked they have a big NO! section that says specifically not to use sunglasses, as they will not offer the right kind of protection from the sun."
] | [
"No.",
"Your sunglasses are nowhere near enough protection.",
"Welder's Glass #14 (I think this is the darkest of all welder's glass but hopefully someone else can say for sure) ",
"is deemed suitable for direct viewing",
"."
] | [
"Yes, you should be able to find, if not the glasses, then the material the glass is made of at a home hardware store. ",
"You'll notice the difference if you actually put on a pair of the $1-$2 glasses. While you can look at the sun and see it quite clearly, you can't see ",
" while wearing them. Those glasses... |
[
"RE: This news about a star seeding the universe with water - Isn't water fairly easily formed on a planet anyway?"
] | [
false
] | Pertaining to Combining hydrogen and oxygen to make water is a relatively low energy reaction from what I know (as well as separating water back to them). I don't think the problem is amount of these elements in the universe, but rather that many planets are inhospitable to the water sticking around due to temperature, lack of atmosphere/magnetic field for protection, lack of a solid surface, etc... I see so many people talking about "Oooh this could be where our water came from!!" I just don't see it being that big of a deal. Am I wrong? EDIT: I have to say though, I'm surprised the H2O molecules are intact after being ejected at such speed and energy | [
"I'm not sure this is as well-established as you imply. The ",
"D/H ratios of comets",
" are wrong for them to be the only source of water on the Earth. The most likely alternative is that the water was present in the material that formed the Earth and was subsequently outgassed from its interior. Regarding the... | [
"Most of the water on Earth came from comets bringing it to Earth. We know this be the Deuterium ratio in the water. There is alot of water on dust grains in interstellar dust, but the question is in what state? Most of the water is in ice form. I read this article and they of course make it sound like amazing news... | [
"I'm not sure that is entirely correct either. The available evidence doesn't point to comets as being a likely source for water as rocksinmyhead pointed out above. Also even if water was present in the early material it probably wouldn't have stuck around for accretion."
] |
[
"Would the same baseball player generate more power with a heavier or lighter bat?"
] | [
false
] | Say he can choose from a 30 oz bat or a 36 oz bat, which would generate more power hitting the ball? How would a player determine the optimal weight for which bat size to use? | [
"A heavier bat would usually generate more power because a slower swing builds up more momentum. A lighter bat may carry more kinetic energy but this figure is not very important when compared to the rate of energy transfer between the bat and ball. Getting the best energy transfer requires a proper balance between... | [
"I think the reason wooden bats are preferred are because they are more flexible than metal bats, and this flexing action increases the duration of contact, and energy transfer. "
] | [
"Well just based on the formula KE = mv",
" a bat swung 2x faster than a bat twice as heavy would have twice the kinetic energy so I would say the lighter bat would generate more power if it resulted in a sufficient increase in swing velocity. I think this is also why the MLB uses wooden bats and not metal ones."... |
[
"Since Mars doesn't have a magnetic field, how would this affect our ability to use electricity-based technologies there?"
] | [
false
] | [deleted] | [
"It would make no noticeable difference on any of those things."
] | [
"Electronics would be more susceptible to solar radiation, but I'm not sure there would be GIC's (Geomagnetically induced currents) on mars like there are on earth without a magnetic field around the planet.. "
] | [
"A planetary body lacking a dipole magnetic field, shouldn't impact the feasibility of permanent dipole magnets. I would think motors and the like would still function normally in the martian atmosphere.",
"But, our astrophysicists probably know better...."
] |
[
"I've heard that heat is the \"least useful\" form of energy. What does this mean? To do with entropy."
] | [
false
] | This was mentioned by Brain Cox in his program (UK only link, sorry) at around 35 minutes in. But he didn't really explain why one form of energy is a "lower quality" energy than another. | [
"100% of work can be transformed to heat but not 100%percent of heat can be converted to work. "
] | [
"Sory I can't watch the programme so I can't comment on exactly what he said.",
"Entropy is strange and unintuitive concept, yet it is very practical and very well understood.",
"Unlike most of the laws of physics the ",
"second law of thermodynamics",
" is not time reversible, and states that over time in ... | [
"Thank you this seems like a great answer :)"
] |
[
"Where does the energy go during the latent heating phase?"
] | [
false
] | I understand temperature is the average kinetic energy of a substance, basically how fast the disordered motion of each molecule is. What I don't understand is why the temperature should stop increasing at the phase transition temperature until the latent heat has been overcome? For a solid melting, why do the molecules collectively "decide" to stop moving faster once they reach the melting point, wait until they get enough energy (which is going where? Loosening/widening the intermolecular bonds?), and then what causes the sudden phase transition, followed by increasing in temperature normally again? Why does the phase transition depend on the overall temperature of the bulk instead of being more or less molecule-for-molecule? Also, why is the latent heat different for fusion and vaporization for water, what exactly is different about the hydrogen bonds in ice and in liquid if the molecules are the same? Please explain in physical instead of mathematical terms, I want to know what's going on with the molecules themselves in space. Thank you for any answers. | [
"OK firstly let's start by considering what temperature actually is.Temperature is a measure of the ",
" of the particles within an object.",
"When you put energy into something (heat) the energy is absorbed by the particles within the object. In a solid, nothing can move, so the heat energy goes into vibration... | [
"The short answer is the molecules do not collectively decide to move slower or faster on phase transition. When you achieve boiling point of water for example, by continuously providing heat you will see that the water is gradually turned to steam, but the total temperature will go higher than 100°C only after all... | [
"Based upon my understanding…",
"The kinetic energy is not uniform, so you’ll have some molecules with higher and other with lower kinetic energy. When two molecules interact, if there is enough kinetic energy, it will break the intermolecular bonds, causing a phase change for one of those particles. As this onl... |
[
"There's such a thing as finite but edgeless space, so is there such a (hypothetical) thing as bounded but infinite space?"
] | [
false
] | null | [
"You are mixing up a lot of terms here, and so it's a bit confusing what you're asking. So please clarify.",
"So I am assuming that by \"space\" you mean a manifold, and so the only reasonable ways to interpret \"finite\" and \"edgeless\" would be \"compact\" and \"without (manifold) boundary\". If so, then, yes,... | [
"\"Is there such a thing as bounded but infinite space?\"",
"Bounded in this case means with a boundary. When I say infinite, I specifically mean \"you will always have more space no matter how much you take up\"",
"\"Could one theoretically have a space that has borders that can be reached in a finite amount o... | [
"When I say infinite, I specifically mean \"you will always have more space no matter how much you take up\"",
"Again, I really don't know what you mean. Those aren't mathematical terms.",
"It sounds like you want \"infinite\" to mean either \"non-compact\" or \"unbounded\" (if, say, there were a notion of dist... |
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