title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How do birds grow feathers?"
] | [
false
] | Is it just like how we grow hair? Can they re-grow after falling out? If so, how long does that take? | [
"Birds can re-grow feathers, (if one is damaged in a fight or accident) but it takes a while. If the feather is one of several needed for flight (e.g. the wing and tail feathers) a wild bird will be at a serious disadvantage. Captive birds will need to have it repaired and even then it will be weak until a new one ... | [
"Cockatiel person here. I can elaborate on a lot of this.",
"Birds can re-grow feathers, (if one is damaged in a fight or accident) but it takes a while.",
"It's a surprisingly fast process, actually. They can generally get through a full molt within a week or two.",
"If the feather is one of several needed f... | [
"What happens if a feather gets damaged outside of the molting period? Does the bird just have to do without it until their next molting period?",
"They lose and regrow feathers year round. They'll just lose a lot more than normal for a week or two during a molt.",
"Those pin feathers look evil, like something ... |
[
"If 100 perfect coins were flipped with identical starting conditions, would they all land the same?"
] | [
false
] | Assuming we have a model that the coin lands heads 50% of the time. | [
"There's a lot of assumptions in your question—but the spirit is that yes, coin flips, which obey Newtonian mechanics are deterministic. People have built robots that can pick which side they want their coin to land. Even more impressive, you can teach yourself to rig coin flips in your favor."
] | [
"There are many that think that consciousness is a quantum phenomenon and not a deterministic, Newtonian process, so that we do have choice based on who we are/what we're thinking rather than initial conditions.",
"https://en.wikipedia.org/wiki/Quantum_mind"
] | [
"But it seems to me that if we agree that humans evolved from simpler life forms than we cannot say that what we call consciousness appeared at a certain specific point in time but rather it is a spectrum or a scale and other animals just fall lower on it. Are their actions also governed by quantum processes or is ... |
[
"What makes paper fresh from the copier hot? Why don't inkjet printers produce the same amount of heat as copiers do?"
] | [
false
] | null | [
"Laser printers and photocopiers don't work under the same principle as an inkjet printer. When you make a photocopy, the first step is to give an electrostatic charge to a special cylinder. That cylinder is coated with a material that becomes conductive when exposed to light. When the document is being scanned, a ... | [
"Photocopiers and laser printers work by applying a layer of dry toner to the page which is held in place by a static charge. The toner is then cooked onto the page using a heated roller (around 220c from memory). This is why the page is hot.",
"Inkjet printers just spray wet ink onto the page which dries natural... | [
"Thank you "
] |
[
"What process makes drinking carbonated drinks too quickly painful?"
] | [
false
] | null | [
"Edit: Upon further research, both hauntedchippy and I are wrong. It isn't the acidity of carbonic acid (or else good ole' vinegar would produce the same sensation), nor is it the mechanical formation of CO2 bubbles, as illustrated by ",
"this study",
" (first result - unfortunately an online copy isn't availab... | [
"and why does that sting?"
] | [
"This is probably what is stinging your tongue. You probably notice it after holding the liquid in your mouth for a short time. If this is the case you shouldn't notice the pain when the drink is flat.",
"Does carbonic acid form in sugar and alcohol-free carbonated drinks, like mineral water?",
"Carbonic acid... |
[
"How much does using warm or hot water affect cleaning hands or dishes? Wouldn't it require almost unbearably hot water to have any anti-bacterial or anti-microbial effect?"
] | [
false
] | null | [
"The maximum safe temp for handwashing is about 110 for brief or occasional exposure. Higher temperatures will cause chapping and tissue damage. This isn't expected to kill germs - serious antibacterial activity is negligible below 120F and significant heat disinfection (eg contact lenses) requires 180 degrees for ... | [
"For the record, sanitizer gel is shown to be at least as effective as soap and water, against the vast majority of microorganisms. That's why most hospitals put sanitizer dispensers outside all the rooms, and docs and nurses use that instead of washing our hands in between every patient. ",
"The rare exceptions ... | [
"Different bacteria have different tolerances for temperature.",
"Using hot water works better because it is better at loosening things and causing them to rinse off the plate. Cold temperatures can cause things to cling more tightly. ",
"With food it is often fat and grease and oils that cause things to stic... |
[
"Relatively larger particles and Wave-Particle duality"
] | [
false
] | As per this , molecules as large as buckyballs have displayed 'wave bahavior'. I can understand wave-particle duality in extremely fast paced particles like electrons and photons. But I am unable to understand this duality when it comes to molecules or even nucleons for that matter. Some further explanation would be helpful... | [
"Palanoid answered this, but don't think of the quantum wave as the size of a particle. This wave describes the location of the thing and as that thing gets heavier it becomes more localized in space. "
] | [
"Everything is both wave and particle. One thing you can use to make sense of this is the ",
"de Broglie wavelength",
", which tells you the length scale over which quantum (wave) effects are important. The de Broglie wavelenth depends on the mass and velocity of the thing of interest and for a proton (the smal... | [
"Make sure that you don't mix the quantum wave function to waves like em-waves that transmit energy. The |ψ|",
" of position-space wave function corresponds to the probability density of finding a molecule in a given place. The size of the object affects the wavelength of the function. "
] |
[
"How does bleach work in that it strips materials of pigment?"
] | [
false
] | null | [
"Stains are commonly caused by the presence of organic pigments in your clothing, for example ",
"beta-Carotene",
". beta-Carotene gets its red-orange color because it absorbs blue light specifically from the long chain of carbon atoms which connect the two hydrocarbon rings.",
"This carbon chain is what we c... | [
"Wow! Thanks! This was great!"
] | [
"Short version - Bleach doesn't suck out dyes and colours, it chemically attacks and shatters the molecules that give things their colour. It's a quirk of how electrons work that many coloured things share a similar chemical structure so a lot of them can get broken down by bleach. "
] |
[
"How can we trust Max Planck's derived units?"
] | [
false
] | null | [
"Planck units are not fundamental limits. This was never assumed by Planck, nor anyone else.",
"Planck units are just units constructed out of fundamental constants related to special relativity, general relativity, and quantum mechanics.",
"The Planck length is not the \"shortest possible distance\", the Planc... | [
"What I mean by fundamental limits is this: Take the Planck length for example, it tells us that anything equal to or shorter than that will exhibit weird quantum effects that we don't really know how to reason just yet. We also have the Planck temperature, which is supposed to give us an upper bound of sorts for t... | [
"The Planck units are just scales where quantum effects ",
" should become important."
] |
[
"If visible light is just a section of a larger spectrum, why is a color wheel continuous?"
] | [
false
] | null | [
"Hi! This question was asked recently. You can find threads ",
"here",
" and ",
"here",
", and more by using a ",
"search",
". Check them out and let us know if you have follow up questions!"
] | [
"Reddit search isn't the best. Glad we could help!"
] | [
"Thanks! I tried searching, but I must not have looked hard enough. In any case, these answer my question wonderfully, thank you!"
] |
[
"Does a frozen drink have less \"effective\" calories than a room temperature one? How significant is the difference?"
] | [
false
] | Take two Slurpees or similar shaved ice drinks. Let one melt and keep one frozen. What is the caloric difference between consuming them? Is there a significant amount of work that my body does to melt the frozen one vs the room temperature one? Put another way, if I consumed a very predictable diet for a month and had two normal Slurpees a day during that time, then the next month I had the same diet but switched the frozen Slurpees out for melted ones, would there be any difference over time to my overall caloric intake? | [
"Your intake would be the same since the temperature of food doesn't affect the calories contained in the carbohydrate, protein and fat molecules. You might burn slightly more calories as the heat from your body warms the slurpee. Slurpees are basically just ice. It takes 1 kcal to heat 1 litre of water by 1 degree... | [
"You're assuming liquid water at 0 celsius. It takes 80 kcal to melt 1 litre of water before you can start raising the temperature."
] | [
"Really? You know I didn't know that. Well that's a bit of a bump up then. "
] |
[
"Why are trade deficits bad?"
] | [
false
] | null | [
"It isn't bad. A country running a trade deficit with nearly full employment and a stable inflation might be doing fine. Large trade deficits generally put a downward pressure on domestic currency which tend to make imports more expensive. This might lead to higher inflation. Again \"large\" is relative, a country ... | [
"Of course it can be bad --- under some conditions.",
"No country can prosper in state of perpetual trade deficit. Having a deficit implies more is leaving than coming in. To sustain this flow, you have to have enough internal financial resilience to grow your economy even as some wealth leaves it.",
"How lon... | [
"So would the US trade deficit fit under this category? They have had a pretty consistent trade deficit with the world for over 40 years. Is Trump essentially correct in his analysis that consistent trade deficits hurt the economy in the long run?"
] |
[
"If the theory of Supersymetry says there's an equal partner for every particle that we can observe, why is it that \"dark matter\" accounts for 95% of the universes mass?"
] | [
false
] | If every particle we could observe had an equal partner you might expect the mass to be roughly 50-50, not so ridiculously lopsided. What gives? | [
"Our standard model includes stuff like top quarks (which we know exist via experiment) but aren't expressed in our universe in the same ways electrons and protons are—so rarity isn't new to known physics. The supersymmetric partners in SuSy are all predicted to be quite massive (at least ~1 Tev range) and often ha... | [
"Note that ",
"/u/AsAChemicalEngineer",
" did not mention anything about supersymmetry being real (he said \"predicted\", \"proposed\"). No supersymmetry has never been observed and there is no indication in Nature that it might be real. It is an hypothesis, but a very popular one.",
"Susy is less popular now... | [
"There is about 5 times more dark matter than normal matter, as ",
"/u/AsAChemicalEngineer",
" said. If supersymmetry is true - which we have no indication of - it predicts that there is a partner ",
" for every particle ",
" we see. That does not mean that every electron in the universe has its partner sup... |
[
"Why is the urge to pee more pronounced when we experience strong emotions (excitement, fear)?"
] | [
false
] | Is this a physiological effect? Or have we had to pee the entire time, and the emotions just make us realize it faster? | [
"Your sympathetic autonomic nervous system (responsible for triggering the \"flight or fight\" response) is triggered by stressors. The neurotransmitter Norepinephrine is released, which causes a number of physiological reactions, among them increased heart-rate, respiration, inhibition of digestion, and relaxatio... | [
"Could you cite your evidence that strong emotions such as excitement and fear increase the urge to pee. To my knowledge activation of the sympathetic nervous system inhibits one's ability to voluntarily urinate."
] | [
"Great response, Thanks. I had no idea excitement triggered a fight or flight response."
] |
[
"If a human body suddenly got sucked up into outer space what would happen to the human body? Why wouldn’t humans flash freeze?"
] | [
false
] | null | [
"I'll answer the second part: a human wouldn't flash-freeze because a vacuum is an extremely good insulator. On a human scale, the thin gas of interplanetary space is so thin that it doesn't really have any temperature at all. There's no convection or conduction of heat out of your body. Instead, there's only radia... | [
"Remember, the amount of pressure your internals pushing outwards on your surface is 1 atm, as our bodies are conditions to live at that pressure.\nThe equivalent would be diving to a depth of 10m in water, where the pressure is 2atm, or an increase of 1 pushing in. You hardly think we’d be crushed at that depth. W... | [
"My favorite part is that due to the low pressure, the moisture on your skin will start to boil, and so will all other fluids in your body that isn't being contained."
] |
[
"Are the 'movable ribs' possessed by Draco volans, (the Flying Dragon), which form its 'wings', considered limbs/appendages?"
] | [
false
] | It consists of bone, presumably muscle to move the bones, and is joined in some way to the spine; what is the nature of this join, is it considered a joint? If I have misunderstood Draco volans' anatomy, and its 'wings' are not movable appendages, do they have the capacity to evolve into limbs or more recognisable wings? Thanks. I'm fascinated by this little critter, what looks like a six limbed vertebrate. | [
"Interesting creature. I imagine you will get some discussion if your post to ",
"r/biology"
] | [
"I'll try there too, thanks.",
"http://www.reddit.com/r/biology/comments/vitsu/are_the_movable_ribs_possessed_by_draco_volans/"
] | [
"No, they're not considered limbs, even though they're jointed. The vertebrate skeleton is divided into ",
"2 main parts",
": the axial skeleton (skull, spinal column, ribs) that composes the primary body axis, and appendicular skeleton (shoulder blades, pelvis, and limbs): bones that are 'draped over' or 'hung... |
[
"Do other types of electromagnetic radiation 'shine' or propagate similar to how visible light does, with shadows, reflections and varying degrees of coherence?"
] | [
false
] | [deleted] | [
"Absolutely. X-ray lasers exist. I work at a facility which has one. The same rules of diffraction, refraction, reflection apply. As my old physics prof used to say, light is light is light. ",
"The really neat thing I like to think about is what it would be like if I could see in the radio spectrum. I think radi... | [
"Yes actually. Any wave is subject to reflections. You'll get 'shadows' of UV light when you wear clothing hence why you get sunburned worse on unprotected areas and reflections of UV off of water can also cause burns (though to much less a degree). Coherence of light depends on the bandwidth of the light leaving t... | [
"If you've ever received a bad sunburn in a snowy environment, you've seen one example. Ultraviolet radiation can reflect off of snow, and you can actually get an even worse sunburn during a day in the snow than you would at the beach."
] |
[
"I've got contacts that are rated for 2 weeks to a month. Now I've been really careful with them, but they haven't gotten uncomfortable at all. Can I keep wearing them past 1 month if they still feel good? (I take them out every night and put them in every morning)"
] | [
false
] | null | [
"I've got Acuvue Oasys Lenses haha."
] | [
"So, first of all you should always follow the products directions. ",
"On the other hand, I was sentenced to a year in prison in 2006 and am blind as fuck. I somehow got through the fishtank without being noticed and wore them for a FUCKING YEAR!!! No contact solution or anything. My prescription is around a (-1... | [
"I have worn contacts for over 10 years and I always wear mine way past the recommended time frame. As long as they still feel comfortable I wear them. I have never had any consequences from it. No infections and my eyesight has not worsened any more than expected. Actually my eyes haven't gotten worse in 2 years."... |
[
"How does navigating by Stars work?"
] | [
false
] | I know that in ye old times, a lot of sailors navigated with the stars. How does that work when the stars move in the sky depending on the time of night and the day of the year? I know that the North Star is a thing to help, but how can only one star be the tool for navigating the ocean? And how did people do it in the Southern Hemisphere, without the help of the North Star? | [
"Knowing your latitude is easy. It's equal to the angle between the celestial pole and the horizon. That's why Polaris is important, it's almost on the north celestial pole. In the southern hemisphere, you can use other stars that are close to the south celestial pole like Sigma Octantis, or you can use any other s... | [
"I know that in ye old times, ",
"Navigating by the stars was routinely done on airliners right up until the 60's. The first versions of the Boeing 747 were fitted with a sextant for taking star-shots (it somewhat resembled a small periscope in the roof of the cockpit). ",
"The US Naval Academy stopped teaching... | [
"We have 4 satellite positioning systems that work worldwide, use reasonably simple local equipment (battery-powered devices) and don't emit signals that can be tracked.",
"I would expect that a smartphone app can do celestial navigation today. It has a clock, it has an orientation sensor and it has a camera. It'... |
[
"Why do the Planetes orbit the Sun?"
] | [
false
] | null | [
"The solar system would have formed in a nebula. It's likely that the nebula would have been slowly spinning. As gravity contracts the gas cloud, conservation of angular momentum makes it spin faster (try sitting on an office chair and spin with your legs out, then pull them in. You'll start spinning much faster)."... | [
"And why did the gas rotate?",
"Excuse me, I just answered that in the text above. I'll try again.",
"The gas would be in motion already. Very few things in the universe stand completely still, due to the force of explosion of an older generation of star, gravitational effects, expansion due to heat, etc. There... | [
"Well, that's where the original energy comes from, yes. They revolve around the sun at the speeds they do because of conservation of angular momentum as the proto-solar-system cloud collapses and condenses, and they rotate around their axes for the same reason: small forces that add together and amplify each other... |
[
"What was the weather/climate like during Pangea?"
] | [
false
] | What was the general climate during Pangea? Were there seasons? I understand it was cold on the poles but what about the equator? What about the Terrain was it completely desolate and like a dessert, a rainforest or were there mountains and constant volcanic activity? | [
"Seasons have more to do with tilt than continental arrangement, so there should have still been seasons. In general, the climate would have been a lot like Asia, except more so. Around the edges it would have been similar to any other continent, with ecosystem type dependent on latitude and weather patterns. De... | [
"I'm really interested in that huge ocean. What was that like? Were there massive hurricanes? What about rouge waves? What kind of life could be found in the center?"
] | [
"Our own continents are moving as we speak. These things take millions of years."
] |
[
"Where are a whale's nipples?"
] | [
false
] | Whales, as mammals should have nipples, correct? or do they have some other structure to deliver milk from the mammary glands? do male whales also have nipples? where are whale nipples located? how do whales "suckle" if they have no lips to create suction on the nipple? -thanks :) | [
"Right here",
"Additional chart",
"Another photo, the two slits beside their urogenital slit."
] | [
"They are located in slits on either side of their urogenital slit. Whales and dolphins (I am pretty sure this includes all species) have a similar setup for the genders. Because it's all tucked up inside for hydrodynamics, a male has what is basically an 'exclamation point' (two lines in line with each other, one ... | [
"From what I recall , there is a difference depending on species and sometimes even sex of the animal.",
"Here's",
" a diagram showing sex-linked differences in size and position in Orcas."
] |
[
"How does one plant a seedless watermelon?"
] | [
false
] | From what kind of seed do seedless watermelons grow? | [
"They take clippings from a living plant and grow those."
] | [
"You sure about that? I figured it'd be like bananas where you breed an infertile triploid hybrid, which sort of ",
" like a switch..."
] | [
"Never feel bad for trying to acquire knowledge. It is the journey, not the destination, that is important."
] |
[
"How was the sediment that forms the rocky planets formed?"
] | [
false
] | Where did the rocks that make up the Earth, Mars, Venus etc. come from? | [
"http://www.theguardian.com/science/2008/apr/28/starsgalaxiesandplanets.geology",
" has the best explanation I've come across.",
"tldr: Tiny particles from the big bang/dead stars keep smacking together until they have enough mass that their gravity starts pulling this dust together and become bigger. Eventuall... | [
"Which dust are you referring to not knowing where it came from?"
] | [
"Most of the heavy atoms, like carbon and nitrogen, that make up the rocky planets and all life on Earth, were made in stars. In the beginning of the Universe, there was only hydrogen, helium, and a trace amount of heavy elements - everything else was made later in stars.",
"When stars die, they eject their mater... |
[
"Can some humans see different wavelengths of light?"
] | [
false
] | I know the visible spectrum is from about 390-750 nm, but are there any reported cases of people with genetic variations out there that allow them to see lower or higher frequencies of light, like maybe 350 or 800 nm? I know there wouldn't be much of a difference in what they saw, but it was just a question that popped into my head. | [
"There are genetic variations in the color opsins that shift their frequencies, but the shift is much less than what you describe especially towards the ends of the absorption spectrums.",
"Look at this graph"
] | [
"There is some speculation and evidence that some humans may be able to see colour differently:",
"http://en.wikipedia.org/wiki/Tetrachromacy"
] | [
"apparently they see uv lights as a new kind of violet - it's just like\nseeing violet, but different"
] |
[
"Why can't computer RAM be phased out and replaced with larger CPU caches?"
] | [
false
] | I have a basic understanding of the hit or miss principle. . If the CPU can communicate with cache several times faster than RAM, will we eventually see a shift to gigabyte-sized CPU cache and removal of "the middle man" that is RAM? And further down the road, we won't need a separate hard drive at all when the CPU can link directly with the memory and that memory can be large enough to suit our storage needs. Is this at all plausible? | [
"Part of it comes down to cost. CPU cache memory is extremely expensive to manufacture in comparison to RAM, which is extremely expensive to manufacture in comparison to storage media like HDDs/SSDs. Then there's the logistics of fitting all that memory on the die of the CPU. Part of the reason why CPU cache memory... | [
"Even if cost was not an issue (as ",
"/u/rmg22893",
" pointed out), we couldn't even come close to fitting gigabytes of cache on a CPU with current technology. As ",
"this image",
" shows, L3 cache is already takes up a huge part of the Core i7 CPU die, and what you're seeing there is only about ",
" 15... | [
"Sandy Bridge E has 15 MB of L3 cache right there on that picture. Just pointing out, otherwise great answer."
] |
[
"Why do \"naturopaths\" use Litmus tests with urine to determine your overall health?"
] | [
false
] | Does it have any meaning at all or just a gimmick? I am majoring in Nutrition with intentions of becoming a Registered Dietitian. I understand that the body has a protein buffer and also the H-H equation and that the body compensates for pH by fluctuating carbon dioxide levels (through respiration). I'm curious why it's "better" to be alkali than acidic - don't we want to be neutral? | [
"Because they don't know how to practice real medicine"
] | [
"Do you know what a naturopath is? ",
"Here",
". Their techniques are not based on evidence, and their model of disease is incompatible with what we know about physiology."
] | [
"Stay in school, you are doing it right."
] |
[
"How have oxygen levels affected evolution in the past and do they apply in any evolutionary terms today? The future?"
] | [
false
] | null | [
"Yes actually. Earth was originally lacking in O2, and the first forms of life were anaerobic organisms. Eventually, oxygenic photosynthesis was evolved, which produced O2. This increased the atmospheric oxygen concentration. The interesting thing about aerobic respiration (using oxygen in energy production), is th... | [
"They definitely apply today. \"During the Carboniferous and Permian periods, atmospheric oxygen concentrations were significantly higher than they are today. Prehistoric insects breathed air that was 31-35% oxygen, as compared to just 21% oxygen in the air you're breathing as you read this. Atmospheric oxygen is t... | [
"so if aliens evolved in 50% oxygen earth similar to ours, they would think dinosaurs were lizards? (I know once the oxygen levels are high enough, the first asteroid that entered its atmosphere would have cause it to ignite)"
] |
[
"Do cousins whose parents are identical twins have the same genes as siblings?"
] | [
false
] | null | [
"If two identical males married females who were also identical twins?",
"Each child has 50% of the combined DNA of it's parents. Each child gets 50% from one and 50% from the other. Due to the number of chromosomes, chance mutations, and a phenomenon known as 'crossing over', there is effectively no limit to the... | [
"Sorry, no I mean if two identical twin brothers had offspring with two different woman, if the children would have the same DNA as if they were fathered by the same parents."
] | [
"Checking for clarification, is this what you're trying to ask?",
"A pair of identical brothers marries a pair of identical sisters. Each couple produces offspring. Is the level of genetic correlation between these offspring the same as the level of genetic correlation between siblings?"
] |
[
"How do magnets get their magnetic fields? How do electrons get their electric fields? How do these even get their force fields in the first place?"
] | [
false
] | null | [
"Electrons have a fundamental property called the quantum mechanical spin. This spin can be understood and described as an intrinsic angular momentum.",
"The spin creates a magnetic dipole moment with a certain magnitude. In non-interacting electrons, these dipole moments are randomly oriented such that in averag... | [
"This ",
"minutephysics",
" video illustrates some of these ideas pretty well, I think."
] | [
"Each electron fundamentally has its own intrinsic dipole moment. Then the electrons and nuclei combine to form atoms, which have some total dipole moment.",
"Then many atoms assemble into a macroscopic piece of material. In a ferromagnetic material, neighboring magnetic dipoles interact strongly with each other ... |
[
"Why isn't the Program Counter / Instruction Pointer register directly exposed?"
] | [
false
] | Why isn't the Program Counter / Instruction Pointer directly exposed like the other registers? Wouldn't that make direct and relative branches/jumps possible by writing directly a value to it or add/subtract from it, without the need to have extra opcodes for unconditional branches/jumps? Would it help the compiler to have all the possibilities of the ALU to create more efficient ways of program flow? Additional Question: Would it be useful to have an opcode that causes the content of a register to be used as the next instruction? (didn't System/360 have something like that?) | [
"Two thoughts come to mind:",
"jmp *%eax"
] | [
"If you look at the way that most ISAs are designed, you'll see that store opcodes typically reserve some number of bits in the opcode to designate the target register. For example, 0x1001 might mean \"store in R1\" and 0x1002 might mean \"store in R2\". ",
"If you change your ISA to treat PC as another general-p... | [
"Yes, I would agree with this. I think the OP however is asking why it isn't possible to do something like PC = ADD(R1,R2) or something. And the fact is, some ISA have that ability. But more importantly, doing that would make the pipeline more complicated. As it stands we have stages of the pipeline and each stage ... |
[
"Why are diamagnetic substances weakly repelled by magnets?"
] | [
false
] | null | [
"Because when a diamagnetic material is held in an external magnetic field, a magnetic field is induced inside the material which opposes the external field. See ",
"this picture",
"."
] | [
"This picture is also instructive. Inside a diamagnet, the flux density is decreased: ",
"https://commons.wikimedia.org/wiki/File:Magnetic_Permeability-no-caption.gif"
] | [
"Just to be sure, this is why soda cans slightly move when a strong magnet is moved near it, right?"
] |
[
"[Astrophysics] How is it that the scattered matter of the \"big bang\" isn't an even spread across our cosmos and instead, we have enormous stars, small stars, humongous galaxies, and unfathomable voids between galaxies?"
] | [
false
] | null | [
"It is evenly spread, on very large scales (measured in the hundreds of millions of light years). All the structure on smaller scales is the result of slight variations in density (about 1 part in 100,000) in the early universe, which have since grown through gravitational attraction.",
"edit: clarified scale of ... | [
"LSS does not extend to arbitrarily large scales - again, there's a certain length scale beyond which homogeneity sets in. You can see this visually in ",
"maps of LSS from numerical simulations",
", and it is also apparent from observational measurements e.g. of the ",
"galaxy correlation function",
", whi... | [
"There are superclusters and supervoids, yes, but there aren't any structures larger than that - there are no \"super-super-clusters\".",
"So if you compare two different regions of space each big enough to contain many superclusters/voids, they will look very similar."
] |
[
"Could negative energy scalar fields be involved in spontaneous symmetry breaking?"
] | [
false
] | null | [
"What do you mean as the energy level of the field?"
] | [
"Are you referring to the ground state energy? The ground state energy can be negative in a QFT. But in a pure QFT context, this is a little ambiguous because the ground state energy needs to be renormalized. This is further complicated by the fact that it is not really an observable in a QFT unless you consider qu... | [
"I suppose my question now is can a gauge field have a \"negative\" energy or is this restricted to gravity. I was assuming that the energy value in take for example ",
"The Mexican Hat Potential Figure",
" is how high or low the scalar field. But my question would be void if there is no such thing as \"negativ... |
[
"How do celestial bodies become tidally locked?"
] | [
false
] | null | [
"As they spin the side closest to the source of gravity gets slightly pulled towards the middle more than the other side elongating it slightly, as it spins the elongated side keeps changing slowing the spinning until one side stays constantly facing the centre "
] | [
"Cheers very much, nice concise explanation 😊 So, is it essentially friction that brings the orbital and rotational periods into sync? And what happens to the angular momentum?"
] | [
"Consider a body b1 of mass M1 with some body b2 of mass M2 orbiting it where M1 > M2. b1 will raise a tidally excited bulge that when ignoring orbital motion will align with the line of centres between the two bodies. When we consider orbital and spin motion of the body then as long as there is a mismatch between ... |
[
"We recently named elements 114 and 116. Has research begun on finding elements over 118?"
] | [
false
] | null | [
"It's not so much finding as inventing."
] | [
"For those that don't get it, the newest elements have been named those funny words for simplicity's sake. The newest elements have been being simply named things like Ununtrium (113-ium) and Ununpentium(115-ium) until such time as international committees can decide on what the new names will be.",
"TL;DR They h... | [
"Great point. It's not like these scientists are busting out microscopes hoping to find deposits in a mine.",
"They discover them by smashing atoms together and hoping for a new one."
] |
[
"Is there a limit to the number of immunity genes bacteria can carry?"
] | [
false
] | Is there a limit to the genome size of bacteria that carry immunities for agents such as penicillin? In other words, if mankind continues to develop anti-bacterial drugs, will strains of bacteria be able to continue evolving immunity genes? | [
"Now theoretically, there must be a physical limit to the quantity of DNA that can be present in a typically sized bacterial cell (or any cell, for that matter). However, realistically it's probably never ever going to occur, due to the huge, vast quantities of DNA that can fit in one cell. The ameboid Polychaos du... | [
"Maybe is the correct term to use! Now I have no idea how long it would take for a gene to be lost from a single bacterial line without any selection pressure, but it would probably be quite a long time. But even if you stopped using the antibiotic for a very long time, as soon as you start using it again, you woul... | [
"Maybe is the correct term to use! Now I have no idea how long it would take for a gene to be lost from a single bacterial line without any selection pressure, but it would probably be quite a long time. But even if you stopped using the antibiotic for a very long time, as soon as you start using it again, you woul... |
[
"Is it rough underwater for fish while a storm is making the ocean surface choppy with big waves?"
] | [
false
] | null | [
"The first few feet are choppy and jerky then its much calmer. I don’t know the ratio, but based on wave turbulence, a 3 foot wave creates 1-2 foot of under current. Most fish are well below the disturbance is my guess. "
] | [
"A particle in the water at the surface moves in an orbit in response to any waves. At the surface, the diameter of this orbital path is equal to the height of the wave, but as you say this rapidly drops off. Orbits decrease in size until the motion is essentially gone at a depth equal to half the wavelength. "
] | [
"From my own experience it can be a bit more at the coast, i often had quite strong wave currents at 3m depth with waves that were a lot smaller. But maybe that has to do with the waves being pushed up against the coast."
] |
[
"If you dug a hole straight down to the other side of the earth, what would happen if you dropped something through it?"
] | [
false
] | This is pretending there’s no core or anything of that matter that would effect it. How would gravity effect it? What would happen? Would it get stuck in the middle, would it gain enough velocity to shoot out the other side? | [
"The object would accelerate towards the core. Once at the core, there is no gravity, so the speed of the object doesn't change at the core. So the object will shoot straight through towards the other side.",
"If there is no air resistance, the object will make it to approximately the same height that it was drop... | [
"To add one variable, would the earth’s rotation interfere? I’m having trouble getting my head around this. It seems that the nut (I’m imagining a knuckle-sized hex bolt) would be continue in a “westerly” direction as does the earth’s surface. So would it bonk onto the edge at some point since it isn’t pinned down ... | [
"To add one variable, would the earth’s rotation interfere? \nI’m having trouble getting my head around this. It seems that the nut (I’m imagining a knuckle-sized hex bolt) would be continue in a “westerly” direction as does the earth’s surface.\nSo would it bonk onto the edge at some point since it isn’t pinned do... |
[
"How was Fermat's Last Theorem eventually proved?"
] | [
false
] | I am more looking for an overview than an in-depth answer, as I know its extremely complicated. | [
" A nontrivial solution to a",
"+b",
"=c",
" in the integers would require some seriously exotic arithmetic objects. We (Wiles) proved that such objects do not exist.",
"I'm going to go a little crazy. I'm not going to go into mathematical detail or anything, more of give an overview and tell aspects of the... | [
"This is where Wiles comes in to the story. He needed to prove the Taniyama-Shimura Conjecture, which says that for every elliptic curve, there is an associated modular form that contains the same information as it. I'm going to try to explain the basics of his approach in an approachable way that isn't incorrect. ... | [
"If you don't feel comfortable with actually doing math problems and just want more of the story, then ",
"Fermat's Enigma",
" is great.",
"If you haven't really done advanced math (in this context, Calc1-3, Diffeq and Linear Algebra are not advanced), but are comfortable with equations and manipulations and ... |
[
"Would it be possible to create a device to generate darkness?"
] | [
false
] | Inspired by a bit in a kid's show my son watches, would it be possible to create a device to generate darkness? Imagine turning on a lightbulb but it instead shrouds the area in darkness. Is such a thing possible? | [
"Not really. Darkness isn't a substance that we can create, it is just a lack of light. In order to pull the light in a direction it wouldn't otherwise go you would need essentially a black hole, not something we can build and market very well.",
"Taking a different approach, something like a smoke bomb could p... | [
"I think those are called curtains. :)",
"Though something like that might be possible, but it would involve basically getting something to remove the light from a room (by absorption for instance). Though you might have other unsavory effects since that energy has to go somewhere which usually means it gets re... | [
"I would think it might also be feasible to create something that temporarily interferes with the signals of the optic nerve or the visual cortex. No need to eradicate photons if the people around can't detect them. Going off on a total sci fi tangent, that could be useful in a tactical situation, especially if the... |
[
"How does fire act in very high pressures?"
] | [
false
] | For example fire in a room with 100 times athmospheric pressure. | [
"You know this is pretty interesting question I would say. You know how some gunpowder burn slowly when placed in ground as a single line? Same amount of gunpowder in a chamber bullet blocking the escape route of the expanding gasses from burning and you get a big boom. Same thing with engines. Fuel air mixture bur... | [
"Based on testing that I have seen and done in ~2atm of pressure, yes the fire gets brighter, as long as there is a continual supply of fuel and oxygen. It acts similar when you fan a fire to stoke it. The fire burns larger and brighter"
] | [
"This is the basis for how rocket engines work. There is an equation which gives the burn rate as a function of pressure; every fuel has a particular burn rate coefficient and exponent that go into this equation. At 1 atmosphere, things burn relatively slowly. When you turn up the pressure, the burn rate increases ... |
[
"What does it take to be considered a scientist."
] | [
false
] | null | [
"You have to be actively advancing knowledge of a particular field. So engineers and lab techs generally aren't scientists, although those are perfectly respectable careers."
] | [
"Thanks, would you say a layman testing a theory could be considered a scientist then? \nAs a business major that loves science just curious as how I can contribute."
] | [
"To be perfectly honest, it's such a specialized and technical field that it would be extremely difficult for anyone to contribute on a part-time basis."
] |
[
"Due to loss of mass via hawking radiation, could there be a black hole that has an escape velocity below the speed of light, thus visible? (Physics)"
] | [
false
] | null | [
"Then it wouldn't be black, would it? :) Hawking radiation reduces a black hole's mass. So the event horizon - the point where the escape velocity is the speed of light - is still there, it's just closer to the center of the black hole."
] | [
"Short answer is that we don't know.",
"I believe the current leading theory is that it will evaporate away to nothing with a massive burst of energy in the last few milliseconds. ",
"But some predict there could be some subatomic remnant left. What that remnant is is anyone's guess. Some predict it would be a ... | [
"No, he means one with the MASS of the moon. The event horizon of that black hole would be roughly the size of a grain of sand."
] |
[
"Does time reverse beneath the event horizon of a black hole?"
] | [
false
] | Does time reverse? If time accelerates to infinity as you approach the event horizon of a black hole, if you move beneath the event horizon, would math break down at infinity and begin reversing as some sort of law of physics? If inside this sphere, time were reversing and accelerating towards infinity, would the center represent the exact beginning of the black hole's little bubble universe? If time doesn't snap and reverse at infinity, could matter even enter a black hole without becoming trapped inside an infinite time dilation? | [
"If time accelerates to infinity as you approach the event horizon of a black hole, if you move beneath the event horizon, would math break down at infinity and begin reversing as some sort of law of physics?",
"No. The math does break down in ",
"Schwarzschild coordinates",
" along with a few other coordinat... | [
"Theoretical physics and physicists are important, and at least some 'armchair physicists' are in a state of trying to improve their understanding of those theories by trying to retell them to others. But yeah, generally it seems like they are talking out of their asses.",
"You have to go down that theoretical ph... | [
"Straightforward, practical answer: we don't know. Currently, I don't think we can know because we can't gain information from inside a black hole. There are lots of complex mathematical and theoretical physical theories that may or may not explain what happens inside a black hole, and without evidence from inside ... |
[
"Is there anything actually orbiting the sun along its North/South axis in our solar system?"
] | [
false
] | Obviously all of the planets in our solar system orbit along a somewhat flat plane (although I’d be curious to know how much distance there is between the “lowest” and “highest” planets). But given the sheer size of the solar system it’s seems absurd to me that there isn’t at least some material orbiting perpendicular to the majority of the mass. So is there anything at all orbiting in that axis? | [
"It is theorized there is Oort cloud out there, beyond the heliopause. It is suggested to consist of small icy objects forming a sphere around the Sun. Also, it is believed to be the source of comets. But since all those objects are very far and do not emit light themselves nobody on Earth has seen them."
] | [
"There are objects out there with odd orbits, but generally everything is nearly along a flat plane because of the conservation of angular momentum. Given enough time, every direction but one sort of cancels out. Objects near the sun that violate this general rule were disturbed from their previous orbit, and objec... | [
"As you said, most of the planets are very close to a plane. ",
"Wikipedia has a list of their inclinations.",
" Planets make up most of the mass of the solar system (after the Sun, of course). So anything beyond that will be very small objects such as comets or asteroids.",
"Anyway, yes, there are a few aste... |
[
"If an ape is \"genetically identical over 98%\" what does this exactly mean?"
] | [
false
] | I have not studied biology in high school and I've just become really interested in the study of evolution and biology and I have difficulties grasping this "gene similarity" concept. I know, for instance, that genetically, gorilla's are about 98% the same as us but I find it hard to understand this. If this similarity is this immense, why do they look, behave and think so different than us? I hope someone can answer this. Thanks a lot! | [
"It's not a very meaningful number. 98% ",
" like a lot, but it's not. We've got over 70% of genes in common with a sea sponge. And a significant amount in common with ",
" life form. ",
"These big differences in visible, macroscopic changes don't correspond to equally big changes at the microscopic level. At... | [
"I support the above answer.",
"The thing to think about here is that all (well, almost all) life forms have to do the same things metabolically: break down and build up fats, proteins, and carbohydrates. So the enzymes are often very similar because the tasks are similar. The differences in the genome are relate... | [
"If you take all of the DNA base pairs in humans and compare them to gorillas, 98% will be identical in the same location. ",
"As Platypuskeeper pointed out, this number isn't terribly useful because it's more important which genes are changing, not really how many total have changed. We look absolutely nothing l... |
[
"To what level can parasympathetic systems 'learn' or be influenced by things like psychological stimuli? (If I only Reddit while I go to the bathroom, will my body 'want' to go to the bathroom more often?)"
] | [
false
] | I guess my specific question is: To what level, if any, can an external (psychological?) stimulus affect a parasympathetic system (in this case, bowel movements)? Will my body make me want to poop more often so it can get its 'reddit fix'? I'd like to control my use of Reddit a little more, and one easy way to seems to be to limit myself to reading my frontpage only during the times I am using the restroom, because I don't control exactly when my body 'needs' to go. But then I got thinking, 'Maybe that would cause some issue where my body 'wants' to go more often', kind of like a learned behavior. To what level can parasympathetic systems 'learn' or be influenced by things like psychological stimuli? | [
"From a psychological standpoint, assuming Reddit is a significant reward to you (meaning something that you enjoy enough to seek out) then what is likely to happen is that your threshold for deciding when you need to use the bathroom will lower. ",
"In other words, if today your bathroom habits are \"I only use ... | [
"This also has some very interesting links to drug addiction, resistance, and withdraws. There was a study with rats, where two rats were hooked up to heroin pumps. One rat had a button that activated both pumps, so it \"knew\" when to expect a dose of the drug. The second rat had no reliable signals of when it wo... | [
"Thank-you both for the detailed information, and the follow-up."
] |
[
"If the strength of an acid is based on concentration, why are acids like Sulfuric Acid always considered so dangerous compared to others?"
] | [
false
] | I was in a lap and we were working with acetic acid (vinegar) and it was highly concentrated. This idiot says something along the lines of Vinegar aint dangerous and takes a sip. I then watched him spit out his gums. Why is it that acids like Sulfuric, Nitic, etc are always portrayed as these ultimately corrosive substances despite concentration? Is there something to these "famous" acids that make them more deadly? And arent bases scarier to spill on you? | [
"Well some factors are:",
"A) For same concentrations, some acids are way stronger than others because they give away their protons much more easily.",
"B) Acids like sulfuric acid can “donate“ multiple protons per acid-molecule giving it more potential to turn solutions acidic.",
"But as you already noticed ... | [
"One thing not mentioned yet is that how \"dangerous\" an acid is can also depend on chemical properties unrelated to acidity. Hydroflouric acid for example is a powerful poison and sulfuric acid extremely hygroscopic, two properties which make those acids risky to work with. There is no one factor all \"famous\" a... | [
"Since another poster already answered most of this I won't repeat them. ",
"To answer your final question, I'm not sure that they are necessarily \"scarier\" so much as equally horrifying. ",
"It's like asking if you prefer to be lit on fire with gasoline or on a stake, is one really that much better in the en... |
[
"What is actually doing the work?"
] | [
false
] | It is something you learn very early on in physics that magnetic fields do no work due to a cross product being involved. However, in the case when you take a magnet, and lower it slowly down to a magnetic piece of metal, and it suddenly flies up and attached itself to the magnet, what is actually doing the work against gravity to raise it? Or is the whole "magnetic fields do no work thing" not the whole story that I should have learned before getting my degree... | [
"On an atomic level, electrons spinning or orbiting is what causes the magnetic field to work. The grand mystery you are asking, or perhaps trying to get to the fundamental nature of is where does the energy whichh is posessed by subatomic level come from? Not a physicist here but i got a couple of them to talk ab... | [
"Yes, I am familiar with where the magnetic fields come from, but I am asking exactly what is pulling against gravity since I have learned in 4 years of physics courses that magnetic fields ",
"do no work."
] | [
"Since the magnetic force from the magnet and the piece of the metal is the same. Without your intervention the magnet would also be pulled down to the metal. So, is the work to lift the metal piece up to the magnet being done by you, when you hold the magnet preventing it from being pulled down to the metal piec... |
[
"What kind of balance system do insects use?"
] | [
false
] | null | [
"I believe the OP was asking about the sense of balance or equilibrioception in insects, not fluid balance.",
"Most flying insects have what is called a ",
"Johnston's organ",
" as part of their antennae which I believe acts as a sort of 3D accelerometer. This tells them which way gravity is pulling, as well ... | [
"Some insects instead use ",
"halteres",
", which are basically dummy wings that flap along with the real wings. When the insect changes its flight path, these structures try to keep vibrating in the same plane. This leads to Coriolis acceleration, which creates a force that is sensed by structures at the base ... | [
"Thank-you very much :D"
] |
[
"Why does blue seem to be the hardest color to achieve for so many things, such as LEDs, fireworks, and paints or dyes?"
] | [
false
] | What makes blue special? Also what category would this be? | [
"Not an answer but blue is the shortest wavelength and therefore the highest energy of the visible spectrum. And higher energy is harder all around to deal with. For example, 7,000 kelvin light bulbs emit a lot of blue spectrum and many people find them to be burning and fatiguing of their vision. Another example i... | [
"Blue LEDs came along after red, yellow and green, but today white LEDs use a blue LED plus phosphors to make red and green. So production of blue LEDs is commonplace if not exactly \"easy\". ",
"Deep blue fireworks are difficult because the burning copper compounds don't emit only blue. They emit blackbody radia... | [
"The sky looks blue because of the Rayleigh effect, which is where the light scatters from the atmosphere. The shortest wave we can see is blue. ",
"Same thing happens in people with blue eyes. They don't actually have melanin in their irises, so the Rayleigh effect makes 'em blue. "
] |
[
"What is the (non-aesthetic) purpose of a gradient on the edge of an automobile windshield?"
] | [
false
] | I've read that it has something to do with tinting and preventing the edges from going yellow. If this is true how does it prevent it? Additionally, are windows still produced with gradients or has a new, better method been put into practice? | [
"Reduce sun glare"
] | [
"And some cars have a black fringe around the edges. That's for aesthetics to hide the adhesive on cars without molding."
] | [
"Visual Aid",
"Are we discussing the black that goes the whole way around, or the blue that's at the very top?"
] |
[
"How do painkillers work on a cellular level?"
] | [
false
] | I am interested in how painkillers work to essentially kill pain. I take an advil, this gets dissolved by my saliva and stomach acids. The chemical(s) infused in the drug get transported in my bloodstream to all parts of my body. I assume then that this chemical (drug) binds to certain cells where the pain is emitted from. Is this only to nerve cells because that is where the pain signal is coming from correct? So this chemical (drug) will bind to nerve cells to block pain? What exactly is it binding to and for how long? Does this create changes within the cell simultaneously, for example would certain transcription factors be activated to yield the production of different proteins? So I guess I have a two part question: how does a drug (infused with a chemical) firstly accomplish its goal on a cellular level (in this case blocking pain), and by doing so does this affect the landscape of the intercellular environment - what does on inside the cell in anything when this chemical binds to the nerve cell to block pain. Thank you! | [
"It depends on the painkiller. Different classes of medication have different mechanisms of action- as another poster mentioned NSAIDs affect the COX pathway. Capsaicin as another example essentially depletes Substance P from the site of application, and Substance P is one of the molecules involved in the transmiss... | [
"Here's a ",
"paper",
" giving an overview of the alternatives to gate control theory -- specificity and intensity -- with pointers in the bibliography for going further down said rabbit hole."
] | [
"So, NSAIDs like ibuprofen are COX2 inhibitors. They don't really bind to the cells. They actually slow down the creation of cyclooxygenase which through a few chemical changes turns arachidonic acid into prostaglandin. Prostaglandin enzymes and COX both have functional roles in the pain pathway. Check out gate con... |
[
"50° Celcius is unbearable weather, but sitting in a tub of 50° water is relaxing. Why?"
] | [
false
] | [deleted] | [
"Water has high specific heat and efficiently conducts heat into your skin, so once you start going above 37C the warming effect is definitely perceptible and quite strong. Heating from water is so efficient that once you start going above 40C-50C it surpasses your body's ability to regulate its temperature. You'... | [
"Serious question-- then shouldn't it be comfortable to stand outside in 50c naked?"
] | [
"50",
" Celcius is ridiculously hot for bathing water. It would not be relaxing, it would be detrimental to health. i.e. Hyperthermia. You could last much longer in air of that temperature than water, so long as it was dry (e.g. desert) heat, with fewer ill effects."
] |
[
"Are there differences between species on the neurotransmitter levels?"
] | [
false
] | null | [
"Yes, there are. The example that comes to mind is the use of Octopamine in Drosophila neuro systems vs mammalian neuro systems. Octopamine is very important for Drosophila/invertebrate learning + memory, but not for mammalian learning + memory systems.",
"http://en.wikipedia.org/wiki/Octopamine"
] | [
"Sorry, completely forgot about this post, thanks for the info!"
] | [
"The most pronounced differences are between arthropods and other animals. Histamine is an important neurotransmitter in the sensory ",
"systems of insects",
" and plays a relatively minor role as a neurotransmitter in other animals. Also, the main excitatory neurotransmitter in mammals, birds, and reptiles is ... |
[
"What happens to bacteria when it is engulfed by a white t-cell?"
] | [
false
] | Once a white t-cell engulfs bacteria the bacteria "dies". What happens to the actual physical part of the bacteria? Is it expelled from the t-cell through diffusion? Just curious. Thanks in advance | [
"First of all you got some of your terms mixed up here. T-cells are more commonly called white blood cells, just like B-cells for example. So it is admittedly not wrong calling it a white T-cell but usually they are just called T-cells.",
"And at least to my knowledge, T-cells are not able to engulf/phagocytose a... | [
"The gamma-delta T-cell subset are capable of ",
"phagocytosis",
", but yes, conventional alpha-beta T-cells don't have that same ability."
] | [
"The process is called ",
"phagocytosis",
" and the compartment or vacuole that engulfs the bacterium fuses with an acidic vacuole called the ",
"lysosome",
" that contains enzymes that aid in the destruction of the bacterial cell. Certain cells such as macrophages, neutrophils, monocytes (which turn into m... |
[
"When it is cold outside, but not cold enough to get frostbite, are a person's extremities at risk of acute damage in any way?"
] | [
false
] | When my hands get cold and it's 0 to 10 C outside, what can happen? Is there any need to worry about temperatures like that besides eventual hypothermia? | [
"Isn't frostbite caused by cell damage when the water in the body freeze => crystalize?"
] | [
"I though windchill just increased the rate of heat loss but not the actual temperature, and therefor wouldn't cause freezing."
] | [
"I looked some stuff up, you are totally right, I should have looked these things up from the beginning because I clearly can't remember them right anymore, sorry, my mistake."
] |
[
"Reading recent articles, I get that we recently spotted the most distant/oldest galaxy ever, 13.4 billion light years away. With my understanding of the expansion of the universe, this galaxy was much closer to us than 13.4 bn ly, at the time it looked like what we see of it today. Am I correct ?"
] | [
false
] | What I understand is that in 13.4 bn years (close to the universe age) light travels 13.4 bn ly. But when photons left that galaxy to reach us, their "starting point", at that time, was closer to our today position than 13.4 bn ly. So, now, that galaxy is 13.4 bn ly away from us, but was closer then. What was the actual distance at that time? I am getting confused with articles I have read, mixing both (distance and elapsed time), but I may think I understand the expansion of the universe, while I actually do not. Please enlighten me. | [
"There are several ways to measure distances in cosmology. Unfortunately, the one that press releases seem to always use is the ",
" (LTD) and is arguably the worst and most misleading distance measure.",
"The LTD is defined as follows. Let t",
" be the time from today since the big bang (to be clear, this is... | [
"So you are on to a subtle point about distances.",
"As a photon is emitted from galaxy A and travels to us at B the distance increases.",
"When we say 13.4bn ly we mean the distance that the photon detected today has traveled is 13.4bn ly. 13.8bn ly as the size of the universe (radius) is the most common figur... | [
"This comes from a conflation of two terms, the universe as a whole and the observable universe. We normally just call both the universe. The observable universe has a distinct boundary."
] |
[
"~1% of smokers die from lung cancer. What accounts for rest of the smoking deaths?"
] | [
false
] | [deleted] | [
"I feel like you're missing something here: all of the causes of death in the graph seem to be because of cigarettes in some way.",
"Like, you might die from being shot, or you die from bacteria that entered your body with/because of the bullet, but you still died because you were shot..."
] | [
"~1% of smokers die from lung cancer",
"Where does that number come from? You quoted a study saying 1% is the lifetime risk for ",
"smokers to die from lung cancer. It also says, immediately before the part you quoted:",
"When expressed as cumulative probability rather than annual death rates, the cumulative ... | [
"I might be missing something myself, but I think the 1600 in 100,000 figure was just the rate of lung cancer deaths over the course of the NLST, which seems to have been 7 years (2002-2009). It looks like the number was primarily used to compare smokers to non-smokers over that timeframe, rather than being intend... |
[
"Medicine: At what point is your skin compromised opening yourself up to water born disease?"
] | [
false
] | Just having a discussion with a friend who insists a flesh wound cannot be infected by water, only a fully opened wound that goes through all the levels of the skin. Is he right? | [
"Any damage to the epidermis can increase the risk of infection. A cut or a scratch can be infected if it's deep enough to draw blood. Once the bacteria in the water enters the blood flow you are at risk. However, the deeper the cut, the greater the chance of infection since there are more defenses bypasses, and... | [
"Thank you for the well written answer"
] | [
"just to add on, when I say 'at risk' I don't mean 'OMG WERE ALL GONNA DIE', I mean it's a viable possibility. Most healthy immune systems can fight off the bacteria in water so long as the water is relatively clean. I've had plenty of cuts and scrapes while swimming and never suffered an infection."
] |
[
"Whitebread. Where did those nutrients go?"
] | [
false
] | refined foods always are said to be less nutritious. Where did they go? what is involved in the refinement process of foods that removes the good part. | [
"One class of nutrients that are particularly sensitive to processing are the ones we would consider anti-oxidants. That includes Vitamins A, C, D, E, and K, as well as other micronutrients. Using your example,during processing of wheat into Wonderbread flour, it undergoes processes of dehulling, grinding, bleach... | [
"The wheat germ is where most of the nutrients are, and they get stripped away during processing. I believe bleach or some other industrial chemicals are used to get the uniform white color. What results is that the processed bread becomes very easy for your body to digest because the fiber has been stripped out, s... | [
"It's got a nice and consistent taste and texture that people like. I love multi-grain bread, but some foods just go better with white bread. "
] |
[
"Why haven't we or why can't we domesticate bears?"
] | [
false
] | We've domesticated livestock, dogs, cats, etc. why can't I have a tame small bear as a pet? | [
"A few reasons"
] | [
"Something that didn't come up in the previous threads:",
"A bear is strong enough that even if totally friendly it could seriously hurt you by accident or in a brief moment of anger.",
"Surely many people have experienced a pet cat scratch your face or a pet dog grab your arm. Annoying but not a big deal. ... | [
"A brown bear can weigh upwards of 1,500 lbs. Even a playful swat could send you flying."
] |
[
"Are any of the large crater impacts (the ones that still have visible debris fields) more recent, e.g. modern times, or even within recorded history?"
] | [
false
] | There are some pretty bad ass crater impacts on the moon.. It's definitely taken its share of potshots... | [
"None of the large craters are from recent impacts. ",
"Here's",
" a nice table of craters, with size and age.",
"The ",
"Tunguska Event",
" is a popular recent event that happened just over a hundred years ago, and there's more information about recent impacts ",
"here",
".",
"Honestly, for this t... | [
"Meteor Crater is a meteorite impact crater approximately 43 miles (69 km) east of Flagstaff, near Winslow in the northern Arizona desert of the United States.",
"The crater was created about 50,000 years ago during the Pleistocene epoch ....",
"It was probably not inhabited by humans; the earliest confirmed re... | [
"Im not sure, but the Sudbury Impact Crater that created the melt sheet and the whole complex resulted in several shattercones as far as Duluth...",
"I think shattercones are the greatest thing in geology.",
"http://en.wikipedia.org/wiki/Shatter_cone"
] |
[
"Since the habitable zone around the sun only grows in diameter as the sun's size increases, how is it that Mars previously had Earth-like conditions?"
] | [
false
] | It's further from the sun, so I would have assumed that the habitable zone will move there eventually as the sun gets larger & hotter. But this states: The new findings, just published in the journal Geophysical Research Letters, provide evidence that early Mars was saturated with water, and that it’s atmosphere was at least 20 times thicker than it is now. What's the deal? | [
"So does that mean the habitable zone around the sun is larger than I am assuming, or that it was located in a different spot in the past. Or neither? "
] | [
"The habitable zone is still defined ",
"as follows",
". It doesn't necessarily have to do with which planets are habitable, it has to do with where liquid water could exist given certain circumstances. ",
"The habitable zone does not change with respect to planetary conditions, though it can change with resp... | [
"Okay awesome, thanks a lot. I thought the wikipedia article summed it up nicely:",
"Estimation of the Solar System's habitable zone is made difficult due to a number of factors. Although the aphelion of planet Venus and the complete orbits of The Moon, the planet Mars and dwarf planet Ceres are within the habita... |
[
"What makes some people have a better memory than others?"
] | [
false
] | null | [
"Everything here people said is right. The thing you have the most control over is the technique which you employ to memorize details. However, genetics can play a role in this. This ",
"study",
" suggests that hippocampus size, the part of your brain responsible for storing memory, can have a direct relationsh... | [
"You seem to be suggesting that hippocampus size is genetic and static. It's not. The brain is very plastic.",
"The famous study of London taxi drivers showed that they have considerably larger hippocampi than other people. The hippocampus, among other things, is very involved in spatial navigation, and this was ... | [
"People who engage in complex stimulus elaboration integrating new info with old remember better. The role of stimulus elaboration was shown clearly by Craik and Tulving way back in 1975 and numerous times since then. "
] |
[
"Can the US government make the big chain stores (Walmart target Lowe's etc) install solar farms on their store roofs?"
] | [
false
] | null | [
"Not a science question. Try a legal sub"
] | [
"First post. Thanks. Any recommendations?"
] | [
"No I'm not familiar with law subs... You could try googling around /seeing if ones with names you might expect exist and then see if they have others listed in their sidebar. ",
"/r/law",
" is probably a sub for example."
] |
[
"Tin cans and string: can the NSA intercept the message?"
] | [
false
] | null | [
"You could do it with a light sensor capable of detecting small movements of the string at about 6 kHz, which isn't impossible for an ambitious high-schooler."
] | [
"Hey, cool, I was one of those students! I remember it being a pain in the butt to get any sort of signal - we just barely got it to work in the last week of the class, and the sound quality was pretty bad. Basically the problem is that it's really sensitive to any small vibration or movement that's not part of the... | [
"Hey, cool, I was one of those students! I remember it being a pain in the butt to get any sort of signal - we just barely got it to work in the last week of the class, and the sound quality was pretty bad. Basically the problem is that it's really sensitive to any small vibration or movement that's not part of the... |
[
"Lack of a specific neuro-transmitter"
] | [
false
] | I am taking psychology at my high school and my teacher was discussing neuro-transmitters and then he said that a lack of a specific neuro-transmitter can cause depression and other mental sicknesses... He said this is common in teenagers and psychiatrists will sometimes prescribe medicine to get them back into balance... how accurate is this? | [
"I'd be surprised if there was a neurotransmitter that was completely \"lacked\" by a human being. Most neurotransmitters have far more than a single function, so if a person lacked one, I doubt they'd develop past very basic embryological stages. ",
"Cases of people who are thought to have ",
" (but still pres... | [
"sweet thank you... this kinda applies to me, so i was interested in this subject"
] | [
"The serotonin depletion or “not enough serotonin” leads to depression hypothesis is promoted by psychopharmaceutical companies and many physicians including psychiatrists. It has become, perhaps, one of the biggest modern myths in medicine; although a similar myth exists about the relationship between schizophren... |
[
"Answers to Vaccines? (serious answers only)"
] | [
false
] | Hello, . I am a father to be, yet unprepared for my child to be born in less than two months. This obviously revolves heavily around the issue of vaccinations. I'm wanting to clear the waters a bit so I can make a clear decision on my child's well being. I am other words asking for your help. I ask your patience with my responses, and take my inquiry as sincere and at face value. I'm just trying to understand what I admittedly do not fully comprehend. As of right now, I am at the beginning (only 15 pages...) of a book called "Deadly Choices" (a pro-vac book). I'm wanting to take all things into consideration. Below are a set of questions that I am trying to have answered, and in a way that I will understand. Why are there any chemicals (regardless of how safe they are) in vaccines? If a virus is already dead (thus a live sample not needed), can't the fluid simply be a saline solution or some other liquid that is void of (seemingly) unnecessary ingredients? Why was mercury ever used in vaccines in the past? Why are there actual cases where some people have incredibly adverse reactions to vaccines? Is it similar to how someone can be allergic to peanuts, but I'll be fine? With there being plenty of misinformation (perspective on where that lies), I can't make out what side is being honest about neurological development and cognitive impairment after a vaccination is given. Could someone help navigate this with me? Are there "natural" or "organic" (buzzwords) like vaccines? Meaning, vaccines that carry only the dead virus and an even more restrictive list of ingredients, even if I have to pay for it? If I decide in waiting to get vaccines for my child, what would be the latest age you would suggest? Being in the military, I've noticed that a rather large percentage of children that belong to military personnel have some type of minor or serious mental impairment, let alone physical. I finally researched the numbers a while back, and that number was actually affirmed (can't recall at the moment). Military members also have the highest rate of vaccinations for themselves AND their children. We're not talking about Agent Orange offspring, either. Now, as we know, correlation does not equal causation, but I find this correlation incredibly hard to ignore, and it freaks me out. Is there anyone who has more information about this, or the possible reasons associated? Please note that I will attempt to answer any questions that are asked honestly and with as much detail as possible. | [
"Chemicals are needed to stimulate the immune system and help \"present\" the vaccine to immune system in a way that will confer immunity. They are also needed to preserve the vaccine for storage and distribution as well as prevent things like bacterial contamination.",
"I believe you're talking about thiomersal... | [
"I'm a parent, too. I understand your need to examine everything. It's really your duty as a parent to make an honest assessment about how to best take care of your kids. And as a father, you tend to focus physical safety; preventing things that will harm their ability to reach their full potential.",
"So...your ... | [
"I'll piggyback onto your comment and address this question:",
"There are different variations of certain vaccines like those for the flu. Flumist is a live attenuated version of each strain predicted to be in circulation during the upcoming flu season, whereas the flu shot is a trivalent influenza subunit vaccin... |
[
"What causes nasal congestion and why can't you just blow your nose and be clear?"
] | [
false
] | Not much more I can think to add, pretty clear through title. Another question that came to mind on the topic though is, why is there usually one semi-clear nostril but it will sometimes switch sides? | [
"The clear-vs-congested nostril switching sides is due to the ",
"nasal cycle",
". The nasal cycle is not related to pathological nasal congestion, ie happens even when you are not sick.",
"Edit: why is this being downvoted? [was at -3 for a bit]"
] | [
"Not an expert on the matter, but usually it's not the actual mucus that causes the feeling of being stopped up. The irritation that causes the mucus also causes swelling in the nasal passages. The feeling where you can't seem to blow something out of your nose comes from that. If anyone else with more expertise ca... | [
"This is exactly right. When you get a decongestant at the pharmacy it is a drug that causes the blood vessels in your nose and sinuses to contract, lowering the swelling and clearing your nose.\nWe have a drug that thins mucus, Guaifenisin also called mucinex, it's great for if you are coughing up lots of phlegm (... |
[
"What happens when stars collide?"
] | [
false
] | [deleted] | [
"Fear not! The worst part about Wikipedia is that it's littered with articles that are either copy-and-pasted from other places, or just filled with links to sources that fall off the internet. This is one of them.",
"Blue stragglers are a real phenomenon, and explaining them as the result of a collision of two... | [
"It's very, very, very, very, very, very, very (I can keep going...) rare for one star to actually collide with another. It can happen more often in globular clusters, where the average stellar density is many more times than what we have in our little corner of the galaxy. That's where we see these \"blue stragg... | [
"When I see sentences like this on Wikipedia...",
"While much is unknown about this theory, there are new strides being made every day",
"I weep for the Wiki."
] |
[
"Could domesticated cats and dogs be considered a dependent species?"
] | [
false
] | If humanity were to disappear tomorrow without a trace, would cats and dogs be able to survive (and even thrive)? Would they be at a disadvantage to more feral creatures? I often see cats and dogs without a home able to survive near human habitats, but I never hear about them living in more wild environments. If they are at a significant disadvantage without humans, could that classify them as being dependent on us as a species? | [
"To answer your question, yes I think domesticated cats and dogs would thrive if humans were to be gone tomorrow and no I do not think of them as dependent on us. Cats and dogs survive very well without homes. Except for the animals at the zoo, which would have no way of getting out of their cages, cats and dogs wo... | [
"Disclosure- Just some amateur conjecture on my part",
"I think the answer is mixed, some breeds like Chihuahuas and poodles are obviously not going to do well on their own. ",
"On the other hand breeds that more closely resemble wolves will survive, they would probably be at a disadvantage when compared to coy... | [
"Dogs quickly revert back to the wild to form packs (actually they're always forming packs but never really 'hunt' in the pack) and the like when they're abandoned. Their hunting skills aren't as good as their ancestors, but they can survive. ",
"This is excepting the breeds we've fucked up in the process though... |
[
"Why does writhing help alleviate pain?"
] | [
false
] | I recently had a 24-hour stomach bug (or something with similar effects). My whole body, especially my stomach, ached and I was unable to get a restful sleep. During the night, I found that movement of any kind helped the pain go away a bit. Why is that? | [
"I am not aware of a specific mechanism involving writhing. I would expect that this is a specific manifestation of the ",
"Gate Control theory of pain",
", which says (sort of) that pain is not additive, but rather that neurons act like a pipe, and filling the pipe with non-pain sensations (or even just lower ... | [
"No. In a gate control model of acupuncture, any benefits would end soon after the acupuncture treatment was over, whereas acupuncturists typically claim that their treatments last a few days/weeks at a time.",
"Acupuncture ",
"is based off",
" the \"traditional\" notion that the body is operated by an energy... | [
"No. In a gate control model of acupuncture, any benefits would end soon after the acupuncture treatment was over, whereas acupuncturists typically claim that their treatments last a few days/weeks at a time.",
"Acupuncture ",
"is based off",
" the \"traditional\" notion that the body is operated by an energy... |
[
"If the universe is expanding at an accelerating rate, where exactly does that expansion happen? At the space between the atoms in my body, or somewhere else?"
] | [
false
] | null | [
"So we have two types of movement here. One is movement through space and the other is a stretching of the fabric of space itself. The common analogy is an ant on a rubber band. The ant walking on the band is traveling through space but stretching the band with an ant on either end will still result in them movi... | [
"The only place the stretching of space dominates so that objects on it are actually all moving away is at the super galactic cluster scale. These are the largest structures in the universe.",
"Ah! Something I can visualize. I was ready to ask a few questions with the ant analogy but given the scale of galactic c... | [
"Space is stretching evenly. Hubble's constant is 70(km/s)/Mpc. This means that if two points in space are 1Mpc apart, in 1 second they will be about 1Mpc+70km apart (slightly more as the distance between was increasing over that second). If there are two relatively stationary objects at these points, the same t... |
[
"How were these lakes formed?"
] | [
false
] | null | [
"A lot of the lakes in Canada are formed in depressions caused by ice sheets during past ice ages. When the ice moved over Canada it essentially scraped indentations in the bedrock. This is especially typical in the ",
"Canadian Shield",
", more or less encircling Hudson Bay. The elongated lakes are an indicati... | [
"Would you be so kind as to include the actual location in your post? Thanks a bunch!"
] | [
"I just zoomed in on a random spot in Canada, couldn't figure out how to get the location, sorry. "
] |
[
"What happens, on a molecular level, that leads to paper becoming soft after applying water to it?"
] | [
false
] | null | [
"Paper consists (mostly) of cellulose fibers, i.e. a polymer of glucose molecules. These glucose molecules have free hydroxyl groups, which can form hydrogen bonds to other molecules. ",
"In dry paper, at least many of these hydrogen bonds are to neighbouring cellulose fibers, which stabilises the overall structu... | [
"Water breaks up the hydrogen bonds between the cellulose fibers, so this stabilisation is lost.",
"To explain a bit more, the hydrogen bonds are formed between cellulose and water, rather than between different parts of the cellulose."
] | [
"Thanks. That explains a lot."
] |
[
"Why do batteries shut down even when they have a little bit more power on them?"
] | [
false
] | Why do batteries seemingly have some juice still in them when they die? For example, when a phone runs out of battery you can try to turn it on again. It might die right on the boot or even once it's turned on if you're lucky (It actually depends on the firmware, some don't try to turn but it's clear that they still have a bit of power left). Why do manufacturers do this? Is this some property of the li-ion architecture? Is this some design choice, maybe to increase battery life? Why not let the user choose to empty the battery for an emergency then? This is a question I've had for a while and I couldn't find an answer anywhere else, so let's see what's it! | [
"The device itself requires a minimum voltage to be able to run properly, with the voltage being synonymous with the battery's ability to deliver the amps to the device. ",
"The lower the charge in the battery, the lower the voltage given off by the battery, so a 12v battery fulled charged/recently charged may a... | [
"There are three aspects to this that I can think of.",
"You're asking about LiIon/LiPo batteries, since you're asking about phones. They are sensitive to deep discharging. If you discharge too far, you risk not being able to charge it again. So there is a cut off (brown out) circuit that monitors the battery and... | [
"with the voltage being synonymous with the battery's ability to deliver the power (amps) to the device.",
"Just to avoid confusion, ampere (\"amps\") is ",
" a unit of power, but of current. Power would be voltage times current."
] |
[
"How many stars exploded in order to create the Carina nebula?"
] | [
false
] | I just saw this post: And it made me wonder. How many stars exploded to create this nebula? Or was it formed through some other process? Given how large this is, it’s hard for me to imagine that one star could create something like this? | [
"The most massive (and arguably, the prettiest) nebulae are giant molecular cloud complexes. Rather than being formed by an outburst of gas from a star (like a planetary nebula) or by a star going supernova (like a supernova remnant), they are not directly formed by stars at all.",
"It starts from the \"interstel... | [
"I've been wondering this for years. Love the explanation, thanks."
] | [
"Thank you for the great answer! This was very helpful and cleared up my confusion."
] |
[
"How far back would we have to go to find the first common ancestor for all humans alive today?"
] | [
false
] | Also, what groups of people in the world today are the furthest relatives? | [
"Surprisingly, not very far!",
"http://humphrysfamilytree.com/ca.html",
"Quick notes: ",
"Quite likely every Muslim in the world today descends from the Prophet Muhammad",
"Quite likely everyone in the West descends from the Prophet Muhammad",
"Quite likely almost every Jew in the world today descends fro... | [
"You are 1 generation away from your parents, 2 persons",
"You are 2 generations away from your grand parents, 4 persons",
"You are 3 generations away from your grand parents, 8 persons",
"You are 4 generations away from your grand parents, 16 persons",
"Etc, etc....",
"10 generations down the line and th... | [
"I dont trust that website at all, the idea that DNA is not passed on over time is false, I am related to mitochondrial eve for example as is any other extant human. In terms of mtDNA mitochondrial eve is the MRCA, we are all derived from that haplogroup and therefore must all draw our mtDNA lineage back to this po... |
[
"What causes \"split face\" fur patterns in cats?"
] | [
false
] | I have a Tortoiseshell cat and her face is split right down the middle, half black, half orange with tabby markings on the orange side. What makes this divide happen? | [
"This is very informative, thank you!"
] | [
"This is very informative, thank you!"
] | [
"The term is chimera. It's what happens when a single organism has genetically distinct cells.",
"Usually in animals it's a result of the merger of multiple fertilized eggs. Tortoiseshell cats seem to be more susceptible to this than normal."
] |
[
"Why does the Soyuz fire do its deorbiting burn with the orbital module?"
] | [
false
] | It seems like a waste of propellant to put the orbital module on a trajectory towards earth's atmosphere because it doesn't contain any crew, and it will burn up on its way down. | [
"If the deorbiting burn doesn't work you have more time to figure out what went wrong. ",
"Soyuz TM-5",
" had that problem (at that time they used the opposite order). The toilet is in the orbital module...",
"It also makes the orbital module burn up quickly instead of staying in space as waste for several mo... | [
"If someone would hurry up and make solar sails practical, we could have a fleet of orbital junkyard dogs to both make us safer from space junk, and make launch planning easier, so you don't need a de-orbiter safety plan for every satellite."
] | [
"Also, the deorbit burn causes a deceleration of only 150 m/s. That is not very much."
] |
[
"How long can a straw be before you aren't able to suck anything out of it?"
] | [
false
] | [deleted] | [
"I have a rough idea from high school physics ten years ago so apologies for any errors and problematic phrasing. The max length for a straw to work (or another kind of water pump) with water on Earth is around 30 feet. The reason it maxes out is because \"sucking\" isn't really a thing. When you suck on a straw yo... | [
"The suction effect is caused by a difference in pressure. The surface of the water is presumably at atmospheric pressure, which is thus the largest possible pressure difference. In other words, the atmosphere pushes down on the water, which is then pushed up through the straw because of the pressure difference bet... | [
"You're right. Suction works by air pressure difference. If the thing you're sucking is water, then the difference between atmospheric pressure and the pressure at which water boils at room temperature gives you a maximum weight that can be supported per unit of surface area. (So regardless of the thickness of the ... |
[
"How is location in outer space measured?"
] | [
false
] | My physics teacher proposed the question of how you can give directions with out a point of reference? How are coordinates assigned to objects in space? Does stuff in space have x,y,z coordinates? What would be the origin or center of space? | [
"Aerospace engineer here. ",
"Everything that's been said so far is absolutely true. Position and motion are both relative. However, most orbital maneuvers that we do can be approximated as taking place within the gravitational influence of a single central body. Therefore, it's easiest to define coordinate syste... | [
"There are no fixed points in space. Spacetime is curved, and space is expanding. We can say where other objects are in relation to our solar system, but there isn't a fixed universal reference point we can build a cartesian coordinate system around."
] | [
"As the others have said position is relative. You ",
" give directions without a defined frame of reference. We can use earth centered coordinates within our solar system. We can use spherical coordinates centered on the earth to describe things we see in distant space.",
"The closest thing you will find to a ... |
[
"Why is the consumption of chicken eggs now recommended by physicians and alike, despite the fact that until recently it was discouraged due to high cholesterol content?"
] | [
false
] | Why is that? What has changed? Was it the discovery of something in the eggs or rather some biomechanism that we were unaware of? | [
"We discovered that high cholesterol foods have less of an effect on your cholesterol than foods with a lot of trans fats and saturated fats."
] | [
"There is no evidence that supports that the consumption of fatty foods correlates with higher cholesterol. In fact, long-term effects of ketogenic diets (little to no carbohydrates) show a decrease in LDLs and an increase in HDLs.",
"http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2716748/"
] | [
"Because people used to think the more you ate of fat/cholesterol/calcium/protein/iron/etc the more you would have in your body, now we know its never that simple. Glycemic index and fat intake likely have more of an effect on cholesterol than actual cholesterol. "
] |
[
"Why is it such a common occurrence for people to turn down music when driving to look for an address?"
] | [
false
] | null | [
"Several common models of attention describe it as a finite resource that you can spread around different tasks, stimuli, senses etc. Actively ignoring some stimulus to focus on another is also a demanding task. So based on our current understanding of attention, the explanation would be that when you need to focus... | [
"It depends on the nature of the secondary task and how much attention you are devoting to the primary task. Yes, you can \"tune out\" music or TV to a certain extent... But sometimes you find yourself having read the same sentence 5 times in a row because your attention was captured by the other stimulus. In that ... | [
"Yes these are called state dependent effects. The explanation is that when trying to recall, you are reinstating the learning context. This can be a state of the environment like whether there is music playing or whether you are in the same room or whether you are chewing gum, or emotional or other kind of state. ... |
[
"How would have our perception changed having 3rd eye? Would it be advantageous to only a pair?"
] | [
false
] | null | [
"Larger field of view (depending on placement). Also, potentially better stereo vision, again depending on placement. That's about it."
] | [
"Would perception of distance and depth change?"
] | [
"The distance to which stereo works is determined by the distance between your eyes (sort of -- technically, there is no limit, but practically, especially for small objects, we have poor stereo beyond 2 meters). The difference between the images on your retinas can provide depth information /sense of depth. For th... |
[
"Would someone please explain, in great detail, how the young earth may have theoretically yielded the first living cell?"
] | [
false
] | I'm not skeptical, I'm just curious as to what chemical processes would coincide in order to create living cells from dead matter. Edit: Thanks for the great discussion guys. You seem to have sated my frustrating curiosity...for now. | [
"Well, I'll give you the RNA hypothesis. Firstly what are the requirements for the first proto-cells? Such proto-cells would need:",
"polymerized \"bio\" molecules (there is no biology at this point in the earth's history so we need some starting materials). ",
"Segregation of contents from the environment (som... | [
"Not really.",
"This is one possible answer to \"how did our biochemistry first come about?\" Because it assumes our biochemistry, it really can't tell us much about the possibility of other biochemical setups.",
"Secondly, this only lays out the simplest of biochemical building blocks. Complex anatomy and stru... | [
"At first glance, this may seem like a snarky question, but you've really struck at the core of a deep and burning question that scientists are working towards explaining at this very moment. Because you say you have limited knowledge, I'm going to try to take a broad view at the kinds of chemical processes you nee... |
[
"Why is it so rare to see a tetrahedron complex with a central atom that has a single charge (+1)?"
] | [
false
] | And are there any exceptions whatsoever? | [
"The ammonium cation NH4",
" is tetrahedral and is plus one charge. I would say this ion is pretty common!",
"In terms of transition metal complexes, tetrahedral geometry is most common in d",
" or d",
" complexes, so Scandium, Yttrium, Lanthanum and Actinium would be candidates for tetrahedral compounds wi... | [
"I don't understand your question. Are you talking about the formal charge of a single atom in any tetrahedral complex, or are you talking about the oxidation state of a metal in a metallic tetrahedral complex?"
] | [
"Sorry if my question was unclear.\nI was talking about the overall charge of the complex "
] |
[
"Articles say that getting the covid vaccine doesn’t affect rapid covid PCR results. Can someone help explain why (not)?"
] | [
false
] | null | [
"The vaccine is injected in your arm and the viral material stays fairly local. PCR test samples are most commonly taken from the nasal or oropharyngeal cavities.",
"Here's a review comparing ",
"intramuscular vs subcutaneous vaccine administration"
] | [
"Adding to what ",
"u/NickWarrenPhD",
" wrote, the RT-PCR test also only detects viral RNA. The vaccine mRNA as well as the vaccine protein (which is undetectable to the RT-PCR test anyway) stays pretty localised so there is zero chance it would end up in your nasal cavity for the RT-PCR to detect."
] | [
"The PCR might not distinguish between live virus and dead virus. Or, maybe the virus still runs a certain course through your body while the vaccine only provides enough immune response to keep you from developing symptoms. Or, maybe the test is actually detecting the vaccine particles and not actual virus particl... |
[
"Are house cats one species of cat or multiple species? If one species, why aren't multiple breeds considered different species?"
] | [
false
] | Hey there, I know almost nothing about taxonomy but I was thinking about this..to clarify a bit more, cats are wide and varied; but I seem to have only found shaky information regarding what species a cat is (wikipedia says ). Is this the only species? How can a species with so much variation within itself not be classified as a different species? If you look at something like birds it seems like they have a large number of species even with minor physical differences between the kinds of birds. To give an example, within the Macaw species of birds there are 19 subspecies alone have little physical variation (at least, I think so), so why aren't they just considered a different "breed" of Macaw? Hopefully this is clear enough. | [
"Contrary to what is often said, this actually isn't a criterion for classification at all. Many interspecific hybrids are perfectly fertile, including all future generations."
] | [
"Because variation that is visible to the human eye isn't representative at all of underlying variation. Different breeds of cats have been bred to look different, but almost the ",
" differences between them are the visible ones. Genetic differences in general are very small. And in many cases, the divergence... | [
"except that Mallard ducks, for example, can produce hybrids with about two dozen other species. Many (perhaps most) species can hybridize with at least one other species."
] |
[
"Why do we get gray hair as we get older?"
] | [
false
] | [deleted] | [
"I think it is more appropriate to say that both are right. ",
"Inside the hair follicle, there are melanocyte stem cells, and melanocytes. Melanocytes are sensitive to hydrogen peroxide levels. Where does hydrogen peroxide come from? It comes from the other prominent type of skin cell, keratinocytes. It is part ... | [
"A theory I've heard about which sounds plausible: small amounts of hydrogen peroxide are produced in many cells in the human body, including around hair follicles. When we are young, we have lots of an enzyme called catalase that breaks the peroxide down into water and oxygen, before it can oxidize important cellu... | [
"I've had many grey hairs that have colored roots. Do we know if there is some controllable mechanism that regulates these processes?"
] |
[
"How did Pangaea break up?"
] | [
false
] | More broadly, "How does plate tectonics work?" I understand the basic theory, but I don't understand how a plate the size of a continent got halfway around the world when there were already plates there. I'd liken it to trying to trans-locate a single brick in a wall without leaving the wall itself. Did the plates in the way break up, or did they somehow go under the moving plates? Help? | [
"The other half of the equation is ",
"subduction",
"."
] | [
"Yep. That's actively what's happening out here in California; the Pacific plate is subducting under the North American plate and the lighter materials melt and then float back up. That's how the current version of the Sierra Nevadas formed, there's a felsic batholith that's floating up through the crust, and whe... | [
"So the plate going under would melt/break up, while the other side would be getting new material that could cool into a plate?"
] |
[
"In regards to the Quantum Zeno Effect, what defines \"observation\"?"
] | [
false
] | null | [
"Perturbation. Probing the system in some way so as to derive information about some element of its state, such as its position or momentum. Keep doing it to a system that would normally (for example) decay, and do it so quickly and \"thoroughly\" that you essentially lock down that observable, which is linked to i... | [
"I think it's better phrased as:",
"Entanglement ",
" as measurement.",
"but the two are fundamentally linked, yes."
] | [
"In general, essentially anything that requires the quantum system to have a well-defined (i.e., classical) state counts as measurement.",
"More technically, if the state of a quantum system becomes inseparably mixed with the state of another quantum system that is too complex for us to realistically describe qua... |
[
"Can it be said that some languages are objectively easier/easier to learn than other languages?"
] | [
false
] | Obviously the difficulty with learning a language depends on if a person knows a similar language already. Apart from that, would it be wrong to, for example, call English easier than Finnish? | [
"Easier in what sense? Languages have different ",
" of complexity. ",
"So while one language might have very complex syntax, maybe its morphology is not complex at all. Another language might be really phonologically complex with a huge inventory of sounds to learn, but perhaps its syntax is not as complex. (T... | [
"Yeah! OP specifically asked to disregard native language influence so that's why I didn't address it here.",
"There's a lot of fascinating work on native language influences on second language learning. Similarities & differences between languages can actually sometimes lead to unexpected effects. For example, h... | [
"Surely your native language is relevant to this question as well. Wouldn't foreign languages with similarities with regards to phonetics and/or grammar be easier to learn than ones that are completely different? (sorry if phonetics isn't the right word, I mean vocal sounds used in word forms)"
] |
[
"Why does sleep deprivation lead to hallucinations?"
] | [
false
] | null | [
"I thought DMT's role in the brain was just hypothesis as there isn't enough evidence etc or was debunked?"
] | [
"I thought DMT's role in the brain was just hypothesis as there isn't enough evidence etc or was debunked?"
] | [
"It is mostly speculation. No solid evidence. I haven't read his book, but Dr. Rick Strassman has a solid theory on it. Check this out for more info:",
"https://www.rickstrassman.com/",
"Again, it's mostly just speculation. But I'm not sure it was debunked."
] |
[
"Can someone please help me understand the concept of mass a little better?"
] | [
false
] | [deleted] | [
"Mass has two major properties (the two I chose might be considered arbitrary by some, but I'm choosing two for the purposes of this discussion). First, the mass of on object tells you how much force it will take to accelerate it. This is captured by Newton's second law: F = m*a. Thus, the more massive something is... | [
"(The reason this doesn't work on Earth is because of the atmosphere slows down lighter things more than heavier) ",
"You mean air resistance, not lighter vs. heavier, right?"
] | [
"Mass is inherent, and weight is just mass by surface gravity. Inertial mass is obtained by newtons dynamics law and gravitational mass is determined by newtons universal gravitation. Dark matter is simply a gravitating, near-perfect black body. Nothing about the definition of mass and weight changes "
] |
[
"What is our current best guess of the topology of the universe?"
] | [
false
] | null | [
"The ",
"observable universe",
" ",
"is simply connected",
" on the scales we can observe. Anything could happen in the rest of the universe, but the simplest guess is that there's more of the same."
] | [
"Which gives absolutely no hint on the topology."
] | [
"Which gives absolutely no hint on the topology."
] |
[
"Are there any theories or examples of Physical Laws that are not static or immutable, and may have changed over time?"
] | [
false
] | It seems almost nothing in the Universe is indefinitely resistant to change, so it is possible to that the rules governing the Universe are also susceptible to change? I've never heard of any theories or examples of this, and it seems that common belief would be that the Universe follows the same rules now as it did at its beginning. Is it unreasonable to think that particles/matter/energy could have behaved differently tens of billions of years ago, and gradually came to behave that we observe today? | [
"There are theories that the fine structure constant, which basically determines the strength of the electromagnetic interaction, may have changed over cosmological time scales.",
"There is some experimental evidence suggesting such an effect, JK Webb's group has been doing spectra analysis of distant quasars and... | [
"I guess after reading your response, I am more interested in why the assumption that the Laws are static exists?",
"Let's say some law wasn't static, but changed with time somehow. E.g., say Newtonian gravity doubled next Tuesday. Well, we could just change the dynamic law as based off a static law F = G(t) M... | [
"It's not that the laws themselves have changed, but the relevance. In the early universe, the equation of state for the quark gluon plasma was highly relevant; nowadays gravity is the most relevant phenomenon on the universal scale.",
"One example is Hubble's Law and Hubble's constant, where Hubble's constant ch... |
[
"Could dark matter be explained by neutrinos?"
] | [
false
] | Okay, there has to be a gap in my knowledge. Which, as an armchair science enthusiast, does have many such gaps. But here's my thinking, and please let me know where I've gone wrong. 1: Dark matter interacts gravitationally, but not with the electromagnetic force. 2: Neutrinos have mass, but don't interact with matter. The only way we can detect them is when they break light speed through a material. I was also under the impression that they wouldn't interact electromagnetically, since they don't have electrons to absorb/emit photons. 3: So, if we have a bunch of neutrinos, maybe even slow-moving (is that even possible?), would they exhibit the characteristics of dark matter? | [
"Neutrinos ",
" a form of dark matter, but they simply do not have enough mass to explain more than a few percent of dark matter. Also, because they have such small mass, they are nearly always moving extremely fast, a property inconsistent with observations about dark matter. For this reason we call neutrinos \"... | [
"Excellent! Thank you so much for the info, and I'm pleased to know that I wasn't all the way out in left field somewhere."
] | [
"Thank you for the follow-up! I'll have to look into the theory behind sterile neutrinos. Dark matter is fascinating, but it's tough to keep up on the research without clickbaity garbage news clogging up the feed."
] |
[
"Why haven't aquatic mammals evolved to breathe underwater?"
] | [
false
] | I know that aquatic creatures eventually learned to start breathing on land, and crustaceans and amphibians can breathe both under and above water, so why cant Mammals? One of the biggest problems for whales and seals is finding an air-hole while hunting, so why haven't they adapted over time to breathe underwater using gill-like devices? | [
"In addition to the non-goal-drivenness others mention, there is a considerable lack of dissolved oxygen in water compared with air, or at least it's harder to get out of the water. And it takes a lot of oxygen to burn the calories to be a warm-blooded mammal. It could happen I guess, but even sea-turtles (who have... | [
"because evolution doesn't push towards a certain goal, it's a \"random walk\" of mutations, most of which are usually detrimental. So they might, if that mutation appears and is useful so it is passed on through the gene pool, but there's nothing to make it happen just because it might help."
] | [
"granted i'm a physicist, not a biologist. I may be incorrect. This is just what I recall from similar threads on the subject."
] |
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