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What happens to helium-filled birthday balloons that are released into open air? | they go up a few thousand feet and pop as the gas in the balloon expands beyond the stretching limit for the rubber. No balloon will ever make it into orbit.. orbit requires thousands and thousands of miles an hour of lateral velocity |
Why does the moon have so many craters and the earth so few? | Partially right. It's mainly erosion, and many smaller things are lost due to disintegration in the atmosphere. Water, wind, ice, etc- they all work to reform the landscape, erasing evidence of impacts. But we still see plenty of craters in dry places or places with less erosional activity. Meteor crater in Arizona is a good example. Also, impacts in the ocean are much less likely to leave a crater (unless it's really big), and since oceans cover over half the surface area of the earth, that many less craters! |
Is there scientific knowledge of a point in our early-mid 20s after which hangovers become much worse? | I can think of a number of different reasons why this may be the case; metabolic rate change, drinking habits, alcohol tolerance just to name a few. But this is simply speculation. Here are a couple of studies that you might find interesting: [Age, alcohol metabolism and liver disease.](_URL_1_) [Variations in alcohol metabolism: influence of sex and age.](_URL_0_) |
When we dream, do our bodies and minds "remember" the dream experiences at a chemical level even though our waking mind has no memory? Do dreams have a physiological effect on the human body? | The short answer to anything dream related is no one knows, because there isn’t enough research and we can’t cut apparat people's brains to look at them with a microscope without them dying and thus not dreaming anymore |
Do elder people who suffer memory loss start losing different "kinds" of memories in a particular order? | > is there an actual pattern for what memories you lose first when you suffer memory loss? In the case of Alzheimer's, yes. As another comment mentioned, 'dementia' is a broad category that can mean a lot of things, and there are also many different causes of memory loss. Different brain regions have different roles in memory, and store different types/duration of memory. With the progression of [MCI to severe Alzheimer's](_URL_0_) the affected portion of the brain expands to encompass more brain regions and by extension more cognitive functions, in a somewhat predictable pattern. There are other things going on too but this is the main reason you see an increasing number of *types* of cognitive impairments with time - more brain regions are being affected. |
Is a brain transplant theoretically possible? If yes, what would the outcome entail? If no, why not? | I find it a little unpleasant but since there have been 'successful' [head transplants](_URL_1_) then yes, in theory a brain transplant could be done. Challenges are mainly with scarring of nerve tissue such as the spinal cord. - _URL_0_ |
Is it theoretically possible to perform a brain transplant whereby the recipient survives and is fully functional? | Honestly we don't possess enough knowledge to successfully transplant a brain. Its a common misconception since the enlightenment that the brain and body are "separate" but you have to understand that the brain also includes all your nerves that extend out from the spine to communicate with the body. Do I believe such a transplant to be possible? No but I have no definitive proof as only extensive testing could really determine if a head/brain/spine transplant could communicate with the nerves located in the recipient body. However when you consider how challenging it can be to get an "alien" organ to be accepted with current practices, you start to see how far off we are from a successful brain transplant. |
Why will a bigger cup of coffee stay hotter longer than a smaller cup of coffee? | It's because surface area grows like length squared whereas volume goes like length cubed. That is, a bigger cup has proportionately more coffee in it relative to its surface area. So you have a much larger amount of heat you need to transport out, but only slightly more surface area that you can transport it through. |
Is there a particular shape coffee/tea cup that keeps the beverage hotter, longer? | Spherical. A sphere has the least amount of surface area per volume, and the surface is where the heat transfer happens. Less surface area means less heat transfer is possible. Since a sphere is not a practical shape for a mug, the cylinders we use now is probably the best comprimise. |
Why is the suicide rate typically significantly higher for men than women? | In England 'the stiff upper lip' is responsible for the majority of male suicides. Men simply do not talk about their problems. Women will more likely go to their social group or a family relative; usually female, and debate their issues, yet in comparison men do not want this. They do not want to seek help because they are supposed to lead and solve it themselves, hence the stiff upper lip. When they reach problem that is unsolvable one of the courses of action to combat that situation is suicide. In the north east of England where there is a lot of poverty an initiative known as CALM has been introduced that presents suicide as a option that everyone considers, as a result of this programme the suicide rate in this area has dropped by 55%. Perhaps this is the way forward? |
How close are lab-grown diamonds to the real ones? At what point is a lab-grown diamond a real diamond? | People are making out in this thread that synthetic diamonds are next to indistinguishable but there are quite a large number of detectable, atomic level differences. This GIA piece summarises the differences _URL_1_ The table at the start of the Identification section lists the main detectable differences: _URL_0_ |
What gases besides Helium can cause a standard party balloon to float? | [Any gases lighter than air](_URL_0_) EDIT: If you have the resources, and are actually going to try this, I would suggest avoiding flammable gases, such as hydrogen - think *Hindenberg disaster* |
Does observing an eclipse contribute to astronomy? | Perhaps the most famous astronomical discovery from an eclipse is Arthur Eddington's observation that the light of distant stars is bent by the gravity of the sun, as predicted by Einstein. They're also useful for seeing the spectrum of the solar corona, which is normally hard to see over the sun. |
Why is it that we are losing helium into space, while hydrogen stays around? | Helium, a noble gas, is too light to be held under earths gravity. Hydrogen is lighter, and free hydrogen will also escape, however, it is also reactive, and unlike helium, is mostly bound up in compounds with other elements. Free hydrogen will still escape. |
Why does skin damaged by the sun not get replaced with healthy new skin? | You're going to have to clarify your question a bit. When you get sunburned, the damaged skin goes away and is replaced by new/healthy skin. |
Would soil on Mars grow plants? | Nope! Not as it is naturally. In the book (which is fantastic, by the way), Mark Watney actually adds fertilizer (poop) and water to the soil, so it's not as simple as it seems in the trailer. That said, plants still wouldn't grow in Martian soil in reality. I'm no botanist, but one major problem with the soil on Mars is that it's covered in perchlorate, an extremely reactive (ie explosive) oxidizer, which is toxic. I'm sure there are other problems as well... |
Why don't wheels spin within their tires? | You're neglecting the high pressure of air inside the tire that keeps the tire bead seated into the rim. All that pressure squeezes the rubber tire against the metal rim and greatly increases the friction between the two. |
Why do I see faint flashes of light when I roll my eyes around with my eyelids closed? | Slight pressure against your retina from the intraocular fluid (leading to sensory input as light) caused by the muscles pulling the eye around. |
How do whales and dolphins sleep? | _URL_0_ That episode of radiolab is very interesting and the first section talks directly of how dolphins sleep. TL;DL - Their brains are a bit more divided than ours (left/right) and they put one hemisphere to sleep at a time, while the other hemisphere functions enough to just keep them surfaced and breathing. They call it logging since they just kinda float there like logs. They then switch hemispheres. Its been a while since I listened to the podcast and I'm sure someone else can come along and give a better/more specific answer, but seeing as its been 4 hours without any responses, I thought I'd take a crack at it. |
How do blue whales sleep? | * _URL_1_ * _URL_2_ * _URL_3_ * _URL_0_ tl;dr most whales have the ability to sleep with one half of their brain at a time. |
How effective is bleach at killing micro organisms? | Bleach (sodium hypochlorite) kills pretty much everything. I work in a BioMed lab, and we use bleach as a standard disinfecting agent before we dispose of biological waste. Bleach is not an antibiotic like many agents used. Instead, it denatures the proteins that comprise microbes, usually irreversibly. Also, the high basicity of bleach can cause damage to cells. Bleach or ethanol (EtOH) are industry standard means of disinfecting in the lab setting. Bleach is used primarily for killing microbes in a sample or beaker (say I have a flask of bacteria that needs to be disposed of), EtOH is used to disinfect surfaces and equipment (spray down the micro-pipettes, biosafety cabinet surface, your hands, etc). Bacterial adaptations are usually the result of antibiotics. Neither bleach nor EtOH are antibiotics, so the chance of adaptations is very, very low. I've never heard of it happening. |
[astronomy] Where do the meteorites that fall on earth come from? | According to [This paper] (_URL_0_) There has been detection of dust from outside of the solar system, possibly coming from several parsecs away. |
If within ice are very compact water molecules, do the molecules in my alcohol/juice/sports drink get more compact when I put them in the fridge? Why don't we notice the difference in density between warm liquid and cool? | Ice is actually less dense than water, so in ice the molecules would be more spread out than in liquid water assuming that the frozen liquid is homogeneous, which it probably isn't. And yes, there is a difference in density between cold and warm water, but it only varies from about 999.97 g/dm^3 at 4°C to 958.4 g/dm^3 at 100°C (998.21 at 22°C) so it might be difficult to notice the difference. As a rule of thumb, when you cool something down it shrinks (of course water below 4°C is an exception to this rule), so the molecules in your juice will be more tightly packed when cold than when warm. |
Do plants and their roots create heat? | I thought this was actually a pretty good question.. Thermoregulation, i.e. producing heat in response to external stimuli, is usually associated with birds and mammals. However, according to [this](_URL_0_) article it sounds like there are some flowering plant species that are able to use an alternate pathway for respiration that allows for heat generation instead of ATP synthesis. This is actually really really cool. Maybe someone who knows more about this can chime in? |
Do plants release heat? | Yes! There are plants that produces excessive amounts of heat, referred to as thermogenic plants. They do this by uncoupling the electron transport chain to produce heat instead of ATP. I cannot think of specific species right now but I know that many of these plants use this heat to better disperse compounds that attract pollinators and I think there is also a plant that uses thermogenesis to melt snow around its flower. |
Are galaxies continually getting flatter? | Generally no. The main reason disks get flatter is that they are dense enough for collisions between particles, which causes them to lose vertical speed and hence drop towards a flat disk. In a galaxy, the odds of even a single star colliding is very small, so the vertical velocity spread doesn't significantly change without a perturbing force. |
How Big Can a Synthetic Diamond Be? | I haven't kept up on the field, but there was a.ckmpany trying to grow them via vapor deposition processes to try and make semicondutor-sized wafers. Last I had heard they were making wafers on the inch or so scale, but I think they got derailed for the jewelry industry. Same deal with Gemesis (if I remember the name right). They do it with pressure chambers. I saw a talk by one of the founders and he had crazy baller jewelry. |
If the Hubble telescope can see extremely far in to deep space, why dont we use it to look at planets/galaxies closer to find life etc. | Galaxies are big, planets are small. Do some simple math, a galaxy is maybe 100,000 light-years across, or more, at a billion light years away that's a ratio of 1:10,000. Now consider a planet, even a huge planet like Jupiter is only about 0.5 light-seconds in diameter. So even at 4 light-years distance, the closest any other star is to us, that's a ratio of about 1:240,000,000. Planets are very, very tiny, there's just no way with current telescopes of resolving them into anything other than a single point. Worse, because planets are near stars the enormous brightness difference means that the light of the planet gets lost in the glare of the star. With advanced techniques it may become possible to cancel out the glare of the star and resolve the planet but such technology is still being developed today and may be years or decades away. |
How come you can push your tongue out since a muscle can only contract? | This here should answer your question _URL_0_ The genioglossus muscle is responsible for "protrud(ing) the tongue as well as depressing its center" |
Does swimming during a storm put you at greater risk of death from lightning? | As the National Lightning Safety Institue says : "Swimming pools are connected to a much larger surface area via underground water pipes, gas lines, electric and telephone wiring, etc. Lightning strikes to the ground anywhere on this metallic network may induce shocks elsewhere." _URL_0_ However they do not explain really more than that. |
How much oxygen does the new Honda fuel cell vehicle consume in comparison to an internal combustion engine? | what about the water moisture put out by fuel cells? I've seen a bus running on fuel cell and the exhaust looked like steam locomotive. I've been on the streets of Manhattan in July when the temp is 100F and humidity is 100% and its feels like hell. If all the vehicles are putting out as much moisture as the bus it will feel like a steam bath... or will it? |
Do other elements naturally occur in multiple configurations in their pure form, the way carbon does? | do you mean like allotropes? Carbon can have several allotropes including buckyballs, graphite, and diamond, and more. _URL_0_ Other elements can exhibit allotropy _URL_1_ |
Why do fruits have very distinct flavors? They are all just made of sugars, where does the "uniqueness" come from? | Fruits have lots of other molecules in addition to sugar. One type of molecule that is responsible for the aroma/taste of fruit is [esters](_URL_0_). Esters are small, volatile organic molecules that, depending on the specific ester in question, have the characteristic smell of a particular fruit. |
Do solar system forming clouds/nebulae have to be spinning (since solar systems seem to form in disks)? If so, why are they spinning? | Basically it's much, much, much more likely for a nebula to have some net angular moment than not. To have no rotation the motion of all the particles that make it up would have to be so carefully balanced and there could be no perturbations from other systems. Basically it just never happens. |
Why do plants turn yellow when they are dehydrated? | Yes, the chlorophyll breaks down over the course of a day or two, causing it to lose its pigment. The grass will not spend energy making new chlorophyll until it has a means of transportating it and other nutrients to throughout the leaves, which requires a certain amount of water. |
Why do atoms prefer to have 8 valence electrons? | I think you'll find that Pauli's exclusion principle helps to explain in more detail why octets are the "perfect" state. The octet rule, though helpful in understanding the intricacies of bonding don't delve into much detail. In Quantum Mechanics, we use quantum numbers n (energy level/shell character), Azimuthal ℓ (Angular), Magnetic mℓ (describes orbital), and Spin ms (angular momentum). These describe various characteristics of nuclear particles. Take a look in more detail to the principles of quantum mechanics and particularly quantum numbers to understand in more depth why octet rules exist. Keep in mind, there are always exceptions, nature is fascinating that way. However for most particles they follow these basic (Actually quite complex) rules. |
Could there be a galaxy closer in distance than Andromeda to the Milky Way that is similar in size and shape to both but we can't see because the core of the Milky Way is blocking our view? | Nope! We can see through the Milky Way well enough in various wavelengths to see what else is out there. Far infrared radiation, for example, can pass through obscuring dust in our galaxy to help us see outwards. There are [a bunch of dwarf galaxies orbiting the Milky Way that you may be interested in](_URL_0_), though. |
Why are SSDs considered as storage and not as non volatile memory ? | > I learnt today about in-memory databases and how now non-versatile memory makes them able to hold information even when powered down. Non-volatile, yes. > It got me thinking : that's just what SSDs do ! So the question is, why are SSDs considered as storage, and wouldn't a SSD database be a good compromise between price and rapidity ? SSD's *ARE* a form of non-volatile memory. Yes, they are frequently used in database applications. The distinction between "storage" and "non-volatile memory" is contextual and superficial. |
Will 128-bit architecture computers exist in the future, or is x64 a limit? | Theoretically there's no reason why they shouldn't. You'll need a 128-bit address space as soon as 16 EiB (the maximum for a 64-bit address space) isn't enough. I have no idea when that point will be reached, but it's unlikely to happen in the next decade or two. However, you can have 128-bit and 256-bit registers in a CPU (SSE and AVX respectively) which can hold one huge number or more typically a vector of multiple 32-bit or 64-bit words. The upcoming AVX-512 will supports 512-bit registers. Additionally, GPUs tend to have wider memory buses that can reach up to 512 bits wide. This lets them read multiple adjacent words in one go to improve memory bandwidth without cranking up the memory clock speed. The downside is more wires between the GPU and memory and the larger area requirements. |
If I was at the midpoint between the sun and the next closest star, how big and bright would the two stars be? | The next closest star is Proxima Centauri, 4.24 light-years away from the Sun. In spite of how close it is to us, Proxima Centauri is a very dim red dwarf - at magnitude +11 it's not visible to us on Earth without a decent telescope. Halfway to Proxima Centauri would put you 2.12 light years from the Sun. Proxima would be magnitude 9.5, still too dim to see without a telescope or at least a very good pair of binoculars. The Sun, meanwhile, would be almost 135,000 further than we usually see it, meaning it would be 135,000^2 times dimmer. That would place its brightness at magnitude -1.1, almost as bright as Sirius as viewed from Earth, the brightest star in the nighttime sky. |
Why are oceans (underwater) full of colour, but fresh water lakes are compellingly gray? Why are there no colourful fish in fresh water? | > Why are there no colourful fish in fresh water? [There are many colourful freshwater fish.](_URL_1_) In particular [Lake Mawali Cichlids.](_URL_0_) |
If I were to point my telescope at a nebula, would it show up in colour? | Usually false-color. Images of nebulae typically include narrow-band filters which pick up only a specific emission line, such as H alpha or OIII. These filters are usually colored corresponding to where they are on the EM spectrum, so H alpha is usually colored pinkish or red because it's at 656 nm. [This site explains it very well and thoroughly](_URL_0_). |
Is it possible for two planets to be inside the habitable zone around a star and for their gravity not to affect each other's orbit? | All planets' gravity affects all other planets. But it's possible for multiple planets to be in stable orbits within a single star's habitable zone, yes. |
How do some fruits and vegetables, like avocado and olives, produce fat? | There's a terminology difference here that is probably confusing you. All organisms produce what are called [fatty acids](_URL_0_), some of which are essential fatty acids, ones that humans require to be healthy, but that we cannot make (enough of) ourselves. Fat is what animals make, and oils are what plants make, the main difference being their consistency, where fats are generally solid, and oils are more liquid. Both animal fats and plant oils are fatty acids. So to answer your questions: Yes fruits and vegetables make fatty acids, but they don't make fats. They make their fatty acids the same way we do, by using complex enzyme pathways to convert other similar compounds (triglycerides and phospholipids) into fatty acids. Yes, each fruit or vegetable as a (mostly) constant composition and amount of fatty acids. |
Is water really tasteless or are we just so used to the taste of water we don't give any thought to it? | There is evidence that mineral content in water affects the flavor we perceive. Bottled water manufacturers add in the desired minerals rather than selling distilled water, which some say tastes "flat." Here's a study about the chemometric analysis of bottled and tap waters that had been through blind taste tests. It was determined that many testers disliked the flavors of high concentrations of certain minerals and liked others. _URL_0_ |
Does the use of microwave ovens distort chemical structures in foods resulting in toxic or otherwise unhealthy chemicals? | Yes, microwave ovens distort chemical structures in foods. The heat from the microwave energy causes proteins to uncoil and change their shape, causing their texture and flavor to change. This phenomenon is known as "cooking", and is the same whether you microwave, boil, bake, or fry food. |
Why silicon cannot form long chains like carbon does, despite being in the same group and having the ability to make the same number of bonds? | They can actually, but they are unstable and oxidize/burn/explode spontaneously in air to form silicon oxides (sand/glass/quartz, etc). The reason for this instability was already given by /u/Brainmold: the Si-H bond is much longer than the C-H bond due to the larger radius of the silicon atom, making the bond much weaker. Compounds consisting only of tetrahedral silicon and hydrogen are called [silanes](_URL_0_) in analogy to the alkanes (tetrahedral carbon and hydrogen). Silanes can form straight chains, branched chains, and rings just like alkanes, but there are much fewer silanes known because the larger silanes become increasingly unstable. |
What exactly is the noise coming through my speakers when my phone receives signals next to it? Why does this happen? Could this phenomenon be used practically? | That's your phone call. Your speaker chords are made of metal and they're acting as a radio antenna and picking up your call. But since your call is digital, and encrypted, and transmitted at a frequency outside your hearing range, the ringing just sounds like noise on the speaker. We use this phenomenon all the time. It's how radios work. ;P |
According to the book "a short history about nearly everything", the universe grew to be a million billion miles across in under a minute after the big bang. This would be much faster than the speed of light, how is this possible? | The Big Bang is the initial expansion of the universe, of space itself. Light moves across space. But we're talking about space itself expanding. Say you have a car that can drive 60mph on the ground. That's it's speed limit. Now I grab the Earth itself and stretch it apart. The car can be receding from me at more than 60mph. |
How could the universe be a few light-years across one second after the big bang, if the speed of light is the highest possible speed? | There is no speed limit on the rate of expansion of the fabric of the universe (space-time). During the first few moments after the Big Bang, if the theory of Inflation is correct, the volume of the universe expanded by a factor of 10^78 in a time span from ~10^-38 to ~10^-32 seconds. Edit - To add to this. The speed of light is the speed limit for which information can propagate (which therefore means anything with mass/energy). There is nothing, as far as we know, limiting the rate of expansion of the universe itself. Objects very far from us are actually travelling away from us at a speed greater than the speed of light since the rate of expansion between two points increases as you increase the distance between said objects. The consequence of this is that light from these objects will never reach us. |
Is it possible for a planet to have a sun orbiting it, rather than the other way around? | All big planets we have found so far consist of a large fraction of hydrogen. This means that if you would grow to the size of a star it would simply ignite and become a star. |
Butter is a dairy product. Why, then, can butter be unrefrigerated but milk or cream goes rancid so quickly? | Water content has a lot to do with it. The ability of bacteria to degrade the butter is controlled by the amount of water present. It has to do with the activity (in the chemistry sense) of the water. The available water is bound to other molecules and not available to bacteria that need it the water to survive. Water can also hydrolyze fats and proteins creating rancid flavors. Also, a lot of the compounds that taste good are easily oxidized and the oxidized forms can taste bad. Like that old ass jar of olive oil in your cupboard...it tastes like crap because it has gone rancid. It smells bad, but not because of bacteria. Often food will smell bad, but the bad smells are not the result of pathogenic bacteria and will not necessarily make you sick. I am a geologist, so this may be a little simple. |
If galaxies are all accelerating away from each other, how long in the future will we not be able to observe the Andromeda galaxy? | Hubble expansion only dominates gravity on the scale of galactic superclusters. Andromeda and the Milky Way will collide along with everything else within our local group eventually. |
Does eating lactose while lactose intolerant have cumulative negative effects? | The lactose itself does nothing in people with lactose intolerance, they just can't digest it. The bacteria that feast on the undigested lactose that enters the intestine cause the problem. If you don't eat lactose for a longer period you'll have less lactose-consuming bacteria in your intestinal flora. If instead you eat lactose regularly your intestinal flora will contain more lactose-consuming bacteria. Which will result in a stronger reaction. So no real permanent damage but eating lactose will worsen it. |
Why do mirrors reflect light? | Every object reflects light; it is this reflected light that enters our eye and allows us to see the object. Mirrors are special in that they reflect nearly all the wavelengths (colors), and the substance doing the reflecting is very smooth on a molecular scale, so you don't have tiny scatterings of the reflected light in different directions due to microscopic bumps in the material. |
Why do mirrors reflect light? | Here are some good answers from /r/askscience: [1](_URL_1_), [2](_URL_0_), [3](_URL_2_), [4](_URL_3_) |
Is there definitive scientific evidence that the universe is, in fact, infinitely expanding? | There's clear evidence that the expansion is happening and that it's accelerating. If we assume this will keep going then eventually all galaxies become isolated from each other and something like a [heat death](_URL_0_) occurs. But no one knows if the expansion will keep on going. We don't even have a good theory for the acceleration yet. |
Would the impact of a very big meteor like the one causing the dinosaurs extinction be noticeable around the world? | The impact that killed the dinosaurs was estimated to be around 100 *million megatons* TNT equivalent. By comparison, the Tsar Bomba was 50 megatons and the shock wave circled the world 2-3 times, detectable by standard instrumentation. The sheer amount of debris and the weather change would be quite noticeable to any naked-eye observer. Such an impact would be 2 *million* Tsar Bombas. Edit: I should have mentioned the Tsar Bomba is the most powerful nuclear bomb ever tested. |
So how do nuts have fat? I mean, fat is a somewhat complex molecule that animals use. What is a plant doing with them? | Plants have plenty of lipid molecules, just like like animals. They serve as a compact form of energy storage, in addition to parts of some essential cell components such as plasma membranes and the basis for some cell signaling molecules such as steroids. As a rule, most plant lipids are oils, which are liquid at room temperature, rather than fats, which are solid at room temperature. But in the functions they serve in the body and how the body processes them, the difference between fats and oils is mostly arbitrary - you body is not at room temperature anyways. And there are certainly examples of plant "fats", a good example being [cocoa butter](_URL_0_). |
Why is it that some craters, notably on the moon, have a small elevation in the centre/point of impact? | I think [Tycho](_URL_2_), a young crater on the moon, is a good example of this. What is going on is that a large impact produces enormous pressure, well above the ultimate compressive strength of the rock. As a result, the rock behaves as a fluid, and you get dynamics similar to [droplets of water](_URL_3_). The impact spreads the rock out, but after that the rock flows back into the depression. The momentum creates a spike in the middle. As the pressure dissipates the rock eventually freezes in place. The larger the impact is, the longer the rock will be able to flow. So a small impact produces a [simple crater](_URL_1_) that looks like a bowl, because the rock never flows back to the center. A larger impact produces the [central peak](_URL_0_) as we discussed. Even larger impacts can produce a [central ring](_URL_4_) if the peak has time to flow back out. Again, all these intermediate stages appear in the water droplets. |
If matter is never created or destroyed, that would mean that there is a set amount of matter, right? But the universe is infinite. How? | There is a fixed amount of mass-energy - matter can become energy and energy can become matter, but none can be created or destroyed. The observable universe is not infinite, and since we can't "see" anything past the edge of the observable universe (there has not been enough time in all of history for light to get from there to here), that doesn't really matter. Just like the question of parallel universes or what happened before the big bang, it simply isn't in the domain of things that Science has the ability to know about. We do know that the density of the observable universe, when you look at it from a large enough scale, seems to be uniform. We don't know and don't care if it continues to be uniform past that horizon - anything out there is far far away, and thanks to the expansion of the universe, it is getting farther away at a rate faster than the speed of light - it cannot possibly have any impact on us, so we simply will never know. |
Does data stored on a computer or flash drive have weight? | As I mentioned in another similar thread, imagine that you have two sets of eight coins. One of the sets is all heads (HHHHHHHH) while the other is (HTTHTHHT), representing the number 105. Do the two sets of coins weigh any differently? |
Why are cold beverages generally preferred over regular beverages? (i.e. cold Coke is better than warm Coke) | This question has been asked [many times before.](_URL_0_) From what I remember the consensus is that the preference for cold drinks is mostly just a peculiarity of western culture. |
If looking at an angled galaxy, like Andromeda, through a telescope, is the light from the far end of the galaxy 200,000 years or so older that the front end? | Yes, but not by very much. The the closer part of the galaxy is a more recent image of what's going on in that particular region of Andromeda, while the far side is an older one. This gives a slightly skewed or warped perception of the state of the galaxy as a whole, but it's minimal and doesn't cause anything that would significantly impact our perception of Andromeda's shape, or its composition, distance, etc. Despite the differences being potentially hundreds of thousands of light-years depending on what points you choose to look at, it needs to be remembered just how enormous galaxies are, how far away they are from Earth, and how slowly they rotate from the perspective of a distant observer. Combine these factors, and you realize that the distortion of the entire image of Andromeda is negligible. |
If our skin regenerates every 27 days, then how do tattoos last a lifetime? | Tattoos only need to be 2-3 layers deep...Only our top layer of skin really 'regenerates'. When a fresh tattoo heals, the top layer peels off like a sunburn, & the ink stays underneath. We can't get ink to stay in that thin top layer, because it sheds off. Feet & hands have more layers & are replaced faster, which is why tattoos don't stay as well in feet/hands. If you have a tattoo & get a deep cut or scrape, the ink is taken out, & will heal with a 'hole' in the tattoo. |
Wouldn't pesticides have to be non-water soluble to resist rain? If so, what is the point of washing fruit and vegetables before eating them? | Pesticides used directly on food crops are not supposed to resist rain, at least not to the extent that they persist and poison people. Pesticides are often washed away by rain which is often part of the guidelines for use - rain can shorten the preharvest interval that is needed before crops can be harvested. The pre harvest interval is needed to ensure that the pesticide levels are below maximum guidelines (Maximum Residue Limit) required by regulatory agencies. Normally the use directions will specify weather conditions suitable for spraying (such as avoiding spraying before a rain and during high winds). Also, a pesticide that can't be mixed with water would be pretty hard to apply. |
How is light pulled toward black holes if photons have no mass? | Because gravity isn't an interaction between two masses. Classically it is, but that's because Newtonian gravity is a low energy approximation to general relativity. Gravity is actually an interaction between various things (including mass) and *spacetime*; since light travels through spacetime, it can't avoid being affected by gravity. |
Despite the both being governed by inverse square laws, why are planetary orbits elliptical but atomic orbits are circular (in the classical model)? | The people who developed the classical model didn't exactly know how the electrons were moving around. They just noticed that the electrons were moving around the nucleus *somehow*. The development of the classical model was an extrapolation that fit with the data at the time. That's why classical electrons orbit the nucleus, travel in circular paths, and have defined positions, even though modern electrons don't. It was the simplest explanation. The physics of planetary movement, on the other hand, are accurate models. That's why all the intricacies have been developed and standardized. They actually act like the model. Electrons don't. |
Can there be two planets close enough that they share a moon in a figure 8 pattern around both bodies? | Sort of. It wouldn't exactly be a figure 8 pattern because the planets would be orbiting each other, so the moon could only switch orbits during certain alignments of the three bodies. More likely, you would have two stars with a planet that switches orbits between them. |
If global warming ramps up C02 in the atmosphere, wouldn't that potentially cause plants to grow bigger and faster as it got worse? | Yes. Current co2 levels are just over 400ppm. Most plants will grow more with co2 levels up to 1200-1500ppm. When getting higher co2 they do better in slightly warmer conditions than if they are getting normal amounts of co2. I dont think this will make it harder for humans to live or go outside though. |
If our universe is expanding at certain rate which started at the time of The Big Bang approx 13.8 billion lightyears ago with current radius of 46.6 billion lightyears, what is causing this expansion? | Another important concept to understand is that nothing in the universe is *traveling* faster than light. Galaxies moving away from us at 400,000,000 m/s aren't actually moving through space that fast. What is happening is the "metric expansion of space time". In other words, space itself is what is growing. As an analogy, imagine a 4x4 grid that is 1" per unit at t=0. You are at (0,0) and there is a planet at (2,2). We can see with the Pythagorean theorem that the distance to that point is sqrt(8) inches away. Now, the way to think of metric expansion is that at time t=1s, you are still at (0,0) and the planet is still at (2,2). We would say that the planet isn't traveling right? But now our initial 4x4 grid is 2" per unit. And our new distance is sqrt(32) inches away. The object is now 4 times further away, but its actual position on the grid is the same. What has changed is the *size of the grid (space) itself*. |
Why does cyanide kill you so quickly? | Cyanide can be ingested, inhaled, or absorbed through the skin. It acts by blocking the cytochrome C oxidase enzyme which is an essential part of intracellular oxygen utilisation. What this means is that the cells can no longer use oxygen at a tissue level, no matter that they are being supplied at adequate amounts. Thus you are in effect suffocated. This explains why it acts so quickly - it is a small molecule that can be absorbed easily, and its mechanism of action is on oxygen utilisation. |
How does cyanide kill you? | It inhibits mitochondrial function. It's a cytochrome c oxidase inhibitor. |
Why do LCD monitors have fixed refresh rates? | This is an appropriate question for askscience. Anyways, a fixed refresh rate makes sense for LCDs. They hold their images between refreshes, so they don't "flicker" like CRTs do. You want the entire LCD screen to refresh at the same time, to eliminate "tearing" of the image, but you don't know exactly how fast the image will be coming it. So the solution was to create a maximum frame rate, and to always refresh at that rate. A variable refresh rate wouldn't have any real advantages, except for possibly very minor energy savings. |
Why do modern LCD monitors stick to the refresh rate model of CRTs? | _URL_0_ This is a decent source to read and answers your question. Anyhow, CRT frame rate was is better than your average LCD monitor now days. CRT monitors were usually equivalent to 75hz - 85hz. LCDs on average are 60hz. The source I posted stated that it has to do with the electrical standards of America. Ignore what people say about the human eye and mind when it comes to refresh rate. There is a lot of false information out there in regards to this. The human eye sees way more than 60fps. The human eye can also perceive things to be smooth even with things at something much lower, like 24fps. This is explained in the article I linked as well. |