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Why is it harder to balance on a still bike than a moving one?
People will say the gyroscope effect of the wheels, though a more important factor is the self-correcting nature of the steering mechanism. As you move and start to fall one way, you steer into it and bring the center of gravity back into balance.. it's a constant balancing act. It's much harder to do this when you are not moving. bikes with counter-rotating wheels to counter the gyroscopic effects are still easy to ride and stable.
Neurologically speaking, what makes a child's brain better at learning new skills and languages than that of an adult?
Lack of myeline around axons makes new synapsis easier to form, and our cerebral axons get myeline coats from age 25 or so onwards. A very young child also has quite a bit more neurons than will have as an adult, and those will make a massive ammount of synapsis. Most of those will end up being pruned. Our species retains brain plasticity well into adulthood, but we lose a bit of it.
If the universe is expanding and accelerating, is time expanding too?
No, just space. Distant objects in space are getting farther apart by about 70 km/s/megaparsec, and getting older by one second per second.
What causes meteors and asteroids to explode mid air when entering an atmosphere?
Air resistance... asteroids move at ridiculous speeds we can't even comprehend like 10s of thousands of mph... ever stuck ur hand out a car window on the motorway and felt how much force is pushing back? It's basically that times 10,000... also at them speeds there is a massive amount of heat generated by friction with the atmosphere... so basically anything entering the atmosphere is simultaneously being melted and blown apart by air... kinda Not the most scientific explanation sorry :) I'm just trying to make it easily understandable
Could a planet exist in a binary star system at the common center between the two stars? Could it be terrestrial?
In a binary of 2 massive objects, we'd usually consider it a [Roche potential.](_URL_0_) which is just the gravitational potential from the two bodies in the corotating reference frame of the orbit (so there's an angular momentum term). The equilibrium point between the two isn't the same as the barycenter (unless they are of equal mass in circular orbits, but that's a special case and doesn't change the scenario anyway). It's an unstable equilibrium point, so a small nudge causes a runaway to one side or the other. It's like trying to balance a pencil on its point.
how dangerous is it if a microwave does not turn off when you open the door (and you routinely forget this fact)
> The radiation produced by a microwave oven is non-ionizing. It therefore does not have the cancer risks associated with ionizing radiation such as X-rays and high-energy particles. Long-term rodent studies to assess cancer risk have so far failed to identify any carcinogenicity from 2.45 GHz microwave radiation even with chronic exposure levels, i.e., large fraction of one's life span, far larger than humans are likely to encounter from any leaking ovens. However, with the oven door open, the radiation may cause damage by heating; as with any cooking device. Every microwave oven sold has a protective interlock so that it cannot be run when the door is open or improperly latched. > There are, however, a few cases where people have been exposed to direct microwave exposure from malfunctioning microwave ovens, or where infants have been placed inside them, resulting in [microwave burns](_URL_0_). Buy 'em a new microwave oven - they are pretty cheap these days.
Why does the middle east have so much oil?
This doesn't directly answer your question, but keep in mind that the significant *known* oils fields in that region are not a singular occurance. Check out [this graphic](_URL_0_). Further, [shale reserves](_URL_1_) may also affect the preconceived notions that some folks have about where the oil really is.
Why does eating spoiled food which has been cooked still make us sick?
Food may spoil and become toxic or irritating if a certain kind of bacteria infected it and left behind toxins or concentrations of something our bodies will reject. Also, certain bacteria can survive relatively high temperatures for short times like dormant botulism spores. Once bacteria gets moving and colonies form, things become complicated. It really depends on how cooked it is and what was infecting it, but usually the typically cooking time/temp isn't sufficient anymore. A few moments at 155F (required temp for ground beef in Illinois) may not kill a developed infection, but 10 minutes at 250F will sterilize anything. *source: I am food safety and sanitation certified by Illinois*
Is it possible to have a moon orbiting a moon?
Tangentially, minor planets (that is, asteroids) can have moons, too. The first discovered was [243 Ida](_URL_0_). The wikipedia page linked has a photo. Ida has an average diameter of around 20 mi. Its satellite, Dactyl, is less than a mile wide.
Why yawning is sometimes contagious?
Mirror motor neurons being heavily associated with evolutionary advantage make us more prone to yawning when we see someone yawn, form the shape when speaking the word, or hearing someone else yawn. Just think about it 👍🏻😄
if radio is an invisible form of electromagnetic wave does that mean I could make an antenna that emits light? (providing I used the right freq)
Antennas have to be sized for the EM frequency they are transmitting/receiving. Simple antennas are usually 1/4 wavelength or 1/2 wavelength long. Let's take a nice green 500nm light. So now we need an antenna that is 125nm or 250 nm long, which is tiny but you could do it using computer chip fabrication techniques. Now the problem is you have to apply an oscillating electric current at the frequency of the EM signal you want to produce. For our 500nm green light, this frequency is 600 terahertz. This is orders of magnitude higher than anything we can achieve with normal electronics.
If a star runs into a giant cloud of Hydrogen will that extend the stars life?
No, stars can't really accrete material very effectively because their radiation pressure blows surrounding material away. Also, interstellar gas clouds tend not to be very dense, so they wouldn't add a significant amount of mass to a star even if it could accrete.
Why do industrial refrigerators like in supermarkets not attempt to cool the entire room?
They do attempt to cool the entire room. A little. But the refrigerators are built to circulate the air internally and not pour cold air into the aisles, so the effect is minimized.
Why does food reheated in a microwave always lose flavor?
Microwaving is basically like boiling the water already inside the food.
When one looks at the night sky with the naked eye can one see other galaxies or is one only seeing other stars?
[Here](_URL_0_) is a list of galaxies visible to the naked eye. Of course, in the types of lighting conditions you find in the average populated area, you will probably not be so lucky. And the ones on the list with magnitude above 6 are not ones would count on being routinely visible, even in a dark area.
Why does body hair reach a maximum length as opposed to our head hair?
> hair on our head which we need to cut or it will grow out forever This is factually incorrect. Both body and hair hair behaves the same. All the hair continues to grow. But after some time, some individual hairs fall off. So if you stop cutting your hair, it will continue to grow, until equilibrium between falling hairs equalizes with growth speed. It probably won't look nice, but it won't grow forever. (source : I haven't cut my hair in 10 years and it haven't gotten past half my back since then) The only difference between different types of hair is how log before individual hairs fall out.
Do freckles block UV radiation?
Yes they do. Freckles are patches of skin that have a high concentration of a biological pigment called [melanin](_URL_2_). Melanin is one of the key pigments associated with darker skin, and importantly in this case, it is a key photo-protector (a substance that protects skin from UV damage). This makes more sense if you look at the [absorption spectrum](_URL_0_), notice how it is both broad (making skin appear brown), but also peaks in the UV. Due to the strong absorption of the UV, melanin basically acts as natural sunscreen, which is why people who are pale are so much more susceptible to sunburns. The strong UV absorption is also why freckles [stand out so clearly in UV images](_URL_1_).
Is there any way to increase the number of dreams I have?
Keep a dream diary. I can only speak for myself but it worked wonders for my dream recall.
Why are mosquitoes more active at dusk?
Many mammals in hot areas of the world are crepuscular (most active at twilight hours). The reason for this is to conserve energy during the hottest hours of the day. Since mosquitoes thrive in hot climates, it makes sense that their peak activity would coincide with their primary prey population: crepuscular mammals like deer. Additionally, it may be easier for a mosquito to sense the heat coming off of a large mammal at dusk, when the surrounding environment is cooler.
Do atoms have a color?
It's wrong to say that your example atom is blue because that is a property of the bulk which depends on the manner in which the atoms are organized. Consider [graphite](_URL_1_) and [diamond](_URL_0_), both are (or at least can be) purely carbon, however they have different optical properties.
Would pi be as difficult to perfectly describe using a different number system?
If a number is irrational in one base, it is irrational in every (integer) base. The notion of irrationality doesn't depend on base as can be seen from its definition: A number is irrational if it can't be written as the ratio of two integers. Pi is irrational because there are no integers *m* and *n* such that *m* / *n* = pi.
Do SSRI's actually contain serotonin or do they cause the body to produce more serotonin?
Neither. Your body naturally makes serotonin even if only a little. To prevent too much accumulating your body you will naturally reabsorb it to keep levels stable. But sometimes you don't have enough and SSRIs block this reabsorption allowing levels to grow. That's the 'reuptake inhibitor' or RI part of SSRI. That said details on _exact_ mechanism of action aren't fully understood.
If both hydrogen and oxygen are flammable then what is it about water that means it puts fire out?
Oxygen is not flammable. Oxygen it a high-energy gas that very readily oxidizes other materials. For something to burn, the reaction requires a fuel (the thing that burns) and an oxidizer like oxygen. When the reaction happens between the fuel and the oxidizer, the sub-product (water, in your case) has a lower energy than the original energy of the fuel + oxidizer. This extra energy is what is released during the burn in the form of heat and what causes the flames. In a similar fashion, if you wan't to separate the water into Oxygen + Hydrogen again, you have to give back this energy that was released somehow... Electrolysis is one common example of how to do that.
Have we already discovered moons with "moons" on their own?
There is no reason why it couldn't, its just going to be hard to get the orbital mechanics to be perfect, but there are systems with 7 stars in creative orbits around each other so it could happen. Since the two moons will be relatively close together in mass they will likely orbit each other similar to a binary star system and the pair will orbit the planet. It would make orbital dynamics in the region rather creative, but I can't find anything that explicitly excludes the occurrence. One reason we haven't found anything like that yet is because we have a hard time picking up planets outside of our own system, and most of the planets we have found are Jupiter sized. Spotting even a Mars sized moon around that planet will take a while longer, and spotting a moon around that moon even longer. We are getting there, but since ~90% of the moon we know about are Jupiter's and Saturn's and we discovered a new Jovian moon in 2011, we still have a ways to go before we start picking up exomoon
Why don't modern cellphones create interferences near speakers any more?
My iPhone 6 makes my guitar amp buzz. Any elaboration on that?
Why doesn't the water spill out of water coolers when you flip a 10 gallon water bottle onto it?
The blue collar at the neck of the jug has a plug that gets pushed in or punctured when it's placed on the dispenser. **Edit** It's been brought to my attention that this is only the case for every one I've ever done, and may not apply to all water bottles.
If the pancreas is the organ that produces insulin, why aren't pancreas transplants used as method to cure diabetes?
[They are](_URL_1_). Pancreas transplantation has been done since 1966, and to date, over 28,000 pancreas transplants have been performed in the US alone. - Another option is to transplant only the [pancreatic islets](_URL_0_), which contain the insulin-producing beta-cells.
Why can't we perform a Pancreas transplant for those with Diabetes?
Type 1 diabetes has been treated with transplants of the pancreas islet cells which produce insulin. Interestingly, the cells are injected into the liver where they happily produce insulin. The problem is rejection and limited supply of donors. It is still experimental, but has helped people who had very unstable blood sugar levels. > [If the cells are not from a genetically identical donor the patient's body will recognize them as foreign and the immune system will begin to attack them as with any transplant rejection. To prevent this immunosuppressant drugs are used. Recent studies have shown that islet transplantation has progressed to the point that 58% of the patients in one study were insulin independent one year after the operation.](_URL_5_)
How does your body regulate hair growth on areas other than your head?
All hair, even on your head, has a pre-set growth period. If you did not cut your hair, it would get to a particular length, stop (rest), and naturally be shed, just like all the other hair. What determines length includes gender, hormone levels, and ancestry (people from colder climates are more hairy), and is all part of the cell cycle of the hair follicle. Some hairs live for years, others only weeks.
With sleep deprivation, what is the actual cause of death when beings are subject to sleeplessness?
As fair warning to this, I am not an expert on sleep, neuroscience or sleep disorders. I saw no answer so I did a little checking around to see if my understanding was correct. Long story short? No one knows the precise reason, especially not at the level of brain chemistry alterations. What happens when you are severely sleep deprived is hallucinations, dramatic spikes in blood pressure, panic attacks, loss of coordination, decrease in motor skills, rapid weight loss after prolonged periods of sleeplessness and eventually coma and death. I'm sorry I can't source this very well, but you might want to read this: _URL_4_ It's not qutie the question you asked, as FFI is a prion disease, but it does give us some insight into the effects of severe sleeplessness. *Edit for spelling x.x
Why is tire pressure constant with a heavier load.
The pressure does increase as you add weight. It doesn't increase as much as you might expect because the added weight also flattens the tire against the ground, increasing area over which the air pressure in the tire can exert force on the ground.
Why are other galaxies accelerating away?
You might wanna read up on the [metric expansion of space](_URL_0_) before pondering this question.
If light can be bent or affected by gravity, why is there not a consistent star-like glow coming from outside black holes?
The black hole can only suck in or deflect away as much light as is incident on it. If there's a black hole freely floating in the galaxy, it's only deflecting an amount of starlight similar to what we see from Earth. That's not much light for us, and it's even less when deflected which will spread it out more, leaving less directed straight at us than hit the black hole in the first place. In the case where a black hole passes between us and another star, though. We definitely see the effects of that light bending. The "two stars" in [this image](_URL_1_) are actually one star whose light has been [gravitationally lensed](_URL_0_) by a black hole passing between us and the star.
Why do birds often stand on one leg?
Until someone with more knowledge comes along - a BBC new article on [Why flamingoes stand on one leg](_URL_0_)
When I transfer data to my external hard drive using a USB cord why does the rate of the transfer constantly change (60mb/s to 90mb/s) throughout the transfer when my computer is doing nothing else?
There's a couple factors that can influence this. 1. Are you transferring one big file, or a whole folder full of different sized files? There's overhead to create and finalize each file written to a file system, so lots of small files will slow down the overall transfer speed. 2. How populated is the hard drive? Disk fragmentation can happen when a disk has handled lots of writes/deletes over its lifetime, and its especially bad with plug and play drives that are formatted as FAT32. If there's a large uninterrupted block on your drive to write to, the speeds will stay high, but once it has to start searching for random places to store files, the speed goes down.
In the distant future, will human garbage landfills become pockets of oil?
The earth went through a phase called the carboniferous period wherein cellulose and wood lignin had evolved, but no organisms capable of metabolising it existed. Thus the plants could grow and grow and grow and lay down biomass that was effectively nonbiodegradable plastic. Nothing could eat it, nothing could process it, it just choked huge areas of the surface until it built up so thick that layers upon layers of wood and lignin compressed eachother endlessly. Most of the coal we have today came from this. Our landfills are tiny in relative scale and dimension, and we are likely to eliminate most waste through composting and recycling long before we lay in the trillions of tons necessary to form coal.
Meteor Showers occur when the Earth passes through dust left by a comet, I've been told... so why doesn't that cloud orbit the Sun as well?
It's all orbiting the Sun in a big elliptical orbit and not usually in the same plane as the Earth.
Why does the debris from comets stay in the same place each year, causing consistent meteor showers?
> Or does it orbit the sun in exactly the same orbital path as the comet itself? That is exactly correct. Without any significant work done on the dust particles, they have no choice but to occupy the same orbit as the comet. The comet's entire orbit is dusty.
If a giant meteor crashed into Earth and destroyed the dinosaurs, why isn't there a crater? Has it just eroded/filled in? Or is it here, just not widely known?
There likely is a crater. The current leading candidate for which crater in particular corresponds to that event is Chicxulub: _URL_0_. Why was the crater hard to find? Much of it is, indeed, the change of land over time - erosion, "filling in", the growth of vegetation, etc. Earth conceals craters pretty quickly on a geological timescale. By comparison, planets or other bodies with neither an atmosphere, a hydrosphere or a biosphere retain their craters in an easily recognizable shape for a very long time - most obviously, the Moon. All of those things make it hard to find the crater in the first place; then there's the matter of figuring out the exact time the crater was created. Current consensus is that it matches within the boundary of experimental error to the extinction event, though a few scientists disagree.
What would happen if we detonated a nuke in space?
[It looks like this.](_URL_1_) _URL_0_ It generates a lot of gamma rays, resulting in an EMP which can damage or destroy electronics and a persistent radiation belt which can destroy satellites.
How is it that both SSRIs and SSREs are both effective antidepressants, despite having the exact opposite mechanism of action?
Theyre not necessarily opposite function. Ssri's increase the amount of serotonin in the synapse, which allows more serotonin to saturate receptors. Ssre's however, despite their name, do not increase serotonin to be removed from the synapse, they increase the sensitivity of serotonin receptors, meaning more serotonin is taken up which would other wise not be utilized by the receptors.
If all anti-depressants (SSRIs in particular) are supposed to do the same thing, why are there SO many varieties? And why are they all considered equally valid?
Same end result but: 1) Different mechanisms to reach that result 2) Different absorption, breakdown, metabolic properties 3) Different side effects due to mechanism of action 4) Different drug interactions 5) Genetic polymorphisms that control drug interactions People in fact ARE very different. Some people may have enzymatic activity which can vary as much as 80-100% from one another. Maybe one person metabolically digests a particular SSRI so quickly it never has a chance to have an effect, while another metabolizes it so slowly that it causes toxic build up. Some drugs might be renally eliminated while others are eliminated in your liver. If a person has kidney failure, one of those drugs might kill them. Etc
Why is helium a finite resource?
For anything to be deemed a resource, it has to be worth more than the effort required to acquire it. This economic concept underlies pretty much all of our resource acquisition activities, notably mining. At present, commercial Helium production is a by-product of oil and gas extraction. He is produced through radioactive decay in the mineral substrate, and trapped in solution in hydrocarbon fields. When these deposits are extracted, He is separated and stored as a separate phase through fractional condensation. There are traces of He in the atmosphere, but these are so dilute that recuperating these is uneconomical. In this context, it is economically recuperable He which is a rarefied resource.
Can two moons of a planet, over the long term, share the same orbit height/apogee/perigee but with different angle, without colliding?
[_URL_4_](_URL_3_) may or may not be helpful. he [Saturnian](_URL_1_) moons [Janus](_URL_2_) and [Epimetheus](_URL_0_) and probably the most famous examples. However, I don't think they exactly share an apogee or perigee (which would technically be an apoapsis and periapsis, since 'gee' only refers to Earth)
Why is it easier to walk uphill than to bike?
On a bike, you have to provide all of the force to keep the bike form rolling backwards down the hill *plus* all the force to move you forwards. On foot, the force that prevents you from sliding backwards is provided by friction.
If white objects reflect all wavelengths of light, then why aren't they mirrors?
This is the difference between specular reflection in which an incident ray of light is reflected as a ray in one definite direction, and Lambertian (or [diffuse](_URL_0_)) reflection in which an incident ray of light is reflected in all directions away from the point of incidence. A lot of objects which appear white are made from materials which are both colourless and transparent in bulk but which have some sort of rough texture or granular structure that leads to strongly diffuse reflection or transmission of light.
How did water and carbon dioxide exist on early Earth if the atmosphere at the time had no oxygen?
Yes, by weight, oxygen is the most abundant element in the Earth's [crust](_URL_0_) and [mantle](_URL_1_) - but it is primarily found in the form of various oxides (quarts, aluminum oxide, etc). For reasons I don't personally understand, the [gasses emitted by volcanoes are mostly water vapor and carbon dioxide](_URL_2_)
Is a blank 15 minute MP3 the same size as a 15 minute MP3 of music?
With CBR encoding, yes, by definition. Bitrate is constant. If you use VBR encoding, then the encoder would (should) be smart enough to make your silent file really really small.
How can people be allergic to eggs but not chicken?
Proteins are made out of building blocks called amino acids. When someone has a food allergy, their immune system overreacts in response to a certain nutrient. In the case of an egg allergy, it reacts to a protein in the yolk or white (or both). These proteins differ from those found in chicken meat. So someone can be allergic to a specific type of protein in the egg without being bothered by the different kinds of protein found in chicken meat. The chicken is able to produce the egg by rearranging amino acids into different kinds of protein molecules. Our own bodies also make different kinds of proteins. For example, hormones are often proteins.
Why don't spiders get stuck in their webs?
Their webs use many different types of silk. Some are elastic, some are strong, and some are sticky. They can also mix these properties as necessary. They know which will lines are sticky a d simply avoid stepping on them. Some also have a coating on their feet which helps avoid issues.
Do plants suffer from viral/bacterial infections like animals? Do they have immune responses?
In addition to what /u/TheRedguard said, we routinely use an agrobacterium to genetically engineer plants. The agrobacterium uses horizontal gene transfer to cause tumors, but we insert its DNA into plants. We add whatever DNA we want to the bacteria and they infect the plant, conferring cold tolerance, drought resistance, any number of traits (assuming we have the correct genes).
Why don't we have monthly lunar and solar eclipses?
Mostly because of the inclination of the moon to the Earth. The moon is inclined 5 degrees relative to the Earth and so rarely lines up with the sun. [A diagram.](_URL_0_)
When did "sleeping" evolve? What are the most primitive organisms that we know of that sleep?
Tangent question, is sleep what evolved or the state of being awake? As in, did multicellular organisms first evolve to walk around, eat, reproduce, then sleep and recover.. or did they evolve to stay in a neutral state then get up, eat, and reproduce?
Why is it so hard to fully delete computer files?
What storage type/file system were your files stored on? A lot depends on the block allocation strategy and journaling algorithm (if any). Naively written programs might assume that whenever they overwrite a data block at a specific offset in the file, they're accessing the very same physical area as before. Reality is that many modern file systems dynamically remap blocks to improve performance through - say - asynchronous serialised writes, implement wear leveling, and so on... On such setups a properly written shredding program must be filesystem aware and access the physical storage while the volume is in a quiescent state, or inquiry the OS about the actual physical location of data pages. That aside, more levels of indirection may be enforced by the hardware controller itself, defeating the purpose of shredding. TL; DR: if you want safe storage disposal, use encryption or sanitise the whole volume, because physical access to the storage is not likely to be accessible to the OS
How much thrust is needed to accelerate spacecraft by 1g in space ?
Those things (EM drive, etc) are a scam. By the way, the thrust is acceleration * mass. So 1g * mass of the rocket in kg = thrust in Newtons.
Why does processor performance increase faster than RAM performances?
RAMs are interconnect dominated - so the larger you make each bank, the slower it will get. Each bit-cell in RAMs have been getting much faster, but the problem is that the interconnects get worse at smaller technology nodes. This is bad for interconnect dominated systems. Secondly, your off chip memory (DRAM) is usually not limited by the speed of the RAM, but the speed of the bus. The wires on the PCB are *huge* compared to the wires within the chip. Lastly, you do see the impact of smaller device sizes on the capacity of the RAM, not necessarily on its speed. Back in 2007 I was running a laptop with 64MB DDR RAM and was perfectly satisfied. Today, my phone has 2GB.
What performance enhancements would one notice from adding more RAM to a computer vs increasing the processor speed?
RAM is essentially for holding the data it needs to perform current tasks. So, the tasks and programs you are asking the computer to run simultaneously will affect how much RAM you should ideally have. If you want to use a metaphor, it's the size of a contractor's truck. It will limit or enable the contractor to hold more materials/tools to do his/her work while taking fewer trips. The processor is essentially for the thinking and calculating that your computer has to do. So it determines the speed with which the computer will perform tasks as long as it's not waiting for data to load into memory. In the same metaphor as above, this is the contractor's speed with which he/she will do actual work once all the required materials and tools are at the site. TL;DR You have the general gist of it, yes.
Do violent video games increase aggression in people?
I remember writing a paper on this last semester. While the APA official statement says violent media results in violent behavior, there are plenty of research studies that show this is not the case and many researchers are prodding the APA to revise their statement. From the handful of papers that I read, it looks like by controlling for the correct variables, you will not see any correlation between violent media and violence in children's behavior. The actual correlation seems to be between parental involvement with their kids and less violent behavior.
Are there any known computational systems stronger than a Turing Machine, without the use of oracles (i.e. possible to build in the real world)? If not, do we know definitively whether such a thing is possible or impossible?
Usually when we talk about hyper computation we ignore runtime complexity. If we just look at what problems are decidable, we believe that no stronger model exists. But if we look at runtime, quantum computation has (at least) a provable quadratic speedup over classical turing machines (grovers algorithm). In the real world we are also not restricted to serial computation. Pi calculus captures parallel semantics and can also compute some problems faster than serial turing machines.
Why does the tilt of the earth affect the seasons more than the aphelion and perihelion cycles of the orbit?
The angle of the sun at different seasons results in about a 2:1 variation in light intensity, and the difference in day length results in a similar impact on total light hitting the ground per day. The end result is something like 5x as much solar energy hitting the earth per day in summer vs winter at 45 deg latitude. That's vastly more than the meager few percent change due to orbital distance.
Why did animals get so much smaller after the asteroid wiped out most of the life on earth?
also, less oxygen meant plants got smaller, so herbivores got smaller, so carnivores/omnivores got smaller.
Is it possible/economical for the garbage company to extract raw materials from your garbage?
There's [plasma arc waste gasification](_URL_1_). Garbage is shredded and heated to 9000 F without oxygen. Everything decomposes to basic elements. The flammable vapor from destroyed organic compounds (soot, methane, carbon monoxide, hydrogen) is siphoned off to be burned elsewhere to run a turbine to power the plasma arc which is superheating the garbage. The fraction of the garbage that doesn't become a gas becomes slag and recyclable metal. These machines do generate [a fair amount of gold](_URL_0_) suspended in a solid solution with iron or copper if you feed them gold-rich electronic waste. Why is this not everywhere if it destroys garbage, doesn't make a lot of pollution, makes a bit of excess energy, and shits gold? Because it costs $20 million for a new plant. They're catching on anyway though because that's really not that bad compared to expanding a full landfill or trucking garbage long distances.
Why does water put out fire, if water is hydrogen and oxygen?
This has been asked numerous times, as recently as yesterday. Please search before asking common questions. _URL_3_ _URL_1_ _URL_0_ _URL_2_ Edit: sorry, you're right that your question is slightly different. As others have pointed out, water is not just a mixture of hydrogen and oxygen, it's a compound comprised of hydrogen and oxygen. They can combine in an oxidation reaction to give off heat, but water is a product of this reaction. Water will not spontaneously decompose into oxygen and hydrogen to provide more fuel, as this is thermodynamically/chemically impossible, so water itself is not flammable.
Why does my shampoo come out of the bottle green, but the soap bubbles in my hair are white?
I am not a scientist. But here is my guess. Layer Thickness. The shampoo poured directly out of the bottle is thicker than any layer of a bubble, which foam already is... Due to the thin layer in a bubble more light can "travel" trough the shampoo an is not reflected, or doesn't interact with the electrons of the shampoo moecules. Maybe if you could make a bubble with a layer as thick as ~5mm you could see some patterns in original shampoo color (from black to green fore example) _URL_1_ _URL_0_
How important are the expiration dates on food really? Obviously it's certainly an issue for perishable food, but do the expectation dates really matter for dry goods and canned food?
It is probably safe as long as it never got wet. Dry sugar lasts a very long time but flour can get rancid. I would taste a pinch of the mix to see if the flour has gone bad. I would also mix the mix up some to make sure it doesn't contain insects, hard lumps or discoloration (signs that it got wet at some point or possibly that bugs got in the flour). Another issue with the flour is that it may lose the ability to rise, so your muffins may not rise as well or at all. Some artificial sweeteners (Aspertame being the one I know of) also go bad (bitter tasting instead of sweet). Check the shelf life of the ingredients of the mix. Sugar has historically been used as a preservative alongside salt (stuff like dried fruit). Flour is made by grinding up seeds very fine and so it contains oils that decay after a while. Here is a decent article about expiration dates in general: _URL_0_
Is it possible for a moon to orbit inside the atmosphere of a gas giant?
No, for two main reasons. The tidal forces near the gas giant would be great enough to disintegrate the moon (the Roche limit). Even if this weren't an issue, the drag forces from the gas acting on the moon would cause its orbit to decay (this is why the ISS needs to keep re-raising its orbit).
if fusion in stars that go supernovae stops at iron, from where did we get heavier elements here on earth??
Fusion in supernovae doesn't stop at iron. It stops at iron in regular stars.
What happens to drugs after the date of expiry? Do they become harmful?
When you read "unstable," it meant that the chemicals in the medication may have fully or partially broken down into other chemicals (or it might be almost entirely the same, but the manufacturer simply didn't study the shelf-life of their product for quite so many years before marketing it, and the drug is still perfectly good). Any new chemicals (breakdown products) may simply be ineffective such as in the case of expired epinephrine, but there are reports of some toxicity in specific cases (tetracycline is one commonly taught in medical schools even if the evidence has been questioned). In your example, [this study](_URL_1_) found a toxic breakdown product of ibuprofen after forcing accelerated degradation. If you want to know about specific cases, search PubMed for research on the "beyond-use" date or "stability" of the drug.
How can our galaxy be on a "collision course" with Andromeda when Hubble's Law says galaxies are accelerating away from us?
The gravitational attraction between the mass of our galaxy and Andromeda's is stronger than the repulsive forces of the Universe's acceleration. We won't have to worry about crashing into other galaxies in our near future either because (as far as I know) we are too far away from them for our the gravitational forces to be significant enough to overcome the repulsive force form the Universes expansion. TL;DR We are on a "collision course" with Andromeda because the gravitational force between our galaxies is stronger than the repulsive force from the expansion of the Universe.
Why can I smell heat? What's actually going on in my nose/brain?
I don't know but are you sure? How do you know the space heater is not burning dust and that is what you smell?
Can you shoot a gun, fatally, in space? What would happen?
yep, gun powder has its own oxidant in the mix. So it will fire just fine in a vacuum, temp wont matter much to it. no reliance on gravity, the bullet would not lose any velocity either, so it would keep going forever or until it got pulled into a planet.
I'm an identical twin: my brother and I both have daughters. Can they be considered half-sisters?
In the scenario you describe, the two daughters would (on average) appear to have the same degree of genetic similarity as half siblings. Extending this idea, if two sets of identical twins had children, then the children of the two couples would exhibit the same degree of genetic similarity as full siblings, rather than cousins.
Why is visible light safe for animals?
Unless the photon energy is enough to ionize molecules in our skin the energy will dissipate as heat.
If humans and ants were the same size, which would be stronger?
Are you talking about shrinking a human to the size of an ant or enlarging an ant to the size of a human? This is a complete non-answer, but humans adopted to be most efficient at their current size and ants adopted to be most efficient at their size. We are very different animals, we are not even in the same phylum; we have endoskeletons they have exoskeletons. An ant enlarged to size of human will have high ratio of volume to surface area and hence might not be able to stand up on it's own strength. It may not even be able to breathe normally, and instantly die. I don't think humans would fare much better at ant size with our complicated organs and such.
Would it be possible to get a sun tan on the moon?
Due to the lack of a magnetosphere and atmosphere on the moon, if you were to expose your skin to the sun, you would have a few problems. You would certainly get sunburned, but that would be just the beginning of your problems. Without the protection of a spacesuit, you'd be getting bombed with ionizing radiation from a couple sources - the sun as well as background cosmic radiation. You would also be affected by neutrons bouncing off the surface of the moon. Short answer : without a spacesuit, you'd get so much cancer, the cancer would have cancer. _URL_1_ _URL_0_
Why can't we taste as well when we have a stuffy nose? Does taste also come from being able to smell food?
Short answer is yes. Flavour is a complex interaction between your taste buds and your olfactory senses.
How would the size of an asteroid relate to the amount of damage it would cause the planet?
*Layman here* You could try to put these inputs in asteroid simulators and compare the results. [Link 1 - the most popular one "Impact Earth" ](_URL_1_) [Link 2](_URL_0_) [Link 3](_URL_2_)
What size must an asteroid have in order to completely destroy planet Earth?
Depends on the velocity, but there's certainly no asteroid in the Solar System even remotely capable of doing anything close to gravitationally unbinding the Earth. The Earth's gravitational binding energy is about 2 x 10^32 J. The kinetic energy of an object (assuming its velocity v is much lower than the speed of light) is KE = 1/2 m v^(2).
What's the genome length limiting factor in the new '$1000 Sequencers'?
Only being able to sequence 70k seems unlikely to impossible (it would largely be pointless). Having a single polymerase sequence 70k is actually incredibly good. Usually individual sequences will be 75-150 base pairs long to maybe 500 for genomic sequencing (sequence millions of little sequences and align them like a puzzle to get the full sequence). Some of the newer sequencers will do 10k ish reads, though i have heard there are some issues with the fidelity of the sequence). Also normal sequencing of a targeted sequence (part of a gene for example) will be say 100-1000 bp). Basically you're using a biological system. The longer the the DNA sequence that is copied (which is a part of the sequencing process). The more likely the reaction is to terminate, or that an error will be made. Usually when you receive sequencing data back the start and stop of the sequence look terrible with the best quality sequence being in the middle.
Why does alcohol feel colder on the skin than water does?
Alcohol is a more volatile liquid than water, so it evaporates more readily. When a liquid evaporates from your skin, it pulls off heat, since in essence, evaporation is the set of the most energetic particles in a medium (see the Boltzmann distribution) "boiling off", removing their kinetic energy from the liquid, and cooling the skin. This is why humans sweat when they get hot. Because alcohol evaporates more readily, it soaks up energy faster than water, and cools your skin more quickly.
When I drive with my windows down, why do I hear a "whoosh" sound when I pass by an inanimate object, like a mailbox, as if I was passing another moving car?
Your car is pretty noisy. It's moving a lot of air around as you drive, not to mention engine, exhaust, and tire noise. When you pass something very close to your car, the sound generated by your car is reflected back at you.
How come when I drive by a parked car, I hear a "whoosh" noise?
The sound produced by the movement of air, engine, tires and other parts of your car is reflecting off the parked car and back to your ears. When things are much farther away than a parked car, the reflected sound doesn't make it back to the location you were until you've already moved out of the area. The whooshiness of the noise is due to the doppler effect shifting the pitch up a bit as you approach and down a bit as you retreat from the stationary car.
If stars stop fusion at Iron (Fe) then how did heavier elements come about?
The reason star fusion "stops at iron" has to do with the binding energy/nucleon in atoms. [Here's](_URL_0_) a little graph that shows you the relevant numbers. Note the turn at mass number 56, iron/nickel-56. At that point, fusion is no longer viable, and the star cannot support its gravitational collapse with it. At this point, a positive feedback loop occurs as the star begins to collapse very rapidly under its own gravity. The resulting influx of matter is incredibly fast (as fast as .2c if memory serves), but it is halted very abruptly by degeneracy pressure. This results in a rebound, or supernova. These so-called core-collapse supernova are massively energetic, enough to produce elements more massive than iron.
Why are solar panels on earth blue, but in space (ISS) they are gold?
It's not gold, its printed copper circuitry. See _URL_0_ for a nice close up picture.
Is there any chance the asteroid belt in our solar system could coalesce and form a planet?
If you are asking "Could it one day happen naturally", no. They're really spread out, and the nature of their movement is really really chaotic. If it could have happened naturally, it would have happened by now. If you are asking if there is enough mass there, the answer is YES! Ceres, the largest asteroid (now termed a dwarf planet), may have more (fresh) water than earth has. Further Reading _URL_3_
Where does Jupiter's color come from? If hydrogen is colorless, and Jupiter is mostly hydrogen, then what's going on?
"Mostly hydrogen" gives away that it isn't only hydrogen. A smaller but not insignificant portion of the atmosphere is composed of other gases, such as helium, methane, water, ammonia but also colored molecules such as ozone (blue), but particularly nitrogen oxides (brown, red, orange). These more-colored compounds require high ionization energies. I would guess, but are not 100% certain that the colored regions are regions in which more ionization occurs, such as lightning (storms, high winds, more friction) and solar radiation (poles).
Do all solar systems have the same plane of orbit?
> So, do all solar systems, share the same plane of orbit or are we only able to discover a certain (unknown?) percentage of existing plants and solar systems with the above technique? The [latter](_URL_2_). > Conversely, if so, what other techniques for exoplanet discovery are there, both theoretical and perhaps already in practice? Stars and planets orbit their common center of mass. Since this is inside the star (or close anyway) we say that the planet is orbiting the star. But the star will also appear to "wobble". It's also [possible](_URL_1_) to directly image a planet, though so far it's pretty difficult. The bad astronomer [talks](_URL_0_) about exoplanet-related issues fairly frequently.
Why do blue (and to a lesser extent green) LEDs appear to be so much brighter than the warmer tones?
Are these monochromatic (single color) LEDs? Or are they white LEDs with a colored cover/bulb?
Are diamonds bulletproof?
Oh heavens no. The important thing to remember is that 'hardness' generally only refers to the materials' resistance to compressive forces. Basically - a 'harder' material can scratch a 'softer' material. It tells you very little about that material's other properties. Diamond, while incredibly hard, is not particularly tough - which is resistance to fracturing. In fact, it's commonly repeated that diamonds can be shattered with a well placed whack of a hammer.
When eating spicy food why does it seem like the food is getting spicier as you eat more?
I'm not a sensory neuroscientist but I believe this has to do with both the type of stimuli and your pervious exposure to the stimuli. There are Vanilloid receptors that play a role in these systems. [Here's](_URL_0_) a good review.
Is it possible to use The Hubble Telescope to look at the interstellar asteroid in our solar system?
It is done. Hubble had a look at it several times. _URL_0_
What would happen if a planet size object collided with a star?
Very little, presumably. Even a "little" star is orders of magnitude larger than a "big" planet. The largest planet we've ever seen, WASP-17b, is roughly 1.7 times more volume than jupiter (and, roughly, about the same mass) The smallest star (And I'm hesitant to call it a "star", seeing as it doesn't maintain the fusion reactions we come to expect from "stars", as such it's a very 'dark' object) we've ever encountered, OTS 44, is 1% the size of our sun, but is still 12 times as heavy as jupiter. Outside of outliers, a "big" planet would simply be annihilated by the massive gravitational pull of the star. A big star wouldn't even notice in any sort of magnitude scale the difference a small planet would cause it.
What is the process used to make seasonal flu vaccines BEFORE the flu season comes? Who does it?
[This page] (_URL_0_) answers the question thoroughly. The answer is that the WHO and other health agencies make an educated guess during the previous flu season which strains they think will be prevalent the following year. The guesses are not always completely right.
How are flu vaccines made every year before flu season?
The World Health Organization (WHO) announces the most likely candidates of the main strains (H1N1 Type B H3N2) before the flu season starts (which is just when illness spikes - the viruses are around before then) there is also the flu season of the other (depending on which you are) hemisphere to consider (seasons being reversed) a universal solution is, of course, hoped for - so that reformulation wouldn't be necessary (and so that production wouldn't lag behind demand) (there's also the issue of culturing in fertilized eggs - other options are being researched)
Does distance from the center of a galaxy affect the average make up of stars?
Closer to the center of a galaxy the fraction of heavier elements ("metals") is higher. This influences the distribution of star masses, but I don't have a direct comparison now. It is expected that we live somewhere in the ideal range for potentially habitable planets. Far outside you don't have enough heavier elements for rocky planets, and close to the center you have to many supernovae ruining atmospheres and too many stellar fly-bys for stable and quiet planetary systems. Not that it would matter much today - most of our exoplanet searches are limited to stars nearby anyway.
Could a planet be at the midpoint between binary stars?
They could have a planet which orbits one or the other of them and thus periodically comes between them (even passing through the midpoint if the stars are of significantly different mass and the planet is in a wide orbit around the larger star), but the midpoint of two equal-mass stars is not a stable location.
Why do your limbs tingle after they fall asleep?
It come from your nerves "waking up." You can have a limb in a position that cut or reduced the sensory signals that are sent to the brain. Then when the connection is restored, the tingling is your brain sensing everything (like pretty much the weight of your own skin) before it remembers to filtering it out.
You're in a stopped car with the windows closed, a horsefly is 'hovering'; Upon accelerating the car, does the fly remain in the same position in space, or does it hit the rear window?
A fly's motion is based on the objects it is in contact with, as well as the gravitational pull of the Earth. A fly would be hovering because the force exerted upwards by the air on the fly's wings is balanced out by the gravitational pull of the earth. Now, if the car were to accelerate, it would bring all of the air with it. Some of the air would be compressed towards the back of the car, which would cause the fly to go backwards a bit, but regardless, the fly should be able to hover there. You can test this with a helium-filled balloon. Be aware of the tension force from the string (you cannot tie it down).
What are the advantages/disadvantages of an engine with more cylinders compared to one with less cylinders but both have the same displacement.
One of the biggest advantages of having more cylinders (with the same displacement) is reduced vibration. An engine with more, smaller cylinders will generally vibrate less than a comparable engine with less cylinders because fewer cylinders means larger, heavier pistons are required to sweep the same volume. Larger, heavier pistons also are generally not as well suited for high-revving, as they put more inertial force on crankshafts, journals, etc. The main tradeoff is a simpler design, as fewer cylinders will not necessitate as complex a design. Of course, being an extremely general question, there are many other variables at play.
Why hasn't another planet or dwarf planet formed in the asteroid belt between Mars and Jupiter?
Our understanding is that a typical planet did not form in that region because the gravitational effects of Jupiter prevented the matter there from coalescing into such a large object. There is one dwarf planet -- Ceres -- in the asteroid belt, but the rest of the objects don't fit that bill. [Ceres](_URL_0_) holds about 1/3 the mass of the entire asteroid belt.