question
stringlengths 19
300
| answer
stringlengths 28
1.02k
|
|---|---|
How do the "small, rocky cores" of the gas giant planets maintain such huge atmospheres?
|
Not really answering the question but I feel it should be pointed out. We do not know if it does still have a solid core. Our models of planetary formation suggest that it should have formed from a solid core but it is actually not known if it still has one. It is quite possible the convective currents eroded the core to a smaller size, or to a fuzzy state or even to the point there is no core. It is really only popscience that speaks about the core of Jupiter like it is a known fact.
|
If you live on a planet 65 million ly away, if you have access to a telescope that could capture an image of Earth, and if you have access to a system that could enhance that image and allow you to zoom in all the way to within several feet of the Earths surface, would you see dinosaurs?
|
> Am I dumb for asking this? No. > If you live on a planet 65 million ly away, if you have access to a telescope that could capture an image of Earth, and if you have access to a system that could enhance that image and allow you to zoom in all the way to within several feet of the Earths surface, would you see dinosaurs? Yes. Light travels at 1ly per year. When we "see" the Sun we actually see it as it was 8 minutes ago not as it actually is. If it suddenly went out we would still see it for 8 more minutes. Looking into space is looking back in time and the further away you look the farther back you see.
|
If Radiation is cumulative in our body, is Bluetooth (even with BLE) harmful to humans if we are constantly exposed to it with cellphones, smartwatch, etc. and also from other's electronic devices around us?
|
There are many forms of radiation, with wildly different properties. Cumulative exposure happens with ionizing radiation, which is radiation that has high enough energy to ionize molecules and potentially cause damage to things like DNA. The more of that type of radiation that you're exposed to, the greater the chance that this cell-level damage turns into an actual medical condition. The radiation emitted by our everyday electronic has a lot less energy and is not nearly energetic enough to ionize matter. In fact, things like Bluetooth, wifi and cellphone signals use a form of radiation that is considerably less energetic than visible light. And not only is the radiation less energetic, there's also a lot less of it. Even sitting indoors, in a regularly lit room, your hit by far more radiation coming from the light source than from all of your electronic devices combined.
|
Is it beneficial to try to avoid coughing when sick?
|
Coughing can help to remove sputum plugs and other irritants from the lungs. It most definitely has beneficial effects. That said, an ineffective cough can be just as dangerous long term as it can hurt muscles and even lung tissue if continued for long periods. (this is very uncommon even among the extremely ill however) In a typical cold, so long as you're not coughing all over people It's generally accepted to cough as needed. Codeine is a cough suppressant, and as such is included in many cough formula's, and can be helpful before bedtime to allow one to rest more easily. Gaufanesin(I probably spelled it wrong, I always do) is an expectorant, meaning it can actually irritate the body and create a cough, and is also in a number of cold formula's.
|
How did researchers find out that we need sunlight to produce Vitamin D?
|
[_URL_0_](_URL_0_) & #x200B; Excellent article outlining the step-wise discovery. Scroll down a bit to the section about UV light. Basically, they first found the activated vitamin D product in cod liver. Then they found that irradiating tissues and oils without any active vitamin D but containing cholesterol-derived precursors to vitamin D produced the same effect as the active vitamin D, elucidating the role of UV light in producing active vitamin D. Although at this time all that was known was that there was some fat-soluble substance present in tissues that served an important role in bone health, nothing known about the molecular structure.
|
Rather than some made up 'dark energy', could the universe be expanding faster because we're being pulled by gravity towards something surrounding us?
|
If the universe were a football field, and galaxies are people standing on the field, the expansion of the universe isn't the people walking away from each other, i.e. it's not galaxies moving through space. It's the football field itself expanding while the people are just standing there (or walking slowly in their own directions because galaxies aren't stationary). What I'm trying to say is that the expansion of the universe is the expansion of space itself between objects, not the movement of objects away from each other through space.
|
How come when I tune to a radio station with no reception in my area, I hear static rather than silence?
|
You, friend, are listening to the background noise of the big bang, fluorescent light fixtures and highly differentiated bits and pieces of past 2.5 Men episodes.
|
How are radio stations able to broadcast silence and have it not sound like static?
|
I'm the chief engineer of a college radio station and since this is likely the only time I'll be abe to chime in with anything, I'd just like to add that, if I turn on our station and there's static, I know our transmitter is off, but if I turn it on and there's silence, I know there's no audio coming from the studio. Others have already done a better job than I could have explaining exactly why this is the case.
|
Could the new US Navy Laser Weapon System (LaWS) be reflected feasibly using a mirror?
|
No, and for several reasons. First, what you normally consider a mirror is only a mirror in certain wavelengths- aka, the visible spectrum (and extended a little on either side). The laser weapon is so far outside of the visible spectrum that it would just pass through. Secondly, even if you had a "mirror" in the wavelength the laser weapon worked in, the mirror would still have to absorb a lot of energy. Mirrors don't exactly reflect light, but instead absorb the light, and then re-emit it. A power laser would have too much energy for a mirror to absorb.
|
Could the US militarys powerful laser weapon be defeated using mirrors?
|
No. A mirror doesn't reflect 100% of the energy and even .1% loss to heat from a 100kw laser would be 100watts in a very small space. I think part of the key is if *current* military lasers are strong enough. That I'm not sure. But lasers in the near future, approaching megawatt ranges? No way in hell.
|
Are any animals scared of the dark?
|
You are asking if we know how the animals feel relative to human emotions. Such answers are always difficult, if not impossible, since the animals can't tell us what they are feeling. We can only read into their responses. Also, the amount of light that humans perceive as "dark" is not the same amount of light that other animals perceive as darkness. That being said, and if we compare to humans, we should probably be looking at group animals that are not nocturnal. Try getting your dog to follow you into a dark cave.
|
Why is the lather of a soap always white, no matter it’s original colour?
|
I believe it's the same phenomenon that makes a pile of sugar look white even though the individual grains are transparent. Light just bounces around a lot at all the air/sugar or air/water interfaces so the substance takes on the same color as the incident light. There's probably just not enough pigment in the liquid of the bubbles themselves to really alter that. I would wager that if you slice your soap very thinly, it won't appear to have much color anymore.
|
How can Hubble observe the necklace nebula from a distance of 15,000 light years if it's only 10,000 years old?
|
That's somewhat poorly worded by the NASA site, though it's very common to put things in these terms. They mean 10,000 years ago *as observed by us*, meaning 25,000 years ago. I almost always refer to things that I observe in the present tense though technically they did of course happen a long time ago. Nearly all observational astronomers pick up this habit, thanks for pointing it out, we should be reminded to be careful about this when reporting discoveries to those who might not be aware of it!
|
How does a flu vaccine lessen symptoms when you catch a flu variant that isn’t one of the variants in that seasons vaccination?
|
Your immune system recognises something as foreign (and potentially harmful) mostly by the proteins on the surface of the pathogen - we call these markers 'antigen'. The white blood cells that are especially good at recognising these antigen are T cells, and B cells. Each cell can recognise a single antigen - in theory. In reality, the T and B cell receptors have a bit of flexibility, and can recognise several different protein shapes that look *almost* the same, but not quite. This is called *cross-reactivity*, and is the reason why you can be vaccinated against one flu strain and still respond to another. This reaction probably won't be as strong, but it does give you somewhat of a response - enough to kick your flu a little faster.
|
Is it possible to develop our night vision?
|
It is not that easy. While our eyes do in fact get used to seeing in dark places it won't be easy for them to see perfectly. We have a series of light sensitive cells inside our eyes. Some of them get "burned out" when looking at bright light, but they quickly heal when no longer exposed to light. This causes us to "get used" to dark places. While they may take even a day to get completely healed, there can be no further improvement in their work after that. So long story short: not really.
|
Are moon rocks worth more than gold?
|
NASA considers moon rocks priceless. It is also, apparently, [illegal](_URL_0_) to sell moon rocks, as they're all national property. That said, they estimated the price of 285g (stolen and discussed in a court case) at $1m, so that would mean the price per gram is ~$3509/g. Gold's current spot price is $56/g.
|
What happens at the source of carbonated bubbles in a glass?
|
The bubbles form at spots of leftover bits of dust or grime or whatever that didn't get cleaned off fully. The cleaner the glass is, the fewer bubbles you will see. Bubbles have a hard time forming on glass itself because the CO*_2_* doesn't have anything to "stick" to in order to form a bubble. The CO*_2_* will come out of the drink whether there are bubbles forming or not, but for a bubble to form, you have to get a bunch of CO*_2_* to sit in the same place, which is hard to do on a clean glass surface. In other types of cup, especially the cheap plastic ones, you can see bubbles sticking to the side of the cup but not going up. This is because the coating they use is hydrophobic, so the liquid prefers to "stick" to a bubble than to the side of the cup. I believe that bubbles can form on plastic surfaces because plastic is generally less "smooth" than glass, so bubbles can coalesce in the little imperfect spots.
|
Why can't we just dump our trash into active volcanos?
|
Lava / Magma is only 2000 to 2500 F in temperature. This is far less than required to properly destroy many hardened materials. You would also have to deal with hazardous fumes. Secondly, only a few volcanoes are safely approachable in a consistent manner to make something like this even remotely feasible. So hauling the trash to those exotic locations would be expensive. Third, volcanoes are dynamic creatures and are subject to frequent change and unexpected behavior - which would make the logistics and safety issues not worth the cost. Edit: That said... when we hike to the volcano and play with lava we do indeed throw our trash in it.
|
How do insects, particularly mosquitoes, survive extremely cold winters?
|
Mosquitoes and many other types of insects enter a dormant state during the winter known as diapause, in which physiological and developmental activities slow down significantly. Such a state can be brought on by a number of different stimuli including photoperiod, thermoperiod, and allelochemicals. Note, however, these various factors must be within a certain range or for a certain period of time to cause diapause induction.
|
How do small insects, like spiders or mosquitoes survive harsh winters?
|
A common strategy is to synchronize their life cycle so that the more resistant stages (eggs or pupae) can weather the winter hidden or buried. Some others have special proteins that keep ice cristals from forming inside them, essentially avoiding freezing to death. Bear in mind that many won't survive, but there are so many that odds are in their favor, and one generation is enough to maintain the population from crashing. I hope that solves your question! (FYI spiders aren't insects, they are arachnids like scorpions and harvestmen. They are all arthropods though)
|
Via a similar process to electrolysis, could we extract a viable amount of oxygen out of CO2?
|
Yep, it's mainly called artificial photosynthesis, and it's arguably the largest unsolved problem in the field of inorganic chemistry. State-of-the-art systems can only consume millimole per hour quantities of CO2, which is obscenely slow, for a bunch of reasons.
|
Can we extract oxygen from CO2?
|
Sure. [You can hire a plant to do it for you.](_URL_1_) If that's not chemical enough for you, there is also active research in making [artificial photosynthetic cells](_URL_0_) that perform the reaction you are describing.
|
How do we remember smell?
|
How do we remember sounds? Everything is just information encoded in our brains, even muscle memory. Smells are known to trigger strong emotions/memories more than other senses, maybe this is what you're experiencing. What is really incredible is how we remember faces. Firstly, our brains separate the face from the rest of the image we're seeing and store just that part. On top of this the brain is combining many "images" of a person's face from different angles and in different lighting conditions. And somehow enough information is stored to distinguish one face from another very similar face.
|
Why do cancer cells consume so much sugar?
|
In addition to /u/baloo_the_bear 's points, cancers often have a modified metabolism, called the Warburg Effect. Basically, cancer cells, even in oxygen-rich environments, will use anaerobic respiration as a means of generating energy. This generates only about 5% of the amount of ATP that normal oxidative phosphorylation (the process that goes on inside the mitochondria) does. In order to make the same amount of energy, then, a cancer cell using the Warburg Effect would have to consume twenty times more glucose than a normal cell.
|
Please help clarify this this apparent paradox: The universe is expanding. The universe is infinite.
|
Let me clarify what the two terms mean. "The universe is infinite" means "If you pick any distance, no matter how large, there are objects farther apart than that distance". "The universe is expanding" means "If you measure the distance between two objects that are sufficiently far apart at one time and then at a later time, the second measurement will be greater than the first". That's all the two statements mean. Hopefully, those definitions clarify why there isn't a contradiction between them.
|
Would the photon sphere around a black hole be one photon thick?
|
Outside of the mathematically ideal, there are no stable photon orbits around a black hole. All orbits inside a photon sphere decay. The Schwarzschild model assumes an eternal non-rotating black hole inside an otherwise empty spacetime, but this is obviously an oversimplification. But for practical purposes a photon sphere can't be perfectly spherical. The presence of massive objects throughout the universe prevent spacetime from ever being so smooth.
|
Why does alcohol make you (feel) warm?
|
It opens up capillaries and vessels near the surface of your skin, making you feel warmer when you are cold because of heat that is now in your extremities. These capillaries would otherwise be closing to protect your blood from losing too much heat. If you are experiencing hypothermia, drinking alcohol will actually inhibit you from saving yourself because of these effects. As the capillaries open, more heat is released from your body resulting in your core temperature dropping more quickly because of more cold blood being transported back to your innards. Questions?
|
Why is CRISPR/Cas9 gene editing so revolutionary? How does it compare to the previous gene editing techniques (e.g ZFNs and TALENs)
|
CRISPR/Cas9 uses RNA to act as a guide for where it cuts the DNA. In comparison, ZFNs and TALENs use proteins to recognize certain DNA sequences. As such, CRISPR/Cas9 is easier to design the guide RNA to target a very specific sequence. CRISPR also has very high efficiency, and is now easy to design in such a way that there is no detectable off-target cleavage. CRISPR can also be introduced with several guide RNAs at once, allowing for multiplexed editing, compared to TALENs and ZFNs. In a sense, CRISPR isn't revolutionary, but evolutionary. It is the cheapest and easiest method of genome editing to date, and the number of labs that have adopted it is pretty staggering, considering how long it has been around.
|
What exactly happens when your ears are ringing, and why does it happen?
|
There are several things that can all produce the same ringing sound, but my favorite is [sponaneous otoacoustic emission](_URL_0_). In this case, your cochlear hair cells can actually generate noise that can be picked up with a sensitive microphone inserted in to the ear. In my understanding, only some of the hair cells actually pick up sound. The rest of them act as volume control by beating with or against the frequency they are leveling. To over simplify, the brain then receives a pair of signals - the leveled sound and the "gain" of the leveling hair cells. With otoacoustic emissions, something knocks the leveling control loop out of whack and those hair cells start beating without a tone present. For example, a doctor might play a tone and then stop it to measure how quickly the control loop responds. This can be used to detect hearing issues in young children.
|
What causes ringing in your ears?
|
Most of the cases of ear ringing (both temporary and chronic) are due to acoustic hyperstimulation of the hair cells, which become "leaky" and continue to signal "white noise" to the CNS. This leakiness is due to the stereocilia being bent: _URL_1_ When the ringing has been caused by something other than a loud noise, then there can be multiple causes, including nerve damage: _URL_0_
|
If you shot a gun in the opposite direction of travel while in a vehicle going the same speed as the maximum speed of the gun's bullet (a jet perhaps), would an observer at the point of ignition see a bullet just fall to the ground and tumble in front of them?
|
Caltech produced a retrorocket bomb in WWII for use in antisubmarine warfare. Some patrol aircraft were outfitted with a magnetic anomaly device, which could detect a sub directly below. The issue, of course, is that's way too late to drop a bomb. The solution was to take a rocket propelled bomb, mount it backwards, and have the plane fly at a fixed speed. Firing the rocket would then cause the bomb to drop straight down. Edit: Found a photo of "Retrorockets" on a PBY Catalina: _URL_0_ (PDF warning, page 9).
|
If I shot a bullet facing backwards on a moving vehicle with speed equal to the bullet's, will the bullet just fall down to the ground?
|
Yes. And in fact all bullets fall to the ground, regardless how fast they are going horizontally. Shoulder height is about 1.4 m. Any object fired horizontally will take 0.53 seconds to fall to the ground, the same as just dropping it, and that answer won't change regardless whether you're shooting a BB gun or a .22 or a high-power rifle. The only difference will be how far horizontally it manages to get in that half second.
|
Car engine: why does shifting up earlier/lower rpm consume less fuel?
|
My best guess is that by shifting earlier you don't let the engine rpm get super high, therefore reducing amount of fuel per second consumed. But by doing this you also lose out on the high rpm power range. If the engine is built correctly (cams etc), you can effectively shift the rpm where the engine has maximum power/torque to a lower range, allowing you to shift early without losing power.
|
Why does sound fade when I yawn? And what's with that bass sound when I yawn especially hard?
|
When you yawn, two things happen that affect your ears: 1. The eustachian tube opens. This tube equilibrates the pressure across your eardrum. It's normally closed to maximize the sound energy reaching your cochlea. When you yawn, some of that energy is lost to the tube (specifically, to an impedance mismatch - it becomes easier for some of the energy to bounce back out of your ear than to go forward). 2. One or both of two middle-ear muscles, the stapedius and the tensor tympani, get activated. These muscles serve to protect your ear from loud sounds by restricting the movement of the middle-ear bones. One of the loudest sounds you can make (in your own head) is chewing, so when your jaw moves, the muscles activate.
|
How did flowers and plants reproduce before there existed bees?
|
The way that plants get pollinated is based largely on the type of plant and the ecosystem. There are types of plants that can pollinate themselves or use the wind to carry their pollen to other plants. In the same vein, there are other insects that can pollinate plants other than bees, but again this depends on the ecosystem. Honey bees themselves are a little percentage of pollinator insects. As a matter of fact, they are actually an invasive species that intrude on the other pollinators.
|
If Bees were not widely populated in the Americas until 1622, how did the flora survive?
|
The Western Honey Bee *apis mellifera* are only one of some 16,000 species of bees and the only one brought from Europe to the Americas for the explicit purpose of being managed. Prior to the arrival of Europeans the native bee species pollinated the native American plants but didn't have to worry about crops like apples which also came from Europe. You should also note that many of our crops are not pollinated by bees of any type: wheat, corn, other grains or are not native to the Americas: apples, citrus, almonds.
|
Is there a taste equivalent of olfactory fatigue?
|
The taste sensations depend upon solutes in our food and drink binding to proteins, 'taste receptors' in the lining of the oral cavity, often gathered into tufts in the epidermis of the tongue. This binding reaction has a forward and backward rate constant, binding < -- > unbinding. If a tastant binds rapidly but unbinds slowly, the taste sensation persists. This is why many artificial sweeteners leave a persistent sense of sweetness long after saliva has rinsed the drink or food away. So, in general, at the cellular level, little sign of receptor adaptation is seen. OTC, central fatigue in sensory systems is an essential feature of managing sensory bandwidth.
|
Why do spiders always curl their legs when they die after being killed by bug spray?
|
Disclaimer: Wikipedia knowledge only, not an expert. When spiders die their hearts can no longer supply the [hydraulic pressure](_URL_0_) that they use to extend their legs; as a result, the previously tensioned ligaments (probably not the right term) contract causing them to curl up.
|
If time goes so fast when we dream, why do people who talk in their sleep speak at a normal pace?
|
Because time isn't moving faster when we sleep. Relative to us it is because our conscious is deactivated, therefore we aren't capable of perceiving time. Time is relative, it doesn't actually change speed.
|
How do we take pictures of our galaxy if we are in our galaxy?
|
Assuming you mean plan view, we don't. All images like that described as showing our galaxy are either digitally (or manually) produced images, or images of other galaxies similar to ours. We can see the milky way in our sky, and being on the outer limb of one of the arms we see it as a broad band of stars dominating one hemisphere of sky. It's in profile. We have no photograph taken that shows the milky way in plan view.
|
When I dream, is my visual cortex being activated or is it merely a thoughtform?
|
_URL_0_ Summary article on dreaming TL;DR yes your visual cortex is active
|
If skin is constantly shedding and renewing, how do tattoos remain permanent?
|
It goes into the dermis, the second layer of your skin, below the epidermis, so it doesn't get recycled as often as the epidermis. If I remember, this is the reason why tattoos fade slowly over a person's life.
|
Why do some stars and objects in space flicker different colours?
|
As the air in Earth's atmosphere moves, it distorts different wavelengths of light differently, and so sometimes you see different amounts of different wavelengths, causing [twinkling, or scintillation](_URL_0_).
|
Do mirrors 'bounce' the photons or do the atoms in the mirror absorb the light and then reemit it a few instances later?
|
Photons exhibited both particle and wave properties. When a light wave hits a mirror then the wave can propogate away on all directions, but all cancel out by destructive interference except one that matches the angle of reflection. The particles trajectories, when calculated via quantum electro dynamics, also experience a similar effect.
|
Is there truth to the belief that your maternal grandfather indicates whether or not you will experience male baldness? I.e. if your mother's father is bald you will likely be bald.
|
Yes, there is some truth here. Male pattern baldness is in many instances, a sex-linked trait which means it is carried on the X chromosome ([ref](_URL_0_)). As a male (XY), you will get your X from your mom (XX) who got one from her dad, and one from her mom, which is what makes this trait recessive in women but dominant in men. There are other factors that contribute to baldness as well as other genes that aren't on the X which can cause it, which is why there is *some* truth to this, but it isn't a hard and fast rule.
|
Hangovers: Why do they exist and why is there no cure?
|
Have you read the [hangover wiki](_URL_0_)? It goes into pretty good detail about what is thouht to cause hangovers and the effects of alcohol on your body. The biggest effector in my opinion is that alcohol inhibits the effects of Anti-Diuretic Hormone(ADH) also known as Vasopressin. Without the effects of ADH your kidneys lose the ability to reabsorb water in the collecting duct and no longer concentrate your urine. Prolonged effect of alcohol on the kidneys will lead to dehydration, which is thought to be the cause of the majority of the effects of an alcohol hangover. The cure for a hangover is to drink a lot of water before you go to bed or *stop drinking so much alcohol*. Moderation is your friend here and will lead to less intense or even no hangovers at all.
|
Why do humans get goosebumps when they are cold? What is the advantage of this
|
Goosebumps make your fur stand on end so it traps more air and improves the insulation. It doesn't really work for humans, since their coat is so thin, so they don't have any advantage from it, but it hasn't gone away yet. Other animals have it, and get use out of it.
|
What is the medical difference between clear, watery snot and thick, yellow snot?
|
Thin and clear mucous is standard, however a thick yellow mucous is an indicator that your immune system is running against some form of an infection. The change in color is due to the presence and function of a type of white blood cell called a neutrophil. You can think of neutrophils as the first responders of your innate immune system; they will generally be the first white blood cells to respond to an infection. These neutrophils will attack the infection by releasing histamines which will in turn attempt to neutralize or destroy the source of the infection. This process is what changes the color and viscosity of your mucous.
|
Are there any known stars that exist outside of a galaxy?
|
[Searched](_URL_3_) Relevant [discussion](_URL_0_) Original question by [kornork](_URL_4_) > In The Universe series (check out the alien galaxies episode), travel through space between galaxies is shown with lots of stars whizzing by. Shouldn't it be mostly empty? Top comment courtesy [HappyMeep](_URL_2_) > Yes, intergalactic space is mostly empty, except for things like hypervelocity stars, which have enough speed to escape the gravitational pull of a galaxy. > The misconception that intergalactic space is full of stars could be due to images like this one: > _URL_1_ > It appears as though there are stars floating around this galaxy (Andromeda), but the stars are actually located inside our own galaxy - we're merely looking past them in order to see Andromeda.
|
Is breakfast the most important meal of the day?
|
This question, and similar questions, come up a lot in AS. You can find some good discussions in old threads: _URL_1_ _URL_3_ _URL_0_ _URL_2_
|
Can the type of wood affect the sound in an electric guitar?
|
This is the physical mechanism of how the wood can affect the *amplified* sound: the whole guitar is a system of coupled oscillations. The strings vibrate, which causes the neck and bridge to vibrate, which causes the wood to vibrate. The pickup detects the vibration of the string, which includes a mix of frequencies (harmonics) in addition to the main note. Some harmonics can vibrate in concert with the wood vibrations better than others, and will be sustained for longer. However, without doing complicated calculations, I don't know how much of an effect this will have.
|
Does the type of wood in the body of an electric guitar significantly affect the tone of the guitar?
|
The wood composition of the guitar does contribute to the tone of the guitar. The guitar is still a mechanical resonator, even if you are using active pickups you pick up the oscillation of the strings, and the oscillation of the strings also depends on the resonator you are hooked up to. If you're using piezo pickups then it is even more sensitive to the shape and type of wood the guitar is made from. Despite what /u/swordfingers has stated modern electric guitars *do* have cavities- if there are tone blocks added, for instance, and so this does have an impact of the sound. It is not the only factor, there is also the touch of the player, quality of strings, amp settings, pickup quality and so on. But wood material *does* affect the tone of a guitar.
|
Shouldn't all multicellular organisms develop some sort of cancer given enough time?
|
They do. Its just the fact that human body is well able to defend itself against such changes that we see so little cancer - cells either kill themselves off with apoptosis if they mutate, or are killed by an immune system before most cancers have any chance to develop.
|
How can I smell heavier-than-air substances like metal?
|
Well, it's not the mass but the volatility which describes if something becomes gaseous. It depends on the intermolecular forces, how strongly the stuff sticks together, which is more related to the _size_ of molecules than their weight. (e.g. radon is a gas and water a liquid at room temperature, even though a radon atom weighs almost 5x as much as a water molecule. It's just that the mutual attraction of radon molecules is far smaller) Anyway, metals aren't very volatile at all either. And the truth is that you _don't_ actually smell metal. The 'metal smell' is actually [oct-1-en-3-one](_URL_0_) and a few other compounds, which are formed by the reaction of the fats on your skin with air and metals.
|
Why is pure carbon typically black when most carbon containing compounds aren't?
|
The color of an object depends on the arrangement of the atoms, the bonds between molecules, and the ability of the electrons to move with the electric fields. A black object absorbs light. The other carbon-based objects simply have a different electronic structure that provides more light scattering (absorbs less light)
|
Why didn't all the matter and energy of the big bang just create an extremely massive black hole?
|
You're assuming that gravity and the expansion of space are somehow linked. They're not. Spacetime expands regardless of what gravity has to say. Separate the two. Expansion is a property of spacetime. Gravity is a consequence of spacetime.
|
Why is carbon used for all these awesome things (carbon fibre, carbon nano tubes, etc)?
|
It's more that carbon is such a flexible atom when it comes to making molecules. You can do so many things with it because it can take on so many different valencies, make so many different kinds of bonds, and arrange itself into so many different molecules. Metals typically do not have the same level of flexibility as carbon.
|
Why do humans seem to forget more as they get older?
|
It's more a decrease in the ability to store things in short term memory and to transfer short term memory into long term memory. Remembering things stored in long term memory prior to loosing the ability is mostly intact, just normal forgetting long term stored things or maybe some loss of that, also. It really has nothing to do with "quantity" of stored information. It does not happen to everyone. I have met many people in their 80's and 90's who seemed to me to have no loss of mental capacity at all.
|
If nitrogen is vital for amino acids, enzymes, peptides, proteins etc. Why do we not use the nitrogen available in the air?
|
"Fixing" nitrogen gas, that is, turning into a chemically useful form like ammonia, nitrate, etc., is actually a very difficult chemical step. The N2 molecule is very stable, and breaking those bonds takes some real work. Up until the early 1900s, the only organisms on earth that could do it were some species of bacteria, and everything else living on earth depended on that steady stream of nitrogen feedstock. The enzymes that do it have been studied intensively, but the detailed mechanism of the reaction is still being debated. Then Fritz Haber and colleagues found a way to make ammonia from nitrogen gas in the air (via a high-temperature metal-catalyzed process). That's what has kept industrial civilization going ever since, especially in its role of making agricultural fertilizers. The Haber process, with modifications, is still being used on a huge scale today.
|
Are temperatures below absolute zero hotter than Infinite Temperature? If so why?
|
[Here](_URL_0_) is an old /r/AskScience comment which has put into an FAQ by /u/rantonels. But the bottom line is **yes**, if "hotter" means "more internal energy". If you have a system which can exist at a negative absolute temperature, that system will have more internal energy at a negative temperature than it will at **any** positive temperature.
|
Could we ever retroactively recycle the trash in your landfills?
|
_URL_0_ According to almighty wikipedia it's been done since 1953.
|
Why Titan has atmosphere and other, larger moons don't?
|
Larger moons? The only one larger is Ganymede and there is evidence of a thin atmosphere on Ganymede. Not to mention Titan is a million km from Saturn, while Ganymede is a million km from Jupiter. Being near Jupiter is probably a really bad place to be when collecting material from the gas cloud that the solar system formed from. Take a look at the [relative masses of objects in the Solar System](_URL_0_) and be amazed. Looking in from outside there are only two things here: the Sun and Jupiter. With maybe hints of a third object: Saturn.
|
Can a food completely devoid of liquid be cooked in the microwave?
|
Yes, of course. Microwaves heat up food through simple dielectric heating, not through resonance with water molecules. I take it you have never warmed up dry rice packs in the microwave.
|
What causes the pee-shudder?
|
Everyone, this has been covered multiple times, and the only real definitive answer to it is " No one really knows" Please stop posting about your personal experiences with it. Even the [wiki](_URL_0_) page has no real resources.
|
Why does screaming help to relive pain and/or fear?
|
IIRC it is a symptom of living in coordination with others and other species. Whimpering/screaming is sign of pain that seems to elicit sympathy or, in the case of fights, gives the other party a sense of victory, much akin to bowing your head and walking away. It's been a while since I took a behavioral biology class, but hopefully my comment helps stem your curiosity until an expert comes.
|
Are expensive shampoos actually any better for my hair?
|
See these old threads: _URL_2_ _URL_0_ _URL_1_ **TL;DR**: Use whatever makes you happy.
|
Do insects sleep? Do they dream?
|
[Wikipedia](_URL_0_) suggests that insects exhibit sleep-like behavior. Unfortunately, since their behavior is so simple, it is difficult to tell exactly what is sleeping. The studies Wikipedia describes base their conclusions on the fact that sleep-deprivation causes the insects to lose cognitive ability. I can't find any material that suggests insects dream, and I consider it unlikely due to the simplicity of their nervous systems and limited cognitive abilities. It would also be difficult to determine if and when they do dream, if they did.
|
Where did all the carbon dioxide come from?
|
There are two main theories about the source of Earth's carbon dioxide. The truth is probably a combination of the two. 1. There was carbon dioxide in the accretion disc that formed Earth 2. Volcanic outgassing; volcanoes excrete a lot of carbon dioxide.
|
Astronomy: how did the universe go from a measurable size to infinite, aka not an actual number?
|
What makes you think it had to be a measurable size to begin with? It is a common misconception to think of the universe at the big bang as a single point. All we know is that it was very hot and dense. If the universe is infinite now it was probably always infinite
|
Are babies physically able to speak?
|
Theoretically, yes. The PHYSICAL components of speech should be able to perform the actions necessary to produce the sounds, but it's the neuronal connections that actually matter. It's not even a matter of 'mental capacity' as it is strengthening and pruning synaptic connections in all the structures required for speech and associating them with the correct areas of higher processing. If, for example, you could exogenously stimulate the lungs, vocal folds, tongue, lips, etc in the correct sequences, the physical structures themselves could produce speech.
|
Could there be bacteria in landfills right now evolving to digest plastics?
|
There are already bacteria which can eat some plastics. A nylon eating bacteria was discovered in 1975 and is one of the best examples of evolution in action Edit: It actually digests one of the byproducts of nylon manufacture _URL_0_ And there is good evidence of polyethylene digestion by bacteria too. _URL_1_ So it's quite probable that more microbes will evolve plastic digesting abilities for a wider range of plastics. Possibly some of these already exist at the bottom of landfills. Personally I don't doubt that we could direct the evolution of microbes to digest further plastics. The difficulty comes identifying which plastic will be amenable to enzymatic digestion and which microbes already have enzymes which with a little evolution will be able to accomplish such a task.
|
Is the Sun getting brighter?
|
[Here's a graph](_URL_0_) There's an 11 year cycle, but the variation in intensity is less than 0.1%.
|
Were does the Solar system fall on amount of planets it has? 8 planets seems like it could be above average.
|
Data on extrasolar planets hasn't been around very long as we haven't had the ability to detect them. At the moment estimates are 300 billion stars in the Milky Way and 100-200 billion planets in the Milky Way. > Are there upper limits for the amount of matter in a stars protoplanetary disk? (excluding multi-star systems) Yes. If the disc is too large then other stars would form (e.g. think of if Jupiter were large enough to be a star).
|
Why do animals eyes reflect light when humans don't?
|
Its from the Tapetum Lucidum. Its an extra layer in the eye of nocturnal animals that reflects photons so the eye can capture more. It's not in us because on bright sunny days where we are our most active, the last thing you want is more light in your eyes. edit: spelling
|
Why is does a pot make sounds right before the water starts to boil?
|
The water at the bottom of the pot is the hottest. This means that water will be the first to boil. But before the water is at a steady boil, the water at the bottom is already boiling and turning into a gas. But because most of the water around it is not yet at boiling temperature it will cool off the steam in the bubble causing it to collapse and make noise. Do this thousands of times a second and that's what makes the noise. This video will also give you some good animations and explanations of it [_URL_0_](_URL_0_)
|
Why didnt the early universe collapse in black hole shortly after the big bang?
|
Hi! This question is in our [Astronomy FAQ](_URL_0_), along with other questions about the expansion of the universe that you may find interesting. Check it out and let us know if you have additional questions!
|
Why didn't the universe collapse into a black hole immediately after the big bang?
|
One important condition for the formation of a black hole is that the spacetime away from your distribution of mass you'd like to be a black hole is asymptotically Minkowski, meaning it gets quickly flatter and flatter as you move out. This is not the case for the early Universe since it was homogeneous (all points were identical).
|
why do the carbons in graphene only have 3 bonds?
|
Each carbon atom in graphene is sp2 hybridized and bonded to three other carbon atoms via sigma bonds. The remaining p orbital is perpendicular to the plane of the carbon atoms, but it is most certainly not non-bonding; in fact, these p orbitals give graphene its remarkable properties. The electrons in the aforementioned p orbitals are delocalized due to resonance (or molecular orbitals, according to MO theory), similar to benzene, but on a much greater scale. Thus, there are partial double bonds in addition to the sigma bonds, and overall, each carbon has four bonds.
|
Is there a pi bond in graphene?
|
It's similar to the [conjugated system](_URL_0_) that you get with a benzene ring. Delocalized electrons come from the p orbital, and double bond lines are drawn, but you can also draw a conjugated system with dotted lines to represent the delocalized bonding.
|
Why does the moon have a bigger effect on tides, although it has a smaller gravitational attraction effect on Earth?
|
This seems to be about how the moon has a smaller gravitational attraction than the sun does, but the moon is the dominant factor in tides, if I'm inferring the right things about the question's context. What matters for tides is not the absolute force, but rather the difference in the force when you compare opposite sides of the earth. So, because the moon is quite close to us, there's a larger difference in the gravitational attraction on the close side of the earth to the far side then when you look at the same difference with respect to the sun. You can find a site that discusses this with the calculations and some helpful visuals [here](_URL_0_)
|
What do I smell exactly when something is dead?
|
The decomposition and putrefaction of biological material is associated with a number of different compounds, which give off the characteristic smell of death and decay. These compounds include: hydrogen sulfide, ammonia, [cadaverine](_URL_1_), [putrescine](_URL_0_), [skatole](_URL_2_), and butyric acid.^1 --- 1) Gennard D. Forensic Entomology: An Introduction. Wiley-Blackwell: 2012.
|
Why do speakers make weird beeping noises when a cellphone is working next to it?
|
That is simply the wires in the speakers picking up the electromagnetic waves sent out from the cell phone, as it sends a reply to a cell tower's query. _URL_0_ On a side note, my radio scanner can actually pick up the inner workings of my computer, if I tune it to the right frequency.
|
If boiling kills germs, why is rancid/rotten meat still inedible after boiling it?
|
Many of the bacteria that cause food poisoning produce lots of toxins which are chemicals rather than living organisms. If enough bacteria are present and producing toxins before the food is boiled, the toxins will still be present in sufficient quantities to cause the illness.
|
Do you still feel pain while unconscious.
|
Yes and no. Most people will wake when they experience pain. If they are prevented from doing so (by a coma for example) - provided their brain stem is still intact - they will still react to the stimulus. But [whether or not you actually experience it in the same manner you would while conscious is a matter still up for debate.](_URL_0_)
|
Can a star be so hot it is invisible to the naked eye?
|
No. As temperature increases, the intensity of every wavelength always and only increases. Different wavelengths increase more than others, causing the peak to shift, but still the intensity everywhere increases. If it's glowing at X-ray frequencies, it also glowing quite brightly in the visible as well.
|
Would it be possible for Jupiter and/or Saturn to ignite?
|
If you did mean set on fire as in a spark causing the hyrdrogen to ignite, no. Oxygen is required for hydrogen to combust, and the composition of Jupiter as far as we're aware contains only a very small amount oxygen. Also although not a very scientific approach, considering that it's 4.5billion years old now, if it were possible for it to spontaneously combust it probably would have done by now anyway.
|
Why does organic milk last longer than conventional milk?
|
Organic milk is preserved by ultra-high temperature pasteurization (138 C for 2-4 seconds). Regular milk is pasteurized at either ~63 C for 30 seconds or so, or ~70 C for 15 seconds. Regular pasteurization kills most things, but UHTP kills *everything*. UHTP milk can sit unrefrigerated on a shelf for about 6 months. But, UHTP also sweetens the milk by caramelizing some of its sugars. It can also turn milk slightly brown. Most Americans won't buy warm, brown, sweet milk though. Organic dairies use UHTP because their milk has to last longer because it usually has a longer trip to make it to most consumers.
|
Why do I hear a ringing when I have headphones on and walk through the (I think magnetic strip reading) security scanner by the library door?
|
Basic explanation because I'm lazy: Headphones work by altering the magnetic field around a magnet connected to a cone. The magnet moves because the magnetic field around it changes (by altering the current in a coil around the magnet), making the cone push air, creating sound. I would imagine that the magnetic strip reader has a constantly changing magnetic field (through the use of alternating current), which makes the magnet jiggle back and forth, causing the cone to move etc. If you record the whining noise, it should be the same frequency as the alternating current in the detector. If the detector works at the same frequency as the power supply (the outlet), you should be hearing a 50Hz whine.
|
When passing through library entrance/exit scanners while wearing earphones, why do I hear a faint buzzing?
|
The scanners use an oscillating electromagnetic field. The speaker in your earphone contains a small magnet attached to the speaker cone, which is normally how electric signals are transformed into sounds for you to listen to. In this case, the external electromagnetic field also causes the magnetized speaker cone to oscillate, which is why you hear the buzz.
|
Can a Universal Turing Machine Simulate Another Universal Turing Machine?
|
Yes. Proof: 1. Any UTM is capable of simulating any Turing machine. 2. Every UTM is a Turing machine. 3. Any UTM is capable of simulating any UTM.
|
Is there any known natural process that can not be theoretically simulated on a universal turing machine?
|
I'm not sure exactly what you're going for but here's a possible answer. A universal turing machine is deterministic. It cannot generate randomness. So a truly random physical process cannot be duplicated perfectly. [Radioactive decay](_URL_0_) is such a process. Of course you can be pseudorandom, which leads us to the definition of "simulation". What actually counts? OTOH, the universe is probably finite, which means there are a finite number of quantum states the universe can take. A quantum state takes a certain amount of information. You could simply encode that much random data on the input tape, and then you'd have a sufficiently large pool of randomness to simulate anything without the machine actually needing to generate it. But random means random, so you're not going to match what happens in the real world exactly, which takes us right back to the meaning of simulation.
|
Would the world have started off as a Pangean style land mass and then moved to what they are now or started as multiple different land masses that became Pangea?
|
There is no way to know what the paleogeography of the very beginning of Earth looked like, because there is just too little surviving material to make out a decent picture. However, it seems most Archean crust was closer to Oceanic crust than continental. It is hypothetised that the first continental crust of the Archean world involved some type of granitisation: as magmatic chambers associated with oceanic crust differentiated, they produced progressively more quartz-feldpar rich liquids, which ended up with the emplacement of buoyant granite intrusions in the otherwise dense oceanic crust. In that respect, the first nubbins of continental crust would have been these relatively minor island-like bodies of granitoid rocks and volcanic centres dispersed throughout the oceanic plates (not unlike the area surrounding the Philippines and the Indo-Malay archipelago), which would have later coalesced in larger masses through accretion along subduction zones.
|
Is there a genetic distinction between "races"? Or are the variations between ethnicities the same as the variations among them?
|
It varies. Some groups do fall into to some degree of genetic distinctiveness. So for example it turns out that Ashkenazic Jews are genetically distinct enough from other Eastern Europeans that one can tell with near certainty if someone in the US has Ashkenazic ancestry. [Source](_URL_0_). At this point this seems to matter more for medicine (different diseases are more common among different racial groups and some medicines are more likely to help people of different racial groups) than to have any ev psych implication.
|
Is there a genetic difference between the races?
|
Intelligence is up for debate, but there are so many environmental factors that can affect the results it's hard to make a definitive call. For example: malaria causes brain damage. It's presence in a very, very large segment of the sub-Saharan African population makes it difficult to sort environmental causes of low intelligence from genetic. And that's not factoring in language issues or cultural differences. As far as I know about studies of this area in America (where malaria isn't a factor, and language and culture are mitigated), intelligence is most closely related to the socio-economic status of the parents.
|
Do the planets ever eclipse each other from Earth's perspective, and if so how often does this happen?
|
Any two planets can align themselves such that one (the closer) is in front of the other from the perspective of Earth. I don't know exactly the periods of this occurring, but it is a geometric problem to understand that it does.
|
Since m = E/c^2, how can photons have energy, but no mass?
|
E=mc^2 is true for objects at rest, but photons are never at rest. The full equation is E^2 = (mc^2 )^2 + (pc)^2 , where p is the momentum. So, for massless particles like photons E=pc, i.e. their energy is related to their momentum.
|
If space is expanding, does that mean if two objects A and B, stood x distance appart, and never moved, that over time, the distance/space between them would increase because space is expanding?
|
The short answer is yes, but only if the interaction between the objects is weaker than the expansion. Systems bound by gravity, or by any other forces for that matter, will remain bound indefinitely, assuming an expansion rate constant in time.
|
Are galaxies vibrant and vivid as pictures portray or they really dull to the human eye?
|
They would be duller. Consider this: We're INSIDE a galaxy right now. When you look up at the spiral arms of the Milky Way you can see it, but it's dim. In some instances, near any sized city with street lights, you can't see it. This is because most stars are pretty dim at a distance. If we can't see our own galaxy clearly and vibrantly from within its boundaries, standing outside the galaxy (which would put us even further from the stars that make it) would probably look even more dim. To fully see an entire galaxy one must be quite far from it. But, the further you get the dimmer the light gets. So, no, you can't see a galaxy as vibrantly and rich as a picture can see it. Here's a neat [EXAMPLE](_URL_0_) of how big the Andromeda galaxy *actually* is, but we can't see it because it's so dim.
|
Can you make a laser-knife out of a laser going through a half-silvered mirror (or one-way mirror), and reflecting off a mirror?
|
You actually described [how a laser itself is constructed](_URL_4_). There are two curved mirrors inside the laser, one is partially transparent. The transparent one is the one the laser beam comes out of. In between the two mirrors is a device that essentially creates photons from electricity (gas, diode, etc) that shoot out in random directions. Photons that happen to go in the direction of the mirrors get amplified each time they go through the device. [Here's the wikipedia link if you want to know more.](_URL_3_)
|
If the universe is infinite, why is the night sky black?
|
"Olbers' Paradox is pretty simple: if the universe is infinite, and is filled with an infinite number of stars, then when the sun goes down, all we should see is a sky full of light. There shouldn't be any black background for stars to twinkle against, or night vision, or shadowy alleyways full of criminals to give superhero movies a dramatic start. Darkness should be exotic, because every star in the universe should be shining down on us at all times. Clearly, that isn't happening, but why? Because we live in a sad baby universe — it's only 14 billion or so years old, which is certainly a long time, but not long enough for an infinite amount of stars to illuminate us with an infinite amount of starshine. " _URL_0_
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.