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Dilb posted:According to the theory, whatever. Unless you're making a more subtle point that I'm missing? Position and velocity is enough. From the overall shape of the galaxy, we know that it's roughly circularly symmetric (i.e. we can see circles of matter with the same tangential velocity). From that fact and a gas cloud's velocity and position, we can tell what the matter enclosed by the gas cloud is. And as you said, it differs radically from what you would expect, looking at the stars. But that's not the only reason we can tell there's dark matter. A different formulation of gravity might solve the galaxy rotation curve problem, but it has a hard time solving both that and the other deviations we see in and around distant galaxies. I think I talked about this somewhere earlier in the thread. There are galaxies that seem to have a lot of light but little gravity, or a lot of gravity and little light. Dark matter explains this easily - the former is dark-matter-poor, the latter is dark-matter-rich (although there is a pretty strong correlation between dark matter and normal matter, there are deviations; there are also deviations with regards to how much light a given amount of normal matter gives off, but you can mostly correct for this by looking at the spectra and such). There is also evidence of dark matter in galaxy clusters, where we can see it through gravitational lensing. A lot of people resisted dark matter when it was first proposed, or continue to resist it - but they've yet to come up with a better explanation.
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Sep 27, 2010 03:39
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Dilb posted:There's also the issue of the speed of light. If a CPU works by signals getting across it and back, then the electrical signals, which travel at a large fraction of the speed of light, need to be able to cross that distance. A 500 GHz CPU, for example, can't be larger than 0.6mm if the signals travel across the chip at the speed of light. In one cycle, a signal does not need to cross the entire chip. It only needs to get to where it is needed.
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Sep 27, 2010 03:53
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squeakygeek posted:In one cycle, a signal does not need to cross the entire chip. It only needs to get to where it is needed. But, generically, it might be needed anywhere. Certain simple programs might be able to run much faster if they only use one tiny bit of the chip, true, but that doesn't make it a faster chip.
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Sep 27, 2010 03:54
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DontMockMySmock posted:But, generically, it might be needed anywhere. Certain simple programs might be able to run much faster if they only use one tiny bit of the chip, true, but that doesn't make it a faster chip. Processors are pipelined so they don't need to do everything in one cycle. Even something as simple as a wire from one part of the chip to the other can be pipelined to take multiple cycles to propagate.
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Sep 27, 2010 04:29
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squeakygeek posted:Processors are pipelined so they don't need to do everything in one cycle. Even something as simple as a wire from one part of the chip to the other can be pipelined to take multiple cycles to propagate. but we're still limited by the properties of semiconductors. theoretically if we could create a superconductive transistor connected by superconductive wires, it wouldnt matter how small it was. it could be as big as a table but the speed of energy transmission would be c. but where do we go from there? or am I wrong
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Sep 27, 2010 04:35
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I just got done reading the book Chaos by James Gleick - I know, Jeff Goldblum, Jurassic Park, blah blah blah. In your opinion, is Chaos a legitimate theory/science, and if so, how mature is it?
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Sep 27, 2010 04:49
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seo posted:but we're still limited by the properties of semiconductors. theoretically if we could create a superconductive transistor connected by superconductive wires, it wouldnt matter how small it was. it could be as big as a table but the speed of energy transmission would be c. but where do we go from there? Yeah, the transistors still take some amount of time to switch. Beyond that, I'm not sure what you're asking. Also, a superconductive transistor is an oxymoron as transistors are semiconductors.
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Sep 27, 2010 04:50
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Shooting Blanks posted:I just got done reading the book Chaos by James Gleick - I know, Jeff Goldblum, Jurassic Park, blah blah blah. Chaos theory isn't science, really, it's mathematics. As for whether chaos theory is scientifically useful, well, it might be. I'm not really an expert. But chaos theory applies mostly to extremely complicated systems, and so tends to be the domain of meteorology and biology and psychology and things that I don't know much about. I'm not even sure chaos theory really helps you get good predictions; as far as I know it mostly tells you why you can't predict things. But then, all I really know about it I learned from Michael Crichton, so I am probably way wrong about things.
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Sep 27, 2010 05:51
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Shooting Blanks posted:I just got done reading the book Chaos by James Gleick - I know, Jeff Goldblum, Jurassic Park, blah blah blah. The trouble is of course that chaos theory, by definition, applies to a set of problems that are really hard. Some good work has been done, and research is still carried out. There are applications (sometimes isolated, sometimes not) in a wide variety of fields. Wikipedia has a short list you might find interesting. But I don't think it's fashionable anymore to be as optimistic as they were back then. If all the hard chaotic problems are going to suddenly become tractable, my guess is it will require a new insight which is as unexpected and novel as the original development of chaos theory was. (With that said, I don't really know anything about the field and wouldn't have dared open my mouth if DontMockMySmock hadn't already said the same of himself.) DontMockMySmock posted:Chaos theory isn't science, really, it's mathematics. *Except for the slim possibility that a logical error was made in "proving" some theorem, and it has gone undiscovered. But of course scientific theories run this risk and others as well. McNerd fucked around with this message at 06:54 on Sep 27, 2010 |
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Sep 27, 2010 06:36
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Thanks for explaining how Hawking radiation wouldn't violate the law of conservation of mass-energy. The virtual particles elsewhere in space, the ones that always pop in and annihilate each other right away, those are made from energy too? Some energy gets turned into a particle pair according to e=mc^2, and when they annihilate, they turn back into energy? I never understand how particles popping out of nothing didn't violate mass-energy conservation, but if you're saying the particles are just energy flipping into matter, that explains it. I know that matter and energy are two sides of the same coin, I just didn't think of applying that to these. Or am I completely wrong?
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Sep 27, 2010 07:44
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How many atomic-level particles have physicists thought up, and how many are experimentally useful? I know in most molecular chemistry applications we really only deal with a few, which is kind of a relief  . Everything I do can be explained by protons and electrons. Do you think we'll ever see stuff like quarks or neutrinos in practical applications?
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Sep 27, 2010 07:48
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There are muons, which are like a heavier electron (Electrons, muons and neutrinos belong to a family of particles called leptons which don't experience the strong nuclear force). Muons have a half-life of a few microseconds. One possible application of muons is for nuclear fusion. When the electron in a hydrogen atom is replaced by a muon the radius of the atom shrinks because of the greater mass. These modified hydrogen atoms are so small that their nuclei have a significant chance of fusing, even at room temperature. At least, that's what I've gleaned from the wikipedia page: http://en.wikipedia.org/wiki/Muon-catalyzed_fusion Edit: well actually the muon brings ions close together instead of replacing an electron but everything else is correct I think.. Willheim Wordsworth fucked around with this message at 08:39 on Sep 27, 2010 |
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Sep 27, 2010 08:36
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Raere posted:Thanks for explaining how Hawking radiation wouldn't violate the law of conservation of mass-energy. The virtual particles elsewhere in space, the ones that always pop in and annihilate each other right away, those are made from energy too? Some energy gets turned into a particle pair according to e=mc^2, and when they annihilate, they turn back into energy? I never understand how particles popping out of nothing didn't violate mass-energy conservation, but if you're saying the particles are just energy flipping into matter, that explains it. I know that matter and energy are two sides of the same coin, I just didn't think of applying that to these. The kind of particles that are popping in and out everywhere don't violate conservation of energy because they don't exist for long enough. The Heisenberg uncertainty principle lets them do that. As long as their energy times the time they existed is on the order of Planck's constant, it can happen. Even when there is nowhere for them to get energy from. This doesn't violate conservation of energy in quantum mechanics because conservation laws apply to average/expected values. It's a little mind-bending but it all makes sense mathematically. antwizzle posted:How many atomic-level particles have physicists thought up, and how many are experimentally useful? I know in most molecular chemistry applications we really only deal with a few, which is kind of a relief More than I know the names of. Any particle that has been discovered is experimentally "useful" because it will show up in supercollider experiments. Here's a few: Fundamental Force Carrying Bosons: Photon, associated with electromagnetism, its own antiparticle Gluon, associated with the strong force, comes in many varieties based on "color" charge W+/- boson, associated with the flavor-changing weak force Z0 boson, associated with the flavor-unchanging weak force, its own antiparticle Fundamental Fermions (leptons and quarks): Leptons (from the Greek meaning "light thing," as in not-heavy): Electron Electron neutrino, carries electron flavor but is small and neutral Muon, a particle that is like a heavy electron Muon neutrino Tau, a particle that is like a REALLY heavy electron Tau neutrino Quarks: Up, charged +2/3 Down, charged -1/3 Strange, a heavy down Charmed, a heavy up Bottom, a heavier down Top, an up that's so heavy it doesn't even form hadrons Hadrons (composites of quarks, from the Greek meaning "heavy thing"): Baryons, made of three quarks, including the proton and neutron Mesons, made of a quark/antiquark pair Other: atomic nuclei, atoms, stranger things like positronium (a hydrogen-like "atom" made of an electron and antielectron (positron) instead of electron and proton) And all of these also have their corresponding antiparticle unless I or the Wikipedia lists I linked said it was its own antiparticle. Only a few of them are stable, these being the photon, the electron, the proton, and various atomic nuclei and atoms.
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Sep 27, 2010 17:35
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DontMockMySmock posted:Top, an up that's so heavy it doesn't even form hadrons So is particle lifetime proportional to mass? Never really learned about it in our modern physics course. Also, I've heard a lot mentioned about AdS/CFT in the context of QCD, mainly that it's believed that certain calculations through it would be possible in a much simpler manner than through QCD. Would those AdS/QCD calculations be considered an example of the predictive power of string theory, or not because those calculations are still possible, albeit in a more difficult process, via QCD? I'm probably gonna ask our resident heavy ions theorist about it too. Saw something about earlier when glancing over an article on some heavy ions results.
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Sep 27, 2010 18:14
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Would it be impossible to take physics w/ calc without having taking calc first?
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Sep 27, 2010 18:17
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Kommienzuspadt posted:Would it be impossible to take physics w/ calc without having taking calc first? Not impossible but definitely far more difficult without than with. Some schools will review the basic calc you need before really starting to use it. Some schools may not you enroll in it without the pre-req or co-req. Or so my first and second-hand experiences with universities in Michigan have suggested.
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Sep 27, 2010 18:35
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EscalatorThief posted:So is particle lifetime proportional to mass? Never really learned about it in our modern physics course. The decay rate of X into YZ... is greater if the difference in rest masses mx - my - mz ... is greater. There's more energy to be released, and that makes it more likely. So since the top is so much heavier than what it decays into (bottom, strange, or down and a W boson) it decays too fast to hadronize. I don't know anything about AdS/CFT. I've never studied Lie groups, so I can't even glean anything from the Wikipedia page. Asking a particle physicist probably is a better idea.
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Sep 27, 2010 19:04
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First off, thanks for doing this! You make a great teacher. Secondly, here's my question(s): What's the largest observed example of the wave-function collapse? I remember hearing from a Physics professor a few years back that they had recently noticed that DNA works at a quantum level, although I'm curious if that boundary has been pushed any more. What's the most disturbing fact that you have learned in physics? The small amount of my knowledge regarding this subject has shown me that it's a strange, strange world out there.
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Sep 27, 2010 21:20
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The Dark Wind posted:First off, thanks for doing this! You make a great teacher. The wave function collapse doesn't really have any interesting results other than when entanglement is involved, and you can't really entangle more than individual subatomic particles. Otherwise, wave functions collapsing when we observe them is just. . . us observing stuff. Whenever you look at something, you collapse its wavefunction, in a sense. If you want to think of it that way. As for disturbing facts, well, physics has nothin' on chemsitry and especially biology. I think perhaps the only really disturbing thing is the sheer immensity of distances involved in astrophysics in comparison to the teeny tiny distances involved in quantum mechanics, and our narrow field of vision in this respect when it comes to the ordinary world. We can't see stuff much smaller than a tenth of a millimeter, nor things much bigger than ten kilometers, and yet there's these whole different worlds that exist at lengths of over a billion billion times as big as that ten killometers and less than a hundred billionth the size of that tenth of a millimeter.
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Sep 27, 2010 21:48
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I have kind of a dumb question about particle accelerators. They are all very big, at least the ones operating much above a few dozen MeV. So, say I want to generate some 10 GeV protons or something...10 GeV is a tiny amount of energy, but to produce even one such particle I would still need a massive accelerator. I suppose this is because the cavity resonators in a modern accelerator can only be made so small, and each one can only provide so much energy, and can only be so efficient, etc. And if I want to wrap the thing in a circle to make it smaller I have to add some pretty big magnets, and so on. And I understand that the luminosity of most large accelerators is absolutely huge, but so far as I'm aware, you still need a giant accelerator and lots of electricity to achieve GeV-TeV+ energies, regardless of beam intensity. But then, recently there has been a lot of interesting work using things like plasma wakefield acceleration, and people are talking about gradients as high as 1 GeV/cm. My question is, what ultimately decides the minimum size and power consumption of a particle accelerator? Are there some fundamental physical or thermodynamical reasons that say "to achieve this much acceleration you need this much energy", other than simple energy conservation? Is there any way to just take 10 GeV of energy and somehow put all or most of it into accelerating one particle? How long of a distance does that require? I guess my question is whether or not there is some basic physical limitation to the field gradients you can achieve, or is it just an engineering/materials problem?
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Sep 27, 2010 23:07
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Morbus posted:I have kind of a dumb question about particle accelerators. It's not a dumb question at all. Accelerator physics is complicated. They come in (basically) two types: linacs and synchrotrons. A linac uses electromagnets to accelerate the particles in a line. A synchrotron uses electromagnets to accelerate the particles in a circle. Linacs have the disadvantage that you have merely the length of the device to get the particle up to speed. Synchrotrons have the disadvantage that the particles will lose energy to aply-named synchrotron radiation. So you're accelerating and containing these bunches of particles with electromagnets. This is where most of the power goes. The vast majority of the power does not go into the particles, but instead into heat in the wires of the electromagnet. This means you also have to spend a lot of effort cooling it. In addition to the accelerating electromagnets, you also need electromagnetic lenses, to keep the beam focused. The bigger a magnetic field you want, to accelerate it faster, the more energy will be lost to heat. The longer your device, the more magnets you need. If you want to use a synchrotron, you can take advantage of accelerating over many revolutions, but you'll spend more energy to make up for the energy lost to synchrotron radiation. Tl;dr: There's no simple way to just take 10 GeV and put it all in a particle.
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Sep 27, 2010 23:32
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DontMockMySmock posted:Whenever you look at something, you collapse its wavefunction, in a sense. I know very little about quantum stuff, but I thought that what made things collapse would be things like a photon bouncing off of an object. Shouldn't that happen whether I'm looking in the direction of the object or not? Basically I'm asking for clarification as to whether "look at" here is being used in a different sense than its everyday meaning.
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Sep 27, 2010 23:59
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helopticor posted:I know very little about quantum stuff, but I thought that what made things collapse would be things like a photon bouncing off of an object. Shouldn't that happen whether I'm looking in the direction of the object or not? It depends on how you look at it (no, pun intended). Let's break this down to its simplest components: there's an electron in the orbital of some atom or molecule, and a photon bounces off of it and heads towards your eye. Either the electron wavefunction was collapsed when it interacted with the photon, or the electron-photon composite wavefunction was collapsed when it interacted with your eye. Or maybe electron-photon-eye-optic nerve wavefunction collapsed when it interacted with your brain. Or maybe this experience is a point on the wavefunction of the electron-photon-eye-optic nerve-brain system and the other points are other universes where you saw something different. No matter which of these ways you look at it, the math comes out the same if you try to predict how likely it was that you observe this photon.
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Sep 28, 2010 00:05
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I have some (I think) fairly simple questions. If the universe is expanding from a single point, and so is the radiation from it, why does the Cosmic Microwave Background come from every direction? What is electricity? I mean, it's something about electrons moving about or something but... What causes gravity? Does light have mass? Apologies if any of these are unknown or difficult to answer. Infinite Monkeys fucked around with this message at 15:51 on Sep 28, 2010 |
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Sep 28, 2010 15:32
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Quick Scoop posted:I have some (I think) fairly simple questions. Don't think of the cosmic microwave background coming from a single point. It came from the universe as it was about 300,000 years old. Furthermore, thinking of the universe as expanding from a single point can lead you astray, since you are no doubt imagining a point within some space, which there wasn't; but that's neither here nor there. In any case, no matter what direction you look in, you look backwards in time - the light that reaches us was emitted some time ago. If you look far enough, in any direction, you see the cosmic microwave background, because you're looking at the universe as it was 300,000 years after the big bang. Light from earlier times can't reach us because back then the universe was opaque. Electricity is electrons moving about in a conductor due to an electric field set up by some sort of power source (a battery, a generator). Some devices can harness their energy as they pass by. Gravity is caused by mass-energy. Mass-energy causes spacetime to curve, in accordance with Einstein's Equations, and curved spacetime tells things how to move, in accordance with the geodesic equation. If you ask "why does spacetime curve," I won't have an answer for you. It just does. Light has energy, and therefore has inertia and gravity, but it is typically referred to as massless because it has no rest mass - if a photon was not moving, it would not have mass; as a consequence of this, photons can't not move at the speed of light.
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Sep 28, 2010 17:19
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I have a semi-related question: What's the significance, if anything, of the rest frame of the CMB?
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Sep 28, 2010 18:09
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Hobnob posted:I have a semi-related question: What's the significance, if anything, of the rest frame of the CMB? I don't think that there really is any significance. We're moving with respect to the rest frame of the gas in the universe 13 billion years ago. I'm not too shocked.
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Sep 28, 2010 18:19
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Thanks, that helped. It was implied to me that the CMB was from the actual big bang, but if I understand correctly it was actually from millions of years after so whatever emitted it had time to get in front of us as it were, then send the radiation back?
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Sep 28, 2010 20:56
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Quick Scoop posted:Thanks, that helped. It was implied to me that the CMB was from the actual big bang, but if I understand correctly it was actually from millions of years after so whatever emitted it had time to get in front of us as it were, then send the radiation back? Hundreds of thousands of years after. I'm not sure what you mean about something getting in front of something else. What happened is this: The universe started out really hot and dense, expanding. As it expanded, it got cooler and less dense. Among the hot gas (plasma, if you want to bother with that distinction) there is light, but the light is not free to propagate forever - it bounces off the charged particles and interacts and changes. Eventually, after a couple hundred thousand years, it cools enough that the charged particles form neutral atoms, and all of a sudden the universe is transparent. This is the moment we are looking at when we look at the CMB, because this is the moment when those photons finally escaped and were free to propagate for billions of years until they hit our microwave telescopes. Between then and now, the photons have redshifted as the universe expands, and are at wavelengths ~1100 times longer than when they are emitted. This puts them in the microwave range.
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Sep 28, 2010 21:06
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DontMockMySmock posted:Among the hot gas (plasma, if you want to bother with that distinction) Is there anything worth elaborating on in this point? Is plasma less different from hot gas than I thought? Was They Might Be Giants' song replacement* unnecessary?, etc. *If you're unfamiliar, they had a famous song that contained a line "the sun is a mass of incandescent gas", and then a bunch of people complained and they made a new song with a line "the sun is a miasma of incandescent plasma".
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Sep 28, 2010 22:56
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helopticor posted:Is there anything worth elaborating on in this point? Is plasma less different from hot gas than I thought? Was They Might Be Giants' song replacement* unnecessary?, etc. It's unimportant. A plasma is a gas with charged particles. It's still a fluid that expands to fill the volume of its container. In comparison, salt water isn't a plasma, despite being a fluid with a significant number of charged particles. Personally, I think miasma is a much worse word to use, as the sun is not composed of vapours which cause cholera.
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Sep 28, 2010 23:22
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helopticor posted:Is there anything worth elaborating on in this point? Is plasma less different from hot gas than I thought? Was They Might Be Giants' song replacement* unnecessary?, etc. Like I mentioned earlier when talking about critical point phenomena, different states of matter are pretty much just a convention (although phase transitions are real and meaningful). Plasma that is as hot as the sun or as hot as the early universe is well approximated by the ideal gas law; ipso facto, it's a gas. It behaves much differently than the sort of plasma you'd make in a lab on earth, which is dominated by electromagnetic interactions and is well-approximated by a very different equation-of-state. Which brings me to my next point: a state of matter is just something that obeys some equation-of-state. There is no sense listing "Bose-Einstein condensate, solid, liquid, gas, plasma," and concluding that there are "five states of matter," as schoolteachers are fond of saying (although they may omit BEC and/or plasma). There is just as much qualitative difference between the material properties of water and ice-1 as there are between ice-1 and ice-2, two different states of ice separated by a phase change (I think there are like twelve different states of ice that have been well-studied). To reiterate the answer to your question, the sun IS a mass of incandescent gas, since it is well-approximated by the ideal gas law. Anyways, "Why Does the Sun Shine? (The Sun is a Mass of Incandescent Gas)" has only one factual error, which is when they say, "The heat and light of the sun are caused by the nuclear reactions between hydrogen, nitrogen, carbon, and helium." In the sun, nitrogen and carbon are not involved (and helium is just a product, not a reactant, so I don't know if it's fair to say there are "reactions between hydrogen and helium" either). In more massive main-sequence stars, carbon and nitrogen ARE involved in building hydrogen into helium, but oxygen is also involved and is sad to be left out of their list (the process is called the CNO cycle, after carbon, nitrogen, and oxygen). A miasma is poisonous fumes from decaying organic matter, or else a foreboding atmosphere. Although it is sometimes used sort of incorrectly to mean a cloud of generally unpleasant poo poo. Doesn't really describe the sun any way you slice it. Although I guess if you're trying to rhyme with "plasma" you don't have a lot of choice. I haven't heard that one, I should go check it out. . . . . . okay so I just did, and they also describe the sun as a "quagmire" in one line. That means "bog," and also doesn't describe the sun. Other than those word choices and the whole "gas/plasma" distinction, the song is factually correct. In case you were wondering. TMBG are still awesome. edit: TMBG is awesome? There's multiple band members and the band name is plural, but it's just one band. . .  grammar!
DontMockMySmock fucked around with this message at 00:38 on Sep 29, 2010 |
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Sep 29, 2010 00:35
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This just gave me a thought. Assuming the CMB will keep redshifting, it'll eventually turn into the Cosmic Radio Background. Will it then interfere with any radio waves we may be broadcasting at that point, or is it weak enough to be negligible? I'm assuming it'll be a long, long time before this happens but it's just a thought.
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Sep 29, 2010 01:03
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normal contact posted:This just gave me a thought. Assuming the CMB will keep redshifting, it'll eventually turn into the Cosmic Radio Background. Will it then interfere with any radio waves we may be broadcasting at that point, or is it weak enough to be negligible? I'm assuming it'll be a long, long time before this happens but it's just a thought. It would, but I imagine by that time (at least a hundred billion years, off the top of my head) I imagine we will have figured out a workaround.
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Sep 29, 2010 01:07
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Here's a question not about anything in specific but rather the methodology of physics - As I understand it, a lot of the major concepts in physics (Inflation, the holographic principle, gravitons) are "invented" (this is a poor term to use) to rectify some problem that arises, i.e. inflation explains the CMB's homogeneity, the holographic principle was used by Susskind to solve the black hole information paradox, etc. This makes sense and follows a problem --> solution path of thinking. Are there any concepts that came about backwards from that? I.e., something strange was found in a particle accelerator experiment that ended up explaining a problem that hadn't yet been solved? I know that string theory was proposed and mostly forgotten before someone realized it could be expanded to a potential quantum gravity solution. Any examples of prior, forgotten concepts being co-opted years later to solve a problem?
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Sep 29, 2010 02:53
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Evan Montegarde posted:Here's a question not about anything in specific but rather the methodology of physics - The big example of an old theory being co-opted to solve new problems would probably be the "cosmological constant." Einstein put that in his theory to explain why a universe full of matter could be static, as it appeared to be at the time (and when the universe was later found to be expanding, Einstein called it the biggest mistake of his career). Nowadays, cosmological constant is the leading candidate for dark energy (the constant is equivalent to adding an amount of energy density to the entire universe that depends on the constant's value). I can't think of anything else that followed a similar pattern besides string theory and cosmological constant. But as to your other question: are there phenomena which are explained by newer experimental results, the answer is a resounding yes. Every bit of information we collect gives us new insight into the big problems. One thing that comes to mind in recent years is the solar neutrino problem. There was a deficit between the predicted quantity of neutrinos coming from the sun and the observed number. This was later explained when neutrino oscillations were discovered - the solar neutrino detectors could only detect the electron-flavor neutrinos, but the neutrinos from the sun oscillate into roughly 1/3 electron-, 1/3 muon-, and 1/3 tau-flavored neutrinos. This deficit soon became apparent in atmospheric muon experiments, as well, and from there neutrino oscillation was hypothesized, and later confirmed by an experiment called Super Kamiokande, thus solving the solar neutrino problem once and for all.
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Sep 29, 2010 03:51
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How come that when you strike a liquid like water really hard it feels like you are striking something solid. Conversely when two solid objects strike each other at really high speeds they behave like they were liquid, I'm thinking of an armor piercing projectile striking a metal armor in this latter case. If the lowest possible temerature is when molecular motion approaches zero, is it conversely true that the maximum possible temperature is when molecular motion approaches the speed of light?
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Sep 29, 2010 13:11
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raptus posted:How come that when you strike a liquid like water really hard it feels like you are striking something solid. On the flip side, when you watch something hit something at high speed, like an armor-piercing projectile striking metal armor, you probably can't even process what's going on unless you watch it in slow-motion. Slow-motion changes your whole perception of it. Remember also that metal is malleable, and metal changing shape is still very much unlike liquid flowing. So your perception of these solids "behaving like they were liquid" isn't accurate. raptus posted:If the lowest possible temerature is when molecular motion approaches zero, is it conversely true that the maximum possible temperature is when molecular motion approaches the speed of light? Well, in a sense, yes; as particle speeds approach the speed of light, the temperature approaches infinity, and infinity sure is the maximum. Temperature is proportional to the kinetic energy of the particles, and kinetic energy of a particle goes to infinity as its speed goes to c.
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Sep 29, 2010 17:27
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DontMockMySmock posted:Well, in a sense, yes; as particle speeds approach the speed of light, the temperature approaches infinity, and infinity sure is the maximum. Temperature is proportional to the kinetic energy of the particles, and kinetic energy of a particle goes to infinity as its speed goes to c. Isn't it difficult to say if there is a "maximum" temperature though? You can always pump a little more energy into your beams and extract a slightly higher temperature I would think.
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Sep 29, 2010 18:52
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EscalatorThief posted:Isn't it difficult to say if there is a "maximum" temperature though? You can always pump a little more energy into your beams and extract a slightly higher temperature I would think. You are technically correct, the best kind of correct. Because "infinity" isn't actually a number. But saying "there is no maximum temperature" and "the maximum temperature is infinity" are pretty much the same thing, except that one is more technically, mathematically correct than the other.
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Sep 29, 2010 20:22
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