'13-07-25, 10:33 phunk	Originally Posted by Charles Chandler Would you care to elaborate? Hydrogen plasma is significantly more opaque than neutral hydrogen. Are you familiar with the source of the CMB? (or do you dispute that as well?)
'13-07-25, 11:02 edd	I'm afraid I'm on vacation and my laptop charger broke, so I'd invite others to pursue comments directed my way freely.
'13-07-25, 11:42 DeiRenDopa	Originally Posted by Charles Chandler Originally Posted by me Among the many papers which cite this is Bi, S. L.; Di Mauro, M. P.; Christensen-Dalsgaard, J., 2000 An improved equation of state under solar interior conditions Astronomy and Astrophysics, v.364, p.879-886 (2000). Figure 1 is quite interesting; part of the caption reads "The fractional contribution arising from nonideal effects to the ideal pressure of the reference solar model 1 which employed the EFF EOS." The y-axis goes from 0.00 to 0.10. Hmm, I guess "the ideal gas laws" aren't such a bad approximation after all. So Bi, S. L.; Di Mauro, M. P.; and Christensen-Dalsgaard, J. conclude that the standard model, developed by Christensen-Dalsgaard, J., is OK after all. Ah yes, MM has taught you well, hasn't he? If your ability to comprehend what you read is as poor as this comment of yours seems to imply, I'll likely bow out of this thread fairly soon. Quote: I "think" that for you, such constitutes confirmation of a proof. You are welcome to think whatever you like. As the saying goes, you are entitled to your own opinions ... but not your own facts. Quote: The standard model might acknowledge compressive ionization, though as you say, at the model temps, there aren't any bound electrons to be liberated by pressure, and thus compressive ionization isn't much of a factor. But the standard model does not take the Coulomb barrier into account, which is a factor at any temperature. If matter could be compressed just by the ideal gas laws, nuclear fusion would be easy. In fact, nuclear fusion is not easy at all. The reason is the Coulomb barrier. The Dalsgaard model doesn't take this into account, therefore the Dalsgaard model is wrong. The Dalsgaard model does not take what I ate for lunch yesterday into account either, therefore the Dalsgaard model is wrong. So, I agree with you. Your model - whatever it eventually will be - will not take into account what my grandfather ate for lunch 50 years' ago. Therefore it will be wrong. Is this truly how you think science is done?!? Quote: The implication is that in order to achieve the known density of the Sun, we'd have to lower the temperature, such that the Coulomb barrier plus the hydrostatic pressure would once again yield the correct densities. But if we lower the temperature, the fusion furnace goes out. Another implication is that compressive ionization is more of a factor at lower temps, which spells even more trouble for the standard model. As I said in an earlier post, willful ignorance is not pretty. If you're interested, I can recommend some standard textbooks you would benefit from reading (and understanding). If you don't like what I write, I'm sure at least some others would also be happy to recommend too. Quote: Yesterday isolated thunderstorms came through my area. One of them was fully developed, complete with an anvil at the bottom of the stratosphere, 14 km above the ground. And I could see this from the ground, meaning that I was seeing through 14+ km of completely opaque air? Your senseless argumentativeness serves no useful purpose. I did a quick internet search; the Earth's atmosphere is still quite opaque in the primary wavelength emitted by hydrogen (your phrase); 1 km "of STP air" is more than enough to block it completely. Quote: Why are radiative processes in astrophysics different from radiative processes in the lab here on Earth? They're not, of course, as you would learn if you were to read (and understand) a standard textbook. No, wait! I forgot; MM rules of logic apply, so the correct answer is "why is a raven like a writing desk?" Quote: Argumentum ad populum. Do you prefer argumentum ad ignorantiam? Quote: Further, it's ironic to hear the word "nonsense" used to describe anything that doesn't sit well with the standard astrophysics model, which is substantially inconsistent with laboratory physics. Hmm, it seems a perfectly good word to describe ... nonsense, wouldn't you say? Quote: Anyway... First, I'd like to say that my position has next to nothing in common with the Electric Universe model, except of course that it places a lot of emphasis on the electric force. Yet what you have written has many of the same features as writings on "the EU model" (by their proponents), such as argumentum ad ignorantiam, frequent use of (willfully created?) strawmen (many of which are the same), idiosyncratic (and inconsistent) use of standard terms, ... Quote: Can you guys refrain from the ad hom comments for just a little while? There's still the outside chance that a legitimate discussion of the issues could occur. You first. Will you cease and desist with the MM-style illogical statements, the gross mis-characterization of the nature of scientific models? Will you read and at least try to understand standard textbooks?
'13-07-25, 11:50 Charles Chandler	Originally Posted by dasmiller So your 'new solution' relies on a process (spontaneous charge separation due to compression in plasma) that has... Here are my comments interspersed with yours... never been demonstrated in a laboratory, I don't know of an instance where this was demonstrated in the lab. doesn't have a theoretical basis, The theoretical basis for it is that electrons can only exist in specific shells, or as free particles. If the atoms are pushed too close together, such that the shells are in conflict, the electrons are liberated. That's "compressive ionization". Then the question is, "What happens to the free particles?" One possibility is degeneracy, which supposedly happens in neutron stars and white dwarfs. Essentially, the electrons stay close to the atoms, but as free particles, making the matter quasi-neutral, and thus lacking any Coulomb barrier. The matter can then be further compressed, limited only by the hydrostatic pressure. I find that to be implausible, since the implication would be that nuclear fusion would be easy, and it isn't. The other possibility is that the electrons are expelled, meaning "compressive charge separation". appears to fly in the face of well-understood physics, and What "well-understood physics"? Electron degeneracy, which is the only other possibility, and which has never been demonstrated in the laboratory, and which disagrees with what we do see in the laboratory? has never been directly or indirectly observed in nature? As concerns direct observations, we're talking about something that could only occur under extreme pressure, so no, we wouldn't expect direct observations. As concerns indirect observations, that would depend on the observer. I'm saying that the Sun's distinct limb is evidence of a charge separation, because no other configuration of known forces can account for it, and to my knowledge, "compressive charge separation" is the only hypothetical candidate. Originally Posted by phunk Hydrogen plasma is significantly more opaque than neutral hydrogen. Are you familiar with the source of the CMB? (or do you dispute that as well?) Can you cite laboratory research for the opacity of neutral hydrogen versus free electrons?
'13-07-25, 12:07 Charles Chandler	Originally Posted by DeiRenDopa I did a quick internet search; the Earth's atmosphere is still quite opaque in the primary wavelength emitted by hydrogen (your phrase); 1 km "of STP air" is more than enough to block it completely. BTW, by "primary wavelength emitted by hydrogen", I meant that it is the most prevalent in the solar spectrum, and therefore the one in which hydrogen is the most easily detected. I guess I could clarify the wording, but I wasn't implying that that the Balmer series is more "primary" than the Lyman. Anyway... Consider the following image. (Look at the picture! Look at it! Hey Michael, can you help me out here? We need to get DeiRenDopa to look at the picture! ) Figure 1. The solar limb seen in H-α (6563 à ), 2007-05-27, courtesy Fred Bruenjes. Now consider the fact that this picture was taken from Earth. If "1 km of STP air is more than enough to block it completely", I should expect the picture to be blank.
'13-07-25, 14:41 edd	Excuse the short post and suboptimal link given my above described situation: http://hyperphysics.phy-astr.gsu.edu...ro/transp.html
'13-07-25, 15:07 Charles Chandler	Originally Posted by edd Excuse the short post and suboptimal link given my above described situation: http://hyperphysics.phy-astr.gsu.edu...ro/transp.html I'd like to commend you for this. The proper way to defeat an argument is with factual information, not ad hom attacks. The link is to a webpage on "Transparency Temperature" from GSU, whose stuff is always top-quality. So I'll have a look, but it certainly seems that I was completely wrong about cool plasma being more opaque than hot plasma. My compliments.
'13-07-25, 15:13 ben m	Charles, The ideal gas law DOES take the coulomb barrier into account. It does do correctly. The Coulomb repulsion is *screened* in dense plasmas. You are incorrect to use the free-space Coulomb force at all, much less to treat it like a hard-core repulsive force. The "hard-core" repulsion that makes liquids and solids incompressible is due to the Pauli Exclusion Principle, not from the Coulomb barrier, and that barrier vanishes as something like the cube of the temperature.
'13-07-25, 15:36 Charles Chandler	Originally Posted by ben m The ideal gas law DOES take the coulomb barrier into account. Since when did PV = nRT include E? Originally Posted by ben m The "hard-core" repulsion that makes liquids and solids incompressible is due to the Pauli Exclusion Principle, not from the Coulomb barrier, and that barrier vanishes as something like the cube of the temperature. No, the barrier doesn't vanish with temperature. It takes a certain temperature to overcome the Coulomb barrier in order to achieve nuclear fusion. In other words, when the inertial force becomes greater than the electrostatic repulsion, fusion becomes possible. See Coulomb Barrier for Fusion.
'13-07-25, 16:40 DeiRenDopa	This is as good a place to start as any ... Originally Posted by Charles Chandler Yesterday isolated thunderstorms came through my area. One of them was fully developed, complete with an anvil at the bottom of the stratosphere, 14 km above the ground. And I could see this from the ground, meaning that I was seeing through 14+ km of completely opaque air? Your senseless argumentativeness serves no useful purpose. Here's an interesting story; CC is blue: Hence the plasma on the limb of the Sun should still be quite transparent at a depth 13.22 Mm, and the opacity should increase steadily with depth, without producing a distinct edge. With an internal light source, the Sun should look like headlights in the fog, with the luminosity gradually tapering off to nothing at some distance from the center, (post #14) edd: You seem to be dramatically oversimplifying what determines opacity in the widely accepted model. (post #15) To get a distinct limb in a smooth density gradient, you really need to say that some sort of threshold is being crossed, where plasma above this precise density is opaque/luminous, and plasma below that density is not. Temperature "could" cause such a threshold (sort of, at least), where plasma above a certain temperature isn't engaging in photon absorption/emission, because [...] So I don't understand how the "widely accepted model" actually accounts for the observations. (post #25) edd: Ummm.... that. That might be one of your problems. (post# 36) Can you explain what you mean by this? I'm not clairvoyant. (post #37) me: Hmm, maybe if you spent some time reading a standard textbook, or even learning the basic physics used in the relevant parts of them, you might not need to be clairvoyant? Let's take the Earth's atmosphere; it's pretty transparent, down to sea level, in the 'optical', but quite opaque in the UV and in the IR (with windows of varying transparency and width). Why is that? If you were to heat it up, how would that change? Would the 'windows' change, both in transparency and (frequency/wavelength) width? Why? What basic physics explains these changes? If the Sun's 'metals' (i.e. all elements other than H and He) were to be removed - in the standard model - how would the Sun be different? Given standard models of the density and temperature profile of the Sun's photosphere (and its element composition), how does the opacity change? In the standard model. (post #38) As concerns your other rhetorical questions, I don't think that anybody on this thread cares to wade through that kind of stuff. If you have something to say, just go ahead and say it, and try to be clear & specific. There are legitimate issues here, and implications. No need to clutter up the discussion with banter. (post #44) me: Yeah, you're right ... if you yourself do not know about that kind of stuff, then you've as much as come out and admitted that you have essentially zero understanding of the standard model (with relevance to the 'transparent to opaque' transition of the photosphere). But never fear, in the glorious tradition of JREF ('putting the E in JREF'), someone will be along, sooner or later, to give a succinct, pertinent summary (leaving you, CC, with egg all over your face). (post #54) 13.22 Mm is the depth at which, in the Dalsgaard model, the density of the Sun achieves that of STP air. So I'm (somewhat casually) saying that at 13.22 Mm, the plasma should be as transparent as sea-level air on Earth. Actually, it should be a lot more transparent, because the model temperature at that depth is over 10 kK, and at that temperature, bound electrons capable of absorbing a photon will be few and far between. So for all intents and purposes, only free-free absorption/emission should be going on, which is somewhat rarer, and could not account for what we would call opacity. (post #47) me: You're right. And perhaps the most legitimate is to first establish that you, CC, do not understand the standard model (at least as it directly relates to the 'transparent to opaque' transition of the photosphere). (post #54) phunk: The sun is a 1.4 million km wide sphere. When you look at edge of the limb, you're looking across the top of thousands of miles of plasma. If you look just slightly "deeper" than the edge, you're looking through thousands of miles of plasma. This makes the limb gradient appear significantly sharper than it would if you could look at a cross section. (post #30) No, you don't understand. In a smooth gradient, the opacity should increase smoothly. Sure, opacity is a linear function of the amount of opaque matter in question, and if you look at the geometry of how a line of sight intersects a sphere, at & below the surface, the opacity increases faster than the density at the tangent. But that still doesn't give you a distinct edge. (post #31) phunk: Given the picture Charles provided, just one pixel deep from the edge has you looking horizontally through about 47000km of plasma. (post #46) OK, so I ran the numbers on that, and here's what I got, for all of you who think that the photosphere should be opaque just because of all of that plasma. Starting from the top of the photosphere, to traverse 47000 km of plasma, the arc chord descends into the Sun to a depth of 400 km, for an average depth through the traversal of (nominally) 200 km (0.999712 R⊙). At that depth, the model density of the Sun is 3.45e-4 kg/m3. The density of STP air is 1.29 kg/m3, which is 3736 thicker. 47000 / 3736 = 12.57. So seeing through 47000 km of solar plasma, at 3.45e-4 kg/m3, should be about like seeing through 12.57 km of STP air, at 1.29 kg/m3. (That's assuming, of course, that the Earthly nitrogen/oxygen mix has the same opacity as the solar hydrogen/helium mix. In reality, the solar plasma should be more transparent, due to a lack of bound electrons.) So then the question is, "How opaque is 12.57 km of STP air?" Anybody? (post #56) me: Why do you need to assume, CC? What do standard astrophysics textbooks say are the dominant sources of opacity (in the optical)? In particular, what have you read about the H- ion? (post #67) me: From the same table, the temperature goes from 5.78e+03 K to ~1.14e+04 K (please confirm). Does a 'solar' mix - predominantly H and He, but not insignificant proportions of metals - keep its ionization state constant over that temperature range? (I have this vague recollection - no doubt from reading standard textbooks - that hydrogen is almost completely neutral at ~5kK, but almost fully ionized at ~10kK; perhaps my memory is playing tricks on me ) (post #76) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - me: What standard astrophysics textbooks did you read, to ensure that you had a good understanding of the mainstream explanation/description of the solar limb (including limb darkening), opacity, and the density/temperature/pressure/composition profile of the Sun? In light of what's in those standard textbooks, how, ummm, accurate would you say your characterization is? More specifically, can you share with us some of the work you did, to try to "understand how the "widely accepted model" actually accounts for the observations"? (post #29) I didn't read textbooks — I read journals, because they're more current. So here are the citations that I'm using so far. Note that this isn't just a reading list — all of these are cited in the text somewhere. So I had a specific reason for citing all of these. (post #37) The link is to a webpage on "Transparency Temperature" from GSU, whose stuff is always top-quality. So I'll have a look, but it certainly seems that I was completely wrong about cool plasma being more opaque than hot plasma. (post #87) Hmm, am I the only one who thinks CC could have saved himself a great deal of time (and egg on his face) if he had read some standard textbooks, before posting here?
'13-07-25, 16:44 DeiRenDopa	Originally Posted by Charles Chandler Since when did PV = nRT include E? Is this the full extent of your understanding of the ideal gas law, CC? Perhaps you might consider going over your notes, and re-reading what is assumed in that law ... Quote: Quote: The "hard-core" repulsion that makes liquids and solids incompressible is due to the Pauli Exclusion Principle, not from the Coulomb barrier, and that barrier vanishes as something like the cube of the temperature. No, the barrier doesn't vanish with temperature. Way to go, CC, way to go. Perhaps you might consider re-reading what ben m actually wrote, and then re-thinking your response? (egg)
'13-07-25, 17:49 Reality Check	Originally Posted by Charles Chandler Yes. See: Saumon, D.; Chabrier, G., 1992: Fluid hydrogen at high density: Pressure ionization. Physical Review A, 46 (4): 2084-2100 Actually no, Charles Chandler, according to your citation to a paper whose abstract does not mention experimental evidence. Originally Posted by Charles Chandler Actually, the physics of photon absorption/emission, at least as concerns laboratory observations, is relatively straightforward, has changed quite a bit since Kirchhoff's laws were plugged into the Bohr model of the atom. A little thing called Quantum Mechanics happened! Originally Posted by Charles Chandler I want to know why space photons require different physics. We want to know why you think that space photons require different physics, Charles Chandler ! They are described with exactly the same physics as any other photons. In the laboratory, cooler plasma is denser and so is more opaque. Ditto for a star. As for Calculations that is a bunch of programs with no relationship to your assertions. Where are your calculations from the actual physics. You know the stuff that physics students do all of the time. Charles Chandler: Five assertions that need evidence Originally Posted by Charles Chandler For you, if scientists say it's so, then those are "known laws of physics", even if they contradict laboratory science, such as solar photons. For me, they should be the same principles. That looks like you have the delusion that you can read my mind, Charles Chandler . For me, the known laws of physics are the scientific theories that have been backed up by so much empirical evidence that they are very, very likely to be correct (this "laws"). Empirical evidence is observations and experiments. For you, there seems to be the fantasy that different laws of physics are applied to astronomical objects. This is not true. Originally Posted by Charles Chandler So you're saying that 1) no 2) no CFDLs are impossible in stellar conduction zones because Conduction zones are turbulent thus no layers of anything can form. Double layers in stellar plasma have scales of 10-11 meters (solar core) to 10 meters (solar wind). Double layers are double layers () not multiple layered structures as you imagine. Double layers do not magically form wherever you want them to form! They need specific conditions to form. Double layers are not stable Regurgitating the actual science over and over may actually transmit some information to you eventually, Charles Chandler. Originally Posted by Charles Chandler I've said repeatedly that plasmas are compressible, but that they hit a limit, and that this limit is a function of ionization, which is typically a function of temperature. We know that plasmas are compressible and that they hit a limit. There is no such thing as a "room-temperature liquid limit" for plasma for the basic reason that plasma is not a liquid. [sarcasm] Plasma is compressible beyond your imaginary "room-temperature liquid limit". Plasma is compressible beyond your imaginary "room-temperature liquid limit". Plasma is compressible beyond your imaginary "room-temperature liquid limit".. Plasma is compressible beyond your imaginary "room-temperature liquid limit". Got it ? [/sarcasm] Stars such as the Sun compress plasma down to very high densities (about that of water at the core - using the known laws of physics). White dwarf stars do even better. Neutron stars do even better than that. Black holes are the ultimate compressors or plasma.
'13-07-25, 18:05 Reality Check	Originally Posted by Charles Chandler Indeed And it's not just that these "thermal bubbles" stop abruptly at precisely the same altitude, establishing a very distinct surface that shouldn't be there in a smooth density gradient. Once again - that is not evidence that the density gradient is not smooth. The detection of granules is evidence that the emission of light from the Sun's surface is from a relatively thin layer that gives the illusion of a distinct surface. We are told granules are driven by convection (which is really basic physics) and we know that this is plasma. We (unlike you, Charles Chandler) expect that there are "powerful non-Newtonian forces" at work, i.e. electromagnetic forces. Stellar plasmas are described using Magnetohydrodynamics Quote: Magnetohydrodynamics (MHD) (magneto fluid dynamics or hydromagnetics) is the study of the dynamics of electrically conducting fluids. Examples of such fluids include plasmas, liquid metals, and salt water or electrolytes. The word magnetohydrodynamics (MHD) is derived from magneto- meaning magnetic field, hydro- meaning liquid, and -dynamics meaning movement. The field of MHD was initiated by Hannes Alfvén,[1] for which he received the Nobel Prize in Physics in 1970. The fundamental concept behind MHD is that magnetic fields can induce currents in a moving conductive fluid, which in turn creates forces on the fluid and also changes the magnetic field itself. The set of equations which describe MHD are a combination of the Navier-Stokes equations of fluid dynamics and Maxwell's equations of electromagnetism. These differential equations have to be solved simultaneously, either analytically or numerically. Our point is that we dismiss your hypothesis because it is not even a hypothesis which at least has evidence for it. It is at best an idea. The lack of mathematics behind it almost gets it into the realm of fantasy. However the physical impossibility of the central premise (double layers I stellar plasma) does make it into a fantasy.
'13-07-25, 18:19 Reality Check	Originally Posted by Charles Chandler Then the question is, "What happens to the free particles?" The answer is easy if you think about the physics of plasmas. Plasmas are ionized and have free electrons ("free particles"). What happens to free electrons in plasmas? They whizz around at random between the positive ions. Now add more ionization from compression and more free electrons. These free electrons join the existing free elections and ... whizz around at random between the positive ions ! Originally Posted by Charles Chandler Can you cite laboratory research for the opacity of neutral hydrogen versus free electrons? Databases such as Astrophysical Opacities and TOPS Opacities use the physical properties of atoms determined from experiments to calculate opacities.
'13-07-25, 18:25 Reality Check	Originally Posted by Charles Chandler Figure 1. The solar limb seen in H-α (6563 à ), 2007-05-27, courtesy Fred Bruenjes. Now consider the fact that this picture was taken from Earth. If "1 km of STP air is more than enough to block it completely", I should expect the picture to be blank. No one needs to look at the picture to know that your expectation is wrong and that DeiRenDopa overstated with "more than enough to block it completely". The correct statement would be that it is "more than enough to lessen its intensity to be generally undetectable". The H-α band is detectable in H-α filtered images here on Earth. ETA: Your citation is bad. You should point to the original image with a full description. The solar limb seen in H-α is also taken in space-based telescopes. I can guess but not know that this is an image taken by Fred Bruenjes using a ground-based telescope. This is just a derail from the thread topic though because the Earth is not the Sun (one of the many mistakes that Michael Mozina made ).
'13-07-25, 18:37 Reality Check	Originally Posted by Charles Chandler Since when did PV = nRT include E? It does not explicitly include E (the Columb barrier). PV = nRT is an empirical law derived from observation and experiment. It includes all of the laws in those observations and experiments including the Columb barrier (and the strong force, weak force but ignoring gravity). It can be derived from the kinetics of an ideal gas. The barriers does vanish with temperature because particles with higher temperature have higher energies and so can overcome the barrier. It also vanishes with density (squeeze cold stuff together hard enough and the barrier is overcome). And yes - the barrier does not actually go away!
'13-07-25, 18:53 ben m	Originally Posted by Charles Chandler Since when did PV = nRT include E? There is no "E" associated with electron-proton interactions. There is a Coulomb potential, which looks like U = 1/r^2 in a vacuum (isolated charges) or like U = e^(-r / lambda)/r^2 in a plasma (the Debye length cuts it off). Do you see an energy scale in there? No. Anyway, when you actually derive the equation-of-state of a collection of interacting objects, to first order the form of the interaction potential *cancels out*. That's why PV= nRT is the equation of state of a Coulomb plasma, AND the equation of state of a collection of ideal billiard balls, AND the equation of state of a collection of Koosh balls, and so on. A correct treatment of the plasma equation of state shows that the Coulombic nature of the interaction DOES NOT MATTER. Certainly not at first order in pressure. Because the Debye length decreases with pressure, I'm pretty sure that the Coulomb potential drops out at second order too. Your guess, that it ought to matter, is wrong. It sounds like you were reasoning by analogy with atoms, but ignorant of what physics governs the atomic length/force scales you found in that analogy. Quote: No, the barrier doesn't vanish with temperature. It takes a certain temperature to overcome the Coulomb barrier in order to achieve nuclear fusion. In other words, when the inertial force becomes greater than the electrostatic repulsion, fusion becomes possible. See Coulomb Barrier for Fusion. The "coulomb barrier for fusion" is a statement about a relationship between collision energies and fusion-probabilities. If two particles collide at low energy, they have a low probability of fusion. (And a good thing too---recall that despite a typical solar-core particle undergoing trillions of collisions per second, the Sun will last for billions of years.) This is entirely irrelevant to the plasma equation of state.
'13-07-25, 19:19 Charles Chandler	Originally Posted by Reality Check We want to know why you think that space photons require different physics, Charles Chandler ! For one example, in the GSU webpage cited by edd entitled Transparency Temperature, it says, Originally Posted by GSU At temperatures higher than about 3000 K where the average kinetic energy of particles is about 0.26 electron volts, the formation of stable atoms is hindered. Above that temperature, matter exists in a plasma state of ionized atoms, which strongly absorbs electromagnetic radiation of all wavelengths, i.e., the plasma is opaque. But in this paper... Flannigan, D. J.; Suslick, K. S., 2005: Plasma formation and temperature measurement during single-bubble cavitation. Nature, 434: 52-55 ...I found the following image... Emissions from hot, high-pressure argon at various pressures. At 9000 K, pretty far above the 3000 K quoted by the GSU webpage, the argon still has distinct emission/absorption bands, and thus is not "absorbing EM radiation of all wavelengths" at all. Interestingly, under pressure the argon loses its spectral spikes. But the pressure that it takes to do this is not present within the optical depth of the Sun. This is just one of many discrepancies that I have observed in the literature between laboratory and solar physics. I can start a collection of such instances if you like. Originally Posted by Reality Check In the laboratory, cooler plasma is denser and so is more opaque. Ditto for a star. No, that's what I was saying, but phunk and edd are saying that cooler plasma is less opaque. Originally Posted by Reality Check Stars such as the Sun compress plasma down to very high densities (about that of water at the core - using the known laws of physics). Actually, the Dalsgaard model has a core density of 1.54e+5 kg/m3, which is 2 orders of magnitude greater than water.
'13-07-25, 19:40 Charles Chandler	Originally Posted by ben m The "coulomb barrier for fusion" is a statement about a relationship between collision energies and fusion-probabilities. If two particles collide at low energy, they have a low probability of fusion. (And a good thing too---recall that despite a typical solar-core particle undergoing trillions of collisions per second, the Sun will last for billions of years.) This is entirely irrelevant to the plasma equation of state. I'm not convinced. It takes a certain amount of collisional energy to achieve fusion. Another way of saying that would be that the inertial forces of the atoms have to exceed the Coulomb forces between them. If you're interested in whether or not the atoms fused, the Coulomb force matters, but if you're not, the force disappears? No, that force should still be there, and as a repulsion, it will affect the equation of state. The Coulomb force doesn't know that you're an astronomer and not a nuclear physicist. To neglect this force, you really have to entertain the concept of electron degeneracy. But this is only to be found in the astrophysical literature — I've never seen it mentioned in nuclear fusion research.
'13-07-25, 20:01 Reality Check	Originally Posted by Charles Chandler For one example, ... This is the application of the same laws of physics in different contexts and amazingly saying different things ! Transparency Temperature is a general statement that ignores absorption lines. Plasma formation and temperature measurement during single-bubble cavitation. has a graph about argon plasma that absorption lines You cannot compare the two. Originally Posted by Charles Chandler This is just one of many discrepancies that I have observed in the literature between laboratory and solar physics. I can start a collection of such instances if you like. It would be stupid not to expect discrepancies in the literature between laboratory and solar physics for the simple reason that laboratories cannot duplicate the conditions in the Sun. If these discrepancies are anything like the one you have listed then feel free to embarrass yourself by listing them, Charles Chandler ! Originally Posted by Charles Chandler No, that's what I was saying, but phunk and edd are saying that cooler plasma is less opaque. Let see: Originally Posted by phunk Hydrogen plasma is significantly more opaque than neutral hydrogen. No cooler plasma there, Charles Chandler! Originally Posted by edd Lets see if I can clarify, CC. What do you think has a higher opacity? An atom of neutral hydrogen or a free electron? No cooler plasma there, Charles Chandler! Originally Posted by phunk It gives you a gradient that will be fully opaque in less than the width of a pixel. You will not see it in the images you're looking at. No cooler plasma there, Charles Chandler! Originally Posted by phunk Charles, do you understand why the limb has a sharp edge in pictures yet? No cooler plasma there, Charles Chandler! No cooler plasma in earlier posts by plunk, Charles Chandler! No cooler plasma in earlier posts by edd, Charles Chandler! As far as I can see you have been talking about cooler plasma but phunk and edd have been comparing to neutral hydrogen. I am saying that that cooler and denser plasma gets more opaque because the mean free path of photons is smaller and they are scattered more. Transparency Temperature is about the Big Bang - plasma that was hot and dense and got cooler and less dense. My statement also does not apply to stellar plasma because it gets hotter and denser with depth.
'13-07-25, 20:20 Reality Check	Originally Posted by Charles Chandler I'm not convinced. Your conviction or not does not matter, Charles Chandler. The physics is that once you have material that can fuse in the right temperature and pressure region then fusion will happen. Quibbling about semantics is not wise, Charles Chandler. No one is saying that the Coulomb force vanishes. Everyone says that its effects vanish. Everyone says that Coulomb barrier is overcome or that the Coulomb barrier vanishes. This is irrelevant to the physics of plasma. Stellar fusion is basically just an energy source that ionizes gas and creates plasma. It is a source of plasma and we do not have to include fusion in the equations used to describe plasma. The Coulomb force is sort of neglected for astrophysical plasmas. Here the electric field can be derived from the magnetic field. Thus only the magnetic field is needed in the magnetohydrodynamics of plasma. ETA: You also should not confuse the Coulomb barrier in fusion with electron degeneracy pressure The Coulomb barrier is the Coulomb force between the positive nuclei. It needs to be overcome (the barrier "vanishes") to achieve fusion. Electron degeneracy pressure is the pressure between the electrons in a material. This provides a limit for the mass of star before it forms a neutron star. The total pressure includes PV=nRT. Materials are said to be electron degenerate at high enough densities and low enough temperatures that the total pressure is dominated by the degeneracy term. The fusion regime though is high densities and high temperatures.
'13-07-25, 20:48 Charles Chandler	Originally Posted by Reality Check The detection of granules is evidence that the emission of light from the Sun's surface is from a relatively thin layer that gives the illusion of a distinct surface. I don't understand this. Originally Posted by Reality Check We are told granules are driven by convection (which is really basic physics) and we know that this is plasma. We (unlike you, Charles Chandler) expect that there are "powerful non-Newtonian forces" at work, i.e. electromagnetic forces. I can't tell by the way you worded that whether you agree with the convective construct or not. As concerns EM forces, in that sense you would actually be like me, because that's what I'm saying. But we disagree in how EM forces are at work... Originally Posted by Reality Check Stellar plasmas are described using Magnetohydrodynamics I find the MHD explanations of granules to be unconvincing. In the quiet Sun, which is covered entirely by granules, the magnetic fields are relatively weak (
'13-07-25, 21:00 ben m	Originally Posted by Charles Chandler I'm not convinced. It takes a certain amount of collisional energy to achieve fusion. Another way of saying that would be that the inertial forces of the atoms have to exceed the Coulomb forces between them. If you're interested in whether or not the atoms fused, the Coulomb force matters, but if you're not, the force disappears? No, that force should still be there, and as a repulsion, it will affect the equation of state. The Coulomb force doesn't know that you're an astronomer and not a nuclear physicist. To neglect this force, you really have to entertain the concept of electron degeneracy. But this is only to be found in the astrophysical literature — I've never seen it mentioned in nuclear fusion research. Your understanding of the equation of state is so garbled that I don't quite know where to begin. I'm convinced that you are wrong because, as a graduate student, like all physics grad students, I took kinetic theory problems and solved them to find equations-of-state. I am telling you that, yes, the details of the Coulomb potential drop out of this calculation, because I've done this calculation myself and seen it happen. This is not guesswork, it's physics. As a nuclear-physics grad student, I also did calculations of fusion rates in hot plasmas. Yes, it is a different calculation. The details of the electromagnetic potential do NOT drop out of this different calculation. This is not guesswork, it's physics. "The nuclear force is a repulsion"? Wrong. In a hydrogen plasma, there are both e- and p+. e repels e, p repels p, but e ATTRACTS p. There are both positive and negative potentials; when you increase the density of a plasma you're increasing both.
'13-07-25, 21:17 Reality Check	Originally Posted by Charles Chandler I don't understand this. Well this is not a surprise, Charles Chandler ! Light is emitted from the photosphere which includes the granules. The photosphere is relatively thin. This gives the illusion that the sun has a sharp edge. Originally Posted by Charles Chandler I can't tell by the way you worded that whether you agree with the convective construct or not. I do - it is basic fluid mechanics that convection cells (granules) form. Originally Posted by Charles Chandler But we disagree in how EM forces are at work... Originally Posted by Charles Chandler I find the MHD explanations of granules to be unconvincing. Wow - are we going to get this "unconvincing = unable to understand the physics or maybe the English" assertion more, Charles Chandler ? There is no MHD explanation of granules - that is fluid mechanics. Look at pot of boiling water sometime or better yet - Bénard cells. There is a convincing and valid MHD theory of plasma. You are making yourself look ignorant about granules, Charles Chandler Quote: Granules on the photosphere of the Sun are caused by convection currents (thermal columns, Bénard cells) of plasma within the Sun's convective zone. The grainy appearance of the solar photosphere is produced by the tops of these convective cells and is called granulation.
'13-07-25, 21:35 Charles Chandler	Originally Posted by Reality Check There is no MHD explanation of granules - that is fluid mechanics. Look at pot of boiling water sometime or better yet - Bénard cells. I don't understand how Bénard cells can achieve supersonic speeds just on the basis of buoyancy.
'13-07-25, 21:50 Reality Check	Originally Posted by Charles Chandler I don't understand how Bénard cells can achieve supersonic speeds just on the basis of buoyancy. Who cares about this, Charles Chandler, when the astronomers who study the subject have no problem with it? If you are interested then research it yourself. There is the small possibility that this is the crank stance of "I do not understand it so it is wrong" but it is more probably a derail from the destruction of the basis of your idea: Originally Posted by Reality Check CFDLs are impossible in stellar conduction zones because Conduction zones are turbulent thus no layers of anything can form. Double layers in stellar plasma have scales of 10-11 meters (solar core) to 10 meters (solar wind). Double layers are double layers () not multiple layered structures as you imagine. Double layers do not magically form wherever you want them to form! They need specific conditions to form. Double layers are not stable.
'13-07-25, 22:11 Charles Chandler	Originally Posted by ben m Your understanding of the equation of state is so garbled that I don't quite know where to begin. I'm convinced that you are wrong because, as a graduate student, like all physics grad students, I took kinetic theory problems and solved them to find equations-of-state. I am telling you that, yes, the details of the Coulomb potential drop out of this calculation, because I've done this calculation myself and seen it happen. This is not guesswork, it's physics. As a nuclear-physics grad student, I also did calculations of fusion rates in hot plasmas. Yes, it is a different calculation. The details of the electromagnetic potential do NOT drop out of this different calculation. This is not guesswork, it's physics. "The nuclear force is a repulsion"? Wrong. In a hydrogen plasma, there are both e- and p+. e repels e, p repels p, but e ATTRACTS p. There are both positive and negative potentials; when you increase the density of a plasma you're increasing both. Oh, OK. Well then my new "fuse whatever you want" machine is actually going to work. (How was I supposed to know?) Because I'm feeling selfless, I'll go ahead and release this into the public domain, so people can start fusing heavy elements and stuff. Here's the plan: Drill a hole in the ground, say 1 cm wide and 100 meters deep. Insert a tungsten pipe into the hole. Stick a plunger into the hole, and add a bunch of weight to it (like a couple of tons or something). This will compress the air in the pipe. This will create a bunch of heat, but that's OK, because we used a tungsten pipe that has a very high melting point, and because the Earth will act as a heat sink. At some point, the hydrostatic pressure of the compressed air will equal the weight on the plunger, and the plunger won't drop down anymore. At this point, we can break off and go get some beer & burgers or something. As the heat radiates out of the pipe and into the surrounding soil, the hydrostatic pressure will relax. But wait — we left the weight on the plunger, so it will press down again. Or more accurately put, the hydrostatic pressure stays the same, but as the temperature drops, so does the volume. Eventually, the volume will have been reduced so much that the nitrogen and oxygen atoms will start fusing into heavier elements. We can mark on the plunger how far it has to push down to finish fusing which elements. So we could let it go for a couple of days, and then pull the plunger out, and if we find a little puddle of iron at the bottom of the pipe, then we label that notch as the Fe notch. We could have notches for gold, platinum, tin, or whatever we felt like fusing. Since density is purely a function of the ideal gas laws, and since we devised a method for putting matter under a lot of pressure, and since we did so in a manner that included a heat sink, we can now just whip up any elements we want, right in our backyards. Would this work? I'm thinking that if we can get the temperature hot enough to turn whatever-it-is-in-there into plasma, but not hot enough to melt the tungsten pipe, this has just gotta work, and stuff. And since you already worked out the equations of state for plasma, and found that density is just a function of temperature and volume, we already have the math to prove it. (In reality, I think that there's a little more to it than that. But I'll let you explain.)
'13-07-25, 22:19 Charles Chandler	Originally Posted by Reality Check Who cares about this, Charles Chandler, when the astronomers who study the subject have no problem with it? If you are interested then research it yourself. There is the small possibility that this is the crank stance of "I do not understand it so it is wrong" but it is more probably a derail from the destruction of the basis of your idea: I did research it, and the Wikipedia article said that the fastest that any gas (or plasma) can flow into a pure vacuum is the speed of sound, and that's by definition. This means that supersonic speeds driven by buoyancy are not physically possible. So OK, astronomers who study the subject have no problem with a construct that isn't physically possible. That's not the first time that I've heard that. But in what sense am I wrong for considering other possible explanations? They can edit the Wikipedia article on granules if it turns out that I'm right.
'13-07-25, 22:26 Reality Check	Originally Posted by Charles Chandler I did research it, and the Wikipedia article said that the fastest that any gas (or plasma) can flow into a pure vacuum is the speed of sound, and that's by definition. Before you research something you have to understand what you are researching, Charles Chandler . What is the fastest that a bunch of plasma (a granule) can move through plasma (the photosphere), Charles Chandler? What is the speed of sound in a plasma, Charles Chandler? Astronomers who study the subject have no problem with a "construct" that is physically possible. The problem is that do you not know what the "construct" is! P.S. Just what is that mysterious Wikipedia article?
'13-07-25, 22:39 Reality Check	Originally Posted by Charles Chandler Here's the plan: Your plan, Charles Chandler, is: Do something irrelevant to the topic of fusion. Ditto etc. etc. etc. You have not understood a simple physical fact: high pressure does not equal high speed. It is high temperatures that give the high speeds needed by nuclear fusion. To get nuclear fusion you need high temperatures to give high speeds to the atoms to overcome the Coulomb barrier. To get sustained nuclear fusion as in the Sun you also need high pressure to maintain the reaction rate (otherwise you have a nuclear bomb).
'13-07-25, 22:46 Reality Check	One of those astronomers that you deny exists Charles Chandler ! Supersonic flows in granules predicted (physically possible!) -Luis Ramon Bellot Rubio measures them: Detection of supersonic horizontal flows in the solar granulation Quote: Hydrodynamic simulations of granular convection predict the existence of supersonic flows covering ~3-4% of the solar surface at any time, but these flows have not been detected unambigously as yet. Using data from the spectropolarimeter aboard the Hinode satellite, I present direct evidence of fast horizontal plasma motions in quiet Sun granules. ...
'13-07-25, 22:51 Reality Check	Magnetic field intensification: comparison of 3D MHD simulations with Hinode/SP results Quote: Aims: By comparing with synthetic observations derived from MHD simulations, we investigate the physical processes underlying the observations, as well as verify the simulations and the interpretation of the observations. ... Conclusions: The observed events are consistent with the process of field intensification by flux advection, radiative cooling, and evacuation by strong downflow found in MHD simulations. The quantitative agreement of synthetic and real observations indicates the validity of both the simulations and the interpretations of the spectro-polarimetric observations.
'13-07-25, 22:53 Reality Check	Hydromagnetic structure of the chromosphere near the supergranule boundary Quote: A Bernoulli flow along magnetic lines of force and the balance of forces perpendicular to it are considered to form the hydrodynamic structure of the chromosphere near the supergranulation boundary. A preliminary supersonic flow model is constructed by use of simplifying assumptions. For this model, the effective kinetic temperature, including the contribution of waves, is required to be as high as 6500 K but may be reduced substantially by improved treatment. An explanation is given of how the magnetic field and the flow regulate themselves to give supersonic velocities and height extension in the chromosphere near the supergranulation boundary. The temperature excess and the speed of downdraft are also shown to be consistent with observations. (but for supergranules!)
'13-07-25, 22:57 Reality Check	General supersonic flows (and unexpected!) may be of interest: Supersonic flows in the solar photosphere Quote: Except for sunspot penumbrae, very few instances of supersonic mass flows in the photosphere were known a few years ago. The situation has changed dramatically thanks to the extremely high spatial resolution provided by Hinode, SUNRISE, and the Swedish 1-m Solar Telescope. Using spectropolarimetric measurements from these instruments, supersonic flows have been discovered both in the quiet Sun and in active regions, in places where they were completely unexpected. Most of them are directed downward, but there are also cases of upward and horizontal motions. Quiescent, relatively stable structures that harbor supersonic flows include granular cells, small-scale flux tubes undergoing convective collapse, pores, light bridges, and sunspot penumbrae (at all radial distances). An overview of these flows will be given, emphasizing their properties and effects on higher atmospheric layers.
'13-07-25, 22:59 Reality Check	Fast horizontal flows in a quiet sun MHD simulation and their spectroscopic signatures Quote: Numerical simulations of solar surface convection have predicted the existence of supersonic horizontal flows in the photospheric granulation. Recently, the detection of such flows in data from the Hinode satellite was reported. We study supersonic granular flows in detail to understand their signatures in spectral lines and to test the observational detection method used to identify these flows in the Hinode observations. We perform time-dependent 3D radiative MHD numerical simulations and synthesize the Fe i 6302 Ã spectral lines at the resolution of the Hinode data for different viewing angles covering the center-limb variation. There is very large variation in the detailed shape of the emergent line profiles depending on the viewing angle and the particular flow properties and orientation. At the full simulation resolution the supersonic flows can even produce distinct satellite lines. After smearing to the Hinode resolution sufficient signature of supersonic motion remains. Our analysis shows that the detection method used to analyze the Hinode data is indeed applicable. However, the detection is very sensitive to ad hoc parameter choices and can also misidentify supersonic flows.
'13-07-25, 23:05 Reality Check	I have to cite this just for the title! New Light on the Heart of Darkness of the Solar Chromosphere
'13-07-26, 01:28 ben m	Originally Posted by Charles Chandler Since density is purely a function of the ideal gas laws, and since we devised a method for putting matter under a lot of pressure, and since we did so in a manner that included a heat sink, we can now just whip up any elements we want, right in our backyards. ? According to the ideal gas laws, your device reaches fairly ordinary earthlike temperatures and pressures while bringing the ram to a halt, then reaches an even-more-ordinary equilibrium pressure sufficient to hold up the ram at ambient temperature. The fusion rate in such a gas is so close to zero as to be negligible. Your step 8 is completely off the mark. If you thought otherwise, perhaps it's because you daydreamed that the ideal gas law failed in this thought experiment, rather than actually pulling out a calculator and finding out.
'13-07-26, 03:55 Dancing David	Originally Posted by Charles Chandler Since when did PV = nRT include E? No, the barrier doesn't vanish with temperature. It takes a certain temperature to overcome the Coulomb barrier in order to achieve nuclear fusion. In other words, when the inertial force becomes greater than the electrostatic repulsion, fusion becomes possible. See Coulomb Barrier for Fusion. Sorry Charles, what exactly does that have to do with the discussion, how does it effect the compression of hydrogen and helium? And you seem to be unaware that actual QM is needed for hydrogen fusion to occur and overcome the Coulomb force.
'13-07-26, 04:02 Dancing David	Originally Posted by Charles Chandler I'm not convinced. It takes a certain amount of collisional energy to achieve fusion. Another way of saying that would be that the inertial forces of the atoms have to exceed the Coulomb forces between them. No it isn't, you just assume it. The relationship is as Ben stated and you are showing a certain unnamed effect here. As two bare protons approach the Coloumb barrier will approach infinity regardless of the energy involved, yes or no Charles? Quote: If you're interested in whether or not the atoms fused, the Coulomb force matters, but if you're not, the force disappears? No, that force should still be there, and as a repulsion, it will affect the equation of state. The Coulomb force doesn't know that you're an astronomer and not a nuclear physicist. To neglect this force, you really have to entertain the concept of electron degeneracy. But this is only to be found in the astrophysical literature — I've never seen it mentioned in nuclear fusion research. Why not ask what Ben was talking about , did you read his post, if you don't understand it, then you should ask questions about plasma and things he mentions, rather than assert your unfounded ideas.
'13-07-26, 04:06 Dancing David	Originally Posted by Charles Chandler Oh, OK. Well then my new "fuse whatever you want" machine is actually going to work. (How was I supposed to know?) Because I'm feeling selfless, I'll go ahead and release this into the public domain, so people can start fusing heavy elements and stuff. Here's the plan: Drill a hole in the ground, say 1 cm wide and 100 meters deep. Insert a tungsten pipe into the hole. Stick a plunger into the hole, and add a bunch of weight to it (like a couple of tons or something). This will compress the air in the pipe. This will create a bunch of heat, but that's OK, because we used a tungsten pipe that has a very high melting point, and because the Earth will act as a heat sink. At some point, the hydrostatic pressure of the compressed air will equal the weight on the plunger, and the plunger won't drop down anymore. At this point, we can break off and go get some beer & burgers or something. As the heat radiates out of the pipe and into the surrounding soil, the hydrostatic pressure will relax. But wait — we left the weight on the plunger, so it will press down again. Or more accurately put, the hydrostatic pressure stays the same, but as the temperature drops, so does the volume. Eventually, the volume will have been reduced so much that the nitrogen and oxygen atoms will start fusing into heavier elements. We can mark on the plunger how far it has to push down to finish fusing which elements. So we could let it go for a couple of days, and then pull the plunger out, and if we find a little puddle of iron at the bottom of the pipe, then we label that notch as the Fe notch. We could have notches for gold, platinum, tin, or whatever we felt like fusing. Since density is purely a function of the ideal gas laws, and since we devised a method for putting matter under a lot of pressure, and since we did so in a manner that included a heat sink, we can now just whip up any elements we want, right in our backyards. Would this work? I'm thinking that if we can get the temperature hot enough to turn whatever-it-is-in-there into plasma, but not hot enough to melt the tungsten pipe, this has just gotta work, and stuff. And since you already worked out the equations of state for plasma, and found that density is just a function of temperature and volume, we already have the math to prove it. (In reality, I think that there's a little more to it than that. But I'll let you explain.) So instead of asking questions about plasma and how it functions, you resort to an analogy about something other than plasma? Really, no questions about what Ben said just a bad analogy? Is there plasma in the pipe?