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24th March 2011, 04:37 PM | #81 |
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24th March 2011, 04:43 PM | #82 |
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24th March 2011, 04:49 PM | #83 |
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NASA Finds Direct Proof of Dark Matter (another observation) (and Abell 520) Electric comets still do not exist! |
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24th March 2011, 04:55 PM | #84 |
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25th March 2011, 01:19 AM | #85 |
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Michael, are you this Michael Suede?
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25th March 2011, 01:30 AM | #86 |
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No Alfvén lets a double layer explode in a circuit, e.g. in the magnetic loop of a solar prominence. This mechanism is not the same as what happens in magnetic reconnection.
So, once more, take the data from the Runov et al. (2003) paper and show us exactly where this double layer is supposed to be. Don't come with statements like "there has to be a double layer" because "there are different plasmas" and then quote Alfvén, who is clearly taking about a double layer created in a current carrying plasma. The two kinds of double layers are not the same. Maybe you should read the double layer wiki page, which is for the biggest part the introduction chapter of my PhD thesis. That is just silly, even MHD uses Maxwell's equations. If you have two regions of oppositely directed magnetic field in a plasma then a current sheet has to exist. It is just a consequence of curl(B) = μ J. Alfvén turns around in his grave when his so-called defenders make claims like this. The figure by Rolf Boström is nice, to see a substorm in a circuit representation. But as I have told MM before, and I probably need to tell you too, circuit representation of plasma physical processes is the long wavelength approximation of the plasma physics equations, not unlike Alfvén when developing MDH (and why in MDH you often find circuit representations), therefore, per definition, a circuit representation cannot describe the process of magnetic reconnection. It can only indicate that something happens and estimates can be made about the power that may or may not be released, however the small scale physics can never be described, let alone the reconfiguration of the magnetic field around the X-point/line. If you would know plasma physics, or even know a little bit about Maxwell's equations, you would understand why a current sheet needs to be there, and is actually measured and it can be modeled, and the Harris model seems most often to be very appropriate. |
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25th March 2011, 03:50 AM | #87 |
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The only time that magnetic reconnection is mentioned in these proceedings is in Alfvén's keynote address, where he discusses magnetic merging. Basically, he is claiming there that reconnection cannot happen in ideal MHD, something any plasma physicist know by now, and e.g. the reason why numerical modeling of MRx can only be done in resistive-MHD, however, some of the times you may see that an MDH code is used, but because of the numerical errors in the programming (due to rounding errors) there is a numerical diffusion, which represents the resistivity of the plasma.
Especially the last comment by Alfvén is very strange: "anyone believing in magnetic merging does not believe that double layers exist", or that "whenever a double layer is found it is another nail to the coffin of magnetic merging." Although a keynote address is supposed to be challenging and thought provoking, the latter comment for example makes no sense at all, because double layers are found above the auroral regions, where the electrons are accelerated Earthward, and nobody would ever suggest that in that region magnetic merging would be a feasable process to occur. So michaelsuede, please explain the observations by Runov et al. (2003) with a double layer, I am very interested how you are going to explain all the magnetic signatures. |
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25th March 2011, 06:40 AM | #88 |
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As we've already verified, Michael has no idea what that equation means.
This thread is analogous to someone saying "pneumonia can never be caused by bacteria, that's nonsense!" and then turning out not to know that bacteria are small organisms with DNA that can be grown in petri dishes. |
25th March 2011, 09:33 AM | #89 |
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25th March 2011, 10:20 AM | #90 |
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The Cluster signatures are inconsequential as to the issue of reconnection when taken from Alfven's point of view.
Alfven is contending that the onset of a substorm is caused by the creation of a DL which redirects the tail current into ionosphere. Alfven gives a crude picture of how and why the neutral sheet is formed in this paper: http://articles.adsabs.harvard.edu/c...;filetype=.pdf And explains the substorms generally here: Figure 11. Bostrom(1974) has given a summary of his theory of magnetic substorms in the form of a circuit. Solar wind energy produces a cross-tail current in the neutral sheet. The arrow indicates that this current can give rise to a very large voltage. (In our terminology, it should be replaced by the DL symbol.) This causes the circuit energy to be discharged over the ionosphere, where it is observed as a magnetic substorm. At substorm onset, the resistance of the neutral sheet increases because a DL is produced and the tail current is redirected to the ionosphere. |
25th March 2011, 10:47 AM | #91 |
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"I have built a vacuum-tube that emits x-rays. Therefore I understand neutron star binaries from my own point of view. Don't bother showing me Chandra telescope data, they're inconsequential."
ETA: either the data agree with your model and/or a competing model; or the data do not agree with your model and/or a competing model. There is no such thing as inconsequential data. Unless you actually have no idea what's going on, and are making excuses for why you won't discuss anything except what's pre-loaded onto your shovel. |
25th March 2011, 11:02 AM | #92 |
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Alfven gives a treatment of why neutral point reconnection is wrong in his book "Cosmic Plasma" from a theory point of view.
Until it can be demonstrated that there is no DL formation/explosion at substorm onset, there is no reason to conclude that 'magnetic reconnection' is a function of novel plasma properties. |
25th March 2011, 11:11 AM | #93 |
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First: No one is asking whether Alfven had a theory. We knew that. Many people have theories. Many of them are wrong. This is a discussion of the real world, as measured by the Cluster spacecraft (whose data look like reconnection) and as governed by Maxwell's Equations (whose allowable B fields allow for reconnection.)
Do you even remember posting the following?
Quote:
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25th March 2011, 11:42 AM | #94 |
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25th March 2011, 11:50 AM | #95 |
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So you deliberately write for people who don't understand the field in question? This really reminds me about a thread here on crackpot physics and why there is so much of it; engineers are so commonly involved in it
[With apologies to then sane majority of engineers, I live with two of them.] |
25th March 2011, 12:06 PM | #96 |
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25th March 2011, 12:18 PM | #97 |
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And what current would that be exactly? The same current as the substorm current wedge? From the THEMIS results it has been found that the creation of the substorm current wedge is not the onset of the substorm.
Also, how is the double layer producing the fast plasma flows (both electrons and ions) towards the Earth, including the flux transport of magnetic field? Also, the Cluster observations are very consequential, as they show that all signatures that are associated with magnetic reconnection are actually there in the Earth's magnetotail. Just dismissing data because they do not fit your preconceptions is hardly scientific. Alfvén has cut open the magnetotail here. And he shows how the currents are closed, this is a rather crude superposition model of a dipole and a background field and some varying field, but then, it is a paper from 1981. Note the neutral line that is in the model, just for that you should dismiss this model immediately, because there cannot be a B=0 point in a 3D magnetic field according to you. No, this is not an explanation of a substorm, this is a circuit model of a substorm, there is quite a difference. For one, you don't see any real physics in that circuit model, everything is just averaged and put into large scale properties as one resistivity or one capacitance etc. etc. All the details that are taking place in the Earth's magnetotail disappear in this kind of description. No large scale double layer has been measured in the tail at the creation of the substorm current wedge. There are a lot of instabilities measured there, but from none of them arises a double layer. Basically the region where this starts shows ballooning instability, and drives a possible current disruption (which is NOT an exploding double layer). Keeping haning on to old papers is not going to bring anything when you subsequently dismiss the best measurements of the tail ever by Cluster and THEMIS. |
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25th March 2011, 12:28 PM | #98 |
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Unfortunately, the EU/ES/EC/PU/PC proponents have switched off physics after Alfvén wrote Cosmic Plasma. Next to that most of them have not got the foggiest about real plasma physics or even simple electrodynamics.
In this case here michaelsuede just has a certain group of links and prepared answers and comments that will be repeated ad infinitum, and any observations, measurements or theoretical developments after ~1981 will be discarded as non-consequential. We know this e.g. from the other michael on this forum, who stems from the same group. Basically, this discussion here is totally useless because MS just like MM is not going to listen to any modern day explanations. |
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25th March 2011, 01:05 PM | #99 |
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"As long as it is admitted that the law may be diverted from its true purpose -- that it may violate property instead of protecting it -- then everyone will want to participate in making the law, either to protect himself against plunder or to use it for plunder. Political questions will always be prejudicial, dominant, and all-absorbing. There will be fighting at the door of the Legislative Palace, and the struggle within will be no less furious." - Bastiat, The Law |
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25th March 2011, 01:21 PM | #100 |
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There are 2 or 3 people here I am pretty sure can argue/discuss this with you meaningfully. None of us AFAIK can make you any money or make you famous. So, why are you trying to convince us. Publish in Nature or other juried journal. That is what will accomplish something
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25th March 2011, 01:27 PM | #101 |
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Also, from the part I quoted,: "stated " is poor phrasing. We tend to look for phrasing like "this set of experiments/observations/equations appear to demonstrate conclusively that...." followed by full descriptions with all appropriate and necessary documentation of the afformentioned experiments/observations/equations.
We tend to be funny that way. As do the respected journals. |
25th March 2011, 01:34 PM | #102 |
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I'm not dismissing the cluster observations of where the onset of "reconnection" occurs.
I am disputing its cause. I am saying there is a current instability in the neutral sheet leading to the creation of a double layer facilitating a "reconnection" event. And I am saying this is all a consequence of Alfven's circuit model of the magnetosphere, which is part of a larger solar circuit. Lessons from laboratory experiments on reconnection http://www.sciencedirect.com/science...3&searchtype=a Double layer formation during current sheet disruptions in a reconnection experiment http://plasma.physics.ucla.edu/Older...le%20Layer.pdf Magnetic Field Line Reconnection Experiments, 5. Current Disruptions and Double Layers http://plasma.physics.ucla.edu/Older...%20Disrupt.pdf Laboratory experiments on current sheet disruptions, double layers turbulence and reconnection http://adsabs.harvard.edu/full/1985IAUS..107...47S |
25th March 2011, 01:41 PM | #103 |
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(rm)
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25th March 2011, 01:43 PM | #104 |
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25th March 2011, 02:57 PM | #105 |
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Well, actually, you got it backwards.
From a quick scan from Walters papers I seem to get the impression that he talks about reconnection and in the associated current sheet between the magnetic field they are able to increase the current so much, that instabilities can start up, leading, amongst others, to double layers in the current sheet. To be specific: Look in the last link to figure 2 where the magnetic field in XZ is shown and the fluid velocity. Now, the current in the current sheet is flowing in the Y direction, out of the screen. Now what they do in the section "current disruption and double layers" is that they artificially increase the potential in the Y direction, thereby increasing the current in the current sheet, and, as expected, when crossing a critical limit, there will be instabilities. HOWEVER, note that the starting point is the general X-line configuration for reconnection as shown in Fig. 2. The current disruption and double layers only appear later. Therefore, the double layer is not facilitating or starting the reconnection, but rather is a possible structure that may or may not arise in the current sheet, depending on how hard the current is driven. And yes, that may be applicable in space plasmas, indeed I myself have written a paper on the stability of double layers and its application so solar flares. No, it cannot be a consequence of Alfven's circuit model of the magnetosphere. Again, a circuit model is good to look a things globally, there is no plasma physics in a circuit model, it is "only" electric circuit theory with batteries, resistances, inductances, capacitances. Anything that is going on at the scale of where things are getting interesting is swept under the carpet. That is a good thing, I have done circuit calculations myself, but look at this paper and see e.g. that in order to calculate the resistance of the accretion disk I really needed to go into the microscopic plasma physics. Then, when I got the answer, I could put that into the circuit. |
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25th March 2011, 04:37 PM | #106 |
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semantics.
If you say reconnection starts at the onset of instabilities, then you would be right. Of course, I don't see it that way because you can have instabilities without generating a double layer and initiating an explosive release. From "Double layer formation during current sheet disruptions in a reconnection experiment" it is clear that the double layer plays an important role in kinetic energy transfer. The cause of a "reconnection" event is the formation of a DL and its associated energy transfer. That is what causes a reconnection event. The instabilities leading to a DL are a consequence of the circuit. |
25th March 2011, 05:52 PM | #107 |
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25th March 2011, 07:41 PM | #108 |
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25th March 2011, 10:43 PM | #109 |
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How can the reconnection be caused by the double layer when the double layer only appears after the reconnection is already started? (see Fig. 2) That is not semantics it is causality.
Secondly the double layer accelerates the plasma in the wrong direction i.e. in the Y direction, whereas the reconnection accelerates the plasma in the X direction (see Fig. 2). Yes, instabilities will most likely be present in the current sheet near the neutral line as they are always present in plasmas. And by the way, I hope you do understand that these double layers that we are discussing right now are completely differnt entities as the ones you claimed at the beginning of the thread? These are current carrying double layers, whereas at the beginning you were discussing non-current carrying double layers at the boundary between different plasmas. |
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26th March 2011, 01:59 AM | #110 |
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26th March 2011, 05:29 AM | #111 |
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26th March 2011, 11:58 AM | #112 |
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I just knew we would have some people who could discuss this from a real knowledge base. Well done!!!!!
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26th March 2011, 03:12 PM | #113 |
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I love the part where "magnetic reconnection is impossible" gets cited as proof that Einstein was wrong. Um? Was this even supposed to be a list of arguments relevant to trying to prove Einstein wrong? Or was it just another excuse to haul out the Plasma Cosmology link-shovel?
I prefer to imagine that it's just a tic. It's like, when you or I is getting onto an airplane, the gate agent takes our ticket and says "Have a good trip" and we accidentally say "you too"? Oops! Michael Suede gets onto the jetway, the agent says "Enjoy your flight" and Suede says "Alfven's circuit model proves that reconnection is impossible." Oops! Sorry! I figure the agents hear that so often they don't notice it any more. |
26th March 2011, 04:57 PM | #114 |
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27th March 2011, 11:19 AM | #115 |
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Comments on Magnetic Reconnection V
Oh, really?
Originally Posted by michaelsuede
That was originally posted on 13 February 2009. It is not exactly "news". I find in an amusing michaelsuede has the capacity to declare that which we actually see before our very eyes as "impossible". There is a huge literature available on magnetic reconnection, both in theory and in practical application (i.e., as observed controlled laboratory experiments). Only in the ravings of the internet lunatics do we find anyone who thinks that all of this physics must be impossible. So I suggest that the attentive reader graduate from the webpages of the illiterati and try on literature intended for adults instead. See, for instance, Magnetic Reconnection - MHD Theory and Applications by Priest & Forbes, Cambridge University Press 2000, a book I have repeatedly recommended and use myself as my standard reference. And for more advanced plasma physics, try Nonlinear Magnetohydrodynamics by Dieter Biskamp, Cambridge University Press 1993 & 1997, especially chapter 8, "Magnetic Reconnection". Or perhaps I might even humbly suggest some of my own many posts on magnetic reconnection in this forum; e.g., Electric Sun: Reconnection vs Induction II (25 Jan 2011), Electric Sun & Magnetic Reconnection X (18 Jan 2011), Electric Sun & Magnetic Reconnection VIII (13 Jan 2011), Electric Sun & Magnetic Reconnection I (30 Nov 2010), Magnetic Reconnection Redux V (30 Dec 2009) & etc. Mr. Suede's dismissal of magnetic reconnection is based on profound ignorance, not on profound knowledge, and is void of merit. |
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27th March 2011, 11:42 AM | #116 |
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27th March 2011, 12:19 PM | #117 |
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28th March 2011, 02:30 AM | #118 |
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Just an addition to the list of Tim Thompson:
Masaaki Yamada, Russell Kulsrud, Russell an Hantao Ji, Magnetic reconnection, Reviews of Modern Physics, vol. 82, Issue 1, pp. 603-664, 2010. A most excellent review paper. |
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28th March 2011, 09:44 AM | #119 |
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28th March 2011, 10:58 AM | #120 |
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It seems those denying the existence of magnetic reconnection missed some of these... If someone disagrees with the above references, maybe some quantitative objective analysis is in order. Maybe it's time those arguing against the existence of magnetic reconnection point out where all that research has failed, specifically, quantitatively, and objectively. For some reason contemporary research seems to be off limits to the crackpots, and no such legitimate refutation is ever offered. Why should the entire world of legitimate physicists concede to the ranting of a half dozen cranks who obviously don't understand math and offer nothing more than arguments from incredulity and ignorance? Why should folks engaged in real science pay any heed to those who dishonestly misrepresent the research of a handful of dead scientists? How is it the against-the-mainstream proponents believe they are smart enough to know something that genuine scientists don't know, but are wholly incapable of communicating those ideas in a way that is compelling and understandable? It does seems to come down to this... It's 2011, and that's how it is in the world of real science. That is also, no doubt, how it will continue to be. |
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