Tim Thompson
Muse
- Joined
- Dec 2, 2008
- Messages
- 969
Magnetic Reconnection In Vacuo VIII
To this Mozina responds in post 6111 by selecting out a few key words of his own to rationalize his selective interpretation of the paper. Herein I will refute Mozina's sloppy attempt to refute me.
The following are the three paragraphs that make up the full test of section 5 ("Toy Model for Vacuum Reconnection"), pages 17-19 in the paper Aspects of Three-Dimensional Magnetic Reconnection; E.R. Priest & C.J. Schrijver; Solar Physics 190(1/2): 1-24, December 1999. I reproduce the test only, but the paper (PDF) including the referenced figures, as well as the CD-ROM contents (99.2 MBytes zip archive) can be accessed from the paper's webpage at Solar Physics ( http://www.springerlink.com/content/l702082772n234t2/fulltext.html ). All emphasis (e.g., italics) is found in the original, except the bold face paragraph title, which is mine.
Paragraph 1
"We have constructed a toy model for vacuum reconnection driven by the motion of photospheric sources and have presented the results in the accompanying CD-ROM. We calculate the potential magnetic field due to two, three or four sources in the solar surface and then extend it to a many-source case in which the surrounding fields generally limit the motions of the field lines in response to the footpoint motions to much smaller amplitudes than in the few-source case. The sources are slowly moved around and we assume that the field remains potential. Although this is an oversimplified model, the resulting motion of the field lines is instructive and it is a useful preliminary for the resistive MHD numerical model that we are planning to undertake."
This is the paragraph that sets the stage, so to speak. See the very first sentence: "We have constructed a toy model for vacuum reconnection driven by the motion of photospheric sources ..." This should be clear enough for anybody, but evidently not Mozina. What is there to say but this: vacuum reconnection is reconnection that takes place, strangely enough, in a vacuum. Indeed, look at the title for the section, "Toy Model for Vacuum Reconnection". Could the authors have been more clear? Yet, Mozina continues to stubbornly foist upon us the fairy tale that this is all MHD, all really currents reconnecting in a plasma, despite explicit language from the authors to the contrary. And pay attention to the part about "driven by the motion of photospheric sources". That does not mean that the photosphere is at all involved in this process, it means that the motions of the sources that drive the vacuum reconnection are chosen to match the observed motions of photospheric sources. This is no great surprise, since the eventual goal is to study magnetic reconnection in the solar corona. This is all reinforced by the comment about footpoint motions; same thing, the motions of the sources match the motions observed for real solar footpoints. Nowhere can we find any evidence, any language, any indication at all that the magnetic reconnection takes place anywhere except a vacuum, as explicitly indicated in the text.
The only mention of MHD is a plan to create a resistive-MHD model in the future. This is not an unimportant point. As is well known, all forms of magnetic field line reconnection in a plasma are possible only in the realm of resistive MHD. Magnetic field line reconnection in a plasma is not physically possible in the realm of ideal MHD. If the authors are already using MHD, then it must be only resistive MHD, but then why would they say they have not done that yet and plan to do so in the future? This only serves to reinforce the obvious point: in this study the magnetic field line reconnection all happens in a vacuum, just like the authors said it did.
Magnetic field line reconnection in a vacuum is easy, just solve Maxwell's equations, no plasma complications required. But it is also boring because it does not do anything remotely interesting, except perhaps allow cute animations. However, magnetic field line reconnection in a plasma can get really exciting. So what the authors have done here is model magnetic field line reconnection in a vacuum (which is what they said they were doing, and I assume the authors actually do know what they did), as a preliminary exercise, just to see how the field lines behave, as a benchmark for later, resistive MHD studies of magnetic field line reconnection in a plasma. In the absence of seriously complicating issues, the reconnection of magnetic field lines in a plasma should look similar to reconnection in a vacuum
Paragraph 2
"First of all, we consider a simple model of binary reconnection due to the motion of two sources (Figure 14(a)). The right-hand source is the larger and it performs an orbit around the other source, during which we keep the directions constant of most of the field lines from the larger source. The way in which the field lines reconnect by changing from being open to closed and back to open can be seen clearly. (Of course, if the field lines are potential, we cannot prescribe both footpoints of a field line as the sources move around, so the choice of which field line directions at the source to keep fixed is entirely arbitrary.) Then we added a third (Figure 14(b)) and a fourth (Figure 14(c)) source and as the sources move slowly around, a rapid counter-flipping of the field lines can be seen due to fan reconnection or separator reconnection. The flipping occurs as they reconnect and move close to the separatrix surface."
Having set the stage in the first paragraph, here we find the description of what is really happening. Notice the comments, "The way in which the field lines reconnect by changing from being open to closed and back to open can be seen clearly"; "a rapid counter-flipping of the field lines"; "The flipping occurs as they reconnect and move close to the separatrix surface." In all cases field lines do the reconnecting. Not "field aligned currents", just "field lines". Now I think it is safe to assume that Priest & Schrijver both know what a field line is, what a field aligned current is, and how to tell the difference between them, especially in their own simulation. Furthermore, as already established above, we have magnetic field lines reconnecting in a vacuum.
Paragraph 3
"These simple experiments demonstrate a fundamental property of magnetic fields in association with magnetic reconnection: for reconnection that occurs on scales comparable to or larger than the characteristic separation of the magnetic poles (i.e., excluding the reconnection associated with small-scale footpoint motion resulting in what is generally described as field-line braiding), there are motions of pairs of field lines towards and later away from the reconnection site. In the simple simulations shown in Movie I on the CD-ROM, vacuum reconnection occurs through null points as field lines move through separators (the intersections of separatrix surfaces) whenever two pairs of field-line segments exchange connectivity at the reconnection location. The simulations suggest that most of the time field lines move through the coronal volume in response to source motions with speeds comparable in magnitude to that of the footpoints themselves. Just prior to reconnection, however, field lines approach the separator and slide past it often with a substantially increased speed. That speed decreases again after reconnection as the (new) field lines move away from the separatrix surface in their new domain of source connectivity. The potential-field simulations of the quiet-sun corona (i.e., in a mixed-polarity region) suggest that the velocities just prior to and just after reconnection could easily be an order of magnitude larger than the source speeds (to be confirmed by resistive-MHD simulations). In an active region, the velocities are generally much smaller because of the many surrounding sources of like polarity (as in the last segment of Movie I), but, in favorable conditions, substantial velocities can be expected there too."
The simulation was introduced in the first paragraph and described in the second. Now, in the third paragraph, the authors discuss the implications and ramifications of the study. Notice again in this paragraph that the authors are explicit about the reconnection of magnetic field lines specifically. References to the corona are not associated with the simulation, but rather with the discussion of its implications. In the case, for instance, of magnetic reconnection in the solar corona, one would expect the field lines to move with a speed & pattern similar to that revealed by the vacuum reconnection study. In particular, see the remark, "The simulations suggest that most of the time field lines move through the coronal volume in response to source motions with speeds comparable in magnitude to that of the footpoints themselves." Here the specific reference is to the coronal volume, not to the corona itself, and the difference is important. Later on there are specific references to simulations of the quiet corona, but those are of course independent from the vacuum study done here.
My conclusion is simple enough. Mozina does not know how to read a science paper. There certainly is a great deal of evidence already in hand that he cannot read or understand the equations found in plasma physics & electromagnetism. This is evidence that he cannot read the English either. Remember, technical & scientific research papers are not directed towards a general readership. Rather, they are the means by which professionals communicate with other professionals; sometimes in the form of a general review intended to inform non-specialists, sometimes in detailed studies intended for specialists (the Priest & Schrijver paper is one of the general review type). Aside from a liberal dose of usually unspectacular mathematics (meaning it's pretty basic stuff even if it looks extreme to outsiders), there is also a fairly dense & precise language (exclusively English now in all of the "major" journals). In order to follow the papers one must be able to read both the mathematics and the English, and both occur in the form of jargon, language as precise as possible to cut down on confusion (for the intended readership, not for the outsider or neophyte).
I see nothing confusing about the language here, and I don't fancy supplementing my math & science lessons to Mozina with English-101 to boot. What we see is Mozina "cherry picking" his favorite disembodied words and trying to rationalize an irrational interpretation of a paper that he otherwise cannot read. No language works that way. No language allows you to pick out key words, without context, and know thereby, everything you need to know. And "context' does not mean the two or three words nearby. It means the whole sentence, the whole paragraph, or more (what does this sentence mean: "Flying planes can be dangerous.").
The truth is that Priest & Schrijver are explicit and clear about two major points: (1) The reconnection is being done by magnetic field lines and not by field aligned currents, and (2) the reconnection of magnetic field lines does happen in a vacuum. Mozina has been reduced to clutching desperate linguistic straws to avoid these conclusions and so has found a way to rationalize and pretend that the authors are actually saying things they are not saying. Really, he is trying to do the same thing to Priest & Schrijver that he has already done to Dungey.
To this Mozina responded ...
It's the same desperate clutching at the same desperate straws. Dungey said "lines of force", but we can trust Mozina that Dungey didn't really mean it.
Well, you sure have a funny way of showing it. You insist that Dungey can't tell the difference between a "line of force" and an electrical current; you insist that Priest & Schrijver really mean "plasma" when they say "vacuum", and you insist that all of the experimenters (e.g., Gekelman, Lawrence, Yamada, Ji & etc.; Comments on magnetic reconnection, 13 Feb 2009; Comments on magnetic reconnection III, 9 Mar 2010) cannot understand their own experiments, foolishly assigning the reconnection to magnetic field lines instead of filed aligned currents. Priest & Forbes are explicit with hundreds of pages of detailed description of the topological reconnection of magnetic field lines (Magnetic Reconnection: MHD Theory and Applications, Eric Priest & Terry Forbes; Cambridge University Press, 2000). Likewise, Paul Bellan spends a whole chapter on the reconnection of magnetic field lines (not field aligned currents; Fundamentals of Plasma Physics, Paul M. Bellan; Cambridge University Press, 2006). And many more. But you insist that all of them, each, and every one of them, is dead wrong. You do in fact explicitly insist that you know more about plasma physics and electromagnetism than they do, and your insistence is laced with accusations of deceit & fraud against anyone who dares to agree with them.
So, when you say, "I don't know more than they do", how is anyone supposed to believe you say that with a straight face? Why would anyone believe this is a truthful self-portrait, when you fall all over yourself insisting to the contrary, every single day?
If you really believe that Dungey knows more than you do, about plasma physics, then why don't you believe Dungey when he says that lines of force reconnect?
To this Mozina responds in post 6111 by selecting out a few key words of his own to rationalize his selective interpretation of the paper. Herein I will refute Mozina's sloppy attempt to refute me.
The following are the three paragraphs that make up the full test of section 5 ("Toy Model for Vacuum Reconnection"), pages 17-19 in the paper Aspects of Three-Dimensional Magnetic Reconnection; E.R. Priest & C.J. Schrijver; Solar Physics 190(1/2): 1-24, December 1999. I reproduce the test only, but the paper (PDF) including the referenced figures, as well as the CD-ROM contents (99.2 MBytes zip archive) can be accessed from the paper's webpage at Solar Physics ( http://www.springerlink.com/content/l702082772n234t2/fulltext.html ). All emphasis (e.g., italics) is found in the original, except the bold face paragraph title, which is mine.
Paragraph 1
"We have constructed a toy model for vacuum reconnection driven by the motion of photospheric sources and have presented the results in the accompanying CD-ROM. We calculate the potential magnetic field due to two, three or four sources in the solar surface and then extend it to a many-source case in which the surrounding fields generally limit the motions of the field lines in response to the footpoint motions to much smaller amplitudes than in the few-source case. The sources are slowly moved around and we assume that the field remains potential. Although this is an oversimplified model, the resulting motion of the field lines is instructive and it is a useful preliminary for the resistive MHD numerical model that we are planning to undertake."
This is the paragraph that sets the stage, so to speak. See the very first sentence: "We have constructed a toy model for vacuum reconnection driven by the motion of photospheric sources ..." This should be clear enough for anybody, but evidently not Mozina. What is there to say but this: vacuum reconnection is reconnection that takes place, strangely enough, in a vacuum. Indeed, look at the title for the section, "Toy Model for Vacuum Reconnection". Could the authors have been more clear? Yet, Mozina continues to stubbornly foist upon us the fairy tale that this is all MHD, all really currents reconnecting in a plasma, despite explicit language from the authors to the contrary. And pay attention to the part about "driven by the motion of photospheric sources". That does not mean that the photosphere is at all involved in this process, it means that the motions of the sources that drive the vacuum reconnection are chosen to match the observed motions of photospheric sources. This is no great surprise, since the eventual goal is to study magnetic reconnection in the solar corona. This is all reinforced by the comment about footpoint motions; same thing, the motions of the sources match the motions observed for real solar footpoints. Nowhere can we find any evidence, any language, any indication at all that the magnetic reconnection takes place anywhere except a vacuum, as explicitly indicated in the text.
The only mention of MHD is a plan to create a resistive-MHD model in the future. This is not an unimportant point. As is well known, all forms of magnetic field line reconnection in a plasma are possible only in the realm of resistive MHD. Magnetic field line reconnection in a plasma is not physically possible in the realm of ideal MHD. If the authors are already using MHD, then it must be only resistive MHD, but then why would they say they have not done that yet and plan to do so in the future? This only serves to reinforce the obvious point: in this study the magnetic field line reconnection all happens in a vacuum, just like the authors said it did.
Magnetic field line reconnection in a vacuum is easy, just solve Maxwell's equations, no plasma complications required. But it is also boring because it does not do anything remotely interesting, except perhaps allow cute animations. However, magnetic field line reconnection in a plasma can get really exciting. So what the authors have done here is model magnetic field line reconnection in a vacuum (which is what they said they were doing, and I assume the authors actually do know what they did), as a preliminary exercise, just to see how the field lines behave, as a benchmark for later, resistive MHD studies of magnetic field line reconnection in a plasma. In the absence of seriously complicating issues, the reconnection of magnetic field lines in a plasma should look similar to reconnection in a vacuum
Paragraph 2
"First of all, we consider a simple model of binary reconnection due to the motion of two sources (Figure 14(a)). The right-hand source is the larger and it performs an orbit around the other source, during which we keep the directions constant of most of the field lines from the larger source. The way in which the field lines reconnect by changing from being open to closed and back to open can be seen clearly. (Of course, if the field lines are potential, we cannot prescribe both footpoints of a field line as the sources move around, so the choice of which field line directions at the source to keep fixed is entirely arbitrary.) Then we added a third (Figure 14(b)) and a fourth (Figure 14(c)) source and as the sources move slowly around, a rapid counter-flipping of the field lines can be seen due to fan reconnection or separator reconnection. The flipping occurs as they reconnect and move close to the separatrix surface."
Having set the stage in the first paragraph, here we find the description of what is really happening. Notice the comments, "The way in which the field lines reconnect by changing from being open to closed and back to open can be seen clearly"; "a rapid counter-flipping of the field lines"; "The flipping occurs as they reconnect and move close to the separatrix surface." In all cases field lines do the reconnecting. Not "field aligned currents", just "field lines". Now I think it is safe to assume that Priest & Schrijver both know what a field line is, what a field aligned current is, and how to tell the difference between them, especially in their own simulation. Furthermore, as already established above, we have magnetic field lines reconnecting in a vacuum.
Paragraph 3
"These simple experiments demonstrate a fundamental property of magnetic fields in association with magnetic reconnection: for reconnection that occurs on scales comparable to or larger than the characteristic separation of the magnetic poles (i.e., excluding the reconnection associated with small-scale footpoint motion resulting in what is generally described as field-line braiding), there are motions of pairs of field lines towards and later away from the reconnection site. In the simple simulations shown in Movie I on the CD-ROM, vacuum reconnection occurs through null points as field lines move through separators (the intersections of separatrix surfaces) whenever two pairs of field-line segments exchange connectivity at the reconnection location. The simulations suggest that most of the time field lines move through the coronal volume in response to source motions with speeds comparable in magnitude to that of the footpoints themselves. Just prior to reconnection, however, field lines approach the separator and slide past it often with a substantially increased speed. That speed decreases again after reconnection as the (new) field lines move away from the separatrix surface in their new domain of source connectivity. The potential-field simulations of the quiet-sun corona (i.e., in a mixed-polarity region) suggest that the velocities just prior to and just after reconnection could easily be an order of magnitude larger than the source speeds (to be confirmed by resistive-MHD simulations). In an active region, the velocities are generally much smaller because of the many surrounding sources of like polarity (as in the last segment of Movie I), but, in favorable conditions, substantial velocities can be expected there too."
The simulation was introduced in the first paragraph and described in the second. Now, in the third paragraph, the authors discuss the implications and ramifications of the study. Notice again in this paragraph that the authors are explicit about the reconnection of magnetic field lines specifically. References to the corona are not associated with the simulation, but rather with the discussion of its implications. In the case, for instance, of magnetic reconnection in the solar corona, one would expect the field lines to move with a speed & pattern similar to that revealed by the vacuum reconnection study. In particular, see the remark, "The simulations suggest that most of the time field lines move through the coronal volume in response to source motions with speeds comparable in magnitude to that of the footpoints themselves." Here the specific reference is to the coronal volume, not to the corona itself, and the difference is important. Later on there are specific references to simulations of the quiet corona, but those are of course independent from the vacuum study done here.
My conclusion is simple enough. Mozina does not know how to read a science paper. There certainly is a great deal of evidence already in hand that he cannot read or understand the equations found in plasma physics & electromagnetism. This is evidence that he cannot read the English either. Remember, technical & scientific research papers are not directed towards a general readership. Rather, they are the means by which professionals communicate with other professionals; sometimes in the form of a general review intended to inform non-specialists, sometimes in detailed studies intended for specialists (the Priest & Schrijver paper is one of the general review type). Aside from a liberal dose of usually unspectacular mathematics (meaning it's pretty basic stuff even if it looks extreme to outsiders), there is also a fairly dense & precise language (exclusively English now in all of the "major" journals). In order to follow the papers one must be able to read both the mathematics and the English, and both occur in the form of jargon, language as precise as possible to cut down on confusion (for the intended readership, not for the outsider or neophyte).
I see nothing confusing about the language here, and I don't fancy supplementing my math & science lessons to Mozina with English-101 to boot. What we see is Mozina "cherry picking" his favorite disembodied words and trying to rationalize an irrational interpretation of a paper that he otherwise cannot read. No language works that way. No language allows you to pick out key words, without context, and know thereby, everything you need to know. And "context' does not mean the two or three words nearby. It means the whole sentence, the whole paragraph, or more (what does this sentence mean: "Flying planes can be dangerous.").
The truth is that Priest & Schrijver are explicit and clear about two major points: (1) The reconnection is being done by magnetic field lines and not by field aligned currents, and (2) the reconnection of magnetic field lines does happen in a vacuum. Mozina has been reduced to clutching desperate linguistic straws to avoid these conclusions and so has found a way to rationalize and pretend that the authors are actually saying things they are not saying. Really, he is trying to do the same thing to Priest & Schrijver that he has already done to Dungey.
Get over it, and admit already that electrical discharges occur in plasmas and flares and Dungey claimed! You can't use only 1/2 his work and ignore the other half *ENTIRELY*.
Does your admonition to others not apply equally to yourself?
You work hard to make hay out of the fact that it was Dungey who used the words "electric discharge".
Does your admonition to others not apply equally to you? You are adamant that Dungey meant "electrical discharge" when he said "electrical discharge". So why do you refuse to believe that when Dungey said "The effect of the discharge is to 'reconnect' the lines of force at the neutral point, and this happens quickly." that he also meant what he said in this case as well?
To this Mozina responded ...
It's the same desperate clutching at the same desperate straws. Dungey said "lines of force", but we can trust Mozina that Dungey didn't really mean it.
Well, you sure have a funny way of showing it. You insist that Dungey can't tell the difference between a "line of force" and an electrical current; you insist that Priest & Schrijver really mean "plasma" when they say "vacuum", and you insist that all of the experimenters (e.g., Gekelman, Lawrence, Yamada, Ji & etc.; Comments on magnetic reconnection, 13 Feb 2009; Comments on magnetic reconnection III, 9 Mar 2010) cannot understand their own experiments, foolishly assigning the reconnection to magnetic field lines instead of filed aligned currents. Priest & Forbes are explicit with hundreds of pages of detailed description of the topological reconnection of magnetic field lines (Magnetic Reconnection: MHD Theory and Applications, Eric Priest & Terry Forbes; Cambridge University Press, 2000). Likewise, Paul Bellan spends a whole chapter on the reconnection of magnetic field lines (not field aligned currents; Fundamentals of Plasma Physics, Paul M. Bellan; Cambridge University Press, 2006). And many more. But you insist that all of them, each, and every one of them, is dead wrong. You do in fact explicitly insist that you know more about plasma physics and electromagnetism than they do, and your insistence is laced with accusations of deceit & fraud against anyone who dares to agree with them.
So, when you say, "I don't know more than they do", how is anyone supposed to believe you say that with a straight face? Why would anyone believe this is a truthful self-portrait, when you fall all over yourself insisting to the contrary, every single day?
If you really believe that Dungey knows more than you do, about plasma physics, then why don't you believe Dungey when he says that lines of force reconnect?
.
!
