Magnetic Reconnection In Vacuo V
Mozina asked for a "peer reviewed" publication to support the claim that magnetic reconnection takes place in a vacuum. In response, on 1 December 2011 at 2:58 PM (in whatever timezone the JREF clock ticks), I posted the following ...
Do a search on books.google.com on "vacuum reconnection" and you will find a paper by Priest, a paper by Priest and Schrijver (here section 5 even has software to do your own vacuum reconnection) and there is a paper by Pritchett, where he specifically lets the density go to zero in his modelling. I think that were the first three links (did this yesterday evening) and there I stopped.
The simple fact that Somov's currents are just two wires carrying an electric current (otherwise you cannot maintain a vacuum) seems to be lost on MM.
And no, vacuum reconnection does not mean that the vacuum itself is reconnecting!
Is there a PARTICULAR ONE that tickles your fancy that I can take a look at?
Yes, this paper:
Aspects of Three-Dimensional Magnetic Reconnection - (Invited Review); Priest & Schrijver, Solar Physics 190(1/2): 1-24, December 1999.
Abstract:
In this review paper we discuss several aspects of magnetic reconnection theory, focusing on the field-line motions that are associated with reconnection. A new exact solution of the nonlinear MHD equations for reconnective annihilation is presented which represents a two-fold generalization of the previous solutions. Magnetic reconnection at null points by several mechanisms is summarized, including spine reconnection, fan reconnection and separator reconnection, where it is pointed out that two common features of separator reconnection are the rapid flipping of magnetic field lines and the collapse of the separator to a current sheet. In addition, a formula for the rate of reconnection between two flux tubes is derived. The magnetic field of the corona is highly complex, since the magnetic carpet consists of a multitude of sources in the photosphere. Progress in understanding this complexity may, however, be made by constructing the skeleton of the field and developing a theory for the local and global bifurcations between the different topologies. The eruption of flux from the Sun may even sometimes be due to a change of topology caused by emerging flux break-out. A CD-ROM attached to this paper presents the results of a toy model of vacuum reconnection, which suggests that rapid flipping of field lines in fan and separator reconnection is an essential ingredient also in real non-vacuum conditions. In addition, it gives an example of binary reconnection between a pair of unbalanced sources as they move around, which may contribute significantly to coronal heating. Finally, we present examples in TRACE movies of geometrical changes of the coronal magnetic field that are a likely result of large-scale magnetic reconnection.
You can download the PDF from the
Solar Physics website without logging in (it worked for me). See section 5, "Toy Model for Vacuum Reconnection" (pages 17-19).
Also recall the abstract already referenced by
Reality Check:
Magnetic reconnection on the sun by E.R. Priest, from the book "Basic Plasma Processes on the Sun", Kluwer 1990, pages 271-288 (abstract truncated on ADS webpage - see paper for full abstract). Here we find the beginning of the 2nd paragraph of the introduction:
In a vacuum, reconnection is a trivial process, but, in a plasma atmosphere such as the Sun's, normally the plasma is attached very effectively to the magnetic field. It is only where the magnetic gradients are, say, a million times stronger than normal that the magnetic field can slip through the plasma and reconnect (Figure 1). There are three important effects of such a process. Firstly, the global topology of the magnetic field may be changed since the connectivity of the field lines may be altered. For example, initially in Figure 1 the point A is joined to point B and finally it is connected to point C. This may affect heat and the flow of particles which tend to travel along field lines. Secondly, inflowing stored magnetic energy is converted into heat, bulk kinetic energy and fast particle energy. Thirdly, reconnection creates large electric currents, electric fields, shock waves, filamentation, each of which may be involved in the acceleration of charged particles."
In light of Priest's hilighted comment, remember my own comments in October:
See my post
Magnetic Reconnection In Vacuo where I outline the clear evidence that magnetic field lines, and not field aligned currents, topologically reconnect to change the energy state of the Magnetic field. To reinforce my demonstration, I now also suggest
Magnets in Motion, where you can access animated gif images of the magnetic field lines reconnecting as magnets move. The magnetic fields are derived from solutions of Maxwell's equations. The author of the page,
Rick Hoadley, has a Master's Degree in Electrical Engineering from
Cornell University, so it is fair to assert that he is an authority on electricity and magnetism.
There is no arguing with the physics, that this definitely represents the breaking & reconnecting of magnetic field lines, no current of any kind involved.
This is not found in textbooks & published papers for the simple reason that is is both obvious & trivial. Contrary to the ill-informed opinion of some, it is actually not true that literally
everything is found within the covers of a book or on the pages of a scholarly paper. These are the same people who think that every question has an answer in the "solutions manual", if you can find it; thinking not required, just look it all up. It is just one more example of appeal too authority rather than an independent examination of the actual physics involved.
There simply is no justification for the claim that the reconnection of magnetic field lines cannot happen in a vacuum.
That certainly satisfies the request. At this time I will add a second exhibit from the relevant literature to support the reality of magnetic reconnection in a vacuum. In this case my source is the textbook
Fundamentals of Plasma Physics by Paul M. Bellan; Cambridge University Press, 2006. Chapter 12 is entitled "Magnetic reconnection"; see section 12.7, "Assignments", page 432, problem number 1. Emphasis is in the original.
Bellan said:
Sweet-Parker type reconnection (Sweet 1958, Parker 1957, Trintchouk, Yamada, Ji, Kulsrud and Carter 2003). Consider the two identical flux conserving current loops shown in Fig. 12.6(a). Because the system is axisymmetric, the magnetic field can be expressed as
[latex]
[/latex]
where psi is the poloidal flux.
{ ... }
(b) Define private flux to be a poloidal flux surface that links only one of the current loops (examples are the flux surfaces labeled 1 and 2 in Fig. 12.6(a)). Define public flux to be a flux surface that links both current loops (examples are flux surfaces 3, 4, 5 in Fig. 12.6(a)). Define the X-point to be the location in the z=0 plane where there is a field null as shown in Fig. 12.6(a); let r0 be the radius of the X-point. Show by sketching that as the two current loops approach each other in vacuum, a private flux surface above the midplane will merge with a private flux surface below to form a public flux surface.
This is literally a textbook exercise for the student in vacuum magnetic reconnection. It is in essence a textbook version of the very same X-point reconnection found in
Clinger's proof that
Mozina has so loudly (but so wrongly) condemned. I realize it is hard to follow without seeing figure 12.6(a), but that really is not the point (go find the book if you like, and as they say in popular English, "knock yourself out").
The real point is this: We have now at our disposal the original and valid proof from
Clinger, a peer-reviewed review paper from Priest & Schrijver, and a textbook exercise for the student, all of which assert the validity of the reconnection of magnetic field lines of force in a vacuum. Lest anyone be tempted to take these efforts too lightly, I would like to point out who we are dealing with here.
W.D. Clinger is an Associate Professor in the College of Computer and Information Science at Northeastern University; his PhD (in computer science I presume) was earned at M.I.T.
Carolus "Karel" Schrijver earned his PhD from the University of Utrecht, Netherlands in 1986 (thesis title "Stellar Magnetic Activity: Complementing Conclusions based on Solar and Stellar Observations"). He is currently the Principal Investigator for the
Atmospheric imaging Assembly (AIA) on the
Solar Dynamics Observatory.
Eric Priest received his PhD from the University of Leeds in 1969 under
T.G. Cowling, thesis title "Magnetohydrodynamic Neutral Point Theory". He was James Gregory Professor of Mathematics at St. Andrews University in Scotland, but retired in 2010 and is now Professor Emeritus. He was made a Fellow of the Royal Society and received the Hale Prize from the American Astronomical Society in 2002; received the Gold Medal of the Royal Astronomical Society and the Payne-Gaposchkin Medal & Prize of the Institute of Physics in 2009. And note that in my comments above I recommend animations of vacuum magnetic reconnection that are made by
Rick Hoadley, who has a Master's Degree in Electrical Engineering from
Cornell University. Finally, for what it's worth, I have B.S. & M.S. degrees in physics from California State University at Los Angeles and am retired from a 28 year career in astronomy & astrophysics. The list of qualifications should not be construed as an assertion that none of these people are capable of being wrong; I have yet to meet the infallible mortal. However, it should be construed as an assertion that everyone in the list has, shall we say, "been around the block" once or twice in the science & technology fields. I think it fair to assert that they are, collectively & individually unlikely to make serious mistakes when it comes to serious efforts involving the basic fundamentals of their respective fields of specialty, or in fields they make a serious effort to study.
As for
Mozina ...
Discussing a poster's credentials is usually off-topic, but Michael Mozina is arguing from his own personal authority. Because Michael Mozina has chosen to cite his credentials as evidence for his personal authority, and because that alleged authority is the foundation of his argument, we cannot discuss his argument without examining his credentials.
See the entire post for the full discussion.
Now, in response to my original post quoted above, an interesting conversation ensues which it is worth reviewing here. All of the highlighting has been added by me.
The way in which the field lines reconnect by changing from being open to closed and back to open can be seen clearly.
Um, it would appear (without having reviewed the actual software and code yet) that in the "toy model" that they are talking about, the "way it works" is by breaking the laws of physics.
There are no "open" magnetic lines. They may close at infinity, but they always form closed loops.
So once more you show your ignorance of mainstream plasmaphysical terminology. Well, who is surprised?
After reading soooooooooooooooo many books and papers you still do not know about the terminology of open and closed field lines?
Apparently, you have not read as much or as well as you claim.
I give up for now. Without seeing the Movie and without reviewing the code that appears to violate the laws of physics, I really have no idea how their "magic" works. All I can see so far is that they are INTENT on claiming that B field lines SWITCH from being closed, to "open". AFAIK, that's bogus nonsense. Unless they have a monopole up their sleeve, or some "magic monopole code" in that "toy" software, it's never going to happen. All magnetic lines form as closed directional loops.
So once more you show your ignorance of mainstream plasmaphysical terminology. Well, who is surprised?
After reading soooooooooooooooo many books and papers you still do not know about the terminology of open and closed field lines?
Apparently, you have not read as much or as well as you claim.
Oh, I know the terminology well enough. Apparently I don't believe the claim, nor do I believe everything I read.
Oh, I know the terminology well enough. Apparently I don't believe the claim, nor do I believe everything I read.
Apparently you
don't know it, othewise you would not have made the silly comment.
Just for the general public, closed field lines are lines that (in this case) start at the Sun and return to the Sun. Open field lines are lines that start at the Sun but do not return. This does not mean that the end of open field lines is just flapping somewhere in the solar wind, but it will be connected somewhere far away to some other magnetic object.
Apparently you don't know it, othewise you would not have made the silly comment.
Just for the general public, closed field lines are lines that (in this case) start at the Sun and return to the Sun. Open field lines are lines that start at the Sun but do not return. This does not mean that the end of open field lines is just flapping somewhere in the solar wind, but it will be connected somewhere far away to some other magnetic object.
IMO its silly to be talking about B LINES being open.
It's just more "confusion factor" IMO.
IMO its silly to be talking about B LINES being open. It's just more "confusion factor" IMO.
Yes, and it is also strange to give electron holes negative mass in semi conductors and still it's done.
It is strange to say the electron has spin, when it is not rotating.
And so one can go on. Sometimes professional jargon is strange to the uninitiated.
Nobody is confused about the open/closed usage, when it is explained how it is used and why. But you are the exception to the rule, now does that not make you feel special?
Yes, and it is also strange to give electron holes negative mass in semi conductors and still it's done.
It is strange to say the electron has spin, when it is not rotating.
And so one can go on. Sometimes professional jargon is strange to the uninitiated.
Nobody is confused about the open/closed usage, when it is explained how it is used and why. But you are the exception to the rule, now does that not make you feel special?
I'm not personally confused. It's an unnecessarily confusing term that is mostly related to the mainstream's aversion to any sort of CIRCUIT/CURRENT flow orientation to events in space. You dumb everything down to the B orientation even though it's the electric horse that does all the actual work, including "opening" those lines of (PLASMA) force.
At the beginning of this conversation,
Mozina assumes that Priest & Schrijver are allowing magnetic field lines to simply "flap in the breeze" (the "open" lines), correctly pointing out that this violates the laws of physics. When chastised by
Tusenfem for his misunderstanding, he insists that he "knows the terminology quite well" and ends up by saying that he is "not personally confused". This does raise the obvious question. If he knows the terminology so well, and if he is not personally confused, then why did he make that mistake in the first place? This is just one small example in a sea of opportunities that the unwary have available too them for misunderstanding of technical writing. Remember, specialist journal research papers (the Priest & Schrijver paper appeared in
Solar Physics are not written for general readers; they are written by specialists with the intention of communicating with other specialists, and are commonly packed with technical jargon, and common words used in the fashion of jargon peculiar to that specialty. So when
Mozina complains that the use of "open lines" is just a "confusion factor", what's the real point? It's not at all confusing to the intended audience, all of whom know exactly & at once what the words "open lines" mean. Anyone who cannot follow the jargon has no business making assertions about the meaning of the papers. This certainly includes
Mozina but it also includes well educated scientists from some unrelated discipline; there is no reason to assume that someone with a PhD in pure mathematics, for instance, will immediately understand all of the jargon in a plasma physics paper, without making an effort to learn that jargon.
Later,
Mozina posts evidence that he has actually read the paper.
You're right Tim, I could download the paper for free. Unfortunately, only the CD must contain the "toy reconnection" code that they are talking about. It's also extremely difficult to know exactly what they mean by the term "vacuum", or a "Toy Model" for that matter. The "toy model" in the paper includes nothing more than a couple of diagrams.
5. Toy Model for Vacuum Reconnection
We have constructed a simple toy model for vacuum reconnection driven by the motion of photospheric sources and have presented the results in the accompanying CD-ROM.
As far as I can tell, they are still talking about PLASMA physics, in this case a LOW DENSITY plasma like the corona.
I guess I need to see the code and the CD.
Although previously "not personally confused" by the jargon (although this appears to be a self-serving falsehood given the conversation reproduced above), now
Mozina admits to being confused by what seems to me fairly ordinary English.
Priest & Schrijver said:
We have constructed a simple 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 limit the motion 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 a resistive MHD numerical model that we are planning to undertake.
I don't see why
Mozina cannot figure this out. The reconnection in a vacuum is
driven by the motions of photospheric sources, meaning that the motions of the sources for the vacuum magnetic reconnection are the same as one sees for photospheric sources. It seems obvious enough to me.
Got a copy of his computer code by any chance? That's likely to be the EASIEST way to falsify the concept.
The computer code no, but the CD yes. One can download a 99.2 MByte zip archive that expands into a 105 MByte folder (on my Mac) from the solar physics webpage for the paper:
http://www.springerlink.com/content/l702082772n234t2/fulltext.html (which does not show the full text). Select the "Electronic Supplementary Material" link. There are two movies in the folder "epriest"; "movingloops.mov" is a movie of real solar coronal loops, while "potentialfields.mov" is the vacuum reconnection movie.
Clinger's is far better looking, but the moving sources in the Priest & Schrijver movie makes it computationally more complicated.
The Bottom Line:
The bottom line at the moment is that we have a serious collection of serious scientists seriously expounding on the reconnection of the lines of force of magnetic fields
in a vacuum, with no plasma involved. It is not enough to insist they must all be wrong simply because one does not like the idea of magnetic reconnection. Rather, it is necessary to be just as serious in opposition as the proponents are serious. I assert, for the record, that this is a criterion that
Mozina has failed to meet.
Every point MUST AND DOES satisfy Gauss's law of magnetism, but NO POINT is the "beginning" of any line.
!