Magnetic Reconnection Redux III
So, once again we cover old ground:
Magnetic Reconnection. Been there, done that, but lets do it again. Magnetic reconnection is a fundamental physical process that is extremely well developed and described both in theory & practice. Anyone who actually wants to learn about it need not look too far. I suggest the book
Magnetic Reconnection: MHD Theory and Applications by Eric Priest & Terry Forbes, Cambridge University Press, 2000. Any textbook on
magnetohydrodynamics and most textbooks on
plasma physics will cover the topic, but this one will do. There are also numerous laboratory experiments studying the phenomenology of magnetic reconnection in detail, such as the
Magnetic Reconnection Experiment in the Princeton Plasma Physics Laboratory at Princeton University. One might as well deny the validity of physics altogether as to deny the validity of magnetic reconnection, they are quite the same thing to do.
... I don't "dismiss" anything. ... I don't see how you (or anyone else) can determine in any of these "experiments" if the magnetic fields are themselves doing anything, ...
But you
do dismiss the experiments without any consideration and I simply don't believe you when you say otherwise. Look, you even put the word "experiment" in quotes because you don't even accept that they are experiments at all. You think maybe the folks over at the Princeton Plasma Physics Laboratory don't even know how to do an experiment? The simple truth is constantly obvious. You cannot & will not consider anything that contradicts your preconception, despite the fact that you actually know nothing at all about the topic at hand. You are simply intolerant to anything that contradicts your preconceptions. The second sentence makes that plain. You "don't see how", and yet you don't even know what is being measured.
... I don't see how you (or anyone else) can determine in any of these "experiments" if the magnetic fields are themselves doing anything, ...
How can you say that seriously when you don't even know what the experiments are or how they are done or what is measured?
Birn's paper on MR theory (discussed on space.com) convinced me that the math related to the theory was fine, the approach is "ok" from the standpoint of physical descriptions, ...
I don't do space.com, so which of Birn's many papers on magnetic reconnection are you talking about?
... but there is no way to physically determine if the this is a "unique" form of energy exchange. How is it physically different (at the point of energy release) than say "circuit reconnection" or "particle reconnection", or induction or an ordinary discharge process in plasma? ... How exactly would that be a unique energy release process and not "induction"?
I have no idea what "particle reconnection" is supposed to be, so I will skip it until & unless you want to tell us what it is. "Circuit reconnection", if it's what I think you mean (i.e, merging electric currents), is simply impossible because it violates the law of conservation of energy. If two currents merge and the total energy after the merger is greater than the total energy before the merger, then where did the energy come from? As for induction, that too is out of the question because that is a transfer of energy from the current to an induced magnetic field, whereas magnetic reconnection is a transfer of energy from the magnetic field to the plasma. Neither does magnetic dissipation work, because the time scale is too large. It would take magnetic dissipation about 1,000,000 years to accelerate a plasma over a typical solar distance scale of about 100,000 km, but magnetic reconnection is impulsive and will do the very same job in about 1 minute.
In the laboratory experiments we can see this happen right in front of us. Magnetic field changes first, followed by plasma acceleration. The magnetic field reconfigures spontaneously to a lower energy state, as one would expect of any physical system, and the energy is transferred to the plasma. If it were currents dong the work, the order of events would be reversed. Furthermore, magnetic reconnection will accelerate a plasma, which means it will accelerate both charge signs in the same direction, while any normal electric field or induction process will accelerate opposite charges in opposite directions.
I'm not blaming Tim for claiming that *ONLY* MR can release energy in plasma, I'm blaming him for choosing something that *DOES NOT* occur in nature under natural circumstances when *NATURAL* explanations can and do release these forms of energy in plasma.
Magnetic reconnection is a natural explanation that occurs in nature. It is observed in Earth's magnetosphere on a regular basis.
A coronal loop is not a "frozen" magnetic line, but rather it is a moving column of flowing plasma full of kinetic energy, much like any discharge in the Earth's atmosphere. The magnetic fields are not there all by themselves doing all the work by themselves, and they are not driving the parade. The magnetic fields exist *BECAUSE OF* the current flow inside the loop and they are generated by the current flow inside that loop that is heating the plasma inside the loop.
As already pointed out by the redoubtable
tusenfem, this is extremely impossible and violates just about every law of electromagnetism you can come up with. The magnetic field of the loop cannot be generated by the current in the loop, and need not be generated by any current at all, for appropriate definitions of "current". It is not at all necessary to have a classical current, as in a stream or flow of particles all of the same sign electric charge, to get a magnetic field. The motions of a charge neutral plasma will efficiently generate magnetic fields. Furthermore, if the plasma is dense enough, the magnetic field once generated will not simply fade away & dissipate, but will remain "frozen" into the plasma.
Let me recap:
1) Magnetic reconnection is a valid and well accepted physical process, well described in theory, and well observed in controlled laboratory experiments. It's validity is beyond question.
2) The magnetic field of a coronal loop cannot possibly be generated by the current(s) flowing in the loop.