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Old 12th February 2012, 11:05 PM   #6156
Tim Thompson
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Lightbulb Plasma Physics: "E orientation" or "B orientation"? III

Originally Posted by Michael Mozina View Post
There is no single "superior" way of viewing events in plasmas.

Actually, yes there is. Furthermore, I have already explained exactly why. And in even further furthermore, you have yourself quoted the explanation, which either went over your head, or was deliberately ignored. Here is the very same passage you quoted, with my emphasis added:

Originally Posted by Parker
It is here that a fundamental misunderstanding has become widely accepted, mistaking the electric current j and the electric current (sic) E (the E, j paradigm) (Parker 1996a) to be the fundamental physical entities. {Editors comment: clearly the second use of "current" for E is a typo where the word "field" is appropriate - TJT} Steady conditions often can be treated using the E, j paradigm, but the dynamics of time-dependent systems becomes difficult, if not impossible, because of the inability to express Newton's equation in terms of E and j in a tractable form. That is to say, E and j are proxies for B and v, but too remote from B and v to handle the momentum equation. So it is not possible to construct a workable set of dynamical field equations in terms of j and E from the equations of Newton and Maxwell. The generalized Ohm's law is often employed, but Ohm's law does not control the large scale dynamics. The tail does not wag the dog. This inadequacy has led to fantasy to complement the limited equations available in the E, j paradigm, attributing the leading dynamical role to an electric field E with unphysical properties. Magnetospheric physics has suffered severely from this misdirection, and we will come back to specific aspects of the misunderstanding at appropriate places in these conversations.

Now, when you put this quote into your post, you chose to highlight the phrase "the tail does not wag the dog". Compare that to the phrases I have highlighted here, which include the words "inability", "not possible" and "unphysical". You chose to ignore them altogether, to your own detriment, because they are the heart of the argument. Nothing you have said in response even deserves to be called marginally relevant, because you choose to ignore the physics on virtually all occasions, this one included.

The letters MHD stand for the word magnetohydrodynamics. The "hydrodynamics" part brings with itself an absolute requirement to include the dynamics of the plasma as a fluid flow. All objects that have a non-zero rest mass are required to adhere to the laws of Newtonian mechanics, or special relativity if the objects are traveling close to the speed of light. Since most space plasmas are non-relativistic, we can under normal circumstances ignore Einstein and satisfy ourselves with Newton. This must be true, and absolutely is always true, even in the presence of electromagnetic fields and the application of Maxwell's equations.

The tail end of your post is an outstanding example of your complete failure to understand the argument and the physics behind it.

Originally Posted by Michael Mozina View Post
I guess Parker is essentially "whining" about the fact the the calculation of gravitational forces is "harder" from a *STRICTLY* E oriented perspective, therefore he intends to use that claim to justify a *STRICTLY* B orientation. Such an extreme position is equally flawed and equally filled with FALSE ASSUMPTIONS.

His claim about the "control" of the large scale dynamics is an EXCELLENT example of one such false assumption. Gravity is *NOT* the "be all end all" of forces as it relates to solar wind, and Magnetism isn't the be all end all either.

Most of what you say here is just plain obviously wrong. To start with, gravity is irrelevant to the argument presented by Parker; it would be exactly the same in the total absence of all gravity, and just as valid, which you would have realized immediately had you understood the physics to the extent which you claim you do. Charged particles accelerated by electromagnetic fields in the complete absence of all gravity still face an absolute requirement to obey the Newtonian laws of motion. The E,j paradigm does not make them "harder" to calculate (with or without quotation marks); Rather, the E,j paradigm makes it impossible to calculate the particle dynamics, just as Parker explicitly said, and you explicitly ignored. This is a fatal flaw in the E,j paradigm, as a consequence of which one must compensate by assuming the existence of electric fields (which in reality do not exist at all) with unphysical properties, meaning properties which are not consistent with the physics of what is really happening, which explains why the "fantasy" fields do not exist in reality, but only in a model of the plasma.

But let's return to gravity. Indeed, it is not the "end all and be all" of anything. However, it is there and it is part of the mix. But in any case, including that of no-gravity, the only correct way to formulate the physics of a plasma is to simultaneously combine Maxwell's equations, required by the presence of electromagnetic fields, and the equations of Newtonian mechanics, usually in the form of the Navier-Stokes equations, because you cannot express mass and mass conservation, momentum, kinetic energy & etc. using Maxwell's equations alone. This is readily done in the B,v paradigm because the velocity is a dynamical variable shared across the board by both Maxwell's equations and the Navier-Stokes equations. This cannot be done at all in the E,j paradigm because there are no dynamical variables common to both Maxwell's equations and the Navier-Stokes equations in that paradigm.

For these reasons I can confidently claim that the E,j paradigm you favor is in fact inferior to the B,v paradigm because the E,j paradigm makes a correct and proper evaluation of the physics of the plasma impossible.
The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell
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