Re: "Faraday's Disk" which started it all

["JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE, IL 60439" <JLU@HEP.ANL.GOV>]

Hi Bill Beatty-
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> 1) In F = qVxB, V is the velocity of the particle whose charge is q;  B is
> the magnetic field (of some source) measured at the location of q; F is the
> force which q experiences due to its interaction with the field B.  All of
> these four quantities are measured by an observer in a given inertial frame.
> In particular, V is simply the velocity of the charged particle in this
> frame.  (Note that the kinematical status of the source of B is not
> explicitly relevant - the local [at q] value of its field B says everything
> about its magnetic force on q - this is the essential usefulness of a field
> theory - indeed B may be the net field of numerous sources.)


I understand.  The concept of "field" requires inertial frames.
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        Nonsense.  A "field" is a force divided by a charge.  Charge
is a relativistic invariant, so a "field" transforms like a force.


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Is the following statement true? :  The concepts within Special Relativity
and EM fields cannot be applied to the case of a test-charge suspended
near a rotating permanent magnet in the shape of a disk.

If SR cannot make predictions about the e-field surrounding a rotating
disk-magnet, then...
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        The statement is false.  Special relativity has no problems with
any ordinary observable phenomena.  GR only comes into  play when gravitation
enters the picture.
        If you find a problem with special relativity, the problem should
be your understanding of SR, not SR.  I give this to you as a general rule.

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  1. Is there ANY way to predict how a single test-charge will behave near
     a rotating disk-magnet?
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        Yes.
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  2. Experimentally, how do charged particles actually behave near
     a rotating disk-magnet?
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        Do the experiment and find out, or do a literature search and see if
the question hasn't already been answered.

*


        "I scored the next great triumph for science myself,
to wit, how the milk gets into the cow.  Both of us
had marveled over that mystery a long time.  We had
followed the cows around for years - that is, in the
daytime - but had never caught them drinking fluid of
that color."
                Mark Twain, Extract from Eve's
                Autobiography