Re: spinning magnet without general relativity

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

Hi all-
        I agree with all of John Denker's remarks except for his caveat:
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> (Perhaps
> the GR goes away if we are close to the rim of a large magnet, so the
> magnet doesn't appear to move if we travel along with it.)

That's more like it.  For a disk spinning at ordinary (nonrelativistic)
speeds, all you need is special relativity in the *instantaneously*
comoving frame at each point, plus (if necessary) a classical treatment of
the obvious centrifugal effects.  (It doesn't need to be a large disk, and
you don't need to be near the rim.)
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        The spinning need not be at non-relativistic speeds.  All this has
"practical" application in astrophysics, where neutron stars do spin with
relativistic speeds.
                                Regards,
                                        Jack

        "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