Re: spinning magnet without general relativity

[John Denker <jsd@MONMOUTH.COM>]

At 12:15 PM -0700 on 6/27/99, William Beaty wrote:
> I thought that GR works in NONinertial frames.

It does indeed, but it is not the *only* thing that works.

> Therefor the spinning disk-magnet can only be attacked via GR.

No, GR is not the *only* way to attack.

> (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.)


At 03:22 PM 6/27/99 -0500, Herb Schulz wrote:
> I believe that E&M Theory and GR don't mix which had been a problem to be
> solved for the better part of this century.

If you look in e.g. _Gravitation_ by Misner, Thorne, and Wheeler, you will
find a fully relativistic formulation of Maxwell's equations.  Can you be
more explicit about the "problem" you are referring to?