Re: Does the Electromagnetic field have a Gravitational field?

highborn_at_gmail.com
Date: 01/06/05 

Date: Thu, 6 Jan 2005 22:11:12 +0000 (UTC)

antimatter33@yahoo.com wrote:
> whopkins@csd.uwm.edu wrote:
> > The electromagnetic field is scale-invariant, as are Maxwell's
> > equations. So it can't provide any non-zero contribution to the
Weyl
> > tensor.
>
> This is only half right - EM is conformally invariant when there is
no
> matter present. As Einstein showed in reference to Weyl's theory, an
> electron in a conformally invariant 4-world would have a mass that
> depended on its spacetime history.
>
> -drl

I understand and agree with whopkins first sentence, but the second
seems a non sequitor. I agree with your first sentence, the scale
invariance is broken by the presence of mass. I also agree with your
second sentence, but I am not sure of its relevance. In my original
reply to Whopkins I was alluding to Weyl's theorem; where in a scaling
of the metric leaves the components (one up, three down in MTW
convention) of Weyl's conformal tensor invariant. I wasn't refering to
Weyl's unified theory; where in a vector changes both length and
direction when it is carried parallel to itself around a closed loop.
Rob Woodside