Re: GR 17 Dublin

From: davidoff404 (davidoff404_AT__at__NO_SPAMyahoo.com)
Date: 07/17/04 

Date: Sun, 18 Jul 2004 00:36:35 +0100

Jack Sarfatti wrote:

> Julian Barbour replaces 4D Diff with 3D Diff + 3D conformal volume
> preserving transformations and relates it to Mach's principle. p.57
>

Barbour's talk is looking interesting. Of particular note is the fact
that he and his collaborators are able to reproduce *all* of standard GR
by working in conformal superspace, at least in the case where the base
manifold is compact without boundary. The case where the base manifold
is asymptotically flat doesn't seem to work in their CS+V theory since
in this case volume-preserving conformal transormations don't appear to
have any meaning. What's even more interesting is that CMC slicing,
which has up to now been regarded as a pure gauge condition, arises as a
*constraint* in Barbour's CS+V theory. Remarkable stuff.