Re: Letter to Dirk Van de moortel

From: Ben Rudiak-Gould (br276deleteme_at_cam.ac.uk)
Date: 03/04/05 

Date: Fri, 04 Mar 2005 19:08:05 +0000

RP wrote:
> I've engaged Dirk in the same argument. He doesn't seem to grasp that
> he's deriving a GR relationship from SR and the premise of
> nonreciprocity (broken symmetry) in an accelerating field. I could be
> wrong, but then so necessarily was Einstein, since this was the very
> argument that he used to support the necessity of GR, an argument that I
> quoted for Dirk, to no avail.

Einstein was wrong in this case, yes.

> But
> then the extension of SR to accelerating frames *is* GR, so why not call
> it properly GR in which the solution to the twin paradox lies.

GR is not an extension of SR to accelerating frames. It's an extension of SR
to cases in which gravity--by which I mean the Riemann curvature--is not
negligible. An accelerating frame is merely a coordinate relabeling of an
inertial frame. Expressing SR dynamics in terms of these coordinates is a
mathematical exercise; it does not change, or extend, the predictions of the
theory.

-- Ben