sci.physics.particle

On Mar 10, 8:27=A0pm, Tom Roberts wrote:
> Tom wrote:
> > The speed of light varies depending on the strength of the
> > gravitational field. Einstein said that.
>
> He said that in 1911, early on the then-unfinished journey to General
> Relativity. GR itself does not really have this property -- the _LOCAL_
> speed of light is everywhere c. When measured over non-local paths the
> speed of light can vary, but there is no definite dependence on
> "strength of the gravitational field", it's rather that one must compute
> an integral over the path to obtain the theoretical value for such a
> speed measurement.
>
> =A0 =A0 =A0 =A0 Yes, as one prolific idiot around here is fixated on,
> =A0 =A0 =A0 =A0 in the APPROXIMATION of weak fields and restriction to
> =A0 =A0 =A0 =A0 paths at fixed gravitational potential, for Newtonian
> =A0 =A0 =A0 =A0 coordinates one can express the non-local COORDINATE
> =A0 =A0 =A0 =A0 speed of light in terms of the gravitational potential.
> =A0 =A0 =A0 =A0 In 1911 Einstein did not understand all the caveats
> =A0 =A0 =A0 =A0 mentioned here, but certainly did by 1915; this idiot
> =A0 =A0 =A0 =A0 still does not understand them.
>
> > You might want to check out:
> > arXiv:gr-qc/0704.3485
> > and the references therein.
>
> Arxiv.org gives "bad identifier".
>
> Tom Roberts

At arxiv.org, just enter the numbers 0704.3485 in the search box.
The statement that "the general theory cannot retain this law" is in
the 1954 edition of 'Relativity: the Special and the General
Theory' (sec 27) In section 6 Einstein uses the word velocity to mean
what we would call speed.