🚀 go-pugleaf

On Mar 11, 11:21 pm, Pentcho Valev <pva...@yahoo.com> wrote:
> On Mar 11, 5:27 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote in
> sci.physics:
>
>
>
> > 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.
>
> >         Yes, as one prolific idiot around here is fixated on,
> >         in the APPROXIMATION of weak fields and restriction to
> >         paths at fixed gravitational potential, for Newtonian
> >         coordinates one can express the non-local COORDINATE
> >         speed of light in terms of the gravitational potential.
> >         In 1911 Einstein did not understand all the caveats
> >         mentioned here, but certainly did by 1915; this idiot
> >         still does not understand them.
>
> The year is 1920 Roberts Roberts and Divine Albert still believes that
> the speed of light "varies with position" in a gravitational field, as
> Superior Brother Steve Carlip explains to you:
>
> http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_o...
> Superior Brother Steve Carlip: "Einstein went on to discover a more
> general theory of relativity which explained gravity in terms of
> curved spacetime, and he talked about the speed of light changing in
> this new theory.  In the 1920 book "Relativity: the special andgeneral theory" he wrote: ". . . according to the general theory of
>
> relativity, the law of the constancy of the velocity of light in
> vacuo, which constitutes one of the two fundamental assumptions in the
> special theory of relativity [. . .] cannot claim any unlimited
> validity.  A curvature of rays of light can only take place when the
> velocity of propagation of light varies with position."  Since
> Einstein talks of velocity (a vector quantity: speed with direction)
> rather than speed alone, it is not clear that he meant the speed will
> change, but the reference to special relativity suggests that he did
> mean so.  THIS INTERPRETATION IS PERFECTLY VALID AND MAKES GOOD
> PHYSICAL SENSE, but a more modern interpretation is that the speed of
> light is constant in general relativity."
>
> In a sense, Superior Brother Steve Carlip is less dishonest (or more
> naive) than you Roberts Roberts.
>
> Pentcho Valev
> pva...@yahoo.com

Interesting, but why does light reflect off a mirror, or get refracted
by an atmosphere?

Perhaps photons do not actually bend, but merely interact with other
matter, be it regular or dark matter.
. - Brad Guth