🚀 go-pugleaf

On Mar 20, 3:02 am, Pentcho Valev <pva...@yahoo.com> wrote:
> On Mar 18, 7:29 pm, Tom Roberts <tjroberts...@sbcglobal.net> wrote in
> sci.physics.relativity:
>
>
>
>
>
> > John C. Polasek wrote:
> > > On Sun, 16 Mar 2008 17:14:22 GMT,TomRoberts
> > > <tjroberts...@sbcglobal.net> wrote:
> > >>        [Ignore Valev when he brings up Pound-Rebka and similar
> > >>         experiments -- they do not measure speed.]
> > > I think, in a very important way, the experiment did effectively
> > > measure light speed, even though the authors thought frequency was
> > > reduced on the way up ("On the Weight of Photons" iirc).
> > > The Mossbauer filter on a speaker cone was oscillated at a minute
> > > rate, and spectral re-centering was achieved by the Doppler effect. On
> > > the up-stroke, the velocity neutralized the speedup of light as it
> > > left the gravity well.
>
> > Think about it -- there is no time synchornization, and if the effect
> > were due to a change in speed there's no way for the apparatus to be
> > sensitive to it; that is, there's no "nominal distance" relative to
> > which a "speed change" could be measured. Their observations are
> > consistent with a change in frequency (measured via Doppler), and say
> > nothing at all about any change in speed. Whether or not the speed
> > changed in addition to the frequency cannot be answered by this
> > particular experiment.
>
> I would agree with you Roberts Roberts if at this place you did not
> always stick your head in the sand, expose other parts of your body
> and fail to explain clearly the two incompatible implications of Pound-
> Rebka result f'=f(1+V/c^2). Let me do this for you:
>
> The Pound-Rebka result f'=f(1+V/c^2) implies that:
>
> (1) the speed of light in a gravitational filed is VARIABLE as
> Einstein suggests in his 1920 "Relativity" and obeys Einstein's 1911
> equation c'=c(1+V/c^2), whereas the wavelength remains constant. The
> application of Einstein's equivalence principle converts c'=c(1+V/c^2)
> into c'=c+v, an equation given by Newton's emission theory of light,
> where v is the relative speed of the light source and the observer in
> the absence of a gravitational field. Einstein's 1905 light postulate
> (c'=c) is false.
>
> (2) the speed of light in a gravitational field is CONSTANT and obeys
> the equation c'=c, in contradiction to what Einstein claims in his
> 1920 "Relativity". The wavelength is variable and obeys the equation
> L'=L/(1+V/c^2). The application of Einstein's equivalence principle
> leads to the conclusion that the equation c'=c+v given by Newton's
> emission theory of light is wrong whereas Einstein's 1905 light
> postulate (c'=c) is correct.
>
> This is a minimum explanation Roberts Roberts - more could be said in
> favour of (1) and against (2).
>

The above is incorrect in a number of ways.
1. The Pound-Rebka experiment in no way implies that the wavelength is
constant. In fact, the opposite is true.
2. The equivalence principle in no way converts c'=c(1+V/c^2) into c'=c
+v, and I frankly don't see how you could even come close to drawing
that conclusion.
3. The 1905 light postulate applies to *inertial frames* only where
there is no curvature throughout the frame. That is what makes it the
*special* theory of relativity as opposed to the *general* theory. The
Pound-Rebka experiment is not an example of comparing lightspeed in
two inertial frames.
4. There is a distinct difference in a curved space between the speed
of light measured *locally* and the speed of light measured from a
different location in spacetime. It is as simple as measuring the
speed of light at location A from a region near A, distinguished from
measuring the speed of light at location A from a region B far away
from A. Tom's correct statement is that the speed of light in vacuum
is always measured *locally* to be c. Measuring the speed of light at
A from a region B and finding an answer c' =/= c does not change the
truth of Tom's correct statement.

PD