🚀 go-pugleaf

On Aug 17, 7:22 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote in
sci.physics:
> Yes, when viewed from far away, using coordinates suited to
> an observer far away, then the coordinate speed of light in vacuum near
> a massive object will be less than c. But that's artificial, a mere
> artifact of a poor choice of coordinates.

Honest Roberts what are you talking about. Be more careful -
Einsteiniana's brothers may rebuke you again. And there is nothing
"artificial" in the fact that light emitted by a massive object will
reach "an observer far away" with speed less than c - after all, there
is a gravitational potential difference between the point of emission
and the point of reception. You will only have to answer the following
question: Does the variation of the speed of light with the
gravitational potential obey Einstein's 1911 equation (given by
Newton's emission theory of light and consistent with the
gravitational redshift factor 1+V/c^2 experimentally confirmed by
Pound and Rebka), or does it obey Einstein's 1955 (in fact, 1915)
"improved" equation (introduced as camouflage and INCONSISTENT with
the gravitational redshift factor 1+V/c^2 experimentally confirmed by
Pound and Rebka):

http://www.physlink.com/Education/AskExperts/ae13.cfm
"So, it is absolutely true that the speed of light is not constant in
a gravitational field [which, by the equivalence principle, applies as
well to accelerating (non-inertial) frames of reference]. If this were
not so, there would be no bending of light by the gravitational field
of stars....Indeed, this is exactly how Einstein did the calculation
in: 'On the Influence of Gravitation on the Propagation of Light,'
Annalen der Physik, 35, 1911. which predated the full formal
development of general relativity by about four years. This paper is
widely available in English. You can find a copy beginning on page 99
of the Dover book 'The Principle of Relativity.' You will find in
section 3 of that paper, Einstein's derivation of the (variable) speed
of light in a gravitational potential, eqn (3). The result is,
c' = c0 ( 1 + V / c^2 )
where V is the gravitational potential relative to the point where the
speed of light c0 is measured."

http://www.speed-light.info/speed_of_light_variable.htm
"Einstein wrote this paper in 1911 in German (download from:
http://www.physik.uni-augsburg.de/annalen/history/einstein-papers/1911_35_898-908.pdf).
It predated the full formal development of general relativity by about
four years. You can find an English translation of this paper in the
Dover book 'The Principle of Relativity' beginning on page 99; you
will find in section 3 of that paper Einstein's derivation of the
variable speed of light in a gravitational potential, eqn (3). The
result is: c'=c0(1+phi/c^2) where phi is the gravitational potential
relative to the point where the speed of light co is measured......You
can find a more sophisticated derivation later by Einstein (1955) from
the full theory of general relativity in the weak field
approximation....For the 1955 results but not in coordinates see page
93, eqn (6.28): c(r)=[1+2phi(r)/c^2]c. Namely the 1955 approximation
shows a variation in km/sec twice as much as first predicted in
1911."

Pentcho Valev
pvalev@yahoo.com