🚀 go-pugleaf

On 22 Nov, 23:08, Tom Roberts <tjroberts...@sbcglobal.net> wrote in
sci.physics.relativity:
> Christoph Schiller wrote:
> > The new, twenty-first edition of the freely
> > downloadable physics textbook is available on
> >    http://www.motionmountain.eu
> > [...]
>
> Thanks. This is an entertaining read, often with an unusual or offbeat
> perspective that is interesting and rewarding.
>
> Tom Roberts

This is the most entertaining text isn't it Roberts Roberts:

Christoph Schiller: "Light can be accelerated. Every mirror does this!
We will see in the chapter on electromagnetism that matter also has
the power to bend light, and thus to accelerate it. However, it will
turn out that all these methods only change the direction of
propagation; none has the power to change the speed of light in a
vacuum."

Now compare Christoph Schiller's discovery (only the direction, not
the speed, changes in a gravitational field) with what you and your
criminal brothers have already discovered:

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html
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 and general 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."

http://www.physlink.com/Education/AskExperts/ae13.cfm
Warren Davis: "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].......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 / c2 ) where V is the gravitational potential relative to the
point where the speed of light c0 is measured."

Tom Roberts wrote in sci.physics.relativity:
> Pentcho Valev wrote:
> > CAN THE SPEED OF LIGHT EXCEED 300000 km/s IN A GRAVITATIONAL FIELD?
> Sure, depending on the physical conditions of the measurement. It can
> also be less than "300000 km/s" (by which I assume you really mean the
> standard value for c). And this can happen even for an accelerated
> observer in a region without any significant gravitation (e.g. in
> Minkowski spacetime).
> Tom Roberts tjroberts@lucent.com

Pentcho Valev