🚀 go-pugleaf

On Aug 28, 5:22 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
> obamas_ins...@yahoo.com wrote in sci.physics.relativity:
> > what the hell does the "speed" of light have to do with how fast
> > gravity propagates throughout the cosmos?
>
> Nothing. It's the other way 'round: the local geometry of spacetime
> determines the local speed of light; the geometry of spacetime is what
> we call "gravity".
>
>         Note this is spaceTIME, not merely space.
>         Note also I am using the theoretical context of GR.
>
> Historically, Einstein based SR on a postulate that the speed of light
> is independent of the speed of its source. While that was natural in the
> historical context of 1905, today it is by no means the best approach to
> SR, and some people (like yourself) think it has more relevance than it
> actually has: none.

Bravo Honest Roberts! There was a bold zombie, Laurent Claessens, who
claimed that Einstein was wrong when he said:

Albert Einstein: "If the speed of light is the least bit affected by
the speed of the light source, then my whole theory of relativity and
theory of gravity is false."

Do you agree with zombie Laurent Claessens, Honest Roberts?

> Today, one derives SR in two distinct ways: as the
> local limit of GR, and as a solution to the equations of GR for a
> universe devoid of content. Because of the former, SR is a useful
> approximation for many local experiments, and has been extensively
> tested; because of the latter, SR is not a viable model of the world we
> inhabit (which is clearly not empty).

Bravo Honest Roberts! Perfect camouflage! And yet the crucial
question: is special relativity valid far away from the source of
gravity, where the gravitational field is zero? In other words, was
John Michell right:

http://admin.wadsworth.com/resource_uploads/static_resources/0534493394/4891/Ch01-Essay.pdf
Clifford Will, "THE RENAISSANCE OF GENERAL RELATIVITY": "The first
glimmerings of the black hole idea date to the 18th century, in the
writings of a British amateur astronomer, the Reverend John Michell.
Reasoning on the basis of the corpuscular theory that light would be
attracted by gravity, he noted that the speed of light emitted from
the surface of a massive body would be reduced by the time the light
was very far from the source. (Michell of course did not know special
relativity.)"

If John Michell was right, Honest Roberts, why do your brothers
Einsteinians interpret the redshift of light coming from distant
massive bodies without even mentioning the reduced speed of light?

> In your opening post of this thread you asserted that gravity propagates
> "instantaneously". Such unfounded claims are worthless -- to make them
> stick you need to come up with a theory in which your claim is true, and
> which also agrees with ALL of the currently-known experimental results.
> That's a VERY difficult task, and to date nobody has done so. But if one
> drops your "instantaneous" claim, then GR, with its propagation of
> changes in gravitation at local speed c, agrees with as much of the
> experimental evidence as any other theory, and more than most. Moreover,
> the few observations which might someday become established as
> refutations of GR [#] have difficulties of their own, and at present
> it's easy to consider alternatives other than "GR is wrong".
>
>         [#] The major ones are: dark matter, dark energy, and the
>         anomalous accelerations of several spacecraft. One might
>         add various cosmological problems ("flatness", "horizon",
>         and the need for "inflation"/"quintessence"/...).
>
> You should LEARN something about physics before attempting to write
> about it.
>
> Tom Roberts

How about you becoming even MORE HONEST, Honest Roberts?

Pentcho Valev
pvalev@yahoo.com