🚀 go-pugleaf

Pentcho Valev wrote:
> 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.
> 
> 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 

Grow up. Learn some physics. Learn to write more accurately and precisely.

It simply is not true that "light emitted by a massive object will reach 'an 
observer far away' with speed less than c". When the light REACHES that observer 
its local speed is c, and that observer will measure it to be c, in the only 
proper way to measure such a speed: LOCALLY. It's just that FAR AWAY NEAR THE 
MASSIVE OBJECT such an observer would assign a COORDINATE SPEED to the light 
that is less than c. Such a COORDINATE SPEED is indeed artificial, and is indeed 
merely an artifact of a poor choice of coordinates. And such a COORDINATE SPEED 
at a position FAR AWAY is not normally what we mean by "speed" in GR.

This is all well known and fully in conformance with the predictions and 
mathematics of GR, and with the way the relativity community uses these concepts 
and words. I have no idea why you are so confused by this, or why you are so 
fixated on it and repeat it endlessly without comprehension.


> after all, there
> is a gravitational potential difference between the point of emission
> and the point of reception.

Bravo -- among your voluminous posts you finally got one thing right.


> 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)

The answer is, of course, that in general NEITHER of those equations is correct, 
and GR most definitely does not obey such equations. Einstein knew this, AND 
SAID SO, but Valev is unable to read and understand EINSTEIN'S words, either. In 
general, to compute the light's average speed over a non-local path, one must 
INTEGRATE OVER THE PATH OF THE LIGHT RAY. The result will depend on both the 
geometry of the manifold and the path. There is no simple formula that can 
capture the complexity of the ACTUAL COMPUTATION in GR.

* In 1955 Einstein was discussing an APPROXIMATION. Is it too much to
   expect you to distinguish between the theory (GR) and AN APPROXIMATION
   TO IT?

* In 1911, Einstein was groping for a relativistic theory of gravitation
   and had not yet completed the groundwork. Is is too much to expect you
   to distinguish between a theory (GR) and an EARLY PAPER NOT CONSISTENT
   WITH IT?

* Pound and Rebka's experiment is consistent with the ACTUAL COMPUTATION
   IN GR. Is it too much to expect you to distinguish between an ACTUAL
   COMPUTATION and some irrelevant formulas you happen to have found?


I have said all this numerous times, and you still don't get it. Spending some 
quality time with a good textbook could remove your confusions, and presumably 
also your fixation with an invalid notion you got from surfing the internet.

You need to find a hobby that is within your capacities. Stalking me in this 
newsgroup is downright rude. But if you're going to do that, at least READ WHAT 
I WRITE and stop re-regurgitating the same nonsense without STUDYING THE SUBJECT.


> [... quotations that Valev clearly does not understand]


Tom Roberts