🚀 go-pugleaf

"harry" <harald.vanlintelButNotThis@epfl.ch> wrote in message 
news:49df27b9$1_3@news.bluewin.ch...
>
> "Pentcho Valev" <pvalev@yahoo.com> wrote in message 
> news:452f830f-1287-4e58-84c7-f34aaf4adeba@k8g2000yqn.googlegroups.com...
> On Apr 10, 12:48 pm, "harry" <harald.vanlintelButNotT...@epfl.ch>
> wrote:
>> "Pentcho Valev" <pva...@yahoo.com> wrote:
>> : or is it consistent with
>> : Einsteiniana's discovery that the speed of light is VARIABLE in a
>> : gravitational field and obeys e.g. Einstein's 1911 equation c'=c(1+gh/
>> : c^2) given by Newton's emission theory of light?
>>
>> You should instead refer to his corrected equations of 1916 - which are 
>> NOT given by Newton's theory.
>
> : In 1915 Einstein replaced c'=c(1+gh/c^2) with c'=c(1+2gh/c^2):
>
> : http://www.mathpages.com/rr/s6-01/6-01.htm
> [...]
>
> In view of what you write below, you certainly did not understand the 
> explanation of mathpages that light speed is a function of direction and 
> in this case *perpendicular* to the star. But even that is irrelevant for 
> your problem.
>
> : However the new equation, c'=c(1+2gh/c^2), was incompatible with the
> : gravitational redshift factor experimentally confirmed by Pound and
> : Rebka:
>
> [..]
>
> : "The result is c'=c(1+V/c^2)
> : where V is the gravitational potential relative to the point where the
> : measurement is taken. 1+V/c^2 is also known as the GRAVITATIONAL
> : REDSHIFT FACTOR."
>
> By chance I already cited the redshift prediction here above (in the part 
> you snipped). You failed to notice that gravitational redshift is only due 
> to the difference in resonance frequencies - neither of which depends on 
> the speed of light between the point of emission and the point of 
> reception. And I explained this too many times to you already.
>
> Good luck - you need it.
> Harald

However, there is more to it! Although Pentcho misdirected his attack, the 
above equation of mathpages does appear to be erroneous. Reminder, 
mathpages:

"we have c_r =1+2phi, which corresponds to Einstein's 1911
equation, except that we have a factor of 2 instead of 1 on the
potential term."

According to Einstein 1916, the tangential length of a measuring rod is 
*not* affected by gravity. Thus the tangential speed of light should 
decrease with increasing gravity just as he assumed in 1911, when he only 
accounted for time dilation and forgot to account for a possible change of 
length. By way of fast verification, when comparing the equations in his 
1916 paper I do find the same factor 8*pi*r for tangential speed of light as 
well as time dilation, which is consistent (locally the value c must be 
found).
Apparently the different light bending prediction of 1916 was due to an 
important detail of the calculation (which I never reproduced), and not due 
to a change in the light speed equation as sometimes suggested in the 
literature.

As a matter of fact, the information about this topic in the literature is 
both scarce and confused. I would welcome constructive clarifications about 
Einstein's 1916 paper (p.197-198) from people who studied Einstein's GRT. As 
a reminder, you can get it here:
http://www.alberteinstein.info/gallery/pdf/CP6Doc30_English_pp146-200.pdf

Harald