🚀 go-pugleaf

On Feb 19, 11:41 am, "Juan R." González-Álvarez wrote in
sci.physics.relativity:
> Pentcho Valev wrote on Thu, 18 Feb 2010 22:42:22 -0800:
>
> > "Gravitational time dilation" is just one of Einsteiniana's panicky
> > reactions to a great threat: the frequency of light the receiver
> > (observer) measures is often different from the frequency the emitter
> > measures, that is, light is often redshifted or blueshifted. In
> > accordance with the formula:
>
> > (frequency) = (speed of light)/(wavelength)
>
> > the only reasonable explanation of the measured frequency shift is that
> > the speed of light relative to the receiver is different from the speed
> > of light relative to the emitter, that is, the speed of light is
> > VARIABLE, not constant. "Gravitational time dilation" misleads the
> > public into believing that the frequency shift is due to a miraculous
> > time dilation dependent on the gravitational potential, not to a
> > variation of the speed of light:
>
> You got all plain wrong again. In fact textbooks in GR give expressions as
>
> c(r) = c(1 + 2phi/c^2)
>
> which are used in the tests of "Gravitational time dilation" and the result
> agrees with GR predictions

Two points. First, you don't know but clever Einsteinians do know that
c(r)=c(1+2phi/c^2) (Einstein's 1915 equation) is inconsistent with the
gravitational redshift factor 1+phi/c^2 confirmed experimentally. It
is c(r)=c(1+phi/c^2) given by Newton's emission theory of light (known
as Einstein's 1911 equation) which is consistent with the
gravitational redshift factor 1+phi/c^2 confirmed experimentally.

Second, both variable-speed-of-light equations, c(r)=c(1+2phi/c^2) and
c(r)=c(1+phi/c^2), are somewhat secret. Most Einsteinians simply teach
that, in a gravitational field, the speed of light is constant and
that's it:

http://www.amazon.com/Brief-History-Time-Stephen-Hawking/dp/0553380168
Stephen Hawking, "A Brief History of Time", Chapter 6:
"Under the theory that light is made up of waves, it was not clear how
it would respond to gravity. But if light is composed of particles,
one might expect them to be affected by gravity in the same way that
cannonballs, rockets, and planets are.....In fact, it is not really
consistent to treat light like cannonballs in Newtons theory of
gravity because the speed of light is fixed. (A cannonball fired
upward from the earth will be slowed down by gravity and will
eventually stop and fall back; a photon, however, must continue upward
at a constant speed...)"

http://www.astronomynotes.com/relativity/s4.htm
"Prediction: light escaping from a large mass should lose energy---the
wavelength must increase since the speed of light is constant.
Stronger surface gravity produces a greater increase in the
wavelength. This is a consequence of time dilation. Suppose person A
on the massive object decides to send light of a specific frequency f
to person B all of the time. So every second, f wave crests leave
person A. The same wave crests are received by person B in an interval
of time interval of (1+z) seconds. He receives the waves at a
frequency of f/(1+z). Remember that the speed of light c = (the
frequency f) (the wavelength L). If the frequency is reduced by (1+z)
times, the wavelength must INcrease by (1+z) times: L_atB = (1+z)
L_atA. In the doppler effect, this lengthening of the wavelength is
called a redshift. For gravity, the effect is called a gravitational
redshift."

http://helios.gsfc.nasa.gov/qa_sp_gr.html
"Is light affected by gravity? If so, how can the speed of light be
constant? Wouldn't the light coming off of the Sun be slower than the
light we make here? If not, why doesn't light escape a black hole?
Yes, light is affected by gravity, but not in its speed. General
Relativity (our best guess as to how the Universe works) gives two
effects of gravity on light. It can bend light (which includes effects
such as gravitational lensing), and it can change the energy of light.
But it changes the energy by shifting the frequency of the light
(gravitational redshift) not by changing light speed. Gravity bends
light by warping space so that what the light beam sees as "straight"
is not straight to an outside observer. The speed of light is still
constant." Dr. Eric Christian

Steve Carlip even teaches that, although the speed of light is
variable in a gravitational field, lately it has become constant and
that's it:

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html
Steve Carlip: "Is c, the speed of light in vacuum, constant? At the
1983 Conference Generale des Poids et Mesures, the following SI
(Systeme International) definition of the metre was adopted: The metre
is the length of the path travelled by light in vacuum during a time
interval of 1/299 792 458 of a second. This defines the speed of light
in vacuum to be exactly 299,792,458 m/s. This provides a very short
answer to the question "Is c constant": Yes, c is CONSTANT BY
DEFINITION!....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. THIS INTERPRETATION
IS PERFECTLY VALID AND MAKES GOOD PHYSICAL SENSE, BUT A MORE MODERN
INTERPRETATION IS THAT THE SPEED OF LIGHT IS CONSTANT in general
relativity."

Pentcho Valev
pvalev@yahoo.com