Re: Einstein interpretation of gravitational redshift is misleading


Sue... wrote:
mluttgens@xxxxxxxxxx wrote:
Sue... wrote:
mluttgens@xxxxxxxxxx wrote:
Sue... wrote:
mluttgens@xxxxxxxxxx wrote:
Sue... wrote:
mluttgens@xxxxxxxxxx wrote:
Sue... wrote:
mluttgens@xxxxxxxxxx wrote:


As the receiver is moving relatively to the source, why doesn't he
observe a blue shift due to the Doppler effect, instead of no shift
at all?


The Mossbauer 'receiver' is extremely narrow due to the high
Q of the atomic oscillator. It only observes (absorbs) light
which is of the right frequency and phase to permit an
efficient transition to a permissible energy level.

A wide band receiver will intercept the transitions at a
higher rate due to the closing motion, just as you have
described.

Sue...

Thank you.

Only crackpots would stick to the explanation according to which
"clocks which run the faster the higher they are located in the
potential, whereas the energy and frequency of the propagating photon
do not change with height."

But, nevertheless, most GRists will probably not openly recognize that
such explanation is "misleading".

Marcel Luttgens

LOL
I am looking for a Pound-Rebka-Snider experiment down a
mine shaft. I think that would clear up a lot of the misunderstanding
but so far I haven't found one. Either my research skills are
getting rusty or graduate students have a softer life these days.

Sue...

You wrote:

"I am looking for a Pound-Rebka-Snider experiment down a
mine shaft. I think that would clear up a lot of the misunderstanding
but so far I haven't found one."

In the meantime, you could content yourself with the formula easily
obtained by using the potential energy of the photons:

Nu1 is the frequency of the signal sent to the bottom
of the shaft.
Nu2 is the frequency of the signal received at the bottom.
d is the distance of the bottom of the shaft to the Earth's center.
Me and Re are respectively the mass and the radius of the Earth.
The shift Nu2/Nu1 - 1 = (GMe/2Re^3c^2) * (Re^2-d^2)

If GR doesn't get the same formula, it is false.

Equation 14 looks reasonable:
http://arxiv.org/abs/gr-qc/9606079

Equation 14 should here be written in terms of the shaft depth!
Perhaps a true GR specialist could do this.


"Perhaps they anticipated it might be used on another
planet where the shaft depth would be meaningless."

Ha Ha !



It is in terms of gravitational potential so
would predict the lowest frequency at the surface
then increasing as the clock either moved up or down.
That is consistant with free pendulms, long know to
decrease in frequency when moved up or down from the
surface.

As for your equation above, Nu1 should equal Nu2.

Look at my equation: the shift is given by (GMe/2Re^3c^2) * (Re^2-d^2)
Only if d = Re is Nu2 equal to Nu1 (the depth of the shaft is 0).
If d = 0 (the receiver is at the Earth's center), the shift becomes
GMe/2Re*c^2.
This shift should rather easily be obtained with GR.

I would rather review the arithmetic for the bellhop paradox
again than your equations after your statement that light
changes frequency absent a change in path length.

"Are you saying if the paper substitutes your equation
or the one they used then it will make the paper wrong?"

As long as their equation 14 is not written in terms of Me, Re and d,
I prefer to wait and see.

A nicer form of the "shaft" shift formula is
shift = GMe/2Rec^2 * (1-d^2/Re^2),
where d is the distance between the bottom of the shaft and the
Earth's center.
The shift could of course be expressed in terms of the
shaft depth = Re-d. Replacing d by Re-depth, one gets
shift = GMe/2Rec^2 * (1-(Re-depth)^2/Re^2)

If the depth = Re, one is left with shift = GMe/2Rec^2 (1)
Let's remember that the signal is sent from the Earth's surface
to the bottom of the shaft.

Notice that a signal emitted at infinity towards the Earth's surface
would be observed to be shifted by GMe/Rec^2 (also according to GR).
The fact that this shift is twice the "shaft" shift (1) must be
more than a coincidence!

Marcel Luttgens

You have us totally confused. You posted Okun's paper
that explains how to avoid the causality violating interpretation.

But now you are arguing on both sides of the issue and
stating propagation effects that violate causality. Perhaps
you should re-read the paper, then attack someone elses
work instead of your own... if you can find fault.

Equation 14 looks reasonable and it appers in full
conformity with Okun's recommendations.
http://arxiv.org/abs/gr-qc/9606079

Sue...

Okun's paper is "misleading" because

"For a freely falling absorber, a signal emitted from the ground
would appear *Doppler blue shifted* by gH/c^2 if it were not
*beforehand* red shifted by gH/c^2 by "the gravitational attraction
of the massive body".

Because of the Doppler effect, one has to accept that the energy and
frequency of the propagating photon change with height, and that clocks

don't run the faster the higher they are located in the potential."

Otoh, I gave a formula for the shift of a signal sent from the Earth's
surface to the bottom of a shaft.

I don't see any contradiction.

Marcel Luttgens

.