These two scenarios are valid outcomes for the Pound and Rebka
The transmitted signals are generated from identical chunks of radioactive iron, as was used in the experiment.
The signal received at the tower top from the frequency generator at the tower base is noted to be redshifted, while the signal received at the tower base from the frequency generator at the tower top is noted to be blueshifted. There are two possible reasons for this. One is that the frequencies being generated are physically varying, and the other is that the generated frequencies at the tower base and top are red or blue shifted as they climb from or fall to earth's gravity well.
The Sachs-Wolfe effect is dependent on the final scenario being true. But it's not true at all because the frequencies generated in atomic clocks, which will be affected in exactly the same way as a radioactive iron frequency generator, are PROVEN to physically vary with altitude. A fact which would seem to have been well established at the time of the Pound and Rebka experiment.
Even so, the Pound and Rebka experiment was fairly obviously intended to confirm the final scenario, apparently being the prediction of GR at the time, which would later support the Sachs-Wolfe effect. Proving that clock rates physically vary would have been a fairly redundant quest anyway.
The Sachs-Wolfe effect briefly; at the time when the universe first became transparent, matter was not isotropically distributed but was clustered in gravitational potential wells, so, photons released within the wells would be redshifted as they climbed out. Hence an anisotropy in the CMBR.
But that has clearly been proven false.
The reality is that once a wavetrain has been generated, the only alterations that can be made to its passing frequency is through doppler effect or distortions in space-time. If the big bang universe was permitted to expand locally, the effect would be inconsequential over the tower height. But the space-time distortion caused by the gravity well could be more significant. The stretch of dimension would logically increase with depth into the well, which would redshift a wavetrain on the journey in, and blueshift it on the journey out. That's certainly no answer though because it's the reverse of what GR predicts.
But the degree of dimension stretch would be exactly proportional to the rate at which the wavetrain passes by a point at any fixed altitude, so the frequency in the wavetrain would remain constant.
I had previously assumed that the blue curve within the earth, shown in the following graph, would be according to current theory because it's absolutely vital to the big bang theory.
The light blue curve to the right of the 'Earth surface' line in the image shows the clock slowing rates from the earth surface outward, per GM/r/c^2, while the light blue curve to the left of that line was generated using the same formula, but the effect on the clock rate is presumed to be proportional to the gravitational gradient (i.e zero at the earth's center). That presumption was necessary to generate a curve which supports the big bang theory.
Working from the earth center outward, the initial clock location was 100000 meter radius from the center. The mass within that enclosed shell is per M' = M*(r1 ^3/r2 ^3). r2 is the earth surface radius, r1 is the shell radius. GM'/r/c^2 gave the clock slowing rate. The shell radius was incremented by the same amount until the surface radius was reached. From there on, M' is equal to M and remains constant.
The extremely abrupt direction change of the blue curve at the surface may not seem correct, but it's exactly as the big bang theory requires.
The clock slowing rate at the earth center depicted by the yellow circle was calculated using the program attached to the end of the page. It assumes that matter is uniformly distributed throughout the earth, and that every piece of matter within the earth contributes to the clock slowing at that point. The same applies for any other point anywhere within the earth. Calculating the clock slowing rate at the center point is straight forward, but that's not the case for a clock that's offset from the center.
Rather than attempt a proper calculation I've chosen a curve that's proportional to the radius squared to connect between the yellow curve origin and slowing rate given for the surface because it provides the most natural blend between the two points. But a straight line connection would have served the purpose just as well. The stark contrast between the two curves within the earth is very obvious.
The yellow curve results from using the proper definition of gravitational potential, and it's validity has been confirmed. It soundly falsifies the big bang theory.
Since the blue curve within the earth is completely wrong and the origin of the yellow curve is correct, if an atomic clock is placed centrally between two i.e. earth sized planets, it will be slowed according to GM/r/c^2, by both planets. The clock slowing rate is obviously dependent on the separation of the planets. Halving the separation distance doubles the slowing rate.
The frequency generator in an atomic clock functions on exactly the same principle as any other naturally occurring electronic oscillator, and they will all be affected in exactly the same way by the presence of mass. Cycle rates in such mechanisms will always be affected equally, including those that generate the entire spectrum of any blackbody radiator.
A 4000 K blackbody spectrum generated today is OBVIOUSLY nothing like the same spectrum generated in the very densely populated environment of the early big bang universe at the time when the CMBR was released. That spectrum will be roughly that of a 2.73 K radiator relative to now. And it's not an illusion, that's how it begins its journey. Expand what would already appear to us to be a very cold radiator and the big bang theory collapses.
The Sachs-Wolfe effect initially makes things worse for the big bang theory because the 4000 K blackbody spectrum from all gravity wells is redshifted. It's the integrated Sachs-Wolfe effect that is dispatched to save the big bang theory. Briefly; a photon passing through a well of gravitational potential will be blue shifted on the way in and redshifted on the way out, and will emerge exactly as it was before the encounter. But if the well deepens while the photon is passing through, the photon will emerge in a redshifted state.
In the expanding big bang universe, on average, all potential wells across the universe are weakening because the total matter content is becoming more sparsely distributed. Photons traveling the universe from the time of the big bang could be blueshifted by as much as they were redshifted at the start, and would arrive here today as they were when they began their journey. The blueshift applied to the photons would counteract the redshift applied by the expansion. i.e. If the 4000 K spectrum in the early universe was redshifted to that of a 2.73 K spectrum today, it would arrive here today with the spectrum of a 2.73 K radiator.
But it's all a hopeless dream because the Sachs-Wolfe effect has been proven false.
'-------Program start------- 'The program is designed to determine a clock slowing rate 'at the earth's center of mass (the yellow curve origin). 'The earth is divided up into 1000 meter thick shells and 'the mass within those shells is presumed to affect the 'earth center clock according to GM/r/c^2. The results are 'all added together to give the total clock slowing rate. CLS c = 3E+08 pi = 3.1416 G = 6.67E-11 Ma = 5.97E+24 ' Earth mass. rb = 6400000 ' Earth radius. ra = 1000 ' Initial enclosed shell radius. rc = ra PRINT " A clock on the Earth's surface slows by" PRINT G * Ma / rb / c ^ 2; "seconds per second." aa: LOCATE 4, 1 M = Ma / (rb ^ 3 / ra ^ 3) - Mc Mc = Mc + M PRINT M; "kg between"; rc; "and"; ra; "radii. " PRINT Mc; "kg total mass check (Earth). " tb = G * M / ra / c ^ 2 'Enclosed mass outer radius. 'tb = G * M / rc / c ^ 2 'Enclosed mass inner radius. 'Choose either one, or any in between, 'it makes little difference. PRINT PRINT tb; "sec^2 slowing for"; rc; "to"; ra; "shell. " rc = ra tc = tc + tb PRINT tc; "sec^2 total time slowing. " '' DO: s$ = INKEY$: LOOP UNTIL s$ <> "" ' Remove the '' switch to step through the program. IF s$ = CHR$(27) THEN END ra = ra + 1000 IF ra > rb THEN END GOTO aa '-----Program end----------Continues.