Pound/Rebka showed in 1960 that electromagnetic radiation apparently lost energy in the gravitational field of earth. The energy difference was according to Einstein 5x10E-15 of the output energy at 45m heigh difference.
The stronger gravitational field of the sun and the distance of 1,5xE11m leads one to expect a much higher energy difference. It should be possible to observe the gravitational red shift by comparing spectral lines. Exist there any observations?
According to some information I found on the net, the thermal broadening of solar spectral lines is about 16 times larger that the predicted gravitational redshift. This makes it difficult to observe the effect. Other material seems to indicate that the issue is unsettled. I.e., that one has not given up on observing the effect, but that corrections and distortions must be understood sufficiently well.
The Pound/Rebka experiment became possible with the help of the Mössbauer effect, which prevents additional broadening of spectral lines (due to nuclear motion and recoil).
Thanks for your answer, Kåre.
The disturbing effects at the Pound/Rebka experiment were more than five times higher than the assumed red shift. This experiment would be reliable in vacuum.
There exist obvious no reliable observations about gravitational red shift of solar radiation. But it should be so significant that easy optical instruments prove it before Einstein's theories.
I am amazed ...
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