Gravitational Redshift (Time Dilatation) - Pound-Repka-Experiment

Links: Wikipedia: Hafele-Keating , Pound-Rebka,  Redshift; Gravitational Redshift, GPS-error

Pound-Repka-Experiment:

Pound and Repka wanted to measure the gravitational redshift of light moving in a gravitational field. The experiment was set up as a variation of Mössbauer spectroscopy. Difference in altitude between gamma-ray source and absorber was 22,50 m.

Result:

The shift in frequency between source and absorber is conform to the prediction of General Relativity. (General relativity predicts that the gravitational field of the Earth will cause a photon emitted downwards (towards the Earth) to be blueshifted (i.e. its frequency will increase) depending on difference of gravitational force.

Question of Einstein test item 9:

What can be concluded by result?

Choice of answers:

A) The frequency of gamma rays have shifted due to gravitational time dilatation

B)  The frequency of gamma rays have shifted due to moving through a gravitational field

C) The frequency of gamma rays have not shifted due to moving through a gravitational field

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