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.
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