What is Pound-Rebka experiment?
The '''Pound-Rebka experiment''' was an [[experiment]] by [[Robert Pound]], and [[Glen Rebka]] that was done in 1960. In his [[general theory of relativity]], [[Albert Einstein]] predicted that [[gravitation]] would influence [[Photon|photons]] the same way it did massive particles: Photons gain [[energy]] when traveling toward a gravitational source (the [[Earth]]). The experiment measures the change of frequency of light moving in a gravitational field. In this case, the effect was a [[blue shift]], the energy increased. {{Physics-stub}} [[Category:Physics experiments]]