# Pound-Rebka Experiment - Astronomy Pound-Rebka Experiment Experiment Background Experiment done in 1959 at Harvards Jefferson laboratory to test Gravitational Red-Shift of light predicted by Einsteins Theory of General Relativity Background Information

Principle of Equivalence states that the force of a gravitational field is equivalent to the acceleration of a given reference system. From the Principle of Equivalence we can also conclude that any frequency shift in light produced by acceleration can also be produced by the appropriate gravitational field. This is like a relativistic Doppler shift.

Experiment Set Up 2 Light Sources- 1 on top of the 22.5 meter laboratory, 1 in the basement.

Experiment Set Up Hypothesized that the Gamma Rays emitted from basement would have a gravitational red shift and Gamma Rays emitted from the roof would have a gravitational blue shift. Prepared the Gamma Ray detectors out of a combination of Iron and Cobalt heated to a high temperature to increase its

sensitivity and resolution to red shift. Equations Used in Experiment By using equations for gravitational potential energy and the relativistic energy expression, the gain in energy of a photon which falls a distance h is : Equations Used in Experiment

Difference in energy shifts from the 2 gamma ray emissions was predicted to be: While it was measured as: Results Basement emitted gamma ray of wavelength

of 1 measured on roof as having wavelength of 1.000000000000002455 Roof emitted gamma ray of wavelength 1 measured in basement as having wavelength of .99999999999999755

Implications The measured energy difference and gravitational shift was within the error margin of the predicted value by General Relativity Experiment claimed as Proof of General Relativity Bibliography

Harvard Gravitational Red Shift Experiment. http://www.circlon-theory.com/HTML/poun dRebka.html Equivalence Principle. http://en.wikipedia.org/wiki/Equivalence_pr inciple Gravitational Red Shift. http://hyperphysics.phy-astr.gsu.edu/hbas

e/relativ/gratim.html