Pound-Rebka experiment

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Jefferson laboratory at Harvard University. The experiment occurred in the left "tower". The attic was later extended in 2004.

The Pound-Rebka experiment is a well known experiment to test Albert Einstein's theory of general relativity. It was proposed by R. V. Pound and G. A. Rebka Jr. in 1959,^[1] and was the last of the classical tests of general relativity to be verified (in the same year). It is a gravitational redshift experiment, which measures the redshift of light moving in a gravitational field, or, equivalently, a test of the general relativity prediction that clocks should run at different rates at different places in a gravitational field. It is considered to be the experiment that ushered in an era of precision tests of general relativity.

The test was carried out at Harvard University's Jefferson laboratory. The frequency of photons emitted by two iron (Fe⁵⁷) sources were compared at a fixed location. They were located twenty-two metres apart, one on the roof of the building and the other in the basement. These sources were chosen because the frequency of the photons they emitted were particularly tightly defined by the Mössbauer effect.

The result confirmed that the predictions of general relativity were borne out at the 10% level.^[2] This was later improved to better than the 1% level by Pound and Snider.^[3]

Another test involving a hydrogen maser increased the accuracy of the measurement.^[4]

[edit] External links

• Physical Review focus story .

[edit] References

1. ^ Pound, R. V., Rebka Jr. G. A. (November 1, 1959). "Gravitational Red-Shift in Nuclear Resonance". Physical Review Letters 3 (9): 439-441. DOI:10.1103/PhysRevLett.3.439. Retrieved on 2006-09-23.
2. ^ Pound, R. V., Rebka Jr. G. A. (April 1, 1960). "Apparent weight of photons". Physical Review Letters 4 (7): 337-341. DOI:10.1103/PhysRevLett.4.337. Retrieved on 2006-09-23.
3. ^ Pound, R. V., Snider J. L. (November 2, 1964). "Effect of Gravity on Nuclear Resonance". Physical Review Letters 13 (18): 539-540. DOI:10.1103/PhysRevLett.13.539. Retrieved on 2006-09-27.
4. ^ Vessot, R. F. C., M. W. Levine, E. M. Mattison, E. L. Blomberg, T. E. Hoffman, G. U. Nystrom, B. F. Farrel, R. Decher, P. B. Eby, C. R. Baugher, J. W. Watts, D. L. Teuber and F. D. Wills (December 29, 1980). "Test of Relativistic Gravitation with a Space-Borne Hydrogen Maser". Physical Review Letters 45 (26): 2081–2084. DOI:10.1103/PhysRevLett.45.2081. Retrieved on 2006-09-24.