Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Has the gravitational red shift been proven for electromagnetic waves only or also for a single photon?

share|cite|improve this question

The first I believe was the Pound-Rebka experiment in 1959 in a tower at Harvard.

The best experimental proof we currently have available is the daily successful operation of the Global Positioning System (GPS).

share|cite|improve this answer
Here I was writing an answer using the same examples. That makes you a party pooper. Pssssstttthhhhhh.... Note that because they used the Mössbauer effect on gamma rays the Rebka and Pound experiment counted discrete photons and of course the GPS system uses EM wave antennas, so both bases are well covered. – dmckee Feb 23 '12 at 20:44
Great minds, etc. – Mark Beadles Feb 23 '12 at 20:55

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.