thought experiment for general rel., I can't remember how it goes

ericqb

There is a thought experiment pertaining to general relativity that involves a signal traveling from the front to the back of an accelerating space ship, if I remember correctly. I'm sorry for being so vague, but this is something I saw browsing in a library years ago, and I really wanted to think about it, but it slipped out of my mind and now I'm not sure how it goes. I believe that astronaut 1 in the front of the ship sends a pulse of light towards astronaut 2 in the back of the ship. The question is, I believe, how does the transit of this pulse compare to the same pulse in a ship that is moving at a constant velocity instead of accelerating. I'm not sure how much of this I have right but there is a thought experiment with a signal involving two astronauts in the front and back of a space ship that is accelerating. Can someone lead me to this thought experiment and a discussion? Thank you so much. Sorry for the vagueness. ericqb

DaleSpam

I think you are interested in the proof of gravitational time dilation using the equivalence principle. If a light of a certain frequency is emitted at the front of an accelerating rocket then by the time the light reaches a detector at the back of the rocket the detector will be going a different velocity and by the Doppler effect will detect a higher frequency. Therefore, by the equivalence principle a rocket sitting vertically in a gravity field will also detect blueshift for light emitted at the front and detected at the back.

Naty1

If that's what you had in mind, you can compare your thoughts to this discussion:

http://en.wikipedia.org/wiki/Introdu...ence_principle

ericqb

Dear DaleSpam,

Thank you for your help. Sorry it took me so long to reply.

ericqb