- #1
yogi
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- 10
We start with a non accelerating long rocket having a clock C1 and photon source S at the front and a mirror M at the rear - photons are emitted at timed intervals recorded on C1 and their return is measured by C1 - so the round trip time for the rest frame is established. The rocket is then accelerated with uniform thrust and the experiment repeated - now the photon going from S to M will take less time than before and the reflected photon will take longer, both for the same reason as the one-way Sagnac effect. The difference in the time between the round trip with no acceleration and with acceleration can be used to determine the acceleration. Next, the rocket thrusters are turn off and the rocket is placed in a uniform G field that has the same intensity as the acceleration developed by the thrusters - the experiment is repeated - the equivalence principle predicts that the same time difference would be measured - but in the case of the rocket under thrust, the time difference was consequent to the fact that the photon traveled a different distance going and coming - in the G field the distance is the same - but the time should be equal to the result obtained when the rocket was accelerated. In both cases involving acceleration, the photon arrives back at the source at the same gravitational potential - so there is no change in frequency - so is the second experiment properly interpreted as an indication that the local velocity of light is affected by gravity?