Does Gravity Affect the Local Speed of Light in Accelerated Frames?

In summary, the second experiment indicated that the local velocity of light is not affected by gravity.
  • #1
yogi
1,525
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?
 
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  • #2
yogi said:
in the G field the distance is the same
How do you conclude that the distance is the same?
 
  • #3
Mmx

yogi said:
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?
have please a critical look at
arXiv.org > physics > physics/0609118

Physics, abstract
physics/0609118
From: Stefan Popescu [view email]
Date: Thu, 14 Sep 2006 09:13:24 GMT (357kb)
Radar echo, Doppler Effect and Radar detection in the uniformly accelerated reference frame
 
  • #4
The coordinate velocity of light is affected by gravity, but the local velocity of light is not.

If you use local rulers and local clocks, the speed of light locally is still 'c', as long as one uses a short enough distance.

I have to run now, there's probably more to say about this.
 
  • #5
pervect said:
The coordinate velocity of light is affected by gravity, but the local velocity of light is not.

If you use local rulers and local clocks, the speed of light locally is still 'c', as long as one uses a short enough distance.

.

In the first case the rocket is an inertial frame and the total time t* over and back is 2L/c where L is the distance from the C1 to M. In the second case when the rocket is undergoing acceleration "a" the time t' from C1 to M is L/(c-at') and the return time t" from M to C1 is L/(c+at"). When the rocket is placed in a uniform gravitational field "g" where (g = a) should not the round trip time in the g field equal (t' + t") > t* as per what might be expected when the rocket was accelerated. And if the round trip time in the "g" filed is the same as in the "a" field, why do we not have an indication of the effect of g upon local light velocity. I welcome your correction.

Bernard - for some reason my acrobat reader cannot read your paper - I will try again
 

Related to Does Gravity Affect the Local Speed of Light in Accelerated Frames?

What is MMX in an Accelerating Frame?

MMX (Michelson-Morley Experiment) in an accelerating frame is a scientific experiment that measures the speed of light in different directions in an accelerating frame of reference. It was first conducted by Albert Michelson and Edward Morley in 1887 and has been repeated by many scientists since then.

Why is MMX in an Accelerating Frame important?

MMX in an accelerating frame is important because it helps to test the validity of the theory of relativity proposed by Albert Einstein. It also provides evidence for the existence of the ether, a hypothetical substance that was believed to be the medium through which light travels.

How is MMX conducted in an Accelerating Frame?

MMX in an accelerating frame is conducted using a device called an interferometer, which splits a beam of light into two perpendicular beams and then recombines them to create an interference pattern. The interference pattern is then analyzed to determine the speed of light in different directions.

What were the results of MMX in an Accelerating Frame?

The results of MMX in an accelerating frame were unexpected and contradictory to the prevailing theory at the time. The experiment showed that the speed of light was the same in all directions, regardless of the motion of the observer, which contradicted the idea of the ether as the medium for light.

How does MMX in an Accelerating Frame relate to the theory of relativity?

The results of MMX in an accelerating frame were one of the key pieces of evidence that led to the development of the theory of relativity. This experiment showed that the speed of light is constant in all frames of reference, which is a fundamental principle of the theory of relativity.

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