Violation of Special Relativity Principle?

[PhysicsTruth]

TL;DR Summary

Violation of relativity principle in discrepancy in observation of clocks in a stationary frame with respect to a uniformly moving frame.

From the michelson-morley experiment, if a clock were to measure the time period of light hitting the mirror and returning back, it would be 2L/c, where L is the distance between the laser nd the mirror. For a moving observer, the time period would have a factor of *gamma*, the boost factor, multiplied to 2L/c. Now this is a thought experiment- Suppose the moving observer sees that the time periods of other similar clocks (placed near the original clock) do not change in a similar fashion as the original clock, then is the Homogeneity principle violated in this case? Time periods should change similarly for every clock as seen by the moving observer, as there is no preferred clock. Am I correct in this?

 

[Dale]

If I understand your scenario correctly, yes. To be clear, you are envisioning a collection of identical clocks at different locations but at rest with respect to each other and in the absence of gravity or other external influences.

 

[PhysicsTruth]

If I understand your scenario correctly, yes. To be clear, you are envisioning a collection of identical clocks at different locations but at rest with respect to each other and in the absence of gravity or other external influences.

Yeah, identical clocks in stationary frame observed by the moving frame observer.

 

[PeroK]

Suppose the moving observer sees that the time periods of other similar clocks (placed near the original clock) do not change in a similar fashion as the original clock ...

What do you mean by "sees"?

 

[PhysicsTruth]

What do you mean by "sees"?

Observes? Calculates?

 

[PeroK]

Observes? Calculates?

Is this to do with light signals from clocks that are further away taking longer to reach an observer?

 

[Halc]

Yeah, identical clocks in stationary frame observed by the moving frame observer.

If you mean a large number of clocks all stationary relative to some inertial frame and synced in that frame, then yes, an observer moving relative to that frame and looking at those clocks go by like frames in a movie would see them tick fast by a factor of gamma. He could also watch the distance markers go by and measure his proper velocity as the rate at which those markers count upwards. This would be his proper velocity, which can exceed c. For this reason it is possible to visit the far side of the galaxy before I die in a sufficiently fast ship. I just need to move at a proper velocity of (in my case) perhaps 5000c.

 

[PhysicsTruth]

Is this to do with light signals from clocks that are further away taking longer to reach an observer?

This is related to the Michelson-Morley experiment.

 

[PeroK]

This is related to the Michelson-Morley experiment.

But more than that you're not prepared to say?

 

[PhysicsTruth]

But more than that you're not prepared to say?

:) But I've shared already the details of the thought experiment.

 

[Dale]

Yeah, identical clocks in stationary frame observed by the moving frame observer.

Yes. Then that would violate the homogeneity principle

 

[PeroK]

:) But I've shared already the details of the thought experiment.

I see no details, just vague hypotheticals.

My guess is that you think you've spotted a fundamental flaw in SR and you're not sure whether

1) you've made a beginner's error in trying to understand SR.

Or

2) you've seen more deeply than the great physicists of the 20th century.

Is that it?

 

[PhysicsTruth]

I'm just a beginner in physics, and I just know that I love it, even though I am terrible at it. It was just a thought experiment, and I wanted to figure it out to be sure. Special relativity is daunting enough for a beginner like me!

 

[PhysicsTruth]

Yes. Then that would violate the homogeneity principle

Thanks. That affirms my intuition.

 

[PeroK]

Yes. Then that would violate the homogeneity principle

How can you say that if we don't know what the OP is talking about?

 

[Dale]

How can you say that if we don't know what the OP is talking about?

He explained it clearly enough to me.

 

[pervect]

Summary:: Violation of relativity principle in discrepancy in observation of clocks in a stationary frame with respect to a uniformly moving frame.

From the michelson-morley experiment, if a clock were to measure the time period of light hitting the mirror and returning back, it would be 2L/c, where L is the distance between the laser nd the mirror.

I would add the qualifier that L is the distance between the laser and the mirror in the interferometer frame. Distance in special relativity are in general frame dependent, so one should specify the frame of observation.

For a moving observer, the time period would have a factor of *gamma*, the boost factor, multiplied to 2L/c.

It is important here to know the direction in which the observer is moving. For instance, they might be moving parallel to the interferometer axis, or they might be moving transverse to it. Or the might be moving in some arbitrary direction. A more precise definition of the motion is needed to answer the question.

Now this is a thought experiment- Suppose the moving observer sees that the time periods of other similar clocks (placed near the original clock) do not change in a similar fashion as the original clock

Are these similar clocks moving at the same velocity?

then is the Homogeneity principle violated in this case? Time periods should change similarly for every clock as seen by the moving observer, as there is no preferred clock. Am I correct in this?

I'm not sure I understand the relevance to the title of the thread, but if you imagine a bunch of clocks at rest in some inertial frame S, and some other inertial observer in frame S', an assuming that the difference in position of the clocks in frame S caused a change in clock rate as measured in frame S' would be a violation of homogeneity, and would also be in violation of special relativity. It is important to the argument that S and S' both be inertial frames.

 

[PhysicsTruth]

I would add the qualifier that L is the distance between the laser and the mirror in the interferometer frame. Distance in special relativity are in general frame dependent, so one should specify the frame of observation.
It is important here to know the direction in which the observer is moving. For instance, they might be moving parallel to the interferometer axis, or they might be moving transverse to it. Or the might be moving in some arbitrary direction. A more precise definition of the motion is needed to answer the question.Are these similar clocks moving at the same velocity?
I'm not sure I understand the relevance to the title of the thread, but if you imagine a bunch of clocks at rest in some inertial frame S, and some other inertial observer in frame S', an assuming that the difference in position of the clocks in frame S caused a change in clock rate as measured in frame S' would be a violation of homogeneity, and would also be in violation of special relativity. It is important to the argument that S and S' both be inertial frames.

I meant to say that if a moving observer were to observe similar such clocks placed in the rest frame as the original one, then, if he were to observe that the clocks did not tick in a similar fashion as the original one he had observed in the rest frame, then the principle of homogeneity is violated. Yes, if the principle of homogeneity is violated, STR is violated in general as homogeneity is one of the guiding principles of STR.

 

[PhysicsTruth]

How can you say that if we don't know what the OP is talking about?

Sorry for the confusion. You can check out the main content of my thread. I had tried to make my thought experiment as clear as possible over there.

 

[Dale]

Yes, if the principle of homogeneity is violated, STR is violated in general as homogeneity is one of the guiding principles of STR.

Not really. The principle of homogeneity is that the laws of physics are homogenous. Violations of homogeneity are always due to inhomogeneous matter/fields, not inhomogeneous laws. So that is no violation.

That said, SR is violated any time there is tidal gravity. That is well known and not problematic.

 

[PhysicsTruth]

Not really. The principle of homogeneity is that the laws of physics are homogenous. Violations of homogeneity are always due to inhomogeneous matter/fields, not inhomogeneous laws. So that is no violation.

That said, SR is violated any time there is tidal gravity. That is well known and not problematic.

Ok, that is something new I got to learn. By the way, I knew that homogeneity referred to the independence of origin in space-time events.

 

[Dale]

Ok, that is something new I got to learn. By the way, I knew that homogeneity referred to the independence of origin in space-time events.

Homogeneity means that the laws of physics are the same at all locations in space. Sometimes homogeneity is taken to include time. Per Noether’s theorem homogeneity in space implies the conservation of momentum and homogeneity in time implies the conservation of energy.

 

[PeroK]

Sorry for the confusion. You can check out the main content of my thread. I had tried to make my thought experiment as clear as possible over there.

Sorry if I misunderstood what you were asking. I must admit I still have no idea what this thread is about.

Why would SRT of all things be violated by the MM experiment?!

 

[vanhees71]

The MM experiment in textbooks is usually analyzed in terms of Newtonian physics leading to the wrong prediction that you could observe an "aether wind", and this is taken as a motivation to introduce special relativity. Then the textbooks do not discuss the MM experiment again in terms of relativistic physics, proving that this indeed explains the observed null effect (BTW a fact that Michelson didn't like too much, so that he repeated the experiment over and over again never finding any evidence for the sought "aether wind") of course.

Of course the relativistic treatment is very simple on a somewhat simplified level: Seen in the frame where the apparatus moves, through the length contraction there's no difference in the time the light needs running between the mirrors and thus there's no shift of the interference fringes when turning the apparatus by 90 degrees.

For a full description, including the laws of reflection etc. it's not that simple anymore:

https://doi.org/10.1119/1.17535