# Is relativity of simultaneity measurable?

Discussion in 'Physics & Math' started by Pete, May 8, 2013.

1. ### LaymanTotally Internally ReflectedValued Senior Member

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I still don't understand what it is your supposed to be teaching me. I was under the impression that I would have a discussion between two people that already know things. I don't think that is possible because the probability of that happening once could be greater than the lifetime of the universe.

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5. ### Neddy BateValued Senior Member

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That's okay, at least we seem to be in agreement now.

I'm glad we agree RoS is measurable, but I don't think any observers have to come together. Every observer in the universe who can see the left lighting strike could also see the embankment clock located at $x_L$ displaying time $t$ at the instant when the lighting strikes, and they could also see the clock on the train in that location displaying time $t'_L$ at that same instant.

Likewise, every observer in the universe who can see the right lighting strike could also see the embankment clock located at $x_R$ displaying time $t$ at the instant when the lighting strikes, and they could also see the clock on the train in that location displaying time $t'_R$ at that same instant.

7. ### TachBannedBanned

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Too bad that mainstream physics disagrees with you two.

8. ### Neddy BateValued Senior Member

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Ash64449 and I are working under Einstein's definition of simultaneity, and his synchronization of clocks. I think your objection is based on the idea that we can't verify those things.

9. ### LaymanTotally Internally ReflectedValued Senior Member

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I think it is a matter that the experiment didn't verify the arrival times as being different as in RoS, and the the MME was then dubbed a failed experiment....

10. ### Neddy BateValued Senior Member

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But you're the guy who thinks that Relativity theory doesn't even have RoS anymore, because they got rid of it after the MME. You think this even though the MME predates Relativity theory. So, you're really not very well informed on the subject.

11. ### wellwisherBannedBanned

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If you wanted to synchronize two clocks between any reference profile, why not simply adjust the speed of the impacted clock so it cancels the predicted change due to relativity? When the clocks flown in the plane return they have different times. If we simply adjusted these clocks, in advance to compensate, they would remain the same and return synchronized. Relativity tells us how they will change therefore, we know how to tweak each clock for any synchronized profile.

This brings us back to what I said, we can tweak the matter of the clock to maintain synchronization. This works because it was the matter within the clock that was being altered due to relativity.

12. ### Neddy BateValued Senior Member

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You could do that, but then the equations which describe the laws of physics would take on different forms in different frames. With Einstein synchronization, the equations are the same in all inertial frames.

Your method would also require an infinite number of different types of clocks and synchronization schemes. With Einstein synchronization, all clocks can be identically constructed, and there is only one synchronization scheme.

13. ### LaymanTotally Internally ReflectedValued Senior Member

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I have been fully aware that the MME predates relativity theory, but you are unaware that Einstein was unaware of the MME when he wrote RoS. You are just jumping to conclusions, the fact that Einstein didn't know about the MME before he wrote RoS over rides that conclusion you are jumping to solely because of the dates the events happened.

14. ### Neddy BateValued Senior Member

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Einstein wrote about RoS in his 1920 book, Relativity. The MME experiment was done in 1887. So you are saying Einstein was ignorant about MME for 33 years, (at least). Also, RoS manifests itself in the Lorentz transforms, so the only way relativity could get rid of RoS is to replace the Lorentz transforms with something else. Of course that has never happened. So RoS is still part of relativity theory, contrary to your claims.

15. ### LaymanTotally Internally ReflectedValued Senior Member

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They didn't have the internet back then. When did they even develop the telephone? Maybe he just didn't get that memo, lol. Why would he?

Lorentz came across Einsteins paper and then contacted him. They where working on the same theory and then collaborated with each other on it. That is how Einstein became discovered for the theory. If Lorentz wasn't also working on it there probably wouldn't even be a theory of relativity. I would guess that Lorentz didn't know about the experiment either, but I know I read from somewhere before that Einstein didn't know about the experiment when he published his paper in 1905. I think light was only shined on him about the experiment after he wrote the book that contained the RoS.

If the Lorentz transforms are exactly in agreement with the proper time I don't think any mathematical correction is necessary. (I find it hard to see how they could be with gamma in the denominator) It is only the wording of the example that would need to stand corrected, and it was with the light clock example. But, I also don't agree with the light clock example because I think they get the wrong answer because they didn't assign the variables correctly. The mathematical result of changing the time variables in the light clock example is the proper time.

16. ### Neddy BateValued Senior Member

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Do you believe length contraction is still part of relativity, or do you think they got rid of that also?

17. ### LaymanTotally Internally ReflectedValued Senior Member

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Why do you think I would believe that? This would be the first time I have ever heard of anything of that sort.

18. ### Neddy BateValued Senior Member

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Well, to be honest, until you came along, I had never heard anyone claim that they got rid of RoS, and just kept length contraction and time dilation.

Anyway, I'm glad you agree that length contraction is still part of relativity. So, according to the embankment, the train is length-contracted, and yet the train just happens to be the right length to fit between the simultaneous lighting strikes. According to the train, the train is not length contracted, so it is too long to fit in between the lighting strikes. Thus the two lighting strikes cannot be simultaneous in the train frame, because if they were simultaneous in the train frame, the lightning strikes would not strike the ends of the train. You see, length contraction automatically leads to RoS. So they can't toss RoS out of relativity, and still keep length contraction.

19. ### LaymanTotally Internally ReflectedValued Senior Member

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I think this variation of the RoS is in error. I think the entire frame of reference of the train will be contracted so then the flashes will start closer to the train or from the train further away from the train. The flashes will arrive at the same time as according to anyone on the train. This is what happens in reality.

20. ### Neddy BateValued Senior Member

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There is nothing in relativity that says the train will be contracted in its own frame. Quite the opposite. According to the train frame, the train would be its normal rest length, and the embankment would be length-contracted. That makes the lightning strikes even closer together, so there is no way they can happen simultaneously in the train frame, or else they would not hit the ends of the train. You are making up your own version of relativity in an effort to make sense of it without having to understand RoS.

21. ### LaymanTotally Internally ReflectedValued Senior Member

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I never said the train will be contracted in its own frame, so I fail to see how this is a valid rebuttal to my statement. We are talking about science not politics.

I don't agree. I think both frames would be able to be able to measure the flashes starting from the same location simultaneously when their clocks would read different times.

If I am not mistaken you are the one that made up your own version of RoS to do just that. There is nothing in RoS that says that the train will be contracted and be hit by the flashes and in another frame the train will not be contracted so then the flashes do not hit the ends of the train because the train is longer than that distance.

22. ### ash64449Registered Senior Member

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OK. As you say.

23. ### ash64449Registered Senior Member

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Pete, can you say what argument did Tach propose to say that RoS is not measurable?

No need of any articles. Just summarize in few words...

If that argument is valid and there is good logic behind it, i will accept that it is not measurable. But for now for me RoS is measurable.