# On the idea of time in physics-relativity

Discussion in 'Physics & Math' started by ash64449, Mar 15, 2013.

1. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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One is an actual experiment of what happens, and the other is an experiment that says what happens that was just made up in a guys head.

3. ### Neddy BateValued Senior Member

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Nothing is ever larger than its rest size.

5. ### PeteIt's not rocket surgeryModerator

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When the toy MME is done on the train, the flashes reflect off the train mirrors at the same time according to the train clocks, as shown by the blue flashes in the train rest frame diagram.

When the toy MME is done on the platform, the flashes reflect off the platform mirrors at the same time according to the platform clocks. This is not illustrated on the diagrams. Can you draw it yourself? Or would you like me to add it?

They do match up. The diagram clearly shows that the flashes return to the detector at the same time.
They both travelled for the same time at the same speed, so they clearly covered the same total distance

"Gauge invariance" desribes a particular aspect the laws of physics, as explained by Dr Carroll in your book. "Gauge invariance of frames observing each other" isn't a meaningful phrase.

"frames observing each other" isn't meaningful either, so it's not clear what you're thinking. It might help to focus on the measurements made with the clocks and rulers of each frame.

Last edited: Apr 4, 2013

7. ### Neddy BateValued Senior Member

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Nothing is ever larger than its rest size. I provided the calculations for the lengths as measured by the train frame, and the platform is shorter than the train. So, you can stop acting as if the lightning strikes were simultaneous in the train frame. It is impossible. Unless you want to add "length contraction" to your list of things you believe relativity got wrong, along with relativity of simultaneity.

8. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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I thought that was your problem, you shouldn't try and push your own problems onto me. That was on your list of things to do, not mine. You brought the whole thing up. I was talking about if relativity of simultaneity actually predicts if the beams of light arrive at the same time and if this agrees with experiment. The interpretations of the MME that I have read do not say the same thing as the thought experiment in this regard.

9. ### Neddy BateValued Senior Member

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It's your problem because you've been saying the light from both lightning strikes arrives simultaneously at the observer located at rest with the midpoint of the train. But if the lightning strikes do not occur simultaneously in that frame (as they cannot because the platform is shorter than the train), then you are wrong to make that claim. In short, it is your problem because it proves you wrong.

10. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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Seemed like a very meaningful phrase to me, I am saying that there is gauge invarience from one frame and another frame that is in relative motion. You could have two MME traveling at a relative speed, and then the scientist flying their MME could look at each other and say that they both got the same results.

It just means that someone in one frame is looking at events that are taking place in another frame. So if you put a MME on a ship, and then looked at it through the Hubble Space Telescope, you would find the same results from the experiment that a scientist on the ship would with the experiment.

11. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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I am saying that what I am saying is what happens in the actual experiments, so then that proves you wrong, since actual experiments should overrule thought experiments.

12. ### Neddy BateValued Senior Member

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So you are saying the MME proves length contraction false?

So you believe relativity is correct, except for the part about relativity of simultaneity, and except for the part about length contraction. Nice!

13. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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Nowhere did I say length contraction was false, it is only a problem with your own understanding. I do agree with the interpretation of the MME, and that the beams will always arrive at the same time. If you try to look into my derivation on post #266, when you translate the triangle to form a right triangle by moving the vector of an objects velocity down, you are actually saying that location is the same location both observers agree on where the beam of light is, their clocks just don't read the same time when this happens, and that is how time dilation makes it agree with the experiment, then I got the equation for the proper time. So then the proper time can be derived by assuming that a beam of light is at the same location relative to two different frames that clocks then read different times.

14. ### Neddy BateValued Senior Member

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Do you agree with my calculations showing that the platform is shorter than the train, according to the train frame?

15. ### originTrump is the best argument against a democracy.Valued Senior Member

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PL undstands none of this, he realizes he doesn't understand it so he has decided to annoy everyone by making absurd claims. Anyone who says the universe is wrong and they are right is just jerking your chain or insane. He is not insane which is clear by his goading demeanor - which of course means he is just a troll just jerking your chain.

16. ### Neddy BateValued Senior Member

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I'm surprised you are ruling out insanity, lol.

17. ### PeteIt's not rocket surgeryModerator

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Well, there's no problem.

If the platform observer looks at the train clocks and rulers, they can see that the flashes reflect off the train mirrors at the same time according to the train clocks, and return to the train detector at the same time, as shown by the blue flashes in the train rest frame diagram.

To spell it out:
When the MME is done on the train, the train clocks and rulers define the result of that experiment.
The platform clocks will show different readings from the train clocks (as shown in the platform rest frame diagram), but they are not used to define the result of the experiment.

18. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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I wouldn't kid yourself, insanity is the only thing he ever see's in anything or anyone. This could change at a snap of a finger. It seems he has expanded his mind into thinking he is the universe now instead of just everyone on Earth. I am saying the universe is right, the actual experiments are correct. I think it is more of a problem with origin (the person) not having that high of a degree in physics or one at all, maybe just internet know how (that really wouldn't be worth anything at all).

19. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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It does if you consider their beam of light measurements in the experiment. It would be like saying that the train can gain more or less on the photon so that the platform then measures the speed of light. The people on the train wouldn't be able to notice that they gain more or less on each photon because of their direction of motion. That is what makes it gauge invarient. The people on the train experience the same thing as the people on the platform do in their experiments. If the people on the train noticed that they gained more or less on the same photon then they wouldn't measure each one to be the speed of light. It would be the speed of light plus their velocity and the speed of light minus their velocity, but this is not what happens because there is no aether! The only thing absolute here is the speed of light. Everything then changes with funky mathmatics inorder to keep it that way.

20. ### PeteIt's not rocket surgeryModerator

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Sorry, I don't follow what you mean. The platform clocks and rulers measure the speed of light as c. The train clocks and rulers also measure the speed of light as c.

Yes, I agree. That's what the train frame diagram shows.

21. ### Prof.Laymantotally internally reflectedRegistered Senior Member

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It is hard to explain, but it is like when you consider the light spheres of each frame. The light sphere of one frame would then not expand out equally from another frame that it is overlapping in the diagram. Since the light sphere of one frame does not spread equally when shown over another frame, then that other frame would not be measuring the same speed of light in every direction as according to that other frames light sphere. The overlapping light spheres from different frames imply that certain directions then gain more or less from different directions in the other frames light sphere. This aspect of it doesn't agree with interpretations of the MME. It wouldn't be completely correct to just overlap a light sphere on another frame and then say, hey this is how they see it from this frame.

If the speed of light is constant in all frames, then all frames would have their own light sphere that would spread equally away from them, and would not have light spheres that spread unequally from other frames.

22. ### PeteIt's not rocket surgeryModerator

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Sorry, Layman, that makes no sense at all. It seems you're way overthinking this, and getting confused by mixing frames together.
It's very clear in the diagrams that all the light flashes have the same speed in both frames.
Can you see any light flash that doesn't have a speed of c?

Do you see that the MME done in the train has the expected result?