# On the idea of time in physics-relativity

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

1. ### SyneSine qua nonValued Senior Member

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I have no idea what you hope to achieve by criticizing something that has not changed in 100 years. No new physics has since altered anything in SR. Light signals will only reach the equidistant observer simultaneously if they were simultaneously emitted. In SR, you can only claim a universally simultaneous emission if they shared the same source location and time, which they do not in this TE.

The reason I say you need to get caught up on 100 year old physics is because you keep asserting Newton's absolute simultaneity.

Again, MMX does not expose relative simultaneity. You keep bringing this up as if you think it exposes some flaw in the TE its results do not even address. As I already told you, the fact that c is invariant in all inertial frames means that absolute simultaneity cannot exist.

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

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I am trying to bring you up to speed about how the properties of light have changed over the past 100 years. The only thing you know about relativity is the relativity of simultaniety, I am saying that it is out dated. The M&M experiment is normally used to explain relativity not Einsteins mind experiment, and it is well known that Einstein didn't know about this experiment, (wonder why that is?). The only place I think that is done is in Einsteins book and the internet. In any other book it will say that the beams of light will reach an observer in motion at the same time that is equidistant even if it is in motion! I think a lot of sites have allowed someone that only knew about the relativity of simultaniety from this book to teach everyone about SR, and has given a lot of people incorrect views on SR because of this.

The mind experiment just doesn't fit with the properties of light, and that is because it is the conclusion of the mind experiment. I am saying what actually happened in actual experiment doesn't agree with the mind experiment. The results are exactly the opposite in this respect. In the mind experiment the beam reaches the observer in the train at different times, in the actual experiment the beam reaches the observer in motion at the same time. It is as simple as that. He wrote this book before he found out the results of the M&M experiment. Einstein was brought up to speed on this issue, it is about time everyone else is brought up to speed about it as well...

5. ### ash64449Registered Senior Member

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This experiment actually tells that speed of light doesn't depend on the object that is emitting.. I mean i do not mean Earth is emitting. i mean it is emitted by a person in earth.. Here nothing is there that explains relativity.. It is just the above conclusion that i have said.. No other conclusion can be taken from this experiment..

7. ### ash64449Registered Senior Member

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From where did you get that conclusion that observer in train sees the the lightning simultaneously??

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

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It is widely accepted that the properties of light are the same as the interpretation of the M&M experiment as being in motion. I just think it comes from a time when the properties of light was unknown, and they where unsure about what would happen in certain events.

For example, a train in constant motion could assume that he is at rest. He then sends a beam of light to the back and front of the train at the same time. He would then measure the beams to reach the ends of the train at the same time. This is said to happen because of the M&M experiment. Theoretical physicist assume that the Earth was actually in motion, and that the experiment actually does prove that an object in motion would measure light to travel the same distance and reach a location at the same time. Einstein did not do this in this mind experiment. The inerpretation of the M&M experiment was what became science, not Einsteins mind experiment. He just didn't know at the time that was what the actual experiment would say. It was just a hiccup in the development of SR.

I think time would have to be dilated differently at the front and the back of the train in order to maintain the constant speed of light relative to both observers at the same time. So I think time would be different at the front and back of the train, I just don't accept that the observer on the train would receive the beams of light at different times because that is not how the properties of light actually are. I don't think there shouldn't be relativity of simultaniety, just that the description of how light behaves in this mind experiment are not correct.

9. ### ash64449Registered Senior Member

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With respect to which reference??(Co-ordinate system)

10. ### ash64449Registered Senior Member

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I watched M&M Experiment.. No other conclusion you can arrive from it.. only this.. Light's speed is always constant and it doesn't depend on the body emitting it and no relative velocity for light... It Actually helps to understand SR easily.. I cannot find why you get opposite result....

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

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From the frame of reference of the observer on the train of course. In the M&M experiment the beams are sent at the same time from scientist in the same frame as the experiment itself. They then measure the beam to reach the end of the experiment at the same time, even though the Earth is in orbit around the sun and rotating, and the sun is revolving around the center of the Milky Way. That would include mutiple forms of acceleration happening at the same time in all directions.

12. ### SyneSine qua nonValued Senior Member

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The properties of light have not changed, so this is only a case of your appalling ignorance of the simplest aspects of SR. The fact that you assert "the relativity of simultaneity... is out dated" is the clearest demonstration you can make of your ignorance. MMX only demonstrates length contraction, as a special case, so MMX alone is not a good, general teaching tool for relativity (only aspects of relativity).

You still do not get the simple fact that what one observer sees as simultaneous (when spatially separated) an observer in relative motion generally will not. And since there is no preferred frame, i.e. invariance of the laws of physics, you cannot demand that the relatively moving observer do so.

It is painfully obvious that you do not understand SR, this TE, MMX, or the properties of light, as you have misrepresented all of these.

13. ### ash64449Registered Senior Member

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Other Conclusion From M&M experiment. LIGHT SPEED IS CONSTANT IN ANY FRAME OF REFERENCE.

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

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Ask yourself this, if the observer on the train saw a beam of light travel the same distance from the front and back of the train, and then he measured them to arrive at different times, would he then be able to conclude that they both traveled at the same speed? $v = \frac {d}{t}$ If the distance is the same and it took a different amout of time to reach a location, then you could only calculate that they had different velocities. The results of the M&M experiment are the result of the constant speed of light being measured to be the same in all frames.

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

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Ya, so what is your point?

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

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When they found the results of the M&M experiment, the properties of light did change, they no longer stayed classical concepts. The mind experiment is a classical physics interpretation of what would happen.

17. ### ash64449Registered Senior Member

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Let me explain M&M experiment in the manner of SR. Light is moving in direction in which the earth is moving.So light needs to travel relativily longer distance. There is a beam splitter. so beams splits into two. A light beam moves perpendicular to beam splitter. so it will travel only the distance that scientist set up. other beam moves parallel to earth's motion.So it goes longer distance,but when it moves back,it needs to move shorter distance to reach the beam. so shorter and longer distance compensate and net it moves the same distance that the beam perpendicular moves. so two beams reach at the same time. See,easy.( note for the scientist,it travels the same distance,but for the observer who doesn't have earths motion sees like this.....)

18. ### ash64449Registered Senior Member

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The above answer is my point..

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

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I don't understand why you are making that point, when I already agree with it, and have this whole time. Makes me think I got you confused somewhere in what I was saying.

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

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But, in the video I linked to look it as a refresher, it claimed that the observer on the train would measure them to reach at different times, not just the obsever on the station. Do you think the video was wrong in saying this?

21. ### ash64449Registered Senior Member

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The M&M experiment is just like this(comparing with the train). AN observer in the train which is moving uniformly emits two beams(observer in the middle). An observer outside sees this and observes like this: Two beams move in opposite direction. A beam which is moving parallel to the train at first moves longer distance while other needs to move shorter distance. another two mirrors is kept opposite sides of the train. so the beam which moved parallel to the train go back travelling shorter distance but the other beam needs to travel longer distance. so those two compensate and reach the observer in the train at the same time. But with an observer in the train, he sees beam reach opposite at the same time and reach him at the same time. because it needs to travel same distance in the frame of observer in the train. See opposite of what we were discussing came!!

22. ### ash64449Registered Senior Member

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NO!! NO!! i will explain later.. Current over here gone!!

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

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Again, I think you missed my post #77, since we posted around the same time.