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Originally Posted by worzel
KenG has hit the nail on the head several times over, MacM (and others have made very good points too). You can't just ignore the relativity of simultaneity if you want to understand what SR actually predicts, let alone if you want to have a feel for SR "means".
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It is not a matter of what it predicts but how it achieves the purported internal consistancy.
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What you believe about 4D spacetime is completely irrelevant to your claim that SR is inconsistent. When you claim that dilation is just the maths and not physical reality you demonstrate a complete lack of understanding about what science is. SR is a mathematical model; or, two postulates and their necessary implications.
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Yes a mathematical model but unrestrained by common sense and untested in its extremes.
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The model makes predictions. Those predictions have been tested. Those tests have all been passed.
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In another post above I have been accused of simply repeating my arguement. It is time to point out that relativists are doing the same thing. This arguement is about as lame as it gets. As pointed out reciprocity has not been tested, observed or emperically demonstrated. The thousands of tests done do not support the theory in its complete form (consequences of the relative velocity view) but only tests and demonstrates a function which does not differentiate from affects which can also be accounted for in an absolute view.
All that can be said about test data is that it is not
entirely "Inconsistant" with SR, not that it supports SR because it also supports the absolute view and suggests the relative velocity view is incorrect in that recorded permanent differential times by a clock violates the reciprocity advocated by SR.
i.e. - Where is the data that shows the pilots view in H&K atomic clock tests, that the earth bound clocks ran slower (were time dilated) vs the airborne clocks.
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The data for the test you ask for could never been done because you won't allow the clocks to turn around and you won't accept that time dilation is real unless the clocks are brought back side by side.
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Note my scenario was desinged to cut to the chase and up hold the principle of KISS. Others have commented here that the round trip does not alter the conclusion. I am inclined to agree that when properly done the round trip should not alter the conclusion.
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Nevertheless, the model predicts time dilation and all the experimental evidence supports that model and thus transitively supports that prediction.
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And so does an absolute view. See GPS.
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The real problem with your thought experiment is that you are claiming that you are measuring physical time dilation and reaching a contradiction while all that is actually being measured is the passage of time in each frame. Your extra clocks really are just calculations in one frame of how time is progressing in another according to SR.
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Absolutely. And is being done in a simple straight forward manner without all the usual complexiety to get from one to the other.
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The supposed contradiction you reach is to then insist that the relativity of simultaneity is not relevant when resolving the supposed paradox you pose. So you use SR to predict time dilation for each observer according the other but won't allow SR to be used to resolve your paradox!
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I repeat. Does simultaneity or doppler produce permanent recordable changes or are they an illusion of motion measurement? Only permanent changes in accumulated time can be real physical time dilation.
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If you want to acutally measure something physical between the observers then you need to have them observe each other and take into account doppler effects as well, just as CM was kind enough to spell out for you.
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We are not and do not want to "Observe" illusions of motion. We want only to record permanent changes in accumulated time due to relative velocity in accordance with SR. If these other aspects of SR do not affect that then there is no reason to include them.
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Your stop time is defined in A's frame. You then compare all clocks from As frame and conclude that time dilation is one way - but that's just cos you're only doing it one way. The other way is to see what happens in B's and C's frames. Whether you believe time dilation is symmetric or not, doing the calculations only from one frame of reference and then claiming that that demonstrates that it only happens that way is completely circular logic.
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I repeat where is the clock data that supports the expectations of the H&K pilots that the earth bound clocks ran slower than their airborne test clocks?
This is not a calaculation it is physical test. You must address the issue that ONLY the accelerated frame has ever demonstrated time dilation. Never the resting frame which defies the SR reciprocity (equality of frames) arguement.
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As KenG has said repeatedly, to understand the problem you need to think about the relativity of simultaneity. As A and B seperate their notion of what is now both "here" and "there" diverges and that is the resolution to the supposed paradox of reciprical time dilation. You can deny it all you want, but you can't show that it leads to any inconsistencies within the theory and you haven't shown any evidence showing that the theory might be wrong (where we can ignore gravitional effects, that is).
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I have considered simultaneity. I would hope that it becomes apparent that these are not pot shots from the hip. But simultaneity and doppler are only present during the motion of the moving frame and do not contribute to and result in the permanent recorded differential of accumulated time by clocks.
If you can show that they ultimately permanently change time recorded such that it agrees with ALL predictions of SR and not merely one half of the prediction then I will gladly conceed. Failing to do that I will steadfastedly maintain that SR is invalid and that data suggests an absolute view rather than the relative velocity view.
Yours was a good post as well.