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B Problem with the atomic clock and time dilation

  1. Aug 30, 2016 #1
    The atomic clock is used as evidence of time dilation and to provide more evidence that light speed is invariant.

    The problem I have with this is that the clock uses frequency and light. It has a feedback loop that is supposed to correct for inaccuracies but the entire loop will obviously be effected in the same way by gravity and acceleration so that no correction would take place. The experiment of the atomic clock doesn't prove time dilation it only once again proves that EMF frequency is effected by gravity and acceleration. This isn't anything we didn't already know about light. It is just another example of blueshift and redshifting.

    Furthermore, isn't light speeding up and slowing down in a gravitational field the same thing mathematically as saying that light is constant and instead time slows and speeds up in a gravitational field? How can we truly tell the difference of which it is?

    A watered down example:
    To me it makes more sense to argue that a person is running twice as fast than to argue that he entered into a spacetime warp that caused everything but him to slow down. Mathematically they would be the same.

    5 miles / 1 hour -> 5 x 2 miles / 1 hour = 10 miles / hour or 10 mph
    5 miles / 1 hour -> 5 miles / 1 hour x .5 = 5 miles/ 0.5hrs or 10 mph
  2. jcsd
  3. Aug 30, 2016 #2

    Vanadium 50

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    You're making a strong claim. Either show how this works quantitatively using the known principles of atomic clocks, or admit you are blowing smoke.
  4. Aug 30, 2016 #3


    Staff: Mentor

    As you say, atomic clocks demonstrate that electromagnetic interactions undergo time dilation. There are also experiments that demonstrate that the strong and weak interactions undergo time dilation. There are also experiments that demonstrate gravitational time dilation.

    See http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html
  5. Aug 30, 2016 #4
    The Doppler effect will effect the reference frequency as well as the output frequency in the same way so I am not sure what it is you want to quantize for you...

    -2% on the Reference -> -2% on the output => reference and output are still synchronized
  6. Aug 30, 2016 #5
    Yes, thanks. I have seen this link a few times on this site. I have searched the threads and fumbled through many arguments before seeing it. :) I appreciate the link. But, If you don't mind...Are there specific experiments on that list that I should focus in relation to this discussion?
  7. Aug 30, 2016 #6


    Staff: Mentor

    Section 4 is specifically about time dilation, but any alternative to SR will have to successfully explain all of the experiments in all of the sections.
  8. Aug 30, 2016 #7
    Thanks. I am specifically focusing on the atomic clock under acceleration and gravity experiments and any inter-related experiments that would help understand how various physical properties of light and gravity might effect the experiment. I am not trying to present an alternative to SR.
  9. Aug 31, 2016 #8


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    Why are you obsessed with atomic clocks? As has already been noted, muon decays
    have been used to verify all flavor a of time dilation and they do not involve any electromagnetic interaction at all.
  10. Sep 1, 2016 #9


    Staff: Mentor

    No, because neither of those statements are mathematical statements at all. They are both interpretations (and both are heuristic, limited, and potentially misleading interpretations).

    There is no "difference" here to tell. The physics is what it is. The fact that you can use two different ordinary language phrases to describe it does not mean there are two different possible physical things that could be happening and we have to try to tell which one. There is only one physical thing happening; the two different ordinary language descriptions are both (heuristic, limited, and potentially misleading) attempts to describe the same physical thing.
  11. Sep 1, 2016 #10


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    For clocks under acceleration I find the experiment by Bailey et al. the most convincing, but muons decay by the weak interaction. So the Sherwin experiment may be more appropriate for you as it uses an EM interaction. The Sherwin experiment was at an acceleration of 10^16 g.
  12. Sep 2, 2016 #11
    What about muon decay?

    EDIT- I see this has been brought up, but what are your thoughts on it?
  13. Sep 2, 2016 #12
    Math relies on units and those units have to be defined.

    Many atomic clocks function by measuring these oscillations of the caesium atom. Question: The caesium atom is at 0K. It is at rest. What gravity is it under? If the clock changes because it isn't at rest is time changing or should be adjust for the ossicalations of the clock so that it would measure as if it were at rest? If it is adjusted for gravity, time would always be constant and light would be speeding up and slowing down due to gravity.
    Last edited: Sep 2, 2016
  14. Sep 2, 2016 #13
    Thanks, I am currently reviewing various documents. Unfortunately the experiment isn't in a controlled apparatus so it takes more work to investigate all the variables that might effect the experiment.
  15. Sep 2, 2016 #14


    Staff: Mentor

    It doesn't matter. See the Sherwin and Bailey experiments referenced above. The frequency of an ideal clock is independent of proper acceleration. This is called the clock hypothesis, and it has been confirmed up to 10^18 g.

    What does matter is differences in gravitational potential, as shown in the Pound Rebka experiment.

    I don't like the "time changing" phrasing. Clocks measure proper time, whether they are moving or not, and all frames agree. Different frames disagree on the amount of coordinate time between two events.
    Last edited: Sep 2, 2016
  16. Sep 3, 2016 #15
    Off Topic:
    I had never heard of that until I read it in Rindler's Essential Relativity. But since it's been tested, why isn't it called the clock theory?
  17. Sep 3, 2016 #16


    Staff: Mentor

    That is a good question. I am sure there is some reasonable history about that name, but I don't know it.
  18. Sep 4, 2016 #17
    The muon experiments seem like solid tight evidence. Some of the online pages indicated that it was assumed that the muons traveled at less than the speed of light. This assumption bothered me. Eventually I found a legit article that showed that they measured the speed and how it was done.

    thanks for taking the time to put me on the right track
  19. Sep 4, 2016 #18

    Mister T

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    Engineers involved in the day-to-day synchronization of the various atomic clocks on board GPS satellites wouldn't be concerned with that objection. Time dilation is a fact that they have to account for to do their job, otherwise the GPS would be useless to us. Provided it's precise enough, it matters not what particular technology is used to measure time, the salient point is that time dilates.
  20. Sep 4, 2016 #19


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    You are very welcome!
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