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Trouton-Noble experiment

  1. Apr 4, 2008 #1
    There is a general lack of awarenes about the fact that Lorenzian interpretation (LI) and Einsteinin interpretation(EI) of relativity (which differ basically in their interpretation of the concept of simultaneity) are observationally indistinguishable. By LI I mean the assumption that the observed lack of the effects of the preferred frame is due to an absolute physical contraction + absolute time dilation(larmor dilation) , due to the velocity of motion relative to the preferred frame .

    However Einsteinian interpretation is preferable not because Lorenzian interpretation is refuted on experimental basis but it is preferable because of 3 reasons.

    1. EI doesn't refer to a concept (namely the existence of a preferable frame ) for which there can be no experimental evidence even if Lorentzian interpretation were correct.

    2. If there is an observed symmetry then it is preferable to assume that this symmetry is something real, rather then assuming that some intrinsically existing assymetry remains hidden in observations because of the form of the physical laws .

    And most importantly,

    3. While in LI the observational equivalence of LT can be explained on the basis of Maxwell equations, there is no reason on the basis of LI why all the physical laws should be Lorentz invariant.

    However despite these advantages of the EI, there is no experimental evidence that LI is wrong. As I mentioned, there are a lot of examples in text books that state LI is refuted by a particular experiment and it can be only explained using EI,

    One example in this context is the Trouton-Noble experiment, for wich sufficient information is available on internet.

    There has been a lot of mostly confusing papers on it but the following paper gives the correct simple explanation why there is no torque.

    J. Franklin, "The absence of 'torque' in the Trouton-Noble experiment",
    arxiv.org/abs/physics/0603110 {Jerrold Franklin 2006 Eur. J. Phys. 27 1251-1256}

    It is because although there is a torque namely although the direction of the resulting Lorentz force deviates from the direction that connects the charges, there is no tendency for the charged plates to change their alignement relative to their direction of motion simply because, the resulting direction of acceleration is not identical to the direction of Lorentz force but it is exactly directed towards other charge.

    The reason is simply because in general dP/dt and dv/dt are not necessarily in the same direction relativistically.
    Last edited by a moderator: Apr 4, 2008
  2. jcsd
  3. Apr 4, 2008 #2


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    Thanks, sounds interesting. I've downloaded the paper and look forward to reading it.
  4. Apr 4, 2008 #3
    If you add the Lorentz Force Law to Maxwell’s equations you get the complete law of classical electromagnetism.

    I have produced equations (non-mainstream) that show the Lorentz Force Law is invariant in an ether flow, and would imaging Maxwell’s equations are invariant as well.

    If the Lorentz Force Law is invariant in an ether flow, I take it the Trouton-Noble experiment's null result would be predictable.
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