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Formal definition of the Equivalence Principle(s)

  1. Jan 15, 2007 #1
    Considering how the various forms of equivalence principle can lead to ambiguous discussions, I would like to know if more formal definitions for the various forms of the Equivalence Principles are available.

    I would consider as "formal" all definitions that could be used (formally) to check if a theory satisfies this principle and eventually under which conditions it does.

    For example, to avoid useless discussions about alleged contradictions between the EP and GR, a formal definition would make a formal and general proof crystal clear. I would also be interrested to see such a formal proof, although I consider it is rather obvious (WEP + sufficient smoothness of the equations).

    Thanks for your help,

    Last edited: Jan 15, 2007
  2. jcsd
  3. Jan 15, 2007 #2


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    One might start here:
    http://relativity.livingreviews.org/open?pubNo=lrr-2006-3&page=articlesu1.html [Broken]
    "The Confrontation between General Relativity and Experiment"
    by Clifford M. Will
    Last edited by a moderator: May 2, 2017
  4. Jan 15, 2007 #3
    Thanks Robphy, this is a very interresting reference.
    I also just received a book by the same author on the same subject.
    A little more difficult to read.

    However, there is no formal definition to be found there.

    What I am looking for is not necessarily a big and complicated mathematical formulation.
    It could be just a little bit more precise than casual english.
    Some statement about trajectories or physical variables in the context of the various forms of EP.

  5. Jan 15, 2007 #4
    The equivalence principle states that what we normally think of as the force of gravity is actually the absence of force: a freely falling observer does not feel his own weight, a freefalling frame is equivalent to an inertial reference frame, flat spacetime.
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