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Einstein’s return to ether, what future of relativity?

  1. Aug 8, 2009 #1
    Dear friends,

    In 1920, Einstein had made a quotation as;

    "According to the general theory of relativity space without ether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standard of space and time (measuring-rods and clocks), nor therefore any space-time intervals in the physical sense."

    This is according to Frank Wilczek (a Nobel Prize winner in physics 2004) recent book - “The Lightness of Being (Mass, Ether, and the Unification of forces)”, in which he has talked about Einstein’s ether as – “Einstein’s relationship with the ether was complex and changed over time “!

    Most of us know that conventional relativity is not ether-based, so when Einstein changed his idea, what will happen to the theory? Will it be better, worse or the same?

    Last edited by a moderator: Aug 8, 2009
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  3. Aug 8, 2009 #2

    George Jones

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    For any particular spacetime, there is a (tensor) field defined at each event (point) of spacetime that is used to tell whether paths in spacetime are timelike, lightlike, or spacelike. This field, known as the metric (tensor), seems to be what Einstein had in mind in the above.
  4. Aug 8, 2009 #3


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    The aspect of the classical ether that relativity did away with was the idea of the ether as a physical substance with its own distinct rest frame--Einstein was just using "ether" to refer to the idea that empty space has properties of its own like curvature, he wasn't suggesting any sort of preferred frame.
  5. Aug 9, 2009 #4
    Hi JesseM Aside from the name "ether" with all its clunky connotations , doesn't any idea of space having properties , whether you call it tensor field , or quantum potential field or cosmic foam , automatically imply the possibility that ;
    1) Light is not totally independant of a matrix or medium of some kind????

    This would seem to be a neccessary condition for the expansionist Cosmology conception of red shift due to light stretched along with space.

    2) The possibility that future science of some kind may be able to directly detect it ???

    Last edited: Aug 9, 2009
  6. Aug 9, 2009 #5
    it really does get into semantics here. there is information at each point in space about its curvature and the strenth of the fields at that point. but what if that information is all that there is? can information be a medium? does a wave of information require a medium to be transmitted? I guess it kinda depends on how you want to look at it.
  7. Aug 12, 2009 #6
    Understood and agreed. That is the fundamental question.
    Certainly in the abstract construction of GR there is only information at every point.

    It is also possible that that information is ,in the end, only a description of direct interactions and consequent motions between particles. Without any intermediate field or medium.

    From what I have read Einstein himself had no definite resolution regarding whether curved space was simply a very useful abstraction or whether it had actual physical implications and reality.

    But ,while any discussion of the subject may be semantically slippery, the question itself is both profound and pivotal and IMO merits continual enquiry and open consideration
  8. Aug 15, 2009 #7
    "But ,while any discussion of the subject may be semantically slippery, the question itself is both profound and pivotal and IMO merits continual enquiry and open consideration"

    Quite right - it should not be dismissed - it may well turn out that inertia is in some way related to the conditioning of space - if you prefer to give it the name ether, then whats the harm so long as one does not impute to it properties that are misleading.
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