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Is Spacetime Moving ?

  1. Jun 14, 2004 #1
    Is Spacetime Moving ???

    If spacetime is considered as a substance, can motion be one of its attributes?

    Is spacetime the immovable substance like the aether? Is an aether the same as a static space? It's an experimental fact that both matter and antimatter move in spacetime.

    When space is merged with time, does this mean that space becomes dynamic (acquiring the attributes of force and acceleration)?
     
  2. jcsd
  3. Jun 15, 2004 #2
    This question could be interpreted as the continuation of an other one concerning the possible quantization of space time. Except the fact that we do no more speak about the quantization but of the structure of space time itself.
    As I use to say in my work: Relativity evacuates the aether but re-introduces a continuum which is an other type of rubber; a quite better one. To avoid misunderstanding, I do not shed tears because of the disappearance of the notion of aether and I don’t want to discuss about the Morley Michelson experiment.

    Relativity accords a big importance to the geometry and I am sure that we could begin a scientific description of the universe in considering the different configurations of its geometry. This said, each configuration appears to be compared with a state of the system and why could we not imagine that yes space time is a kind of substance whose motion is the change between a preceding state and the following one?
    With the Relativity we can accept the idea that the field (of gravitation) which is strongly connected with the curvature and consequently with the geometry (and the topology) of the space time “carries” a part of the energy present in the universe and the way around that the repartition of this energy determinates the geometry of the universe; one more time, if one agree with the idea that energy can move, space time, as carrier of a part of it, can move.

    I must say your question is a central one in my approach which is built in considering the vacuum as a stage with at least 3 inseparable types of random fluctuations (Electric Magnetic and Gravitational) interacting together in a strange play. Using again a beautiful picture as still used in an other thread, we usually just look at the player (the EM field) forgetting that whilst he is catching our attention with Shakespeare, his foot are supported by the stage (the geometry) which appears to be exactly so important as the text if one wants to see the play.

    The Law of the equivalence between the curvature tensor and the stress energy tensor connected to the duality wave – particle and the equivalence mass of a particle – energy of the particle let me guess that space time itself interpreted as geometric structure carries a part of the total energy in universe; and if one compares the volumes occupied by the vacuum to the volumes occupied by what we call the matter, one can guess too that most part of the energy should be “dark” (I mean carried by the structure).

    Concerning the notion of time which is certainly strongly connected with the notion of entropy why not imagine that time could be a function of position and speed [e.g. for one spatial dimension: t = f[x, v(x)] leading to a definition of the duration dt = ("d"f/"d"x). dx + ["d"f/"d"v(x)]. dv(x) / "d" means here partial derivation] which would be amazingly in harmony with some recent works made by psychologists concerning the perception of the duration by human people; see French edition of American Scientific; June 2004]?
     
  4. Jun 15, 2004 #3
    http://www.ncsu.edu/felder-public/kenny/papers/gr2.html


     
  5. Jun 15, 2004 #4
    I am working on the possible dynamic of this "rubber." Wha I come up with is two distinct topologies. These are not equivalent iff the dynamic exists. If spacetime is static then supersymmetry is possible.

    Thanks, Russell for the papers by Felder. I am still reading it. He describes his 3rd way of understanding general relativity by the use of arbitrary coordinate systems. But in my study of spacetime, I am trying to avoid the use of any coordinate system. Do you think we can still describe local motion of spacetime without the use of a coordinate system?
     
  6. Jun 18, 2004 #5
    Points in manifolds are covered by coordinate patches, but tensors give coordinate independence. A symmetry.

    Tensors:

    http://www.grc.nasa.gov/WWW/K-12/Numbers/Math/documents/Tensors_TM2002211716.pdf
     
  7. Jun 18, 2004 #6
    Again, thanks for this paper by NASA on tensors. I always had a fear of tensors but maybe after reading this paper, I am hoping to be rid of this fear once sense for all.
     
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