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I SR and the passage of time

  1. Oct 23, 2015 #1
    Does SR enable the passage of time.
    Rietdjik(1967)-Putnam(1968)-Penrose-Maxwell and others, claim that SR proves Eternalism.
    That is; the world is an eternal (a-temporal) 4-dimensional spacetime manifold in which all events exist and the notion of a moving Now (a global hyper-surface of simultaneous "now events") moving in to the future is a psychological illusion.
    Is that physically substantial or just philosophically?
  2. jcsd
  3. Oct 23, 2015 #2

    Simon Bridge

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    Welcome to PF;
    What do you mean by enable"?

    In physics time passes from the POV of an observer ... i.e. time depends on your point of view, just like space does.
    SR formalism takes time, explicitly, as another dimension of space - so all points on the time axis exist alongside each other in the same way as all points on the three space axes. SR is only as model though - it cannot prove or disprove anything.
    Everything apart from that is philosophy.
  4. Oct 23, 2015 #3


    Staff: Mentor

    The key to answering that question is whether or not, in principle, there is an experiment which could be performed that could answer the question. Since there is no such experiment, the question is philosophical, not scientific.
  5. Oct 24, 2015 #4
    I am sorry Simon but I am afraid you are wrong on both accounts;
    SR formalism specifically does not take time as another dimension of space. Minkowski, Einstein's math teacher and colleague, and the developer of the Geometry of Numbers and of the concept "Spacetime" , devised the first geometrical formulation of SR. You see it in every popular presentation of SR and in many physics textbooks. It has a light-cone structure that is an intrinsic part of SR geometry. This structure encodes (causal) information about the worldline of a particle (or a reference frame) moving in spacetime. The temporal axis is strictly not as the spatial axis ; it is perpendicular to it and represents a different kind of dimension.
    To say that SR (a formidable scientific achievement) is only a model, represents a very shallow understanding of science and of it's positivist limitations (theoretical, operational, semantic, pragmatic and so on). SR is proved every single day through SR corrections of time-dilation in GPS satellites. What more (or kind of) proof are you looking for Simon?
    And considering your demarcation of physics vs philosophy , whether the world is 3 or 4D i.e., whether all events exist (and the passage of time is an illusion) is a very substantial physical question. At least it was so for Einstein, Lorentz, Minkowski, Weyl, and the others i've mentioned which are mainly philosophers like Putnam (which does not make them less capable than physicists) .
    I hope this helps clarify my question.
  6. Oct 24, 2015 #5
    Dale I agree completely.
    But... Ed Witten and Frank Wilczek both claim that their quantum gravity (string) theories will pretty soon be available for empirical testing .
    This could be our observation of actual fundamental space. This is because space is an emergent phenomena in string theory. I am saying that the debate about space and time is not settled or trivial , and that it needs serious analysis which is not strictly philosophical but reaches the core of mathematical theoretical physics.
  7. Oct 24, 2015 #6


    Staff: Mentor

    And when that happens, if that happens, then it would become a scientific question (making the rather large assumption that the question would be answerable by tests of string theory). Until that point it remains philosophical.

    Thread closed.
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