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Ellis on an evolving block universe (gr-qc/0605049)

  1. May 9, 2006 #1

    robphy

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    Ellis on an "evolving block universe" (gr-qc/0605049)

    Here's an interesting article I just browsed through:

    gr-qc/0605049

    Physics in the Real Universe: Time and Spacetime
    George F. R. Ellis

    The Block Universe idea, representing spacetime as a fixed whole, suggests the flow of time is an illusion: the entire universe just is, with no special meaning attached to the present time. This view is however based on time-reversible microphysical laws and does not represent macro-physical behaviour and the development of emergent complex systems, including life, which do indeed exist in the real universe. When these are taken into account, the unchanging block universe view of spacetime is best replaced by an evolving block universe which extends as time evolves, with the potential of the future continually becoming the certainty of the past. However this time evolution is not related to any preferred surfaces in spacetime; rather it is associated with the evolution of proper time along families of world lines

    http://arxiv.org/abs/gr-qc/0605049

    (This, of course, is the Ellis of "Hawking/Ellis" and "Ellis/Williams".)
     
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  3. May 9, 2006 #2

    George Jones

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    A few words of warning - I think this is an attempt by Ellis, a Templeton Prize winner, to give a scientific basis to some of his spiritual and philosophical views.

    For examplle from section 4.1 of this paper: "The block universe picture has sometimes been used as an argument against free will (Brennan 2006); but the physics implied in that picture is not sufficient to even begin contemplating issues of free will. This description does not provide a valid context for that discussion. The more complex view presented here provides an adequate context for that discussion, and does not give evidence against the existence of free will; on the contrary, it is broadly congruent with such existence."

    Writing elsewhere, Ellis says "In order for ethical choices to be meaningful, it is crucial that the human mind has free will."

    I, too, think that this looks like an interesting article.

    Regards,
    George
     
  4. May 10, 2006 #3

    Garth

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    Is not there a basic philosophical error in assuming that simply drawing a space-time diagram, which automatically entails observing a block universe, itself proves that the future is predetermined and we have no free will?

    Such a timeless perspective may be 'God's' POV but it is not ours, nor any other observer within space-time, for whom the 'passing of time' is not an illusion but the most basic fact of conscious awareness.

    The question of the relativity of simultaneity may be a problem for God but never for us, because we can never obtain information from events that lie in our future light-cone only from our past light-cone.

    Garth
     
  5. May 10, 2006 #4
    *
    The question of the relativity of simultaneity may be a problem for God but never for us, because we can never obtain information from events that lie in our future light-cone only from our past light-cone.
    *

    Euh, that is even so in classical relativity: we (humans on earth) need to extrapolate our information to make well educated guesses about the future. The debate free will versus determinism is useless, there is no point in speaking about issues which cannot - even in principle - be resolved.
     
  6. May 10, 2006 #5

    robphy

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    I guess a similar concern could be said of a well-posed initial value problem (differential equations with boundary conditions).

    A space-time diagram and an IVP are merely models of certain aspects of the physics.
     
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