RE: Time

From: Brian Harper (harper.10@osu.edu)
Date: Tue Sep 09 2003 - 10:30:53 EDT

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    At 08:13 PM 9/8/2003 -0500, Glenn Morton wrote:
    Hi Brian,

    >-----Original Message-----
    >From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu]On
    >Behalf Of Brian Harper
    >Sent: Monday, September 08, 2003 1:50 PM

    >Look at it this way, if you are going to select then
    >there must be something to select from. If all the
    >universes have the same laws etc then there is
    >nothing to select from.
    >
    >Everett does not satisfy these conditions.

    One needs a correction here. Some versions of the many-world's hypothesis
    actually do have selection:
            "Natural selection of 'favored' universes seems the stuff of science
    fiction. However the American cosmologist Lee Smolin conjectures that the
    multiverse could display the effects of heredity and selection. When a black
    hole collapses, he speculates that another universe sprouts from its
    interior, creating a new expanse of space and time disjoint from our won.
    Small universes, in which there was too little space or time to form many
    black holes, would not leave many progeny. Nor, he argues, would even a
    large universe if its physics prohibited stars from ever terminating as
    black holes."
            "Smolin then adds a new twist-the physical laws governing the daughter
    universe many differ from those in its parent, but only slightly. Since the
    number of progeny a universe has depends on the laws prevailing within it,
    there is a selection pressure. Many generations, or many iterations, would
    lead to a 'takeover' by the universes that generate the most numerous
    progeny. These would be the ones governed by laws that allowed the largest
    number of black holes to form." Martin Rees, Before the Beginning, (Reading,
    Mass: Helix Books, 1997), p. 249-250


    This is rather speculative, to say the least :).

    A couple of clarifications. First, I was responding to
    the comment by Blake:

    "They all as far as I am aware explain the apparent fine tuning
    of the universe by positing that this is one of many universes."

    I was pointing at that not all explain fine tuning. I was not
    arguing that none do. There has been a lot of talk about
    Everett. I cannot see how that MWH explains fine-tuning.

    Second, anthropic selection and natural selection are
    comletely different animals. One does not have to get
    as creative as Smolin does above to get anthropic selection.

    For example, a rapid inflation causing the universe to
    separate into causally disconnected "domains" followed
    by stochastic symmetry breaking leading to different
    laws and physical constants in the different domains.
    This is enough to argue anthropic selection provided
    there are a vast number of these domains.

    Let me review again what anthropic selection is. Suppose
    we have this vast number of domains described above and
    we ask: "Why is it that I happen to find myself in this
    universe that is finely tuned for life, isn't this special?".
    And the answer: "Not really, you can't very well be in one of the
    others".

    Also, it is important to point out that anthropic selection
    does not itself actually explain anything except for why
    you are in the finely tuned universe as opposed to one
    of those where life is impossible. The explanation is,
    of course, trivial. The real work in explanation is the
    theory or evidence or whatever for the multiworlds.



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