Re: Parallel Universes

From: scerir (scerir@libero.it)
Date: Wed Feb 12 2003 - 15:15:11 MST

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    [Rafal]
    > ### But I thought that as the entropy of the universe increases, the
    > amount of information needed to describe it also increases.

    I did not read Tegmark's paper. But, yes, if by entropy you mean a
    measure of irreversibility, then in MWI entropy increases for sure.

    We can see it in many ways. The branching structure, i.e., is,
    itself, irreversibility. Or, if you prefer, it is asymmetry
    between past and future. So we can also say that MWI broke its
    own and unique law: the time symmetrical Schroedinger equation.

    We can also put it in different terms. MWI supposes there is no
    communication between different worlds. Hence, imo, it supposes
    there is no 'interference' between different components of the
    wave function (at least after the splitting occurs). But having
    no 'interference' means a transition from an original 'pure' state
    to a 'mixture'. And we know, from a Von Neumann theorem, that in
    the change from a 'pure' state to a 'mixture' the entropy increases.
    (On the contrary the evolution described by the Schroedinger equation
    is unitary and the entropy is invariant).

    I do not know if MWI 'maximize', globally or locally, the entropy
    increase. And, perhaps, a 'comparative' calculation is not easy.
    Because there are many different theoretical models of measurement
    or 'collapse'.

    In any case it is possible, in general, to link the effective gain
    of information to the difference betwwen the initial entropy and
    the final one (Brillouin rule).

    s.

    "This approach has several variations which are called
    the 'relative state interpretation' and the 'many worlds
    interpretation'. None is satisfactory because they
    merely replace the arbitrariness of the collapse postulate
    by that of the no-communication hypothesis."
    - Asher Peres, 'Quantum THeory: Concepts and Methods',
    Kluwer Ac. Press, 1998, p. 374.



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