From: hal@finney.org
Date: Fri Nov 16 2001 - 12:10:40 MST
Damien B forwards:
> In his recent paper, "There Are No Limits To The Open Society"
> http://www.eeng.dcu.ie/~tkpw/tcr/volume-03/number-02/node1.html
> Tipler suggests that oscillative nudging by self aware observers will be
> able to take advantage of chaos theory to produce an Omega Point.
and adds:
> It's not that recent (1998), which was before the apparent acceleration of
> the cosmos was discovered. But it's a neat summary for newcomers. And see
> the technical appendix on why there *must* be an Omega Point (unitarity
> violation otherwise):
> http://www.eeng.dcu.ie/~tkpw/tcr/volume-03/number-02/node2.html
It's interesting now that the evidence seems strong for an open universe
to look at Tipler's argument for why the universe "must" be closed.
Basically it is so that black holes will not evaporate. If a black hole
evaporates, then information is lost. But a basic principle of QM is
that information is never lost, that in principle you can reconstruct
the past from the future. Thus black hole evaporation is a mystery
which seems to violate the laws of physics.
Now the conventional "explanation" is to simply say that we won't really
know what will happen until we have a good theory of quantum gravity,
which we don't have. But we have faith that with that theory in hand,
the mystery will be solved. Either black holes won't fully evaporate
(maybe some kind of kernel will be left behind that might be like a new
form of elementary particle but which holds all of the information that
fell into the black hole), or maybe the evaporation won't be random but
will somehow encode the information that fell in, or something else.
But Tipler's explanation is to say that black holes won't evaporate,
because the universe won't last long enough. In fact he says that the
universe MUST be of finite duration otherwise black holes would evaporate
which would violate our current understanding of the laws of physics.
I think in retrospect that this is not a very strong argument. If you
have a theory which would produce a contradiction if X happens, then you
can try to solve it by saying that X will never happen. But if there is
no a priori reason to believe that X can't happen, it looks pretty ad hoc.
Besides, there are some theories that mini black holes could have been
produced early in the universe which would have evaporated long ago, and
so Tipler has to deny that this could happen as well. It really doesn't
seem likely that the universe is engaged in a conspiracy to prevent black
holes from evaporating just because our present understanding of the laws
of nature produces contradictory predictions about what would happen then.
Hal
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