From: Hal Finney (hal@finney.org)
Date: Mon May 20 2002 - 19:21:51 MDT
Amara forwards:
> http://xxx.lanl.gov/abs/astro-ph/0205279
> The Ultimate Fate of Life in an Accelerating Universe
> Authors: Katherine Freese (Univ. of Michigan) William H. Kinney (Columbia
> Univ.)
>
> The ultimate fate of life in a universe with accelerated expansion
> is considered. Previous work by Krauss and Starkman showed that
> life cannot go on indefinitely in a universe dominated by a
> cosmological constant. In this paper we consider instead other
> models of acceleration (including quintessence and Cardassian
> expansion). We find that it is possible in these cosmologies for
> life to persist indefinitely. As an example we study potentials of
> the form $V \propto \phi^n$ and find the requirement $n < -2$.
It was disappointing that this paper did not reference the work of
Frank Tipler, who showed other kinds of limitations to the development
of life in an open universe. However the authors do reproduce some of
Tipler's reasoning:
"We note that a finite system, while it may be capable of an infinite
amount of computation, is only capable of storing a finite number of
memories. As long as the expansion of the universe is accelerating, any
system which is initially finite must remain so, since any additional
material with which to build new "memory" has redshifted beyond the
horizon and is therefore unavailable. We thus reach the apparently
inescapable conclusion that, while life itself may be immortal, any
individual is doomed to mortality."
I'm not sure that last sentence is quite right; life will be divided
into ever smaller, isolated "islands" separated by event horizons,
each one eventually forced into an infinite loop. So a more accurate
statement is that any individual can go on living forever, but he can
only have a finite number of experiences. And I think the same thing
will be true for life itself, in accelerating universe models.
Hal
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 09:14:14 MST