From: Hal Finney (hal@finney.org)
Date: Thu Mar 06 2003 - 11:26:11 MST
Robert Bradbury points to:
http://arxiv.org/abs/astro-ph/0302506
Like the old joke goes: Phew! I thought you said 22 MILLION years!
Not very funny for Extropians though.
Basically this paper examines what would happen if the "dark energy"
had slightly more negative pressure than currently imagined, and it shows
that eventually the negative pressure becomes overwhelming, tearing apart
every form of structure. Furthermore, amazingly enough, rather plausible
values of the pressure parameter imply that we will switch to that "rip"
epoch relatively soon. The universe is presently about 13 GYr (billion
years) old, and the "Big Rip" is estimated at 35 GYr.
The universe's history can be divided into epochs where various physical
effects dominate. We are presently in what you might call the "galactic
epoch", where gravitationally bound structures like galaxies and stellar
systems are the main structures. The authors argue that this epoch is
unique in the whole history of the universe (supposing the Big Rip theory
is true) in that it is the only one where nonlinear, complex structures
can form. Earlier and later in history, everything is very uniform.
The implication might be that only now could life form.
So we have a universe where life evolves and then more or less immediately
(on the cosmic scale) gets destroyed. And that's actually what has
always been expected, by anthropic considerations. It has been a bit
of a mystery why the universe has seemed to be so much bigger and more
elaborate than is necessary for life to evolve. "Anthropicists" would
predict that the universe is as complex as necessary for life, but no
more so. Well, this theory seems to be one of the first ones where the
universe meets that description, at least in terms of its temporal extent.
It's possible that this "ripping" force could be a source of energy as we
approach the final days, giving us the ability to do more computations
than would otherwise be possible. However I don't think we can get an
infinite number of computations as in Frank Tipler's Omega Point theory
which relied on a Big Crunch. The problem is that we are constantly
losing matter as it is ripped away by this infinitely powerful force.
So even though we may gain energy, we lose matter and so will be able to
do less and less with what we have. Eventually all structure is lost.
All in all this is not a hopeful model.
Hal
This archive was generated by hypermail 2.1.5 : Thu Mar 06 2003 - 11:34:31 MST