From: Anders Sandberg (asa@nada.kth.se)
Date: Mon May 05 2003 - 10:41:11 MDT
Here is an intriguing paper, similar to some of stuff in the paper of Nick
Bostrom and Milan M. Cirkovic (http://arxiv.org/abs/gr-qc/9906042):
http://arxiv.org/abs/hep-th/0208013
(some comments at http://www.nature.com/nsu/020812/020812-2.html)
Disturbing Implications of a Cosmological Constant
Authors: Lisa Dyson, Matthew Kleban, Leonard Susskind
In this paper we consider the implications of a cosmological
constant for the evolution of the universe, under a set of
assumptions motivated by the holographic and horizon complementarity
principles. We discuss the ``causal patch" description of spacetime
required by this framework, and present some simple examples of
cosmologies described this way. We argue that these assumptions
inevitably lead to very deep paradoxes, which seem to require major
revisions of our usual assumptions.
The image of the universe they arrive at undergoes inflation, expansion into
a lifebearing state, then gradual heath death and being separated into
nothingness by advancing horizons. Then nothing happens for titanic
timescales, until random fluctuations cause new inflation or the ready-made
assembly of an universe. And so on. However, they calculate that most
universes that fit the anthropic principle (contain liveable worlds where
humans can exist) will not be due to a consistent expansion from an
inflation state, but due to a "miraculous" random assembly (their example is
an universe with our element abundancies and same appearance, but 10K
background temperature, which is inconsistent with primordial
nucleosynthesis). These miraculous universes are far more likely than the
plausible ones, so it is surprising that we see a physics that makes sense.
Not even creationism helps, as they analyse in the paper, since a deliberate
creation is only the start of a trajectory through this vast phase space.
One has to drop some rather deep assumptions to get things to work.
Sounds like it is in Nick's territory :-)
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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