# Re: Tipler's Conjectures

From: Amara Graps (Amara.Graps@mpi-hd.mpg.de)
Date: Sun May 06 2001 - 08:43:49 MDT

Amara

http://xxx.uni-augsburg.de/abs/gr-qc/0105002
General Relativity and Quantum Cosmology, abstract
gr-qc/0105002

From: "Marcelo J. Reboucas" <reboucas@cbpf.br>
Date: Wed, 2 May 2001 00:49:39 GMT (147kb)

Detectability of Cosmic Topology in Almost Flat Universes

Authors: G.I. Gomero, M.J. Reboucas, R. Tavakol
Comments: 18 pages, 3 figures, LaTeX2e

Recent observations suggest that the ratio of the total density to
the critical density of the universe, $\Omega_0$, is likely to be
very close to one, with a significant proportion of this energy
being in the form of a dark component with negative pressure.
Motivated by this result, we study the question of observational
detection of possible non-trivial topologies in universes with
$\Omega_0 \sim 1$, which include a cosmological constant. Using a
number of indicators we find that as $\Omega_0 \to 1$, increasing
families of possible topologies become either undetectable or can
be excluded observationally. Furthermore, given a non-zero lower
bound on $|\Omega_0 - 1|$, we can rule out families of topologies
as possible candidates for the shape of our universe. We
demonstrate these findings concretely by considering families of
topologies and employing bounds on cosmological parameters from
recent observations. We find that given the present bounds on
cosmological parameters, there are families of both hyperbolic and
spherical manifolds that remain undetectable and families that can
be excluded as the shape of our universe. These results are of
importance in future search strategies for the detection of the
shape of our universe, given that there are an infinite number of
theoretically possible topologies and that the future observations
are expected to put a non-zero lower bound on $|\Omega_0 - 1|$
which is more accurate and closer to zero.

Paper: Source (147kb), PostScript, or Other formats

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Amara Graps               | Max-Planck-Institut fuer Kernphysik
Interplanetary Dust Group | Saupfercheckweg 1
+49-6221-516-543          | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://www.mpi-hd.mpg.de/dustgroup/~graps
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