X-Message-Number: 29062
Date: Sat, 3 Feb 2007 23:25:34 -0500
From: Jonano <>
Subject: Endless Universe Made Possible By New Model

Endless Universe Made Possible By New Model

Science Daily   A new cosmological model demonstrates the universe can
endlessly expand and contract, providing a rival to Big Bang theories
and solving a thorny modern physics problem, according to University
of North Carolina at Chapel Hill physicists.Ads by Google Advertise on
this site

The cyclic model proposed by Dr. Paul Frampton, Louis J. Rubin Jr.
distinguished professor of physics in UNC's College of Arts &
Sciences, and co-author Lauris Baum, a UNC graduate student in
physics, has four key parts: expansion, turnaround, contraction and
bounce.

During expansion, dark energy -- the unknown force causing the
universe to expand at an accelerating rate -- pushes and pushes until
all matter fragments into patches so far apart that nothing can bridge
the gaps. Everything from black holes to atoms disintegrates. This
point, just a fraction of a second before the end of time, is the
turnaround.

At the turnaround, each fragmented patch collapses and contracts
individually instead of pulling back together in a reversal of the Big
Bang. The patches become an infinite number of independent universes
that contract and then bounce outward again, reinflating in a manner
similar to the Big Bang. One patch becomes our universe.

"This cycle happens an infinite number of times, thus eliminating any
start or end of time," Frampton said. "There is no Big Bang."

An article describing the model is available on the arXiv.org e-print
archive and will appear in an upcoming issue of Physical Review
Letters. The work was supported in part by a U.S. Department of Energy
grant.

Cosmologists first offered an oscillating universe model, with no
beginning or end, as a Big Bang alternative in the 1930s. The idea was
abandoned because the oscillations could not be reconciled with the
rules of physics, including the second law of thermodynamics, Frampton
said.

The second law says entropy (a measure of disorder) can't be
destroyed. But if entropy increases from one oscillation to the next,
the universe becomes larger with each cycle. "The universe would grow
like a runaway snowball," Frampton said. Each oscillation will also
become successively longer. "Extrapolating backwards in time, this
implies that the oscillations before our present one were shorter and
shorter. This leads inevitably to a Big Bang," he said.

Frampton and Baum circumvent the Big Bang by postulating that, at the
turnaround, any remaining entropy is in patches too remote for
interaction. Having each "causal patch" become a separate universe
allows each universe to contract essentially empty of matter and
entropy. "The presence of any matter creates insuperable difficulties
with contraction," Frampton said. "The idea of coming back empty is
the most important ingredient of this new cyclic model."

This concept jolted Frampton when it popped into his head last October.

"I suddenly saw there was a new way of solving this seemingly
impossible problem," he said. "I was sitting with my feet on my desk,
half-asleep and puzzled, and I almost fell out of my chair when I
realized there was a much, much simpler possibility."

Also key to Frampton and Baum's model is an assumption about dark
energy's equation of state -- the mathematical description of its
pressure and density. Frampton and Baum assume dark energy's equation
of state is always less than -1. This distinguishes their work from a
similar cyclic model proposed in 2002 by physicists Paul Steinhardt
and Neil Turok, who assumed the equation of state is never less than
-1.

A negative equation of state gives Frampton and Baum a way to stop the
universe from blowing itself apart irreversibly, an end physicists
call the "Big Rip." The pair found that in their model, the density of
dark energy becomes equal to the density of the universe and expansion
stops just before the Big Rip.

New satellites currently under construction, such as the European
Space Agency's Planck satellite, could gather enough information to
determine dark energy's equation of state, Frampton said.

http://www.sciencedaily.com/releases/2007/01/070130091159.htm

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