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Does dark energy bring back the cyclical Universe idea?
Socrates II — (archived)

Title: Dark Energy and the Return of the Phoenix Universe

Authors: Jean-Luc Lehners and Paul J. Steinhardt

Categories: hep-th astro-ph gr-qc

Comments: 5 pages, 3 figures

In cyclic universe models based on a single scalar field (e.g., the radion determining the distance between branes in M-theory), virtually the entire universe makes it through the ekpyrotic smoothing and flattening phase, bounces, and enters a new epoch of expansion and cooling.

This stable evolution cannot occur, however, if scale-invariant curvature perturbations are produced by the entropic mechanism because it requires two scalar fields (e.g., the radion and the Calabi-Yau dilaton) evolving along an unstable classical trajectory.

In fact, we show here that an overwhelming fraction of the universe fails to make it through the ekpyrotic phase; nevertheless, a sufficient volume survives and cycling continues forever provided the dark energy phase of the cycle lasts long enough, of order a trillion years.

Two consequences are a new role for dark energy and a global structure of the universe radically different from that of eternal inflation.

http://arxiv.org/abs/0812.3388 , 162kb

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