Quantum effects, soft singularities and the fate of the Universe in a Braneworld cosmology

Tretyakov, Petr ; Toporensky, Aleksey ; Shtanov, Yuri ; Sahni, Varun (2006) Quantum effects, soft singularities and the fate of the Universe in a Braneworld cosmology Classical and Quantum Gravity, 23 (10). pp. 3259-3274. ISSN 0264-9381

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Official URL: http://iopscience.iop.org/0264-9381/23/10/001

Related URL: http://dx.doi.org/10.1088/0264-9381/23/10/001

Abstract

We examine a class of braneworld models in which the expanding universe encounters a 'quiescent' future singularity. At a quiescent singularity, the energy density and pressure of the cosmic fluid as well as the Hubble parameter remain finite, while all derivatives of the Hubble parameter diverge (i.e.,H·, H··, etc →∞). Since the Kretschmann invariant diverges (RiklmRiklm → ∞) at the singularity, one expects quantum effects to play an important role as the quiescent singularity is approached. We explore the effects of vacuum polarization due to massless conformally coupled fields near the singularity and show that these can either cause the universe to recollapse or, else, lead to a softer singularity at which Η, H,H·, and H·· remain finite, while H··· and higher derivatives of the Hubble parameter diverge. An important aspect of the quiescent singularity is that it is encountered in regions of low density, which has obvious implications for a universe consisting of a cosmic web of high-and low-density regions-superclusters and voids. In addition to vacuum polarization, the effects of quantum particle production of non-conformal fields are also likely to be important. A preliminary examination shows that intense particle production can lead to an accelerating universe whose Hubble parameter shows oscillations about a constant value.

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics.
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Deposited On:04 Jul 2011 11:13
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