Bouncing branes

Prodanov, Emil M.

doi:10.1016/s0370-2693(02)01337-0

Cited by 5 publications

(4 citation statements)

References 17 publications

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“…The same picture can be found in [85] where the non-minimal coupling of gravity to fermions is allowed. Besides the model presented here, non-singular scenarios have been reported in the literature within various models such as f (R) theories of gravity in the Palatini [86] and metric [87] formalisms, nonsingular cosmological settings in the presence of a spinning fluid in the context of EC theory [88], bouncing scenarios in brane models [89][90][91][92][93], and modified Gauss-Bonnet gravity [94] (see also [95] for recent review). While the spacetime singularities could generically occur as the end-product of a continual gravitational collapse, it is widely believed that in the very final stages of the collapse where the scales are comparable to the Planck length and extreme gravity regions are dominant, quantum corrections could generate a strong negative pressure in the interior of the cloud to finally resolve the classical singularity [96][97][98][99][100][101][102][103][104][105][106][107].…”

Section: Discussionmentioning

confidence: 99%

Collapse and dispersal of a homogeneous spin fluid in Einstein–Cartan theory

2015

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In the present work, we revisit the process of gravitational collapse of a spherically symmetric homogeneous dust fluid which is described by the OppenheimerSnyder (OS) model (Oppenheimer and Snyder in Phys Rev D 56:455, 1939). We show that such a scenario would not end in a spacetime singularity when the spin degrees of freedom of fermionic particles within the collapsing cloud are taken into account. To this purpose, we take the matter content of the stellar object as a homogeneous Weyssenhoff fluid. Employing the homogeneous and isotropic FLRW metric for the interior spacetime setup, it is shown that the spin of matter, in the context of a negative pressure, acts against the pull of gravity and decelerates the dynamical evolution of the collapse in its later stages. Our results show a picture of gravitational collapse in which the collapse process halts at a finite radius, whose value depends on the initial configuration. We thus show that the spacetime singularity that occurs in the OS model is replaced by a non-singular bounce beyond which the collapsing cloud re-expands to infinity. Depending on the model parameters, one can find a minimum value for the boundary of the collapsing cloud or correspondingly a threshold value for the mass content below which the horizon formation can be avoided. Our results are supported by a thorough numerical analysis.

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Section: Discussionmentioning

confidence: 99%

Collapse and dispersal of a homogeneous spin fluid in Einstein–Cartan theory

2015

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“…It is worth mentioning that, besides the model presented here, non-singular scenarios have been reported within models of f (R) theories of gravity in Palatini [171] and metric [172] formalisms, generalized teleparallel theories of gravity [173][174][175][176], bouncing in brane models [177][178][179][180][181] and modified Gauss-Bonnet gravity [182] (see also [183] for recent review). In [184], it is shown that a quantized neutral scalar field minimally coupled to classical gravitational field may avoid the singularity.…”

Section: Discussionmentioning

confidence: 74%

Einstein–Cartan gravitational collapse of a homogeneous Weyssenhoff fluid

et al. 2014

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We consider the gravitational collapse of a spherically symmetric homogeneous matter distribution consisting of a Weyssenhoff fluid in the presence of a negative cosmological constant. Our aim is to investigate the effects of torsion and spin averaged terms on the final outcome of the collapse. For a specific interior space-time setup, namely the homogeneous and isotropic FLRW metric, we obtain two classes of solutions to the field equations where depending on the relation between spin source parameters, (i) the collapse procedure culminates in a space-time singularity or (ii) it is replaced by a non-singular bounce. We show that, under certain conditions, for a specific subset of the former solutions, the formation of trapped surfaces is prevented and thus the resulted singularity could be naked. The curvature singularity that forms could be gravitationally strong in the sense of Tipler. Our numerical analysis for the latter solutions shows that the collapsing dynamical process experiences four phases, so that two of which occur at the pre-bounce and the other two at post-bounce regimes. We further observe that there can be found a minimum radius for the apparent horizon curve, such that the main outcome of which is that there exists an upper bound for the size of the collapsing body, below which no horizon forms throughout the whole scenario.

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Section: Introductionmentioning

confidence: 99%

“…Brane-world models permit a new approach to these difficulties, since they appear to allow the possibility that brane-bound observers might experience a bouncing universe, while embedded within a stable higher-dimensional geometry [3]- [16]. Reference [8] pointed out such an apparent example, consisting of a four-dimensional cosmology based on a brane world embedded in a five-dimensional Reissner-Nordström background 6 .…”

Section: Introductionmentioning

confidence: 99%

On bouncing brane worlds,S-branes and branonium cosmology

Burgess

Quevedo

Rabadán

et al. 2004

J. Cosmol. Astropart. Phys.

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We present several higher-dimensional spacetimes for which observers living on 3-branes experience an induced metric which bounces. The classes of examples include boundary branes on generalised S-brane backgrounds and probe branes in D-brane/anti D-brane systems. The bounces we consider normally would be expected to require an energy density which violates the weak energy condition, and for our co-dimension one examples this is attributable to bulk curvature terms in the effective Friedmann equation. We examine the features of the acceleration which provides the bounce, including in some cases the existence of positive acceleration without event horizons, and we give a geometrical interpretation for it. We discuss the stability of the solutions from the point of view of both the brane and the bulk. Some of our examples appear to be stable from the bulk point of view, suggesting the possible existence of stable bouncing cosmologies within the brane-world framework.

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Bouncing branes

Abstract: Two classical scalar fields are minimally coupled to gravity in the Kachru-Shulz-Silverstein scenario with a rolling fifth radius. A Tolman wormhole solution is found for a IR×S 3 brane with Lorentz metric and for a IR × AdS 3 brane with positive definite metric.

Cited by 5 publications

References 17 publications

Collapse and dispersal of a homogeneous spin fluid in Einstein–Cartan theory

Collapse and dispersal of a homogeneous spin fluid in Einstein–Cartan theory

Einstein–Cartan gravitational collapse of a homogeneous Weyssenhoff fluid

On bouncing brane worlds,S-branes and branonium cosmology

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