New isotropic and anisotropic sudden singularities

Barrow, John D.; Tsagas, Christos G.

doi:10.1088/0264-9381/22/9/006

Cited by 160 publications

(120 citation statements)

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“…However, over the last few years, more singularities have been considered such as big rips, sudden singularities, and there has even been a renewed interest in non-singular events such as bounces and turnarounds [2,3,4,5,6].…”

Section: Introductionmentioning

confidence: 99%

Cosmological milestones and energy conditions

Cattoën¹,

Visser²

2007

J. Phys.: Conf. Ser.

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Abstract. Until recently, the physically relevant singularities occurring in FRW cosmologies had traditionally been thought to be limited to the big bang, and possibly a big crunch. However, over the last few years, the zoo of cosmological singularities considered in the literature has become considerably more extensive, with big rips and sudden singularities added to the mix, as well as renewed interest in non-singular cosmological events such as bounces and turnarounds. In this talk, we present an extensive catalogue of such cosmological milestones, both at the kinematical and dynamical level. First, using generalized power series, purely kinematical definitions of these cosmological events are provided in terms of the behaviour of the scale factor a(t). The notion of a scale-factor singularity is defined, and its relation to curvature singularities (polynomial and differential) is explored. Second, dynamical information is extracted by using the Friedmann equations (without assuming even the existence of any equation of state) to place constraints on whether or not the classical energy conditions are satisfied at the cosmological milestones. Since the classification is extremely general, and modulo certain technical assumptions complete, the corresponding results are to a high degree model-independent.

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Section: Introductionmentioning

confidence: 99%

Cosmological milestones and energy conditions

Cattoën¹,

Visser²

2007

J. Phys.: Conf. Ser.

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“…Along this perspective, recently Barrow has discussed the interesting case of "sudden" singularities that may arise in expanding FRW Universes even if the dominant energy condition is not violated [19,20]. The possibility of anisotropic sudden singularities has been also discussed recently by Barrow and Tsagas [21]. We will briefly comment about the possible relevance of the considerations developed here in the context of the physics of sudden singularity.…”

Section: Introductionmentioning

confidence: 66%

Gradient expansion(s) and dark energy

Giovannini

2005

J. Cosmol. Astropart. Phys.

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Motivated by recent claims stating that the acceleration of the present Universe is due to fluctuations with wavelength larger than the Hubble radius, we present a general analysis of various perturbative solutions of fully inhomogeneous Einstein equations supplemented by a perfect fluid. The equivalence of formally different gradient expansions is demonstrated. If the barotropic index vanishes, the deceleration parameter is always positive semi-definite.

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“…• Generalized sudden future singularities: For t → t s a → a s , ρ → ρ s , | p| → p s , and the derivatives of the pressure may diverge [20]. For this singularity, all the energy conditions are satisfied.…”

Section: Future Singularitiesmentioning

confidence: 99%