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We find a simple modification of the longitudinal mode in General Relativity which incorporates the idea of limiting curvature. In this case the singularities in contracting Friedmann and Kasner universes are avoided, and instead, the…

General Relativity and Quantum Cosmology · Physics 2017-04-18 Ali H. Chamseddine , Viatcheslav Mukhanov

The future finite-time singularities emerging in alternative gravity dark energy models are classified and studied in Jordan and Einstein frames. It is shown that such singularity may occur even in flat spacetime for the specific choice of…

High Energy Physics - Theory · Physics 2009-06-30 S. Capozziello , M. De Laurentis , S. Nojiri , S. D. Odintsov

Setting aside anthropic arguments, there is no reason why the universe should initially favour a net expanding phase rather than one experiencing a net contraction. However, a collapsing universe containing "normal" matter will end at a…

General Relativity and Quantum Cosmology · Physics 2019-11-20 Jean Alexandre , Katy Clough

We consider equations of the type: \[\partial_t \omega = \omega R(\omega),\] for general linear operators $R$ in any spatial dimension. We prove that such equations almost always exhibit finite-time singularities for smooth and localized…

Analysis of PDEs · Mathematics 2024-07-24 Roberta Bianchini , Tarek M. Elgindi

The existence of a positive and possibly varying Lambda-term opens a much wider field of possibilities for the future of our Universe than it was usually thought before. Definite predictions may be made for finite (though very large)…

Astrophysics · Physics 2008-11-26 A. A. Starobinsky

Future singularities arising in a family of models for the expanding Universe, characterized by sharing a convenient parametrization of the energy budget in terms of the deceleration parameter, are classified. Finite-time future…

General Relativity and Quantum Cosmology · Physics 2019-01-23 Emilio Elizalde , Martiros Khurshudyan , Shin'ichi Nojiri

We consider the late-time accelerated universe in the Friedmann-Robertson-Walker (FRW) spacetime with a nonzero curvature, and investigate cosmological models when the cosmic fluid is taken to be inhomogeneous and viscous (bulk viscous),…

General Relativity and Quantum Cosmology · Physics 2023-01-18 Iver Brevik , Alexander V. Timoshkin

We construct a FLRW universe considering an anisotropic scaling between space and time at extremely high and low energies only. In this context, Friedmann equations contain an additional term arising from spatial curvature which implements…

General Relativity and Quantum Cosmology · Physics 2018-12-26 Rodrigo Maier , Ivano Damião Soares

Both dark energy models and modified gravity theories could lead to cosmological evolutions different from either the recollapse into a Big Crunch or exponential de Sitter expansion. The newly arising singularities may represent true…

General Relativity and Quantum Cosmology · Physics 2015-06-15 László Á. Gergely , Zoltán Keresztes , Alexander Yu. Kamenshchik

Using the fluid representation, we formulate the conditions for the appearance of all four types finite-time future singularity in modified gravity in accelerating FRW universe. It stressed that number of standard quintessence/phantom DE…

High Energy Physics - Theory · Physics 2014-11-20 Shin'ichi Nojiri , Sergei D. Odintsov

We investigate the impact of singularities occurring at future times in solutions of the Friedmann equations expressed in conformal coordinates. We focus on the consequences of extending the time coordinate through the singularity for the…

General Physics · Physics 2011-02-18 Michael Ibison

In the case of unhindered gravitational collapse of matter cloud governed by the Lemaitre-Tolman-Bondi (LTB) spacetime, the end-state singularity is either locally visible, globally visible or completely hidden. We have a past-null…

General Relativity and Quantum Cosmology · Physics 2024-02-23 Ashok B. Joshi , Karim Mosani , Pankaj S. Joshi

We review recent work on the existence and nature of cosmological singularities that can be formed during the evolution of generic as well as specific cosmological spacetimes in general relativity. We first discuss necessary and sufficient…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Spiros Cotsakis

We consider here the genericity aspects of spacetime singularities that occur in cosmology and in gravitational collapse. The singularity theorems (that predict the occurrence of singularities in general relativity) allow the singularities…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Pankaj S. Joshi

Cosmological singularity theorems such as that of Hawking and Penrose assume local curvature conditions as well as global ones like the existence of a compact (achronal) slice. Here, we prove a new singularity theorem for chronological…

General Relativity and Quantum Cosmology · Physics 2019-08-29 Martin Lesourd

The present accelerated expansion of the universe has enriched the list of possible scenarios for its fate, singular or not. In this paper a unifying framework for analyzing such behaviors is proposed, based on generalized power and…

General Relativity and Quantum Cosmology · Physics 2019-03-07 L. Fernández-Jambrina

We demonstrate analytically and numerically the existence of geodesically complete singularities in quintessence and scalar tensor quintessence models with scalar field potential of the form $V(\phi)\sim \vert \phi\vert^n$ with $0<n<1$. In…

General Relativity and Quantum Cosmology · Physics 2017-10-18 A. Lymperis , L. Perivolaropoulos , S. Lola

In this comment we discuss big rip singularities occurring in typical phantom models by violation of the weak energy condition. After that, we compare them with future late-time singularities arising in models where the scale factor ends in…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Luis P. Chimento , Ruth Lazkoz

The Born-Infeld determinantal gravity has been recently proposed as a way to smooth the Big Bang singularity. This theory is formulated on the Weitzenbock space-time and the teleparallel representation is used instead of the standard…

General Relativity and Quantum Cosmology · Physics 2014-12-24 Mariam Bouhmadi-Lopez , Che-Yu Chen , Pisin Chen

We propose a model universe, in which the dimension of the space is a continuous variable, which can take any real positive number. The dynamics leads to a model in which the universe has no singularity. The difference between our model and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 M. Khorrami , R. Mansouri , M. Mohazzab , M. R. Ejtehadi