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In this paper we build on our previous work and the work of Peter Lynds within a Bohmian framework to consider the intervallic structure of thermodynamic reversibility as well as presenting new considerations for the measurement of…

General Physics · Physics 2011-05-10 Maurice Passman , Philip V. Fellman , Jonathan Vos Post

We continue our analysis of a quantum cosmology model describing a flat Friedmann--Lema\^itre--Robertson--Walker universe filled with a (free) massless scalar field and an arbitrary perfect fluid. For positive energy density in the scalar…

General Relativity and Quantum Cosmology · Physics 2022-04-08 Steffen Gielen , Lucía Menéndez-Pidal

In hep-th/0506040 we discussed a classically constrained model of gravity. This theory contains known solutions of General Relativity (GR), and admits solutions that are absent in GR. Here we study cosmological implications of some of these…

High Energy Physics - Theory · Physics 2008-11-26 Gregory Gabadadze , Yanwen Shang

We describe a numerical approach to address the BKL conjecture that the generic cosmological singularity is locally Mixmaster-like. We consider application of a symplectic PDE solver to three models of increasing complexity--spatially…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Beverly K. Berger

Purely time dependent solutions in four-dimensional Einstein-Cartan-Kalb-Ramond (ECKR) theory of gravity are shown not to be possible leading to a trivial vanishing of all Kalb-Ramond fields. This result seems to contradict previously…

General Relativity and Quantum Cosmology · Physics 2007-05-23 L. C. Garcia de Andrade

The paper establishes the result that solutions of the type described in the title of the article are only those that have been already presented in the literature. The procedure adopted in the paper is somewhat novel - while the usual…

General Relativity and Quantum Cosmology · Physics 2009-11-07 A. K. Raychaudhuri

In this work, we study the issue of the past and future cosmological singularities in the context of the fourth-order conformal Weyl gravity. In particular, we investigate the emergent universe scenario proposed by Ellis {\it et al}, and…

General Relativity and Quantum Cosmology · Physics 2020-06-02 Yaghoub Heydarzade

We propose a new cosmological scenario which resolves the conventional initial singularity problem. The space-time geometry has an unconventional time-like singularity on a lower dimensional hypersurface, with localized energy density. The…

High Energy Physics - Theory · Physics 2009-11-07 L. Cornalba , M. S. Costa , C. Kounnas

Time-independent non-linear Schr\"{o}dinger-type (NLS) formulation of FRW cosmology with canonical scalar field are considered in case of two barotropic fluids. We derived Friedmann formulation variables in terms of NLS variables. Seven…

General Relativity and Quantum Cosmology · Physics 2021-07-19 Chonticha Kritpetch , Jarunee Sanongkhun , Pichet Vanichchapongjaroen , Burin Gumjudpai

We consider new cosmological solutions with a collapsing, an intermediate and an expanding phase. The boundary between the expanding (collapsing) phase and the intermediate phase is seen by comoving observers as a cosmological past (future)…

High Energy Physics - Theory · Physics 2009-11-07 L. Cornalba , Miguel S. Costa

A short review on spherically symmetric static regular black holes and spherically symmetric non singular cosmological space-time is presented. Several models of regular black holes, including new ones, are considered. First, a large class…

General Relativity and Quantum Cosmology · Physics 2022-11-24 Lorenzo Sebastiani , Sergio Zerbini

A new approach is suggested which allows to describe phenomenologically arbitrary topologies of the Universe. It consists in a generalizaton of third quantization. This quantization is carried out for the case of asymptotic closeness to a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 A. A. Kirillov

Self-similar, spherically symmetric cosmological models with a perfect fluid and a scalar field with an exponential potential are investigated. New variables are defined which lead to a compact state space, and dynamical systems methods are…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Alan Coley , Martin Goliath

We study how a cosmological bounce with a Type IV singularity at the bouncing point, can be generated by a classical vacuum $F(G)$ gravity. We focus our investigation on the behavior of the vacuum $F(G)$ theory near the Type IV singular…

General Relativity and Quantum Cosmology · Physics 2015-12-23 V. K. Oikonomou

New exact vacuum solutions with various singularities in the plane-symmetric spacetime are shown, and they are applied to the analysis of inhomogeneous cosmological models and colliding gravitational waves. One of the singularities can be…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Kenji Tomita

The gravitational collapse of spherical, barotropic perfect fluids is analyzed here. For the first time, the final state of these systems is studied without resorting to simplifying assumptions - such as self-similarity - using a new…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Roberto Giambo' , Fabio Giannoni , Giulio Magli , Paolo Piccione

We study the existence of new features in lumplike solutions in models of a real scalar field in two dimensional flat spacetime. We present new models and field configurations that exhibit a non standard decay, shrinking or stretching the…

High Energy Physics - Theory · Physics 2019-01-29 M. A. Marques

We study in this article a class of homogeneous, but anisotropic cosmological models in which shear viscosity is included. Within the matter content we consider a component (the quintessence component) determined by the barotropic equations…

Astrophysics · Physics 2009-10-31 Mauricio Cataldo , Sergio del Campo

I argue that there are no physical singularities in space-time. Singular space-time models do not belong to the ontology of the world, because of a simple reason: they are concepts, defective solutions of Einstein's field equations. I…

General Physics · Physics 2012-10-10 Gustavo E. Romero

We investigate the effect of deviations from general relativity on approach to the initial singularity by finding exact cosmological solutions to a wide class of fourth-order gravity theories. We present new anisotropic vacuum solutions of…

General Relativity and Quantum Cosmology · Physics 2009-11-11 T. Clifton , John D. Barrow