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The fluctuations of the vacuum energy are treated as a non-equilibrium process and a stochastic model for the cosmological constant is presented, which yields a natural explanation for the smallness or zero value of the constant in the…

Astrophysics · Physics 2007-05-23 J. W. Moffat

Einstein-Vlasov system is solved for a homogeneous isotropic spacetime with positive curvature. In the case of the Universe consisting of massless particles the equation for R(t) is solved analytically.

General Relativity and Quantum Cosmology · Physics 2008-02-03 Tigran Aivazian

We prove well-posedness of the initial value problem for the Einstein equations for spatially-homogeneous cosmologies with data at an isotropic cosmological singularity, for which the matter content is either a cosmological constant with…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Paul Tod

Astronomical observations have shown that the expansion of the universe is at present accelerating, in a way consistent with the presence of a positive cosmological constant. This is a major puzzle, because we do not understand: why the…

Astrophysics · Physics 2007-05-23 Jordi Miralda-Escude

Adopting the q-theory approach to the cosmological constant problem, a simple field-theoretic model is presented which generates an effective cosmological constant (remnant vacuum energy density) of the observed order of magnitude,…

High Energy Physics - Theory · Physics 2011-08-11 F. R. Klinkhamer

We present a simple and complete classification of static solutions in the Einstein-Maxwell system with a massless scalar field in arbitrary $n(\ge 3)$ dimensions. We consider spacetimes which correspond to a warped product $M^2 \times…

General Relativity and Quantum Cosmology · Physics 2018-08-07 Hideki Maeda , Cristian Martinez

We report on a new two-parameter class of cosmological solutions to the Einstein-Maxwell equations. The solutions have everywhere regular curvature invariants. We prove that the solutions are geodesically complete and globally hyperbolic.

General Relativity and Quantum Cosmology · Physics 2009-11-07 Stoytcho Yazadjiev , Ventseslav Rizov

On the basis of qualitative analysis of the system of differential equations of the standard cosmological model it is shown that in the case of zero cosmological constant this system has a stable center corresponding to zero values of…

General Relativity and Quantum Cosmology · Physics 2016-09-29 Yurii Ignat'ev

Following an earlier suggestion by Dolgov, we present a specific model of two massless vector fields which dynamically cancel a cosmological constant of arbitrary magnitude and sign. Flat Minkowski spacetime appears asymptotically as an…

High Energy Physics - Theory · Physics 2012-04-03 V. Emelyanov , F. R. Klinkhamer

We construct infinite-dimensional families of non-singular static space times, solutions of the vacuum Einstein-Maxwell equations with a negative cosmological constant. The families include an infinite-dimensional family of solutions with…

Differential Geometry · Mathematics 2017-04-05 Piotr Chrusciel , Erwann Delay

We extend the usual gravitational action principle by promoting the bare cosmological constant (CC) from a parameter to a field which can take many possible values. Variation leads to a new integral constraint equation which determines the…

General Relativity and Quantum Cosmology · Physics 2011-03-21 John D. Barrow , Douglas J. Shaw

A covariant Lagrangian formulation of a solution to the cosmological constant problem, based on vizualising the fluctuations of the vacuum energy as a non-equilibrium process with stochastic behaviour, is presented. The variational…

Astrophysics · Physics 2016-08-30 J. W. Moffat

The quantum gravitational contribution to the renormalization group behavior of the electric charge in Einstein-Maxwell theory with a cosmological constant is considered. Quantum gravity is shown to lead to a contribution to the running…

High Energy Physics - Theory · Physics 2008-11-26 David J. Toms

The cosmological constant is one of the most pressing problems in modern physics. We address this issue from an emergent gravity standpoint, by using an analogue gravity model. Indeed, the dynamics of the emergent metric in a Bose-Einstein…

General Relativity and Quantum Cosmology · Physics 2012-02-29 Stefano Finazzi , Stefano Liberati , Lorenzo Sindoni

A positive cosmological constant simplifies the asymptotics of forever expanding cosmological solutions of the Einstein equations. In this paper a general mathematical analysis on the level of formal power series is carried out for vacuum…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Alan D. Rendall

Strong field (exact) solutions of the gravitational field equations of General Relativity in the presence of a Cosmological Constant are investigated. In particular, a full exact solution is derived within the inhomogeneous Szekeres-Szafron…

General Relativity and Quantum Cosmology · Physics 2011-07-19 G. V. Kraniotis , S. B. Whitehouse

In this paper we found an Exact solution for massless scalar field with cosmological constant. This exact solution generalized the Levi-Civita vacuum solution\cite{8} to a massless scalar field,with a cosmological constant term. This…

Mathematical Physics · Physics 2010-11-02 H. R. Rezazadeh

We construct new classes of cosmological solution to the five dimensional Einstein-Maxwell-dilaton theory, that are non-stationary and almost conformally regular everywhere. The base geometry for the solutions is the four-dimensional…

General Relativity and Quantum Cosmology · Physics 2021-07-21 Bardia H. Fahim , Masoud Ghezelbash

We review recent results concerning the spherically symmetric Einstein-scalar field system with positive cosmological constant. We do so by comparing with the classical results of Christodoulou concerning the asymptotically flat case…

General Relativity and Quantum Cosmology · Physics 2013-12-02 João L. Costa

We establish the existence of a family of static, spherically symmetric spacetimes that are solutions of the Einstein Field Equations of General Relativity coupled to the electric field of a static point charge obeying the equations of…

General Relativity and Quantum Cosmology · Physics 2025-08-11 Erik Amorim