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The concept of smooth deformation of Riemannian manifolds associated with the extrinsic curvature is explained and applied to the FLRW cosmology. We show that such deformation can be derived from Einstein-Hilbert-like dynamical principle…

General Relativity and Quantum Cosmology · Physics 2017-04-06 Abraao J. S. Capistrano , Luiz A. Cabral

I briefly review the cosmological constant problem and the issue of dark energy (or quintessence). Within the framework of quantum field theory, the vacuum expectation value of the energy momentum tensor formally diverges as $k^4$. A cutoff…

Astrophysics · Physics 2008-11-26 Varun Sahni

As an alternative to dark energy it has been suggested that we may be at the center of an inhomogeneous isotropic universe described by a Lemaitre-Tolman-Bondi (LTB) solution of Einstein's field equations. In order to test such an…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Antonio Enea Romano

The cosmological constant problem is examined under the assumption that the extrinsic curvature of the space-time contributes to the vacuum. A compensation mechanism based on a variable cosmological term is proposed. Under a suitable…

General Relativity and Quantum Cosmology · Physics 2009-09-25 M. D. Maia , G. S. Silva

We study the influence of the fluctuations of a Lorentz invariant and conserved vacuum on cosmological metric perturbations, and show that they generically blow up in the IR. We compute this effect using the K\"all\'en-Lehmann spectral…

High Energy Physics - Theory · Physics 2016-07-06 Niayesh Afshordi , Elliot Nelson

A new analytical solution for the luminosity distance in flat $\Lambda$CDM cosmology is derived in terms of elliptical integrals of first kind with real argument. The consequent derivation of the distance modulus allows evaluating the…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-19 Lorenzo Zaninetti

In a series of articles, we have shown that the newly discovered plasma-redshift cosmology gives a simpler, more accurate and consistent explanation of many cosmological phenomena than the big-bang cosmology. The SNe Ia observations are in…

Astrophysics · Physics 2007-05-23 Ari Brynjolfsson

Quantum liquids, in which an effective Lorentzian metric and thus some kind of gravity gradually arise in the low-energy corner, are the objects where the problems related to the quantum vacuum can be investigated in detail. In particular,…

General Relativity and Quantum Cosmology · Physics 2007-05-23 G. E. Volovik

We use one of the simplest forms of the K-essence theory and we apply it to the classical anisotropic Bianchi type I cosmological model, with a barotropic perfect fluid modeling the usual matter content and with cosmological constant. The…

General Relativity and Quantum Cosmology · Physics 2014-09-11 J. Socorro , Luis O. Pimentel , Abraham Espinoza-García

We derive mathematical models of the elementary process of dissolution/growth of bubbles in a liquid under pressure control. The modeling starts with a fully compressible version, both for the liquid and the gas phase so that the entropy…

Fluid Dynamics · Physics 2014-03-04 Dieter Bothe , Kohei Soga

The purpose of this study is to describe a perfect fluid matter distribution that leads to a constant curvature region, thanks to the effect of a non-minimal coupling. This distribution exhibits a density profile within the range found in…

General Relativity and Quantum Cosmology · Physics 2011-07-04 J. Páramos , O. Bertolami

We study the quantification of coherence in infinite dimensional systems, especially the infinite dimensional bosonic systems in Fock space. We show that given the energy constraints, the relative entropy of coherence serves as a…

Quantum Physics · Physics 2016-01-27 Yu-Ran Zhang , Lian-He Shao , Yongming Li , Heng Fan

In the framework of a Varying Speed of Light theory, we study the eigenvalues associated with the Wheeler-DeWitt equation representing the vacuum expectation values associated with the cosmological constant. We find that the Wheeler-DeWitt…

General Relativity and Quantum Cosmology · Physics 2015-03-13 Remo Garattini , Mariafelicia De Laurentis

A more conventional realization of a symmetry which had been proposed towards the solution of cosmological constant problem is considered. In this study the multiplication of the coordinates by the imaginary number $i$ in the literature is…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Recai Erdem

This paper investigates the asymptotic behavior of the Helmholtz free energy of mixtures at small compressibility. We start from a general representation for the local free energy that is valid in stable subregions of the phase diagram. On…

Mathematical Physics · Physics 2021-04-20 Dieter Bothe , Wolfgang Dreyer , Pierre-Etienne Druet

The relativistic invariant zeta-function approach to computation of the vacuum energy contribution to cosmological constant is discussed. It is shown that this value is determined by the fourth power of the quantized field mass, while the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Igor O. Cherednikov

In this paper, we investigate the density-dependent incompressible nematic liquid crystal flows in $n(n=2$ or $3)$ dimensional bounded domain. More precisely, we obtain the local existence and uniqueness of the solutions when the viscosity…

Analysis of PDEs · Mathematics 2015-02-03 Jincheng Gao , Qiang Tao , Zheng-an Yao

In a recent paper (Vigoureux et al. Int. J. Theor. Phys. 47:928, 2007) it has been suggested that the velocity of light and the expansion of the universe are two aspects of one single concept connecting space and time in the expanding…

Cosmology and Nongalactic Astrophysics · Physics 2011-03-22 David Viennot , Jean-Marie Vigoureux

The concept of deformation of Riemannian geometry is reviewed, with applications to gravitation and cosmology. Starting with an analysis of the cosmological constant problem, it is shown that space-times are deformable in the sense of local…

General Relativity and Quantum Cosmology · Physics 2015-05-28 M. D. Maia

The well-known fluid equation of cosmology is examined with a view to elucidating the precise conditions under which it is applicable.

General Physics · Physics 2008-05-22 Jeremy Dunning-Davies