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In this paper we perform systematic investigation of all possible solutions with static compact extra dimensions and expanding three-dimensional subspace (``our Universe''). Unlike previous papers, we consider extra-dimensional subspace to…

General Relativity and Quantum Cosmology · Physics 2021-04-22 Dmitry Chirkov , Alex Giacomini , Sergey A. Pavluchenko , Alexey Toporensky

After a short history of the $\Lambda$-term it is explained why the (effective) cosmological constant is expected to obtain contributions from short-distance physics, corresponding to an energy at least as large as the Fermi scale. The…

Astrophysics · Physics 2007-05-23 Norbert Straumann

We investigate cosmological solutions of Brans-Dicke theory with both the vacuum energy density and the gravitational constant decaying linearly with the Hubble parameter. A particular class of them, with constant deceleration factor, sheds…

General Relativity and Quantum Cosmology · Physics 2010-03-19 A. E. Montenegro , S. Carneiro

We consider a higher dimensional gravity theory with a negative kinetic energy scalar field and a cosmological constant. We find that the theory admits an exact cosmological solution for the scale factor of our universe. It has the feature…

General Relativity and Quantum Cosmology · Physics 2008-11-26 S. T. Hong , J. Lee , T. H. Lee , P. OH

The universe is found to have undergone several phases in which the gravitational constant had different behaviors. During some epochs the energy density of the universe remained constant and the universe remained static. In the radiation…

Astrophysics · Physics 2007-05-23 Arbab I. Arbab

An overview of the cosmological models with expansion, shear and rotation is presented. Problems of the rotating models are discussed, their general kinematic properties and dynamical realizations are described. A particular attention is…

Astrophysics · Physics 2007-05-23 Yuri N. Obukhov

We review astrophysical, cosmological and terrestrial evidence for and against the constancy of fundamental parameters of particle physics, and discuss theoretical issues of unification and scalar-mediated forces, finding that the current…

High Energy Physics - Phenomenology · Physics 2008-11-26 Thomas Dent

A mechanism is introduced to reduce a large cosmological constant to a sufficiently small value consistent with observational upper limit. The basic ingradient in this mechanism is a distinction which has been made between the two unit…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Y. Bisabr , H. Salehi

The flatness and cosmological constant problems are solved with varying speed of light c, gravitational coupling strength G and cosmological parameter Lambda, by explicitly assuming energy conservation of observed matter. The present…

General Relativity and Quantum Cosmology · Physics 2009-10-31 P. Gopakumar , G. V. Vijayagovindan

Given a functional for a one-dimensional physical system, a classical problem is to minimize it by finding stationary solutions and then checking the positive definiteness of the second variation. Establishing the positive definiteness is,…

Classical Analysis and ODEs · Mathematics 2017-04-26 Thomas Lessinnes , Alain Goriely

Universe structure emerges in the unreduced, complex-dynamic interaction process with the simplest initial configuration (two attracting homogeneous fields, quant-ph/9902015). The unreduced interaction analysis gives intrinsically creative…

General Physics · Physics 2007-05-23 Andrei P. Kirilyuk

One of the most enduring and unresolved challenges in modern theoretical and observational cosmology is the fine-tuning and coincidence problems associated with the cosmological constant. Rather than attempting to reconcile these issues…

General Relativity and Quantum Cosmology · Physics 2026-02-24 H. R. Fazlollahi

The mechanism of low energy physics formation in the framework of multidimensional gravity is discussed. It is shown that a wide set of parameters of a primary theory could lead to the observable Universe. Quantum fluctuations of extra…

General Relativity and Quantum Cosmology · Physics 2013-02-12 S. G. Rubin

The formation mechanism of universes with distinctly different properties is considered within the framework of pure gravity in a space of D > 4 dimensions. The emergence of the Planck scale and its relationship to the inflaton mass are…

General Relativity and Quantum Cosmology · Physics 2008-11-26 S. G. Rubin

There is a deep cosmological mystery: although dependent on very different underlying physics, the timescales of structure formation, of galaxy cooling (both radiatively and against the CMB), and of vacuum domination do not differ by many…

High Energy Physics - Theory · Physics 2009-09-24 Raphael Bousso , Lawrence J. Hall , Yasunori Nomura

After a survey of the present state of cosmological theory and observations, this article discusses a series of major themes underlying the relation of philosophy to cosmology. These are: A: The uniqueness of the universe; B: The large…

Astrophysics · Physics 2007-05-23 George F. R. Ellis

New Planck scale physics may solve the singularity problems of classical general relativity and may lead to interesting consequences for very early Universe cosmology. Two approaches to these questions are reviewed in this article. The…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Robert H. Brandenberger

The clockwork is a mechanism for generating light particles with exponentially suppressed interactions in theories which contain no small parameters at the fundamental level. We develop a general description of the clockwork mechanism valid…

High Energy Physics - Phenomenology · Physics 2017-03-08 Gian F. Giudice , Matthew McCullough

We present some cosmological solutions of Brans-Dicke theory, characterized by a decaying vacuum energy density and by a constant relative matter density. With these features, they shed light on the cosmological constant problems, leading…

General Relativity and Quantum Cosmology · Physics 2010-03-19 S. Carneiro , A. E. Montenegro

There are many theories of quantum gravity, depending on asymptotic boundary conditions, and the amount of supersymmetry. The cosmological constant is one of the fundamental parameters that characterize different theories. If it is…

High Energy Physics - Theory · Physics 2015-06-26 T. Banks