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A nonvanishing cosmological term in Einstein's equations implies a nonvanishing spacetime curvature even in absence of any kind of matter. It would, in consequence, affect many of the underlying kinematic tenets of physical theory. The…

General Relativity and Quantum Cosmology · Physics 2009-11-10 R. Aldrovandi , J. P. Beltran Almeida , J. G. Pereira

Increasing improvements in the independent determinations of the Hubble constant and the age of the universe now seem to indicate that we need a small non-vanishing cosmological constant to make the two independent observations consistent…

High Energy Physics - Phenomenology · Physics 2009-10-28 Anupam Singh

Despite the many outstanding cosmological observations leading to a strong evidence for a nonvanishing cosmological constant (CC) term in the gravitational field equations, the theoretical status of this quantity seems to be lagging well…

High Energy Physics - Theory · Physics 2010-02-11 Ilya L. Shapiro , Joan Sola

Within the framework of the minimum quadratic Poincare gauge theory of gravity in the Riemann-Cartan spacetime we study the influence of gravitational vacuum energy density (a cosmological constant) on the dynamics of various gravitating…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Nguyen Hong Chuong , Nguyen Van Hoang

The vacuum fluctuations of all quantum fields filling the universe are supposed to leave enormous energy and pressure contributions which are incompatible with observations. It has been recently suggested that, when the effective nature of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Vincenzo Branchina , Dario Zappalà

It is believed that gravity will be explained in the framework of the existing quantum theory when one succeeds in eliminating divergencies at large momenta or small distances (although the phenomenon of gravity has been observed only at…

General Relativity and Quantum Cosmology · Physics 2008-07-28 Felix Lev

We outline the evaluation of the cosmological constant in the framework of the standard field-theoretical treatment of vacuum energy and discuss the relation between the vacuum energy problem and the gauge-group spontaneous symmetry…

General Relativity and Quantum Cosmology · Physics 2008-11-26 A. A. Andrianov , F. Cannata , P. Giacconi , A. Yu. Kamenshchik , R. Soldati

In this Letter we show that the vacuum polarization of quantum fields in an anti-de Sitter space naturally gives rise to a small but nonzero cosmological constant in a brane world living in it. To explain the extremely small ratio of mass…

High Energy Physics - Theory · Physics 2010-11-05 Li-Xin Li

We propose several covariant models which may solve one of the problems in the cosmological constant. One of the model can be regarded as an extension of sequestering model. Other models could be regarded as extensions of the covariant…

High Energy Physics - Theory · Physics 2016-11-10 Shin'ichi Nojiri

We investigate the line element of spacetime around a linear cosmic string in the presence of a cosmological constant. We obtain the metric and argue that it should be discarded because of asymptotic considerations. Then a time dependent…

General Relativity and Quantum Cosmology · Physics 2009-01-05 Amir H. Abbassi , Amir M. Abbassi

We study the quantization of geometry in the presence of a cosmological constant, using a discretiza- tion with constant-curvature simplices. Phase space turns out to be compact and the Hilbert space finite dimensional for each link. Not…

General Relativity and Quantum Cosmology · Physics 2015-04-22 Carlo Rovelli , Francesca Vidotto

The Standard Cosmological Model of the 1980's is no more. I describe the definitive evidence that the density of matter is insufficient to result in a flat universe, as well as the mounting evidence that the cosmological constant is not…

High Energy Physics - Phenomenology · Physics 2009-10-31 Lawrence M. Krauss

This paper examines two cosmological models of quantum gravity (from string theory and loop quantum gravity) to investigate the foundational and conceptual issues arising from quantum treatments of the big bang. While the classical…

History and Philosophy of Physics · Physics 2017-11-01 Nick Huggett , Christian Wuthrich

We use the phase plane analysis technique of Madsen and Ellis to consider a universe with a true cosmological constant as well as a cosmological "constant" that is decaying. Time symmetric dynamics for the inflationary era allows eternally…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-27 George F. R. Ellis , Emma Platts , David Sloan , Amanda Weltman

Special theory of relativity has been formulated in a vacuum momentum-energy representation which is equivalent to Einstein special relativity and predicts just the same results as it. Although in this sense such a formulation would be at…

General Relativity and Quantum Cosmology · Physics 2007-05-23 P. F. Gonzalez-Diaz

The cosmological constant is not an absolute constant. The gravitating part of the vacuum energy is adjusted to the energy density of matter and to other types of the perturbations of the vacuum. We discuss how the vacuum energy responds…

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

The existence of a non-zero cosmological constant $\Lambda$ gives rise to controversial interpretations. Is $\Lambda$ a universal constant fixing the geometry of an empty universe, as fundamental as the Planck constant or the speed of light…

General Relativity and Quantum Cosmology · Physics 2012-09-25 Jean-Pierre Gazeau , Mario Novello

One hope to solve the cosmological constant problem is to identify a symmetry principle, based on which the cosmological constant can be reduced either to zero, or to a tiny value. Here, we note that requiring that the vacuum state is…

General Relativity and Quantum Cosmology · Physics 2011-06-01 Jurjen F. Koksma , Tomislav Prokopec

A holistic view of the cosmological appearance and development of space is obtained by studying space as a spherically closed surface of a 4-sphere in a zero energy balance between motion and gravitation. Such an approach re-establishes…

Astrophysics · Physics 2009-11-13 Tuomo Suntola

A multidimensional cosmological model with space-time consisting of n (n>1) Einstein spaces M_i is investigated in the presence of a cosmological constant Lambda and a homogeneous minimally coupled free scalar field. Generalized de Sitter…

General Relativity and Quantum Cosmology · Physics 2008-11-26 A. Zhuk