scholarly journals A PROPOSED SCALE-DEPENDENT COSMOLOGY FOR THE INHOMOGENEOUS UNIVERSE

1996 ◽  
Vol 05 (03) ◽  
pp. 293-312 ◽  
Author(s):  
C.W. KIM ◽  
J. SONG
Keyword(s):  
Hubble Parameter ◽  
Globular Clusters ◽  
Observational Cosmology ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Inhomogeneous Universe ◽  
Stress Energy ◽  
Walker Metric ◽  
Age Of The Universe ◽  
The Universe

We propose a scale-dependent cosmology with the stress-energy tensor of viscous fluid, in which the Robertson-Walker metric and the Einstein equation are generalized in such a way that Ω0, H0 and the age of the Universe all become scale-dependent. Its implications on the observational cosmology and possible modifications of the standard Friedmann cosmology are discussed. For example, since the age of the Universe in this model depends on the local values of Ω0 and the Hubble parameter, the age of the locally open Universe even with the high value of hubble parameter can be long enough to accommodate the measured ages of the oldest stars and globular clusters.

scholarly journals Cosmological perfect fluids in Gauss–Bonnet gravity

2019 ◽  
Vol 16 (09) ◽  
pp. 1950133 ◽  
Author(s):  
Salvatore Capozziello ◽  
Carlo Alberto Mantica ◽  
Luca Guido Molinari
Keyword(s):  
Perfect Fluid ◽  
Topological Invariant ◽  
Energy Tensor ◽  
Curvature Scalar ◽  
Stress Energy Tensor ◽  
Perfect Fluids ◽  
Stress Energy ◽  
Walker Metric ◽  
Friedmann Robertson Walker ◽  
Hubble Flow

In a [Formula: see text]-dimensional Friedmann–Robertson–Walker metric, it is rigorously shown that any analytical theory of gravity [Formula: see text], where [Formula: see text] is the curvature scalar and [Formula: see text] is the Gauss–Bonnet topological invariant, can be associated to a perfect-fluid stress–energy tensor. In this perspective, dark components of the cosmological Hubble flow can be geometrically interpreted.

scholarly journals AN ISOTROPIZATION MECHANISM IN BIANCHI I MODEL

2003 ◽  
Vol 12 (08) ◽  
pp. 1499-1508
Author(s):  
H. H. FLICHE ◽  
R. TRIAY ◽  
M. NOVELLO ◽  
L. R. De FREITAS
Keyword(s):  
Initial Conditions ◽  
Hamiltonian Formalism ◽  
Anisotropic Pressure ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Stress Energy ◽  
Elimination Mechanism ◽  
Pass Through ◽  
The Universe ◽  
Efficient Elimination

We ask whether the problem on the initial conditions in Cosmology can be solved if an efficient elimination mechanism of the anisotropy was present at earlier epochs. We explore the consequences of the existence of an epoch in which the material content of the Universe was represented by an stress-energy tensor possessing anisotropic pressure which depends nonlinearly on the expansion parameter. We show that for selected candidate behaviors the associated shear pass through a maximum and vanishes asymptotically. We use the Hamiltonian formalism to define a constant of motion which enables us to classify the cosmological world-models.

A COSMOLOGY WITH A TIME AND SPACE COORDINATE-DEPENDENT SCALE FACTOR

1995 ◽  
Vol 10 (26) ◽  
pp. 1887-1894
Author(s):  
C.W. KIM ◽  
A. SINIBALDI ◽  
J. SONG
Keyword(s):  
Einstein Equation ◽  
Globular Clusters ◽  
Scale Factor ◽  
Time And Space ◽  
Cosmic Scale ◽  
Walker Metric ◽  
Space Coordinate ◽  
Age Of The Universe ◽  
The Universe

Based on the increase of Ω0 as a function of cosmic scale, the Robertson-Walker metric and the Einstein equation are generalized so that Ω0, H0 and the age of the Universe, to, all become functions of cosmic scales at which we observe them. The calculated local (within our galaxy) age of the Universe is about 18 Gyr, consistent with the ages of the oldest stars and globular clusters in our galaxy, while the ages at distant scales are shorter than the local age, solving the age puzzle. It is also shown that H0 becomes scale-dependent.

scholarly journals Stress-energy tensor correlators from the world-sheet

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Hanno Bertle ◽  
Andrea Dei ◽  
Matthias R. Gaberdiel
Keyword(s):  
Vertex Operator ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
World Sheet ◽  
Stress Energy ◽  
The World

Abstract The large N limit of symmetric orbifold theories was recently argued to have an AdS/CFT dual world-sheet description in terms of an sl(2, ℝ) WZW model. In previous work the world-sheet state corresponding to the symmetric orbifold stress-energy tensor was identified. We calculate certain 2- and 3-point functions of the corresponding vertex operator on the world-sheet, and demonstrate that these amplitudes reproduce exactly what one expects from the dual symmetric orbifold perspective.

ON THE ELECTROMAGNETIC PERTURBATIONS OF A MULTICONICAL SPACETIME

1996 ◽  
Vol 11 (27) ◽  
pp. 2171-2177
Author(s):  
A.N. ALIEV
Keyword(s):  
Cosmic Strings ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Stress Energy ◽  
Electromagnetic Perturbations

The electromagnetic perturbations propagating in the multiconical spacetime of N parallel cosmic strings are described. The expression for vacuum average of the stress-energy tensor is reduced to a form involving only zero-spin-weighted perturbation modes.

scholarly journals Kerr-Newman stress-tensor from minimal coupling

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Ming-Zhi Chung ◽  
Yu-tin Huang ◽  
Jung-Wook Kim
Keyword(s):  
Form Factor ◽  
Stress Tensor ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Minimal Coupling ◽  
Massive Spin ◽  
Stress Energy ◽  
Newman Black Hole ◽  
Higher Spin ◽  
The One

Abstract In this paper, we demonstrate that at leading order in post Minkowskian (PM) expansion, the stress-energy tensor of Kerr-Newman black hole can be recovered to all orders in spin from three sets of minimal coupling: the electric and gravitational minimal coupling for higher-spin particles, and the “minimal coupling” for massive spin-2 decay. These couplings are uniquely defined from kinematic consideration alone. This is shown by extracting the classical piece of the one-loop stress-energy tensor form factor, which we provide a basis that is valid to all orders in spin. The 1 PM stress tensor, and the metric in the harmonic gauge, is then recovered from the classical spin limit of the form factor.

Sign in / Sign up

Export Citation Format

Share Document