منابع مشابه
Kantowski-Sachs String Cosmologies
We present new exact solutions of the low-energy-effective-action string equations with both dilaton φ and axion H fields non-zero. The background universe is of Kantowski-Sachs type. We consider the possibility of a pseudoscalar axion field h (H = eφ(dh)∗) that can be either time or space dependent. The case of time-dependent h reduces to that of a stiff perfect-fluid cosmology. For space-depe...
متن کاملA Perturbed Kantowski-sachs Cosmological Model
A numerical integration is made, starting with a Kantowski-Sachs (KS) model with an added initial perturbation at time one-tenth the age of the universe, and evolving up to the present. According to a prediction by Barrow (1989), the ratio between the fluctuations of the average matter density and those of the metric tensor varies with the inverse squared wavelength of the fluctuation. In this ...
متن کاملThe Kantowski-Sachs Space-Time in Loop Quantum Gravity
We extend the ideas introduced in the previous work to a more general space-time. In particular we consider the Kantowski-Sachs space time with space section with topology R× S. In this way we want to study a general space time that we think to be the space time inside the horizon of a black hole. In this case the phase space is four dimensional and we simply apply the quantization procedure su...
متن کاملCanonical theory of the Kantowski-Sachs cosmological models
We briefly discuss the Hamiltonian formalism of Kantowski-Sachs space-times with vacuum, anisotropic fluid and two cross-streaming radiation field sources. For these models a cosmological time is introduced. New constraints are found in which the fluid momenta are separated from the rest of the variables. In consequence their Poisson brackets give an Abelian algebra.
متن کاملTime-Symmetrization and Isotropization of Stiff-Fluid Kantowski-Sachs Universes
It is shown that growing-entropy stiff-fluid Kantowski-Sachs universes become time-symmetric (if they start with time-asymmetric phase) and isotropize. Isotropization happens without any inflationary era during the evolution since there is no cosmological term here. It seems that this approach is an alternative to inflation since the universe gets bigger and bigger approaching ’flatness’. short...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 1997
ISSN: 0556-2821,1089-4918
DOI: 10.1103/physrevd.55.630