The consistency of the constraint with the evolution equations for spatially inhomogeneous and irrotational silent (SIIS) models of Petrov type I, demands that the former are preserved along the timelike congruence represented by the velocity of the dust fluid, leading to new non-trivial constraints. This fact has been used to conjecture that the resulting models correspond to the spatially hom...

Bianchi type V I0 massive string cosmological models using the technique given by Letelier (1983) with magnetic field are investigated. To get the deterministic models, we assume that the expansion (θ) in the model is proportional to the shear (σ) and also the fluid obeys the barotropic equation of state. It was found that vacuum energy density Λ ∝ 1 t2 which matches with natural units. The beh...

The consistency of the constraint with the evolution equations for spatially inhomogeneous and irrotational silent (SIIS) models of Petrov type I, demands that the former are preserved along the timelike congruence represented by the velocity of the dust fluid, leading to new non-trivial constraints. This fact has been used to conjecture that the resulting models correspond to the spatially hom...

In one-loop string effective action, we study a generality of non-singular cosmological solutions found in the isotropic and homogeneous case. We discuss Bianchi I and IX type spacetimes. We find that nonsingular solutions still exist in Bianchi I model around nonsingular flat Friedmann solutions. On the other hand, we cannot find any nonsingular solutions in Bianchi IX model. Non-existence of ...

The Chern-Simons functional SCS is an exact solution to the AshtekarHamilton-Jacobi equation of general relativity with a nonzero cosmological constant. In this paper we consider SCS in Bianchi type IX cosmology with S spatial surfaces. We show that among the classical solutions generated by SCS, there is a two-parameter family of Euclidean spacetimes that have a regular NUT-type closing. When ...

We use a dynamical systems approach to analyse the tilting spatially homogeneous Bianchi models of solvable type (e.g., types VIh and VIIh) with a perfect fluid and a linear barotropic γ-law equation of state. In particular, we study the late-time behaviour of tilted Bianchi models, with an emphasis on the existence of equilibrium points and their stability properties. We briefly discuss the ti...

We study a string-inspired cosmological model from the symmetries point of view. We start by deducing the form that each physical quantity must take so that the field equations, in the string frame, admit self-similar solutions. In the same way, we formalize the use of power-law solutions (less restrictive than the self-similar ones) by studying the wave equation for the dilaton through the Lie...

We present a new action which reproduces the cosmological sector of general relativity in both Friedmann-Lemaitre-Robertson-Walker (FLRW) and Bianchi models. This makes no reference to scale factor, is frictional type first examined by Herglotz. demonstrate that extremization this usual dynamics physical observables, symplectification Einstein-Hilbert for end discussing some increased explanato...