Making use of the $1 + 3$ covariant formalism, we show explicitly effect that nonmetricity has on dynamics universe. Then, using Dynamical System Approach, analyze evolution Bianchi type-I cosmologies within framework $f(\mathcal{Q})$ gravity. We consider several models function $f(\mathcal{Q})$, each them manifesting isotropic eras universe, whether transitional or not. In one case, in additio...

Current observations indicate that, on a large enough scale, the universe is homogeneous and isotropic. However, this does not preclude possibility of some anisotropy having occurred during early stages evolution universe, which could then have been damped out later. This idea has aroused interest in Bianchi models, are but anisotropic. Secondly, there much modified gravity these days due to pr...

We solve the Wheeler-DeWitt equation for the minisuperspace of a cosmological Bianchi type-I model with a minimally coupled massive scalar field f as the source by generalizing the calculation of Lukash and Schmidt @Astron. Nachr. 309, 25 ~1988!#. Contrary to other approaches we allow strong anisotropy. Combining analytical and numerical methods, we apply an adiabatic approximation for f , and ...

A general method for solving the Cosmological Einstein’s Field Equations (EFE) in vacuum is presented, and is applied to the Bianchi Type III vacuum cosmology. As a result, the entire space of solutions for this model is found. This space is composed of two distinct, disconnected ,three-parameter families. Both of them admit four Killing vector Fields and no homothetic vector. One family repres...

Deviations from statistical isotropy can be modeled in various ways, for instance, anisotropic cosmological models (Bianchi models), compact topologies and presence of primordial magnetic field. Signature of anisotropy manifests itself in CMB correlation patterns. Here we explore the symmetries of the correlation function and its implications on the observable measures constructed within the Bi...

We show several kinematical properties that are intrinsic to the Bianchi models with compact spatial sections. Especially, with spacelike hypersurfaces being closed, (A) no anisotropic expansion is allowed for Bianchi type V and VII (A = 0), and (B) type IV and VI (A = 0, 1) does not exist. In order to show them, we put into geometric terms what is meant by spatial homogeneity and employ a math...

An anisotropic ~Bianchi type I! cosmology is considered in the four-dimensional Neveu-Schwarz–NeveuSchwarz ~NS–NS! sector of low-energy effective string theory coupled to a dilaton and an axionlike H field within a de Sitter–Einstein frame background. The general solution of the gravitational field equations can be expressed in an exact parametric form in both Einstein and string frames. The st...

Bianchi-type string cosmology involves generalizations of the FRW backgrounds with three transitive spacelike Killing symmetries, but without any a priori assumption of isotropy in the 3D sections of homogeneity. With emphasis on those cases with diagonal metrics and vanishing cosmological constant which have not been previously examined in the literature, the present findings allow an overview...