The two-component formalism in quantum cosmology is revisited with a particular emphasis on the identification of time. Its relation with the appearance of imaginary eigenvalues is established. It is explicitly shown how ...

The Einstein equations for an isotropic and homogeneous Friedmann-Robertson-Walker universe in the presence of a quintessence scalar field are shown to be described in a compact way, formally identical to the dynamics of ...

In this letter we study the effects of a noncommutative minisuperspace, including matter degrees of freedom on a toy model for FRW universe with cosmological constant. In this simple model the vacuum energy density is ...

We present the construction of a Hamiltonian description for a (non-Lagrangian) Bianchi type-V cosmological model using the solutions of the equations of motion as a starting point. We study the quantization of the model ...

The paper is the first of two parts of a work reviewing some approaches to the problem of time in quantum cosmology, which were put forward last decade, and which demonstrated their relation to the problems of reparametrization ...

The dynamics of the most general Bianchi IX cosmology with three time dependent scale factors for the Einstein-Skyrme system are analyzed. For the Skyrmion, a generalized hedgehog ansatz with unit baryon charge is introduced. ...

Using the WKB-like and Hamilton procedures classical solutions to commutative and noncommutative cosmology are found. This is carried out in the Bianchi type I cosmological model coupled to barotropic perfect fluid and ...

Using the WKB-like and Hamilton procedures classical solutions to commutative and noncommutative cosmology are found. This is carried out in the Bianchi type I cosmological model coupled to barotropic perfect fluid and ...

In this letter we study the effects of a noncommutative minisuperspace, including matter degrees of freedom on a toy model for FRW universe with cosmological constant. In this simple model the vacuum energy density is ...