We consider the horizon problem in a homogeneous but anisotropic universe (Bianchi type I). We show that the problem cannot be solved if (1) the matter obeys the strong energy condition with the positive energy density and (2) the Einstein equations hold. The strong energy condition is violated during cosmological inflation. PACS numbers: 98.80.Hw Typeset using REVTEX

We present a class of new exact homogeneous cosmological solutions with a radiation fluid for all scalar-tensor theories. The solutions belong to Bianchi type V Ih cosmologies. Explicit examples of nonsingular homogeneous scalartensor cosmologies are also given. 04.50.+h, 04.20.Jb, 98.80.Hw Typeset using REVTEX ∗E-mail: [email protected]

The Bianchi type I cosmological model is brought into a form where the evolution of observables is governed by the unconstrained Hamiltonian that coincides with the Hamiltonian describing the relative motion of particles in the integrable 3-body hyperbolic Euler-Calogero-Sutherland system.

We explain how the round four sphere can be sliced along homogeneous 3 manifolds of topology S/D 8 . This defines a Euclidean Bianchi type IX model for Einstein’s equations with cosmological constant. The geometric properties of this model are investigated. PACS: 02.40.-k, 02.40.Ma, 98.80.Hw MSC: 53C42

An asymptotic stability analysis of spatially homogeneous models of Bianchi type containing tilted perfect fluids is performed. Using the known attractors for the non-tilted Bianchi type universes, we check whether they are stable against perturbations with respect to tilted perfect fluids. We perform the analysis for all Bianchi class B models and the Bianchi type V I0 model. In particular, we...

We find solutions for quantum Class A Bianchi models of the form Ψ = W e ±Φ generalizing the results obtained by Moncrief and Ryan in standard quantum cosmology. For the II and IX Bianchi models there are other solu-tions˜Φ 2 , ˜ Φ 9 to the Hamilton-Jacobi equation for which Ψ is necessarely zero, in contrast with solutions found in supersymmetric quantum cosmology.

Antoni Ferragut, a) Jaume Llibre, b) and Chara Pantazi c) Departament de Matemàtica Aplicada I, Universitat Politècnica de Catalunya, ETSEIB, Av. Diagonal, 647, 08028, Barcelona, Catalonia, Spain Departament de Matemàtiques, Universitat Autònoma de Barcelona, Edifici C, 08193 Bellaterra, Barcelona, Catalonia, Spain Departament de Matemàtica Aplicada I, Universitat Politècnica de Catalunya, (EPS...