ar X iv : g r - qc / 9 70 80 38 v 2 5 M ay 1 99 8 The Gowdy T 3 Cosmologies revisited

ar X iv : g r - qc / 9 70 80 38 v 1 1 8 A ug 1 99 7 The Gowdy T 3 Cosmologies revisited

We have examined and repeated earlier numerical calculations of Berger and Moncrief for the evolution of unpolarized Gowdy T 3 cosmological models. Our calculations do not always agree with theirs, and we come to the opposite conclusion: these models do not appear to develop velocity term dominated behaviour.

ar X iv : g r - qc / 9 21 20 13 v 1 2 1 D ec 1 99 2 Inhomogeneous and anisotropic cosmologies

ar X iv : g r - qc / 0 50 80 08 v 1 1 A ug 2 00 5 Observables for the polarized Gowdy model

We give an explicit characterization of all functions on the phase space for the polarized Gowdy 3-torus spacetimes which have weakly vanishing Poisson brackets with the Hamiltonian and momentum constraint functions.

ar X iv : g r - qc / 9 80 10 66 v 2 1 6 M ay 1 99 8 Birth of a Closed Universe of Negative Spatial Curvature

We propose a modified form of the spontaneous birth of the universe by quantum tunneling. It proceeds through topology change and inflation, to eventually become a universe with closed spatial sections of negative curvature and nontrivial global topology. PACS numbers: 98.80.Hw, 04.20.Gz

ar X iv : g r - qc / 9 51 10 66 v 1 2 4 N ov 1 99 5 Scalar Field Inhomogeneous

Some exact solutions for the Einstein field equations corresponding to inhomogeneous G 2 cosmologies with an exponential-potential scalar field which generalize solutions obtained previously are considered. Several particular cases are studied and the properties related to generalized inflation and asymptotic behaviour of the models are discussed.