N ov 1 99 9 Cosmological models with variable “ constants ”

The behavior of the “constants”, G, c, h̄, a, e, mi and Λ, considering them as variable, in the framework of a flat cosmological model with FRW symmetries described by a bulk viscous fluid and considering mechanisms of adiabatic matter creation are investigated. Two cases are studied; one with radiation predominance and another of matter predominance. It is found that with the solution obtained our model verifies these basic principles: Lorentz invariance and general covariance, Mach, Equivalence and causality. Finally to emphasize that the envisaged models are free from the main problem: Planck’s, horizon and entropy. With regard to that model with matter predominance it is seen that mechanisms of creation of matter cannot be considered since if these are taken into account the temperature would increase instead of remaining constant while the universe expands.