We consider a non singular origin for the Universe starting from an Einstein static Universe in the framework of a theory which uses two volume elements √−gd4x and Φd4x, where Φ is a metric independent density, also curvature, curvature square terms, first order formalism and for scale invariance a dilaton field φ are considered in the action. In the Einstein frame we also add a cosmological term that parametrizes the zero point fluctuations. The resulting effective potential for the dilaton contains two flat regions, for φ → ∞ relevant for the non singular origin of the Universe and φ → −∞, describing our present Universe. Surprisingly, avoidance of singularities and stability as φ → ∞ imply a positive but small vacuum energy as φ → −∞. Zero vacuum energy density for the present universe is the ”threshold” for universe creation. This requires a modified emergent universe scenario, where the universe although very old, it does have a beginning.
|State||Published - 2013|