A model of the universe with decaying vacuum energy

摘要

The consequences of taking the total active gravitational mass of the universe phasewise constant together with a decaying vacuum energy in the background of Robertson-Walker space-time are investigated. The model so determined admits a contracted Ricci-collineation along the fluid flow vector v~i. It is geometrically closed but ever-expanding and does not possess the initial singularity, horizon, entropy, monopole or cosmological constant problems of the standard big bang cosmology. Estimates of the present matter, radiation and vacuum energy densities, the age of the universe and the present values of the deceleration parameter and the scale factor are also obtained.