From de Sitter to de Sitter: A non-singular inflationary universe driven by vacuum

Abstract

A semi-classical analysis of vacuum energy in the expanding spacetime suggests that the cosmological term decays with time, with a concomitant matter production. For early times we find, in Planck units, $\Lambda \approx H^4$, where H is the Hubble parameter. The corresponding cosmological solution has no initial singularity, existing since an infinite past. During an infinitely long period we have a quasi-de Sitter, inflationary universe, with $H\approx 1$. However, at a given time, the expansion undertakes a phase transition, with H and $\Lambda$ decreasing to nearly zero in a few Planck times, producing a huge amount of radiation. On the other hand, the late-time scenario is similar to the standard model, with the radiation phase followed by a dust era, which tends asymptotically to a de Sitter universe, with vacuum dominating again.

arXiv commentThis essay received an "honorable mention" in the 2006 Essay Competition of the Gravity Research Foundation

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• The Cosmological Constant Problem and Running Vacuum in the Expanding Universe
• Observational constraints on late-time Lambda(t) cosmology
• Evolution of density perturbations in decaying vacuum cosmology
• Evolution of density perturbations in decaying vacuum cosmology: The case of non-zero perturbations in the cosmological term
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• f(R,T) Gravity Model Behaving as a Dark Energy Source
• Particle Production and Universal Thermodynamics
• A new mechanism for dark matter generation from an interacting cosmological constant