Stationarity of Inflation and Predictions of Quantum Cosmology

TL;DR

This paper explores different inflationary regimes in cosmology, analyzing their stationarity and implications for quantum cosmology, including a new mechanism potentially addressing the cosmological constant problem.

Contribution

It classifies inflationary regimes, examines their stationarity properties, and proposes a novel mechanism relevant to quantum cosmology and the cosmological constant problem.

Findings

Inflation without self-reproduction leads to a non-stationary universe.

Eternal inflation with self-reproduction can have stationary or non-stationary probability distributions.

A new mechanism is proposed that may help solve the cosmological constant problem.

Abstract

We describe several different regimes which are possible in inflationary cosmology. The simplest one is inflation without self-reproduction of the universe. In this scenario the universe is not stationary. The second regime, which exists in a broad class of inflationary models, is eternal inflation with the self-reproduction of inflationary domains. In this regime local properties of domains with a given density and given values of fields do not depend on the time when these domains were produced. The probability distribution to find a domain with given properties in a self-reproducing universe may or may not be stationary, depending on the choice of an inflationary model. We give examples of models where each of these possibilities can be realized, and discuss some implications of our results for quantum cosmology. In particular, we propose a new mechanism which may help solving the cosmological constant problem.