Oscillatory Universes in Loop Quantum Cosmology and Initial Conditions for Inflation

TL;DR

This paper explores oscillatory universes in Loop Quantum Cosmology, showing how quantum effects can set initial conditions for inflation and lead to eternal self-reproduction under certain parameters.

Contribution

It introduces a semi-classical reformulation of Loop Quantum Cosmology effects as an effective phantom fluid, demonstrating how oscillations can naturally lead to inflationary initial conditions.

Findings

Oscillatory universes undergo cyclic expansion and contraction.

Quantum effects can trigger initial conditions for inflation.

Eternal self-reproduction occurs at small quantum gravity parameters.

Abstract

Positively-curved, oscillatory universes are studied within the context of Loop Quantum Cosmology subject to a consistent semi-classical treatment. The semi-classical effects are reformulated in terms of an effective phantom fluid with a variable equation of state. In cosmologies sourced by a massless scalar field, these effects lead to a universe that undergoes ever-repeating cycles of expansion and contraction. The presence of a self-interaction potential for the field breaks the symmetry of the cycles and can enable the oscillations to establish the initial conditions for successful slow-roll inflation, even when the field is initially at the minimum of its potential with a small kinetic energy. The displacement of the field from its minimum is enhanced for lower and more natural values of the parameter that sets the effective quantum gravity scale. For sufficiently small values of this parameter, the universe can enter a stage of eternal self-reproduction.