Quantum Instability of the Emergent Universe

TL;DR

This paper analyzes the quantum stability of the Emergent Universe scenario, revealing that quantum effects cause the initial static universe to become unstable, challenging its viability as a model for inflation.

Contribution

It provides a semi-classical quantum analysis showing the inherent instability of the Emergent Universe scenario over long timescales.

Findings

Quantum effects destabilize the static universe initial condition.

Wavepacket spreading prevents a well-defined initial state.

The scenario cannot reliably evolve into inflation over long periods.

Abstract

We perform a semi-classical analysis of the Emergent Universe scenario for inflation. Fixing the background, and taking the inflaton to be homogenous, we cast the inflaton's evolution as a one-dimensional quantum mechanics problem. We find that the tuning required over a long time scale for this inflationary scenario is unstable quantum mechanically. Considering the inflaton field value as a wavepacket, the spreading of the wavepacket destroys any chance of both starting and ending with a well-formed state. Thus, one cannot have an Einstein static universe to begin with that evolves into a well-defined beginning to inflation a long time later.