Quantum Cosmic No-Hair Theorem and Inflation

TL;DR

This paper explores how quantum effects during inflation rapidly erase initial conditions, making the Bunch-Davies vacuum a strong attractor, with implications for bouncing universes where this process is less efficient.

Contribution

It extends the inflationary no hair theorem into the quantum regime, demonstrating rapid erasure of initial conditions and analyzing differences in bouncing universe scenarios.

Findings

Quantum inflation erases initial distortions in about 10 e-folds.

The Bunch-Davies vacuum acts as a strong quantum attractor.

Bouncing universes retain initial conditions longer due to less efficient quantum balding.

Abstract

We consider implications of the quantum extension of the inflationary no hair theorem. We show that when the quantum state of inflation is picked to ensure the validity of the EFT of fluctuations, it takes only ${\cal O}(10)$ efolds of inflation to erase the effects of the initial distortions on the inflationary observables. Thus the Bunch-Davies vacuum is a very strong quantum attractor during inflation. We also consider bouncing universes, where the initial conditions seem to linger much longer and the quantum `balding' by evolution appears to be less efficient.