Harmonic cosmology: How much can we know about a universe before the big bang?

TL;DR

This paper explores the potential to understand the universe before the big bang through loop quantum cosmology, highlighting the challenges in correlating pre- and post-big bang quantum fluctuations due to observational limitations.

Contribution

It demonstrates that quantum fluctuations before the big bang are generally uncorrelated with those after, emphasizing the difficulty of empirically probing pre-big bang conditions.

Findings

Quantum fluctuations before the big bang are unrelated to those after.

Precise observations are required to determine pre-big bang quantum fluctuations.

Loop quantum cosmology provides an exactly solvable model for this analysis.

Abstract

Quantum gravity may remove classical space-time singularities and thus reveal what a universe at and before the big bang could be like. In loop quantum cosmology, an exactly solvable model is available which allows one to address precise dynamical coherent states and their evolution in such a setting. It is shown here that quantum fluctuations before the big bang are generically unrelated to those after the big bang. A reliable determination of pre-big bang quantum fluctuations would require exceedingly precise observations.