Quantum cosmology: a review

TL;DR

This review explores quantum cosmology by emphasizing the role of inhomogeneity and many interacting degrees of freedom, connecting it with condensed matter and particle physics, and discussing new methodological developments.

Contribution

It introduces a novel perspective on quantum cosmology that moves beyond minisuperspace models, incorporating inhomogeneity and microscopic interactions in the space-time description.

Findings

New formulation of quantum cosmology emphasizing inhomogeneity

Connections established with condensed matter and particle physics systems

Discussion of methodological extensions for fundamental and effective theories

Abstract

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity: De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting "microscopic" degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.