On a Quantum Weyl Curvature Hypothesis

TL;DR

This paper explores a quantum extension of Penrose's Weyl curvature hypothesis, linking it to the initial quantum state of the universe and discussing potential implications for quantum gravity and cosmology.

Contribution

It introduces a quantum version of the Weyl curvature hypothesis and discusses its possible justification within a fundamental quantum gravity framework.

Findings

Estimates for the entropy of the universe are provided.

A quantum analogue of the Weyl curvature hypothesis is proposed.

Implications for recollapsing universes are discussed.

Abstract

Roger Penrose's Weyl curvature hypothesis states that the Weyl curvature is small at past singularities, but not at future singularities. We review the motivations for this conjecture and present estimates for the entropy of our Universe. We then extend this hypothesis to the quantum regime by demanding that the initial state of primordial quantum fluctuations be the adiabatic vacuum in a (quasi-) de~Sitter space. We finally attempt a justification of this quantum version from a fundamental theory of quantum gravity and speculate on its consequences in the case of a classically recollapsing universe.