Quantum geometry and black holes

TL;DR

This paper explores loop quantum gravity techniques applied to spherically symmetric black holes, focusing on quantization methods, singularity resolution, and potential observational effects like quasinormal modes.

Contribution

It introduces a novel approach using inhomogeneous slicings and Abelianized constraints for quantum black holes, extending previous loop quantum gravity models.

Findings

Singularities are replaced by space-time extensions.

Quantization methods enable defining operators for space-time metrics.

Potential observational signatures in quasinormal modes.

Abstract

We summarize our work on spherically symmetric midi-superspaces in loop quantum gravity. Our approach is based on using inhomogeneous slicings that may penetrate the horizon in case there is one and on a redefinition of the constraints so the Hamiltonian has an Abelian algebra with itself. We discuss basic and improved quantizations as is done in loop quantum cosmology. We discuss the use of parameterized Dirac observables to define operators associated with kinematical variables in the physical space of states, as a first step to introduce an operator associated with the space-time metric. We analyze the elimination of singularities and how they are replaced by extensions of the space-times. We discuss the charged case and potential observational consequences in quasinormal modes. We also analyze the covariance of the approach. Finally, we comment on other recent approaches of quantum black holes, including mini-superspaces motivated by loop quantum gravity.