Rodolfo Gambini

Quantum scalar field in quantum gravity with spherical symmetry

This is a summary of the talk presented by one of us in Loops 2011. We discuss the application of the uniform discretization approach to spherically symmetric gravity coupled to a spherically symmetric scalar field.

A scenario for black hole evaporation on a quantum geometry

We incorporate elements of the recently discovered exact solutions of the quantum constraints of loop quantum gravity for vacuum spherically symmetric space-times into the paradigm of black hole evaporation due to Ashtekar and Bojowald. The quantization of the area of the surfaces of symmetry of the solutions implies that the number of nice slices that can be fit inside the black hole is finite. The foliation eventually moves through the region where the singularity in the classical theory used to be and all the particles that fell into the black hole due to Hawking radiation emerge finally as a white hole. This yields a variant of a scenario advocated by Arkani-Hamed {\em et al.} Fluctuations in the horizon that naturally arise in the quantum space time allow radiation to emerge during the evaporation process due to stimulated emission allowing evaporation to proceed beyond Page time without reaching the maximum entanglement limit until the formation of the white hole. No firewalls nor remnants arise in this scenario.

Fundamental Loss of Quantum Coherence from Quantum Gravity

We discuss the fundamental loss of unitarity that appears in quantum mechanics when one uses physically realistic devices to measure time and space. The effect is independent of any interaction with the environment and appears in addition to any usual environmental decoherence. We discuss the conceptual and potential experimental implications of this process of decoherence.

Black holes in loop quantum gravity

We summarize recent results concerning the quantization of the complete extension of the Schwarzschild space-time using spherically symmetric loop quantum gravity. We find an exact solution of the polymerized theory, that is expected to capture features of the semi-classical limit. The singularity is eliminated but the space-time still contains a horizon. Although the solution is known partially numerically and therefore a proper global analysis is not possible, a global structure akin to a singularity-free Reissner-Nordstrom space-time including a Cauchy horizon is suggested.

Canonical quantum gravity and consistent discretizations

This paper covers some developments in canonical quantum gravity that occurred since ICGC-2000, emphasizing the recently introduced consistent discretizations of general relativity.