Month: January 2022

David Wallace
Pittsburg University

Quantum gravity at low energies

I provide a conceptually-focused presentation of `low-energy quantum gravity’ (LEQG), the effective quantum field theory obtained from general relativity and which provides a well-defined theory of quantum gravity at energies well below the Planck scale. I emphasize the extent to which some such theory is required by the abundant observational evidence in astrophysics and cosmology …

David Wallace
Pittsburg University

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Poster for Don Marolf's virtual seminar: Spacetime wormholes, superselection sectors, and ensembles in quantum gravity: An Overview

Don Marolf
University of California Santa Barbara

Spacetime wormholes, superselection sectors, and ensembles in quantum gravity: An Overview

Don Marolf will review and summarize recent developments regarding spacetime wormholes in the gravitational path integral and their implications for the existence of a certain notion of “superselection sectors” in quantum gravity.  The existence of such sectors implies that, in certain contexts, we can think of quantum gravity as describing a statistical ensemble of theories.  …

Don Marolf
University of California Santa Barbara

Spacetime wormholes, superselection sectors, and ensembles in quantum gravity: An Overview Read More »

Chris Smeenk Joins QISS. Expanded Visiting Philosophers Program.

We are happy to welcome Chris Smeenk to the consortium. Chris is the director of the Rotman Institute of Philosophy and professor of philosophy at Western University. In partnership with the Rotman Institute of Philosophy the current QISS visiting program aimed at philosophers will be significantly expanded, with the aim to train a new generation of philosophers of …

Chris Smeenk Joins QISS. Expanded Visiting Philosophers Program. Read More »

Richard Howl
Oxford University

Testing quantum gravity with non-Gaussianity and a Bose-Einstein condensate

Due to rapid progress in experimental quantum information science, a table-top test of quantum gravity may soon be possible. A promising possibility is to place two micro-solids in a spatial superposition and separable state. If, after a short time, entanglement between the micro-solids is observed then this could provide evidence of a quantum theory of gravity, assuming all other interactions can be neglected and that gravity provides a local interaction. These proposals have raised a number of questions, such as whether entanglement generation would really provide a test of quantum gravity and whether the experiments are feasible in the near term. Here, we consider whether an alternative signature of quantum gravity to entanglement could be used for a table-top test, and an alternative experimental setting. Specifically, we consider non-Gaussianity rather than entanglement and how this could be searched for in a Bose-Einstein condensate (BEC) to evidence quantum gravity. We discuss whether using non-Gaussianity and a BEC could provide any advantages to entanglement and micro-solids.

Laurent Freidel
Perimeter Institute

The nature of quantum entanglement in gravity: a tale about Noether and subsystems

In this talk, I will present a new perspective about decomposing gravitational systems into subsystems. I will explain what is the nature of entanglement of gravitational subsystems and the importance of local symmetries. I will emphasize the central role of the corner symmetry group in capturing all the necessary data needed to glue back seamlessly quantum spacetime regions. I will explain some of the key results we have achieved in the construction of the representations of these groups. If time permits, I will present new results about the canonical description of open gravitational systems and what it teaches us about the nature of quantum gravitational radiation.

Emily Adlam
Western University, Rotman Institute of Philosophy

Contextuality, Fine-tuning and Teleological Explanation

In this talk I will assess various proposals for the source of the intuition that there is something problematic about contextuality, and argue that contextuality is best thought of in terms of fine-tuning. I will suggest that as with other fine-tuning problems in quantum mechanics, this behaviour can be understood as a manifestation of teleological features of physics. I will also introduce several formal mathematical frameworks that have been used to analyse contextuality and discuss how their results should be interpreted.