Schrödinger's Black Hole Cat

Abstract

In the absence of a fully-fledged theory of quantum gravity, we propose a "bottom-up" framework for exploring quantum-gravitational physics by pairing two of the most fundamental concepts of quantum theory and general relativity, namely quantum superposition and spacetime. We show how to describe such "spacetime superpositions" and explore effects they induce upon quantum matter. Our approach capitalizes on standard tools of quantum field theory in curved space, and allows us to calculate physical observables like transition probabilities for a particle detector residing in curvature-superposed de Sitter spacetime, or outside a mass-superposed black hole. Crucially, such scenarios represent genuine quantum superpositions of spacetimes, in contrast with superpositions of metrics which only differ by a coordinate transformation and thus are not different according to general relativity.

arXiv comment12 pages, Honourable Mention in the Gravity Research Foundation 2022 Awards for Essays on Gravitation

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Cited by in corpus (6)

• Quantum superpositions of Minkowski spacetime
• Quantum Reference Frames at the Boundary of Spacetime
• Identification is Pointless: Quantum Coordinates, Localisation of Events, and the Quantum Hole Argument
• Entanglement harvesting in quantum superposed spacetime
• Quantum conformal symmetries for spacetimes in superposition
• Accelerated detector in a superposed spacetime