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arXiv · 2205.15387

Unitarity and quantum resolution of gravitational singularities

Steffen Gielen·Lucía Menéndez-Pidal
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Abstract

We explore the consequences of requiring that quantum theories of gravity be unitary, mostly focusing on simple cosmological models to illustrate the main points. We show that unitarity for a clock that encounters a classical singularity at finite time implies quantum singularity resolution, but for a clock that encounters future infinity at finite time leads to a quantum recollapse. We then find that our starting point - assuming the general covariance of general relativity - is actually incompatible with general quantum unitarity: singularity resolution in quantum gravity can always be engineered by choosing the right clock, or avoided by using a different one.

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Steffen Gielen, Lucía Menéndez-Pidal. 2022-05-30. Unitarity and quantum resolution of gravitational singularities. https://doi.org/10.1142/s021827182241005x

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