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arXiv · 2404.00159

What an event is not: unravelling the identity of events in quantum theory and gravity

Anne-Catherine de la Hamette·Viktoria Kabel·Časlav Brukner
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Abstract

We explore the notion of events at the intersection between quantum physics and gravity, inspired by recent research on superpositions of semiclassical spacetimes. By going through various experiments and thought experiments -- from a decaying atom, to the double-slit experiment, to the quantum switch -- we analyse which properties can and cannot be used to define events in such non-classical contexts. Our findings suggest an operational, context-dependent definition of events which emphasises that their properties can be accessed without destroying or altering observed phenomena. We discuss the implications of this understanding of events for indefinite causal order as well as the non-absoluteness of events in the Wigner's friend thought experiment. These findings provide a first step for developing a notion of event in quantum spacetime.

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Anne-Catherine de la Hamette, Viktoria Kabel, Časlav Brukner. 2024-03-29. What an event is not: unravelling the identity of events in quantum theory and gravity. https://arxiv.org/abs/2404.00159

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