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This paper challenges the prevailing view that Spacetime State Realism in Everettian Quantum Mechanics is dynamically local, arguing instead that its inherent non-separability complicates compatibility with relativistic causality. The analysis focuses on the ontological implications of reduced density matrices for non-localized regions, offering a rigorous theoretical critique relevant to foundational quantum mechanics research.
Snakes on a Hyper-Plane: Dynamical and Ontological Locality in Everettian Quantum Mechanics
arXiv:2609.07860v1 Announce Type: new Abstract: An apparently emerging consensus holds that Everettian Quantum Mechanics (EQM), in the Spacetime State Realism (SSR) version of Wallace and Timpson, involves ontological non-locality (i.e., non-separability) but is fully compatible with the dynamical notion of locality usually taken to be required by relativity. The claim of dynamical locality is based on the fact that the local beables postulated by the theory (namely, Reduced Density Matrices, RDMs, associated with localized regions) are not affected by interventions outside their past light cones. However, the theory's non-separability means that it posits non-local beables (namely RDMs for non-localized regions) in addition to the local ones. We argue here that the involvement of non-local beables introduces complications for extant formulations of dynamical locality and at least suggests, contrary to the emerging consensus, that SSR EQM should perhaps not be considered compatible with relativistic causality after all.
Abstract:An apparently emerging consensus holds that Everettian Quantum Mechanics (EQM), in the Spacetime State Realism (SSR) version of Wallace and Timpson, involves ontological non-locality (i.e., non-separability) but is fully compatible with the dynamical notion of locality usually taken to be required by relativity. The claim of dynamical locality is based on the fact that the local beables postulated by the theory (namely, Reduced Density Matrices, RDMs, associated with localized regions) are not affected by interventions outside their past light cones. However, the theory's non-separability means that it posits non-local beables (namely RDMs for non-localized regions) in addition to the local ones. We argue here that the involvement of non-local beables introduces complications for extant formulations of dynamical locality and at least suggests, contrary to the emerging consensus, that SSR EQM should perhaps not be considered compatible with relativistic causality after all.
arXiv:2609.07860 [quant-ph]
(or arXiv:2609.07860v1 [quant-ph] for this version)
https://doi.org/10.48550/arXiv.2609.07860 Focus to learn more arXiv-issued DOI via DataCite (pending registration)
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Full text under the publisher's open licence · 232 words
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