SOPhiA 2022

Salzburgiense Concilium Omnibus Philosophis Analyticis

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Programme - Talk

How Do Quantum Systems Persist?
(Philosophy of Science, English)

Persistence is a central issue of metaphysics, and despite the development of several formal accounts in recent years, only a handful of papers have been dedicated to investigating the persistence of quantum systems. I argue that while the extensive literature on persistence has proved effective for classical systems, it does not successfully extend its application to the quantum domain.



The difficulty arises due to quantum position indefiniteness. As a consequence of superposition, entanglement, and incompatible observables, a quantum systems can fail to have definite exact location in spacetime -- a feature that plays an indispensable role in formal accounts of persistence. According to the traditional definition: an object persists if and only if its spatiotemporal path is non-achronal (where path is the union of regions at which the object is exactly located). This means that a persisting object is exactly located at no less than two instants of time. A quantum system that exists for a duration of time, without having any exact location at all, will have an empty path -- the system cannot be taken to persist. Evidently, the traditional account of persistence breaks down in the quantum domain.

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Pashby (2016) recognises this difficulty and provides an alternative notion of exact location: a quantum system is exactly located at a region if this is the minimal region at which it is entirely located. This modification allows him to continue to utilise the traditional definition of persistence. However, I argue that the account faces a serious co- and multilocation challenge to which there is no immediate resolution, and furthermore fails to account for the persistence of certain systems. This ultimately makes the account an unattractive candidate for quantum persistence. The question remains: is it possible to modify the traditional framework to accommodate cases of position indefiniteness or should quantum persistence be defined in completely different terms?

Chair: Wojciech Grabon
Time: 12:00-12:30, 09. September 2022 (Friday)
Location: SR 1.004
Remark: (Online Talk)

Maria Norgaard 
(University of Geneva, France)



Testability and Meaning deco