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Decoherence, the measurement problem and realism

Kearney, Peter (2020) Decoherence, the measurement problem and realism. [Preprint]


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I argue that decoherence can be seen as resolving the measurement problem, provided that one is willing to accept two key features of the resolution. The first is that the proposed resolution addresses only the “generic” measurement problem – “why do we get definite measurement outcomes?”, rather than the “specific” measurement problem — “why do we get the particular outcome we do?” The second feature of the proposed resolution is that measurement outcomes are observer-dependent, that is, measurement outcomes are only defined relative to a particular observational context, predicated on a subsystem-environment split and a restriction to certain local observables.

I then consider whether this resolution can be considered a “realist” one. I suggest that interpretations of quantum mechanics can usefully be characterised along a spectrum as more or less realist, or correlatively, less or more observer-dependent. As one moves along the spectrum an increasingly objective viewpoint is adopted, in the sense of independence from any observational context.

I argue that the decoherence approach to measurement outcomes lies some distance along the realist spectrum, distinguishing it from purely instrumentalist or operationalist interpretations. However, the decoherence approach currently falls short of the ideal of “Archimedean Realism”, which seeks an entirely observer-independent account of why the particular observational perspectives that we occupy are constrained in the way they seem to be. I suggest that to achieve that ideal the decoherence approach would need to be supplemented with additional physical structure which singles out some Hilbert space factorisations as physically preferred.

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Item Type: Preprint
Keywords: quantum theory, decoherence, measurement problem, realism
Subjects: Specific Sciences > Physics
Specific Sciences > Physics > Quantum Mechanics
Depositing User: Dr Peter Kearney
Date Deposited: 06 Sep 2023 16:49
Last Modified: 06 Sep 2023 16:49
Item ID: 22497
Subjects: Specific Sciences > Physics
Specific Sciences > Physics > Quantum Mechanics
Date: 8 November 2020

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