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Particles, fields, and the measurement of electron spin

Sebens, Charles T. (2021) Particles, fields, and the measurement of electron spin. Synthese, 198 (12). pp. 11943-11975. ISSN 0039-7857. doi:10.1007/s11229-020-02843-5.

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This article compares treatments of the Stern–Gerlach experiment across different physical theories, building up to a novel analysis of electron spin measurement in the context of classical Dirac field theory. Modeling the electron as a classical rigid body or point particle, we can explain why the entire electron is always found at just one location on the detector (uniqueness) but we cannot explain why there are only two locations where the electron is ever found (discreteness). Using non-relativistic or relativistic quantum mechanics, we can explain both uniqueness and discreteness. Moving to more fundamental physics, both features can be explained within a quantum theory of the Dirac field. In a classical theory of the Dirac field, the rotating charge of the electron can split into two pieces that each hit the detector at a different location. In this classical context, we can explain a feature of electron spin that is often described as distinctively quantum (discreteness) but we cannot explain another feature that could be explained within any of the other theories (uniqueness).

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Additional Information:© 2020 Springer Nature Switzerland AG. Received 12 March 2020; Accepted 20 August 2020; Published 03 September 2020. Thank you to Valia Allori, Jacob Barandes, Jeffrey Barrett, Mario Hubert, and the anonymous reviewers for helpful feedback and discussion.
Subject Keywords:Electron spin; Dirac equation; Dirac field; Stern–Gerlach experiment
Issue or Number:12
Record Number:CaltechAUTHORS:20200922-132154675
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Official Citation:Sebens, C.T. Particles, fields, and the measurement of electron spin. Synthese 198, 11943–11975 (2021).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105473
Deposited By: Tony Diaz
Deposited On:22 Sep 2020 20:27
Last Modified:04 Oct 2021 22:24

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