Respectable Anti-Realism: Quantum Mechanics Turns Epistemic

Video Description

Hans Busstra and Dr. Lídia del Rio talk to Dr. Matthew Leifer, Assistant Professor of Physics at Chapman University, about the epistemic interpretation of quantum mechanics. Classically, when physicists call themselves ‘realists’ they mean that we should assume that a physical, observer-independent universe is fundamental. But if this counts as realism, anti-realism is perhaps the more respectable position. Leifer points, for instance, to ‘Bell-Wigner mashups’: thought-experiments that entangle different observers to arrive at disturbing consequences; for instance, that there is no ‘absoluteness of facts’ for all observers, in a classical sense. Our previous video on the Frauchiger-Renner thought-experiment with Lídia del Rio: https://youtu.be/v7kxWT_zI60 Selected publications by Matthew Leifer: Leifer, Matthew S. “Uncertainty from the Aharonov–Vaidman identity.” Quantum Studies: Mathematics and Foundations, vol. 10, pp. 373–397, 2023. PDF/Abstract (arXiv) mattleifer.info+12mattleifer.info+12arxiv.org+12 Catani, Lorenzo; Leifer, Matthew S. “A mathematical framework for operational fine tunings.” Quantum, vol. 7, article 948, 16 Mar 2023. PDF/DOI/ArXiv mattleifer.info+1quantum-journal.org+1 Catani, Lorenzo; Leifer, Matthew S.; Scala, Giovanni; Schmid, David; Spekkens, Robert W. “What is nonclassical about uncertainty relations?” Physical Review Letters, vol. 129, iss. 24, 2022. Abstract (via arXiv) chapman.edu+8arxiv.org+8mattleifer.info+8 Leifer, Matthew S.; Duarte, Cristhiano. “Noncontextuality inequalities from antidistinguishability.” Physical Review A, vol. 101, iss. 6, p. 062113, 2020. PDF/Abstract (arXiv) fetzer-franklin-fund.org+2mattleifer.info+2arxiv.org+2 Timestamps: 0:00 Introduction 3:06 What is classicality? 5:56 Classical information vs quantum information 11:42 Experimental metaphysics 14:18 Metaphysical implications of Bell's work 18:42 What is realism? 21:51 Realism vs anti-realism 25:58 The internal realism of theories 29:51 How the public understands quantum mechanics 32:14 Interpreting quantum mechanics is like tightrope walking 34:51 On naive realism 38:41 How would you define physicalism? 44:33 On mind and consciousness 48:19 Panpsychists have physics-envy 49:25 It's unclear what the Copenhagen interpretation is... 56:54 On the quantum-classical cut 1:09:29 Craziness derived from sensible premises 1:14:50 Why 'for all practical purposes' is not a solution 1:21:44 On Bell-Wigner mashups 1:30:37 What constitutes an observer? 1:33:53 Matt on the meaning of quantum mechanics and the limits of physics. All music licensed under Storyblocks and Soundstripe All stock footage licensed under Storyblocks. Used under fair-use: fragment from "Memento", Christopher Nolan, 2000 Interview content copyright by Essentia Foundation, 2025 www.essentiafoundation.org