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Respectable Anti-Realism: Quantum Mechanics Turns Epistemic

2025-07-04 Education
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Essentia Foundation
Essentia Foundation
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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

Top Comments (10)

@IJustMadeAComment 2025-07-04

Can we please give it up to Hans Busstra (the interviewer)...! He has really expanded this channel.

85 1 replies
@PETEtheking 2025-07-04

This is how the magic is redeemed to stay in the worldview. It was thought to be dead at the hand of materialism and yet we had no idea how much he have yet to learn.

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@Ajith-c2h 2025-07-05

Any measurement using an instrument is a result of a duality - the activity being measured and the activity of the instrument. Then there is another duality happening when we interpret the measurement and give it a value. The information produced in this second step has no absolute basis - it is based on some axioms we have made up. And there are different sets of axioms possible (eg. moving from Newtonion to Einstein). So the end result is just knowledge with no absolute basis. Any theory based on any measurement (or direct observation) has an epistemic interpretation. It just so happens that for classical physics, the variation in the initial measurement is minimal with repeated observations, so all our axioms appear to be "true", getting challenged only when the magnitude changes (eg. modeling gravity going from local to global to solar system to cosmic scale). However, with quantum, the measurement varies largely with the observation, so it exposes the faults in our basic axioms (about existence of objects, particles, time) which were always there. The theories just predict what we can observe in the future, it's not a reflection of a reality. And there will always be incompleteness and inconsistency as we fuzz the line between the measurer and the measured.

14 1 replies
@ondudengrund 2025-07-04

Wow, this is so much more dynamic and captivating than any other "podcast like interviews/conversation" I have seen. Having a very interesting topic on top is not bad either : )

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@iramtauqir5333 2025-07-05

So good to hear, how what we know today as science were first a subject of philosophy. And how we need to approach interpretations of quantum mechanics through the philosophical method, i.e., coming up with a 'set' of reasonable assumptions which can be put to practical, physical tests as experiments in physics

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@rdeorca 2025-07-05

Art exists as a superposition of possibilities. Only the perception causes that superposition to collapse — into either temporary reality or permanent reality. This distinction is absolute. I look at temporary art: the collapsed superposition is temporary. I look at permanent art: the collapsed superposition is permanent, infinite.

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@builderofcastles 2025-07-06

The first, and largest mistake science has ever made is separating physics and metaphysics. Our world is continuum from spiritual to physical.

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@SQ_SherryQ 2025-07-06

I've needed this channel for my entire life .... WOW

1
@TimelineTheSchizoid 2025-07-08

"and as physicists, we are very unprepared" is such a massive understatement. The crisis in causality has brought out the worst in us, as some become dogmatic about the old models. Meanwhile people are taking the news and trying to run away with their personal takes on the matter.

1
@VoidSage-VishnuS 2025-10-17

The last take on physics as a partial solution to the puzzle with other parts really takes off the heaviness from my shoulder. 😊

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