Dr. David Schmid, Dr. Lídia Del Rio and Hans Busstra explore a metaphysical shift that’s happening in the foundations of physics: the wave function is no longer regarded as something real, but just as a description of what we know about the world. In philosophical terms: the wave function is not ontic, but epistemic. And in more popular terms: the multiverse is science fiction, resting on a too-literal interpretation of a piece of mathematics called the Schrödinger equation.
Our previous video with Dr. Del Rio on the Frauchiger-Renner thought experiment:
https://www.youtube.com/watch?v=v7kxWT_zI60
Three other 'epistemicists', who’ve just been awarded a prestigious prize in the foundations of physics:
https://www.youtube.com/watch?v=NnAj66Z1kNQ
Chapters marks
00:00:00 Introduction
00:03:30 — When did it dawn on you that QM is weird?
00:05:54 — The quantum phenomena that still scare David
00:07:53 — How to account for non-locality
00:12:19 — "What are the symbols representing?"
00:15:34 — What is the wavefunction really?
00:17:00 — "The standard view we are taught in the classroom..."
00:19:23 — Classically explaining quantum
00:20:23 — On Wheeler's delayed choice experiment
00:28:38 — How to interpret the delayed choice experiment
00:32:56 — How can a single particle 'know' what's going on at both paths?
00:36:41 — Quantum phenomena that remain weird: contextuality
00:44:38 — What are the viable ontological explanations we have?
00:48:26 — Is there evidence for an epistemic interpretation?
00:52:56 — Understanding epistemic interpretations
00:57:28 — Are we in a new era of physics?
01:00:43 — Lídia on what constitutes measurement
01:04:36 — How relevant are these recent theoretical findings?
01:07:36 — Experiments with AI as an observer?
01:08:36 — David and Lídia on what consciousness is
01:13:51 — Closing thoughts
Links to relevant scientific work of Schmid and Del Rio:
Why interference phenomena do not capture the essence of quantum theory
L Catani, M Leifer, D Schmid, RW Spekkens
Quantum 7, 1119
A review and analysis of six extended Wigner's friend arguments
D Schmid, Y Yīng, M Leifer
arXiv preprint arXiv:2308.16220
Guiding our interpretation of quantum theory by principles of causation and inference
D Schmid, Thesis, University of Waterloo
https://uwspace.uwaterloo.ca/items/7aed8173-684a-40af-bff5-e625f29fe810
Thought experiments in a quantum computer,
Nuriya Nurgalieva, Simon Mathis, Lídia del Rio, Renato Renner:
https://arxiv.org/abs/2209.06236
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Interview content copyright by Essentia Foundation, 2025
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