Tim Maudlin is a philosopher of science specializing in the foundations of physics, metaphysics, and logic. He is a professor at New York University, a member of the Foundational Questions Institute, and the founder and director of the John Bell Institute for the Foundations of Physics.
In this very in-depth discussion, Tim and I probe the foundations of science through the avenues of locality and determinism as arising from the Einstein-Poldosky-Rosen (EPR) paradox and Bell’s Theorem. These issues are so intricate that even the Nobel Prize commitee incorrectly described the significance of Bell’s work in their press release for the 2022 prize in physics. Viewers motivated enough to think deeply about these ideas will be rewarded with a conceptually proper understanding of the nonlocal nature of physics and its manifestation in quantum theory.
Timothy Nguyen 
Dear Dr. Timothy Nguyen,
I have a few objections to Maudlin’s conclusion that Bell’s theorem proves the world to be non-local. I agree with his analysis of EPR and Bell, I think it’s the best you can find. Where I disagree with him is on the point of superdeterminism (the denial of Bell’s independence assumption). I am going to argue for the following points:
1. Bell’s statistical independence (SI) assumption is false in the general case, being incompatible with the laws of physics we know.
2. There are particular situations where SI is true, Maudlin’s examples with medical experiments on rats fall into that category.
3. I will provide a reasonable qualitative explanation of Bell correlations.
4. It is not true that superdeterminism is just a vague idea. There are pretty mature models based on it.
Point 1.
Let’s consider the case of a physical system composed of N particles which interact through a long range force. It could be charged particles as described by classical electromagnetism or massive particles as described by the general relativity or any other such theory. We know that the state of such a system must be a solution to the corresponding N-body problem. For example, two objects interacting gravitationally would have co-planar elliptical orbits, since this is how the solution to the 2-body problem looks like. Mathematically, you cannot split such a system into independent subsystems, since the state depends explicitly on all objects. If you assume that the two orbiting objects are independent you would conclude that their trajectories should be determined by the solution of the 1-body problem, which will be two lines, not two ellipses. Therefore, systems of interacting particles cannot have independent states. But matter consists of electrons and nuclei (atoms), which are both massive and charged, therefore, in the general case, Bell’s independence assumption would be false. Alice and Bob and their detectors and the particle source must satisfy together the equations of electromagnetism (Maxwell) and gravity (Einstein) so, the hidden variable, which is expected to be determined by the state of the source, cannot be independent of the states of the detectors. Therefore Bell’s theorem cannot rule out classical electromagnetism or general relativity as a possible theory underlying quantum mechanics.
Point 2.
In the macroscopic limit the electromagnetic interactions between electrons and nuclei cancel out, giving Newtonian mechanics with contact forces only. Since medical tests on rats are focused on macroscopic properties (like the concentration of some substance in blood) we can ignore the long-range electromagnetical interactions, so Bell’s independence assumption is true in this case. Science is saved.
Point 3.
a. The EM field configuration at the locus of the emission inside the source is a function of global charge configuration and momenta (Maxwell’s equations).
b. That EM field configuration determines the acceleration of the electron which is about to emit the entangled pair via the Lorentz force.
c. The polarization of the emitted photons are determined by the electron undergoing acceleration (b).
From a, b and c we get that the hidden variables (polarizations) depend on the states of the detectors. So, the source „knows” what the detectors are doing so it can supply suitable pairs to violate the inequalities.
Point 4.
We have a few research programs based on superdeterminism, together with some recent papers:
– ’t Hooft’s cellular automaton interpretation
Explicit construction of Local Hidden Variables for any quantum theory up to any desired accuracy
https://arxiv.org/abs/2103.04335
– Wetterich’s probabilistic cellular automaton
Probabilistic cellular automata for interacting fermionic quantum field theories
https://arxiv.org/abs/2007.06366
– Stochastic electrodinamics
– Stochastic Electrodynamics: The Closest Classical Approximation to Quantum Theory
– https://arxiv.org/abs/1903.00996
Thanks for this great interview! In case you haven’t seen it already, you should check the video of an old conference by Sidney Coleman entitled “Quantum mechanics in your face”.
He addresses several points which you also covered with Maudlin, including:
– the GHZ version of Bell’s inequality (which was a big revelation for me as it was the first time I really understood Bell’s argument)
– the notion of “interpretation” where he cites a great quote by Feynman (“The question is not how to interpret QM, it is how to interpret classical physics in the light of quantum theory”)
He does not show Mermin’s diagram, unfortunately.
There is, however, a comment he makes which I can’t square with Maudlin’s exposition. Coleman claims that the EPR and Bell experiments do not have any “spooky action at a distance”. In other words, he seems to deny that experiments show that QM is nonlocal, thus flagrantly contradicting Maudlin. But I tend to agree with Maudlin, so… (I hesitate to write this): is Coleman wrong?
Timothy Nguyen is certainly no authority on physics, and he continues to invite cranks onto his podcast. No serious scientist entertains Maudlin for five minutes. The Standard Model is a field theory, not a particle theory. The physics is completely local and not even very surprising. Furthermore, his interview with CS major Scott Aaronson reveals that he knows nothing about issues of renormalization and the reasons why the Wightman and Hagg-Kastler axioms have not been generally accepted. QFT operators are more naturally nonlinear functionals of source functions, not linear OVDs. The idea that we can avoid chaos to control infinite-dimensional fields for error-corrected quantum computation is utterly bonkers. Hit the books, my friend.