Tim Maudlin on Quantum Hidden Variables

New Sean M. Carroll podcast:

Mindscape 241 | Tim Maudlin on Locality, Hidden Variables, and Quantum Foundations

Last year's Nobel Prize for experimental tests of Bell's Theorem was the first Nobel in the foundations of quantum mechanics since Max Born in 1954. Quantum foundations is enjoying a bit of a resurgence, inspired in part by improving quantum technology but also by a realization that understanding quantum mechanics might help with other problems in physics (and be important in its own right). Tim Maudlin is a leading philosopher of physics and also a skeptic of the Everett interpretation. We discuss the logic behind hidden-variable approaches such as Bohmian mechanics, and also the broader question of the importance of the foundations of physics.

Maudlin is one of the more sensible philosophers of Physics. However, I must caution you.

Carroll is a big believer in Many-worlds theory. Maudlin is not. Maudlin pushes Bohmian mechanics.

They both say the Nobel Prize committee, and a lot of others, get Bell's theorem wrong. I explained here why the Nobel site is correct.

I do not agree that the 2022 Nobel Prize has anything to do with quantum foundations. The prize citation said that it was for experimental work only. Those experiments only confirmed what everyone thought for 90 years.

Maudlin says many Bohmians take pride in the theory being just an interpretation of QM, making all the same predictions. However he argues that new research may show a way for Bohmian mechanics to signal faster than light. If so, and experimentally verified, it would contradict QM and relativity.

Carroll and Maudlin both complain that Physics departments do not take these foundational issues seriously. That is because very little worthwhile work has emerged.

They discuss whether electrons and photons are really particles or fields. Maudlin says some believe that the fermions are particles, while the bosons are fields. I am not sure it matters. They are either particles that act like fields, or fields that act like particles.

R.P. Feynman was famously a big believer in particles, as illustrated by Feynman diagrams. Other say the diagrams are just shorthands for field theory calculations. Carroll claims that Feynman was motivated in part by field theories having a vacuum energy, and dark energy had not been discovered yet. Maudlin had not heard that. I am skeptical.

Maudlin made some sensible comments about the arrow of time. I expected Carroll to disagree, but he chickened out.

My main issue with Maudlin is with Bohmian QM. He says that the experts rejected it for faulty reasons. I say they were legitimate reasons.

Bohmian QM is nonlocal. In it, an electron has a position along with a ghost function some distance away. You get the satisfaction of saying the election has a definite position, but it does not do you any good because it is controlled by the ghost function. You can never study an electron in isolation because there is some ghost a thousand miles away that you know nothing about. And the electron might not really be in its Bohmian position.

Carroll said that "hidden variables" is a misnomer because they are observable, not hidden. It is not true. The electron ghost cannot be observed. Science would never make any progress if particle were really controlled by distant ghosts. The whole theory is like having an equation with a mathematical solution that must be rejected for being unphysical.

Maudlin would answer that Bell's theorem, along with the Bell test experiments, have proved that QM is nonlocal, so I should just get over it and embrace nonlocality.

Nope. Bell showed that a theory making certain assumptions must give results differing standard QM results, and therefore be false. Those assumptions are locality, hidden variables, no retrocausality, no superdeterminism, and single outcomes.

Maudlin would say that those are all reasonable assumptions for any acceptable theory, except for locality, so locality must be wrong.

Carroll says that single outcomes must be wrong, so he believes in Many-worlds.

I say hidden variables only make sense in a classical pre-quantum theory, and that is the wrong assumption.

The hidden variable theory assumption is sometimes called realism, commuting variables, classical mechanics, or Bell's beables. The idea is that an intuitively realistic theory would allow the theory to be defined by commuting variables, so that knowing one does not interfere with knowing the others. QM famously has position and momentum as noncommuting observables, so you cannot know both at the same time.

The Einstein EPR Elements of Physical Reality folks say that a theory with Heisenberg uncertainty is incomplete. The Bell-heads say that they are just assuming objective reality.

That would have seemed like a reasonable assumption before Heisenberg declared otherwise in 1925.

Heisenberg uncertainty, and noncommuting observables, seem strange at first, but we see something similar in all wave phenomena. Light and electrons are readily observed to act like waves. So I accept that. All the alternatives, such as action-at-a-distance, are so bizarre that I do not even see how science would develop if they were true.

Mainstream Physics textbooks say QM is obviously right, and there is no need to bother with the sort of theories that Bohm and Bell were pursuing.

The Need for Interpretations of Relativity

I posted comments on a Sabine Hossenfelder video on relativity a few months ago. Now here is another:

The REAL Reason You Don't Understand Relativity

Think Relativity is confusing? Well, it's not just you -- even the experts can't seem to agree on its meaning, and often get basic facts about the formalism completely wrong. Here, we critique one such renowned professional who, in claiming to be clarifying the standardized theory of relativity, turns out to actually be promoting a misguided personal interpretation. What is this expert's confusion exactly, and why are such misconceptions so prevalent amongst the physics community?

Indeed, be cautious of posturers, gaslighters, stigmatizers, and Giordano-Bruno-burners who want to convince you that your inability to understand Relativity stems from your own deficient reasoning -- because when even the experts can't agree, you know there is something up...

It makes an argument that quantum mechanics is mysterious, so we have multiple interpretations, and we need the same for relativity.

You might say that the textbooks already provide two interpretations: Lorentzian and Einsteinian.

It points out that Einstein's interpretation is confused. He rejected the aether, and then endorsed it years later. He rejected geometrization of spacetime. He had a peculiar explanation of the twin paradox.

It also finds Hossenfelder\s explanation confusing.

I am not sure where this guy is going with this argument. He promises another video to explain.

The Wikipedia page on Lorentz ether theory says that it pre-dates Einstein and is experimentally indistinguishable from Einstein's special relativity. So you could say that these are two different interpretations of the same theory.

But then I would say that Minkowski's geometrical spacetime theory is another interpretation still. It is more different from Einstein's, as Einstein's is from Lorentz's. Maybe these should be understood as three different interpretations of the same theory.

Wikipedia says:

In the absence of any way to experimentally distinguish between LET and SR, SR is widely preferred over LET, due to the superfluous assumption of an undetectable aether in LET, and the validity of the relativity principle in LET seeming ad hoc or coincidental.

Einstein is indeed preferred over Lorentz, but I don't think that the reasoning is correct. Lorentz was the one to say that the aether was superfluous. And it was Einstein who made the relativity principle a postulate, instead of justifying it.

People don't like to talk about interpretations of relativity, because it undermines Einstein's genius. If all Einstein did was to find another interpretation of an accepted theory of Lorentz, then what is the big deal?
 

Sometimes the explanation is that Lorentz based his theory on Michelson-Morley and other experiments, and so his theory was "ad hoc or coincidental". Einstein based his on Lorentz's principles, and so his was paradigm shifting and revolutionary. At the time, everyone thought that Einstein's theory was just an elaboration of Lorentz's ideas.

Here is a Wikipedia explanation on why the FitzGerald contraction was ad hoc:

This hypothesis was partly motivated by Oliver Heaviside's discovery in 1888 that electrostatic fields are contracting in the line of motion. But since there was no reason at that time to assume that binding forces in matter are of electric origin, length contraction of matter in motion with respect to the aether was considered an Ad hoc hypothesis.

No reason to think? FitzGerald and Lorentz appear to have thought that, and it is true that the binding forces in solids are electric. I would call it brilliant reasoning, not ad hoc.

Minkowski spacetime is widly preferred over Einstein's interpretation, as it gives a coherent geometrical view that explains the paradoxes. It was based on Lorentz and Poincare, not Einstein.

The key principle that is usually used to distinguish Einstein from Lorentz is to say there is no aether, which means that there is no preferred frame. Both Lorentz and Einstein accept the relativity principle, so all inertial frames are equivalent, but Lorentz might prefer one somehow. Einstein would say that none can be preferred.

I am not sure that this reflects Lorentz's and Einstein's views accurately, but regardless, there is no scientific difference. It does not mean anything to say that there is no preferred frame. It is only meaningful to say that there is a symmetry between the frames.

The Cosmic Microwave Background radiation gives a preferred frame for what is motionless. It is not a counterexample to special relativity. So it is confusing to say that special relativity does not allow a preferred frame.

It is also said that Lorentz had an electromagnetic interpretation, while Einstein had a kinematic interpretation. Lorentz believed that electromagnetism underlies everything. Poincare wrote in 1905 that he was adopting an interpretation that relativity was about how we measure space and time, and that this was different from Lorentz's interpretation. So Poincare was the first with a spacetime interpretation.

The Minkowski geometrical interpretation says that all the special relativity mysteries derive from the non-euclidean geometry of spacetime. That has dominated the textbooks since about 1910, even though Einstein spoke out against it.

I guess that relativity has three interpretations. Lorentz relativity, based on Maxwell's equations and Michelson-Morley experiment. Einstein relativity, based on postulating what Lorentz and Poincare proved. Poincare-Minkowski relativity, based on a non-euclidean geometry on spacetime.

Here is a 2014 paper on Poincaré on clocks in motion, that was just posted online. It goes into Poincare's unpublished writings in detail, and argues that he had a somewhat different interpretation of relativity from Einstein and Minkowski.

How the Left is Corrupting Science

Evolutionists used to complain endlessly on how religious believers were corrupting science by promoting Intelligent Design. It was all a big hoax. It never got into the schools or academia in any significant way.

The Skeptical Inquirer has a new paper:

Biology faces a grave threat from “progressive” politics that are changing the way our work is done, delimiting areas of biology that are taboo and will not be funded by the government or published in scientific journals, stipulating what words biologists must avoid in their writing, and decreeing how biology is taught to students and communicated to other scientists and the public through the technical and popular press. We wrote this article not to argue that biology is dead, but to show how ideology is poisoning it. The science that has brought us so much progress and understanding—from the structure of DNA to the green revolution and the design of COVID-19 vaccines—is endangered by political dogma strangling our essential tradition of open research and scientific communication. And because much of what we discuss occurs within academic science, where many scientists are too cowed to speak their minds, the public is largely unfamiliar with these issues. Sadly, by the time they become apparent to everyone, it might be too late.

Scientific papers are being blocked because of politics. We know the problem is bad, because papers are even being retracted because of leftist politics. Quillette reports:

In 2020, five psychologists asked the editors of PNAS to retract their study of racial bias in police shootings. PNAS, which stands for the Proceedings of the National Academies of Science, is one of the most prestigious multidisciplinary journals in the world. Retraction is an outcome no scholar wishes to experience because it signifies a serious research error and, as such, entails considerable reputational damage.

Some observers have suggested that the retraction was politically motivated. The study, which showed no evidence of racial bias in police shootings, had been used in political debates in ways that challenged calls for radical police reform; calls that had grown louder in the aftermath of the murder of George Floyd. Heather Mac Donald, a research fellow at the conservative Manhattan Institute, claimed the article was retracted because she had cited it in a congressional hearing and in essays published in the Wall Street Journal and other right-leaning media outlets.

Another paper was retracted because it drew attention to Rapid Onset Gender Dysphoria (ROGD).

This is being compared to Soviet Lysenkoism. At least the Soviets thought that what they were doing was right. And they were not grooming small children.

Carroll says Many-Worlds is Falsifiable

Physicist Sean M. Carroll is a guest on another podcast, and goes into detail on some of his favorite topics, like the Many-Worlds theory of quantum mechanics. If you are a fan of his, you have probably heard it all. I just want to mention a couple of things where he is way off base.

He says there are a lot of "bad worries" about Everett MW, such as it being not falsifiable. It postulates other worlds that we cannot visit.

His answer is that you can believe in the worlds because they can be described by the Schroedinger equation. MW could be falsified by disproving that equation. He then refuses to give any more arguments against MW, as he just wants to say what is good about it.

This argument is really stupid. Say you have a cat in a superposition of alive and dead. Then you observe it dead. QM nows says you have a wave function of a dead cat. MW says you still have a live cat in a parallel universe.

Somehow that live cat has to be postulated and taken on faith, as it is impossible to observe.

Carroll would presumably say that QM cannot predict whether the cat is alive or dead, so MW is not a postulate, but just continuing to believe in that uncertainty even after you determine that the cat is dead.

Got it? Idiotic.

Many-Worlds is just like the following fantasy: There is no such thing as probability. Every time you say that there is a chance of several things happening, and you see one, then what really happened was that the world split into parallel worlds, with each thing happening in its own world. All things happened, and probability is just the illusion of getting disconnected from the other worlds.

He goes on the argue that last years Nobel Prize committee got this wrong:

The Northern Irish physicist John Stewart Bell (1928–1990), who worked at CERN, the European particle physics laboratory, took a closer look at the problem. He discovered that there is a type of experiment that can determine whether the world is purely quantum mechanical, or whether there could be another description with hidden variables. If his experiment is repeated many times, all theories with hidden variables show a correlation between the results that must be lower than, or at most equal to, a specific value. This is called Bell’s inequality.

And also:

John Clauser developed John Bell’s ideas, leading to a practical experiment. When he took the measurements, they supported quantum mechanics by clearly violating a Bell inequality. This means that quantum mechanics cannot be replaced by a theory that uses hidden variables.

This is saying that Bell showed how QM can be distinguished from classical theories, and the prize was given for the experiment confirming QM.

Carroll says this is wrong because Bell believed in the Bohmian hidden variable theory. He says that theory is wrong, but some people believe in it, so experiments do not rule it out.

Bell's Theorem is a mathematical theorem, so it has technical hypotheses. Violating the hypotheses gives loopholes. The main ones are: action-at-a-distance, retrocausality, multiple outcomes, and superdeterminism. These are all outlandish, and my guess is that no one on the Nobel committee believes in any of them. The Nobel description is correct. It just skips over the unphysical loopholes.

There is no need to go into any of this in a Nobel press release. They are clear that the prize is only being given for experimental work, and not for any endorsement of theoretical interpretaions by Bell or anyone else. Clauser thought that he would disprove QM, but instead he confirmed it.

How Max Born got a Nobel Prize

New paper, also here:

Rovelli, Carlo and Heilbron, John (2023) Matrix Mechanics Mis-Prized: Max Born's Belated Nobelization. [Preprint]

We examine evaluations of the contributions of Matrix Mechanics and Max Born to the formulation of quantum mechanics from Heisenberg's Helgoland paper of 1925 to Born's Nobel Prize of 1954. We point out that the process of evaluation is continuing in the light of recent interpretations of the theory that deemphasize the importance of the wave function.

Their main argument is that Born should have gotten a Nobel Prize in the 1930s, along with Heisenberg, Schroedinger, and Dirac. He got one much later for the probabilistic interpretation, but quantum mechanics was already using probability and Born's comment did not add much.

I am not sure, but it is an interesting account of the early history of quantum mechanics.

Kaku Continues to Push Quantum Supremacy

The world's biggest Physics charlatan gave a Google lecture: Michio Kaku | Quantum Supremacy | Talks at Google.

He is entertaining to listen to, but he wildly distorts everything.

YouTube is trying to limit its reputation for spreading misinformation, slaps on this disclaimer:

Climate change
United Nations
Climate change refers to long-term shifts in temperatures and weather patterns, mainly caused by human activities, especially the burning of fossil fuels.

This is pointless. The talk is not even about climate.

I think the disclaimer is misleading. Humans are increasing the CO2 in the atmosphere, and that is probably responsible for most of the recent global warming. But the climate has been changing for millions of years, and I am not sure what it means to be mainly caused by humans.

Here a company eager for quantum computers:

Rolls-Royce runs simulations of the computational fluid dynamics (CFD when designing a jet engine) of the engine. A modern jet engine is a spinning maw of blades pulling in air at hundreds of miles per hour. Understanding how air moves through the engine as the turbine spins thousands of times per second is no simple feat for even the most powerful classical computers. Today, Rolls-Royce engineers have to scale down the CFD models or accept a lower level of detail. The firm believes quantum computing could pave the way toward more powerful and accurate simulations.

Sadly, the quantum computers we have at our disposal in 2023 aren't up to the challenge. The most capable quantum computers used in research have just a few dozen qubits (quantum bits), and the results aren't particularly reliable.

So it is doing simulations on Nvidia GPUs, like everyone else. There is no chance that those simulations will ever move to quantum computers.

More Doubts about Google Quantum Supremacy

Gil Kalai has written another paper challenging Google's 2019 paper that was titled, “Quantum supremacy using a programmable superconducting processor”.

Google's paper was published in the British science journal Nature, and made a big splash.

He says:

the supremacy claim has largely (but not fully) been refuted. There are also doubts regarding the claim that the Sycamore 2019 experiment represents a “programmable processor” as the calibration process and other matters weaken this.

I am sure the Google folks would say that better results are on the way, and will see no need to respond.

Dr. Bee Denies Free WIll

Sabine Hossenfelder explains a lot of science well, but she goes off the rails when discussing a favorite topic this week:

I don't believe in free will. This is why.

She covers the main issues, but omits her wacky belief -- she believes in superdeterminism. That is the belief that everything has been determined by the Big Bang, and that it is impossible to do a randomized scientific experiment. We are all slaves in a giant machine, and it is impossible to learn how the machine works.

This belief is so crazy that it is enough to discredit everything she says. Maybe that is why she omits it in this video.

She disagrees with the philosophers who say that free will is compatible with determinism. But then she says it is also incompatible with indeterminism! She is wrong about this. Free will means acting contrary to what others predict, so it appears as indeterminism.

Her main argument is that physicists use equations to predict things, so everything is predictable by equations. The obvious exception is quantum mechanics, but she says the wave function is determined. She neglects to say that the wave function is not observable.

Quantum mechanics is indeterministic. It does not rule out free will.

The guy said to me: Why don't I kill myself tomorrow, because what is the point of anything? ... I am not a psychologist, I am a physicist. I don't know what to say to people with existential angst. Please see a psychologist. I am not a philosopher either.

In essence, she is a preprogrammed robot, and she is not programmed to kill herself.

She could give this answer to anything. Why does she believe in climate change? She is programmed to.

I think that some people have libertarian free will, and some don't. Pres. Joe Biden probably had free will when he was younger, but appears to have lost that mental capacity. Sam Harris probably did also, before spending a year doing LSD experiments. When people like Hossenfelder and Harris deny that they have free will, we should take them seriously. Maybe they are just puppets, lacking the mental ability to make decisions on their own. They are like schizophrenics who hear and follow voices in their heads. q

If you do not have free will, then you are not a fully conscious human being. Free will is the most obvious thing about your existence. Without free will, you are just a cog in a machine.

Here is a interesting new video in favor of free will.

Biologist Jerry Coyne summarizes Hossenfelder (and agrees):

In October of 2020, Hossenfelder declared that libertarian free will — i.e., the “I-could-have-done-otherwise-using-my-volition” form — didn’t exist. I agree with her, of course, for we’re both “naturalists” and “hard determinists.” If you think matter obeys the laws of physics, which is universally accepted in science,  then there’s no room for mental lucubrations that could somehow tweak the laws of physics (Mental lucubrations are instantiations of physical law!) That’s why she (and I) think that, as far as libertarian free will is concerned, “it’s obvious that we don’t have it.”

I believe in libertarian free will, but not in anything that breaks the laws of physics. If free will breaks the laws, which law? Where is that law published? Who got the Nobel Prize for such a huge discovery?

There is no such law. Just a belief, by some, that the past determines the future. But there is no such law, and much of science is based on the possibility of unpredictable influences.

She cites philosophers, but according to her data, only 11% say "no free will".

Her answer is a good one: those people should see a psychologist. I manage to hang onto being a hard determinist, though of course I act as if I can make free decisions. We can’t live without feeling that way because that’s just the way our brains are constructed.

At least he is honest here. It is like saying: As a schizophrenic, I hear voices in my head. I don't know why. Ask a psychologist. I follow the voices because of how my brain is constructed.

A recent PBS TV Nova episode seems to be against free will:

Your Brain: Who's in Control?

Are you in control, or is your brain controlling you? Dive into the latest research on the subconscious with neuroscientist Heather Berlin. Sleepwalking, anesthesia, game theory, and more reveal surprising insights in this eye-opening journey to discover what’s really driving the decisions you make.

The show presents evidence that your conscious decisions can be influenced by subconscious brain processes. I am sure that's true, but I don't think it has much to do with free will. You are still making a decision, even if you are not fully conscious of all aspects of it.