Keating Interviews Deutsch on Many-worlds

Physicist Dr Brian Keating posted this interview:

David Deutsch: The Quantum Theory No One Dares Explain!

David Deutsch just exposed something shocking about modern science. Most quantum theories aren't actually science at all. They're just miracles disguised as explanations. When you ask how quantum entanglement works, most interpretations by popular scientists basically reduce to "magic happens." That's not science, that's giving up on our understanding of reality. David Deutsch is a quantum physicist at Oxford, a pioneer in quantum computing, and one of the most important theoretical physicists alive. He argues that only the many-worlds theory actually explains what's happening in quantum experiments instead of just accepting it as a mystery never to be explained. This conversation reveals why modern physics has abandoned its core mission.

So Deutsch is a leading theoretical physicist, and also one who has written books explaining science and the scientific method to the general public.

I disagree with most of what he says.

He promotes some vague ideas called Constructor theory. It is just an idea, and does not solve anything.

His idol is Karl Popper, and his falsifiability criterion. He says that is the most important thing for any scientist to learn.

He is mostly famous for promoting many-worlds theory, and using it as a rationale for quantum computing.

He gets the obvious question:

[Keating] And then if you would, 33:06 can you think of an experiment to you know to put the many worlds theory to 33:11 perhaps a falsifiable test a decisive test as Popper?

No, there is no experiment. It is funny to watch his dance around this question, as it refutes nearly everything he stands for. How can many-worlds be a scientific theory if it fails his basic test of what such a theory should do?

He does argue in favor a many-worlds, but purely on philosophical grounds, as it is not testable with current technology.

one time I met Popper and 38:04 it was in the company of of Bryce Dewitt and we tried to persuade him of the uh 38:10 Everett interpretation, as we called it then. Oh wow. and and um he was very uh 38:16 strongly against it but absolutely not on the grounds of untestability.

The theory is untestable, and has several other fatal defects.

He talks about infinity a lot. Yes, infinity is crucial in mathematics, but it is not clear to me what he is saying about the science of infinity.

He gives a typical philosopher trashing of positivism:

Falsehood is is harmless. It's in fact it's a condition for 11:23 progress. What has happened is bad philosophy.

In the late 19th century, there was the philosophy of positivism 11:29 which said that we cannot understand anything um via theories that are not 11:37 confirmable. Later this turned into logical positivism which said that theories that aren't confirmable by 11:43 observation are meaningless.

And then people noticed that that would mean that 11:48 logical positivism was itself meaningless since it's a philosophical theory that can't be verified by 11:54 experiment. So then Wittgenstein concluded yeah it's meaningless and all 12:00 philosophy is meaningless including mine and people took this seriously and people take this seriously to this day. 12:06 It's just nonsense. It was nonsense from the beginning.

His criticism of positivism is the nonsense. It is like saying: Math requires proofs. Proofs depend on axioms. The axioms cannot be proved. Thus math is meaningless.

The positivist simply says that he attaches meaning to theories with experimental confirmation. Nothing wrong with that.

He acts as if a philosopher should be able to prove his worldview correct. But no system is ever able to prove itself correct.

He goes on to blame positivists for the bad reputation of many-worlds theory.

He has his own kooky version of Einstein's anti-positivism:

Einstein was was uh led 12:11 astray by positivism in his youth and it was only by rejecting it that he managed 12:18 to invent conceptually new theories of the world.

Positivism to him perhaps 12:23 psychologically positivism taught him the importance of asking what the theory 12:29 says about experiment about observation rather than just assuming that it was the same as in the previous theory. That 12:35 that's true and and harmless and beneficial.

But the idea that things which are not verifiable are meaningless 12:43 that would have torpedoed special relativity and general relativity would have would have killed it in in the 12:49 cradle. So later and when it came to quantum theory, Einstein was firmly on 12:55 the side of realism. He he was on the side of there is a real world.

Special relativity was invented by Lorentz, Poincare, and Minkowski, and they were driven by experimental results. I would call them positivists. Einstein's version of special relativity was considered positivist, or even instrumentalist. Likewise general relativity.

Deutsch promotes a philosophy of realism, where a theory should try to say what is real. But Einstein carefully avoided saying whether the aether was real, whether there can be a preferred frame, and whether the FitzGerald contraction can be understood in terms of molecular forces. His whole approach was to say the theory follows from his postulates, without explaining the mechanisms.

It is true that Einstein grew to dislike the positivism of Bohr and Heisenberg, but Einstein was on the wrong side of that debate.

Keating ends by bringing up Einstein's happiest thought, as he always does, and an amusing suggestion that AI progress might be limited in a way analogous to how Hubble telescope imaging was limited by the width of a horse's butt.

Here is another new interview: David Deutsch: AGI, the origins of quantum computing, and the future of humanity.