Sunday, September 8, 2019

Carroll promotes his dopey new quantum book

Physicist Sean M. Carroll has a NY Times op-ed today promoting his stupid new book.
“I think I can safely say that nobody really understands quantum mechanics,” observed the physicist and Nobel laureate Richard Feynman. ...

What’s surprising is that physicists seem to be O.K. with not understanding the most important theory they have.
No, that is ridiculous.

I assume that Feynman meant that it is hard to relate quantum objects to classical objects with a more intuitive understanding. Physicists grappled with the theory in the 1920s, and by 1935 everyone had a good understanding of it.
The reality is exactly backward. Few modern physics departments have researchers working to understand the foundations of quantum theory.
That is because the foundations were well-understood 90 years ago.
In the 1950s the physicist David Bohm, egged on by Einstein, proposed an ingenious way of augmenting traditional quantum theory in order to solve the measurement problem. ... Around the same time, a graduate student named Hugh Everett invented the “many-worlds” theory, another attempt to solve the measurement problem, only to be ridiculed by Bohr’s defenders.
They deserved to be ridiculed, but their theories did nothing towards solving the measurement problem, are philosophically absurd, and have no empirical support.
The current generation of philosophers of physics takes quantum mechanics very seriously, and they have done crucially important work in bringing conceptual clarity to the field.
Who? I do not think that there is any living philosopher who has shed any light on the subject.
It’s hard to make progress when the data just keep confirming the theories we have, rather than pointing toward new ones.

The problem is that, despite the success of our current theories at fitting the data, they can’t be the final answer, because they are internally inconsistent.
This must sound crazy to an outsider. Physicists have perfectly good theories that explain all the data well, and yet Carroll writes books on why the theories are no good.

The theories are just fine. Carroll's philosophical prejudices are what is wrong.

Carroll does not say what would discredit himself -- he is a big believer in many-worlds theory. If he wrote an op-ed explaining exactly what he believes about quantum mechanics, everyone would deduce that he is a crackpot.

Philosopher Tim Maudlin also has a popular new essay on quantum mechanics. He is not so disturbed by the measurement problem, or indeterminism, or Schroedinger's cat, but he is tripped up by causality:
What Bell showed that if A and B are governed by local physics — no spooky-action-at-a-distance — then certain sorts of correlations between the behaviours of the systems cannot be predicted or explained by any local physics.
This is only true if "local physics" means a classical theory of local hidden variables. Bell did show that quantum mechanics can be distinguished from those classical theories, but there is still no action-at-a-distance.

Update: Lumo trashes Carroll's article. Woit traces an extremely misleading claim about a physics journal editorial policy. The journal just said that it is a physics journals, and articles have to have some physics in them. Philosophy articles could be published elsewhere.

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