Thursday, November 22, 2018

Glashow defends textbook quantum mechanics

I sometimes complain that crackpot ideas have taken over the popularizations of physics, in part because the professors who know better have been silent. But I am happy to say that a distinguished physicist has spoken up to criticize a popular quantum mechanics book.

Sheldon Lee Glashow reviews a book to criticize these ideas:
Schroedinger's cat is simultaneously alive and dead.
We should accept non-falsifiable theories, because no theory is really falsifiable anyway.
Theories cannot be verified either.
Copenhagen interpretation has clouded the minds of physicists.
Glashow is right about these points. Attacking Copenhagen because of Schroedinger's cat is foolishness. The cat is only half-dead in the sense that our knowledge is imperfect, and not because of some fundamental shortcoming of quantum mechanics.

The Becker book attacks Copenhagen because it says that the underlying philosophy of logical positivism is faulty. I do believe it is correct to say that quantum mechanics was founded on a logical positivist philosophy. I think that is a good thing, not a bad thing.

Unfortunately, logical positivism has fallen out of favor among philosophers, and so has the Copenhagen interpretation. Was one shift a consequence of the other? I don't know.

The situation is muddied by the fact that no one defends logical positivism anymore. Copenhagen and positivism seem to have a lot of believers among physicists, but not so many expressing public opinions. Many physicists defend variants of Copenhagen, but prefer to call it consistent histories or QBism.

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