jacob_cannell above seems to think it is very important for physicists to know about Solomonoff induction.

I think a more charitable read would go like this: being smarter doesn't necessarily mean that you know everything there's to know nor that you are more rational than other people. Since being rational or knowing about Bayesian epistemology is important in every field of science, physicists should be motivated to learn this stuff. I don't think he was suggesting that French pastries are literally useful to them.

Solomonoff induction is one of those ideas that keeps circulating here, for reasons that escape me.

Well, LW was born as a forum about artificial intelligence. Solomonoff induction is like an ideal engine for generalized intelligence, which is very cool!

Bayesian methods didn't save Jaynes from being terminally confused about causality and the Bell inequalities.

That's unfortunate, but we cannot ask of anyone, even geniuses, to transcend their time. Leonardo da Vinci held some ridiculous beliefs, for our standars, just like Ramanujan or Einstein. With this I'm not implying that Jaynes was a genius of that caliber, I would ascribe that status more to Laplace. On the 'bright' side, in our time nobody knows how to reconcile epistemic probability and quantum causality :)