I had a bunch of aside that I wanted to dive into, like,

Feynman path integrals.

Because it seems to me that there's some kind of a deep symmetry

between multiverse theory and Feynman path integrals.

You're absolutely right.

He believed in multiple histories,

but to the extent that he thought that these were

actually physically real things,

or merely mathematical objects, is open to question.

He was relatively silent on the matter.

He was certainly a realist,

but he made one of the worst quips,

and it's an absolute genius, probably next to Einstein,

second greatest physicist, the 20th century.

But he said, if you think you understand quantum theory,

you don't understand quantum theory,

which is nonsense.

You ever understood quantum theory,

David Deutsch understands quantum theory.

So that was one of the few occasions

where Feynman fell into irrationality and pessimism.

I think it was a plank who said science advances

...