Right.

Like, it's hitting...

All of them, they get hit on the nose.

So when you look at this, this is the...

Remember I mentioned there are all these different directions that lead to non-Markovianity.

This is another one of the directions, is looking at the wavefunction and going, "What metaphysical category does this fit into? Is the wavefunction straightforward ontological furniture? It's not quite ex- maybe, I don't know." You know, I know Tim, this Tim Maudlin, right, he has a view the wavefunction is a distinct kind of ontology.

Um, you know, there are many views, right? Maybe the wavefunction should be understood as purely epistemic.

Sure.

later, 1928,

Schrodinger gives... several lectures on what's now called wave mechanics.

And in the fourth lecture on wave mechanics, section 15, Schrodinger describes his early views on what he thought the wave function could be.

Maybe it was a piece of ontology, meaning something that physically existed.

He even describes a kind of proto many worlds or Everett concept.

kind of picture where maybe to the extent that the mechanical picture could be used at all, the old mechanical picture of particles, somehow the wave function was describing the mechanical system doing everything that it could do, but in some ways it was behaving stronger than in others.

That's the language he used.

I can make this more precise

Consistency, of course, right.

Exactly.

Exactly.

But, um, but at least for me, I was very nervous because if you make a proof very long and very complicated, the odds increase that you're somewhere going to slip in an assumption that you're trying to prove at the end.

So what, what these proofs are trying to get is the Born rule, a specific formula for how you take the quantum state and how you take certain mathematical ingredients called operators and you put them together, and then you apply a certain mathematical operation to them, and what comes out is the probability that a measurement will have a certain kind of value.

That's the Born rule.

Um, you don't want to assume anything...

Mm.