[spot5010]

What you said here makes sense. Forgive me, but I have trouble even articulating what it is that I don’t understand correctly.

Maybe what I meant was this: if I perform a quantum experiment where the spin measurement of an electron could be spin up or spin down, the future me would end up in one of two branches: I measure spin up, or I measure spin down. There wouldn’t be any possible world where I measure a superposition of spin up and spin down, because such a a state is going to decohere rapidly. This makes sense. What I’m unable to grasp is that even though the wave function of the universe contains both branches, “I” somehow experience only one of the two branches.

The answer to that I guess if that the two branches are nearly orthogonal they will merrily evolve independent of each other. But somehow “I” only experience only one of them.

Sorry for the rambling. I’m not able to articulate what I don’t understand.

[Nevermark]

Good questions.

> The future me would end up in one of two branches: I measure spin up, or I measure spin down.

The future "you's" would each see spin up, and spin down, respectively.

We are just as quantum as what we measure. There isn't a scale where entanglement and superposition turn into something else. No classical vs. quantum atoms.

Just as an up-spin qubit touching an up/down qubit results in an up-up qubit pair in superposition with an up-down superposition, conserving the qubit, when we touch a qubit we get "us"-up and "us"-down versions.

No information is created. None is destroyed. We experience a correlation = "collapse" (both versions of us), but the quantum information just continues on as before, qubit conserved.