I’m not convinced that the specifics of “why” someone might consider themselves a plural smeared across a multiverse are irrelevant. MWI and the dynamics of evolving amplitude are a straightforward implication of the foundational math of a highly predictive theory, whereas the different flavors of classical multiverse are a bit harder to justify as “likely to be real”, and also harder to be confident about any implications.
If I do the electron-spin thing I can be fairly confident of the future existence of a thing-which-claims-to-be-me experiencing both outcomes as well as my relative likelihood of “becoming” each one, but if I’m in a classical multiverse doing a coin flip then perhaps my future experiences are contingent on whether the Boltzmann-brain-emulator running on the grand Kolmogorov-brute-forcing hypercomputer is biased against tails (that’s not to say I can make use of any of that to make a better prediction about the coin, but it does mean upon seeing heads that I can conclude approximately nothing about any “me”s running around that saw tails).
Fully agreed, I wasn’t trying to say that there are just as good justifications for a classical multiverse as a quantum multiverse. Just that it’s the “multiverse” part that’s more relevant than the “quantum” part. If you accept multiverses at all, most types include the possibility that there may be indistinguishable pre-flip versions of ‘you’ that experience different post-flip outcomes.
I’m not convinced that the specifics of “why” someone might consider themselves a plural smeared across a multiverse are irrelevant. MWI and the dynamics of evolving amplitude are a straightforward implication of the foundational math of a highly predictive theory, whereas the different flavors of classical multiverse are a bit harder to justify as “likely to be real”, and also harder to be confident about any implications.
If I do the electron-spin thing I can be fairly confident of the future existence of a thing-which-claims-to-be-me experiencing both outcomes as well as my relative likelihood of “becoming” each one, but if I’m in a classical multiverse doing a coin flip then perhaps my future experiences are contingent on whether the Boltzmann-brain-emulator running on the grand Kolmogorov-brute-forcing hypercomputer is biased against tails (that’s not to say I can make use of any of that to make a better prediction about the coin, but it does mean upon seeing heads that I can conclude approximately nothing about any “me”s running around that saw tails).
Fully agreed, I wasn’t trying to say that there are just as good justifications for a classical multiverse as a quantum multiverse. Just that it’s the “multiverse” part that’s more relevant than the “quantum” part. If you accept multiverses at all, most types include the possibility that there may be indistinguishable pre-flip versions of ‘you’ that experience different post-flip outcomes.
No they are not straightforward, MWI is controversial and subject to ongoing research.