I think to some extent we have been talking past each other. Very roughly speaking, I think that am more worried about what happens in the middle of an experiment, where you are more worried about what happens at the end. I actually completely agree with you that when a conscious being performs a measurement, then, from the perspective of that being, both interpretations of what happened when it performed the observation are equivalent. That is, the being has no way of telling them apart, and asking which interpretation is true at that point is, in my opinion, roughly along the same lines as asking whether the objective world exists.
(Just to be clear, it’s not my intent to get mystical here. I think of consciousness as essentially just being a way of processing information about the world, rather than positing the existence of souls.)
pcalau12i@lemmygrad.ml 5 days ago
My main issue with Many Worlds is that it is always superfluous.
We know that the exponential complexity of the quantum state cannot be explained by saying every outcome simply occurs in another branch. That would make it mathematically equivalent to an ensemble, and ensembles can be decomposed into large collections of simple deterministic systems with only linear complexity. If that were how reality worked, quantum mechanics would be unnecessary. The theory could be reduced to classical statistical mechanics.
A quantum superposition, such as an electron being spin up and spin down, is not an electron doing both in some proportions. If it were, it would again be equivalent to an ensemble and fully describable using classical probability theory. If the quantum state has any ontology at all, it cannot merely represent particles doing multiple things at once. It must be something else, a distinct beable that either influences particles, as in pilot wave theories, or gives rise to them, as in collapse models.
Some Many Worlds advocates eventually concede this, but then argue that particles never really existed and are only subjective illusions, while the quantum state alone is real. Calling something a subjective illusion does not remove the need for explanation. Hallucinations are still physical processes with physical causes. You can explain them by analyzing the brain and its interactions.
Likewise, you still need a physical explanation for how the illusion of particles arises. Any such explanation ends up equivalent to explaining how real particles arise, and once you do that, Many Worlds becomes unnecessary. You can always replace the multiverse with a single universe by making the process stochastic instead of deterministic.