Shouldn’t the default position be that a multiverse exist? A multiverse is what logic suggests (starting with “a point in motion is a line” and moving up to higher dimensions)
This parsimony question also overlaps the Simulation Hypothesis: the fact that most physical laws resolve at macro-scale, by aggregating probabilities, and only break down into odd behavior (where a particle seems to care whether or not you're looking), smells to this programmer like an optimization hack. :)
Just started reading Donald Hoffman's "The Case Against Reality", which posits some very bold answers to this question, theorizing that there is no reason to assume that base reality is anything like our perceptions (subjective or scientific), any more than there's a reason to assume the perception of a desktop icon has a direct relationship with its filesystem implementation. The implications of a "consciousness-first" rather than "matter-first" explanation of existence are staggering, and it isn't hard to set up a model in which that explanation is more parsimonious than Multiple Worlds.
Also, what you're describing sounds more like a multi-dimensional (above the ones we're aware of) universe rather than a multiverse.
> what you're describing sounds more like a multi-dimensional (above the ones we're aware of) universe rather than a multiverse.
I don’t know enough about physics to understand how a multi-dimensional (above 4D) universe is different than a multiverse. I assumed they were one and the same concept.
Imagine multiple copies of the same 4D universe.
How about that?
This idea of a multiverse is some metaphysics sprinkled in with the Copenhagen interpretation that boils down to something like this: the total probability of any observed outcome summed with the probability of all possible outcomes is, of course, one.
The metaphysics is this-- assuming that all the outcomes that did not occur did occur in some other unobservable and inaccessible universes.
This is essentially the meaning of the plus symbol in summing probabilities; it separates the observed wavefunction from every other possible wavefunction. It is absurd to draw such a mind-boggling conclusion from a plus sign.
Just because a theory makes correct predictions, does not mean, necessarily that those mechanisms exist in the actual physical universe. It is entirely possible to make correct predictions with incorrect models.
I think the leap from A to B is unnecessary. "We don't know" is also an acceptable answer.