Empirical Evidence for Multiverse

[Whateverist]

It's not a theory, it's a hypothesis. Actually a group of hypotheses. Like all valid hypotheses, they attempt to explain observations in a way that is at least potentially testable

That was my point in the OP. By their very nature, Multiverse theories exclude that possibility.

By their very nature? Really!

I always thought so, at least if we accept that the (our) universe is expanding at a rate which rules out ever contracting.  It is hard to imagine how an adjoining-verse would ever intrude upon our own in a way that would be perceptible from our perspective or conclusively inferable from anything we can detect.  But then I always was a pessimist.

On a separate point, Quantum, don't you doubt the idea that every cell of a multiverse may behave according to laws/patterns that may vary randomly between cells?  It seems to me more likely that whatever underlying substrate gives rise to cells would be common and behave homogeneously, with any variation being accounted for by the rules of organizing principles of the mega-verse .. which we simply don't know.