It is evidence of (what we now know as) quantum mechanics. MWI is just an interpretation of QM, so there isn’t really evidence for MWI that isn’t also evidence for the other interpretations according to the people who favor them.
It is evidence of (what we now know as) quantum mechanics. MWI is just an interpretation of QM, so there isn’t really evidence for MWI that isn’t also evidence for the other interpretations according to the people who favor them.