On the other hand, in the many-worlds interpretation of quantum mechanics, reality consists only of a deterministically evolving wave function, non-locality is a non-issue.
One problem with the many-worlds interpretation, however, has been that it is fundamentally untestable, since observations can only be made in our world.
They formulate theories similar to the many-worlds interpretation, finally deciding that none of the theories they discus fit their previous observations.
Although philosophers have discussed related concepts for centuries, in the early 1970s the only genuine physical theory yielding a multiverse of sorts was the many-worlds interpretation of quantum mechanics.
Normally, when people think of the multiverse, they think of the many-worlds interpretation of quantum mechanics, where every possibility is actualised.