In the many worlds theory, these different universes are related, they peel off from one another. Do you think it's possible, like in lots of the Hollywood depictions, for these universes to interact with one another? It's almost certainly impossible to travel from universe to universe. So if we can't interact with these other universes, can the idea ever be tested? Well, the many worlds' interpretation is super-duper testable in the sense that it is falsifiable.