Dr. Strange Introduces the Multiverse to the Masses

This month's blockbuster Marvel comic book movie Dr. Strange will serve as many people's introduction to the exotic idea of the multiverse, the notion that besides our universe there are a host -- maybe an infinity -- of unseen other universes, some radically different from our own, some highly similar but distinct in crucial ways.

The film is a worthy and thought-provoking entertainment, but an idea that serves as a good plot device for imaginative counterfactual play in the realm of fictio...