Ever wondered if there's another you, somewhere out there in the universe? How about an infinite number of people like you, whose lives are almost exactly like yours — or what your life could have ...

Pick up any science fiction book from the 1960s, and you’ll find parallel dimensions explained through magic portals or mysterious machines that work “just because.” Today’s readers want stories that ...

Right now there might be a whole other universe where instead of brown hair you have red hair, or a universe where you're a classical pianist, not an engineer. In fact, an infinite number of versions ...