ABSTRACT
This conclusion presents an overview of key concepts covered in the preceding chapters of this book. It is commonplace to talk about 'the world' as if there is just one world namely, the one four-dimensional universe in which, as it were, we live and move and have our being. But many philosophers and scientists believe that, in fact, there are many things that deserve to be called worlds. Some believe in parallel universes. Some believe that even within our universe there are, many branching 'paths' along which the future might unfold, and that these paths are no less concretely real than the events you are presently experiencing. Some believe in special kinds of abstract states of affairs that constitute complete, alternative ways in which our universe might have turned out. All of these kinds of things and more have been characterized as other worlds; whats more, metaphysicians commonly identify some of these other worlds as merely possible worlds.
