The many-worlds interpretation of quantum cosmology requires that there be many, perhaps an infinite number, of worlds, new ones arising from each quantum interaction. Constellations, a play by Nick Payne opening November 8 at the Players Club of Swarthmore, is an artful riff on this notion, using multiple short scenes to portray divergent outcomes of each event. The result is a wittily complex structure used to tell a very simple story: two people meet, take up housekeeping together, break up, get together again, settle down, face the future. At least, in several of the multiple universes that are all equally possible, they do several of those things.