Bruce Sterling is one terrific writer and he's relatively new, but I don't know how long he's been doing it; he probably doesn't need the publicity anymore!
Larry NivenThere were timelines branching and branching, a mega-universe of universes, millions more every minute. Billions? Trillions? The universe split every time someone made a decision. Split, so that every decision ever made could go both ways. Every choice made by every man, woman, and child was reversed in the universe next door.
Larry Niven