"Amy Reed works part-time as a PR person for a tech start-up, run by her college roommate's nineteen-year-old son, in Palo Alto, California. Donny is a baby genius, a junior at Stanford in his spare time. His play for fortune is an algorithm that may allow people access to their "multiverses"--All the planes on which their alternative life choices can be played out simultaneously--to see how the decisions they've made have shaped their lives. Donny...