"A Million Open Doors"

John Barnes' A Million Open Doors is the first of three books in a series about the Thousand Cultures. In this universe, Earth has established many interstellar colonies via slower-than-light travel (apparently involving suspended animation of some sort). Each colony was assigned to a particular culture, pre-existing or newly-created. (A single planet may hold more than one culture, as, of course, Earth itself does.) These cultures have evolved each in its own direction for centuries, with only limited contact with other worlds. Recently, though, a new technology, the "springer", has made possible virtually instantaneous travel between worlds; it is only necessary that a springer be set up on a planet to allow such travel to any other world with a springer. Springers are being delivered to the human-colonized worlds as rapidly as possible (which is still restricted to STL, of course). Therefore, the Thousand Cultures are being forced into more intimate contact, with unpredictable results.

( A Million Open Doors )

This book is thought-provoking, at times funny, and deserving of the Nebula nomination it received.