To my wife, Sandra
I must express my thanks to Larry Niven, David Brin and Eric Brown, who took the trouble to read and comment closely on drafts of this novel, and on the imagined universe it portrays: thanks to their input the quality of this work has been greatly enhanced. Thanks also to Arthur C. Clarke, Bob Shaw, Charles Sheffield, Joe Haldeman, and David Pringle for their words of praise and encouragement. Finally I owe a great debt of gratitude to Malcolm Edwards, my editor at Grafton, for his patience, encouragement, and close attention to the development of this work.