This John W. Campbell Award–winning novel is “brilliantly conceived . . . Anderson’s narrative soars, as unfettered as an exalting dream” (Publishers Weekly, starred review).   Astronaut Christian Brannock achieved immortality when he allowed his consciousness to be uploaded onto a computer. Billions of years later, when AI’s called nodes control the galaxy and the survival of Earth is threatened by the expansion of the sun, Brannock is summoned to investigate the condition of humanity’s home planet. He will soon meet another mind—that of a woman named Laurinda Ashcroft, who chose to merge with an Earth-based computer. Together, they must explore a simulation of Earth and all of its alternative pasts and futures, run by a rogue robot whose ambivalence toward human existence may hide far more dangerous secrets . . .   “Anderson, far more than many newer science fiction writers, takes the trouble to envision a genuinely strange, complex future for mankind.” —The Washington Post  Praise for Science Fiction Grand Master Poul Anderson   “One of science fiction’s most revered writers.” —USA Today “The great canvas of interstellar space comes alive under Anderson’s hand as it does under no other.” —Gordon R. Dickson   “One of science fiction’s most influential and prolific writers.” —The Daily Telegraph