City at the End of Time
Greg Bear
 City at the End of Time is about the Kalpa, the last city on Earth, one hundred trillion years in the future. The novel's back-story describes how the aging universe continued expanding and its spacetime fabric weakened. With the galaxies burnt out, humanity dispersed across the cosmos, where they encountered the Typhon, an inexplicable entity that was destroying the decaying universe. It consumed matter and replaced space-time with emptiness and inconsistencies beyond the laws of physics. The resulting Chaos spread rapidly, driving some humans back to ancient Earth with its rekindled sun. In an attempt to fend off the approaching Typhon, leaders of the dying Earth sent for Polybiblios, a human living with the Shen, an ancient alien race. Polybiblios returned to Earth with his adopted daughter, Ishanaxade, a being he had constructed from "fate-logs" of intelligent species collected by the Shen. After the Shen system fell, and the Chaos surrounded Earth, its leaders instructed everybody to convert themselves from primordial (real) matter to noötic (virtual) mass. As each city fell, its inhabitants retreated to the last remaining cities, the Kalpa and Nataraja. Using knowledge he had gleaned from the Shen, Polybiblios build reality generators to protect the Kalpa. Nataraja, which had rebelled the instruction to convert to noötic matter, was left to fend for itself. The novel alternates between the Kalpa and present-day Seattle, where three drifters, Ginny, Jack and Daniel are in possession of sum-runners, small stone-like talismans that give them "fate-shifting" abilities, whereby they can jump between fate-lines (world lines in a multiverse). Ginny and Jack also have disturbing dreams of the Kalpa, and are inexplicably connected to Jebrassy and Taidba, two "breeds" living in the future city. Fate-shifters and their sum-runners are hunted by "collectors" working for the Chalk Princess, an entity controlled by the Typhon from the future. These hunters place adverts in local newspapers inviting "dreamers" to contact them for "help". In the future the Typhon is destroying history and world-lines are being broken, merging the past and the present. With the Chaos closing in on the Kalpa, the inhabitants (all noötic) are unable to venture outside the city walls. Under Ishanaxade's instructions they create "breeds", copies of ancient humans, using primordial matter. They send them in groups into the Chaos to find out if Nataraja still stands, but none return. Ishanaxade herself ventures out, but is not heard from again. As the Typhon starts breaching the Kalpa, the last batch of breeds, including Jebrassy and Taidba, leave the city in search of help. Armed with portable reality generators, they slowly progress through the "unreal" landscape in search of the rebel city. Meanwhile the Chaos has reached all the way back to the present-day, and an event called the Terminus hits Seattle: the past, present and future collides and world-lines are severed. Ginny, Jack and Daniel, having evaded the hunters, trek across a degenerating Seattle. Protected by their sum-runners, they are drawn to the Nataraja, where Ishanaxade is waiting. While still in the Kalpa, Ishanaxade had instructed Polybiblios to create the sum-runners containing "fragmented Babels", and in the Chaos she had sent them back to the "beginning of time". The sum-runners were programmed to lead the bearers to Ishanaxade when the expected Terminus occurred. The breeds, programmed to see Ishanaxade as their "mother", are also drawn to Nataraja, and Jebrassy and Taidba find their counterparts Jack and Ginny in the ruined city. The Kalpa falls to the Chaos, but in Nataraja, the sum-runners and their Babel fragments are united and a new history is created causing the Typhon, now a failed god, to implode.