Diaspora
Greg Egan
 Diaspora begins with a description of "orphanogenesis", the birthing of a citizen without any ancestors (most citizens descend from fleshers uploaded at some point), and the subsequent upbringing of the newborn Yatima within Konishi polis. Yatima matures within a few real-time days, because citizens' subjective time runs about 800 times as rapidly as flesher and gleisner time. Early on, Yatima and a friend, Inoshiro, use abandoned gleisner bodies to visit a Bridger colony near the ruins of Atlanta on Earth. Years later, the gleisner Karpal, using a gravitational-wave detector, determines that a binary neutron star system in the constellation of Lacerta has collapsed, releasing a huge burst of energy. Previous predictions portrayed the system's stable orbit as likely to last for another seven million years. By analysing irregularities in the orbit, Karpal discovers that the devastating burst of energy will reach Earth within the next four days. Yatima and Inoshiro return to Earth to urge the fleshers — gathered in a conference — either to migrate to the polises or at least to shelter themselves. Many fleshers reject this advice, or fail fully to appreciate its urgency quickly enough. Stirred up by a paranoid Static diplomat, many fleshers suspect that Yatima and Inoshiro have come to trick or coerce them into "Introdus", or mass-migration into the polises, involving masses of virus-sized nanomachines which dismantle a human body and record the brain's information states as it is chemically converted into a crystalline computer. The gamma ray burst reaches Earth shortly after the conference, destroying the atmosphere and causing a mass extinction. The gleisners and the Coalition of Polises survive the burst, thanks to cosmic radiation hardening. Over the next few years, Yatima and other citizens and gleisners attempt to rescue any surviving fleshers from slow suffocation, starvation, or poisoning by offering to upload them into the polises. The novel's title itself refers to a quest undertaken by most of the inhabitants of Carter-Zimmerman ("C-Z"), a polis devoted to physics and understanding the cosmos, along with volunteers from throughout the Coalition of Polises. The Diaspora consists of a collection of one thousand clones (digital copies) of C-Z polis, deployed toward stars in all directions in the hope of gathering as much data as possible in order to revise the long-held classical understanding of Kozuch Theory, which had failed to predict the Lacerta event. The bulk of the novel follows this expedition, rotating back and forth between different cloned instances of the same cast of main characters as different C-Z clones make discoveries along the way, relaying information to one another over hundreds of light years – and finally between universes.