Every orphan was an explorer, sent to map uncharted territory.
And every orphan was the uncharted territory itself.
In 2975, the orphan Yatima is grown from a randomly mutated digital mind seed in the conceptory of Konishi polis. Yatima explores the Coalition of Polises, the network of computers where most life in the solar system now resides, and joins a friend, Inoshiro, to borrow an abandoned robot body and meet a thriving community of “fleshers” in the enclave of Atlanta.
Twenty-one years later, news arrives from a lunar observatory: gravitational waves from Lac G-1, a nearby pair of neutron stars, show that the Earth is about to be bathed in a gamma-ray flash created by the stars' collision — an event that was not expected to take place for seven million years. Yatima and Inoshiro return to Atlanta to try to warn the fleshers, but meet suspicion and disbelief. Some lives are saved, but the Earth is ravaged.
In the aftermath of the disaster, the survivors resolve to discover the cause of the neutron stars' premature collision, and they launch a thousand polises into interstellar space in search of answers. This diaspora eventually reaches a planet subtly transformed to encode a message from an older group of travellers: a greater danger than Lac G-1 is imminent, and the only escape route leads beyond the visible universe.
[Greg Egan] has been shortlisted for the Arthur C. Clarke Award.This is not correct.
On Swift, there was only deuterium, carbon-13, nitrogen-15, oxygen-18, sulphur-34: the heaviest stable isotope of each element.The difficulties of either creating a biosphere, or modifying an existing one, to use heavy water are not addressed. Certainly, the chemistry of heavy water is sufficiently different from that of normal water that a complete substitution would be fatal to most organisms in Earth's biosphere. Life based on heavy water might well be possible, but it would not be a simple matter to make the substitution.
… Poincaré's rotational ‘pole’ — the two-dimensional sphere on the hypersurface that stayed fixed in space as the star rotated.Although this is physically possible, it's not very likely. The more probable situation in 5 dimensions (though not in 4) is to have two single-point rotational poles, as in 3 dimensions. There are some novel aspects, though: in general, a rotating star in 5 dimensions will have two equators, and two distinct rotational periods. More on this.