Seth is a surveyor, along with his friend Theo, a leech-like creature running through his skull who tells Seth what lies to his left and right. Theo, in turn, relies on Seth for mobility, and for ordinary vision looking forwards and backwards. Like everyone else in their world, they are symbionts, depending on each other to survive. In the universe containing Seth's world, light cannot travel in all directions: there is a “dark cone” to the north and south. Seth can only face to the east (or the west, if he tips his head backwards). If he starts to turn to the north or south, his body stretches out across the landscape, and to rotate as far as north-north-east is every bit as impossible as accelerating to the speed of light. Every living thing in Seth’s world is in a state of perpetual migration as they follow the sun’s shifting orbit and the narrow habitable zone it creates. Cities are being constantly disassembled at one edge and rebuilt at the other, with surveyors mapping safe routes ahead. But when Seth and Theo join an expedition to the edge of the habitable zone, they discover a terrifying threat: a fissure in the surface of the world, so deep and wide that no one can perceive its limits. As the habitable zone continues to move, the migration will soon be blocked by this unbridgeable void, and the expedition has only one option to save its city from annihilation: descend into the unknown.

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.

A million years from now, the galaxy is divided between the vast, cooperative meta-civilisation known as the Amalgam, and the silent occupiers of the galactic core known as the Aloof. The Aloof have long rejected all attempts by the Amalgam to enter their territory, but have permitted travellers to take a perilous ride as unencrypted data in their communications network, providing a short-cut across the galaxy's central bulge. When Rakesh encounters a traveller, Lahl, who claims she was woken by the Aloof on such a journey and shown a meteor full of traces of DNA, he accepts her challenge to try to find the uncharted world deep in the Aloof's territory from which the meteor originated. Roi and Zak live inside the Splinter, a world of rock that swims in a sea of light they call the Incandescence. Living on the margins of a rigidly organised society, they seek to decipher the subtle clues that can reveal the true nature of the Splinter. In fact, the Splinter is orbiting a black hole, which is about to capture a neighbouring star, wreaking havoc. As the signs of danger grow, Roi, Zak, and a growing band of recruits struggle to understand and take control of their fate. Meanwhile, Rakesh is gradually uncovering their remote history, and his search for the lost DNA world ultimately leads him to a civilisation trapped in cultural stagnation, and startling revelations about the true nature and motives of the Aloof.

Paul Durham keeps making Copies of himself: software simulations of his own brain and body which can be run in virtual reality, albeit seventeen times more slowly than real time. He wants them to be his guinea pigs for a set of experiments about the nature of artificial intelligence, time, and causality, but they keep changing their mind and baling out on him, shutting themselves down. Maria Deluca is an Autoverse addict; she’s unemployed and running out of money, but she can’t stop wasting her time playing around with the cellular automaton known as the Autoverse, a virtual world that follows a simple set of mathematical rules as its “laws of physics”. Paul makes Maria a very strange offer: he asks her to design a seed for an entire virtual biosphere able to exist inside the Autoverse, modelled right down to the molecular level. The job will pay well, and will allow her to indulge her obsession. There has to be a catch, though, because such a seed would be useless without a simulation of the Autoverse large enough to allow the resulting biosphere to grow and flourish — a feat far beyond the capacity of all the computers in the world.

As a young boy, Prabir Suresh lives with his parents and sister on an otherwise uninhabited island in a remote part of the Indonesian peninsula. Prabir names it Teranesia, populating it with imaginary creatures even stranger than the evolutionarily puzzling butterflies that his parents are studying. Civil war strikes, orphaning Prabir and his sister. Eighteen years later, rumours of bizarre new species of plants and animals being discovered in the peninsula that was their childhood home draw Prabir's sister back to the island - Prabir cannot bear for her to have gone out alone and he follows, persuading a pharmaceutical researcher to take him along as a guide.

Nasim is a young computer scientist, hoping to work on the Human Connectome Project: a plan to map every neural connection in the human brain. But funding for the project is cancelled, and Nasim ends up devoting her career to Zendegi, a computerised virtual world used by millions of people. Fifteen years later, a revived Connectome Project has published a map of the brain. Zendegi is facing fierce competition from its rivals, and Nasim decides to exploit the map to fill the virtual world with better Proxies: the bit-players that bring its crowd scenes to life. As controversy rages over the nature and rights of the Proxies, a friend with terminal cancer begs Nasim to make a Proxy of him, so some part of him will survive to help raise his orphaned son. But Zendegi is about to become a battlefield ...

Greg Egan is arguably Australia's greatest living science fiction writer. In a career spanning more than thirty years, he has produced a steady stream of novels and stories that address a wide range of scientific and philosophical concerns: artificial intelligence, higher mathematics, science vs religion, the nature of consciousness, and the impact of technology on the human personality. All these ideas and more find their way into this generous and illuminating collection, the clear product of a man who is both a master storyteller and a rigorous, exploratory thinker. The Best of Greg Egan contains twenty stories and novellas arranged in chronological order, and each of them is a brilliantly conceived, painstakingly developed gem, including the Hugo Award-winning novella "Oceanic", a powerful account of a boy whose deeply held religious beliefs are undermined by what he comes to learn about the laws of the physical world. This book really does represent the best of Greg Egan, and it therefore takes its place among the best of contemporary SF. Startling, intelligent and always hugely entertaining, it provides an ideal introduction to one of the most accomplished and original writers working today. This is an important and provocative collection, and it deserves a place on the serious science fiction reader's permanent shelf.