illions of planets in our galaxy have been explored at sublight speeds, but only a few examples of the most primitive otherworldly life have yet been discovered by humanity. Those planets bearing alien life have been quarantined for their own preservation, but this has not stopped mankind from establishing numerous colonies elsewhere. These scattered worlds are linked in a novel way: Anyone wishing to travel from one globe to another (and those doing so are a distinct minority) simply transmit the information constituting their encoded selves, information which is used to resurrect the traveler in a new body at the receiving end.
And what bodies! Sexual dimorphism has vanished, and people spontaneously adopt a gender only upon prolonged exposure to a new lover's physiological cues. Inside each human is a Qusp, a device which not only grants access to virtual landscapes, but also allows complete control of the autonomic functions. The Qusp also grants practical immortality, recording minute-to-minute backups of each individual, transferred to a new body upon any merely "local" death.
Such is the near-utopia 20,000 years from now. But as with many utopic schemes, this one is growing stagnant, as people become timid and ossify under the weight of their long lives. Still, a few bold souls continue to push ahead into new frontiers. One such is a scientist named Cass, who is intent on testing the Sarumpaet paradigm that governs physics. Conducting an experiment near the star Mimosa, Cass accidentally creates a pocket universe that is not merely stable but expanding. Pushing outward in all directions at half-light-speed, the new rival universe engulfs and destroys anything in its path.
Flash forward some six centuries. Humanity is still desperately trying to counter the expanding conqueror, the real nature of which is unknown, for nothing can be glimpsed beyond the destructive interface. The large space station dubbed the Rindler is the current nexus for researchers, one of whom is named Tchicaya. Arriving onboard the Rindler in his new body, the 4,000-year-old Tchicaya finds that his oldest friend, Mariama, is there as well. But the pair have drifted apart over the millennia and now learn that they are on opposite sides of the battle. Tchicaya is a Yielder, who wants to learn to co-exist with the rival universe, while Mariama is a Preservationist, who wants to destroy the threat and preserve mankind from harm.
The Rindler is rife with politics, but some scientific headway is made nonetheless. When Tchicaya and his associates finally penetrate the barrier and learn that life of a strange sort has bootstrapped itself into existence inside the pocket cosmos, all the balances shift. Breaking their word, the Preservationists unleash their killing probes, and Tchicaya and Mariama are forced to cross the interface into a cosmos where even the rules of physics do not apply, and contact their only allies, the xennobes.
A Sturgeon for a new century
In a short story from 1995 entitled "Luminous," Greg Egan first conceived of the brilliant notion of seeding a part of the cosmos with a rival kind of mathematics that would spread and mutate anything it touched. Although not linearly connected to that story, this novel is plainly his further extrapolation of this rich premise. In addition to this existential riff, we also note three other main themes. There's a fascinating examination of the continuity and transfiguration of identity among immortals (issues of identity have always been central to Egan's work). There's keen-edged speculation regarding bodily modifications and gender, a la the writings of John Varley and Ursula Le Guin. There's a classic first-contact scenario, with the novelty of the life being more or less mathematical in nature and existing on a kind of cellular automata substrate. All in all, then, this is a complex, dense novel, but not one that obfuscates or thwarts emotional involvement.
For the curious, the title refers to a method of graphing vectors which comes to stand as a metaphor for the way any individual's life evolves, a kind of life chart. This application of abstruse mathematical concepts to mundane yet important issues any person might face, whether in our century or 20 millennia from now, is typical of Egan's methodology. Consequently, any reader must be willing to work a little to engage himself with Egan's sometimes knotty arguments. This is not a slam-bang adventure tale for lazy fans. And Egan's way of eliding direct explanations in many cases also demands close attention. (But this latter tactic is, of course, in common usage among the better SF writers.) For instance, Chapter 6 and its mates, which detail a "Slowdown" on Tchicaya's homeworld during his youth, will be initially confounding. But if the reader persists, she will encounter a marvelous idea concerning sublight travel, one I don't think I've ever seen before.
And of course Egan does not neglect either the emotional storms of his characters, or a sense of adventure. The simmering relationship between Tchicaya and Mariama is well developed and surprising, and the plunge into the pocket universe has plenty of harrowing moments. A lot of Egan's success relates to his use of concrete, easily graspable figurative language for weird concepts. (This is a technique employed by Stephen Baxter as well.) Consider this: "It was ... like having a billion-piece jigsaw puzzle stolen by a swarm of flying insects: difficult to reverse, but not impossible."
If I were to cite one flaw here, it's a minor one concerning the language. In a genderless world, Egan continues to use "he" and "she" to denominate individuals. Perhaps he felt new pronouns would add too much strangeness to the tale, but it seems almost cheating not to have employed some neologisms.
