By the late 30th century, human beings have split into several different manifestations. Most people reside as virtual consciousness in the polises, independent city-states embedded in virtual reality. Others, the gleisners, occupy robot bodies and have spread across the solar system. And the fleshers form a continuum, from the unaltered statics to the genetically engineered, wildly variegated exuberants to the bridgers, a consortium of humans self-consciously altering their genomes in such a way as to keep fleshers from growing too far apart. By the mid 2900's, this situation has reached an uneasy stability, with implicit understandings between the three great branches of humanity.
All of that changes with the discovery that a nearby binary neutron star system is losing angular momentum much faster than it should, and will soon coalesce into a black hole, spilling a burst of deadly gamma radiation across the sky. The Earth's biosphere is doomed to a slow death. The age of flesh draws to a close, and humans are forced to accept either physical existence in gleisner bodies or virtual existence in the now-starbound polises. Or death.
Thus begins a halting exodus to the stars, as humanity embarks upon a quest to understand the disaster that has befallen it, in defiance of all known physical laws. But the Diaspora is also humanity's struggle to maintain some connection with the physical universe, to avoid slipping into the deadly trap of a purely solipsistic existence in the artificial worlds of the polises.
In this wildly ambitious novel, Egan demonstrates a first-rate speculative imagination tempered by a firm grounding in mathematics and science. This is science fiction, not Space Opera, not Raymond Chandler in Virtual Reality, not Herman Wouk in Warp Drive. This stuff is not for the faint of heart. If you like your sf light and airy, easy to read and digest, full of fluff and replete with reassurances that humans will always be human no matter how far we travel or how much technology we accumulate--then don't bother with Diaspora
. Or anything else by Egan. Sections of this novel read like a textbook, as when Egan proposes a mechanism for the accelerated loss of angular momentum from that binary neutron star:
...Quarks of a certain color could become locally heavier in one core, causing them to sink slightly until the attraction of the other quarks buoyed them up; in the other core, quarks of the same color would be lighter, and would rise. Tidal and rotational forces would also come into play. The separation of color would be minute, but the effects would be dramatic: the two orbiting, polarized cores would generate powerful jets of mesons, which would act to brake the neutron stars' orbital motion--a kind of nuclear analogue of gravitational radiation, but mediated by the strong force and hence much more energetic.
...Or the particulars of chemistry in a five-dimensional universe:
"How are you going to make molecules, if every chemical bond triggers nuclear fusion?"
"Not every bond does. If you throw enough hydrons together, the leptons fill up all the energy levels where they're confined tightly within the nucleus, so the outermost ones end up protruding sufficiently to be able to bind two atoms together with a respectable separation between the nuclei. You have to fill up the first two levels completely, which takes twelve leptons--so every stable molecule needs to contain a few judiciously placed atoms of number 13 or higher. Atom 27 can form fifteen covalent bonds; it's the closest thing in the macrosphere to carbon."
This isn't brain candy, this is brain brandy, the kind of stuff you can really wrap your head around. And that's good, because what the book offers in first-rate, wild-ass scientific speculation it lacks in warmth. There's not a lot of touchy-feely human interaction going on here, although Egan tries and to a certain extent succeeds in engaging us with his characters and involving us with their plights. This is no mean feat. It's a testament to Egan's skill that we care at all about his characters, because their very nature as robots or virtual beings creates an immediate gulf between them and us. Egan tries never to lose track of their vestigial humanity, but at the same time he never lets us forget that these characters are to a large degree indestructible and immortal, with minds spanning centuries of experience, virtual libraries of information, and unimaginable processing power. And to a certain extent the function of Egan's characters is to comment upon and analyze the complex scenarios he has dreamed up for us.
Ah, but what scenarios! Egan's versatile and bold imagination takes us from the foundations of matter to the edge of virtual biology, from the inner solar system to interstellar space, to the edges of a fractal cosmos, universes trillions of branch points removed from our own.
So you won't find a lot of Hallmark moments here. But you will get one hell of a ride..
Sullydog is the editor and publisher of the ezine Neverworlds
. Check it out!