Rating: 6.1 (out of 10)
Mathematician Greg Egan writes hard science fiction in its purest form; in other words, he is the kind of science fiction writer who writes because he has an itch to scratch. He doesn’t so much build worlds as generate models based around whatever theoretical concepts are occupying his thoughts at the moment – narratives driven by speculation about scientific concepts, the issues and conflicts that arise from them, and the rational thinking required to solve them. Egan has always done the science half of science fiction as well as anyone can.
Unfortunately, he is also the kind of hard sci-fi writer who isn’t quite as successful at the fiction half of the equation. He doesn’t do people well. His characters’ emotional lives seem to spring from the same kind of rationalism as his mathematical musings; solutions to equations that need to be formulated to move the story forward. Often, characters are distinguished only by a few rudimentary personality traits or physical differences.
The world of Dichronauts contains two spatial dimensions and two temporal ones, rather than the “3+1” dimensions our own existence occupies. The people of this world are symbiotes, each comprised of a “walker” and a “sider” – siders are parasites who cannot move around on their own and who need their walkers’ blood supply to live; walkers can only see one side of the world on their own and need their siders to see the other. Walkers and siders are bonded for life at birth, and presumably cannot be separated without causing damage to both.
The sun revolves around the earth in this world, so its people are constantly migrating to stay within its habitable zones. The walker Seth and his sider, Theo, are surveyors who scout the migration paths for their home city. Together, they make a discovery, and embark on a journey, that quite literally turns their world upside down.
That journey is not lacking for interesting turns and revelations, though again these are only stimulating to the intellect, and to the base desire of the sci-fi reader to explore and map out new frontiers. Some of the more interesting intimations about the relationships between siders and walkers are deposited into the story for logical reasons but are not investigated adequately enough to make it an emotionally compelling experience. And while the physical properties of this world are explored in detail, its society has no real culture to speak of. The people of this world seem to exist only to rationalize their environment, which seems to be all the author is concerned with as well.
In other words, if you love geometry as much as Greg Egan does – and are satisfied by a narrative driven purely by reason – Dichronauts is your kind of novel (add another star or two, accordingly). I can’t make a higher recommendation without a more complete experience.