I really enjoy writing that sits out on the edge of genres, mixing various aspects of different kinds of writing, pushing the boundaries and challenging the reader. But reading Poul Anderson's novel of deep space flight, I'm reminded of how I got to where I am today. That is, to find the edges, I pretty much started in the exact middle. Nothing gets more middle than traditional hard science fiction, where the science often overtakes the plot, and less expert writers end up lecturing. I'm quite pleased that Anderson does not fall anywhere near that category; his hard science fiction is an adventure with no dearth of science.
Tau Zero is the story of a Bussard ramjet travelling to a planet some 32 light years from Earth with a crew of 50 and enough cargo for them to establish a colony. Anderson holds to relativity as we generally understand it: the speed of light is an absolute limit, and the Leonora Christine will never reach that speed. But it can always grow incrementally closer, thus causing massive time dilation, meaning that the time on the ship is less than the time of the objects moving at a normal speed. Anderson starts the story with introductions of two of the main characters, Charles Reymont and Ingrid Lindgren, indicating with a fascinating conversation and enticing descriptive passages that his prose is going to attempt to match the scope of his story. The characters that inhabit Tau Zero are not flat, providing numerous lenses through which the reader can witness the effects of the voyage.
Along with the astrophysics that Anderson describes—what exactly it means to move so close to the speed of light, he also spends a good deal of time moving through the cast of characters, flirting with sociology and psychology as he examines the effects of the voyage on individuals and relationships, both personal and professional. And generally speaking, he nails the characters: they are lively and interesting, even when they are not good people. For the first third of the novel he intersperses the travelogue with the characters' stories, setting a foundation for the tragedy that follows. For just as you think you have a grasp on the science and the people, Leonora Christine passes through a nebula, damaging her engines such that she cannot slow down. As Anderson has explained, the engines that provide propulsion also protect the ship from the particles and waves that relativity have made excruciatingly dangerous, and since they are basically nuclear reactors, they must be shut down to be repaired. But shutting them down removes the protection the engines afford the ship, so their only hope is to accelerate and move out into intergalactic space where particles are nearly non-existent and shut the engines down. But the faster they travel, the more time that passes in the universe.
General understanding of relativity makes this obvious, and if the reader doesn't have that knowledge, Anderson imparts it in his physics lectures that have a feel of the poetic about them. They are not only educational, but they are brilliantly crafted, mixing the wonder and power of the universe with the hard laws of physics. It's strange to find myself saying that his physics lectures actually sing and challenge the craft of some of the best writers of science fiction, mainly because I didn't think such a thing is possible. But what are often the most tedious passages in hard science fiction are delights, begging to be read over and over again, not for clarity's sake, but because they are compellingly constructed.
Thus, the Leonora Christine travels faster and faster, approaching the speed of light, hours passing on board the ship while thousands of years pass in the rest of the universe. And just as devoted as he is to the science of his work, Anderson realistically ponders the result of such a journey upon people. How does a person cope with not just the fact that everyone they know is dead, but eventually that by the best estimates, the solar system itself has been destroyed by the natural laws governing stellar evolution? Reymont and Lindgren attempt to keep hope alive among the crew, reminding them that as bad as it gets, they are still alive; but as more and more time passes in the universe, that hope becomes a burden that nearly no one can bear. Even Reymont, the feisty sergeant at arms for the ship has to rely on other people to lift his spirits. And while this may sound depressing and perhaps even maudlin, Anderson has crafted the characters so well that the reader wants to read the stories of their coping with their situation.
Not since I read Hal Clement's Mission of Gravity have I seen the type of craft that can be used to create such a compelling hard science fiction story. And not since I read James Blish's Cities in Flight have I seen a novel go the places that Tau Zero takes the reader. It's a tour de force, both of science and writing, and a desperately compelling read. I begrudged every moment I did not have the book in my hands, and I feel I have to go find more of his writing, despairing that I will only be adding whatever I find to the big stack of things to be read. Fortunately, the books shouldn't be hard to find, as I am told that Baen books is about to reprint the Anderson library. If it's true, I intend to take advantage and buy a stack of his books. And if they are even a quarter as good as Tau Zero, I'm going to be a very happy reader indeed.