The Clockwork Rocket by Greg Egan

Reviewed by Michael Levy

The Clockwork Rocket US cover

The Clockwork Rocket UK cover

I'm what you might call a physics groupie. I hang out with physicists on a regular basis and I read the physics and astronomy articles in Science News first. I have to admit, though, that the last formal physics course I took was way back in high school, during the dark ages, when it was still possible to think of the atom as a miniature solar system. I mention this by way of admitting that I may not be the ideal reviewer for Greg Egan's fine new novel The Clockwork Rocket, the first volume in his Orthogonal series. I mean, forget about Clarke, forget about Clement, heck, forget about Robert L. Forward and Stephen Baxter; this is real hard science fiction, multiple diagrams, equations and all. Egan doesn't just play with the net up, to quote Gregory Benford; he teaches you the physics of tennis while he's at it.

The Clockwork Rocket takes place in a different universe than ours, one with decidedly different physics. To quote Egan's website, it is a Riemannian universe, one described by "geometries that we'd normally think of as kinds of space, whether flat or curved, where all the dimensions are treated as fundamentally the same. In contrast, in the Lorentzian space-time of our own universe, one of the dimensions, time, is singled out for special treatment." If you want to know exactly how the physics of a Riemannian universe might work, Egan spells it out in detail in the text, on his website, and in appendices at the back of the book. More immediately to the point, however, the novel concerns a group of alien scientists, who live in the Riemannian universe that Egan has created and who must figure out the relevant physics for themselves in order to preserve their species from extinction.

Egan doesn't immediately announce what he's doing at the beginning of the book, although the jacket copy gives away some of the more spectacular differences between his universe and ours. This is, for example, a universe where light does not have one speed and the stars in the sky all have multicolored trails because the various spectra reach the viewer over a period of years. It is a universe where "the creation of light is accompanied by the creation of kinetic energy," rendering all matter inherently less stable; a person who works too hard at physical labor may quite literally burst into flame and a meteor strike on a large planet could turn it into a second sun. It is also a universe where a spaceship traveling at near light speed can, from the viewpoint of several generations of crewmembers, return to its home planet hundreds of years after it was launched, though only a few years will have passed for those who stayed behind. Egan has extrapolated dozens of other large and small differences between our Lorentzian universe and his Riemannian one, concerning everything from how life might evolve and metabolize raw materials, to how a rocket engine would work, to how two materials in close proximity might wear on each other, all given this radically different physics.

The story concerns an intelligent alien species who are in some ways very different from us, but in other ways quite similar. Protean in form, they are able to sprout arms and legs in a variety of different combinations as needed. With training, they can learn to produce images, even writing on their bodies and absorbing those images from each other through close contact. They have two sexes, but the female of the species reproduces by splitting into four parts, essentially dying as a person to produce offspring. Children tend to be born in paired couples who then go on to reproduce together themselves, but it occasionally happens that an odd number of children are born or one of a pair dies. The resulting solo is often considered strange, a sort of pervert, and is pressured to pair up with another solo of the opposite sex. Women are larger and stronger, but men of necessity do the bulk of both the long-term planning and the childcare. In a sense, although nearly every woman's life is cut short by reproduction, it's mostly just men who die. As one might imagine, the existence of hollin, a medication that can defer women's reproduction almost indefinitely, is controversial, considered quite literally a life saver by women who want more out of existence than just reproduction, but viewed as something akin to blasphemy by (generally) male conservatives. Given the form of reproduction Egan has postulated, hollin is a necessary element in the text for a variety of plot-driven reasons, but the sometimes violent male reaction against it also signals the author's concern with our society’s current debate over abortion and birth control. This in turn serves as an avenue of engagement with the text for the audience; even creatures as strange as these have concerns that parallel our own, both literally and emotionally.

As the book opens, society is in the throes of an industrial revolution. A variety of purely mechanical, clockwork technologies have been created, but there is nothing comparable to workable electricity. Yalda, Egan's protagonist, is a solo, and worse yet a solo female with no interest in reproduction, who'd rather discover how machines work than farm. Her father, a relatively enlightened sort, encourages her to go to school where she blossoms, despite gaining a reputation as an oddball, and is eventually sent on to university. There she finds a complex and exciting world of new ideas and changing customs, not to mention some very real danger. Yalda, who remains somewhat naïve and unworldly, is taken under her wing by an older scientist who is herself a solo, and she is introduced to other well-educated women at the proto-feminist Solo Club. Although it is illegal, these women take hollin to prolong their life spans by staving off spontaneous asexual reproduction, which can occur under crowded urban conditions. Solos are the subject of considerable prejudice and when the son of a civic leader attacks Yalda she is imprisoned and tortured for fighting back. Radicalized by this experience, Yalda studies hard, develops her own revolutionary theory of rotational physics, resists attacks on her work by hidebound colleagues, and finally gains a university teaching position and the respect of a new generation of scientists. Her growing concern, however, is with the Hurtlers, fast moving meteors which have begun to speed through the solar system in increasing numbers, and which, Yalda realizes, herald an impending catastrophe for her world. The daring plan that Yalda and other scientists come up with to buy the time with which to find a solution to this problem is to build a giant rocket that can approach the speed of red light, the slowest form of light in the universe. They will return home only a few years later, from their world's perspective, but generations will have passed on the ship, during which the crew may invent the science to save their world.

As a reviewer I have on more than one occasion used some variation on the phrase "This novel is not for everyone," and this is certainly the case for The Clockwork Rocket. It's hard to imagine any other writer in our field feeling comfortable stopping his or her narrative periodically, heck, frequently, for physics lectures, and this may derail readers whose sense of wonder isn't satisfied by such things. When Egan does this, however, the story takes on some of the feel of a Platonic dialogue, with Socrates deducing a wide range of brilliant ideas and the other characters periodically answering back, "Well, so it would seem," or "This cannot be disputed." In some ways Egan's method is reminiscent of the clumsy infodumps found in science fiction of the Gernsback era, but there's a key difference here. Unlike the typical Gernsback-era writer, Egan knows exactly what he's doing. The characters who lectured on and on in the early Amazing stories are mostly telling each other what they already know in the most clumsy manner imaginable. Their purpose, transparently, is to let the reader in on some super-scientific idea of the author's, but they're invariably talking nonsense. Egan's characters, however, given the scientific premise that underpins the novel, appear to make sense, though what they're saying may be hard to follow. In fact they come very close, I think, to recreating the kind of dialogues that actually occur between brilliant scientists. One can imagine Einstein conversing with his students in this manner as they walk the tree-lined sidewalks of Princeton, changing the world as they go. Yes, these scientific discussions stop the action of the story dead in its tracks and they violate all traditional rules of good narrative, but, if you can follow the science, even a little bit, even though it’s not real, oh my!

Many science fiction writers have used the generation starship trope, so many that at least one scholarly book has been published on the subject. The hollowed-out asteroid as generation ship is also nothing new, but I doubt that anyone has ever attempted to launch what is essentially a hollowed-out asteroid (actually in this case an entire mountain) from the surface of a planet. In our universe such a thing would be entirely impossible, of course, but Egan's Riemannian physics makes it feasible. Egan also devotes a great deal of space to describing how his starship might be constructed, again including technical details, but also paying attention to the practical needs of his crew, needs that are in some ways identical to but in other ways differ significantly from our own. This detail exemplifies one of The Clockwork Rocket's greatest strengths. On one level we have all of the sophisticated and abstract scientific data describing Yalda's universe and its many (from our point of view) oddities, but on another level, we have a great deal of attention paid to more visceral matters. What kind of closed environment will allow aliens with their particular nutritional needs to produce enough food to survive? How exactly will they limit reproduction on board the starship? How do you run a sophisticated machine with millions, perhaps billions of cogs and springs, but no practical understanding of electricity (and, yes, we have a small steampunk vibe going here too, though it's less than you might expect).

In The Clockwork Rocket Greg Egan has brought together a number of science fiction’s standard tropes—the depiction of a truly alien species, the creation of a universe with physics different from our own, the bildungsroman of a genius inventor, a race to avoid the end of the world, and a generation starship—in a way that is both novel and satisfying. The physics is decidedly heavy and the dozens of diagrams and equations will be off-putting to some readers, but others, I'm sure, will find them endlessly engaging and I can easily imagine the development of a blog or two devoted to arguing over their intricacies. Beyond the science, however, as is often the case with Egan's best work, this is also a gripping and, I suppose the appropriate word is "human" story. We come to care deeply about Yalda, an ugly duckling who, if she never becomes a swan, nonetheless triumphs beyond all expectations. We also care about her friends, her society and, indeed, her entire fascinating, down the rabbit hole Riemannian universe. Book two of Orthogonal will presumably be dominated by the generation starship trope, but Egan has done the ground work necessary to set up any number of engaging variations on the scientific discoveries he's already revealed and surely still more surprises are in store. I don’t know whether or not I'll be able to handle the physics, but I do look forward to them.


Michael Levy teaches English at an obscure Wisconsin university and is a past president of both the Science Fiction Research Association and The International Association for the Fantastic in the Arts.