It’s been over a year since I read the first book of Greg Egan’s Orthogonal trilogy and I make no apologies for that. I can enjoy pretty much every single one of this author’s book but they require significant mental work and consequent preparation to fully appreciate. Reading The Eternal Flame requires having read the first book as Egan wastes no time in explaining how the physics of this universe work or the biological details of the alien species who are the protagonists of the story. Consequently I also assume this prior knowledge in this post.

Two generations after the launch of the Peerless, its crew is facing a predictable problem: overpopulation. Though farm yields have improved and the levels allocated for farmlands have multiplied, food production has no hope of coping with a population that doubles every generation. The only solution is for the females aboard to starve themselves. Under simulated famine conditions, female bodies fission into two children instead of four but this understandably takes a toll of the psychological well being of every female crew member. Biologist Carlo hopes to spare his co this ordeal by understanding this mechanism and finding a way to artificially induce it.

In the meantime, the physicists continue to search for an energy source powerful enough to turn around the Peerless to return to the homeworld and to save it from the Hurtlers, even if they have to evacuate everyone from the planet. They are granted a boon when astronomer Tamaro notices an object traveling on a trajectory that will bring it close to the Peerless. It is made of orthogonal matter, in effect their version of anti-matter, and a daring mission is launched to change its course to track the ship so that future generations can study it at will and perhaps use it as a source of fuel. This opens up new avenues of research, propelling their understanding of their universe’s physics from the realm of relativity to that of quantum mechanics. The title of the novel refers to the myth of an everlasting source of energy, an Eternal Flame that burns with no fuel, that is the ultimate goal of all such research.

With two separate research tracks and different people working on each one, there is no central character like Yalda in the first book. This means that it’s even more difficult than is usual in an Egan novel for the reader to identify with any character. More problematic is that the two tracks aren’t treated with the same degree of scientific rigour. It’s clear that performing a detailed examination of the physics that will fall out of a cosmology based on Riemannian geometry is why Egan created the Orthogonal universe in the first place. I’d go so far as to say that most of the enjoyment from reading this novel lies in following along as the physicists break discuss their theories, perform experiments, try to adjust their models to take into account unexpected results and debate each other. It’s like reading a whodunit that is completely fair. In theory, a reader who is smart enough and dedicated enough to learn the material thoroughly should be able to arrive at the same conclusions as the researchers and have a proper eureka moment of their own. I’m far from being smart enough to do this but I can imagine how satisfying it would be if I was.

On the biological research front while they also perform experiments both on the poor aborines and on themselves, there are no real models. In fact, by the end of the novel, the big discovery that they make has a much more significant impact on the society aboard the Peerless than any of the physicists’ findings, yet they don’t really understand why it works, only that it does. It’s frankly embarrassing that they don’t even have the equivalent of a cellular model of how their biology works. The biologists simply got lucky by finding just the right light signals that can be replayed to stimulate the effects they’re interested in. At the same time, much of the excitement and drama of the novel occurs on this front. Some scenes, such as chasing down a pair of aborines and rescuing a hostage, seem to have been included only because Egan felt that he needed something resembling a more conventional novel but the narrative balance feels way off. The precise details of how Carlo chases down an aborine don’t really matter within the wider context of the overall story.

Still, there are plenty of interesting things going on here. One way of looking at it is that this novel restates the traditional conflict between men and women in the most original way I have yet seen. Carlo searches for a technological key that will allow them to control the reproductive fissioning process and spare women from being forced to starve themselves but as another character pointed out, it didn’t even occur to him to look into the matter of starving the males even though he knows that in the aborines, this contributes to the females fissioning into two instead of four children. It also struck me how powerful an emotional chord it must be to have a mother being able to hold a child in her arms, something that has never occurred in the history of this species. It’s a completely novel situation that has no parallel for humanity and so invokes a new set of emotions. Characteristically for him, Egan doesn’t dwell on these emotions. On the other hand, it feels gratifying that he trusts the reader well enough to realize for themselves how momentous this is. On the other, the occasion seems momentous enough that it calls for more than a nod from Egan.

For all of these reasons, I both love and hate this novel. I love that it exists and I wished that I had the intelligence and mathematical background to fully appreciate its exploration of physics. But I also acknowledge that it is deeply flawed as a novel, with a horribly unbalanced narrative and unsatisfying character development. The usual criticisms of Egan’s work apply here: his characters don’t feel like real people and they win arguments against ideological opponents too easily. This is disappointing given how well Egan succeeded in developing the character of Yalda in The Clockwork Rocket. It’s a given that I will eventually go on to read the final book of the trilogy but that will be both because of the immense amount of work it requires and because I didn’t really like this one all that much.