Forty-two hundred million years or so from now, two galaxies will be colliding. . . .

In this Hugo-Award nominated story, Charles Stross takes up one of the classic science fictional forms: the story of human destiny on a cosmic time scale. H. G. Wells brought the theme into science fiction in The Time Machine, with the Time Traveler watching the dying sun rise slowly over a beach in the inconceivably remote future earth of 32,000,000 A.D.; Olaf Stapledon worked on vaster time scales, eventually recounting the entire history of the cosmos over a span of half a trillion years in Star Maker. It’s a mark of how our vision of the cosmos has changed, in less than a century, that Stross’s latest scenes are set roughly a trillion years from now.

How do you tell a connected story on this time scale, inconceivably longer than any human lifespan we can even imagine? Stross resorts to the same expedient as Wells: time travel. In fact, he explores the implications of time travel quite thoroughly, from the economics of scarcity (only one time gate can be open at a given instant, apparently anywhere in the cosmos, so opportunities for time travel get used up) to the social organization of time travelers. His viewpoint character, Pierce, is a recruit of a secret organization that travels backward and forward in time, changing history “to prevent wild efflorescences of resource-depleting overindustrialization, to suppress competing abhuman intelligences, and to prevent the pointless resource drain of attempts to colonize other star systems,” with the ultimate aim of prolonging human existence as far as possible—even reshaping the sun to prevent its depletion in a mere few billion years, and protecting Earth’s orbit from the Milky Way’s collision with Andromeda.

But any organization so powerful must have its own hidden agendas, and that’s a big part of what this story is about. One of Stross’s recurring themes (see for example Glasshouse, his Prometheus Award-winning novel of 2006) is the impact of memory erasure. Stross’s secret organization, the Stasis, has the ultimate in memory erasure: the ability to change history so that an agent’s memories no longer refer to anything outside themselves. His plot turns on an irony: On one hand, the human civilizations throughout Earth’s prolonged existence routinely invent pantopticon surveillance technology, indeed so routinely that the Stasis’s definition of a civilized society is one where every human act is recorded (though apparently the inner workings of brains remain inaccessible). On the other, the final records of humanity, in the great library at the end of the Earth’s existence, cover all the alternate pasts, with no simple way to find any particular past. This is the basis of the metaphor of his title: a palimpsest is a parchment that has been written on once and then scraped clean for reuse, leaving traces of the original text from which sufficiently advanced technology can reconstruct its former content. The very mass of information provide a hiding place for conspiracies both within and against the Stasis.

And at this point Stross’s story becomes curiously reminiscent of one of the classics of science fiction: Isaac Asimov’s The End of Eternity, a startling novel in which Asimov criticized the very rational bureaucracies that most of his fiction idealized. Like the Stasis, Eternity worked to prolong human survival, and to prevent the pursuit of dangerous extremes such as interstellar colonization, through manipulation of human history. Like the Stasis, Eternity recruited from every era, and faced its recruits with the knowledge that their own birth worlds would eventually be erased by some historical readjustment. And like the Stasis, Eternity attracted personalities with certain pathological traits—or inflicted those traits upon them. Both novels ultimately turn on their viewpoint characters realize that the organization that has become their home, their family, and indeed their nation is not the solution humanity has been seeking, but the problem.

To be specific, the problem is power. The Stasis is aware of the temptations of power: Stross writes, “True world governments were rare, cumbersome dinosaurs notorious for their absolute top-down corruption and catastrophic-failure modes; the stasis tended to discourage them.” Vernor Vinge could not have said it more clearly! But its own power traps it into its own failure modes, its own narrowness of vision and denial of human potentiality.

And the solution? That would be telling. But the solution’s scale is impressive; indeed, it’s as comparable to Stapledon as the book’s timespan. And it’s presented as a truly impressive, indeed a breathtaking, final reveal. Stross gave me both the pleasure of a classic science-fictional eschatology and the satisfaction of its having a hard science fictional basis. Stross mentions that he was tempted to turn Palimpsest into a novel; I would be equally tempted to read it if he did. Not least because of the absolute appropriateness of the story’s ending to its carefully developed theme. Palimpsest is one of the most science fictional stories I have read in years.