Cixin Liu 2016. Death’s End. Translated by Ken Liu. Kindle Edition. Also New York: Tor Books. 608 pp.

A worthy conclusion to the Three-Body Problem books and ideas.

Cixin Liu is not short of ambition. The scope of this book is likely to leave the reader, for a while, uninterested in little issues like obtaining food and maintaining personal safety. The here and now made humdrum. As might be expected by a novel which ends at the end of the universe, and scouts out so many original ideas along the journey.

The first parts of this novel feel like a realisation of game theory with scenarios played out between the civilisations of Earth and Trisolaris, and also between factions of humans. The strategies employed by various players depending on who, if anyone, has strategic ascendancy evoke the Prisoner’s Dilemma and other thought experiments in philosophy and mathematics. For example, given that in a vast universe there are bound to be vastly technically superior races who would exterminate potential future rivals (us) at the drop of a hat, is there a way to stay safe and avoid extermination?

By the end, the book is more an exploration of ideas set out by cosmologists and theoreticians like Max Tegmark in Our Mathematical Universe and David Deutsch in The Beginning of Infinity: Is the universe a mathematical object? What might dark matter be? Will the universe expand forever or collapse in another big bang? All these are in Cixin Liu’s vision, and quantities such as the cosmological constant and speed of light are opportunities, not constraints. What would the other dimensions hypothesised by physicists look like if we could encounter them? In this novel, dimensions are big, so to speak.

It says something about this book that contemporary theories in physics and cosmology are weaved into the story in an entirely (to me) believable way, yet human interactions often seem to be lifted out of pop psychology and future political scenarious seem naïve and incredible. Given how vanishingly few rational and moral humans have been elected to positions of political power up to now in human history, is it really plausible that only a hundred years or so hence the population of the entire planet will really decide trust one man on a dead man switch to keep humanity safe from an attack by Trisolaris? The ways that various narrative tools (like memoir excerpts) are used to explain what is going on also seems clumsy; certainly not the sort of thing the late and much lamented Iain M. Banks would ever be caught doing. Nevertheless, it is a pity that many potential readers of hard SF can’t get past these trivial blemishes to the really important stuff: big ideas that take what we think we know about current physics and extrapolate to explore what might be possible if one was able to be out and about in the wider universe.

Cixin Liu paints human societies and their technologies in several future times. I was interested in his choices of what technologies would mature and become influential. Thus he has humans (starting in the quite near future) having perfected hibernation technology so that it is routine to go into suspended animation and awake 50 or 200 years in the future. No doubt this is more of a plot device rather than a bet on plausible future technologies, since it lets Cixin Liu’s characters travel through the story and greatly extend their influence on the plot (and on the reader). But this device never seems entirely believable, probably because solutions to various problematic social implications never become clear. Who keeps the lights on if everyone wants to escape to the future? If diseases are cured or a better quality of life is on offer in the future, who is going to hang around and make those advances in knowledge? Other developments, such as artificial intelligence, barely seem to influence these futures. They are there, but they have trivial roles. It is as if AI will enable better toasters, but not much more.

Nevertheless, the few negatives are insignificant while the many positives are all-consuming; this and the preceding two books are memorable SF, up there very close to the greatest.