The Dark Forest
Humanity knows the Trisolaran invasion fleet is coming — and that it will take four centuries to arrive. Earth also knows Trisolaris can monitor every human communication and structure in real time, leaving strategists nowhere to hide their plans.
In response, the United Nations launches the Wallfacer Project: four individuals are given sweeping authority and resources to devise defense strategies entirely inside their own minds, safe from alien surveillance, with no obligation to explain their true intentions to anyone — even their own governments. Among them is Luo Ji, an obscure astronomer-sociologist who has no idea why he was chosen, and whom Trisolaris has, inexplicably, marked for assassination above all others.
As the other Wallfacers pursue grand, very public schemes, Luo Ji drifts through personal indulgence before slowly realizing that an offhand conversation years earlier may hold the key to humanity's only real chance of survival — a theory about the nature of the universe itself, and why civilizations that reveal themselves rarely survive the encounter.
Naval political officer single-mindedly devoted to building humanity's future space fleet.
Astronomer-sociologist chosen, for reasons unknown to him, as one of four Wallfacers granted sweeping authority to plan Earth's defense in total secrecy.
Returning investigator who continues to look out for Luo Ji.
It's the hypothesis Luo Ji develops as his Wallfacer strategy: the universe is like a dark forest in which every civilization is a hunter forced to stay silent, because any civilization that broadcasts its location risks being destroyed by another. Luo Ji later uses the threat of revealing Trisolaris's coordinates as leverage to force a standoff between Earth and the invading fleet.
Joel Martinsen translated The Dark Forest from the original Chinese; the English edition was published by Tor Books in 2015. (The first book, The Three-Body Problem, and the third, Death's End, were translated by Ken Liu.)
