"The Three-Body Problem" is a science fiction novel by Liu Cixin that explores the consequences of first contact with an alien civilization. The story begins during China's Cultural Revolution and follows a physicist who discovers a secret military project that communicates with extraterrestrial life. The title refers to a complex physics problem involving predicting the motion of three celestial bodies. In the novel, this problem symbolizes the unpredictable interactions between humans and the Trisolarans, an alien race from a planet with an unstable orbit around three suns.