Timeline of the Trilogy
This timeline summarizes the major events that unfold across the story.
The events span decades and reshape humanity's understanding of the universe.
Book One: The Three-Body Problem
Cultural Revolution Era (1960s–1970s) The story begins during China's Cultural Revolution. Ye Wenjie witnesses the death of her father and is sent to work at Red Coast Base, a classified radio observatory. Years of isolation and disillusionment culminate in her decision to respond to a Trisolaran signal — and to include Earth's location in her reply.
Discovery of the ETO (Present Day) Decades after the original transmission, a mysterious organization called the Earth-Trisolaris Organization (ETO) is operating covertly, assisting the Trisolarans and attempting to undermine Earth's defenses. Nanomaterials researcher Wang Miao is recruited to investigate, working alongside detective Da Shi. The investigation eventually reveals the existence of sophons and the Trisolaran invasion fleet.
The Virtual Reality Game The ETO uses a virtual reality game — Three Body — to recruit intellectuals sympathetic to their cause. The game depicts the unstable civilization on Trisolaris, struggling to survive in a chaotic three-sun system. Players who complete the highest levels are recruited directly.
Sophon Deployment Revealed Humanity learns that the Trisolarans have deployed sophons — engineered subatomic surveillance devices — to Earth. The sophons are actively disrupting particle physics experiments, freezing the development of human science at a critical moment. The announcement is deliberate: Trisolaris wants humanity to know it is being watched.
The Invasion Fleet Announced Trisolaris publicly confirms that a fleet of 1,400 ships is en route to Earth. It will arrive in approximately 400 years. The Era of Crisis begins.
Book Two: The Dark Forest
The Wallfacer Project The United Nations creates the Wallfacer Project in response to the sophon surveillance problem. Four individuals are granted extraordinary resources to develop secret defense strategies — plans that exist only in their minds and never need to be explained. Luo Ji is among the four selected.
Zhang Beihai's Actions Military officer Zhang Beihai, convinced that defeatism will undermine humanity's long-term survival, takes covert action to protect the integrity of the fleet-building project. He uses hibernation technology to project himself centuries forward into the crisis.
The Droplet Arrives The Trisolarans send an advance probe — the Droplet — to demonstrate their technological superiority. In a matter of hours, it destroys most of the human space fleet gathered in formation. The demonstration is overwhelming and intentional: it is meant to show what the invasion fleet will be capable of.
Luo Ji's Breakthrough After years of apparent inaction, Luo Ji reveals the Dark Forest Theory and its deterrence application. He has identified the coordinates of a distant star system, broadcast them, and confirmed that the system was subsequently destroyed by an unknown force. He now holds a dead man's switch: if he is killed or fails to maintain the system, Trisolaris's coordinates will be broadcast — and Trisolaris will be destroyed by whatever apex predators inhabit the Dark Forest.
The Deterrence Stalemate Trisolaris and Earth enter a deterrence equilibrium. The invasion is held in check. The Era of Deterrence begins. For a deeper look at how deterrence works, see Cosmic Deterrence.
Book Three: Death's End
Centuries of Stability The deterrence holds for a period of time. Human civilization advances and changes. The original protagonists pass from the scene, some preserved through hibernation.
The Deterrence Fails A series of events — including manipulation of the human controller and political decisions made under pressure — leads to the deterrence system breaking down. Trisolaris's location is ultimately broadcast, and the Trisolarans face the consequences they spent centuries trying to avoid.
Dimensional Weapons The arrival of dimensional weaponry — technology capable of reducing three-dimensional regions of space to two dimensions — reveals that the Dark Forest contains threats far greater than either humanity or Trisolaris. The universe is more dangerous than the trilogy's characters initially understood, and the logic of cosmic survival is harsher than even Luo Ji's theory described.
The Final Reckoning The events of Death's End expand the story to cosmological scale, with consequences that extend billions of years into the future. The three novels move from a story about one civilization encountering another into a story about the fundamental nature of a universe governed by Dark Forest logic — and about what, if anything, survives within it.
For more detail on specific phases, see First Contact Timeline and Human Civilization Timeline.