# The Dark Forest

The Dark Forest (Chinese: 黑暗森林) is a 2008 science fiction novel by the Chinese writer Liu Cixin. It is the sequel to the Hugo Award-winning novel The Three-Body Problem in the trilogy formally titled Remembrance of Earth's Past (colloquially referred to by Chinese readers by the title of the first novel). The English version, translated by Joel Martinsen, was published in 2015.
The novel revolves around humanity's attempts to construct a defence against an impending invasion fleet from an alien planet. It explores the dark forest hypothesis (so-named after the novel), a possible solution to the Fermi paradox, though similar theories have been described as early as 1983.

## Plot

Following the events of The Three Body Problem, humanity unites to defend Earth against the invasion fleet of the alien planet Trisolaris, which will arrive in approximately 400 years. Earth's defence is severely hampered by Trisolaran "sophons", omnipresent but unobservable supercomputers that spy on all Earth activity and interfere with technological development.
However, as sophons cannot surveil human thought, the United Nations appoints four "Wallfacers": individuals tasked with developing defence strategies known only to themselves, and are provided near-unlimited power to do so. Three of the Wallfacers are renowned for their military, political and scientific expertise, but their secret strategies are ultimately exposed by Trisolaris' agents, the "Wallbreakers".
The fourth Wallfacer is the obscure sociologist and ex-astronomer Luo Ji who, despite being less qualified, is chosen because he is the target of the only assassination order ever issued by Trisolaris. Initially unsure why he is feared by Trisolaris, Luo eventually realizes it is because of a prior encounter with astrophysicist Ye Wenjie, who was the first human to establish contact with Trisolaris. Ye had encouraged Luo to develop a theory of "cosmic sociology", the central claim of which is that a civilization which broadcasts its location to the universe will almost certainly invite its destruction by another civilization. Luo tests his hypothesis by broadcasting the location of a star 50 light-years away, then entering hibernation while awaiting to see if the target star is destroyed, which it is by an unknown advanced civilization. The Trisolarans, realizing Luo has uncovered a way to destroy Trisolaris, send probes to jam any further cosmic broadcasts.
200 years later, Luo is revived into a utopian society boasting advanced technology. However, the widespread belief in Earth's superiority is shattered when its entire space fleet is annihilated by a single Trisolaran probe. Assuming Earth is almost certain to lose the war, two surviving spaceships escape the Solar System to establish civilization elsewhere.
Amidst the ensuing panic on Earth, Luo resumes his Wallfacer role and dedicates his efforts on a seemingly ineffective defence strategy, which is actually a secret ruse to overcome the Trisolaran jamming of cosmic broadcasts. Threatening Trisolaris with mutual assured destruction should he broadcast Trisolaris' (and by proximity, Earth's) location, Luo forces Trisolaris to divert its invasion fleet and to aid human scientific progress.
Years later, Luo converses with a pacifist Trisolaran. They agree that it may be possible for galactic civilizations to engage in peaceful relations.

## Principal characters
### Ye Wenjie (叶文洁)

    Astrophysicist who initiated contact between Earth and Trisolaris. Spiritual leader of the Earth Trisolaris Organization (ETO), the network of pro-Trisolaris human agents on Earth.

### Zhang Beihai (章北海)

    Political commissar in the PLA Navy and later the Chinese Space Force, responsible for promoting "triumphalism": the conviction that Earth will eventually prevail over Trisolaris. However, he secretly harbors the opposite convictions of "defeatism" (that Earth is doomed to defeat) and "escapism" (that humanity should escape the Solar System and re-establish civilization elsewhere).

### Shi Qiang (史强)

    Also nicknamed Da Shi (大史), a returning character from The Three-Body Problem. The Wallfacer Program's Head of Security who becomes a close ally to Luo Ji.

### Ding Yi (丁仪)

    Theoretical physicist, returning from The Three-Body Problem. The first human to physically make contact with a Trisolaran object.

### Zhuang Yan (庄颜)

    Graduate of the Central Academy of Fine Arts, she later becomes Luo Ji's wife.

### Wallfacers
#### Frederick Tyler (弗雷德里克·泰勒)

    Former US Secretary of Defense, whose defence strategy features an Earth fleet falsely defecting to the Trisolaran fleet, where an attack can be launched. His plan is exposed by the Wallbreaker "von Neumann".

#### Manuel Rey Diaz (曼努尔·雷迪亚兹)

    Former President of Venezuela, whose defence strategy was to threaten the propulsion of Mercury into the Sun, a mutual assured destruction scenario where both Earth and the invading Trisolarn fleet will be destroyed by solar debris. His plan is exposed by the Wallbreaker "Mozi".

#### Bill Hines (比尔·希恩斯)

    English neuroscientist, physicist and former EU president, whose strategy is to use mind-control to deceptively spread defeatism, thus promoting escapism to ensure humanity's survival. His plan is exposed by the Wallbreaker "Aristotle", who is actually his wife Yamasugi Keiko (山杉恵子).

#### Luo Ji (罗辑)

    Ex-astronomer and sociologist. He forces a truce by threatening to broadcast Trisolaris' position which will invite its destruction by a third party.

## Videos

* Waterdrop, referring to the Trisolaran droplet probe, is a 14-minute tribute film produced by Wang Ren, who was then a graduate student studying Architecture in Columbia University. The author Liu Cixin commented, "This is the kind of film I have in mind. If the feeling of such an atmosphere can be delivered in a Three Body Problem film, I would rest in peace after I die."
* MC Three Body - The Dark Forest is an animation series produced by a group of Chinese fans. Initially a machinima series produced using the video game Minecraft, they later switched to using professional animation software. The series was released online at the beginning of 2018.
* A Chinese animated series based on The Dark Forest aired from December 10, 2022 to March 25, 2023.
* A three-part documentary series entitled Rendezvous with the Future which explores the science behind Liu Cixin's science fiction was produced by BBC Studios and released by Bilibili in China in November 2022. The second episode covers many ideas featured in The Dark Forest such as the space elevator and artificial hibernation. An international version of the series has not yet been released.