Adventists
One of two main factions of the ETO. Adventists are fundamentalists, believers in Evans's Pan-Species Communism, and have completely given up on human nature. They are motivated by despair and hatred of humanity, and they welcome Trisolaran "reformation" or even the extinction of humans. Their motto, courtesy of Evans, is: "We don't know what extraterrestrial civilization is like, but we know humanity." Pan Han is an Adventist.
Liu writes that the Adventists' alienation in the ETO arose from "the faults of human civilization itself."
Chaotic Era and Stable Era
In the game Three Body, any time that is not a Stable Era—during which the behavior of the sun(s) can be predicted—is a Chaotic Era. In a Chaotic Era, it is impossible to predict when/if a sun will rise, how many suns will rise, the suns' proximity to the planet's surface or one another, and when/if a sun will set. Extreme heat, extreme cold, and gravitational/ozone events can occur during Chaotic Eras. During Chaotic Eras, almost all people in the world dehydrate for survival. The preliminary goal of Three Body is to create an accurate prediction of Stable Eras so that society can rehydrate and progress without being destroyed by an unpredictable Chaotic Era.
cosmic microwave background
As explained in The Three-Body Problem, the cosmic microwave background is observable radiation that fills the entire universe, created from the "embers" left over after the universe cooled post-Big Bang. Wang Miao sees the cosmic microwave background flicker in a 5% fluctuation—something that shouldn't happen even over a million-year period—as proof of the countdown's reality.
The apparent flickering of the cosmic microwave background is revealed to be a trick orchestrated by sophons sent by the Trisolarans to confuse humanity.
Cultural Revolution
A sociopolitical movement in the People's Republic of China initiated by Mao Zedong in 1966 and lasting until his death in 1976. The goal of the Cultural Revolution was to preserve Chinese communism and spread Maoist thought. The period included many instances of violence and chaos, with reported death tolls ranging widely, from tens of thousands to tens of millions.
A translator's note in The Three-Body Problem lists the "Five Black Categories," the political identities most targeted during the revolution: landlords, rich farmers, counter-revolutionaries, "bad elements," and right-wingers (especially capitalists).
Earth-Trisolaris Organization
The Earth-Trisolaris Organization (ETO) is an organization whose stated goal is to "invite Trisolaran civilization to reform human civilization, to curb human madness and evil, so that the Earth can once again become a harmonious, prosperous, sinless world." Within the ETO, various factions have ulterior motives, ranging from the destruction of humanity to protecting humans from Trisolaran invasion.
The ETO consists almost entirely of self-described "spiritual nobles," or well-educated high-class people. Many of them are elites from the academic and financial spheres.
The ETO was founded by Mike Evans. Ye Wenjie is the commander-in-chief, though this is more of a "spiritual leader" role; she doesn't participate in the organization's operations.
Flying Blade
A nanomaterial developed by Wang Miao that is incredibly strong and thin, about one-hundredth the thickness of human hair. Flying Blade filaments are spread across the Panama Canal and used to slice the ETO's Judgment Day into pieces.
The countdown is revealed to be Trisolaris's attempt to halt Flying Blade research because it could theoretically help humans develop their space technology.
the Frontiers of Science
The Frontiers of Science is an international academic group whose goal is to discover the boundary of scientific study. It is very influential and full of famous scholars. Wang Miao has contact with members of the Frontiers of Science, primarily Shen Yufei, but he's not a member himself.
gradualistic mode
According to the documents of the Red Coast Project, "gradualistic mode" is one of two ways scientific research can be converted into practical applications. In gradualistic mode, progress is made by applying research to technology gradually; advances accumulate until a breakthrough is made. The example given is the development of space technology, which was the result of hundreds of years of applied aviation research.
Judgment Day
The ETO's ship, a modified oil tanker, from which they receive transmissions from Trisolaris. Da Shi comes up with a plan to use Wang Miao's Flying Blade to destroy the Judgment Day and retrieve the data on Trisolaris stored there.
maser
In a translator's note, Ken Liu explains that a maser is like a laser but for electromagnetic radiation—typically microwaves. In the Monitoring Department at Red Coast, Ye Wenjie uses a maser as part of the base's very sensitive reception system.
Pan-Species Communism
An ideology created by Mike Evans centered around the tenet "All lives are equal," including those of animals and plants.
Project Sophon
Project Sophon is a Trisolaran project to halt scientific progress on Earth to ensure the Trisolaran invasion's success. Project Sophon transforms single protons into superintelligent computers, which are then fired at Earth, where they prevent humanity from manipulating matter in the micro dimensions, thereby advancing technologically. The sophons accomplish this by interfering with results at particle accelerators, making science appear random and hopeless, as well as creating "miracles," like images appearing on film and the cosmic microwave background apparently "flickering."
Redemptionists
One of two main factions of the ETO, formed long after the ETO. The Redemptionist group is religious, and they worship their idea of the advanced Trisolaran civilization. They believe "the Lord" (Trisolarans) is in crisis, and the duty of salvation falls on humanity. The Redemptionists' ultimate goal is to save the Lord, and though they have some willingness to sacrifice the human world to some degree, their ideal solution is to avoid the invasion of Earth. Trying to solve the three-body problem is a religious ritual of their faith. Ye Wenjie is a Redemptionist.
Liu writes that the Redemptionists' alienation in the ETO arose from "the yearning and adoration for a more advanced civilization."
saltatory mode
According to the documents of the Red Coast Project, "saltatory mode" is one of two ways scientific research can be converted into practical applications. In saltatory mode, research is rapidly applied to technology, leading to a technological leap. The example given is the development of atomic weapons, which physicists believed would be impossible into the 1940s, when atomic energy was developed within a very short period.
SETI
Acronym for the Search for Extraterrestrial Intelligence. The Red Coast Project report claims that SETI is the field with the greatest possibility for a technology leap.
struggle session
A struggle session or denunciation rally is a public event during which "class enemies" are publicly humiliated and often tortured or beaten. This is usually done in a related public space (town square, university, workplace) and often performed by people the victim knows (students against teachers, children against their parents, spouses against each other, etc), generally for the purpose of exciting an audience and furthering Maoist thought reform.
In Section I: Silent Spring, Ye Wenjie's father, Ye Zhetai, is beaten to death during a struggle session at Tsinghua University in 1967.
Survivors
A small third faction within the ETO. The Survivors formed after confirming the incoming Trisolaran invasion, and their goal is to ensure their descendants' survival of the inevitable conflict. Serving the Trisolaran invaders is one of the Survivors' tactics.
Compared to the other two factions, the Survivors tend to come from lower social classes, and most are from China. They are a rapidly growing faction, though much smaller than the Redemptionists and Adventists in The Three-Body Problem.
Liu writes that the Survivors' alienation in the ETO arose from "the strong desire for one's descendants to survive that final war."
technology leap
A technology leap occurs when fundamental science is converted to applied technology across a great span in an extremely brief time interval. According to reports from the Red Coast Project, the field with the greatest potential for a technology leap is the Search for Extraterrestrial Intelligence (SETI).
Three Body
Three Body is a video game created by the Earth-Trisolaris Organization, especially Redemptionists, to recruit members to their cause. Three Body is a completely immersive video game, played wearing a V-suit, in which players follow the rise and fall of civilizations through Stable and Chaotic Eras. Three Body progresses through civilizations independently for each player, possibly with different worlds and goals.
the three-body problem
A problem in orbital mechanics in which one takes the positions and velocities of three masses and solves for their subsequent motion (also called the n-body problem). In The Three-Body Problem, the three suns of the Trisolaran system create a real-life three-body problem. The suns' movements are unpredictable, so it's functionally impossible to predict Stable and Chaotic Eras with accuracy.
This will eventually result in Trisolaris's destruction due to collision with one of the suns. Trisolarans' only option is to settle a new solar system.
Trisolaris
The planet inhabited by Trisolarans. Trisolaris is located in a tri-solar system, a literal three-body problem, and their planet will soon be destroyed by proximity to one of the suns. The Trisolaran civilization (much more technologically advanced than Earth's, though progressing at a slower rate) must find a new system to inhabit.
V-suit
A popular piece of gaming equipment consisting of a panoramic viewing helmet and a haptic feedback suit, allowing players to experience the physical sensations of the game (heat, pain, contact, etc). The game Three Body is played wearing a V-suit.
