### What is the Three-body problem

The Three-Body Problem refers to a classic problem in celestial mechanics and physics that involves predicting the motion of three celestial bodies under the influence of their mutual gravitational attraction. The challenge arises from the complex and chaotic nature of the interactions between three massive objects.

In the context of astrophysics and celestial mechanics, the problem can be stated as follows: Given three massive bodies (such as stars or planets) in space, each exerting gravitational force on the other two, predict their motions over time. While the gravitational interactions between two bodies are well understood and follow Kepler's laws of planetary motion, the addition of a third body introduces complexities that make predicting their orbits analytically difficult.

The Three-Body Problem has been studied for centuries, and solutions exist for specific scenarios, such as the restricted three-body problem where one of the bodies is much less massive than the other two. However, in general cases, there is no simple, closed-form solution. The motion of three celestial bodies in a gravitational system can lead to chaotic behavior, making long-term predictions challenging.

### The Three-Body Problem (novel)

The term "Three-Body Problem" is also the title of a science fiction novel written by Liu Cixin, originally published in Chinese in 2008. The novel explores the consequences of a universe where the Three-Body Problem is fundamentally unsolvable, and it has gained international acclaim for its imaginative approach to science fiction and its incorporation of scientific concepts.

The story begins during China's Cultural Revolution, where physicist Ye Wenjie witnesses her father's public execution for political reasons. Ye Wenjie is later sent to work at a secret military base called Red Coast Base. There, she becomes involved in a top-secret project involving the study of extraterrestrial civilizations.

Decades later, in the present day, nanomaterials researcher Wang Miao gets drawn into a mysterious virtual reality game called "Three-Body," where players try to solve the Three-Body Problem, a dilemma in predicting the motion of three celestial bodies. As he delves deeper into the game, Wang Miao discovers connections to a real-world scientific mystery and a conspiracy that could have profound implications for humanity's future.

The novel weaves together elements of hard science fiction, historical events, and political intrigue. It explores themes of human nature, the consequences of scientific discovery, and the potential impact of contact with an extraterrestrial civilization. The trilogy as a whole delves into grand cosmic and philosophical ideas, making it a unique and thought-provoking work within the science fiction genre.