📖 Three-Body Glossary: Key Terms Explained in English

As a foreign fan, one of my biggest challenges was tracking all the unique terms in Three-Body. Here's a comprehensive glossary to help you navigate the trilogy. I've included Chinese and explained concepts in plain English.

The central theory of cosmic sociology. The universe is a dark forest where every civilization is a camouflaged hunter. Any civilization that reveals its existence will be destroyed by another. It explains why the universe is silent despite presumably being full of life.

> "The universe is a dark forest. Every civilization is an armed hunter stalking through the trees..."

2. The Wallfacer Project (面壁计划 Miànbì Jìhuà)

A strategy exploiting the Trisolaran weakness: they cannot deceive or hide their thoughts. Four "Wallfacers" are given unlimited resources and authority to devise secret plans. Their true intentions must remain hidden from Trisolaran sophons — and from all of humanity.

3. The Swordholder (执剑人 Zhíjiànrén)

The person who holds the switch for the Dark Forest deterrence — a threat to broadcast Trisolaris's location to the universe if they attack Earth. The first Swordholder is Luo Ji. The second is Cheng Xin. Their choice determines humanity's fate.

A Trisolaran probe made of strong-interaction material. Its surface is perfectly smooth — at the atomic level. It destroys the entire human space fleet in minutes. The most terrifying display of technological superiority in science fiction.

A proton (质子) that has been "unfolded" into multiple dimensions by Trisolaran technology and programmed with artificial intelligence. Sophons monitor human activities, sabotage scientific research, and communicate instantaneously between Trisolaris and Earth.

6. Dimensional Reduction / Planar Attack (降维打击 Jiàngwéi Dǎjí)

An attack that reduces a higher-dimensional space to a lower one. The most famous example is the dual-vector foil, which flattens 3D space into 2D — like being drawn into a painting, still alive but impossibly flat.

7. Dual Vector Foil (二向箔 Èr Xiàng Bó)

A weapon deployed by higher civilizations. It appears as a small, transparent sheet that, once activated, begins converting three-dimensional space into two-dimensional space at nearly the speed of light. The solar system's destruction by this weapon is one of the most haunting passages in all of literature.

8. Gravitational Wave Antenna (引力波天线 Yǐnlìbō Tiānxiàn)

A device that uses gravitational waves to transmit information across the universe at the speed of light. It's the mechanism behind the Dark Forest deterrence — Earth's threat to broadcast Trisolaris's coordinates to the cosmos.

A theoretical faster-than-light drive that works by contracting spacetime in front of a spaceship and expanding it behind. The ship essentially "surfs" on a wave of curved space. Yun Tianming's fairy tales secretly conveyed this technology to humanity.

10. Cosmic Sociology (宇宙社会学 Yǔzhòu Shèhuìxué)

A theoretical framework created by Ye Wenjie and developed by Luo Ji. Based on two axioms:

1. Survival is the first need of civilization

2. Civilization continuously grows and expands, but the total matter in the universe remains constant

| 叶文洁 | Ye Wenjie | The one who contacted Trisolaris |

| 罗辑 | Luo Ji | Wallfacer, First Swordholder |

| 章北海 | Zhang Beihai | The "Fifth Wallfacer" |

| 程心 | Cheng Xin | Second Swordholder |

| 云天明 | Yun Tianming | Human envoy to Trisolaris |

| 史强 | Shi Qiang | Detective, protector of Luo Ji |

| 汪淼 | Wang Miao | Nanomaterial researcher, Book 1 protagonist |

| QY (地球三体组织) | Earth Trisolaris Organization — humans who worship Trisolaris |

| PDC (行星防御理事会) | Planetary Defense Council — UN body for alien defense |

| Space Force (太空军) | Earth's space military force |

| Wallfacer Project (面壁计划) | Secret defense strategy against Trisolaris |

| Wallbreaker Project (破壁计划) | Trisolaran effort to uncover Wallfacer plans |

| Natural Selection (自然选择号) | Zhang Beihai's spaceship, which fled the solar system |

| Blue Space (蓝色空间号) | Another ship that escaped |

| Gravity (万有引力号) | The ship carrying the gravitational wave antenna |

| Bronze Age (青铜时代号) | Ship captured after the battle |

| Trisolaris Fleet (三体舰队) | The invasion force heading to Earth |

💡 Quick Reference: Most Confusing Terms for New Readers

- 4D fragments → bubbles of four-dimensional space

- 2D → the flattened state after dual-vector foil attack

- Collapsing dimensions → the universe losing dimensions over time

- Light speed → universal speed limit (300,000 km/s)

- Low light speed → slowed by curvature trails

- Black domain → region where light speed approaches zero

- Lightsail → ship powered by light pressure

This glossary works as your companion while reading. Bookmark this page and refer back whenever you encounter a term you don't recognize!