Liu Cixin wrote The Three-Body Problem the patient way, spending far more time thinking than typing. The core concept arrived from a physics paper, and once that idea locked into place the actual draft moved quickly.

The Direct Answer
He built the whole novel around a single physics idea, then drafted fast once the concept held together.
Liu has said the seed was the classical three-body problem reframed as three suns, and that most of his roughly four years on the trilogy went into thinking rather than writing (China Daily, 2015).

The Idea Came First

The story started with a real problem in physics. The three-body problem describes how three objects moving under mutual gravity trace paths that resist any clean, long-term prediction. A small change at the start sends the whole system somewhere unexpected. Liu read a paper on it and, instead of seeing an equation, he saw a setting. He flipped the abstract bodies into stars.

I read the paper and suddenly thought: what if the three bodies were three suns?

Liu Cixin, Nature Future Conditional Q&A, 2016

From that single question the rest of the book grew outward. A world orbiting three unstable suns would swing between scorching heat and killing cold with no reliable pattern, so any civilization there would rise and collapse over and over. Liu then paired that alien predicament with a very human one. He set part of the story during China's Cultural Revolution because he wanted a character who had genuinely lost faith in humanity, and he felt that period could produce such a person honestly rather than for effect.

Years of Thinking, Months of Writing

The trilogy, published in Chinese under the umbrella title Remembrance of Earth's Past, took him roughly four years to complete. Most of that stretch went into working out the concept and the structure, not into drafting. In a 2015 interview he described the balance plainly: once he actually sat down to write, each book came together in only two or three months. The slow part was everything that happened before the first sentence.

He did all of this while holding down a full-time engineering job. The Three-Body Problem first appeared in 2006, serialized in the Chinese magazine Science Fiction World, and Ken Liu's English translation arrived in 2014 and won the Hugo Award for Best Novel in 2015. To see how he fit a project this size around his shifts, read the full Liu Cixin writing routine.

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