Liu Cixin’s Three Body series is a science fiction trilogy that offers a vision of optimistic determinism. I enjoyed the first two books, and thought to record some thoughts on the series as a whole, with spoilers kept to a minimum. As usual, my posts on books focus on the ideas I found most striking.

The most important idea: When I hear Peter Thiel saying that we can imagine the future with the help of science fiction, this is the kind of story I feel he means. The series emphasizes the importance of interiority and independent thinking. It presents a blueprint for how technology can advance, from building particle accelerators and fusion plants to colonizing the solar system and harvesting energy from different planets. It’s about how humans build new technologies, not how all scientific development culminates in dystopia. And like Thiel’s ideas, a layer of pessimism covers a radiantly optimistic core.

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The premise. Liu Cixin’s favorite science fiction authors are Arthur C. Clarke and Isaac Asimov. I’m not familiar with either, instead his books remind me of Neal Stephenson’s: Full of science and philosophical engagement, with exposition of stunning ideas, all wrapped up in a tasty plot.

Three Body is primarily about first contact with aliens. The premise is mundane,
the setting is not. A science fiction trilogy that starts out during the Cultural Revolution, imagine that.

Here’s a bit more as background: During the Cultural Revolution, the daughter of a persecuted physicist gets involved with the Chinese effort to contact extraterrestrials, before the Americans and Soviets get to it first. In a moment of despair, Ye Wenjie secretly broadcasts a message to the cosmos; magnified by the sun, it invites any listening extraterrestrials to take humanity to task on its various moral failings. The message reaches the Trisolarans, who inhabit a star system four light years away from Earth. They’re so named because their planet revolves around three suns, which orbit in an unstable configuration.

Trisolarans have evolved with the three sun problem for millennia. Eventually they figure out that they cannot predict the path of the three suns, and thus they risk being swallowed someday by a stray. Trisolaran technology is significantly more advanced than human technology, and they send a fleet to Earth after receiving Ye Wenjie’s signal. Four decades later, humanity discovers her communications, and determine that the Trisolaran fleet would reach the solar system in four centuries. The rest of the books deal with humanity’s response to the Trisolaran mobilization.

I like best the descriptions of these two reviewers. From Jason Heller of NPR: “While in the virtual world of Three Body, Wang confronts philosophical conundrums that border on the psychedelic, all while remaining scientifically rigorous.” And here’s Joshua Rothman of the New Yorker: “Liu Cixin’s writing evokes the thrill of exploration and the beauty of scale.” He likes the Chinese setting too. After remarking that sci-fi is often biased towards American themes of the war for independence and the Wild West, Rothman praises another of Liu’s stories: “I doubt that any Western sci-fi writer has so thoroughly explored the theme of filial piety.”

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Interiority. The three books prize interiority, to an almost sinister extent. Crucial plot points turn on deceptions, from people like Ye Wenjie and Zhang Beihai, who cultivate secrets and bear them in silence, with severe results for the rest of the world. The case is even more extreme with the Wallfacers, four people who are given extraordinary authority to develop defensive strategies that are meant to be hidden from the rest of humanity.

Incredibly, there’s a scene in the third book in which Earth’s greatest experts engage in esoteric analysis of a literary work, with debate afterwards on the work’s intended message. I myself am not a Straussian, and it makes me wonder if Liu is. Liu reminds people that “vagueness and ambiguity are at the heart of literary expression.” The work the experts analyze contains odd allusions and small inconsistencies, and Liu states that “real intelligent information must be hidden deep.” In a later scene, Liu castigates the uncritical reader: “Previous efforts at decipherment had failed largely due to people’s habitual belief that the stories involved only a single layer of metaphors to hide the real message.” Instead, the good reader must realize that truth might hide beneath multiple layers of metaphors.

People aren’t so susceptible to herd-thinking in Liu’s world. How are bubbles created? By the lack of independent thinking combined with the belief that majorities are generally right. In the Three Body world, key characters work through problems on their own. We see in scene after scene that the private ruminations of people lead them to determine the correct courses of action, without consulting public opinion first.

Liu focuses a great deal on the interior thoughts of the main characters. Everyone else is out of focus. His world is one in which countries largely cooperate with each other, letting go of most national pride to work together. At times it seems like the entire government apparatus is set up to serve our heroes. This efficient cooperation of government bureaucrats, all of whom are meritorious and think beyond themselves, is to me the most alien part of Liu’s world. Three Body could use some discussions of public choice.

A last thought about interiority: The governments of Three Body are comfortable with vesting enormous powers in people who aren’t thoroughly vetted first. This pathology is most evident in the Wallfacer project and the Swordholder position, although it seems to affect many levels of elite selection. Placing trust in intelligent people is a lovely idea, but I feel that this is becoming less and less plausible of a practice in our world. Given all the records that people can surface, I wonder if it’s possible for anyone to escape severe vetting. I submit that in a few years, anyone who has a Twitter profile or a blog will not be able to survive Congressional confirmation, let alone be elected to high office. And I wonder to what extent the quality of government elites get worse (if at all), when we select for people who are willing to be really boring in their 20s.

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Definite optimism. The books are very nearly a blueprint for how to build the future. Humanity has four centuries to deal with the arrival of the Trisolaran Fleet. In the meantime, scientists and governments work together to advance science to deal with the threat. They work on fusion, allowing humanity to obtain much cheaper sources of energy. They mine resources from asteroids and other planets. They move away from chemical-based rockets, and instead develop rockets based on radiation drives that use nuclear fusion. Their advances in software and hardware make cities are nicer places to live. They re-forestize the deserts. They colonize the rest of the solar system and they perfect creating enclosed cities on moons and planets. They develop engines powered by curvature propulsion (I do not know what this is) so that humanity can fly at the speed of light. My favorite part: They test out a version of the Orion Project—sending an object through space by exploding small hydrogen bombs behind it.

I always had the same question when I read about these technologies: Why should it take the threat of an alien invasion for humanity to develop them? I’m not advocating for curvature propulsion and fusion-based rockets. The point isn’t that Liu has identified the correct means on all the scientific questions; instead I admire the goals. It shouldn’t take an alien threat to push us towards cheap energy and solar system exploration.

I quite identify with the themes of The Great Stagnation, and the idea that we’ve had lots of progress in the world of bits but not so much in the world of atoms. And I wonder if Liu Cixin’s imagination is a result of personally witnessing rapid economic growth and regular scientific milestones. Arthur C. Clarke was born in 1917, and Isaac Asimov was born in 1920. When they were young, they witnessed the development of the Manhattan Project and experienced postwar prosperity. 24 years after the Trinity Test, they saw the Apollo Project deliver three men to the moon.

Liu Cixin was born in 1963; liberal reforms began in 1979, and especially in the last decade, Liu has been heavily exposed to domestic scientific milestones. These include China’s space projects (Tiangong, Long March, Shenzhou), deep sea exploration (the Jiaolong submersible), better telescopes (Tianyan), and gleaming new bridges, trains, and cities. I’m not saying that other space programs have done nothing, instead that they don’t get as much domestic publicity as China’s media is able to muster. Liu has been compared to Clarke and Asimov in writing “classical” science fiction; I wonder if these authors all focused on writing about technological advances, instead of dystopian societies, because they all witnessed rapid progress. If so, let’s hope that more people in developing countries get into writing science fiction, and not leave it all to comfortable authors in rich countries, most of whom can imagine nothing other than dystopia.

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The three books. I did not enjoy all three books equally. The first, Three Body Problem, is excellent. The second, The Dark Forest, is very good. The third, Death’s End, is too dismal for words. If you pick up the series, I suggest stopping by the end of the second book, which like the first is full of vibrant ideas. The trilogy could have wrapped up on a smart and philosophical note; instead, the ending felt hollow and Hollywood.

The second book is still good, but for me it never reached the quality of the first. The Dark Forest is a perfectly fine science fiction book, and it presents a compelling answer to the Fermi Paradox. My complaint with it is that it loses the distinctly Chinese flavor of the first book. The Three Body Problem is philosophical and historical. In one scene, Ye Wenjie visits her mother, whose denunciation of her father led to his death by beating; in another scene, she confronts the three students who actually led the beating. The first book doesn’t even have all that much science fiction in it, while the rest have all that you want and more. The science is great, but I liked better the parts that engage historically.

Every Chinese person I’ve talked to claims to have liked the first book better; every non-Chinese says the second is better. I miss the excellent footnotes Ken Liu prepared for the first book; there were fewer opportunities for them in the next two.

Another part of the first book I really liked: Liu explicitly discusses the ideas of von Neumann, Newton, Aristotle, Mozi, Copernicus, and more. There were fewer of these historical/philosophical discussions in the others.

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Anti-intellectualism. Da Shi, the street-smart cop, is regularly proved right in his derision of intellectuals. Wang Miao first states that: “You know that a person’s ability to discern the truth is directly proportional to his knowledge.” But later on he admits: “Many of the best scientists can be fooled by pseudoscience, and sometimes devote their lives to it. But pseudoscience is afraid of one particular type of people: stage magicians. In fact, many pseudoscientific hoaxes were exposed by stage magicians. Compared to the bookworms of the scientific world, your experience as a cop makes you far more likely to perceive such a large-scale conspiracy.”

It’s true that intellectuals deliver the scientific advances. But the intellectuals are responsible for causing all of humanity’s problems in the first place.

At one point, the world’s experts doubt that the character Yun Tianming could possibly craft a scientifically-rigorous literary work, because “after all, he only had an undergraduate degree.” I couldn’t help but feel that Liu Cixin, a software engineer at a power plant who didn’t study beyond undergrad, felt some bitter satisfaction at writing these words.

One last note on this topic: Throughout the trilogy, and especially in the first book, people discuss the merits of theory versus experimentation. Both sides had good arguments, and I didn’t follow which came out ahead. On the one hand, humanity kept lamenting a technological block that Trisolaris placed on Earth, stopping humanity from advancing on fundamental theory. On the other hand, many of the great advancements were driven by experiment-oriented people. If I re-read the books, this will be a theme I’ll focus more on.

Ye Wenjie recalled her father saying, “I’m not opposed to your idea. But we are, after all, the department of theoretical physics. Why do you want to avoid theory?”

Yang replied, “I want to devote myself to the times, to make some real-world contributions.”

Her father said, “Theory is the foundation of application. Isn’t discovering fundamental laws the biggest contribution to our time?”

Yang hesitated and finally revealed his real concern: “It’s easy to make ideological mistakes in theory.”

Her father had nothing to say to that.

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The writing. A few of my friends have complained that the book’s writing isn’t very good. Ken Liu, translator of the first and third books, offers this thought: “The best translations into English do not, in fact, read as if they were originally written in English. The English words are arranged in such a way that the reader sees a glimpse of another culture’s patterns of thinking, hears an echo of another language’s rhythms and cadences, and feels a tremor of another people’s gestures and movements.”

Some of the rhythms do feel odd. But I was able to perfectly picture some of these sentences in Chinese, and I want to assure my friends that the conciseness works better in the original language. For example, when describing a bath, I don’t regret that Liu wrote: “She felt her body turn as soft as noodles.” It adds a different flavor to the books.

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Politically incorrect. Some parts of the books felt quite politically incorrect, I’ll discuss just two. First, Robin Hanson picks up on the strain of misogyny that’s especially evident in the third book. I was surprised at how often Liu described the human world as too “feminized,” and how men from only previous eras could be described as “tough.” At one point, a frustrated commander cries out: “Don’t you know that there are no more men on Earth?”

Hanson suggests that Liu is able to get away with this because he’s Chinese. I want to add another point. Liu portrays the other alien civilizations, which are all more advanced than Earth, as totalitarian societies. His implicit suggestion is that they’ve traded in personal freedoms for technological advancement and cosmic survival. Trisolarans live in a totalitarian caste system; another, still more advanced aliens lack even the ability to keep their own thoughts private. I haven’t seen anyone else call Liu out on this point.

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A few last thoughts:

I’ll return to the idea that this is the kind of science fiction that I think Peter Thiel wants people to read. A big theme is that it takes work build the future, that it’s possible, and that government has a role to play.

To conclude, here’s a scene I enjoyed from the first book, which beautifully describes the three body problem. In interviews, Liu has suggested that he’s able to turn visualize concepts into formulas, presumably this describes how he sees it himself.

I created a sphere in this infinite space for myself: not too big, though possessing mass. My mental state didn’t improve, however. The sphere floated in the middle of “emptiness”—in infinite space, anywhere could be the middle. The universe had nothing that could act on it, and it could act on nothing. It hung there, never moving, never changing, like a perfect interpretation for death.

I created a second sphere whose mass was equal to the first one’s. Both had perfectly reflective surfaces. They reflected each other’s images, displaying the only existence in the universe other than itself. But the situation didn’t improve much. If the spheres had no initial movement—that is, if I didn’t push them at first—they would be quickly pulled together by their own gravitational attraction. Then the two spheres would stay together and hang there without moving, a symbol for death. If they did have initial movement and didn’t collide, then they would revolve around each other under the influence of gravity. No matter what the initial conditions, the revolutions would eventually stabilize and become unchanging: the dance of death.

I then introduced a third sphere, and to my astonishment, the situation changed completely. Like I said, any geometric figure turns into numbers in the depths of my mind. The sphereless, one-sphere, and two-sphere universes all showed up as a single equation or a few equations, like a few lonesome leaves in late fall. But this third sphere gave “emptiness” life. The three spheres, given initial movements, went through complex, seemingly never-repeating movements. The descriptive equations rained down in a thunderstorm without end.