Liu Cixin's "Three Body Problem" Series

Imagining Technological Impacts on Societies via Science-Fiction

Jul 15, 2023

This Spring I read the Remembrance of Earth’s Past trilogy aka The Three Body Problem trilogy or as it is frequently referred to online, Three Body. The series was created by an author living in China named Liu Cixin, who developed the series while working as a computer engineer at the Niangziguan Power Plant in Yangquan, Shanxi. Three Body’s English translations have gone on to win or be nominated for numerous science-fiction book awards like the Hugo, Nebula, and Arthur C. Clarke awards.

I think it is important to read fiction from other places than one is familiar, in particular sci-fi or speculative fiction, because of the insight it offers and adds to the imaginative capacity for the future. Even, or especially so, in darker tomes like Three Body. One way I describe the premise of the book is to take Carl Sagan’s exploration of societal changes stemming from radio astronomers picking up a message from outer space in Contact, and combine it with the deep-time concepts and existential dread of Adrian Tchaikovsky’s Children of Time (though without the highly evolved spiders).

The books in order of release:

The Three Body Problem 三体 2006, translated by Ken Liu 2014 (400 pages)
The Dark Forest 黑暗森林 2008, translated by Joel Martinsen 2015 (513 pages)
Death’s End 死神永生 2010, translated by Ken Liu 2016 (605 pages)

I became aware of Three Body from online forums that frequently referenced Cixin’s work. Usually the reference was not to Three Body, but to the second title in the series The Dark Forest. The title of the second book doubles as the name for a potential solution to the Fermi paradox. The content creators at Kurzesagt created a series of short educational animated episodes on the Fermi paradox. I highly recommend watching their ten-minute animated video below covering the dark forest hypothesis if unfamiliar with either the Fermi paradox or dark forest hypothesis.

First Contact with E.T. Sets the Stage

In Carl Sagan’s Contact, the main character is Ellie Arroway, and after the loss of her father at an early age, she becomes a professional astronomer and picks up a message from space. Arroway’s research team confirms the signal and then reports it up the chain-of-command all the way to the President of the United States (‘played’ in the movie version by then-President Bill Clinton). Contact portrayed a textbook approach to first communication from beyond the solar system. Three Body by comparison, suggests the Contact perspective may be a product of a more optimistic era. Three Body takes a different approach as to how a message is received, how it is responded to, and how it is broadly made known to the world.

In Three Body, a woman named Ye Wenjie is the first to receive a message from outside the solar system. Like Contact’s Ellie Arroway, Ye’s father also died tragically when she was young. However, Ye Wenjie’s father died in front of her eyes because he was a physics professor beaten to death by a group of Red Guard students during the Chinese Cultural Revolution. Ye nonetheless strives to become an astrophysicist, but she is branded as an ideological subversive due to family ties and sent off to a labor camp in China’s hinterland. She ends up reading a book, Rachel Carson’s environmental classic Silent Spring, which later gets her imprisoned when the text is classified as counter-revolutionary. However, her skill set as an astrophysicist (still a rarity when compared to the general population) allows her to be recruited to work at a nearby military research facility with an aim to disrupt satellites using radio waves.

While no one else is around in the facility, Ye Wenjie gets into the radio control room and discovers a way to use the sun to boost a radio signal so that it maintains signal integrity for distances of light-years rather than decaying into cosmic background noise shortly after leaving the solar system like it normally does. She is unaware that she has succeeded until a response is received years later.

The communication received from space is a warning. The sender describes the harsh environmental conditions of their planet, Trisolaris, and go on to say in essence do not send a second transmission this direction because an alien invasion fleet will show up at Earth. She realizes that would likely be the end of humanity as we know it, which given how humanity has treated her so far does not seem like much of a concern, and so she sends a second transmission to give away Earth’s position. With the clock ticking, Ye Wenjie keeps this act secret.

The extraterrestrials Ye Wenjie contacted are called Trisolarans, named after the triple star system their planet attempts to survive. Due to the chaotic orbits of the three stars (a literal description of the classical Three Body Problem) the Trisolaran home-world is plunged into alternating eras of stability and near extinction. Trisolaran biology is such that they are able to go into a state of suspended animation at will by dehydrating themselves to survive “chaotic eras.” Trisolarans long for a more stable solar system to anchor their civilization, and therefore launch their fleet towards Earth.

Eventually, the interstellar communications are discovered by the rest of the world and planet Earth braces itself for a Trisolaran fleet set to arrive in about four hundred years. Whether humanity can develop a sufficient response in four centuries — and not fall apart — sets up focal points for the remainder of the series. The reader tags along with primary characters that wake up from stasis pods and catch glimpses of the Earth as it adapts from its own cycles of stable and chaotic eras.

Technology: Quantum Entangled Smart-Protons, Strong Force Material, and Living Underground.

While there are multiple eras in the timeline of Three Body that use technologies with a functional impact on the story — such as human hibernation, space elevators utilizing nanotech cables, and nuclear fusion engines for human spacecraft — those are well-tread technologies in science fiction. The three I picked below to expand on are a bit more unique to Three Body:

Sophons (and the Wallfacer response)
Droplets (a Trisolaran probe that looks like a metal raindrop)
Humans living underground as prelude to living in space habitats.

Sophons v Wallfacers v Wallbreakers

In Three Body, the universe has 11 dimensions according to a version of string theory called M-Theory. Trisolarans create a sophon by taking a proton and pulling surface area out from higher dimensional space so that they can etch transistors onto them. The sophons are made to be supercomputers that can move between those dimensions and become super small, or big, as needed. Regardless of apparent size, a sophon’s actual mass does not increase beyond that of being an itty-bitty proton. The sophon’s small mass allows it to be accelerated to near the speed of light and arrive at Earth centuries ahead of the Trisolaran fleet.

Regarding conceptualizing the oddness of what an object that moves into higher dimensional space looks like, I highly recommend this demonstration video of 4D toys:

The Trisolaran’s make multiple sophons and keep some on Trisolaris that are quantum entangled with the sophons sent to earth. This allows for instant communication between the sophons regardless of distance.

The sophons perform two primary functions for the Trisolarans: one is near-perfect surveillance of Earth, the second is to infiltrate human particle colliders and bump into the particles under observation and interfere with the results. By tampering with the particle collider results the sophons lockdown human advancement and understanding in physics. The next four hundred years of human technological efforts are confined to extrapolations from the realm of scientific understanding as we know it today.

Knowing that Earth is under surveillance, and that most Earth technology can be hacked or infiltrated, the governments of Earth decide to start the Wallfacer program. The program name comes from a meditation technique of facing a blank wall. The only space that the sophons cannot surveil are the thoughts in peoples minds. Four people are selected to be wallfacers, a former U.S. Secretary of Defense, a neuroscientist, an out-of-the-box revolutionary/demagogue, and an obscure Chinese professor of sociology. That last Wallfacer is a central character named Luo Ji, and the only reason he was selected is that he was the target of an assassination attempt directed by Trisolaris for reasons unknown. The wallfacers are given extraordinary control of resources to carry out any plan they might have without question because a seemingly ridiculous request could be part of a plan, or a ruse.

As Dr. Wendy Whitman Cobb of Air University wrote in a 2021 piece for Strategic Studies Quarterly called Sophons, Wallfacers, Swordholders, and the Cosmic Safety Notice: Strategic Thought in Chinese Science Fiction:

The wallfacer strategy encompasses a number of advantages. For one, it retains the element of surprise. And even if a wallfacer does discuss a particular strategy, there is no way to know whether that strategy is the true one—disclosing a strategy might be a feint in one direction preserving freedom of maneuver in another.

Some humans have opted to take sides with the Trisolarans and are members of the secretive Earth-Trisolaris Organization (ETO). Some of the ETO members work with the sophons to try and crack the plans of the wallfacers, and they are called wallbreakers. I found it entertaining to speculate as to what a wallfacer’s plan might truly be given their actions. Then for some plans to be dramatically revealed in detail by a wallbreaker (with the plan often creating public outrage) is a good way to let the reader play along with events in the story.

Droplet, the little probe that could.

In middle school, we learned about the four fundamental forces in the universe: electromagnetism, gravity, weak force, and strong force. Electromagnetism and gravity get a lot of play in media, and the weak force (radioactive decay) gets publicity in nuclear fission, fusion, and even has a theory to unify it with electromagnetism called electroweak force. What about the strong force, that nuclear force that binds an atom together and literally keeps us all from not matter-ing at all? Three Body has got you covered when it comes to exploring the strong force with the droplet.

Another Trisolaran technological marvel that I still think about, its name derives from having a raindrop shape and being completely reflective. Like the sophons, the droplets arrive in Earth’s solar system before the main Trisolaran fleet. However, unlike the sophons, a droplet is minivan sized, so instead of arriving four centuries ahead of the fleet like the sophons a droplet arrives about two centuries ahead of the fleet.

When the droplet comes into Earth’s solar system, the humans think it may be some kind of gift, as it appears inert and without a visible means of propulsion (it turns out to be a plasma halo at the tail that was turned off). They are able to get close to it and discover that the outer layer at an atomic level has been so perfectly arranged using the strong force that it created a frictionless surface with the hardness of a neutron star.

Cixin has stated in interviews that he is influenced by authors like Arthur C. Clarke, and the droplet felt very Clarkean. The design of the droplet sounds so mathematically precise that it becomes uncanny. Cixin even goes so far as to have the characters make references to Clarke, for example on page 415 of The Dark Forest:

2001: A Space Odyssey, Arthur C. Clarke had described a black monolith left on the moon by an advanced alien civilization. Surveyors had measured its dimensions with ordinary rulers and had found a ratio of one to four to nine. When these were rechecked using the most high-precision measurement technology on Earth, the ratio remained an exact one to four to nine, with no error at all. Clarke described it as a “passive yet almost arrogant display of geometrical perfection.”

A near-perfectly shaped metallic droplet with a near-indestructible shell may not sound very imposing, but such a thing is a terrifyingly simple alternative to big guns, lasers, and missiles.

Better Living Underground

This book really sold the intellectual appeal of underground building for me. The Earth’s surface is a dangerous place. Not only is there wind, rain, and all the other atmospheric elements, but things can fall down onto it. In Three Body, Earth’s governments come into alignment regarding putting an enormous amount of resources into advancing human presence in space. However, this creates an industrial pressure that causes ecological catastrophe across Earth’s surface.

Cixin’s descriptions of underground future cities are not ones that sound like an office building with no windows or a concrete bunker. These cities are enormous. There are massive support pillars that allow people to go to-and-from the surface, and from those pillars extend branches that have housing of almost every conceivable type hanging off of them. With an artificial sun illuminating the interior, the descriptions sound more luxurious than simply being in a vault. I also find part of the appeal in Cixin’s descriptions to be the oddly organic tree-like structure in the underground cities that I imagine when reading. Granted, it would look precarious to us to see a 3000 squarefoot house hanging off a branch, but it is likely secured by wire capable of cutting a ship in half like a cheese slicer.

There is a movement of human habitat that takes place in the series from people living on the surface, to living underground, to living in enormous space habitats around Jupiter — with some habitats having access to gravity and others not. Meanwhile, the entire surface of the Earth eventually becomes viewed as something like a nature preserve or national park.

Humanity’s Lack of Commitment to Humanity

The first book, The Three Body Problem, covers the time period from the cultural revolution to when the signal is secretly sent to the communication’s discovery by the world at large. The second and third books, Dark Forest and Death’s End, track the time period from the end of the first book through the centuries of preparing for physical contact and its aftermath. The books are also about what happens to human societies as they grapple with these circumstances.

One apparent theme in Three Body is that the worse circumstances get, the more accepting humans are of authoritarian and/or totalitarian forms of rule. Humanity is depicted as having gone through cylces of feast and famine wherein human rights, democracy, and environmental concerns are described by characters as being luxuries for the fat times. Due to main characters persisting throughout the timespan of the series by entering into states of suspended animation, they interact with characters of different eras and explore the contrast between the eras.

As Jiayang Fan, staff writer at The New Yorker describes in her piece on Cixin and Three Body:

Although physics furnishes the novels’ premises, it is politics that drives the plots. At every turn, the characters are forced to make brutal calculations in which moral absolutism is pitted against the greater good. In their pursuit of survival, men and women employ Machiavellian game theory and adopt a bleak consequentialism. In Liu’s fictional universe, idealism is fatal and kindness an exorbitant luxury. As one general says in the trilogy, “In a time of war, we can’t afford to be too scrupulous.” Indeed, it is usually when people do not play by the rules of Realpolitik that the most lives are lost.

I think many people would recognize there is a difference between passing laws that may be oppressive in some way, but can be argued as necessary due to an emergency circumstance — and just collectively deciding to become cattle adjacent by giving dictators absolute power. It is a questionable premise that chances for survival would improve with less accountability. During the American Civil War elections were still held in 1864, and President Lincoln won reelection with 55% to 45% of the popular vote. Cultural aspects to human organization can go beyond mere survival, and I think of them as being a bit more functional or morally ambivalent than Cixin portrays.

Some of the morality-or-survival plays that occur in the series I felt were forced at times, and in particular made the character Cheng Xin frustrating. This juxtaposition brought about by the main characters waking up in new eras even carries over to gender expression themes. Characters emerge from stasis and cannot tell men apart from women because the average man’s appearance is much more feminine (taller/lankier and facial structure/presentation). This reminds me of anxieties that the Chinese Communist Party has had regarding masculinity. A fear of the K-pop/boy-bandification of males that robs them of the physical and mental fortitude to do ‘what must be done,’ or something. It also read to me as a bit of a commentary (maybe even critique) of the impact on human evolution due to female mate selection.

The history of sci-fi under the CCP’s China is interesting as well. To again quote Jiayang Fan’s New Yorker article:

When the Communists came to power, science fiction presented itself as a handy way of furthering Mao’s “Campaign of Marching Toward Science and Technology.” Sci-fi would stimulate the interest of children and adolescents, and encourage them to contribute to the country’s modernization. But during the Cultural Revolution the genre was banned, along with other nonrevolutionary literature, and even science itself was subjected to ideological-purity tests. In astronomy, discussion of sunspots was forbidden, because the literal meaning of the Chinese term is “solar black spots,” and black was the color associated with counter-revolutionaries.
Science fiction made a resurgence in the early years of Deng Xiaoping’s reformist regime, when Liu was writing at night while maintaining his engineering day job. It was scrutinized more closely again in the years immediately after the Tiananmen protests, when he was beginning work on “Supernova Era.” The genre has now been steadily thriving for a couple of decades, but it’s not inconceivable that the political winds could change again, as Xi Jinping’s government seeks to establish increasingly rigid cultural control. Speculative fiction is the art of imagining alternative worlds, and the same political establishment that permits it to be used as propaganda for the existing regime is also likely to recognize its capacity to interrogate the legitimacy of the status quo.

It sounds like Cixin has a balance to maintain, but from what I have seen of his public comments regarding the CCP’s more controversial activities, I don’t think he’s going to be agitating against it any time soon.

Cixin has stated that George Orwell (author of 1984 and Animal Farm) was influential to him as a writer. Similar to Orwell’s 1984, Three Body’s Earth is often conceptualized as a tripolar world order. Whereas 1984 features the superstates of Oceania, Eurasia, and East Asia, Three Body suggests similar geographic spheres of power with the Earth’s space fleet terrestrially represented by North America, Europe, and Asia. Unlike 1984 where the tripolar order is in a state of perpetual war, Three Body showcases tripolar cooperation with the fate of humanity resting in the hands of its committees.

Final Thoughts on Three Body Series and DFH

Having read many of the famous authors Cixin cites as influences, I put him right up there with them in the category of hard science-fiction that I thoroughly enjoyed.

An area that I would have liked to have read more about were the cults referenced and the shadowy Earth-Trisolaris Organization that sprung up once the world learned about Trisolaris. Misanthropy was given as a prevailing reason, but I was curious to see how weird it might have been getting on within those movements and how those sentiments might have changed over the centuries.

As I discovered reading interviews, that sort of character exploration is not really Liu Cixin’s thing:

Types are central to the way Liu thinks of people; he has a knack for quickly sketching the various classes that make up Chinese society. A scientist is described as “nothing more than a typical intellectual of the period: cautious, timid, seeking only to protect himself.” Another character, “a typical political cadre of the time,” had “an extremely keen sense for politics and saw everything through an ideological lens.” This characteristic endows his fiction with a sociopolitical specificity that has the texture of reality. At the same time, it doesn’t allow for much emotional complexity, and Liu has been criticized for peopling his books with characters who seem like cardboard cutouts installed in magnificent dioramas. Liu readily admits to the charge. “I did not begin writing for love of literature,” he told me. “I did so for love of science.” [From Jiayang Fan New Yorker article]

The big idea discussed by characters in the book and basis for the dark forest hypothesis is the term “cosmic sociology.” Take one part ever-expanding space faring civilizations plus limited resources in the universe and there will be danger about. Is it pessimistic? Yes, and it makes for two types of advanced civilizations in the universe: those that can hide and those that are dead.

Do I think that the Dark Forest hypothesis is the most likely solution to the so-called Fermi paradox? No. I think if there is a solution (or paradox at all) it may be the zoo hypothesis. My main reservations with the Dark Forest hypothesis as a Fermi paradox solution are as follows:

By the time a civilization advances technologically to develop relativistic kill vehicles (example: big rock accelerated to near light-speed) and can annihilate a planet or a star, then it has likely gotten so far beyond simply ‘surviving’ that imagining what could threaten the survival of such a species boggles the mind. Able to set-up shop in a third of the galaxy, but still can’t crack overconsumption and overpopulation? Is ‘advanced’ the right word to use for such a civilization?
By the time a civilization spreads out enough to have wide areas of interstellar space under its control, it may become questionable what is even meant by civilization or culture, because the vast interstellar distances with little pockets of planetary space foster divergence. If a civilization can keep an empire like that together then why would it not just absorb/annex systems of comparatively less technologically developed civilizations?
What is a civilization anyway? Culture is a concept that people carry around in their heads. Culture is not physically real apart from the artifacts people create. In Earth history, while many civilizations have tales of conquest and devastation, on the whole it is also a lot of trading and mingling with blurred lines along frontiers.
Novelty can be extremely valuable. As far as I know, the solar system around Earth is mostly dead rocky planets, moons, and gas giants. If it is quiet like that in most other places, then life is an extreme rarity. One of the reasons not to slash-and-burn jungle rainforest is not due to ‘morality,’ but that there may be plants and animals yet to be discovered that have exponential impacts on things like chemistry, biology, and medicine. Simply put, if such a place might help such an ‘advanced’ civilization then what’s the point of going to the effort of destroying it?

That being said, I think it is an interesting thought experiment. The universe is a tremendously big place, and those probabilities warrant some caution. One response to #4 might be that it ignores preemptive strikes inherent in the Dark Forest hypothesis, but I don’t know that I completely buy that because it prioritizes a hazy notion of security (again, for what exactly, the ‘civilization’?) over not wasting resources like a planet or an entire solar system.

Write to me and tell me what you think, would especially like to hear from those of you that have read the books! [email to gpress@substack.com]

There has been a series production adaptation in China from Tencent, and Netflix is also bringing a series — and recently released the trailer below (even features a Carl Sagan voiceover lol):