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Literature / The Three-Body Problem

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Engage in physics at your own risk.

"There's a strange contradiction revealed by the naivete and kindness demonstrated by humanity when faced with the universe: On Earth, humankind can step onto another continent, and without a thought, destroy the kindred civilizations found there through warfare and disease. But when they gaze up at the stars, they turn sentimental and believe that if extraterrestrial intelligences exist, they must be civilizations bound by universal, noble, moral constraints, as if cherishing and loving different forms of life are parts of a self-evident universal code of conduct."
Liu Cixin

The Three-Body Problem (三体) is a science fiction novel by Chinese author Liu Cixin. First serialized in 2006, it was published as a novel in 2008, and quickly became one of the most popular science fiction novels in China. An English translation by Ken Liu was published in 2014 and also became a breakout success, garnering a Nebula nomination in 2014 and winning the 2015 Best Novel Hugo. There are two sequels, The Dark Forest (黑暗森林) and Death's End (死神永生). Collectively, they are known as the Remembrance of Earth's Past (地球往事) trilogy, though readers usually refer to the entire trilogy with the name of the first book. The second book has been translated and published in 2015, and the third translation has been published in 2016.

A fourth book, The Redemption of Time (观想之宙), was published in 2011 and translated in 2019. Not written by Liu Cixin, it originated as an ambitious and hugely popular fanfiction that received the Approval of God, and is officially semi-canonical — readers may consider it the "true" conclusion to the trilogy or disregard it according to their preferences, as it radically reframes the themes of the trilogy to allow for a more hopeful ending.


In modern day China, Wang Miao is facing a problem: all the foremost physicists in his speciality, nanomaterials, are committing suicide, leaving behind extremely cryptic suicide notes. He's assigned to join a mysterious secret society that may have some answers, but keeps getting distracted by a revolutionary new MMORPG called "Three Body"... and also by the mysterious numbers that appear only in his vision, counting down to a date about fifty days away.

Many years into the past, Ye Wenjie is having a problem: though a brilliant physicist, she was branded a political dissident back during the Cultural Revolution, and was exiled to a lonely military station called Red Coast. However, Red Coast harbors goals far beyond the scopes of the earth, and Ye's personal struggles will have lasting impacts on the fate of the whole world...


A film adaptation of the first book is stuck in Development Hell. An animated TV adaptation is being developed by Chinese entertainment company Yoo Zoo Entertainment. A webtoon adaptation is in progress and the English translation may be found here. In 2020, a live-action TV adaptation is being developed by Netflix, with David Benioff & D.B. Weiss (Game of Thrones) and Alexander Woo (The Terror: Infamy) as showrunners.

See also Ball Lightning, a pseudo-prequel to the series also written by Liu Cixin.


  • Absolute Xenophobe: Every single race in the entire universe. Under the Dark Forest theory, every single race in the universe is ultimately hostile to the existence of any other alien race, and actively works towards the complete destruction of other races. While lesser races engage in galactic wars, advanced god-like races are committing mass genocide on a universal scale by ruthlessly attacking any location suspected of harboring sentient races with incomprehensibly powerful weapons.
  • Abusive Precursors: Ancient aliens have used weapons which, among other things, have lowered the speed of light universally and reduced the universe from 10 to 3 dimensions. They continue to do so.
  • Adaptation Expansion: The webtoon adds a considerable amount of material focusing on Shi Qiang, in particular a story arc where he and his team follow Pan Han to Italy.
  • Aliens Are Bastards:
    • The Trisolarans' history bred everything out of their culture except the desperate need to survive at all costs... though there seem to be individual exceptions. By the third book, they have mastered human deception by feeding humans false science to hamper humanity's technological boom, embracing their culture only to deceive and enslave them later, and refusing to give them the means to escape a dark forest strike.
    • It's not just the Trisolarans. In the third book it's revealed that casual annihilation of any intelligent race that is discovered is entirely routine; they don't care about the damage their weapons do to the fabric of reality; and the universe is effectively a war ruin as a result of billions of years of conflict and the damage wrought by those weapons. The grand unifying universal sociology theory is built upon this rule.
    • It's not all bad. The last chapters of the third book hint at the existence of a greater galactic society, with interstellar trade, alliance, and information exchange all possible. The dark forest theorem is still extremely in effect, however, and it's considered very rude to ask someone where their homeworld is.
  • Alien Invasion: Already launched, and due in about 450 years. They have mastered lightspeed travel in the third book and can reach Earth in a few years, but invasion is narrowly averted by the dark forest broadcast.
  • Ambiguous Disorder: Yang Dong's strange detached look and hyper-rational behavior is something that made her attractive in story, but also hard to approach. Considering the nigh-unintelligible, almost disturbing sketches she made on her childhood notebook, it's likely that she had some kind of savant syndrome or autism.
  • And You Thought It Was a Game: "Three Body" is a covert recruitment tool for the ETO.
  • Apocalypse How: The author wrote an article discussing apocalypses in the series and their absence in Chinese literature in general.
    • From the first book: The present Trisolaran civilisation is the latest in over two hundred, each of which was wiped out after a Planetary Extinction (minimum) caused by the planet's chaotic orbit. Special note goes to number 191, which is destroyed when the planet gets ripped apart by tidal forces after passing close to the suns; the smaller fragment eventually becomes a moon of the larger fragment, still holding visible ruins on its surface. Eleven other planets in the system have already fallen into the suns, and given time Trisolaris will fall in as well.
    • From the second book: The "Great Ravine" that occurred off-screen during the Crisis Era is a planetary Societal Disruption, with over half the Earth's population dying out over the course of half a century due to wars, famine and general lack of resources.
    • From the third book: The end of (most) life on earth is narrowly averted when the Trisolarans call off their invasion just in time for humanity not to have to eat itself, but Trisolaris is destroyed shortly afterwards. Then later played straight on a 'Total Extinction' scale when the Solar System is converted to two dimensions. The universe itself is implied to be on the way to a universal, metaphysical annihilation if galactic warfare is allowed to continue.
  • Applied Phlebotinum: While most of the fictional science in the book is explored in great lengths, the "mathematical language" that allows the first contact between species is hand-waved.
  • Artistic License – Astronomy: The Alpha Centauri system, where Trisolaris is located, is portrayed as three stars orbiting each other in chaotic, unpredictable ways. In fact, it consists of a stable binary pair of stars orbited at a great distance by a red dwarf star.note 
  • Ascend to a Higher Plane of Existence: Inverted. Due to dimensional warfare, the universe will keep being reduced to lower dimensions. So higher civilizations must be able to project themselves to lower dimensions to survive.
  • Beneath Notice: In Shi's lecture to Luo Ji near the start of The Dark Forest, he identifies this as the foundation of real shrewdness. This becomes key to Luo Ji's ultimate plan at the end of the book, when he convinces everyone around him, including the Trisolarans, that he has no way to stop the invasion, and is only working on an ultimately meaningless project in order to escape reality.
  • Big Good: The Returners, who seek to ensure a Big Crunch that will recreate the universe in its original shape, undamaged by endless warfare. They broadcast a message in every possible language encouraging people to return mass from their pocket universes to the greater universe to avoid its mass going below some lower threshold that will prevent it from collapsing into a new singularity. Whether they succeed is left open.
  • Binary Suns: Trisolaris has three suns (hence the name) and orbits them in an unpredictable pattern: sometimes it's orbiting one particular star and has a stable climate (a Stable Era) and sometimes it's orbiting all three at once and has a wildly unstable climate (a Chaotic Era). The transition between one orbit and another can be traumatic due to the gravitational pull and proximity to the suns, and it's not unheard of for such transitions to completely destroy Trisolaran civilization in the process, leaving the survivors to rebuild.
  • Bizarre Alien Biology: Trisolarans only appear in one scene in the first book and are never given a complete description, but we know a handful of details: they can mummify themselves at will to enter a state of suspended animation, they communicate through flashes of light (and have no real barrier between thinking something and saying it), and reproduce by fusing together and then splitting into several new Trisolarans, which inherit some memories from their parents.
    • In The Redemption of Time, Yun Tianming becomes the first and only human to lay eyes on a Trisolaran. Their most salient feature is that they’re no larger than rice grains, which has had profound effects on their intelligence and psychology. The irony of them calling humanity “bugs” is the first thing Yun realizes.
  • Boring, but Practical: Photoids, projectiles used to carry out dark forest strikes. It's very destructive and also very cheap and boring because it's just a bullet thrown at near-lightspeed, which gives it enough power to tear apart a star. note 
  • But for Me, It Was Tuesday: Singer's role in the Solar System's destruction, reinforcing the hypothesis that most dark forest strikes are economical and mundane.
  • The Chessmaster: The Wallfacers are explicitly intended to be this. Only Luo Ji succeeds. Also Zhang Beihai who, along with his father, predicts the future development of human society under sophon lockdown and successfully executes a centuries long plot to ensure that at least some humans escape. Tianming presumably also qualifies given the steps he'd have had to take for his plan to work.
  • Cosmic Flaw: Near the end of Death's End, it's revealed that the early universe consisted of ten dimensions rather than three, and the speed of light was near-infinite. Unfortunately, over billions of years Sufficiently-Advanced Abusive Precursors have been using incomprehensibly-advanced weapons to create Negative Space Wedgies that are reducing the dimensionality of the universe, and the speed of light itself, to destroy their enemies. Eventually the universe will be reduced to two dimensions, and then one, and then... well...
  • Cosmic Horror Story: The book has strong parallels with the cosmic horror genre by putting humans in a universe where everyone is an enemy, and every enemy is magnitudes upon magnitudes more powerful than they could ever become.
  • Crapsack World:
    • Trisolaris, with its extremely unpredictable environment.
    • The second and third book reveal that the whole universe is also this. The Dark Forest theory says that every single race in the universe is or will be absolutely hostile to each other, due to the inability to establish trust, the fundamental desire for survival, and the limited resources in the universe. It is a necessity for every single race to enact genocide on every other alien race they encounter, or else they would risk genocide to themselves. Combine the Dark Forest theory, with the fact that Sufficiently Advanced Aliens are everywhere, and the only reason they haven't genocided humanity is because they don't know where the humans are, the entire universe is revealed to be an infinitely bleak one where hope for peaceful survival is impossible.
  • Curb-Stomp Battle: In order to make a statement, Earth deploys thousands of powerful warships to engage the first small Trisolaran probe which enters our Solar System. Unfortunately for Earth, the probe easily destroys the entire fleet in a matter of hours while taking no damage; the only Earth ships that survive were nowhere near there.
  • Cute and Psycho: Sophon by the third book, depending on the situation.
  • Death of a Thousand Cuts: Death's End reveals this is happening to the entire universe. With advanced technology, it's possible to lower the speed of light in a region of space called a black domain. One can also reduce the number of dimensions to exterminate everything within it while leaving the rest of the universe untouched. But what happens when you continuously repeat the process everywhere? Eventually these areas chain together to create a universal black domain and lower the universal speed of light. Likewise, it's possible to reduce the number of dimensions in the entire universe through repetition of dimensional warfare. This is how the universe was reduced to current three dimensions from its original ten and well on its way to only two, while the speed of light is reduced to its current speed from its original near-infinite. Eventually there will be one dimension, and then nothing at all.
  • Death World: Due to its chaotic orbit around three suns, Trisolaris is a nasty place. When it orbits any one sun, it goes into a Stable Era, during which conditions are actually pretty mild. However, the rest of the time it's being kicked around like a football during Chaotic Eras, where it alternates between broiling heat and freezing cold with absolutely no rhyme or reason at all. On particularly close or distant passes, temperatures may melt rock or drop to near absolute zero. Sometimes, the three suns align in a straight line with Trisolaris at one end, causing everything on the surface to literally fall into the nearest sun. Due to the eponymous three-body problem, all of this happens completely at random, and cannot be predicted at all. The only reason anything lives there at all is that native life adapted to dehydrate indefinitely and then come back when conditions got better.
  • Despair Event Horizon:
    • Ye Wenjie crosses it at the end of the first book after she finds out that far from being a morally-superior civilization who can save humanity from its own madness, the Trisolarans suffer from many of the same foibles that she hates in humanity and are in many ways even worse.
    • Tyler in book two after his Wallbreaker cracks his strategy and the pressure of being unable to save the world (along with the reality that no matter what he says and does, everyone will assume that it's part of his genius strategy) catches up to him. He ends up shooting himself.
    • In the third book it’s finally revealed just why so many physicists had been committing suicide in the first: They’d come to understand not only that the sophon lockdown had made further progress in fundamental theory impossible, but also that the ability of Sufficiently Advanced Aliens to casually interfere with their observations called the whole concept of immutable physical laws derivable by experiment and observation into question. As Ding Yi puts it “Do you think only sophons create illusions? Do you think the only illusions exist in the particle accelerator terminals?” This realisation undermines their belief in their profession so badly that it drives some of them to kill themselves.
  • The Dreaded:
    • Luo Ji is this to Trisolaris, for reasons absolutely nobody can fathom. It's because he's close to figuring out that the universe is a dark forest and that he can beat Trisolaris by threatening to Summon Bigger Fish.
    • Wade from the third book is even more so. The Trisolarans calculated that Luo Ji had roughly a 91-98% chance (depending on the situation) of transmitting a dark forest broadcast against Trisolaris if deterrence failed. Wade's is always 100%.
  • Driven to Suicide: In book two, Frederick Tyler, the first Wallfacer, crosses the Despair Event Horizon after his strategy is exposed and he eventually shoots himself.
  • Emergency Broadcast: The president of the Solar System Federation gives one in book three shortly after Singer's "piece of paper" arrives.
  • Everything Trying to Kill You: This is the effect of the computer virus targeted at Luo Ji while in hibernation; any device that gets infected will attempt to kill him somehow. Combined with Everything Is Online, it gets to a point where even sofas are a danger.
  • Fake Defector: Tyler planned to have his Space Fighters seemingly defect to the Trisolarans, only to blow themselves up in a suicide attack and take them out. His Wallbreaker manages to figure out the strategy before it gets very far, though.
  • Flat World: The Solar System by the third book, reduced to 2D (which kills everyone in it). Also the eventual fate of the universe due to dimensional warfare.
  • For Want of a Nail: This is the ultimate plan of the Trisolarans in the first book. By using their absurdly small but extremely fast robots, they can ruin any particle collider experiments done on Earth by randomizing the results. Without those experiments, humans cannot develop weapons that can stop the Trisolaran fleet.
  • Four Is Death: Inverted in book two, where four "Wallfacers" are tasked with formulating the strategy to defeat Trisolaris. The fourth, Luo Ji, is the one who succeeds.
  • Good Cop/Bad Cop: Discussed in Shi's lecture to Luo Ji early in The Dark Forest about shrewdness.
  • Good Is Dumb: Cheng Xin's refusal to endanger human lives leads her to make two Tragic Mistakes that ultimately put mankind in grave danger. It's worth noting that humanity as a whole is far softer and more moral in the Deterrence and Bunker Eras, so they collectively play the trope straight as well.
  • Good Is Not Soft: Officer "Big" Shi.
  • Good with Numbers: Wei Cheng is a child genius and mathematics who has special talent in dealing with numbers, which helps him to solve the three-body problem later.
  • The Great Politics Mess-Up: The Dark Forest, originally published in 2008, has a meeting 20 Minutes into the Future between a former American secretary of defense and an aged Islamic fundamentalist hiding out in Afghanistan who is clearly intended to be — but not named as — Osama bin Laden. The English translation of the book didn't appear until 2015, meaning that the mess-up was baked into it from the start.
    • The second book also has Hugo Chavez's successor as being a highly competent and popular leader who turned Venezuela into the most powerful state in South America.
  • Hand Wave: While most of the fictional science in the book is explored and deconstructed in great lengths, the "mathematical language" that any intelligent species can decipher and use to communicate is taken for granted.
  • Happy Ending Override: Book two ends with the war between Earth and Trisolaris coming to an end, and Luo Ji expressing hope that "one day, bright light will illuminate the dark forest". Come book three, the war resumes, Earth and Trisolaris are both destroyed, and the entire universe is on its way to eternal death thanks to dimensional warfare. Damn.
    • Part of the purpose of book four is to override the override: thanks to the manipulations of a Sufficiently Advanced Alien, the universe does undergo a Big Crunch and is reborn, minus five kilograms of matter. This universe is still wracked by dimensional war, but it's better than the last one. Most notably, the chaotic Trisolaris system is now the stable trinary system that Alpha Centauri is in real life, and a very different Trisolaran species has evolved there, meaning there's no more immediate threat to Earth. Yun Tianming, reborn as a new person with the memories of the old, is tasked with visiting other universes to discover how true peace can be achieved... but first, as a warning, he needs to write down the history of the previous. Writing under the name he has in the new universe, Cixin Liu, he decides to call this history Remembrance of Earth's Past, starting with Book 1: The Three-Body Problem.
  • Hard Truth Aesop: Sometimes, in order to survive, you have to Shoot the Dog.
  • Hero of Another Story: In book 3 Tianming's capture and assimilation into Trisolaran society ultimately commanding sufficient authority and resources that he can order the construction of a pocket universe to gift to his unrequited love could have been a book in itself, but is completely elided. In fact, this inspired a Fan Sequel The Redemption of Time which was subsequently published with the author's permission.
  • Higher-Tech Species: The Trisolarans are far beyond humanity, though not quite to the point of being Sufficiently Advanced Aliens (despite their claims to the contrary).
  • Hit So Hard, the Calendar Felt It: The events of The Three-Body Problem trigger the start of the "Crisis Era". Death's End reveals this to be the first of several times the calendar gets reset.
  • Hobbes Was Right: Reality is a war of all against all on a universal scale due to difficulties of communication and an inability for trust to be established between races. Game theory requires a civilization to wipe out any other intelligent life it discovers. Any race that rejects this reasoning is destroyed by others who accept it.
  • Homeworld Evacuation:
    • Trisolaris is expected to be destroyed for good within a thousand years, hence their need to colonize a world outside its solar system. The fleet they're sending to invade Earth doubles as The Ark.
    • The possibility of sending one or more Generation Ships to flee the solar system before the Trisolarans arrive is a recurring plot element in the second and third books. "Escapism" never ends up getting off the ground, not because of technological or logistical problems, but because the question of who gets to go quickly becomes the Berserk Button for humanity, and no politician is willing to risk a massive international backlash by endorsing it.
  • Hopeless War: Earth versus Trisolaris is widely expected to be this, given the Trisolarans much greater technology, which humanity can't hope to match thanks to the sophon block. The point is really driven home in book two when Earth's entire space fleet is wiped out by a single two-meter Trisolaran probe, nine more of which will arrive within three years, followed by a thousand warships in another two centuries.
  • Human Popsicle: Hibernation technology features prominently in both sequels, allowing people to step decades or even centuries into the future. It was originally developed to allow people with terminal diseases to sleep until a cure was discovered.
  • Humans Advance Swiftly:
    • The Trisolarans estimate that in the five centuries it will take them to reach Earth four light-years away, Earth will have far surpassed Trisolaran technology and will easily crush the invasion force... unless Trisolaris can halt Earth's scientific progress.
    • Even with the sophon block, humanity makes some astonishingly rapid progress. By the early 23rd century, while the Trisolaran invaders are still two hundred years away, they've built a massive Standard Sci-Fi Fleet and constructed space habitats all over the solar system. And this is in spite of a colossal economic collapse (the "Great Ravine") that pretty much shattered civilization as we know it for decades and halved the population of Earth.
  • Humans Are Bastards: Played with. Her experiences during the Cultural Revolution are the cause of Wenjie's nihilism and other experiences of human destructiveness are why many members of the ETO believe humanity deserves to be destroyed. However, in the end it turns out that humans are too soft and sentimental to survive in a harsh universe.
  • Humans Need Aliens: Both main ETO factions, for different reasons. The Redemptionists believe humanity can't be trusted to rule itself, and should be subservient to Trisolaran rulers; the Adventists believe that humans have mismanaged the planet we should be lucky to have and deserve to be annihilated.
  • Humans Through Alien Eyes: The Trisolarians' view of Earthlings subverts the trope that an alien encountering human culture for the first time would reach conclusions that all agree with those of the person invoking the trope.
  • Inscrutable Aliens: The basis of Dark Forest theory. All civilizations in the universe destroy all other civilizations they meet because they can't establish trust. Most likely due to communication difficulty because of the extreme distance, completely different physiology, or maybe it's just not economical to deal with cultural differences and subsequent wars arising from it. The Trisolarans are unique in this regard because their home world is about to fall into a star and they need a new home, so they don't destroy the Earth outright.
  • Insult Backfire: At the end of the first book, the Trisolarans' last message to humanity is a snide "You are bugs!" In the epilogue, the human characters note that humanity has spent its entire history at war with the bugs that infest its crops, and yet those bugs are still around - implying that just because the Trisolarans are more technologically advanced, it doesn't make their victory as certain as they seem to think.
  • It's All About Me: Luo Ji for the first half of the second book. His cynicism runs so deep that for a good while he genuinely doesn't care what happens to humanity, instead using his Wallfacer privileges to enjoy a hedonistic lifestyle for himself.
  • Les Collaborateurs: The Earth-Trisolaris Organization is a terrorist group that believes humanity cannot manage its own affairs and deserves to be conquered by Trisolaris. There are two major factions in the ETO: the Redemptionists, who want to set up a Vichy Earth scenario where the Trisolarans rule over a human utopia, and the Adventists, who believe that humanity is wretched beyond repair and should be exterminated.
  • Loads and Loads of Characters: And disposable too due to the massive time span of the series.
  • Made of Indestructium: Trisolaran tech is impossible to scratch using conventional technologies due to their mastery of the strong interaction. Humanity's space fleets found this out the hard way in book two.
  • Magical Computer: The sophons, Sufficiently Advanced computers packed into a space the size of a proton.
  • Make an Example of Them: Apparently a key part of Trisolaran culture, though the humans go there too.
  • Modern Stasis: The sophons' purpose is to interfere with human technological development so that they won't be able to halt the Trisolaran invasion when it lands. They do so by detecting particle accelerators and forcing them to give random results so that subatomic physics cannot be discovered.
  • Mohs Scale of Science Fiction Hardness: 3 or 4. While often considered an exemplar of hard science fiction (it was previously listed as "easily a 5"), the books rely on several Big Lies as well as some handwaving to get the plot going. The most obvious discrepancy has been mentioned above: The Alpha Centauri system is a binary star system (Alpha Centauri A and B) orbited by Proxima Centauri, rather than a highly unpredictable system of three stars. Proxima Centauri is also a red dwarf, rather than a Sun-like star. The "flying stars" are also unrealistic, as there should be no physical mechanism that filters out the stars' photospheres (the parts we actually see) and leaves behind a visible core. The solar amplification of electromagnetic waves is also something that is made up for this story. Even if we assume string theory is true, this does not mean protons have lower-dimensional structure that can be unfolded and made into an AI. Furthermore, quantum entanglement does not allow instantaneous communication, as proved by the no-communication theorem.
  • More than Three Dimensions: Seen in Death's End with Gravity and Blue Space encountering a fragment of four-dimensional space. It's believed that the universe originally had ten macro-dimensions, but this was reduced to three through dimensional warfare.
  • Named After Their Planet: The Trisolarans are from... Trisolaris.
  • Nice Job Breaking It, Hero!:
    • Wenjie's counterpart on Trisolaris, see Schmuck Bait below.
    • One reason that Cheng Xin is so divisive is that she seems to specialise in these.
  • No Kill Like Overkill: The races responsible for Dark Forest strikes don’t care about collateral damage or preserving inhabitable planets when they wipe out a race. The basic attack seen twice in the books involves blowing up a star. When that isn’t guaranteed to be effective they escalate to weapons that remove a spatial dimension utterly annihilating everything in the vicinity (and, eventually, the universe).
  • No-Paper Future: Inverted during Death's End when the Earth Civilization Museum stores information by carving characters onto Pluto in order to have it last for geographical eons.
  • Normal Fish in a Tiny Pond: The Trisolarans are extremely advanced by humanity's standards, having mastered manipulation of the strong interaction force. Yet they're nothing in comparison to the other aliens out there, who are capable of manipulating the laws of physics, lowering the speed of light, and destroying entire dimensions.
  • Not So Different: The passages describing Ye Wenjie's receiving the first message from Trisolaris and her Trisolaran counterpart's first detection of her message are virtually identical.
  • Punchclock Villain: Singer, the lowest-ranked member of his Starfish Alien crew, whose whole job is to scan for alien civilizations and destroy them from afar (which he often does while singing).
  • Puny Earthlings: The Trisolarans view humans as this.
    • Strangely, averted by Singer from a greater civilization who sees humanity as greater threat despite being not very advanced technologically.
  • Ramming Always Works: In book two, Earth's entire fleet is wiped out by a two-meter long Trisolaran probe which destroys each ship by ramming them one at a time. Turns out they'd figured out how to use the strong atomic force to make their technology indestructable.
  • Razor Floss: The nanofilament, as spectacularly demonstrated with the Judgement Day.
  • Ring World Planet: Many of these types of cities are built behind the shadows of the solar system's gas giants during the Bunker Era to protect against a Dark Forest strike.
  • Sacrificial Planet:
    • Trisolaris used to be one of twelve planets in its system, but the other eleven fell into the suns over time due to a combination of the system's natural Gravity Screw and the suns' periodic "breathing" which caused them to de-orbit. Trisolaris itself will fall in as well inside a millenium, hence their need to find a new planet to colonize.
    • Luo Ji unleashes a dark forest strike on a (hopefully uninhabited) system fifty light-years from Earth to test whether the Dark Forest theory is correct.
  • Schmuck Bait: An inverted version. The message Wenjie receives from the Trisolaran Red Coast equivalent is a sincere warning; however, she's sufficiently disgusted with humanity that she deliberately ignores the warning anyway.
  • Science-Fiction Writers Have No Sense of Scale: Averted; the sheer distances involved in space travel, and the impossibility of communicating easily across the void, form the basis of the dark forest theory.
    • Coupled with that, the discussion about the dark forest theory points out how, at earth's current technological level, we could colonize the galaxy in a million years. Slow for us, but the timescale of the universe, that's less than the blink of an eye.
  • Screw This, I'm Out of Here!: Several civilizations have decided to skip out the horrors of the universe and wait out the destruction by hiding in their Pocket Dimension. This has the adverse side-effect of potentially removing enough matter from the main universe so there won't be enough gravitational pull to trigger a Big Crunch and recreate the universe in its original, unflawed state.
  • Shoot the Dog: A dark forest strike is not an act of malice, but rather one of ruthless self-interest. Because communicating with another civilization leaves you at the mercy of their unknown intentions, and leaving them alone runs the risk of them eventually finding you anyway, the only logical act is to Do Unto Others Before They Do Unto Us.
  • Shout-Out: The alien perfection of the monoliths from the novel version of 2001: A Space Odyssey is explicitly referenced when the Droplets are introduced close-up.
  • Sliding Scale of Idealism vs. Cynicism: The first book is very cynical, the second book drives it all the way into despair-inducing dog-eat-dog hopelessness on a cosmic scale, and the third book takes the scale up even higher by turning the book into a hard-science Cosmic Horror Story where nearly all hope in the universe is gone.
  • Small, Secluded World: Universe 647, the gift universe from Yun Tianming that Cheng Xin and Guan Yifan spend some time in toward the end of the book.
  • Standard Sci-Fi Fleet: Deconstructed. Earth builds a very impressive one in book two, consisting of two thousand ships armed with gamma-ray lasers, hydrogen bombs, railguns, and Space Fighters, and capable of reaching ten percent of light-speed. Unfortunately, the Trisolarans, being a Higher-Tech Species, have technology that is literally Made of Indestructium, and Earth's whole fleet is destroyed by a single probe.
  • Star-Crossed Lovers: Though not exactly lovers, Cheng Xin and Yun Tianming. After learning that it was Yun Tianming that had bought the star for her, she rushes to see him only for her to find that his brain had already been removed. Later, when they talk long distance, they promise to meet each other at that star. Much later, when she hears from 艾 AA that Yun has arrived in her solar system, she tries to reach him only to be stuck in the rupture of a death line.
  • Star Killing: Dark forest strikes usually do this by shooting a star with a "photoid," which is essentially just a rock...fired at speeds just under the speed of light, so that its energy is a significant fraction of the star's mass. The impact literally blows the star open, spewing its contents onto surrounding planets before the star ultimately collapses. This is what happens to Trisolaris due to the dark forest broadcast.
  • Stock Star Systems: Trisolaris orbits the three suns of Alpha Centauri, the nearest system to Sol. Otherwise averted; other systems are referred to by a catalogue number (such as 187J3X1) rather than a familiar name.
  • Stop, or I Shoot Myself!: In book two, Luo Ji manages to scare Trisolaris into calling off their invasion by threatening to kill himself, which would trigger a dead man's switch and send out an improvised dark forest broadcast targeting Trisolaris.
  • Story Within a Story: Yun Tianming's three interconnected fairy tales which he tells to Cheng Xin to covertly pass important information to Earth.
  • Subspace Ansible: The sophons on Earth can communicate instantaneously with their counterparts on Trisolaris via quantum entanglement.
  • Sufficiently Advanced Alien:
    • Subverted with the Trisolarans. They do have extremely powerful technology, but they use it to fake feats that are beyond even them in order to make humanity believe they are this. For example, they can't actually switch off the background microwave radiation of the universe at will, but they can make it seem like they can by wrapping the planet in an extremely thin shell and having it act as a filter.
    • Played straight in book three with the revelation that many civilizations across the galaxy not only have the power to weaponize the laws of physics, but mathematics as well.
  • Summon Bigger Fish: A dark forest broadcast. Basically, you transmit the location of your enemy's sun to the galaxy at large, and wait for somebody to take it out.
  • Technologically Advanced Foe: The Trisolarans have technology far beyond anything humanity can muster. Humans can understand it, to some extent, but beating it is another matter.
  • Telepathy: Sort of. Trisolarans' thoughts are transparent to each other, meaning that they can read each others' minds even at significant distances. As a result they have very little experience with deception and political intrigue, forcing them to rely on their human collaborators to deduce Earth's defensive strategies.
  • Time Skip: A number of times in the sequels, usually when main characters go into hibernation, with the story later skipping to when they wake.
  • Too Dumb to Live: Despite the overwhelming evidence humanity keeps coming up with reasons to reject the Dark Forest interpretation of the universe, can’t quite believe that the Trisolarans really do intend to wipe them out, prohibit attempts to escape from the Solar System and even introduce the death penalty for anyone who tries to develop the technology that would make an escape possible. Ultimately they arrogantly believe, based on only two data points, that they can see a way to survive a photoid strike by hiding behind the gas giants without considering that aliens who have experience destroying civilizations will know all these tricks and, when appropriate, will use weapons that render them ineffective. Cheng Xin is arguably the avatar of this.
  • Unspoken Plan Guarantee: Averted in book one; the plan to use monofilament on the Judgement Day is explained in great detail and then goes off without a hitch.
    • Then invoked quite explicitly in the sequel; the sophons can eavesdrop on any spoken or written communication anywhere in the world. The four people tasked with resisting the Trisolarans have to put their plans into effect without explaining the meaning of their orders or giving instructions which make their plan obvious, or the Trisolarans will simply counter them. Two of the four fail in relatively short order, the third one has his own goal other than resisting the Trisolarans, and the Trisolarans figure it out anyway. The fourth plan eventually succeeds, playing the trope straight as the reader doesn't learn the truth until Luo Ji explains it to Trisolaris.
  • Unusual User Interface: "Three Body" only supports interface via haptic (full body force-feedback) suit.
    • A computer made out of 30 million people was made in the game, which the Trisolarans actually did for real.
  • Villain Has a Point: During the Cultural Revolution, countless atrocities were committed to elevate "the common man" above such supposed elitists as academics and intellectuals. This is part of why Ye Wenjie come to despise humanity so much. However, throughout The Three-Body Problem, most of the evils we see come from one manner of "elites" or another, while the one display of human goodness that almost makes Ye Wenjie reconsider her position comes from common, uneducated people in a remote village. Also, it's explicitly noted that intellectuals are the ones who are easiest to convert to selling out their own species to the Trisolarans, while the regular working man tends to resist the notion. The implication seems to be that the Communists' failing was less in their ideals and more in not recognizing that they were, themselves, behaving in an elitist and technocratic way.
  • Water Is Womanly: This trope is mentioned:
    "A woman should be like water, able to flow over and around anything."
  • We ARE Struggling Together: Both ETO factions (Redemptionists and Adventists) spend considerable resources hunting each other. The Trisolarans engage in a bit of this as well.
  • Weirdness Coupon: Luo Ji is among the four people tasked with resisting the Trisolaran invasion, and he uses this power to make a series of bizarre demands. The Earth government can't ask him to explain what he is actually trying to accomplish and goes along with it for some time. Eventually they come to believe he actually doesn't have a plan and increasingly restrict what he is allowed to do. Earth is right at first, but Luo Ji's increasing irrelevance means the Trisolarans miss their chance to stop him when he does finally come up with a plan.
  • Year Outside, Hour Inside:
    • The area in the wake of a sufficiently-powerful lightspeed jump slows down the speed of light considerably, so anyone within will feel time like this. This is how one can signal to the rest of the universe that a planet/solar system is "safe." Cheng Xin and Guan Yifan get trapped in one, spending 12 days in one while seventeen million years pass outside.
    • The flow of time in the pocket universe Yun Tianming leaves for Cheng Xin and Guan Yifan is tuned so that they can survive until the great universe is reborn. They end up exiting after one year, while over ten billion years have passed outside.
  • You Are Worth Hell: Invoked in book two when Zhang Beihai is about to nuke the rest of Starship Earth to protect the Natural Selection.
    Zhang Beihai: Children, let me do this.
    Dongfang Yanxu: You mean, 'If I don't go to hell, who will'? Is that it?
    Zhang Beihai: From the moment I became a soldier, I was prepared to go there if necessary.

"If I destroy you, what business is it of yours?"

Alternative Title(s): Three Body Problem


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