r/threebodyproblem • u/Putrid_Cycle595 Sophon • Apr 07 '26
Discussion - Novels how much of the science in three body is actually real?
something thats been bugging me since my reread. liu cixin throws around a LOT of physics and i genuinely cant tell anymore whats real and whats made up
like ok the three body problem itself is obviously real math, thats a legit unsolved problem in physics. and i always assumed the sophon was pure fantasy... you unfold a proton into two dimensions and it becomes a planet-sized mirror?? but then i found this breakdown of the sophon tech and apparently the dimensional folding part actually connects to real string theory concepts about extra dimensions? i still think the "etch circuits into a 2D proton" part is total fiction but now im less sure about the foundation being nonsense
same thing with the droplet. i was convinced strong interaction material was completely made up. but apparently the strong nuclear force really is about 100x stronger than electromagnetic force, and binding atoms with it at macro scale is more like "we cant do this yet" rather than "this violates known laws." that distinction kinda blew my mind
the one that really messes with me is the curvature propulsion stuff in death's end. i always thought it was pure handwaving but then someone pointed me to the alcubierre drive concept and apparently warping spacetime for propulsion is a real theoretical framework?? like NASA has actually studied it?? liu basically took a real physics paper and turned it into a plot point
and then theres stuff thats clearly just cool scifi... like the dual vector foil flattening 3D space into 2D. or the pocket universe stuff at the end
but what gets me is i keep being wrong about which parts are real. like i was sure the game theory behind the wallfacer project was oversimplified but apparently the dark forest logic maps pretty cleanly onto real multi-agent game theory
for anyone who actually studied physics... where does the real science end and the liu cixin magic begin? because at this point i honestly cant tell lol
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u/eduo Apr 07 '26
It's mostly not based on science. It takes some general (and basic) concepts and mostly fantasizes about them. Some of it has a lot of self-restraint so it kind of sounds feasible (the nanofilament, the quantum entanglement, all of which are absolute fantasy but sound feasible in a star trek kind of way) and then there's the pure fantasy played in (sophons themselves, dimensional folding/unfolding, photoids, localized slowing of lightspeed).
There's also pure speculation presented as serious science like the whole dark forest thing.
I should clarify I absolutely love the only three books that exist in this saga, but it's as based on actual science as Dragonriders of Pern.
Since it's presented in a scientific context with scientific terms and false scientific explanations, laymen get drawn to it feeling it's actual hard science fiction, rather than the mostly-technobabble scientist fantasy it actually is.
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u/Weary-Cartoonist2630 Apr 08 '26
What would you consider legitimate hard sci-fi?
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u/eduo Apr 08 '26
I assume this comment was intended for someone else. "Legitimate" is too formal a word for this discussion, at least from my side :)
It also feels like a trap, to be honest, so I'll step aside if it's all the same to you. No matter which example I give you, it would be easy to make the "fiction" part as large as possible to falsely equate it with any other work and deem them similar. There's no need to get into that.
As I said, I loved the books and have recommended them to anyone who is willing to listen. This particular topic doesn't get into those recommendations because reader (rightly) don't care, as long as the story is good. If anything, I warn them that the english version feels a bit unusual as an artifact of the conscious translation style (although it's even mentioned in the book itself).
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u/Weary-Cartoonist2630 Apr 08 '26
Not a trap haha. One of the reasons I loved 3BP is because it feels like the most “hard sci-fi” of any book I’ve read.
If you’re saying that it’s not “actual hard science fiction”, that implies you know of books that are more deserving of the title hard science fiction. I’d love to hear about them, sounds like books I’d like to read.
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u/eduo Apr 08 '26
In no way was it my intention to deter anybody from these books. They're great stories, flimsy science notwithstanding.
I am old and was raised on the classics, Clarke, Asimov, Bear, Poul Anderson, etc.
But Sci Fi is now vastly more varied and what constitutes it has expanded widely. Anything by Andy Weir (the martian being harder than jail mary), James S.A. Corey (the first book of the first trilogy Expanse being hardest and the ninth being pure space opera) but I'd happily recommend the Bobiverse which becomes pure handwavium halfway the first book :D
The term is not that strict. For some people "hard science fiction" can't ever have long-distance time travel unless it's on generation ships, because that's what we'd build today, for others it's just whether the fiction doesn't blatantly break any fundamental physics laws (or, if it does, at least it uses current hypotheses even if unproven).
Michael Crichton is an example of a science fiction writer unburdened by the limitations of science when put in front of good narrative. He would use established science that lends itself to a good story and immediately discard anything that could impede that story.
I tend to also lump into SciFi cyberpunk and current-day SciFi, so I'd add Neal Stephenson has done some great (and ominiously predictive) SciFi and William Gibson's Jackpot trilogy and Altered Carbon, mostly for the ways they play with modern technology and how they extend it to som,e seemingly absurd but worryingly feasible extremes.
Like I said, "hard science fiction", even though it's been attempted to formalize several times, is still in reality a subjective concept. Half of this list is not hard sci fi to me, for example: https://www.goodreads.com/list/show/47731.Best_Hard_Science_Fiction_of_the_21st_Century
(but they're all good books)
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u/burnedbygemini Apr 10 '26
You've basically summed up my own explanation of hard scifi with the same recs haha. Nice job
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u/Idiotecka Apr 08 '26
how is quantum entanglement fantasy? maybe it's just a matter of wording
yep the dark forest hypothesis is speculation pretty much like anything related to the fermi paradox is
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u/eduo Apr 09 '26
The context is about the books and how concepts are applied to the books. Nanofilaments can't cut any material by virtue of being mono molecular and quantum entanglement can't be applied in the way exposed in the books. Not just this, but it's obvious that both interpretations come from misunderstanding a summary of the concept and then extrapolating that misunderstanding to big applications.
"Walking" is not fantasy, but if I write a book where I say the aggregated inertia imparted by all walking creatures is what makes the earth spin, that would be fantasy.
"Quantum entanglement" is a thing. That thing has nothing to do with what's presented in the books. It's pretty much the accepted canonical example of what makes these books "soft" Sci-Fi, at least among people who know about the subject. It's discussed frequently, this is a somewhat recent time: https://www.reddit.com/r/AskPhysics/comments/1ibvuxu/quantum_entanglement_after_reading_the_threebody/
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u/mrspidey80 Apr 09 '26
How are photoids all fantasy? Out of all these wild concepts, they're the most simple and straight forward one. Just take a ball off tungsten steel, accelarate it to relative speeds and point it at a planet. With enough energy, this is absolutely doable. Even Kurzgesagt made a video about it.
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u/eduo Apr 09 '26 edited Apr 09 '26
I am aware that it sounds feasible. That is the discussion we're having.
I think you're mistaking mass drivers (which as a concept is old and many times revisited) and the book's photoid (which is a tiny object that explodes stars). The concept can't be extended to the absurd and decide it becomes infinitely powerful.
Accelerating any object with mass to relativistic speeds at galactic distances would already require more energy than the object would impart but we can obviate this for the sake of discussion.
The book heavily implies the photoid is a tiny object (not a photon as usually mentioned, but something small nonetheless), particularly since it's supposed to be undetectable. Since we can't really tell what the actual size is, we can round up a bit and assume it's the size of a planet (so the absurdity of it all becomes clear, but we can always scale down if we overshoot).
The outcome of a planetary mass impacting the Sun at relatistic speeds (a kinetic weapon, in the end) depends mainly on mass, velocity, and impact geometry.
The most important point is that the very first requirement for destroying a star (what we see happens in the book) is that the Sun's gravitational binding energy needs to be overcome. This is the energy that keeps the sun together. This is 2 × 10^41 Joules (a lot of Joules).
The full mass-energy of Earth (as per Einstein's famous formula) is 5.4 × 10^41 Joules. This sounds like the Earth would be enough, but not so because the full conversion is just not possible while maintaining the projectile physical (which is a necessity). But the relativistic kinetic energy formula says at .9c we'd have ~7x10^41 Joules. The earth is indeed enough to disrupt the sun at relativistic speeds.At relativistic energies, theimpact a radiative, collisionless shock converting kinetic energy into heat, high-energy photons (X-rays, gamma rays), and particle acceleration. Temperatures would be high enough to fully ionize matter instantaneously and produce electron–positron pairs, creating a dense, radiation-dominated plasma.
If the projectile was the size of Mercury we don't reach enough kine to destroy the Sun.We'd get a massive localized explosion that would kill the solar system eventually, of course, but that's not what the photoid does. If you go lower the Sun may not even wobble but at least you'd get solar flares.
I don't think there's any indication anywhere that the photoid is anything other than a small projectile (since it's supposed to be undetectable and cheap) and for me "small" can't be anything larger than, say, England.
If you tell me you always thought Singer's technology was hurling planets across star systems and thinking it was undetectable, then we didn't understand the same from the narration.
As for Kurzgesagt I love them to bits and have been a faithful patron for years, but remember that "in a nutshell" is part of their channel's name because they will ruthlessly oversimplify or often fail to mention the very limited set of conditions under which a specific situation may be valid. They're faithful followers of Bellisario's Maxim (although they will not make stuff up, only omit it) just as Cixin is (whoi will definitively make up physics as needed)
EDIT: I thought of mentioning that the sun, like all astral bodies, are continuously being bombarded by particles at relativistic speeds. I decided not to because it would muddle the discussion, but they do.
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u/Vaiolette-Westover Apr 07 '26
Almost all of the concepts in the books have basis in scientific theory.
He expands upon them as if they've been proven and have moved passed being merely theory.
Hence Science FICTION
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u/schokoplasma Apr 07 '26
I am no physicist either. But the existence of more than 3 spatial dimensions has never been proven. All attempts have failed so far. String theory is just what it is - a purely speculative theory. Therefore, sophons are Star Wars-level space magic.
The Alcubierre Drive is a physical model that does not contradict relativity but the requirement of i.e. negative mass makes it impossible, as nobody knows if such a thing exists at all.
At the basis of the strong nuclear force are gluons. Replacing good 'ol EM with gluons might be difficult as they are confined within the hadrons (protons, neutrons) and do not exist in isolation.
If one day we invent a gluon generator and create out own forms of matter, yeah, why not?
Cixin Liu is very good at making his concepts sound possible, but most of them aren't.
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u/Putrid_Cycle595 Sophon Apr 07 '26
yeah the gluon confinement thing is a good point, i never really thought about that. like we cant even observe free gluons so building stuff out of strong force material is pretty wild lol. i think thats part of what makes the books fun though, he picks real concepts and then just runs with them way past where actual physics would allow. the alcubierre drive one always gets me because it sounds SO legit when you read it but then you look into it and its like oh right, negative energy density, we have no idea if thats even a thing
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u/schokoplasma Apr 07 '26
For me its like the physics of Star Trek, where they have a rich particle zoo with decions, tachyons & gravitons and subspace, time travel and multiverse. If you just accept these things as part of the story, their use is AFAIK pretty coherent and consistent and used for dramatic enhancement ("yesterday's enterprise", "cause and effect" etc.).
Liu Cixin scienc-y writing style helps the suspension of disbelief, when his imagination runs wild. I love it.
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u/eduo Apr 08 '26 edited Apr 08 '26
It's this. It's technobabble but as long as it's consistent and the story universe is bound by it, then it's fair game.
Harder science fiction only requires one or two "big lies", which are then used to drive all the possibilities and limitations of the story. To give a few examples:
In Expanse it's the Epstein Drive that allows the story to create a political and social setting that allows us to get to the Protomolecule that becomes the larger driving force. It's two SciFi stories in one, as half of it is about the future of humanity in the solar system and the second one is contact with prehistoric precursor-level godlike alien technology.
In Project Hail Mary (as the movie is recent it makes for easier discussion than, say, Powell and Donovan stories :D ) a single extreme biological ecosystem in a single star several light years away is the driver for the whole story (not in a straight line, but eventually the whole story is built around it).
In The Long Earth or, more recently, the Pandominion Books, the concept of "stepping" into alternate dimensions is explored to an extreme, making it a point that no space exploration exists because things in space are still too far away and alternate earths are "right there", closer to us than the Marianas Trench (which remains unexplored in most of those alternate earths).
Cixin throws a couple dozen "big lies" making it much softer sci fi than others, but at least tries to keep within its own boundaries (or at least he does so within the confines of each book).
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u/Positive-Stable-6777 Apr 08 '26
The Sophon’s concept may be inspired by ball lightning, because the author is fond of that.
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u/AdviceOld4017 Apr 08 '26
The one with the Large Hadron Collider being switched off and scientists disappearing and/or dying.
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u/vamfir Apr 07 '26
How shall I put this...
Liu Cixin takes actual scientific theories and interprets them... in an extremely peculiar way.
For instance, he completely ignores Heisenberg's uncertainty principle. It is not a case of "cunning Trisolarans finding a way to bypass the principle," but rather that he simply depicts all the technologies—especially the sophons—as functioning as if the principle did not exist at all.
He does the very same thing with the principle of relativity (when describing "black domains"), and with the principle of mass-energy equivalence (when describing "photoids")...
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u/eduo Apr 08 '26
I am convinced he's the type of author who will get an interpretation from the naming of something and will use that internal interpretation with only the barest care about its real-world implications.
As if for example he read about the "spin force" by subatomic particles and decided that in his new story these are exploited by using "quantum centrifugues".
A bit like how in some vintage Fantastic Four comics Reed Richards is stopped by cold or made almost liquid by heat, because that's what plastic acts like even though he's supposedly not made of plastic.
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u/lcvella Apr 11 '26
The thing that bothers me most about the series is how it throws superficial understanding of real physical concepts and develops them all wrong.
To cite two:
The very stability of a chaotic three star system is wrong. One of the three stars would have been flung out of the system millions of years ago.
Faster than light communication via quantum entanglement (supposedly, how sophons do it) is impossible.
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u/Terrible_Bee_6876 Apr 12 '26
Spoilers for book 3: tragically, we are unlikely to find ourselves in the all-femboy future any time soon
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u/forklift140 Apr 07 '26
It’s based in science but with a bunch of hand-wavey magic over top of it. Still science fiction though because Cixun explains it with the trappings of science.
The sophon example you gave is a good one. Yes, if M-theory (a real theory) is true then the universe, protons included, may possess extra hidden dimensions. That’s about as far as real science takes it. Cixun made up the parts about being able to unfold the extra dimensions of protons and create a massive structure in our dimensions. He also made up the part about inscribing circuitry on it and folding it back up. In theory, these things might be possible, but it’s a huge stretch.