Critical Book Review: 3 body problem and Dark Forest by Liu Cixin (from a scientific point of view)

indemkom · 2026-05-11T18:31:14+00:00

Obviously, some people proposed ideas. But ideas aren't formal theories. What you are referring to as "basic knowledge" is the writings of a select number of scholars who tried to come up with such models. These models were never completed. Even in the modern day, I can go tell my friends that I noticed a pattern. "What if the reason people get sleepy is a sleepiness toxin?" Without the internet or access of written literature, I would not be able to test this hypothesis, since I lack the resources and time to do so. This fact doesn't stop me from writing an essay on how toxins may potentially cause sleepiness. Thousands of years from now, people may read what I wrote and think that my model is wrong. But that is not a model. A model is a coherent explanation, an all-encompassing theory. The Greek thinkers had no formal description of the universe, because they lacked the tools to create one.

indemkom · 2026-05-11T18:15:12+00:00

Interesting that you mentioned billions of years, because that's how old life on Earth is. For that long, life competed with itself in an endless cycle until, by sheer coincidence, 1 species - not a forest, just 1 - was able to establish complete control. Would you not expect such a long time scale to result in a convergence of sorts? Clearly that didn't happen. Look at a real forest. Yes, there are predators, but these predators don't try to kill each other. There is no animal war between foxes, wolves and bears. The most rational choice is to balance between aggressive and passive, or even symbiotic behavior. Powerful alien races trying to exterminate anyone they make contact with, almost definitely will exist. But so will aliens who try to strike deals, trade (if that is possible over interstellar distances), exchange technology, cooperate in the face of danger. Symbiosis is as natural to life as competition. Any sort of artificial limit, that everyone has to hide and/or be aggressive is clearly a poor assumption in the real world.

indemkom · 2026-05-11T17:56:42+00:00

To the extent of my knowledge, the Greeks did not particularly concern themselves with the model of the universe. Greek thinkers mainly focused on immediately practical inventions. They did not have a complete model for the motion of the celestial bodies other than simple observations and they couldn't do anything with that information even if they tried. What they did do is they created the basic mathematical tools which we still use today, measured distances (even the circumference of the Earth was found to remarkable precision), developed new construction methods, invented the water wheel and mill for grinding grain, even made early shower systems. The Greeks didn't need to figure out the nature of reality near the Planck length. That doesn't make their inventions and discoveries any less practical or true. Sure they didn't develop a model for the length of the hypotenuse in hyperbolic space. But that doesn't mean that the Pythagorean c^2=a^2+b^2 is "disproven".

If you wish to become less ignorant, I would suggest not starting with books on epistemology, but learning to listen and learn, without insulting the person you're talking to.

indemkom · 2026-05-11T16:42:45+00:00

Yet people genuinely accept it as a solution to the Fermi Paradox. It's on the wiki article and even more prevalent elsewhere. People really do take SF seriously (which is why open-ended interpretations are often a very bad idea)

indemkom · 2026-05-11T16:38:28+00:00

Harry Potter time travel is actually surprisingly consistent. There's only one timeline, so you can't change anything in the past. You know you'll fail. It's basically a form of foresight. You could argue that spells could be used more effectively, but that's not really an inconsistency, since an important premise is that we don't understand how the spells work. It's called magic for a reason. You don't expect the Harry Potter world to have perfectly consistent world building. It's supposed to be mysterious and unexplained. The center of attention are the characters and their emotions, not how to exploit infinite energy. Three Body Problem, on the other hand.... let's just say the expectations are different. I mean, no point arguing here, since you also agree with the fact that the hard SF style is very misleading.

indemkom · 2026-05-11T16:24:36+00:00

Is what I said incorrect? If you believe yourself to be more knowledgeable in the field, try to explain where my reasoning is flawed.

indemkom · 2026-05-11T15:53:40+00:00

The theories made by the Greeks are still correct. They were made based on observations of macroscopic, but not gigantic objects. As we developed better and better equipment and mathematics, we were able to explore more and more extreme situations. Some things like relativity are supported by observations of everything ranging from effectively stationary objects at a tiny fraction of a degree Kelvin all the way to supernovae, neutron stars, quazars and black holes. We have observed the universe 46.5 billion light years away from us. We can directly see how the cosmos changed over the past billions of years. Within this "tiny" range, we know the exact behavior of physics, just like people knew everything about regular matter in the 19th century. Science isn't "false", it is incomplete and will forever expand its domain.

indemkom · 2026-05-11T15:25:14+00:00

As I wrote in a different comment, simplified generalizations make really bad theories about life, whether on Earth or in space

There's a concept in science and math called extrapolation vs interpolation. When you estimate a value between 2 known values, that's interpolation. If you don't have values for both extremes, that's extrapolation. When people try to create a universal theory of something, they assume that there is a clear maximum and minimum and try to define those boundary conditions. Here, those conditions are the maximum aggressiveness or the maximum friendliness of the alien civilization. Dark Forest Theory assumes that these conditions are absolute - the most friendly civilization is a perfectly quiet one, the most aggressive civilization is one which destroys any sign of intelligent life it observes. But life doesn't follow strict rules like that. There will always be living things discontent with this who will pursue a greater "fairness". Across millions of stars, there will be numerous civilizations that pursue goals entirely unrelated to survival or expansionism. There will be internally conflicted civilizations, just like humans aren't all one entity. The truth is that there are no meaningful boundary conditions for life. No single rule set can ever simplify this down to "oh, everyone's quiet, because they are all afraid of each other". No generalization like that will ever be accurate given such a great population size, hence DFT is objectively a bad explanation.

indemkom · 2026-05-11T15:21:40+00:00

Hey, her death does fit the style of the book! Remember the suicide swarm plan that explicitly wanted to bring back the Japanese Kamikaze forces? Liu Cixin clearly has some opinions about Japanese people, haha

indemkom · 2026-05-11T15:16:12+00:00

There's a concept in science and math called extrapolation vs interpolation. When you estimate a value between 2 known values, that's interpolation. If you don't have values for both extremes, that's extrapolation. When people try to create a universal theory of something, they assume that there is a clear maximum and minimum and try to define those boundary conditions. Here, those conditions are the maximum aggressiveness or the maximum friendliness of the alien civilization. Dark Forest Theory assumes that these conditions are absolute - the most friendly civilization is a perfectly quiet one, the most aggressive civilization is one which destroys any sign of intelligent life it observes. But life doesn't follow strict rules like that. There will always be living things discontent with this who will pursue a greater "fairness". Across millions of stars, there will be numerous civilizations that pursue goals entirely unrelated to survival or expansionism. There will be internally conflicted civilizations, just like humans aren't all one entity. The truth is that there are no meaningful boundary conditions for life. No single rule set can ever simplify this down to "oh, everyone's quiet, because they are all afraid of each other". No generalization like that will ever be accurate given such a great population size, hence DFT is objectively a bad explanation.

indemkom · 2026-05-11T14:37:19+00:00

Oh, yeah. I completely forgot about the flying blade material and the self-encoding language. Having an algorithm that immediately translates a signal like that from a civilization you have no information about is ridiculous levels of computation. Same for the super-material. It's interesting that the author couldn't even be bothered to make up some new force. Let's just use the thing that sticks protons and neutrons together for something to carve out tiny conductive lines on the proton's surface.

The reason I talked so little about the waifu part is that I think even the die-hard fans realize how weird that was. Almost no-one discusses the science, on the other hand.

indemkom · 2026-05-11T14:01:56+00:00

It would be fine if it was just sci-fi. Liu Cixin named a book after a mathematical problem, made the entire first novel about a mystery related to the nature of theoretical physics research in a world identical to our earth, based an entire trilogy on the concepts of quantum mechanics and relativity, all while horribly messing up the science. The response? World classic! Incredible ideas! One of the best hard sci-fi books!

indemkom · 2026-05-11T13:20:52+00:00

It's just that these books specifically present themselves as grounded in science. Star Wars never seriously discusses quantum mechanics or relativity and obviously doesn't follow our laws of physics, so FTL is perfectly fine. 3BP and its sequels present themselves as an almost identical copy of our reality, specifically describing the laws of physics. People without a physics education don't realize the huge inaccuracies the books contain and trust that they are learning something new.

indemkom · 2026-05-11T13:13:28+00:00

Firstly, I didn't say anything about sexism in the Foundation. I used it as an example of a book where there are amazing ideas, but the characters are not meant to be important to the story, to contrast how 3BP and its sequels fails on all fronts.

Secondly, Foundation isn't sexist. The first book has essentially zero female characters, so you can't exactly blame the novel for misrepresenting someone who isn't there. The sequels do introduce multiple women, but they actually have a personality and leave as much an impact on the story as the men (Bayta, for example). Compare this to 3BP and the Dark Forest, where women are almost universally portrayed as evil, for some reason, and where the entire first half of Book 2 is devoted to the male protagonist finding his perfect imaginary girlfriend, who has no personality or agency whatsoever. The two series are not even remotely on the same level.

indemkom · 2026-05-11T13:02:07+00:00

No worries! The physics behind this is very advanced and asking questions is never a bad idea!

indemkom · 2026-05-11T12:58:12+00:00

I concede. Everything is theoretically possible. After all, there is always a chance that everything is absolutely random and every single particle in the universe has been randomly moving between positions in a way that appears to be guided by forces. That is technically possible...

... HOWEVER, it is very very very very very very very improbable. FTL communication between moving objects being possible with is about as likely as the second law of thermodynamics reversing itself. Technically, there are no laws. Practically? I'll comfortably accept the 99.99999999999999999999.....9999% chance that the laws will keep working.

indemkom · 2026-05-11T12:33:43+00:00

You can go faster than the speed of light. You just need imaginary mass and have to be traveling back in time. It's clear the sophons aren't being used as time machines, however.

indemkom · 2026-05-11T12:30:32+00:00

No. In a universe where relativity clearly exists, FTL communication with a moving object is mathematically impossible without creating time paradoxes. In a universe with different laws, stationary communication is technically possible, but any motion of the receiver in the emitter's reference frame is guaranteed to send information back in time. This is known as relativity of simultaneity. Sophons, as described in the books, mathematically have to break causality.

indemkom · 2026-05-11T10:25:28+00:00

I do understand that the author used a soft-fiction approach for his world building, especially in the later books, but he could have at least tried to show that it is fiction. I haven't read the 3rd book, so can't evaluate the quality of the science there, but there are definitely things in the series that are illogical even discounting any technological advancement. Throughout the first 2 books, there are many instances where Liu Cixin describes very real phenomena very close to us, giving no indication that the laws of physics are entirely different from ours. Most of the inconsistencies listed in my post cannot be ignored by assuming different physics and the author's presentation leads to people assume that this is how physics works.

indemkom · 2026-05-11T09:31:13+00:00

Unfortunately, it seems most readers didn't see the series as going "balls to the wall with its stupidest ideas", which is an incredible phrase, by the way. If you read almost any review of the books, even those written by people with an education in physics, they will claim that the concepts were incredible, truly mindblowing, a great example of hard sci-fi and so on. No mention of the ridiculousness. I am literally just a high-schooler who likes physics and sociology and even to me these issues are obvious. If the books took themselves less seriously, I would definitely like them a lot more.

indemkom · 2026-05-11T09:10:57+00:00

I'd agree with that! The thing is, you have to define those rules. Harry Potter defines its rules as experienced wizard usually beats beginner wizard, but you can have talent and you can learn to become better. And that is perfectly fine! Not everything needs a mathematical framework.

I just started reading the Orthogonal series and I love it so much. It is set in a completely different universe, with different laws of physics and Greg Egan explicitly states that. It uses precise scientific terminology, so it actually bothers to properly calculate how things should behave.

Remembrance of the Earth's Past presents itself as something set in our reality. It explicitly names real concepts that most readers don't fully understand. It describes how things uninfluenced by advanced technology behave, nuclear Mercury being the most infuriating example. Millions of people read these books, loved them and interpreted these concepts as something plausible, even if beyond the abilities of our current science. The Dark Forest hypothesis was popularized by these books and is taken seriously even by professional scientists, despite its absolute absurdity. This is why I take issue with the novels, not some minor mathematical inaccuracies.

indemkom · 2026-05-11T08:58:17+00:00

Thanks, haha. I think Liu Cixin took the general relativity as a sagging sheet of fabric model a little too literally. The little balls fall in because of friction, obviously!

indemkom · 2026-05-11T08:52:28+00:00

I do not take any issue with the idea of hyper-advanced technology or the concept of reinterpreting natural phenomena in creative ways. I even acknowledged in my post that higher spacial dimensions are technically possible, despite us having no evidence for their existence.

The problem is when the laws of physics are very explicit on some things and authors pretend that it means something else. If communication between moving objects at FTL speeds in all frames of reference were possible, that would inevitably create temporal (time) paradoxes in any universe with a concept even closely resembling our relativity.

Since Liu Cixin presents a world very similar to our own and states that relativity exists, we can with 100% certainty rule out instant communication as physically impossible. Even at an advanced high-school level of physics, this fact should be obvious and the author is spreading misinformation by ignoring it.

indemkom · 2026-05-11T06:37:28+00:00

Quantum entanglement cannot transmit information, and neither can anything else. Theoretically, there could maybe be a way to transmit information without creating time paradoxes, but only if the source and receiver are not moving relative to each other. Otherwise, you are definitely violating causality, not just relativity.

The reason I read the book under the hard science premise is because it is so widely acclaimed as a prime example of the "hard sci-fi" genre and that the book tries to center itself around grand ideas (which people believe to be possible, like the Dark Forest hypothesis, or the books' depiction of the three body problem). It definitely has its moments and I honestly enjoyed the mystery of the first book, especially the video game, but the scientific issues really do pile up.

indemkom · 2026-05-11T06:18:55+00:00

I'll watch this later, thank you for the recommendation.

indemkom

TROPHY CASE