Tuesday, October 20, 2020


When I find an author whose work I enjoy, I'm tempted to read as little of their work as I can, as slowly as I can, to drag out a supply of fresh good novels as long as possible. So it's a little unusual that I would so quickly return to Liu Cixin so quickly, but here I am, just a month after finishing The Three Body Problem and wrapping up the sequel, The Dark Forest. Part of that might be because of COVID focusing my attention, part might be the sci-fi kick I've been on lately, but I think the most compelling thing is just that 3BP was a damn fine book, and I wanted to read another one.

MINI SPOILERS for The Dark Forest, MEGA SPOILERS for The Three Body Problem

I put this book on hold at the library the moment I finished the first one, but I also was a little skeptical about just how Liu would manage to follow the first book. 3BP had so many wonderful tricks that seemed impossible to repeat. Even though it was nominally a science-fiction book, it opens during the Cultural Revolution and feels like a historical fiction novel for a long time, and then like a mystery novel for quite a while. It isn't until near the end of the book that we finally learn what the Three Body Problem is and who is behind the events of the story. But now that we do know, how can the mystery be maintained? I was curious if the series would transition into a more typical sci-fi novel with space battles, or if he would try to repeat the historical and mystery aspects again.

As it turns out, he does neither, and instead segues into still another genre. Most of this book feels like a political thriller, on a global scale grander than anything this side of seveneves. Earth is nominally united against the Trisolaran threat, but old divisions still exist, and we see the tacit struggles occurring between West and East, global North and global South, between established industries and nascent ones, between various ideologies. Political capital is gathered and exploited and expended and lost as various leaders and strategies rise and fall.

There is a pretty solid break from the previous book, both in the structure and tone, and also just in the characters. Most of the major people from 3BP are missing in TDF or just have brief cameos, with Shi Qiang the one major recurring character. But it also adds to the sense of scope and scale of the story: this is an enormous crisis gripping all of humanity for centuries, so of course different people will be involved at different times.

There is a nice mystery aspect that continues in this book, though. The mystery in 3BP mostly revolved around the titular game, what was killing the scientists, and how it related to the Red Coast Base; it's a mystery about an adversary. In TDF, the mystery is about the allies. The single most creative and exciting idea in this novel is the "Wallfacers", four men who have been selected to create and carry out secret plans to thwart the Trisolaran invaders.

Doing a bit of recap for my own benefit: At the end of 3BP, we learned that the Trisolaran fleet is en route to the Solar System, with the stated goal of destroying all of humanity and settling on Earth. Their technology is vastly superior to ours, but they are concerned about mankind's fast progress: The Trisolarans have been more advanced than us for hundreds of thousands of years, but in the last 200 years we have progressed more rapidly than they had in thousands of years, and if that trend continues then by the time they arrive (around 2400 AD) humanity will have become vastly more powerful than them and easily able to crush the invasion.

It will take centuries for the Trisolarans to arrive, but thanks to their mastery of subatomic physics, they are able to manipulate events on Earth at the microscopic level. (Think quantum entanglement.) That isn't enough to take macroscopic action like assassinating a head of state, but through their sophons they are able to spy on humanity, seeing and hearing everything that takes place; and they can interfere with subatomic experiments, thwarting the efforts of particle accelerators and colliders to plumb the mysteries of neutrinos and other fundamental elements of the universe. Thanks to this, they effectively place a lock on humanity's progress: we can continue developing the existing technology we have, but entire fields of study are closed off, including quantum research (and its computational advantages), strong nuclear forces, and so on.

But, there's one thing the Trisolarans can't do: they can't peer inside our minds. They can observe what a human says and what he does, but the "why" remains a mystery to them. So, the Wallfacers exploit this weakness. They carry out their plans in plain sight, but everyone, human and trisolaran alike, is aware that there are other angles and wrinkles to those plans, and are constantly kept guessing what their true aim is.

This all ends up being incredibly fun, with wheels within wheels, as we try to guess what the various Wallfacers are up to.


Hines is probably the most interesting Wallfacer to me. When reading the detail about how Keiko's eyes flashed open as soon as she was going to sleep, I guessed that she was his Wallbreaker, though I still wasn't sure what the implications of that were. One random idea I had was that, since Luo Ji was chosen because Trisolaris was scared of him, Hines might have been chosen if the PDC know that Keiko was a member of the ETO. In this scenario, part of Hines' deception could have been feeding misinformation through Keiko back to Trisolaris. Or, another thought was that maybe Hines was the Wallbreaker all along and Keiko was secretly the Wallfacer. Of course, neither of those scenarios is true, but it was fun to think about! So many of the plot twists in this story were wild, so it felt like no possibility was out of bounds.

Even at the end of the novel, I'm still not totally clear on exactly what Hines' plan was and what its status is. Where are the sleeper agents? At first I thought that they had fully permeated society and implanted the mental seal on everyone, but that doesn't seem to be the case, given how virulently everyone reacts against Escapism near the end. And I don't think it had a major impact on the actions of the ships escaping the teardrop assault, as the main actors there were all hibernators who had gone to sleep prior to the seal's invention. It feels like this might be something coming back in the third book.

Of course, Liu ends up being the most successful Wallfacer of the four. His "spell" seemed simultaneously obvious and opaque. I was certain that some greater power would respond to his message by wiping out the planet he indicated, and that is in fact what happened. But I wasn't expecting the cosmic sociological theory behind it, which turned out to be shocking and fascinating. I'd thought that it would be some sort of higher-dimensional entity, somewhat like when the Trisolarans summon the sophons in the previous book, or if, like, a colony of ants were to form an arrow pointing at a thing they didn't like, and some giant human then casually destroyed that thing. But it turns out to be a matter of numbers rather than a matter of scale, which is really interesting to think about. After reading Liu's afterword to 3BP, I thought he was probably too pessimistic about encountering alien life, but the explanation in this book is definitely sobering, and makes one reconsider the wisdom of our constant broadcasting.

This is, of course, the Dark Forest of the title. I spent most of the book wondering what that referred to. Late in the novel, after Liu reawakens in the future, we learn about the tree structure of the underground city, so for a while I thought the "Forest" referred to the city, and mused that "Dark" could refer to it being underground, or engaged in sinister activity, or some future event that would cut out the limitless power from the city and plunge it into eternal gloom. But, yeah, the title ends up referring to the entire universe, so that's pretty cool. It's another thing that reminded me of 3BP in how late we learn about something huge that causes us to rethink the entire galaxy.

Besides the epic distance and physical scale of the book, the span of time is also really epic and intriguing. I almost immediately thought of A Canticle for Leibowitz, which also had multiple-century jumps through time and radical changes in the social and technological order. TDF has a lot more interweaving between the eras, though, thanks to hybernation technology. Though, now that I think of it, the Lazarus/Benjamin character in ACfL could perhaps be playing a similar role, but without offering a point-of-view perspective. And the hybernation of humans could have some parallels with the Trisolaran cycle of dehydration and rehydration.


Liu kept the magic going for the second book, which is really impressive, given how moved I was by the first one. I'm really curious where they'll go from here in the third book! It would be a fairly satisfying ending on its own, with a vision for the future sketched out, some cool callbacks to the previous book and the major characters being in appropriate places. But there are definitely some loose threads out there (Garden of Eden, anyone?), as well as the bigger implications of sociology, so I can see the potential for the stakes to, incredibly, get even higher. I've already put the third book on hold and am very eager to find where it goes!


  1. Bro- always fun to read these. I will state for the record that you are the *least* spoilery poster who uses warnings - if I pick this series up I genuinely don't know what is going to happen. :)

    1. Heh, excellent! If you do read it, I look forward to discussing with you. There's lots of fun ideas to chew over, and more than a few things that reminded me of Stellaris.