Book Review: The Dark Forest by Cixin Liu

The Dark Forest (黑暗森林), by Cixin Liu, is the second book in the Remembrance of Earth’s Past series and is translated from Chinese by Joel Martinsen. This is the sequel to the 2015 Hugo-award winning novel, The Three Body Problem, which received an enormous amount of well-deserved praise. The Dark Forest is no different; it is an absolutely excellent sci-fi story that I recommend checking out.

Note that this post has significant spoilers for the first book in the series (The Three Body Problem). If you haven't read that yet, stop here. Otherwise I try to avoid spoilers from book two in this review.

Overall Impression
This was an excellent second book in the Remembrance of Earth’s Past series (more commonly just called by its first book: The Three Body Problem). The focus is heavily on the plot as humanity, represented by key individuals who serve as main characters, prepares for the inevitable arrival of the alien invasion fleet. It's very cool how the author spans the story over several centuries allowing us to glimpse how technology and human culture changes in that time without having to detail all of future human history. The story starts a bit slower than it's predecessor, but it ramps up quickly to an exciting and unexpected conclusion.

Plot
The plot is probably where the book shines best as this is a hard science fiction tale where the events and concepts take center stage. The story starts right at the end of The Three Body Problem and the dawn of the "Crisis Era" as humanity prepares for their inevitable confrontation with the Trisolarian invasion fleet. It will take four hundred years for the fleet to arrive so humanity has time to prepare. However, they are under technological lockdown and it is unclear how much they will be able to accomplish in that time.

The story is told through three parts. Given the large timespan covered in the novel (ie, centuries), this is done to break up the story so that meaningful character interactions can happen. Without spoiling much, the main focus of the novel is the Wallfacer Project, which is a desperate attempt by humanity to come up with strategies to use against the Trisolarians. These are kept secret in the Wallfacer's mind in order to prevent spying, which also allows the reader to attempt to decipher the plans before they are revealed. In terms of pacing, the story starts a bit slow, particularly in comparison to the prior novel. However, by the end the pacing is really fast and makes the book very hard to put down.

Characters
There are several memorable characters in the story, such as Luo Ji, Shi Qiang, and Zhang Behai. Numerous other secondary characters also have important roles to play; however, like it's predecessor, The Dark Forest is more about the overall story rather than individual characters. Still, their individual story arcs are interesting enough and, especially for the main ones, you want to keep reading to find out what they end up doing. Although some parts of the story are told as though from an omniscient narrator or by dialogue with people familiar with history, most of the time we see the world through the eyes of these select few characters giving a more personal feel to the large timespan and epic scope of the novel.

Setting / World Building
As the first novel established, humanity is not alone in the universe. The closest star system to us, Alpha Centauri, is home to the Trisolarians. In the events of the first book, we learn how humanity discovered them and how they subsequently launched a fleet to destroy us. Given the astronomical distances between stars, this would take over 400 years. In the meantime, the Trisolarians have used their sophons to block technological progress and this sets the background of The Dark Forest.

In this novel, we get to see how the Earth changes over time as humans focus heavily on research and space technologies, sometimes at the expense of other necessities in life. We eventually get to see some very advanced technology, but we feel the ever present threat that despite all this, the Trisolarians are still far ahead. I won't say much more, as it is best to experience the novel and see how the author paints the story.

There are a few scientific inaccuracies throughout the text, though they don't really affect the story. For example, there's a mention that for fun the astronomers had pointed their space telescope to get images of themselves on the Earth, which is technically impossible. There's also inaccuracies about the nature of Alpha Centauri and how bright Jupiter actually is. Finally, something the author probably didn't anticipate, is the mention that several decades into the Crisis Era (think of it as the very near future), there are over two hundred planetary systems know. In actuality, there are nearly two thousand planets known today, a number that will only go up as time progresses.

Final Thoughts
This was an excellent novel and a must-read for fans of classic science fiction. I was reminded of several of Arthur C. Clarke's novels and even of Sphere by Michael Crichton. The plot was a little slow at the beginning, particularly in comparison with The Three Body Problem. However, this does pick up and by the end it is rushing ahead getting cooler and cooler with each turn of the (digital) page. The characters are also pretty neat and provide a personal touch across the large timespan covered in the story. I eagerly await the translation of the third and final installment of this series.