
The final book in the The Three Body Problem trilogy….
It remains to be seen how closely the Netflix series follows this final book in the Three Body Problem trilogy as the series has not gotten to any of the storyline in this book as of the time of this writing. This book starts where The Dark Forest leaves off, with humanity and the Trisolarians in a truce mitigated by the threat of mutually assured destruction. With Luo Ji (in the book), Saul Durand, in the series, as the former Wallfacer and current swordholder maintaining the balance of power as he approaches nearly a century of life. Earth has determined, that due to Luo Ji’s age, he needs to be replaced. Humanity has softened mightily since he has taken over. Life has been, perhaps, too good. Humanity chooses a kinder, gentler swordholder in Cheng Xin.

Yun Tianming and Cheng Xin or Will Downing, portrayed by Actor Alex Sharp and Jin Cheng, portrayed by actor Jess Hong in the Netflix series
The very instant she assumes her duties, the Trisolarians begin their attack. They anticipate that there will be a moment of hesitation on her part and move quickly to disable any transmissions of the coordinates of Earth or Trisolaris beyond the solar system. They then begin their plan to overtake Earth. They force all the people of Earth to either Australia or a small colony on Mars. The majority of Earth’s population moves to Australia. Conditions are brutal, but survivable. The Trisolarians then mandate that there shall be no electricity. Providing the resources for billions of people on just one continent is only possible with electricity. Obviously, in the scramble for resources, chaos ensues. Fortunately, one of the starships that fled during the Trisolarian attack many years earlier, makes a transmission of Earth’s and the Trisolarian’s coordinates, thus making Earth undesirable for inhabiting as it will eventually be targeted for destruction by some receiver of the coordinates. All plans for Trisolarians to inhabit Earth are abandoned. The only trace of the Trisolarians to remain is a robotic humanoid named Sophon. She allows humans to maintain contact with Trisolarians through her.
This is how Cheng Xin learns that the brain that belonged to the cancer-ridden Yun Tianming that was launched via coordinated nuclear explosions (aka The Staircase Project) actually made it to the Trisolarian fleet where they were able to re-animate him back to human form from just his brain. After his brain was launched Cheng Xin had learned that Yun Tianming spent a $20 million fortune he had inherited on buying a star for her. They had been classmates in college and remained friendly afterwards, but Cheng Xin had no idea Yun Tianming was in love with her. An arrangement is made through Sophon for Cheng Xin to communicate with Yun Tianming, although with great restrictions. If any information is passed between the two that the Trisolarians deem undesirable, Cheng Xin will be instantly killed. Yun Tianming transmits information in the form of fairy tales he has fabricated. They had become popular with Trisolarian society, but Yun Tianming had written some of them with secret messages that divulge Trisolarian technology such as light speed ships. They also make an agreement that they will meet in the solar system that Yun Tianming bought Cheng Xin if they are ever able.
Cheng Xin then goes into hibernation for over 50 years shortly after the conversation, just as Earth is on the verge of being destroyed by an unknown civilization. The weapon used resembles a sheet of paper that is capable of traveling at nearly light speed and collapsing three dimensions into two. The collapse of dimensions presumably kills everything within. It is later learned that this weapon will likely turn the entire universe into two dimensions. The civilization that wielded this weapon is presumed to have figured out a way to sustain their own existence in two dimensions.
Eventually, most of humanity is wiped out, with the exception of Cheng Xin, her friend AA (No explanation is given for this weird name in the book), and a small group of others from the two ships that fled from the original Trisolarian attack. Chen Xin and AA just happened to be traveling in one of the few space curvature-drive ships that humans had created and are able to escape the paper-like weapon. They end up in the solar system that Yun Tianming bought for Cheng Xin. AA winds up on a planet with Yun Tianming and Chen Xing on a ship with an astronomer named Guan Yifan, who was part of the crew of the ship that transmitted the Earth’s coordinates and stopped the Trisolarian takeover. Cheng Xin and Guan Yifan end up in a mini 1 km³ universe that Yun Tianming has created for Cheng Xin to ride out the end of their original universe. She is there with Guan Yifan and Sophon. There is no time in this universe as millions of years pass outside.
It is believed that the universe will eventually reset itself and start over, but will require all of its original matter to do so. They end up emptying the contents of their mini-universe back into the regular universe and take their chances with fate. In the end, Romeo and Juliet (Yun Tianming and Cheng Xin) are never reunited and it looks as if life is headed back to the Garden of Eden.
This is a very long and detailed book. It describes all sorts of worlds, theories, and technologies that will probably make for a great tv series. This book, however seemed to go a little to deep into the weeds with this stuff for the second half of the book. I found myself losing interest in the technological and descriptive details and wondering what is going to happen to the characters? I am an engineer saying this, this book went deep enough into the scientific and theoretical weeds to almost lose me. This is probably more than most readers want from their science fiction. In the end, we are never really certain of much, except that Cheng Xin is likely one of the last humans to exist and that the inhabitants of the universe are most likely doomed to destroy it.
Thinking about this series of three books, it strikes me really odd that the author was able to write nearly 1400 pages about an alien invasion and never physically describe an alien. He addresses their intelligence, culture, and technology, but never once is there any sort of physical description, other than that they can be dehydrated into hibernation and rehydrated back to life. I am not sure how he pulled this off. Perhaps the author never revealed an alien so that God could, perhaps, be the mystical force cleansing the universe and bringing it back to Eden?

















