Death’s End is the finale of The Remembrance of Earth’s Past. The series begins with humans encountering a belligerent alien species from a neighboring star system, but the scale of humans’ conflict increases exponentially each each book.
Liu’s universe is always kinetic. Characters’ decisions cascade through hundreds of years of human history and — with hibernation as a plot device — they see the consequences of their decisions in the flesh.
In the third book, the primary such character is Cheng, an aerospace engineer. She’s the technical lead of a government program to shoot a human brain towards the approaching Trisolarian civilization. After firing one off, she hibernates for 300 years to a point in time where humans and the Trisolarian race are in a stand-off. Humans are threatening to alert the universe to their existence through gravitational waves, effectively committing suicide, if the Trisolarian force infiltrates Earth.
Cheng is elected “Swordholder”, chief negotiating officer, but the Trisolarian force deems her weak and immediately attacks Earth. Only through a deus ex machina do humans frighten the Trisolarian fleet away with gravitational waves. In other words, humans choose the devil they don’t know.
Liu so deftly weaves world building with philosophy and cosmology that it is easy to forget that he’s writing fiction. Liu captures primitive urges — survival, improvement, expansion — and constructs from them an organic hologram of our Solar System, Milky Way, and universe. In that universe, humans grapple for meaning and policy amongst external, warring alien civilizations. More than mere fiction, it feels like Liu is predicting with how humanity will adapt and react to interstellar technology.
And I have faith in Liu’s interpretation of humanity at large. Humans cycle between timidity, overoptimism, strength, resignation, enlightenment, and ignorance. Governments oscillate between fascism, libertarianism, and democracy. Innovation is both publicly and privately funded and the characters’ allegiance is divided between their family, government, and species.
On the cosmic scale, Liu questions whether the universe’s natural “forces” are natural at all. He suggests that dimensions and Lightspeed are weapons that God-tier civilizations utilize in their wars with one another. For example, a civilization might transform itself from a 4D to a 3D species before vaporizing their 4D world and their enemies within it. In Liu’s universe, war is the only constant.
The book has spirituality and philosophy that’s unmatched in both prior books. Cheng, in an inter-dimensional time capsule, creates a memoir of humanity that, in a twist, is revealed to be the source material for many of the series’ earlier chapters. And ultimately she risks her life. She and countless like her leave their inter-dimensional time capsules so the universe has enough mass to collapse into a Big Crunch.
So Cheng resolves The Remembrance of Earth’s Past on a note of sacrifice. Life to Liu is a struggle for survival and power, but Liu’s protagonist gives that up for the motherly creation of a new universe she will never meet. In Liu’s universe, life reveals itself as a force that acts across form and time.