Death's End

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Death's End

United States edition cover
Author	Liu Cixin
Original title	死神永生
Translator	Ken Liu
Language	Chinese
Series	Remembrance of Earth's Past
Genre	Science fiction, Hard science fiction
Publication date	2010
Publication place	China
Pages	592[1]
ISBN	978-0765377104
Preceded by	The Dark Forest

Death's End (Chinese: 死神永生) is a science fiction novel by the Chinese writer Liu Cixin. It is the third novel in the trilogy titled Remembrance of Earth's Past, following the Hugo Award-winning novel The Three-Body Problem and its sequel, The Dark Forest. The original Chinese version was published in 2010. Ken Liu translated the English edition in 2016.^[2] It was a finalist for the 2017 Hugo Award for Best Novel and winner of the 2017 Locus Award for Best Science Fiction Novel.

During the Fall of Constantinople in AD 1453, a prostitute gains the ability to retrieve small objects in seemingly impossible ways, up to and including the vital organs of heavily guarded human targets. Constantine XI tasks her with killing Mehmed II, but her powers mysteriously vanish, and she is executed. These events are attributed to the passage of a "four-dimensional fragment" through the solar system.

An aeronautical engineer named Cheng Xin is recruited by the Planetary Intelligence Agency (PIA) to work on the Staircase Project, an attempt to launch a probe toward the Trisolaran fleet to gather intelligence. The seemingly impossible goal of accelerating the probe to 1% of lightspeed is realized through her idea of lining up ICBMs, Topol and Dongfeng missiles to launch the probe using nuclear pulse propulsion. The Planetary Defence Council (PDC) at first rejects the plan because of the high intercept speed and the unlikelihood of being able to surveil Trisolaran communications. Thomas Wade, the CIA agent leading the project, proposes making the probe desirable to Trisolaris by putting a live human on board, who would then act as a double agent after being integrated into the fleet. However, the mass of the vehicle is limited to only a few kilograms, so Wade decides to find a volunteer to be euthanized and send only their brain, on the assumption that the Trisolarans will be willing and able to reconstruct their body.

One of Cheng Xin's acquaintances, an engineer named Yun Tianming who has always held a secret affection for her, discovers that he is terminally ill. Upon receiving an unexpected sum of money, he buys the title deed to the distant star DX3906 from the United Nations and anonymously gifts it to Cheng. When Cheng learns of Yun's illness, she persuades him to volunteer for the Staircase Project; he is selected as the subject and his brain is extracted and launched. A malfunction causes the spacecraft to go off course into deep space and the project is written off as a failure. After learning that Yun was the source of the star title, Cheng enters hibernation, in order to serve as the Staircase Project's liaison for future generations.

The Trisolaran invasion has been forestalled by Luo Ji's creation of Dark Forest Deterrence, which threatens Mutually Assured Destruction (MAD) by broadcasting Trisolaris's location across the universe to bring it to the attention of hostile alien civilizations, although this would give away Earth's location as well. The deterrence is enforced by a system of gravitational-wave transmitters distributed across Earth and mounted on some spacecraft. The person who bears sole responsibility for activating the system in the event of Trisolaran aggression is designated Swordholder; Luo Ji is the first holder of the position.

The deserting ships Bronze Age and Blue Space are invited to return to the solar system. Bronze Age arrives first, but the UN puts its crew on trial for crimes against humanity. Its commander manages to warn Blue Space not to return before his execution; the stellar warship Gravity, which is equipped with a deterrent transmitter, and two Trisolaran droplets set off in pursuit.

Fifty years pass. Cheng is woken from hibernation due to her possession of DX3906, which has been discovered to have planets by an astronomer named AA. Cheng and AA start an aerospace company together, to exploit the planets in the distant future.

Luo Ji is preparing to retire as Swordholder and the UN is seeking replacements; Cheng becomes the leading candidate. Wade, who has also hibernated, desires the position and attempts to murder her, but fails and is given a long prison sentence. Cheng is selected to succeed Luo, but the moment the handover occurs, Trisolaris begins an attack against Earth. They have correctly predicted that Cheng will be unwilling to activate the system and doom two civilizations, and all the deterrence system components remaining in the solar system are destroyed.

The Trisolarans, through their ambassador Sophon, relocate all of humanity to Australia, where they are forced to live under appalling conditions intended to rapidly shrink the population. However, in deep space, Blue Space has discovered another four-dimensional fragment; its crew learns to navigate the fourth dimension and uses that ability to disable the two droplets and capture Gravity. They use Gravity's transmitter to send the MAD broadcast, then resolve not to return to the solar system. Upon detecting the broadcast, the Trisolarans abandon their invasion and flee the solar system.

One of Trisolaris's three suns is struck by a relativistic "photoid" launched by unspecified aliens, destroying both it and the Trisolaran homeworld. It is understood that sooner or later, the Solar System will suffer a similar attack.

The Trisolarans reveal that they have a fully reconstituted Yun Tianming in their custody, and allow him and Cheng to meet over a sophon-mediated audiovisual link. The conversation is closely monitored to avoid intelligence disclosures, so Yun tells Cheng three elaborate fairy tales, carefully composed to communicate key scientific concepts through metaphor and subtext. Yun invites Cheng to meet him on one of her planets before the link is broken.

The first fairy tale is never decoded even after great effort, and the UN eventually gives up the attempt. The second tale explains that it is possible to reduce the speed of light in a region of space. This would signal to the galaxy at large that Earth is harmless and need not be destroyed, at the cost of trapping human civilization inside a "black domain" forever. The third tale explains that lightspeed travel may be accomplished by manipulating the local curvature of spacetime, using the analogy of soap reducing the surface tension of water.

Humanity decides to construct space colonies in the shadow of the solar system's gas giants, where they could survive the destruction of the sun by photoid attack. Virtually everyone evacuates from the Earth. Lightspeed travel research is banned after it comes to be seen by the population as an escape hatch for the ultra-wealthy, who could use relativistic time dilation to cheat death; it is also discovered that using it leaves permanent traces on spacetime. Wade, who by now has been released from prison, asks Cheng to transfer her considerable personal wealth to him to finance a secret lightspeed research project; she assents after extracting a promise that he will return the wealth and shut down the program at her request.

Cheng hibernates for sixty years, and is woken when Wade's program is discovered by the government. The technology works and provides very promising research in other fields, but Wade has also created a private army equipped with potentially devastating antimatter weaponry. Horrified by this, Cheng invokes the promise, and Wade surrenders. However, the government shows no mercy to Wade, and executes him, prompting Cheng to return to hibernate with AA until the alien strike comes.

60 years later, the solar system is attacked with a spacetime anomaly that causes the third dimension to collapse into the second; humanity has no defense against this and will be rendered extinct within days. The existence of such weapons was the secret of Yun's first fairy tale; it is later explained that using such a weapon was a gesture of respect by the attacker as they considered humanity a powerful and dangerous enemy. The only way to survive is either to flee at light speed, or find a way to live in the 2D plane; neither appears a realistic possiblity. Cheng and AA fly on one of their corporation's private spacecraft to Pluto, where they meet Luo Ji, who gives them a number of artifacts from the Museum of Humanity. He then reveals that their ship is equipped with a lightspeed drive, built in secret by Wade's associates after his death. Luo Ji instructs them to escape the solar system while he stays behind. They set a course for DX3906. As they leave all of the solar system is pulled into the second dimension and flattened, ending human civilization.

Cheng Xin and AA arrive at DX3906 286 years later. They discover that the system has two planets, which they name Planet Blue and Planet Gray. There, they encounter Guan Yifan, a civilian cosmologist of Gravity, who explains that the crew of his ship and Blue Space went on to develop curvature propulsion and founded an interstellar society.

Cheng Xin and Guan Yifan fly to the nearby Planet Gray to investigate signs of alien activity. They discover a series of Death Lines, the seed elements of a black domain, which have been laid down by the aliens in order to hasten the end of the universe. Guan Yifan explains that endless interstellar warfare using curvature- and dimension-based weaponry is degrading the entire universe. In its youth, the universe possessed ten dimensions, and the speed of light was near infinity, but as time went on, galactic civilizations in conflict would collapse regions of space into lower dimensions, forcing each other to permanently migrate there while the higher dimensions ceased to exist entirely. At the same time, the widespread use of black domains resulted in the speed of light permanently lowering throughout the universe, until it degenerated to three dimensions and the current value of c.

As Cheng Xin and Guan Yifan fly back to Planet Blue, they are notified by AA that Yun Tianming has arrived. Cheng is overjoyed that they will finally reunite. However, the activity of Yun's curvature drive triggers the death lines, converting the system into a black domain with a lightspeed only marginally above their current orbital velocity. They hibernate to survive the time necessary to adapt their spacecraft to functioning in this environment; once the process completes they realize that 18 million years have passed in an external frame of reference. Upon descending to Planet Blue, they find a message revealing that AA and Yun Tianming lived a happy life together, and have left Cheng and Guan a gift: a portal to a pocket universe, made with Trisolaran technology, containing one cubic kilometer of idyllic farmstead. They enter the universe, meet with Sophon, who was already living there, and wait outside of time for the main universe to die and be reborn in a Big Bounce.

After living there for some time, Cheng Xin and Guan Yifan receive an alien message aimed at all denizens of micro-universes in all languages including Earth's and Trisolaran's, stating that the presence of micro-universes deprives the main universe of mass, disrupting its cycle of expansion, collapse and rebirth. Cheng Xin, accompanied by Yifan, wearily reflects on her lifetime of moral duty. They decide to disassemble the contents of the micro-universe and return the mass to the main universe, then join it in death and rebirth. They leave behind a message in a bottle and a self-sustaining terrarium for the denizens of the reborn universe to uncover.

• Cheng Xin (程心) – Aerospace engineer from the early 21st century, second Swordholder
• Yun Tianming (云天明) – Cheng Xin's university classmate who has a romantic interest in her; his brain is sent into space and captured by the Trisolaran fleet, who manage to clone his body and return him to life.
• Thomas Wade (托马斯·维德) – Former CIA Chief, most effective candidate for Swordholder, develops curvature propulsion prototype.
• Ai AA (艾AA) – Ph.D. in astronomy from the Deterrence Era, Cheng Xin's friend and traveling companion
• Luo Ji (罗辑) – Cosmic Sociologist, first Sword-holder
• Neil Scott – Captain of Bronze Age
• Sebastian Schneider – Lieutenant commander of targeting systems and attack patterns aboard Bronze Age
• Captain Morovich – Captain of Gravity
• Chu Yan – Captain of Blue Space
• Sophon (智子) — Trisolaran android, controlled by sophons, who provides a diplomatic and communicative link between Earth and Trisolaris
• Guan Yifan (关一帆) – A civilian astronomer from Gravity
• Yang Dong (杨冬) – String theorist and daughter of Ye Wenjie and Yang Weining, later committed suicide
• Fraisse (弗赖斯) – Australian Aboriginal man who befriends Cheng Xin during the resettlement
• Singer – The exterminator on board an observing ship, attacking the Solar System with dual-vector foil.

The additional books in the Remembrance of Earth's Past trilogy are:^[3]

• 三体 (The Three-Body Problem), 2008; English translation by Ken Liu published by Tor Books in 2014
• 黑暗森林 (The Dark Forest), 2008; English translation by Joel Martinsen published by Tor Books in 2015

• Official website