Death's End

by Cixin Liu

  “Before I explain to you the details of your task, I want you to understand one thing: Your highest priority is preventing the system from falling into the wrong hands. When you cannot ascertain the degree of risk with confidence, you should err on the side of destroying the transmission system—even if you should turn out to be mistaken. When you do decide to act, don’t worry about collateral damage. If necessary, destroying the entire ship would be acceptable.”

  Hunter was in the first duty cycle when Gravity left Earth. During those five years, he regularly took a certain kind of small blue pills. At the end of the duty cycle, when he was scheduled to go into hibernation, a physical revealed that he had cerebrovascular coagulation disorder, which was also called “no-hibernation disease.” Patients with this rare condition suffered no ill effects in daily life, but could not enter hibernation because the awakening process would cause massive brain damage. It was the only medical condition discovered so far that could prevent someone from going into hibernation. When the diagnosis was confirmed, everyone around Hunter looked at him as though they were at his funeral.

  Thus, throughout the whole voyage, Hunter had remained awake. Every time someone emerged from hibernation, they saw he had aged more. He told all the newly awakened the interesting things that had happened in the dozen or so years that had passed while they slept. The lowly cook became the most beloved figure on the ship, and he was popular with officers and enlisted men alike. Gradually, he turned into a symbol of the long voyage of Gravity. No one suspected that this easygoing, generous man held the same rank as the captain and was also the only man other than the captain with the authority and ability to destroy the ship in the event of a crisis.

  During the first thirty years of the journey, Hunter had several girlfriends. In this matter he held an advantage others did not possess: He could date women in different duty cycles, one after the other. But after a few decades, as Hunter became Old Hunter, the women, still young, treated him as only a friend with interesting stories.

  During this half century, the only woman Old Hunter ever truly loved was Reiko Akihara. But most of that time, more than ten million AU separated them. This was because Sublieutenant Akihara was aboard Blue Space, where she was a navigator.

  The hunt for Blue Space was the only undertaking where Earth and Trisolaris truly shared the same goal, because this lone ship heading into deep space was a threat to both worlds. During the Earth’s attempt to lure back the two ships that had survived the dark battles, Blue Space had learned the dark forest nature of the universe. If Blue Space someday mastered the ability to broadcast to the universe, the consequences would be unimaginable. The hunt thus received the total cooperation of Trisolaris. Before entering the blind region, the sophons had provided Gravity with a real-time, continuous view of the interior of the prey.

  Over the decades, Hunter was promoted from petty officer second class to petty officer first class, and then, as a special promotion, became a commissioned officer. Starting as an ensign, he was promoted all the way up to lieutenant. But even at the end, he never had the formal authorization to view the live feed of the interior of Blue Space transmitted by the sophons. However, he did possess the backdoor codes to all the ship’s systems, and he often viewed a palm-sized version of the video feed in his own cabin.

  He saw that Blue Space was a completely different society from Gravity. It was militaristic, authoritarian, and governed by strict codes of discipline. Everyone devoted their spiritual energy to the collective. The first time he saw Reiko was two years after the start of the chase. He was instantly smitten by this East Asian beauty. He would watch her for hours every day, and sometimes even thought he knew her life better than he knew his own. But a year later, Reiko went into hibernation, and the next time she woke up for duty was thirty years later. She was still young, but Hunter was already near sixty.

  On Christmas Eve, after a wild party, he returned to his cabin and brought up the live feed from Blue Space. The view began with a diagram of the complex overall structure of the ship. He tapped the location of the navigation center, and the view zoomed in to show Reiko on duty. She was looking at a large holographic star map, on which a bright red line traced the course of Blue Space. Behind it was a white line that almost coincided with the red line, indicating the path taken by Gravity. Hunter noticed that the white line deviated slightly from Gravity’s true course. Right now, the two ships were still a few thousand AU apart. At this distance, it was difficult to track a target as small as a spaceship with certainty. The white line probably only indicated their best guess, although the estimate of the distance between the two ships was pretty accurate.

  Hunter zoomed in some more. Reiko suddenly turned to face him, and, with a smile that made his heart clench, said, “Merry Christmas!” Hunter knew that Reiko wasn’t talking to him, but to all those hunting her ship. She was aware that she was being watched by sophons, though she couldn’t see her pursuers. Regardless, this was one of the happiest moments of Hunter’s life.

  Because the crew aboard Blue Space was large, Reiko’s duty cycle didn’t last long. One year later, she entered hibernation again. Hunter looked forward to the day he would meet Reiko face-to-face, when Gravity finally caught up to Blue Space. Sadly, he knew that he would be almost eighty by the time that happened. He hoped he would get to tell her he loved her and then watch as she was taken away for trial.

  For half a century, Hunter faithfully carried out his mission. He remained alert for any unusual conditions aboard the ship, preparing in his mind action plans for various crises. But the mission didn’t really put too much pressure on him. He knew that another form of insurance, utterly reliable, accompanied Gravity. Like many others, he often watched the droplets cruising at a distance from the portholes. But the droplets, in his eyes, held another meaning. If anything unusual occurred on Gravity, especially if there were signs of a mutiny or illegal attempts to seize control of the gravitational wave transmission system, he knew that the droplets would destroy this ship. They could move far faster than he—a droplet could accelerate from a few thousand meters away and reach a target in no more than five seconds.

  Now, Hunter’s mission was almost over. The degenerate matter vibrating string at the heart of the gravitational wave antenna, less than ten nanometers in diameter but running the entire length of the fifteen-hundred-meter hull, had almost reached its half-life. In another two months, the density of the string would fall below the minimum threshold for gravitational wave transmissions, and the system would fail completely. Gravity would turn from a broadcast station that posed a threat to two worlds to an ordinary stellar spaceship, and Hunter’s work would be done. He would reveal his true identity at that time. He was curious whether he would face admiration or condemnation from his crewmates. In any case, he would stop taking those blue pills, and his cerebrovascular coagulation disorder would disappear. He would enter hibernation and awaken on the Earth to live out the rest of his days in a new era. But he would hibernate only after seeing Reiko, which should happen soon.

  But then the sophons fell blind. During the voyage, he had imagined hundreds of possible crises, and this was one of the worst possibilities. The loss of the sophons meant that the droplets and Trisolaris no longer knew everything happening aboard Gravity. If the unexpected happened, the droplets could not react in time. This made the situation far more dangerous, and Hunter felt the weight on his shoulders increase tenfold, as though he had only started his mission.

  Hunter now paid even closer attention to happenings on the ship. The entire crew of Gravity had been awakened from hibernation, and that made monitoring difficult. But Hunter was the only member of the crew everyone was familiar with, and he was popular and had an abundance of social connections. Moreover, his easygoing manner and his insignificant post meant that most were not on guard in his presence. The enlisted men and junior officers, especially, told him things they wouldn’t dare say to senior officers or the psych corps. This all
owed Hunter to have a full grasp of the situation.

  After the sophons were blinded, strange things began to happen all over the ship: An ecological area in the middle of the ship was struck by a micrometeoroid; more than one person claimed to have seen openings suddenly appear in bulkheads, accompanied by the disappearance of certain objects that reappeared later, undamaged.…

  Out of all these oddities, the experience of Commander Devon, head of the MP, made the deepest impression on Hunter. Devon was one of the senior officers on the ship. Normally Hunter did not interact with them much. But when he saw Devon seek out the psychiatrist—whom most people on the ship avoided—he grew alert. Over a bottle of vintage whiskey, he finally got Devon to spill the story of his strange encounter.

  To be sure, other than the micrometeoroid strike, the most reasonable explanation for all the strange goings-on was that the crew was suffering from hallucinations. The loss of the sophons might have, in some unknown way, triggered a kind of mass mental disorder—at least that was how Dr. West and the psych corps explained it. Hunter’s duty did not allow him to accept this explanation easily; but other than hallucinations or a mass mental disorder, the strange stories told by the crew seemed impossible. However, Hunter’s mission was to respond to impossibilities that somehow became possible.

  Despite the massive antenna, the controller unit for the gravitational wave transmitter took up little space. Situated in a small spherical cabin at the stern, the controller was completely independent and not connected to the other parts of the ship. The spherical cabin was like a reinforced safe. No one aboard Gravity had the codes for entry, not even the captain. Only the Swordholder on Earth could activate the gravitational wave broadcast—in such an event, a beam of neutrinos would be transmitted to Gravity and switch on the transmitter. Right now, such a signal would take a year to arrive from the Earth.

  But if Gravity were hijacked, the safety measures around the spherical cabin would not last long.

  Hunter’s watch had a special button. When pressed, it would trigger a heat bomb inside the spherical cabin, which would vaporize everything inside. His job was very simple: No matter what the crisis, as soon as he judged the risk to be in excess of a certain threshold, he would press the button and destroy the controller, rendering the gravitational wave transmitter inoperable.

  In a sense, Hunter was an “Anti-Swordholder.”

  Hunter didn’t put all his trust in the button on his watch and the heat bomb in the cabin, which he had never laid eyes on. Ideally, he wanted to keep watch outside the control cabin day and night, but of course that would draw suspicion, and his hidden identity was his biggest advantage. Still, he wanted to be as close to the control cabin as possible, so he tried to regularly visit the astronomical observatory, also located at the stern. Since the entire crew was out of hibernation, Hunter had assistants to take care of his culinary duties, which gave him plenty of time to himself. In addition, as Dr. Guan Yifan was the only civilian scientist aboard and thus not subject to military discipline, no one thought it strange that Hunter often went to Guan to share the liquor that he was able to obtain due to his position. Dr. Guan, in turn, enjoyed the drinks, and lectured Hunter on the “universe’s three and three hundred thousand syndrome.” Soon, Hunter spent most of his time in the observatory, separated from the gravitational wave transmission controller by only a short corridor about twenty meters long.

  Hunter was on his way to the observatory again when he passed Guan Yifan and Dr. West heading for the bow of the ship. He decided that he would take a peek at the control cabin. When he was about ten meters away, the klaxons for the droplet attack started blaring. Due to his rank, the information window appearing before him displayed very few details, but he knew that the droplets were, at this time, farther away from the ship than when they had flown in formation. He had about ten to twenty seconds until impact.

  During these final moments, Old Hunter felt only relief and joy. No matter what happened next, he would have completed his mission. He looked forward not to death, but to his victory.

  This was why, half a minute later, when the klaxons stopped, Hunter became the only one aboard who felt no relief from his extreme terror. The cessation of the alarm indicated, for him, great danger: In a situation of great uncertainty, the gravitational wave transmitter was still intact. Without hesitation, he pressed the button on his watch.

  Nothing happened. Even though the control cabin was tightly sealed, he should have been able to feel the tremors from the detonation. A line of text appeared on his wristwatch display:

  Failure: The self-destruct module has been dismantled.

  Hunter wasn’t even surprised. He had already intuitively anticipated that the worst had happened. He had been but a few seconds from relief, but the relief would never come.

  * * *

  Neither droplet struck their respective targets. Both brushed by Gravity or Blue Space at extremely close range—only a few tens of meters.

  Three minutes after the attack alert was lifted, Joseph Morovich, captain of Gravity, finally managed to gather his senior staff at the combat center, in the middle of which was a giant situation map. No stars were shown against the dark expanse of space, only the positions of the two ships and the attack trajectories of the droplets. The two long white trails appeared as straight lines, but the data indicated they were parabolas with very low curvature. As the two droplets accelerated toward their targets in the simulation, their headings began to drift. The changes were small, but cumulatively, they resulted in the droplets barely missing their targets. Many of the senior officers had participated in the Doomsday Battle, and their memory of the sharp turns the droplets were capable of executing while moving at extremely high velocities still brought heart-stopping terror. However, the trajectories on the display were completely different: It was as though some outside force perpendicular to the attack vectors of the droplets had steadily pushed them out of the way.

  “Replay the recording,” the captain ordered. “Visible light range.”

  The stars and the galaxy appeared. This was no longer a computer simulation. In one corner, flickering numbers showed the passage of time. Everyone relived the terror of a few minutes ago, when all they could do was wait for death because evasive maneuvers and defensive shots were all meaningless. Soon, the numbers stopped changing. The droplets had already swept past the ships, but because they were moving so fast, no one could see them.

  The display shifted to slow-motion replay of the high-speed recording. Since the complete recording, over ten seconds long, would take a long time to play through, only the last few seconds were shown. The officers saw a droplet pass in front of the camera like a faint meteor across the sea of stars in the background. The recording was played again, and froze when the droplet was in the middle of the screen. The image zoomed in until the droplet took up most of the display.

  Half a century of cruising in formation with the droplets made everyone familiar with their appearance, and what they saw now shocked them. The droplet on the display was still shaped like a teardrop, but its surface was no longer a perfectly smooth mirror. Instead, it was dim and coppery yellow, as though full of rust. It was as if a magician’s spell of eternal youth had failed, and the marks left by three centuries of spaceflight had all appeared at once. Instead of a shining spirit, the droplet had turned into an ancient artillery shell drifting through space. Communications with the Earth during the last few years had given these officers some basic insight into the principles of strong-interaction materials. They knew that the surface of a droplet was held in a force field generated by mechanisms inside. This force field counteracted the electromagnetic force between particles, allowing the strong nuclear force to spill out. Without the force field, strong-interaction material reverted to ordinary metal.

  The droplets had died.

  Next, they reviewed the post-attack data. The simulation showed that after the droplet brushed by Gravity, the mysterious perpendicular
force making small heading changes vanished, and the droplet coasted along its final vector. But this only lasted a few seconds. Thereafter, the droplet began to decelerate. The combat analysis computer concluded that the force decelerating the droplet was equal in magnitude to the force that had changed its heading. The obvious conclusion was that the source of the force had shifted from pushing at the side of the droplet to pushing from the front.

  Since the recording was made by high-magnification telescopic lens, it was possible to see the back of the departing droplet. The droplet turned ninety degrees so that it was perpendicular to its own direction of motion and continued to coast. Then it began to decelerate. The next scene seemed to be taken from a fairy tale—good thing Dr. West was also present, or else he would again declare the others to be suffering from hallucinations. A triangular object, about twice as long as the droplet, appeared in front of it. The staff immediately recognized it as a shuttle from Blue Space! In order to increase its propulsive power, multiple small fusion drives were attached to the hull of the shuttle. Although the nozzles of the drives all pointed away from the camera, it was still possible to see the glow they made as they operated under maximum output. The shuttle was pushing against the droplet to slow it down. And it was easy to deduce that it was also the source of the force that caused the droplets to deviate from their attack vectors.

  After the shuttle’s appearance, two human figures wearing space suits appeared on the other side of the droplet—the side closest to the camera. The deceleration caused the figures to stick to the surface of the droplet; one of them held some kind of instrument in his hands and appeared to be analyzing the droplet. In the past, droplets had seemed almost divine in the eyes of humankind, not belonging to this world and not approachable. The only people who had ever come close to touching a droplet had been vaporized in the Doomsday Battle. But now, the droplet had lost all its mystery. Without its mirrorlike sheen, it seemed ordinary, broken-down, older and less advanced than the shuttle and the astronauts—some antique or piece of trash collected by the latter. A few seconds later, the shuttle and the astronauts disappeared, and the dead droplet was once again alone in space. But it continued to decelerate, indicating that the shuttle was still there pushing against it, only now invisible.