Death's End

by Cixin Liu

  Not long ago on Pluto, Cheng Xin had experienced one of the most relaxed moments of her life. Indeed, it was easy to face the end of the world: All responsibilities were gone, as were all worries and anxieties. Life was as simple and pure as the moment when one first emerged from the mother’s womb. Cheng Xin just had to wait in peace for her poetic, artistic end, for her moment to join the giant painting of the Solar System.

  But now, everything had been turned upside down. Early cosmology had presented a paradox: If the universe was infinite, then every spot in the universe would feel the cumulative effects of the infinite gravity exerted by an infinity of celestial bodies. Cheng Xin really did feel an infinite gravity now. The power came from every corner of the universe, ruthlessly tearing at her soul. The horror of her last moments as the Swordholder 127 years ago resurfaced as four billion years of history pressed down on her and suffocated her. The sky was full of eyes staring at her: the eyes of dinosaurs, trilobites, ants, birds, butterflies, bacteria … just the number of men and women who had lived on the Earth possessed a hundred billion pairs of eyes.

  Cheng Xin saw AA’s eyes, and understood the words in her gaze: You’ve finally experienced something worse than death.

  Cheng Xin knew that she had no choice but to live on. She and AA were the last two survivors of human civilization. Her death would mean the death of half of all that was left of humanity. Living on was the appropriate punishment for her mistake.

  But the course ahead was a blank. In her heart, space was no longer black, but colorless. What was the point of going anywhere?

  “Where should we go?” Cheng Xin muttered.

  “Go find them,” Luo Ji said. His image was even more blurred and now only black and white.

  His words illuminated Cheng Xin’s dark thoughts like lightning. She and AA looked at each other and immediately understood who “them” meant.

  Luo Ji continued, “They’re still alive. The Bunker World received a gravitational wave transmission from them five years ago. It was a short message, and didn’t explain where they were. Halo will periodically hail them with gravitational waves. Maybe you’ll find them; maybe they’ll find you.”

  Luo Ji’s black-and-white image disappeared as well, but they could still hear his voice. He said one last thing, “Ah, it’s time for me to go into the picture. Safe travels, children.”

  The transmission from Pluto was cut off.

  On the monitor, they could see Pluto light up and expand in two dimensions. The part of Pluto containing the museum was the first to touch the plane.

  The Doppler effect of Halo’s speed was now visible. The light from the stars ahead shifted to bluish, while the light from the stars behind shifted to reddish. The color shift was apparent in the two-dimensional Solar System.

  Outside, no other fleeing spaceships could be seen; Halo had passed them all. All the fleeing spaceships were now falling onto the two-dimensional space like drops of rain against glass.

  Very few transmissions could now be received from the direction of the Solar System. Due to the Doppler effect, the brief bursts of voices sounded strange, like singing.

  “We’re very close! Are you behind us?” … “Don’t do this! No!” … “There’s no pain. I’m telling you, it’ll be over in a flash.” … “You still don’t believe me, after all this? Fine, don’t believe me.” … “Yes, sweetie, we’ll become very thin.” … “Come here! We should be together.”

  Cheng Xin and AA listened. The voices became fewer and fewer, and separated by longer gaps. After thirty minutes, they heard the last voice coming out of the Solar System:

  “Ahhhhhhhhh—”

  The voice was cut off. The giant painting called the Solar System was complete.

  Halo continued to fall toward the plane. The speed it had already achieved was slowing down its fall, but the ship still hadn’t achieved escape velocity. By now, Halo was the only man-made three-dimensional object in the Solar System, and Cheng Xin and AA were the only people not in the painting. Halo was very close to the plane, and from this angle, looking at the two-dimensional Sun was like looking at the sea from shore: the dim, dark red surface stretched into the distance without bounds. The freshly flattened Pluto was now very large, and still expanded at a rate that was visible to the naked eye. Cheng Xin examined the exquisite “tree rings” of Pluto and tried to find traces of the museum, but she couldn’t see anything—it was too small. The giant waterfall that was three-dimensional space tumbling into the flat plane seemed inexorable. Cheng Xin began to doubt whether the curvature propulsion engine really was capable of propelling the ship to lightspeed. She hoped for everything to be over.

  But then, the ship’s AI spoke.

  “Halo will enter lightspeed in one hundred and eighty seconds. Please select a destination.”

  “We don’t know where to go,” said AA.

  “You can select a destination after we’ve entered lightspeed. However, you won’t subjectively be spending much time in lightspeed, and it’s easy to overshoot your destination. It’s best if you select it now.”

  “We don’t know where to find them,” Cheng Xin said. Their existence gave the future some light, but she still felt lost.

  AA clutched Cheng Xin’s hands. “Have you forgotten? Other than them, he also exists in the universe.”

  Yes, he still exists. Cheng Xin was overwhelmed by heartache. She had never yearned to see anyone as much as him.

  “You have a date,” AA said.

  “Yes, we have a date,” Cheng Xin repeated mechanically. The torrents of emotion left her numb.

  “Then let’s go to your star.”

  “Yes, let’s go to our star!” Cheng Xin turned to the ship’s AI. “Can you find DX3906? That was the assigned number back at the beginning of the Crisis Era.”

  “Yes. The star is now numbered S74390E2. Please confirm.”

  A large holographic star map appeared before them. It showed everything within five hundred light-years of the Solar System. One of the stars glowed bright red, and a white arrow pointed at it. Cheng Xin was very familiar with it.

  “That’s the one. Let’s go there.”

  “Course set and confirmed. Halo will enter lightspeed in fifty seconds.”

  The holographic star map disappeared. In fact, the ship’s entire hull disappeared, and Cheng Xin and AA seemed to be floating in space itself. The AI had never employed this display mode before. In front of them was the starry sea that was the Milky Way, which was now pure blue, reminding them of the real sea. Behind them was the two-dimensional Solar System, suffused with a bloody red.

  The universe shuddered and transformed. All the stars in front of them shot straight ahead, as though that half of the universe had transformed into a black bowl and all the stars were falling into the bottom. They clustered ahead of the ship and fused into a single glow, like a giant sapphire in which it was not possible to distinguish individual stars. From time to time, individual stars shot out of the sapphire and swept past the pure black space to fall behind the ship, changing color the whole way: from blue to green, then yellow, and turning red once they were behind the ship. Looking back from the ship, the two-dimensional Solar System and the stars fused into a red ball like a campfire at the end of the universe.

  Halo flew at the speed of light toward the star that Yun Tianming had given Cheng Xin.

  PART VI

  Galaxy Era, Year 409

  Our Star

  Halo shut off the curvature engine and coasted at lightspeed.

  During the voyage, AA tried to comfort Cheng Xin, even though she knew this was a hopeless task.

  “It’s ridiculous for you to blame yourself for the destruction of the Solar System. Who do you think you are? Do you think if you stand on your hands, you’ve lifted the Earth? Even if you hadn’t stopped Wade, the outcome of that war would have been hard to predict.

  “Could Halo City really have achieved independence? Even Wade couldn’t be certain of that. Could the
Federation Government and Fleet really have been scared of a few antimatter bullets? Maybe Halo City could have destroyed a few warships, or even a space city, but ultimately, Halo City would have been exterminated by the Federation Fleet. And in that version of history, there would be no Mercury base, no second chance.

  “Even if Halo City had managed to achieve independence, continued to research curvature propulsion, discovered the slowing effects of the trails, and finally collaborated with the Federation Government to build more than a thousand lightspeed ships in time, do you think people would have agreed to build the black domain? Remember how confident people were that the Bunker World would survive a dark forest strike—why would they have agreed to isolate themselves in the black domain?”

  AA’s words slid across Cheng Xin’s thoughts like drops of water across a lily pad, leaving no trace. Cheng Xin’s only thought was to find Yun Tianming and tell him everything. In her mind, a journey of 287 light-years would take a long time, but the ship’s AI informed her that the trip would only take fifty-two hours in the ship’s frame of reference. Everything felt unreal to Cheng Xin, as though she had already died and gone to another world.

  Cheng Xin spent a long time gazing out of the portholes at space. She understood that each time a star leapt out of the blue cluster in front, swept past the ship, and joined the red cluster behind the ship, it meant that Halo had passed it. She counted the stars and watched as they turned from blue to red—the sight was hypnotic. Eventually, she fell asleep.

  By the time Cheng Xin awakened, Halo was close to its destination. It turned 180 degrees and activated the curvature engine for deceleration—in fact, the ship was pushing against its own trail. As the ship decelerated, the blue and red clusters began to spread out like two clusters of exploding fireworks, and soon evolved into a sea of stars distributed evenly around the ship. The slowing down of the ship also gradually erased the red and blue shifts. Cheng Xin and AA saw that the Milky Way ahead of them still looked about the same, but behind them, none of the stars looked familiar. The Solar System was long gone.

  “We’re now two hundred eighty-six point five light-years from the Solar System,” said the ship’s AI.

  “So two hundred eighty-six years has already passed back there?” AA asked. She looked as if she had just awakened from a dream.

  “Yes, if you are using their frame of reference.”

  Cheng Xin sighed. For the Solar System in its current condition, was there a difference between 286 years and 2.86 million years? But she thought of something.

  “When did the collapse into two dimensions stop?”

  The question made AA speechless, as well. Right: When—if ever—did it stop? Was there an instruction within that small, packaged two-dimensional foil that would eventually stop it? Cheng Xin and AA had no theoretical understanding of how three-dimensional space collapsed into two dimensions, but they instinctively thought the idea of an instruction embedded into two-dimensional space to halt its infinite expansion was too magical, the kind of magic that seemed impossible.

  Would the collapse never stop?

  It was best to not think about it too much.

  The star called DX3906 was about the Sun’s size. As Halo began decelerating, it still looked like an ordinary star, but by the time the curvature engine shut off, the star appeared as a disk whose light seemed redder than the Sun’s.

  Halo engaged the fusion reactor, and the silence on the ship was broken. The humming of the engine filled the ship, and every surface vibrated slightly. The ship’s AI analyzed the data obtained by the monitoring system and confirmed the basic facts about this solar system: DX3906 had two planets, both of them solid. The one farther from the star was about the size of Mars, but it had no atmosphere and appeared gray in color—so Cheng Xin and AA decided to call it Planet Gray. The other planet, closer to the star, was about the size of the Earth, and its surface resembled the Earth’s: an atmosphere containing oxygen and many signs of life, but without evidence of agriculture or industry. Since it was blue, like the Earth, they decided to call it Planet Blue.

  AA was very happy that her research had been confirmed. More than four hundred years ago, she had discovered the star’s planetary system. Before then, people had thought it was a bare star without any planets. Through that work, AA had gotten to know Cheng Xin. Without that coincidence, her life would have turned out completely differently. Fate was such an odd thing: Four centuries ago, when she had gazed at this distant world through the telescope, she could never have imagined that she’d come here one day.

  “Were you able to see these two planets back then?” Cheng Xin asked.

  “No. They were impossible to see in the visible light range. Maybe those telescopes from the Solar System advance warning system could have seen them, but all I could do was deduce their existence through the data obtained via the solar gravitational lens.… I did theorize about the appearance of these two planets, and it looks like I was basically right.”

  Halo had taken only fifty-two hours (by the ship’s frame of reference) to traverse the 286 light-years between the Solar System and the planetary system around DX3906, but it took eight full days to cross the sixty AU between the rim of the planetary system and Planet Blue at sub-light speeds. As Halo approached Planet Blue, Cheng Xin and AA discovered that its resemblance to the Earth was only superficial. The blue hue of this planet wasn’t the result of an ocean, but the color of the vegetation covering the continents. Planet Blue’s oceans were light yellow and took up only about a fifth of the planet’s surface. Planet Blue was a cold world; about a third of its continental surface was covered by blue vegetation, with the rest shrouded in snow. Most of the ocean was frozen, and only small patches near the equator were in liquid form.

  Halo entered orbit around Planet Blue and began its descent. But the ship’s AI announced a new discovery. “An intelligent radio signal has been detected from the surface. It’s a landing beacon using communication formats dating from the start of the Crisis Era. Would you like me to follow its instructions?”

  Cheng Xin and AA looked at each other excitedly. “Yes!” Cheng Xin said. “Follow its instructions to land.”

  “Hypergravity will approach 4G. Please enter into secured landing positions. Landing sequence will be initiated once you’re secure.”

  “Do you think it’s him?” AA asked.

  Cheng Xin shook her head. In her life, moments of happiness were only gaps between mass catastrophes. She was now afraid of happiness.

  Cheng Xin and AA sat in hypergravity seats, and the seats closed around them like giant palms squeezing them tight. Halo decelerated and descended, entering Planet Blue’s atmosphere after a series of powerful jolts. They could see the blue-and-white continents swinging into view in the images captured by the ship’s monitoring system.

  Twenty minutes later, Halo landed near the equator. The ship’s AI suggested that Cheng Xin and AA wait ten minutes before getting out of their seats, to give their bodies a chance to adjust to Planet Blue’s gravity, which was similar to the Earth’s. Out of the porthole and on the monitoring system terminals, they could see that the yacht had landed in the middle of a blue grassland. Not too far away, they could see rolling mountains covered by snow—the landing site was near the foot of the mountain range. The sky was a light yellow, like the ocean when viewed from space. A light red sun shone in the sky. It was noon on Planet Blue, but the sky and the sun’s colors made it resemble dusk on the Earth.

  Cheng Xin and AA didn’t examine the environment around them too carefully. Their attention was taken up by another small vehicle parked near Halo. It was a tiny craft, about four to five meters tall, with a dark gray surface. The profile was streamlined, but the tail fins were tiny. It didn’t seem to be an aircraft, but rather a ground-to-space shuttle.

  A man stood next to the shuttle, dressed in a white jacket and dark-colored pants. The turbulence of Halo’s landing disturbed his hair.

  “Is that him?”
AA asked.

  Cheng Xin shook her head. She knew right away that this wasn’t Yun Tianming.

  The man waded through the blue sea of grass toward Halo. He moved slowly, and his posture and movements showed some exhaustion. He didn’t show any signs of surprise or excitement, as if the appearance of Halo was a perfectly normal occurrence. He stopped a few tens of meters away from the yacht and waited patiently in the grass.

  “He’s good-looking,” said AA.

  The man looked to be in his forties. He was East Asian in appearance, and he was indeed more handsome than Yun Tianming, with a broad forehead and wise but gentle eyes. His gaze made you believe he was always thinking, as if nothing in the universe, including Halo, could surprise him, but only cause him to think more. He lifted his hands and moved them around his head, indicating a helmet. Then he shook his head and waved one hand, indicating that they didn’t need space suits out there.

  The ship’s AI agreed. “Atmospheric composition: thirty-five percent oxygen, sixty-three percent nitrogen, two percent carbon dioxide, with trace amounts of inert gasses. Breathable. But the atmospheric pressure is only point five three of Earth standard. Do not engage in strenuous exercise.”

  “What is that biological entity standing next to the ship?” asked AA.

  “Standard human being,” the AI replied.

  Cheng Xin and AA exited the ship. They hadn’t adjusted to the gravity yet, and stumbled a bit as they walked. Outside, they breathed easily, not feeling the thinness of the air. A chill breeze blew at them and brought the fragrance of grass, refreshing them. The wide-open view showed the blue-and-white mountains and earth, the light yellow sky and red sun. The whole thing resembled a false-color photograph of the Earth. Other than the strange colors, everything looked familiar. Even the blades of grass looked just like the grass on the Earth, except for their blue hue. The man came to the foot of the stairs.

  “Wait a minute. The stairs are too steep. I’ll help you down.” He climbed up the stairs easily and helped Cheng Xin down. “You should have rested longer before coming out. There’s no urgency.” Cheng Xin could hear an obvious Deterrence Era accent.