Death's End

by Cixin Liu

  Guan Yifan ordered the ship to do another scan at a depth range between ten and twenty meters. This took another hour, the bulk of which was spent waiting for the ship to pass overhead. Still nothing. At that depth there was no more soil, only bedrock.

  Guan Yifan adjusted the scanning range to between twenty and thirty meters. “This is the last time,” he said to Cheng Xin. “The sensors can’t go deeper than that.”

  They waited for the ship to orbit Planet Blue another time. The sun was setting and the sky was full of lovely, fiery clouds, while the purple woods were limned with a golden glow.

  This time, the shuttle’s screen showed the images transmitted back by the ship. After processing by enhancement software, they could see a few fragments of white words embedded in the dark rock: “e,” “liv,” “a,” “life,” “you,” “little,” “side,” “Go.” The white color was to indicate that the words were carved into the bedrock; each character was about a meter square, and they were arranged into four rows. The words were twenty-three to twenty-eight meters below them, carved into a forty-degree incline.

  WE LIVED A HAPPY LIFE TOGETHER

  WE GIVE YOU A LITTLE

  SURVIVE THE COLLAPSE INSIDE

  GO TO THE NEW

  Hunter’s AI invoked the geological expert system to interpret the results. They found out that the giant characters had initially been carved into the surface of a large sedimentary rock formation on the side of a mountain. The original surface was about 130 square meters. Over the eons, the mountain on which the rock had been located sank, and that was how the carved rock ended up below them. More than four lines of text had been carved into it, but the lower portion of the rock had been broken up during the geological transformations and all the text there lost. The surviving text was incomplete as well—the last three lines all had missing characters at the end.

  Cheng Xin and Guan Yifan embraced again. They cried tears of joy at the news concerning 艾 AA and Yun Tianming, and shared the happiness that they had enjoyed more than one hundred eighty thousand centuries ago. Their despairing hearts grew peaceful.

  “I wonder what their life here was like?” Cheng Xin asked, tears glistening in her eyes.

  “Anything was possible,” said Yifan.

  “Did they have children?”

  “Anything was possible. They could have even founded a civilization here.”

  Cheng Xin knew that was indeed possible. But even if that civilization had lasted ten million years, the eight million-plus years that had come after would have erased all traces of it.

  Time really was the cruelest force of all.

  Something strange interrupted their meditation: a rectangle limned by faint lines of light, about a man’s height, hovered over the clearing like the dashed selection lines marked out by dragging a mouse. It moved through the air, but did not go far before returning to its original position. It was possible that it had been there all along, but the outline was so faint and thin that it was invisible during daytime. Whether it was made by a force field or actual substance, there was no doubt it was the creation of intelligence. The lines making up the rectangle seemed to evoke the line-shaped stars in the sky.

  “Do you think this is the … gift they left for us?” Cheng Xin asked.

  “Seems hard to believe. How could it have survived more than eighteen million years?”

  But he was wrong. The object had indeed survived eighteen million years. And, if necessary, it could survive until the end of the universe, because it existed outside of time.

  The door remembered that, initially, it had been placed next to the rock carved with text, and it had a real metal frame. But the metal had eroded away after only five hundred thousand years, though the object had always remained brand new. It had no fear of time because its own time had not yet started. It had been thirty meters underground, next to the carved rock, but it had detected the presence of humans and risen to the surface. During the process, it did not interact with the crust, moving like a ghost. It now confirmed that these two were indeed the ones it had been expecting.

  “I think it looks like a door,” Cheng Xin said.

  Yifan picked up a small branch and tossed it at the rectangle. The branch passed through it and landed on the other side. They saw a luminescent flock of little balloon creatures drift over. A few passed through the rectangle and one even crossed the glowing outline.

  Yifan reached out and touched the frame. The light and his finger passed through each other, and he felt nothing. Without even thinking, he extended his hand into the space outlined by the rectangle. Cheng Xin screamed. Yifan pulled his hand back, and everything looked unharmed.

  “Your hand.… It didn’t go through.” Cheng Xin pointed to the other side of the rectangle.

  Yifan tried again. His hand and forearm disappeared as they entered the plane of the rectangle and did not go through. From the other side, Cheng Xin saw the cross section of his forearm, like the surface of a window. All his bones, muscles, and blood vessels were clearly visible. He pulled his hand back and tried again with a branch. It went through the frame without problems. Right after, two insects with spinning rotors passed through the rectangle as well.

  “It really is a door—a smart door that recognizes what’s going through it,” Yifan said.

  “It allowed you in.”

  “Probably you, as well.”

  Cheng Xin gingerly tried, and her arm also disappeared in the “door.” Yifan observed the cross section of her arm from the other side, and had a moment of déjà vu.

  “Wait for me here,” Yifan said. “I’ll go investigate.”

  “We should go together,” Cheng Xin said resolutely.

  “No, you wait here.”

  Cheng Xin grabbed him by both shoulders and turned him to face her. She looked into his eyes. “Do you really want us to also be separated by eighteen million years?”

  Yifan stared back into her eyes for a long moment, and finally nodded. “Perhaps we should bring some things with us.”

  Ten minutes later, they passed through the door, hand in hand.

  Outside of Time

  Our Universe

  Primordial darkness.

  Cheng Xin and Guan Yifan were once again immersed in a time vacuum. The sensation was similar to when they had entered reduced lightspeed back in the shuttle. Time did not flow here, or maybe it was more accurate to say that time did not exist. They lost all sense of time, and experienced again that feeling of stepping across time, but existing outside of it.

  Darkness disappeared; time began.

  There is no appropriate expression in human language to express the moment at the start of time. To say that time began after they entered the door would be wrong because “after” required time. There was no time here, and thus no before or after. The time “after” they entered could have been shorter than a billion-billionth of a second, or longer than a billion billion years.

  The sun brightened. It did so very gradually: At first it was just a disk, and then the light began to unveil the world. It was like a song that began as barely audible notes, then grew and grew into a mighty chorus. A circle of blue appeared around the sun, expanded, and turned into a blue sky. Under the blue sky, a pastoral scene slowly took shape. There was an unplanted field with black soil; next to it was an exquisite white house. There were also a few trees that brought a hint of the exotic with their broad, strangely shaped leaves. As the sun continued to brighten, the peaceful scene appeared like a welcoming embrace.

  “There are people here!” Guan Yifan pointed at the distance.

  They could see the backs of two figures standing on the horizon: a man and a woman. The man had just put down his uplifted arm.

  “That’s us,” said Cheng Xin.

  In front of those two figures, they could see a distant white house and trees, exact duplicates of the ones nearby. They couldn’t see what was at the feet of those figures due to the distance, but they could guess that it was anoth
er black field. At the end of the world was a duplicate of it, or maybe a projection.

  Duplicates or projections of the world existed all around them. They looked to their sides and saw the same scene repeated. The two of them also existed in those worlds, but all they could see were the backs of those figures, who turned their heads away as Cheng Xin and Yifan turned to look at them. They looked behind them and saw the same thing—except now they were looking at the world from the other direction.

  The entrance to the world had disappeared.

  They followed a path of stepping-stones, and around them, the copies of themselves in the copies of their world walked along with them. The path was broken by a brook with no bridge over it, but the brook was so small that they could step over it. Only now did they realize that gravity was a standard 1G. They passed the copse of trees and came to the white house. The door was shut and the windows covered by blue curtains. Everything looked brand new, dustless—as a matter of fact, they were brand new, also, as time had just begun to flow.

  In front of the house was a pile of simple, primitive farming tools: shovels, rakes, baskets, water pails, and so on. Although some of them were shaped a bit oddly, it was easy to tell their function by appearance. What most drew their attention, though, was a row of metal columns erected next to the farming tools. They were about the height of a person, and the smooth surfaces glinted in the sunlight. Each column had four metal attachments that seemed to be folded limbs. The columns were probably robots in a resting state.

  They decided to familiarize themselves with the environment before entering the house, and so they continued to walk past it. After a bit less than a kilometer, they reached the edge of the small world and faced the duplicate world before them. At first, they thought it was just a reflected image of their own world, though it was not mirrored. But after they were halfway there they decided that it couldn’t be a reflection: Everything looked so real. They took a step forward and entered the duplicate world without any resistance. Looking around, Cheng Xin was struck with a hint of terror.

  Everything looked the same as when they had first entered the world. They were in the same pastoral scene, with duplicates of the scene before them and to the sides, and in those copies, copies of them also existed. They turned around to look back, and they saw copies of themselves at the far end of the world they had just left, looking behind them.

  Yifan let out a long sigh. “I don’t think we need to go any farther. We’ll never reach the end.” He pointed up and then down. “I bet that without these barriers, we’d see the same scene above and below us as well.”

  “Do you know what this is?”

  “Are you familiar with the work of Charles Misner?”

  “Who was he?”

  “A physicist of the Common Era. He was the one who first came up with this concept. The world we’re in is actually very simple. It’s a regular cube about a kilometer on each side. You can imagine it as a room with four walls and a ceiling as well as a floor. But the room is constructed such that the ceiling is also the floor, and each wall is the same as the opposite wall. In reality, it has only two walls. If you walk through one of the walls, you’ll immediately reappear at the opposite wall, and the same is true of the floor and ceiling. Thus, this is a completely enclosed world in which the end is also the beginning. The images we see all around us are the result of light returning to the starting point after crossing the world. We’re still in the same world we started from, because this is the only world that exists. Every copy we see around us is just an image of this world.”

  “So this is…”

  “Yes!” Yifan swept his arm around to indicate everything. “Yun Tianming once gave you a star, and now he’s given you a universe. Cheng Xin, this is an entire universe. It might be small, but it’s a complete universe.”

  Cheng Xin looked around, at a loss for words. Yifan sat down quietly on a ridge in the field and picked up a fistful of black earth, letting the soil slip from between his fingers. He sounded depressed. “He’s quite a man to be able to give the woman he loved a star and a universe. But I can’t give you anything.”

  Cheng Xin sat down as well and leaned on his shoulder. She laughed as she said, “You’re the only man in this universe. I don’t think you need to give me anything.”

  The feeling of being alone in the universe was soon shattered by the sound of a door opening. A figure in white came out of the house and walked toward them. The world was so small that it was possible to clearly see anyone at any distance. They saw that the newcomer was a woman dressed in a kimono. The kimono, decorated with tiny red flowers, was like a walking flower bush that brought the feeling of spring to the universe.

  “Sophon!” Cheng Xin cried out.

  “I know her,” Yifan said. “She’s the robot controlled by sophons.”

  They walked over to meet the woman under one of the trees. Cheng Xin saw that it really was Sophon: That unparalleled beauty remained unchanged.

  Sophon bowed deeply to Cheng Xin and Guan Yifan. When she straightened, she smiled at Cheng Xin. “I said that the universe is grand, but life is grander. Fate has indeed directed us to meet again.”

  “I couldn’t have imagined,” Cheng Xin said. “I’m really glad to see you. Really.” Sophon brought her to the past—more than eighteen million years ago. But that wasn’t really accurate, because they were now in another time stream altogether.

  Sophon bowed again. “Welcome to Universe 647. I am its manager.”

  “The manager of the universe?” Yifan looked at Sophon, astounded. “What a grand title! For a cosmologist like me, that sounds like—”

  “Oh no!” Sophon laughed and waved his remark away. “You are the true masters of Universe 647 and have full authority over everything here. I’m just here to serve you.”

  Sophon made a gesture indicating that they should follow her. They followed her to a refined parlor inside the house. The parlor was decorated in an Eastern style with a few calming brush paintings and calligraphy scrolls hung on the walls. Cheng Xin looked for artifacts taken from Pluto by Halo but didn’t find any. After they sat down at an antique wooden desk, Sophon poured tea for them—without going through the complicated steps of the Way of Tea. The tea leaves seemed to be Longjing, and they stood up at the bottom of the cups like a tiny green forest, giving off a fresh fragrance.

  To Cheng Xin and Guan Yifan, everything seemed to be a dream.

  Sophon spoke. “This universe is a gift. Mr. Yun Tianming gave it to the both of you.”

  “I think it’s meant for Cheng Xin,” said Yifan.

  “No. You’re also one of the intended recipients. Your authorization was added to the recognition system later; otherwise you wouldn’t have been allowed in. Mr. Yun hoped that you could hide in this tiny universe and avoid the collapse of the great universe—or the big crunch—and, after the next big bang, enter the new universe and see its Edenic Age. Right now, we exist in an independent timeline. Time is passing rapidly in the great universe, and you will certainly be able to see its end within your lifetimes. More specifically, I estimate that the great universe will collapse into a singularity after about ten years here.”

  “If a new big bang occurs, how will we know?” asked Yifan.

  “We’ll know. We can sense the conditions in the great universe through the supermembrane.”

  Sophon’s words reminded Cheng Xin of what Yun Tianming and 艾 AA had carved into the rock. But Guan Yifan was reminded of something else. He noticed that Sophon spoke of the “Edenic Age” of the new universe. This was a term invented by the Galactic humans. Two possibilities presented themselves. One was that coincidentally, the Trisolarans had also picked this term. The second possibility was far more terrifying: the Trisolarans had already discovered the Galactic humans. Given how quickly Yun Tianming had arrived on Planet Blue, it was apparent that the First Trisolaran Fleet was very close to the worlds of humankind. And now, the Trisolaran civilization had developed to the p
oint where they were capable of constructing small universes: This was a great threat to humanity.

  Then he laughed.

  “What are you laughing at?” Cheng Xin asked.

  “Myself.”

  He found himself ridiculous. More than eighteen million years had passed since the day he’d departed World II to come to Planet Blue, and that was before they entered this small universe with its own time. By now, hundreds of millions of years must have passed in the great universe. He was worried about truly ancient history.

  “Have you seen Yun Tianming?” Cheng Xin asked.

  Sophon shook her head. “No. I’ve never met him.”

  “What about 艾 AA?”

  “The last time I saw her was on Earth.”

  “Then how did you come to be here?”

  “Universe 647 was a custom order. I’ve been here since its completion. Remember that I am fundamentally just a collection of digital bits, and many copies of me can be made.”

  “Did you know that Tianming brought this universe to Planet Blue?”

  “I don’t know what Planet Blue is. If it’s a planet, then Mr. Yun couldn’t have brought Universe 647 to it, because this is an independent universe that does not exist within the great universe. He could only bring the entrance to the universe there.”

  “Why aren’t Tianming and AA here?” Yifan asked. This was also the question Cheng Xin most wanted answered. She hadn’t asked earlier because she was afraid of hearing an answer she didn’t want to know.

  Sophon shook her head again. “I don’t know. The recognition system has always had Mr. Yun’s authorization.”

  “Is anyone else’s authorization in the system?”

  “No. Only the three of you.”

  After a while, Cheng Xin said to Yifan, “AA always cared more than me about the world around her. I don’t think she would have been interested in a new universe tens of billions of years later.”

  “I’m interested,” said Yifan. “I really want to see what a new universe is like before it’s distorted and tampered with by life and civilization. I think it must exhibit the highest degree of harmony and beauty.”