by Cixin Liu
Cheng Xin found herself in a white spherical space. She saw that 艾 AA was floating nearby, dressed in the same skintight hibernation suit. Her hair was wet and her limbs were spread out powerlessly; clearly, she had just been awakened as well. As their eyes met, Cheng Xin wanted to speak, but the numbness caused by the cold had still not left her, and she couldn’t make any noise. AA shook her head, meaning that she was in the same state and didn’t know anything.
Cheng Xin noticed that the space was filled with a golden light like the setting sun. The light came in through a circular window—a porthole. Outside the porthole, Cheng Xin could see only blurred streaks and swirling lines. The lines were arranged into parallel bands of blue and yellow, revealing a world covered by raging storms and torrents, clearly the surface of Jupiter. Cheng Xin saw that the surface of Jupiter looked much brighter than she remembered.
Strangely, the wide, raging cloud band in the middle reminded her of the Yellow River. She knew, of course, that an eddy in this “Yellow River” was big enough to contain the Earth. Against this background, Cheng Xin saw an object. The main body of the object was a long column whose sections were of different diameters. Three short cylinders were perpendicularly attached to the main column at different locations. The entire assembly slowly rotated around the axis of the column. Cheng Xin decided that she was looking at a combined space city formed from eight separate space cities docked together.
She discovered another amazing fact as well: The place they were in stayed at rest relative to the combined space city, but Jupiter was slowly moving in the background. Based on the brightness of Jupiter, they were now on the side facing the Sun, and she could see the shadow of the combined space city against the gaseous surface of Jupiter. After a while, the Jovian terminator appeared, dividing Jupiter’s day from night, and she saw the monstrous eye that was the Great Red Spot drifting into view. Everything confirmed the fact that both the place they were in and the combined space city were not in Jupiter’s shadow and did not orbit the Sun in parallel with Jupiter; instead, they were Jupiter’s satellites and revolved around the gas giant.
“Where are we?” Cheng Xin asked. She was finally able to speak in a hoarse voice, but she still couldn’t move her body.
AA shook her head again. “No idea. I think we’re on a spaceship.”
They continued to drift in the golden glow of Jupiter, like a dreamscape.
“You’re on Halo.”
The voice came from an information window that had just popped up next to them. In the window was an old man with a head full of white hair. Cheng Xin recognized him as Cao Bin. Based on his age, she realized that she had leapt across another long stretch of years. Cao Bin told her that it was now May 19 of Year 67 of the Bunker Era. She realized that fifty-six more years had passed since her last brief awakening.
She avoided life by staying outside of time, and she watched as others aged, seemingly in an instant. Her heart was filled with regret and guilt. She decided that no matter what happened from now on, this was her last hibernation.
Cao Bin told them that they were on the latest ship to bear the Halo name. It had been constructed only three years ago. After the Halo City Incident, more than half a century earlier, he and Bi Yunfeng had both been convicted, though both had served short sentences and then been released. Bi Yunfeng had died more than ten years earlier, and Cao Bin brought along his well wishes for her and AA. Cheng Xin’s eyes moistened.
Cao Bin also told them that there were now fifty-two large space cities in the Jupiter cluster, most of which had been combined into bigger cities. What they could see was Jupiter Combination II. Since the advance warning system had been refined twenty years ago, all cities had decided to become Jovian satellites. Only after an alert was issued would the cities change orbit and go into hiding.
“Life in the cities is once again like being in paradise. It’s too bad that you won’t get to see it, because there’s no time.” Cao Bin paused. Cheng Xin and AA exchanged uneasy glances. They realized that he had been so loquacious until now because he was trying to delay this moment.
“Was there an attack alert?”
Cao Bin nodded. “Yes, there’s been an alert. During the last half century, there were two false alarms, and each time, we almost awakened you. But this time it’s real. Children—I’m already one hundred and twelve years of age, so I think I can call you that—the dark forest strike is finally here.”
Cheng Xin’s heart tensed. It wasn’t because the attack had arrived—humanity had been preparing for this moment for more than a century. Rather, she sensed that something was wrong. She and AA had been awakened by contract. It would have taken at least four to five hours for them to recover to this stage, which meant that the alert had been issued some time ago. But outside the porthole, Jupiter Combination II had not disassembled nor changed its orbit, but continued to drift as a Jovian satellite, as though nothing had happened. They turned to Cao Bin: The centenarian’s expression was too placid, as though hiding utter despair.
“Where are you now?” AA asked.
“I’m at the advance warning center,” Cao Bin said, and pointed behind him.
Cheng Xin saw a hall behind him that looked like a control center. Information windows filled almost every bit of space. The windows drifted around the hall, but new windows kept on popping open before them, only to be covered in turn by still newer windows—like the flood after a burst dam. But the people in the hall seemed to be doing nothing. Half of them were in military uniforms, but they all either stood leaning against a desk or sat still. Everyone had dull eyes, and all had the same ominous calm expression that was on Cao Bin’s face.
It shouldn’t be like this.
This didn’t look like a world hunkered down inside a bunker, certain it could survive the attack. It looked more like three centuries ago—no, four centuries ago now—when the Trisolar Crisis had first developed. Back then, at the offices of the PIA and the PDC, Cheng Xin had seen this kind of atmosphere and expression everywhere: despair against some superpowerful force in the universe, a kind of numbness and indifference that said We give up.
Most of the people in the control center were quiet, but a few whispered to each other with somber faces. Cheng Xin saw a man sitting numbly. A cup had fallen over on the table in front of him, and a blue liquid spilled off the table onto his pants, but he ignored it. On the other side, in front of a large information window that seemed to show some complicated, evolving situation, a man in military uniform embraced a woman dressed as a civilian. The woman’s face seemed wet.…
“Why aren’t we entering Jupiter’s shadow?” AA pointed at the combined city outside the porthole.
“There’s no point. The bunker is useless,” Cao Bin said, lowering his eyes.
“How far is the photoid from the Sun?” Cheng Xin asked.
“There’s no photoid.”
“Then what have you found?”
Cao Bin gave a wretched laugh. “A slip of paper.”
Bunker Era, Year 66
Outside the Solar System
A year before Cheng Xin’s awakening, the advance warning system discovered an unknown flying object sweeping past the edge of the Oort Cloud at a speed close to lightspeed. At its closest approach, the object was only 1.3 light-years from the Sun. The object’s volume was immense, and at its near-lightspeed velocity, the radiation generated by its impact with the scattered dust and atoms in space was intense. The advance warning system also observed the object making a small course change during flight to avoid a patch of interstellar dust, before resuming its previous course. It was most certainly an intelligent spaceship.
This was the first time that Solar System humans—as opposed to Galactic humans—had observed another extraterrestrial civilization besides the Trisolarans.
Due to lessons learned from the previous three false alarms, the Federation Government did not publicize this discovery. No more than a thousand people in the entire Bunker World knew
about it. During the few days when the spaceship had been closest to the Solar System, these individuals lived in extreme anxiety and terror. In the few tens of space observation units comprising the advance warning system, in the advance warning center (a space city in the Jupiter cluster), in the battle center of Federation Fleet Command, and in the office of the president of the Solar System Federation, people held their breaths and watched the spaceship’s course like a trembling school of fish hiding at the bottom of a pond, waiting for the trawler to pass overhead. These individuals’ terror developed to absurd levels later: They refused to use radio communications, walked noiselessly, and spoke only in whispers.… In reality, everyone understood that these gestures were meaningless, not the least because what the advance warning system observed had happened a year and four months ago. By now, the spaceship was already gone.
After the extraterrestrial spaceship moved farther away, these individuals did not relax. The advance warning system discovered something else that was worrisome. The strange spaceship did not shoot a photoid at the Sun, but did launch something else. This object was also shot at the Sun at lightspeed, but it produced none of the emissions associated with photoids and was completely invisible electromagnetically. The advance warning system only managed to discover it through gravitational waves. The object continuously emitted weak gravitational waves whose strength and frequency remained constant. The waves clearly carried no message, and were probably the result of some physical characteristic of the projectile. When the advance warning system initially discovered these gravitational waves, the source was thought to be the extraterrestrial spaceship. But they soon found that the source was separate from the spaceship, and it was approaching the Solar System at lightspeed.
Further analysis of the observation data revealed that the projectile wasn’t aimed precisely at the Sun. According to its current trajectory, it would sweep past the Sun outside the orbit of Mars. If the intended target had been the Sun, this was a relatively gross error. This showed another way that the projectile was different from a photoid: The data gathered from the previous two photoid strikes all showed that after a photoid was launched, it followed a precise, straight trajectory to the target star (taking into account the motion of the star) and did not require any course correction. It could be surmised that a photoid was essentially a rock flying under inertia at lightspeed. Tracking the gravitational wave source showed that the projectile did not make any course corrections, apparently indicating that its target was not the Sun. This provided some comfort for everyone involved.
When the projectile was about 150 AU from the Sun, the gravitational waves it emitted began to rapidly decrease in frequency. The advance warning system discovered that this was due to its deceleration. Within a few days, the projectile’s velocity went from lightspeed to one-thousandth of lightspeed, and continued to decrease. Such low speed meant that it wasn’t enough to threaten the Sun, which provided further comfort. In addition, at this speed, human spacecraft could keep up with it. In other words, it was possible to send out ships to intercept it.
* * *
Revelation and Alaska departed the Neptune city cluster and flew in formation to investigate the unknown projectile.
Both ships were equipped with gravitational wave reception systems and could form a positioning network to determine the location of the transmission source with precision at close range. Since the Broadcast Era, more ships had been built that could transmit and receive gravitational waves. But the design concepts used in these ships were very different from earlier antenna ships. One of the main innovations was separating the gravitational wave antenna from the ship itself so that they formed two independent units. The antenna could then be combined with different ships, and could be replaced after it failed due to decay. Revelation and Alaska were only medium-sized ships, but they had about the same total volumes as large ships because the gravitational wave antennas made up a large portion of their structures. The two ships resembled helium-filled airships of the Common Era: They looked immense, but the effective payload was just the small gondola hanging below the gasbags.
Ten days after the two ships left port, General Vasilenko and 白 Ice,8 dressed in lightweight space suits and magnetic shoes, took a stroll on the gravitational wave antenna of Revelation. They enjoyed doing this because there was much more space out here compared to the interior of the spaceship, and walking around the antenna made one feel like walking on solid earth. They were the leaders of the first exploratory team: Vasilenko was the commander while 白 Ice was in charge of technical matters.
Alexei Vasilenko had been an observer in the advance warning system during the Broadcast Era. Together with Widnall, he had discovered the trails of the Trisolaran lightspeed ships, which led to the first false alarm. After the incident, Sublieutenant Vasilenko was made one of the scapegoats and was dishonorably discharged. But he thought the punishment unjust and hoped that history would ultimately clear his name, and thus entered hibernation. As time passed, the discovery of the lightspeed trails grew in importance, and the damage from the first false alarm was gradually forgotten. Vasilenko awakened in Year 9 of the Bunker Era, was restored to his former rank, and by now had been promoted to vice admiral of the Solar Federation Space Force. However, he was close to eighty years of age. As he looked at 白 Ice strolling next to him, he thought how unfair life was: This man had been born eighty years before himself and came from the Crisis Era; yet, after hibernation, he was just over forty.
白 Ice’s original name was Bai Aisi.9 After awakening, he wanted to appear more integrated and not so behind the times, and chose a more common modern name that mixed English and Chinese elements. He had been a doctoral student under Ding Yi and had gone into hibernation near the end of the Crisis Era, awakening only twenty-two years ago. Usually, such a long leap across the years meant the hibernator would have trouble catching up to the new age, but theoretical physics was a special case. The sophon lock meant that Common Era physicists could still be considered professionally relevant during the Deterrence Era, and the creation of the circumsolar particle accelerator upended all the assumptions of fundamental theoretical physics, as though a deck of cards had been reshuffled.
Back during the Common Era, superstring theory had been thought of as advanced theory, the physics of the twenty-second century. The creation of the circumsolar particle accelerator allowed superstring theory to be confirmed via experiments. The result, however, was disastrous. Concepts that had to be rejected far outnumbered predictions that were confirmed. Many results that the Trisolarans had passed on were falsified. Based on the high level of technology the Trisolarans were later able to achieve, it was inconceivable that they had made such mistakes in fundamental theory. The only conclusion was that they had lied to humans even in the areas of basic theory.
白 Ice had proposed some theoretical models that were among the few confirmed by the circumsolar particle accelerator. By the time he awakened, physics had essentially been called back to the starting line. He quickly distinguished himself and won great honors, and after ten or so years, he was once again at the vanguard of the field.
“Look familiar?” Vasilenko gestured at everything around them.
“Indeed. But the self-confidence and arrogance of humanity are all gone,” said 白 Ice.
This resonated with Vasilenko. He looked back along the ship’s course. Neptune was only a tiny blue dot and the Sun a faint spot of light, incapable of even casting their shadows against the antenna surface. Where were the two thousand stellar-class warships that had formed a magnificent phalanx all those years ago? Now, there were just these two lonely ships with a complement of no more than a hundred crew. Alaska was about a hundred thousand kilometers away but not visible to them. That ship wasn’t only acting as the other end of the positioning network, but also held another exploratory team organized the same as the team aboard Revelation. Fleet Command called the team aboard Alaska the backup, indicating that the brass h
ad made ample preparations for the risk and danger inherent in this expedition. Here, at the cold, desolate frontier of the Solar System, the antenna under their feet seemed a lonesome island in the universe. Vasilenko wanted to sigh, but thought better of it. He took something out of the pocket of his spacesuit and let it float between the two of them, spinning slowly.
“Check this out.”
The object appeared to be a bone from some animal. In fact, it was a metallic machine component; the frigid light of the stars glinted against its smooth surface.
Vasilenko pointed at the spinning object. “About a hundred hours ago, we detected a patch of floating metallic debris next to the ship’s course. A drone retrieved a few items, and this is one of them: a piece of the cooling system for a nuclear fusion reactor aboard a stellar-class warship from the end of the Crisis Era.”
“It’s from the Doomsday Battle?” asked an awed 白 Ice.
“Yes. We also found the armrest from a chair and a bulkhead fragment.”
They had been passing through the vicinity of the ancient battlefield from nearly two centuries earlier. After the Bunker Project started, people often discovered remnants of ancient warships. Some were placed in museums while others were bought and sold through the black market. 白 Ice held the component and felt a chill pass through the glove of the space suit, straight into his marrow. He let it go, and the component continued to spin slowly, as though moved by some soul embedded within. 白 Ice moved his eyes away and gazed into the distance. All he could see was a bottomless, empty abyss. Two thousand warships and millions of dead bodies had been drifting in this patch of desolate space for nearly two centuries. The sacrificial blood of the dead had long ago sublimated from ice to gas and dissipated.
“The target of our exploration might be more dangerous than even the droplets this time,” 白 Ice said.
“True. Back then, we already had some familiarity with the Trisolarans. But we know nothing about the world that created and sent this.… Dr. Bai, do you have any guesses as to what we will encounter?”
