Death's End

by Cixin Liu

  “I’ve been through that already.”

  “If you continue to pursue the dream of lightspeed spaceflight, you’ll encounter more such experiences. Can you really endure them?”

  * * *

  The false alarm was the largest social disturbance since the Great Resettlement. Although brief in duration and limited in the damage caused, it left an indelible mark in the psyche of the world.

  Most of the thousands of spaceports across the world had shuttles that took off while surrounded by crowds, and more than ten thousand people died in the flames of fusion drives. Armed conflicts also took place at the base stations of space elevators. Unlike at the spaceports, the fights at the space elevators involved nations. Some countries attempted to occupy the international elevator’s base station in tropical waters, and only the timely confirmation that the attack alarm was false prevented full-scale warfare. In orbits around Earth, and even on Mars, groups of people fought over spaceships.

  In addition to the degenerates who were willing to kill to ensure their own survival, the public discovered something else that disgusted them during the course of the false alarm: tens of small stellar spaceships and near-stellar spaceships were discovered to be in secret construction in geosynchronous orbit and on the dark side of the moon. Near-stellar spaceships possessed the ecological cycling systems of stellar ships, but were only equipped with propulsion systems for interplanetary flight. Some of these luxurious yachts belonged to large companies, and others to extremely wealthy individuals. All the crafts were small, and could only maintain a few people with their ecological cycling systems. They had only one purpose: long-term seclusion behind the giant planets.

  The advance warning system that was still being constructed could only provide a warning window of about twenty-four hours. If a dark forest strike really arrived, there wasn’t enough time for any spacecraft to go from the Earth to Jupiter, the nearest barrier planet. In actuality, the Earth dangled over a sea of death. Rationally, everyone understood this, and the ugly fights that broke out during the false alarm were nothing more than meaningless mass madness driven by a survival instinct that overwhelmed rational thinking. Currently, about fifty thousand individuals resided at Jupiter—most of them were space force personnel at the Jupiter base, along with some staff doing preparatory work for the Bunker Project. They had plenty of justification for being at Jupiter, and the public did not begrudge them their place. But once these secret stellar ships were completed, their wealthy owners would be able to hide in the shadow of Jupiter indefinitely.

  Legally—at least right now—there was no international or national prohibition against the construction of stellar ships by organizations or individuals, and hiding out behind the gas giants wasn’t the same as Escapism. However, the inequality here was seen as the greatest in human history: inequality before death.

  Historically, inequality mainly manifested itself in areas like economics or social status, but death basically treated everyone the same. To be sure, such equality wasn’t absolute: For instance, access to medical care wasn’t evenly distributed; the wealthy fared better in natural disasters than the poor; soldiers and civilians had different rates of survival in war; and so on. But never before had a situation like this presented itself: less than one-ten-thousandth of the population could go into safe hiding, leaving billions on Earth to die.

  Even in ancient times, such manifest inequality would have been intolerable, let alone now.

  This led directly to international skepticism about the plan for lightspeed ships.

  Although spaceships hiding permanently behind Jupiter or Saturn could survive a dark forest strike, life on those ships would not be enviable. No matter how comfortable the ecological cycling systems made the shipboard environment, the occupants would be living in the cold, desolate regions of the outer Solar System in isolation. But as observations of the Second Trisolaran Fleet revealed, spacecraft powered by curvature propulsion could achieve lightspeed almost instantaneously. A lightspeed ship could go from the Earth to Jupiter in less than an hour, and the advance warning system would be more than sufficient. Powerful and wealthy individuals who possessed lightspeed ships could thus live in comfort on the Earth and then escape at the last minute, without regard for the billions left behind. This was a prospect society simply could not tolerate. The terrifying sights from the false alarm remained fresh in the public’s mind, and most people agreed that the appearance of lightspeed ships would lead to worldwide chaos. Thus, the plan for developing lightspeed ships faced unprecedented resistance.

  * * *

  The false alarm was the result of the explosive amplifying effects of a hyper-information society when fed sensitive news. Its source was an anomaly detected by the first observation unit of the advance warning system. The anomaly was real, though it had nothing to do with photoids.

  Excerpt from A Past Outside of Time

  Space Sentries: The Solar System Advance Warning System

  The Earth had observed photoids only twice in the past: the destruction of 187J3X1 and of the Trisolaran system. Knowledge about the phenomenon was thus limited. All that was known was that a photoid moved at close to the speed of light, but there was no data concerning its volume, rest mass, or relativistic mass as it approached the speed of light. A photoid was certainly the most primitive weapon capable of attacking a star, since it relied only on the enormous kinetic energy generated by its high relativistic mass to damage the target. Once a civilization possessed the technology to accelerate an object to near the speed of light, a “bullet” with very little mass possessed immense destructive power. This was indeed “economical.”

  The most valuable data concerning photoids was obtained right before the annihilation of the Trisolaran system. Scientists were able to make an important discovery: Due to a photoid’s ultrahigh velocity, powerful radiation ranging from visible light to gamma rays was emitted as it collided with the few atoms scattered in space and interstellar dust. The radiation had distinctive characteristics. Since the photoids were extremely small, direct observation of them was impossible. But the characteristic radiation could be detected.

  At first blush, it seemed impossible to give advance warning for photoids, because they moved at close to the speed of light. This meant that they moved almost as fast as the radiation they generated, and reached their target almost simultaneously. In other words, the observer was outside the event’s light cone.

  But reality was a bit more complicated. Any object with rest mass could not achieve lightspeed. Although a photoid’s speed approached lightspeed, it was still slightly slower than true lightspeed. This difference meant that the radiation from the photoid moved just a bit faster than the photoid itself. If the photoid had to travel a long distance, this difference was magnified. Also, a photoid’s trajectory to the target wasn’t an absolute straight line. Since it wasn’t massless, it couldn’t avoid the gravitational attractions of nearby celestial bodies, and its path typically ended up being slightly curved. The curvature was much greater than the curvature of light through the same gravitational field. For the photoid to strike the target, its trajectory had to take this effect into account. This meant that the path traveled by the photoid was longer than the path taken by its radiation.

  For these two reasons, the radiation from the photoid would reach the Solar System before the photoid itself. The twenty-four-hour estimated warning period was calculated based on the maximum distance at which photoid emissions could be observed. By the time the radiation reached the Earth, the photoid itself would still be about 180 AU away.

  But that was merely the ideal scenario. If the photoid were launched from a nearby spaceship, there would be almost no warning—like what had happened to Trisolaris.

  Thirty-five observation units were planned for the Solar System advance warning system. These would monitor the sky in every direction for photoid emissions.

  Broadcast Era, Year 8

  Fate’s Choice

&
nbsp; Two days before the false alarm; Observation Unit #1

  Observation Unit #1 was in fact just the Ringier-Fitzroy Station from the end of the Crisis Era. More than seventy years ago, it was this observation station that had first discovered the strong-interaction space probes—the droplets. The station was still located on the outer edge of the asteroid belt, but all its equipment had been updated. Take the visible light telescope, for instance: The lenses were even bigger, and the first lens’s diameter had increased from twelve hundred meters to two thousand meters, big enough for a small town to fit on it. These gigantic lenses were made from materials taken directly from the asteroid belt. The first one was a medium-sized lens five hundred meters in diameter. After that was finished, it was used to focus sunlight on asteroids so that the melted rock could be made into pure glass and then formed into additional lenses. In total, six lenses floated in a ten-kilometer-long column in space, far apart from each other. The observation station itself was located at the end of the column of lenses, and could only hold a crew of two.

  The crew was still made up of a scientist and a military officer. The officer was responsible for monitoring photoid emissions, while the scientist conducted astronomical and cosmological research. Thus, the tradition of fighting for observation time begun three centuries ago by General Fitzroy and Dr. Ringier continued.

  After this, the largest telescope in history, had completed its shakedown tests and successfully taken its first image—a star forty-seven light-years away—Widnall, the astronomer on the crew, was as excited as if he’d just had a son. Laymen did not understand that previous telescopes could only amplify the luminosity of stars outside the Solar System, not reveal any shapes. No matter how powerful the telescopes were, the stars always showed up as tiny point sources, only incrementally brighter than images taken by lesser telescopes. But now, in the view of this ultrapowerful telescope, a star showed up as a disk for the first time. Though it was small, like a Ping-Pong ball seen from tens of meters away, and one couldn’t see any details in the disk, this was still an epochal moment in the history of the ancient science of visible-light astronomy.

  “The cataracts have been removed from the eyes of astronomy!” said Widnall dramatically, wiping his eyes.

  But Sublieutenant Vasilenko wasn’t impressed. “I think you need to remember our role here: We are sentries. In the old days, we’d be perched atop a wooden watchtower on the frontier, a desolate desert or snowfield around us. Standing erect in the frigid breeze, we’d be gazing in the direction of the enemy. As soon as we saw tanks coming up the horizon, or men on horses, we’d make a call or light smoke signals to inform the homeland that the enemy invasion had begun.… You need to get into that mental space. Don’t think of yourself as being in an observatory.”

  Widnall’s eyes temporarily left the terminal showing the image from the telescope and looked out the porthole of the station. He could see a few irregularly shaped rocks drifting at some distance: fragments of asteroids left from the glass-making operation. They spun slowly in the cold sunlight and seemed to emphasize the desolation of space. The scene did seem to evoke a sense of the “mental space” the sublieutenant described.

  Widnall said, “If we really discover a photoid, it would be better to not issue a warning at all. It’s useless, anyway. To die suddenly without even knowing what hit you is actually a rather fortunate fate. But you’d rather torture a few billion people for twenty-four hours. I think that’s akin to a crime against humanity.”

  “By that logic, you and I would be the most unfortunate people in the world since we would know about our fate the longest.”

  The observation station received new orders from Fleet Command to adjust the telescope and observe the remnants of the Trisolaran system. Widnall didn’t argue with Vasilenko this time, because he was very interested in that ruined world as well.

  The floating lenses began to move around and adjust their positions, the plasma thrusters at the rims of the lenses emitting blue flames. Only now did the lenses in the distance reveal themselves, the blue flames marking out the overall shape of the telescope. The ten-kilometer-long group of lenses slowly turned, stopping when the telescope was pointed in the direction of the Trisolaran system. Then the lenses shifted up and down the axis to focus. Finally, most of the flames went out, with only a few fireflies flickering now and then as the lenses engaged in precision focus adjustments.

  In the unprocessed view of the telescope, the Trisolaran system looked very ordinary, just a small patch of white against the background of space, like a feather. But after the image had been processed and magnified, it appeared as a magnificent nebula that took up the entire screen. It had been seven years since the explosion of the star, so what they were seeing now was the scene three years after the explosion. Under the influence of gravity and the exploded star’s angular momentum, the nebula had turned from sharp radiating rays into a soft blur of clouds, which was then flattened by the centrifugal force of the spin into a spiral. Above the nebula, the two remaining stars could be seen. One of them showed up as a disk, while the other one, more distant, remained a point of light distinguished only by its motion against the background stars.

  The two stars that survived the catastrophe achieved the dream of generations on Trisolaris and formed a stable double-star system, but no life would enjoy their light, as the entire system was now uninhabitable. It was now apparent that the dark forest strike had destroyed only one star out of the three, not only because of economics, but also to achieve a more sinister goal: As long as the system still retained one or two stars, the material in the nebula would be constantly absorbed by the stars, generating powerful radiation in the process. The Trisolaran system was now a radiation furnace, a domain of death for life and civilization. It was the powerful radiation that caused the nebula itself to glow and appear so clear and bright on the telescope.

  “I’m reminded of the clouds viewed from atop Mount Emei,” said Vasilenko. “That’s a mountain in China. Viewing the moon from the peak is an exquisite sight. The night I was there, the peak floated in a boundless sea of clouds, turned pure silver by the moon above. It looked a lot like this.”

  Seeing this silvery graveyard more than forty trillion kilometers away made Widnall wax philosophical. “From a scientific perspective, ‘destroy’ isn’t really accurate. Nothing has disappeared. All the matter that used to be there is still there, and so is all the angular momentum. It’s only the arrangement of matter that has changed, like a deck of cards being reshuffled. But life is like a straight flush: Once you shuffle, it’s gone.”

  Widnall examined the image some more and made an important discovery.

  “What is that?!” He pointed at a spot in the image some distance from the nebula. By scale, it was about thirty AU from the nebula center.

  Vasilenko stared at the spot. He lacked the trained eye of an astronomer, and couldn’t see anything unusual at first. But eventually, he saw a vague circular outline against the pitch-black background, like a soap bubble in space.

  “It’s very large. The diameter is about … ten astronomical units. Is it dust?”

  “Absolutely not. Dust doesn’t look anything like that.”

  “You’ve never seen it before?”

  “No one could have seen it. Whatever it is, it’s transparent, with a very faint border. The largest telescopes in the past wouldn’t have been able to detect it.”

  Widnall zoomed out a bit to get a better sense of the position of the strange new object with respect to the double stars, and to try to observe the spin of the nebula. On the screen, the nebula again turned into a small patch of white against the black abyss of space.

  About six thousand AU from the Trisolaran system, he found another “soap bubble.” This one was much bigger than the first, with a diameter of about fifty AU, spacious enough to contain the Trisolaran system or the Solar System.

  “My God!” Vasilenko cried out. “Do you know where that is?”


  Widnall stared at the screen for a while and said, tentatively, “That’s where the Second Trisolaran Fleet went into lightspeed, isn’t it?”

  “Exactly.”

  “You’re certain?”

  “My old job was to observe this part of space. I know it better than the palm of my hand.”

  The conclusion was inescapable: Ships using curvature propulsion left behind trails as they accelerated to lightspeed. The trails apparently did not fade with time, but expanded and altered the nature of the space around them.

  The first, smaller bubble was inside the Trisolaran system. There were several possible explanations for its existence. Perhaps the Trisolarans did not know initially that curvature propulsion would leave behind such trails, and the bubble was an accident created during engine tests or test flights; or perhaps they did know about the trails, but left them within the star system by mistake. But it was certain that they wanted to avoid purposefully leaving such trails. Eleven years ago, the Second Trisolaran Fleet had cruised for a full year using conventional means, and only when they were six thousand AU from their home world did they engage the curvature engines to enter lightspeed. The purpose was to start the trails as far from the home world as possible, though by that time it was already too late.

  At the time, the behavior of the Second Trisolaran Fleet had puzzled people. The most convincing explanation was that they were trying to avoid ill effects on the home world caused by 415 ships entering lightspeed. However, it was clear now that they were trying to avoid exposing the location of Trisolaris by the trails of curvature propulsion. The Second Trisolaran Fleet had exited lightspeed when it was still six thousand AU from the Solar System for the same reason.

  Widnall and Vasilenko stared at each other, and they could each see the terror building in the other’s eyes. They had reached the same conclusion.

  “We have to report this right away,” said Widnall.