by Liu Cixin
Since nothing could exceed the speed of light, if light couldn’t leave the Solar System’s event horizon, nothing else could either. The Solar System would be hermetically sealed off from the rest of the universe.
And therefore completely safe—as far as the rest of the universe was concerned.
How would a distant observer see the Solar System black hole created by lowering the speed of light? There were two possibilities: for technologically primitive observers, the Solar System would simply disappear; and, for technologically advanced observers, they should be able to detect the black hole, but instantly understand that the system was safe.
Take a distant star, a barely visible dot. Anyone casually glancing at it would say: Oh, that star is safe; that star will not threaten us.
This was the cosmic safety notice. The impossible was possible, after all.
The interpreters thought of the Glutton’s Sea, thought of the Storyless Kingdom sealed off from the rest of the universe by the sea. This additional bearing coordinate really wasn’t necessary—they already understood.
Later, people would call a black hole formed by lowering the speed of light a “black domain.” Compared to black holes where the speed of light was unaltered, a reduced-lightspeed black hole had a much larger Schwarzschild radius. The interior was not a space-time singularity, but a fairly open region.
The helicopter continued above the clouds. It was now after 11 P.M., and the sun slowly set in the west, leaving only a slice visible. In the golden light of the midnight sun, everyone tried to imagine life in a world where light moved just below 16.7 kilometers per second, tried to imagine the creeping light of such a sunset.
* * *
By now, most of the puzzle pieces in Yun Tianming’s stories had fallen into place. But one piece remained: the paintings of Needle-Eye. The interpreters couldn’t figure out the dual-layer metaphor or find any bearing coordinates. Some thought that the paintings might be another bearing coordinate for the Moskstraumen, symbolizing the event horizon of the black domain. They reasoned that from an outside observer’s perspective, anything entering the black domain would be forever fixed at the event horizon, which resembled being painted into a picture. But most interpreters disagreed. The meaning of the Moskstraumen was very clear, and Tianming had used the Glutton’s Sea to act as a bearing coordinate. There was no need for another.
Ultimately, this last piece of the puzzle could not be deciphered. Like the missing arms of Venus de Milo, the paintings of Needle-Eye remained mysterious. But as this detail formed the foundation for all three stories and described an elegant ruthlessness, an exquisite cruelty, and a beautiful death, it must have hinted at a great secret of life and death.
Excerpt from A Past Outside of Time
Three Paths of Survival for Earth Civilization
I. The Bunker Project: This was the plan with the most hope for success, because it was based entirely on known technologies and involved no theoretical unknowns. In some sense, the Bunker Project could be viewed as a natural continuation of the development of the human race. Even without the threat of a dark forest strike, it was time for humanity to begin colonizing the rest of the Solar System. The Bunker Project just made the effort more focused and the goals clearer.
This was also a plan devised entirely by the Earth itself; it had not been described in the message from Yun Tianming.
II. The Black Domain Plan: This involved transforming the Solar System into a reduced-lightspeed black hole to broadcast a cosmic safety notice. Out of all the choices, this was the most technically challenging. Within a region of space fifty AU (or 7.5 billion kilometers) in radius, a physical constant had to be altered. This was dubbed God’s Engineering Project. The theoretical unknowns were immense.
But if the Black Domain Plan were to succeed, it would provide the most protection for Earth civilization. Setting aside its effect as a cosmic safety notice, the black domain itself would act as a highly effective protective barrier. Any external missile, such as a photoid, would be traveling at a very high velocity to produce the necessary destructive power, and would thus enter the black domain with a speed far in excess of the modified speed of light inside. Under the theory of relativity, such an object would have to proceed at the (new, low) speed of light as soon as it crossed the barrier, and its excess kinetic energy would be converted to mass. The first part of the object entering the black domain would suddenly slow down and acquire a much larger mass, while the rest of the object, still moving at the unaltered speed of light, would run into the first part, thereby destroying the entire missile with the impact. Calculations showed that even objects made of strong-interaction materials such as droplets would be completely shattered at the boundary of the black domain. Thus, a black domain was also dubbed “the cosmic safe.”
There was yet another advantage to the Black Domain Plan: Out of all three choices, it was the only plan that allowed humanity to continue to live on the familiar surface of the Earth and avoid an exile in space.
But Earth civilization would pay a heavy price. The Solar System would be completely divided from the rest of the universe, equivalent to humanity shrinking their universe from 16 billion light-years across to one hundred AU. Moreover, it was impossible to know what life in such a world would be like. It was certain that electronic and quantum computers would have to operate at extremely low speeds, so humanity might regress to a low-technology society. This would be an even more absolute seal than the technology seal imposed by the sophons. Besides being a cosmic safety notice, the Black Domain Plan was also a form of technological self-mutilation. Humans would never be able to escape from this reduced-lightspeed trap.
III. Lightspeed Spaceflight Plan: Although the theoretical foundation for curvature propulsion was unknown, it was clearly easier than the Black Domain Plan.
Lightspeed spaceflight could not, however, provide any security for Earth civilization. It was only good for escape into the stars. Of all three plans, this involved the most unknowns. Even if it succeeded, members of the human race who escaped into the vast emptiness of space faced unpredictable dangers. Also, the dangers of escapism meant that the plan faced numerous political barriers and traps.
Yet a portion of humanity was certain to be obsessed with lightspeed spaceflight for reasons other than survival.
For people of the Broadcast Era, the only smart choice was to carry out all three plans simultaneously.
Broadcast Era, Year 8
Fate’s Choice
Cheng Xin came to the headquarters of the Halo Group.
This was her first time here. She had never participated in its operation because, subconsciously, she never thought of the enormous wealth as truly hers, or Yun Tianming’s. They possessed that star, but the wealth generated by the star belonged to society.
But now, perhaps, the Halo Group could help her realize her dream.
The corporate headquarters occupied an entire giant tree. Interestingly, all the buildings on the tree were transparent. Moreover, as the refractive index in the construction material was close to that of the air, all internal structures were visible. One could see employees moving inside as well as countless information windows. The hanging buildings resembled transparent ant farms with colorful ants milling about inside.
Inside the large conference room at the tip of the tree, Cheng Xin got to meet most of the high-level executives of the Halo Group. They were all young, smart, and vivacious. Most of them had never met Cheng Xin before, and they did not disguise their awe and adoration.
After the meeting, when only Cheng Xin and AA remained in the large, empty room, they began to talk about the future of the company. The message from Yun Tianming and the deciphering progress remained secrets from the public. To protect Tianming, Fleet International and the UN planned to release the results gradually to the public and to make them appear as the fruits of research on Earth. Some deliberate false research results would also be mixed in to further conceal the real origi
n of the information.
Cheng Xin had gotten used to the transparent floor and no longer felt so acrophobic. A few large information windows drifted in the conference room, displaying live video feeds from a few of the Halo Group’s construction projects in Earth orbit, one of which was the giant cross in geosynchronous orbit. After Tianming’s reappearance, the public’s hopes for a miracle gradually faded, and with the initiation of the Bunker Project, the religious fervor dimmed. The church stopped investing in the giant cross, and it was abandoned. Now it was in the process of being dismantled so that only a giant “1” remained—a rather meaningful sight.
“I don’t like ‘black domain,’” said AA. “It would be more appropriate to call it ‘black tomb,’ a tomb we dig for ourselves.”
Cheng Xin looked at the city below through the transparent floor. “I don’t think of it that way. During the era I was from, the Earth was completely separated from the rest of the universe. Everyone lived on the surface, and very rarely did they glance up at the stars. People had lived that way for five thousand years, and you can’t just say that wasn’t a good life. Even now, the Solar System is basically separated from the rest of the universe. The only people who are in deep space are the thousand or so people on those two spaceships.”
“But I feel that if we separate ourselves from the stars, dreams will die.”
“Not at all. In ancient times there was happiness and joy as well, and they had no fewer dreams than we. Also, even inside a black domain, we would still see the stars, only … who knows what that would look like.… Personally, I don’t like ‘black domain’ either.”
“I know you don’t.”
“I like lightspeed ships.”
“We all like lightspeed ships. The Halo Group should build lightspeed ships!”
“I thought you weren’t going to agree,” Cheng Xin said. “This requires heavy investment in basic research.”
“You think I’m just a capitalist? Well, you’re not wrong. I am, and so are the members of the board of directors. We want to maximize profits. But that doesn’t conflict with lightspeed spaceships. Politically, the government will devote the most resources into the Bunker Project and the black domain, but lightspeed ships will be left to entrepreneurs.… We should put our efforts into the Bunker Project, and then use some of the profits to research lightspeed ships.”
“Here’s my thinking, AA: Curvature propulsion and the black domain probably share some fundamental theories. We can wait for the government and the World Academy of Sciences to complete that part of the research, then develop it toward curvature propulsion.”
“All right. We should start a Halo Group Academy of Sciences, too, and recruit scientists. Many of them have dreamed about lightspeed spaceflight, but they can’t find such opportunities in national or international projects—”
AA was interrupted by a sudden surge of new information windows. Windows of all sizes appeared in every direction like a colorful avalanche, quickly burying the few original information windows showing feeds from the Halo Group’s projects. A “window avalanche” like this usually indicated the sudden occurrence of some important event, but the flood of information often caused people to be overwhelmed, unable to find out what actually happened. Such was the case with AA and Cheng Xin. They saw that most of the windows were filled with complex text and animated figures, and only those windows that showed pure images could be taken in at a glance. In one of the windows, Cheng Xin saw a few faces looking upwards, then the lens zoomed in until a frightened pair of eyes filled the frame, accompanied by a cacophony of screams.…
A new window came to the forefront showing AA’s secretary. She stared at AA and Cheng Xin, her face full of terror and shock.
“A warning! An attack!” she shouted.
“Any specifics?” AA asked.
“They activated the first observation unit in the Solar System advance warning system and found a photoid right away!”
“In what direction? How far?”
“I don’t know. I don’t know anything. All I know—”
“Is this an official warning?” Cheng Xin asked calmly.
“I don’t think so. But it’s in all the media. I’m sure it’s real! Let’s get to the spaceport and run for our lives!” The secretary disappeared from the window.
Cheng Xin and AA passed through the dense congeries of information windows and arrived at the transparent wall of the conference room. They saw that panic had already seized the city below them. A massive increase in the number of flying cars outside resulted in chaos, and every vehicle tried to force itself through the jam at high speed. One of the cars struck a giant tree building and erupted into a fireball. Soon, fire and columns of smoke appeared in two other locations in the city.…
AA picked out a few information windows and perused them carefully. Cheng Xin, on the other hand, tried to get in touch with the members of the IDC. Most of their phones were busy, and Cheng Xin managed to talk to only two committee members. One of them, like AA and Cheng Xin, knew nothing. The other, a PDC official, told Cheng Xin that he could confirm that Observation Unit #1 in the Solar System advance warning system had noticed some significant anomaly, but he didn’t know the specifics. He also confirmed that Fleet International and the UN had not issued a formal dark forest strike alarm, but he wasn’t optimistic.
“There are two possibilities for why no alarm has been issued: One, nothing has happened. Two, the photoid is too close and an alarm would be useless.”
AA was only able to obtain one piece of specific information from her reading: The photoid was coming along the ecliptic plane. There were conflicting reports concerning its exact direction and distance from the Sun, and estimates of when the photoid would strike the sun diverged wildly: Some claimed that the world had another month; others said only a few hours.
“We should go to Halo,” AA said.
“Is there enough time?”
Halo was a corporate spaceship that belonged to the Halo Group. Right now, it was parked at the company’s geosynchronous base. If the alarm was real, their only hope now was to ride the ship to Jupiter and hide out behind the gas giant before the photoid struck. As Jupiter was in opposition, and therefore as close to the Earth as it could be, it would take twenty-five to thirty days for the ship to fly from the Earth to Jupiter, which was just under the upper end of the range of estimates for when the photoid would strike. But this estimate seemed highly unreliable: The advance warning system was still being constructed, and couldn’t have given such an early alert.
“We have to do something instead of waiting here to die!” AA said. She dragged Cheng Xin out of the conference room and onto the parking lot at the top of the tree. They ducked into a flying car, but AA seemed to remember something and got out again. A few minutes later, she returned with an oblong object that resembled a violin case. She opened the case, took out what was inside, and carried it with her into the car, leaving the case behind.
Cheng Xin looked at what was in AA’s hand and recognized the implement: a rifle, though adapted to shoot laser bolts instead of bullets.
“Why are you bringing this?” Cheng Xin asked.
“The spaceport is sure to be filled with people—who knows what’s going to happen?” AA tossed the rifle onto the backseat and started the flying car.
Every city had a spaceport to service various small space vessels—rather like ancient airports.
The flying car merged into a mighty aerial stream of traffic. All the countless cars in the stream, like a swarm of locusts, were headed for the spaceport. They cast a flowing shadow along the ground, as though the city’s blood was seeping out.
Ahead, a dozen or so white lines rose into the blue sky, trails left by spaceships. They rose straight up and then turned east and disappeared in the depths of the firmament. New white lines continuously shot up from the ground and extended into air, each line headed by a fireball that was brighter even than the sun: the flame from the fusion dr
ives of the ships.
On an information window inside the car, Cheng Xin saw a live video feed taken from near-Earth orbit. Countless rising white lines appeared against the tan background of the continent and extended upward. They grew more numerous, denser, as though the Earth was growing white hair. The fireballs at the ends of the white lines were like fireflies drifting into space. This was the greatest collective escape into space in human history.
Their car arrived above the spaceport. About a hundred spacecraft were arrayed below, and more were being moved out of the giant hangar in the distance. Space planes had long since fallen out of use, and modern shuttles all took off vertically. Unlike the oddly shaped spacecraft Cheng Xin had seen at the port in the space elevator terminal station, these shuttles all had streamlined profiles, with three or four tail fins. They were now erected helter-skelter in the parking lot of the spaceport, like a forest of steel.
AA had called ahead to the hangar to move one of the Halo Group’s shuttles onto the lot. She quickly picked out the shuttle from the air and landed their car next to it.
Cheng Xin looked at the shuttles around her. They were of different sizes: The smaller ones were only about a few meters tall, looking like giant versions of artillery shells. It was hard to imagine that such tiny crafts could escape the Earth’s gravity well. There were also larger vessels, some as big as ancient airliners. The Halo Group’s shuttle was medium-small in size, about ten meters tall, covered with a reflective metallic surface reminiscent of the droplets. The shuttle was parked on a wheeled launch frame so that it could be dragged to the launch point at a moment’s notice. They would ride this shuttle to reach Halo in orbit.