by Cixin Liu
The weather that day was good. There was no wind and no sandstorms, and the early spring air smelled fresh. The two of them, teacher and student, lay against a dune. The desert of Northern China was bathed in the light of the setting sun. Normally, Bai Aisi thought of these rolling dunes as a woman’s body—possibly a comparison that had originated with Ding Yi himself—but now he thought of them as an exposed brain. In the golden dusk, the brain revealed its profusion of grooves and folds. He looked up at the sky. Today, the dusty air managed to let through a bit of long-missed blue, like a mind about to be enlightened.
Ding Yi said, “Aisi, I want to tell you a few things that you should not repeat to others. Even if I don’t return, don’t tell others. There’s no special reason. I just don’t want to be laughed at.”
“Professor Ding, why not wait until you’re back to tell me?”
Bai Aisi wasn’t trying to comfort Ding Yi. He was sincere. He was still drunk with the ecstasy and vision of humanity’s imminent great victory over the Trisolaran fleet, and he did not think Ding Yi’s trip to the droplet would involve much danger.
“Answer a question first, please.” Ding Yi ignored Bai Aisi’s question and pointed at the desert lit by the westering sun. “Forget about the uncertainty principle for a minute and suppose everything is determinable. If you know the initial conditions, you can calculate and derive the conditions at any later point in time. Suppose an extraterrestrial scientist were given all data about the Earth several billion years ago. Do you think it could predict the existence of this desert solely through calculation?”
Bai Aisi pondered this. “No. This desert wasn’t the result of the Earth’s natural evolution, but the result of man-made forces. The behavior of civilizations can’t be grasped through the laws of physics.”
“Very good. Then why do we and our colleagues all want to try to explain the conditions of today’s cosmos, and to predict its future, solely through deductions based on the laws of physics?”
Ding Yi’s words surprised Bai Aisi. The man had never revealed such thoughts in the past.
Bai Aisi said, “I think that’s beyond physics. The goal of physics is to discover the fundamental laws of nature. Although the man-made desertification of the Earth could not be calculated directly from physics, it still follows laws. Universal laws are constant.”
“Heh heh heh heh.” Ding Yi’s laugh was not joyous at all. As he recalled it later, Bai Aisi thought it was the most sinister laughter he had ever heard. There was a hint of masochistic pleasure, an excitement at seeing everything falling into the abyss, an attempt to use joy as a cover for terror, until terror itself became an indulgence. “Your last sentence! I’ve often comforted myself this way. I’ve always forced myself to believe that there’s at least one table at this banquet filled with dishes that remain fucking untouched.... I tell myself that again and again. And I’m going to say it one more time before I die.”
Bai Aisi thought Ding Yi’s mind was elsewhere and that he talked as if he were dreaming. He didn’t know what to say.
Ding Yi continued, “At the beginning of the crisis, when the sophons were interfering with the particle accelerators, a few people committed suicide. At the time, I thought what they did made no sense. Theoreticians should be excited by such experimental data! But now I understand. Those people knew more than I did. Take Yang Dong, for instance. She knew much more than I did, and thought further. She probably knew things we don’t even know now. Do you think only sophons create illusions? Do you think the only illusions exist in the particle accelerator terminals? Do you think the rest of the universe is as pure as a virgin, waiting for us to explore? Too bad that she left with everything she knew.”
“If she had talked with you more back then, perhaps she wouldn’t have chosen to go.”
“Perhaps I would have gone with her.”
Ding Yi dug a pit in the sand and watched as the sand on the rim flowed back in like a waterfall. “If I don’t come back, everything in my room is yours. I know that you’ve always liked those Common Era things I brought.”
“That’s true, especially those tobacco pipes.... But I don’t think I’ll get them.”
“I hope you’re right. I also have some money—”
“Please, Professor!”
“I want you to use it to pay for hibernation. The longer the better—of course, that’s assuming you want to. I have two goals in mind: One, I want you to go look at the endgame for me—the endgame for physics. Two... how do I say this? I don’t want you to waste your life. After others have decided that physics actually exists, there will still be plenty of time for you to go do physics.”
“That... seems like something Yang Dong would say.”
“Maybe it’s not nonsense.”
Bai Aisi noticed that the pit Ding Yi had dug in the desert was rapidly expanding. They stood up and backed away as the pit continued to grow, getting deeper as well as wider. Soon, the bottom disappeared in shadows. Sand flooded into the pit in torrents, and soon, the diameter of the pit was close to a hundred meters, and a nearby dune was swallowed up. Bai Aisi ran toward the car and got into the driver’s seat; Ding Yi followed into the passenger seat. Bai Aisi noticed that the car was moving slowly toward the pit, dragged along by the sand underneath. He turned on the engine and the wheels began to turn, but the car continued to slide backwards.
Ding Yi laughed that sinister laugh again. “Heh heh heh heh... ”
Bai Aisi turned the electric motor to the highest setting and the wheels spun madly, throwing up sand everywhere. But the car still moved toward the pit like a plate pulled along on a tablecloth.
“Niagara Falls! Heh heh heh heh...”
Bai Aisi looked back and saw a sight that made his blood curdle: The pit now took up his entire field of vision. The whole desert was swallowed up by it, and the world was like a giant pit whose bottom was an abyss. At the rim, flowing sand poured in and formed a spectacular yellow sandfall. Ding Yi wasn’t exactly right in his description: The Niagara Falls were minuscule compared to this sandfall of terror. The sandfall extended from the near edge of the pit all the way to the far edge on the horizon, forming an immense sandfall ring. The sand torrents rumbled as if the world itself were coming apart. The car continued to slide toward the pit, faster and faster. Bai Aisi floored the accelerator and leaned his weight into it, but there was no effect.
“You fool. Do you really think we can escape?” Ding Yi said while still laughing sinisterly. “Escape velocity! Why don’t you calculate the escape velocity? Are you thinking with your butt? Heh heh heh heh...”
The car tumbled over the rim and dropped in the sandfall. The sand raining down around them seemed to stop as everything plunged into the abyss. Bai Aisi screamed with utter terror, but he couldn’t hear himself. All he heard was Ding Yi’s wild laughter.
“Hahahahaha... There’s no table untouched at the dinner party, and there’s no virgin untouched in the universe... waheeheeheehee... wahahahaha...”
白 Ice woke from his nightmare and found himself covered in cold sweat. Around him, more droplets of sweat hung suspended in air. He floated for a while, his body stiff, and then dashed out of his cabin and headed for Vasilenko’s cabin. It took a while before the door opened, as Vasilenko was also sleeping.
“General! Do not keep that thing, that thing they call a slip of paper, in the spaceship! No, I mean, don’t allow Revelation to hover around it. We should leave immediately, and get as far away as possible!”
“What have you discovered?”
“Nothing. It’s my intuition.”
“You don’t look so good. Exhaustion? I think you’re worrying too much. That thing... I don’t think it’s anything. There’s nothing inside. It should be harmless.”
白 Ice grabbed Vasilenko by the shoulders and gazed into his eyes. “Don’t be arrogant!”
“What?”
“Don’t be arrogant. Weakness and ignorance are not barriers to survival, but arrogance is.
Remember the droplet!”
白 Ice’s last sentence had an effect. Vasilenko stared at him in silence for a few seconds, then nodded slowly. “All right, Dr. Bai, I’ll listen to you. Revelation will depart from the slip and back off one thousand kilometers. We’ll leave just a pinnace to monitor it.... Maybe two thousand kilometers?”
白 Ice let Vasilenko go and wiped his forehead. “You decide. I suggest, the farther the better. I will write a formal report as soon as possible and let Command know of my theories.” Stumbling, he drifted away.
Revelation left the slip. It passed through the ship’s hull and was reexposed to space. Since the background was dark again, it once again appeared to be an opaque white slip of paper. Revelation pulled away from the slip until the two were about two thousand kilometers apart, then continued to sail in parallel, waiting for the arrival of Tomorrow. A pinnace with a crew of two stayed about ten meters from the slip to monitor it continuously.
The gravitational waves emitted by the paper slip continued to diminish, and its light gradually dimmed.
On Revelation, 白 Ice shut himself in the laboratory. Around him, he set up more than a dozen information windows, all connected to the ship’s quantum computer, which was carrying out massive computations. The windows were packed with equations, curves, and matrices. Surrounded by the windows, 白 Ice was anxious and irritable, like a trapped animal.
Fifty hours after the separation from Revelation, the gravitational wave emitted from the paper slip disappeared completely. The white light from it blinked twice and also went out. The slip of paper was gone.
“Has it evaporated?” Vasilenko asked.
“I don’t think so. But we can’t see it anymore.” 白 Ice shook his head wearily and closed the information windows around him one by one.
After another hour during which no signs of the slip could be detected, Vasilenko ordered the pinnace to return to Revelation. But the two crew members on duty in the pinnace didn’t acknowledge the order; the radio only transmitted a hurried conversation between them.
“Look out below! What’s going on?”
“It’s rising!”
“Don’t touch it! Get out!!”
“My leg! Ahhh—”
After the scream, the monitoring terminal on Revelation showed one of the crew members leaving the pinnace and activating the thrusters on his space suit in an attempt to escape. They saw a bright light; the source was the bottom of the pinnace, which was melting! The pinnace looked like a scoop of ice cream dropped onto a scalding sheet of glass: The bottom was melting and spreading in every direction. The “glass” was invisible, and the plane’s existence was indicated only by the spreading pool of melted pinnace material. The pool spread into an extremely thin sheet and emitted bewitching, colorful lights, like fireworks scattered through a sheet of glass.
The escaped crewman flew some distance but seemed to be pulled by gravity toward that plane marked by the melted pinnace. His feet touched the plane and immediately melted into a shiny puddle. The rest of his body also began to spread out on the plane, and he had time only for a scream that was abruptly cut off.
“All hands to hypergravitation seats! Full Ahead!”
As soon as he saw the escaping crewman’s feet touch the invisible plane, Vasilenko gave the order. Revelation wasn’t a stellar ship, so when it engaged in Full Ahead acceleration, the crew did not need to enter into the protective deep-sea state. But the hypergravity was enough to sink everyone deep into their seats. Since the order was given in such a hurry, a few couldn’t get to their seats in time and fell to the stern of the ship with injuries. Revelation’s exhaust nozzles emitted a plasma stream several kilometers long that pierced the dark night of space. Far in the distance, where the pinnace was still melting, they could see the phosphorescent glow like will-o’-the-wisps in the wilderness.
From the zoomed-in view on the monitoring terminal, they could see that only the very top part of the pinnace was left, and that too soon disappeared into the brilliant plane. The body of the dead crewman was also diffused into the plane, showing up as a gigantic, man-shaped glow. His body had been transformed into a slice on the plane without thickness. Though large in area, it had no volume.
“We’re not moving,” the pilot of Revelation said. He had trouble talking through the hypergravity. “The ship isn’t accelerating.”
“What are you babbling about?” Vasilenko wanted to shout, but the hypergravity turned it into a whisper.
It really did seem as if the pilot should have been wrong. Everyone on the ship was pressed against their seat by hypergravity, which indicated that the ship was in the process of extreme acceleration. It was visually impossible for a passenger to tell whether the ship was moving in space because all celestial bodies that could act as reference points were too far away, so they couldn’t see parallax in a short time frame. However, the ship’s navigation system could detect even tiny amounts of motion and acceleration; it couldn’t be wrong.
Revelation was under hypergravity, but had no acceleration. Some force had nailed it to this point in space.
“There is acceleration,” said 白 Ice weakly. “But the space in this region is flowing in the opposite direction, thus canceling out our motion.”
“The space is flowing? Where to?”
“There, of course.”
白 Ice couldn’t lift his hand, which was now too heavy. But everyone knew where he meant. Revelation sank into a deathlike silence. Normally, hypergravity made people feel safe, as though they were escaping from danger under the embrace of some protective power. But now it seemed as oppressive and suffocating as a tomb.
“Open a channel to Command,” 白 Ice said. “There’s no time, so we’ll treat this as our formal report.”
“Channel open.”
“General, you once said, ‘I don’t think it’s anything. There’s nothing inside.’ You were right. That slip really wasn’t anything, and contained nothing. It’s only space, just like the space around us, which isn’t anything and contains nothing. But there’s a difference: It’s two-dimensional. It’s not a block, but a slice. A slice without thickness.”
“Hadn’t it evaporated?”
“The protective field around it evaporated. The force field acted like packaging that separated the two-dimensional space from the three-dimensional space. But now the two are in direct contact. Do you remember what Blue Space and Gravity saw?”
No one answered, but they all remembered: the four-dimensional space falling into three dimensions, like a waterfall off a cliff.
“Just as four-dimensional space collapses into three dimensions, three-dimensional space can collapse into two dimensions, with one dimension folding and curling into the quantum realm. The area of that slice of two-dimensional space—it only has area—will rapidly expand, causing more space to collapse.... We’re now in space that is falling toward two dimensions, and ultimately, the entire Solar System will follow. In other words, the Solar System will turn into a painting with no thickness.”
“Can we escape it?”
“Escaping this is like rowing a boat above a waterfall. Unless we exceed a certain escape velocity, we’ll tumble over the cliff. It’s like tossing a pebble up from the ground: No matter how high you throw the rock, it will eventually fall back down. The entire Solar System is within the zone of collapse, and anyone trying to escape must reach escape velocity.”
“What is the escape velocity?”
“I’ve computed it four separate times. Pretty sure I got it right.”
“What is it?!”
Everyone aboard Revelation and Alaska held their breaths and listened to this final calculation as representatives of humanity.
白 Ice calmly announced his judgment. “Lightspeed.”
The navigation system showed that Revelation was now moving in the opposite direction from its heading. It started by moving slowly toward the two-dimensional space, but gradually accelerated. The ship’s drive was still p
owering Full Ahead. This would at least slow down the rate of the ship’s fall and delay the inevitable.
On the plane two thousand kilometers away, the light emitted by the two-dimensionalized pinnace and crewmen had already gone out. Compared to collapsing from four dimensions to three, the fall from three dimensions to two gave off much less energy. Two two-dimensional structures were revealed clearly by the starlight. On the two-dimensionalized pinnace, it was possible to see the details of three-dimensional structures unfolded in two dimensions—the crew cabin, the fusion reactor, and so on—as well as the curled-up figure of the crewman in the cabin. In the figure of the other crewman, the bones and blood vessels could be clearly discerned, as well as all the body parts. During the process of falling into two dimensions, every point on a three-dimensional object was projected onto the plane in accordance with precise geometric principles, and so these two figures turned out to be the most complete and precise images of the original three-dimensional pinnace and people. All the internal structures were now laid out side by side in two dimensions with nothing hidden. The projection process, however, was very different from that used in engineering drawings, and so it was difficult to visually reimagine the shapes’ original three-dimensional structure. The greatest difference from engineering drawings lay in the fact that the two-dimensional unfolding occurred at every scale: All the original three-dimensional structures and details were laid out in parallel in two dimensions, and the result replicated, in some measure, the effect of viewing the three-dimensional world from four-dimensional space. This closely resembled drawings of fractals: No matter how much you zoomed in on a part of the image, it would get no less complex. However, fractals were theoretical concepts—actual representations were inevitably limited by the resolution, and after zooming in a number of times, the images lost their fractal nature. The complexity of the two-dimensionalized three-dimensional objects, on the other hand, was real: The resolution was at the level of fundamental particles. On the monitoring terminal of Revelation, the eye could only see a limited resolution, but the complexity and number of details already made the viewers dizzy. This was the universe’s most complicated image; staring at it for too long would drive one mad.
