Cixin Liu - Death's End

“It’s better than death,” said Yifan.

While Cheng Xin was still recovering from the shock, Yifan continued, “The speed of light is also frequently used as a weapon. I’m not talking about building light tombs—or, as you call them, black domains. Those are just defensive mechanisms employed by weak worms like us. The gods do not stoop so low. In war, it’s possible to make reduced-lightspeed black holes to seal the enemy inside. But more commonly, the technique is used to construct the equivalents of pits and city walls. Some reduced-lightspeed belts are large enough to traverse an entire arm of a galaxy. In places where the stars are dense, many reduced-lightspeed black holes can be connected together into chains that stretch for tens of millions of light-years. That’s a Great Wall at the scale of the universe. Even the most powerful fleets, once trapped, would not be able to escape. Those barriers are very difficult to cross.”

“What is the ultimate result of all this manipulation of space-time?”

“Dimensional strikes will eventually cause more and more of the universe to become two-dimensional, until one day the entire universe is two-dimensional. Similarly, the construction of fortifications will eventually cause all the reduced-lightspeed areas to connect, until the different lowered lightspeeds all average out: This new average will be the new c for the universe.

“At that time, any scientist from a baby civilization—like us—would think that the speed of light through vacuum is barely a dozen kilometers per second, and this is an ironclad universal constant, just like we now think the same of three hundred thousand kilometers per second.

“Of course, I’ve only brought up two examples. Other universal laws of physics have been used as weapons as well, though we don’t know all of them. It’s very possible that every law of physics has been weaponized. It’s possible that in some parts of the universe, even… Forget it, I don’t even believe that.”

“What were you going to say?”

“The foundation of mathematics.”

Cheng Xin tried to imagine it, but it was simply impossible. “That’s… madness.” Then she asked, “Will the universe turn into a war ruin? Or, maybe it’s more accurate to ask: Will the laws of physics turn into war ruins?”

“Maybe they already are…. The physicists and cosmologists of the new world are focused on trying to recover the original appearance of the universe before the wars more than ten billion years ago. They’ve already constructed a fairly clear theoretical model describing the pre-war universe. That was a really lovely time, when the universe itself was a Garden of Eden. Of course, the beauty could only be described mathematically. We can’t picture it: Our brains don’t have enough dimensions.”

Cheng Xin thought back to the conversation with the Ring again.

Did you build this four-dimensional fragment?

You told me that you came from the sea. Did you build the sea?

“You are saying that the universe of the Edenic Age was four-dimensional, and that the speed of light was much higher?”

“No, not at all. The universe of the Edenic Age was ten-dimensional. The speed of light back then wasn’t only much higher—rather, it was close to infinity. Light back then was capable of action at a distance, and could go from one end of the cosmos to the other within a Planck time…. If you had been to four-dimensional space, you would have some vague hint of how beautiful that ten-dimensional Garden must have been.”

“You’re saying—”

“I’m not saying anything.” Yifan seemed to have awakened from a dream. “We’ve only seen small hints; everything else is just guessing. You should treat it as a guess, just a dark myth we’ve made up.”

But Cheng Xin continued to follow the course of the discussion taken so far. “—that during the wars after the Edenic Age, one dimension after another was imprisoned from the macroscopic into the microscopic, and the speed of light was reduced again and again…. ”

“As I said, I’m not saying anything, just guessing.” Yifan’s voice grew softer. “But no one knows if the truth is even darker than our guesses…. We are certain of only one thing: The universe is dying.”

The ship stopped accelerating, and weightlessness returned. Before Cheng Xin’s eyes, space and the stars appeared more and more hallucinatory, more and more like a nightmare. Only the 3G hypergravity had brought some sense of solidity. She had welcomed the powerful embrace of those arms, an embrace that had provided some protection against the terror and frigidity of the dark myths of the universe. But now the hypergravity was gone, and only nightmare remained. The Milky Way appeared as a patch of ice hiding bloody remains, and DX3906 nearby appeared as a cremator burning over an abyss.

“Can you turn off the holographic display?” Cheng Xin asked.

Yifan turned it off, and Cheng Xin returned from the vastness of space to the cramped eggshell interior of the cabin. Here, she recovered a trace of the security she craved.

“I shouldn’t have told you all that,” Yifan said. His sorrow was sincere.

“I would have found out sooner or later,” Cheng Xin said.

“Let me repeat: They are just guesses. There’s no real scientific proof. Don’t think about it too much. Focus on what’s before your eyes; focus on the life you must live.” Yifan put a hand over hers. “Even if what I told you is true, those events are measured at the scale of hundreds of millions of years. Come with me to our world, which is now also your world. Live out your life and stop skipping across the surface of time. As long as you live your life within a hundred thousand years and a thousand light-years, none of those things need concern you. That ought to be enough for anyone.”

“Yes, it is enough, thank you.” Cheng Xin held Yifan’s hand.

Cheng Xin and Guan Yifan spent the rest of the journey in the forced slumber of the sleep-aid machine. The trip lasted four days. By the time they awakened in the hypergravity of deceleration, Planet Gray took up most of their field of view.

Planet Gray was a small planet. It visually resembled the moon, a barren rock, but instead of craters, much of Planet Gray’s surface was taken up by desolate plains. Hunter entered orbit around Planet Gray. Due to the lack of an atmosphere, the orbit was very low. The ship approached the coordinates provided by the monitoring satellite, where the five unidentified spacecraft had landed and then taken off. Yifan had planned to land the shuttle there and investigate the traces left by the spacecraft, but he and Cheng Xin had not anticipated that the mysterious visitors would leave behind such large signs that they were visible from space.

“What is that ?” Cheng Xin cried out.

“Death lines.” Yifan recognized them right away. “Don’t get too close,” he said to the AI.

He was referring to five black lines. One end of each line was connected to the surface of the planet, and the other end extended into space, like five black hairs growing out of Planet Gray. Each line stretched higher than Hunter ’s orbit.

“What are they?”

“Trails left by curvature propulsion. Those lines are the result of extreme curvature manipulation. The speed of light within the trails is zero.”

On the next orbit, Guan Yifan and Cheng Xin entered the shuttle and descended toward the surface. Due to the low orbit and the lack of an atmosphere, the descent was smooth and fast. The shuttle landed about three kilometers from the death lines.

They leapt across the surface under 0.2G. A thin layer of dust covered the surface of Planet Gray, along with gravel of various sizes. Due to the lack of atmospheric scattering of sunlight, shadows and lit areas were sharply delineated. When they were about a hundred meters from the death lines, Yifan waved Cheng Xin to a stop. Each death line was about twenty or thirty meters in diameter, and from here, they resembled death columns.