Death's End

“I can see that. The moment I entered lightspeed, I felt myself change. I realized that I could, in my lifetime, leap across space-time and reach the edge of the cosmos and the end of the universe. Things that used to seem only philosophical suddenly became concrete and practical.”

“Yes. Things like the fate and goal of the universe used to be only ethereal concerns of philosophers, but now every ordinary person must consider them.”

“Has anyone in the new world thought of going to the end of the universe?”

“Of course. Five ultimate spaceships have already been launched.”

“Ultimate spaceships?”

“Some call them doomsday ships. These lightspeed ships have no destination at all. They turn their curvature engines to maximum and accelerate like crazy, infinitely approaching the speed of light. Their goal is to leap across time using relativity until they reach the heat death of the universe. By their calculations, ten years within their frame of reference would equal fifty billion years in ours. As a matter of fact, you don’t even need to plan for it. If some malfunction occurs after a ship has accelerated to lightspeed, preventing the ship from decelerating, then you’d also reach the end of the universe within your lifetime.”

“I pity Solar System humans,” said Cheng Xin. “Even at the very end, most of them lived lives confined to a tiny portion of space-time, like those old men and women who never left their home villages during the Common Era. The universe remained a mystery to them until the end.”

Yifan lifted his head to gaze at Cheng Xin. Under 3G, this was a very strenuous exercise. But he persisted for some time.

“You don’t need to pity them. Really, let me tell you: don’t. The reality of the universe is not something to envy.”

“Why?”

Yifan lifted a hand and pointed at the stars of the galaxy. Then he let the 3G force pull his arm back to this chest.

“Darkness. Only darkness.”

“You mean the dark forest state?”

Guan Yifan shook his head, a gesture that appeared to be a struggle in hypergravity. “For us, the dark forest state is all-important, but it’s just a detail of the cosmos. If you think of the cosmos as a great battlefield, dark forest strikes are nothing more than snipers shooting at the careless—messengers, mess men, etc. In the grand scheme of the battle, they are nothing. You have not seen what a true interstellar war is like.”

“Have you?”

“We’ve caught a few glimpses. But most things we know are just guesses…. Do you really want to know? The more you possess of this kind of knowledge, the less light remains in your heart.”

“My heart is already completely dark. I want to know.”

And so, more than six centuries after Luo Ji had fallen through ice into that lake, another dark veil hiding the truth about the universe was lifted before the gaze of one of the only survivors of Earth civilization.

Yifan asked, “Why don’t you tell me what the most powerful weapon for a civilization possessing almost infinite technological prowess is? Don’t think of this as a technical question. Think philosophy.”

Cheng Xin pondered for a while and then struggled to shake her head. “I don’t know.”

“Your experiences should give you a hint.”

What had she experienced? She had seen how a cruel attacker could lower the dimensions of space by one and destroy a solar system. What are dimensions?

“The universal laws of physics,” Cheng Xin said.

“That’s right. The universal laws of physics are the most terrifying weapons, and also the most effective defenses. Whether it’s by the Milky Way or the Andromeda Galaxy, at the scale of the local galactic group or the Virgo Supercluster, those warring civilizations possessing godlike technology will not hesitate to use the universal laws of physics as weapons. There are many laws that can be manipulated into weapons, but most commonly, the focus is on spatial dimensions and the speed of light. Typically, lowering spatial dimensions is a technique for attack, and lowering the speed of light is a technique for defense. Thus, the dimensional strike on the Solar System was an advanced attack method. A dimensional strike is a sign of respect. In this universe, respect is not easy to earn. I guess you could consider it an honor for Earth civilization.”

“I thought of something I wanted to ask you. When will the collapse of space in the vicinity of the Solar System into two dimensions cease?”

“It will never cease.”

Cheng Xin shuddered.

“You are scared? Do you think that in this galaxy, in this universe, only the Solar System is collapsing into two dimensions? Haha…”

Guan Yifan’s bitter laughter caused Cheng Xin’s heart to seize up. She said, “What you’re saying makes no sense. At least, it doesn’t make sense to lower spatial dimensions as a weapon. In the long run, that’s the sort of attack that would kill the attacker as well as the target. Eventually, the side that initiated attack would also see their own space fall into the two-dimensional abyss they created.”