Death's End

Chu Yan pointed in the direction they had come from. Morovich and Guan saw those tubes again, which now also lay open so that all the liquids flowing through them could be seen clearly. Inside the spherical region, the tubes were curved and distorted, and the sphere appeared like a drop of dew hanging on a spiderweb. This was different from how the region had appeared in three-dimensional space. There, the warped point didn’t refract light, and so appeared completely invisible. Its presence could only be made known via the disappearance of objects that had entered four-dimensional space inside the bubble.

“If you come here again, you must wear space suits. Novices can’t always tell locations accurately, and finding a new warped point for the return trip might result in landing outside the ship in three-dimensional space.”

Chu Yan indicated that the other two should follow, and entered the dewdrop-like bubble. In an instant they were back inside the three-dimensional world, back in the corridor inside the ship, in exactly the place where, ten minutes ago, they had entered four-dimensional space. In fact, they had never left—the space they were in had just gained an extra dimension. The round opening in the bulkhead was still there, and they could still see the “broken” tubes inside.

But to Morovich and Guan, the world no longer seemed familiar. They now experienced the three-dimensional world as narrow and smothering. Guan dealt with it slightly better—he had at least experienced four-dimensional space once before, in a semiconscious state. But Morovich was feeling claustrophobic, as though he was being suffocated.

“This is normal. You’ll get used to it after a few times.” Chu Yan laughed. “The two of you now know what real vastness means. Even if you put on space suits and go take a walk in space now, you’ll feel confined.”

“How did all this happen?” Morovich tore open his collar and gasped.

“We entered a region of space where space has four dimensions. That’s it. We call this region a four-dimensional fragment.”

“But we’re in three-dimensional space now!”

“Four-dimensional space contains three-dimensional space, just as three-dimensional space contains two-dimensional space. To make another analogy: We’re located inside a three-dimensional sheet of paper in four-dimensional space.”

“Let me propose a model,” said Guan excitedly. “The entirety of our three-dimensional space is a large, thin sheet of paper, sixteen billion light-years across. Somewhere on this sheet of paper is a tiny, four-dimensional soap bubble.”

“Perfect, Dr. Guan!” Chu Yan clapped Guan’s shoulder, making him tumble in weightlessness. “I’ve been trying to come up with a good analogy, and you hit it in one try. This is why we need a cosmologist! You’re exactly right. We were on this three-dimensional sheet of paper, crawling over the surface. Then we came into the soap bubble. From a warped point, we can manage to leave the surface of the paper and entered the space inside the bubble.”

“Though we were in four-dimensional space just now, our bodies remained three-dimensional,” Morovich said.

“That’s right. We were flat, three-dimensional people drifting in four-dimensional space. It’s not clear how our bodies are able to survive in four-dimensional space, given that the physical laws are likely different. There are many such mysteries.”

“What exactly are warped points?”

“The three-dimensional sheet of paper is not completely flat everywhere. Some places are warped, reaching into the fourth dimension. That’s what a warped point is: a tunnel from lower dimensions into higher dimensions. We can get into four-dimensional space by jumping into them.”

“Are there many warped points?”

“Oh yes. They’re everywhere. Blue Space was able to discover their secret earlier because we have more people aboard, and so there were many more opportunities to encounter warped points. Gravity, besides having fewer people, also had a much stricter psychological monitoring regime—even those who encountered warped points dared not discuss them.”

“Are all warped points this small?”

“No. Some are much bigger. There’s one mystery we’ve never been able to solve: We once observed that the rear third of Gravity had warped into four-dimensional space, and stayed there for several minutes. How could you have not noticed anything odd?”

“Well, the last third of the ship usually had no crew. Oh, wait, he was there.” Morovich turned to Guan Yifan. “You must have experienced that. I think I heard about it from Dr. West.”

“I was only half awake. Later, that idiot convinced me that I was only hallucinating.”