“Wait,” Namir said, and it was like a command. “Suppose we don’t want to take your shortcut? Maybe we’d rather continue as planned and have those years to prepare for meeting your people.”

“They aren’t mine, and they aren’t people,” Spy said. “If all of you would prefer the old slow way, tell me now. I will ask the Other-prime.”

Meryl spoke up first. “Not me. The sooner the better.”

Dustin nodded slowly. “Me, too.”

“Paul?” I said.

He tugged on his ear, a sign that he was conflicted. “Spy . . . we know our technology has worked this far. I can understand Namir’s reluctance to try something new and untested. Just on your say-so.”

“I won’t argue with you.” It was looking at Namir. “But technology is not involved at all. It’s just that the way you experience time is connected to the way you think about time, and that is flawed.”

“And you can change that?” I said. “The way we think about time?”

“No, no, no. The bird does not have to build the elevator to ride in it.”

He moved his gaze to Paul. “What it is . . . Let me put this as simply as possible. We are—or you and the Other-prime are—here together in a definite place in space and time. In a simple Einsteinian way. Twelve years from now, you will again share a place in the space-time continuum. Share a point. So what connects those two points?”

I remembered that from school. “A geodesic,” I said, simultaneously with Paul and Namir.

“Exactly,” it said, and looked at the two Martians. “A geodesic in space-time is something like a line drawn between two points on a map.”

Fly-in-Amber sketched a line with his finger. “The shortest natural distance.”

Spy nodded. “True and not true. There’s only one shortest line between the two points, but there are many geodesics. It gets complicated if you have gravity and acceleration.”

“But there’s no magic wand,” Paul said. “You’re talking about going from here to there, a really long distance, with no time elapsing. That’s not possible, no matter how fast you go.”

I think that was the only time I ever saw Spy laugh. “Tell that to a photon. Or tell it to me tomorrow. Which will be twelve years from now, after a trip of no duration.”

“Unless we refuse your offer,” Namir said.

“Like the bird refusing to enter the elevator? I’m afraid you’re already in the net. As I said, I could ask the Other-prime to set you free, but at least two of you do want to take the shortcut. How about you, Carmen?”

“Wait. What if something goes wrong en route? The hydroponics spring a leak or the ship’s guidance system lets a pebble through? We won’t be able to deal with it.”