Timeline

26:12:01

Half a dozen hot-air balloons were rising above the mesas in the morning sun. It was now almost eleven o'clock. One of the balloons had a zigzag pattern, which reminded Stern of a Navajo sandpainting.

"I'm sorry," Gordon was saying. "But the answer is no. You can't go back in the prototype, David. It's just too dangerous."

"Why? I thought this was all so safe. Safer than a car. What's dangerous?"

"I told you we don't have transcription errors - the errors that occur during rebuilding," Gordon said. "But that's not precisely accurate."

"Ah."

"Ordinarily, it's true that we can't find any evidence of errors. But they probably occur during every trip. They're just too minor to detect. But like radiation exposure, transcription errors are cumulative. You can't see them after one trip, but after ten or twenty trips, the signs start to be visible. Maybe you have a small seam like a scar in your skin. A small streak in your cornea. Or maybe you begin to have noticeable symptoms, like diabetes, or circulatory problems. Once that happens, you can't go anymore. Because you can't afford to have the problems get worse. That means you've reached your trip limit."

"And that's happened?"

"Yes. To some lab animals. And to several people. The pioneers - the ones who used this prototype machine."

Stern hesitated. "Where are those people now?"

"Most of them are still here. Still working for us. But they don't travel anymore. They can't."

"Okay," Stern said, "but I'm only talking about one trip."

"And we haven't used or calibrated this machine for a long time," Gordon said. "It may be okay, and it may not be. Look: suppose I let you go back, and after you arrive in 1357, you discover you have errors so serious, you don't dare return. Because you couldn't risk more accumulation."

"You're saying I'd have to stay back there."

"Yes."

Stern said, "Has that ever happened to anybody?"

Gordon paused. "Possibly."

"You mean there's somebody back there now?"

"Possibly," Gordon said. "We're not sure."

"But this is very important to know," Stern said, suddenly excited. "You're telling me there might be somebody already back there who could help them."

"I don't know," Gordon said, "if this particular person would help."

"But shouldn't we tell them? Advise them?"

"There's no way to make contact with them."

"Actually," Stern said, "I think there is."