Garner seemed to understand. “It’s probably best if you don’t meet yourself,” he said. “It’s not going to split the universe or anything, but I think it would be very distracting.”
He had an accent—one Travis was sure he’d never heard before. Nor had anybody else in 2016, he knew.
Garner stepped from the doorway and advanced. He smiled vaguely and shook his head. “I haven’t seen someone look this old in over a thousand years.”
They stood at the center of the gigantic floor pane and spoke at length. Travis told Garner, in broad strokes, the story of the Breach as it’d played out on Earth. All that had resulted from that day in March of 1978. All that this version of Garner couldn’t know about—the aftermath of the plan he and the others had conceived and launched from this ship. The man looked disturbed, even remorseful, by the time Travis reached the end. He stared away into the starfield below—the planet and twin suns were no longer in view—and exhaled slowly.
“We knew it would go bad in a lot of ways,” Garner said softly. “We debated whether to do it at all. But in the end the decision was unanimous. We had the chance to set things right. How could we pass it up?”
He stood staring into the depths a moment longer, and then he drew a folded black card from his pocket and handed it to Travis. “Don’t open that until you’re ready. Inside is a long string of random letters, which your counterpart here has already thought. Once you return to
“And to do that, I just think what’s on this card,” Travis said, more verifying than asking.
Garner nodded. “It’ll work best if you read it aloud—that should keep your stream of thought on track. Other than that, there’s nothing to it. You can do it from anywhere on Earth, anytime after you go back. You read those letters, and the tunnel opens for us to come through. Easy as that.”
Travis looked at the card. He thought of the disparity between its size and its power. Like a nuclear launch key. He slipped it into his pocket, then looked back up at Garner.
Garner was gazing down through the window again. Watching the edge where stars were continually sliding into view. Travis realized he was waiting for something.
At last the man pointed. “There.”
Travis followed his downstretched arm and fingertip and saw a medium-bright yellow star that’d just crept into the frame. At a glance there was nothing special about it. It was all but lost amid the scatter of other stars.
“Is that what I think it is?” Travis said.
Garner nodded and spoke just above a breath. “There’s not a day I don’t come to this room and look at it. I stare at that little speck, and I wonder if there’s anything left of the Ferris wheel on Navy Pier in Chicago, or the Ko?toku-in temple in Tokyo, or Nelson’s Column in Trafalgar Square. And I’ll never know.”
“Can you actually change things?” Travis said. “If all of you come through to 2016, do you really believe you can rewrite history? And if you can, how do you know you’ll make it better? Couldn’t the same kind of war still happen someday, for other reasons?”
It took a long time for Garner to answer. His eyes and his head slowly turned, tracking the distant pinpoint of light in the endless black. He was still watching it when he began to speak.
“I can tell you about dozens of close calls the world has scraped past, these last twelve hundred years. Any one of those could’ve ended it. Finally one did. It was a matter of time.” Far below the curved glass, the giant gas planet crept back into view. First came one horn of the lit crescent, and then the broad curve. The mostly dark mass of the thing blotted out the stars beyond it like an ink spill. “There are fundamental problems that never seem to go away,” Garner said, “no matter how advanced the world becomes. No matter what you invent. No matter what you cure. You never get rid of things like denial, in-group and out-group thinking, cognitive dissonance. The things that underlie every conflict and every war. There are always people who
“But is that enough to change things forever? A few hundred of you, among a few billion?”
Travis watched Garner and saw something in his eyes, flickering beneath the conviction with which he’d just spoken. A vestige of his earlier remorse, maybe.
“No,” Garner said. “It takes more than that.”
Travis found himself speaking the word even as he thought it: “The filter.”
Garner nodded just perceptibly. “How much do you know about it?”
“Almost nothing,” Travis said.
Seconds passed. Garner looked away. “A few minutes ago you told me about a computer called the Blackbird. Alien technology that you repurposed in some other timeline. A machine that can make hyper-accurate predictions, even about random events that haven’t happened yet.”
Travis waited for him to go on.
“We found computers just like that,” Garner said, “governing the hubs of this tunnel network.” He indicated the massive planet, already slipping back out of view. “You can’t see it from here, but there’s an object the size of Long Island orbiting just above the cloud tops down there. An artificial satellite. We managed to board it soon after arriving in this system. The best we could tell, it’s a way station of some kind, connecting hundreds of these tunnels to one another. The place is filled with old electronics, some of it running down, most of it still working. There’s automated maintenance overseeing everything critical, and based on certain timers we were able to decipher, we figure the thing’s been abandoned for just over three billion years.”
Travis tried to get a sense of time on that scale, but gave it up after a few seconds.
“Huge areas of the satellite are just stores of backup supplies,” Garner said. “Including computers. We took one, brought it aboard this ship, and spent about fifty years learning everything we could about it. Learning that it does its computation by interacting with surrounding material.
“A whole planet’s worth,” Travis said. “The Blackbird told me that at the end.”
Garner nodded. “Once we understood that part, we realized there was a certain function we could use this computer for, if we ever made it back to Earth through one of these tunnels—back to Earth during your time. This function was very difficult to set up; it’s nothing you could’ve done with the Blackbird. The programming alone took us two decades. Then we ran thousands of simulations of how it would play out in real life once we triggered it. How it would work on Earth.”
“How
“We called it the filter. I don’t remember who came up with that name, but it stuck. I guess it made the idea sound clean.”
“What does it do?”
Garner remained silent for a while. He didn’t look at Travis. Beneath him, the planet slipped away again, leaving only the tumble of stars.
“There’s a question philosophers used to ask,” Garner said. “Maybe you’ve heard some version of it. Suppose you suddenly found yourself on a street corner in Europe, in the year 1895, and encountered a six-year-old boy named Adolf Hitler. Could you kill him, right then and there?”
“You’re asking?” Travis said.
“Sure.”
Travis thought about it. “I really don’t know. I’d think I
Garner nodded. “That’s a common answer. Let’s say you did kill him. Do you believe World War Two would be prevented as a result?”
Travis shrugged. “I’m sure there’d still be a fight about something around that time.”
