The Breach - Ghost Country - Deep Sky

the network. Which makes sense, when you think about it. If you strung the universe with these tunnels, you’d never know when some hostile race might evolve somewhere, punch in and show up in your backyard.”
    “So how do you go through it?” Bethany said.
    “You need a tumbler,” Garner said.
    Everyone waited for him to go on.
    “That’s the best stab at translating the word from their language—whoever built the tunnels. Tumbler, as in the mechanism inside a lock. The way it works is, any two points connected by a tunnel need to be authorized before someone can travel between them. Think of it as unlocking them. And the only way to do that is for a single individual—a single conscious mind—to think the same complex thought outside both entry points first. You see how that works? It means at least one person has to make the trip the old-fashioned way—in a ship—before the tunnel lets anyone through. So you’d open one entrance, think a specific thought near it—an exchange from Twelfth Night, say—and then chug across space at ship speed to the other entrance, and think the exchange again. Same mind, same thought—that’s what the tunnel listens for. Until it hears that, it won’t open.”
    Travis thought he understood the concept, and the reasoning behind it. “It means no new civilization can come out of the blue and expand their presence in space too quickly, right? They can’t push their boundaries any faster than ships can travel.”
    Garner nodded. “And a person stuck with that job, unlocking a tunnel’s two ends, is the tumbler. In this case it’s you. I’m sure you can guess why.”
    Travis considered it. He stared at the seatback in front of him, then turned to Garner. “Because I’ve already made the trip. There’s one of me on that end already, and one of me on this end.”
    Another nod.
    “Will that actually work?” Travis said.
    “Same mind, same thought,” Garner said.
    “So what is the thought? Did they put it in the message?”
    Garner shook his head. “They’ll give it to you in person. After you go through to their end.”
    He watched Travis for the confusion he obviously expected. Travis saw Paige’s and Bethany’s eyes narrow too.
    “How will you go through the tunnel if you haven’t unlocked it yet?” Garner said. “That’s another safety—one for the tumbler’s own protection. The term for it translates to something like ‘scouting.’ You get to do it just once, back and forth—a single round-trip. The logic of it goes like this: a tumbler usually has to unlock a tunnel’s first end, then travel for a very long time across space to unlock the second end. But before he unlocks the second end, he can choose to enter the tunnel there, just once, and go through it to take a good look at the first end again. To scout it.”
    Travis saw the point—was pretty certain he did, anyway. “After all that time had gone by, while you were crossing space in a ship, it’d be risky to reach the far end of the tunnel and just open it blindly. What if things back home had changed by then? What if there was something dangerous waiting to come through?”
    Garner managed a smile. “Hell, you might open the tunnel and get a magma flow. Or seawater pressurized at a mile’s depth. A lot can change, given enough time, and it could take thousands of years for a ship to travel the distance required. It could take longer. The Deep Sky’s crew isn’t worried about that in this case, obviously. As far as I can tell, they just want to speak to you before you fully open the tunnel. About what, I have no idea.”
    “So the other me,” Travis said, “the one aboard the Deep Sky, will unlock the far end of the tunnel first, and once that’s done, I can make a single trip to their side and back. A scouting trip.”
    “That’s the plan, as I understand it.”
    Travis stared at him, thinking it all through. Random questions remained. Trailing ends. One in particular.
    “Tell us about the filter,” Travis said.
    Garner looked surprised. “How can you know about that?”
    “Beyond that word, we don’t know about it,” Travis said. “I’ll explain the how later.”
    He held Garner’s gaze and waited for him to speak.
    “I don’t know much more than you do, I’m afraid,” Garner said. “The filter was always the strangest part, to me. And the scariest, I suppose.”
    “Why?” Paige said.
    Travis noticed Bethany looking around at everyone like she’d