Schild’s Ladder

layer; they’d heard stories about the artifact, which had supposedly been built by an earlier civilization, but they had never had the means to verify its existence. They couldn’t quite comprehend the nature of the threat she had described, but they did believe that she came from the outer reaches, and they had decided that they had nothing to lose by erring on the side of caution.

They would permit the creation of the tar pit. They would begin evacuating the Bright immediately.

The Sarumpaet rode the highway loop back into the Bright, escorted by Tannsjo and Hintikka?—?Cass’s names for two of the Colonists who’d traveled down from the outpost with the banner. She’d explained to them that she’d moved from the wreck of her old vehicle into this new, smaller model, brought here by two colleagues who’d traveled all the way from her home; they found many aspects of this account baffling, but didn’t expect to make sense of it until they’d learned much more. The legends about her had been full of obvious nonsense that they’d hoped to dispel, but they were patient, and they could wait for a more complete understanding.

“Do they know you’re their creator?” Mariama asked.

Cass snorted. “That would be an overblown claim for me to make, when I didn’t have the slightest idea what I was creating. But I haven’t told them anything about Mimosa. All I’ve ever said is that I came into their world to try to keep it from colliding with my own.”

The outposts in the Bright were all located unfavorably for their purpose, so they left the highway at a brand new ramp that Tannsjo and Hintikka fashioned from within, with tools they’d brought along for the purpose. Even more impressively, after forming the exit, the Colonists sent a signal into the structure that began to shift its operation into reverse. This expedition would not be able to get home by completing the loop in the original direction, and apparently it had never occurred to the highway-makers to have two opposing lanes running side by side.

The Bright was exactly as Tchicaya remembered it, but he had never expected to see Planck worms bearing down on him again the way they had in the honeycomb, unless it was at the moment before his death. The Bright was some three centimeters deep, but the Colonists had never mapped its limits in latitude or longitude. Tchicaya could only hope that if other xennobe civilizations unknown to the Colonists had sent their own explorers into the region, they’d see the tar pit coming, and flee.

The Sarumpaet launched the seed; it disappeared into the haze. For several minutes, there was nothing. Then an ominous sprite shadow appeared, a gray stain spreading across the sky.

This was as much as they could afford to witness. The Colonists would monitor the tar pit from below, but they would not see anything of the battle, if it was won here.

Tannsjo and Hintikka led the way back.

Once they were in transit, the highway sealed behind them, Tchicaya asked Cass, “What do they make of the fact that some near-siders almost wiped them out?”

“I told them that the top of the Bright was encroaching on our homes,” she said, “which alarmed us, and made some of us act in haste. I think they could empathize with that; shifting weather’s been known to have the same effect on people here, now and then. But I gather they’re still a bit skeptical about the notion that the Planck worms could have killed everything in their path. They’re also puzzled that the advance of the Bright could be such a big deal to us?—?given that we come from somewhere even more hostile.”

Mariama said, “Do they understand that the border’s still encroaching? That we’re still losing territory?”

“Yes,” Cass replied. “But they’ve offered to work with us, to do what they can to find a solution.”

Tchicaya was bemused. “Don’t you think that problem is a bit beyond them?” The toolkit had found no way to freeze the border. All the evidence suggested that the expansion was unstoppable.

Cass said, “Of course it is, right now. But they’ve come from nothing, to this'?—?she gestured at the highway around them?—?'in just six hundred years. Give them another near-side month or two, and they’ll definitely be the ones leading the way.”

They returned to the place Mariama had named Museum City. The tar pit would take time to stabilize, and until the Planck worms had either been trapped and killed, or failed to show up entirely, it would not be safe to try to drill through the mess and make contact with the border.

It had been less than a millisecond since the Sarumpaet had begun its flight. Tchicaya enjoyed imagining his own startled near-side version hearing the news that the Planck worms had been defeated, before he’d even had time to grow anxious about the fate of the mission. He’d made no firm plans for reversing his bifurcation, since he’d never really expected to return, but the less-traveled Tchicaya would probably be willing to be subsumed. If not, he only hoped that their continued separation would be justified, and they didn’t merely dog each other’s footsteps. If they both tried to meet up with Rasmah it would be awkward, though Tchicaya had little doubt which one of them she’d choose.

Cass gave Mariama xennobe language lessons. Tchicaya sat in on them, but he found them heavy going. Mariama made her own copy of the vendek-based communications software and began converting it into something a Mediator could work with, but filling in the gaps and formalizing the structures of the language was a huge task.

Tchicaya had expanded the Sarumpaet's scape, building rooms beyond the observation deck, giving all three passengers privacy. He began sleeping more, eight or ten hours in every ship- day.

Mostly, he dreamed that he was back on the Rindler. It was strange to feel pangs of nostalgia, not for solid ground and blue skies, but for stars and borderlight.

The Colonists were intensely curious about the aliens, and eager to explain their own world to them. They dragged the Sarumpaet from group to group, place to place; if Cass had let them, they probably would have taken her on a tour of every city in their realm, talking to her nonstop all the way. In near-side terms, their history only stretched back about a year, and they had only explored a few thousand cubic kilometers of the far side, but by any local measure their civilization was orders of magnitude vaster than all of inhabited space. And they were far from alone: they’d had direct contact with twelve other sentient species, and they had secondhand knowledge of hundreds more.

Tchicaya listened to Cass’s translations, and marveled at the things they were learning, but he could see how weary she was becoming, and he felt both a protective sympathy for her, and a lesser, parallel exhaustion of his own. He had dived into the far side unprepared, and whether or not he eventually made it his home, he needed to come up for air.

On their fifty-third night in the city, Mariama woke him, standing by his bed, shaking him by the arm. He squinted at her and willed the scape to grow brighter.

“It’s about Cass.”

He nodded. “She has to get out soon. The minute the tar pit’s safe to traverse, we need to start drilling.”

Mariama sat on the bed beside him. “She’s started talking to me about staying on. Seeing out her original project, in some form or other: freezing the border, pushing away the far side. Whatever can be done to stop the evacuations.”

Tchicaya was horrified. “That could take centuries!” He only meant far-side time, though on reflection he wondered if that wasn’t optimistic.

Mariama said, “I don’t know what she’s thinking. That they’ll crucify her outside, if she dares to emerge without a solution? Or maybe it’s more personal. Either way, I don’t think she can hold out that long. It’s too open- ended, and she’s taking it all too personally. She’s already been through enough. Will you try to talk some sense into her?”

“Sure.”

“Thanks.” Mariama smiled. “It’ll come better from you. I’d sound too much like someone who’s simply angling for her job.”

Tchicaya wondered for a moment if he’d misunderstood her, but she’d managed to be oblique without the slightest hint of ambiguity.

“Why do you want her job?” he said.

“I’m ready for this,” Mariama declared. “It’s exactly what I came to the Rindler to do.”

“You came to the Rindler to work with Tarek on Planck worms!”