Schild’s Ladder

was left to others to tackle the problem decades later, the far side would have swallowed entire star systems?—?at the very least, Mimosa itself. If they acted now, they could send it flying out of inhabited space even faster than it was expanding.

When the border hit the femtomachine, they would have a chance to interact with it, but no fleeting, localized encounter would be sufficient to sculpt the borderlight into a propulsion system. They needed to buy themselves more time. Matching the border’s velocity would have been ideal, but there was no prospect of achieving that. Their only hope was to find a way to keep working on the problem after the far side had swallowed them.

The Mimosans had choreographed a bravura quantum maneuver that would allow the femtomachine to inject a partial clone of itself through the border, and rotate all of its amplitude into the successful branch at the same time. But the passengers couldn’t all pass through. The bulk of the femtomachine would have to become a device whose sole purpose was to implement the move, and only the acorporeals were structured in a way that gave them the power to rewrite their minds right out of existence, converting themselves into pieces of the quantum catapult. All seven had been needed, to make it work. Cass had been left to go in alone.

The first part of the plan had succeeded: the core of the original femtomachine had been re-created, in miniature, in the far side. But it had not been as mobile as its designers had hoped, and Cass had been trapped by changing conditions, hundreds of times. She had kept struggling to get the Oppenheimer into position, proceeding in fits and starts, but the vehicle’s hull had become compromised, vendeks had flooded in.

If this had happened in the ferment of the Bright, Tchicaya doubted that any trace of the crippled machine would have remained a picosecond later, but the massed invasion by a single, tenacious species had effectively fossilized it whole. An unknown time later?—?near-side decades, or centuries?—?a group of intelligent xennobes had found the wreck. Subject to the same infestation themselves, they had revived the Oppenheimer with a vendek bred specifically to reverse the effects of the first.

Awake, but still trapped?—?nothing could remedy the fact that her vehicle was too primitive for the constantly evolving terrain?—?Cass had begun trying to communicate with her benefactors. Her own first message had taken the form of a layer population, vibrating, counting out the primes. From there, it had been a long, arduous process, but they’d eventually reached a point of limited mutual understanding.

Then the xennobes had vanished, prey to some shift in climate or culture; she had never discovered the reason. After decades had passed, another, related group had appeared, aware of the previous encounter, but speaking a different language themselves, and too impatient to learn to communicate properly. They had tried to carry her toward the border?—?knowing that this had been her original goal?—?without really understanding her nature. Moving anything through the far side was a delicate process, and their technology had not been up to the task. The Oppenheimer had become trapped again, damaged again. Invaded, frozen, and abandoned.

That was her last experience before waking on the deck of the Sarumpaet. She had no way of knowing whether the Oppenheimer had been towed here by the builders of the city, or whether the city had grown up around it.

Tchicaya was humbled; everything he’d been through was a stroll in the desert by comparison. He couldn’t even offer her the comfort of hearing that her own failed mission had been completed from the outside.

But he had to press on. As gently as he could, he began explaining what had happened on the near side. Cass had long ago faced up to the likelihood that her actions had destroyed whole worlds, but she’d had no way of knowing how much time had passed, and he could see the wounds reopening as he described the numbers, the scale of the evacuation.

He compressed the machinations of the factions on the Rindler to the briefest sketch, but he made one thing clear: the vast majority of people had never intended to destroy sentient life in the far side. Most still wanted the incursion to be halted, but not at the cost of genocide.

For all the bad news that accompanied it, understanding the Sarumpaet's presence seemed to solidify Cass’s sense of reality. She could connect herself to the near side again. She could imagine something other than exile, and madness.

When Tchicaya finished speaking, she stood. “You want them to evacuate the Bright, so you can trap the Planck worms there?”

“Yes.”

“And you’d like me to translate that message?”

“If you can.”

“I’ll need to be able to create vendeks,” Cass explained. She had invented her own terminology for everything, but Tchicaya’s Mediator was smoothing over the differences. “I don’t understand the perceptual physiology, but there’s a family of short-lived vendeks related to the parasprites that my first xennobe tribe employed for communication. Though what their descendants will make of any of this, I don’t know.”

Mariama worked with the toolkit to sort out interfaces with the software Cass had used back on the Oppenheimer to create the communications vendeks. While this was happening, Tchicaya rehearsed scenarios with her, possible responses from the Colonists. He wasn’t entirely sure why she wanted this, but she appeared to be afraid of being caught out, unprepared.

“Everything’s ready,” Mariama declared. “As much as it will ever be.”

They moved the Sarumpaet right up to the ruins of the Oppenheimer. The Colonists were still patiently looking on as the banner flashed out its mathematical lexicon.

Cass said, “I hope they really are expecting this. If I waved a papyrus at Tutankhamen and he started speaking to me, I’d probably run screaming from the room and never come back.”

She sent the first vendeks out from the ship.

The scape painted a burst of color spreading out around them, fading rapidly as it moved. These vendeks did not last long in the room’s environment; to Tchicaya’s eyes, the signal looked faint by the time it reached the Colonists.

It was not too faint for them to notice. They sprang into action, gathering more equipment. If the Bright had made them feign constant excitement, this was the real thing; Tchicaya hadn’t seen their bodies convulse so much since they’d descended from the surface of the outpost.

Reassembled in a huddle, armed with their additional machinery?—?recording devices, translators??—?they finally found a reason to talk back.

Tchicaya wasn’t privy to the exchange. Cass didn’t talk aloud in her own native language, offering up sentences for direct translation, nor was there any running translation of the replies. She had never got far enough to integrate the xennobe language into the usual, Mediator-based scheme of things; she was working from her own mental dictionary of signals, memories of past conversations, brute-force software assistance, and guesswork. She made gestures with her body, frowned to herself, and emitted grunts and sighs, but most of the action was going on inside her simulated skull.

After almost twenty minutes, she paused to give the two spectators a brief commentary. “They expected me to speak in an ancient language, but they weren’t quite sure which one it would be. We’ve sorted that all out now.” She looked ragged, but she smiled.

Tchicaya was about to launch into a stream of lavish praise, but Mariama replied calmly, “That’s good.”

Cass nodded. “I think they trust me, more or less. At least they’re willing to listen.”

She resumed the conversation. Vendeks washed back and forth between the Colonists and the flea masquerading as a resurrected mummy.

More than four hours after the exchange had begun, Cass sat down on the deck and cradled her head in her arms. Three of the Colonists left the chamber.

Tchicaya waited. There’d be a reason for the hiatus: the Colonists were fetching another language expert, another translation device, a better dictionary.

Cass looked up suddenly, as if she’d completely forgotten that she was no longer alone.

“It’s done,” she said. “They understood me.”

The Bright itself was of little value to their hosts, she explained, but it did contain several outposts from which they’d been attempting to learn more about whatever lay beyond. They hadn’t constructed the signaling