Schild’s Ladder

withdraw from the debate entirely, as the other seven had, but Tchicaya understood his refusal to do so. The fate of the vacuum had to be argued on its merits, not treated as a surrogate through which its creators could be condemned or absolved, and Yann intended the fact that he’d dared to take sides to highlight that distinction.

“So there’s been no theoretical progress while I was in transit?” A definitive breakthrough would have been the first thing Yann mentioned, but there might still have been promising developments.

Yann shrugged. “Three steps left, four steps down. We scribe these elaborate probe graphs and drop them through the border, then hope that whatever we can see of their decay will tell us something useful. Even when we make an inspired choice of probe and get a clean set of data, as evidence for competing models it’s all hideously indirect.”

In the immediate aftermath of the accident, it had been easy to devise candidates for meta-rules that stabilized both the old and new vacuum in bulk. In those days, the theorists' biggest problem had been an excess of possibilities. The borderlight’s spectrum had helped narrow the choices somewhat, and even the single, fortunate fact that the border was traveling slower than light had ultimately been shown to rule out a class of theories in which the accident had merely changed some particle masses and triggered a boring old Higgs field collapse. In that case, the Mimosan vacuum would have been nothing but a lower-energy version of the ordinary vacuum, and coming to terms with its physics would have been as simple as altering a few numbers in the old equations. A careful analysis, though, had eventually confirmed most people’s instinctive hunch: any single kind of vacuum?—? even one that was undergoing such a collapse?—?had to appear exactly the same to anyone who was coasting through it, an ancient principle known as Lorentz invariance, dating back to the abolition of the aether. The only velocity at which a change could spread while satisfying that criterion was lightspeed.

Since the Rindler had provided a stable platform from which to probe the border experimentally?—?while vividly driving home the point that it was not Lorentz-invariant?—? the embarrassment of riches had proved illusory. Once it had become possible to put the new theories to the test, the only ones that hadn’t been falsified were those that remained too ill-defined to offer clear predictions. That provisional vagueness wasn’t necessarily a flaw, though; it could easily be the case that the correct grand generalization of the Sarumpaet rules simply couldn’t be pinned down from one example of a stable vacuum and a murky glimpse of another, and it was better to be forced to confront that fact than to be lulled for a second time into a false sense of security.

Yann said thoughtfully, “I suppose we could always stop messing about trying to peek behind the border, and just resurrect the Quietener.” He punched his hands together enthusiastically. “A few well-planned experiments in the old style might cut straight to the heart of things.”

“Oh, that’s a great idea. We could do it right here.” A second seeding of the novo-vacuum, from a starting point that was already moving rapidly in the same direction as everyone who was fleeing the first, would be twice as difficult to escape. Yann’s sardonic suggestion was sobering, though, since it was far from being the only way in which the disaster might be magnified. However careful they were, whatever their motives, there was always the chance of simply making things worse.

“We’re dropping the next probe in about twelve hours' time,” Yann said. “If you’re interested, I could probably swing it.”

“Swing what?”

“Bringing you along.”

Tchicaya’s throat tightened. “You mean, you go down there? In person?”

“Absolutely.”

“Why?”

Yann laughed. “Don’t ask me! You’re the one with the flesh fetish; I thought you’d understand. That’s how they do things here. I just play along.”

Tchicaya looked past him, into the opaque pearly light, more featureless than any darkness he’d ever encountered. The eyes relished darkness, conjuring up hints of what it might contain, but the borderlight flooded his vision with incontrovertible blankness.

And he believed he could live in that light? He believed the embodied should end their flight, end their resistance, and march straight into that blinding whiteness?

The borderlight was a surface phenomenon, a distractingly perfect veil. Whatever lay behind it could easily be as richly structured and complex as the universe he knew.

He said, “Let me sleep on it.”

Half the Rindler's sixteen modules were devoted to accommodation. The ship informed Tchicaya of the cabin he’d been allocated, but he declined detailed directions, since Yann seemed eager to continue as his guide.

“I’ll show you where I am, myself, first,” Yann offered. “It’s on the way, and you’re always welcome to drop by.” The accommodation modules were all split into multiple levels; away from the edges, where you could still glimpse the sky, it was like being in a high-rise building. When they left the stairwell, Yann paced briskly down a corridor, and pointed out the room.

Tchicaya’s heart sank. The cabin was divided into two banks of narrow slots, each about a meter wide and half as high. A number of the slots contained inert figures. Rows of handholds between the pigeonholes were apparently intended to assist the occupants in gaining access. Yann followed his gaze and said, “It’s not that hard, once you’re used to it.” He demonstrated, clambering up and sliding into his coffin-sized bunk, the fifth in a stack of eight.

Tchicaya said forlornly, “My embodiment request had the standard clause: if there was no room for me here at full size, the ship was meant to bounce me to the nearest alternative destination. Maybe I’m going to have to start spelling out the meaning of some of those terms.” In four millennia of traveling between planetary surfaces, he’d encountered a wide range of living conditions deemed acceptable by the local people, whether through custom or necessity. On rare occasions, he’d even been provided with deliberately inhospitable accommodation. He’d never seen people squeezed together as tightly as this.

“Mmm.” Yann’s response was noncommittal, as if in retrospect he wasn’t surprised by the complaint, but it honestly hadn’t occurred to him that a newcomer would see the Rindler as cramped. He deftly reversed his insertion maneuver and joined Tchicaya on the deck.

“I’d suggest they ease things by scrapping the garden,” Tchicaya mused, “but given how little difference that would make, they probably should keep it, for sanity’s sake.”

Yann squeezed past him, back into the corridor. Tchicaya trudged after him dejectedly. He’d felt no sense of panic upon waking in the confinement of the crib, but he hadn’t realized he’d soon be moving into something smaller.

He crossed the final walkway with his eyes locked straight ahead, still faltering every ten or fifteen meters when the false horizon became impossible to ignore. He was angry that he was letting these petty tribulations weigh on him. He was lucky: he was used to travel, he was used to change, and he should have been inured to this kind of minor disappointment. Most of the evacuees on the verge of leaving Pachner had lived there all their lives, and change of the kind they were about to confront was something metaphysically foreign to them. Never mind what lay behind the borderlight; those people knew the shape of every rock within a thousand-kilometer radius of their homes, and even if they ended up on a world miraculously similar by any planetologist’s standards, they’d still feel alienated and dispossessed.

As they climbed the stairs, Tchicaya joked, “Let’s head back to the garden. I can sleep in the bushes.” His shoulders were already aching at the thought of having to lie so still. He could modify himself to lose his usual urge to turn over repeatedly as he slept, but the prospect of needing to do that only made him feel claustrophobic in a deeper sense. You could whittle away a hundred little things like that, and not miss any of them individually, but then you woke one day to find that half your memories no longer rang true, every minor joy and hardship drained of its flavor and significance.

“D37, wasn’t it?” Yann asked cheerfully. “That’s left here, then fourth door on the right.” He stopped and let Tchicaya walk past him. “I’ll talk to you again soon about the probe drop, but I’m sure the others won’t object.”

“Yeah. Thanks.” Tchicaya raised a hand in farewell.

The doors he passed were all closed, but the fourth recognized him and opened to his presence.

In front of him stood a desk, two chairs, and a set of shelves. He stepped into the room, and saw one, quite