Schild’s Ladder

Tchicaya turned away from the control panel. He hadn’t heard Rasmah entering the Blue Room.

“It’s an old joke they used to tell, back on Maeder,” she explained, crossing the wide, empty floor. “Which just goes to show how much work it takes to send a bad meme off to smallpox heaven.”

“Don’t count on having done that,” Tchicaya warned her. “I believe the original version was Everyone complains about human nature. When the second half became patently false, the meme just shifted context. You can tear the meaning right out of these one-liners, and they’ll still find a way to keep propagating.”

“Damn.” She sat beside him. “So what are the laws, right now?”

“As far as I can tell, we have a macroscopic SO(2,2) symmetry, and E7 as the gauge group.” He gestured at the display. “Nothing we haven’t grabbed before, generically, though the details of the Lagrangian are unique.” Tchicaya laughed. “Listen to me. I really am getting blase about this.”

“Seen one universe, seen them all.” Rasmah leaned closer to examine the symmetry diagrams that the software had guessed from some partial results, and was now proceeding to test further with the Left Hand.

She glanced at the endurance clock. “Thirteen minutes? That’s close to the record. You think this might?—?” Tchicaya glowered at her, and she laughed. “Don’t tell me: I’m jinxing the result.”

“Hardly. I’m just growing a little impatient with the idea that we keep grabbing dynamics, over and over, in the hope that one of them will turn out to be stable. It’s never going to happen.”

“You think not?” Rasmah pursed her lips. “Okay. It’s no use just complaining, though. What do you want to do about it?”

Tchicaya made a gesture of helplessness.

She regarded him with disappointment. “Are you this lazy about everything?”

She was only teasing, but the accusation stung. Rasmah had been on the Rindler just six months longer than he had, but she’d already contributed substantially to several projects. Having helped to design the spectrometer that had been lost with the Scribe, she’d gone on to improve the design still further for the models used in both the Left and Right Hands. The Scribe’s replacement had been planned as a single machine, but when attempts to renegotiate the protocols for its shared use collapsed for the seventh time, even the most ecumenical researchers had lost patience, and agreed to the duplication.

Tchicaya stretched his arms. “I’ve certainly had enough of staring at this for one day. Are you here to take over?”

“Yes.” She smiled and added, “But I’m early, so I’m afraid you can’t actually leave yet.”

The destruction of the Scribe, and the end to cooperation between the factions, had delayed follow-ups to Branco’s experiment, but once the two Hands were in place and gathering data, everybody on the Rindler had been riveted by the results. For months, the Blue Room?—?where the Left Hand’s data was displayed, now that trips to the border were considered imprudent?—?had been packed with people twenty-four hours a day, and it was no secret that the Preservationists had reacted in the same way.

Branco’s technique appeared to have confirmed Sophus’s original assertion: the novo-vacuum did not obey any single analog or extension of the Sarumpaet rules. It was possible to correlate a macroscopic portion of the near side of the border with parts of the total far-side state that did obey specific rules, but each time the experiment was repeated, the rules were different. All of Sarumpaet’s carefully reasoned arguments about which patterns of nodes in a quantum graph could persist as particles had been revealed as utterly parochial; the larger truth was, the ordinary vacuum that dominated the near side was correlated with sequences of graphs that behaved in that particular fashion, so it hid the fact that they were really just part of a superposition of countless other possibilities. The quantum subtleties that could, in principle, render the whole superposition visible were buried in the sheer number of details that would have had to be tracked in order to observe it.

The far side lacked the means to conceal its quantum nature in the same fashion, but if the view was less misleading, it remained confusing. Interpreting the new experiments was like trying to make sense of a jungle by watching an endless parade of exotic creatures cling briefly to the windows of a vehicle, stunned by the light, curious, or angry, but always flying off a moment later, never to return.

At first, every new set of laws had had their fifteen minutes of fame, but since none of them could be pinned to the near side for much longer than that, the novelty had begun to wear thin. Exhilaration at the cornucopia had given way to frustration. The experiments continued, but it had become a struggle to maintain even the symbolic presence of one sentient observer around the clock. Tchicaya supposed that this was fair enough: all the theorists were drowning in data already, and they had better things to do than sit and watch more come pouring in. For a week or two, he’d hoped that patient observation might actually lead him to a worthwhile discovery himself, but that was beginning to sound as crazy as looking for patterns in any other set of random quantum results.

“Oh, there it goes!” Rasmah wailed, as if she’d seriously expected otherwise. The patch of the border they’d pinned to the latest set of laws had just reverted to the old inscrutable glow. “What do you think would happen,” she mused, “if we scribed some device that could function under the far-side dynamics, before we lost the correlation?”

Tchicaya said, “Even if it survived, what good would that do us? We’ve never been able to grab the same dynamics twice.”

“What if we scribed a Scribe?”

“Ha! Like that Escher drawing?”

“Yeah.” Rasmah pulled a face, suddenly aghast. “Though…that’s a left hand drawing a right, and vice versa. We can’t have that, can we?”

“Are you serious, though? Do you think we could insert a machine that could signal back to us in some way?”

Rasmah didn’t reply immediately. “I don’t know. What does the border look like, from the other side? Does it always look as if our physics is happening behind it? Or is something more symmetrical going on, where someone on the far side would catch glimpses just as varied and transient as the ones we’re seeing?”

“I have no idea,” Tchicaya admitted. “I don’t even see how you could pose that question, in Sophus’s model. You’d have to describe a specific observer on the far side, on whose terms you wanted to see things. But if the different far-side dynamics don’t form decoherent branches?—?except over the tiny patches where we’re forcing them to do so?—?what exactly are the laws the observer is supposed to obey?” The startled birds and butterflies fluttering against the window weren’t even real; it was no use asking what they saw, staring back. The slices of different “universes” pinned against the border were more like the patterns formed by splattered insects. If they hadn’t been dead, they would never have been seen side by side in quite the same way.

It was midnight, by the Rindler's arbitrary clock. The lighting of public spaces changed with the cycle, and though many people happily slept through the daytime and worked all night, Tchicaya had ended up in synch with the light.

He stood. “That’s it, I’ve had enough.”

“You could stay and keep me company,” Rasmah suggested.

“I wouldn’t want to distract you.” He smiled and backed away, raising a hand good night. They’d been circling each other at a distance for weeks, and his body had begun to change for her, but Tchicaya had decided that he would not allow anything to happen between them. While it would have been unlikely to end as swiftly, or as comically, as his experiment with Yann, he wanted to keep his life free of complications.

Tchicaya made his way around the ship, slightly removed from everything around him. The corridors were nearly deserted; maybe the Preservationists were having some kind of conference. The ghost town ambience reminded him of a hundred provincial cities he’d trekked through at night; on the empty walkways, the blaze of stars was like the view when you left the brightest streets behind, and the sky came suddenly to life.

He recalled a night he’d spent in a small town on Quine, thirty-six subjective years after he’d left Turaev: the mirror image of his birth in the moment of his departure. Three centuries had passed, in real time. He’d sat in an alley and wept for hours, like an abandoned child. The next day, he’d made half a dozen new friends among the locals, and some of the friendships had lasted three times longer than all the years he’d spent on his home world.

He still missed those people. He still missed Lesya, and his children and grandchildren on Gleason. And yet, he could never entirely separate that from the realization that part of the joy he’d felt in their presence had come from the sense that they were lifting him out of his state of exile. They had never been substitutes for the home and