Грег Иган - Schild’s Ladder

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 family he’d left behind; it had never been that crude. But every kind of happiness bore some imprint in the shape of the pain it had assuaged.

He heard footsteps behind him, outpacing his own. He stopped and turned to face the wall of the walkway, as if admiring the view, wiping his eyes with his forearm, less embarrassed by his tears than the fact that he’d be at a loss to explain them. If he’d still been on Turaev after four thousand years, he would have gone mad. And if he’d traveled and returned in the approved way, to find that nothing had changed in his absence, he would have gone mad even faster. He did not regret leaving.

Mariama said, "You look like you’re about to jump off a bridge."

"I didn’t realize you were following me."

She laughed. "I wasn’t following you . What are we meant to do? Walk in opposite directions around the ship? All Preservationists must march clockwise? That would make for some long journeys."

"Forget it." He turned to look at her. It was unjust beyond belief, but right at this moment — having resolved for the thousandth time that he’d made the right decision — he wanted to rant in her face about the price she’d made him pay. After all her talk as a rebel child, after leading by example, after four thousand years as a traveler, she had now decided that her role in life was to fight to keep the planet-bound cultures — all the slaves she’d vowed to liberate, all the drones she’d promised to shake out of their stupor — safely marinating in their own inertia for another twenty thousand years.

He said, "Where are you heading?"

Mariama hesitated. "Do you know Kadir?"

"Only slightly. We didn’t exactly hit it off." Tchicaya was about to add something more acerbic, when he realized that today was the day Kadir’s home world, Zapata, would have fallen. That was only true in terms of a reference frame fixed to the local stars, not the Rindler 's notion of simultaneity, and in any case no confirmation of the event would reach them for decades, but unless the border had magically altered its speed in distant regions, the planet’s loss was a certainty.

"He’s holding a kind of wake. That’s where I’m going."

"So you and he are close?"

Mariama said, "Not especially. But he’s invited everyone, not just his friends."

Tchicaya leaned back against the wall, unfazed by its transparency. He said, "Why did you come here?"

She shaded her eyes against the borderlight. "I thought you’d decided that we were never going to have this argument."

"If you think I’ve shut you up, now’s your chance."

"You know why I’m here," she said. "Don’t pretend it’s a mystery." The glare was too much; she turned to stand beside him. "Do you want to come with me, to this thing of Kadir’s?"