They sat and discussed the possibilities. Tchicaya had learned quite a bit from his faction’s experts, and Mariama even more, but they needed a bigger group; on the Rindler, everyone’s ideas had sparked off someone else’s.
For weeks, they argued and experimented. They took turns sleeping for an hour each; even without any fixed, bodily need to recuperate, their minds were still structured to function best that way. The toolkit diligently analyzed vast lists of possibilities, sorting through the quantum states that might be swallowing all their probes without a trace, hunting for a new design that would avoid that fate and return with solid information.
Nothing worked. The darkness beneath them remained inscrutable.
They had no way of knowing how long it would be until the Planck worms came flooding down after them. On bad days, Tchicaya consoled himself with the thought that when they died, the Planck worms might be buried with them. On worse days, he faced the possibility that brute mutation would find a way through, where all their passion and borrowed ingenuity had failed.
On the thirty-seventh day, Tchicaya woke and looked around the scape. They’d tried all manner of distractions for the sake of inspiration, but no stroll through a forest, no mountain hike, no swim across a sunlit lake had led them to the answer. So they’d stopped ransacking their memories for places to camp, and returned to the unpalatable truth. They were stranded in an ugly, barren cave in the pockmarked rind of an alien universe, waiting to be corroded into noise by a billion species of ravenous sludge.
Mariama smiled encouragingly. “Any revelatory dreams?”
“I’m afraid not.” He’d dreamed he was a half-trained Sapper from the legend, suddenly confronted by a new kind of bomb, falling beside it toward a landscape of shadows that might have been anything from a desert to a vast metropolis.
“My turn, then. Come on, get up.”
“I will. Soon.” She could just as easily conjure up a bed of her own, but taking turns with one imposed a kind of discipline.
Tchicaya closed his eyes again. Sleep had lost all power to assuage his weariness, but it was still an escape while it lasted. He’d understood from the start that their struggle was quixotic, but he’d never imagined such a dispiriting end. They’d spend their last days writing equations on paper planes, and tossing them into an abyss.
As he drifted back toward sleep, he pictured himself gathering up a mountain of crumpled paper and heaving it out of the Sarumpaet into the darkness below. If by chance some scrap went wafting through into another world, he’d never even know that he’d succeeded.
He opened his eyes. “We launch all our paper planes at once. Then we throw a message back, and use it to clear away all the garbage.”
Mariama sighed. “What are you ranting about?”
Tchicaya beamed at her. “We have a list of the kind of states the region below us might be in, and we have strategies for dealing with them all. But we still haven’t found a probe that will cross through and return — giving us a definite answer, letting us know which strategy to use. Fine. We put the Sarumpaet into a superposition of states, in which it tries them all simultaneously.”
Mariama was speechless. It took Tchicaya several seconds to interpret this response; he had rarely surprised her, and he had certainly never shocked her before.
She said, “Who cares about quantum divergence, if one world out of every quadrillion is the best of all possible worlds? That sounds like some desperate fatalist nonsense from the last days before the Qusp.”
Tchicaya shook his head, laughing. “I know! But it’s not! Answer me this: a quantum computer does a search for the solution to an equation, testing a few trillion candidates simultaneously. In how many worlds does it fail?”
Mariama scowled. “None, if there’s a solution at all. But that’s different. The divergence is all internal and contained; it doesn’t split the environment into branches halfway through the calculation.” A flicker of uncertainty crossed her face. “You don’t think we could — ”
Tchicaya said, “We’re not in the near side anymore. Coherence is nowhere near as fragile here. Whatever this gulf is that we’re facing, there’s no fundamental reason why we shouldn’t be able to stretch a single quantum computer all the way across it. And if we handle all the strategies with sufficient care, we ought to be able to manipulate the whole coherent system so that the failures cancel out.”
She nodded slowly, then broke into an astonished grin. “We reach out and swallow the problem; we internalize it completely. Then we can bludgeon our way through by trial and error, without the world ever seeing a single mistake.”
They spent three days refining the idea, thrashing out the details with the toolkit and the ship. It was a complex maneuver, and it would require precise control over the ship’s environment, both before and after it crossed through the boundary. The toolkit had had plenty of time to study the surrounding vendeks, and it understood the physics of this obscure cul-de-sac as thoroughly as that of the near-side vacuum itself. The second half of the problem could not be dealt with by direct observation, but that didn’t mean they’d be taking a leap into the dark. Each strategy for making the crossing relied on a set of assumptions about the other side. Once they put the ship into a superposition of strategies, each component would know the kind of place it would end up in, if it ended up anywhere at all.
Tchicaya snapped awake, knowing the reason instantly. He’d been summoned to alertness by the tug of a trip wire that he’d installed, back on the near side, when he’d worked with the toolkit to construct a software container to sit between their minds and the raw quantum gates of the ship’s processor.
Mariama was seated a short distance away, gazing out into the vendek cell. Tchicaya said, “Do you want to tell me what you’re doing?”
She turned to him, frowning slightly. “Just rearranging a few things internally. I didn’t realize I had so little privacy.”
“I own this whole setup,” he said. “You knew that when you came into it.”
Mariama spread her arms. “Fine. Rummage through my memories; see if I care.”
Tchicaya sat up on the edge of the bed. “What were you trying to expel into the environment?” At the border of the simulated Qusp in which her mind was cocooned, he’d replaced some of the more arcane facilities of the standard hardware — things she’d have no good reason to want to use, under the circumstances — with fakes that merely rang alarm bells. It had been a last-minute decision; the toolkit would have happily simulated the Qusp in its entirety, as the simplest means of guaranteeing that everything worked smoothly when it was piped through.
“Nothing,” she said. “It was a mistake. I didn’t even realize you’d put me in a cage, so I brshed against the bars by accident.” She waved a hand at him irritably. “Go back to sleep.”
He rose to his feet. “Are you going to tell me, or am I going to have to look for myself?” In an ordinary Qusp, the owner of the hardware could freeze the whole program and inspect its state at leisure. But the quantum gates here were implemented at too low a level; there was no room for that approach. All he could do was send in a swarm of utility algorithms to search for anything suspicious, while shuffling her working mind aside. That would do no lasting damage, but he had no idea how she would experience it. It could be extremely unpleasant.