Грег Иган - Schild’s Ladder

Ilene reeled off a list of measurements from the instrument probes that were monitoring their environment, out to a radius of more than a light-hour. There was nothing on its way that could wreck the experiment — or at least, nothing traveling slower than ninety-five percent of lightspeed. Zulkifli followed with a status report from the machinery deep inside the Quietener. Systems that had been preparing themselves for the last twelve hours were now minutes away from readiness.

The single graph on the wall was just a useful shorthand for the state they were hoping to create; the novo-vacuum itself was the sum of equal parts of forty-eight variations of the target graph, all generated by simple symmetry transformations of the original. All the individual variations favored one direction over another, but the sum combined every possible bias, canceling them all out and giving rise to a perfectly isotropic state. Since none of the graphs could be found in nature, this elegant description was useless as a recipe, but it wasn’t hard to show that the same state vector could also be described by a different sum: forty-eight regions of ordinary vacuum, each slightly curved, oriented in forty-eight different directions.

Inside the Quietener, an asteroid’s-mass worth of helium had been cooled into a Bose-Einstein condensate, and manipulated into a state where it was equally likely to be found in any of forty-eight different places. These alternative locations were distributed across the surface of a sphere six kilometers wide. Ordinary matter — or any kind of matter interacting with the outside world — would have behaved as if each distinct position had already become the sole reality; if a swarm of dust particles wandering by had made themselves part of the system, or if the helium’s behavior en masse had merely hinted at the detailed motion of its own atoms, then that behavior could only have told half the story — the classical half — and all the quantum subtleties would have been lost in the fine print. But the condensate was isolated as scrupulously as any cycling Qusp, and it had been cooled to the point where the states of all its individual atoms were dictated completely by its macroscopic properties. With no hidden complications, inside or out, the result was a quantum-mechanical system the size of a mountain.

The geometry of the vacuum in the Quietener inherited the helium’s multiplicity: its state vector was a sum of the vectors for forty-eight different gravitational fields. Once the condensate’s components had all been nudged into place, the quantum geometry at the center of the sphere would be equivalent to the novo-vacuum, and a new kind of space-time would blossom into existence.

That was the idealized version: a predictable event in a known location. In reality, the outcome remained hostage to countless imperfections and potential intrusions. If the experimenters were lucky, sometime over a period measured in minutes, somewhere over a region measured in meters, a few thousand cubic Planck lengths of novo-vacuum would be created, and survive for an unprecedented six-trillionths of a second.

Yann turned to Cass. "Are you ready to freeze?" The first time he’d asked her this, she’d been almost as nervous as the moment before she’d been transmitted from Earth, but the question had rapidly become a formality. Of course she was ready. That was how things were done . Just a few minutes of numb immobility, watching the data appear on the screen in front of her, and the odds were good that it would be the last time. A five-hour trip back to the station, a day or two of analysis, a brief celebration, and she would depart. Her Earth body, frozen more deeply than this one had ever been, was waiting for her. She’d step across the light-years in a subjective instant, a new set of memories to sweep away the icy cobwebs of her old self.

She said, "No. I’m not ready."

Yann looked alarmed, but only for a moment. Cass suspected that he’d just conferred privately with someone better able to guess what she had in mind. Though the Mimosans didn’t think any more rapidly than she did — running on Qusps themselves, they faced the same computing bottlenecks — they could communicate with each other about five times faster than her own form of speech allowed. That only annoyed her when they used it to talk about her behind her back.

She added dryly, "Tell Rainzi I’ve changed my mind."

Yann smiled, clearly delighted, and then his icon was instantly replaced by Rainzi’s. Fair enough: with the countdown proceeding, the Mimosans had better things to do than fake inertia for its own sake.

Rainzi’s response was more cautious than Yann’s. "Are you certain you want to do this? After everything you told me?"

"I’m the quintessential singleton," Cass replied. "I weigh up all my choices very carefully."

There was no time to spell out in glacial words everything she was feeling, everything that had swayed her. Part of it was the same sense of ownership that had brought her all this distance in the first place: justifiably or not, she didn’t want the Mimosans to have a better view than she did of the thing they were about to create together. There was the same longing for immediacy, too: she would never see, or touch, any graph as it really was, but to remain locked in a body that could only perceive a fraction of the data, milliseconds after the fact, would leave her feeling almost as detached from the event, now, as if she’d stayed on Earth, waiting for the centuries-old news of an experiment conducted light-years away. Every viewpoint was a compromise, but she had to be as close as she could get.

Beyond the experiment itself, though, it was clear to her now that she couldn’t leave Mimosa without doing at least one thing that went against the grain. After five years of monastic restraint, five years of denying herself the dishonest comforts of virtual reality, she was sick of placing that principle above everything else. Beyond the fact that this disembodiment would be entirely in the service of honesty, she needed, very badly, to drag herself out of the absolutist rut she’d been digging from the moment she’d arrived. If she’d compromised a little from the start, maybe she wouldn’t have felt the same sense of desperation. But it was too late now for half-measures. If she returned to Earth unchanged , it wouldn’t be a triumph of integrity. It would be a kind of death. She’d implode into something as hermetic and immutable as a black hole.

All this, weighed against the thing she hated most: lack of control. Every choice she made rendered meaningless. What choices, though ? Her clones would run for a few subjective minutes, most of them in rapt attention as the data poured in. What was the worst that one of these transient selves might do? Utter a few unkind words to Livia or Darsono? Disclose some small guilty secret from her past to people who either wouldn’t understand, wouldn’t care, or at the very least, wouldn’t have the chance to reproach her for long? She wasn’t opening up the gates to the old human nightmare: endless varieties of suffering, endless varieties of stupidity, endless varieties of banality. She would diffuse a very small distance into the space of possibilities, and whatever unhappiness she might experience, whatever misdemeanors she might commit, would be erased beyond recovery.

Rainzi looked skeptical, and she couldn’t blame him. But there was no time left for him to play devil’s advocate, to test her resolve. Cass stood her ground, silently, and after a moment he nodded assent.

She felt a stream of low-level requests for data, and she willed her Mediator to respond. She’d been through the same process before her transmission from Earth: sending the preliminaries first, things that needed to be known about the structure of her mind before it could be implemented in a new environment.