Грег Иган - Permutation City

She whispered, "It looks like they're ignoring us completely . . . but do they think they're talking to real Lambertians -- or have they noticed the differences?"

"I can't tell. But as a group, they're reacting normally, so far."

Zemansky said, "If a robot greeted you in your own language, wouldn't you reply?"

Repetto nodded. "And the instinct goes far deeper, with the Lambertians. I don't think they'd . . . discriminate. If they've noticed the differences, they'll want to understand them, eventually -- but the first priority will still be to receive the message. And to judge it."

Mouthpiece began to drift into a more complex formation. Maria could make little sense of it -- but she could see the Lambertians tentatively begin to mimic the change. This was it: Durham and Repetto's cosmological package deal. An explanation for the primordial cloud, and for the deep rules underlying Autoverse chemistry: a cellular automaton, created with the cloud in place, five billion years ago. The two billion years of planetary formation which strictly hadn't happened seemed like a forgivable white lie, for the moment; messy details like that could be mentioned later, if the basic idea was accepted.

Durham said, "Bad messages usually can't be conveyed very far. Maybe the fact that Mouthpiece clearly isn't a team for a nearby community will add credence to the theory."

Nobody replied. Zemansky smiled sunnily. Maria watched the dancing swarms, hypnotized. The Lambertians seemed to be imitating Mouthpiece almost perfectly, now -- but that only proved that they'd "read" the message. It didn't yet mean that they believed it.

Maria turned away, and saw black dots against the sky. Persistence of vision was back in Elysium, in her model-of-a-brain. She remembered her dissatisfaction, clutching Autoverse molecules with her real-world hands and gloves. Had she come any closer to knowing the Autoverse as it really was?

Repetto said, "They're asking a question. They're asking for . . . clarification." Maria turned back. The Lambertians had broken step with Mouthpiece, and the swarm had rearranged itself into something like an undulated black flying carpet. "They want 'the rest of the message' -- the rest of the theory. They want a description of the universe within which the cellular automaton was created."

Durham nodded. He looked dazed, but happy. "Answer them. Give them the TVC rules."

Repetto was surprised. "Are you sure? That wasn't the plan --"

"What are we going to do? Tell them it's none of their business?"

"I'll translate the rules. Give me five seconds."

Mouthpiece began a new dance. The waving carpet dispersed, then began to fall into step.

Durham turned to Maria. "This is better than we'd dared to hope. This way, they reinforce us. They won't just stop challenging our version; they'll help to affirm it."

Zemansky said, "They haven't accepted it yet. All they've said is that the first part of what we've told them makes no sense alone. They might ask about real-world physics, next."

Durham closed his eyes, smiling. He said quietly, "Let them ask. We'll explain everything -- right back to the Big Bang, if we have to."

Repetto said, puzzled, "I don't think it's holding."

Durham glanced at the swarm. "Give them a chance. They've barely tried it out."

"You're right. But they're already sending back a . . . rebuttal."

The swarm's new pattern was strong and simple: a sphere, rippling with waves like circles of latitude, running from pole to pole. Repetto said, "The software can't interpret their response. I'm going to ask it to reassess all the old data; there may be a few cases where this dance has been observed before -- but too few to be treated as statistically significant."

Maria said, "Maybe we've made some kind of grammatical error. Screwed up the syntax, so they're laughing in our face -- without bothering to think about the message itself."

Repetto said, "Not exactly." He frowned, like a man trying to visualize something tricky. Mouthpiece began to echo the spherical pattern. Maria felt a chill in her Elysian bowels.

Durham said sharply, "What are you doing?"

"Just being polite. Just acknowledging their message."

"Which is?"

"You may not want to hear it."

"I can find out for myself, if I have to." He took a step toward Repetto, more a gesture of impatience than a threat; a cloud of tiny blue gnat-like creatures flew up from the grass, chirping loudly.

Repetto glanced at Zemansky; something electric passed between them. Maria was confused -- they were, unmistakably, lovers; she'd never noticed before. But perhaps the signals had passed through other channels, before, hidden from her. Only now --

Repetto said, "Their response is that the TVC rules are false -- because the system those rules describe would endure forever. They're rejecting everything we've told them, because it leads to what they think is an absurdity."

Durham scowled. "You're talking absurdities. They've had transfinite mathematics for thousands of years."

"As a formality, a tool -- an intermediate step in certain calculations. None of their models lead to infinite results. Most teams would never go so far as to try to communicate a model which did; that's why this response is one we've rarely seen before."

Durham was silent for a while, then he said firmly, "We need time to decide how to handle this. We'll go back, study the history of the infinite in Lambertian culture, find a way around the problem, then return."

Maria was distracted by something bright pulsing at the edge of her vision. She turned her head -- but whatever it was seemed to fly around her as fast as she tracked it. Then she realized it was the window on Elysium; she'd all but banished it from her attention, filling it in like a blind spot. She tried to focus on it, but had difficulty making sense of the image. She centered and enlarged it.

The golden towers of Permutation City were flowing past the apartment window. She cried out in astonishment, and put her hands up, trying to gesture to the others. The buildings weren't simply moving away; they were softening, melting, deforming. She fell to her knees, torn between a desire to return to her true body, to protect it -- and dread at what might happen if she did. She dug one hand into the Lambertian soil; it felt real, solid, trustworthy.

Durham grabbed her shoulder. "We're going back. Stay calm. It's only a view -- we're not part of the City."

She nodded and steeled herself, fighting every visceral instinct about the source of the danger, and the direction in which she should flee. The cloned apartment looked as solid as ever . . . and in any case, its demise could not, in itself, harm her. The body she had to defend was invisible: the model running at the far end of Durham's territory. She would be no safer pretending to be on Planet Lambert than she would pretending to be in the cloned apartment.

She returned.

The four of them stood by the window, speechless, as the City rapidly and silently . . . imploded. Buildings rushed by, abandoning their edges and details, converging on a central point. The outskirts followed, the fields and parks flowing in toward the golden sphere which was all that remained of the thousand towers. Rainforest passed in a viridian blur. Then the scene turned to blackness as the foothills crowded in, burying their viewpoint in a wall of rock.

Maria turned to Durham. "The people who were in there . . . ?"

"They'll all have left. Shocked but unharmed. Nobody was in there -- in the software -- any more than we were." He was shaken, but he seemed convinced.

"And what about the founders with adjoining territory?"

"I'll warn them. Everyone can come here, everyone can shift. We'll all be safe, here. The TVC grid is constantly growing; we can keep moving away, while we plan the next step."