Zemansky manipulated the view until they were peering straight down the middle of the thin layer of transparent "null" cells which separated the Autoverse region from Maria's territory -- bringing her own processors into sight for the first time. An arrow in a small key diagram above showed the orientation; they were looking straight toward the distant hub. All the processors were structurally identical, but those in the Autoverse were alive with the coded streams of activated states marking data flows, while her own were almost idle. Then Durham plugged her territory into the software he was running, and a wave of data swept out from the hub -- looking like something from the stargate sequence in 2001 -- as the processors were reprogrammed. The real wave would have passed in a Standard Time picosecond; the map was smart enough to show the event in slow motion.

The reprogrammed processors flickered with data -- and then began to sprout construction wires. Every processor in the TVC grid was a von Neumann machine as well as a Turing machine -- a universal constructor as well as a universal computer. The only construction task they'd performed in the past had been a one-off act of self-replication, but they still retained the potential to build anything at all, given the appropriate blueprint.

The construction wires reached across the gap and touched the surface of the Autoverse processors. Maria held her breath, almost expecting to see a defensive reaction, a counterattack. Durham had analyzed the possibilities in advance: if the TVC rules continued to hold true, any "war" between these machines would soon reach a perpetual stalemate; they could face each other forever, annihilating each other's "weapons" as fast as they grew, and no strategy could ever break the deadlock.

If the TVC rules failed, though, there was no way of predicting the outcome.

There was no -- detectable -- counterattack. The construction wires withdrew, leaving behind data links bridging the gap between the pyramids. Since the map was showing the links as intact, the software must have received some evidence that they were actually working: the Autoverse processors were at least reacting as they should to simple tests of the integrity of the connections.

Durham said, "Well, that's something. They haven't managed to shut us out completely."

Repetto grimaced. "You make it sound like the Lambertians have taken control of the processors -- that they're deciding what's going on here. They don't even know that this level exists."

Durham kept his eyes on the screen. "Of course they don't. But it still feels like we're sneaking up on some kind of . . . sentient adversary. The Lambertians' guardian angels: aware of all the levels -- but jealously defending their own people's version of reality." He caught Maria's worried glance, and smiled. "Only joking."

Maria looked on as Durham and Zemansky ran a series of tests to verify that they really had plugged in to the Autoverse region. Everything checked out -- but then, all the same tests had worked when run through the authorized link, down at the hub. The suspect processors were merely acting as messengers, passing data around in a giant loop which confirmed that they could still talk to each other -- that the basic structure of the grid hadn't fallen apart.

Durham said, "Now we try to stop the clock." He hit a few keys, and Maria watched his commands racing across the links. She thought: Maybe there was something wrong down at the hub. Maybe this whole crisis is going to turn out to be nothing but a tiny, localized bug. Perfectly explicable. Easily fixed.

Durham said, "No luck. I'll try to reduce the rate."

Again, the commands were ignored.

Next, he increased the Autoverse clock rate by fifty percent -- successfully -- then slowed it down in small steps, until it was back at the original value.

Maria said numbly, "What kind of sense does that make? We can run it as fast as we like -- within our capacity to give it computing resources -- but if we try to slow it down, we hit a brick wall. That's just . . . perverse."

Zemansky said, "Think of it from the Autoverse point of view. Slowing down the Autoverse is speeding up Elysium; it's as if there's a limit to how fast it can run us -- a limit to the computing resources it can spare for us."

Maria blanched. "What are you suggesting? That Elysium is now a computer program being run somewhere in the Autoverse?"

"No. But there's a symmetry to it. A principle of relativity. Elysium was envisioned as a fixed frame of reference, a touchstone of reality -- against which the Autoverse could be declared a mere simulation. The truth has turned out to be more subtle: there are no fixed points, no immovable objects, no absolute laws." Zemansky betrayed no fear, smiling beatifically as she spoke, as if the ideas enchanted her. Maria longed to know whether she was merely concealing her emotions, or whether she had actually chosen a state of tranquility in the face of her world's dethronement.

Durham said flatly, "Symmetries were made to be broken. And we still have the edge: we still know far more about Elysium -- and the Autoverse -- than the Lambertians. There's no reason why our version of the truth can't make as much sense to them as it does to us. All we have to do is give them the proper context for their ideas."

Repetto had created a puppet team of Lambertians he called Mouthpiece: a swarm of tiny robots resembling Lambertians, capable of functioning in the Autoverse -- although ultimately controlled by signals from outside. He'd also created human-shaped "telepresence robots" for the four of them. With Mouthpiece as translator, they could "reveal themselves" to the Lambertians and begin the difficult process of establishing contact.

What remained to be seen was whether or not the Autoverse would let them in.

Zemansky displayed the chosen entry point: a deserted stretch of grassland on one of Planet Lambert's equatorial islands. Repetto had been observing a team of scientists in a nearby community; the range of ideas they were exploring was wider than that of most other teams, and he believed there was a chance that they'd be receptive to Elysian theories.

Durham said, "Time to dip a toe in the water." On a second window, he duplicated the grassland scene, then zoomed in at a dizzying rate on a point in midair, until a haze of tumbling molecules appeared, and then individual Autoverse cells. The vacuum between molecules was shown as transparent, but faint lines delineated the lattice.

He said, "One red atom. One tiny miracle. Is that too much to ask for?"

Maria watched the commands stream across the TVC map: instructions to a single processor to rewrite the data which represented this microscopic portion of the Autoverse.

Nothing happened. The vacuum remained vacuum.

Durham swore softly. Maria turned to the window. The City was still standing; Elysium was not decaying like a discredited dream. But she felt herself break out in a sweat, felt her body drag her to the edge of panic. She had never really swallowed Durham's claim that there was a danger in sharing their knowledge with the other Elysians -- but now she wanted to flee the room herself, hide her face from the evidence, lest she add to the weight of disbelief.

Durham tried again, but the Autoverse was holding fast to its laws. Red atoms could not spontaneously appear from nowhere -- it would have violated the cellular automaton rules. And if those rules had once been nothing but a few lines of a computer program -- a program which could always be halted and rewritten, interrupted and countermanded, subjugated by higher laws -- that was no longer true. Zemansky was right: there was no rigid hierarchy of reality and simulation anymore. The chain of cause and effect was a loop now -- or a knot of unknown topology.