Aden thought about that for a while. Then he said, "All right. Fuck you. Stay."

He got to his feet and walked out of the room. Maria listened to him fumbling with his cycle, then opening the front door, slamming it closed.

She tidied up in the kitchen, checked the locks, switched off the lights. Then she went upstairs and lay on her bed, leaving the room in darkness, trying to picture the likely course of events over the next few weeks. Aden would phone before he left, trying to patch things up, but she could see how easy it would be, now, to break things off permanently. And now that it had reached that stage, it seemed like the obvious thing to do. She wasn't upset, or relieved -- just calm. It always made her feel that way: burning bridges, driving people away. Simplifying her life.

She'd left the terminal switched on after reading Durham's ROM; the screen was blank, and supposedly pure black, but as her eyes adapted to the dark she could see it glowing a faint gray. Every now and then there was a brief flash at a random point on the screen -- a pixel activated by background radiation, struck by a cosmic ray. She watched the flashes, like a slow rain falling on a window to another world, until she fell asleep.

11

(Remit not paucity)

JANUARY 2051

Malcolm Carter presented as a tall, solid, vigorous-looking man in late middle age -- and in fact he was fifty-eight, so his visitor's body might easily have been styled directly on his real one. Peer remembered seeing photographs of Carter in the early thirties, when he rose to prominence as one of the first architect-programmers to concentrate on the needs of Copies, rather than catering to the human visitors who used virtual environments merely for work or entertainment. Visitors had ended up hiring him too, though -- visitors like Kate who were on their way in. And Kate had moved in a similar orbit then, a young computer artist snatched out of obscurity in Oregon and adopted by the San Francisco glitterati at about the same time as Carter's own ascent from a small Arizona software house. Peer wasn't sure he would have recognized the man from those old magazine shots -- but then, nobody continued to look the way they'd looked in the thirties, if they could possibly help it.

Carter shook hands with Peer, and nodded at Kate; Peer wondered, curious but not really jealous, if they were greeting each other a little more warmly in a private detour from the version of the meeting he was seeing. They were standing in a spacious reception area, the walls and high ceiling decorated with a motif of tiered concentric circles moulded into the cream-colored plaster, the floor tiled in black-and-white diamonds. This was Carter's publicly listed VR address; anyone at all could call the number and "come here." The room spawned separate versions for separate callers, though; Peer and Kate had taken steps to arrive together, but there had been no risk of them accidentally bumping into one of Carter's -- or Durham's -- wealthy clients.

Carter said, "I hope you don't mind if we keep this brief and to the point. I don't like to use inducers for more than twenty-four hours at a stretch."

Peer said, "It's good of you to make the time to see us at all." He cursed himself silently; he was contemplating paying this man a substantial portion of his entire wealth -- and trusting him with the fate of an autonomous version of his own consciousness. He had a right to an audience. Still, at a slow-down of sixty . . .

Carter -- if it really was Carter, and not just a convincing mask -- pointed out a door at the end of the room. "There's a rough sketch of the city through there, if you want to take the tour later on; just call out for a guide if you need one. But I expect the city itself's not your main concern. What you really want to know is, can I fit you safely into the cracks?"

Peer glanced at Kate. She remained silent. She was already convinced; this was all for his benefit.

Carter held out a hand toward the middle of the room. "See that fountain?" A ten-meter-wide marble wedding cake, topped with a winged cherub wrestling a serpent, duly appeared. Water cascaded down from a gushing wound in the cherub's neck. Carter said, "It's being computed by redundancies in the sketch of the city. I can extract the results, because I know exactly where to look for them -- but nobody else would have a hope in hell of picking them out."

Peer walked up to the fountain. Even as he approached, he noticed that the spray was intangible; when he dipped his hand in the water around the base he felt nothing, and the motion he made with his fingers left the foaming surface unchanged. They were spying on the calculations, not interacting with them; the fountain was a closed system.

Carter said, "In your case, of course, nobody will need to know the results. Except you -- and you'll know them because you'll be them."

Peer replied, almost without thinking, "Not me. My clone."

"Whatever." Carter clapped his hands, and a multicolored, three-dimensional lattice appeared, floating in the air above the fountain. "This is a schematic of part of the software running the sketch of the city. Each cube represents a process. Packets of data -- those blips of colored light -- flow between them.

"There's nothing so crude as a subset of processes dedicated to the fountain. Every individual process -- and every individual packet of data -- is involved with some aspect of the city. But there are some slightly inefficient calculations going on here and there, and some 'redundant' pieces of information being exchanged." Pin-pricks in a smattering of the cubes, and some of the data, glowed bright blue. "One of the simplest tricks is to use a vector when only a direction is needed -- when the magnitude of the vector is irrelevant. Perfectly reasonable operations on the vector, entirely justified in their own context, incidentally perform arithmetic on the magnitude. But that's just one technique; there are dozens of others." He clapped his hands again, and everything but the blue highlights vanished. The diagram re-formed, the scattered processes coming together into a compact grid. "The point is, the fountain gets computed along with the city, without any of the software explicitly stealing time for a parasitic task. Every line of every program makes sense in terms of computing the city."

Peer said, "And if Durham runs your code through an optimizer which rescales all the unnecessary vectors, trims away all the inefficiencies . . . ?"

Carter shook his head. "I don't believe he'd meddle with the code at all, but even if he does, optimizers can only track things so far. In the full version of the city, the results of your calculations will propagate so widely that it would take months for any program to deduce that the data's not actually needed somewhere -- that it ultimately makes no difference to the legitimate inhabitants." He grinned. "Optimizing anything to do with Copies is a subtle business. You must have heard about the billionaire recluse who wanted to run as fast as possible -- even though he never made contact with the outside world -- so he fed his own code into an optimizer. After analyzing it for a year, the optimizer reported this program will produce no output, and spat out the optimized version -- which did precisely nothing."

Peer laughed, although he'd heard the joke before.

Carter said, "The fact is, the city is so complex, there's so much going on, that even if it had all been left to chance, I wouldn't be surprised if there were some quite sophisticated secondary computations taking place, purely by accident. I haven't gone looking for them, though -- it would bum up far too much processor time. And the same applies to anyone searching for you. It's just not a practical proposition. Why would anyone spend millions of dollars scanning for something which can do no harm?"