Permutation City

She tried half a dozen numbers, starting with Francesca's, ending with Aden's. The terminal declared them all invalid. She couldn't bring herself to try her own. Durham watched in silence. He seemed to be caught between genuine sympathy and a kind of clinical fascination -- as if an attempt to make a few phone calls cast doubt on her sanity; as if she was engaged in some bizarre, psychotic behavior worthy of the closest scrutiny: peering behind a mirror in search of the objects seen in the reflection; talking back to a television program . . . or making calls on a toy phone.

Maria pushed the floating machine away angrily; it moved easily, but came to a halt as soon as she took her hands off it. Patchwork VR and its physics-of-convenience seemed like the final insult.

She said, "Do you think I'm stupid? What does a dummy terminal prove?"

"Nothing. So why don't you apply your own criteria?" He said, "Central computer," and the terminal flashed up an icon-studded menu, headed permutation city computing facility. "Not many people use this interface, these days; it's the original version, designed before the launch. But it still plugs you into as much computing power as the latest co-personality links."

He showed Maria a text file. She recognized it immediately; it was a program she'd written herself, to solve a large, intentionally difficult, set of Diophantine equations. The output of this program was the key they'd agreed upon to unlock Durham's access to the other Copies, "after" the launch.

He ran it. It spat out its results immediately: a screenful of numbers, the smallest of which was twenty digits long. On any real-world computer, it should have taken years.

Maria was unimpressed. "You could have frozen us while the program was running, making it seem like no time had passed. Or you could have generated the answers in advance." She gestured at the terminal. "I expect you're faking all of this: you're not talking to a genuine operating system, you're not really running the program at all."

"Feel free to alter some parameters in the equations, and try again."

She did. The modified program "ran" just as quickly, churning out a new set of answers. She laughed sourly. "So what am I supposed to do now? Verify all this in my head? You could put any bullshit you liked on the screen; I wouldn't know the difference. And if I wrote another program to check the results, you could fake its operation, too. You control this whole environment, don't you? So I can't trust anything. Whatever I do to try to test your claims, you can intervene and make it go your way. Is that why you wanted my scan file, all along? So you could lock me in here and bombard me with lies -- finally 'prove' all your mad ideas to someone?"

"You're being paranoid now."

"Am I? You're the expert."

She looked around the luxurious prison cell. Red velvet curtains stirred in a faint breeze. She slipped out of bed and crossed the room, ignoring Durham; the more she argued with him, the harder it was to be physically afraid of him. He'd chosen his form of torture, and he was sticking to it.

The window looked out on a forest of glistening towers -- no doubt correctly rendered according to all the laws of optics, but still too slick to be real . . . like some nineteen twenties Expressionist film set. She'd seen the sketches; this was Permutation City -- whatever hardware it was running on. She looked down. They were seventy or eighty stories up, the street was all but invisible, but just below the window, a dozen meters to the right, a walkway stretched across to an adjacent building, and she could see the puppet citizens, chatting together in twos and threes as they strode toward their imaginary destinations. All of this looked expensive -- but slowdown could buy a lot of subjective computing power, if that was the trade-off you wanted to make. How much time had passed in the outside world? Years? Decades?

Had she managed to save Francesca?

Durham said, "You think I've kidnapped your scan file, and run this whole city, solely for the pleasure of deceiving you?"

"It's the simplest explanation."

"It's ludicrous, and you know it. I'm sorry; I know this must be painful for you. But I didn't do it lightly. It's been seven thousand years; I've had a lot of time to think it over."

She spun around to face him. "Stop lying to me!"

He threw his hands up, in a gesture of contrition -- and impatience. "Maria . . . you are in the TVC universe. The launch worked, the dust hypothesis has been vindicated. It's a fact, and you'd better come to terms with that, because you're now part of a society which has been living with it for millennia.