She said, "Chiang's version was three-dimensional, wasn't it?"

"Much better. N-dimensional. Four, five, six, whatever you like. That leaves plenty of room for data within easy reach. In two dimensions, the original von Neumann machine had to reach farther and farther -- and wait longer and longer -- for each successive bit of data. In a six-dimensional TVC automaton, you can have a three-dimensional grid of computers, which keeps on growing indefinitely -- each with its own three-dimensional memory, which can also grow without bound."

Maria said numbly, "Where are you supposed to fit into all of this? If you think translating human biochemistry into Autoverse terms is difficult, how are you going to map yourself into a six-dimensional world designed solely to support von Neumann machines?"

"The TVC universe is one big, ever-expanding processor cluster. It runs a Copy of me --"

"I thought the whole point was to do away with Copies!"

"-- in a VR environment which lets me interact with the TVC level. Yes, I'll be a patchwork Copy, as always -- there's no alternative to that -- but I'll also be linked to the cellular automaton itself. I'll witness its operation, I'll experience its laws. By observing it, I'll make it a part of what has to be explained.

"And when the simulated TVC universe being run on the physical computer is suddenly shut down, the best explanation for what I've witnessed will be a continuation of that universe -- an extension made out of dust."

Maria could almost see it: a vast lattice of computers, a seed of order in a sea of a random noise, extending itself from moment to moment by sheer force of internal logic, "accreting" the necessary building blocks from the chaos of non-space-time by the very act of defining space and time.

Visualizing wasn't believing, though.

She said, "What makes you so sure? Why not another deluded psychiatric patient, who believes he was -- briefly -- a Copy being run on a TVC automaton being run on a processor cluster in another world?"

"You're the one who invoked Occam's razor. Wouldn't you say that a self-contained TVC universe is a simpler explanation, by far?"

"No. It's about the most bizarre thing I can imagine."

"It's a lot less bizarre than yet another version of this universe, containing yet another version of me, with yet another set of convenient delusions."

"How many of your clients believed all this? How many think they're coming along for the ride?"

"Fifteen. And there's a sixteenth who, I think, is tempted."

"They paid -- ?"

"About two million each." He snorted. "It's quite funny, the significance the police have attached to that. Some large sums of money have changed hands, for reasons more complex than usual -- so they assume I must be doing something illegal. I mean, billionaires have been known to make donations larger than that to the Church of the God Who Makes No Difference." He added hastily, "None of mine."

Maria was having some trouble with the scale of things herself. "You found fifteen Copies willing to part with two million dollars after hearing this bullshit? Anyone that gullible deserves to lose their money."

Durham took no offence. "If you were a Copy, you'd believe the dust theory, too. You'd feel the truth of it in your nonexistent bones. Some of these people carried out the same experiments as I did -- computing themselves in randomized fragments -- but others didn't need to. They already knew that they could scatter themselves across real time and real space, and they'd still find themselves. Every Copy proves the dust theory to itself a million times a day."

It suddenly occurred to Maria that Durham might have invented all of this for her sake, alone -- while telling his clients exactly what Hayden had assumed: some fraudulent but utterly non-metaphysical tale of a hidden supercomputer. But she couldn't see what he had to gain by confusing her . . . and too many details made too much sense, now. If his clients had accepted the whole mad vision, the problem of making them believe in a nonexistent supercomputer vanished. Or at least changed from a question of evidence to a question of faith. She said, "So you promised to fit a snapshot of each of your 'backers' into the Garden-of-Eden configuration, plus the software to run them on the TVC?"

Durham said proudly, "All that and more. The major world libraries; not quite the full holdings, but tens of millions of files -- text, audio, visual, interactive -- on every conceivable subject. Databases too numerous to list -- including all the mapped genomes. Software: expert systems, knowledge miners, metaprogrammers. Thousands of off-the-shelf VR environments: deserts, jungles, coral reefs, Mars and the moon. And I've commissioned Malcolm Carter, no less, to create a major city to act as a central meeting place: Permutation City, capital of the TVC universe.

"And, of course, there'll be your contribution: the seed for an alien world. Humanity is going to find other life in this universe, eventually. How can we give up hope of doing the same? Sure, we'll have our own software descendants, and recreated Earth animals, and no doubt novel, wholly artificial creatures as well. We won't be alone. But we still need a chance to confront the Other. We mustn't leave that possibility behind. And what could be more alien than Autoverse life?"

Maria's skin crawled. Durham's logic was impeccable; an endlessly expanding TVC universe, with new computing power being manufactured out of nothing in all directions, "would" eventually be big enough to run an Autoverse planet -- or even a whole planetary system. The packed version of Planet Lambert -- the compressed description, with its topographic summaries in place of actual mountains and rivers -- would easily fit into the memory of a real-world computer. Then Durham's Copy could simply wait for the TVC grid to be big enough -- or pause himself, to avoid waiting -- and have the whole thing unfold.

Durham said, "I've been working on the software which will run the first moments of the TVC universe on a real-world computer. I can probably finish that myself. But I can't complete the Autoverse work without you, Maria."

She laughed sharply. "You want me to keep working for you? You lie to me. You get me visited by the Fraud Squad. You confess to a history of mental illness. You tell me you're the twenty-third incarnation of a retailing millionaire from a parallel world --"

"Whatever you think about the dust theory -- and whatever you think about my psychological health -- I can prove to you that I'm not a criminal. My backers will vouch for that; they all know exactly what their money's being used for. None of them are victims of fraud."

"I accept that. I just --"

"Then accept the payment. Finish the work. Whatever the police have told you, you have every right to the money, and I have every right to give it to you. Nobody's going to take you to court, nobody's going to throw you into prison."

Maria was flustered. "Just, hold on. Will you give me a chance to think?" Durham's sheer reasonableness was beginning to be as exhausting as the impassioned rhetoric of any obvious fanatic. And so much ground had shifted in the last half-hour that she hadn't had a chance to even start to reappraise her own situation: legally, financially . . . and morally.

She said, "Why don't your backers tell the police all this? If they can confirm your story for me, why can't they do the same for the cops? By refusing to talk, they're just fueling suspicion."

Durham agreed. "Tell me about it. It makes everything ten times harder -- but I'm just going to have to keep on living with that. Do you think they'd risk the truth becoming public knowledge? There have already been some embarrassing leaks -- but so far we've been able to muddy the water by putting out our own misinformation. Copies with de facto control of billion-dollar business empires would much rather have people linking them to some dubious salesman and his breakthrough supercomputer -- and have the rumors fizzle out from lack of substantiation -- than let the world know that they plan to send a clone into an artificial universe which runs without hardware. The share markets can get nervous enough when people start wondering if a certain board of directors have all taken up playing virtual Caligula in their spare time. If word got out that a Copy in a position of power had done something which might be construed as a sign that they no longer felt obliged to give a shit about their corporate responsibilities, their personal wealth, or the continued existence of Planet Earth . . . "