Of course, all these reassuring plans had been made by a man with two futures. Would he really want to keep an old Copy running, when he could save his money for a deathbed scan, and "his own" immortality?

Squeak. "Can we get to work, now?"

"That's what I'm here for."

This time, the model would be described at the standard time resolution of one millisecond, throughout -- but the order in which the states were computed would be varied.

Squeak. "Experiment two, trial number one. Reverse order."

Paul counted. "One. Two. Three." Reverse order. After an initial leap into the future, he was now traveling backward through real time. It would have been a nice touch if he'd been able to view an external event on the terminal -- some entropic cliche like a vase being smashed -- knowing that it was himself, and not the scene, that was being "rewound" . . . but he knew that it couldn't be done (quite apart from the fact that it would have ruined the experiment, betraying the difference between subject and control). In real time, the first thing to be computed would be his model-time-final brain state, complete with memories of everything that "had happened" in the "preceding" ten seconds. Those memories couldn't include having seen a real broken vase assemble itself from fragments, if the vase hadn't even been smashed yet. The trick could have been done with a simulation, or a video recording of the real thing -- but that wouldn't have been the same.

"Eight. Nine. Ten." Another imperceptible leap into the future, and the djinn reappeared.

Squeak. "Trial number two. Odd numbered states, then even."

In external terms: he would count to ten, skipping every second model-time moment . . . then forget having done so, and count again, going back and filling in the gaps.

And from his own point of view? As he counted, once only, the external world -- even if he couldn't see it -- was flickering back and forth between two separate regions of time, which had been chopped up into seventeen-millisecond portions, and interleaved.

So . . . who was right? Paul thought it over, half seriously. Maybe both, descriptions were equally valid; after all, relativity had abolished absolute time. Everybody was entitled to their own frame of reference; crossing deep space at close to lightspeed, or skimming the event horizon of a black hole. Why shouldn't a Copy's experience of time be as sacrosanct as that of any astronaut?

The analogy was flawed, though. Relativistic transformations were smooth -- possibly extreme, but always continuous. One observer's space-time could be stretched and deformed in the eyes of another -- but it couldn't be sliced like a loaf of bread and then shuffled like a deck of cards.

"Every tenth state, in ten sets."

Paul counted -- and for argument's sake, tried to defend his own perspective, tried to imagine the outside world actually cycling through fragments of time drawn from ten distinct periods. The trouble was . . . this allegedly shuddering universe contained the computer which ran the whole model, the infrastructure upon which everything else depended. If its orderly chronology had been torn to shreds, what was keeping him together, enabling him to ponder the question?

"Every twentieth state, in twenty sets."

Nineteen episodes of amnesia, nineteen new beginnings.

(Unless, of course, he was the control.)

"Every hundredth state, in one hundred sets."

He'd lost any real feeling for what was happening. He just counted.

"Pseudo-random ordering of states."

"One. Two. Three."

Now he was . . . dust. To an outside observer, these ten seconds had been ground up into ten thousand uncorrelated moments and scattered throughout real time -- and in model time, the outside world had suffered an equivalent fate. Yet the pattern of his awareness remained perfectly intact: somehow he found himself, "assembled himself from these scrambled fragments. He'd been taken apart like a jigsaw puzzle -- but his dissection and shuffling were transparent to him. Somehow -- on their own terms -- the pieces remained connected.

"Eight. Nine. Ten."

Squeak. "You're sweating."

"Both of me?"

Squeak. The djinn laughed. "What do you think?"

Paul said, "Do me one small favor. The experiment is over. Shut down one of me -- control or subject, I don't care."

Squeak. "Done."

"Now there's no need to conceal anything, is there? So run the pseudo-random effect on me again -- and stay on-line. This time, you count to ten."

Squeak. Durham shook his head. "Can't do it, Paul. Think about it: you can't be computed non-sequentially when past perceptions aren't known."

Of course; the broken vase problem all over again.

Paul said, "Record yourself, then, and use that."

The djinn seemed to find the request amusing, but he agreed; he even slowed down the recording so it lasted ten model-time seconds. Paul watched the blurred lips and jaws intently, listened carefully to the drone of white noise.

Squeak. "Happy now?"

"You did scramble me, and not the recording?"

Squeak. "Of course. Your wish is my command."

"Yeah? Then do it again."

Durham grimaced, but obliged.

Paul said, "Now, scramble the recording."

It looked just the same. Of course.

"Again."

Squeak. "What's the point of all this?"

"Just do it."

Paul watched, the hairs on the back of his neck rising, convinced that he was on the verge of . . . what? Finally confronting the "obvious" fact that the wildest permutations in the relationship between model time and real time would be undetectable to an isolated Copy? He'd accepted the near certainty of that, tacitly, for almost twenty years . . . but the firsthand experience of having his mind literally scrambled -- to absolutely no effect -- was still provocative in a way that the abstract understanding had never been.

He said, "When do we move on to the next stage?"

Squeak. "Why so keen all of a sudden?"

"Nothing's changed. I just want to get it over and done with."

Squeak. "Lining up all the other machines is taking some delicate negotiations. The network allocation software isn't designed to accommodate whims about geography. It's a bit like going to a bank and asking to deposit some money . . . at a certain location in a particular computer's memory. Basically, people think I'm crazy."

Paul felt a momentary pang of empathy, recalling his own anticipation of these difficulties. Empathy verging on identification. He smothered it. The two of them were irreversibly different people now, with different problems and different goals -- and the stupidest thing he could do would be to forget that.

Squeak. "I could suspend you while I finalize the arrangements, save you the boredom -- if that's what you want."

"You're too kind. But I'd rather stay conscious. I've got a lot to think about."

7

(Remit not paucity)

NOVEMBER 2050

"Twelve to eighteen months? Are they sure?"

Francesca Deluca said drily, "What can I say? They modeled it."

Maria did her best to sound calm. "That's plenty of time. We'll get you scanned. We'll get the money together. I can sell the house, and borrow some from Aden --"

Francesca smiled but shook her head. "No, darling." Her hair had grayed a little since Maria had last really looked at her, last consciously gauged her appearance, but she showed no obvious signs of ill health. "What's the point? Even if I wanted that -- and I don't -- what's the use of a scan that will never be run?"