Lloyd was silent for a time. Finally, gently, he went on. "You said before that maybe I was embracing the idea that the future was immutable too readily. But I'm not. I'm not just looking for a way to avoid guilt — and I'm certainly not looking for a way to avoid marrying you, darling. But that the visions are real is the only conclusion possible based on the physics I know. The math is abstruse, I'll grant you, but there's an excellent theoretical basis for supporting the Minkowski interpretation."

"Physics can change in twenty-one years," said Michiko. "There was a lot of stuff they believed in 1988 that we know isn't true today. A new paradigm, a new model, might displace Minkowski or Einstein."

Lloyd didn't know what to say.

"It could happen," said Michiko earnestly.

Lloyd tried to make his tone soft. "I need — I need something more than just your fervent wish. I need a rational explanation; I need a solid theory that could explain why the visions are anything but the one true fixed future." He stopped himself before he added, "A future in which we aren't meant to be together."

Michiko's voice was growing desperate. "Well, okay, all right, maybe the visions are of an actual, real future — but not of 2030."

Lloyd knew he shouldn't push it; knew that Michiko was vulnerable — hell, knew that he was vulnerable. But she had to face reality. "The evidence from newspapers seems pretty conclusive," he said softly.

"No — no, it's not." Michiko sounded increasingly adamant. "It isn't really. The visions could be of a time much farther in the future."

"What do you mean?"

"Do you know who Frank Tipler is?"

Lloyd frowned. "A candid drunk?"

"What? Oh, I get it — but it's Tipler with one P. He wrote The Physics of Immortality."

"The Physics of what?" said Lloyd, eyebrows rising.

"Immortality. Living forever. It's what you always wanted, isn't it? All the time in the world; all the time to do all the things you want to do. Well, Tipler says that at the Omega Point — the end of time — we will all be resurrected and live forever."

"What kind of gibberish is that?"

"I admit it's a whopper," said Michiko. "But he made a good case."

"Oh?" said Lloyd, the syllable pregnant with skepticism.

"He says that computer-based life will eventually supplant biological life, and that information-processing capabilities will continue to expand year after year, until at some point, in the far future, no conceivable computing problem will be impossible. There will be nothing that the future machine life won't have the power and resources to calculate."

''I suppose."

"Now, consider an exact, specific description of every atom in a human body: what type it is, where it is located, and how it relates to the other atoms in the body. If you knew that, you could resurrect a person in his entirety: an exact duplicate, right down to the unique memories stored in the brain and the exact sequence of nucleotides making up his DNA. Tipler says that a sufficiently advanced computer far enough in the future could easily recreate you, just by building up a simulacrum that reflects the same information — the same atoms, in the same places."

"But there's no record of me. You can't reconstruct me without — I don't know — some kind of scan of me… something like that."

"It doesn't matter. You could be reproduced without any specific info about you."

"What are you talking about?"

"Tipler says there are about 110,000 active genes that make up a human being. That means that all the possible permutations of those genes — all the possible biologically distinct human beings that could conceivably exist — amount to about ten to the tenth to the sixth different people. So if you were to simulate all those permutations — "

"Simulate ten to the tenth to the sixth human beings?" said Lloyd. "Come on!"

"It all follows from saying that you have essentially infinite information-processing capabilities," said Michiko. "There may be oodles of possible humans, but it is a finite number."

"Just barely finite."

"There are also a finite number of possible memory states. With enough storage capacity, not only could you reproduce every possible human being, but also every possible set of memories each of them could have."

"But you'd need one simulated human for every memory state," said Lloyd. "One in which I ate pizza last night — or at least had memories of doing that. Another in which I ate a hamburger. Et cetera, et cetera, ad nauseam."

"Exactly. But Tipler says you could reproduce all possible humans that could ever exist, and all possible memories that they could ever have, in ten to the tenth to the twenty-third bits."

"Ten to the tenth to the… "

"Ten to the tenth to the twenty-third."

"That's crazy," said Lloyd.

"It's a finite quantity. And it could all be reproduced on a sufficiently advanced computer."

"But why would anyone do that?"

"Well, Tipler says the Omega Point loves us, and — "

"Loves us?"

"You really should read the book; he makes it sound much more reasonable than I do."

"He'd pretty much have to," said Lloyd, deadpan.

"And remember that the passage of time will slow down as the universe comes to an end, if it eventually is going to collapse down into a Big Crunch — "

"Most studies indicate that's not going to happen, you know; there isn't enough mass, even taking into account dark matter, to close the universe."

Michiko pressed on. "But if it does collapse, time will be protracted so that it will seem to take forever to do so. And that means the resurrected humans will seem to live forever: they'll be immortal."

"Oh, come on. Someday, if I'm lucky, maybe I'll get a Nobel. But that's about as much immortality as anyone could ever hope for."

"Not according to Tipler," said Michiko.

"And you buy this?"

"Wellll, no, not entirely. But even if you set aside Tipler's religious overtones, couldn't you envision a far, far future in which — I don't know, in which some bored high-school student decides to simulate every possible human and every possible memory state?"

"I guess. Maybe."

"In fact, he doesn't have to simulate all the possible states — he could simulate just one random one."

"Oh, I see. And you're saying that what we saw — the visions — they're not of the actual future twenty-one years from now, but rather are from this far-future science experiment. A simulation, one possible take. Just one of the infinite — excuse me, almost infinite possible futures."

"Exactly!"

Lloyd shook his head. "That's pretty hard to swallow."

"Is it? Is it really? Is it any harder to swallow than the idea that we have seen the future, and that future is immutable, and even foreknowledge of it won't be enough to allow us to prevent that future from coming true? I mean, come on: if you have a vision that says you'll be in Mongolia in twenty-one years, all you have to do to defeat the vision is not go to Mongolia. Surely you're not predicting that you're going to be forced to go there, against your will? Surely we have volition."

Lloyd tried to keep his voice soft. He was used to arguing science with other people, but not with Michiko. Even an intellectual debate had a personal edge. "If the vision has you in Mongolia, you'll end up being there. Oh, you may have every intention of never going there, but it'll happen, and it'll seem quite natural at the time. You know as well as I do that humans are lousy at realizing their desires. You can make a promise today that you're going to go on a diet, and have every intention of still being on it a month from now, but, somehow, without it seeming like you have no free will at all, you might very well be off your diet by then."