Robert Sawyer: Iterations

“I’m going to have to kill you,” I said to myself, matter-of-factly.

The face looking back at me across the desktop was my own, of course, but not the way I was used to seeing it; it wasn’t flopped left-to-right like it is in a mirror. The other me reacted with an appropriate mixture of surprise and disbelief. The shaggy eyebrows went up—God, why don’t I trim those things?—the brown eyes widened, and the mouth opened to utter a protest.

“You can’t kill me,” he—I—said. “I’m you.”

I frowned, disappointed that he didn’t understand. “You’re a me that never should have existed.”

He spread his arms a bit. “Who’s to say which of us should have existed?”

One of the interesting things about working in the publishing industry in Canada is this: it’s full of Americans who came here during Vietnam. And, even if they didn’t want to go to war, some of themdo know how to get guns. “Who’s to say which of us should have existed?” I repeated. I took the Glock 9 mm that Jack Spalding had procured for me out of my pocket and pulled the trigger. “I am.”

I was at home with Mary, my wife and, until everything had fallen apart, my business partner. We were in our bedroom, and I was trying to get through to her. “Don’t you see?” I said, sitting on the edge of the bed. “None of this is real—it can’t be.”

She sat down next to me and began brushing her hair. “What are you talking about?”

“You. Me. This bed. This house. This planet . It’s all faked. It’s all a computer-based simulation.”

Mary shook her head slightly. She hated it when I talked like this.

“It’s true,” I said. “It’s true—and I can prove it.”

She pressed her lips tightly together, and blew air out of her nose. She didn’t say “How?” She didn’t say anything.

I wished there were a more obvious way. I wished I could grab hold of—of that wall there, say, and pull it aside, revealing the machinery beyond, but, of course, I couldn’t. The wall was simulated perfectly; the rest of Toronto was simulated perfectly, too. So was all of Canada, of North America, the entire planet. There was no place I could take her where she would see that corners had been cut, see scaffolding propping up a false front to a non-existent building. This Earth—at least all of its surface, and its atmosphere thinning out to almost nothing a few hundred kilometers up, and its rocky crust, and maybe even some portion of its mantle—were flawlessly reproduced.

But even they had limits. Yes, they could reproduce Earth, or as much of it as humans could ever access, but—

“Look,” I said. “Imagine a space probe that could travel at one-tenth the speed of light.”

She was staring at me as though I wasn’t even speaking English anymore.

I pressed on. “Imagine that space probe, taking decades to get to the next star. And imagine it finding raw materials there to build ten duplicates of itself, and then sending those duplicates, at the same speed, to ten other nearby stars. Even if it took fifty years to find the raw materials and make the duplicates, and fifty more years for those duplicates to travel to their target stars, if the process continued, how long do you think it would take for such probes to colonize the entire galaxy?”

“What are you talking about?” said Mary again.

“Sixty thousand years,” I said, triumphantly. “Give or take. One single probe, launched into space by any civilization anywhere in the Milky Way, could colonize this whole giant galaxy in just sixty thousand years.”

Our little publishing company had been called CanScience Books; I’d been editorial director. Mary didn’t know much about science, but she was a wiz at accounting. “So?”

“So,” I said, “the universe is maybe twelve billion years old.” I grabbed her shoulders. “Don’t you see? Someone somewhere must have launched self-replicating probes like the ones I described. This planet should have been visited by them… but it hasn’t.”

“Maybe there aren’t any other civilizations.”

“Of course there are. There must be.” It drove me nuts that she never read the books we’d published.“Everything we know about physics and chemistry and biology says the universe should be overrun with life. But none of it has come here.” I shifted my weight; maybe I shook her slightly. I so much wanted her to see . “And what about SETI? The search for extraterrestrial intelligence? We’ve been listening for half a century now and haven’t picked up a thing. We shouldn’t need to do anything more than point a radio dish up at the night sky to pick up thousands—millions—of alien signals. But there’s nothing.

“And think about the moon. Do you know how many people have gone to the moon? Twelve! That’s all, in the total history of our race—twelve people have stood on its surface. And no one has gone back; no one even has plans to go back. And what about Mars? We should have landed on it within a few years of going to the moon, but no one’s made it there—and, again, no one is planning to go. And the space probes we send there keep failing. The Mars Climate Orbiter, the Mars Polar Lander—complete write-offs! I mean, let’s be real: an important mission to Mars junked because some engineer couldn’t convert between imperial and metric measurements? It’s unbelievable.”

“I still don’t see—” began Mary.

“Let me spell it out, then: it’s one thing to simulate the Earth. That’s a big computing problem, sure, but it’s doable.”

“Not on any computer I’ve ever seen,” said Mary.

“Well, no, of course it’s not doableyet. But it will be. Eventually, the Earth and everyone who ever lived on itwill be simulateable on sufficiently advanced computers.”

“When?” said Mary.

“Who knows? A million years from now? A billion? Ten billion? Or maybe—Frank Tipler wrote about this—maybe at the very end of time, as the universe is collapsing back down in a big crunch. Eventually there will be sufficient computing power to simulate the entire planet and everyone who ever lived on it.”

“How would they know anything about us?” asked Mary. “How could they possibly simulate you and me without records of what we were like?”

“They won’t need any records.” Why couldn’t she see this? “A human being consists of about thirty thousand active genes. That means that there are about three-to-the-millionth-power possible genetically distinct humans. And there are about 2-to-the-10th-to-the-17th power possible human memories. Multiply it all out, and you’ll find that you could reproduce all possible versions of our world—including every possible combination of human beings, with every possible set of memories—in 10-to-10th-to-the-123rd bits.”

“Ten to the tenth to…”

“To the 123rd, yes,” I said. “And that amount will surely eventually be computable. Meaning that you could—well, Tipler used the word ‘resurrect,’ and that’s as good as any—you could resurrect everyone who ever lived as computer simulations, without knowing anything specific about them.”

Mary looked at me. “And you think that’s what we are? Resurrected versions of people who died billions of years ago?”

“We have to be. It’s the only thing that explains the absence of extraterrestrial probes here, or of radio signals from other civilizations. To simulate Von Neumann probes—that’s what those self-replicating robots are called—and the chatter of alien races would mean simulating the rest of the universe, with its billions of different lifeforms. But they don’t have enough computer memory—or, if they do, they consider it wasteful. So, yes, this world seems real to us, but it’s fake. It has to be.”