Factoring Humanity

  Times big L: the lifetime of such a civilization.

  A civilization that had radio probably also had nuclear weapons, or other equally dangerous things.

  Civilizations could be wiped out in a matter of moments—certainly in less than a single thirty-one-hour day.

  “They can’t be dead,” said Salme.

  “They’re either dead, or they voluntarily stopped, or the message is complete.”

  There was a knock at the door. Heather covered the mouthpiece. “Come in!”

  The departmental assistant stuck his head in. “Sorry to bother you, Professor Davis, but the CBC is on the phone. They want to talk to you about what happened to the aliens.”

  10

  Kyle’s lab was crowded. The dean leaned against one wall, the department chair had his butt perched on the shelf jutting out of the bottom of Cheetah’s console, a lawyer from the university’s patent unit sat in Kyle’s usual chair, and the five grad students who worked on Kyle’s quantum-computing team were milling around as well.

  “Okay,” said Kyle to the group. “As you know, there’s been a technique available since nineteen ninety-six for producing simple quantum-logic gates; that technique was based on using nuclear magnetic resonance to measure atomic spins. But it was hampered by the fact that as you added bits, the output signal got exponentially weaker: a thirty-bit quantum computer based on that principle produces output only one-billionth as strong as that from a one-bit computer based on the same technique.

  “Well, the method we’re going to demonstrate today is, we believe, the long-sought-after breakthrough: a quantum computer that, in theory, can employ an unlimited number of bits with no reduction in output quality. For our demo today, we’re going to try to factor a randomly generated three-hundred-digit number. To do that on the department’s ECB-5000 would take approximately one hundred years of constant calculation. If we’re right—if this works—we’ll have an answer about thirty seconds after I commence the experiment.”

  He moved across the room.

  “Our prototype quantum computer, which we call Democritus, has not just thirty registers, but one thousand, each of which consists of a single atom. The results will be a series of interference patterns, which another computer—that one over there—will analyze and reduce to a numeric readout.” He looked from face to face. “All set? Let’s go.”

  Kyle walked over to the simple black console containing the Democritus computer. For the sake of drama, they’d built a large knife switch, worthy of Frankenstein’s lab, into the side of the cabinet. Kyle pulled it down, its blade touching the metal contacts. A bright red LED came on and—

  —and everyone held their breath. Kyle kept watching Democritus, which, of course, was operating absolutely silently. Part of him missed the old days of clicking relays. Others were watching the digital clock mounted next to the red EXIT sign on the curving wall.

  Ten seconds went by.

  Then ten more.

  Then a final ten.

  And then the LED went dark.

  Kyle let out his breath.

  “Done,” he said, heart pounding.

  He gestured for everyone to follow him across the room. There, another computer was analyzing the output from Democritus.

  “It’ll take about five minutes to decode the interference pattern,” said Kyle. He allowed himself a smile. “If you’re thinking that that’s a lot longer than it took to produce the pattern, you’re right—but we’re now dealing with a conventional computer.”

  “How many computations would it take to factor a number that big?” asked the dean, her voice clearly intrigued.

  “Approximately ten to the five hundredth,” said Kyle.

  “And there’s no way to do it in fewer steps?” she asked. “This isn’t a case of Democritus taking a shortcut?”

  Kyle shook his head. “No, it really does take ten to the five hundredth steps to factor a number that big.”

  “But Democritus didn’t do that many steps.”

  “This Democritus didn’t—in fact, it performed only one calculation, using a thousand atoms as the stones in its abacus, so to speak, to do so. But if all went well, 10500 other Democrituses in other universes will also each have done one calculation—involving, of course, a total of a thousand times 10500 atoms, which is 10503 atoms. And that, my friends, is a very significant number.”

  “How so?” asked the department chair.

  “Well, the precise value isn’t important. What is important is how it relates to the number of atoms in our entire universe.” Kyle smiled, waiting for the inevitable question.

  “And how many atoms are there in our universe?” asked the dean.

  “I called up Holtz over in the McLennan Physical Labs and asked her,” said Kyle. “The answer, plus or minus a couple of orders of magnitude, is that there are ten to the eightieth atoms in the universe.”

  A few jaws dropped.

  “Do you see?” said Kyle. “In that thirty-second period, to factor our test number, Democritus must have accessed many trillions of times more atoms than there are in our entire universe. Other, earlier quantum-computing demonstrations have never involved enough bits to actually exceed the quantity of atoms available to them in our universe, leaving open some doubt as to whether they’d actually accessed parallel worlds, but if this experiment works, the only answer will be that our Democritus worked in tandem with computers in other universes.”

  The conventional computer they were standing in front of beeped and one of its monitors came to life. Precisely two strings of numbers appeared on the screen, each dozens of digits long.

  “Are those the first two factors?” asked the lawyer, clearly anxious to start notarizing things.

  Kyle felt his heart sink. “Ah, no. No.” He swallowed; his stomach was roiling. “I mean, yes, certainly, they are doubtless factors of our source number, but—but. . .”

  One of Kyle’s grad students looked at him and then said the words that, at that moment, Kyle himself couldn’t get out. “The display shouldn’t have appeared until all the factors are ready. Unless by some miracle, the source number has only two factors, then the experiment didn’t work.”

  The department head loomed in at the screen and placed his index finger on the last digit of the second number; it was a four. “That’s an even number, so there have got to be smaller factors that aren’t displayed.” He straightened up. “What went wrong?”

  Kyle was shaking his head. “It worked—sort of. Our Democritus did do only one calculation. The other number must have come from a parallel universe.”

  “You can’t prove that,” said the dean. “Only two calculations means that only two thousand atoms were involved.”

  “I know,” said Kyle. He breathed out. “Sorry, everyone. We’ll keep working on it.”

  The dean frowned, presumably thinking of all the money that had already been spent. She left the room. The department head laid a hand briefly on Kyle’s slumped shoulder before he, too, left, followed by the lawyer.

  Kyle looked at his grad students and shrugged. Nothing was going his way these days . . .

  After the students went home, Kyle sat down in his chair in front of Cheetah’s console.

  “I’m sorry,” said Cheetah.

  “Yeah,” said Kyle. He shook his head. “It should have worked.”

  “I’m confident you’ll figure out what went wrong.”

  “I suppose.” He looked up at the print of “Christus Hypercubus.” “But maybe it’ll never work; researchers have been trying to accomplish this for over twenty years without success. He dropped his gaze to the floor. “I just keep wasting my time on projects that never bear fruit.”

  “Like me,” said Cheetah, without rancor.

  Kyle said nothing.

  “I have faith in you,” said Cheetah.

  Kyle made a sound in his throat, a laugh aborted.

  “What?”

  “I dunno. Maybe that’s the whole problem. May
be it’s my lack of faith.”

  “You mean God is punishing you for being an atheist?”

  Kyle did laugh, but it was humorless. “Not that kind of faith. I mean my faith in quantum physics.” He paused. “When I was a grad student, nothing excited me like quantum mechanics—it was mind-expanding, endlessly fascinating. But I felt sure that someday it would all click, you know—all make sense. Someday I’d really see. But I never have. Oh, I understand the equations in an abstract way, but I don’t get it, you know? Maybe I don’t even really believe it.”

  “You’ve lost me,” said Cheetah.

  Kyle spread his arms, trying to find a way to explain it. “I was at a party once, and this fat guy comes in, and he’s got a slice through a geode held to his forehead by a headband. I never asked about it—guy comes in with something like that, you don’t ask. But his companion, a scrawny woman, must have noticed me looking at the geode, so she comes over and says, ‘That’s Cory—he’s gifted with the third eye.’ And I’m thinking, Good Christ, let me out of here. Later, Cory comes up to me and says, ‘Hey, man, what time is it?’ And I’m thinking what good is the third eye if you don’t even know what fucking time it is?”

  Cheetah was quiet for a while. “And your point would be . . . ?”

  “My point is that maybe you do need some special insight to understand—really, deeply understand—quantum mechanics. Einstein never did, you know; he was never comfortable with it, calling it ‘spooky action at a distance.’ But some of these guys in quantum mechanics, they do get it—either that or they fake it really well. Me, I always thought I’d be one of those who’d get it, too—that it would click at some point. But it hasn’t. I never developed the third eye.”

  “Maybe you should get a geode slice from the Earth Sciences Centre.”

  Kyle grunted. “Maybe. I guess down deep, at some basic level, I just don’t buy quantum mechanics. I feel like a bit of a charlatan.”

  “Democritus did indeed communicate with at least one other alternative reality. That seems to confirm the many-worlds interpretation.”

  Kyle looked at Cheetah’s lenses. “That’s it,” he said simply. “That’s the problem. This type of quantum computing hinges on the many-worlds interpretation, but, come on, really, how plausible is that? Surely not every conceivable universe exists, but rather only the ones that have at least some likelihood of having occurred.”

  “For instance?” asked Cheetah.

  “Well,” said Kyle, “there’s no recorded case of anyone ever being killed by a meteor falling on them, but it could happen. So, is there a universe in which I was killed that way yesterday? Another one in which I was killed that way the day before? A third in which I was killed that way the day before that? A fourth, fifth, and sixth in which it was my brother, not me, who was killed? A seventh, eighth, and ninth in which both of us were killed on those days by meteor impacts?”

  Cheetah did not hesitate. “No.”

  “Why not?”

  “Because meteors have no volition—in every universe, precisely the same meteors hit the Earth.”

  “All right,” said Kyle, “but say one crashes today in—I don’t know—say in Antarctica. Now, I’ve never been to Antarctica, and I never intend to go there, but is there some parallel universe in which I did go, and in which I happened to be killed by that meteor? And then aren’t there seven billion times as many universes, accounting for all the people alive who might instead have gone to Antarctica?”

  “It does seem rather an awful lot of parallel universes, doesn’t it?” said Cheetah.

  “Exactly. In which case there must be some sort of filtration process—something that distinguishes between conceivable universes and plausible ones, between those that we simply can imagine and those that have some reasonable chance of actually existing. That could explain why we only got one other factor back in the experiment.”

  “I suppose you’re right and—oh.”

  “What?” said Kyle.

  “I see what you’re getting at.”

  Kyle was surprised; he wasn’t sure he himself knew what he was getting at. “And that is?”

  “The ethics of the many-worlds interpretation.”

  Kyle considered. “You know, I guess you’re right. Say I find a wallet that contains an unlocked SmartCash card with a thousand dollars on it. Say the wallet also has a driver’s license in it; I’ve got the rightful owner’s name and address right there.”

  Cheetah had a cross-shaped pattern of LEDs on his console. He could activate the vertical column of them or the horizontal row to simulate either nodding or shaking his head. He did his nod.

  “Well,” said Kyle, “according to the many-worlds interpretation, anything that can possibly go two ways does go two ways. There’s a universe in which I return the money to the person who lost it, but there’s also a universe in which I keep it for myself. Now, if there are bound to be two universes, then why the heck shouldn’t I be the guy who keeps the money?”

  “An intriguing question, and without impugning your character, such a dilemma does seem within the realm of possibility. But I suspect your moral concerns run deeper: I suspect you’re wondering about you and Rebecca. Even if in this universe you didn’t molest her, you’re wondering if there is some conceivable universe in which you did.”

  Kyle slumped back in his chair. Cheetah was right. For once, the goddamned machine was right.

  It was an insidious thing, the human mind. The mere accusation was enough to get it working, even against itself.

  And was there such a universe? A universe where he really could creep into his own daughter’s room after midnight and do those horrible things to her?

  Not here, of course. Not in this universe. But in another one—one, perhaps, where he hadn’t got tenure, where his control over life had slipped away, where he drank more than he should, where he and Heather were still fighting to keep the wolf from the door—or where they had divorced early on, or he was a widower, and his own sexuality was finding no normal outlet.

  Could such a universe exist? Could Becky’s memories, although false in this universe, be a true reflection of another reality? Could she now have access, through some quantum aberration, to those memories from a parallel world, just as a quantum computer accesses information from other timelines?

  Or was the very notion that he’d abuse his daughter utterly outlandish, impossible, unthinkable—a meteor conking him on the head in the Antarctic?

  Kyle stood up and did something he’d never done before. He lied to Cheetah.

  “No,” he said. “No, you’re completely wrong about that.”

  He left the lab, the lights shutting off automatically as he did so.

  Maybe, some thought, the Centaurs had simply skipped one day for a holiday on their homeworld, or to indicate some sort of punctuation in the overall message. If that were the case, the next message would come in at 6:36 P.M. the following day, Friday, July 28.

  Heather had spent much of the thirty-one intervening hours dealing with reporters; overnight, the alien messages had gone from being of no general interest to front-page news worldwide. And now the CBC was doing a live remote feed from Heather’s office.

  The news crew had provided a large digital clock, which was attached to the top of Heather’s monitor with masking tape. They’d brought three cameras: one was kept trained on Heather, another on the clock, and the third on her monitor screen.

  The clock was counting down. It was now two minutes to the scheduled time for the next message.

  “Professor Davis,” said the black female reporter, who had a pleasant Jamaican accent, “what are you thinking? What are you feeling as we wait for another message from the stars?”

  Heather had done five other TV appearances over the last thirty-one hours, but she’d yet to come up with an answer she was happy with. “I don’t really know,” she said, trying to follow the reporter’s instruction not to look directly into the camera. “I feel like I’ve l
ost a friend. I never did know what he was saying, but he was there, every day. I could count on him. I could trust him. And now that’s shattered.”

  As she said that, she wondered if Kyle was watching.

  “Twenty seconds,” said the reporter.

  Heather turned to look at the computer monitor.

  “Fifteen.”

  She raised her left hand, fingers crossed.

  “Ten.”

  It couldn’t be finished.

  “Nine.”

  It couldn’t have come to an end.

  “Eight.”

  Not after all this time.

  “Seven.”

  Not after a decade.

  “Six.”

  Not without an answer.

  “Five.”

  Not without the key.

  “Four.”

  Not with it still remaining a mystery.

  “Three.”

  Her heart was pounding.

  “Two.”

  She closed her eyes and astonished herself to find that she was thinking a silent prayer.

  “One.”

  Heather opened her eyes, focused on the screen.

  “Zero.”

  Nothing. It was over.

  11

  Heather pushed the door buzzer outside Kyle’s lab. There was no response. She touched her thumb to the scanning plate, wondering for a moment whether he’d delisted her from the index. But the door slid aside, and she entered the lab.

  “Is that you, Professor Davis?”

  “Oh, hello, Cheetah.”

  “It’s been some time since you’ve dropped by. It’s good to see you.”

  “Thanks. Is Kyle around?”

  “He had to go down to Professor Montgomery’s office; he said he would be back shortly.”

  “Thanks. I’ll wait, if that’s— Good grief, what’s that?”

  “What’s what?” asked Cheetah.

  “That poster. It’s Dali, isn’t it?” The style was unmistakable, but it was a Dali she’d never seen before: a painting of Jesus nailed to a most unusual cross.