Everyone except the geologists adjourned to a conference room at the Creighton Mine: Mary Vaughan, the geneticist who’d come up from Toronto; Reuben Montego, the Inco doctor; Louise Benoit, the SNO postdoc who had been on hand when the detector had been destroyed; Bonnie Jean Mah, director of the SNO project; and, most important of all, Ponter Boddit, physicist from a parallel world, the only living Neanderthal to be seen on this Earth since at least 27,000 years ago.
Mary had chosen to sit beside Bonnie Jean Mah, the only woman in the room who’d had an empty chair next to her. Holding forth, standing at the front of the room, was Reuben Montego. “Question,” he said in that Jamaican accent Mary found delightful. “Why is there a mining operation on this site?”
Mary herself had no clue, and none of those who obviously did know looked inclined to play games, but at last Bonnie Jean Mah replied. “Because 1.8 billion years ago,” she said, “an asteroid hit here, resulting in huge deposits of nickel.”
“Exactly,” said Reuben. “An event that happened long before there was any multicellular life on Earth, an event both Ponter’s world and ours share in their common pasts.” He looked from face to face, coming at last to Mary’s own. “One has little choice in where mines will be built,” Reuben said. “You put them where the ores are. But what about SNO? Why was it built here?”
“Because,” said Mah, “the two kilometers of rock over top of the mine provide an excellent shield against cosmic rays, making it an ideal location for a neutrino detector.”
“But it’s not just that, is it, ma’am?” said Reuben, who, Mary assumed, had become quite the expert thanks to the help of Louise. “There are deep mines elsewhere on the planet. But this mine also has very low background radiation, right? In fact, this site is uniquely qualified for housing instruments that would be adversely affected by natural radiation.”
This sounded reasonable to Mary, and she noted that Professor Mah nodded once. But then Mah added, “So?”
“So,” said Reuben, “in Ponter’s universe a deep mine was also built on this very spot, to excavate the same nickel deposits. And eventually he himself recognized the value of the site and convinced his government to set up a physics facility underground here.”
“So he would have us believe that there’s a neutrino detector at the same place in the other universe?” asked Mah.
Reuben shook his head. “No,” he said. “No, there isn’t. Remember, the choice of using this facility for a neutrino observatory also had to do with a historical accident: that Canada’s nuclear reactors, unlike those of the U.S. or the U.K. or Japan or Russia, happen to use heavy water as a moderator. That set of circumstances isn’t duplicated in Ponter’s world-in fact, they don’t seem to use nuclear power. But this underground facility is equally good for another very delicate kind of instrument.” He paused and looked from face to face, then he said, “Ponter, where do you work?”
Ponter replied, “Dusble korbul to kalbtadu.” And the implant, using its male voice, provided the translation: “In a quantum-computing facility.”
“Quantum computing?” repeated Mary, but feeling uncomfortable doing so; she wasn’t used to being the most ignorant one in the room.
“That’s right,” said Reuben, grinning. “Dr. Benoit?”
Louise got up and nodded at the M.D. “Quantum computing is something we’re just starting to play with ourselves,” she said, pushing hair out of her eyes. “A regular computer can determine the factors of a given number by trying one possible factor to see if it works, then another, then another, then another: brute-force calculation. But if you used a conventional computer to factor a big number-say, one with 512 digits, like those used to encrypt credit-card transactions on the World Wide Web-it would take countless centuries to try all the possible factors one at a time.”
She, too, looked from face to face, making sure she hadn’t lost her audience. “But a quantum computer uses superposition of quantum states to check multiple possible factors simultaneously,” said Louise. “That is, in essence, new short-lived duplicate universes are spun off specifically to do the quantum calculation, and, once the factoring is complete-which would be virtually instantaneously-all those universes collapse back down into one again, since, except for the candidate number they tested to see if it was a factor, they’re otherwise identical. And so, in the time it takes to try just one factor, you actually get them all tried simultaneously, and you solve a previously intractable problem.” She paused. “At least, until now, that’s how we’ve believed quantum computing works-relying on the momentary superposition of quantum states effectively creating different universes.”
Mary nodded, trying to follow along.
“But suppose that isn’t how it really happens,” said Louise. “Suppose that rather than creating temporary universes for a fraction of a second, a quantum computer instead accesses already existing parallel universes-other versions of reality in which the quantum computer also exists.”
“There’s no theoretical basis for believing that,” said Bonnie Jean, sounding annoyed. “And, besides, there’s no quantum computer at this location, in the only universe that we know does exist.”
“Exactly!” said Louise. “What I propose is this: Dr. Boddit and his colleague were trying to factor a number so large that to check every possible factor of it required more versions of the quantum computer than there were in separate already existing long-term universes. Do you see? It reached into thousands-millions! — of existing ones. And in each of those parallel universes, the quantum computer found a duplicate of itself, and that duplicate tried a different potential factor. Right? But what if you were factoring a huge number, a gigantic number, a number with more possible factors than there are parallel universes in which the quantum-computing facility already exists? What then? Well, I think that’s what happened here: Dr. Boddit and his partner were factoring a gigantic number, the quantum computer found its siblings in all-every single one-of the parallel universes in which it already existed, but it still needed more copies of itself, and so it went looking in other parallel universes, including ones in which the quantum-computing facility had never been built-such as our universe. And when it reached one of those, it was like hitting a wall, causing the factoring experiment to abort. And that crash caused a large part of Ponter’s computing facility to be transferred into this universe.”
Mary noted that Dr. Mah was nodding. “The air that accompanied Ponter.”
“Exactly,” said Louise. “As we’d guessed, it was mostly just air transferred to this universe-enough air to burst open the acrylic sphere. But, in addition to the air, one person, who happened to be standing in the quantum-computing facility, was transferred, as well.”
“So he didn’t know he was going to come here?” asked Mah.
“No,” said Reuben Montego, “he didn’t. If you think we were shocked, imagine how shocked he was. The poor guy instantly found himself submerged in water, in absolute darkness. If there hadn’t been that massive bubble of air transferred with him, he would have drowned for sure.”
Your whole world turned inside out, thought Mary. She looked at the Neanderthal. He was certainly doing a good job of hiding the disorientation and fear he must feel, but the shock surely had been enormous.
Mary gave him a small, empathetic smile.