Factoring Humanity Read Online Free PDF Page B

finger. “That is the question! And there are two possible answers. The one that’s simply weird is that in transit between the lightbulb and the film, the single photon breaks up into a series of waves, some of which go through one slit and some through the other, forming the interference pattern.
    “But the other answer—the really interesting answer—is that the photon never breaks up, but rather remains a discrete particle, and as such, it has no choice but to go through only one of the two possible slits— in this universe. But just as you, Kyle, could have taken either route around Queen’s Park, so the photon could have taken the path through either slit— and in a parallel universe, it took the other path.”
    “But how come we see the interference pattern?” asked D’Annunzio, chewing gum as he spoke. “I mean, if we stood south of the Parliament Buildings, we’d never see two versions of Graves, one coming around the east side and one around the west.”
    “Excellent question!” crowed Papineau. “The answer is that the two-slit experiment is a very special example of parallel universes. The original single universe splits into two universes once the photon encounters the slits, but the two universes exist separately only so long as the photon is traveling. Since it makes no difference now or ever which path the photon actually took, the universes collapse back together into a single universe. The only evidence that the two universes ever existed is the interference pattern left behind on the film.”
    “But what if it does make a difference which slit was chosen?” asked Roopshand from the back.
    “In any experiment you can devise in which the choice of slit actually matters—indeed, in any experiment in which you can detect which slit the photon went through—you don’t get the interference pattern. If it matters at all, the universes never stitch back together into one; they continue on as two separate universes.
    It had been a heady class—as all of Papineau’s were. And it had also been a metaphor that Kyle carried with him throughout his life: choices, branching paths.
    Back then, back in 1996, even though he and Heather were still students, he knew which choice he wanted. He wanted to live in the universe in which they did have a baby.
    And so that November, their first child, Mary Lorraine Graves, was born.

 
     
     
    5

    Kyle was walking along Willcocks Street, heading from New College back toward Mullin Hall, but he was accosted before he could cross St. George.
    “Sir—excuse me. Sir, pardon me! Yes, you. Dale Wong, City-TV. We’d like to ask you a question.”
    “A streeter?” said Kyle, the word coming to him from somewhere.
    The young man with the camcorder was amused. “Exactly, sir. A streeter. Here’s our question. Today is the tenth anniversary of the receipt of the first radio message from Alpha Centauri.”
    “Is it really?”
    “Yes, sir. How has it affected you this past decade, knowing that there’s intelligent life elsewhere in the universe?”
    Kyle frowned, thinking. “Well, that’s a good question. It’s certainly interesting—my wife actually works on trying to decode the alien radio messages.”
    “But how has it changed you—changed your outlook?”
    “Well, I suppose it gives me a little perspective on things. You know—all our problems don’t amount to much, compared to the limitless universe.” The words rang false as they came out. Kyle paused—long enough, he knew, that the man wouldn’t be able to use the video clip without editing. “No, no, that’s not it. You want the truth? It hasn’t changed a damn thing. No matter how big the universe gets, we’re always looking inside.”
    “Thank you, sir. Thank—Ma’am! Ma’am! A moment of your time, please!”
    Kyle continued to walk. He hadn’t really thought about it before, but his current research project clearly had had its genesis back in the spring of 1996, the same day