Superposition by David Walton

hanging from a hook. I thought of what he’d been wearing when he showed up at my house and picked up the jacket. I felt around, and in one of the pockets I found an envelope. The words “Jacob Kelley” were penned on it in Brian’s handwriting.
    I tore it open and pulled out a single sheet of folded smartpaper. The only words were a single line of printed text: “What is your favorite number?”
    Marek looked over my shoulder. “What’s that, some kind of password request?”
    I smiled. “Something like that. You have a pen?”
    Marek fished a Bic pen out of his pocket, and I wrote “137.036” on the paper. When I stopped, the printing disappeared and was replaced by a longer message:
    Dear Jacob:
    I wanted to come and tell you about all this in person, but I didn’t have the nerve. I think it’s for the best this way. You’re smart; you’ll figure it out, and maybe someday you’ll join me.
    Say goodbye to Cathie for me.
    Brian
    I showed the letter to Marek.
    â€œI thought he did come see you in person,” Marek said.
    â€œYeah. I don’t know what he means. Maybe he changed his mind after he wrote this.” I replaced the jacket on the hook on the back of the door, and a small mirror to one side caught my eye. Something about the light reflected from it seemed wrong. Marek moved in front of it, and his reflection flitted across the mirror in the opposite direction of his movement. Definitely odd. I stepped in front of it, so I could see my own reflection, and saw right away that my hair was parted on the wrong side. It was like looking at a photograph of myself instead of a reflection. I raised my hand, and the wrong hand went up. This wasn’t really a mirror.
    â€œWhat’s going on with this?” I asked. I reached out to lift it off the wall. My reversed reflection in the mirror did the same, though with the wrong hand. I looked in my face, only there was something wrong, so horribly wrong that for a split second I couldn’t figure out what it was. My eyes were missing. In their place, there was only a smooth expanse of skin, unbroken, with not even a cavity where the eyes should have been.
    It was like when a child in a crowded room reaches up and grasps, with easy familiarity, her father’s hand, only to discover that it is not her father after all but a complete stranger. A moment of calm reassurance is transformed into a moment of horror as she realizes that, not only is she holding the hand of a man she doesn’t know, but she has no idea where her father is.
    I jerked away from the mirror, letting it fall back against the wall, and touched my eyes. The reflection in the mirror was normal again, too. “Did you see that?” I asked.
    Marek peered in the mirror, then back at me. “See what?”
    â€œCome on,” I said. “Time to go.”
    â€œWhere are we going?”
    â€œTo say goodbye to Cathie, like the letter says.”
    â€œWho’s Cathie? Someone who works here?”
    â€œCathie’s not a who,” I said. “She’s a what.”

    Underneath the Feynman Center were several levels of subbasement and the main access to the collider ring. The badges Jean had given us granted access to the elevator that descended into the collider tunnel itself. The tunnel was a huge concrete borehole similar in size to a highway tunnel—the same kind of earth-borer machines had been used to dig it out—except that this one was thirty miles long and ran in an ellipse. A large portion of the space was taken up by the particle ring itself—in which the subatomic particles orbited—and the huge electromagnets that straddled it, along with their entourage of other coolant pipes and snaking electrical cables.
    There was a pedestrian path, about fifteen feet wide. Scientists who had to get from place to place along the ring usually rode bicycles, but there were a few golf