Secret Passages

by Paul Preuss

  “Endaxi.” Minakis shrugged. “You can do it with a single photon. It interferes with itself if it goes through both slits; if only one slit is open, it makes a discrete hit. But how does it know, before it gets to the barrier, whether it will encounter two slits or one? How does it know whether to behave like a particle or a wave?”

  “You think, because of this signal moving backward in time.”

  He nodded. She was quick, perhaps a little too quick; she wasn’t listening so much as keeping him talking, a photographer’s trick. “At the moment the photon is emitted, a signal from the future tells it the outcome. The catch is, the signal moving backward in time covers exactly the same interval as the signal moving forward in time.”

  “So it could never be detected,” she murmured, her fist pressed against her lips as she held the camera to her eye and rapidly shot more frames.

  “Which is why it normally goes undetected,” Minakis said, gently correcting her. He patted the optical bench. “What we’ve done is to shrink time along one leg of the transaction—shrink it in the forward direction, so to speak. Warp time like a bow.”

  “I get it…I think.” She let her camera fall to her chest “By speeding up time along one leg of the path, you spoil the transaction.”

  “Malista. The result comes back before the photon goes anywhere. ‘One slit is closed,’ says the future signal—or in this case, ‘One beam path is closed’—so the photon expects to behave like a particle. Meanwhile the experimenter fools it and opens the other slit, the other beam path, too. But the outcome has already been signaled, and the result is a particlelike splotch, not the wavy interference one would expect of superposed paths. Impossible! Or if the photon thinks both paths are open, the experimenter closes one, and in this case a single path produces wavelike interference. Impossible again!”

  “That’s what you’ve done with this setup?”

  “I’ll show you. This laser is the photon source. The beam splitter sends part of the beam to Ambelakia.”

  He invited her to peer through the aiming telescope, and she bent to the eyepiece. Centered in the crosshairs was an array of corner reflectors cemented to the roof of a chapel, reflecting only the evening sky.

  “Half the beam goes forty kilometers and comes back. The other half follows a parallel path of the same length—because it is reflected numerous times by these spinning prisms. Then the beams are recombined, as in an ordinary Michelson interferometer. According to the Copenhagen interpretation, each photon is taking two superposed paths, both possible, neither definite, like Schrödinger’s alive-dead cat, until somebody observes the result.”

  Minakis paused and grinned at Anne-Marie as if he were about to reveal a secret. “We’re interested in which path the photon really took.” He tapped a key on the computer keyboard and a heavy disk rotated, snapping an instrument into position on the tabletop. “You see, we can arrange the path so that each time the distant beam comes back to the tabletop it goes through this black box.”

  The “black” box was in fact a gray box of painted steel a foot long, with thickly filtered, lenslike openings aligned between two mirrors on the steel bench. “A photon spends no time in here. I mean that literally—it gets through this box faster than light.”

  Sticking with what made literal sense to her, Anne-Marie said, “So you’re splitting a photon and messing with half of it. You can mess with what information it gets from the future—what it knows about what effect it is supposed to cause.”

  “Nicely put,” he said dryly. Perhaps she had been listening.

  “Where’s the crunch?”

  “Ah, the crunch. It’s here, where the two light paths recombine.”

  In train behind the black box was a larger steel box, as wide and tall as a ream of business stationery, fitted with an optical tube in its center and hinged to the bench along its edge. Minakis folded it back, revealing a flat metal plate as big as a sheet of paper, coated with a dull sheen. “It’s a CCD, a charge-coupled device that sends information about photon hits to the computer.” With a long finger he tapped the thin plate. From it, flat strips of optical fiber ran to the computer against the wall. “When photons arrive here, the computer counts the hits and constructs either an interference pattern or a discrete splotch—according to whether two beams are open or only one. But if the black box is in the second beam line, the photons are getting information of outcomes before there have been any outcomes. So the computer shows us whether information from the future has changed the photon’s past.”

  “Do I get to watch this miracle?” Anne-Marie asked quietly.

  “You call it a miracle?” Minakis replaced the hood over the CCD plate and snapped it into place. “Perhaps it is a miracle—that the world is real.”

  The rotating prisms spun with an ear-needling whistle. Minakis and Anne-Marie peered at the computer screen.

  “Without the black box, here’s what one beam looks like,” Minakis said. The computer screen showed a glowing white splotch in the middle of an otherwise dark screen, brightest in the middle, fading toward the edges, like a burned-out picture tube.

  “And here’s both beams.” He tapped the keyboard. Under the scream of the prisms Anne-Marie could hear the soft click of a solenoid shutter snapping out of the beam path. The computer screen instantly flipped to a pattern of concentric circles, bright lines alternating with black lines, the crests and troughs of interfering waves of light.

  “Now we put in the black box.” Minakis tapped the keyboard. The turntable whirred, sliding the black box into place, momentarily interrupting the beam. The interference fringes vanished and the plain white splotch reappeared.

  Anne-Marie leaned forward to peer over Minakis’s shoulder. “How do I know that’s just because you blocked the second path with the black box?”

  “You’re a skeptic. Excellent.” He tapped a series of commands on the keyboard, the alphanumerics appearing in a stripe down the side of the screen. “I’m instructing the shutters to leave both paths open until a packet of photons has reached the beam splitter, but to close the first beam before they can be recombined. This will happen very rapidly and repeatedly, in order to build up an image. In the interim, both beams will be blocked.”

  Minakis pressed Enter. The screen went dim, but within a second a perfectly circular interference pattern had assembled: the photons traveling on a single path to Ambelakia and back were behaving as if they had traveled along two paths.

  If Anne-Marie were to believe what she saw, the simple display on the screen was evidence that Minakis could trick the future—even recover the past, a few milliseconds of it.

  “Of course, this could all be in the computer itself, just a program I’m running to fool you,” Minakis said happily.

  Anne-Marie’s smile was a grimace. “I doubt I’m worth the effort.”

  “I have to go home now,” Dimitris announced loudly. All this time he had been standing beside the door, listening to their conversation in English. Evidently he had abandoned the attempt to understand. “My father will want me at the taverna.”

  “Thanks for your help, Dimitri.” Minakis turned from the screen. “You and I will talk later.” He groped in his jacket and handed the boy a brown envelope. “If I were you, I wouldn’t let your father have all of this. You did the work.”

  Dimitris grinned. “There are lots of good hiding places on the way back to the village, kyrie.”

  Minakis and Anne-Marie went outside and watched as Dimitris led the donkey down the stony track. Relieved of her burdens, Irini stepped lightly.

  Anne-Marie sat on the rocky ground, settling her back against the chapel wall, to watch the moon rise over Dikti, while Minakis went inside to turn off the switches and rewrap the interferometer in its plastic shroud. When he came back out, he dropped easily to the ground beside her, as flexibly as a teenager. For a few moments they savored the spectacle of moonrise over the bare cliffs.

  “I observe that the moon is rising,”
Anne-Marie said soberly.

  Minakis threw back his head and laughed, and he was still wiping tears from his eyes when she turned to him, a sly grin on her face.

  But her grin soon faded, and his chuckles died. “What next?” she asked. “Why haven’t you published what you’ve done? Why hasn’t the world heard all about it? Especially my husband.”

  “My former colleagues have published, although my name is not on their papers. Anyone who wants to spend the time and money can replicate our experiment.” His smile was sour. “Meanwhile reports of superluminal photons go into the hopper of unbelievable results, along with naked quarks and the like.”

  “Why isn’t your name on those papers?”

  “I didn’t want it there. I don’t publish fragments. What I’ve showed you is not what I set out to do.”

  “All this hinting! Just tell me.”

  He acknowledged her temper with a wry smile. “Call it a telescope into the past. Or think of it as bait for your husband. If Peter has studied what’s in that envelope I gave you, he will know that what he wants to prove can be proved.”

  “He wants to prove the world is real. It’s all he talks about these days.”

  “Then he must accept that the past is shaped by the future as much as the future is shaped by the past.”

  “That sounds as if you think the future causes the past.” She bowed her head and rubbed her temples.

  “You saw it tonight. Does it disturb you?”

  “Yes,” she said emphatically. “It’s like saying that every bad thing that happens to us, we cause ourselves by what we do later.”

  “Every good thing too, by that reasoning.”

  “Isn’t the past hard enough to live down without worrying that we’re making it happen all over again?”

  “If we’re speaking in metaphors, that would be a good way to describe memory.”

  “Memory isn’t cause,” she said unhappily.

  “Cause and effect are illusions. We do not say, when we travel from Paris to Athens, that Paris causes Athens. These places exist in a fixed spatial relation; only the order of our experiences differs. Time is a dimension like the dimensions of space. Just because we experience time as a one-way street doesn’t mean it is a one-way street.”

  “And if someone puts a bomb on the plane, would you call that cause and effect?”

  “Some events are inextricably entangled.”

  “What you showed me tonight was patterns on a computer screen. Do they mean we can go back and change the past?”

  “Oshi.” Minakis thrust out his chin. “Even if we could go back—not in person, of course—it wouldn’t change anything. When you go from Athens to Paris, Paris is Paris.”

  “Assuming your plane gets there.” Anne-Marie pushed herself away from the wall, suddenly restless.

  The level space at the top of the peak was hardly wider than the chapel itself. She circled the building, surrounded by a sweep of stone and sky and starlit sea, and when she rounded the last corner, Minakis was on his feet, waiting for her.

  “I didn’t tell Peter where to find you,” she said defiantly. “I didn’t want him here.”

  “Perhaps he will find me anyway.”

  “Do you know what scares me? What if he has to choose between me and that machine inside, and he chooses the machine?”

  “What kind of choice would you face?”

  “No choice; I made it before I married him. My son.”

  “You can have them both,” Minakis said.

  “What do you mean?” she demanded.

  “I brought you here on purpose. I think you know that.”

  “Yes.”

  “I know what you want.”

  “Yes,” she said. “What do I have to do to get it?”

  Cold air swept down the slopes; the wind sifted through the thorny plants that clung to the crevices among the rocks, a sound like falling water, like the breeze in a pine forest.

  “We’d better start down,” Minakis said. “It’s getting cold.”

  24

  They sat beside an oak fire. He had given her food and wine and the answers to all her questions but one, and now he questioned her.

  “Does Peter know about Alain?”

  She shook her head. “I’ve never told anyone the whole truth.”

  “Are you willing to tell me?”

  “Will it change anything?”

  “I don’t know.” His worry beads wound themselves around the fingers of his left hand, clicking softly.

  For the past two days she had shared Minakis’s losses and hopes so deeply that she had come to feel a great affection for him. Now he had retreated again, playing god. Since there was no more to gain by hiding, she stroked her throat with an open hand, coaxing herself to speak, and made her face into a mask.

  “Papa was always on tour when I was little. We moved a lot because Mama was anxious to stay as close as possible—Milan one year; New York the next for what seemed forever, probably six months while he was doing the States; Vienna—it must have been expensive moving us around, and she made up for it by installing us in the cheapest places. Alain and I shared a bedroom and sometimes a bed.

  “I was as curious as he was, the first times we explored. He was sweet, not insistent, not…pokey. I got bored before he did, but I didn’t think much about it.

  “When I was eleven we learned that Papa was having ‘affairs,’ although we didn’t know what affairs were exactly. We couldn’t ask Mama, it upset her too much—their fights were how we heard the word in the first place, how we knew it had something to do with other women. Which was as much as I wanted to know. But Alain was thirteen, he had sex on the brain.

  “That year was the first time he rolled on top of me, pushed my knees apart, pulled up my nightgown. Nothing happened except he made a sticky mess on my belly, but the next time he tried it I slapped him as hard as I could and started screaming. When Mama came running in, I said I’d had a bad dream.

  “Alain didn’t bother me again, as long as she was around, although when we were alone there were times he pawed at me like a zombie, with no control of himself, apologizing all the time—‘I’m sorry, I’m sorry’—but coming at me anyway.

  “When I was fifteen we moved back to Paris. One night Papa came home late from a performance, drunk—he was drunk a lot that year; I suppose his career was starting to slip—and demanding money for a taxi at the top of his voice, which Mama refused to give him. He hit her. We’d never seen him do that.

  “Alain went crazy. He attacked Papa with his fists. He was sobbing so hard he could hardly see, but he couldn’t stop himself. Papa was shocked—he wouldn’t use his hands to defend himself, all he could do was run, and Alain ran outside after him and threw a handful of coins on the sidewalk and yelled at him not to come back.

  “Next day the police came and told us Papa was dead. Later we found out he’d been with a man’s wife, and the man found them and shot him. Both of them.

  “I don’t remember much about that day except that the apartment was full of people all day long and Mama was in hysterics and somebody, a doctor I suppose, made her take sleeping medicine. When everybody finally left she was snoring like a freight train. Alain came at me and begged me to help him forget what had happened—what he’d done to Papa, he said…” Anne-Marie broke off, the words sticking in her dry throat.

  Minakis said, “You don’t have to…”

  “Yes I do,” she whispered. “And you have to listen.” She reached for her glass and sipped the last of the wine, then held on to the empty glass, squeezing it in her fingers. “He kept at me. He had his hand clamped over my mouth so I couldn’t scream, and I almost passed out. When it was all over he started crying again, all of a sudden desperate for forgiveness. I forgave him. It was the only way I could get him off me.” She relaxed her grip on the empty glass and set it on the table.

  “From then on I slept on the couch. I told Mama why, and even though Alain denied it, and she trie
d to make excuses for him—even though she knew it was true and it horrified her—it wasn’t in her to spend money on a bigger place for us to live.

  “I started classes at the Sorbonne, officially living at home but spending as little time there as I could. I had some girlfriends. I told them lurid tales about imaginary lovers; they told me about contraception. There were boys I wanted to know, but whenever I daydreamed about them needy Alain would loom up in my thoughts, blotting out everyone else. There were nights when I stood on a bridge staring at the Seine, wondering how long it would take to drown.

  “Meanwhile Alain got a job with an antiquary in the rue Dauphine. He had no formal education beyond the lycée, but he’d always haunted museums and galleries—he was a quick study and a social charmer. When he was twenty-one he got his trust fund—Mama had made Papa set up trusts for both of us—and he left Paris to work for the gallery’s Zurich branch.

  “When I came into my own inheritance I didn’t tell Mama where I was going; I told only my bank. I spent the next year working my way across North Africa. I was a party girl, an arrogant, manipulative bitch, someone I wouldn’t want to know”—she smiled crookedly at Minakis—“until I landed in jail in Algiers for smuggling hash. They let me go, but I can’t go back. I’m persona non grata.

  “I wasn’t celibate, but the idea of marriage turned my stomach. In Egypt I had a German boyfriend who was a stringer for Reuters. I picked up photography from him, and pretty soon I was selling snaps of my jet-set acquaintances to magazines like Stern and Paris Match.

  “I got to Crete on a seagoing hotel owned by a Saudi arms dealer and came ashore half blind with migraine from a permanent hangover. By the time my hands stopped shaking and I could focus a camera again, they’d sailed without me.