Lost and Wanted

by Nell Freudenberger

  “My parents say the same thing.”

  Addie nodded. “And so there are good days, and very bad ones. People used to ask me, when I had the gallery, whether I had ever wanted to be an artist—and I always said, Oh, no—that wasn’t my inclination at all. I confess that this is the only time I’ve ever wished to have that talent. So there would be somewhere to put all of this.” She gestured to her chest, where a black cashmere scarf was expertly draped. “If someone had described art to me in those terms then, I would have dismissed them out of hand. Art isn’t therapy, I would have said.”

  I drew in a breath. “I’ve sometimes found science a little therapeutic,” I suggested.

  “I can imagine,” Addie said. “A whole other world.”

  “If you’d like to join us for the tour—”

  Addie glanced at her watch. “Will you promise me a rain check? I’m meeting a friend nearby. And then I thought I could come back for Simmi whenever you’re ready.”

  We arranged for me to call her when we were finished. After she left, I buzzed the keypad on the second set of doors and the department secretary let us in. We walked through the recently renovated common area, with peripheral glassed-in offices. I pointed out Rainer Weiss’s office to the kids.

  “Rai built the first version of those machines in the pictures. That was in the seventies, when I was a baby.” Jack was distracted by Simmi’s presence, and both children only nodded. I might as well have said that Rai had built his prototype during the Crusades. “Hardly anyone thought that detecting gravitational waves was possible back then. But now everyone thinks Rai’s going to win the Nobel Prize.”

  “Oh,” Jack said. Then he turned to Simmi. “What were you for Halloween this year?”

  Rai wasn’t in, but we found Neel on his computer around the corner. He had just changed offices, and this was the first time I’d seen it. The new space was almost empty, dusty sunlight pouring in from two rectangular windows just below the ceiling. There was a whiteboard on the wall behind his desk, covered with notes in red, a couch with metal arms, and a coat tree in one corner. Neel and I had been working steadily on the rotor project since the spring, making progress, but most of our communication was over email or on the phone. When we met, it was usually in my office. There was something slightly different about our interactions since his marriage; I had expected it, but the change seemed to take Neel by surprise. Sometimes I would find him looking at me in a strange way, as if I were the one who’d done something that had caught him off guard.

  This new office was nothing like Arty’s—like most of MIT, it felt efficient and intentionally unadorned compared to Harvard—but I could remember coming upon him just this way in the past, when he was concentrating, one hand resting on the keyboard, the other twisting a piece of his hair between thumb and forefinger. He tended to rock very slightly back and forth in his chair, as if to some rhythm in his own thought.

  He heard us at the door and looked up.

  “Jack!” he said. “Hey!” They hadn’t seen each other since the spring, when Jack had spent an afternoon in my office on a day off from school.

  “And this is Simmi,” I told him.

  Neel got up and high-fived each kid. Then he indicated his screen. “Want to see something funny?”

  The children stepped closer to see the screen. It was a cartoon of Santa Claus in space, throwing down the sort of warped net we sometimes use to represent gravitational waves. Oops, I almost forgot LIGO, Santa was saying.

  Simmi made a questioning face at Jack, who clearly didn’t understand either.

  “You might have to explain,” I told Neel. “To me, too—because if the rumors are right, Santa’s definitely not going to forget LIGO next year.”

  Neel grinned at me. “Roxy says the prize will only count if I get an invitation to Stockholm myself—and even if LIGO wins, I’m not important enough to go. So you and I are going to have to hit it big with the rotor project.” Then he turned to the kids. “The machines ‘heard’ gravitational waves for the second time around Christmas,” he said, “so the joke is that the new waves were a present from Santa. The reindeer are being knocked around by the waves. That’s silly, since you wouldn’t be able to feel gravitational waves unless you were right up close to the source.”

  Jack smiled uncertainly.

  “But I also think it’s funny because there are a lot of people who thought gravitational waves were about as real as Santa Claus. It’s been a while since you guys were into Santa, right?”

  “Jack hasn’t believed since he was three,” I said. “I had to remind him not to spoil it for the other kids.”

  “Oh yeah, me, too.” Simmi suddenly sounded young, in her eagerness to appear the opposite.

  “You have to wonder about those kids who believe in him,” Neel said, pleasing both children. “But I like the cartoon. What we do here does sometimes feel like magic, at least inside the lab.” He looked from one to the other. “So do you guys want to go in?”

  15.

  We left the offices in NW-22 through a side door, descending a few iron steps where there had once been a loading dock. We crossed the parking lot and went up another set to the adjacent building that contained the lab.

  “Are there real lasers in here?” Simmi asked.

  Neel nodded. “Very cool infrared lasers, actually.”

  “Can we see them?” Jack asked.

  I started to explain why that wouldn’t be a good idea, but Neel looked down at Jack and smiled: “Let’s pull out all the stops,” he said. “Why not?”

  “Awesome,” Jack said.

  “You’re just going to have to pay attention,” Neel said. “Really follow instructions, because the lasers could be dangerous.”

  Both kids nodded solemnly. “What could they do?” Simmi asked.

  “They could burn your skin, or your eyes,” Neel said. “Not where we’ll be standing, though. We’ll be looking at them through a little round window, like the porthole of a ship. But we’ll wear glasses, just to be absolutely safe.”

  We followed Neel down to the basement level, where he used his ID to open another locked door into a hallway. Posters describing different elements of LIGO’s operation hung under fluorescent lights, giving the stuffy, underground passageway the feeling of a high school corridor. Neel guided us past the restrooms, which the children assured me they didn’t need, and around a corner to the small control room that led to the lab. The control room was narrow inside, only about six by ten feet, with a row of computers on three walls. To the right of where we’d come in was a second door—heavy, steel, and plastered with cautionary signage—which led directly into the lab. I saw Jack noticing the black-and-yellow “Danger” sign, as Neel passed us the safety glasses, along with paper shoe protectors and elasticized white surgical caps.

  “Are these to keep us safe from the lasers, too?” Simmi asked, tucking her hair into the cap. She wasn’t wearing earrings, but I saw that her piercings had closed neatly, without any visible irritation.

  “Those are actually to protect the machines, not you,” Neel said. “Same with the booties over our shoes. You’ll see that almost everything inside the lab is covered with foil or plastic; even just a few specks of dust inside the interferometer, and the experiment stops working the way it should.”

  He indicated the red light above the entrance. “When that light is red, it means the lasers in the lab are on.”

  Jack and Simmi were suitably impressed, and even more so when we actually entered the lab. There was the steady hum of the equipment; our feet in their paper shoes made no sound on the concrete floor. I saw the children taking in the colored wiring, the pneumatic tubing, the surrounding installations of shiny auxiliary equipment; this was what science was supposed to look like. We turned a corner, and there was the massive steel beam pipe right at eye level, almost four feet wide.
The two silo-shaped vacuum chambers at either end of the pipe rose higher, almost to the skylit, triple-height ceiling.

  “Whoa,” Jack said, looking up.

  I had been wondering if Neel was going to be able to boil his description of gravitational wave detection down to the kids’ level, but he was remarkably patient. He explained that the beam pipe represented just a small segment of the enormous machines in the photos they’d seen outside. Neel pointed to the vacuum chambers at either end of the pipe.

  “Each one of those chambers has mirrors in it. The laser light bounces back and forth between the mirrors, making a pattern we can study. We know that our machines have heard a gravitational wave when the pattern changes. That’s because space actually curves when the gravitational wave rolls through it. Of course you know you have to walk farther on a curved path than you do if you walk in a straight line. The same thing happens to the laser, if a gravitational wave curves the space it’s traveling through—only with a gravitational wave, that extra distance is tinier than anything you can imagine.”

  “Like an atom,” Jack said, glancing slyly at me.

  “Like if you divided the tiniest piece of an atom into ten thousand parts,” Neel said. “That’s what we have to measure. And that’s why we have to make the beam so perfectly empty and quiet—because we don’t want anything except a gravitational wave to get in the laser’s way as it goes back and forth between the mirrors. We pump everything out of the beam, to make what scientists call a vacuum.”

  “Vacuums are usually loud,” Jack pointed out.

  “Loud when they’re taking air in,” Neel said. “Sucking things up. Quiet when they’re closed off, because sound can’t travel without air—does that make sense to you guys?”

  “Do we have to be quiet?” Simmi asked.

  “Well, I wouldn’t yell,” Neel said. “But we’ve already figured out how to block out the noise people make. Now we’re working on much smaller noises. Like the noise the light makes when it hits the mirror. That’s why we have to squeeze it before it goes into the machine.”

  “Squeeze light?” Jack said.

  “I know,” Neel said. “It’s weird. But have you heard of photons? Those are the smallest pieces of light. They travel together, in little groups.”

  “Like the girls at my school,” Simmi said knowingly.

  Neel smiled. “Exactly. When each clique of photons hits the mirror, they make a noise—let’s call it a squeal. We’re trying to get rid of the squeal, without getting rid of the girls.”

  Apart from the four of us, there were only two other people in the lab, a postdoc working at a computer, and a technician sweeping the floor underneath one of the vacuum chambers, behind plastic sheeting. The children seemed especially interested in the technician, who was completely swaddled in a loose-fitting white suit, made of the same paper as our booties. He wore a cap like ours, as well as a surgical mask and yellow plastic gloves; even his eyes were barely visible behind the amber lenses of his glasses.

  Neel called to the postdoc, and he left his station across the lab to join us.

  “Meet Vlad,” Neel said, “our Optical Parametric Oscillator specialist. That’s the actual light-squeezing tool.”

  When Neel told him who I was, Vlad became excited; he was interested in the electroweak paper my group had published in the summer, and had several questions. While we were talking, the technician shouldered past us, carrying a blue plastic cleaning bucket filled with water bottles wrapped in aluminum foil. There was plenty of room, even with the group of us, but he came unnecessarily close, as if we were in his way.

  “Hey, Eddie. Have you seen a step stool?” Neel asked.

  Eddie pulled down his paper mask in annoyance and pointed toward the lab’s south wall, but didn’t offer to get the stool, possibly because he didn’t like taking orders from Neel. “Getting some of this shit out of here,” he said, indicating the cleaning bucket. The children gave each other a look: profanity delighted them.

  “Charming guy,” I said to Neel.

  “Eddie’s all right,” Neel said. “Just a little misanthropic.”

  “I’ll grab it,” Vlad said. He disappeared behind one of the steel towers, and came back with a step stool, also covered in foil. The children would need it to look through the viewport, which was at adult height.

  “We’re going to see the lasers, right?” Simmi asked.

  “And the mirrors,” Neel promised. He was carrying an undistinguished-looking gray plastic case; now he put it down on a steel table next to the vacuum chamber, and removed a black metal viewing tube, mounted on a pistol-like grip.

  “This is called a monocular. It’s like half a set of binoculars,” Neel said, “only for infrared light.”

  “Like binoculars for a Cyclops,” Jack said.

  “Cyclopular,” Simmi replied, without thinking. That playing with words, I thought—that was Charlie, too.

  Neel led us over to one of the metal silos that housed the vacuum chamber. He lifted the plastic, and we walked around its cylindrical base to the viewport, a round window at the height of the beam pipe. Vlad positioned the stool so that the children would be able to see inside, and removed a Plexiglas cap that protected the round glass window.

  “Take a look,” Neel said. “What you’re going to see first are the most expensive mirrors in the world. Then I’ll give you the monocular, and you can check out the laser.”

  Vlad excused himself to go back to work, and Simmi stepped up to look into the window.

  “Oh,” she gasped. “It’s so pretty!”

  She looked for longer than I would have expected, and Jack waited patiently until she’d had her fill. Then he took his turn.

  “You’ve got to see this, Mom,” he told me seriously, when he’d finished.

  I was very familiar with the LIGO setup from all the lectures I’d attended, the schematic drawings in innumerable papers, but I’d never actually seen the interior of an interferometer in person. I found myself looking into the steel cavity of the vacuum chamber, a space maybe ten feet in diameter. In the center, between me and the dark opening to the beam pipe, were two mirrors: the size of a stack of dinner plates, but clear and fantastically strong. Each one was like a glass lozenge, or a gem. They hung suspended inside steel scaffolding, connected by pure glass threads. The penultimate mirror had a diamond clarity, but the optical coating on the lowest-hanging mirror—what made it so extraordinarily reflective—also lent the glass an opalescent, dark pink cast.

  “The laser is bouncing off the mirror right now?” Jack confirmed.

  Neel nodded. “It is. But to see an infrared beam, you need your Cyclops eye. Get on the stool first, and then I’ll hand it to you.”

  He handed Simmi the monocular, and the children took turns looking at the laser. They asked smart questions: Why did the air look green around the red beam? If the laser was so powerful, why didn’t it burn the mirror?

  When they’d both had a turn, Simmi wanted to look again. Jack obligingly returned the monocular, but as Simmi stepped up and put her eye to the instrument, we heard the sharp crack of the metal tube hitting the window.

  Before I could react, Neel grabbed Simmi, swinging her violently to the floor. “Careful!” he barked, pushing the children out of the way; we stumbled backward, through the plastic, and I dragged the kids underneath the steel table, crouching with them there and instinctively trying to protect their faces. I braced myself for an explosion: breaking glass and the roar of the machine. But nothing happened. They cowered against me, pressed against my sides, but after a few moments they looked up, trying to determine from my expression whether they were safe.

  “Neel?” Vlad called out from across the lab. “Everything okay?”

  Neel was checking the glass viewport, shaking his head. When he was satisfied, he replaced the protective cover. “All
good,” he called back to Vlad. Simmi and Jack and I crawled out, and climbed unsteadily to our feet.

  “What happened?” Jack said.

  “Nothing,” Neel said. “No problem.” But he looked over their heads at me, and mimed wiping sweat from his brow.

  “Did I break it?” Simmi asked in a small voice.

  Neel put his hand on her shoulder. “No,” he said. “No—but I was actually more worried about you than the machine. If the viewport were to crack, the glass would implode. The pipe would start sucking in everything around it, like a giant vacuum cleaner. It would suck you right in with it.”

  “And then the lasers would burn you up,” Jack concluded.

  “Well, no,” Neel said. “The laser would shut off automatically. But your head wouldn’t be in very good shape with all that broken glass.”

  I still had my arm around Simmi, and I hugged her to me. “You okay?”

  “Yeah,” she said. “I’m fine.” But her voice was shaky.

  “I’m so sorry,” Neel said. “I didn’t mean to scare you.”

  “It was kind of exciting,” Jack said. “Right? Has the porthole ever actually broken?”

  “The viewport,” Neel corrected automatically. “It happened once in Italy, at the VIRGO detector. No one got hurt, but the experiment shut down for a year.”

  Simmi’s eyes darted around the lab, as if anticipating danger from another source. “Is the tour finished?” she asked.

  “If you want it to be,” Neel said. He looked at me guiltily, and I understood: it had been going so well. “There’s more we could see—” he ventured, but the kids’ faces made it clear that they were finished with the lab. Neel changed his tack. “I wanted to talk to Helen about something. We have a computer with a really fast connection that you guys could use in the control room, if you want to play a game or something?”

  Simmi turned to Jack. “Do you like Fruit Smash?”

  “Oh yeah,” he said. “I play it all the time.”