Lost and Wanted(114)

“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.