"Henry?"

"You're a little oblivious, aren't you?"

"I guess so. Henry and Grace?"

"He's crushing, big-time."

"I guess," John said. It was his turn to be sly. "What does Grace know about 'us'?"

"We're dating, didn't I tell you?"

"I couldn't even get ahold of you all week."

"I do go to school," she said. "But the weekends are all yours. Until you screw it up."

"Won't be long."

Casey grinned, and their conversation turned to other things. At the end of the evening, he found her in his arms on his grungy couch, her lips on his.

The lab was huge: a football fieldsized enclosure off the engineering building, with additional bays. The main area housed a dozen experiments: the subcritical nuclear pile that was roped off, a miniature tokamak, a medium energy collider, a supercool lab, a metallurgy lab, and a machine shop. One of the bays was the freshman lab, broken into six benches, all of them labeled and cluttered with junk. One said: "Pinball."

"You already got us a lab area?" John said.

"If I didn't, someone else would have taken it," Grace said. The table was empty, except for a pile of empty boxes some other team had thrown on it. "There have already been inquiries on our s.p.a.ce. Use it or lose it, you know."

John shook his head. "Do you just not have any other ideas for projects?" he asked.

Grace grinned. "We have lots of ideas. They all stink," she said. "So, what do you think?"

John looked around the labs. There was a Geiger counter on one table. An X-ray machine was roped off across the bay. Light microscopes sat atop workbenches. A scanning electron microscope was hidden somewhere. He realized that his poking at the device with a jeweler's tool kit was a waste of time. Here were tools that he could use to probe the inside of the device, without opening it up.

And he could have access to it all.

"Fine," John said. "We'll do it."

He sat at the table in his apartment and stared at the blank page of the notebook. The device was on the table. It grinned at him, its teeth an LED green. The jeweler's kit lay open but unused. It was his habit to sit every night and think about the device, what it did, and what he had done with it. All of that was written in the notebook. But tonight his mind was elsewhere.

He found himself drawing freehand, not the device but rather a pinball machine. He'd played it so much in high school. There'd been one at the Lawson's where he bought comic books. He'd ride into town on his bike, spend his meager allowance on books and pinball, milking high-score extra games from a single quarter. He'd played a lot of games, and he remembered once when the machine was broken the repairman had had the front open like the hood of a car. Inside had been a hundred lights, a mile of wire, and a lot of dust. Mesmerizing, but that didn't mean he knew how a pinball machine actually worked. But when it came right down to it, it was freshman physics.

It was a ball on a slanted plain. Gravity was the enemy. When he thought of it that way, it became an experiment in cla.s.sical physics. He had been reminded of pinball during physics lab, because the ball followed Newtonian laws of motion. The ball was easy: It was ball-bearing. The plane was easy: It was a slab of wood with obstacles. Add lights, flippers, b.u.mpers, and scoring and you're there.

John started making a parts list under the drawing.

He jumped when the doorbell rang.

"John, it's me!"

"s.h.i.t!" It was Casey. He stared at the device sitting on the table. She couldn't see it. He couldn't explain it if she did. He grabbed it and ran to the bedroom. He shoved it into the lockbox and turned the key.

"John!"

"Coming!" He threw the lockbox onto the floor of the closet.

As he ran past the kitchen table, he realized the tools were still out. He folded them up in their leather satchel.

"John, I see you through the peephole! Open up!"

"I'm... I'm cleaning up."

"Don't bother. We're going out."

John tossed the tool kit on top of the refrigerator, then unlocked the door.

Casey was dressed in a miniskirt and leather jacket with dangling leather bangles. John couldn't say he liked the local styles, but Casey looked good enough in anything.

"You're not dressed," she said flatly.

"I-Uh, I was... working?"

"Yeah, I figured." She waved her hands. "Go, go on; get dressed. We have to be there in an hour."

"Right."

John jumped in the shower, sprinkling more than showering. When he came out of the bathroom, Casey was paging through his notebook. He'd left it on the table.

"What's this?" she said.

"Just a notebook." He reached out to take it from her.

"These are pretty elaborate drawings," she said. "Very crisp, very clear."

"It's nothing!" John cried. He s.n.a.t.c.hed the notebook from her hands, slapping it shut. He threw it through the door of his bedroom, where it sailed with a ripple of pages.

Casey looked at him calmly. "Fine, it's nothing. You ready?" There was a tone to her words that chilled him, that ebbed his anger and made him feel cautious.

All night Casey was aloof, hardly dancing at all. Instead of going back to his apartment, she asked to be dropped off at the dorm. John watched her enter Benchley Hall and realized he'd made a superb mistake in letting her see the notebook. No one could know about the device.

"Here's the parts list I came up with," John said. It'd been relatively easy to come up with. Flippers were a chunk of wood attached to a solenoid. b.u.mpers were plastic wrapped in rubber with a solenoid inside. The coin box could be bought from whoever made them for vending machines. The b.a.l.l.s were steel ball bearings. The launcher was a spring and rod. He'd need a sheet of gla.s.s, power, a stand, wood. The first design would be simple.

Grace looked at the list, then reached for his drawing.

"Your perspective's off," she said.

"I barely got a B on my first drafting a.s.signment," John said.

"I'll get someone to redraw these," she said. Henry took the diagram from Grace and grunted.

"Machine shop," he said.

"Yeah," Grace said. "We'll need some time on the lathe and we'll need the soldering tools."

They were standing at their table in the lab. All around them was the sound of voices and tools clinking. The thrum of some equipment somewhere vibrated the floor. Casey had wanted to join them but had begged off at the last minute. "You guys can handle the tech. I'll handle the other stuff." What other stuff was there? John wondered. And how had she gotten on the team?

"Why is it called pinball again?" Grace asked. "There's no pins on this list. I see a ball, but no pins."

"Steelball," Henry chimed in. John realized he was suggesting a new name.

"I don't know why they call it pinball," John said. "They just do."

"I'm sure it'll become apparent as we move forward," Grace said. "Where's Casey? Everything all right between you two?"

"What?" John said. "She had something to do, okay? Why do you think there's something wrong?"

Grace looked at him strangely, and John realized he'd yelled at her.

"Sorry. Didn't mean to raise my voice."

"Yeah, no problem."

"Hold on," Henry said. He disappeared into a storeroom. John heard things banging around. Henry emerged with a huge piece of fiberboard. He hauled it over to their lab table and John helped him heft it onto the table.

"Can we use this?" John asked. It was about the right size for the play board.

"Everything in there is fair game," Grace said.

John took out a measuring tape. He marked off a rectangle a meter wide and two meters long. He held his hands along the width and flipped imaginary flippers. Maybe a little skinnier, he thought.

"We'll need a lacquer to smooth the surface, and paint," he said.

Henry had found a block of wood in the skunk works room. He propped the first plank up, giving it a five-degree angle. Then he grinned at Grace and John. He pulled a steel ball bearing, about two centimeters across, from his pocket and held it at the top of the plank.

"Ready?" he asked, then let the ball go.

It rolled down the plank, gained speed, and flew off the end. John caught it in his palm.

"Cool," Henry said.

"I love potential energy," Grace said.

John found himself grinning too. It had been no sort of test at all, no prototype of any value, but the physics was true. It could work.

They missed dinner, and by the time they looked up from their drawings and list of parts, the lab was empty. They agreed to meet daily after cla.s.s, then parted company.

John went back to his apartment, retrieved the device, and returned to the lab. Since Casey was busy that night, he figured he'd do something he'd been meaning to do for a long time.

The lab was still empty when he unlocked the door. Now that he had a key, he could stop by any time he wanted. He walked the entire length of the room to be certain, but it was truly empty.

John sat at the row of light microscopes and turned the first one on.

He removed the device from his bag and placed it under the microscope.

The light microscope only gave an increase in resolution of a few times, but it was better than the magnifying gla.s.s he had at the apartment.

He peered at the gray surface of the device, looking for anything that was out of the ordinary, looking for any clue.

Centimeter by centimeter, he examined the surface.

One hand on the scope, one hand holding a pencil, he drew close-ups of the controls. But even with the microscope, he saw nothing that he hadn't seen before.

Then he turned it on its side. The line was a hair-width wide, and ran the circ.u.mference of the device's disk. Was this how the device came together? he wondered.

He spun the device slowly under the scope, following the line. It remained the same hair-width wide, but then he saw the scratches.

They were tiny, but a dozen of them radiated from the crack, as if a tiny tool had been used to dig there. Why?

The door opened and John jumped.

"h.e.l.lo there, working late, I see."

John reached for the device to hide it but then felt that would look too suspicious. He turned, smiling. Professor Wilson stood by the door.

"Uh, yeah," John said. He'd had almost no contact with his advisor and didn't want any now.

"You're the other Wilson, aren't you?"

"Yeah, I am," John said, regretting for the umpteenth time that Wilson was the name he'd latched onto when he'd met his faux father in this universe.

"What's that you're looking at?" Professor Wilson asked.

"Nothing, nothing important."

Wilson peered around John at the device sitting on the microscope's stage. He stared at it, then nodded slowly. John refused to explain or say more or remove it from sight.

"How are cla.s.ses? Too hard? You were admitted with just a GED, correct? You and I had some question on how you'd handle the core physics cla.s.ses."

John gritted his teeth. He'd had no question of how he'd do, but Wilson had.