He dug his hands into his pockets and kept walking, right past the end of Exhibition Road, still cordoned off with temporary wire barriers while the college and the State Department argued about who was responsible for the damage. Petrovitch lingered again: all that remained of the whiteboard Pif had used to extract the first of her equations was a grainy photograph taken on her camera. His original floating sphere was somewhere underneath it.

Everything was temporary. Nothing lasted forever, not things, not people, not love, not time itself.

He shrugged and walked on. Of course there was no question over who was responsible, just one over who was going to pay for it. In the meantime, he carried on past the Albert Hall to the building just next door—an arts college—which he’d co-opted until they could find some artists.

Glass-fronted edifices had fared badly, and this one had been no exception. The front was swathed in heavy plastic that rippled in the wind and did nothing to insulate the inside from the biting cold. But there was electricity, and light, and network access. He’d decided that it was good enough, and set up shop in the basement.

He peeled his way through the doorframe and let the translucent sheet fall back behind him. The sounds of outside became muffled and changed. It was more like a ship at sea now, crackling and groaning with every gust and gyre.

“Hey,” he said.

Out of sight, Lucy answered into her mouthpiece. “I was waiting for you.”

Petrovitch headed for the stairwell. “Are you done?”

He could hear her breathing: she would insist on balancing the microphone just too high so that it was between her nose and her upper lip. “I don’t know. I mean, I followed the instructions, and it looks like it could work. There were some bits left over.”

“There always are.” He trotted down the stairs and through the fire doors.

“It’s not going to blow up, is it?”

“No.”

“Sure?”

“Yeah. Well, the flywheel might. As long as you don’t stand directly in the way, it’ll be fine.” He barged through another door. The room had originally been for the curation and restoration of old paintings, big enough for what he wanted, but the machine in front of him was now too tall, too wide, to ever make it outside. He looked back at the exit. “Can’t think of everything.”

Lucy peeled her headset off and threw it casually on the side of a sink. “For what it’s worth,” and she made a little show of revealing her creation, as if she were a magician’s assistant.

Which, in a way, she was.

She looked so painfully young, so painfully alone. Petrovitch was a poor substitute for a parent: he had no idea how to make it better. Keeping her occupied like this was the best he could do, but it didn’t stop her from waking in the night, calling out for her lost mother and father, and sobbing when she realized that they were never coming back.

“Are you going to start it up, then?”

She went back to her printed notes. “Okay. Turn it on at the wall—done that. Take the manual brakes off the flywheel and the oscillator.” As she spun the two wheels that released the clamps, she asked, “Did you get a call today? From a Catholic priest?”

“Yeah. No; he came to talk to me in person. Haven’t seen any old guys in red robes wandering around yet, but it’s only a matter of time.”

“What’s it all about? He asked me about Michael, whether I’d be willing to talk to some committee or other. I’d said he’d need to check with you first.”

“He had checked with me first. I told him I’d rip his arms off and beat him with the wet ends if he bothered you.”

“I guess it’ll suck to be him, then.” She looked down at the sheet of paper in her hand, and flicked two switches.

“Tell me if he tries to contact you again. Or anyone else on the same subject.” He wondered how far to take it. “I’m not going to forbid you from talking about Michael—not really my style—but, you know. I’d prefer it if you didn’t. Not to them.”

“I won’t.” She tugged at her ponytail and flashed him a smile. “Don’t worry.”

“The judge said it’s my job to worry about you.”

Her smile slipped, and she turned her back on him.

“Sorry,” he said.

“Stop apologizing. Just, just press a button, or something.”

Petrovitch sighed and reached past her to thumb the big red button on the front of the control panel. The machine’s central column sank down smoothly, then with only the top part of it showing, it rose again to its full height. It paused for a moment, then started to sink again, repeating the cycle.

Lucy looked up. “That bit works.”

“Engage the magnetic coupling.”

“You love this, don’t you?”

“You’ll learn to love it too.” Petrovitch watched as she closed the circuit-breaker on the electromagnets. There were actual honest-to-god sparks, fat blue ones that leaped out at the copper contacts.

She gave a little squeak, but there was no harm done.

A needle started to pulse across a meter, creeping ever closer to the end-stop. The machine began to sing with a low bass note.

Petrovitch eased Lucy aside and inspected all the dials and readings. At some point he was going to have to modify the test rig so that it gave a digital read-out that he could then arrange in neat graphs and publish in a reputable peer-reviewed journal.

For now, he contented himself with making a recording of everything he saw, storing it away on the hard-drive he kept in his pocket.

The flywheel was starting to push the limits which he’d set and, with no load, there was nothing to stop it eventually spinning itself to destruction. The pitch it was calling at was beyond a middle-C: time to let it slow down. He heaved the switching gear back and thumbed the red switch.

The central column stopped its steady rise and fall, and the flywheel’s note slowly ran down through the octave.

“So what did we just do?”

Petrovitch lined up the footage he’d shot, editing it down and splicing it to a convenient thirty-second clip that a news channels could stream without effort. “Solved the world’s energy needs for the foreseeable future.”

“How?”

“By using a second-quantum repulsor to lift a weight, which then falls and does work. But the energy we use to power the repulsors to raise the load is less than we generate when it goes down. It’s a perpetual motion machine.” The video clip and the accompanying notes were ready to go. “If you’ve got shares in energy companies, tell me now.”

“Hang on.” Lucy walked around the base of the machine. “We put electricity in. We get electricity out. More comes out than we put in, so we can use that electricity to run the machine and still have some left over. Right?”

“And it’ll never stop. Once you’ve built one, you have free power—until it breaks down, of course. Even I can’t prevent that.”

“How much free power?”

“Out of this thing? Barely enough for a two-bar electric fire. But they’ll get bigger, better. No one will ever build a power station again that doesn’t use these.”

“You’re serious.”

“Yeah. I mean, it’s not really free energy: it has to come from somewhere, because otherwise that’s just wrong. But we don’t have to do anything to get it. We just press a button and there it is.” There was nothing stopping him. “Sure about those shares?”

“They’re going to get hosed, aren’t they?”

“Yeah. That’s progress for you.” And he sent the footage out into the ether. “It’s way past lunch. You eaten yet?”

“No.” She went back through the checklist, turning everything off, before finally unplugging the device from the wall. “I didn’t feel hungry.”

“Neither did I, but I suppose we ought. I’ll buy.”

“You’re going to have to. Your idea of a regular allowance is once every six months.” She looked at him. “Anyway, since when have you had to pay for anything?”

“Yeah. Okay, so let’s go out and see what we can scrounge.”