Pif whistled air out of her mouth. “So what are you going to do? Will the university spring for it?”

“I’m a private student. The foundation that supplies my scholarship will cover it.” He screwed up the wrapper and dropped it in the bin. “Have you anything else?”

“Yes, but… that’s very generous of them. You’ve talked to them already?” She rolled away and dug out another energy bar.

“I didn’t want to hang around. I haven’t exactly got time on my side. It’ll happen next Monday, when the funds are in place.”

Pif was distracted again by her equation. She swung around to face it. “Why did you say it was a wave?”

Petrovitch held out his hand for the energy bar, and she placed it deftly without looking around. “I don’t know. You’ve written it like a zeta function, but it looks more like the bastard child of a Fourier transform.”

“I should be able to solve this.” She glanced at him as he crammed his mouth with food. “Do you want second place on the paper?”

“It can’t hurt: Ekanobi and Petrovitch, twenty twenty-five. What is it?”

“Quantum gravity. Part of it, anyway.”

He stopped chewing and got up slowly, energy bar lying forgotten on the edge of his desk. He walked to the board. “Which part?”

“The last part. I’m going to do all the calculations again, from scratch, and see if I can get to this point again. I’ve got it all written down…” She was breathless, more than that, hyperventilating. “Sam, I just caught a glimpse of creation.”

Her body started to sway, and Petrovitch caught her, and managed to get her head down between her knees.

He crouched next to her, feeling a cold sweat spring up on his own forehead. “You’ve probably made a mistake, somewhere,” he said.

“Probably,” she agreed. “At least one. Promise me you won’t die until I’ve gone through the proof.”

“I’ll try not to.” He pointed at the board. “Yobany stos, if you pull this off…”

She looked out from under her fringe. “It means I’ll never have to put up with you taking my lunch again.”

“Yeah. But in Russia, lunch takes you.” He sat back on his haunches and squinted at the symbols on the board through half-closed eyes. He almost saw it too, the flicker of recognition of something wholly and completely true. “How certain are you of this?”

“Certain? No. But look at it! It’s beautiful.”

“Take a picture of it. For posterity.”

Pif gave him her phone, and he rested his elbows on her desk to reduce the camera shake. It clicked, and she was frozen in time forever, arms folded, grinning like a loon.

“Perfect,” he said.