“Got it,” Aisha said, her hand trembling over her notebook. “Thank you. For everything.”

“Finally,” the girl said. “You’re late. I’ve been waiting since Tuesday.”

“Don’t thank me,” Future-Aisha said, and a sad smile flickered across her face. “Just don’t do quantum computing on a Tuesday. And Aisha? When you get to 2072… don’t open the folder.”

“Question seven, 2066,” Future-Aisha would say. “A seed germinates in a dark cupboard. After ten days, it’s pale and has long, thin leaves. Explain.”

Newton, unimpressed, continued his hoarding.

The screen didn’t show a program. It showed a mirror. Not her reflection, exactly, but a slightly older version of her—maybe eighteen, with sharper cheekbones and tired eyes. The girl in the mirror was wearing a lab coat.

Question 1: Circuits. Easy. Question 4: Germination. She smiled. Question 7: The Carbon Cycle.