Cmichel67 · CC BY-SA 4.0

A Polish-American theoretical chemist who, with Kenichi Fukui, worked out the rules governing how and why chemical reactions follow the pathways they do — the Woodward-Hoffmann rules, which turned much of organic chemistry from trial-and-error into something predictable. The work won him the 1981 Nobel Prize in Chemistry. Beyond the lab, Hoffmann has published poetry and plays, and taught for decades at Cornell as the Frank H. T. Rhodes Professor of Humane Letters.