In the pantheon of modern physics, few figures can match the quiet authority of Gerard ’t Hooft. The theoretical physicist, now a professor emeritus at Utrecht University in the Netherlands, has spent much of the past five decades reshaping our understanding of the fundamental forces that knit together reality. But ’t Hooft’s unassuming, soft-spoken manner belies his towering scientific stature, which is better revealed by the mathematical rigor and deep physical insights that define his work—an...