Ben Roy Mottelson

Born 9 July 1926, Mottelson was American by birth but spent his career in Denmark, where he pursued the architecture of the atom's core. Working at the boundary of theory and experiment, he developed models showing that nuclei deform under rotation and vibration, behaving less like rigid balls than fluid forms. The Nobel committee recognized him in 1975 for overturning the tidy spherical picture that had guided nuclear physics for decades. He continued working into old age, a physicist who'd redrawn the atomic blueprint. He died 13 May 2022.