We study neutron-proton equilibration in dynamically deformed atomic nuclei created in nuclear collisions. The two ends of the elongated nucleus are initially dissimilar in compositions and equilibrate on a sub-zeptosecond timescale following first-order kinetics. The technique of equilibration chronometry used to obtain this result enables new insight into the nuclear equation of state that governs many nuclear and astrophysical phenomena leading to the origin of the chemical elements.
