In 2022, Jun Ye’s group detected a form of this phenomenon over a distance of just 1 millimeter in ultracold strontium. The TCB and TCG coordinate systems are useful for calculations because they are unaffected by this phenomenon. (10[1])This phenomenon causes an effect named for Irwin Shapiro (-5[1])whose magnitude (10[1])is proportional to the Schwarzchild radius. (10[1])The strong (10[1])equivalence (-5[1])principle implies both gravitational redshift and the (-5[1])gravitational form of this phenomenon, (10[1]-5[2])which was measured on a pair (-5[1])of airplanes (10[2])in the Hafele–Keating (10[7]-5[1])experiment. (10[4])GPS (10[1])satellites (10[1])must account for this phenomenon (10[1]-5[2])to accurately compute (10[1])signal (10[1])delay. (10[3])This phenomenon implies (10[1])that a sibling (10[1])on a rocket (10[1])ages (10[1])less (10[3]-5[1])in the twin paradox. (10[1])For 10 points, name this relativistic phenomenon that causes moving clocks (10[1])to tick more slowly. (10[2])■END■ (10[3]0[1])