In 2021, Ye et al. verified this phenomenon by creating an optical lattice of 100,000 strontium atoms and measuring how they maintained coherence for 37 seconds. A phenomenon caused by this effect was first experimentally confirmed by firing radio pulses at Venus and is named for Irwin Shapiro. A pair of airplanes were used to observe two types of this phenomenon in the (*) Hafele-Keating experiment. Rossi and Hall’s verification of this phenomenon found a much larger concentration (-5[1])of muons in the lower atmosphere than expected. A sibling traveling on a rocket near lightspeed will age slower than their earthbound counterpart due to this phenomenon in the (10[1])twin paradox. For 10 points, name this relativistic phenomenon where a clock traveling at a high speed runs slower. ■END■