Around-the-World Atomic Clocks: Predicted Relativistic Time Gains

doi:10.1126/science.177.4044.166

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Science 14 July 1972:
Vol. 177. no. 4044, pp. 166 - 168
DOI: 10.1126/science.177.4044.166

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Around-the-World Atomic Clocks: Predicted Relativistic Time Gains

J. C. Hafele ¹ and Richard E. Keating ²

¹ Department of Physics, Washington University, St. Louis, Missouri 63130
² Time Service Division, U.S. Naval Observatory, Washington, D.C. 20390

During October 1971, four cesium beam atomic clocks were flownon regularly scheduled commercial jet flights around the worldtwice, once eastward and once westward, to test Einstein's theoryof relativity with macroscopic clocks. From the actual flightpaths of each trip, the theory predicts that the flying clocks,compared with reference clocks at the U.S. Naval Observatory,should have lost 40 ± 23 nanoseconds during the eastwardtrip, and should have gained 275 ± 21 nanoseconds duringthe westward trip. The observed time differences are presentedin the report that follows this one.