An experimental researcher who, with Richard E. Keating, tested relativistic clock predictions using four portable atomic clocks flown around the world. Comparing their readings with a reference timescale after eastward and westward journeys gave different accumulated times. The comparison brought time dilation into a transportable laboratory instrument: the prediction depends on both the aircraft’s motion and its altitude through gravitational time dilation.[ref]
Around-the-World Atomic Clocks: Observed Relativistic Time Gains by J. C. Hafele and others. Printed pp. 168–170: four cesium clocks, reference comparisons, flight directions and comparison with predictions
New to topics? Read the docs here!