Relativity: The Physics of Time Dilationindex.htmlshapeimage_1_link_0

Proofs of Gravitational Time Dilation

The first proofs for gravitational came when highly accurate atomic clocks were put in airplanes and after being flown around at high altitudes. After the journey the atomic clock on the plane was compared to another on the ground which were synchronised before the plane journey. The clock on the plane was found to be faster than the one on the ground by the amount predicted by gravitational time dilation

More recently scientists have tested the theory on much smaller levels using optical clocks accurate to one second in every 3.7 billion years. By comparing the two clocks and changing their heights by less than a metre they measured a time change consistent with that predicted by gravitational time dilation.

The paper which describes the test of general relativity at height changes of less than a metre is available in the Further Reading & Documentaries section.