[ntp:questions] National time standard differences

David J Taylor david-taylor at blueyonder.delete-this-bit.and-this-part.co.uk.invalid
Fri Feb 12 06:48:45 UTC 2010

"Greg Hennessy" <greg.hennessy@> wrote in message news:It%cn.19853
> From the abstract:
> Around-the-World Atomic Clocks: Observed 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
> Four cesium beam clocks flown around the world on commercial jet
> flights during October 1971, once eastward and once westward, recorded
> directionally dependent time differences which are in good agreement
> with predictions of conventional relativity theory. Relative to the
> atomic time scale of the U.S. Naval Observatory, the flying clocks
> lost 59 ± 10 nanoseconds during the eastward trip and gained 273 ± 7
> nanoseconds during the westward trip, where the errors are the
> corresponding standard deviations. These results provide an
> unambiguous empirical resolution of the famous clock "paradox" with
> macroscopic clocks.

Greg, thanks for that.  It sounds as if the measurements were down to the 
ten-nanosecond level or so.  Those of us at the microsecond level may be 
spared relativistic corrections.

A pity they make you pay to see an article that old.


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