General Relativity and Gravitation

, Volume 10, Issue 3, pp 181–204 | Cite as

A test of the equivalence principle using a space-borne clock

  • R. F. C. Vessot
  • M. W. Levine
Research Articles


An experimental verification of Einstein's equivalence principle has been made using an atomic hydrogen maser in a space probe attaining an altitude of 10,000 km above the earth's surface. At the present stage of the data reduction, confirmation is at the 2×10−4 level of accuracy. The experiment and the resulting data are described including a comment on the limits to the anisotropy of the velocity of light. We believe that this is the first direct, high-accuracy test of the symmetry of the propagation of light and a beginning in the use of high-accuracy clocks in space to measure relativistic phenomena.


Hydrogen Anisotropy Atomic Hydrogen Differential Geometry Space Probe 
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Copyright information

© Plenum Publishing Corporation 1979

Authors and Affiliations

  • R. F. C. Vessot
    • 1
    • 2
  • M. W. Levine
    • 1
    • 2
  1. 1.Center for AstrophysicsHarvard College ObservatoryUSA
  2. 2.Smithsonian Astrophysical ObservatoryCambridge

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