Verification of the Principle of Equivalence for Massive Bodies

Abstract

Analysis of 1389 measurements, accumulated between 1970 and 1974, of echo delays of laser signals transmitted from Earth and reflected from cube corners on the Moon shows gravitational binding energy to contribute equally to Earth's inertial and passive gravitational masses to within the estimated uncertainty of 1.5%. The corresponding restriction on the Eddington-Robertson parameters is $4\ensuremath{\beta}\ensuremath{-}\ensuremath{\gamma}\ensuremath{-}3=\ensuremath{-}0.001\ifmmode\pm\else\textpm\fi{}0.015$. Combination with other results, as if independent, yields $\ensuremath{\beta}=1.003\ifmmode\pm\else\textpm\fi{}0.005$ and $\ensuremath{\gamma}=1.008\ifmmode\pm\else\textpm\fi{}0.008$, in accord with general relativity.