New Experimental Limit on Velocity-Dependent Interactions of Clocks and Distant Matter

An experiment analogous to that of Kennedy-Thorndike and the ammonia-beam experiment of Cedarholm, Bland, Havens, and Townes has been performed using the Mössbauer effect in ${\mathrm{Fe}}^{57}$. A ${\mathrm{Co}}^{57}$ source was on the rim and an iron absorber near the center of a centifuge. The frequency shift between the rotating source and absorber was measured as a function of the angular position relative to the fixed stars. An anomalous velocity-dependent interaction of clocks with a field derived from distant matter would be expected to cause a frequency shift $\frac{\Delta \nu }{\nu }=\frac{2\gamma \mathrm{u}·\mathrm{v}}{c^2}$, where $\gamma$ is a constant, v the relative velocity of source and absorber, and u the velocity of the laboratory relative to a reference frame in which distant matter has an isotropic velocity distribution. The value of the component of $\gamma \mathrm{u}$ lying in the earth's equatorial plane was found to be 220±840 cm/sec.