Radio‐wave deflection experiments confirm Einstein

Abstract

Einstein yes, Brans–Dicke no, is the apparent verdict of some recent experiments at the National Radio Astronomy Observatory, Green Bank, West Virginia. Edward Fomalont and Richard Sramek measured the deflection of microwave radiation by the Sun's gravitational field and report results sufficiently precise that they are consistent with Einstein's general relativity but not with scalar–tensor formulations such as Brans–Dicke theory. The remaining uncertainty concerns possible systematic errors in these observations, not the formal statistical error, which appears to be sufficiently small. The experimenters used a 35‐km baseline radio interferometer to study three nearly collinear radio sources at two frequencies and found the bending to be 1.015±0.011 times that predicted by general relativity; the Brans–Dicke prediction differs by about seven percent.