Verification of Einstein’s Special Theory of Relativity
using Transverse Doppler Effect
A Critical Review of Ives-Stilwell Experiment of 1938
Chai Haoqiang, Du Long, Hoang Phuc Hung and Wang Yibin
UNL2201, University Scholars Programme, National University of Singapore, Singapore
Doppler Effect is a very well-known physical phenomenon. Discovered by Austrian physicist
Christian Doppler in 1842, it describes the change of frequency of a wave for an observer
moving relative to the source of the wave. Doppler Effect had been confirmed by numerous
experiments under Classical physics, but was once again put under scrutiny of the Special
Theory of Relativity (SR) when Einstein published his seminal paper On the Electrodynamics of
Moving Bodies in 1905. In this paper, Einstein predicted the existence of the “Transverse
Doppler Effect” (TDE), which would emerge under Lorentz Transformation, of the classical
formula for Doppler Effect (Einstein 1905). In 1938, Herbert E. Ives and G. R. Stilwell conducted a
groundbreaking experiment to verify this prediction, and the positive results obtained were
considered as the first direct and quantitative confirmation for the time dilation factor of the SR.
This paper presents a critical commentary on the Ives-Stilwell experiment. The original
experiment is reviewed and analysed in three main areas, namely the theory, the experimental
setup and the empirical results. Several possible sources of error are discussed, including optical
dissymmetry and possible Doppler shift in the central reference line. This is followed by a review
of subsequent studies on this experiment, including experiments adopting the principle of this
experiment and also experiments using different principles.
Although Ives-Stilwell Experiment was aimed to prove the validity of the Lorentz
transformation, it indirectly provided strong confirmation for the time-dilation factor of SR. This
experiment was certainly not perfect. There are several sources of errors, and the level of
accuracy of the experimental results is indeed rather low compared to the modern standard.
However, Ives and Stilwell experiment inspired a series of experiments using the same principle
but with much higher accuracy. These experiments all successfully demonstrated the excellent
predictability of the SR.
It was also noted that the current experiments mainly focus on the high frequency region
of the electromagnetic wave spectrum, and TDE in the low frequency waves such as microwaves
are seldom studied. Also, there are many other experimental setups different from the Ives-
Stilwell type experiments but can be used to verify the same TDE. However, they also lack
sufficient investigation. More experiments done in these areas will definitely contribute to a
more thorough verification of SR.
Ives, H E, and G R Stilwell. "An Experimental Study of the Rate of a Moving Atomic Clock."
Journal of the Optical Society of America, 1938: 215-226.
—. "An experimental study of the rate of a moving atomic clock. II." Journal of the Optical
Society of America, 1941: 369-374.