The Ives and Stillwell Atomic Clock experiment is one of the first to measure the Doppler Effect for waves traveling at very fast velocities. They were able to measure the shift in the “center of gravity” as well as the Doppler displacement. Ives and Stillwell were not proponents of Special Relativity. In fact, they concluded that their experimental findings supported the theoretical predictions of Larmor-Lorentz.  Some have asserted that the SRT equations are the only set of equations that can predict this experiment’s resutls.  Not only is this not true, but the CICS equations seem to do it with better accuracy.


SRT and the CICS model use different equations, with different meanings associated with those equations, to produce the expected shift in the center of gravity. Interestingly, both produce the exact same predictions (given the level of accuracy in the experiment)! Therefore any comparison of the expected results to the actual results will reveal no difference between the two theories.

In predicting the Doppler displacement, the CICS equations appear to produce results that exactly match the expected results. Said differently, the average error between the CICS-based predicted results and the actual experimental results is 0.00 angstrom. SRT, on the other hand, produces results that have an average error of 0.03 angstrom.

What Do The Results Mean?

Proponents of SRT use experiments such as Ives and Stillwell as a way of challenging alternatives theories. Until the introduction of the CICS model, few non-Lorentz based equations were able to successfully predict the results of the experiment.

The CICS model and SRT both predict the same results for the shift experiment. The CICS model appears to offer better quantitative (or mathematical) predictions of the displacementexperiment. However, since both SRT and the CICS model offer statistically equivalent predictions of the Ives and Stillwell atomic clock experiment, the experiment cannot be used to invalidate either theory.

See the Papers section for more detail behind this analysis.

Comments are closed.