The Sign of the Doppler Shift in Ultracentrifuge Experiments

Measurements of the transverse Doppler effect have provided important confirmatory evidence for the validity of Einstein’s theory of special relativity (SR) as it pertains to time dilation. However, these investigations fall into two distinct categories depending on whether the light source or the detector is accelerated relative to the rest frame of the observer. In their original work employing a moving light source in the laboratory, Ives and Stillwell state explicitly that they observe a wavelength shift to the red, and therefore a slowing down of the initially accelerated clock, in complete agreement with Einstein’s predictions. By contrast, although both Hay et al. and Kündig also report complete agreement with SR on the basis of their ultracentrifuge experiments in which the absorber/detector is under constant high acceleration, their theoretical discussion actually contradicts this assertion. For example, Kündig states that his work demonstrates “that the clock which experiences acceleration is retarded compared to the clock at rest,” thereby giving unequivocal support to the