Special relativity aces time trial
The scientists made the moving clock by accelerating lithium ions to one-third the speed of light. Then they measured a set of transitions within the lithium as electrons hopped between various energy levels. The frequency of the transitions served as the ‘ticking’ of the clock. Transitions within lithium ions that were not moving served as the stationary clock.
On the one hand, very cool-sounding experiment. On the other, [yawn], Einstein wins again. Cool experiment wins, though. This blurb makes it sound like maybe they were doing spectroscopy and seeing the shift in the resonance, much like in the Pound-Rebka experiment which confirmed gravitational time dilation. I have to go get the paper at work and read it.