Tests of Lorentz Violation in Atomic and Optical Physics
  Atomic physics can probe the Lorentz and CPT symmetries at the Planck level. Bounds on coefficients for Lorentz violation have been found using atomic clocks, masers, electromagnetic cavities, and Penning traps, among others, and in future it may be possible to place bounds using spectroscopy of antihydrogen atoms. The CPT '04 Meeting on CPT and Lorentz Symmetry was held in August 2004 in Bloomington, Indiana, USA, and covered Lorentz violation in all branches of physics. This report gives an overview of the recent advances in Lorentz-symmetry studies in atomic and optical physics. 
Neil Russell