Five Decades of Lasers, Six Decades of Progress, and a Proposed Space Experiment to Test Einstein's Assumptions

Even though this is the 52$^{\mathrm{nd}}$ year of the Laser, progress in its control and application in precision measurements is still accelerating. The Optical Frequency Comb technology exploded in 1999-2000 from the synthesis of advances in independent fields of Laser Stabilization, UltraFast Lasers, and NonLinear Optical Fibers, enabling a thousand-fold advance in optical frequency measurement, and searches (in the 17th digit) for time-variation of physical ``constants.'' Current advances in ultra-precise locking are making possible stable optical frequencies defined by length and the speed of light, as well as by locking lasers to the resonant frequency of atoms. These two ``clocks'' represent our current prototypes of the clocks postulated by Einstein in 1905 in formulating the theory of Special Relativity, which can now be tested into the 18$^{\mathrm{th}}$ decimal in a proposed Space-based experiment now being planned by our Space-Time Asymmetry Research collaboration (STAR).