Further evidence for cosmological evolution of the fine structure constant

We describe the results of a search for time variability of the fine structure constant a using absorption systems in the spectra of distant quasars. Three large optical data sets and two 21 cm and mm absorption systems provide four independent samples, spanning similar to 23% to 87% of the age of the universe. Each sample yields a smaller a in the past and the optical sample shows a 4 sigma deviation: Delta alpha/alpha = -0.72 +/-0.18 x 10(-5) over the redshift range 0.5 < z < 3.5. We find no systematic effects which can explain our results. The only potentially significant systematic effects push Delta alpha/alpha towards positive values; i.e., our results would become more significant were we to correct for them.