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 α using absorption systems in the spectra of distant quasars. Three large optical data sets and two 21cm and mm absorption systems provide four independent samples, spanning ∼23% to 87% of the age of the universe. Each sample yields a smaller α in the past and the optical sample shows a 4σ deviation: Δα/α = -0.72±0.18×10^-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 Δα/α towards positive values; i.e., our results would become more significant were we to correct for them.