Relativistic corrections in atoms and space-time variation of the fine structure constant

Comparison of quasar absorption line spectra with laboratory spectra provides the best probe for variability of the fine structure constant, α = e 2/ħc, over cosmological time-scales. We have demonstrated [1] that high sensitivity to the variation of α can be obtained from a comparison of the spectra of heavy and light atoms and have obtained an order of magnitude gain in precision over previous methods [2]. Our new data [3] hint that α was smaller at earlier epochs. Careful searches have so far not revealed any spurious effect that can explain the observations