Variability of the proton-to-electron mass ratio on cosmological scales
  So far the only seemingly significant indication of a cosmological variation exists for the proton-to-electron mass ratio as stated by Reinhold et al. (2006). The measured indication of variation is based on the combined analysis of H2 absorption systems in the spectra of Q0405-443 and Q0347-383 at z=2.595 and z=3.025, respectively. The high resolution data of the latter is reanalyzed in this work to examine the influence of different fitting procedures and further potential nonconformities. This analysis cannot reproduce the significance achieved by the previous detection. 
Martin Wendt, Dieter Reimers (Hamburger Sternwarte)