• elementary particles;
  • quasars: absorption lines;
  • quasars: individual: Q0347–3819;
  • cosmology: observations

Exotic cosmologies predict the variability of the fundamental physical constants over the cosmic time. Using the Very Large Telescope/Ultraviolet-Visual Echelle Spectrograph (VLT/UVES) high-resolution spectra of the quasar Q0347–3819 and unblended electronic-vibrational-rotational lines of the H2 molecule identified at zabs=3.025 we test possible changes in the proton-to-electron mass ratio μ0=mp/me over the period of ∼11 Gyr. We obtained a new constraint on the time-averaged variation rate of μ0 of |μ˙/μ0|<5×10-15 yr-1 (1σ confidence level). The estimated 1σ uncertainty interval of the μ/μ0| ratio of about 0.004 per cent implies that since the time when the H2 spectrum was formed at zabs=3.025, μ0 has not changed by more than a few thousandths of a per cent.