SIMBAD references

Multidimensional cosmologies allow for variations of fundamental physical constants over the course of cosmological evolution, and different versions of the theories predict different time dependences. In particular, such variations could manifest themselves as changes of the proton-to-electron mass ratio µ = m_p/m_e over the period of ∼10¹⁰ yr since the moment of formation of high-redshift QSO spectra. Here we analyze a new high-resolution spectrum of the z = 2.81080 molecular hydrogen absorption system toward the QSO PKS 0528-250 to derive a new observational constraint to the time-averaged variation rate of the proton-to-electron mass ratio. We find | µ{dot}/µ |<1.5x10^–14 yr^–1, which is much tighter than previously measured limits.