LC12995
- Since the days of Dirac scientists have been wondering about the possibility that fundamental constants may have varied over the history of the universe. In the past decade this question has been made operational through the comparison of spectral lines observed in objects, known to be old, in comparison with spectral lines observed in the laboratory, i.e. in the present epoch. The mass ratio between a proton and an electron is such an important fundamental constant, which may be tested by looking at hydrogen molecules. Now very detailed observations of the largest set of hydrogen lines so far (over 90) of the brightest know quasar system (J2123-005 at redshift =2.05) with a lookback time of over 10 billion years from the two largest optical telescopes in the world (the Very Large Telescope in Paranal, Chile and the Keck Telescope in Hawaii) show that such observations on "old hydrogen" can be made, and are not overwhelmed by systematic effects. The results from both telescopes perfectly agree with each other and give a slight indication of a change of a fundamental constant. However, the evidence is too small to call proof. More observations will be needed (of other quasar systems), but we know now better about the trustworthyness of such observations.
