HAVE THE MASSES OF MOLECULES CHANGED DURING THE LIFETIME OF THE UNIVERSE

Based on an analysis of observations of molecular lines in the spectra of extragalactic objects, we have checked the nucleon masses for poss ible variability (with respect to the electron mass). This kind of var iability is suggested by a number of many-dimensional cosmological mod els. No statistically significant variations in the masses of H-2 and CO molecules and, hence, in the masses of the proton m(p), and neutron m(n) at the epoch corresponding to cosmological redshifts z similar t o 0.2-3, were found. Electronic-vibrational-rotational lines of the H- 2 molecule at z = 2.811 were analyzed in the spectrum of the quasar PK S 0528-250 obtained by Lanzetta et al. (1995), and an upper limit of \ Delta m(p)/m(p)\ < 2 x 10(-4) was found. This constraint improves the previously reported result by one order of magnitude. Measurements of molecular CO radio lines in the spectra of the galaxy IRAS F10214+4724 at z = 2.286 and the quasars PKS 1157+014 at z = 1.944 and PKS 1413+1 35 at z = 0.247 were analyzed. The bounds \Delta M/M\ < 8 x 10(-4), 3 x 10(-4), and 2 x 10-4 on possible changes (Delta M) in the mass of th e CO molecule (M proportional to m(n) + m(p)) were obtained for the ab ove three values of z.