EVIDENCE FOR THE STANDARD MODEL THROUGH QSO ABSORPTION-LINES

Since their first detection in 1969, QSO absorption lines have been ex tensively observed with increasing resolution over a wide range of wav elengths. A wealth of information has been gathered over the last four decades, most of which is consistent with the standard big bang model , in the sense that (i) the data are consistent with the formation of the absorption lines in the intervening galaxies and intergalactic clo uds; (ii) some of the properties of these absorbers have been found to change with redshift, i.e. evolve with time (which supports the stand ard model); (iii) the change in some of these properties is consistent with the expectations of the standard cosmological model. Below, I wi ll first present some of the arguments, based on observations, for the intervening nature of the absorbers and therefore for the cosmologica l nature of their redshifts, and then discuss the changes in the obser ved properties of these lines with redshift and therefore with time.