Understanding how galaxies evolve is an essential element of learning the fundamental laws of nature using observational cosmology. Galaxy evolution can be studied either by comparing galaxies at different radial distances - because things observed at large distances are being seen when the Universe was much younger than it is today - or by investigating the fossil remnants of prior activity in the present-day kinematics, dynamics, and stellar populations in the galaxies themselves.
Several faculty, with postdocs and students, are making use of the Sloan Digital Sky Survey to investigate the stellar and dark-matter contents of galaxies as a function of type, environment, and lookback time, and to relate the physical properties of the galaxies themselves to the large scale structure in which they formed. The Sloan Digital Sky Survey is by far the largest census of galaxies ever undertaken; it is producing extremely precise descriptions of the relationships among galaxies.
NASA's recently-launched Spitzer Space Infrared Telescope Facility will extend the study of galaxy evolution to the mid and far-infrared, where emission is very sensitive to the physical state of the gas and dust and the radiation fields in which they find themselves. SIRTF is be by far the most sensitive instrument ever made for these spectral regions and the NYU observational cosmology group has approved SIRTF projects.