| Citation | P.J.E. Peebles' wide-ranging contributions to physical cosmology have established him as the leading exponent of this subject in his generation. In the early 1960s he began investigate galaxy formation and helium synthesis on the hypothesis that the Universe originated as a hot dense 'primordial fireball'. Had it not been for this prior theoretical work, the cosmological significance of Penzias and Wilson's serendipitous detection of 'excess antenna temperature at 4080 MHz' would have been less readily appreciated. He has calculated in detail how various types of initial inhomogeneity may amplify (or decay) in an expanding universe, with reference to galaxy formation and the possible detectability of anisotrophies in the background radiation - even though many other authors have subsequently addressed these problems, the clearest and soundest treatment is still generally found in Peebles' pioneering papers. He has also investigated the detectability of 'young' galaxies, and offered compelling arguments for 'missing mass' in galactic halos and clusters. More recently, Peebles and his Princeton collaborators have used the various catalogues to carry out elaborate analyses of how galaxies are distributed. His correlation techniques and their results - implying that there are no preferred clustering scales - have dominated thoughts on galaxy formation for several years. Peebles continues to play a leading role in both the empirical and the theoretical sides of the subject. |