Proceedings of International Meeting held in Trieste, Italy, April 10-13, 1985

The large-scale structure of the Universe and systems Clusters, and Groups of galaxies are topics like Superclusters, They fully justify the meeting on "Clusters of great interest. and Groups of Galaxies." The topics covered included the spatial distribution and the clustering of galaxies; the properties of Superclusters, Clusters and Groups of galaxies; radio and X-ray observations; the problem of unseen matter; theories concerning hierarchical clustering, pancakes, cluster and galaxy formation and evolution. The meeting was held at the International Center for Theoretical Physics in Trieste (Italy) from September 13 to September 16, 1983. It was attended by about 150 participants from 22 nations who presented 67 invited lectures (il) and contributed papers (cp), and 45 poster papers (pp). The Scientific Organizing Committee consisted of F. Bertola, P. Biermann, A. Cavaliere, N. Dallaporta, D. Gerba1, M. Hack, J . V . Peach, D. Sciama (Chairman), G. Setti, M. Tarenghi. We are particularly indebted to D. Sciama, A. Cavaliere and F. Bertola for their work of coordination. We were acting as the three members of the Local Organizing Committee. Moreover, we are pleased to thank the Chairmen of the Sessions (M. Hack, N. Da11aporta, G. Burbidge, B. Mills, M. Rees, P. Biermann, L.Z. Fang, L. Gouguenheim) for their valuable help.

The 1980's have been times of great excitement in Astrophysics and Cosmology. Professors Dennis Sciama and Fabio Mardirossian and all the other Members of the Organizing Committees are to be congratulated for having given us a taste of this excitement in Trieste, by inviting the leaders of the subject to the meeting they have organized. The excitement has corne from the new observations of the three-dimensional structure of the universe through a large number of new measurements of redshifts. These have revealed that clusters of galaxies are distributed on the surface of big empty bubbles of diameters of the order of 20-50 Mpc. Additionally, there is some evidence for invisible dark matter (whose composition is not known) as well as evidence for the gravitational lens effect. To cap this has corne the supernova of 1987, an event which last occurred 383 years ago. For the first time in history, the neutrino flux from the supernova was measured, giving limits to neutrino masses and numbers of neutrino types. (The dark matter problem is related to Particle Physics - beyond this standard model). It is good to be alive when all this happens and to try to comprehend this. Once again, our appreciation to the organisers and to those who presented their beautiful results.

Proceedings of International Meeting held in Trieste, Italy, April 10-13, 1985