Activities in 1985-1986

From the Report for Academic Year 1985-1986
of the Institute for Advanced Study

PIET HUT continued his research in stellar dynamics, where he concentrated on the dynamical evolution of globular clusters. He collaborated with: Shogo Inagaki from Kyoto University, Japan; Jun Makino from Tokyo University, Japan; Andy Fabian, Peter Eggleton and Jim Pringle from the Institute of Astronomy, Cambridge, UK; Frank Verbunt from the Max-Planck-Institute near Munich, West Germany; Haldan Cohn from Indiana University; and Herwig de Jonghe.

Piet Hut entered a new area of research in the interface between Computer Science and Astrophysics. He started a long-term collaboration with Gerald Sussman, from the Artificial Intelligence Laboratory at M.I.T. This collaboration concerns the development of qualitatively new types of software, and in the future possibly new special-purpose hardware, for setting up, executing and analyzing dynamical simulations of galaxies and star clusters. In a related project, Joshua Barnes and Piet Hut developed a novel algorithm for performing N-body calculations in which the number of interactions per particle grows only logarithmically.

Another field of interdisciplinary research in which Piet Hut was active was a collaboration between four paleontologists including Erle Kauffman and William Elder (University of Colorado, Boulder), Gerta Keller (Princeton University) and Thorn Hansen (Western Washington University), two geologists, Walter Alvarez (University of California, Berkeley) and Eugene Shoemaker (United States Geological Survey, Flagstaff, Arizona) and two astronomers, Paul Weissman (Jet Propulsion Laboratory, Pasadena, California) and Piet Hut. Together they wrote a comprehensive paper which addresses the possibility of comet showers causing mass extinctions, in a critical comparison of material from all three disciplines. Piet Hut and Gerta Keller were invited to give a Luis Clark Vanuxem Public Lecture at Princeton University in December 1985, in which they reported on the results of their collaboration.