SUPERGRAVITY P. van NIEUWENHUIZEN To Joel Scherk 0370 ...

In memoriam Joel ScherkJoel Scherk died on May 16, 1980. Although 33 years old, he had made many very importantdiscoveries in dual string theory and supergravity, as will be manifest in this review. It is striking tonote how logical and sustained the development of his thinking was.His first important contribution was the renormalization of the one-loop open dual string amplitude.Then he developed the idea of the zero-slope limit when all masses except the lightest tend to infinity,and found that this leads to quantum field theories. In particular the closed string sector yielded generalrelativity, and from then on he was fascinated by gravitation. The one-loop contributions of the openstring model in d = 26 dimensions were shown to correspond to a new ghost-free set of states,corresponding to closed Strings and interpreted as Pomeron states. One of these states was described byan antisymmetric tensor gauge field, which is nowadays of interest. Then he started wondering whathappens with the extra dimensions in our four-dimensional world. This led him to the idea ofspontaneous compactification of space-time, extending ideas of Kalusza and Klein.In supergravity he started by solving the matter coupling problem and worked out the super-Higgseffect. Then he constructed the N = 3 supergravity, and both the SO(4) and the SU(4) versions of N = 4extended supergravity. The latter model was suggested by taking the zero slope limit of the d 10dimensional closed string dual model with fermions. The d = 10 open string model yielded in the zeroslope limit N = 4 supersymmetric Yang—Mills theory. In the SU(4) model he found a noncompactSU(1, 1) global symmetry, and in the N = 2, 3, 4 models he gave a complete treatment of the dualityand chiral symmetries. He then formulated N = 1 d = 11 supergravity, which yields the N = 8 d = 4model upon dimensional reduction. He also developed the idea of spontaneous symmetry breaking bymeans of dimensional reduction, and worked out the particle spectrum. There he found a masslessvector boson and proposed the idea that it yields the (testable) force of antigravity.Despite this impressive record, Joel was a relaxed and very friendly person. He was among the bestand most pedagogical speakers and his articles were crystal clear. He was always open to discussionand had a very developed sense of humour. He also contributed actively to the popularization oftheoretical physics by radio talks, lectures for lay-men and articles in popular scientific magazines.This short review was written by his closest friends. We will miss him deeply.