The fourth course of the International School of Physics of Exotic Atoms
took place at the "Ettore Majorana" Center for Scien- tific Culture,
Erice, from March 31 to April 6, 1984. As tradition, exotic atoms have
been a tool for studying elec- tromagnetic, weak and strong interactions
at low energies. We felt it appropriate to have a full course devoted to
a discussion of the information to be gained on the fundamental
interactions from the study of low energy systems. In this kind of
physics, which is characterized experimentally by very intense particle
sources and very sensitive apparatuses, one can search for rare events
and can perform precise measurements. Sensitive tests of the predictions
of current theories of electro- weak and strong interactions can thus be
achieved. The course was attended by 54 participants from 23 institutes
in 9 countries. The morning lectures reviewed the achievements of the
field in the last few years and the afternoon seminars dealt with new
results and projects.