This volume comprised the proceedings of a NATO Advanced Study Institute
held in Geilo, Norway between 29 March and 9 April 1987. Al though the
principal support for the meeting was provided by the NATO Cornrni ttee
for Scientific Affairs, a number of additional sponsors also
contributed. Additional funds were received from: Institutt for
Energiteknikk (Norway) The Norwegian Research Council for Science and
Humanities NORDITA (Denmark) VISTA (Norway) The organizing cornrni ttee
would like to take this opportunity to thank all sponsors for their help
in promoting an exciting and rewarding meeting. This Study Institute was
the ninth of a series of meetings held in Geilo on subjects related to
phase transitions and was a natural successor to the 1985 meeting on
Scaling Phenomena in Disordered Systems. Many of the subjects discussed
at the latter meeting were revisited in 1987, with time dependence as an
added feature. Often the common theme was the concept of fractals first
introduced into statistical physics some six years ago. However, by no
means all disordered systems can be forced into a fractal framework, and
many of the lectures reinforced this lesson.