  The Casimir effect refers to the existence of a macroscopic force between
conducting plates in vacuum due to quantum fluctuations of fields. These forces
play an important role, among other things, in the design of nano-scale
mechanical devices. Accurate experimental observations of this phenomenon have
motivated the development of new theoretical approaches in dealing with the
effects of different geometries, temperature etc. In this talk, I will focus on
a new method we have developed in calculating the contribution to the Casimir
effect due to diffraction from edges and holes in different geometries, at zero
and at finite temperature.
