The Optical Approach to Casimir Effects
  We propose a new approach to the Casimir effect based on classical ray optics. We define and compute the contribution of classical optical paths to the Casimir force between rigid bodies. Our approach improves upon the proximity force approximation. It can be generalized easily to arbitrary geometries, different boundary conditions, to the computation of Casimir energy densities and to many other situations. This is a brief introduction to the method. Joint work with R.L.Jaffe. 
Antonello Scardicchio