A simple model for electromagnetic wave propagation through zero-temperature
plasma is analyzed. Many of the complexities of the plasma state are present
even under these idealized conditions, and a number of mathematical
difficulties emerge. In particular, boundary value problems formulated on the
basis of conventional electromagnetic theory turn out to be ill-posed in this
context. However, conditions may be prescribed under which solutions to the
Dirichlet problem exist in an appropriately weak sense. In addition to its
physical interest, analysis of the cold plasma model illuminates generic
difficulties in formulating and solving boundary value problems for mixed
elliptic-hyperbolic partial differential equations.