  Consider a strictly convex set $\Omega$ in the plane, and a homogeneous,
stationary magnetic field orthogonal to the plane whose strength is $B$ on the
complement of $\Omega$ and $0$ inside $\Omega$. The trajectories of a charged
particle in this setting are straight lines concatenated with circular arcs of
Larmor radius $\mu$. We examine the dynamics of such a particle and call this
inverse magnetic billiards. Comparisons are made to standard Birkhoff billiards
and magnetic billiards, as some theorems regarding inverse magnetic billiards
are consistent with each of these billiard variants while others are not.
