Billiards Obtuse and Irrational

The triangular billiards problem, which
goes back to the 1800s, asks if every triangular
shaped billiard table has a periodic billiard path.
The answer is easily seen to be yes for acute
triangles, right triangles, and triangles whose
angles are rational multiples of Pi. This leaves
the case of obtuse irrational triangles, about
which almost nothing is known. In my talk I will
present new results about the obtuse case, and
will demonstrate McBilliards, a graphical user
interface written by myself and Pat Hooper, which
reveals a wealth of new phenomena in connection
with the triangular billiards problem.