Abstract:
The triangular billiards problem, which goes back
about 200 years, asks if every triangular shaped billiard
table has a periodic billiard path. Until recently, almost
nothing was known about this problem. In particular, it was
not known if there was any epsilon>0 such that all obtuse triangles
with big angle less than 90+epsilon degrees had a periodic
billiard path. I will describe my computeraided (but rigorous)
proof that a triangle has a periodic billiard path if all
its angles are less than 100 degrees. During the talk, I
hope to demonstrate McBilliards, a graphical user interface
which lets the user survey the proof and also experiment with
triangular billiards.
