Light in a sphere

If you put light inside a sphere, and the sphere was made out of reflective material - the light should bounce around it forever, right?

What would happen if you shinned a lazor in it? More and more light would get added,

Hmm, is it actually geometrically impossible to fire a laser into a hole in a sphere in such a way that the reflected beam never hits the hole again?  I'm not sure.

Me neither but I highly doubt it given that the hole is of a finite size (err... it's not infinitely small). Also, it wouldn't have to exit the hole in the same direction that it entered.