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,

Nah, it should come right out. It's physically impossible to construct an object that takes light through a hole and never lets it bounce out (excepting a very very black box and other such tomfoolery). Of course instead of a hole you could use a one way mirror.

Where are you going with this, anyways? Photon cannons you say? That's cool, I guess. Good luck on inventing that perfect reflector in the meantime.