not sure if this is posted, so imagine i have a 3- dimensional cube. lets say its about 10m x 10m x 10m in volume. this cube is empty on the inside but its inner surface is covered with mirrors. normal plane mirrors all around the walls, like tiles but instead mirrors. so what happens if i switch on a light bulb inside this box and immediately switch it off. will the light escape when i can ensure that there is not a single hole / leak available for the light to escape. or in other words. will the light be still bouncing around in the cube even after the light source is switched off?