There is a perfect box with with no gaps or cracks, with mirrors on the interior walls of the box. There is also a light bulb which can emit light but reflects any that goes upon it (with a super two-way mirrored surface, perhaps?). If one switches the lightbulb on, then there is light in the box. What happenes when the light is switched off? As the walls will reflect it and there is nothing to absorb it, will it go on being reflected for a long period of time, or forever if the mirrors are perfect? I was thinking about this for quite a while now, and I know there must be holes in the experiement, but if all the conditions are perfect, is there anything that will stop the light from bouncing around forever inside the box? Thanks!