I just joined to ask this question... I was imagining a sphere made of mirrors inside it and shooting a light to the inside (assuming none of it would escape back through the same hole). Once light enters, it will forever bounce inside the sphere. So my question is, will there be a limit of the amount of light that can 'fit' the sphere? In other words, as light has no volume, is there a limit of the amount of light that can fit inside a given volume or is it potentially infinite?