Mirrors versus diffuse reflection

Years back I experimented with this concept in a roleplaying game. In this setting I had habitats layered likeonions, with several layers of forests piled on top, and inbetween the trees huge pillars that leaked bright green light. The "higher" up the trees one travelled, the lighteryou became. It took the characters a while to realise they lived in a space habitat circling the sun at an orbit further than Neptune. The light the habitat received was collected and focussed from within the orbit of Mercury. Please do consider the experiments done in japan to convey light by fiberoptic cable, to illuminate enclosed office spaces, or for catfish tanks. This could very well evolve into an aesthetic form of architecture we can scarcely comprehend or appreciate right now.