Peter D. Geldart

One of our pervasive conditions is to be immersed in radiation, but what we see is constrained to the visual spectrum, to a sensitivity of about 1/10th of a second, and by our position. Rather than being limitations, these constraints provide a framework in which we can navigate, examine and think about the world. The author considers the taken-for-granted phenomena of moonlight on water and sunlight on snow to show that our position is crucial: when we move bright specular reflections follow us on top of the diffuse background.