ABSTRACT
Virtually all the naturally occurring light originates from the sun, and the question for this chapter is: “Why can we see sunlight?”
In order to answer this question, we need to consider a) what is sunlight, b) how light propagates from a source to a destination and c) how light can be detected by living organisms. Even when detected, though, without some form of information processing, the data obtained from the light detectors will be useless so we need to “see” what is minimally required to have some form of vision. Last, one may wonder why the sense of vision evolved in the first place.
