If grass is green because the blades reflect green light what colour is grass by nature?

Answer 1

This kind of question has caught my imagination as well-- at first it sounds like a joke. If an object is green because it absorbs all the frequencies of light except green, and the green light is reflected away from the object, doesn't this lead one to wonder about the actual color of the object? The object is rejecting the light the color of which we attribute to it. I think we have to conclude that regardless of the nature of the object, if an object reflects green light we assign to it the color green. However a more intriguing possibility is that color itself is a psychological phenomenon, in a way analogous to the pitch of sounds. Perhaps color doesn't really exist as a thing, but is the psychological interpretation that our brains give to light of various frequencies. I think we could then conclude that no objects are in fact colored at all, but can simply be categorized by the frequencies of EMR that the object absorbs and reflects. Of course, humans that we are, we can still go on enjoying the experience of color no matter what it is. Related to this is the fact that in western cultures, the usual interpretation of relative pitch is that as you move toward the left on a piano keyboard, for example, the pitch is going 'down', and as you move to the right the pitch is going 'up'. But this is not universal. Some cultures interpret pitch in just the opposite way. There is nothing inherently 'up' about 'upper' registers of a keyboard. ___________________ I think now that I may have mis-understood the questioner's original intent. Grass and many other plants appear green because of the chlorophyl in them. Plant material without chlorophyl would have a variety of color depending on the plants, but one indication might be the wonderful colors we observe in deciduous forests in the fall.