(June 2, 2012 at 9:41 pm)padraic Wrote: Colour is perception,and apparently varies with species, and even within species (ours,at least)
Perception of color varies, yes. However, color is defined not by our perception of it, but by the wavelength of the reflected light, which is somewhat less subjective.
ETA: Actually, we're both correct. Color can be described by both visual perception as well as by the wavelength of reflected light. Perception can vary not only per observer but on environmental conditions.
From experience as a diver, I can relate that a red fish (or rather, one that would appear red at the surface) at 100' depth does not appear red unless a light is shined on it - but only because the red portion of the spectrum from sunlight is fully absorbed at shallower depths. Is it still red? I suppose that depends on your perspective.
