Chapter 28. Color
Strictly speaking, the rays are not colored.
Optics, Isaac Newton
Most people are able to sense color—it’s the sensation that arises when our eyes are presented with different spectral mixes of light. Light with a wavelength of near 400 nanometers makes most people experience the sensation “blue,” while light with a wavelength near 700 nm causes the sensation “red.” We describe color as a sensation because that’s what it is. It’s tempting to say that the light arriving at our eyes is colored, and we’re just detecting that property, but this misses many essential characteristics of the perceptual process; perhaps the most significant one is this: Two very different mixes of light of different frequencies can ...