After reading Mach’s book on Optics, I came away thinking that the idea that “White Light contains all the colors” is a lie.
I’m leaning toward believing that Sunlight (which is what Newton had in mind when he talked about “White Light”) contains, in fact, no color at all, but only the quality we call “Brightness.” This is because the photons arriving from the Sun are arriving all jumbled, giving the human visual apparatus no reason to recognize any colors. It is only when order is imposed upon this crazy storm of photons that the visual apparatus begins to register certain photon-patterns as “color.”
One way to impose order on arriving Sunlight is by the use of a prism. The properties of the prism manipulate the arriving Sunlight into ordered bands (the “rainbow”), based on photon-frequency, which the human visual apparatus can then recognize as color.
However, it is obvious when looking at a rainbow that only about 7 colors are discernable to the human visual apparatus based solely on single-frequencies of photon-impact. All the other colors of the world are created by the MIXTURE of frequencies. These colors are NOT “contained” in White Light at all– well, indirectly maybe, but not in the way it is typically imagined and taught. Most colors are created by MATTER– specifically, Matter that comes in contact with the Energy provided by Light. Matter absorbes this Energy, conducts certain reactions, and re-emits Energy-pulses (photons) of varying frequencies. Certain mixtures of certain emission-frequencies register in the human visual apparatus as color. The only colors stimulated by SINGLE frequencies are those of the rainbow. All other colors are mixtures of frequencies.
It is NOT true that the color of objects is the result of the Light they reflect. Truly reflected Sunlight maintains its character as (what is misleadingly called) “White Light.” Object-Color is the RE-emission of the Sun’s Energy absorbed by Matter. This re-emitted Energy will always be less than the absorbed Energy (unless Energy is added from another source or storage-center).