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Re: Color



I don't know exactly what is meant by color when used as in the original
question but I want my students to understand that there is no particular
wavelength of electromagnetic radiation that is perceived as white
and therefore
no wavelength we would call white light. I want them to understand that white
is something that your brain makes up when it overloads on visible wavelengths
coming from a common source. The eye sends a message that says there is some
blue light coming from over there along with some green. Some red is mixed in
too. Perhaps some purple or even a bit of yellow. Now your brain having
received all of these varying messages from the optic nerve says something
like... Blue, green, red, yellow...what should I do with all of this???? I
think I'll make something up. How about white. The only place in
the universe
that white exists is in your brain.

That sounds like orthodox solipsism to me. Confining my attention solely to
the matter of colored light, let me say that any given white light can be
matched by a standard observer to a mixture of two spectral sources, say a
spectral blue and a spectral orange. Moreover, for any given white that
mixture is not unique. A deep violet and a yellow-green, or alternatively a
deep red and a blue-green could be mixed to produce the same percept.

That's what color theory says. That isn't the way that colorimeters are
constructed, of course.

Leigh