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Theories of Color

September 29, 2012

Theory #1 (Light absorbs color from surfaces, and then some bounces off):

Light from the sun is, for the most part, colorless until it comes upon a surface with color. The sun light that hits the surface absorbs the color from the surface, and when it bounces off the surface it carries that color with it.

Theory #2 (Surfaces absorb some light colors and reflects other)

Light from the sun has all the rainbow colors (like ROYGBIV). When light hits a surface, some of the color gets absorbed into the surface, while other colors bounce of the surface.

Theory #2a  (reflected colors represent color of objects)

The color that we perceive surfaces to be is due to the colored light coming off and entering into our eyes, creating a “visual perception” of color based on the light that enters.

Theory #2b:  (absorbed color represent the color of objects)

The color that we perceive surfaces to be is due to the color light that stays with the object. Because that color is absorbed into the material, it gives that material the visual effect of having that color.

The general consensus is that none of these theories seems adequate and all of them have problems.

We have many arguments for and against, so here is just a few examples for each theory:

Theory #1:

Arguments for:  Colored objects left out in the sun become sun-faded. When you shine a flashlight on colored paper, light of that color comes off.

Arguments against: Prisms and rainbows suggest that sun light already has all the colors. White light from the computer screen isn’t colorless, its made of red, green, and blue.

Challenge: Explaining how color shows up with things like CDs, rainbows, which don’t have any instinstic color for light to absorb.

Theory #2a:

Arguments for:  Prisms and rainbows suggest color is already in sunlight. When you shine a flashlight on colored paper, light of that color comes off.

Argument against: Some colors like grey are not a rainbow color, so in the theory it would seem grey can’t be reflected off, but we grey things exist.

Challenge for: Explaining how surfaces “know” which colors to send off and which to absorb. There isn’t a “gate keeper” person there, telling which colors get to stay and which colors must go on.

Theory #2b:

Arguments for:  When things get colored in everyday life, its because the surface absorbed that color and the color stayed there. This is how painting works and why red wine stains.

Arguments against:  Blue light comes off of blue things (we’ve seen it on our hands when shining flashlights on blue construction paper)


A student asked this question at the end of the day:  If you get rid of all the lights in a room, do the objects still have color?

I’m thinking…

We are deep into ontology: What is the nature of light? What is the nature of color?

We are deep into mechanisms: What are the interactions that can occur between light and materials?

We are also deep in theory-driven science: What evidence can we marshall for and against theories?

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