We often think of color in a Roy G. Biv sort of way; young kids are taught about the basic primary colors of blue, red, and yellow, and eventually they graduate to the “color wheel” that you may remember from school. The wheel actually has quite a history: it was Isaac Newton himself who invented it, in 1704. Newton also assigned a musical note to each color; meaning in theory you could take any array of colors - like those in a painting or photograph - and derive a musical composition from them.
A later version the wheel that strongly influenced the way color is taught in schools was invented by Milton Maycock-Bradley (the guy, not the toy company that later bore his name); it turns out Mr. Bradley was extremely worried that kids weren’t learning enough about colors in school.
But more than just learning the names of different hues, it’s the way we perceive color that’s important. As Michael mentioned in his classic video, Is Your Red the Same As My Red?, color does not, in a sense, exist out there independently in the world; it’s a function of the human visual system, a sensation constructed by our brains as they perceive visual input. What we see as color is the way our grey matter interprets varying frequencies of electromagnetic waves that are experienced by the eyes. So a red ball isn’t really red, it’s made of a material that exists in the world in a way that humans perceive it as red - as it reflects red wavelengths of light back into our eyes.
And because of the way our eyes are receiving that red light, the ball is, in a weird way, everything except red, since it’s absorbing the light that’s in every other color of the spectrum but reflecting the red light back at us. So an argument could be made that the ball is actually every other color; you could even consider it “anti-red”! Interestingly, if you want to figure out what colors of light something is absorbing versus reflecting, you go back to that color wheel: an object is absorbing the color that you see on the opposite side of the wheel from which it appears to be; so a blue object is absorbing orange light, a yellow one is absorbing purple, etc.).
While we’re talking about this: what does it mean when you hear people say something “absorbs” some of the colors of light? How does an object absorb colors? It’s really just a way of discussing where the energy in the light goes: when light hits the atoms in the object, the energy is transferred to those atoms, and causes electrons to jump about a bit; so the energy is “absorbed” into the material in the sense that it is transformed into another form of energy and not seen again as light.
For your cube, though, because it’s transparent, most of that light isn’t absorbed, it’s transmitted through. For details on how this affects the colors you see and their wavelengths, check out Michael’s short video on the cube, below. In general, light hitting an object can do three things: 1) be transmitted, 2) be absorbed, or 3) be reflected. This leads to two different ways that things out in the world can be colored (or appear colored to our brains), which are known as additive and subtractive color.
Additive color mixing is, to some degree, the color of light. It’s the colors you see on a computer monitor or phone screen, and is generally made up of red, green, and blue (RGB color), which are combined in various amounts so your brain puts them together to perceive an array of different colors. With additive color, the color you see is created by combining lights of different wavelengths.
Subtractive color mixing involves the opposite - filtering out different wavelengths to get specific colors. Generally it uses a white background and then, like in your cube, the colors are created by mixing different amounts of cyan, magenta, and yellow (called the “subtractive color primaries” - CMY color). Typically, it’s the type of color mixing you get with pigments: printed photos and graphics are created with subtractive color, for example. One of the unusual things about your cube is that it’s an example of subtractive color using white light, rather than pigments.
Now, you might imagine that using additive versus subtractive colors wouldn’t make a lot of difference, but in practice, because of the way each uses different wavelengths of light to create colors, you get some strange results when you compare additive and subtractive mixing. For example, with additive, pink is made up of a mixture of red and purple light; in subtractive, it’s a mix of red and white pigment.
Another strange thing about colors is that because it’s really the interactions between wavelengths that create them, an object’s color doesn’t just depend on what color it “actually” is, but what type of light you’re seeing it in. We usually talk about objects by the color they would appear to be in regular, white light - like the red ball from a few paragraphs ago. In white light, that ball looks red, because the light has all the other colors in it: the ball is reflecting red light back, and absorbing the blue, green, and other colors. If you shine a red light on the ball, it’ll still look red (because there is red light present to be reflected). But what if you shine a blue light on it? It can’t look red, because there’s no red light to reflect back; and it won’t look blue because it’s absorbing the blue light - so it will just sort of look black.
That’s similar to what happens when you view human blood underwater. Blood is red; as you see below, a spectral analysis of its color reflectance shows that. But you’ll also see that it’s a tiny bit green.
graph by Christopher Baird
Now, blood is always a little bit green, but it’s so red that in normal light we don’t notice that, only the familiar bright crimson. But in light that doesn’t have much red - like the bluish light at the bottom of the ocean - the green would show up, but the red would not, and boom - green blood.
Chromatics - the science of color - is a fascinating field, and this is just a taste of the surprising things it’s discovered. It turns out that color really is in the eye of the beholder, and we hope you enjoy beholding your new CMY cube, and all of the many colors you’ll find dancing within.
