Black is often considered a color of emptiness and void. However, upon closer inspection, black contains glimpses of every color within it. The key to finding this chromatic diversity lies in examining black’s physical properties and interactions with light.
The Physics of Black
In physics, black is the absence of light. When no visible light is reflected or emitted from an object, it appears black. This occurs because the object absorbs all wavelengths of visible light equally. However, just because black absorbs all visible light does not mean it lacks color.
Sir Isaac Newton demonstrated this in a famous experiment in the 1660s. He used a prism to break up sunlight into its constituent colors – the visible spectrum we know as ROYGBIV (red, orange, yellow, green, blue, indigo, and violet). Newton then recombined these colors using a second prism, reproducing the original white sunlight.
From this experiment, Newton showed that white light contains all colors within it. Black, therefore, can be thought of as the absorption of the entire visible spectrum. So while black absorbs all colors, those colors must inherently exist in black in order for it to absorb them in the first place.
Seeing Hidden Colors
Black’s hidden colors can become visible under certain conditions:
- Metamerism – when two colors match under one light source but not another
- Iridescence – light interference causing shifts in hue
- Reflectance – some dark colors reflect a % of light
Metamerism occurs because the spectrum of light emitted by different sources varies. Sunlight, incandescent bulbs, fluorescent lamps, LEDs – all produce slightly different wavelengths of light. What appears black under one may reveal color under another. Iridescence is an optical effect from light interference at nano-scale structures on a surface. It splits white light into rainbow colors. Finally, some seemingly black materials can reflect a tiny percentage of light. Dark colors emerge based on which wavelengths reflect back to our eyes.
Mixing Colors
Black can result from mixing two colors of pigment or light. In art, black is traditionally mixed using complementary colors opposite on the color wheel:
- Blue + Orange = Black
- Green + Red = Black
- Yellow + Purple = Black
Digital screens like TVs or phones create black by mixing light from red, green, and blue pixels (the RGB color model). In printing, black ink is composite – containing cyan, magenta, and yellow pigments within the “black” ink. As a result, mixing colors to create black imbues black with hints of those colors.
Black Body Radiation
Heating an object causes it to glow, emitting black body radiation. The temperature determines the wavelengths emitted, producing vivid colors. While cooler black bodies appear reddish, hotter ones trend blue. Even at moderate heat, though, the full spectrum emerges – including green, yellow, and white.
For example, blacksmiths know the colors of heated steel by heart: 425°C emits faint red, 600°C glows a brighter cherry red, 900°C turns orange-yellow, and 1350°C approaches white hot. Though dark at room temperature, black therefore contains a veritable rainbow.
Black Dyes and Pigments
Examining the sources of black dyes and pigments further unveils the colors hidden within:
- Carbon black – Soot residue from burning organic matter like charcoal, tar, and plant oils. Carbon molecules absorb across the visible spectrum.
- Ivory black – Charred animal bones, containing calcium phosphate and carbon. Popular historic black pigment.
- Lamp black – Very pure carbon soot from controlled burning of oils in lantern-like chambers.
- Iron oxide black – Black iron (II, III) oxide, commonly mineral magnetite. Partly absorbs, partly reflects blue and purple hues.
- PBk31 – Modern masstone black pigment. Composite of dyes, inorganic pigments, and metal oxides for deep black color.
While pure carbon black absorbs fully across the spectrum, many other black pigments reflect hints of color. These echoes emerge through microscopy or spectroscopy, even if imperceptible to the naked eye.
Black in Nature
Black spans the natural world, from animals to plants to minerals. Melanin, a class of pigments occurring across biology, produces common black, brown, and grey tones. However, it chemically absorbs light selectively, imparting rich underlying hues. Truly black melanin combines with other pigments, like reddish-black eumelanin and yellow-black pheomelanin. Iridescence in birds and insects also reveals colorful mechanisms beneath their dark exterior.
Black and Color Perception
Human color perception itself links black with our experience of all other colors. The retinal cells sensing color connect to black-and-white sensing cells that handle mixtures of light and dark. Black forms the essential backdrop defining the appearance of colors. Artists intensify brightness and saturation of hues by juxtaposing them against deep black.
Optical illusions playing with contrast effects demonstrate this as well. Are the horizontal bars bent or straight in this grid? Our perception of color deceives us thanks to the alternating black lines.
| █ | █ | █ | █ | █ | █ | █ |
Black both defines and plays with color thanks to its special connection to light and visual processing. It is not an empty void but rather a rich composite from across the chromatic spectrum.
Schrodinger’s Cat and Superblack Materials
The quantum physics thought experiment of Schrodinger’s Cat imagines a cat in box that is simultaneously dead and alive until observed. Black contains such dichotomies: light yet dark, a color yet the absorption of color, repelling yet blending with all hues.
New ultra-black materials like Vantablack point to these paradoxes. By structuring carbon nanotubes vertically, Vantablack absorbs 99.965% of light, setting a record for darkest human-made substance. However, there are still wavelengths to absorb. Perhaps one day even deeper blacks will reveal the entire spectrum within.
Conclusion
Black is a surprisingly colorful paradox. While black absorbs all visible light, it contains glimmers of every color within its light-swallowing surface. Physics shows that black arises from absorbing the entire spectrum. Mixing complementary colors creates black pigments and dyes composite with multiple hues. Black in nature selectively absorbs and reflects various wavelengths. Our visual perception itself inextricably links black and color. So while black first appears empty, exploring its deeper properties illuminates the vibrancy waiting inside.
