Pink is a color that is commonly associated with femininity, childhood, and romance. However, many people are surprised to learn that pink is actually not present in the visible light spectrum. This leads to an intriguing question – if pink light does not exist, why do we perceive the color pink?
The visible light spectrum
The colors we see are determined by the wavelengths of visible light. When white light, which contains all wavelengths, passes through a prism it separates into the colors of the rainbow. This is known as the visible light spectrum.
The visible light spectrum contains all the colors that the human eye can detect. Starting from the longest wavelength, the order of colors in the visible spectrum is:
- Red – ~700 nm
- Orange – ~620 nm
- Yellow – ~580 nm
- Green – ~530 nm
- Blue – ~470 nm
- Violet – ~420 nm
As you can see, there is no specific wavelength for the color pink within the visible spectrum. This raises the question – if there is no pink wavelength, how can we see the color pink?
How we see color
To understand how we see the color pink, we first need to understand some basics about how human color vision works.
Our eyes contain special light-sensitive cells called cones. There are three types of cones that are each sensitive to different wavelengths of light:
- S-cones – sensitive to short blue wavelengths
- M-cones – sensitive to medium green wavelengths
- L-cones – sensitive to long red wavelengths
When light enters our eye, it stimulates the three cone types to varying degrees. Our visual system interprets the signals from the three cone types to give us our perception of color.
For example, yellow light stimulates the L-cones (red) and M-cones (green) roughly equally, but stimulates S-cones (blue) very little. This stimulation pattern is interpreted by the brain as the color yellow.
Mixing wavelengths to see pink
This brings us back to the question of how we see the color pink. Pink light does not exist as a single wavelength, but we can perceive it when our eyes receive the right combination of red and blue light.
Red light stimulates the L-cones strongly, while blue light stimulates the S-cones. When these two wavelengths enter our eye simultaneously, our visual system interprets this as the color pink. Essentially, pink is a mix of the two wavelengths at either end of the visible spectrum.
This mixing of light wavelengths is called additive color mixing. By mixing different combinations of red, green, and blue light, our eyes can perceive the range of colors in the visible spectrum – including those not represented by a pure wavelength like pink.
Differences in pink perception
Research has shown that the perception of the color pink can vary significantly between different people:
- Women are more likely than men to select pink as their favorite color or consider it their color of choice for personal products. This may be due to cultural associations between pink and femininity.
- Some people have a condition called pink-green color blindness, where they have trouble distinguishing between pinks and greens. This is due to issues with their M-cone (green) receptors.
- The way we name colors also influences pink perception. Having a separate name for pink makes English speakers recognize it more readily than speakers of languages that classify pink as a shade of red.
So in summary, while pink does not correspond to any single wavelength of light, we are able to perceive it due to the mix of wavelengths and how these stimulate our eye’s color-sensitive cones.
Seeing pink in nature
While pink light itself does not exist, many pink objects in nature selectively reflect pink wavelengths of light. Here are some common examples:
Pink flowers
Many species of flowers contain natural plant pigments called anthocyanins. These pigments absorb green and blue light, while reflecting back red and pink light wavelengths, causing us to see these flowers as pink.
Pink animals
Some animals display pink tones due to pigmentation, blood flow, or diet. Flamingos get their characteristic pink hue from pigments in the shrimp they eat. While pink dolphins and pigs inherit their pinkness through genetics and circulation.
Pink skies
When the sun is low on the horizon, its light has to pass through more atmosphere. Shorter blue wavelengths are scattered away, leaving longer pink/red wavelengths to give dramatic pink sunrises and sunsets.
The future of seeing pink
Advancements in technology are adding to our perception and use of the color pink.
- Laser light shows can generate pure pink tones by combining red and blue lasers. More vivid than light filtered through pigments.
- LED lighting also mixes red and blue light to emit customizable pink light, allowing matching to brand colors.
- Augmented reality overlays and displays can introduce the perception of pink, even on objects lacking physical pigments.
So while pink does not exist as a spectral color, we are clearly able to perceive and use this non-spectral color in many facets of life. Our visual system mixes wavelengths to create color sensations beyond those produced by monochromatic light. This empowers us to paint our world in pink.
Conclusion
The reason we can see the color pink despite it not existing as a single wavelength of light is because of how our visual system mixes and perceives combinations of wavelengths. Pink is essentially a mix of red and blue light. We are able to see pink due to cells in our eyes called cones that are sensitive to these red and blue wavelengths. The stimulation of both the red and blue cones tricks our brain into perceiving the sensation of seeing pink. This additive mixing of light allows us to see a range of colors, including non-spectral colors like pink, that do not correspond to any single wavelength. So while pink light itself does not exist, we are able to visually experience this color through the magic of our color vision.