The world showcases vibrant shades of purple, from lavender flowers and amethyst gemstones to plums, eggplants, and purple emperor butterflies. However, if you examine the Electromagnetic Spectrum closely, you’ll find that purple doesn’t exist (aside from the bluish hints of violet and indigo).
This absence is because purple is a construct of our brains, arising solely from neural processing.
Does this imply that purple is non-existent? Not quite. The key lies in our perception and the combination of various wavelengths within the visible light spectrum.
“I would argue that it doesn’t actually exist,” said Zab Johnson, executive director and senior fellow of the Wharton Neuroscience Initiative at the University of Pennsylvania. “It’s all about the workings of our nervous system, embodying both beauty and complexity.”
Every color originates with light. As sunlight reaches the Earth, it encompasses a variety of wavelengths, including long wavelengths like Infrared and Radio waves, alongside shorter, high-energy wavelengths like X-rays. Ultraviolet rays can also harm our bodies, according to Live Science.
Visible light, which constitutes only around 0.0035% of the electromagnetic spectrum, is what our brain perceives. This narrow band is what we recognize as the colors of a rainbow. The spectrum ranges from long wavelengths associated with red to shorter wavelengths linked with indigo and violet.
Our color perception hinges on specialized receptors behind the eye, known as cones, which respond to visible light. The human eye contains three types of cones: those sensitive to long, medium, and short wavelengths. Long wavelength cones respond to reddish light, medium wavelength cones are attuned to green, and short wavelength cones detect blue.
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When light interacts with our eyes, these three cone types process light information and generate electrical signals for the brain. The brain then interprets this data to formulate our visual experience.
“Our mechanisms continuously perform this intricate computation involving these three varying ratios,” Johnson explained. For instance, if both long and medium wavelength cones are activated, the brain perceives orange or yellow. However, when the medium and short wavelength cones are stimulated, the brain infers teal.
What about purple? When short (blue) and long (red) cones are activated, the brain “creates colors that don’t actually exist in reality,” Johnson stated. Red and blue occupy opposite ends of the visible spectrum; thus, when the brain encounters these wavelengths, it bends our linear perception of the spectrum into a circular representation. Essentially, this means light doesn’t behave this way, but rather, it’s the combination of red and blue that leads to the perception of purple and magenta.
Consequently, purple and magenta are classified as “nonspectral” colors, as they do not exist as distinct electromagnetic radiation. Nonspectral colors, like purple, result from light composed of two different wavelengths. In contrast, spectral colors such as red, orange, yellow, green, blue, indigo, and, notably, violet, consist of single wavelengths.
Regardless of its tangible existence, purple has captivated humanity for millennia, as noted by Narayan Kandecal, Director of the Straus Center for Conservation and Technical Studies at Harvard Museum. For example, the ancient Phoenicians derived a color named Tyrian purple by crushing sea snails, often used for royal or ceremonial robes. Today, purple retains associations with wealth, power, and even magic. “That association endures, though there are now various shades of purple available,” he stated to Live Science.
Whether it is generated by our minds or crafted from crushed shellfish, purple maintains its uniqueness and warrants a careful appreciation. “Since it doesn’t actually occur in nature, its creation carries an additional significance,” Johnson remarked. “Hence, purple is now even more extraordinary.”
Source: www.livescience.com