Do All Electromagnetic Radiations Have Different Colours?

In this article, we will explore the fascinating interaction between electromagnetic radiation and color perception. We will delve into the science behind what we see and what is invisible to us, and how different species perceive their world.

The Visible Light Spectrum and Color Perception

Most of us are familiar with the visible light spectrum, which ranges from approximately 380 to 750 nanometers (nm). Within this narrow band, we can perceive a spectrum of colors, from the deep red to the violet, which appears furthest in the electromagnetic spectrum. This range is astonishingly small considering that the entire electromagnetic spectrum spans from as short as gamma rays (less than 0.000018 nm) to as long as radio waves (up to several kilometers).

Our perception of color is rooted in our visual systems. The retina in our eyes contains three types of color-sensitive light receptor cells called cones. These cones peak in sensitivity to different portions of the spectrum: red, green, and blue. This trio allows us to experience the colors that we see.

Outside the Visible Light Spectrum

However, outside this narrow spectrum, our eyes cannot perceive electromagnetic radiation as colors. Wavelengths longer than 750 nm are in the infrared and microwave regions, which we can only detect through specialized sensors or heat receptors in our skin. Conversely, wavelengths shorter than 380 nm fall into the ultraviolet, X-ray, and gamma-ray regions. These higher-energy wavelengths can be harmful to our cells and even lead to cancer.

Color Perception Beyond the Visible Spectrum

Color is a subjective experience, and it is experienced only by beings with visual capabilities. For example, bees have the ability to perceive ultraviolet light, which is invisible to us. Despite this, they can distinguish between different wavelengths even in the ultraviolet range, making the surface of flowers look like an elaborate landing pad to them.

If you are curious to see how bees perceive the world, you can explore “See Like A Bee: Ultraviolet Flower Photography”, where different examples of how bees see flowers are showcased. It is essential, however, to remember that the colors in these photographs are arbitrary, as they are created to represent what a bee might see.

The Nature of Color and Wavelengths

Color is not inherent to the wavelengths themselves; rather, it is a subjective experience that arises when we perceive these wavelengths. Red, for instance, is not a single wavelength but rather a range of wavelengths that we interpret as red. This range can be different for various species.

The mantis shrimp, known for its complex visual system, can distinguish between different polarizations of light, perceiving each as a different color. This means that the same wavelength can appear as multiple colors, depending on the species or the visual system used.

Conversely, while different wavelengths appear as different colors to us, it's important to note that any attempts to interpret signals outside the visible spectrum as colors are constrained by our own limitations. We might attempt to give a frequency a name, but any perception of color would inevitably be influenced by our existing bias, leading us to imagine it as a shade of a visible color.

Understanding the nature of color and electromagnetic radiation is crucial for fields such as photonics, optics, and even medicine. It opens up new possibilities for both scientific research and technological advancements.

For further reading, you can explore more on electromagnetic radiation, color perception, and the visible light spectrum. These topics offer endless fascination and can deepen your understanding of the world around us.