THE colors they are a visual perception, that is, a “sensory translation” in our brain of a physical quantity which is the wavelength of light within a certain frequency band (the so-called “visible light”). But how many colors are there? The answer is very complex, because we must remember that, first of allcolors technically don’t exist. What exists are the different wavelengths that make up light, which are not divided into separate categories but form a continuum. So technically the colors are infinitebut those that we can actually distinguish depend on our eye. In this sense, therefore, we must consider the maximum potential of our perception: the most popular answer is that this leads us to see 10 million colorsbut people affected by tetrachromy would have the potential to perceive up to 100 times more.
Not just the colors of the rainbow: what is a color from a physical point of view
Since color depends on who perceives it, answering is therefore much less easy than it may seem, and we must admit that we We don’t know the exact number of colors. Just think, this difficulty applies even to things that we consider most certain and banal, such as the rainbow. Traditionally there is this idea that there are seven colors in the rainbow, identified by Isaac Newton by dispersing sunlight with a prism (continuing studies that date back to Aristotle): red, orange, yellow, green, blue, indigo, viola.
Yet this is an inaccuracy, and not even a very subtle one: the colors we see when the rainbow appears are the result of the decomposition of light into its various individual wavelengthswhich gives us a spectrum of colors ranging from the shortest wavelengths of blue and violet to the longest wavelengths of red: we only see those that fall within our “visible light”, which includes the shades from 380 to 780 nanometers in wavelength. And so, for simplicity, we have grouped them into the seven classic shades: but just because we don’t see more of them, it doesn’t mean that these are the only ones present or that – as we read every now and then – some colors “don’t exist” because they don’t appear in the rainbow (that’s the case of poor magenta). As often happens in nature, it’s all a question of spectrum and perspective.
How do we see colors? Cones and rods
If we say that color is a theme of perspective, we must understand How do we see colors?. When a ray of white sunlight (which, remember, contains all the colors) hits an object, the material that object is made of absorbs most of the wavelengths and reflects the rest. For example, if we see a bottle that is blue, we know that the material it is made of is reflecting the blue wavelengths and absorbing all the other wavelengths.
Those light waves, reflected from the sun, bounce directly into our eyes. Specifically, they enter through the cornea, pass through the pupil and arrive at the back of the eye, where there is a tissue called retina. Here there are special cells called sticks And coneswhose task is to identify light and communicate its characteristics to the brain. The cones in particular contain photopigments (i.e. molecules that detect color), which are different from each other: humans generally have three types of photopigments: red, green, and blue, and each type of cone is sensitive to different wavelengths of visible light.
When light hits them, the cones send electrical signals to the brain through the optic nerve, which is connected directly to a part of the brain called the thalamus and then to the visual cortex and the prefrontal cortex. This is how we see colors, understand shapes, and connect the information that comes from our senses to thoughts or memories. Since they depend on personal perception, it can happen that (aside from important variations, such as color blindness) two different people see colors more or less differently from each other.
How many colors can we perceive?
So we are already faced with a different question. And that is: How many colors can we perceive?? To measure our perception of colors, we must remember, as we said above, that the light within the spectrum visible to us is perceived by the cones in the three different categories of photopigments. As reported by theAmerican Academy of Ophthalmologyit is estimated that humans can distinguish up to 10 million colors.
But there are exceptions: researchers estimate that up to 12% of women actually have 4 types of cones in the retina instead of 3: a mutation called tetrachromia. These people would have the potential to perceive 100 times more colors than the rest of us. This first radical difference gives us an idea of the potential for color perception: even animals see different colors than we do, potentially much more numerous (even if the myth of mantis shrimp seeing millions of colors more than us has been debunked). So here we go again: how many colors exist? Well, virtually, infinite.
