Alan Alda recently challenged scientists to explain this simple question to 11-year-olds in less than 300 words.
What is colour?
It’s one of our most common experiences, and we all know it when we see it.
But what, exactly, is colour? Where does it come from, and why does it appear the way it does? Two things are responsible: light and your perceptions.
What you see as white light (like sunlight) is actually all the colours combined, something you can figure out if you shine it through a prism.
What makes one color intrinsically different from any other is the amount of energy it has: for the colors we can see, violet light has the most, while red light has the least.
Objects have different colours because they absorb light with some energies and not others; ones that absorb all the colours are totally black, ones that reflect all the colours are totally white.
A green plant is green because it reflects green light (which reaches your eye) but absorbs blue and red.
So that’s what the different colours are, but there’s something special about ourselves that allow us to see them differently, too!
What does a rainbow look like to you?
The colours you see are due to three types of specialized cells in your eyes known as cones, which are sensitive to blue light, green light, and red light.
Different shades and hues stimulate the three types of cone cells by different amounts, and your brain interprets the signal as the different colours that you see.
The blue, green and red cones working together even allow us to see colours that aren’t in the rainbow at all, like magenta or pink!
Objects have colour, their reflected light hits the cells in your eye, and your brain tells you what to see.
