Throughout history, the conundrum of colour has exercised some very bright minds.
Isaac Newton, 1666
In 1666, Isaac Newton experimented with a beam of light and a transparent, triangular prism.
He observed that when light passed through this, it split – or dispersed – into different coloured rays.
Newton had discovered that white light is composed of the visible colours.
What wasn't known then is that light, like sound, travels in waves.
As they encounter a new medium, light waves can bounce back in reflection.
Or, they can change direction, known as refraction.
How much a light ray is refracted depends on its wavelength because different wavelengths travel through the glass at slightly different speeds.
Violet has the shortest wavelength and travels at the slowest speed through the medium, refracting the most, while red has the longest and travels the fastest, refracting the least.
So colours are how our brains perceive different wavelengths of visible light.
When we see a rainbow, raindrops are splitting the travelling light, like Newton's prism, into a colourful spectrum.
Different materials react to light in different ways, according to their physical properties.
Some reflect most white light.
Others tend to absorb more.
Black absorbs all wavelengths of light, so no colour is reflected back.
Hence the dark colouring of solar panels, for maximum absorption of sunlight.
Conversely, if something's white, it's reflecting back all of the wavelengths of light.
That's why buildings are painted white in hot countries – to reflect sunlight and keep the occupants cool.
Beyond black and white, objects appear coloured according to which wavelengths of light they cannot absorb.
So something red absorbs many of the wavelengths that make up white light, but reflects the wavelengths that we perceive as a particular, brilliant red.
The world may appear to be full of colour, but remember, these dazzling shades are merely how our brains perceive different wavelengths of light.