Is Color Just an Illusion? What Newton’s Prism Experiment Revealed

When you look at a rainbow or a bright computer screen, it feels obvious that colors are part of the world around us. But in the 17th century, Isaac Newton discovered something that turned this idea upside down: **light itself has no color.**

In his famous prism experiment, Newton passed a beam of sunlight through a glass prism and split it into seven distinct colors—the spectrum we all recognize today. At first glance, this might seem like proof that light *contains* colors. But Newton went further. He noticed that when these colored rays overlapped, they created countless new shades and gradations. This led him to conclude that light is not uniform, but made up of rays with different “refrangibility.”

In his book *Opticks*, Newton made a bold claim: **“To speak properly, the rays of light have no color.”**

Color, he argued, is not a property of light itself, but the result of how our eyes and brain respond to different kinds of rays.

What about objects? Why does a leaf look green, or the sky appear blue? Newton explained that objects don’t *possess* color. Instead, they reflect some kinds of light more strongly than others. In other words, color is an effect of interaction—not an intrinsic feature of matter.

This insight laid the foundation for modern optics and completely reshaped our understanding of light and perception. From rainbows to screen displays to spectroscopy, much of today’s science and technology builds on Newton’s groundbreaking discovery.