Thomas Young
A London doctor who guessed, in 1802, that the eye needs only three kinds of color sensor. He was right.
- Lived
- 1773–1829
- Three-receptor idea
- Royal Institution lectures, 1801–02
- Also
- Wave theory of light; Rosetta Stone
Thomas Young (1773–1829) was a physician and one of history's great all-rounders. He read about a dozen languages as a teenager, worked out how the eye's lens changes shape to focus (years before he turned to color vision), was the first to describe astigmatism, and helped decipher Egyptian hieroglyphs on the Rosetta Stone.
His big color idea came in lectures at the Royal Institution in 1801–02. The eye, he reasoned, can't hold a separate sensor for every color, so it must have just three kinds, each responding to a broad band of light, with every color a blend of their signals. He first named them red, yellow and blue, then revised them to red, green and violet. That's trichromacy, later developed by Hermann von Helmholtz and tested by James Clerk Maxwell.
At the same time he was arguing, against the authority of Newton, that light is a wave. His experiments with interference, light waves adding and canceling like ripples on water, let him estimate the wavelengths of different colors, and his numbers came close to modern values. Red light's waves are longer than violet's (see the spectrum).
Young's guess was confirmed in the 20th century, when scientists measured three cone pigments in the human retina. It explains color blindness, why screens need only red, green and blue pixels, and why three lights can match almost any color.
Swatches
- Red · receptor in both versions
- Green · revised version
- Violet · revised version
- Yellow · first version
- Blue · first version
Colors
Sources
- Young, T. (1802). On the theory of light and colours. Philosophical Transactions 92: 12–48.
- Mollon, J. D. (2003). The origins of modern color science. In S. Shevell (ed.), The Science of Color. Optical Society of America.
- Wikipedia, 'Thomas Young (scientist)' and 'Young–Helmholtz theory'.
Hex values are screen approximations. Every page lists its sources.