1801–1803Reputable sourceWell documented
Young and the Wave Nature of Light
On the timeline · around 1801–1803 ·
What happened
Newton had held that light was a stream of particles, but around 1801 the English polymath Thomas Young challenged him. In his famous double-slit experiment, Young passed light through two narrow slits and saw it form an interference pattern of bright and dark bands — behaviour possible only if light travels as a wave. He even measured the wavelengths of different colours.
Why it matters
Young's experiment established the wave theory of light and became one of the most celebrated demonstrations in physics. Revived a century later in the quantum era, the double-slit experiment now stands as the classic illustration of the strange wave–particle duality of nature.