Final answer:
Thomas Young used the double-slit experiment to prove that light has wave-like properties, a finding that contrasted with Isaac Newton's particle theory of light. The experiment's success led to widespread acceptance of the wave theory of light.
Step-by-step explanation:
The physicist who used diffraction to demonstrate that light was a wave and had an experiment named after him that he probably never performed himself is Thomas Young. In 1801, Young, an English physicist and physician, conducted the now-classic double-slit experiment which gave definitive proof of the wave character of light. While Christiaan Huygens had earlier proposed the wave nature of light, his principle was not considered conclusive evidence. It was only after Young's experiment that the wave theory of light gained widespread acceptance, contrasting the particle theory of light advocated by Isaac Newton. Moreover, the discovery of diffraction patterns from X-ray scattering by crystals by Max von Laue, and the electron diffraction experiments performed by Clinton J. Davisson, Lester H. Germer, and G. P. Thomson, further corroborated the wave-like properties of not just light, but other forms of electromagnetic and matter waves.
The physicist who used diffraction to demonstrate that light was a wave and has an experiment named after him is:
Thomas Young
Young's double-slit experiment, performed in the early 19th century, provided strong evidence for the wave nature of light. The experiment demonstrated interference patterns, which could only be explained by considering light as a wave. The experiment is often referred to as Young's experiment, and it played a crucial role in the development of the wave theory of light.