By the seventeenth century, although many physicists had already advocated the wave theory of light, which held that light was incident by waves, Newton's corpuscular theory, which described light as a particle, was well accepted in the scientific community.
In 1801, the English physicist and physician Thomas Young was the first to demonstrate, with solid experimental results, the phenomenon of light interference, which results in the acceptance of the wave theory. Although the accepted theory today is wave-particle duality, as enunciated by French physicist Louis-Victor de Broglie, based on Albert Einstein's conclusions on the characteristics of photons.
In Young's experiment, three screens are used, the first one consisting of a hole where diffraction of the incident light occurs, the second with two holes, side by side, causing new diffraction. In the latter, the spots caused by the interference of the waves resulting from the second diffraction are projected.
By replacing these holes with very narrow slits, the spots become fringed, making it easier to see better lit regions (maximum) and poorly lit regions (minimum).
It is observed that the highest intensity occurs in the center, and after this maximum, there are regions of lower light intensity, and others of minimum, interspersing.