Thomas Young’s double-slit experiment with light produced alternating bright and dark bands through interference. Light passing through two narrow openings spread out, and the overlapping waves reinforced or canceled one another at different locations.
Young presented this evidence in 1801 and used it to support the wave theory of light. Bright bands formed where the waves arrived in phase, while dark bands formed where their phases differed so that the amplitudes canceled. The pattern could be observed even though neither slit alone produced such a series of fringes.
The experiment challenged Isaac Newton’s older corpuscular model, although the historical debate was not settled immediately. Later developments, including Maxwell’s electromagnetic theory and quantum mechanics, gave the result broader significance.
This is distinct from the modern electron double-slit experiment. Electrons are matter particles, yet they also build an interference pattern under suitable conditions, demonstrating wave-particle duality.