The concept of wave-particle duality is a fundamental principle in quantum mechanics, which states that quantum entities, such as light and matter, exhibit both wave and particle properties depending on the experimental circumstances.
The wave-particle duality of light and matter has a long and complex history. Sir Isaac Newton advocated for the corpuscular theory of light, while Christiaan Huygens proposed the wave theory of light. Experiments by J. J. Thomson, Robert Millikan, and Charles Wilson showed that free electrons had particle properties, while Louis de Broglie’s theory of electron waves in 1924 proposed that electrons and all matter could be considered as waves.