particle theory of light

The particle theory of light, also known as the photon theory, posits that light consists of discrete packets of energy called photons. This concept emerged from observations and theories in the early 20th century, notably Albert Einstein's explanation of the photoelectric effect in 1905.12

Historically, light was debated as either a wave or a particle. While Isaac Newton favored a particle model, Christiaan Huygens proposed a wave theory. By the late 19th century, light was widely accepted as an electromagnetic wave. However, phenomena like the photoelectric effect and the Compton effect demonstrated that light also exhibits particle-like behavior.3452

This led to the concept of wave-particle duality, where light, and indeed all matter, possesses both wave and particle characteristics. Quantum mechanics provides the framework for understanding this duality, describing particles not with definite trajectories but with wave functions that indicate probabilities.564