Max Planck won the 1918 Nobel Prize in Physics for originating the theory of energy quanta. He proposed that matter exchanges energy in discrete packets rather than in an entirely continuous flow.
Planck introduced the idea in 1900 while studying the spectrum of thermal radiation emitted by hot objects. To match experimental measurements, he used a constant now called the Planck constant, written as h. The relation E = hν links a quantum’s energy with the frequency of radiation.
Planck initially treated quantization as a mathematical solution to the black-body radiation problem, but the idea became a foundation of quantum theory. Albert Einstein later applied the concept to light itself when explaining the photoelectric effect, work recognized by his 1921 Physics Nobel.
Planck’s prize was awarded in 1918 but presented in 1919. The delay reflected the disruption caused by the First World War. The Planck constant remains one of the defining constants of modern physics.