The story
Named for Max Planck (1858–1947), German theoretical physicist, who discovered it in 1900.
Etymology from Wiktionary, CC BY-SA 4.0.
Planck's constant
Today it means: the constant of proportionality (symbol ℎ), relating the energy and frequency of a photon (6.626×10⁻³⁴ joule-second); also related to the indeterminacy limit in the Heisenberg uncertainty principle; the quantum of action Full definition →