Max Planck

Theoretical physicist — Max Karl Ernst Ludwig Planck (1858–1947) was a German theoretical physicist, born in Kiel and active for most of his career in Berlin. Studying the blackbody spectrum, in 1900 he introduced the revolutionary hypothesis that energy is emitted and absorbed in discrete packets, quanta, of value $E=h\nu$: thus quantum physics was born. This idea, which he himself long regarded as a mathematical device, paved the way for the work of Einstein, Bohr and Heisenberg and radically changed twentieth-century physics. He received the Nobel Prize in Physics in 1918. He was also a moral figure of reference for German science, which he tried to defend during the Nazi regime.

Fun fact

His life was marked by family tragedies: his son Erwin was executed by the Nazis in 1945 for involvement in the plot against Hitler.

Theories and contributions

• Energy quantum — Radiation energy is emitted and absorbed in discrete packets proportional to frequency: $E = h\nu$.
• Planck’s law of the blackbody — Describes the spectral energy density of blackbody radiation: $u(\nu,T)=\dfrac{8\pi h\nu^3}{c^3}\dfrac{1}{e^{h\nu/kT}-1}$.
• Planck constant — Fundamental constant of nature $h \approx 6{.}626\times10^{-34}\,\mathrm{J\,s}$, which sets the scale of quantum phenomena.

Present in chapters

00 00a 21

Linked atoms

9 linked atoms.

00 Grandezze fisiche, stime, equilibrio

• What is a physical quantity

00a Come usare il sito

• Quick reference

21 Introduzione alla meccanica quantistica

• The four great themes of quantum mechanics
• The ultraviolet catastrophe
• Planck’s hypothesis
• The photon
• De Broglie’s hypothesis
• The historic photoelectric effect experiment
• The four pillars: a single structure