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Max Planck (1858-1947), German physicist, reading at his desk. Max Karl Ernst Ludwig Planck pioneered the quantum theories that revolutionized classical physics. His 1900 paper, describing black body radiation, proposed that radiation must be emitted or received in energy packets (quanta), rather than continuously. Quantum theory grew in acceptance after its use in explaining the photoelectric effect (Einstein, 1905) and the electronic structure of atoms (Bohr, 1913). Planck received the 1918 Nobel Prize in Physics for his work.
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