Max Planck

Max Planck was a German theoretical physicist whose 1900 explanation of blackbody radiation introduced energy quantization and founded quantum theory.

Heinrich Hertz: German physicist whose experiments demonstrated electromagnetic waves and helped establish classical electrodynamics. Hertz’s measurements of blackbody radiation helped frame the problem Planck tried to solve.
Blackbody radiation: Electromagnetic radiation emitted by an ideal absorber in thermal equilibrium, with a spectrum determined by temperature. Its measured spectrum was the phenomenon Planck’s formula explained.
Thermodynamics: The study of heat, work, temperature, and energy transformations in macroscopic systems. Planck approached radiation through thermodynamic principles rather than a mechanical model of light.
Quantum theory: The body of physical theories describing matter and energy through quantized states and probabilistic rules. Planck’s radiation hypothesis marked the beginning of this broader theoretical tradition.
Max Planck Society: A German organization that supports basic research through a network of independent institutes. The society adopted Planck’s name as the successor to the research organization he once led.
Wilhelm Wien: German physicist who formulated a displacement law and an approximate radiation law for blackbodies. Wien’s radiation law was an essential predecessor that Planck’s formula extended.
Planck's law: The formula giving the spectral distribution of electromagnetic radiation emitted by a blackbody at a given temperature. This is the precise radiation formula Planck derived to match observations across wavelengths.
Entropy: A thermodynamic state function measuring energy dispersal and the number of microscopic arrangements compatible with a state. Planck used entropy to connect radiation laws with the behavior of resonators.
Photoelectric effect: The emission of electrons from a material when it absorbs light of sufficient frequency. Einstein used Planck’s energy quantum to explain why light frequency controls electron emission.
Planck units: A system of natural units defined from fundamental constants, including Planck’s constant. The units carry Planck’s name and connect his constant to scales of nature.

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