Used with
permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA,
http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps
Max Planck (1858-1947) solved the dilemma of describing accurately the frequency distribution of radiation from a black body, a problem that had been approached from both the high (Wien) and low (Rayleigh) frequency ends, but with no apparent smooth overlap. Planck postulated that electromagnetic energy was not infinitely divisible, but existed in particles, or quanta, proportional to the frequency of the radiation. The Planck constant, h, in the exponent of the black body spectral distribution equation tamed the ultraviolet catastrophy to produce distribution curves such as shown in the Fraunhofer stamp of radiation from the sun. Planck received the 1918 Nobel prize in physics, and Einstein and Bohr applied quantum theory to the photoelectric effect and atomic structure, explaining away some baffling paradoxes of classical physics. The German stamp shows a black body emitting a quantized amount of energy, while the spectrum of this radiation appears continuous to the eye. Planck's constant also commemorates the anniversary of his death in 1947.