Max Karl Ernst Ludwig Planck (1858-1947), a German physicist who played a vital role in the development of quantum theory. Planck’s study of the distribution of energy in the electromagnetic spectrum led him to deduce the relationship between the energy and the frequency of radiation. In a paper published in 1900, he announced his derivation; it was based on the revolutionary idea that the energy emitted by a resonator could only take on discrete values or quanta. The energy for a resonator of frequency v is hv where h is a universal constant, now called Planck's constant. Planck’s work marked a turning point in the history of physics and influenced a wide spectrum of subsequent work, including Einstein's explanations of the photoelectric effect. Planck was awarded the Nobel Prize in Physics in 1918.