Planck, Max (1858-1947)

proposed the quantum theory in 1900 to explain how radiant energy (such as light) is given off and absorbed. The quantum theory completely revolutionized modern physics. It answered many questions and solved many problems that had puzzled scientists for years. For his work with the quantum theory, Planck won the Nobel Prize in physics in 1918. The basic concept of the quantum theory is that radiant energy, such as light, is a continuous stream of tiny packets of energy called quanta (or quantum in the singular). A quantum is the smallest amount of energy possible. Mathematically, the energy in a quantum is measured as the frequency of the radiation, V, times a universal constant, h. This constant value is also known as Planck's constant. Planck's formula applies to all forms of radiant energy, including ultraviolet light, X rays, radio waves, microwaves, and so on. An obvious conclusion that can be drawn from Planck's theory (and formula) is that forms of radiant energy with high frequencies have higher energy than those with lower frequencies. Planck proposed his theory to solve a particular experimental problem. He never expected it to become the basic principle of a new kind of physics. But this is exactly what happened. Albert Einstein and Niels Bohr quickly adopted Planck's ideas and extended them to many areas of physics. Einstein used the quantum theory to explain the photoelectric effect Bohr used the theory to explain how electrons in the outer shells of their atoms give off light energy without falling back into the nucleus. He theorized that electrons give off energy in limited bursts of quanta-not continuously.
Max Planck was born in Kiel, a city in north - western Germany, in 1858. He studied at the universities of Munich and Berlin with the great German scientists Hermann Helmholtz and Gustav Kirchhoff. Planck received a Ph.D. in physics and began teaching physics at the university level. He taught at the University of Berlin for most of his career. Planck served in many scientific associations, including the Prussian Academy of Science and the Kaiser Wilhelm Society of Berlin (later renamed the Max Planck Society). He was also made a foreign member of the Royal Society of London. Planck enjoyed a wide range of interests outside of physics, including music, religion, and philosophy. He was also deeply concerned about justice. Planck stayed in Germany during the Nazi regime because he felt his duty to do so. But his family suffered terribly. In 1944 his son Erwin was arrested and executed for alleged participation in the plot to assassinate Hitler. Planck remained in Germany after World War II. He died in 1947.