Max Karl Ernst Ludwig Planck (23.04.1858 —4.10.1947) — a German theoretical physicist,
the founder of quantum theory, a member of the Berlin Academy of Sciences (1894) and its permanent secretary
in 1912 — 38. He was born in Kiel. He graduated from the University of Munich (1878), where in 1879 he received the degree of Doctor of Philosophy. In 1880 — 85 he worked at the University of Munich, in 1885 —88 he was professor of theoretical physics at the University of Kiel, and in 1889 — 26 at the University of Berlin.
His work was in the fields of thermodynamics, the theory of thermal radiation, relativity, quantum theory, the history and methodology of physics, and the philosophy of science. In 1900, starting from an assumption alien to classical physics, that atomic oscillators emit energy only in definite portions, quanta, the energy of a quantum being proportional to the frequency of oscillation (the quantum hypothesis), he derived the law of the distribution of energy in the spectrum of a black body. He introduced a fundamental constant (the Planck constant) with the dimension of action. The formula of Planck's law received experimental confirmation at once. Assessing the significance of Planck's discovery, A. Einstein wrote: “It was Planck's radiation law that gave the first exact determination of the absolute magnitudes of atoms, independently of other proposals. More than that, it showed convincingly that, besides the atomistic structure of matter, there is a kind of atomistic structure of energy, governed by the universal constant introduced by Planck. This discovery became the basis of all research in twentieth-century physics. And from that time it has almost completely determined its development. Without this discovery it would have been impossible to establish a true theory of molecules and atoms and of the energy processes that govern their transformations. More than that, it shattered the framework of classical mechanics and electrodynamics and set science the task of finding a new cognitive basis for all of physics.”
The Planck constant, or quantum of action, is one of the universal constants of physics. The day of 14 December 1900, when Planck reported to the German Physical Society the theoretical derivation of the radiation law, became the birth date of quantum theory (Nobel Prize, 1918). However, although Planck's radiation formula was accepted as describing the experimental facts simply and adequately, the theory Planck proposed as the foundation of this formula did not attract the attention of scientists until 1905, when A. Einstein used the revolutionary idea of quanta, extending it to the process of emission itself, and predicted the photon.
Planck's work on relativity was of great importance. He was one of the first to understand it, accept it and support it resolutely. In 1906 he derived the equations of relativistic dynamics, obtaining expressions for the energy and momentum of the electron, and so completed the relativisation of classical mechanics. He also introduced the term “theory of relativity” (1906). In 1907 he generalised thermodynamics within the framework of the special theory of relativity.
He gave a general derivation of the laws of chemical equilibrium in gases and dilute solutions (1887).
In solving concrete scientific problems he stood on materialist positions: he spoke out against the “energeticists” in defence of L. Boltzmann, pointing out that they misunderstood the real meaning of the second law of thermodynamics, criticised E. Mach in defence of atomism, and fought the later currents of positivism. In general, however, he could not rise above contemplative materialism. Planck's active struggle against physical idealism at the turn of the 19th and 20th centuries played an important part in the history of the development of knowledge.
A foreign member of the USSR Academy of Sciences (1926) and of the Royal Society (1926). A scientific society in the Federal Republic of Germany is named after Planck. The German Physical Society established the M. Planck Medal.