Planck
NAME: Planck, Max
ACHIEVEMENT(S): Planck’s constant
NICKNAME/ALIAS: born Max Karl Ernst Ludwig Planck
DATE/PLACE OF BIRTH: 23 April 1858, at Kiel, Germany
DATE/PLACE/AGE AT DEATH: 3 October 1947, in Gottingen, Germany. Aged 89
DISCIPLINE: Physicist
FIELD: Theoretical physics
LANGUAGE: German
PARENTS: Johann Julius Wilhelm von Planck and Emma Patzig
SIBLINGS: Two elder half-siblings; three elder siblings
SPOUSE: Marie Merck (d. 1909), married 1885; Marga von Hoesslin, married
1911
CHILDREN: Karl (d. 1916), Margarete (d. 1917), Emma (d. 1919) and Erwin (d.
1945) by first marriage; one son by second marriage
EDUCATION: Konigliche Maximilian Gymnasium, 1867-74; University of Munich,
1874-75; University of Berlin, 1877 and 1878; University of Munich, 1878-79
MAJOR WORK: 'Vorlesungen uber die Theorie der Warmestrahlung', 1906
LIFE AND TIMES:
At the University of Berlin Planck studied under the eminent <taught by> Helmholtz* and <taught by> Kirchhoff*, and made an independent study of <studied work of> Clausius'* work on thermodynamics, the science that deals with heat, mechanical energy, and energy transformations on the basis of a few fundamental laws. In 1878, Planck returned to Munich, and in 1879, he took a Ph.D.
Between 1880 and 1892, Planck carried out a systematic study of thermodynamic principles, especially in relation to chemical phenomena such as osmotic pressure, boiling and freezing points of solutions, and the dissociation of gases.
In 1885 he became extraordinary professor of theoretical physics at the University of Kiel, and his research in thermodynamics and its application to physical chemistry and
electrochemistry soon earned him international recognition within the scientific community. On Kirchhoff's death in 1887 Planck was appointed professor at the University of Berlin and director of the newly-founded Institute for Theoretical Physics (1888).
Planck soon became involved in the problem of black body radiation. In 1862, Kirchhoff had introduced, as an ideal standard for measurement and theoretical investigation, the idea of a perfect black body that would absorb all frequencies of radiation when heated, would give off all frequencies of radiation as it cools, and would reflect none. Radiation from such a body therefore would depend only on its temperature.
From 1862, Kirchhoff and others began investigating the nature of the thermal radiation emitted by black bodies, searching for a mathematical law that would describe the way in which a black body radiates heat. However, the problem proved highly complex, because black bodies do not give off heat in the way that scientists had predicted.
Progress was made in 1879, with <work related to> Stefan's* discovery that the total energy emitted is proportional to the fourth power of the absolute temperature (theoretically explained by <work related to> Boltzmann* as applying only to perfect black bodies in 1884, verified in 1896 by the German physicists <work related to> Pringsheim* and Otto Lummer, and now known as the Stefan-Boltzmann Law).
Also, by the early 1890s black-body experiments had shown that a graph of energy versus frequency or wavelength is a characteristic curve which retains its shape as the
temperature is raised but shifts towards higher frequencies.
In 1896, Planck began working on the problem of black-body radiation, and by 1900, had come to the revolutionary assumption that the energy radiated by a black body is carried away in separate "packages", or 'quanta' (from the Latin 'quantum', for "an amount"). This concept was revolutionary because physicists had long believed that energy was always transmitted in some continuous form, such as a wave, whereas Planck's suggestion was that the heat energy radiated by a black body should be regarded as a stream of a finite number of separate units of energy (quanta), the size of which is a function of the wavelength of the radiation.
His mathematical expression of this concept was E = hvwhere v is the frequency of the radiation and h is a constant (now recognized to be a fundamental constant of nature, and generally known as Planck's constant).
By directly relating the energy of a radiation to its frequency, Planck had found an explanation for the observation that radiation of greater energy has a higher frequency distribution. His discovery was important because it made possible, for the first time, the use of matter-related concepts in an analysis of phenomena involving energy, the concept
constituting the birth of quantum theory and marking a revolution in physics.
After completing his study of black body radiation, Planck turned his attention to another new and important field of physics, relativity. <a supporter of> Einstein's* paper on theory of general relativity was published in 1905, and subsequently Planck, the first prominent physicist to champion Einstein's special theory of relativity, tried successfully to incorporate his quantum concept into Einstein's new system.
In particular, he extended Einstein's arguments from the field of electromagnetism to that of mechanics. Meanwhile, also in 1905, Einstein published a paper in which he made the
first productive use of the quantum concept when he used the idea of light quanta, or photons, to explain the photoelectric effect (the ejection of electrons from a metal surface irradiated by ultraviolet rays).
Then in 1907 Einstein showed the generality of the quantum hypothesis by using it to interpret the temperature dependence of the specific heats of solids. In 1909, Einstein introduced the wave-particle duality into physics, and then in 1913 <theory applied by> Bohr* applied the quantum theory to the atom, and evidence was at last found concerning the behaviour of electrons in the atom.
This was later developed into a full system of quantum mechanics (the complex mathematical treatment of quantum theory) in the 1920s, by <theory developed by> Schrodinger*, <theory developed by> Born*, <theory developed by> Heisenberg*, <theory developed by> Dirac* and others, when it also became clear that energy and matter have both a particle and wave nature.
In recognition of his achievement, in 1919 Planck was awarded the 1918 Nobel Prize for physics. In 1914 Planck and <work related to> Nernst* succeeded in bringing Einstein to Berlin, and after the war, in 1919, arrangements were made for <taught> Laue*, Planck's favourite student, to come to Berlin too.
When Planck retired in 1928, at the age of 70, another prominent theoretical physicist, Schrodinger, the originator of wave mechanics, was chosen as his successor.
ASSESSMENT: The theoretical physicist who formulated the quantum theory which revolutionized physics.
EXTRA CONNECTIONS: His work related to that of <work related to> De Broglie* and <work related to> Lenard*.
<a colleague was> Ostwald* was a colleague.
ONELINER: Max Planck, quantum physics pioneer
BIBLIOGRAPHY:
DSB, EB,
Biog Dictionary of Physicists
Notable Twentieth-Century Scientists
Weber, Robert L., Pioneers of Science: Nobel Prize Winners in Physics, American Institute of Physics, 1980