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ScienceWeek
- In Focus
On Pascual Jordan and Nazi Physics
The individual human brain is an extremely complex natural system, and the individual human mind, the manifestation of the dynamics of that system, is at least of an equal order of complexity and also a domain where paradox is commonplace. (Ernst) Pascual Jordan (1902-1980) was one of the great theoretical physicists of this century, the principal architect of the Born-Heisenberg-Jordan matrix quantum mechanics (see Note #1 below), the essential inventor of *quantum field theory, and a 20th century tour de force in mathematical physics -- but he was also an ardent Nazi storm trooper, "complete with brown uniform, jackboots, and swastika armband..." And if that paradox is not enough, add to it the fact that Jordan not only defended the physics of Albert Einstein to the Nazi regime which despised Einstein because Einstein was a Jew, but also devoted considerable effort to developing the details of Einstein's general theory of relativity.
Engelbert L. Schucking (New York University, US), theoretical physicist and a former student of Pascual Jordan (beginning in 1952), presents a biographical essay on Jordan, with Schucking making the following points (Physics Today October 1999):
1) Pascual Jordan was the originator of the quantum theory of fields, "which we now take to be the basis of all physics." He was the first to realize that all things in the Universe -- photons, electrons, protons, atoms, and elephants -- are field quanta. Of the triumvirate Pascual Jordan, *Max Born, and *Werner Heisenberg that formulated matrix quantum mechanics in 1925, Jordan was the principal architect of the theory. But in spite of his revolutionary contributions, Jordan never achieved the acclaim of his colleagues Heisenberg and *Wolfgang Pauli, perhaps because Jordan was looked down upon by Pauli and Heisenberg as more of a mathematician than a physicist.
2) Schucking points out that Jordan also made the first formulation of what is now called *Fermi-Dirac statistics. The story is that in 1925 Max Born, who was then editor of the Zeitschrift fur Physik was given a paper by Jordan for publication in the journal. Born put the paper in his briefcase and then left for the US to give lectures at MIT. Born forgot about the paper, and when he returned to Germany six months later, he found the paper at the bottom of the suitcase. According to Max Born: "It contained what came to be known as the Fermi-Dirac statistics. In the meantime, it had been discovered by Enrico Fermi and, independently, by Paul Dirac. But Jordan was the first."
3) In May 1933, Jordan joined the Nazi party. But even before the Nazis came to power in January 1933, Jordan had been a conservative nationalist, and under the pseudonym "Domeier" he had published his elitist views in the right-wing journal Deutsches Volkstum (German Heritage). In November 1933, Jordan joined an SA (Sturmabteilung) unit and became a storm trooper. He volunteered for the Luftwaffe in 1939, worked mostly as a meteorologist at airfields, and also at the notorious Peenemunde rocket center. In 1953, thanks to the intercession of Wolfgang Pauli, Jordan was "rehabilitated" and advanced from visiting to full professor at the University of Hamburg.
4) The Schucking article includes an amusing extract from a play by *Bertolt Brecht (Fright and Misery in the Third Reich) in which Brecht satirizes Nazi physics in a scene in which two physicists execute tortuous verbalizations in an attempt to avoid mentioning the dangerous "E-word" (Einstein). In fact, most German physicists, when writing about relativity during the Nazi era, shunned the dangerous E-word. Schucking notes: "A circumspect Heisenberg managed to avoid it." Jordan, however, did use Einstein's name when writing about relativity.
5) Schucking notes that the contributions of Pascual Jordan are for the most part still widely unknown. "The bulk of the monumental 1925 Born-Jordan paper 'Zur Quantenmechanik' was written by Jordan [*Note #1]." It has also been argued that Jordan's habilitation lecture was crucial for Heisenberg's discovery of the uncertainty principle. "Even Jordan's pioneering work in quantum field theory was not immediately appreciated. His formalism of *creation and annihilation operators, now the basic language of physics, was still viewed with suspicion by Pauli in 1933." In a seminal paper in 1935, Jordan showed how his formalism could treat the physics of multiparticle systems -- now the standard treatment in condensed matter physics -- and generate the representations that are now used in particle physics.
6) In 1979, *Eugene Wigner proposed Jordan for the Nobel Prize in Physics, but the Swedish Academy awarded the prize that year to *Sheldon Glashow, Abdus Salam, and Steven Weinberg -- according to Schucking, "three practitioners of the art that Jordan had invented." Less than a year later, Jordan died at the age of 78 while filling in formulae in a manuscript at his kitchen table.
Physics Today http://www.physicstoday.org
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Notes by ScienceWeek:
The 1997 edition of Chambers Biographical Dictionary contains a short paragraph on "(Ernst) Pascual Jordan (1902- ) German theoretical physicist". Evidently, 17 years after Jordan's death, the editors of the dictionary were not aware of it. Several current popular biographical dictionaries of scientists contain no mention of Pascual Jordan at all. David Bohm's 1951 textbook Quantum Theory does not mention Jordan at all. The 1958 4th edition of Paul Dirac's The Principles of Quantum Mechanics does not mention Jordan at all. Jordan is also not mentioned anywhere in Richard Feynman's Lectures on Physics (1965). Additional note: Pascual Jordan (1902-1980) should not be confused with the noted mathematician Camille Jordan (1838-1922). Camille Jordan was the foremost specialist in algebra of his time, publishing research in topology, analysis, and particularly in group theory. The so-called "Jordan curve" in analysis is the curve of Camille Jordan.
quantum field theory: The mathematical fusion of quantum mechanics with special relativity theory. It is now the overall theory of fundamental particles and their interactions, with each type of particle represented by appropriate operators which obey specific algebraic commutation laws.
Max Born: (1882-1970) Nobel Prize in Physics 1954. Born did fundamental work in quantum theory, particularly work linking the wave function of the electron to electron distribution probability. It was Born who apparently coined the term "quantum mechanics". Heisenberg was one of Born's students.
Werner Heisenberg: (1901-1976) Nobel Prize in Physics 1932. Developed quantum theory (matrix quantum mechanics) and formulated the uncertainty principle, which concerns matter, radiation, and their reactions, and which places absolute limits on the achievable accuracy of measurement of physical phenomena in the quantum domain.
Wolfgang Pauli: (1900-1958) Nobel Prize in Physics 1945. Originated the exclusion principle, which states that in a given system no two fermions (electrons, protons, neutrons, or other elementary particles of half-integral spin) can be characterized by the same set of quantum numbers. He also predicted the existence of neutrinos.
Fermi-Dirac statistics: The statistics of an assembly of identical half-integer spin particles. Such particles satisfy the Pauli exclusion principle, i.e., no two particles of the same kind in the system may simultaneously occupy the same quantum state.
Bertolt Brecht: (1898-1956) Considered by many to be Germany's greatest dramatist, Brecht presented his plays as instruments of sociological analysis. When Hitler came to power in 1933, Brecht left Germany and in 1941 finally settled in Hollywood (US). The play in question, Fright and Misery under the Third Reich, is also called Fear and Loathing under the Third Reich (Furcht und Elend des dritten Reiches, 1945). In 1948, Brecht moved to East Berlin to direct a theater. Always in conflict with bureaucratic authority, Brecht's years in East Germany proved difficult for both himself and the communist East German government.
Note #1: What is known as "Heisenberg's matrix mechanics" (matrix quantum mechanics) is a particular formulation of quantum mechanics in which the vector aspect of quantum theory is emphasized, whereas the wave aspects of quantum phenomena play a secondary role. Although wave quantum mechanics (subsequently developed by Schroedinger, see below) and matrix quantum mechanics appear superficially to be very different, the two theories are in fact completely equivalent and lead to the same physical predictions. Werner Heisenberg's first paper on the subject appeared in 1925, and in this paper matrix theory is not mentioned explicitly because Heisenberg did not realize yet that his mathematical operations had a matrix theory interpretation. The connection with matrix theory was demonstrated the same year in the already mentioned important paper by Max Born and Pascual Jordan (Z. fur Physik 1925 34:858). In a second paper a short time later, Born and Jordan and Heisenberg all published together and clarified the principles of matrix quantum mechanics (Z. fur Physik 1926 35:557). The wave quantum mechanics of Erwin Schroedinger was not published until 1926 (Annalen der Physik 1926 79:361), so that historically matrix mechanics was invented and developed before Schroedinger invented wave mechanics. Given wave mechanics, the invention of matrix mechanics might be viewed as inevitable, since the set of all solutions of a linear differential equation can be regarded as a vector space. The fact that matrix mechanics was invented without wave mechanics is considered by some physicists to be an astounding theoretical accomplishment.
creation and annihilation operators: These are quantum mechanical operators which increase or reduce, respectively, the occupation of a single quantum state by one. For example, an annihilation operator applied to a state of one particle yields the vacuum. In this context, "operators" are abstract representations of certain specific mathematical operations, and consideration of the various algebras of such operators has proved to be of immense importance in theoretical physics.
Eugene Wigner: (1902-1995) He introduced the idea of parity, or symmetry theory, into nuclear physics. He shared the 1963 Nobel Prize for Physics with Maria Goeppert-Mayer (1906-1972) and Hans Jensen (1907-1973).
Sheldon Glashow, Abdus Salam, and Steven Weinberg: Shared the 1979 Nobel Prize in Physics for the unified theory of weak and electromagnetic fundamental forces, and for the prediction of the existence of the weak neutral current. Abdus Salam (1926-1996).
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