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Austrian–Swiss physicist (1900–1958)
Born in the Austrian capital of Vienna, Pauli was the son of a professor of physical chemistry at the university there and the godson of Ernst Mach. He was educated at the University of Munich, where he obtained his PhD in 1922. After further study in Copenhagen with Niels Bohr and at Göttingen with Max Born, Pauli taught at Heidelberg before accepting the professorship of physics at the Federal Institute of Technology, Zurich. Apart from the war years, which he spent working in America at the Institute of Advanced Studies, Princeton, he remained there until his early death in 1958.
Pauli was a physicist much respected by his colleagues for his deep insight into the newly emerging quantum theory. His initial reputation was made in relativity theory with his publication in 1921 of his Relativitätstheorie (Theory of Relativity). His name is mainly linked with two substantial achievements. The first, formulated in 1924, is known as the Pauli exclusion principle. It follows from this that as an electron can spin in only two ways each quantum orbit can hold no more than two electrons. Once both vacancies are full further electrons can fit only into other orbits. With this principle the distribution of orbital electrons at last became clear, that is, they could be explained and predicted in purely quantum terms.
The early model of the atom by Niels Bohr had been extended by Arnold Sommerfeld in 1915. In the Bohr–Sommerfeld atom, each electron orbiting the nucleus had three quantum numbers: n, l, and m. Pauli introduced a fourth quantum number (s), which could have values of +1/2 or –1/2 and corresponded to possible values of the ‘spin’ of the electron. Pauli's exclusion principle stated that no two electrons in an atom could have the same four quantum numbers (n, l, m, and s). The concept of electron spin was verified in 1926 by Samuel Goudsmit and George Uhlenbek. The exclusion principle explained many aspects of atomic behavior, including the spectral effects discovered by Pieter Zeeman. It has also been applied to other particles. It was for his introduction of the exclusion principle that Pauli was awarded the 1945 Nobel Prize for physics.
Pauli's second great insight was in resolving a problem in beta decay – a type of radioactivity in which electrons are emitted by the atomic nucleus. It was found that the energies of the electrons covered a continuous range up to a maximum value. The difficulty was in reconciling this with the law of conservation of energy; specifically, what happened to the ‘missing’ energy when the electrons had lower energies than the maximum? In 1930, in a letter to Lise Meitner, Pauli suggested that an emitted electron was accompanied by a neutral particle that carried the excess energy. Enrico Fermi suggested the name ‘neutrino’ for this particle, which was first observed in 1953 by Frederick Reines.
| Biography: Wolfgang Ernst Pauli |
The Austrian theoretical physicist Wolfgang Ernst Pauli (1900-1958) was awarded the Nobel Prize in Physics for his discovery of the exclusion principle, known as the Pauli principle.
Wolfgang Pauli the son of Wolfgang Joseph Pauli, a professor in the University of Vienna, was born in that city on April 25, 1900. Brilliant at school, he studied theoretical physics in the University of Munich under Arnold Sommerfeld (1918-1921) and graduated as a Doctor of Philosophy. Sommerfeld asked him to write the article on relativity for the Encyclopedia of Mathematical Sciences. The article, over 200 pages long, was published in 1921; it was translated into English and Italian in 1958 and is still definitive.
Pauli was an assistant to Max Born at Göttingen (1921-1922) and to Niels Bohr at Copenhagen (1922-1923). He then spent 5 years as a lecturer in the University of Hamburg, and in 1928 he became professor of physics in the Federal Institute of Technology at Zurich.
In 1921 the generally accepted theory of the atom was that advanced by Bohr in 1913. In the case of the hydrogen atom with its single electron, the state of the atom was defined by a single quantum number representing the energy in the possible circular orbits of the electron. By postulating an additional set of quantum numbers Sommerfeld later extended Bohr's theory to cover the elliptical orbits in complex atoms, and a third set was later postulated to explain the atom in a magnetic field. The Bohr-Sommerfeld theory explained the hydrogen atom satisfactorily; but in the case of complex atoms it did not explain the doublet nature of the series of the alkali spectra, nor did it explain the anomalous Zeeman effect which Pauli had tried to elucidate while he was at Copenhagen.
In 1924-1925 Pauli published his theoretical solution of the anomalous Zeeman effect. To explain it, others had suggested that the third, or magnetic, quantum number should be regarded as having a half-integer value. But Pauli postulated a fourth quantum number, a fourth degree of freedom. This he regarded as having one of two values only - a property he later defined as "two-valuedness not describable classically." He then defined his "principle," which is now usually stated as follows: no two electrons in the same atom can have all four quantum numbers equal. Recognized from the time of its publication as important, it was not at once called the exclusion, or Pauli, principle. In 1925 G. E. Uhlenbeck and S. A. Goudsmit introduced the hypothesis of electron spin, with possible quantum numbers of either + ½ or -½. About this time the new mechanics, as exemplified by Werner Heisenberg's matrix mechanics and Erwin Schrödinger's wave equation, was making headway, but these methods did not easily explain the problem of the hydrogen atom because it involved the inverse-square law in the attractive force. In 1926 Pauli solved this problem brilliantly by identifying his hypothetical fourth degree of freedom with Uhlenbeck and Goudsmit's "spin," and since then this degree has been called the spin quantum.
Between 1928 and 1930 Pauli first attempted - partly in collaboration with Heisenberg - to apply the quantum principle to the interaction of radiation and matter. These three papers constituted the first steps in quantum field theory. In the early 1930s, to explain the phenomenon of beta decay of nuclei, by which an unpredictable amount of energy appeared to be lost, Pauli postulated the existence of a neutral particle of low mass but with spin ½ For this particle Enrico Fermi later coined the name "neutrino."
Pauli was visiting professor at the University of Michigan (1931, 1941) and at the Institute for Advanced Study, Princeton (1935-1936, 1940-1945). He received many honors, including the Nobel Prize for Physics in 1945. In 1953 he was elected a Foreign Member of the Royal Society. He died in Zurich on Dec. 15, 1958.
Further Reading
There is a biography of Pauli in Nobel Lectures, Physics, 1942-1962 (1964), which also includes his Nobel Lecture. For his work see N. H. de V. Heathcote, Nobel Prize Winners, Physics, 1901-1950 (1953); B. Hoffmann, The Strange Story of the Quantum (2d ed. 1959); and A. d'Abro, The Rise of the New Physics, vol. 2 (1951).
| Columbia Encyclopedia: Wolfgang Pauli |
| Wikipedia: Wolfgang Pauli |
| Wolfgang Pauli | |
|---|---|
| Born | Wolfgang Ernst Pauli 25 April 1900 Vienna, Austria-Hungary |
| Died | 15 December 1958 (aged 58) Zürich, Switzerland |
| Citizenship | Switzerland |
| Nationality | Austria |
| Fields | Physics |
| Institutions | University of Göttingen University of Copenhagen University of Hamburg ETH Zürich Princeton University |
| Alma mater | Ludwig-Maximilians University |
| Doctoral advisor | Arnold Sommerfeld |
| Other academic advisors | Max Born |
| Doctoral students | Nicholas Kemmer Felix Villars |
| Other notable students | Sigurd Zienau |
| Known for | Pauli exclusion principle Pauli-Villars regularization Pauli matrices Pauli effect Pauli equation Pauli group Coining 'not even wrong' |
| Influences | Ernst Mach Carl Jung |
| Influenced | Ralph Kronig |
| Notable awards | Lorentz Medal (1931) Nobel Prize in Physics (1945) Matteucci Medal (1956) Max Planck Medal (1958) |
| Religious stance | Roman Catholic |
|
Notes
His godfather was Ernst Mach. He is not to be confused with Wolfgang Paul, who Pauli called his 'real part.' |
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Wolfgang Ernst Pauli (April 25, 1900 – December 15, 1958) was an Austrian theoretical physicist and one of the pioneers of quantum physics. In 1945, after being nominated by Albert Einstein, he received the Nobel Prize in Physics for his "decisive contribution through his discovery of a new law of Nature, the exclusion principle or Pauli principle," involving spin theory, underpinning the structure of matter and the whole of chemistry.
Contents |
Pauli was born in Vienna to a chemist Wolfgang Joseph Pauli (né Wolf Pascheles, 1869 - 1955) and the mother Berta Camilla Schütz. His middle name was given in honor of his godfather, the physicist Ernst Mach. His paternal grandparents were from prominent Jewish families of Prague, but his father converted from Judaism to Roman Catholicism shortly before his marriage in 1899. Bertha Schütz was raised in her mother's Roman Catholic religion, but her father was the Jewish writer Friedrich Schütz. Although Pauli was raised as a Roman Catholic, eventually he and his parents left the Church.[1]
Pauli attended the Döblinger-Gymnasium in Vienna, graduating with distinction in 1918. Only two months after graduation, the young prodigy published his first paper, on Albert Einstein's theory of general relativity. He attended the Ludwig-Maximilians University in Munich, working under Arnold Sommerfeld, where he received his PhD in July 1921 for his thesis on the quantum theory of ionized molecular hydrogen.
Sommerfeld asked Pauli to review the theory of relativity for the Encyklopaedie der mathematischen Wissenschaften (Encyclopedia of Mathematical Sciences). Two months after receiving his doctorate, Pauli completed the article, which came to 237 pages. It was praised by Einstein; published as a monograph, it remains a standard reference on the subject to this day.
Pauli spent a year at the University of Göttingen as the assistant to Max Born, and the following year at the Institute for Theoretical Physics in Copenhagen, which later became the Niels Bohr Institute in 1965. From 1923 to 1928, he was a lecturer at the University of Hamburg. During this period, Pauli was instrumental in the development of the modern theory of quantum mechanics. In particular, he formulated the exclusion principle and the theory of nonrelativistic spin.
At the end of 1930, shortly after his postulation of the neutrino and immediately following his divorce in November, Pauli had a severe breakdown. He consulted psychiatrist and psychotherapist Carl Jung who, like Pauli, lived near Zürich. Jung immediately began interpreting Pauli's deeply archetypal dreams,[2] and Pauli became one of the depth psychologist’s best students. Soon, he began to criticize the epistemology of Jung’s theory scientifically, and this contributed to a certain clarification of the latter’s thoughts, especially about the concept of synchronicity. A great deal of these discussions is documented in the Pauli/Jung letters, today published as Atom and Archetype. Jung's elaborate analysis of more than 400 of Pauli's dreams is documented in Psychology and Alchemy.
In 1928, he was appointed Professor of Theoretical Physics at ETH Zürich in Switzerland where he made significant scientific progress. He held visiting professorships at the University of Michigan in 1931, and the Institute for Advanced Study in Princeton in 1935. He was awarded the Lorentz Medal in 1931.
The German annexation of Austria in 1938 made him a German national, which became a difficulty with the outbreak of World War II in 1939. Pauli moved to the United States in 1940, where he was Professor of Theoretical Physics at Princeton. After the war, in 1946, he became a naturalized citizen of the United States, before returning to Zürich, where he mostly remained for the rest of his life.
In 1958, Pauli was awarded the Max Planck medal. In that same year, he fell ill with pancreatic cancer. When his last assistant, Charles Enz, visited him at the Rotkreuz hospital in Zürich, Pauli asked him: “Did you see the room number?” It was number 137. Throughout his life, Pauli had been preoccupied with the question of why the fine structure constant, a dimensionless fundamental constant, has a value nearly equal to 1/137. Pauli died in that room on 15 December 1958.
Pauli made many important contributions in his career as a physicist, primarily in the field of quantum mechanics. He seldom published papers, preferring lengthy correspondences with colleagues such as Niels Bohr and Werner Heisenberg, with whom he had close friendships. Many of his ideas and results were never published and appeared only in his letters, which were often copied and circulated by their recipients. Pauli was apparently unconcerned that much of his work thus went uncredited.
Pauli proposed in 1924 a new quantum degree of freedom (or quantum number) with two possible values, in order to resolve inconsistencies between observed molecular spectra and the developing theory of quantum mechanics. He formulated the Pauli exclusion principle, perhaps his most important work, which stated that no two electrons could exist in the same quantum state, identified by four quantum numbers including his new two-valued degree of freedom. The idea of spin originated with Ralph Kronig. George Uhlenbeck and Samuel Goudsmit one year later identified Pauli's new degree of freedom as electron spin.
In 1926, shortly after Heisenberg published the matrix theory of modern quantum mechanics, Pauli used it to derive the observed spectrum of the hydrogen atom. This result was important in securing credibility for Heisenberg's theory.
Pauli introduced the 2 × 2 Pauli matrices as a basis of spin operators, thus solving the nonrelativistic theory of spin. This work is sometimes said to have influenced Paul Dirac in his creation of the Dirac equation for the relativistic electron, though Dirac stated that he invented these same matrices himself independently at the time, without Pauli's influence. Dirac invented similar but larger (4x4) spin matrices for use in his relativistic treatment of fermionic spin.
In 1930, Pauli considered the problem of beta decay. In a letter of 4 December to Lise Meitner et al., beginning, "Dear radioactive ladies and gentlemen", he proposed the existence of a hitherto unobserved neutral particle with a small mass, no greater than 1% the mass of a proton, in order to explain the continuous spectrum of beta decay. In 1934, Enrico Fermi incorporated the particle, which he called a neutrino, into his theory of beta decay. The neutrino was first confirmed experimentally in 1956 by Frederick Reines and Clyde Cowan, two and a half years before Pauli's death. On receiving the news, he replied by telegram: "Thanks for message. Everything comes to him who knows how to wait. Pauli."[3]
In 1940, he proved the spin-statistics theorem, a critical result of quantum field theory which states that particles with half-integer spin are fermions, while particles with integer spin are bosons.
In 1949, he published a paper on Pauli-Villars regularization, which provides an important prescription for renormalization, or removing infinities from quantum field theories.
Pauli made repeated criticisms of the modern synthesis of evolutionary biology,[4][5] and his contemporary admirers point to modes of epigenetic inheritance as supportive of his arguments.[6]
The Pauli effect was named after his bizarre ability to break experimental equipment simply by being in the vicinity. Pauli himself was aware of his reputation, and was delighted whenever the Pauli effect manifested.
Regarding physics, Pauli was famously a perfectionist. This extended not just to his own work, but also to the work of his colleagues. As a result, he became known within the physics community as the "conscience of physics", the critic to whom his colleagues were accountable. He could be scathing in his dismissal of any theory he found lacking, often labelling it ganz falsch, utterly false.
However, this was not his most severe criticism, which he reserved for theories or theses so unclearly presented as to be untestable or unevaluatable, and thus not properly belonging within the realm of science, even though posing as such. They were worse than wrong because they could not be proven wrong. Famously, he once said of such an unclear paper: Das ist nicht nur nicht richtig, es ist nicht einmal falsch! "Not only is it not right, it's not even wrong".
His supposed remarks when meeting[citation needed] another leading physicist, Paul Ehrenfest, illustrates this notion of an arrogant Pauli. The two met at a conference for the first time. Ehrenfest, though never having met Pauli, was familiar with his papers, and was quite impressed with them. After a few minutes of conversation, Ehrenfest remarked, "I think I like your papers better than you," to which Pauli shot back, "I think I like you better than your papers". The two became very good friends from then on.
A somewhat warmer picture emerges from this story which appears in the article on Dirac:
"Werner Heisenberg [in Physics and Beyond, 1971] recollects a friendly conversation among young participants at the 1927 Solvay Conference, about Einstein and Planck's views on religion. Wolfgang Pauli, Heisenberg, and Dirac took part in it. Dirac's contribution was a poignant and clear criticism of the political manipulation of religion, that was much appreciated for its lucidity by Bohr, when Heisenberg reported it to him later. Among other things, Dirac said: "I cannot understand why we idle discussing religion. If we are honest - and as scientists honesty is our precise duty - we cannot help but admit that any religion is a pack of false statements, deprived of any real foundation. The very idea of God is a product of human imagination. [...] I do not recognize any religious myth, at least because they contradict one another. [...]" Heisenberg's view was tolerant. Pauli had kept silent, after some initial remarks. But when finally he was asked for his opinion, jokingly he said: "Well, I'd say that also our friend Dirac has got a religion and the first commandment of this religion is 'God does not exist and Paul Dirac is his prophet'". Everybody burst into laughter, including Dirac.
In May 1929, Pauli left the Roman Catholic Church. In December of that year, he married Käthe Margarethe Deppner. The marriage was an unhappy one, ending in divorce in 1930 after less than a year. He married again in 1934 to Franziska Bertram. They had no children.
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