Everything about Pauli totally explained
Wolfgang Ernst Pauli (
April 25,
1900 –
December 15,
1958) was an
Austrian
theoretical physicist noted for his work on
spin theory, and for the discovery of the
exclusion principle underpinning the structure of matter and the whole of
chemistry.
Biography
Pauli was born in
Vienna to Wolfgang Joseph Pauli and 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 (originally Wolf Pascheles) 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.
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
Einstein's theory of
general relativity. He attended the
Ludwig-Maximilians University in
Munich, working under
Sommerfeld, where he received his
doctorate in July 1921 for a thesis on the quantum theory of ionised
molecular hydrogen.
Sommerfeld asked Pauli to review the
theory of relativity for the
Encyklopaedie der mathematischen Wissenschaften (a German "
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.
He 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 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. (See below for a list of his scientific contributions.)
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.
At the beginning of 1931, shortly after his divorce and immediately following his postulation of the
neutrino, Pauli had a severe breakdown. He consulted the psychiatrist and psychotherapist
Carl Jung who, like Pauli, lived near
Zurich. Jung immediately began interpreting Pauli's deeply
archetypal dreams, 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 (see below).
In 1928, he was appointed Professor of Theoretical Physics at
ETH Zurich 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.
In 1934, he married
Franciska Bertram. This marriage would last for the rest of his life. They had no children.
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 Zurich, where he mostly remained for the rest of his life.
In 1945, he received the
Nobel Prize in Physics for his "decisive contribution through his discovery in 1925 of a new law of Nature, the exclusion principle or
Pauli principle." He was nominated for the prize by
Einstein.
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 Zurich, 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 December 15, 1958.
Scientific career
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
Bohr and
Heisenberg, with whom he'd 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. The following are the most important results for which he
has been credited:
In 1924, Pauli proposed 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.
Uhlenbeck and
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.
In 1927, he introduced the 2x2
Pauli matrices as a basis of spin operators, thus solving the nonrelativistic theory of spin. This work is sometimes said to have influenced
Dirac in his discovery 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 December 4, beginning "Dear radioactive ladies and gentlemen" (to
Lise Meitner et al.), 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,
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"
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, and his contemporary admirers point to modes of
epigenetic inheritance as supportive of his arguments.
Personality and reputation
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 wasn't 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 couldn't be proven wrong. Famously, he once said of such an unclear paper: "It is
not even wrong."
His supposed remarks when meeting 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 can't understand why we idle discussing religion. If we're honest - and as scientists honesty is our precise duty - we can't 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 don't 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 doesn't exist and Paul Dirac is his prophet.'" Everybody burst into laughter, including Dirac.
Bibliographies
by Pauli
about Pauli
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