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Wolfgang Pauli
Times obituary
A GREAT THEORETICAL PHYSICIST
Professor Wolfgang Pauli, Professor of Physics at the Federal Polytechnical High School, Zurich, died on Monday at the age of 59, our Geneva Correspondent reports.
He was born in Vienna, where his father was a professor in chemistry, but he himself studied at the University of Munich, where he was a pupil of Sommerfeld. Later he also worked with Professor Nils Bohr in Copenhagen. In 1939 he was invited to the United States by Albert Einstein and as a visiting professor at the Institute for Advanced Studies, Princeton, New Jersey; he stayed until 1946.
Pauli was one of the great theoretical physicists of his generation. As an originator of simple yet insightful ideas he was perhaps the greatest. He was also a man of great charm, known personally to most of his colleagues, friends, and admirers
tion as well as admiration by very many—young as well as old. He attained in his later years to a position approaching that of an oracle—one quick of opinion, yet happy as well as willing to change his mind when new facts had been discovered.
His first and most important contribution to physics was made in 1924. At this time, the theory of atomic structure was at the stage when the electrons that surround the nuclei of atoms were still considered in what might nat be called billiard-ball terms—but they had become billiard-balls whose behavior and possible states of energy were governed by what at the time were purely arbitrary rules. Pauli was responsible for the generalization that no two electrons could be in the same energy state—Pauli's exclusion principle, as it has been called. There is no explanation of this principle. It merely appears to be a fact which, in its general form, was first cast and stated by Puuli. It is accommodated, as indeed it had to be in the later and more sophisticated treatment of electrons in terms of wave mechanics.
NOBEL PRIZE AWARDED
The quantum theory of the atom accounts in some detail for many of the properties of the 100 or so chemical elements, and in this feat of generalization, Pauli's exclusion principle played a necessary part. Although the theory of the nucleus of the atom is in a less satisfactory state than that of the electronic or nic or outer structure of the atom, it appears that in the nucleus, too, Pauli's exclusion principle operates.
Pauli made a second and quite distinct contribution to physics in 1931. This, like the first, was in essence a simple but imaginative idea. A difficulty had arisen at that time in explaining the type of radioactivity in which electrons are emitted. When an atomic nucleus changes from one energy state to another, the energy absorbed or released should clearly be the same for all atoms that undergo the same change. But in this form of radioactive breakdown, the electrons are emitted with different energies from different atoms, and only the upper limit of their energy has the value required to tie in with other lines of evidence—cases, for example, in which a nucleus can break down by alternative routes to give the same final form.
Pauli saw that all difficulties could be resolved in the principle by supposing that there existed an electrically neutral particle with small or negligible mass, whose scle function was to carry away the balance of energy not accounted for. Pauli's ideas were elaborated by the late Professor Enrico Fermi three years later, and the name neutrino was given to the particle. The Nobel Prize which came to Pauli in 1945 was thus doubly deserved.
Pauli's simple way of putting things together—and looking at them—was illustrated in letters that he wrote before and after an experiment carried out in January last year to test a prediction by C. N. Yang and T. D. Lee, who later shared a Nobel Prize, that there would be a lack of symmetry with respect to left- and right-handedness in particles that entered into nuclear interactions only with some reluctance, such interactions being described therefore as "weak." Before the experiment, Pauli wrote to a fellow physicist: "I do not (underlined) believe that the Lord is a weak left-hander, and I am ready to bet a very high sum that the experiments will give symmetric results."
After the experiment, which showed the predicted lack of symmetry, he confessed in a further letter to a feeling of shock and went on: "I am shocked not so much by the fact that the Lord prefers the left hand, but by the fact that he still appears to be left-right symmetric when he expresses himself strongly." He was discussing one of the most profound problems of nuclear physics, but doing it in the simplest way possible.
This was typical of Pauli in a part of science that has often appeared difficult—and still does he have a genius for fastening on some one point which could be made simple, and so presented was seen at once to be important. That was the quality of his genius—and the simplicity that was in his nature as well as in his thinking made him also well loved.
A GREAT THEORETICAL PHYSICIST
Professor Wolfgang Pauli, Professor of Physics at the Federal Polytechnical High School, Zurich, died on Monday at the age of 59, our Geneva Correspondent reports.
He was born in Vienna, where his father was a professor in chemistry, but he himself studied at the University of Munich, where he was a pupil of Sommerfeld. Later he also worked with Professor Nils Bohr in Copenhagen. In 1939 he was invited to the United States by Albert Einstein and as a visiting professor at the Institute for Advanced Studies, Princeton, New Jersey; he stayed until 1946.
Pauli was one of the great theoretical physicists of his generation. As an originator of simple yet insightful ideas he was perhaps the greatest. He was also a man of great charm, known personally to most of his colleagues, friends, and admirers
tion as well as admiration by very many—young as well as old. He attained in his later years to a position approaching that of an oracle—one quick of opinion, yet happy as well as willing to change his mind when new facts had been discovered.
His first and most important contribution to physics was made in 1924. At this time, the theory of atomic structure was at the stage when the electrons that surround the nuclei of atoms were still considered in what might nat be called billiard-ball terms—but they had become billiard-balls whose behavior and possible states of energy were governed by what at the time were purely arbitrary rules. Pauli was responsible for the generalization that no two electrons could be in the same energy state—Pauli's exclusion principle, as it has been called. There is no explanation of this principle. It merely appears to be a fact which, in its general form, was first cast and stated by Puuli. It is accommodated, as indeed it had to be in the later and more sophisticated treatment of electrons in terms of wave mechanics.
NOBEL PRIZE AWARDED
The quantum theory of the atom accounts in some detail for many of the properties of the 100 or so chemical elements, and in this feat of generalization, Pauli's exclusion principle played a necessary part. Although the theory of the nucleus of the atom is in a less satisfactory state than that of the electronic or nic or outer structure of the atom, it appears that in the nucleus, too, Pauli's exclusion principle operates.
Pauli made a second and quite distinct contribution to physics in 1931. This, like the first, was in essence a simple but imaginative idea. A difficulty had arisen at that time in explaining the type of radioactivity in which electrons are emitted. When an atomic nucleus changes from one energy state to another, the energy absorbed or released should clearly be the same for all atoms that undergo the same change. But in this form of radioactive breakdown, the electrons are emitted with different energies from different atoms, and only the upper limit of their energy has the value required to tie in with other lines of evidence—cases, for example, in which a nucleus can break down by alternative routes to give the same final form.
Pauli saw that all difficulties could be resolved in the principle by supposing that there existed an electrically neutral particle with small or negligible mass, whose scle function was to carry away the balance of energy not accounted for. Pauli's ideas were elaborated by the late Professor Enrico Fermi three years later, and the name neutrino was given to the particle. The Nobel Prize which came to Pauli in 1945 was thus doubly deserved.
Pauli's simple way of putting things together—and looking at them—was illustrated in letters that he wrote before and after an experiment carried out in January last year to test a prediction by C. N. Yang and T. D. Lee, who later shared a Nobel Prize, that there would be a lack of symmetry with respect to left- and right-handedness in particles that entered into nuclear interactions only with some reluctance, such interactions being described therefore as "weak." Before the experiment, Pauli wrote to a fellow physicist: "I do not (underlined) believe that the Lord is a weak left-hander, and I am ready to bet a very high sum that the experiments will give symmetric results."
After the experiment, which showed the predicted lack of symmetry, he confessed in a further letter to a feeling of shock and went on: "I am shocked not so much by the fact that the Lord prefers the left hand, but by the fact that he still appears to be left-right symmetric when he expresses himself strongly." He was discussing one of the most profound problems of nuclear physics, but doing it in the simplest way possible.
This was typical of Pauli in a part of science that has often appeared difficult—and still does he have a genius for fastening on some one point which could be made simple, and so presented was seen at once to be important. That was the quality of his genius—and the simplicity that was in his nature as well as in his thinking made him also well loved.
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