Isidor Isaac Rabi
Isidor Isaac Rabi (/ˈrɑːbi/; born Israel Isaac Rabi, July 29, 1898 – January 11, 1988) was an American physicist who won the Nobel Prize in Physics in 1944 for his discovery of nuclear magnetic resonance, which is used in magnetic resonance imaging (MRI). He was also one of the first scientists in the United States to work on the cavity magnetron, which is used in microwave radar and microwave ovens.
Isidor Isaac Rabi
January 11, 1988 (aged 89)
New York City, U.S.
2
- Newcomb Cleveland Prize (1939)
- Elliott Cresson Medal (1942)
- Nobel Prize in Physics (1944)
- Medal for Merit (1948)
- Barnard Medal (1960)
- Atoms for Peace Award (1967)
- Oersted Medal (1982)
- Public Welfare Medal (1985)
- Vannevar Bush Award (1986)
Born into a traditional Polish-Jewish family in Rymanów, Galicia, Rabi came to the United States as an infant and was raised in New York's Lower East Side. He entered Cornell University as an electrical engineering student in 1916, but soon switched to chemistry. Later, he became interested in physics. He continued his studies at Columbia University, where he was awarded his doctorate for a thesis on the magnetic susceptibility of certain crystals. In 1927, he headed for Europe, where he met and worked with many of the finest physicists of the time.
In 1929, Rabi returned to the United States, where Columbia offered him a faculty position. In collaboration with Gregory Breit, he developed the Breit–Rabi equation and predicted that the Stern–Gerlach experiment could be modified to confirm the properties of the atomic nucleus. His techniques for using nuclear magnetic resonance to discern the magnetic moment and nuclear spin of atoms earned him the Nobel Prize in Physics in 1944. Nuclear magnetic resonance became an important tool for nuclear physics and chemistry, and the subsequent development of magnetic resonance imaging from it has also made it important to the field of medicine.
During World War II he worked on radar at the Massachusetts Institute of Technology (MIT) Radiation Laboratory (RadLab) and on the Manhattan Project. After the war, he served on the General Advisory Committee (GAC) of the Atomic Energy Commission, and was chairman from 1952 to 1956. He also served on the Science Advisory Committees (SACs) of the Office of Defense Mobilization and the Army's Ballistic Research Laboratory, and was Science Advisor to President Dwight D. Eisenhower. He was involved with the establishment of the Brookhaven National Laboratory in 1946, and later, as United States delegate to UNESCO, with the creation of CERN in 1952. When Columbia created the rank of university professor in 1964, Rabi was the first to receive that position. A special chair was named after him in 1985. He retired from teaching in 1967, but remained active in the department and held the title of University Professor Emeritus and Special Lecturer until his death.
Early years[edit]
Israel Isaac Rabi was born on July 29, 1898, into a Polish-Jewish Orthodox family in Rymanów, Galicia, in what was then part of Austria-Hungary but is now Poland. Soon after he was born, his father, David Rabi, emigrated to the United States. The younger Rabi and his mother, Sheindel, joined David there a few months later, and the family moved into a two-room apartment on the Lower East Side of Manhattan. At home the family spoke Yiddish. When Rabi was enrolled in school, Sheindel said his name was Izzy, and a school official, thinking it was short for Isidor, put that down as his name. Henceforth, that became his official name. Later, in response to anti-Semitism, he started writing his name as Isidor Isaac Rabi, and was known professionally as I.I. Rabi. To most of his friends and family, including his sister Gertrude, who was born in 1903, he was known simply by his last name. In 1907, the family moved to Brownsville, Brooklyn, where they ran a grocery store.[1]
As a boy, Rabi was interested in science. He read science books borrowed from the public library and built his own radio set. His first scientific paper, on the design of a radio condenser, was published in Modern Electrics when he was in elementary school.[2][3] After reading about Copernican heliocentrism, he became an atheist. "It's all very simple", he told his parents, adding, "Who needs God?"[4] As a compromise with his parents, for his Bar Mitzvah, which was held at home, he gave a speech in Yiddish about how an electric light works. He attended the Manual Training High School in Brooklyn, from which he graduated in 1916.[5] Later that year, he entered Cornell University as an electrical engineering student, but soon switched to chemistry. After the American entry into World War I in 1917, he joined the Student Army Training Corps at Cornell. For his senior thesis, he investigated the oxidation states of manganese. He was awarded his Bachelor of Science degree in June 1919, but since at the time Jews were largely excluded from employment in the chemical industry and academia, he did not receive any job offers. He worked briefly at the Lederle Laboratories, and then as a bookkeeper.[6]
Education[edit]
In 1922 Rabi returned to Cornell as a graduate chemistry student, and began studying physics. In 1923 he met, and began courting, Helen Newmark, a summer-semester student at Hunter College. To be near her when she returned home, he continued his studies at Columbia University, where his supervisor was Albert Wills. In June 1924 Rabi landed a job as a part-time tutor at the City College of New York. Wills, whose specialty was magnetism, suggested that Rabi write his doctoral thesis on the magnetic susceptibility of sodium vapor. The topic did not appeal to Rabi, but after William Lawrence Bragg gave a seminar at Columbia about the electric susceptibility of certain crystals called Tutton's salts, Rabi decided to research their magnetic susceptibility, and Wills agreed to be his supervisor.[7]
Measuring the magnetic resonance of crystals first involved growing the crystals, a simple procedure often done by elementary school students. The crystals then had to be prepared by skillfully cutting them into sections with facets that had an orientation different from the internal structure of the crystal, and the response to a magnetic field had to be painstakingly measured. While his crystals were growing, Rabi read James Clerk Maxwell's 1873 A Treatise on Electricity and Magnetism, which inspired an easier method. He lowered a crystal on a glass fiber attached to a torsion balance into a solution whose magnetic susceptibility could be varied between two magnetic poles. When it matched that of the crystal, the magnet could be turned on and off without disturbing the crystal. The new method not only required much less work, it also produced a more accurate result. Rabi sent his thesis, entitled On the Principal Magnetic Susceptibilities of Crystals, to Physical Review on July 16, 1926. He married Helen the next day. The paper attracted little fanfare in academic circles, although it was read by Kariamanickam Srinivasa Krishnan, who used the method in his own investigations of crystals. Rabi concluded that he needed to promote his work as well as publish it.[8][9]
Like many other young physicists, Rabi was closely following momentous events in Europe. He was astounded by the Stern–Gerlach experiment, which convinced him of the validity of quantum mechanics. With Ralph Kronig, Francis Bitter, Mark Zemansky and others, he set out to extend the Schrödinger equation to symmetric top molecules and find the energy states of such a mechanical system. The problem was that none of them could solve the resulting equation, a second-order partial differential equation. Rabi found the answer in Ludwig Schlesinger's Einführung in die Theorie der Differentialgleichungen, which describes a method originally developed by Carl Gustav Jacob Jacobi. The equation had the form of a hypergeometric equation to which Jacobi had found a solution. Kronig and Rabi wrote up their result and sent it to Physical Review, which published it in 1927.[10][11]
Europe[edit]
In May 1927, Rabi was appointed a Barnard Fellow. This came with a stipend of $1,500 ($26,000 in 2023 dollars[12]) for the period from September 1927 to June 1928. He immediately applied for a year's leave of absence from the City College of New York so he could study in Europe. When this was refused, he resigned. On reaching Zürich, where he hoped to work for Erwin Schrödinger, he met two fellow Americans, Julius Adams Stratton and Linus Pauling. They found that Schrödinger was leaving, as he had been appointed head of the Theoretical Institute at Friedrich Wilhelm University in Berlin. Rabi therefore decided to seek a position with Arnold Sommerfeld at the University of Munich instead. In Munich, he found two more Americans, Howard Percy Robertson and Edward Condon. Sommerfeld accepted Rabi as a postdoctoral researcher. German physicists Rudolf Peierls and Hans Bethe were also working with Sommerfeld at the time, but the three Americans became especially close.[13]
On Wills' advice, Rabi traveled to Leeds for the 97th annual meeting of the British Association for the Advancement of Science, where he heard Werner Heisenberg present a paper on quantum mechanics. Afterwards, Rabi moved to Copenhagen, where he volunteered to work for Niels Bohr. Bohr was on vacation, but Rabi went straight to work on calculating the magnetic susceptibility of molecular hydrogen. After Bohr returned in October, he arranged for Rabi and Yoshio Nishina to continue their work with Wolfgang Pauli at the University of Hamburg.[14]
Although he came to Hamburg to work with Pauli, Rabi found Otto Stern working there with two English-speaking postdoctoral fellows, Ronald Fraser and John Bradshaw Taylor. Rabi soon made friends with them, and became interested in their molecular beam experiments,[15] for which Stern would receive the Nobel Prize in Physics in 1943.[16] Their research involved non-uniform magnetic fields, which were difficult to manipulate and hard to measure accurately. Rabi devised a method of using a uniform field instead, with the molecular beam at a glancing angle, so the atoms would be deflected like light through a prism. This would be easier to use, and produce more accurate results. Encouraged by Stern, and greatly assisted by Taylor, Rabi managed to get his idea to work. On Stern's advice, Rabi wrote a letter about his results to Nature,[15] which published it in February 1929,[17] followed by a paper entitled Zur Methode der Ablenkung von Molekularstrahlen ("On the method of deflection of molecular beams") to Zeitschrift für Physik, where it was published in April.[18]
By this time the Barnard Fellowship had expired, and Rabi and Helen were living on a $182 ($3,200 in 2023 dollars[12]) per month stipend from the Rockefeller Foundation. They left Hamburg for Leipzig, where he hoped to work with Heisenberg. In Leipzig, he found Robert Oppenheimer, a fellow New Yorker. It would be the start of a long friendship. Heisenberg departed for a tour of the United States in March 1929, so Rabi and Oppenheimer decided to go to the ETH Zurich, where Pauli was now the professor of physics. Rabi's education in physics was enriched by the leaders in the field he met there, which included Paul Dirac, Walter Heitler, Fritz London, Francis Wheeler Loomis, John von Neumann, John Slater, Leó Szilárd and Eugene Wigner.[19]