Fritz London discovered practical applications of quantum mechanics and is known primarily for his work with the explanation of the covalent bond in hydrogen. His theories regarding superconductivity and superfluids were also important contributions to the development of these areas of science. Fritz Wolfgang London was born on March 7, 1900, in Breslau, Germany (now Wroclaw, Poland). He was the elder of two sons born to Luise (Hamburger) and Franz London, who taught mathematics at the University of Breslau as well as at the University of Bonn. Fritz London received a classical education in high school, and his university studies followed the same pattern. He attended the universities of Bonn, Frankfurt, and Munich, receiving his Ph.D. in philosophy from Munich in 1921; his dissertation involved a study of symbolic logic. In the four-year period following his graduation, London taught at various secondary schools in Germany and continued to study and write about philosophy. He then decided to pursue a new field of interest--theoretical physics--and returned to Munich to study under German theoretical physicist Arnold Sommerfeld.
One of the first topics on which London worked at Munich was the hydrogen molecule. He was interested in the question of whether or not modern quantum mechanics could provide an explanation for the covalent bond--the chemical bond involving shared electrons--that holds two hydrogen atoms together in a hydrogen molecule. That task became the model for much of London's subsequent work.
Until the 1930s, quantum mechanics, or wave mechanics, had been regarded as a totally sufficient system--in fact, the only correct system--for dealing with atomic-scale particles and their interactions with energy. The practical application was much less clear, and London began to explore the ways in which quantum principles could be used to explain visible phenomena. His research into the hydrogen molecule in the late 1920s, along with German physicist Walter Heitler , is recognized for advancing the existing knowledge of chemical bonding. In his 1954 introduction to London's second volume of Superfluids, Felix Bloch described the duo's success with the hydrogen molecule as an illustration of "the direct connection between pure quantum phenomena and some of the most striking facts of chemistry." In 1927 London and Heitler published a paper detailing the results of their analysis.
After this triumph, London continued to work on similar problems, looking for the applications of quantum theory to various types of chemical reactions and to the nature of forces between two molecules. Most of his work was brought together in a book on molecular theory scheduled to be published by the German firm of Springer. By the time the manuscript reached the publisher, however, London had left Germany, and Springer refused to honor its contract. Although London continued to work on the book in English translation, it never appeared in print.
In 1932 London turned his energies toward a new topic: superconductivity, or the complete disappearance of electrical resistance in a substance, seen particularly at low temperatures. That topic was one his younger brother Heinz London had selected for his doctoral research at the University of Breslau. Over the next few years, the London brothers worked together to develop a new theory of superconductivity. In the course of their research, they found that an extremely thin outer layer in the superconducting material contains the electrical current. A key element in their studies was a new perspective on the subject provided by the 1933 discovery by W. Meissner and R. Ochsenfeld that superconducting materials tend to expel a magnetic field within it prior to cooling. Bloch, in his introduction to volume two of London's Superfluids, called the Londons' 1934 paper on superconductivity "a decisive step forward by indicating the direction in which a solution [to the problem of superconductivity] has to be sought."
London's work on superconductivity seemed to lead naturally to a related topic: superfluidity. First described by the Russian physicist Pyotr Kapitsa in the late 1930s and early 1940s, superfluidity is the tendency of a fluid to flow without resistance, much as electrons flow without resistance in a superconductor. Liquid helium below the temperature of 2.19 K, for example, may flow upward along the sides of a container and pass through tiny cracks that would be impervious, or impenetrable, to other liquids. London spent a large fraction of the last two decades of his life trying to solve that challenge. The result of that effort was the monumental two-volume work Superfluids, the second part of which was published after his death.
London's research work was interrupted in the 1930s by the rise of Nazi dictator Adolf Hitler in Germany. Both London and his brother left Germany in 1933 for England, where they both accepted appointments at Oxford University's Clarendon Laboratory. Fritz then spent two years at the Institut Henri Poincaré in Paris before taking a job as professor of theoretical chemistry at Duke University in North Carolina. He remained at Duke until his death of a heart attack in Durham, North Carolina, on March 30, 1954. He was survived by his wife, the former Edith Caspary, an artist, and their two children.
This is the complete article, containing 839 words
(approx. 3 pages at 300 words per page).
