1939 - Science

Science

Otto Hahn, Fritz Strassmann, and Lise Meitner publish their work on nuclear reactions in the German scientific journal Die Naturwissenschaften January 6 (see 1938); they identify the elements barium, cerium, and lanthanum as products of the neutron bombardment of uranium, but they do not recognize that fission has occurred.

The cyclotron of Nebraska-born nuclear physicist John R. (Ray) Dunning, 31, produces nuclear fission for the first time in America January 25 in Room 128 of Columbia University's Pupin Physics Laboratory, suggesting the possibility of self-sustaining chain reaction. When the cyclotron is shut down, stable cobalt-59 begets within its disks unstable cobalt-60, which emits gamma rays.

Lise Meitner recognizes that nuclear fission did in fact occur in her work last year with Otto Hahn and Fritz Strassmann; living in exile in Britain, she states that fact in a letter published in the journal Nature February 11. Enrico Fermi, Hungarian-born U.S. physicist Leo Szilard, 41, Ontario-born U.S. physicist Walter H. Zinn, 32, C. B. Pegram, and John R. Dunning repeat Meitner's experiment at Columbia March 3 with the same result. The nuclear research at Columbia confirms European findings that the absorption of a neutron by a uranium nucleus sometimes causes the nucleus to split into approximately equal parts with the release of enormous amounts of energy. Danish physicist Niels Bohr discusses the findings with Albert Einstein at Princeton, N.J., and Hungarian-born physicist Eugene P. Wigner, 36, and others convince Einstein of the need to warn President Roosevelt that production of an atomic bomb is a real possibility (see Bohr, 1913; Einstein, 1929; U-235, 1935; 1940).

Albert Einstein writes to President Roosevelt August 2, "Some recent work by E. Fermi and L. Szilard which has been communicated to me in manuscript leads me to expect that the element uranium may be turned into a new and important source of energy in the near future. Certain aspects of the situation which has arisen seem to call for watchfulness and, if necessary, quick action on the part of the Administration . . . In the course of the last four months it has been made almost certain . . . that it may become possible to set up a nuclear chain reaction in a large mass of uranium, by which vast amounts of power and large quantities of radium-like elements would be generated . . . This new phenomenon could lead also to the construction of bombs." FDR appoints an Advisory Committee on Uranium (see first controlled chain reaction, 1942).

San Francisco-born experimental physicist Luis W. (Walter) Alvarez, 28, at the University of California, Berkeley, and Swiss-born physicist Felix Bloch, 33, of Stanford University make the first measurement of a neutron's magnetic moment—a characteristic of the strength and direction of its magnetic field (see Rabi, 1938). Bloch proposed a method 5 years ago for splitting a beam of neutrons into two components corresponding to the two possible orientations of a neutron in a magnetic field; Alvarez last year discovered that some radioactive elements decay by a process of orbital-electron capture, in which an orbital electron merges with its nucleus to produce an element smaller by one atomic number (see particle accelerator, 1946).

Chemist Linus C. Pauling develops a resonance theory of chemical valence that has enabled him to construct models for a number of anomalous molecules, notably the benzene molecule, which have not been explainable by conventional chemical terms (see 1931; Dirac and Schrödinger, 1926). Now 38, Pauling produces a full account of chemical bonding, and his book The Nature of the Chemical Bond and the Structure of Molecules and Crystals will win him a 1954 Nobel Prize.

Hanover-born Berlin chemist Isidor Traube, 79, accepts a position at the University of Edinburgh, having founded capillary chemistry and advanced knowledge of critical temperature, osmosis, colloids, and surface tension through his research on liquids.

The Mathematical Foundations of Quantum Mechanics by John von Neumann provides a precise formulation and proof of the "ergodic hypothesis" of statistical mathematics (see 1926). Now 28, von Neumann published a definition of ordinal numbers 8 years ago, it has been universally adopted, and he will become a professor next year at Princeton's Institute of Advanced Study.

Elements of Mathematics (Elémentes mathématique) by French mathematicians who use the pen name Nicolas Bourbaki will have a powerful influence on the development of algebraic geometry and other areas of mathematical research. Paris-born mathematician André Weil, 33, has encouraged his colleagues to build on work by David Hilbert and Kurt Gödel.

Swedish astrophysicist Hannes (Olof Gösta) Alfvén, 31, publishes a theory of magnetic storms and auroral displays in the atmosphere. Alfvén will join the staff of the Royal Institute of Technology at Stockholm next year.

Mathematician Ferdinand von Lindemann dies at Munich March 1 at age 86; archaeologist Howard Carter at London March 2 at age 65; Nobel physical chemist Wilhelm Ostwald outside Leipzig April 4 at age 78; mathematician Giuseppe Peano at Turin April 20 at age 73; logician-mathematician Stanislaw Leshniewkski suddenly at Warsaw May 13 at age 55, having pioneered the concepts of protothesis, ontology, and mereology; astronomer Sir Frank Dyson dies at sea while en route from Australia to England May 25 at age 71.