Ben Roy Mottelson dies at 95; Shed light on the shape of atoms

By awarding the Nobel to Drs. Mottelson, Bohr and Rainwater, the Royal Swedish Academy of Sciences cited his “discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection.”

Ben Roy Mottelson was born on July 9, 1926, in Chicago, the second of three children born to Goodman and Georgia (Blum) Mottelson. His father was an engineer. The family home was a place of spirited conversation on scientific, political, and moral issues, Dr. Mottelson recalled in an autobiographical sketch for the Nobel Foundation.

He graduated from Lyons Township High School in La Grange, Ill., during World War II and, after joining the Navy, was sent to Purdue University for officer training. After graduating with a bachelor’s degree in 1947, he entered Harvard University for graduate studies in nuclear physics. There he studied with Julian Schwinger, the theoretical physicist who received the Nobel Prize in 1965 for his work on quantum electrodynamics. With Dr. Schwinger as his thesis advisor, Dr. Mottelson earned his Ph.D. in 1950.

Receiving a one-year Sheldon Travel Scholarship from Harvard, he decided to spend time at the Institute for Theoretical Physics in Copenhagen (later renamed for Niels Bohr, its founder). Dr. Bohr still worked there, as did his son Aage. It was at this time that he began the collaboration between Dr. Mottelson and the young Dr. Bohr. (In a twist of science, Niels Bohr had proposed the liquid droplet model which was eventually rendered obsolete by the work of Drs. Mottelson, Rainwater, and Aage Bohr.)

When the Sheldon fellowship ended, Dr. Mottelson received a two-year fellowship from the United States Atomic Energy Commission, allowing him to remain in Copenhagen. He then was hired by the recently formed European Organization for Nuclear Research, known as CERN, which had been started in Copenhagen before moving to Geneva.

When the Nordic Institute for Theoretical Atomic Physics was created in 1957, Dr. Mottelson was hired there as a professor. He remained there for the rest of his professional life, with only a brief stint at the University of California, Berkeley, in the spring of 1959.

He became a naturalized Danish citizen in 1971.

The theory established by Dr. Mottelson and his colleagues on the shape of atomic nuclei became universally accepted. But, as is often the case in science, he initially met with some resistance.

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