Aage Bohr followed his father, the eminent physicist Niels Bohr, into the field of theoretical physics. Bohr's father was director of the Institute for Theoretical Physics in Copenhagen and instrumental in the development of the Manhattan Project (the U.S. secret program to build the atom bomb during World War II), which the younger Bohr also contributed to as his father's secretary and lab assistant. In the late 1940s and 1950s, Aage Bohr conducted his own research on the structure of the atomic nucleus. With his collaborators, James Rainwater and Ben R. Mottelson, Bohr developed the collective model of nuclear matter. For their work, the three scientists were awarded the Nobel Prize in physics in 1975.
Aage Neils Bohr was born in Copenhagen on June 19, 1922, the fourth son of Margrethe No slash rlund Bohr and Niels Bohr. His early education took place at the Sortedam Gymnasium, as well as informally at his father's Institute for Theoretical Physics, where he met many of the world's leading names in physics. Bohr's physics education was interrupted by the invasion of Denmark by German forces in 1940. The Jewish Bohr family was forced to flee their country to neutral Sweden, and later England, before coming to the United States. The younger Bohr accompanied his father to the United States in 1943, serving as his secretary and lab assistant at the Los Alamos Scientific Laboratory in New Mexico. After World War II, the family returned to Denmark, where Bohr resumed his education at the University of Copenhagen. He received his M.S. degree from the University of Copenhagen in 1946 and his Ph.D. in 1954.
During his graduate studies, Bohr accepted a research position at the Institute for Theoretical Physics, but returned to the United States in 1949, where he conducted research at Columbia University on the hyperfine structure of deuterium ("heavy hydrogen") and began working with James Rainwater on the structure of the atomic nucleus. Working together at Columbia to understand the basic makeup of the atomic nucleus, Bohr and Rainwater came to the conclusion that a new model was needed to adequately explain the structural and functional properties of the nucleus. The two model theories previously put forth directly contradicted each other, and over the years the soundness of both had been challenged. One of those models, the liquid-drop model, was developed by Bohr's father in 1936. This model proposed that protons and neutrons (the nucleons) are held together by nuclear forces comparable to the way molecules attract each other in a drop of water. The second and opposing model, the shell model, held that the nucleons move in concentric orbits, or shells, in much the same manner electron shells do in an atom. The shell model, put forth by Maria Goeppert-Mayer and J. Hans D. Jensen in 1949, also posited that the sum of the forces of the nucleons resulted in a spherical "force field." Later experiments challenged this theory by showing that in cases where the outermost shell was incomplete, the charge distribution around the nucleus was nonspherical. Rainwater's contribution to the existing body of research was to suggest that interactions between particles in an incomplete outer shell and those deep within the nucleus might cause the nucleus to become distorted.
Bohr expanded this research in a collaboration with Benjamin Mottelson when he returned to the Institute for Theoretical Physics in Copenhagen in 1950. Acting on Rainwater's hypothesis, Bohr, working with Mottelson, created a new model for describing nuclear structure. This model, called the collective model, was a synthesis of the liquid and shell models. The new model showed that the surface of the nucleus does indeed act like a liquid drop, but that the shell structure is subject to centrifugal distortions that account for some nuclei being spherical and some oblong.
The trio of Bohr, Mottelson, and Rainwater received the 1975 Nobel Prize in physics for what the Royal Swedish Academy of Sciences described as the "discovery of the connection between collective motion and particle motion in the atomic nucleus and the development of the theory of the structure of the atomic nucleus based on this connection."
At the time of his father's death in 1962, Bohr had assumed the directorship at the Institute for Theoretical Physics, then renamed the Niels Bohr Institute. He remained there in this administrative capacity until 1970. He became director of the Nordic Institute for Theoretical Atomic Physics (Nordita) in 1975. Bohr continued to do theoretical research until his retirement from Nordita in 1981.
In addition to the Nobel Prize, Bohr has received many other honors from his peers during his career. They include the Dannie Heineman Prize in 1960, the Pope Pius XI Medal in 1963, the Atoms for Peace Award in 1969, the O slash rsted Medal in 1970, the Rutherford Medal in 1972, the John Price Wetherill Medal in 1974, and the Ole Ro slash mer Medal in 1976. He has been a member of six academies of science throughout Europe, the National Academy of Science in the United States, and has held membership in many other professional associations. He has received honorary degrees from the Universities of Oslo, Heidelberg, Trondheim, Manchester, and Uppsala.
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