Christian Møller The Concepts of Mass and Energy in the General Theory of Relativity I-II
Christian Møller was a prominent representative of Danish theoretical physics during half a century, well known within research and also as a splendid lecturer. He worked for the whole of his scientific life at the University of Copenhagen. He was born in 1904 in Jylland. He became fascinated by the beauty of physics, especially by relativity theory, at an early age. He was associated with the Institute of Theoretical Physics already in the 1920’s, and was there deeply influenced by his highly admired master Niels Bohr, and the stimulating atmosphere at this institute. This was the time when relativistic quantum mechanics was being developed. Møller succeeded in calculating the collision process between two relativistic electrons as early as 1930-31. Nowadays, calculations of this sort are made routinely in courses on QED as an example of second order perturbative theory, but in those days the systematic perturbative technique was not yet developed. Møller instead made use of an intricate argument, invented by himself, to derive the correct result. Electron-electron scattering is nowadays simply called Møller-scattering.
In the years to come, Møller continued to be deeply involved in quantum mechanical problems of current interest: Dirac’s positron theory, the theory of beta decay, and Yukawa’s meson theory. He also made significant contributions to the theory of the S matrix, based upon basic principles from quantum mechanics and relativity.
In the last 25 years of his life, Møller returned to the main passion of his scientific life, namely general relativity. His textbook «The Theory of Relativity» from 1952, containing both the special and the general relativity, became rapidly a classic in the field. The second and much expanded version the book was published in 1972. In the meantime, significant achievements had been made both on the theoretical and on the experimental side, and Møller became quite naturally a central figure in this lively scientific community.
When NORDITA was established in Copenhagen in 1957 Møller became its first director, and he had this position until 1971. He took also other administrative duties, in connection with CERN.
Møller remained scientifically active until the end of his life. He died in January 1980, after a brief period of illness. His many friends will remember him not only as a great scientist but also as a very kind man, possessing personal integrity and a good sense of humor.