In the first half of the 20th century, the work of Niels Bohr and his collaborators established Copenhagen as a world center for modern physics. Bohr encouraged contacts and collaborations with Nordic physicists, several of whom visited Copenhagen to take part in the international research going on there. These developments naturally led to discussions to establish a joint Nordic research center.
The 1950s saw a widespread political will for joint projects, both at the Nordic and at the European level; the war had demonstrated the importance of scientific preeminence and that of physics in particular. In 1952, the Western European nations decided to establish a large accelerator laboratory, the European Center for Nuclear Physics (CERN). Copenhagen figured prominently as a possible site for the new laboratory. Eventually Geneva was preferred but the theory group of the new laboratory was initially located in Copenhagen.
When it was finally decided that the CERN theory group was to move from Copenhagen to Geneva, Torsten Gustafson, Niels Bohr and other prominent Nordic physicists took the initiative to establish a Nordic center for theoretical physics in Copenhagen. The idea was well received at the political level, notably by the Swedish Prime Minister Tage Erlander. Theoretical physics was an uncontroversial, relatively inexpensive area of collaboration and research, and the other Nordic countries stood to benefit from the eminent research group in Copenhagen.
Nordita opened on October 1st 1957. An important activity of the new Institute was the training of young Nordic researchers, as there was no organized doctoral education in physics in the Nordic countries at that time. In the 1960s, the Nordic countries considerably expanded their research and teaching in physics, with many new positions being established at the universities. A large fraction of the researchers who had been trained at Nordita were offered positions and the Institute has continued to train future leaders in theoretical physics. Out of 320 young researchers who worked at Nordita in Copenhagen between 1957 and 2006, at least 165 have secured permanent university positions. It is still early days for Nordita in Stockholm, but of 20 postdoctoral fellows at Nordita since 2007, 18 have moved on into other academic positions at the postdoctoral or junior faculty level. Today, Nordita alumni form an extensive contact group, which the Institute draws upon for maintaining and extending Nordic collaborations.
Although Nordita originally derived its name from atomic physics, the Nordita faculty was quite diverse from the beginning. Christian Møller (1904-1980), Nordita's first Director, was known for his contributions to the theory of gravitation and quantum chemistry. Léon Rosenfeld (1904-1974) joined Nordita in 1958. He coined the term "lepton" and was among the first to work on quantum electrodynamics. Gunnar Källén (1926-1968) worked on elementary particle physics and the renormalization of quantum electrodynamics. Nuclear and atomic physics was represented in the early years by Stefan Rozental (1903-1994) and Ben Roy Mottelson. Mottelson would go on to win the 1975 Nobel Prize in Physics, together with Aage Bohr and Leo James Rainwater, for his groundbreaking work on the geometry of atomic nuclei. Aage Bohr became Director of Nordita in 1975. Gerald E. Brown accepted a Nordita professorship in 1960, bringing his research on many body problems and effective models for the atomic interaction, and later the theory of compact stars and the chiral bag model of the atomic nucleus.
James Hamilton arrived at Nordita in 1964 and soon established a research group in elementary particle physics, focusing in particular on the use of dispersion relations in the analysis of the strong interaction. At that time, particle physics was still widely considered a sub-field of nuclear physics and Hamilton's lectures provided invaluable guidance for young Nordic researchers interested in this emerging area of theoretical physics. In the years 1976-78, Hamilton published a series of papers calculating the effect of electromagnetic interactions on hadron scattering that became known as "the Nordita method."
Gösta Gustafson came to Copenhagen as a Nordita fellow in 1968 and worked with James Hamilton. He remained in close contact after returning to Lund in 1972 and the famous "Lund String Model" later emerged out of this interaction. This is a phenomenological model of hadronization in particle scattering that is still widely used, for instance in analyzing data from the Large Hadron Collider at CERN. As of today, it has been cited more than 2000 times, a striking documentation of its impact.
Holger Bech Nielsen was a Nordita fellow from 1967-1971. In the following years he produced a number of tremendously influential articles on highly energetic particle collisions. Nielsen is today regarded one of the fathers of String Theory. Nordita has remained a strong player in the field of String Theory with Paolo Di Vecchia and Konstantin Zarembo leading the high-energy theory group.
In the 1970's Nordita was instrumental in building up the field of astrophysics and cosmology in the Nordic countries through the training of young researchers and organizing workshops, and summer schools. It was an attractive subject for Nordita to introduce because of the numerous observational discoveries due to advances in instrumentation, and because astrophysics has broad contacts with other branches of physics that were already pursued at the Institute. This extension of research areas was aided by the flexibility Nordita had to make strategic recruitments and attract world class talent.
Astrophysical research at Nordita is still outstanding in its areas of specialization: the study of compact objects and high-density matter (neutron stars, black holes) led by Christopher Pethick, astrophysical magneto-hydrodynamics and plasma astrophysics led by Axel Brandenburg. This is a field that has greatly benefitted from the rapid increase in computational power allowing more sophisticated simulation of physical systems. Pethick has advanced physics by his imaginative applications of many-body theory across several different areas, starting with helium liquids, continuing with neutron star dynamics and supernova collapse, and more recently the analysis of the rich physics of ultra-cold atomic condensates, where he and his colleagues are engaged in a continuing dialogue with leading experimentalists.
Nordita has a strong tradition in the field of condensed matter physics. Alan Luther and Christopher Pethick came to Nordita in the mid 1970's and had profound influence on the development of condensed matter physics in the Nordic countries. Alan Luther is known for his work on electron systems in one dimension. The techniques he invented are of prime importance in the study of nano wires, including those exhibiting topological phases of matter. The strong emphasis on condensed matter physics continues with the recent addition of Alexander Balatsky, a leading expert on the theory of strongly correlated electrons, to the Nordita senior faculty.
The discovery of chaos and self-organized criticality in complex systems was one of the most important developments in science in the second half of the 20th century. These concepts are tightly woven into the fabric of many fields of science, and we have only touched on the full scope of insights they can bring. John Hertz, who joined Nordita in 1981, is a pioneer in the theory of neural networks and author of one of the defining textbooks in the field. Kim Sneppen, who was a Nordita fellow from 1989 to 1991, and co-author of the well known Bak-Sneppen model of co-evolution of interacting species, is recognized for his work on self-organized criticality and non-linear dynamics, extending into the field of biological networks. This field of research has a close interaction between theory and experiments on specific biological systems, such as bacteriophages (viruses infecting bacteria).
The scientific history of Nordita spans over 50 years and includes many other notable developments that are not described here. Over time, not only the content of fundamental research in theoretical physics has changed, but also its infrastructure and technology. The information age deeply affects how researchers gather and disseminate information and facilitates long-distance collaborations. Today seminars at Nordita are routinely recorded and uploaded to YouTube and software for computational astrophysics, developed at Nordita, is publicly available worldwide. Extensive numerical simulations have become an indispensible part of Nordita research, and, in that, the Institute greatly benefits from ready access to world-class technological infrastructure in Sweden and the other Nordic countries.
NORDITA 50 år - article by Christofer Cronström published in 2008 in Reflexer, the journal of Fysikersamfundet i Finland.
The on-line biography of Professor James Hamilton, who was a Nordita Professor of Theoretical Particle Physics from 1964 to 1986, includes chapters on his years at Nordita in Copenhagen.