The origins of the Niels Bohr Archive (NBA) may be dated to the 1950s, when Niels Bohr (1885–1962) set up a “secretariat” at his residence, the Carlsberg Mansion, in order to organize some of his letters and manuscripts. In the late 1950s, when the American Philosophical Society inaugurated the Archives for the History of Quantum Physics (AHQP) – an ambitious project to document the early history of quantum physics – Niels Bohr offered Carlsberg as its headquarters. This seemed only natural, as Bohr’s Copenhagen institute had been an international centre for developing quantum physics. As a result NBA (as it was called already then) became an original AHQP repository, offering its resources to historians of science from all over the world on some 290 microfilms, on which the Niels Bohr Scientific Correspondence (about 6,000 letters and drafts) the Niels Bohr Scientific Manuscripts (about 500 units), the originals of which are deposited at NBA, constitute a central part.

Establishment as a formal institution

In 1985, in connection with the centennial for Niels Bohr’s birth, NBA was formally established as an independent institution located at the Niels Bohr Institute with its own board of directors and under the supervision of the Danish Ministry of Education, which provided an annual grant covering most of the day-to-day expenses. To balance its budget as well as to carry on research, NBA has taken advantage of its privilege to apply for project support from private sources. In 2012 the University of Copenhagen took over the supervision of NBA, at the same time as the Danish Ministry increased its annual support to cover the salaries of the three employees in addition to a fixed sum for day-to-day expenses.

Archival holdings

On the occasion of its formal establishment, NBA received the majority of Bohr’s letters and manuscripts as well as other relevant items through a deed of gift from Niels Bohr’s widow and sons. These papers, which have since been conserved, ordered and catalogued, comprise the core of NBA’s holdings. Over the years the collections have been augmented with supplementary papers originating from Niels Bohr as well as from several of Bohr’s contemporaries, such as George Hevesy, Léon Rosenfeld, Hendrik Antony Kramers and Oskar Klein, in addition to several physicists of the next generation, notably Aage Bohr. Requests for material are still handled by the staff of three.

Niels Bohr Collected Works

From the very beginning in the early 1960s, NBA’s first priority was the publication of the Niels Bohr Collected Works, a project started by Niels Bohr’s younger colleague, Léon Rosenfeld. Work on the first volumes was supported by the Carlsberg Foundation. Volume 1 was published in 1972. In 1977, the project was taken over by Erik Rüdinger, who also took over the task of looking after the Archive. Rüdinger was Director of NBA until 1989, when he was succeeded by Finn Aaserud, who also took over as General Editor of the Collected Works which were completed with the publication of Volume 12 in 2006. In 2008, the Collected Works were published in a new limited edition with an added cumulative index. The new edition is also available as an e-book.

Centenary of the Bohr atom

NBA was heavily involved in the celebrations of the 100th anniversary in 2013 of Bohr’s path-breaking atomic model, which started a revolution in physics and its applications that still goes on today. In connection with the anniversary NBA was responsible for several research and popular publications as well as conferences and a film festival. In particular, a book by the prominent historian of science John L. Heilbron and NBA Director Finn Aaserud based on the otherwise closed early correspondence between Bohr and his fiancée Margrethe Nørlund, whom he was later to marry, sheds new light on Bohr both as a scientist and a person. Furthermore, an international historical conference in Copenhagen on Niels Bohr, his life and work provided the basis for the publication of an important proceedings.