After matriculation at the Gammelholm Grammar
School in 1903, he entered Copenhagen University where he came under
the guidance of Professor C. Christiansen, a profoundly original and
highly endowed physicist, and took his Master's degree in Physics in
1909 and his Doctor's degree in 1911.
While still a student, the announcement by the Academy of Sciences
in Copenhagen of a prize to be awarded for the solution of a certain
scientific problem, caused him to take up an experimental and
theoretical investigation of the surface tension by means of
oscillating fluid jets. This work, which he carried out in his
father's laboratory and for which he received the prize offered (a
gold medal), was published in the Transactions of the Royal Society,
Bohr's subsequent studies, however, became more and more theoretical
in character, his doctor's disputation being a purely theoretical
piece of work on the explanation of the properties of the metals
with the aid of the electron theory, which remains to this day a
classic on the subject. It was in this work that Bohr was first
confronted with the implications of Planck's quantum theory of
In the autumn of 1911 he made a stay at Cambridge, where he profited
by following the experimental work going on in the
J.J. Thomson's guidance, at the same time as he pursued own
theoretical studies. In the spring of 1912 he was at work in
Professor Rutherford's laboratory in Manchester, where just in
those years such an intensive scientific life and activity prevailed
as a consequence of that investigator's fundamental inquiries into
the radioactive phenomena. Having there carried out a theoretical
piece of work on the absorption of alpha rays which was published in
the Philosophical Magazine, 1913, he passed on to a study of
the structure of atoms on the basis of Rutherford's discovery of the
atomic nucleus. By introducing conceptions borrowed from the Quantum
Theory as established by Planck, which had gradually come to occupy
a prominent position in the science of theoretical physics, he
succeeded in working out and presenting a picture of atomic
structure that, with later improvements (mainly as a result of
Heisenberg's ideas in 1925), still fitly serves as an elucidation of
the physical and chemical properties of the elements.
In 1913-1914 Bohr held a Lectureship in Physics at Copenhagen
University and in 1914-1916 a similar appointment at the Victoria
University in Manchester. In 1916 he was appointed Professor of
Theoretical Physics at Copenhagen University, and since 1920 (until
his death in 1962) he was at the head of the Institute for
Theoretical Physics, established for him at that university.
Recognition of his work on the structure of atoms came with the
award of the Nobel Prize for 1922.
Bohr's activities in his Institute were since 1930 more and more
directed to research on the constitution of the atomic nuclei, and
of their transmutations and disintegrations. In 1936 he pointed out
that in nuclear processes the smallness of the region in which
interactions take place, as well as the strength of these
interactions, justify the transition processes to be described more
in a classical way than in the case of atoms (Cf. »Neutron capture
and nuclear constitution«, Nature, 137 (1936) 344).
A liquid drop would, according to this view, give a very good
picture of the nucleus. This so-called liquid droplet theory
permitted the understanding of the mechanism of nuclear fission,
when the splitting of uranium was discovered by Hahn and Strassmann,
in 1939, and formed the basis of important theoretical studies in
this field (among others, by Frisch and Meitner).
Bohr also contributed to the clarification of the problems
encountered in quantum physics, in particular by developing the
concept of complementarily. Hereby he could show how deeply the
changes in the field of physics have affected fundamental features
of our scientific outlook and how the consequences of this change of
attitude reach far beyond the scope of atomic physics and touch upon
all domains of human knowledge. These views are discussed in a
number of essays, written during the years 1933-1962. They are
available in English, collected in two volumes with the title Atomic
Physics and Human Knowledge and Essays 1958-1962 on Atomic
Physics and Human Knowledge, edited by John Wiley and Sons, New
York and London, in 1958 and 1963, respectively.
Among Professor Bohr's numerous writings (some 115 publications),
three appearing as books in the English language may be mentioned
here as embodying his principal thoughts: The Theory of Spectra
and Atomic Constitution, University Press, Cambridge, 1922/2nd.
ed., 1924; Atomic Theory and the Description of Nature,
University Press, Cambridge, 1934/reprint 1961; The Unity of
Knowledge, Doubleday & Co., New York, 1955.
During the Nazi occupation of Denmark in World War II, Bohr escaped
to Sweden and spent the last two years of the war in England and
America, where he became associated with the Atomic Energy Project.
In his later years, he devoted his work to the peaceful application
of atomic physics and to political problems arising from the
development of atomic weapons. In particular, he advocated a
development towards full openness between nations. His views are
especially set forth in his Open Letter to the United Nations,
June 9, 1950.
Until the end, Bohr's mind remained alert as ever; during the last
few years of his life he had shown keen interest in the new
developments of molecular biology. The latest formulation of his
thoughts on the problem of Life appeared in his final (unfinished)
article, published after his death: "Licht und Leben-noch einmal",
Naturwiss., 50 (1963) 72: (in English: "Light and Life
revisited", ICSU Rev., 5 ( 1963) 194).
Niels Bohr was President of the Royal Danish Academy of Sciences, of
the Danish Cancer Committee, and Chairman of the Danish Atomic
Energy Commission. He was a Foreign Member of the Royal Society
(London ), the Royal Institution, and Academies in Amsterdam,
Berlin, Bologna, Boston, Göttingen, Helsingfors, Budapest, München,
Oslo, Paris, Rome,
Stockholm, Uppsala, Vienna, Washington, Harlem, Moscow,
Trondhjem, Halle, Dublin, Liege, and Cracow. He was Doctor,
honoris causa, of the following universities, colleges, and
institutes: (1923-1939) -
(1945-1962) - Sorbonne (Paris),
Athens, Lund, New
Roosevek (Chicago, Ill.),
(Haifa), Bombay, Calcutta,
Cambridge (Mass.), and
Professor Bohr was married, in 1912, to Margrethe Nřrlund, who was
for him an ideal companion. They had six sons, of whom they lost
two; the other four have made distinguished careers in various
professions - Hans Henrik (M.D.), Erik (chemical engineer),
(Ph.D., theoretical physicist, following his father as Director of
the Institute for Theoretical Physics), Ernest (lawyer).
Niels Bohr died in Copenhagen on November 18, 1962.