Niels Henrik David Bohr was born
in Copenhagen on October 7, 1885, as the son of Christian Bohr,
Professor of Physiology at Copenhagen University, and his wife Ellen,
née Adler. Niels, together with his younger brother
Harald (the future Professor in Mathematics), grew up in an
atmosphere most favourable to the development of his genius - his
father was an eminent physiologist and was largely responsible
for awakening his interest in physics while still at school, his
mother came from a family distinguished in the field of
education.
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, 1908.
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 radiation.
In the autumn of 1911 he made a stay at Cambridge, where he
profited by following the experimental work going on in the
Cavendish
Laboratory under Sir 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 complementarity. 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) - Cambridge, Liverpool, Manchester, Oxford, Copenhagen,
Edinburgh,
Kiel,
Providence, California, Oslo, Birmingham, London; (1945-1962) - Sorbonne (Paris),
Princeton,
Mc. Gill
(Montreal), Glasgow, Aberdeen, Athens, Lund, New York, Basel, Aarhus, Macalester (St. Paul), Minnesota, Roosevelt (Chicago, Ill.), Zagreb,
Technion
(Haifa), Bombay, Calcutta, Warsaw, Brussels, Harvard, Cambridge (Mass.), and Rockefeller (New
York).
Professor Bohr was married, in 1912, to Margrethe Nørlund,
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), Aage (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.
From Nobel Lectures, Physics 1922-1941, Elsevier Publishing Company, Amsterdam, 1965
This autobiography/biography was written at the time of the award and first published in the book series Les Prix Nobel. It was later edited and republished in Nobel Lectures. To cite this document, always state the source as shown above.
Copyright © The Nobel Foundation 1922
Niels Bohr
