Copenhagen, 1885 – Ibid, 1962
Danish physicist who made important contributions to the understanding of the structure of the atom and quantum mechanics.
Son of Christian Bohr, a devout Lutheran, professor of physiology at the University of the city, and Ellen Adler, from a wealthy Jewish family of great importance in Danish banking, and in the "circles of Parliament".
Considered one of the most dazzling figures in contemporary Physics and, for his theoretical contributions and practical work, as one of the fathers of the atomic bomb, he was awarded the Nobel Prize in Physics in 1922 "for his research on the structure of atoms and the radiation emanating from them.
He studied Physics at the University of Copenhagen, where he obtained his doctorate in 1911. After having revealed himself as a firm promise in the field of Nuclear Physics, he traveled to England to expand his knowledge at the Cavendish Laboratory of the University of Copenhagen. Cambridge, under the tutelage of Sir Joseph John Thomson, a British chemist distinguished with the Nobel Prize in 1906 for his studies on the passage of electricity through the interior of gases, which had allowed him to discover the particle later baptized by Stoney as electron .
The doctoral thesis that the young Bohr had just read in Copenhagen was dedicated precisely to the study of electrons, and that he had taken to British territory with the hope of seeing it translated into English.
But Thomson was not enthusiastic about Bohr's work, so he decided to leave the Cavendish Laboratory and go to the University of Manchester, where he took advantage of the teachings of another Nobel laureate, Ernest Rutherford, to further his knowledge of radioactivity and models. of the atom.
From then on, a close collaboration was established between the two scientists that, sustained by firm ties of friendship, would be as lasting as it was fruitful.
Rutherford had elaborated a theory of the atom that was totally valid on a speculative plane, but that could not be sustained within the laws of classical Physics. Borh, in a display of audacity that was unpredictable in his timid and withdrawn character, dared to sidestep these problems that hindered Rutherford's progress with a solution as simple as it was risky: he simply stated that the movements that occurred within the atom they are governed by laws foreign to those of traditional Physics.
In 1913, Niels Bohr achieved worldwide celebrity in the field of Physics by publishing a series of essays in which he revealed his particular model of the structure of the atom. It was a modification of Rutherford's atomic model in which the atom is like "a microscopic solar system" in which the electrons orbit the nucleus. Bohr assumed that the electrons moved in circular orbits around the nucleus.
Niels Bohr developed his model according to three fundamental postulates:
1- The electrons describe circular orbits around the nucleus of the atom without radiating energy.
2- The only orbits allowed for an electron are those for which the angular momentum of the electron is a certain integer multiple.
3- The electron only emits or absorbs energy in jumps from one allowed orbit to another.
Three years later, the Danish scientist returned to his hometown to take up a position as professor of Theoretical Physics at his old alma mater; and, in 1920, thanks to the international prestige that he had been acquiring for his studies and publications, he obtained the necessary subsidies for the foundation of the Nordic Institute of Theoretical Physics (later called the Niels Bohr Institute), whose direction he assumed from 1921 to the date of his death (1962).
In a very short time, this Institute was erected, together with the German universities of Munich and Göttingen, at one of the three corners of the European triangle where the main research on the Physics of the atom was being developed.
In 1922, the year in which Bohr definitively established himself as a scientist of universal renown with the award of the Nobel Prize, his son Aage Niels Bohr was born, who followed in his father's footsteps and collaborated with him on various investigations.
Also with a doctorate in Physics, he was, like his father, a university professor of this subject and director of the Nordic Institute for Theoretical Physics, and received the Nobel Prize in 1975.
Immersed in his research on the atom and quantum mechanics, Niels Bohr enunciated, in 1923, the principle of correspondence, to which he added, in 1928, the principle of complementarity. As a result of this last contribution, the so-called "Copenhagen School of Quantum Mechanics" was formed around his figure, whose theories were fiercely refuted by Albert Einstein. Despite these differences, the father of the theory of relativity recognized the Danish physicist as "one of the greatest scientific researchers of our time."
In the 1930s, Niels Bohr spent long periods in the United States, where he brought the first news about nuclear fission, discovered in Berlin in 1938 by Otto Hahn and Fritz Strassmann, which would give rise to the manufacturing works of nuclear weapons of mass destruction. For five months he worked with J. A. Wheeler at the Institute for Advanced Study in Princeton, New Jersey, and announced with his collaborator that plutonium, like uranium, would be fissile.
In 1939, back in Denmark, he was elected president of the Royal Danish Academy of Sciences. He settled back in Copenhagen, where he continued to do research and teach until, in 1943, following the German occupation, he had to leave the country due to his Jewish origins.
His life and that of his loved ones became so threatened that he was forced to put his family on a small fishing boat and head for Sweden. A few days later, Bohr took refuge in the United States and, under the pseudonym Nicholas Baker, began to actively collaborate in the so-called "Manhattan Project", developed in the Los Alamos laboratory in New Mexico, the result of which was the manufacture of the first atomic bomb
At the end of World War II, in 1945, he returned to Denmark and returned to lead the Nordic Institute for Theoretical Physics. From then on, aware of the devastating applications that his research could have, he devoted himself to convincing his colleagues of the need to use the discoveries of nuclear physics for useful and beneficial purposes.
A pioneer in the organization of international symposia and conferences on the peaceful use of atomic energy, in 1951 he published and disseminated throughout the world a manifesto signed by more than a hundred eminent scientists, in which it was stated that public authorities should guarantee the use of atomic energy for peaceful purposes. For all these reasons, in 1957, he received the Atoms for Peace award, convened by the Ford Foundation to promote scientific research aimed at improving Humanity.
Director, since 1953, of the European Organization for Nuclear Research, Niels Henrik David Borh died in Copenhagen during the autumn of 1962, at the age of seventy-seven, after having printed some works as valuable as Theory of Spectra and Atomic Constitution (1922), Light and Life (1933), Atomic Theory and Description of Nature (1934), The Mechanism of Nuclear Fission (1939), and Atomic Physics and Human Knowledge (1958).
