Niels Bohr  bigraphy, stories - A Danish physicist-theorist and public figure

Niels Bohr : biography

07 October 1885 - 18 November 1962

Bohr is known as a founder of the first quantum theory of an atom and an active member of development of quantum mechanics’ basis. He also made a major distribution to the development of a theory about atomic nucleus and nuclear reactions, processes of interaction of elementary particles with environment.

Youth. The Bohr-van Leeuwen theorem (1885-1911)

Niels Bohr was born in a family of a professor of physiology in the Christian Bohr’s Copenhagen university (1858-1911) who twice became a candidate for Nobel prize on physiology and medicine, and Ellen Adler (1860-1930), a daughter of an influential and well-off Jewish banker and parliamentarian liberal David Baruh Adler (1826-1878) and Jenny Raphael (1830-1902) from a British Jewish banker dynasty Raphael Raphael and Sons. Bohr’s parents married in 1881.

In school Niels was interested in physics and mathematics, he was also keen on philosophy. It was favoured by regular visits of father’s colleagues and friends: a philosopher Harald Hoffding, a physicist Christian Christiansen, a linguist Wilhelm Tomsen. Bohr’s close friend and classmate was his second cousin (in the female line) who became a famous psychologist Edgar Rubin (1886-1951, among his optical illusions was a so-called Rubin’s vase). Rubin involved Bohr to study philosophy.

Another Bohr’s interest was football. Niels and his brother Harald (who became a famous mathematician) played in the amateur club “Academisk” (the first was a goalkeeper and the second was a halfback). In the future Harald successfully played in Danish national team and won a silver medal on the Olympic Games in 1908 where Danish team was inferior to British in the final game.

In 1903 Niels Bohr entered the Copenhagen University where he studied physics, chemistry, astronomy and mathematics. He with his brother organized a student philosophy group members of which made lectures by turns. In university Niels Bohr made his first works on studying vibration of liquid flow for more exact definition of the size of surface tension of water. The theoretical research in 1906 was awarded with the golden medal of Danish royal society. In 1907-1909 it was supplemented with experimental results which were got by Bohr in physiology laboratory of his father and it was published with the help of leading figures in physics of that time Ramsay and Rayleigh.

In 1910 Bohr became a holder of master’s degree and in May of 1911 he defended doctoral dissertation on classical electronic theory of metals. In this dissertation Bohr developed Lorenz’ ideas and proved an important theorem of classical static mechanics which claims that magnetic moment of every totality of elemental electrical charge which move according to laws of classical mechanics in constant magnetic field in stationary condition is equal to zero. In 1919 this theorem was independently discovered again by Johanna van Leeuwen and has a name the Bohr-van Leeuwen theorem. It has an ingenuous result of impossibility of explanation of material’s magnetic characteristics (particularly diamagnetism) in limits of classical physics. It seems to be the first Bohr’s collision with narrow-mindedness of classical description which brought him closer to questions of quantum theory.

Bohr in England. Bohr’s theory (1911-1016)

In 1911 Bohr got a grant of 2500 kronas from the Fund of Karlsberg to have a study course abroad. In September of 1911 he arrived in Cambridge to started working in Cavendish laboratory under the leadership за famous Tompson. But the collaboration wasn’t established: Tompson wasn’t interested in a young Danish man who straight off showed him a mistake in one of Tompson’s works and who spoke English not very well. Afterwards Bohr recollected about it: “I was disappointed, Tompson wasn’t interested that his calculations weren’t right. It was my fault too. I spoke English not enough well and couldn’t explain myself… On the whole it was interesting but absolutely useless to work in Cambridge”.

Finally in March of 1912 Bohr moved to Manchester to Ernest Reserford whom he met not long ago. In 1911 Reserford after his experiments published the planetary model of an atom. Bohr actively started to work on this subject and had a lot of discussions with a famous chemist Georg Hevesy who worked in Manchester at that time and with Reserford himself. The initial idea was the fact that element’s characteristics were defined by whole number – the atomic number which is equal to nucleus’ charge which could change in processes of radioactive decay. The first use of Reserford’s atomic model for Bohr was examination of processes of interaction of alpha and beta-rays with material which he conducted in last months of his stay in England, in summer of 1912 Bohr returned in Denmark.

Living octopus

Living octopus

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