NIELS BOHR
Niels Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research.
He developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete, and that the electrons revolve in stable orbits around the atomic nucleus, but can jump from one energy level (or orbit) to another. He conceived the principle of complementarity: that items could be separately analysed in terms of contradictory properties, like behaving as a wave or a stream of particles. The notion of complementarity dominated Bohr's thinking on both science and philosophy.
Bohr founded the Institute of Theoretical Physics at the University of Copenhagen, now known as the Niels Bohr Institute, which opened in 1920. He predicted the existence of a new zirconium-like element, which was named hafnium, after the Latin name for Copenhagen, where it was discovered. Later, the element bohrium was named after him.
After Hitler took power in Germany, Bohr was deeply concerned for his colleagues there, and offered a place for many escaping Jewish scientists to live and work. He later donated his gold Nobel medal to the Finnish war effort. In 1939 Bohr visited the United States with the news from Lise Meitner (who had escaped German-occupied Austria) that German scientists were working on splitting the atom. This spurred the United States to launch the Manhattan Project to develop the atomic bomb. Shortly after Bohr's return home, the German army occupied Denmark. Three years later Bohr's family fled to Sweden in a fishing boat. Then Bohr and his son Aage left Sweden traveling in the empty bomb rack of a British military plane. They ultimately went to the United States, where both joined the government's team of physicists working on atomic bomb at Los Alamos. Bohr had qualms about the consequences of the bomb. He angered Winston Churchill by wanting to share information with the Soviet Union and supporting postwar arms control. Bohr went on to organize the Atoms for Peace Conference in Geneva in 1955. Bohr called for international cooperation on nuclear energy. He was involved with the establishment of CERN and he became the first chairman of the Nordic Institute for Theoretical Physics in 1957.
Niels Bohr 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 Prof. 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 doctoral 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 stayed in 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 intensive scientific life and activity prevailed as a consequence of that investigator's fundamental inquiries into the radioactive phenomena. Having 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, which even today serves as an elucidation of the physical and chemical properties of the elements.
Recognition of his work on the structure of atoms came with the award of the Nobel Prize for 1922.
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, a Nobel Prize winner (Ph.D., theoretical physicist, following his father as Director of the Institute for Theoretical Physics), Ernest (lawyer).
Bohr's personal warmth, good humor and hospitality combined with world events to make Copenhagen a refuge for many of the century's greatest physicists.
Niels Bohr who was born in 1885 died in Copenhagen in 1962 following a stroke.
Three famous quotes of Bohr.
"An expert is a man who has made all the mistakes which can be made, in a very narrow field."
"Never express yourself more clearly than you are able to think".
" Prediction is very difficult especially about the future."
PPR
18—02--2014
( hari krishnamurthy K. HARIHARAN)"think of them as Sand paper.
They Scratch & hurt you,
but in the end you are polished and they are finished. ''
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