Niels Henrik David Bohr (7 October 1885 – 18 November 1962, married Margrethe Norlund in 1912) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. He was part of the British team of physicists working on the Manhattan Project.
Bohr, who died 40 years ago, said that under his beloved protégé, ''everything was being done in Germany to develop atomic weapons.''
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.
He also acted as a prominent part of the team of physicists working on the Manhattan Project. His contribution to the field of physics has received remarkable praise from many scientists all over the world.
During World War II, Bohr fled Copenhagen to escape the Nazis. He traveled to Los Alamos, New Mexico to advise the scientists developing the first atomic bomb. He returned to Copenhagen after the war and later promoted the peaceful use of atomic energy.
Bohr recognized that his first assumption violates the principles of classical mechanics. But he knew that it was impossible to explain the spectrum of the hydrogen atom within the limits of classical physics. He was therefore willing to assume that one or more of the principles from classical physics might not be valid on the atomic scale.
He also introduced the idea that the electrons travel in discrete orbits around the atom's nucleus, the chemical properties of the particular element being largely determined by the number of electrons in the outer orbits.
The model introduced the theory of electrons traveling in orbits around the atom's nucleus, the chemical properties of the element being largely determined by the number of electrons in the outer orbits. Bohr also introduced the idea that an electron could drop from a higher-energy orbit to a lower one, emitting a photon (light quantum) of discrete energy. This became the basis for quantum theory.
Bohr proposed a model that included the idea that the electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbits. He calculated the radii for these allowed orbits by using the theories of classical physics and by making some new assumptions.
In the Bohr Model the neutrons and protons occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun
In 1921, with the assistance of the Danish government and the Carlsberg Foundation, he founded the Institute of Theoretical Physics in Copenhagen, where he served as director for the rest of his life. The Institute soon became an international focal point for theoretical physicists in the 1920s and 1930s, and most of the world's best known theoretical physicists of that period spent at least some time there.
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.
After receiving his doctorate in 1911, Bohr traveled to England on a study grant and worked under J.J. Thomson, who had discovered the electron 15 years earlier. Bohr began to work on the problem of the atom's structure.