'Never express yourself more clearly than you are able to think.Henry Gwyn Jeffries Moseley was born in Dorset in November 1887. 'The best weapon of a dictatorship is secrecy, but the best weapon of a democracy should be the weapon of openness.' 'Everything we call real is made of things that cannot be regarded as real.' It forces us to change our thinking in order to find it.' 'Every great and deep difficulty bears in itself its own solution. It has since been renamed the Niels Bohr Institute in his honor. Bohr's theory stresses the point that an experiment's results are deeply affected by the measurement tools used to carry them out.īohr's contributions to the study of quantum mechanics are forever memorialized at the Institute for Theoretical Physics at Copenhagen University, which he helped found in 1920 and headed until his death in 1962. This concept, which forms the basis of early quantum theory, also explains that regardless of how one views an electron, all understanding of its properties must be rooted in empirical measurement. Quantum theoryīohr's concept of complementarity, which he wrote about in a number of essays between 19, states that an electron can be viewed in two ways, either as a particle or as a wave, but never both at the same time. Atomic Energy Project during World War II, Bohr was an outspoken advocate for the peaceful application of atomic physics. This theory was instrumental in the first attempts to split uranium atoms in the 1930s, an important step in the development of the atomic bomb.ĭespite his contributions to the U.S. According to his liquid droplet theory, a liquid drop provides an accurate representation of an atom's nucleus. Liquid droplet theoryīohr's theoretical work contributed significantly to scientists' understanding of nuclear fission. 107 on the periodic table of elements, is named for him. The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons.īohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element. (Image credit: Boris15 Shutterstock) Atomic modelīohr's greatest contribution to modern physics was the atomic model. He believed that nations should be completely open with one another and wrote down these views in his Open Letter to the United Nations in 1950.Ī stylized representation of a lithium atom illustrates Niels Bohr's atomic model, that an atom is a small, positively charged nucleus surrounded by orbiting electrons. He dedicated his work toward the peaceful use of atomic physics and toward solving political problems arising from the development of atomic weapons of destruction. It was important to him, however, to use his skills for good and not violence.

He spent the last two years of the war in England and the United States, where he got involved with the Atomic Energy Project. When the Nazis invaded Denmark in World War II, Bohr managed to escape to Sweden. Later in life, he became president of the Royal Danish Academy of Sciences, as well as a member of scientific academies all over the world. In the same year that he began his studies with Rutherford, Bohr married the love of his life, Margaret Nørlund, with whom he had six sons. This work earned him a Nobel Prize of his own in 1922. In 1920, he was appointed the head of the Institute for Theoretical Physics.Ĭombining Rutherford's description of the nucleus and Planck's theory about quanta, Bohr explained what happens inside an atom and developed a picture of atomic structure. He went back to Copenhagen University in 1916 to become a professor of theoretical physics. Under Rutherford's tutelage, Bohr began studying the properties of atoms.īohr held a lectureship in physics at Copenhagen University from 1913 to 1914 and went on to hold a similar position at Victoria University in Manchester from 1914 to 1916.

Thompson in England when he was introduced to Ernest Rutherford, whose discovery of the nucleus and development of an atomic model had earned him a Nobel Prize in chemistry in 1908. In 1912, Bohr was working for the Nobel laureate J.J.

Henry moseley atomic theory