Niels Bohr (1885-1962), Danish physicist, Nobel prize of physics in 1922. (Photo by Boyer/Roger Viollet)
School period
College/University
Gallery of Niels Bohr
Career
Gallery of Niels Bohr
Niels Bohr
Gallery of Niels Bohr
Niels Bohr
Gallery of Niels Bohr
Niels Bohr
Gallery of Niels Bohr
1953
Professor Niels Bohr (1885-1962), the nuclear scientist who shared the Nobel prize for Physics in 1922. (Photo by Keystone)
Gallery of Niels Bohr
1958
From left to right, famous physicists Sir Lawrence Bragg (1890-1971), Professor Niels Bohr (1885-1962), and Sir John Cockcroft (1897-1967) attend the annual Anglo-Danish Society banquet at the Dorchester Hotel in London, on May 29, 1956. (Photo by J. Wilds/Keystone/Hulton Archive)
Gallery of Niels Bohr
1958
Danish physicist Niels Bohr (1885-1962) and Sir John Cockcroft, director of the Atomic Energy Authority at Copenhagen, winner of the Niels Bohr Medal for his contribution towards the peaceful uses of atomic energy. (Photo by Keystone)
Gallery of Niels Bohr
Niels Bohr
Gallery of Niels Bohr
Niels Bohr
Gallery of Niels Bohr
Niels Bohr
Gallery of Niels Bohr
The Danish physicist Niels Bohr (1885-1962). He was awarded the 1922 Nobel prize for physics. (Photo by Hulton-Deutsch Collection/CORBIS)
Achievements
A postage stamp depicting Bohr from Mongolia.
Membership
The Royal Netherlands Academy of Arts and Sciences
From left to right, famous physicists Sir Lawrence Bragg (1890-1971), Professor Niels Bohr (1885-1962), and Sir John Cockcroft (1897-1967) attend the annual Anglo-Danish Society banquet at the Dorchester Hotel in London, on May 29, 1956. (Photo by J. Wilds/Keystone/Hulton Archive)
Danish physicist Niels Bohr (1885-1962) and Sir John Cockcroft, director of the Atomic Energy Authority at Copenhagen, winner of the Niels Bohr Medal for his contribution towards the peaceful uses of atomic energy. (Photo by Keystone)
(First published in 1934, and reprinted in 1961, this coll...)
First published in 1934, and reprinted in 1961, this collection contains four articles and an introductory survey. Originally written for various journals during the 1920s, the articles concern themselves with the epistemological significance of discoveries in quantum physics. Although aimed at physicists, they are generally non-technical, with only one using some elementary mathematics. This book will be of value to anyone with an interest in Bohr's contribution to physics.
(These essays and speeches by the Nobel Prize–winning phys...)
These essays and speeches by the Nobel Prize–winning physicist date from 1934 to 1958. Rather than expositions on quantum physics, the articles are philosophical in nature, exploring the relevance of atomic physics to many areas of human endeavor. Topics include light and life, biology and atomic physics, natural philosophy and human cultures, unity of knowledge, atoms and human knowledge, and physical science and the problem of life. An essay in which Bohr and Einstein discuss determinism in quantum theory and the future of the wave equation theory is of particular note.
(Quantum Theory contains the seminal works of quantum theo...)
Quantum Theory contains the seminal works of quantum theory from the early years of the 20th Century, representing breakthroughs in science that radically altered the landscape of modern knowledge: Quantum Theory of Line-Spectra by Niels Bohr and The Origin and Development of the Quantum Theory by Max Planck.
Niels Bohr, in full Niels Henrik David Bohr, was a Danish physicist who is generally regarded as one of the foremost physicists of the 20th century. He 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.
Background
Niels Henrik David Bohr was born on October 7, 1885, in Denmark's capital city, Copenhagen. He was the second of three children in a prosperous, upper-class family.
His father was Christian Bohr, a brilliant physiology professor who would later be nominated twice for a Nobel Prize. His mother was Ellen Adler, daughter of a wealthy Danish politician.
His father had been raised in a Lutheran family and his mother in a Jewish family. Niels was baptized as a Lutheran at the age of six to please one of his grandmothers. Neither his father nor his mother practiced their religions.
Education
Niels' parents were deeply passionate about their children's education. Niels was taught at home until he started formal schooling aged 7 at the Gammelholm Grammar School. The school was both an elementary and high school. It had strict discipline and expected its students to work hard.
His father brought home a variety of fellow professors from the University of Copenhagen and the Bohr children were allowed to listen to the conversations, which were wide-ranging, discussing science, philosophy, and the arts.
Niels was good at most school subjects, but was rather weak in his own native language, Danish. While he loved talking, he had a thorough dislike of writing essays. Naturally talented in mathematics, he became increasingly drawn to the sciences. Physics especially interested Niels and by the time he was a teenager he was correcting the mistakes in his schools' textbooks. In addition to his intellectual vigor, he was also unusually strong physically. He didn't just correct textbooks; he would also "correct" other students, getting into fights at school, which he usually won.
Although he would eventually become one of the world's greatest theoretical physicists, he was talented practically with his hands. He and his younger brother spent hours making things in their father's workshop.
His father saw Niels had the potential to become an outstanding scientist. However, neither of Niels' parents wanted their son to grow up with narrow interests. They ensured he was well-educated culturally and in sports.
His father was particularly enthusiastic about the works of the German author Goethe and would regularly recite large tracts of Faust to his children. His father also loved soccer and encouraged his sons to play at school and university. Niels became a goalkeeper, while his younger brother Harald went on to play for Denmark, winning an Olympic silver medal.
In 1903, aged 17, Niels graduated from high school. Later that year he began his studies at the University of Copenhagen. He studied astronomy, chemistry, mathematics, and majored in physics. In February 1905, while he was working towards his degree, The Royal Danish Academy of Sciences announced a gold medal would be awarded for the best research paper on methods for measuring the surface tension of liquids. This was a prize intended for experienced scientists, not undergraduates. Niels was aware of his own growing strength in physics and he was ambitious; he decided he would enter the competition.
He was fortunate in having a professor for a father. His father allowed him space in his physiology laboratory to do experiments. For months Niels worked alone and obsessively during the night, making his own equipment and using it to form water jets and make measurements.
His father, recognizing his son's growing obsession with the experiments, ordered him to stop and write up his research. Niels retreated to his wealthy maternal grandparents' country estate to do this. The paper he submitted at the end of October 1906 was sufficiently brilliant to win him a gold medal - a remarkable achievement for an undergraduate. He shared the prize with Peder Pedersen, 11 years his senior, who would soon become a professor of electrical engineering.
Niels Bohr graduated with a Bachelor of Science degree in 1907.
In the years 1907-1911, Bohr completed his Master's and doctoral degrees in physics. In both cases, he turned his attention to the electron theory of metals. His doctoral degree, awarded in April 1911, was a purely theoretical work.
In the autumn of 1911, Niels Bohr made a stay at 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 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. Having there 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, still fitly serves as an elucidation of the physical and chemical properties of the elements.
In 1913-1914 Bohr held a Lectureship in Physics at Copenhagen University and in 1914-1916 a similar appointment at the Victoria University in Manchester. In 1916 he was appointed Professor of Theoretical Physics at Copenhagen University, and since 1920 (until his death in 1962) he was at the head of the Institute for Theoretical Physics (now Niels Bohr Institute), established for him at that university.
Recognition of his work on the structure of atoms came with the award of the Nobel Prize for 1922.
Bohr's activities in his Institute were since 1930 more and more directed to research on the constitution of the atomic nuclei, and of their transmutations and disintegrations. In 1936 he pointed out that in nuclear processes the smallness of the region in which interactions take place, as well as the strength of these interactions, justify the transition processes to be described more in a classical way than in the case of atoms.
A liquid drop would, according to this view, give a very good picture of the nucleus. This so-called liquid droplet theory permitted the understanding of the mechanism of nuclear fission, when the splitting of uranium was discovered by Hahn and Strassmann, in 1939, and formed the basis of important theoretical studies in this field.
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. These views are discussed in a number of essays, written during the years 1933-1962. They are available in English, collected in two volumes with the title Atomic Physics and Human Knowledge and Essays 1958-1962 on Atomic Physics and Human Knowledge, edited by John Wiley and Sons, New York and London, in 1958 and 1963, respectively.
Among Professor Bohr's numerous writings (some 115 publications), three appearing as books in the English language may be mentioned here as embodying his principal thoughts: The Theory of Spectra and Atomic Constitution, Atomic Theory and the Description of Nature, The Unity of Knowledge.
During the Nazi occupation of Denmark in World War II, Bohr escaped to Sweden and spent the last two years of the war in England and America, where he became associated with the Atomic Energy Project. In his later years, he devoted his work to the peaceful application of atomic physics and to political problems arising from the development of atomic weapons. In particular, he advocated a development towards full openness between nations. His views are especially set forth in his Open Letter to the United Nations, June 9, 1950.
Until the end, Bohr's mind remained alert as ever; during the last few years of his life, he had shown keen interest in the new developments of molecular biology. The latest formulation of his thoughts on the problem of Life appeared in his final (unfinished) article, published after his death: "Licht und Leben - noch einmal" (1963, in English: "Light and Life revisited").
He was Doctor, honoris causa, of the following universities, colleges, and institutes: (1923-1939) - Cambridge, Liverpool, Manchester, Oxford, Copenhagen, Edinburgh, Kiel, Providence, California, Oslo, Birmingham, London; (1945-1962) - Sorbonne (Paris), Princeton, Mc. Gill (Montreal), Glasgow, Aberdeen, Athens, Lund, New York, Basel, Aarhus, Macalester (St. Paul), Minnesota, Roosevelt (Chicago, Ill.), Zagreb, Technion (Haifa), Bombay, Calcutta, Warsaw, Brussels, Harvard, Cambridge (Mass.), and Rockefeller (New York).
Niels Bohr died in Copenhagen on November 18, 1962.
(These essays and speeches by the Nobel Prize–winning phys...)
1957
Religion
Bohr, although he had been christened in the Christian Church and had Jewish origins on his mother's side, was an agnostic.
Politics
Bohr's scientific brilliance happened to come about parallel to World War II. Denmark was occupied by Nazi Germany for the bulk of the war. During this time, Bohr arranged for many Jewish scientists to be hidden throughout Denmark or assisted their escape to Sweden. He also donated the money from his Nobel Prize to the Finnish war effort. When it was revealed that the Nazis were going to arrest Bohr, he and his family also fled to Sweden, where Bohr managed to convince the King of Sweden to publicly announce that his country would harbor Jewish refugees.
Bohr was then recruited by the United States and Britain to work on the Manhattan Project - the initiative that would ultimately create the atomic bomb.
Views
Niels Bohr suggested one day that electrons can not be just anywhere. He continued that the electrons only have certain amounts of energy and that they can only be found certain distances away from the nucleus. Furthermore that they travel around the nucleus at very high speed, in a circular motion called orbits. The electrons don't get pulled into the nucleus, in spite of being attracted to the nucleus by the electrostatic attraction between them.
Bohr further proclaimed that the electrons that have the same energy attraction orbit at the same distance from the nucleus. The more energy in the electron the further it can be away from the nucleus. This meant that the atom is therefore made up of sets of possible energy levels, which were then called Electron shells.
The further away they are the closer the electron shells are to one another. For some imparticular reason, from the nucleus outwards, they were called the K shell, L shell M shell, and so on.
Niels Bohr is responsible for the Bohr's theory of the atom and liquid-drop model of the atomic nucleus.
The Bohr theory was based on four postulates:
(1) An Atom, consisting of a nucleus together with its system of electrons, possesses certain special dynamical states having the property that as long as the atom remains in one of these states it doesn't radiate.
(2) The dynamical equilibrium of states can be treated by ordinary mechanics: but the transitions between them cannot be so treated and indeed are not subject to explicit description.
(3) When an atom makes a transition from one state, of energy E₁, to another, of lower energy E₂, the excess energy is emitted as radiation of a single frequency, v, related to the energy difference by Planck's relationship E₁ - E₂ = hv.
(4) For a single electron moving in an orbit around the nucleus the angular moving in an orbit around the nucleus, the angular momentum, L, is an integer multiple of h/2 π.
Quotations:
"An expert is a person who has made all the mistakes that can be made in a very narrow field."
"The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth."
"Prediction is very difficult, especially about the future."
"Those who are not shocked when they first come across quantum theory cannot possibly have understood it."
"Everything we call real is made of things that cannot be regarded as real."
"How wonderful that we have met with a paradox. Now we have some hope of making progress."
"There are some things so serious that you have to laugh at them."
"Never express yourself more clearly than you are able to think."
"A physicist is just an atom's way of looking at itself."
Membership
In 1923, Niels Bohr became a Foreign Member of the Royal Netherlands Academy of Arts and Sciences.
In 1926, he became a Foreign Member of the Royal Society.
The Royal Netherlands Academy of Arts and Sciences
1923
The Royal Society
1926
Personality
Physical Characteristics:
As a youth, Bohr was unusually strong physically.
Interests
Sport & Clubs
soccer
Connections
In 1912, Bohr married Margrethe Nørlund in Copenhagen. The couple would have six children; four survived to adulthood and one, Aage, would become a well-known physics scientist as well. Aage shared with two others the 1975 Nobel Prize in Physics for his research on motion in atomic nuclei.