Aage Niels Bohr
Bohr in 1955
|Died||8 September 2009 87) (aged|
|Alma mater||University of Copenhagen|
|Known for||Geometry of atomic nuclei|
|Thesis||Rotational States of Atomic Nuclei (1954)|
Aage Niels Bohr (Danish: [ˈɔːwə ˌnels ˈboɐ̯ˀ] (
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions. Other forms of nuclear matter are also studied. Nuclear physics should not be confused with atomic physics, which studies the atom as a whole, including its electrons.
The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions for humankind in the field of physics. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others being the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.
Leo James Rainwater was an American physicist who shared the Nobel Prize in Physics in 1975 for his part in determining the asymmetrical shapes of certain atomic nuclei.
Aage Niels Bohr was born in Copenhagen on 19 June 1922, the fourth of six sons of the physicist Niels Bohr and his wife Margrethe Bohr (née Nørlund).His oldest brother, Christian, died in a boating accident in 1934, and his youngest, Harald, from childhood meningitis. Of the others, Hans became a physician; Erik, a chemical engineer; and Ernest, a lawyer and an Olympic athlete who played field hockey for Denmark at the 1948 Summer Olympics in London. The family lived at the Institute of Theoretical Physics at the University of Copenhagen, now known as the Niels Bohr Institute, where he grew up surrounded by physicists who were working with his father, such as Hans Kramers, Oskar Klein, Yoshio Nishina, Wolfgang Pauli and Werner Heisenberg. In 1932, the family moved to the Carlsberg Æresbolig, a mansion donated by Carl Jacobsen, the heir to Carlsberg breweries, to be used as an honorary residence by the Dane who had made the most prominent contribution to science, literature or the arts.
Copenhagen is the capital and most populous city of Denmark. As of July 2018, the city has a population of 777,218. It forms the core of the wider urban area of Copenhagen and the Copenhagen metropolitan area. Copenhagen is situated on the eastern coast of the island of Zealand; another small portion of the city is located on Amager, and is separated from Malmö, Sweden, by the strait of Øresund. The Øresund Bridge connects the two cities by rail and road.
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate causes of phenomena, and usually frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole. The field generally includes two types of physicists: experimental physicists who specialize in the observation of physical phenomena and the analysis of experiments, and theoretical physicists who specialize in mathematical modeling of physical systems to rationalize, explain and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies.
Niels Henrik David 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.
Bohr went to high school at Sortedam Gymnasiumin Copenhagen. In 1940, shortly after the German occupation of Denmark in April, he entered the University of Copenhagen, where he studied physics. He assisted his father, helping draft correspondence and articles related to epistemology and physics. In September 1943, word reached his family that the Nazis considered them to be Jewish, because Aage's grandmother, Ellen Adler Bohr, had been Jewish, and that they therefore were in danger of being arrested. The Danish resistance helped the family escape by sea to Sweden. Bohr arrived there in October 1943, and then flew to Britain on a de Havilland Mosquito operated by British Overseas Airways Corporation. The Mosquitoes were unarmed high-speed bomber aircraft that had been converted to carry small, valuable cargoes or important passengers. By flying at high speed and high altitude, they could cross German-occupied Norway, and yet avoid German fighters. Bohr, equipped with parachute, flying suit and oxygen mask, spent the three-hour flight lying on a mattress in the aircraft's bomb bay.
Epistemology is the branch of philosophy concerned with the theory of knowledge.
The rescue of the Danish Jews occurred during Nazi Germany's occupation of Denmark during World War II. On October 1, 1943, Nazi leader Adolf Hitler ordered Danish Jews to be arrested and deported. Despite great personal risk, the Danish resistance movement, with the assistance of many Danish citizens, managed to evacuate 7,220 of Denmark's 7,800 Jews, plus 686 non-Jewish spouses, by sea to nearby neutral Sweden.
The de Havilland DH.98 Mosquito is a British twin-engine shoulder-winged multi-role combat aircraft, introduced during the Second World War, unusual in that its frame is constructed mostly of wood. It was nicknamed The Wooden Wonder, or "Mossie". Lord Beaverbrook, Minister of Aircraft Production, nicknamed it "Freeman's Folly", alluding to Air Chief Marshal Sir Wilfred Freeman, who defended Geoffrey de Havilland and his design concept against orders to scrap the project. In 1941 it was one of the fastest operational aircraft in the world.
On arrival in London, Bohr rejoined his father, who had flown to Britain the week before.He officially became a junior researcher at the Department of Scientific and Industrial Research, but actually served as personal assistant and secretary to his father. The two worked on Tube Alloys, the British atomic bomb project. On 30 December 1943, they made the first of a number of visits to the United States, where his father was a consultant to the Manhattan Project. Due to his father's fame, they were given false names; Bohr became James Baker, and his father, Nicholas Baker. In 1945, the director of the Los Alamos Laboratory, Robert Oppenheimer, asked them to review the design of the modulated neutron initiator. They reported that it would work. That they had reached this conclusion put Enrico Fermi's concerns about the viability of the design to rest. The initiators performed flawlessly in the bombs used in the atomic bombings of Hiroshima and Nagasaki in August 1945.
The Department of Scientific and Industrial Research was a department of the British Government responsible for the organisation, development and encouragement of scientific and industrial research. At the outbreak of World War I, "Britain found ... it was dangerously dependent on enemy industries". At the request of the Board of Trade, the Board of Education prepared a White Paper under the chairmanship of Sir William McCormick. The DSIR was set up to fill the roles that the White Paper specified: "to finance worthy research proposals, to award research fellowships and studentships [in universities], and to encourage the development of research associations in private industry and research facilities in university science departments. [It] rapidly assumed a key role in coordinating government aid to university research. It maintained these roles until 1965. The annual budget during its first year, 1915, was £1,000,000.
Tube Alloys was the code name of the research and development programme authorised by the United Kingdom, with participation from Canada, to develop nuclear weapons during the Second World War. Starting before the Manhattan Project in the United States, the British efforts were kept classified, and as such had to be referred to by code even within the highest circles of government.
The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the actual bombs. The Army component of the project was designated the Manhattan District; Manhattan gradually superseded the official codename, Development of Substitute Materials, for the entire project. Along the way, the project absorbed its earlier British counterpart, Tube Alloys. The Manhattan Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly US$2 billion. Over 90% of the cost was for building factories and to produce fissile material, with less than 10% for development and production of the weapons. Research and production took place at more than 30 sites across the United States, the United Kingdom, and Canada.
In August 1945, with the war ended, Bohr returned to Denmark, where he resumed his university education, graduating with a master's degree in 1946, with a thesis concerned with some aspects of atomic stopping power problems.In early 1948, Bohr became a member of the Institute for Advanced Study in Princeton, New Jersey. While paying a visit to Columbia University, he met Isidor Isaac Rabi, who sparked in him an interest in recent discoveries related to the hyperfine structure of deuterium. This led to Bohr becoming a visiting fellow at Columbia from January 1949 to August 1950. While in the United States, Bohr married Marietta Soffer on 11 March 1950. They had three children: Vilhelm, Tomas and Margrethe.
Stopping power in nuclear and materials physics is defined as the retarding force acting on charged particles, typically alpha and beta particles, due to interaction with matter, resulting in loss of particle energy. Its application is important in areas such as radiation protection, ion implantation and nuclear medicine.
The Institute for Advanced Study (IAS) located 1 Einstein Drive, Princeton, New Jersey, in the United States, is an independent, postdoctoral research center for theoretical research and intellectual inquiry founded in 1930 by American educator Abraham Flexner, together with philanthropists Louis Bamberger and Caroline Bamberger Fuld.
Princeton is a municipality with a borough form of government in Mercer County, New Jersey, United States, that was established in its current form on January 1, 2013, through the consolidation of the Borough of Princeton and Princeton Township. As of the 2010 United States Census, the municipality's population was 28,572, reflecting the former township's population of 16,265, along with the 12,307 in the former borough.
By the late 1940s it was known that the properties of atomic nuclei could not be explained by then-current models such as the liquid drop model developed by Niels Bohr amongst others. The shell model, developed in 1949 by Maria Goeppert-Mayer and others, allowed some additional features to be explained, in particular the so-called magic numbers. However, there were also properties that could not be explained, including the non-spherical distribution of charge in certain nuclei.In a 1950 paper, James Rainwater of Columbia University suggested a variant of the drop model of the nucleus that could explain a non-spherical charge distribution. Rainwater's model postulated a nucleus like a balloon with balls inside that distort the surface as they move about. He discussed the idea with Bohr, who was visiting Columbia at the time, and had independently conceived the same idea, and had, about a month after Rainwater's submission, submitted for publication a paper that discussed the same problem, but along more general lines. Bohr imagined a rotating, irregular-shaped nucleus with a form of surface tension. Bohr developed the idea further, in 1951 publishing a paper that comprehensively treated the relationship between oscillations of the surface of the nucleus and the movement of the individual nucleons.
In nuclear physics and nuclear chemistry, the nuclear shell model is a model of the atomic nucleus which uses the Pauli exclusion principle to describe the structure of the nucleus in terms of energy levels. The first shell model was proposed by Dmitry Ivanenko in 1932. The model was developed in 1949 following independent work by several physicists, most notably Eugene Paul Wigner, Maria Goeppert Mayer and J. Hans D. Jensen, who shared the 1963 Nobel Prize in Physics for their contributions.
In nuclear physics, a magic number is a number of nucleons such that they are arranged into complete shells within the atomic nucleus. The seven most widely recognized magic numbers as of 2007 are 2, 8, 20, 28, 50, 82, and 126. For protons, this corresponds to the elements helium, oxygen, calcium, nickel, tin, lead and the hypothetical unbihexium, although 126 is so far only known to be a magic number for neutrons. Atomic nuclei consisting of such a magic number of nucleons have a higher average binding energy per nucleon than one would expect based upon predictions such as the semi-empirical mass formula and are hence more stable against nuclear decay.
In chemistry and physics, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines an isotope's mass number.
Upon his return to Copenhagen in 1950, Bohr began working with Ben Mottelson to compare the theoretical work with experimental data. In three papers, that were published in 1952 and 1953, Bohr and Mottelson demonstrated close agreement between theory and experiment; for example, showing that the energy levels of certain nuclei could be described by a rotation spectrum.They were thereby able to reconcile the shell model with Rainwater's concept. This work stimulated many new theoretical and experimental studies. Bohr, Mottelson and Rainwater were jointly awarded the 1975 Nobel Prize in Physics "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection". Because his father had been awarded the prize in 1922, Bohr became one of only four pairs of fathers and sons to win the Nobel Prize in Physics.
Only after doing his Nobel Prize-winning research did Bohr receive his doctorate from the University of Copenhagen, in 1954, writing his thesis on "Rotational States of Atomic Nuclei".Bohr became a professor at the University of Copenhagen in 1956, and, following his father's death in 1962, succeeded him as director of the Niels Bohr Institute, a position he held until 1970. He remained active there until he retired in 1992. He was also a member of the board of the Nordic Institute for Theoretical Physics (Nordita) from its inception in 1957, and was its director from 1975 to 1981. In addition to the Nobel Prize, he won the Dannie Heineman Prize for Mathematical Physics in 1960, the Atoms for Peace Award in 1969, H.C. Ørsted Medal in 1970, Rutherford Medal and Prize in 1972, John Price Wetherill Medal in 1974, and the Ole Rømer medal in 1976. Bohr and Mottelson continued to work together, publishing a two-volume monograph, Nuclear Structure. The first volume, Single-Particle Motion, appeared in 1969; the second, Nuclear Deformations, in 1975.
In 1972 he was awarded an honorary degree, doctor philos. honoris causa, at the Norwegian Institute of Technology, later part of Norwegian University of Science and Technology.
In 1981, Bohr became a founding member of the World Cultural Council.
His wife Marietta died on 2 October 1978.In 1981, he married Bente Scharff Meyer. His son, Tomas Bohr, is a Professor of Physics at the Technical University of Denmark, working in the area of fluid dynamics. Aage Bohr died in Copenhagen on 9 September 2009. He was survived by his second wife and children.
In atomic physics, the Rutherford–Bohr model or Bohr model or Bohr diagram, presented by Niels Bohr and Ernest Rutherford in 1913, is a system consisting of a small, dense nucleus surrounded by revolving electrons —similar to the structure of the Solar System, but with attraction provided by electrostatic forces rather than gravity. After the cubic model (1902), the plum-pudding model (1904), the Saturnian model (1904), and the Rutherford model (1911) came the Rutherford–Bohr model or just Bohr model for short (1913). The improvement to the Rutherford model is mostly a quantum physical interpretation of it. The model's key success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen. While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced. Not only did the Bohr model explain the reason for the structure of the Rydberg formula, it also provided a justification for its empirical results in terms of fundamental physical constants.
Felix Bloch was a Swiss-American physicist and Nobel physics laureate who worked mainly in the U.S. He and Edward Mills Purcell were awarded the 1952 Nobel Prize for Physics for "their development of new ways and methods for nuclear magnetic precision measurements." In 1954–1955, he served for one year as the first Director-General of CERN. Felix Bloch made fundamental theoretical contributions to the understanding of electron behavior in crystal lattices, ferromagnetism, and nuclear magnetic resonance.
Lise Meitner was an Austrian-Swedish physicist who worked on radioactivity and nuclear physics. Meitner, Otto Hahn and Otto Robert Frisch led the small group of scientists who first discovered nuclear fission of uranium when it absorbed an extra neutron; the results were published in early 1939. Meitner, Hahn and Frisch understood that the fission process, which splits the atomic nucleus of uranium into two smaller nuclei, must be accompanied by an enormous release of energy. Their research into nuclear fission helped to pioneer nuclear reactors to generate electricity as well as the development of nuclear weapons during World War II.
The Niels Bohr Institute is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics.
Bohr usually refers to:
Christian Harald Lauritz Peter Emil Bohr (1855–1911) was a Danish physician, father of the physicist and Nobel laureate Niels Bohr, as well as the mathematician and football player Harald Bohr and grandfather of another physicist and nobel laureate Aage Bohr. He married Ellen Adler in 1881.
George Charles de Hevesy was a Hungarian radiochemist and Nobel Prize in Chemistry laureate, recognized in 1943 for his key role in the development of radioactive tracers to study chemical processes such as in the metabolism of animals. He also co-discovered the element hafnium.
Ben Roy Mottelson is an American-born Danish nuclear physicist. He won the 1975 Nobel Prize in Physics for his work on the non-spherical geometry of atomic nuclei.
Val Logsdon Fitch was an American nuclear physicist who, with co-researcher James Cronin, was awarded the 1980 Nobel Prize in Physics for a 1964 experiment using the Alternating Gradient Synchrotron at Brookhaven National Laboratory that proved that certain subatomic reactions do not adhere to fundamental symmetry principles. Specifically, they proved, by examining the decay of K-mesons, that a reaction run in reverse does not retrace the path of the original reaction, which showed that the reactions of subatomic particles are not indifferent to time. Thus the phenomenon of CP violation was discovered. This demolished the faith that physicists had that natural laws were governed by symmetry.
Gaja Alaga was a Croatian theoretical physicist who specialised in nuclear physics.
Otto Robert Frisch FRS was an Austrian physicist who worked on nuclear physics. With Lise Meitner he advanced the first theoretical explanation of nuclear fission and first experimentally detected the fission by-products. Later, with his collaborator Rudolf Peierls he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940.
The Columbia University Physics Department includes approximately 40 faculty members teaching and conducting research in the areas of astrophysics, high energy nuclear physics, high energy particle physics, atomic-molecular-optical physics, condensed matter physics, and theoretical physics.
The Nordic Institute for Theoretical Physics, or Nordita, is an international organisation for research in theoretical physics. It was established in 1957 by Niels Bohr and the Swedish physicist Torsten Gustafson. Nordita was originally located at the Niels Bohr Institute in Copenhagen (Denmark), but moved to the AlbaNova University Centre in Stockholm (Sweden) on 1 January 2007. The main research areas at Nordita are astrophysics, hard and soft condensed matter physics, and high-energy physics.
Gerald Edward "Gerry" Brown was an American theoretical physicist who worked on nuclear physics and astrophysics. Since 1968 he had been a professor at the Stony Brook University. He was a distinguished professor emeritus of the C. N. Yang Institute for Theoretical Physics at Stony Brook University.
The Bohr family is a Danish family of scientists, scholars and amateur sportsmen.
The discovery of the neutron and its properties was central to the extraordinary developments in atomic physics in the first half of the 20th century. Early in the century, Ernest Rutherford developed a crude model of the atom, based on the gold foil experiment of Hans Geiger and Ernest Marsden. In this model, atoms had their mass and positive electric charge concentrated in a very small nucleus. By 1920 chemical isotopes had been discovered, the atomic masses had been determined to be (approximately) integer multiples of the mass of the hydrogen atom, and the atomic number had been identified as the charge on the nucleus. Throughout the 1920s, the nucleus was viewed as composed of combinations of protons and electrons, the two elementary particles known at the time, but that model presented several experimental and theoretical contradictions.
George F. Bertsch is an American nuclear physicist.
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