Niels Henrik David Bohr ( Danish: Ã, [nels' bo ???] October 7, 1885 - November 18, 1962) was a Danish physicist who made a fundamental contribution to understanding atomic structure and quantum theory, where he received the Nobel Prize in Physics in 1922. Bohr is also a philosopher and promoter of scientific research.
Bohr developed the Bohr model of the atom, in which he proposed that the electron energy levels are discrete and that electrons rotate in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another. Although the Bohr model has been replaced by other models, its basic principle remains in effect. He defines the principle of complementarity: that things can be analyzed separately in terms of conflicting properties, such as behaving as waves or particle flow. The idea of ​​complementarity dominates Bohr's thinking in 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. Bohr guided and collaborated with physicists including Hans Kramers, Oskar Klein, George de Hevesy, and Werner Heisenberg. He predicted the existence of a new zirconium element, named hafnium, after the Latin name for Copenhagen, where it was found. Then, the element of the bohrium is named after its name.
During the 1930s, Bohr helped refugees from Nazism. After Denmark was occupied by Germany, he held a famous meeting with Heisenberg, who has been the head of the German nuclear weapons project. In September 1943, the word reached Bohr that he would be captured by Germany, and he fled to Sweden. From there, he was flown to England, where he joined the British Tube Alloys nuclear weapons project, and was part of the British mission to the Manhattan Project. After the war, Bohr called for international cooperation on nuclear energy. He was involved with the formation of CERN and the Research Establishment RisÃÆ'¸ Danish Atomic Energy Commission and became the first chairman of the Nordic Institute for Theoretical Physics in 1957.
Video Niels Bohr
Initial years
Bohr was born in Copenhagen, Denmark, on October 7, 1885, the second child of three children from Christian Bohr, a professor of physiology at the University of Copenhagen, and Ellen Adler Bohr, who belongs to a wealthy Danes rich Jewish family in banking and parliamentary circles. She has an older sister, Jenny, and Harald's brother. Jenny became a teacher, while Harald became a mathematician and Olympic footballer who played for Denmark's national team at the 1908 Summer Olympics in London. Bohr is a passionate football player as well, and the two brothers play several matches for the Copenhagen Academy Club Academy Boldklub, with Bohr as the goalkeeper.
Bohr was educated at Gammelholm Latin School, beginning when he was seven years old. In 1903, Bohr enrolled as a scholar at the University of Copenhagen. His department was physics, which he studied under Professor Christian Christiansen, the only university physics professor at the time. He also studied astronomy and mathematics under Professor Thorvald Thiele, and philosophy under Professor Harald HÃÆ'¸ffding, a friend of his father.
In 1905, a gold medal competition was sponsored by the Royal Danish Academy of Sciences and Letters to investigate a method for measuring liquid surface tones that Lord Rayleigh had proposed in 1879. This included measuring the oscillation frequency of the radius of a water jet. Bohr conducted a series of experiments using his father's laboratory at the university; the university itself does not have a physics laboratory. To complete his experiment, he had to make his own glass, creating a test tube with the necessary elliptical cross-section. He transcends the original task, incorporating improvements into Rayleigh's theory and methods, taking into account the viscosity of water, and by working with limited amplitude, not just very small ones. His essay, which he delivered at the last minute, won the prize. He then submitted a better version of the newspaper to the Royal Society in London for publication in the Philosophical Transactions of the Royal Society.
Harald became the first of two Bohr brothers to earn a master's degree, which he earned for mathematics in April 1909. Niels needed nine more months to earn his master's degree. Students must submit a thesis on the subject assigned by their supervisor. Bohr's supervisor was a Christian, and the topic he chose was the electron theory of metal. Bohr went on to describe his master thesis in his much larger Doctor of Philosophy thesis. He observes the literature on this issue, sets the model postulated by Paul Drude and elaborated by Hendrik Lorentz, in which electrons in metals are considered to behave like gases. Bohr extends the Lorentz model, but still can not explain phenomena such as the Hall effect, and concludes that electron theory can not fully explain the magnetic properties of metals. The thesis was accepted in April 1911, and Bohr made his formal defense on 13 May. Harald had received his doctorate the previous year. Bohr's thesis was a breakthrough, but it attracted little interest outside Scandinavia because it was written in Danish, a requirement of the University of Copenhagen at the time. In 1921, the Dutch physicist, Hendrika Johanna van Leeuwen, independently obtained the theorem from Bohr's thesis, now known as Bohr-van Leeuwen's theorem.
In 1910, Bohr met Margrethe NÃÆ'¸rlund, brother of the Niels mathematician Erik NÃÆ'¸rlund. Bohr resigned from his membership in the Danish Church on April 16, 1912, and he and Margrethe married in a civil ceremony at the town hall in Slagelse on 1 August. Years later, his brother Harald also left the church before marriage. Bohr and Margrethe had six sons. The eldest, Christian, died in a boat accident in 1934, and the other, Harald, died of meningitis in childhood. Aage Bohr became a successful physicist, and in 1975 was awarded the Nobel Prize in physics, like his father. Hans Bohr became a doctor; Erik Bohr, a chemical engineer; and Ernest, a lawyer. Like his uncle Harald, Ernest Bohr became an Olympic athlete, playing hockey in Denmark at the 1948 Summer Games in London.
Maps Niels Bohr
Physics
Bohr Model
In September 1911, Bohr, backed by a fellowship of the Carlsberg Foundation, went to England. At that time, where most of the theoretical work on the structure of atoms and molecules is being done. He met J. J. Thomson from the Cavendish Laboratory and Trinity College, Cambridge. He attended lectures on electromagnetism given by James Jeans and Joseph Larmor, and did research on cathode rays, but failed to impress Thomson. He was more successful with young physicists such as William Lawrence Bragg Australia, and Ernest Rutherford of New Zealand, whose 1911 atomic model Rutherford had challenged the model of Thomson pudding in 1904. Bohr accepted an invitation from Rutherford to undertake post-doctoral work at Victoria University of Manchester , where Bohr meets George de Hevesy and Charles Galton Darwin (called Bohr as "the real grandson of Darwin").
Bohr returned to Denmark in July 1912 for his marriage, and toured England and Scotland on his honeymoon. Upon his return, he became a privatdocent at the University of Copenhagen, lecturing on thermodynamics. Martin Knudsen listed Bohr's name for a guide , approved in July 1913, and Bohr then began teaching medical students. Three of his papers, which later became famous as "trilogy", were published in Philosophical Magazine in July, September and November of that year. He adapted Rutherford's nuclear structure to Max Planck's quantum theory and created the Bohr atomic model.
The planetary model of the atom is not new, but Bohr's treatment is. Taking a 1912 paper by Darwin on the role of electrons in the interaction of alpha particles with nuclei as his starting point, he advanced the theory of electrons that run in orbit around the nucleus of the atom, with the chemical properties of each element greatly determined by the number of electrons in the orbit outside its atom. He introduced the idea that electrons could fall from high-energy orbit to lower, in the process of emitting discrete quantum energy. This becomes the basis for what is now known as the old quantum theory.
Pada 1885, Johann Balmer telah datang dengan seri Balmer-nya untuk menggambarkan garis spektrum yang terlihat dari atom hidrogen:
where? is the wavelength of the light absorbed or emitted and R H is the Rydberg constant. Balmer's formula is reinforced by the discovery of additional spectral lines, but for thirty years, no one can explain why it worked. In his first paper trilogy, Bohr was able to get it from his model:
where m e is the mass of the electron, e is the load, h is the Planck constant and is atomic atomic number (1 for hydrogen).
The first hurdle model is the Pickering series, a line that does not fit the Balmer formula. When challenged by Alfred Fowler, Bohr replies that they are caused by ionized helium, a helium atom with only one electron. The Bohr model was found to work for such ions. Many old physicists, such as Thomson, Rayleigh and Hendrik Lorentz, disliked the trilogy, but the younger generation, including Rutherford, David Hilbert, Albert Einstein, Enrico Fermi, Max Born and Arnold Sommerfeld saw it as a breakthrough. Trilogy acceptance is entirely due to its ability to explain phenomena that inhibit other models, and to predict results that are then verified by the experiment. Currently, the Bohr atom model has been replaced, but it is still the most famous atomic model, as it often appears in the physics and chemistry of high school.
Bohr did not enjoy teaching medical students. He decides to return to Manchester, where Rutherford has offered him a job as a reader in place of Darwin, whose term of office has ended. Bohr accepted. He took a leave of absence from the University of Copenhagen, which he started by taking a holiday in Tyrol with his brother Harald and aunt Hanna Adler. There, he visited the University of GÃÆ'¶ttingen and Ludwig Maximilian University of Munich, where he met Sommerfeld and organized a seminar on trilogy. The First World War broke out when they were in Tyrol, making it very difficult to travel back to Denmark and Bohr's next trip with Margrethe to England, where he arrived in October 1914. They stayed until July 1916, by which time he had been appointed to the Chief of Theoretical Physics at the University of Copenhagen, a position created especially for him. His doctorate was abolished at the same time, so he still had to teach physics to medical students. The new professors were officially introduced to King Christian X, who expressed his joy at meeting such a famous soccer player.
Institute of Physics
In April 1917, Bohr began a campaign to establish the Theoretical Physics Institute. He gained support from the Danish government and the Carlsberg Foundation, and considerable contributions were also made by industrial and private donors, many of them Jewish. Legislation establishing the Institute was passed in November 1918. Now known as the Niels Bohr Institute, it was opened on March 3, 1921, with Bohr as its director. His family moved into an apartment on the first floor. The Bohr Institute serves as a focal point for researchers in quantum mechanics and related subjects in the 1920s and 1930s, when most of the world's famous theoretical physicists spend some time in the company. Early arrivals include Hans Kramers from the Netherlands, Swedish Oskar Klein, George de Hevesy from Hungary, Wojciech Rubinowicz from Poland and Svein Rosseland from Norway. Bohr became greatly appreciated as a delightful host and a prominent partner. Klein and Rosseland published the Institute's first publication even before it was opened.
The Bohr model works well for hydrogen, but can not explain the more complex elements. In 1919, Bohr moved away from the idea that electrons orbit the nucleus and develop heuristics to describe it. Rare earth elements cause specific classification problems for chemists, because they are very similar chemically. Important developments occurred in 1924 with Wolfgang Pauli's discovery of Pauli exclusionary principles, which placed the Bohr model on a strong theoretical footing. Bohr can then state that the undiscovered element (72) is not a rare earth element, but an element with chemical properties similar to zirconium. He was soon challenged by the French chemist Georges Urbain, who claimed to have found a rare earth element 72, which he called "celtium". At the Institut in Copenhagen, Dirk Coster and George de Hevesy took on the challenge of proving that Bohr was right and Urbain was wrong. Starting with a clear idea of ​​the chemical properties of an unknown element greatly simplifies the search process. They went through a sample from the Copenhagen Mineralogical Museum looking for a zirconium-like element and soon found it. The element, which they named hafnium ( Hafnia to Latin name for Copenhagen) was more common than gold.
In 1922, Bohr was awarded the Nobel Prize in Physics "for his services in the investigation of atomic structures and radiation emanating from them". The award thus recognized both the Trilogy and the beginning of leading his work in the emerging fields of quantum mechanics. For his Nobel lecture, Bohr gave a comprehensive survey audience what came to be known about the atomic structure, including the principle of correspondence, which he had formulated. It states that the behavior of systems described by quantum theory reproduces classical physics within the limits of large quantum numbers.
Compton's invention scattered by Arthur Holly Compton in 1923 convinced most physicists that light consists of photons, and that energy and momentum are conserved in a collision between electrons and photons. In 1924, Bohr, Kramers and John C. Slater, an American physicist working at the Institut in Copenhagen, proposed the Bohr-Kramers-Slater (BKS) theory. It is more of a program than a full physical theory, because the ideas it develops are not done quantitatively. The BKS theory is the last attempt to understand the interaction of matter and electromagnetic radiation on the basis of the old quantum theory, in which quantum phenomena are treated by imposing quantum restrictions on the classical wave description of the electromagnetic field.
Modeling atomic behavior under the incidence of electromagnetic radiation using a "virtual oscillator" at absorption and emission frequencies, rather than different (different) frequencies of the Bohr orbit, causes Max Born, Werner Heisenberg and Kramers to explore different mathematical models. They lead to the development of matrix mechanics, the first form of modern quantum mechanics. The BKS theory also generates discussion of, and new attention, difficulties in the foundations of the old quantum theory. The most provocative BKS element - that momentum and energy need not be preserved in any interaction, but only statistically - is immediately shown to be contrary to experiments conducted by Walther Bothe and Hans Geiger. In light of these results, Bohr told Darwin that "there is nothing to do but to give our revolutionary efforts an honorable cemetery".
Quantum mechanics
The introduction of a spin by George Uhlenbeck and Samuel Goudsmit in November 1925 is a milestone. The following month, Bohr went to Leiden to attend the 50th birthday celebration Hendrick Lorentz received his doctorate. When the train stopped in Hamburg, he was greeted by Wolfgang Pauli and Otto Stern, who asked for his opinion on the spin theory. Bohr indicates that he has concerns about the interaction between the electrons and the magnetic field. When he arrived in Leiden, Paul Ehrenfest and Albert Einstein told Bohr that Einstein had solved this problem using relativity. Bohr then asked Uhlenbeck and Goudsmit put this into their paper. So when he met with Werner Heisenberg and Pascual Jordan in GÃÆ'¶ttingen on his way back, he had become, in his own words, "a prophet of the gospel of an electron magnet".
Heisenberg first came to Copenhagen in 1924, then returned to Göttingen in June 1925, shortly afterwards developing the basic mathematical quantum mechanics. When he showed the results to Max Born in GÃÆ'¶ttingen, Born realized that they could be expressed using a matrix. This work drew the attention of British physicist Paul Dirac, who came to Copenhagen for six months in September 1926. Austrian physicist Erwin SchrÃÆ'¶dinger also visited in 1926. His efforts in explaining quantum physics in classical terms use the impressive wave mechanics of Bohr, who believe it contributed "so much clarity and mathematical simplicity that represents a major advance over all forms of precise quantum mechanics".
When Kramers left the Institute in 1926 to take a seat as professor of theoretical physics at Utrecht University, Bohr arranged for Heisenberg to return and take the Kramers place as a lector at the University of Copenhagen. Heisenberg worked in Copenhagen as a university professor and Bohr's assistant from 1926 to 1927.
Bohr became convinced that light behaves like waves and particles, and in 1927, experiments confirmed De Broglie's hypothesis that matter (such as electrons) also behaves like waves. He understands the philosophical principle of complementarity: that they seem to have mutually exclusive properties, such as the wave or flow of particles, depending on the experimental frame. He felt that it was not fully understood by professional philosophers.
In Copenhagen in 1927, Heisenberg developed the principle of uncertainty, which Bohr adhered to. In a paper presented at the Volta Conference in Como in September 1927, he showed that the principle of uncertainty can stem from classical arguments, without quantum or matrix terminology. Einstein favored the determinism of classical physics over the new probabilistic quantum physics that he himself had contributed. The philosophical issues emerging from the new aspects of quantum mechanics are the subject of a widely celebrated discussion. Einstein and Bohr have good arguments about these issues throughout their lives.
In 1914, Carl Jacobsen, the heir of Carlsberg's brewery, left his mansion to live by Dane, who has made the greatest contribution to science, literature or art, as a dwelling place of honor (Danish: ÃÆ' â € resbolig ). Harald HÃÆ'¸ffding was the first resident, and after his death in July 1931, the Danish Royal Academy of Sciences and Literature gave Bohr residence. He and his family moved there in 1932. He was elected president of the Academy on March 17, 1939.
In 1929, the phenomenon of beta decay prompted Bohr to again suggest that energy conservation laws were abandoned, but hypothetical neutrino Enrico Fermi and the subsequent 1932 invention of neutrons gave another explanation. This prompted Bohr to create a new theory of nucleus compounds in 1936, which explains how neutrons can be captured by the nucleus. In this model, the nucleus may change shape like a drop of fluid. He worked on this with a new collaborator, Danish physicist Fritz Kalckar, who died suddenly in 1938.
The discovery of nuclear fission by Otto Hahn in December 1938 (and his theoretical explanation by Lise Meitner) aroused a strong interest among physicists. Bohr brought the news to the United States where he opened the 5th Washington Conference on Theoretical Physics with Fermi on January 26, 1939. When Bohr told George Placzek that this solved all the mysteries of the transuranic elements, Placzek told him that what remained: neutron uranium energy does not match its decay. Bohr thought about it for a few minutes and then announced to Placzek, LÃÆ' Â © on Rosenfeld and John Wheeler that "I have understood everything." Based on the liquid drop model of the nucleus, Bohr concluded that it is a more abundant uranium-235 isotope rather than uranium-238 which is primarily responsible for fission with thermal neutrons. In April 1940, John R. Dunning pointed out that Bohr was right. Meanwhile, Bohr and Wheeler developed the theoretical treatment they published in a September 1939 paper on "Nuclear Fission Mechanism".
Philosophy
Bohr read the 19th century Danish existentialist philosopher SÃÆ'¸ren Kierkegaard. Richard Rhodes argues in the The Atomic Bombing that Bohr was influenced by Kierkegaard through HÃÆ'¸ffding. In 1909, Bohr sent his sister Kierkegaard Stages on the Way of Life as a birthday gift. In the attached letter, Bohr writes, "This is the only thing I have to send home, but I do not believe it will be so easy to find something better... I even think it is one of the most fun things that I've read. "Bohr enjoys Kierkegaard's language and literary style, but mentions that he has some disagreements with Kierkegaard's philosophy. Some biographers Bohr suggested that this contradiction stems from Kierkegaard's advocacy of Christianity, while Bohr is an atheist.
There are several disagreements over the extent to which Kierkegaard influenced Bohr's philosophy and science. David Favrholdt argues that Kierkegaard had minimal influence over Bohr's work, taking Bohr's statement of disagreement with Kierkegaard at face value, while Jan Faye argues that one can disagree with the content of the theory when accepting public places and structures.
Nazism and the Second World War
The rise of Nazism in Germany prompted many scholars to flee from their country, either because they were Jews or because they were political opponents of the Nazi regime. In 1933, the Rockefeller Foundation made funds to help support refugee academics, and Bohr discussed the program with Rockefeller Foundation President Max Mason in May 1933 during a visit to the United States. Bohr offered temporary refugees at the Institute, provided them with financial support, arranged for them to be awarded a scholarship from the Rockefeller Foundation, and finally found them a place in institutions around the world. Those he helped include Guido Beck, Felix Bloch, James Franck, George de Hevesy, Otto Frisch, Hilde Levi, Lise Meitner, George Placzek, Eugene Rabinowitch, Stefan Rozental, Erich Ernst Schneider, Edward Teller, Arthur von Hippel and Victor Weisskopf.
In April 1940, at the beginning of the Second World War, Nazi Germany invaded and occupied Denmark. To prevent Germany from finding the Nobel gold medals Max von Laue and James Franck, Bohr has de Hevesy disperse them in aqua regia. In this form, they are kept on shelves at the Institute until after the war, when gold is precipitated and the medal is struck back by the Nobel Foundation. Bohr continued to run the Institute, but all the foreign scholars left.
Meet Heisenberg
Bohr was aware of the possibility of using uranium-235 to make atomic bombs, referring to lectures in England and Denmark shortly before and after the war began, but he did not believe it was technically feasible to extract sufficient quantities of uranium-235. In September 1941, Heisenberg, who had been head of the German nuclear energy project, visited Bohr in Copenhagen. During this meeting the two men took private time outside, whose contents have caused much speculation, as both gave different accounts. According to Heisenberg, he began discussing nuclear energy, morality, and war, which Bohr seems to have caused by ending the conversation unexpectedly while not instructing Heisenberg about his own opinion. Ivan Supek, one of Heisenberg's disciples and friends, claimed that the main subject of the meeting was Carl Friedrich von WeizsÃÆ'¤cker, who had proposed to try to persuade Bohr to mediate peace between Britain and Germany.
In 1957, Heisenberg wrote to Robert Jungk, who then worked on the book. More brilliant than a Thousand Sun: Personal History of the Atomic Scientists. Heisenberg explained that he had visited Copenhagen to communicate with Bohr the views of some German scientists, that the production of nuclear weapons was made possible by great efforts, and this raised the enormous responsibility of the world's scientists on both sides. When Bohr saw Jungk's portrayal in the translation of the book in Danish, he wrote (but never sent) a letter to Heisenberg, stating that he never understood the purpose of Heisenberg's visit, surprised by Heisenberg's opinion that Germany would win the war, and that atomic weapons could determine.
Michael Frayn's 1998 show Copenhagen explored what might happen at the 1941 meeting between Heisenberg and Bohr. The BBC television drama version premiered on September 26, 2002, with Stephen Rea as Bohr, and Daniel Craig as Heisenberg. The same previous meeting has been dramatized by the BBC [Science Horizon] science documentary series in 1992, with Anthony Bate as Bohr, and Philip Anthony as Heisenberg. The meeting was also dramatized in Norwegian/Danish/English miniseries The Heavy Water War .
Manhattan Project
In September 1943, the word reached Bohr and his brother Harald that the Nazis regarded their families as Jews, because their mother was Jewish, and therefore they were in danger of being arrested. Danish resistance helped Bohr and his wife escape by sea to Sweden on 29 September. The next day, Bohr persuaded King Gustaf V of Sweden to make Sweden's public desire to grant asylum to Jewish refugees. On October 2, 1943, Swedish radio broadcasts that Sweden was ready to offer asylum, and the mass rescue of Danish Jews by compatriots followed quickly afterwards. Some historians claim that Bohr's actions lead directly to mass rescue, while others say that, although Bohr did everything he could for his fellow countrymen, his actions were not a decisive influence on the wider event. Finally, more than 7,000 Danish Jews fled to Sweden.
When Bohr's breakout news reached England, Lord Cherwell sent a telegram to Bohr asking him to come to England. Bohr arrived in Scotland on October 6 at a de Havilland Mosquito operated by British Overseas Airways Corporation (BOAC). Mosquitos are high-speed bomber aircraft without weapons that have been converted to carry valuable small cargoes or important passengers. By flying at high speed and high altitude, they could cross the occupied Norway, but avoid the German warriors. Bohr, equipped with parachutes, flying suits and oxygen masks, spent a three-hour flight lying on a mattress in the plane's bomb bay. During the flight, Bohr did not use his flying helmet because it was too small, and consequently did not hear the pilot intercom instruction to power its oxygen supply as the plane climbed to a high altitude to surpass Norway. He collapsed from oxygen starvation and only came back to life when the plane descended into the lowlands of the North Sea. Bohr's son, Aage, followed his father to England on another flight a week later, and became his personal assistant.
Bohr was warmly received by James Chadwick and Sir John Anderson, but for security reasons Bohr was not seen. He was given an apartment at St James's Palace and an office with the British Tube Alloys nuclear weapons development team. Bohr was astonished at the amount of progress that had been made. Chadwick arranged for Bohr to visit the United States as a consultant for Tube Alloys, with Aage as his assistant. On December 8, 1943, Bohr arrived in Washington, DC, where he met the director of the Manhattan Project, Brigadier General Leslie R. Groves, Jr. He visited Einstein and Pauli at the Institute for Advanced Study in Princeton, New Jersey, and went to Los Alamos in New Mexico, where nuclear weapons were being designed. For security reasons, he went by the name "Nicholas Baker" in the United States, while the Aage became "James Baker". In May 1944, the Danish Resistance newspaper De frie Danske reported that they had learned that the 'famous son of Denmark Professor Niels Bohr' in October of the previous year had left his country via Sweden to London and from there went to Moscow from where he could be assumed to support war effort.
Bohr does not remain at Los Alamos, but pays a series of extended visits over the next two years. Robert Oppenheimer praised Bohr by acting "as a scientific father figure for younger men", notably Richard Feynman. Bohr was quoted as saying, "They do not need my help in making atomic bombs." Oppenheimer gave Bohr an appreciation for his important contribution to the work of a modulated neutron initiator. "This device remains a stubborn puzzle," said Oppenheimer, "but in early February 1945 Niels Bohr clarified what to do."
Bohr admitted early on that nuclear weapons would change international relations. In April 1944, he received a letter from Peter Kapitza, written several months earlier when Bohr was in Sweden, inviting him to come to the Soviet Union. The letter convinces Bohr that the Soviets are aware of the Anglo-American project, and will try to catch up. He sent Kapitza a non-committal response, which he showed to the British authorities before being sent. Bohr met Churchill on May 16, 1944, but found that "we do not speak the same language". Churchill disagreed with the idea of ​​openness to the Russians to the point he wrote in a letter: "It seems that Bohr should be limited or at least made to see that he is very close to mortal evil."
Oppenheimer suggested that Bohr visit President Franklin D. Roosevelt to convince him that the Manhattan Project should be shared with the Soviets in the hope of speeding up the outcome. Bohr's friend, Supreme Court Justice Felix Frankfurter, told President Roosevelt about Bohr's opinion, and their meeting took place on August 26, 1944. Roosevelt suggested that Bohr return to England to try to win British approval. When Churchill and Roosevelt met at Hyde Park on September 19, 1944, they rejected the idea of ​​telling the world about the project, and their conversation maiden mosaic contained a rider that "questions should be made about Professor Bohr's activities and the steps taken to ensure that he responsible for no information leak, especially to Russians ".
In June 1950, Bohr delivered an "Open Letter" to the United Nations calling for international cooperation on nuclear energy. In the 1950s, after the first Soviet nuclear weapons test, the International Atomic Energy Agency was formed in accordance with Bohr's suggestion. In 1957 he received the first Atoms for Peace award.
Next year
With the end of the war, Bohr returned to Copenhagen on 25 August 1945, and was re-elected as President of the Danish Academy of Arts and Sciences on 21 September. At the Academy memorial meeting on October 17, 1947 for King Christian X, who died in April, the new king, Frederick IX, announced that he bestowed the Order of the Elephant at Bohr. This award is usually given only to nobles and heads of state, but the king says that it is respected not only Bohr personally, but Danish science. Bohr designed his own symbol that displayed taijitu (the symbols of yin and yang) and the motto in Latin: contraria sunt complementa contrarian sunt complementa, is complementary ".
The Second World War shows that science and physics in particular, now require considerable financial and material resources. To avoid brain drain to the United States, twelve European countries united to create CERN, a research organization along the lines of national laboratories in the United States, designed to undertake a Great Science project beyond the resources of just one of them. An immediate question arises regarding the best location for the facility. Bohr and Kramers felt that the Institute in Copenhagen would be the ideal place. Pierre Auger, who arranged preliminary discussions, disagreed; he feels that both Bohr and his Institute have passed his prime, and that Bohr's presence will overshadow the others. After a long debate, Bohr promised his support to CERN in February 1952, and Geneva was chosen as the site in October. CERN Theory Group was headquartered in Copenhagen until their new accommodation in Geneva was ready in 1957. Victor Weisskopf, later to become Director General of CERN, summed up Bohr's role, saying that "there were other figures who started and understood CERN's ideas. others will not be enough, however, if someone with his posture does not support him. "
Meanwhile, the Scandinavian countries established the Nordic Institute for Theoretical Physics in 1957, with Bohr as its chairman. He was also involved with the establishment of the Research Establishment RisÃÆ'¸ Danish Atomic Energy Commission, and served as the first chairman of February 1956.
Bohr died of heart failure at his home in Carlsberg on 18 November 1962. He was cremated, and his ashes were buried in a family gang at Assistens Cemetery in the NÃÆ'¸rrebro section of Copenhagen, along with his parents, his brother Harald, and his son Christian. Years later, the ashes of his wife were also buried there. On October 7, 1965, on his 80th birthday, The Institute of Theoretical Physics at the University of Copenhagen was officially renamed the so-called unofficially for many years: the Niels Bohr Institute.
Accolades
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