Hans Albrecht Bethe (Bethe Hans Albrecht)( German-American physicist, Nobel Prize in Physics, 1967)
Comments for Hans Albrecht Bethe (Bethe Hans Albrecht)
Biography Hans Albrecht Bethe (Bethe Hans Albrecht)
genus. July 2, 1906
. German-American physicist Hans Albrecht Bethe was born in Strasbourg, . Alsace-Lorraine (at that time belonged to Germany), . and was the only child of Theodore Julius Albrecht Bethe, . seen physiologist and professor of medicine, . and Anna (nee Kuhn) from the family of Professor Bethe,
. From 1915 to 1924. B. studied at the Goethe Gymnasium in Frankfurt, followed by two years was a student at the University of Frankfurt. I studied two and a half years in graduate school, University of Munich under the guidance of Arnold Sommerfeld, who made a great contribution to modern physics, he received his doctorate in theoretical physics in 1928
Another graduate student B. expressed interest in quantum mechanics, its mathematical theory describing the interaction between matter and radiation. Formulated in the mid 20-ies. Werner Heisenberg, Erwin Schrodinger and P.A.M. Dirac, . it was the result of earlier research in the field of quantum theory: Max Planck discovered, . that radiation is not continuous, . but consists of discrete portions of energy, . subsequently called quanta, Albert Einstein showed, . that photons, . quanta of light (electromagnetic radiation), . when the photoelectric effect act like particles, Niels Bohr used quantum theory to describe the atomic energy levels, . responsible for the characteristic spectra of the emitted radiation, and finally, . Louis de Broglie put forward a bold assumption, . that if the radiation (light) could behave like a particle, . then the particle can behave like a wave,
. The idea of de Broglie was experimentally confirmed by Clinton J. Davisson, who discovered the wave behavior of electrons. In 1927, Mr.. B. wrote a scientific article on the diffraction of electrons by crystals, in which to explain the observations of Davisson used quantum mechanics, yet not understood at that time, most physicists. B. was one of the first scientists to conclusively demonstrate the application of new theory.
After receiving his doctorate, B. worked in 1928 ... 1929. professor of physics at the universities of Frankfurt and Stuttgart. He was appointed lecturer at the University of Munich in 1929, but most of the time over the next three years, held in Cambridge (England), where he met Ernest Rutherford, and in Rome, where he worked with Enrico Fermi. He also established contact with Niels Bohr. Over By this time B. developed using the mathematical technique known as group theory, to determine the quantum-mechanical behavior of crystals. Having made a significant contribution to the theory of atomic structure, B. in the early 30-ies. started the theoretical study of the process of rapid energy loss of particles passing through matter, for that matter, he returned periodically throughout his scientific activities.
. Appointed assistant professor at the University of Tц╪bingen in 1932, BA, whose mother was Jewish, lost this position 'in the following year, after the publication of Hitler became chancellor of Germany, anti-Semitic decrees
. B. left Germany in 1933, the year he lectured at Manchester University in England, and then in 1934 ... 1935. became a Member of the University of Bristol. In 1935. he became an assistant professor at Cornell University in Ithaca (New York), and then full professor in 1937
Here B. returned to the study of nuclear physics. In 1936, Mr.. in collaboration with the American physicist Robert F. Becherom and ms. Livingston B. written several extensive works, which were summed known at that time results in this, then still in its infancy, the field. Three journal issue with these articles immediately became a classic and more than 20 years, is widely used as a basic textbook on nuclear physics.
In 1938. a conference on theoretical physics in Washington (DC) account B. drew one unresolved question of the nature of energy the sun and other stars. Astronomers have gained a lot of information about the extremely high temperatures and other stellar characteristics, and concluded that the source of energy should be the nature of thermonuclear. However, they could not determine the reaction, which would give the quantitative characteristics that are consistent with the observed radiation, size, age and other properties of stars. Quickly learn to astronomical data and use their encyclopedic knowledge of nuclear physics, B. solved this problem for six weeks.
. First German astronomer Carl Friedrich von Weizsц╓cker was proposed to explain this issue a synthesis of two protons (hydrogen nuclei, . in large quantities inside the Sun), . which yields a deuterium (also called heavy hydrogen, . nucleus which contains protons and neutrons) and the energy is released in the form of a positron (positive electron) and neutrinos (uncharged particles),
. Protons are positively charged, while the number of protons in the nucleus defines the element (hydrogen nucleus contains one proton, but can also contain neutrons whose mass is approximately equal to the mass of the proton, but they do not carry a charge). In the synthesis of two protons emitted by a positive particle (positron), resulting in one of the protons into a neutron. B. considered solar characteristics such as temperature, density, composition, and the expected rate of reaction, and calculated that the fusion reaction is precisely at such a speed, which provides the observed release of energy the sun. However, his calculations showed that for stars more massive than the Sun, the reaction must involve heavier nuclei.
For massive stars B. proposed six-carbon-nitrogen cycle. In the first step of carbon with atomic weight 12 (the most common and stable form of carbon with 6 protons and 6 neutrons in the nucleus) captures a proton and turns into a nitrogen-13 (7 protons, 6 neutrons) and emitting energy in the form of gamma rays. Unstable nitrogen-13 decays by emitting a positron (which transforms a proton into a neutron) and neutrino and turning to carbon-13 (6 protons, 7 neutrons). Nitrogen-14 in turn captures a proton and becomes oxygen-15 (8 protons, 7 neutrons), again by emitting gamma-rays. Unstable oxygen-15 emits a positron (replacing the proton by a neutron) and neutrino, turning into nitrogen-15 (7 protons, 8 neutrons). The last step of nitrogen-15 captures a proton, but the result is not a heavy nucleus, which contains 8 protons and 8 neutrons, which would give the oxygen-16. Instead, the two formed the nucleus: the carbon-12 and helium-4 (2 protons, 2 neutrons). Carbon-12 can now repeat the cycle, and helium-4 adds to star reserve of this gas. At each step of the cycle energy is released in the form of various kinds of radiations that give it the brightness of the star. Calculations Used. allowed a deeper understanding of the behavior and evolution of stars.
At the end of 30 - years. B. continued his theoretical studies of atomic nuclei. Among his many accomplishments was the first mathematical justification of the fact that newly discovered meson could be related to the force which keeps the nucleus from the decay. He also investigated a very sophisticated shock waves generated by the explosion, which proved useful for his further work on the Manhattan Project to create an atomic bomb.
. In 1941, shortly before the U.S. entered World War II, B
. became an American citizen. In a short time he worked on microwaves and their applications to radar in the Radiation Laboratory at MIT, and then in 1943. joined the Manhattan Project at Los Alamos (New Mexico). There, as director of the department of theoretical physics, he was responsible for the calculations of possible behavior of the atomic bomb. His profound knowledge in the field of nuclear physics, shock waves and electromagnetic theory played a significant role in the success of the program.
Back at Cornell University in 1946, B. continued research in many areas of interest to him - for example, made an important contribution to modern quantum electrodynamics. He also did much - along with other scientists - in order to understand public opinion, the danger to humanity posed by nuclear weapons. He has always been a supporter of arms control, maintaining at the same time, the idea of using nuclear energy for peaceful purposes. From 1956 to 1959. B. served in the Presidential Science Advisory Committee.
In 1967. B. was awarded the Nobel Prize in Physics "for his contribution to the theory of nuclear reactions, especially for his discoveries concerning the energy stars'. When presenting the winner Oscar Klein, a member of the Royal Swedish Academy of Sciences, noted the breadth of knowledge B. and said that some of his discoveries in physics, each individually worthy of self Nobel Prize. Job B. the sources of stellar energy, "said Klein," is one of the most important applications in fundamental physics in our time and leads to deepening our knowledge of the universe '.
Later B. studied the distribution of matter in neutron stars, as well as the collapse of giant stars. His research on high-speed input into the earth's atmosphere have helped in the development of both military and civilian spacecraft. Looking back on his work at Los Alamos as 'terribly exciting', he opposed the government-supported programs deploy anti-missile shield, viewing it as impracticable.
In 1939, Mr.. B. married Rose Ewald, the daughter of the famous German physicist, and had fled Nazi Germany. They have two children. Modest and attentive to others, B. once fond of skiing and mountain climbing, and later, as they say, became interested in the economy. His colleagues respected him for a very bright mind, and carefully developed scientific methods.
In addition to the Nobel Prize, B. received a government award the U.S. - Medal of Merit (1946), . Henry Draper Medal of the American National Academy of Sciences (1947), . Medal of the Max Planck Germanskogo Physical Society (1955), . Medal of Enrico Fermi Atomic Energy Commission, USA (1961), . Eddington Medal of the Royal Astronomical Society of London (1963) and the prize Vennevara Bush of the U.S. National Academy of Sciences (1985),
. He is a member of the American Philosophical Society, the American National Academy of Sciences, the American Physical Society and the American Astronomical Society, as well as foreign member of the Royal Society of London. He received honorary degrees from universities of Birmingham and Manchester.