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Hans Bete

Picture of Hans Bete

Date of Birth: 07/02/1906

Age: 98

Place of birth: Strasbourg

Citizenship: United States

Background

Another graduate student B. expressed interest in quantum mechanics and its mathematical theory describing the interaction between matter and radiation. Formulated in the mid 20s. Werner Heisenberg, Erwin Schrodinger and PAM Dirac, it was the result of earlier research in the field of quantum theory: Max Planck discovered that the radiation is not continuous, but consists of discrete portions of energy, later called photons; Albert Einstein showed that photons, quanta of light (electromagnetic radiation), and the photoelectric effect act like particles; Niels Bohr used the quantum theory to describe nuclear energy levels, are responsible for the characteristic spectra of the emitted radiation; Finally, Louis de Broglie put forward a bold assumption that if the radiation (light) can behave like a particle, then the particle can behave like a wave. The idea of ??de Broglie was experimentally confirmed J. Clinton. Davisson, who discovered the wave behavior of electrons. In 1927, B. wrote a scientific article devoted to the diffraction of electrons by crystals, in which to explain the observations Davisson used quantum mechanics are not understood at the time by most physicists. B. was one of the first scientists to clearly demonstrate the application of the 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 spent in Cambridge (England), where he met with Ernest Rutherford, and in Rome, where he worked with Enrico Fermi. He also established contact with Niels Bohr. Over time etoyu AB has developed the use of mathematical technique known as group theory, to determine the quantum-mechanical behavior of crystals. Having made significant contributions to the theory of atomic structure, B. in the early 30-ies. He started the theoretical study of rapid energy loss process of the particles passing through matter; to this point he returns periodically throughout his scientific career.

Appointed an assistant professor in the University of Tubingen in 1932, B., whose mother was Jewish, lost this post` next year, after the publication of Hitler became Chancellor of Germany, anti-Semitic decrees. B. left Germany in 1933, the year he lectured at the University of Manchester in England, and then in 1934 ... 1935. He became a member of the Academic Council of the University of Bristol. In 1935 he became an assistant professor at Cornell University in Ithaca (NY), and then a full professor in 1937

Here, B. returned to the study of nuclear physics. In 1936, in collaboration with the American physicists Robert F. Becherom and MS B. Livingston wrote several extensive works, which were summed known at that time results in the, 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 at a conference on theoretical physics at Washington (DC) has attracted the attention of B. One unresolved question of the nature of energy the sun and other stars. Astronomers have accumulated a lot of information about the extremely high temperatures and other characteristics of the star and came to the conclusion that the power source must have a thermonuclear nature. However, they could not determine reactions that would give the quantitative characteristics that are consistent with the observed emission, size, age and other characteristics of stars. Quickly mastered with astronomical data and applying his encyclopedic knowledge in the field of nuclear physics, B. solved this problem for six weeks.

For the first time the German astronomer Carl Friedrich von Weizsacker has been proposed to explain this issue a synthesis of two protons (hydrogen nuclei in large numbers inside the Sun), which yields a deuterium (also called heavy hydrogen, whose nucleus contains a proton and a neutron) and energy is released in the form of positron (positive electron) and a neutrino (uncharged particles). Protons are positively charged, and the number of protons in the nucleus determines element (hydrogen nucleus contains a proton, but may comprise neutrons whose mass is approximately equal to the proton mass, but they do not carry a charge). In the synthesis of the two protons emitted positive particle (positron), resulting in one of the protons is converted into a neutron. B. considered such solar characteristics, such as temperature, density, composition, and the expected rate of reaction, and calculated that the synthesis reaction takes place just at such a rate that provides the observed energy release of the Sun. However, his calculations show that for stars more massive than the Sun, in the reaction must involve heavier nuclei.

For massive stars B. proposed six-carbon-nitrogen cycle. In the first step the carbon with an atomic weight of 12 (the most common and stable form of carbon from 6 protons and neutrons in the nucleus 6) captures a proton, turning into nitrogen-13 (7 protons, neutrons 6) and emitting energy in form of gamma rays. Unstable nitrogen-13 decays by emitting a positron (which converts a proton into a neutron) and neutrino and turning at the same time in the carbon-13 (6 protons and 7 neutrons). Carbon-13 captures one of more of available protons and always converted to nitrogen-14 (7 protons, neutrons 7), again emitting the gamma rays. Nitrogen-14, in turn, captures a proton and becomes oxygen-15 (8 protons, neutrons 7), again emitting the gamma rays. Unstable oxygen-15 emits a positron (replacing the proton neutron) and neutrino turning into nitrogen-15 (seven protons and 8 neutrons). On nitrogen-15 captures the last step of a proton, but not result in a heavier core containing 8 8 protons and neutrons, which would provide oxygen-16. Instead, the two cores is formed: carbon-12 and helium-4 (2 protons, 2 neutrons). Carbon-12 can now repeat the cycle, and helium-4 replenishes the supply of this gas star. At each step of the cycle, energy is released in the form of various types of radiation, which give it the brightness of the star. B. Calculations have allowed a better understanding of the behavior and evolution of stars.

In the late 30`s. B. continued his theoretical studies of atomic nuclei. Among his many achievements was the first mathematical justification that the newly discovered meson could be related to the force that holds the nucleus of the collapse. He also explored the highly complex shock waves produced by the explosion, which proved to be useful for its future work on the Manhattan Project to create the atomic bomb.

In 1941, shortly before the US entered World War II, B. became an American citizen. For a short time he worked on microwave and radar applications to the Radiation Laboratory in the Massachusetts Institute of Technology, and then in 1943 joined the Manhattan Project in Los Alamos (New Mexico). There, as director of the Department of Theoretical Physics, he was responsible for the calculation of the possible behavior of the atomic bomb. His in-depth 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 it - for example, made an important contribution to modern quantum electrodynamics. He also did a lot - together with other scientists - in order to understand public opinion of 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 contributions to the theory of nuclear reactions, especially his discoveries concerning the energy source of stars." At the presentation of the winner of Oscar Klein, a member of the Royal Swedish Academy of Sciences, he said the breadth of knowledge and B. said that some of his discoveries in the field of physics, each individually deserved self Nobel Prize. B. Work on sources of energy star, said Klein, "is one of the most important applications in fundamental physics in our time and leads to a deepening of our knowledge about the universe."

In the future, B. studied the distribution of matter in neutron stars, as well as the collapse of giant stars. His research on high-speed entry into the Earth`s atmosphere have helped in the development of both military and civilian spacecraft. Reminiscing about his work at Los Alamos as a "terribly exciting", he opposed the government supports the deployment of anti-missile shield program, regarding it as impracticable.

In 1939, B. married Rose Ewald, the daughter of the famous German physicist, and who left Nazi Germany. They have two children. The modest and attentive to others, B. once fond of skiing and mountain climbing, and later, as they say, became interested in economics. His colleagues respected him for his very lucid mind and carefully developed scientific methods.

In addition to the Nobel Prize, B. received US government award - medal "For Merits" (1946), Henry Draper Medal of the American National Academy of Sciences (1947), the Max Planck Medal of the German Physical Society (1955), Medal of Enrico Fermi at the US Atomic Energy Commission ( 1961), Eddington medal of the royal astronomical society (1963), and the prize Bush Vennevara US National Academy of Sciences (1985). He is a member of the American Philosophical Society, the US National Academy of Sciences, the American Physical Society and the American Astronomical Society and a foreign member of the Royal Society of London. He received honorary degrees from the Universities of Birmingham and Manchester.