Tomonaga (Tomonaga), Itiro( Japanese physicist, Nobel Prize in Physics, 1965)
Comments for Tomonaga (Tomonaga), Itiro
Biography Tomonaga (Tomonaga), Itiro
March 31, 1906, Mr.. - July 8, 1979
Japanese physicist Itiro Tomonaga was born in Tokyo, was the eldest son Sandzyuro and Hideo Tomonaga. In 1913, when his father was appointed professor of philosophy of the Kyoto Imperial University, the family moved to Kyoto, where T. studied at the renowned throughout the country, the 3rd high school.
T. received a bachelor's degree in nuclear physics at Kyoto in 1929. and stayed there for three years as a graduate student and assistant in a research laboratory Kadzyuro Tamaki. One of his colleagues there was Hideki Yukawa, who later predicted the existence of the pion, a particle carrying out the transfer of nuclear forces between protons and neutrons. In 1932, Mr.. T. transferred to the Institute of Chemical and Physical Research in Tokyo as an assistant researcher laboratory Yoshio Nishino. From 1937 to 1939. He worked at the University of Leipzig with Werner Heisenberg. Work on the physical properties of the atomic nucleus, which he published while in Germany, was admitted as a doctoral dissertation at Tokyo Imperial University in 1939
In 1941, Mr.. T. was appointed professor of physics at Tokyo University of Science and Literature (which later became part of the Tokyo University of Culture). During the Second World War he worked on radar, ie. in the area, which occupied and Julius C. Schwinger, and later share with him the Nobel Prize.
In early research interests of the T. were associated with quantum electrodynamics, which he periodically returned for more than 20 years. His first research in this area was done with Nishino in Tokyo, he continued it with Heisenberg in Leipzig and returned to him together with his students in Tokyo during the war. Significant progress in this direction began in 1947, and it is for this work he received the Nobel Prize.
Aim of studies of T. in the field of quantum electrodynamics is the harmonization of the two momentous physical theories in the XX. - Quantum mechanics and special relativity. Quantum mechanics in the form in which it was formulated in the mid 20's., Successfully coped with an explanation of atomic structure. However, there was one significant moment, where this theory was incomplete because it did not take into account the possibility of converting matter into energy, and vice versa. The possibility of such a transformation - is the central result of the special theory of relativity of Albert Einstein.
Since 1927. English physicist P.A. M. Dirac tried to reconcile quantum mechanics with the theory of relativity. He focused on the relationship between electrons and electromagnetic, radiation. According to the final form of the theory of Dirac, a photon, or quantum of electromagnetic energy can 'materialize', thus creating an electron and a positron (antiparticle of the electron double). Similarly, the electron and positron annihilation as a result may give rise to a photon. T. and Nishino studied these processes in the early 30's.
Dirac's theory gave the key to a new understanding of the interactions of charged particles. For example, two neighboring electron can exchange a series of photons, being thrown by them as balls. Reaction force is being tested by each electron when it emits or absorbs a photon, then manifest itself as electromagnetic repulsion, which tends to remove the electrons from each other. In this case we say that participating in such an exchange photons are 'virtual' particles because their existence is fleeting and can not be detected directly.
. The energy of virtual photons can be calculated using the Heisenberg uncertainty principle according to which the maximum energy of the particles depends on the time required for the measurement of this energy
. Because virtual photons, there is very little time, their energy can be large. Moreover, since the interaction of electrons on the convergence of shortening the lifetime of the virtual photons, in this case the upper limit of energy rises more. There is an interesting question: what happens when the same electron at first emit a virtual photon, and then re-swallow it. In this case, the lifetime of a photon can be close to zero and, therefore, permissible energy becomes unbounded. Continuous emission and absorption of photons, apparently, will give the electron an infinite mass.
By the early 40-ies. was recognized that from the Dirac theory implies that the electron must have an infinite mass, as well - for similar reasons related to the virtual electrons and positrons - and infinite electric charge. These conclusions are obviously absurd, since the electron mass and charge, as is well known, finite and not very large. Nevertheless, this theory continued to be used, because its shortcomings become apparent only when we study the electrons with a very close range. For most experiments, feasible at that time, Dirac's theory gave the correct predictions, besides a better theory.
The crisis erupted in quantum electrodynamics in 1947, when Willis S. Lamb, Robert K. Rutherford experiment found that one energy level of an electron in a hydrogen atom is slightly different from the value predicted by Dirac. Around the same time, Polycarp Kusch and his colleagues found that the magnetic moment of the electron is also slightly different from the predicted value. These contradictions have led T. and Schwinger reconstruct quantum electrodynamics. T., isolated in postwar Japan, the majority of Western physicists, learned about the results of the Lamb is not a scientific journal, and a popular science column in a weekly American magazine.
. First there were attempts to cope with an apparently infinite mass and charge of an electron, simply denying their existence
. T. Schwinger and chose a different approach: instead of discarding the infinities they used them. They showed, . that the measured electron mass must consist of two components: the true, . or 'pure', . mass, . which would have the electron, . if he had seen in isolation, . and mass, . associated with a cloud of virtual photons (and other virtual particles), . which the electron is continuously emits and absorbs,
. If a cloud of photons have infinite mass, then it follows that the net weight must also be infinite, but the negative. When two of these components are connected to the overall mass of infinity cancel out, leaving only a small ending balance, which corresponds to the measured mass. Using a similar approach to the infinite electron charge, T. and Schwinger postulated an infinite negative net charge, which attracts positively charged cloud of virtual particles. Infinitely large positive charge of the virtual cloud screens the negative net charge, except for the final balance.
Mathematical procedure, invented the T. and Schwinger to avoid infinite mass and charge, is called the renormalization. Although the renormalization of quantum electrodynamics gave life-saving concept, ultimately, many physicists believed that such a remedy worse than the disease. Renormalization eliminates some of infinity, introducing others, including the mass, which not only endless, but still negative. However T. Schwinger and emphasized that their theory of the observed values of the masses are finite and positive. Electron can not be separated from its cloud of virtual particles, so the endless net mass and charge can not be seen. Regardless of the T. and Schwinger, and approximately the same time, Richard F. Feynman found a completely different way to express the ideas of quantum electrodynamics. He showed that each interaction between the particles (including virtual particles) can be represented by diagrams of the trajectories of particles in space and time.
. Renormalization theory in quantum electrodynamics has been the most accurate of all physical theories
. Some characteristics of the electron can be measured with accuracy values of up to several billions of dollars, the value predicted by theory, exactly consistent with the experimental data. Moreover, quantum electrodynamics served as a model for theories describing the other forces of nature, and the renormalization was an important step to ensure that these theories have to work.
. T., Feynman and Schwinger shared the Nobel Prize in Physics for 1965
. 'for fundamental work in quantum electrodynamics with far-reaching consequences for the physics of elementary particles', in his Nobel lecture T. touched on the evolution of ideas that prompted him to begin work in this direction. The failure of Dirac's theory, he said, 'has created many strong distrust of the quantum field theory. There were even people with extreme views who thought that the very concept of a field has nothing to do with the true laws of nature ... Under the influence of Heisenberg, I came to the conclusion that the theory of a field, having no explanation, needs a frontal assault on it '.
Job T. during and immediately after the Second World War became known outside Japan, primarily through the efforts of the Yukawa. As a result, in 1949. he was invited to the Institute for Basic Research in Princeton (New Jersey), where he was working in the field of quantum mechanics of systems of many particles, such as solids, and thus opened a new area of research. When in 1951. died Nishino, T. returned to Japan to head the Institute of Chemical and Physical Research. From 1956 to 1962. He was president of Tokyo University of Culture, and from 1963 to 1969. served as president of the Science Council of Japan. He also headed the Institute of Optical Research and served in various government committees. He helped organize the Institute for Research on Fundamental Physics at Kyoto University and the Institute for Nuclear Studies at the University of Tokyo.
In 1940. T. married Ryoko Sekiguchi, daughter of Director of the Tokyo Metropolitan Observatory. They had two sons and a daughter. T. died July 8, 1979
In addition to the Nobel Prize, T. won the Japanese Academy of Sciences (1948), the Order of Culture of the Japanese Government (1952) and the gold medal of. Lomonosov USSR (1964). He was a member of the Japan Academy of Sciences, . Germany Academy of Natural Scientists 'Leopoldina', . foreign member of the Royal Swedish Academy of Sciences, . corresponding member of the Bavarian Academy of Sciences, . foreign member of the U.S. National Academy of Sciences.,