YANG (Yang), Chen Ning( Chinese-American physicist, Nobel Prize in Physics, 1957)
Comments for YANG (Yang), Chen Ning
Biography YANG (Yang), Chen Ning
genus. September 22, 1922
Chinese-American physicist Yang (Yang) Chen Ning was born in Hefei (Anhui province), he - the eldest of five children, Jan Kechuanya, professor of mathematics, and his wife, who before her marriage was called Lo Menhua. In 1929, Mr.. family moved to Beijing, where Professor Yang has taught at the University of Tsinghua, and his son went to high school. When Japan invaded China, Tsinghua University moved to r. Kunming, where he joined the National southwestern united university. YA. enrolled in the new university, where he later became his schoolmate Lee Tszundao, and received in 1942. Bachelor's degree in physics, wrote a work on group theory and molecular spectra. In 1944, Mr.. He received a master's degree, presenting a thesis on the statistical theory of ordering transitions to a disordered state. In 1945, Mr.. scholarship of the National southwestern united university, he enrolled at the University of Chicago to work under the leadership of Enrico Fermi. His thesis, . presented in 1948, . opponent which was Edward Teller, . Entitled 'On the angular distribution in nuclear reactions and measurements of coincidences' ( 'On the Angular Distribution in Nuclear Reaction and Coincidence Measurements').,
. Left in Chicago for another year, I
. worked as a lecturer in physics, and then moved to the Institute for Basic Research in Princeton (New Jersey). During the 1953/54 academic r. he was chief physicist, Brookhaven National Laboratory on Long Island (New York). He became a professor of physics at the Institute for Basic Research in 1955. and remained in that position for more than 11 years, then moved to the University of New York at Stony Brook, Long Island at the rate of professor and director of the Institute of Theoretical Physics.
It was at this time I. began to meet regularly with Lee, who was now at Columbia University, to continue the discussion of physical problems, which they began, when both studied at Chicago. In May 1956,. They drew attention to a problem concerning the law of conservation of parity. Parity conservation follows from one of the symmetry in nature, recognized by physicists. This means among other things, that nature does not target either the right or the left side, so that the mirror image of the interaction of particles must obey the same laws as the interaction itself, if parity is conserved.
. In quantum mechanics, each particle or system of particles is described by some mathematical expression, which is called the wave function
. Mirroring results in the replacement of spatial coordinates x, y, z to-x,-y,-z. If the sign of the function is reversed, then the parity of the particle or system is equal to -1 (odd). If the function does not change, then the parity is +1 (even). The law of conservation of parity, first formulated in 1925, claimed that the total parity (the product of parities of all the participating particles) is the same both before and after interaction. The law gained widespread acceptance because it leads to a useful theoretical and experimental results, and in addition, likely more because the desire of physicists to find the answer in the nature of such symmetry. Most intuitively felt that nature does not prefer right over left, or vice versa.
. The problem of conservation of parity has arisen in connection with two completely different types of K-mesons, unstable particles observed among the other pieces after the high-energy bombardment of atomic nuclei
. One of them (theta) is divided into two pi-meson, since the pi-meson has a certain parity of -1, the total parity of the two pi-meson is (-1) б╥ (-1) = +1. Consequently, the parent of theta-particle should also have parity +1. In contrast, tau, which generates three pi-meson, should have parity (-1) б╥ (-1) б╥ (-1) = -1. Consequently, on the one hand, if the theta-and tau-mesons have different parity, then they must be different particles. On the other hand, the experimental data, such as the fact that they have equal masses and lifetimes suggest that it is one and the same particle. Absorbed in this, apparently unsolvable dilemma, I. and Lee boldly decided to find experimental confirmation of the law of parity conservation.
. In particle interactions involving four forces: strong interaction, . connecting the protons with neutrons in the nucleus, the electromagnetic force, . acting on charged particles, the weak interaction, . associated with the emission of particles during radioactive decay, . and gravity - force, . acting on the mass,
. To my surprise, I. and Lee found that there are numerous experimental confirmation of parity conservation in strong and electromagnetic interactions, but such evidence is completely absent in the case of weak interactions. Gravitation - it is so relatively weak force that the interaction of elementary particles it is usually neglected. No one from the reports of scientists should not have confirmation of the principle of conservation of parity in weak interactions, although the decay of theta and tau particles on the pi-mesons include any. YA. and Lee quickly consider how to conduct experiments to give a precise answer to the question remains whether the parity in weak interactions. Because they were theorists, some experiments have provided to others.
The first people who responded to their call, were By Tszyansyun from Columbia University, together with physicists from the National Bureau of Standards USA. In 1956 ... 1957. after six months of grueling preparation for the difficult experiment By radioactive cobalt was placed inside an electromagnet and cooled to temperatures close to absolute zero, in order to minimize the effect of thermal motion. Cobalt emits beta particles (electrons) and neutrinos (uncharged particles with zero mass). Since the atoms behave like tiny magnets, their directions are parallel to the electromagnetic field, to set an orientation. If parity is conserved in the radioactive decay of cobalt, which is a weak interaction, then in the direction of north and south poles of a magnet flew to an equal number of electrons emitted. By discovered that more electrons fly from the southern end of. Parity is not conserved. Subsequent experiments by other scientists almost immediately confirmed the violation of the law of conservation of parity in the decay and transformation of pi-mesons in the mu-mesons and mu-mesons into electrons and neutrinos (or antineutrinos). In mu-meson and electron asymmetry is manifested directions back and forth.
When non-compliance with the law of parity I. and Lee were able to assume that the theta and tau, and in fact one particle capable of two different types of decay. Violation of the law of conservation of parity has caused a whole avalanche of theoretical and experimental studies. With these new studies, scientists pin their hopes for a unified field theory, which unites four known types of interaction, an idea which is directly connected with the name of Albert Einstein.
. 'In anticipation of the study of so-called parity laws which has led to important discoveries in the field of elementary particles', I
. and Lee were awarded in 1957. Nobel Prize in Physics. When presenting the winners O.B. Klein, . Member of the Royal Swedish Academy of Sciences, . said: 'The result of their study was unexpected, . when it became, . that assumptions, . concerning symmetry, . even in well-known processes have had no experimental proof for the reason, . that the experiments were thus, . that their results do not depend on the justice or injustice of these assumptions',
. Klein was congratulated both the winners on their success in resolving 'the most deadlock problems in the physics of elementary particles, after which the experimental and theoretical work is scored key'.
Main scientific interests I. lie in the field theory and elementary particles, statistical mechanics (the science of the atomic origins of thermal phenomena) and the principles of symmetry. New principle for describing the interaction of particles and fields, which he proposed in 1954. with Robert L. Mills, then at Brookhaven National Laboratory, became the basis for many studies in the field of fundamental physics, known as the gauge theory. It is believed that the gauge principles underlie all basic interactions in nature.
I. visited the People's Republic every year since 1971, helping establish mutual understanding and friendship between their homeland and the United States. He married Tu Chile in 1950, they have two sons and a daughter. Before leaving the United States from China in 1945. YA. decided to choose a name that Americans would be easy to pronounce. He chose the name of Franklin, because I admire Benjamin Franklin, with a biography which was familiar, and American friends call him Frank. He became a U.S. citizen in 1964
I. received honorary doctorates from Princeton, Minnesota, University of Durham, as well as some institutions. He was awarded a commemorative prize Yeshiva University's Albert Einstein (1957) and the Rumford Medal of the American Academy of Arts and Sciences (1980). He is a member of the U.S. National Academy of Sciences, the American Philosophical Society, the Brazilian Academy of Sciences, the Venezuelan Academy of Sciences and the American Physical Society