Date of Birth: 08/06/1936
Place of birth: Waltham
Citizenship: United States
In his early work devoted to elementary particles and interactions between them, B. used a mathematical technique called renormalization, which offered Gell-Mann, Lowe (colleague Gell-Mann at Caltech), and others, in order to overcome some of the difficulties in quantum electrodynamics. With the direct application of quantum theory to the behavior of elementary particles we had to deal with such uncomfortable values, as an infinite power. Gell-Mann and Low use of renormalization group in order to modify the mathematical representation, such as point particles, such as electrons, to remove obstacles to further the application of the theory. V. made his contribution to this theory, deciding in his doctoral thesis problem associated with the K mesons (kaons). At Cornell University in part due to the work of their colleagues Michael Fischer and Benjamin Uaydoma he became interested in critical phenomena, with a view to further applications of the renormalization group.
Critical phenomena - a special material behavior under certain external conditions (eg, temperature and pressure), when the properties of materials change dramatically. These special conditions are called the critical point. For example, if we take the water temperature at which a liquid solidifies or becomes vapor pressure dependent. In boiling liquid and vapor coexisting, and if they are kept in a closed volume, we can say that they are in equilibrium; they are usually easy to distinguish because they have a huge difference in density. However, when the boiling point rises with pressurized fluid density decreases with increasing temperature, since the liquid is expanded (pressure is only slightly water condenses), while steam (gas) is strongly compressed and becomes denser. If we increase the heating to keep the boiling point as the pressure grows, we eventually reach the point (219 atmospheres of pressure, temperature of 374 & # 186; C), where the two densities are equal and the boiling disappears. Now it is impossible to separate the liquid from the vapor, and the question itself loses its usual meaning. These pressure and temperature determine the critical point of water. Another example is the critical point gives the temperature (called the Curie point by the name of Pierre Curie), below which the ferromagnetic material begins spontaneously magnetized and above which it is non-magnetized. If the magnet is heated above the Curie point, it loses its magnetic properties and "remembers" its original state, when cooled again. Critical phenomena for the first time systematically studied in the 1860s. carbon dioxide.
Systems with critical points have a special bond between interactions at very short distances (micro level) and macro characteristics of the body. In the case of water microscale phenomena are reduced to the motion of molecules and intermolecular attraction. In the case of the magnet is determined by the ability of elementary magnets is associated with the spins of the electrons, influence on its neighbors, prompting them to a particular ordering. Near the critical point of these ordinary exposure increases many times its size, which leads to an agreed makropovedeniyu. Quantitative understanding of critical phenomena is faced with the complexity of a large number of independent microinteractions (degrees of freedom) and acting on the longer distances the correlations between the different areas, which eventually cover all the material body. The values ??fluctuate from one point to another and from region to region, forming many different levels of interaction, or scale values.
Scientists have energetically took up the problem, trying to find a way that would reduce the complexity to acceptable limits, without compromising the fairness of the theory itself. In 1937, the Russian physicist Lev Landau proposed a method, called the theory of the average of the field, in the case of magnets, in which he averaged magnetization fluctuations, suggesting that fluctuations are significant only at the atomic level. In 1944, the Norwegian-American chemist Lars Onsager found quantitative solution for the two-dimensional model, which allowed him to calculate the magnetic properties, and also to show the error of the Landau theory. As a result, it became necessary to create a new, more general theory. In 1965, Wyden suggested that the change of scale interactions near the critical point must not violate the fairness of the mathematical description. In 1966, American physicist Leo Kadanoff proposed to divide the ferromagnetic system near the critical point in the cell, each of which would contain a small number of atomic level magnets, and cell size would determine the value of the scale. Other scientists have also contributed to a possible solution to this problem. But it was the use of renormalization group theory V. gave a successful method to describe the behavior near the critical point and allowed to find quantitative estimates of the properties of the system with the help of computers.
In fact, B. broke system blocks arranged like a grid, as did Kadanoff. Since the small scale and the large number of small units, he used the averaging procedure. Then, gradually increasing the scale and size of blocks, he repeated this process again and again until, until it came down to the final presentation, which gave the numerical results are consistent with experimental data. At each step of smaller-scale fluctuations are averaged, and the fluctuations of greater magnitude approaching that to include the entire system. He also found that the system near its critical point can be characterized by a small number of parameters that have quality versatility. In other words, the same parameters can be used to calculate the behavior of a surprisingly large number of other systems. Later, B. and Fisher have developed some aspects of this method further, increasing its value.
Other physicists quickly recognized the importance of B. Landau called critical phenomena the most important unsolved problem of theoretical physics, and B. himself later said that the problem to which he applied the method belong to the most difficult in physics. "If it were not so, - he explained - that they would decide by a simpler method much earlier."
B. was awarded in 1982 g.Nobelevskoy Prize in Physics "for his theory of critical phenomena in connection with phase transitions". When presenting the winner Stig Lundqvist, a member of the Royal Swedish Academy of Sciences, in his speech he congratulated V. with its "elegant and profound" solution of the problem of phase transitions. Produce nitrates derived V., he said, "gave a complete theoretical description of the behavior near the critical point, and also led to the methods of numerical calculation of critical values. In the decade that has passed since the publication of his first works - continued Lundqvist, the complete triumph of his ideas and techniques confirmed the life itself. "
Renormalization practical application can be expected in areas such as liquid leakage through the solid, freeze, crack propagation in metals and oil flow in underground reservoirs in which microscopic complex physical processes occur in macroscopic effects. In recent years, B. tries to apply his methods to the theory of quarks - the particles that, as suggested by Gell-Mann, serve as building blocks for protons, neutrons, and other subatomic particles that were once considered elementary.
Since 1976 V. focuses on computer modeling. Finding that his theoretical work is limited by the speed and memory of modern computers, he became an advocate for the creation of supercomputer centers, serving scientists.
In 1982 W. married Alison Brown, a specialist at Cornell computers computer service. Former amateur musician who played the oboe, he likes folk dancing and hiking trip. He describes himself as "a workaholic, who sees a lot of opportunities especially their weight."
V. is a member of the US National Academy of Sciences and the American Academy of Arts and Sciences. Among his other awards: Danny Heineman Prize of the American Physical Society (1973), the Wolf Prize Wolf Foundation (1980), which he shared with Fisher and Kadanoffom and honorary award to graduates of California Institute of Technology (1981). He holds an honorary doctorate degree from Harvard University.