Ilya Prigogine was born in Moscow, Russia, in 1917. His father, Roman, was a chemical engineer and his mother, Julia had studied music at the conservatory in Moscow. Although Prigognine eventually elected to study chemistry, his highly philosophical approach to science reflected his numerous interests which included history, art, music, and law. Under the direction of Théophile De Donder, Prigogine received his Ph.D. from the Free University of Brussels in 1941 with the thesis, "The Thermodynamic Study of Irreversible Phenomena." De Donder was the founder of the Brussels school of thermodynamics (the branch of physics that deals with the behavior of heat and related phenomena).
Prigogine was particularly interested in the nature of time as it related to chemistry, and was therefore attracted to a study of the second law of thermodynamics that states that any spontaneous change in a closed system (one where neither matter nor energy flows into or out of the system) occurs in the direction that increases entropy, the measure of unavailable energy in a system or the measure of its disorder. This law indicates that as time passes in a closed system, disorder always increases, leading Sir Arthur Stanley Eddington to refer to the second law as supplying "the arrow of time." The move toward entropy described in the second law is irreversible, which contrasts with all other physical laws in which processes are reversible in time. This contrast begged the question of how the reversible, random workings of molecular and atomic motions could lead to processes that have a preferred direction in time. The second law also suggests that the universe is moving toward eventual decay, a point when all energy and matter will reach a uniform state of equilibrium known as heat death.
Intrigued by these issues, Prigogine moved his focus away from the ideal "closed" system described in the second law and instead studied open systems that exchange matter and energy with an outside environment. Prigogine's first success in dealing with irreversible processes and open systems not at equilibrium came in 1945. In his doctoral research, he showed that for systems not too far from equilibrium, changes take place so as to achieve a steady state in which the production of entropy is at a minimum. This is true near equilibrium where the flux (or flow) of energy or matter through the system is directly proportional to the force creating that flux; that is, the flux and the force are linearly related. But such a steady state, once established, is stable and continues unchanged; it cannot evolve into a new state.
In 1947 Prigogine succeeded De Donder to become full professor at the Free University of Brussels. He subsequently showed that far from equilibrium, where fluxes and forces are no longer linearly related, a system can become unstable and evolve new, organized structures spontaneously. Prigogine called these organizations dissipative structures and developed the mathematical means of describing them. Prigogine theorized that such structures can be maintained as long as the energy and material fluxes are kept up. The process by which a new order evolves is labeled self-organization. In a nonlinear system there exist points--Prigogine referred to these as moments of choice or bifurcation points--at which the system is unstable, and small fluctuations can grow to a macroscopic or large size, creating a new structure. Randomness enters at the bifurcation points, so that predictions with respect to outcomes can only be expressed as probabilities.
Prigogine's findings, while important, remained largely theoretical into the 1960s. Attempting to confirm his ideas, Prigogine worked with G. Nicolis and Réné Lefever to devise a simple mathematical model now called the Brusselator to better test his theories. Then in 1965 the Belousov-Zhabotinskii reaction, discovered in 1951 in the Soviet Union, became widely known abroad. One version of the reaction, in which the dissipative structures can be seen and do not have to be revealed by elaborate measurements, is a solution of malonic acid and bromate ion in sulfuric acid and ferrous phenanthroline (ferroin). Depending on the temperature and concentrations of the various species, the color of the solution may change back and forth from red to blue, or a pattern of red and blue may be formed that is either stationary or moves through the solution in a regular manner. These patterns gave striking visual proof of the existence of Prigogine's dissipative structures.
Prigogine's work is of great interest to many fields. In the fields of biology and biochemistry, it was suggested by Alan Mathison Turing in 1952 that instabilities in chemical reaction systems could explain the patterns of stripes on a zebra or spots on a leopard. On a still larger scale, the thermodynamics of irreversible systems may explain how evolution, a process that gives rise to ever more specialized forms, is compatible with a physical picture of the world in which systems inevitably move from an ordered to a disordered state.
Prigogine and others have also applied the principles of irreversible thermodynamics to such disparate systems as the development of traffic patterns on a highway in response to driving conditions and the buildup of giant termite mounds in which a large number of independent termites behave in an orderly, seemingly purposeful, and intelligent fashion. On a larger scale, Prigogine's research allows a somewhat different and brighter view of the universe's ultimate fate. As explained in Omni, the theory of dissipative structures "offers a guardedly optimistic alternative to the pessimistic view of mankind's future--that winding down of nature toward a kind of heat death."
Prigogine was named director of the Instituts Internationaux de Physique et de Chimie (the Solvay Institute) in 1959, a post in which he continued after his retirement from the Free University in 1985. In 1977 he became the first Belgian awarded the Nobel Prize. He and his wife Marina Prokopowicz, an engineer whom he married in 1961, live in Brussels.
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