Life in a chaotic universe: an interview with Ilya Prigogine

Foundations of science, 2002

Nonclarity around the understanding of the concept of chaos has caused some confusion in the contemporary natural science. For instance, not making a clear distinction between the deterministic and quantum chaos has made it impossible to evaluate the approach of Ilya Prigogine in an appropriate way. It is shown that Jean Bricmont has missed the target in his critique of I. Prigogine's ideas, as the latter has concentrated his interest on systems consisting of infinite (arbitrarily large) number of particles in incessant mutual impact, the former on systems that have a finite (not necessarily large, although sometimes very large) number of particles, which move freely of any mutual impact or participate only in transient interaction. The difference may sometimes be quite crucial. It is also suggested that if we consider the irreversibility as the basic element of description of physical world, the world of trajectories and wave functions cannot be researched apart from this real irreversibility.

Discrete Dynamics in Nature and Society, 2004

This special issue is devoted to the memory of the great scientist Ilya Prigogine, our teacher and friend. Prigogine's fundamental contributions to nonequilibrium physics and complexity not only shaped the views of twentieth century science but also opened pathways for the twenty-first century research. The science of complexity emerged as a new paradigm and has caught the attention of numerous scientists all over the world in the last few decades. Prigogine led us to an understanding of the physical conditions underlying the emergence of complex structures and self organization. This is the law of order through fluctuations far from equilibrium. Already a Nobel Laureate, he was one of the first to understand and accept the extreme importance of this new field of studies. He proposed revolutionary ideas about discrete time, space, and the new laws of physics underlying self organization and the interdependence of complex systems. It is never easy to be the first and it is always extremely complicated to change the opinions and established views of scientists, especially in physics. However, he succeeded in doing so, and that is why we all appreciate and admire him. He had a unique scientific vision and intuition, which gave him the force to develop the understanding of issues such as deterministic chaos, discrete time and space, irreversibility and nonintegrability. Prigogine took special care to share his knowledge not only with his students and colleagues, but also with the general public. His scientific results and views have been formulated in brilliant papers and books. Until the very moment he passed away, Ilya Prigogine was working on finding new laws of physics, laws which will provide understanding of complex, living and thinking systems dynamics. It will take some time to understand his innovative ideas which up to now are finding scientific confirmation. I. Prigogine always wanted things to run faster and understanding to be better and deeper. Each result made him more uneasy because he saw already many more questions appearing. He never gave up, even when facing problems in the understanding of his ideas.

Chaos (Woodbury, N.Y.), 2017

Friends and colleagues who knew Ilya Prigogine well called him "A poet of thermodynamics." It is an apt description. When Prigogine talked about thermodynamics and irreversible processes, one had the sense he understood or knew more than what his words conveyed. Natural processes all around us are irreversible; it is a fact. Their consequence is not merely to increase the entropy of the universe and destroy order. They can also do the opposite: create highly ordered complex structures with extraordinary properties and create life itself. Prigogine saw this as a profound aspect of nature that thermodynamics has revealed. When he came across the famed South Indian sculpture of Nataraja, the dancing Shiva, that depicts as a cosmic dance the perfect balance between creation and destruction that originate from the same source, he made sure he had a bronze statue of Nataraja of highest artistic quality in his art collection. A picture of it became the cover art for the book Thermodynamic Theory of Structure Stability and Fluctuations, 1 that he coauthored with Paul Glansdorff. It was poetry of thermodynamics, creation and destruction emerging from a common source, a perfectly balanced cosmic dance. One could surmise all this from Prigogine's discourses on thermodynamics. Dissipative structures was the name Prigogine coined, nearly 50 years ago, for the complex structures created by irreversible processes. As this special issue celebrating the hundredth anniversary of his birth shows (Prigogine was born on January 25, 1917) the study of dissipative structures is still a very active subject that is advancing into new areas. If we pursue the study of dissipative structures, we might be led to more insights, perhaps even new laws or principles that give us a better understanding of how complex structures come about spontaneously, their responses to changes in physical parameters, and their collective behavior. These advances, among other things, are also a quest for a thermodynamic understanding of processes we see in organisms and even those that created life. Convinced of the centrality of irreversible processes in nature and the reality of the arrow of time, Prigogine had to confront a vexing duality of physics. From the point of view of time-reversible mechanics, motion-and hence all transformations of matter-into the future or into the past had no fundamental distinction. Irreversibility and the arrow of time could not be real, it must be an illusion. It must be an illusion created by us, macroscopic living beings, due to the limitations of our faculties.

The twenty-first century is starting with a huge bang. For the person in the street, the bang is about a technical revolution that may eventually dwarf the industrial revolution of the 18th and 19th centuries, having already produced a drastic change in the rules of economics. For the scientifically minded, one aspect of this bang is the complexity revolution, which is changing the focus of research in all scientific disciplines, for instance human biology and medicine. What role does physics, the oldest and simplest science, have to play in this? Being a theoretical physicist to the core, I want to focus on theoretical physics. Is it going to change also? Twentieth-century theoretical physics came out of the relativistic revolution and the quantum mechanical revolution. It was all about simplicity and continuity (in spite of quantum jumps). Its principal tool was calculus. Its final expression was field theory. Twenty-first-century theoretical physics is coming out of the chaos revolution. It will be about complexity and its principal tool will be the computer. Its final expression remains to be found. Thermodynamics, as a vital part of theoretical physics, will partake in the transformation. CHAOS For theoretical physicists the revolution started a few decades ago with chaos. Chaos is a purely mathematical concept; it is an undeniable mathematical fact. We know that theoretical physics is built on mathematics, and that all theoretical physicists are applied mathematicians. The first question that I want to examine, then, is: why is it that, among all the practitioners of science, applied science, engineering disciplines, and human sciences, physicists were practically the last ones to be interested in chaos and to use it in their work? There were exceptions, of course. The people who built the large particle accelerators knew about chaos; in fact they discovered much of it. There are many other exceptions. But the majority of physicists did not know about chaos, and still does not. Engineers of many sorts, meteorologists, some types of chemists, population biologists, cardiologists, economists, and even psychologists, seized upon chaos long before the physicists did. During my teaching career at MIT, twice I introduced some simple chaos in an undergraduate course for physics majors; I wanted these future physicists to be exposed to it. But in the MIT physics department, faculty members do not teach the same course for very long. After two or three years, they move you to another course to keep you from getting stale. And so, twice

2001

Explaining Chaos is an informative, original and enjoyable introduction to chaos theory and its associated philosophical problems. The book does not presuppose any previous background in chaos theory. Nevertheless, the discussion may be as interesting to experienced readers as it is to novices. In particular, several mathematical interludes deepen the discussion of technical issues and provide numerous interesting insights that could further enlighten readers already familiar with the central ideas. The reader will ®nd an accessible discussion striking a good balance between scienti®c and philosophical topics. Unfortunately, the physical and the philosophical parts are uneven in quality. While the treatment of the scienti®c issues is thorough and skilful, the philosophical discussions have signi®cant lacunas. Nevertheless, Smith's enthusiasm for exploring these issues is contagious and the book is a valuable contribution to a ®eld that has, despite its importance, received little attention from philosophers so far. Explaining Chaos consists of ten chapters that could be divided into two main categories: the mathematics and physics of chaos, and the implications of chaos for scienti®c practice and methodology. In Chapters 1 (dynamical systems), 2 (fractals), 6 (universality), 8 (experimental evidence for chaos), and 9 (randomness), Smith introduces the central topics of chaos theory and discusses important results. In Chapter 10, he addresses the question of how chaos could adequately be de®ned. On the whole, these chapters provide a very knowledgeable and skilful presentation of the basics of chaos theory. In Chapters 3 (models and simplicity), 4 (prediction), 5 (approximate truth), and 7 (explanation), Smith considers the methodological implications of chaos theory. Here, he aims at showing that chaos, though an interesting and exciting ®eld of investigation, by no means requires a revision of the basic traits of scienti®c methodology. Smith successfully resists the temptation to be carried away by fancy bold claims and, on the contrary, argues that chaos theory may be considered a respectable tool for decent scienti®c research.