High Ambassador of a "New Alliance"

Vasileios Basios, Brussels, Belgium

Ilya Prigogine was born during the Bolshevik revolution, in Moscow, in 1917. He died on the 28th of May 2003 at his own alma matter university hospital 'Erasmus' in Brussels. He was calm and surrounded by family. His beloved wife Marina and his sons survive him. He attributed to her loving presence the peace and optimism that are so necessary for a theoretician who wants to pick his "path among all successive bifurcations", as he once wittily described it. Indeed if something characterises Prigogine's life it is "fluctuations - their efficacy in striking coincidences", as he maintained.

Ilya's father, Roman Prigogine, a chemical engineer, and his family, had to flee the newborn Soviet Union. They first sought refuge in Germany, in 1921. Then, in 1929, they moved to Brussels. Ilya graduated from the University of Brussels (Université Libre de Bruxelles, ULB) and subsequently pursued a career there as Professor of Physical Chemistry.

His scientific thinking was formed in the intellectual climate of his mentor and Ph.D. advisor Theophile De Donder (1873-1957). He always had an enduring respect and admiration for him. Indeed he would show his affection for his teacher on every occasion. De Donder was a charismatic 'self-made' man and academic, who established what came to be known as the 'Brussels School of Thermodynamics'. He was one of the pioneers in the field of non-equilibrium thermodynamics.

The thermodynamics and statistical mechanics of those days were focused on equilibrium systems, pursuing a rather simple minded, reductionistic approach. The prevailing tendency was one of reducing all to linear responses to an underlying mechanistic causation that was fueled by the drive for equilibrium. This program had its internal limitations and Prigogine was intellectually astute and morally courageous enough to foresee new avenues of research through what came to be known as 'non-linear thermodynamics'.

Indeed, from his early days Ilya Prigogine challenged the established linear approach that became epitomised as the 'Onsager reciprocity relations.' He established a theorem for the entropy production of open systems. It extended the second law of thermodynamics to the area of open, far from equilibrium, systems.

Throughout this taxing project he always stressed the role played by two further influences in his life. They were a second teacher, the experimentalist Jean Trimmermans (1882-1971) and what Prigogine later called "a performing school of theoretical biology" in Brussels. The concurrence of these two influences, he said, allowed him to gain confidence in the validity of his theoretical approach.

Nevertheless, a theoretician needs a philosophical impetus and vision as much as he needs experimental data. In his case this philosophical impetus and vision was provided by his readings of Bergson. Later, in the early fifties, he had the opportunity to meet Alan Turing in Manchester. He said that at the time he did not fully grasp Turing's monumental ideas on pattern formation in the molecular reaction-diffusion systems. But, as he described it, this "thought matured in him" so that he eventually came to grasp the overall picture by focusing his attention on the study of instabilities. He and his co-workers passed on this work to the international bibliography as "the Turing instability". Prigogine was then able to suggest systems with a varied repertoire of behaviour - chemical oscillations, pattern formations and emergent, complex properties that manifest in the course of their dynamic evolution.

It was in this context, and while pursuing the understanding of an unexplained, at that time, set of oscillating chemical reactions - the famous 'Belusov-Zhabotinsky reaction' - that Prigogine introduced the concept of dissipative structures. Dissipative structures evolve out of fluctuations. Nevertheless, they are stable in themselves because in last analysis, they don't constitute mere fluctuations. They are described as "living in symbiosis with their environment". Once the exchange of energy and matter between the open system and its environment ceases, they simply disappear.

Prigogine and his two young students, at that time, Gregoire Nicolis and René Lefevre were able to propose a model in accordance with the theory of dissipative structures that could explain oscillatory chemical reactions. It remained in the scientific literature as "the Brusselator", a classic model by now, but highly controversial at the time when Prigogine and his co-workers introduced it. This model was especially controversial from the standpoint of 'catastrophe theory' pioneered and promoted by René Thom at the time.

Finally a deeper understanding turned the tide in favour of the theory of dissipative structures. Nonlinear System Analysis started to touch on many and diverse disciplines. Notably it resonated with the field of epigenetic and regulatory processes in biology, where ideas and concepts from systems far from equilibrium found one of their most fertile grounds of application. These achievements accumulated and eventually earned Ilya Prigogine the 1977 Nobel Prize for Chemistry, which was given to him for his contributions to the theory of dissipative structures in far from equilibrium irreversible systems. It was a field which Prigogine himself and his collaborators at that time, had initiated, laying the foundations for the study of non-linear complex systems in their contemporary setting.

Prigogine's work broke the path for several investigations regarding the philosophical and epistemological implications of the study of complex, non-linear and/or chaotic systems. Indeed, it was Prigogine's audacious fundamental work that enabled us to understand the most important aspect of complex systems.

However, one thing needs to be understood here: complex systems are not merely complicated. As a matter of fact, they need not be complicated at all. Their complexity lies in the structural interrelation among their parts and between these and the whole engulfing them. Nonlinearity, the sine qua non of complexity, defies simple causal superposition principles. A slightly different cause will result in a greatly different effect. Hence probabilities come to play a significant role. They reflect the inherent uncertainty associated with such systems and need to be incorporated, along with determinism, in the detailed study of complex systems.

Himself a great educator and humanist, Prigogine helped in the popularisation of the concepts arising out of his own work and field via an intense programme of public lectures, articles and books for the general public. His most famous contribution on this level is "La Nouvelle Alliance" (translated in English as 'Order out of Chaos'), written with Isabelle Stengers. Their book has been translated into twenty-some languages and has been recognised as a classic ever since it first appeared. He raised the educated public's awareness about the utility and applications of his research agenda. He also elucidated the philosophical and epistemological issues relating to his studies.

As early as the mid sixties, Prigogine started drawing to himself several teams of a diverse and interdisciplinary nature. They were from specialists studying the emergent, complex, social behaviour of ants and social insects, to chemists and physicists studying pattern formation far from equilibrium and phase transitions; cosmologists and high energy physicists; chronobiologists; system biologists and theoretical immunologists; pioneers in brain studies; and finally pioneers in climate dynamics. Even sociologists and economists drew - and still draw - inspiration and encouragement from his work.

A strong personality and well versed man not only in physics and chemistry but also in other sciences and the humanities, Prigogine demanded nothing less than a complete re-unification of the famous two cultures - the sciences and the humanities. Thus his insights and contributions dominated the field that he himself initiated.

Another great fascination of Prigogine was that of the "arrow of time". Since Gibbs and Boltzman, the reconciliation of macroscopic irreversible dynamics of thermodynamical systems with the underlying reversible microscopic dynamics of their constituents, has been the Holy Grail of statistical physics. Prigogine was fascinated by irreversibility and considered his Nobel-winning work as a first step towards finally incorporating the arrow of time into the fundamental laws of physics. He even dared to challenge the very notion of 'laws of nature' in order to tease out the point at which these idealisations need to be changed in order "to save the phenomena".

Later this new style of a 'neoplatonic-academy-kind-of-centres', as some have described it, would fertilise the creation of multi-and inter-disciplinary centres of complex systems around the globe - himself being on the board, or an honorary member of many of them. The recipient of numerous awards, honorary as well as operational, he had also earned himself such endearing appellations as 'the poet of thermodynamics', or 'the Heraclitus of modern science.'

Since he was also a great admirer of poetry and Greek philosophy - Paul Valery and the pre-Socratics in particular - he would jokingly deny these appellations fearing that people would think him to be as difficult to comprehend as Valery or Heraclitus. Once he was amused that a young student drew some analogies between Paul Valery and Giordano Bruno's poetry. He said something to the effect that he was not so surprised that students these days might know about Bruno's poetry, but that they are still able to read and appreciate Valery!

He also maintained a lifelong interest in archeology, particularly in the art of pre-Colombian America and that of the Cycladic civilisation. He could talk for hours about their 'rites of passage', their concept of time and their methods of time keeping, as vividly expressed in their art.

Prigogine was also very musical. An accomplished piano player, he would often pass many hours a day playing. "According to my mother I was able to read musical scores before I could read printed words"; he used to say. Playing the piano was for him so essential that he insisted on acquiring access to one as a non-negotiable condition for accepting his position as director of a research centre at the University of Texas in Austin. Nowadays this centre is called 'The Ilya Prigogine Center of Statistical Mechanics.'

Prigogine pursued many paths. Sometimes he even questioned his own older findings so that he could finally approach his much desired goal of his understanding of irreversibility. He was never discouraged or disappointed. He could never fail since he could never stop trying - even when he became too frail to be able to follow the latest developments.

Emergence, complexity, uncertainty, irreversibility: these are the pillars on which Prigogine believed he could rest the bridge unifying the 'two cultures' -- that of the sciences and that of the humanities. Revisiting Aristotle may be helpful in this respect. Aristotle maintained that plants are animals compared with rocks, but rocks compared to animals. Something similar applies to Prigogine's work on complex systems and their emerging properties. Complex systems could be seen as 'alive' compared to machines,but machines compared to living systems.

As we observe Prigogine's passing into another dimension, the sciences dealing with complexity find themselves at a crossroads. According to some skeptics, the very notion of complexity is ambiguous. Furthermore, the sceptics believe that it has given rise to a very ambitious project. They insist that its basic concept is far too all-embracing, holistic and blurred to ever become the subject of a proper scientific investigation. Needless to add that similar skepticism had been levelled in the past against the study of Time and Space, of Entropy and Information, of Cognition and Consciousness. Skeptics in science frequently want to fit reality into their static vision of science. But the real challenge for investigators would be to fit their vision of science into the dynamics of reality. We shouldn't allow our concepts to fashion the picture of the world. Rather we should allow the essence of the world to fashion the nature of our concepts.

Scientific thinking today has reached a stage which doesn't compare with that of any other in its history. The feeling is that Complexity and Emergence, Time and Space, Entropy and Information, Cognition and Consciousness are presently at the frontier of fundamental research in the physical sciences. Despite that, they cannot be defined in exclusively objective quantitative terms. The reason is simple. These four areas constitute also the ultimate prerequisites for the observations carried out in their name. As Prigogine once remarked, "you cannot do non-linear mathematics with a linear mind".

In our times the very foundations of what we perceive as a properly established epistemological ethos have been cast in doubt. This calls for a radically new kind of science - one that can reflect on its own foundations. It also calls for a new kind of scientists. They don't only need to be cognizant of their limitations. They need to be cognizant of their objectifications. In addition, they need to be aware of the relative merits of different, complementary or even seemingly contradictory approaches.

Never before has the need for qualitative change in science been so obvious -- and pressing. The importance of Prigogine's scientific contribution lies in that he has made such a radical change not only possible, but imperative. Indeed, Prigogine can be considered the prophet of an altogether new era in science. This fact ensures that the spirit of his work will survive him for a long time to come. It can only directly inform and inspire the struggle for introducing self-reflection into science.

Science is normally considered as a noun aiming at a very concrete object. It might be better conceived as a verb - i.e. as an indefinite and ever unfolding becoming. Prigogine will rest in peace if such a change occcurs.

Dr. Vasileios Basios is a physicist of the Centre for Nonlinear Phenomena and Complex Systems at ULB. During the first part of his stay in Brussels he worked with Ilya Progogine's team for four years.