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.