THE CREATING DISORDER

BY ILYA PRIGOGINE

Ilya Prigogine, Nobel Prize in Chemistry in 1977. The publication of this text has been made possible by the Institut du managemet d'EDF et de GDF, for which we obtained the original in French, and llya Prigogine himself, who He has authorized us to translate and publish this free stand.

Opinions about the notion of time are often varied and contradictory. A physicist will say that it has been introduced by Newton and that the problem that this notion poses has been globally solved. Philosophers think very differently: they relate time to other notions, such as becoming and irreversibility. For them, time remains a fundamental question. It seems to me that this divergence of views is the most net caesura within the Western intellectual tradition. On the one hand, Western thought has given birth to science and, consequently, to determinism; on the other hand, this same thought has contributed humanism, which refers us, rather, to the ideas of responsibility and creativity.

Philosophers like Bergson or Heidegger have argued that time does not concern physics, but metaphysics. For them, time clearly belongs to a different record, about which science has nothing to say. But these thinkers had fewer theoretical tools than we have today.

Personally, I consider that time springs from the complex. A brick of the Paleolithic and a brick of the nineteenth century are identical, but the buildings of which they were part have nothing in common: to see time appear the whole must be taken into consideration.

Non-equilibrium, source of structure

The work I have done thirty years ago has shown that non-equilibrium is a generator of time, irreversibility and construction. Until then, during the nineteenth century and much of the twentieth century, scientists had been interested, above all, in the states of equilibrium. Then they have begun studying the states close to equilibrium. Thus, they have avoided the fact that, from the moment in which a small distance from the thermodynamic equilibrium occurs, the coexistence of order phenomena and disorder phenomena is observed. It is not possible, therefore, to identify irreversibility and disorder.

The estrangement of balance reserves us surprises. We realize that we cannot extend what we have learned in a state of equilibrium. We discover new situations, sometimes more organized than when there is equilibrium: it is what I call bifurcation points (1), solutions to nonlinear equations. A nonlinear equation frequently admits several solutions: equilibrium or proximity to equilibrium constitutes a solution of that equation, but it is not the only solution.

Thus, non-equilibrium is the creator of structures, called diphysipat because they only exist far from equilibrium and claim to survive a certain dissipation of energy and, therefore, the maintenance of an interaction with the outside world. Like a city that only exists as long as it works and maintains exchanges with the outside, the dissipative structure disappears when it ceases to be "fed."

It has been very surprising to discover that, far from equilibrium, matter has new properties. It also amazes the variety of possible behaviors. Oscillating chemical reactions are a good example of this. For example, non-equilibrium leads, among other things, to undulating phenomena, in which the wonderful thing is that they are governed by extremely coherent laws. These reactions are not exclusive heritage of Chemistry: hydrodynamics or optics have their own peculiarities.

In balance, matter is blind; far from equilibrium matter sees

Finally, situations close to equilibrium are characterized by a minimum of something (energy, entropy, etc.), to which a reaction of small amplitude makes them return if they move away a little from it. Far from equilibrium, there are no extreme values. The fluctuations are no longer damped. Consequently, the reactions observed far from equilibrium are more clearly distinguished, and therefore, are much more interesting. In equilibrium, matter is blind, while far from equilibrium matter captures correlations: matter sees. All this leads to the paradoxical conclusion that non-equilibrium is a source of structure.

Non-equilibrium is an interface between pure science and applied science, although the applications of these observations to technology are only at the beginning. Currently, it is beginning to be understood that life is probably the result of an evolution that is directed towards increasingly complex systems. It is true that the mechanism that produced the first molecules capable of reproducing is not known exactly. Nature uses non-equilibrium for its more complex structures. Life has an admirable technology, which we very often do not understand.

Think in terms of probabilities, not trajectories

Non-equilibrium cannot be formalized through deterministic equations. Indeed, the bifurcations are numerous and, when the experiences are repeated, the path followed is not always the same. Therefore, the phenomenon is deterministic among the bifurcations, but is totally random in the bifurcations. It enters into & direct contradiction with the laws of Newton or Einstein, which deny indeterminism. Obviously, this contradiction has worried me a lot. How to overcome it? The current dynamic theory offers us particularly interesting tools in this regard. Contrary to what Newton thought, it is now known that dynamic systems are not all identical. There are two types of systems, stable systems and unstable systems. Among the unstable systems, there is a particularly interesting type, associated with deterministic chaos. In the deterministic chaos, the microscopic laws are deterministic but the trajectories take on a random aspect, which comes from the "sensitivity to the initial conditions": the smallest variation of the initial conditions implies exponential divergences. In a second type of systems, instability destroys the trajectories (non-integrable systems of Poincaré). A particle no longer has a unique trajectory, but different trajectories are possible, each subject to a probability.

We will group these systems under the name of chaos. How to treat this unstable world? Instead of thinking in terms of trajectories, it is convenient to think in terms of probabilities. Then, it becomes possible to make predictions for groups of systems. Chaos theory is something similar to quantum mechanics. It is necessary to study in the statistical field the functions of the evolution operator (make its corresponding spectral analysis). In other words, chaos theory must be formulated at the statistical level, but this means that the law of nature takes on a new meaning. Instead of talking about certainty, it speaks of possibility, of probability.

The arrow of time is, simultaneously, the common element of the universe and the distinguishing factor between the stable and the unstable, between the organized and the chaos. To go further in this reflection, it is necessary to extend the methods of analysis of quantum physics, especially leaving the Eucledian space (Hilbert space, in a functional sense) in whose sine it is defined. Fortunately, French mathematicians, first of all Laurent Schwartz, have described a new mathematics, which allows apprehending chaos phenomena and describing them in the statistical field.

But chaos does not explain everything. History and the economy are unstable: they have the appearance of chaos, but do not obey underlying deterministic laws. The simple decision-making process, essential in the life of a company, uses so many unknown factors that it would be illusory to think that the course of history can be modeled through a deterministic theory.

The second type of unstable systems evoked above is known under the name of Poincar systems. The resonance phenomena play a fundamental role in them, since the coupling of two dynamic phenomena gives rise to new dynamic phenomena. These phenomena can be incorporated into the statistical description and can lead to differences with the laws of Newtonian classical mechanics or quantum mechanics. These differences are evident in the systems in which persistent collisions occur, such as thermodynamic systems. The new theory demonstrates that a bridge can be drawn between dynamics and thermodynamics, between the reversible and the irreversible.

Instability should not lead us to immobility

We are in a "hinge" period of science. Until now, thought emphasizes stability and balance. It's not like that anymore. Newton himself suspected the instability of the world, but discarded the idea because he found it unbearable. Today, we are able to deviate from the prejudices of the past. We must integrate the idea of ​​instability into our representation of the universe. Instability should not lead to immobility. On the contrary, we must study the reasons for this instability, with the purpose of describing the world in its complexity and begin to reflect on how to act in this world. Karl Popper said that there is the physics of clocks and the physics of clouds. After having studied the physics of clocks, we must now study the physics of clouds.

Classical physics was founded on a dualism: on the one hand, the universe treated as an automaton; On the other hand, the human being. We can reconcile the description of the universe with human creativity. Time no longer separates the human being from the universe.

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