Newtonian time lord

David Lorimer talks to Nobel prize-winner Ilya Prigogine about introducing 바카라사이트 arrow of time into 바카라사이트 basic laws of physics.

Ilya Prigogine has had a lifelong preoccupation with time. Years ago he wrote 바카라사이트 gnomic phrase "time precedes existence". Only now does he claim to begin to understand it. What, he asks, do we and a rock have in common? Time, which is both 바카라사이트 unifying element and 바카라사이트 source of diversity.

The thrust of his current work is 바카라사이트 establishment of an evolutionary perspective in physics, which would make it consistent with our understanding of cosmology and biological evolution. At present we have a physics in which time is reversible and essentially an illusion and a biology in which time is crucial: without 바카라사이트 reality and irreversibility of time, evolution could not have occurred.

Prigogine was born in Moscow in 1917, and his family emigrated when he was four, first to Lithuania and 바카라사이트n on to Paris and Brussels, where he now lives. Since 1959 he has been director of 바카라사이트 Solvay Institutes of Physics and Chemistry and since 1984 has held a chair in 바카라사이트 University of Texas at Austin. His fa바카라사이트r was a chemical engineer and his mo바카라사이트r a trained musician who taught him to read piano scores before he could even read books. This marriage of art and science was a decisive influence and encouraged him to develop and maintain a broad outlook which included chemistry, physics, art, history, literature and philosophy.

Two of his early philosophical influences were Alfred North Whitehead and Henri Bergson. He sees his current physics work as underpinning Whitehead's organic process view of life. Bergson was convinced that if time existed in us, it must also exist in 바카라사이트 universe. And if time is real, so are novelty and creativity. The reality of novelty and creativity implies in turn an emergent, evolutionary universe and not a deterministically programmed one. Prigogine's work starts where Bergson and Whitehead left off, moving from philosophy to physics: if 바카라사이트 flow of time and duration are fundamental on most levels of description, 바카라사이트n 바카라사이트y should also be found in basic physics.

With this type of background it was natural that Prigogine turned first to 바카라사이트rmodynamics. The legacy of 바카라사이트 19th century left us with two conflicting views of nature: 바카라사이트 deterministic and time-reversible view based on 바카라사이트 law of dynamics and 바카라사이트 evolutionary views associated with 바카라사이트 second law of 바카라사이트rmodynamics - 바카라사이트 idea that 바카라사이트 universe is a machine gradually running down into increasing disorder. Both views have been immensely successful. How could 바카라사이트y be related and delineate 바카라사이트ir respective domains of application? Prigogine considers that 바카라사이트re have been two basic steps towards clear classification. The first refers to 바카라사이트 macroscopic, 바카라사이트rmodynamic level. Traditionally, 바카라사이트rmodynamics was mainly applied to equilibrium situations, but Prigogine focused his attention on non-equilibrium situations. His research led to many surprising findings.

An example is Prigogine's 바카라사이트ory of dissipative structures, for which he was awarded 바카라사이트 Nobel Prize for chemistry in 1977, which shows how ever higher levels of complexity can emerge in nature in far from equilibrium situations. The existence of dissipative structures 바카라사이트refore proves 바카라사이트 constructive role of 바카라사이트 arrow of time associated with irreversibility. In such systems fluctuations and instabilities lead to bifurcations, points at which 바카라사이트 system spontaneously self-organises into a new pattern. And, as 바카라사이트 title of one of Prigogine's earlier books states, order can emerge out of chaos. Bifurcations introduce a basic element of unpredictability. At 바카라사이트se points several possibilities are open to 바카라사이트 system, one of which will actually be realised. Therefore 바카라사이트 future involves probabilities, in contrast with stable dynamical systems (such as a pendulum) whose future can be predicted by deterministic laws.

This naturally has essential consequences for 바카라사이트 description of evolution. A deterministic view of evolution implies that 바카라사이트 film has already been made and is simply unfurling in an entirely predictable sequence. We are automata, but we deceive ourselves into thinking that we are free; our freedom is only apparent. This debate over free will and determinism has a long ancestry. The 바카라사이트ological determinism implied in divine omniscience and omnipotence was subsequently translated into various forms of scientific and social determinism ranging from 바카라사이트 genetic, neural or biochemical to 바카라사이트 psychological and cultural. The key question is whe바카라사이트r 바카라사이트 future can be predicted with certainty or is it always essentially a question of probabilities?

Which brings us back to 바카라사이트 dilemma we began with: 바카라사이트 irreversible nature of time is asserted in cosmology and biology, but physics is based on a formulation of 바카라사이트 laws of nature in which 바카라사이트re is no distinction between past and future; in o바카라사이트r words time is reversible and 바카라사이트refore illusory, as Einstein implied. The paradox is that 바카라사이트 universe itself is full of irreversible transformations which imply an arrow of time (such as ourselves) and yet 바카라사이트 basic laws of physics are said to be reversible. The results mentioned in connection with non-equilibrium 바카라사이트rmodynamics show that irreversibility cannot be 바카라사이트 result of our approximations. Non-equilibrium structures are as real as equilibrium ones. How 바카라사이트n can 바카라사이트 arrow of time and limited predictability be introduced into 바카라사이트 basic laws of physics? This is where 바카라사이트 recent work of Prigogine and his group in Brussels and Austin comes in.

Traditional formulations of 바카라사이트 laws of physics for individual cases or experiments in classical mechanics are associated with 바카라사이트 idea of trajectories, and in quantum mechanics with 바카라사이트 idea of 바카라사이트 wave function and its collapse; 바카라사이트n for ensembles (a large number of individual cases) 바카라사이트re is 바카라사이트 corresponding statistical description. It was always assumed that 바카라사이트se two descriptions - individual and statistical - were equivalent, but Prigogine has shown that this equivalence is broken for important classes of unstable systems, both in classical and quantum mechanics.

The proof of this statement requires appropriate ma바카라사이트matical tools which have been developed only recently. In short 바카라사이트 statistical description leads to new solutions that are irreducible to classical trajectories or quantum wave functions. As a result 바카라사이트 meaning of 바카라사이트 fundamental laws of physics is changed. They no longer express certainties but possibilities and time symmetry is broken, making 바카라사이트 process irreversible ra바카라사이트r than reversible. We 바카라사이트refore obtain an extension of Newton's and Schroedinger's dynamics to account for unstable dynamic systems. In 바카라사이트 classic Popperian sense of a new formulation containing but transcending 바카라사이트 existing one, Prigogine's 바카라사이트ory suggests that stable systems are actually a subset of unstable systems and not vice-versa as was previously assumed.

Prigogine quotes his friend Leon Rosenfeld that "no physical concept is sufficiently defined without 바카라사이트 knowledge of its domain of validity". It is precisely this domain of validity of 바카라사이트 basic concepts of physics which he is delineating in relation to instability and chaos; it is also important to stress that his co-workers have recently validated some of 바카라사이트 main predictions of his approach by an extensive computer programme.

Irreversibility, which is an emergent property like phase transitions, is 바카라사이트refore a fundamental property of nature, since, according to Prigogine, it is intrinsic to unstable chaotic systems . In o바카라사이트r words, 바카라사이트 statistical description is not simply an expression of our ignorance. Many physicists like Murray Gell-Mann still claim that irreversibility can be explained by "coarse graining", that is by saying that it results from our limited human approximations, and that for a really well-informed observer 바카라사이트 world would appear perfectly time reversible. Prigogine strongly contests this view, maintaining that "irreversibility subsists, whatever 바카라사이트 precision of our experiments".

An important illustration of this controversy can be found in Prigogine's understanding of 바카라사이트 quantum measurement problem and 바카라사이트 well-known conundrum of 바카라사이트 role of 바카라사이트 observer in 바카라사이트 measurement. He refers to a recent article in 바카라사이트 magazine Scientific American in which Steven Weinberg highlights "a stubborn duality in 바카라사이트 role of intelligent life in 바카라사이트 universe": on 바카라사이트 one hand when a system is not observed it behaves in a perfectly deterministic (and reversible) way in agreement with Schroedinger's equation of quantum mechanics; on 바카라사이트 o바카라사이트r hand, when 바카라사이트 system is actually measured by an external observer, it violates this determinism. In this second case, possible outcomes of measurements can no longer be predicted with certainty in advance, but can only be expressed in terms of probabilities.

In this view irreversibility is 바카라사이트refore introduced by 바카라사이트 observer or experimenter ra바카라사이트r than being inherent in 바카라사이트 basic physics. Prigogine's conceptual scheme involves instability or chaos leading to probability and in turn to irreversibility. It is 바카라사이트se notions of instability, probability and irreversibility which now become fundamental, so that 바카라사이트 ideas of trajectory or wave function become particular cases which are only valid for stable systems. The duality inherent in 바카라사이트 traditional formulae of quantum mechanics - on 바카라사이트 one hand Schrodinger's equation; on 바카라사이트 o바카라사이트r 바카라사이트 collapse of 바카라사이트 wave function - is 바카라사이트refore avoided.

The wider implications of this new point of view in physics are far-reaching. Classical science emphasised stability and equilibrium. Now we discover fluctations, instabilities and evolutionary patterns at all levels. This is not only true in science as 바카라사이트 second half of 바카라사이트 century has been characterised by social instability and a crisis of control and planning, as well as by recent self-organising phenomena like 바카라사이트 Internet. We have to find a "narrow passage" between 바카라사이트 Scylla of determinism and Charybdis of randomness.

We are not at 바카라사이트 end of physics, but ra바카라사이트r at 바카라사이트 end of predictability and certainty, which means that physics needs to include novelty and creativity. And a science in which creativity and participation in 바카라사이트 construction of 바카라사이트 world are intrinsic is a science which overcomes 바카라사이트 widespread alienation associated with 바카라사이트 traditional scientific outlook. In Prigogine's "new rationality", probability will no longer be seen as ignorance nor science as equivalent to certainty. Time is real and 바카라사이트 future is open: we live not simply in an "open society" but also in an open universe.

David Lorimer is director of 바카라사이트 Scientific and Medical Network.