Time and notion

July 17, 1998

He may have a Nobel prize, countless honorary doctorates and a viscountcy from the king of Belgium, but Ilya Prigogine's belief that time really does exist has alienated the physics community. Andrew Robinson reports

For a man who is totally preoccupied with the meaning of time, Ilya Prigogine is surprisingly indifferent to the millennium. "I hope to be alive," he says with a slight shrug of his 81-year-old shoulders.

Sitting in his office at the Free University in Brussels, where he has carried out most of his work, Prigogine goes on: "In all fields of science, history is important. We cannot understand biology without time, we cannot understand cosmology without the direction of time. Theoretical physics has been an exception, like a closed island. What I am trying to do is include time in the general picture of theoretical physics."

But most theoretical physicists, and indeed most scientists, are resistant to Prigogine's world-view, despite his Nobel prize, some 50 honorary doctorates and a viscountcy from the king of Belgium. They dislike his somewhat regal acceptance of recognition, his formidable rhetorical powers, his explicit desire to unite the humanities and the sciences - but most of all they dislike his basic scientific contention, which stems from his obsession with time.

Einstein held that time was "an illusion". And so have all the great names of physics, from Galileo and Newton to Steven Weinberg and Stephen Hawking. According to Hawking, "ordinary time" is something we humans invent "to describe our subjective impressions of the universe".

For Prigogine, by contrast, time is not man-made. "Time precedes existence," he says. Time predates the big bang. We are not father of time, but its children. Time, with its directional "arrow", forever dividing the past from the future, is no illusion of our minds, but a fundamental property of nature, both in the human world and - great physicists notwithstanding - in the atomic world.

So why did he come to view time so differently from Einstein? Prigogine struggles for an answer and finds one eventually, not in science but in history. He believes that Einstein was influenced in his view of time by the terrible history of the era he lived through: two world wars, the rise of fascism and communism, the Holocaust, the dropping of the atomic bomb.

"There was a difference of a generation (between Einstein and myself). In the 1930s Einstein perhaps had the impression of a decadent world, perhaps a little like Stefan Zweig who committed suicide because he was in despair about the future. I was young and I never despaired. For me time was always the hope of humanity." For Einstein, however, "time was an imperfection, and science, a way to get away ... from the turmoil, from the wars. Einstein wanted to find some kind of safe harbour in eternity."

Prigogine's rather different conclusion about time was reached despite the fact that he himself came much closer to extermination by the Nazis than Einstein. Born in Moscow in 1917 to a prosperous bourgeois family, he had to leave Russia in the wake of the revolution and eventually settled, aged 12, in Belgium.

In 1941, having completed his PhD in chemistry at the Free University, he was invited to work in Germany with a scientist who was a well-known Nazi, but he refused. Shortly after, the occupying powers began their arrest of Belgian Jews. Prigogine, his Jewish fiancee and her family were taken in, but somehow, through outside intervention, they managed to be released. He began clandestine teaching of students. After the liberation, he received a medal for his work in the Resistance, though he never took up arms.

With the war over, encouraged by the work of his supervisor, Theophile de Donder, Prigogine began to think about irreversible processes in nature. These are processes that show an arrow of time, in other words that do not show the typical reversible "equilibrium" behaviour of classical Newtonian systems, such as the planets orbiting the sun. If we run a movie of a swinging pendulum or a rolling billiard ball backwards, we see nothing absurd; these are virtually time-reversible equilibrium processes. But if we do the same with an egg that has just been scrambled, or a bull that has just destroyed a china shop, the result is comical, because of time's arrow. This fact is expressed in physics by the second law of thermodynamics: that in any irreversible process, the entropy (disorder) of the universe always increases.

But in the real world, far from equilibrium, we are surrounded by completely irreversible non-equilibrium processes, by life itself. The young Prigogine found himself asking some obvious questions. How is it that life does not seem to follow the basic Newtonian laws? If the tendency of the universe has always been towards increasing disorder, how is it that islands of order, such as plants and animals, have been able to evolve?

Half a century ago, most physicists and chemists regarded such questions as too mathematically intractable to admit of serious study. Prigogine recalls giving a lecture, after which the greatest expert in the field of thermodynamics commented: "I am astonished that this young man is so interested in non-equilibrium physics. Irreversible processes are transient. Why not wait and study equilibrium as everyone else does?" He says: "I was so amazed at this response that I did not have the presence of mind to answer: 'But we are all transient. Is it not natural to be interested in our common human condition?'" Not to be put off, Prigogine and his collaborator Paul Glansdorff discovered "a surprising fact: that the non-equilibrium world was not a world of disorder" - as the received wisdom had it - "but an interesting new world. Near equilibrium is a stable world - in which fluctuations always decay - but far from equilibrium, fluctuations create new structures, which I called dissipative structures."

An everyday example is the eddy/vortex. If you blow lightly on a flute, you do not hear a note; but if you blow harder and in the correct manner, you do. At first, the air molecules are simply disordered by your breath; but when you blow harder, they form patterns that give rise to the characteristic note. As long as you keep blowing, the patterns persist. These molecular "structures", which, of course, exist only transiently, are "dissipative", because they dissipate when you stop blowing. Human beings are dissipative structures too: if we stop eating, we eventually die.

Throughout the 1950s and 1960s, Prigogine and collaborators of the "Brussels school" developed their theory of the self-organisation of molecules. Then in 1968 Russian scientists observed a series of oscillating reactions, so-called chemical clocks, that apparently defied the second law of thermodynamics and seemed to endorse Prigogine's theory of dissipative structures.

The discovery gave Prigogine's theoretical work a large boost in scientific credibility, leading to his solo winning of the Nobel prize in chemistry in 1977, for "revitalising science with theories making possible the study of the most varied problems, such as city traffic congestion and the multiplication of cancer cells".

While Prigogine's work from this period is widely applauded, judgements about his more recent work over the past two decades range from cautious interest to outright dismissal, even contempt. According to the Scientific American journalist John Horgan, "scientists familiar with Prigogine's work - including the many younger practitioners of chaos and complexity who have clearly borrowed his ideas and rhetoric - have little or nothing good to say about him".

In this later work Prigogine maintains that "irreversibility subsists, whatever the precision of our experiments". In other words, science's inability to measure nature with total precision is not the result of human mental failings but of the element of chance built into the world by time's arrow.

In Prigogine's view, we should abandon any "dreams of a final theory" (Weinberg) and any hope that we shall soon read "the mind of God" (Stephen Hawking's much-quoted phrase). Instead we should embrace "the end of certainty". The world, says Prigogine, is neither entirely lawful nor entirely a game of chance. "Perhaps there is a more subtle form of reality which involves both laws and games, time and eternity." This, he says persuasively, would account for our human sense of free will and creativity.

His most persistent critic has been a Belgian physicist, Jean Bricmont. Though Bricmont says he admires some of Prigogine's earlier work, of his recent claims - that we need new laws of nature - Bricmont wrote: "Either (they) are taken literally, sound radical I and are plainly wrong. Or they areI are a rather confused way to express standard ideas."

Prigogine is clearly needled by Bricmont. "Bricmont puts what I'm saying upside down. He says 'Prigogine speaks about the end of science and science is the only rationality we have'. But what I'm saying is that we are speaking of a new science, a new rationality, that is necessary to explain the multiplicity of the world, to explain that you and I are meeting today, which was probably not programmed 15 million years ago. But I would not like to enter even a discussion with Bricmont. I despise his article."

However, Prigogine does admit that his non-technical books have lent themselves to misinterpretation. "This is partly my fault, because I came to the conclusion that irreversibility is a fundamental part of the laws of nature and announced this. But at this time (1980) my arguments were more intuitive; I appealed to common sense. I had some mathematics already, but it was not convincing, so criticism was possible. Now, the theory is mathematically exact."

Prigogine's books remain, for most people, a fascinating, if baffling mixture of exciting ideas, expressed in vivid language, along with impenetrable mathematics. His central message - that science can only progress by incorporating time's arrow and not by ignoring it or explaining it away - seems indisputable. But whether his analysis of how to do this is as seminal as he claims is less easy to assess. One has to conclude that only time will determine the true significance of Prigogine's work.

THE TIMES 7Jjuly 17J1998J13 credit Worldly wise: 8 'If we run a movie of a swinging pendulum backwards, we see nothing absurd. But if we do the same with a bull that has just destroyed a china shop, the result is comical, because of time's arrow'

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