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Home OpinionsGetting
to know Ilya Prigogine |
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Getting to know Ilya
Prigogine
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Part 02: The
interview
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 Note:
Professor Prigogine sat down to meet with SCIENTECMATRIX.com
(SCM) shortly after the Third Prigogine Seminar at the
University of Brussels, dedicated to the subject "Penser la
Science: Qu'est-ce que l'information?" ("Thinking about
Science.What is information?") in early February 2002. The
interview refers to the seminar on one or two occasions.
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SCM started by asking Professor
Prigogine, whether his theories on chaos, irreversibility and
the arrow of time now have been accepted by the international
scientific community at large. But our interviewee hardly
needs to be encouraged to give us an overview of his ideas:
Ilya Prigogine: The macroscopic aspect, the creation of
structures, the non-equilibrium (*) system has been accepted.
Of course you know, in the present scientific community there
are always people who rediscover the same thing, in different
forms. But on the whole I would say it has been accepted. Now,
my aim and my ambition is still to create a microscopic
structure and this is not accepted generally for two reasons.
First of all it, is a very new point of view, and
secondly, the papers which I published about this could always
be criticised for, I would say, a certain lack of rigorous
mathematics. And it is only over the last two years that we
have now an exact mathematics leading us to laws including the
time symmetry breaking on the microscopic level. There have
been already some papers published in The Physical Review, and
I suppose that they will be accepted because they are exact,
reasonably rigorous and based on good mathematics. This is
relatively recent. Before, we always had to use also some
intuitive arguments, allowing to just say: maybe, maybe not,
this question is open… This discussion has been going on for
at least 150 years.
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As I often say, it is the contradictory
heritage from the 19th century, of deterministic dynamics that
needs classical equations. This is deterministic(*).
Probabilities are introduced by our measurement.
Irreversibility(*) is an approximate concept, the result of
our mistakes, you could say, or our ignorance (…)
My
point of view has always been that we need an extension of the
laws of dynamics. And after many years, I must say, with the
help of my younger colleagues, we have now an exact theory
which is based on a classification of dynamic systems. You
see, what is so curious and very important is that
irreversible systems enter reversible systems. If every system
would be irreversible, that would be simpler. If every system
would be reversible that would also be simpler. But you have
the two classes.
When you look at the tidings and the
movements of the moon, etc. you can predict them with a
precision that you cannot expect in time-irreversible
dynamics. On the other hand, when you take heat conduction
then you come to uniformity in an irreversible way. Therefore,
you have two types of systems. The question is: what is the
difference between the two?
That is why I saw that
we first had simpler systems, which is due to classical
quantum mechanics, and now we have to extend them to
non-reversible systems: to systems that represent an arrow of
time (*). |
Integrable
and non-integrable systems (*)
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 This is possible when you start with the
classification of dynamic systems given by Poincaré (*) in
which he made a distinction between 'integrable' systems and
'non-integrable' systems. Integrable systems are systems in
which you can eliminate the interaction.
You come out
with systems which are formed by independent particles which
are essentially independent of the outside world. So consider
a gas of a thousand particles and suppose there is no
interaction. The momentum of each molecule will be conserved.
Therefore each molecule will continue to move independently of
most other parts. And this is certainly an integrable system
and it is a time-reversible system. |
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 But if you consider interactions, then
the question is: can you eliminate interaction, or can you
not? If you can eliminate interaction, you have an integrable
system. If you cannot eliminate interaction you have a
non-integrable system.
What we have done over the last few
years is to study the dynamics, classical or quantum, of
non-integrable systems. And there we are sure that
non-integrability is, according to Poincaré essentially due to
resonance. For example, if you have an electron which falls
from a higher level to a lower level, it emits a proton. You
have a resonance between the photon and the electron and the
atom. That is an old idea, suggested by Einstein and Bohr at
the beginning of last
century. |
Dissipative
structures (*)
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I. Prigogine: Non-integrability is
related to resonances. So the technical question is: how can
you eliminate resonances? And so, in all methods it is
essentially a matter of eliminating resonance. But once you
eliminate resonance in a non-integrable system, this means the
solution cannot be found on the level of trajectories, it can
only be on the level of statistics, of many particles.
It is like a social system: you cannot do social
theory for individual people. You cannot make sociology for
you and me alone. We are embedded in society. We cannot
imagine ourselves as being independent. And the same is true
for a town. If you see a town, it is a well-defined structure,
but it is an open structure. In other words, it only exists
because the town is surrounded by a country-side and there are
exchanges of values, exchanges of people that visit... |
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... the town and the neighbourhood. And
that is very different from the structure as you see it in a
crystal. The crystal isno more in interaction with the outside
world. It is a closed system. So essentially the idea that we
have pursued has shown that for non-integrable systems you
again obtain objects which are in interaction all the time
with the outside world. In other words, they are like
dissipative structures on the microscopic level. And in
essence, life is not a microscopic but a half-microscopic
thing, a cell, some millimetres or whatsoever, is always an
open system. A cell can only survive because it takes air, or
eats. It is again a kind of dissipative structure or closed
dissipative structure. Of course if you say it is a
dissipative structure, you are not saying much, because you
have to give more precisions, you have to speak of nucleic
acids, about proteins, but still it belongs to this class.
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The
arrow of time (*)
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I. Prigogine: What we have shown now is
that for elementary atoms or molecules when you take into
account the excited state or save a particle, you come again
to the same, you come to units which are no longer
independent. You come to units in which one is floating in the
sea of the other. So you have a more coherent view of the
universe. And the arrow of time is related to this floating,
this perpetual interaction between one particle and the other.
And therefore, you come again to the arrow of time. So, in my
opinion, the arrow of time is a fundamental property of all
nature. It is there on all levels, elemental particles as I
indicated, atoms, molecules, life, town, sociology... And I
think this is not absurd, because we see every evolutionary
aspect, cosmology is an evolutionary cosmology, stars are
evolving, so I cannot think of any example of a
non-evolutionary system. Except that you maintain it in
equilibrium, and even in an equilibrium, which is a particular
case because in equilibrium, you have as many partners: you
have got a that becomes b, and you have b that becomes a -
that's equilibrium. It has no arrow of time. But this is
obviously a special case. In general, you would have more a
going to b, or b going to a – in general you have an arrow of
time.
So, essentially, I consider equilibrium situations -
situations which are no arrow of time - as an exception, and
non-equilibrium situations as being the rule.
But even if
you speak about the Earth and the Sun, or the Moon...
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...and the Sun: it is true that if you
consider these two objects as isolated, you can apply Newton;
we generalise it. You see, for example, a simplification is
the Sun, the Earth and Jupiter, which is by far the biggest
planet. And our planetary system is only so stable because
there is a big Sun and a big planet Jupiter, so the particles
that are in cannot easily escape. However, when you consider
the three-body problem, you have already very strange
irreversible behaviour.
For example, what is shown on
computer, when you have got three particles in attractive
interaction, after some time you will have one particle going
away and the two others coming closer. I think that is very
convincing that there is already some irreversibility.
In
human life, of course, the arrow of time is very fundamental.
I think that in life it is necessary in all situations. And
then of course uncertainty, because the arrow of time, there
is probability – that is the meaning of an arrow of time, that
nothing is determined - and life is only possible because of
uncertainty. A plant has to know when it should flower, that
is a decision. It may go wrong, and then it will die. And I
think what characterises humans is that uncertainty is around
over a very long period of time. We think about our children,
we think about the next generation and that introduces a long
time-scale. |
Art and physics
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Prigogine: The direction of time
is really a fundamental extension of dimension. And as I
mentioned, you see, in my lecture, you have essentially a
conflict between prediction and the uncertainty of the future.
You come to the problem of death, you come to the problem of
literature, of art, of music. A while ago a colloquium was
held, and a book edited under my direction "L' homme devant
l'incertain" ("Man facing uncertainty"). I will see to it that
you get a copy. "L' homme devant l'incertain" that is true for
many things, whether from the viewpoint of cosmology,
dynamics, biology, music etc. There are also interactions
between modern music and modern art, for example, which have
been very much inspired by the discoveries in physics. For
example, you can find chaos in certain types of music, and
fractals (*) in some kinds of paintings. So there is a strong
interaction.
Last week you said: « La
créativité se porte bien dans un contexte de probabilité… »
(Creativity thrives in a context of
probability)
Prigogine: Yes, because if there were determinism, there
would be no creativity. Everything would have been given. When
I was young, I liked the vision of Henri Bergson (*),who said:
"It appears that I experience creativity every day." So in
essence, when you speak, when you hear, you write something,
you are doing something which did not exist before.
It is
inconceivable that we should be living a life where everything
is predicted, and this discussion has been going on for 2500
years. Take for example conflict between Parmenides and
Heraklitos. Parmenides said: "Nothing new can appear. What
exists, exists, and what does not exist does not exist." But I
think that, due to the fact that he wrote a new book shows
that he was contradicting himself. The fact that he expressed
himself this way obviously changed our view. Therefore, to
deny creativity is self-contradictory. Besides, should
creativity only be related to humans? This is very unlikely,
as what we are doing, making airplanes and so on, has already
been done in nature: there are many flowers who 'use a type of
airplane' to disseminate.
You write somewhere
that "Matter is more integrated than we usually believe…" and
that "The gap between life and non-life is smaller than we
think... Chemical communication between molecules over long
distances and long periods of time, also in non-living
systems." Could you explain that a little?
Prigogine: No, matter is more complex,
because matter can self-organise and before the idea of matter
was simply motion. But matter can give rise to the Bénard
instabilities (*), vortices, and collective coherent
behaviour. That is a relatively new idea of matter that is
self-organising in a situation that is far from being in
equilibrium. Matter can be ordered, and life is order. When
you see the complicated forms of matter which appear far from
equilibrium, you have the idea that life is a fluctuation far
from equilibrium.
You even say that
communication between molecules over long distances and long
periods of time also exists between non-living systems.
Prigogine: Yes, that is true. You have a
coherent system, you have communication over a long distance
because it is coherent; to act all together needs
communication over a large distance and over a long time,
because you see dissociations for seconds or minutes and you
know that. So, matter has a way of communicating over long
distances over a long time. And often I say: matter in
equilibrium is blind, and it communicates over short distances
over a short time. Matter out of equilibrium begins to see.
You used the word 'fluctuation' a moment ago
and you also said once that the Big Bang (cf. the Belgian
professor Lemaître s.j. and others) is also a kind of
fluctuation.
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But if you say that matter is
self-organising in principle, and if we agree that matter is
energy, then what is the principle that is organising
energy?
Prigogine: Well, I don't see exactly what you mean. Matter
is energy, that is true, but then what? If matter is
self-organising, and therefore energy is also
self-organising…
Yes - where does the energy
come from that makes matter
self-organising?
Prigogine: Well, the energy
is in our universe. And where do universes come from? I don't
know. Where are energies coming from? I don't know. But to
come back on your initial question about resonance: I don't
see how Sheldrake's idea of very long-range communication
could be interpreted as similar to the resonance of which I
speak.
Last Thursday you mentioned during your
lecture: "Exister, c'est participer ('To be = to take
part')
Prigogine: Yes, because you see: the
town is participating in the life of the country. Life is
participating in non-life. The atmosphere is changed because
of life. The first atmosphere was a reducing atmosphere, now
we have much oxygen, and that is because we are supposed to be
a product of life. And I mentioned that particles or atoms
exist because they are interacting with fields. In matter, the
atom interacts with the photon field by emission or
absorption. Therefore, we have now units which are interacting
all the time, which are embedded in the universe. Every day,
the separation of one element, and the change from one
dimension to another, is an approximation, and also a very
valid one. For example, if I have to analyse the enzymes, or
there is a possibility to create new organisms, … field
theory. Therefore, we do not exaggerate; not all levels are
strongly connected, but there is no level that is separated.
And there is no part of the level that is separated from the
other part. So in essence, as far as I know, I can say that
"to exist, is to participate". Notice that "to exist" does not
refer to "static being", but to active, dynamic participation.
This is also true for us, because it is evident that we only
exist because we participate. Whether this will still be true
after our death, I don't know, but in our life, we
participate, whether on the internet, at the university, in
our family, with friends, and so on. We cannot imagine an
existence that would not be temporal – existence is something
temporal, it is an arrow of time. This is not only evident on
our level, but it includes all levels of existence that are
levels of participation.
One final question: if
more people would be willing to accept your ideas, your world
view, in which way would it change the world as we know it
today?
 Prigogine: Well, it would
definitely lead to different mathematics, and different
physical explanations. And, although I don't want to make any
prophecy, I think it would also lead to a more unified western
culture, because, as I often write, historical human science
has always been time-oriented, whereas basic sciences are
generally not time-oriented.
People used to say to me:
time is not a subject for you to, it has been solved by Newton
and Einstein. Today, I don't think many people would say that.
But, you see, the problem of what is time and what is space is
more a question of in which medium are we living? And this is,
I think, a question which has interested everybody since
pre-historical times. This is one of the characteristics of
every life form, to be interested in the medium in which it
lives and exists. But no other species has been so interested
in the medium as human beings have.
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