Ubiquity by Mark Buchanan, Weidenfeld & Nicolson, 拢20, ISBN
0297643762
CONSIDER this. At 11 am on a fine summer morning in Sarajevo, 28 June 1914, a
car carrying two passengers made a wrong turn. It stopped directly in front of
Gavrilo Princip, a 19-year-old Bosnian Serb student. Princip drew a pistol from
his pocket, pulled the trigger and killed the Hungarian Archduke Franz
Ferdinand. This initiated a chain reaction, leading to the First World War.
How could a chauffeur鈥檚 mistake lead to this cataclysm? Is this really a
meaningful interpretation of events?
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The tool of history, certainly, is story-telling after the fact. Why is this?
Why does it make no useful theoretical predictions? Why is it, in other words,
that 鈥淟ife is understood backwards, but must be lived forwards鈥�, as philosopher
S酶ren Kierkegaard put it. Mark Buchanan鈥檚 Ubiquity aims to answer
this.
Buchanan wants us to know that we live in a special time in which new ideas
are beginning to make it possible to see why history is the way it is.
Surprisingly, perhaps, the ideas it uses find their origin not in history, but
in theoretical physics. He proposes to explain why history is鈥攁nd even
must be鈥攑unctuated by dramatic, unpredictable upheavals. He promotes a
theory declaring that all past efforts to perceive cycles, progressions and
understandable patterns of change in history have necessarily been doomed to
failure.
That theory is self-organised criticality. The classic example is a heap of
sand, onto which grains are added. The pile organises itself into a sequence of
states. Unavoidably, these include avalanches of all sizes, including large
catastrophic ones. These are the critical states, way out of equilibrium. They
contrast sharply with the equilibrium flat beach, which is nothing dramatic
happening. You can also visualise the critical state as a nuclear reactor poised
to explode.
In the 13 years since its discovery, the idea of self-organised criticality
has spread like a whirlwind to scientific disciplines ranging from geophysics to
biology, economics鈥攁nd history.
The distribution of earthquakes by severity, for example, follows a 鈥減ower
law鈥� known as the Gutenberg-Richter law. The annual average number of
earthquakes of magnitude M is 10-bM (the constant b
turns out to be about 1). This is precisely what critical state thinking
predicts. By contrast, repeated efforts to find periodic patterns in earthquakes
have failed. None, it seems, exist.
More spectacular is the application to biology. Could it be that mass
extinctions are intrinsic outcomes of the dynamics of evolution? Try considering
them as co-evolutionary avalanches, where extinction of one species leads to the
extinctions of others in a chain reaction. Compare this to the traditional
environment of scientific thought, dominated by the view that nature is in a
state of equilibrium and balance. This leads to the unquestioned assumption that
mass extinctions must be caused by external cataclysmic events鈥攕uch as
meteorites.
鈥淭he sciences do not try to explain, they hardly even try to interpret, they
mainly make models,鈥� the mathematician John von Neumann once noted. Indeed, the
theoretical work on criticality is based on simple mathematical models that can
be studied either by mathematical analysis or by computer simulations. The
models are more metaphorical than one is used to in theoretical physics. It
would be asking too much to expect a model of biology to produce elephants. But
like all theoretical modelling it must stand the test of comparison with
nature.
The concept of 鈥渦biquity鈥� expresses the view that details are not important
in deciding the outcome. In 1998, Don Turcotte and Bruce Malamud from Cornell
University studied the distribution of forest fires in Australia and the US.
They found that the distribution could be understood from a simple 鈥渢oy model鈥�
developed in 1992 by Barbara Drossel and Franz Schwabl. This implies that the
forests are in the self-organised critical state.
In 1996, Roy Anderson and Chris Rhodes of the University of Oxford took the
same model and plugged in people in place of trees and measles in place of
fires. The result explained the distribution of measles epidemics on the Faroe
Islands in the North Atlantic. 鈥淚f this does not bring home the point [of
ubiquity], perhaps nothing will,鈥� Buchanan concludes: 鈥淭he ubiquity of the
critical state may well be considered the first really solid discovery of
complexity theory.鈥�
I must admit now that I am not your usual unbiased, emotionally detached book
reviewer. I was heavily involved with the discovery in 1987. Bearing in mind
previous disasters in popular science writing, it was with trembling hands that
I grabbed this book and turned the pages. Does Buchanan get it all right? Does
he really understand how this might change the way we look at the world? Does he
succeed in bringing to life the excitement of the discovery, and the subsequent
applications to a multitude of disciplines, usually believed to be beyond the
reach of the tools of theoretical physics?
He does. This is the book I wish I had written. I ended up with the good,
warm feeling that there is indeed someone out there listening and able to
communicate the novel way of thinking, without compromising scientific
integrity. Buchanan succeeds where others fail. Most books on complexity simply
skate from one topic to the next, failing to emphasise鈥攐r even realise
鈥攖hat we are dealing with a new set of fundamental ideas. 鈥淲ithout the
core ideas behind ubiquity, the very enterprise of science would be doomed from
the start,鈥� says James Crutchfield, physicist at the Santa Fe Institute. Indeed,
without ubiquity, science would degenerate into stamp collection.
Now back to history. How would 鈥渟and pile historians鈥� interpret the events
leading to the First World War? They would notice that in the world of sand
every grain is similar to every other: there can really be no question of any
one being a Great Grain. By understanding that the pile is always at the edge of
radical change, they would come to realise that there are always places on the
pile at which a falling grain can trigger world-changing events.
Had our driver in Sarajevo not made the wrong turn, other minor,
unpredictable, actions would have led to other cataclysmic avalanches, which
also could only be explained in hindsight. Revolutions are moments that got
lucky!
鈥淐ontingency is the affirmation of control by immediate events over destiny,
the kingdom lost for want of a horseshoe nail,鈥� as biologist Stephen J. Gould
has observed. And contingency is the hallmark of the critical state.