Why the World Is Simpler Than You Think
Buchanan, Mark, New Statesman (1996)
Earthquakes, forest fires, wars and stock markets: do they all follow a universal law?
In 1934, the historian H A L Fisher arrived at a rather bleak conclusion on the nature of human history. "Men wiser and more learned than I," he wrote, "have discerned in history a plot, a rhythm, a predetermined pattern. These harmonies are concealed from me. I can see only one emergency following upon another. . . and only one safe rule for the historian: that he should recognise in the development of human destinies the play of the contingent and the unforeseen."
Fisher was writing during the Great Depression, just 20 years after a chauffeur had touched off the First World War by taking a wrong turn, thereby enabling an assassin in Sarajevo to kill the Austro-Hungarian Archduke Franz Ferdinand and his wife. To Fisher and his contemporaries, accidents of all sorts seemed charged with an alarming power to set the world on its head. One day in 1920, a pet monkey bit and infected the King of Greece. The king's subsequent death set off a chain of political events that led to war between Greece and Turkey. "A quarter of a million persons," as Winston Churchill later commented, "died of this monkey's bite."
Today, we may all feel that Fisher's view was needlessly pessimistic, a mere product of the times. And yet, one may still wonder: do we really know anything about the natural dynamics and rhythms of history? Can we do anything more than guess as to whether there is "a plot, a rhythm, a predetermined pattern"?
It may sound ridiculous, but it is my belief that a new perspective on these questions may be emerging from, of all places, theoretical physics. It suggests that Fisher's suspicions were indeed well placed - that the course of human affairs possesses a rather extraordinary kind of unpredictability, and may always escape our efforts to understand it in terms of general causes and effects. What's more, it may be something like a law of nature that history must, by necessity, be punctuated by inexplicable and utterly unforeseeable upheavals.
To see the roots of this unlikely connection between physics and history, imagine sprinkling grains of rice on to a table, one by one. As a pile grows larger and steeper, avalanches will occasionally carry some grains down the sides. This much is clear. But where and when should we expect the avalanches? What is their typical size? And what are the conditions that set up the really big ones? Over the past decade or so, physicists have tried to answer these questions.
What makes a rice pile interesting to physicists is that the forces at work do not find immediate release. Sprinkle droplets of water on a placid lake, and each will quickly disappear, swallowed up as the surface of the water becomes flat once more. The water level will gradually rise, and yet the history of the process is fairly boring. In the pile of grains, however, stress accumulates slowly, only to be released in sudden, spontaneous avalanches. When a grain falls in one place rather than another, this event is not washed away, but alters the entire course of the future. So the pile bears the long traces of the past and, in its workings, history matters in an important way.
In the late 1980s, physicists at the Brookhaven National Laboratory in New York State worked out the elements of the following basic picture. (They were envisioning a pile of sand, rather than rice, but this is of secondary importance.) At first, they found, before the pile has become steep, a falling grain can trigger only small avalanches. One grain may trigger another to tumble, and this may induce another to slide as well, but the chain reaction will die out quickly. As grains continue to rain down, however, many grains eventually come to be balanced uneasily on steep slopes, barely hanging on. The pile evolves naturally to a condition in which a single grain has the potential to trigger a domino-like reaction of tumbling grains that can sweep through the entire pile. …