Physicist Per Bak experimented with complex systems by dropping sand on a table, one small grain at a time.
As grains accumulated the pile became steeper. Then avalanches started to occur. Bak recorded their size and analyzed the pattern. The distribution followed a power law — a long-tailed curve that also describes the size distribution of earthquakes, lunar craters, solar flares, power outages, wars, species extinction events, and many other phenomena. In a power distribution there are many more small events than very large ones, and the largest events are orders of magnitude greater in size.
Bak found that the sandpile eventually reached a critical state where it collapsed spontaneously. He called this ‘self-organized criticality’ because it happened without any external action. He described all of this in his book How Nature Works: The Science of Self-Organized Citicality (1996).
“If we drop a single grain of sand at one place instead of another, this causes only a small local change in the configuration. There is no means by which the disturbance can spread system-wide. The response to small perturbations is small. In a noncritical world nothing dramatic ever happens. It is easy to be a weather (sand) forecaster in the flatland of a non-critical system. Not only can he predict what will happen, but he can also understand it, to the limited extent that there is something to understand. The action at some place does not depend on events happening long before at far-away places.”
Things changed dramatically when the sandpile went critical.
“A single grain of sand might cause an avalanche involving the entire pile. A small change in the configuration might cause what would otherwise be an insignificant event to become a catastrophe. The sand forecaster can still make short time predictions by carefully identifying the rules and monitoring his local environment. If he sees an avalanche coming, he can predict when it will hit with some degree of accuracy. However, he cannot predict when a large event will occur, since this is contingent on very minor details of the configuration of the entire sandpile.”
Bak’s experiment offers deeper insight into the behavior of other complex systems, including many we have come to count upon as being stable.
Criticality marks a phase transition — a sudden and occasionally catastrophic change of state. In The Black Swan: The Impact of the Highly Improbable (2007), Nassim Nicholas Taleb calls these sudden, unexpected catastrophes ‘Black Swans.’
“A small number of Black Swans explain almost everything in our world, from the success of ideas and religions, to the dynamics of historical events, to elements of our personal lives. Ever since we left the Pleistocene, some ten millennia ago, the effect of these Black Swans has been increasing. It started accelerating during the industrial revolution, as the world started getting more complicated, while ordinary events, the ones we study and discuss and try to predict from reading the newspapers, have become increasingly inconsequential.”
Life is experienced, Taleb says, as “the cumulative effect of a handful of significant shocks.” The path of history is not foreseeable. We are certain to be surprised.
This article is an excerpt from a book in progress on collaboration and transformative change. It was first posted on January 9, 2018, on LinkedIn.