Drop grains of sand onto a flat surface and they form a pile. Keep adding grains and eventually ya’ll witness an avalanche. The curious thing about avalanches is that yer can’t tell how big they is going to be. A single dropped grain could dislodge a handful of other grains or hundreds of grains or thousands or perhaps tens of thousands of ‘em. How odd that the same trigger, the dropped grain of sand, could generate results that vary over several orders of magnitude.
Of course, the size of the avalanche don’t depend on the size of the grain at all. Instead, it depends on the complex network of forces that exist within the pile when the grain hits. It turns out that when these forces are balanced just right, the scale of avalanches cannot be determined in advance. This balance is known as self-organized criticality and it is true of earthquakes, forest fires, stock market crashes, the size of which cannot be predicted in advance.
Now it looks as if web traffic is in this same state of self organized criticality.
At least that’s what Mikhail Simkin and a friend at the University of California, Los Angeles, tell us. They have looked at the traffic at various popular websites and say it looks remarkably like the way avalanches occur, with very little activity for long periods interspersed with huge spikes in traffic that can vary by orders of magnitude.
Simkin argues that the web is like a pile of sand in a state of self organized criticality. Instead of a network of forces between grains, the web depends on a constantly changing network of links between pages. At any moment, these links could generate a flurry of activity as the page becomes dugg or slashdotted, for example. But the traffic from such an ‘avalanche’ can vary over several orders of magnitude in an entirely unpredictable way.
(This seems so obvious that ah can’t quite believe that Simkin is the first to suggest this, but if he is, well done.)
The lesson for all ya bloggers out there is to keep dropping the grains of sand.
Ref: arxiv.org/abs/0711.1235: A Theory of Web Traffic