# The Back Half Of The Chessboard

I offered my complaint about Erik Brynjolfsson and Andrew McAffee *Race Against The Machine* yesterday, but I also want to praise one extremely important insight in the book that really changed my way of thinking about something. This is what they call “the back half of the chessboard” and they derive it from an old story about a Persian king who makes a deal in which he promises to pay someone as follows. On the first day, one grain of rice is placed on one square of a chessboard. On the second day, two grains go in the second square. On the third day, four grains go in the third square. On the forth day, it’s eight grains in the forth square. The king agrees, and of course it turns out that 2^64 grains of rice bankrupts the kingdom. But the point about the back of the chessboard is that even though the mathematical pattern is evident throughout the process, the actual impact is amazingly backloaded.

The point of this, in terms of technological progress, is that we’ve gotten so accustomed to Moore’s Law that we sometimes overlook the implication that the deeper we get into the chessboard, the *bigger the changes*. We all know that computers advanced a lot between 1991 and 2011, but we should expect the scale of change over the next 20 years to dwarf those changes. This is a straightforward application of a well-known principle and some pretty basic math, but it’s usually not discussed in quite the right way. We think we’re used to the idea of rapid improvements in information technology, but we’re actually standing on the precipice of changes that are much larger in scale than what we’ve seen thus far.