Even systems that are not designed to be adaptive do things their designers never meant. Computer operating systems and Wall Street stock-trading programs monitor their own activities, giving them a degree of self-awareness. A basic result in computer science is that self-referential systems are inherently unpredictable: a small change can snowball into a vastly different outcome as the system loops back on itself. We already experience this. 'The instability of computer programs in general, and operating systems in particular, comes out of these Gödelian questions,' says the MIT physicist Seth Lloyd.