<em>How Nature Works: The Science of Self-Organized Criticality</em>

Per Bak's How Nature Works (Copernicus, 1996) was his definitive statement of self-organized criticality for a broad scientific and general audience. The book walked through the sandpile model, power-law distributions, the Bak-Sneppen evolutionary model, applications to earthquakes and forest fires, and speculative extensions to economics and neuroscience. Bak argued that self-organized criticality was not a curious property of specific systems but a universal organizing principle: complex systems with many interacting components naturally drive themselves toward critical states where small causes produce effects of any size. While peers found his claims overreaching, the book's core thesis — that power laws are signatures of criticality and criticality is a generic attractor — has been progressively vindicated by research showing that neural networks, ecosystems, financial markets, and even the cortical activity underlying thought exhibit the dynamics Bak described.