phenomena, including: The magnitude of earthquakes (Gutenberg–Richter law) and frequency of aftershocks (Omori law) Fluctuations in economic systems such as financial markets (references to SOC are common in econophysics) The evolution of proteins Forest fires Neuronal avalanches in the cortex Acoustic emission from fracturing materials Despite the numerous applications of SOC to understanding natural phenomena, the universality of SOC theory has been questioned. For example, experiments with real piles of rice revealed their dynamics to be far more sensitive to parameters than originally predicted. Furthermore, it has been argued that 1/f scaling in EEG recordings are inconsistent with critical states, and whether SOC is a fundamental property of neural systems remains an open and controversial topic. Self-organized criticality and optimization It has been found that the avalanches from an SOC process make effective patterns in a random search for optimal solutions on graphs. An example of such an optimization problem is graph coloring. The SOC process apparently helps the optimization from getting stuck in a local optimum without the use of any annealing scheme, as suggested by previous work on extremal optimization. See also 1/f noise Complex systems Critical brain hypothesis Critical exponents Detrended fluctuation analysis, a method to detect power-law scaling in time series. Dual-phase evolution, another process that contributes to self-organization in complex systems. Fractals Ilya Prigogine, a systems scientist who helped formalize dissipative system behavior in general terms. Power laws Red Queen hypothesis Scale invariance Self-organization Self-organized criticality control References Further reading Papercore summary. Self-organized criticality on arxiv.org Critical phenomena Applied and interdisciplinary physics Chaos theory Self-organization