Self-Organized Criticality (Per Bak, 1988)
State of a system in which the effects of a constant-size perturbation vary from small to large according to a power law:
- N = # effects of a given size; S = size of effect
- N = S-k or lnN = -k*lnS (i.e. Linear log-log plot)
Edge of Chaos (“Complexity”) = Critical state
- Simple perturbations will normally have small effects, but occasionally large ones when they push the system into chaos
Fossil records of extinction events
- Show a power-law distribution => biosphere in critical state
- Major extinction events (loss of many species) need not require catastrophe theory as an explanation. The chance small perturbation may be enough.