---
description: Bak argues that the default assumption across sciences -- economics biology geophysics -- that large systems are in stable equilibrium blinds researchers to the critical dynamics that actually govern these systems
type: claim
domain: critical-systems
created: 2026-02-16
source: "Bak, How Nature Works (1996)"
confidence: likely
tradition: "self-organized criticality, complexity science, statistical physics"
---

# equilibrium models of complex systems are fundamentally misleading because systems in balance cannot exhibit catastrophes fractals or history

Physics has two well-understood regimes for many-body systems: crystals (perfect order, every atom in its place) and gases (perfect disorder, every atom independent). Both are tractable precisely because they are uniform -- they look the same everywhere. Both are equilibrium systems. Both are simple. Bak argues that the real world -- landscapes, ecosystems, economies, brains -- is neither ordered nor disordered but poised at a critical state between the two, and that the equilibrium toolkit is useless for understanding it.

The argument is precise: equilibrium systems are linear. A small perturbation produces a proportionally small response. Contingency is irrelevant -- small freak events can never have dramatic consequences. Large fluctuations in equilibrium require many random events to accidentally align, which is "prohibitively unlikely." But the phenomena that actually matter -- earthquakes, mass extinctions, market crashes, wars -- are precisely the large fluctuations that equilibrium theory declares impossible. General equilibrium theory in economics "assumes that perfect markets, perfect rationality, and so on bring economic systems into stable Nash equilibria." The result: "Traditional economics does not describe much of what is actually going on." Economists "cull" or "prune" their data to remove large events, "which amounts to throwing the baby out with the bathwater."

The same equilibrium bias operates in biology, where nature is assumed to be "in balance" -- a view that motivates conservationism but makes evolution incomprehensible. "If nature is in balance, how did we get here in the first place?" The apparent equilibrium is merely a period of stasis between punctuations. And in geophysics, the Gutenberg-Richter law stares researchers in the face while they construct individual narrative explanations for each large earthquake.

Bak's alternative: the sandpile, not the flat beach. Economics is like sand, not like water. Decisions are discrete, not continuous. There is friction -- we don't continuously adjust our holdings to every price fluctuation. This friction prevents equilibrium from being reached, just as friction prevents the sandpile from collapsing to a flat state. The resulting dynamics are fundamentally different: avalanches of all sizes, 1/f fluctuations, and catastrophes that require no special cause. The space launch industry illustrates this vividly: [[the space launch cost trajectory is a phase transition not a gradual decline analogous to sail-to-steam in maritime transport]], where the shift from expendable to reusable rockets was a discontinuous rupture that equilibrium cost models completely failed to predict -- exactly the kind of phase transition that Bak's framework anticipates. Since [[the efficient market hypothesis fails because its three core assumptions rational investors independence and normal distributions all fail empirically]], Bak provides the deeper explanation: the failure is not in the specific assumptions but in the entire equilibrium framework. And since [[financial markets are inherently unstable at the system level because debt financing and mark to market accounting create self-reinforcing positive feedback loops]], the positive feedback dynamics of levered asset markets are exactly the kind of non-equilibrium behavior that the sandpile model predicts but equilibrium theory cannot accommodate.

---

Relevant Notes:
- [[the efficient market hypothesis fails because its three core assumptions rational investors independence and normal distributions all fail empirically]] -- EMH fails because markets are critical systems not equilibrium ones
- [[minsky's financial instability hypothesis shows that stability breeds instability as good times incentivize leverage and risk-taking that fragilize the system until shocks trigger cascades]] -- Minsky describes a specific mechanism by which economic equilibrium is unreachable
- [[financial markets are inherently unstable at the system level because debt financing and mark to market accounting create self-reinforcing positive feedback loops]] -- system-level instability is an expected property of critical systems
- [[democracies fail at information aggregation not coordination because voters are rationally irrational about policy beliefs]] -- political systems may also be poorly modeled by equilibrium assumptions
- [[complex systems drive themselves to the critical state without external tuning because energy input and dissipation naturally select for the critical slope]] -- provides the alternative to equilibrium: the critical attractor
- [[large catastrophic events in critical systems require no special cause because the same dynamics that produce small events occasionally produce enormous ones]] -- catastrophes are the signature behavior that equilibrium models declare impossible
- [[chaos produces randomness not complexity because chaotic systems have no memory and cannot accumulate structure over time]] -- both equilibrium and chaos fail to explain complexity, but for different reasons
- [[power laws in financial returns indicate self-organized criticality not statistical anomalies because markets tune themselves to maximize information processing and adaptability]] -- power law returns are the empirical signature that markets are critical systems not equilibrium ones
- [[equilibrium systems cannot generate complexity because response is always proportional to perturbation]] -- source-faithful treatment of why equilibrium frameworks fail for complex systems
- [[the space launch cost trajectory is a phase transition not a gradual decline analogous to sail-to-steam in maritime transport]] -- launch cost reduction as a phase transition that equilibrium models would miss: the shift from expendable to reusable is discontinuous, not incremental

Topics:
- [[maps/livingip overview]]