PERSON
Per Bak
The Danish physicist who discovered that complex systems naturally drive themselves toward the edge of catastrophe—and whose theory of self-organized criticality turns out to be the most rigorous framework available for understanding why the AI disruption happened when it did, at the scale it did, and why no one could predict it.
Per Bak was the physicist who proved that catastrophe is not an anomaly. Born in Denmark in 1948, he spent most of his career at Brookhaven National Laboratory in New York, where in 1987 he co-authored with Chao Tang and Kurt Wiesenfeld a paper proposing that large complex systems—sandpiles, tectonic plates, ecosystems, financial markets—spontaneously drive themselves to a
critical state where small perturbations can trigger cascading events of any size. He was frequently accused of overclaiming; his 1996 book
How Nature Works argued that
sandpile dynamics explained everything from earthquakes to evolution to stock market crashes. The trajectory of the science since his death in 2002 has been one of quiet, relentless vindication. In 2021, researchers demonstrated that the learning dynamics of
neural networks are generically attracted to a self-organized critical state; in 2024, optimal deep neural network performance was shown to occur precisely at