Jim Rutt defines a "Boltzmann brain" as a hypothetical self-aware entity that arises due to random fluctuations out of a state of chaos or thermal equilibrium, as postulated by Ludwig Boltzmann in the context of statistical mechanics. According to Rutt, while Boltzmann initially used these fluctuations to explain the improbable organization of the universe, the concept of a Boltzmann brain extends this to suggest that such entities could spontaneously form and possess a consciousness similar to human brains. These brains would be highly improbable yet inevitable within an eternally existing infinite universe. The concept serves more as a philosophical and theoretical puzzle, poking at the limits of our understanding of reality and the nature of intelligent thought, while also challenging the assumptions underpinning cosmology and the anthropic principle.

See also: emergence, evolutionary psychology, free will, quantum foundations