Adrian Bejan | Constructal Law & Thermodynamics

Jul 22, 2025

In this video, Adrian Bejan explains how the Constructal Law expands the view of thermodynamics by showing that design is not just a human act but a natural phenomenon. He begins by revisiting the second law of thermodynamics, which was historically framed in the age of steam, with notable figures such as Carnot, Clausius, and Kelvin. Bejan defines the Constructal Law as a law of physics that accounts for the evolution of flow architecture in both animate and inanimate systems. Its central message is that flow systems persist by changing their configuration to provide greater access to their currents. Life, in this view, is a phenomenon of movement, and evolution is freedom to change.

Bejan presents the Constructal Law as: "For a finite size flow system (not infinitesimal) to persist in time (to live), it must evolve with freedom such that it provides easier and greater access to what flows."
He connects this to animate and inanimate systems, including human movement, animal locomotion, airplane design, and urban traffic, all of which show the same tendency to morph for easier flow.
Bejan contrasts the second law (movement from high to low temperature) with the Constructal Law (movement toward better configuration), stating that the former is about what happens, while the latter is about what comes next.
He emphasizes that design is a natural occurrence; it arises from physics, not imposed by intelligence or invention.
Bejan identifies freedom as the enabler of change, explaining that without the freedom to morph, systems cannot evolve or perform better over time.
He concludes that the Constructal Law is about life as movement, and its emergence in nature reveals how everything flows, everything morphs, and everything is connected through design.

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