Physics: The Foundation of Diversity

Adrian Bejan, the J.A. Jones Distinguished Professor of Mechanical Engineering at Duke University, has published a new book titled “Diversity through Freedom.” This is Bejan’s fifth book written for a general audience, and it was published in February 2026 by Springer.

In previous books, Bejan has used his concept of constructal law — the tendency of all systems to evolve toward easier access to flow — to explain everyday phenomena that aren’t traditionally tied to physics. In his newest publication, Bejan departs somewhat from his previous line of thinking to instead focus on how this concept gives rise to the vast amount of diversity found in the natural world.

“Nature does not try to optimize its designs; it is not interested in finding maximums and minimums,” Bejan said. “In fact, perfection is the enemy of evolution, which means that large amounts of diversity in the world are unavoidable.”

This line of thinking stems from a paper that Bejan published in 2023 in the journal Biosystems. Aptly titled, “Perfection is the Enemy of Evolution,” the work shows how tiny tolerances for imperfection opens the design space for a variety of solutions by a substantial amount. And what is variety but a synonym for diversity?

In his new work, Bejan revisits several topics covered in previous books while also introducing new topics that relate constructal law to observed phenomena. The sizes and shapes of animals that fly, run and swim the farthest. Body types of elite athletes for certain events. Hierarchies found within human societies such as the consistently unequal distribution of wealth.

Where previous work showed how the physics of increasing flows into systems is responsible for many systemic designs, the new work delves into why, even within these naturally optimized solutions, a large amount of diversity is still found.

“I found myself questioning some of my previous conclusions,” Bejan explained. “I used to look at how physics naturally trended toward perfected solutions, but now I see that ‘good enough’ is all nature cares about. And diversity is the natural result.”

Bejan’s new work also delves into novel topics, often focusing on concepts that do not seem to relate to physics at first glance. For example, he examines the difference between spontaneously occurring diversity and diversity that is forced on a system from outside pressures.

The former, he says, will always lead to better outcomes and solutions that will stand the test of time. The latter, however, is a recipe for disaster. This view is heavily influenced by his time spent growing up in Romania behind the “Iron Curtain” before immigrating to the United States as a young man.

“The good idea spread naturally because it is useful to many. It attracts a crowd of all kinds, volunteers. This is the phenomenon of diversity in nature,” Bejan said during a speech while receiving the prestigious 2024 American Society of Mechanical Engineers Medal. “The good idea is like a beautiful flower that attracts the bees, painters, photographers and people in love. Be both, the flower and the bee!”