Adrian Bejan - Design in Nature: How the Constructal Law Governs Evolution in Biology, Physics, Technology, and Social Organization

A most stimulating thought principle, framed in a nice and lively personal story. What I find most exciting is the exceptionally broad perspective that Bejan adopts for developing his concepts. Design in Nature is a fascinating read.

E WALD W EIBEL , Professor Emeritus of Anatomy, University of Bern

With wide-ranging examples and the iconic pictures to go with them, Bejan illustrates that nature is inherently an outstanding designer of flow configurations, which raises philosophic issues beyond the remit of thermodynamics. Is the distinction between animate and inanimate blurred by their common constructal design? This and many more issues are raised by Professor Bejans distinguished and original work, fittingly presented in Design in Nature.

J EFFERY L EWINS , Deputy Praelector, Magdalene College, Cambridge University

Bejan masterfully unifiesunder a deep common lawphysics, chemistry, biology and even part of the social sciences. His treatment of natural design, flow systems and complex order as spontaneously arising from flow optimization is novel, powerful and highly plausible.

M ASSIMO P IATTELLI -P ALMARINI , author of What Darwin Got Wrong and Professor of Cognitive Science at the University of Arizona

Copyright 2012 by Adrian Bejan and J. Peder Zane

All rights reserved. Published in the United States by Doubleday, a division of Random House, Inc., New York, and in Canada by Random House of Canada Limited, Toronto.

www.doubleday.com

DOUBLEDAY and the portrayal of an anchor with a dolphin are registered trademarks of Random House, Inc.

Grateful acknowledgment is made to the following for permission to reprint previously published material: : drawing used by permission of the Istituto Geografico de Agostini, Novara, Italy; all other images courtesy of the author.

Jacket design by Michael J. Windsor
Jacket illustration Daryl Balfour/Gallo Images/Getty Images

Library of Congress Cataloging-in-Publication Data
Bejan, Adrian.
Design in nature : how the constructal law governs evolution in biology, physics, technology, and social organization / Adrian Bejan, J. Peder Zane.1st ed.
p. cm.
Includes bibliographical references and index.
1. Pattern formation (Physical sciences) I. Zane, J. Peder. II. Title.
Q172.5.C45B45 2011
500dc23 2011015398

eISBN: 978-0-385-53462-8

v3.1_r1

This book is about design in nature as a scientific discipline, centered on a physics law of design and evolution: the constructal law. This law sweeps the entire mosaic of nature from inanimate rivers to animate designs, such as vascular tissues, locomotion, and social organization.

Discovering a unifying law of design in nature was not on my to-do list when I traveled to Nancy, France, in late September 1995. I was a forty-seven-year-old professor of mechanical engineering at Duke University who had come to deliver a lecture at an international conference on thermodynamics. Giving you a sense of how steeped my career was in mechanical engineering, I remember that I had brought flyers announcing the publication of my seventh book, Entropy Generation Minimization.

My work took a fateful turn during the prebanquet speech delivered by the Belgian Nobel laureate).

Figure 1. The phenomenon of design in nature unites the inanimate with the animate. The left side shows the delta of the Lena River in northern Siberia. The right side shows a cast of the human lung.

When he made that statement, something clicked, the penny dropped. I knew that Prigogine, and everyone else, was wrong. They werent blind; the similarities among these treelike structures are clear to the naked eye. What they couldnt see was the scientific principle that governs the design of these diverse phenomena. In a flash, I realized that the world was not formed by random accidents, chance, and fate but that behind the dizzying diversity is a seamless stream of predictable patterns.

As these thoughts began to flow, I started down a long, uncharted, and wondrously exciting path that would allow me to see the world in a new, and better, light. In the sixteen years since, I have shown how a single law of physics shapes the design of all around us. This insight would lead me to challenge many articles of faith held by my scientific colleagues, including the bedrock beliefs that biological creatures like you and me are governed by different principles from the inanimate world of winds and rivers and the engineered world of airplanes, ships, and automobiles. Over time, I would develop a new understanding of evolutionary phenomena and the oneness of nature that would reveal how design emerges without an intelligent designer. I would also offer a new theory for the history of Earth and what it means to be alive.

In addition, I and a growing number of scientists around the world would begin finding new ways to make life easier: better ways to design roads and transport systems; to predict the evolution of civilization and science, of cities, universities, sports, and the global use of energy. We would unravel the mysteries of Egypts Pyramids and the genius of the Eiffel Tower while demonstrating how governments are designed like river basins and how businesses are as interdependent as the trees on the forest floor.

All that lay in the future when I boarded the plane for the trip home. High over the Atlantic, I opened my notebook (the old-fashioned kind, with paper) and wrote down the constructal law:

For a finite-size flow system to persist in time (to live), its configuration must evolve in such a way that provides easier access to the currents that flow through it.

I was writing in the language of science, but the fundamental idea is this: Everything that moves, whether animate or inanimate, is a flow system. All flow systems generate shape and structure in time in order to facilitate this movement across a landscape filled with resistance (for example, friction). The designs we see in nature are not the result of chance. They arise naturally, spontaneously, because they enhance access to flow in time.

Flow systems have two basic features (properties). There is the current that is flowing (for example, fluid, heat, mass, or information) and the design through which it flows. A lightning bolt, for example, is a flow system for discharging electricity from a cloud. In a flash it creates a brilliant branched structure because this is a very efficient way to move a current (electricity) from a volume (the cloud) to a point (the church steeple or another cloud). A river basins evolution produces a similar architecture because it, too, is moving a current (water) from an area (the plain) to a point (the river mouth). We also find a treelike structure in the air passages of lungs (a flow system for oxygen), in the capillaries (a flow system for blood), and the dendrites of neurons in our brains (a flow system for electrical signals and images). This treelike pattern emerges throughout nature because it is an effective design for facilitating point-to-area and area-to-point flows. Indeed, wherever you find such flows, you find a treelike structure.