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A review by davidr
Design in Nature: How the Constructal Law Governs Evolution in Biology, Physics, Technology, and Social Organization by Adrian Bejan
2.0
In this book, Adrian Bejan hypothesizes a principle that he names the "constructal law". It states that everything in nature configures itself and reconfigures itself to increase flow, or to make flow more efficient.
What does Bejan mean by flow? Any concrete object or abstract concept can flow. Water can flow, air can flow, blood, heat and electricity can flow. Also, knowledge, concepts, memes, ideas, and data are things that flow.
By "design", Bejan does not mean that somebody designed the flows. He means that the flows configure themselves into a design.
A prime example of the constructal law is the flow of rainwater. It falls everywhere, and drops of water coagulate into millions of branchlets, which combine into thousands of tiny streams, hundreds of large streams, creaks, and a smaller number of rivers. This hierarchy is "designed" to maximize the flow of water. The circulatory system in animals and humans is similarly configured into capillaries, small and large arteries. The trunk of a tree is divided into a few stout branches, more thin branches, and many very thin branches and then to leaves, a structure that helps to maximize the flow of water through the tree and into the atmosphere.
A road system starts out with lots of narrow dirt roads, fewer paved side roads, fewer major roads, and fewer main highways. This system maximizes the flow of traffic. The diffusion of knowledge follows a similar pattern, as does the flow of athleticism through high schools, colleges, and on into professional sports.
Bejan uses mathematical formulas to back up his claims that these designs help to maximize the various flows in nature.
But I have a few complaints about the book. First, it is very repetitive. This type of book, where a major claim of a new idea is made, seems to fit a pattern where the author self-aggrandizes the importance of his new idea or theory.
I always thought that the "purpose" of an organism is to reproduce its own genes. But Bejan claims that the purpose of all organisms is to maximize flow. The purpose of a tree, for example, is to maximize the flow of water from the ground into the atmosphere. The purpose of a fish is to undulate and churn the water in the ocean, to mix it and to make it flow more rapidly. This seems so bizarre to me.
Many things in nature organize themselves by some power law. The book is filled with graphics that demonstrate these power laws over a diverse variety of "flows". Bejan claims that this is evidence in favor of the constructal law. He claims that the constructal law is a law of physics, but when he claims that the fact that the frequency of words in language obeys a power law is evidence of a law of physics, I have a hard time agreeing.
There is a core of genius in the constructal law. But it is buried in some tedious, repetitive language. Perhaps the author could clean it up. At the same time, he could demonstrate not only what but also how these structures configure themselves to obey the constructal law.
What does Bejan mean by flow? Any concrete object or abstract concept can flow. Water can flow, air can flow, blood, heat and electricity can flow. Also, knowledge, concepts, memes, ideas, and data are things that flow.
By "design", Bejan does not mean that somebody designed the flows. He means that the flows configure themselves into a design.
A prime example of the constructal law is the flow of rainwater. It falls everywhere, and drops of water coagulate into millions of branchlets, which combine into thousands of tiny streams, hundreds of large streams, creaks, and a smaller number of rivers. This hierarchy is "designed" to maximize the flow of water. The circulatory system in animals and humans is similarly configured into capillaries, small and large arteries. The trunk of a tree is divided into a few stout branches, more thin branches, and many very thin branches and then to leaves, a structure that helps to maximize the flow of water through the tree and into the atmosphere.
A road system starts out with lots of narrow dirt roads, fewer paved side roads, fewer major roads, and fewer main highways. This system maximizes the flow of traffic. The diffusion of knowledge follows a similar pattern, as does the flow of athleticism through high schools, colleges, and on into professional sports.
Bejan uses mathematical formulas to back up his claims that these designs help to maximize the various flows in nature.
But I have a few complaints about the book. First, it is very repetitive. This type of book, where a major claim of a new idea is made, seems to fit a pattern where the author self-aggrandizes the importance of his new idea or theory.
I always thought that the "purpose" of an organism is to reproduce its own genes. But Bejan claims that the purpose of all organisms is to maximize flow. The purpose of a tree, for example, is to maximize the flow of water from the ground into the atmosphere. The purpose of a fish is to undulate and churn the water in the ocean, to mix it and to make it flow more rapidly. This seems so bizarre to me.
Many things in nature organize themselves by some power law. The book is filled with graphics that demonstrate these power laws over a diverse variety of "flows". Bejan claims that this is evidence in favor of the constructal law. He claims that the constructal law is a law of physics, but when he claims that the fact that the frequency of words in language obeys a power law is evidence of a law of physics, I have a hard time agreeing.
There is a core of genius in the constructal law. But it is buried in some tedious, repetitive language. Perhaps the author could clean it up. At the same time, he could demonstrate not only what but also how these structures configure themselves to obey the constructal law.