Constructal Theory: Introduction to the Inverse of Biomimicry
by Tim McGee, Helena, MT, USA on 12.12.06
A new theory, and possibly a new law of physics, Constructal theory can be understood as the inverse of biomimicry. Instead of looking to nature or biology to guide design, constructal theory starts from the understanding of the simple constructal law and extrapolates out a series of structures or designs for that situation. Amazingly, this new law of physics has been shown to describe the evolution of architecture found in nature. Let that sink in. A theory from the field of thermodynamics describes why a leaf looks like a leaf…why a river looks like a river…and much more.
Constructal theory not only enables scientists to better understand why Nature looks the way it does, but may give us insight into how we can shape our technology for a sustainable future. This Treehugger exclusive series will help our readers understand the exciting new discovery, and why it matters. To begin- The Constructal Law:
“For a flow system to persist in time (to survive) it must evolve in such a way that it provides easier and easier access to the currents that flow through it”. -Adrian Bejan
Biomimetics, Biomimicry, or bio-inspiration, has been around as long as humans. It’s incredible to look at nature and discover such complex and efficient designs. Biological organisms have evolved non-intuitive structures that fit perfectly with their environment. Biomimicry has proven to be a powerful tool when it comes to thinking about systems design, or even specific engineering feats like flight, or Velcro. Through biomimetics we can harness millions of years of trial and error from biological evolution. But what has guided those forms?
The theory of evolution is one of the most supported hypotheses in all of science. Indeed its explanatory and predictive power has made it the cornerstone of biology. Constructal theory goes further than the theory of evolution. Breaking the traditional boundaries between biology, physics, geology, and social sciences it describes how flow systems change through time. Biological organisms are flow systems. River basins are flow systems. Trees are a flow system. New York City is a flow system. Constructal theory says that for any of these flow systems to persist, to sustain, or survive, they must be structured (architecturally designed) in such a way that the things within that system increasingly get to where they need to go. This gives shape and structure to everything that evolves over time. Below is a concept drawing of how constructal theory evolves the concept of a branched structure into lung. Underneath the drawing are photographs of a lung and a river basin. One is biological, one is geological, and they operate on vastly different scales, but both utilize the same principle and have 'evolved' a similar architecture to solve a similar problem.
The lung needs to get air efficiently from one entry point to a volume. The upper river basin needs to get water from a volume to one exit point. Constructal theory has been shown to predict both structures.
This discipline spanning theory has been around for over ten years, and has been rapidly gaining attention in scientific circles. For those who can't wait, the constructal theory website has more research and background on the theory. The book, "Shape and Structure, From Engineering to Nature' by Adrian Bejan the founder of the idea, also provides an in-depth look at the science. Further exclusive in-depth posts will follow in the next few weeks. In the mean time, please feel free to ask questions, give ideas, or comment on the idea itself.
Constructal Theory: Introduction to the Inverse of Biomimicry
Constructal Theory: Sustainability
Constructal Theory: The Science
Constructal Theory: The Applications
Images used with permission from author::Constructal Theory Web Portal::Shape and Structure, From Engineering to Nature
While this is gorgeous stuff, I cringe at giving it this new name 'constructal theory.' Another name, familiar from your high school physics class, is 'derivation from first principles.' I'm glad it's getting press, and maybe a renaming is important for that, but people should keep in mind that these ideas, while fascinating, are not the sole purvey of people who call them 'constructal.'
Can someone explain what the difference is between this theory and Fractal based Chaos theory?
Can someone explain what the difference is between this theory and Fractal based Chaos theory?
Good question, I was just going to mention fractals.
From the amazon link:
Search inside the book:
Pg. 5
"They are not because according to Mandelbrot's definition of fractal dimension, a fractal is an object generated by repeating ad infinitum an algorithm based on postulated similarity rules. The infinite sequence of stages of branching or coalescence is notably missing from natural tree systems. The fractal algorithm user is forced to interrupt the sequence only after a few steps (the inner cutoff) so that this user may be able to see the drawing".
I don't know about you, but I like it. I always wondered about the infinite pattern of fractals and how that algorithm translated into finite structures. This "new" theory may suggest an answer to reality.
I am intrigued.
Common, we all know that the reason things are as they are is due to Intelligent Design! :)
This "new" theory is really not new at all.
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A. Note- that is correct, it is 10 years old, but its development and expansion is rather new, and new research on the theory is published all the time. In that sense, it is quite a new theory compared to say- evolution, or gravity.
It's great that this is getting press, but the reply to the comment about the theory not being "new" was way off base.
It's NOT new. It's a whole lot more than 10 years old. It was taught in my high school and college physics classes 14 years ago as something old as the hills, and fundamental to most aspects of physics. The idea of deriving outcomes of (biological, geological, astronomical, other) systems based on the simple laws that govern them is gorgeous, necessary, and very very old.
Giving an old concept a new name may get press, but I don't think it's good for science, because it makes people ignore all the beautiful work that other people have done, and not used this cute catch phrase. For example, very similar ideas are found in the scaling laws of West, Brown, Enquist and Savage that use basic physical laws of energy to predict how metabolic rates changes from a mouse to an elephant. (http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pbio.0020440)
That said, these ideas (constructal, derivation of scaling laws, etc) differ from, say, fractals, because simply describing a pattern as fractal like does not derive its shape from another property of the system. The cool thing here is that they are deriving the shapes from other properties of the system.
So "Go with the Flow" now has a scientific principle attached? I have lived this way for years...
KV- you are not alone in this criticism, many before you have said the same thing- Even many scientists I talk to today say:
"I have been doing this for 30 years, but we never called it constructal theory..."
Their experience has told them that they don't need a new fangled language to discuss what is essentially a well practiced method that they already knew and were comfortable with.
The problem with this criticism is that it misses the point- constructal theory is not a single rule or scaling law that describes 'HOW' a system works-
But, instead it is a fundamental law of physics that explains 'WHY' a system works. And it is a WORLD OF DIFFERENCE.
The scaling laws you mentioned can not reliably go beyond their data set model of experience, nor do they provide a reason for why this trend exists- they simply state that it does. Constructal theory provides a more fundamental understanding of the system, that enables not only an accurately prediction of the same scaling law, but go far beyond observed case studies (in fact all it needs is inputs to the system- no direct observation of results).
In my third piece I describe this difference in more detail, in hopes that I can better show you why it is an important difference. It is good to remain skeptical, but important to keep an open mind.