Shape of rolling stones due to turbulence can connect the evolution of biophysics.

Professor Adrian Bejan of Duke University

Have we ever thought why larger animals live longer and travel further? This statement may seem to be quite simple but indeed has a lot of physics behind it and in this article, you will be astonished to know it. This simple law of physics extends to the simplest forms of mass migration on the planet like rolling stones flowing with the fast streams of rivers and the turbulent eddies forming in water and air currents. A research was been carried out at Duke University and the results found is quite fascinating.

After analyzing the results, Adrian Bejan, Professor of Mechanical Engineering at Duke University came to a conclusion that evolution not only applies to biological things but in any other physical system in motion. Bejan has been working in this field for a long time and he has even developed a physical law called the “constructal law“, which states that any flowing system allowed to change freely over time will trend toward an easier flowing architecture.

For the botanical domain of systems like rivers, roots, and vascular systems, this law applies in a way that limited large channels carry massive flows to abundant smaller branches for dispersal. Similarly for the zoological domain of systems like animals, a few large species with widespread, long-range influences on the environment act together with many smaller species touching smaller regions, but in greater numbers.

In his latest paper, Bejan illustrated that this idea can be generalized even further. He postulates that the most basic processes that have shaped the planet’s landscape for billions of years like rolling stones and turbulent water currents can also adhere to these physical laws.

Theory of Evolution

Bejan said, “I’m defining evolution literally to mean what the word implies, which is continuous change in a discernible direction over time.” What Darwin imagined for animals and called ‘evolution‘ is actually a physical description, and it applies to everything else that morphs freely while flowing, whether it’s biological or not. So my ‘aha’ is that evolution is everything because everything is in motion and is free to change while moving.”

Bejan solved a series of simple physics equations to prove his theory that both the time spent moving and the distance traveled of a rolling stone should increase with its mass. He further compared ” an eddy of turbulence” with the “fluid eye rotating in a fluid socket” and concluded that its lifespan and traveling distance also increase with its size.

Both processes have been responsible for moving objects across the Earth’s surface for billions of years. Bejan also points out that rolling stone evolve to have less friction so that they can travel further. That is, they become rounder over time.

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Previously Bejan worked on animal size, lifespan, and travel distance and established a fact that, despite the differences, all animals should have roughly the same number of breaths per lifetime. Comparing his previous theory on animals, Bejan injected the analyzing results in his new work and clinched that all other things being equal, all rolling stones and eddies have the same number of revolutions before their energy dissipates through friction.

Bejan further added, “These three characteristics,life span, life travel and the constancy of the number of breaths or revolutions of bodies that move mass, unite the animal, the eddy, and the rolling stone. Traditional camps believe that evolution is only biological and has already been explained to the hilt. I’m showing that evolution is actually based in physics and that it is simply designed change over time. To the origin of life in non-living matter, abiogenesis, rolling stones and turbulence add the physics of evolution.”

Well, this experiment may seem simple but its importance is undoubtedly significant in environmental science. This experiments will help us further in understanding the infinitesimal fundamentals of biophysics along with Charles Darwin’s theory of evolution proposed almost 150 years ago.


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