I was delighted to see my old friend the tensegrity in the news coverage of the Rover’s landing on Mars. Since tensegrities are the strongest structures in Universe, I was not surprised to discover they had successfully protected the Rover during landing.

TENSEGRITY

Timothy Wilken, MD

Buckminster Fuller studied Universe’s organizing strategies for over fifty years. Of all the synergic patterns in Universe, the most powerful onehe found was the tensegrity. Tensegrity is a contraction of the terms “tension” & “integrity“. A tensegrity is a balanced systemof pushand pull.

Push & Pull

Tensegrityis the pattern that results when push and pull have a win-win relationship with each other. Buckminster Fuller explained that these fundamental phenomena were not opposites, but complements that could always be found together. He further explained that push is divergent while pull is convergent. Tensegrity is a pair, like many co-existing pairs, of fundamental physical laws – push and pull – compression and tension – repulsion and attraction.

Push and pull seem so common and ordinary in our experience of life that we humans think little of these forces. Most of us assume they are simple opposites. In and out. Back and forth. Force directed in one direction or its opposite.

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Fullerexplained that these fundamental phenomena were not opposites, but compliments that could always be found together. He further explained that pushis divergentwhile pull is convergent.

Imagine pushing a ping-pong ball on a smooth table with the point of a sharp pencil. The ball would always roll away from the direction of the push, first rolling one way then the other. Push is divergent. Now imagine the difference, if you attach a string to the ping pong ball with tape, and pull it toward you. No matter how other forces might influence the ball to roll away from you, the string would always bring it to you more and more directly. Pull is convergent.

Another example from common experience occurs when we are pulling a trailer with a car. When driving uphill, one is pulling against gravity. The trailer converges into a course behind the car. If the trailer begins to sway, increasing pull by increasing acceleration can dampen the swaying motion.

Driving downhill, however, the trailer may begin to push. This produces a strong side to side force – divergence. The trailer will begin to sway from side to side. Push again, is divergent. When the trailer begins to push, experts advise to accelerate slightly in order to re-establish pull. Pull is convergent, and the trailer will straighten course.

The Balloon

A common example of a tensegrity is in a child’s balloon. When examined as a system, the rubber skin of the balloon can be seen as continuously pulling (against the air inside) while the individual molecules of air are discontinuously pushing against the inside of the balloon keeping it inflated. All external forces striking the external surface are immediately and continuously distributed over the entire system, meaning the balloon is very strong despite its thin material.

The automobile tire works the same way. It is the tensional integrity in in the tire that yield a low failure rate despite the wear of high speeds and long miles.

A tensegrity then is any balanced system composed of two elements – a continuous pull balanced by discontinuous push. When these two forces are in balance a stabilized system results that is maximally strong. The air bags protecting NASA’s Rover are tensegrities. 

Larger structures

Tensegrity also refers to a means of creating structures. Tensegrity was first explored by artist Kenneth Snelson to produce sculptures such as his 18 metre high Needle Tower (1968). The idea was adopted into architecture in the 1980s with David Geiger designing the first significant structure – a competition hall for the Summer Olympics of 1988.

The term ‘tensegrity’ was coined for Snelson by Buckminster Fuller from tensional integrity. His famous geodesic domes are themselves tensegrities: “The great structural systems of Universe are accomplished by islanded compression and omnicontinuous tension. Tensegrity is a contraction of tensional integrity structuring. All geodesic domes are tensegrity structures, whether the Tension-islanded compression differentiations are visible to the observer or not.Tensegrity geodesic spheres do what they do because they have the properties of hydraulically or pneumatically inflated structures.”

The larger the tensegrity the stronger it is. The geodesic dome at Disney World in Florida is an example. Theoretically, there is no limitation to the size of a tensegrity. Cities could be covered with geodesic domes Planets could be contained within them.

As Harvard physician and scientist Donald Ingber explains: “The tension-bearing members in these structures – whether Fuller’s domes or Snelson’s sculptures – map out the shortest paths between adjacent members (and are therefore, by definition, arranged geodesically) Tensional forces naturally transmit themselves over the shortest distance between two points, so the members of a tensegrity structure are precisely positioned to best withstand stress. For this reason, tensegrity structures offer a maximum amount of strength“.

Life Tensegrities

Two tensegrities are easily recognizeable in systems of the human body. The muscular-skeletal system is a tensegrity of muscle and bone, the muscle provides continuous pull, the bones discontinuous push.

This forms the basis for all human physical mobility. The central nervous system can also be understood as using the analogy of tensegrity where motor neurons (discontinuously pushing our bones and joints) are in balance with sensory neurons (continuously pulling information), these forces complement each other to give us intelligent motion.

Read about the Ortegrity, a Human Organizational Tensegrity.

Read about the GIFTegrity, a Help Exchange Gifting Tensegrity.