ZQ25

What Forces are at Work Here? Tom McKeag

and developed his system of geodesics, or minimal pathways to constrain movement; the fundamentals of turning a mechanism (parts that move) into a stable structure (parts that do not). This concept is quickly demonstrated at any scale of “stick” building: a square of joined sticks is not stable and “racks” (revealing it as a mechanism) until an additional diagonal cross piece is added, thus creating two stable triangles (now stabilized into a structure). Fuller developed his most formal definition of tensegrity in his book Synergetics. “Tensegrity describes a structural-relationship principle in which structural shape is guaranteed by the finitely closed, comprehensively continuous, tensional behaviors of the system and not by the discontinuous and exclusively local compressional member behaviors” (2). The human body structure has often been held as a tensegrity model, with bones comprising the rigid struts, and muscle and sinew the tensioning cables. Fuller’s geodesic domes and tetrahedral space frames are also examples ("Bucky, geodesics, and biomimicry" by Jay Baldwin: https://issuu.com/eggermont/docs/ zq_issue_02r_final/36). It was at the cellular scale, however, that this concept was most intriguing to Ingber.

Page 14 of 118

The “Aha!” Moment In 1975 Donald Ingber was a 19-year old molecular biophysics and biochemistry student at Yale with an interest in art. One day in sculpture class, he and his classmates were given sets of wooden dowels and fishing line and told to make some objects according to a simple rule: none of the stiff dowels within their sculptures could touch each other. One of the students knew of the work of Kenneth Snelson and Buckminster Fuller and clued his fellows into how they could make a wide variety of tensegrity models. Ingber had just been working in the lab culturing cancer cells and in the course of his work had observed how easily the cells changed shape from flat to round depending on their surroundings while still maintaining their overall integrity. He remarked on this to his supervisor and told him they were exhibiting tensegrity. After explaining the source of his insight he was told never to mention it again. Undeterred, Ingber went on to write his thesis on the topic. For this thesis he built many models to test and illustrate his ideas. The Prevailing Paradigm A quick review of the human cell is in order here, with first a reminder that not all cells