Podcast 16 was recorded while walking through the bush. I explain the new direction I'm taking with Darwin at Home: exploring tensegrity structure. Tensegrity is a beautiful kind of structure made of pushes and pulls with the special restriction that the pushes do not touch each other but rather are suspended in a network of tension. Here's an image of one:

A long time ago I was inspired by a piece of art in a sculputure garden in the east of Holland called the Needle Tower which was a creation of the artist Kenneth Snelson.

Ken Snelson has his own website with a page about Structure & Tensegrity. Early on he worked with Buckminster Fuller, who eventually came up with the word and developed a bunch of ideas around it.

Building tensegrities is difficult physically, and also difficult virtually. Originally we would build scaffolding, place the tensegrity intervals, and then remove the scaffolding, because tensegrity structures only have their shape when they are finished and the tension network is complete.

The big challenge will be to discover the general organizing principles behind tensegrity and to use them to evolve tensegrities. I've rewritten the physics code so that there are only rigid elements and pulling elements, which means that tensegrity is the only possible structure.

This new direction requires that the software detect when there are collisions between intervals, which is something I've never had to do before. I've introduced the "Cross" class which holds a relationship between two intervals and pays attention to whether they are colliding.

When a Cross detects that two intervals have collided or passed through each other, the intervals will "lose points" or be "damaged". This way it should be possible to have a population of structures which violate the collision restriction, but some violate less frequently than others.

The ultimate dream would be to actually be able to build the evolved tensegrities in reality. The fitness function will probably now no longer involve walking, but instead something like structure height.