A few weeks ago a friend told me about the remarkable method Antoni Gaudi used for designing arch based structures. He built inverted string models and attached small weights to simulate the loads to be placed on the arch. It is a charming symmetry of physics that a hanging string chooses the same, but inverted, shape that an arch needs in order to distribute stress uniformly. By simply turning the model upside down Gaudi had a perfect scale model of his arch.

One of Gaudi's arch models
One of Gaudi’s arch models

Gaudi’s most famous work is probably the Sagrada Familia basilica in Barcelona.

The Sagrada Familia basilica in Barcelona
The Sagrada Familia basilica in Barcelona

A string secured at both ends assumes a shape called a catenary, the string supports its weight and the weight of its loads by bending until the tension along its length is the same everywhere. Strings just know how to do this. Imagine a string hanging from two points, if you nudge the lowest point to the left the right-hand side gets more tension dragging the string back when you let go. Think of the mathematical effort a computer goes through to evaluate the stresses on a component. The string just does it. It reminds me of Einstein’s quote

“God does not care about our mathematical difficulties. He integrates empirically”

I find this approach to engineering intriguing, I wonder if it has any application in the fusion world?