Proceedings of the International Conference on Intelligent Systems and Semiotics (ISAS'97), National Institute of Standards and Technology Publ., Gaithersburg, MD, 1997, pp. 378-382.
Celestial bodies such as galaxies, stellar clusters, planetary systems, etc., have different geometric shapes (e.g., galaxies can be spiral or circular, etc.). Usually, complicated physical theories are used to explain these shapes; for example, several dozen different theories explain why many galaxies are of spiral shape. Some rare shapes are still difficult to explain.
It turns out that to explain these "astroshapes", we do not need to know the details of physical equations: practically all the shapes of celestial bodies can be explained by simple geometric invariance properties. This fact explains, e.g., why so many different physical theories lead to the same spiral galaxy shapes.
This same physical idea is used to solve a different problem: the optimal sensor placement for non-destructive testing of aerospace systems.