You are delegated the task of designing a new motorway system to connect three towns that form the vertices of an equilateral triangle. Don’t worry, it’s not difficult. All you must do is connect the towns in such a way that you use the minimal length of motorway.
The world seems to be getting a smaller and smaller as transport becomes more and more efficient. Although a plane could take us to the other side of the world in under forty-eight hours, the cost is the main deterrent. As a physicist I am obliged to think of other options (however theoretical).