“An alternative approach would be to make collapse occur whenever the system reached a certain threshold, like a rubber band breaking when it is stretched too far. A well-known example of an attempt along these lines was put forward by mathematical physicist Roger Penrose, best known for his work in general relativity. Penrose’s theory uses gravity in a crucial way. He suggests that wave functions spontaneously collapse when they begin to describe macroscopic superpositions in which different components have appreciably different gravitational fields.”