The idea that angular momentum and energy may be transferred from a rotating black hole to a particle being scattered by it was proposed by Roger Penrose in 1971. The first discussion of a runaway effect, the black hole bomb, was explored by W. H. Press and S. A. Teukolsky in 1972. If such an effect were to spontaneously occur, it may point to new physics beyond the Standard Model, and showing that black holes have "hair", as pointed out by a paper from 2017, by William E. East and Frans Pretorius.