Extreme black holes have hair that can be combed

Black holes depend on only three parameters (mass, angular momentum, and charge), a uniqueness property known as the “no-hair” theorem. In a Letter published in the Physical Review D, researchers announce finding an exception: a class of black holes, known as extreme black holes, that has classical hair in the vaccuum Einstein theory. The newly discovered hair depends on how the black hole formed, thus violating the uniqueness, or “no hair” theorem.