Most newborn black holes spew gas so hard they almost stop spinning

Most black holes may spin far more slowly than expected. When black holes form from collapsing stars, they emit powerful jets of energy, and these jets slow down the black holes’ spin to nearly nothing within minutes.

The spin of a newborn black hole is governed by two competing phenomena. When fast-moving material in its orbit falls in, the black hole takes in energy and its rotation speeds up. But that same consumption causes a huge jet to blast away…