Probably all physical black holes have some spin because they gain it from the matter that falls into it: it's conservation of angular momentum, basically. Ther

Probably all physical black holes have some spin because they gain it from the matter that falls into it: it's conservation of angular momentum, basically. There are precise mathematical versions of rotating black holes: https://en.wikipedia.org/wiki/Kerr_metric?wprov=sfla1 https://en.wikipedia.org/wiki/Kerr_metric?wprov=sfla1