A spinning black hole will generally have the geometry of an oblate spheroid, much like the Earth. It is not possible for a black hole to spin so fast it would tear itself apart. But there is a limit that you reach where it's the fastest a black hole can spin. And this is what is called an extremal black hole.
Welcome to the October 2022 Ask Me Anything episode of Mindscape! These monthly excursions are funded by Patreon supporters (who are also the ones asking the questions). We take questions asked by Patreons, whittle them down to a more manageable number — based primarily on whether I have anything interesting to say about them, not whether the questions themselves are good — and sometimes group them together if they are about a similar topic. Enjoy!
Support Mindscape on Patreon.
See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.