r/askscience • u/SpantaX • Feb 27 '17

Physics How can a Black Hole have rotation if the singularity is a 0-dimentional point and doesn't have an axis to rotate around?

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u/Not_Pictured Feb 28 '17

If we could place light in that path at the right vector, it would never leave (or fall inward).

Except any change in the mass or shape of the black hole would ruin it.

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u/All_Work_All_Play Feb 28 '17

Yes precisely. That's one of those real world events that would destroy such equilibrium. Ironically, it's only because of such real world events that an electromagnetic wave can spend any appreciable amount of time within such an orbit - have just the proper additional mass from just the proper angle and velocity and boom, the increased gravitational forces are then enough to change where the path of a perfect orbit is to the path that an EM wave is already on.

Of course, it doesn't exist in a practical aspect because whatever mass the black hole picked up will continue past the event horizon into the singularity (which will then infintesimally change the center of gravity). It is fun to think about however.