20

I hope this question isn't too naive, but would it theoretically be possible to have a black hole with 2 singularities (or 2 black holes at the same location). If this is possible, would there be any significant differences on the effects of space time?

What I am thinking of is if you were to have a spinning black hole that has a ring as your first singularity and in the center of that ring was yet another singularity (with no angular momentum). Would it be theoretically possible for this structure to exist or would the inner black hole just begin to spin the same direction gaining some the momentum?

Similarly, what if you have two spinning black holes with perpendicular ring singularities at the same location? (And if you wanted to be really crazy, add another singularity into the middle of that)

If there is something I am missing or misinterpreting about black holes or singularities, please feel free to let me know as I am no expert.

John Rennie
  • 367,598
Mark N
  • 451

3 Answers3

19

There are only four known stable black hole geometries: Schwarzschild, Reissner-Nordstrom, Kerr and Kerr-Newman. We expect that any random assemblage of matter dense enough to form a black hole will relax into one of these four geometries by emission of gravitational waves. None of these geometries has two distinct singularities, so (as far as we know) it is impossible to have a black hole with two distinct singularities.

You suggest possible arrangements of matter in your question, and as Jerry says in his answer these could occur as transient states in a black hole collision. However in time (actually very quickly :-) they will relax into one of the four known geometries with just a single singularity.

John Rennie
  • 367,598
14

I think the closest model to what you're talking about would be two colliding black holes, during the intermediate period where their horizons had merged, but the central objects had not yet collided. These systems are very different from isolated black holes, as they give off significant gravitational radiation, and have horizons that rapidly change in shape as they give off this radiation.

Zo the Relativist
  • 42,237
0

Quite apart from whether a point singularity can exist inside a ring singularity there's the little detail that a solid ring (and a ring singularity will behave as one) in orbit about a central body is unstable. If one point is infinitesimally closer to the center (and it will--quantum uncertainty) there will be more attraction there and the difference will be magnified. Given the forces involved the ring and the point will very quickly collide and you'll be left with one singularity.

Your other configurations fare no better in the stability department.

Loren Pechtel
  • 1,739