Can a Naked Singularity Become a Black Hole?

[Endervhar]

From what I can discover it seems that a naked singularity is a singularity without an event horizon.

It also seems that this may be a black hole in the making, as it is a product of continued gravitational collapse.

This seems to raise three questions:

1. If a singularity is a point at which spacetime is infinitely curved, how can the curvature increase?

2. If the curvature at the singularity cannot further increase, why is it not a black hole already.

3. If the curvature is not infinite, how can it be described as a singularity.

 

[LostConjugate]

I never heard of a naked black hole, so I looked it up. But I don't see anything about what your describing. Just that it is a theoretical black hole that has such a high angular momentum that the event horizon becomes a ring of two event horizons that cancel each other out.

There is some mathematical proof of the possibility if a black hole was in a perfect vacuum with very high angular momentum.

It is still a singularity though.

 

[Endervhar]

Since my O P, I have found de Felice’s paper (www.arxiv.org/abs/0710.0983). I need an explanation with less maths, please.

 

[LostConjugate]

As the black hole gains more and more angular momentum the shape of the event horizon becomes like a doughnut. As even more angular momentum is added the top and bottom of the doughnut get closer and closer together. With the top being a mirror of the bottom, if they were pressed together the event horizon would cease to exist.

 

[Endervhar]

Thanks, LostConjugate.

My understanding of an event horizon is that it is a spherical projection of the point at which the gravitational attraction of a very dense body becomes so strong that nothing can escape.
A singularity would be such an entity, yet here we have a singularity without an event horizon.
Does this mean that light, for example, can escape no matter how close to the singularity it approaches?

 

[LostConjugate]

Thanks, LostConjugate.

My understanding of an event horizon is that it is a spherical projection of the point at which the gravitational attraction of a very dense body becomes so strong that nothing can escape.
A singularity would be such an entity, yet here we have a singularity without an event horizon.
Does this mean that light, for example, can escape no matter how close to the singularity it approaches?

Exactly. That is why it is an important theoretical concept to physicists.

 

[Endervhar]

So if a naked singularity is found, it will be visible?

I won't ask how the light escapes, I guess I would need a lot of maths to have any chance of understanding that.

 

[LostConjugate]

It still seems illogical that light could interact with it and return. It does show that light can escape from anywhere around it, but what exactly happens when you try to interact with the singularity is still unknown.

I would expect that if it were even large enough to interact with light, the light it interacts with would never return.

What is interesting is that it would allow a singularity to exist within close proximity without destroying everything around it. Inside of a space ship, or power plant for example.

 

[Endervhar]

if it were even large enough to interact with light,

Is there an expectation that a naked singularity would be a small one, or were you just considering the lower end of a potentially wide range of sizes?

 

[Drakkith]

How does the angular momentum of a black hole effect its event horizon?

 

[Nabeshin]

My understanding of an event horizon is that it is a spherical projection of the point at which the gravitational attraction of a very dense body becomes so strong that nothing can escape.

Slight clarification here: the event horizon need not be spherical. Indeed, for a rotating black hole it is an ellipsoid. In more complex configurations, such as the situation which arises when two black holes are merging, the event horizon can have a much more complex geometry.

Also, asking the question of "how can we interact with the singularity?" is quite meaningless. By definition, the singularity is the point at which the equations of general relativity don't make sense any more. So what theory shall we use to describe how these objects interact with the environment? Any theory which predicts the singularity can simultaneously say nothing about how it interacts, since the theory by definition makes no sense at the singularity! So only a theory with no singularity (i.e. some type of quantum gravity which halts collapse at ~ Planck density) could describe the interactions in this kind of situation, but then it is not really a singularity!

 

[Endervhar]

but then it is not really a singularity

This has to raise the possibly naive question: is a singularity a physical possibility?

 

[Nabeshin]

This has to raise the possibly naive question: is a singularity a physical possibility?

Indeed. Most physicists would probably answer in the negative. A physical object where spacetime curvature becomes infinite is simply too outlandish for the community at large to accept.

 

[Endervhar]

A physical object where spacetime curvature becomes infinite is simply too outlandish for the community at large to accept.

Well, that's a relief. Thanks.

 

[LostConjugate]

How does the angular momentum of a black hole effect its event horizon?

It causes it to become a ring shape based on the Kerr Metric I guess.