# Are singularities shaped as a sphere.

1. Jan 4, 2012

### MartinJH

I havent read much on black holes as its not something that interests me compared to other goings on. When ever I do read/hear about them I have always pictured them as being a flat, circular plane. From what I have read they form from collaspsing stars, I understand that much. So do they remain a sphere once they get to the point in which we define them as a singularity.

2. Jan 4, 2012

### rollcast

For a non rotating black hole the singularity will be a point, basically it is an entity which has a location in space but has no dimensions of length, area or volume.

In spinning black holes the singularity can take on a ring shape in line with the plane of motion. The ring singularity is of zero thickness, ie. perpendicular to the plane of motion, but it does have a non zero radius.

3. Jan 4, 2012

### Staff: Mentor

also a black hole has an event horizon that for a non-spinning variety is a sphere. its the surface boundary where once passed light can no longer escape from the BH.

An observer outside the BH watching objects fall into the BH will see the things hover at the event horizon and never fall in whereas the falling object will observe itself continuing to fall past the event horizon and at that point no longer able to send back any signal to the observer because the radio or light signal cant escape from the BH.

4. Jan 4, 2012

### phinds

Inside the event horizon of a black hole, we really don't know WHAT is going it. The math models break down and so we call it a "singularity" but that's just a name for "no idea". It certainly seems that since the event horizon is spherical, then whatever is inside it is spherical but that's still a guess. Calling the singularity a dimensionless (but massive) point is a tautology --- both really just mean that we don't know.

5. Jan 4, 2012

### Ryan_m_b

Staff Emeritus
Black holes as defined by their event horizon's are roughly spherical. Beyond them our models don't work very well and predict an infinitely dense point known as a singularity. As far as I understand this is regarded is not being the case by most scientists and we wont really know what goes on inside a black hole until we develop better models.

6. Jan 4, 2012

### Danger

I've seen it stated (by someone reputable, as in an astrophysicist whose name I can't recall) that our universe can be thought of as a black hole in that no communication is possible with whatever universes, if any, lie beyond. If that is correct, then the answer to your question is all around you.

7. Jan 6, 2012

### MartinJH

Thank you everyone, I appretiate the responces and read them a few times.

Rollcast, your answer I feel has answered my question, and, in a way I do understand. It has not so much stunned me but given me a lot to think about. Ive never been the one for maths so its usually doing things Roger Penrose style, though with mind-drawings.

jedishrfu, phinds and Ryan; You have touched on possibly as much as I know about the subject in discussion and I knew exactly what was being said, thank you.

Also, Danger, your post has also hit a spot with me. Thinking about the universe as possibly a singularity. Thats very intriguing for me though I will take it as a pinch of salt.

Going back to Rollcasts answer briefly;
When talking about a spinning black hole what would anyone see when viewing the Black hole off-set from the plane of motion, if anything at all considering it has zero thickness. Would the presence of it only be felt.