# Sizes of black holes

1. Dec 12, 2012

### goldsax

If a black hole is a stellar structure that has collapsed on itself to a singularity does that mean it has no size? But is so defined by its mass and schwarzschild radius?
Cheers

2. Dec 12, 2012

### Drakkith

Staff Emeritus
The black hole has a size defined by the event horizon. The actual volume and such is a bit more complicated to determine due to spacetime curvature I believe. A singularity, IF it exists at all, would have no size.

3. Dec 12, 2012

### mathman

Current physical theory is unable to accurately describe what is going on inside the event horizon of a black hole. Quantum theory and general relativity don't mesh, and they both come into play.

4. Jan 3, 2013

### galleon

The thing to realise is that the term 'black hole' doesn't mean: 'the bit at the center where all of the mass is concentrated, that may or may not be a singularity'.

'black hole' refers to the whole volume inside the event horizon, which clearly can have a radius, surface area and volume.

my understanding is that non-rotating black holes are perfect spheres with a radii equal to their Schwarzchild radius, and that rotating black holes are distorted into oblate spheroids, as are most rotating stellar objects.

5. Jan 4, 2013

### snorkack

A Schwarzschild blackhole singularity is a mathematical point, yes, and so is a NordstrÃ¶m black hole singularity. But Kerr and Newman black hole singularities are one dimensional - they have no thickness, but they have circumference, radius etc.

6. Jan 6, 2013

### BH Wiz

How can it be one dimensional with a circumference and a radius? does that make it 2 dimensional?