What is Singularity?

[mdmaaz]

Main Question or Discussion Point

I have read that inside a blackhole there is a point called "singularity", where all the laws of physics break down. But exactly what does that mean?

 

[tiny-tim]

hi mdmaaz!

it means that the laws of physics as we know them break down …

once we've managed to unite relativity and quantum theory, our laws of physics will be different, and we may be able to apply them to the singularity

(alternatively, maybe our black hole equation will turn out to be wrong, and the singularity isn't exactly what we think it is)

 

[Nabeshin]

To expand on what tiny-tim said, we say a singularity occurs when our laws of physics are no longer well defined. For example, in Newtonian physics, the gravitational force is expressed as:
$$F\sim\frac{1}{r^2}$$
When r=0, this equation is undefined (since division by zero is not defined), or we say that it is singular. I.e. there is a singularity at r=0. This is analogous to what happens with a black hole.