<p><span class="math-container">$$
    K_\text{min}=2\pi\sqrt{a^2+3(ma^2)^{2/3}}
\tag{1}
$$</span></p>
<p>where the quantities <span class="math-container">$m$</span> and <span class="math-container">$a$</span>, both of which have units of length, are defined by
<span class="math-container">$$
    m=\frac{GM}{c^2}
\hskip2cm
    a=\frac{J}{Mc}.
\tag{2}
$$</span></p>
<p>The maximum spin is a=m (an extremal Kerr black hole), the borderline case between a black hole and a naked singularity.</p>
<p>More details from Chiral Anomaly here:
<a href="https://physics.stackexchange.com/a/469282/">https://physics.stackexchange.com/a/469282/</a></p>

CC BY-SA 4.0
2020-07-14T04:39:16.337Z
Ok i am not really a math guy can you tell me if the ringularity can be spinning faster than c?
Helena Wells
CC BY-SA 4.0
2020-07-14T10:27:41.410Z
@Helena As Chiral Anomaly says, "The geometry inside a Kerr black hole is pretty crazy". In GR, you can apply SR in a sufficiently small region of spacetime, where "sufficiently small" means that the effects of curvature in that region are small enough to be negligible. But the effects of curvature are *never* negligible if the region contains a singularity. So trying to apply the geometric notions of SR to the ringularity itself doesn't work.
PM 2Ring
CC BY-SA 4.0
2020-07-14T13:29:29.420Z
This isn't really a helpful answer. I don't see velocity mentioned and $K_{\rm min}$ is undefined.
ProfRob
CC BY-SA 4.0
2020-07-14T17:52:17.217Z
@user253751 if special relativity breaks down near the ringularity then it could be anything.
Helena Wells
CC BY-SA 4.0
2020-07-14T04:36:14.793Z
2020-07-14T10:15:05.230Z
2020-07-14T10:15:05.230Z
gisol
<p>How fast is a ringularity<sup>1</sup> spinning? Spinning black holes are created from spinning stars.</p>
<p>The angular momentum of the 'parent' star must be conserved so spinning black holes are spinning much much faster than their 'parent' star.</p>
<p>Since black holes have generally less mass than their parent star and mass is found only in a tiny amount of space then the ringularity should be spinning incredibly fast.</p>
<p>The ringularity is a ring which contains all the mass of the black hole and it is in the center and it is almost infinitely tiny so it must be spinning almost infinitely fast.</p>
<p>Can it spin faster than c? Is there any way to know if SR can be violated inside such extremely dense objects?</p>
<p><sup>1</sup><a href="https://en.wikipedia.org/wiki/Ring_singularity" rel="nofollow noreferrer">Ring singularity</a></p>

CC BY-SA 4.0
2020-07-14T17:47:55.857Z
I don't say it is but could it possible it is violated near the ringularities?
Helena Wells
<black-hole><singularity>
Velocity of ringularity
Helena Wells
# Velocity of ringularity

(Asked by: username_0 on 2020-07-14)

How fast is a ringularity1 spinning? Spinning black holes are created from spinning stars.

The angular momentum of the 'parent' star must be conserved so spinning black holes are spinning much much faster than their 'parent' star.

Since black holes have generally less mass than their parent star and mass is found only in a tiny amount of space then the ringularity should be spinning incredibly fast.

The ringularity is a ring which contains all the mass of the black hole and it is in the center and it is almost infinitely tiny so it must be spinning almost infinitely fast.

Can it spin faster than c? Is there any way to know if SR can be violated inside such extremely dense objects?

1[Ring singularity](https://en.wikipedia.org/wiki/Ring_singularity)

**Tags:** black-hole, singularity
> **Comments:**
> **username_0**: I don't say it is but could it possible it is violated near the ringularities?  

---

## 1 answers

### Answer by username_1 on 2020-07-14. Score: 1

$$
K\_\text{min}=2\pi\sqrt{a^2+3(ma^2)^{2/3}}
\tag{1}
$$

where the quantities $m$ and $a$, both of which have units of length, are defined by
$$
m=\frac{GM}{c^2}
\hskip2cm
a=\frac{J}{Mc}.
\tag{2}
$$

The maximum spin is a=m (an extremal Kerr black hole), the borderline case between a black hole and a naked singularity.

More details from Chiral Anomaly here:
<https://physics.stackexchange.com/a/469282/>

> **Comments:**
> **username_0**: Ok i am not really a math guy can you tell me if the ringularity can be spinning faster than c?  
> **username_2**: @Helena As Chiral Anomaly says, "The geometry inside a Kerr black hole is pretty crazy". In GR, you can apply SR in a sufficiently small region of spacetime, where "sufficiently small" means that the effects of curvature in that region are small enough to be negligible. But the effects of curvature are *never* negligible if the region contains a singularity. So trying to apply the geometric notions of SR to the ringularity itself doesn't work.  
> **username_3**: This isn't really a helpful answer. I don't see velocity mentioned and $K_{\rm min}$ is undefined.  
> **username_0**: @user253751 if special relativity breaks down near the ringularity then it could be anything.  

---

