<p>What I understood about it till now is that space-time fabric is kind of broken there. Please tell me whether I am correct.</p>

<ul>
<li><p>If it's true then does it mean that perception of time will stop there?</p></li>
<li><p>I really can't get what broken space fabric is like. If it's a hole then how is matter supposed to be present inside that?</p></li>
<li><p>Is a black hole a discontinuity?</p></li>
</ul>

CC BY-SA 4.0
2019-04-05T19:14:43.053Z
As [Ben Crowell says](https://physics.stackexchange.com/a/144458/123208) on the Physics site: "A singularity in GR is like a piece that has been cut out of the manifold. It's not a point or point-set at all".
PM 2Ring
CC BY-SA 4.0
2019-04-05T19:20:22.837Z
So can we say its equivalent to a blank space?
TheVariant
CC BY-SA 4.0
2019-04-05T19:43:55.563Z
It's worse than that. To keep things simple, imagine that we only have 2 dimensions, 1 of time & 1 of space, so we can draw a map on paper of the spacetime containing a black hole. Where the singularity is, it's not merely blank paper, there's actually a hole in the paper.
PM 2Ring
CC BY-SA 4.0
2019-04-05T19:45:28.007Z
The function $\frac{1}{x^2}$ is continuous in all the points of the curve. But $x=0$ is not on the curve.
peterh
CC BY-SA 4.0
2019-04-05T23:12:19.060Z
@peterh excellent example! Correct if just looking at points on the *two* curves, but the function is actually *discontinuous* over the domain $\mathbb {R}$, which of course is the point you're illustrating.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-04-06T07:21:36.423Z
If your real question is "What's the core of a black hole *really* like?", we can't give you a proper answer until we have a theory that properly connects quantum mechanics and general relativity, aka a quantum gravity theory. In the mean time, the consensus is that quantum effects will prohibit the mathematical singularities of GR.
PM 2Ring
CC BY-SA 4.0
2019-04-06T07:24:27.570Z
I am just trying to get what are the characteristics of discontinuity in space .Like how time and space dimension behave there.
TheVariant
CC BY-SA 4.0
2019-04-06T10:33:36.257Z
Ok. Then Ben's answer on Physics I linked earlier covers that. And as mistertribs's answer here mentions, even if such discontinuities are physically possible, we can't ever observe them because they're hidden behind an event horizon. And once you're inside the event horizon, you can't see the singularity: nothing (including light) leaves the singularity, and it's never in the past of any observer. Normal matter certainly can't exist at the core of a black hole, whether or not there's an actual singularity there.
PM 2Ring
<black-hole><space-time>
Discontinuity in space-time
TheVariant
# Discontinuity in space-time

(Asked by: username_0 on 2019-04-05)

What I understood about it till now is that space-time fabric is kind of broken there. Please tell me whether I am correct.

* If it's true then does it mean that perception of time will stop there?
* I really can't get what broken space fabric is like. If it's a hole then how is matter supposed to be present inside that?
* Is a black hole a discontinuity?

**Tags:** black-hole, space-time

> **Comments:**
> **username_1**: As [Ben Crowell says](https://physics.stackexchange.com/a/144458/123208) on the Physics site: "A singularity in GR is like a piece that has been cut out of the manifold. It's not a point or point-set at all".  
> **username_0**: So can we say its equivalent to a blank space?  
> **username_1**: It's worse than that. To keep things simple, imagine that we only have 2 dimensions, 1 of time & 1 of space, so we can draw a map on paper of the spacetime containing a black hole. Where the singularity is, it's not merely blank paper, there's actually a hole in the paper.  
> **username_2**: The function $\frac{1}{x^2}$ is continuous in all the points of the curve. But $x=0$ is not on the curve.  
> **username_3**: @username_2 excellent example! Correct if just looking at points on the *two* curves, but the function is actually *discontinuous* over the domain $\mathbb {R}$, which of course is the point you're illustrating.  
> **username_1**: If your real question is "What's the core of a black hole *really* like?", we can't give you a proper answer until we have a theory that properly connects quantum mechanics and general relativity, aka a quantum gravity theory. In the mean time, the consensus is that quantum effects will prohibit the mathematical singularities of GR.  
> **username_0**: I am just trying to get what are the characteristics of discontinuity in space .Like how time and space dimension behave there.  
> **username_1**: Ok. Then Ben's answer on Physics I linked earlier covers that. And as mistertribs's answer here mentions, even if such discontinuities are physically possible, we can't ever observe them because they're hidden behind an event horizon. And once you're inside the event horizon, you can't see the singularity: nothing (including light) leaves the singularity, and it's never in the past of any observer. Normal matter certainly can't exist at the core of a black hole, whether or not there's an actual singularity there.  

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## 0 answers

