Linked Questions

2
votes
2answers
720 views

Dipping a Dyson Ring below the event horizon [duplicate]

The basic assumption about inescapability beyond the Event Horizon is that the necessary escape speed (orbital speed) would exceed speed of light, therefore no object can achieve it. Now, would it be ...
1
vote
1answer
256 views

Could we build a spherical shell around a black hole singularity inside the event horizon? [duplicate]

Let's say we have acquired the technology to build such colossal structures. If we built a spherical shell (supposedly made of a very strong material) with a black hole right at the center, would ...
39
votes
5answers
5k views

Why is a black hole black?

In general relativity (ignoring Hawking radiation), why is a black hole black? Why nothing, not even light, can escape from inside a black hole? To make the question simpler, say, why is a ...
15
votes
2answers
4k views

Can we have a black hole without a singularity?

Assuming we have a sufficiently small and massive object such that it's escape velocity is greater than the speed of light, isn't this a black hole? It has an event horizon that light cannot escape, ...
15
votes
6answers
2k views

Why must a singularity form inside a black hole? [duplicate]

What is the exact reason that normal matter can not exist within an event horizon? I can understand how a super-dense object like a neutron star could accrete mass until its physical radius is less ...
7
votes
3answers
2k views

Event Horizon of Supermassive Black Holes

I'm going to ask/explain this as best I can; I'm sure I have some fundamentals wrong here. Spaghettification is a phenomenon which occurs only in stellar-mass black holes owing to the immense gravity ...
12
votes
1answer
2k views

A Hollow Black Hole

I was just reading a question about the gravity inside a hollow neutron star. It was a trivial question, obviously there is no force felt. But then it got me thinking. Suppose you had a hollow sphere ...
0
votes
2answers
536 views

Particles inside black hole does not hit singularity

We say that if any particles from outside fall into the black hole, they eventually hit singularity. Then why not particles already inside the black hole are at singularity? Or are they? If yes, then ...
3
votes
1answer
193 views

How do we know black hole is empty (except singularity)?

As no information is allowed from inside event horizon, how did we figure out that all matter/energy in a black hole is concentrated at a point like singularity. Say for example how it was ruled out ...
2
votes
1answer
177 views

Thought experiment: ultra-fast outward push inside a black hole

Suppose I have a classical schwarzchild Black hole $B$ of mass $M$. And consider a spherical-subset (or sub-black-hole if you will) $B'$ (sharing the same singularity and having mass $M'$ (We will ...
2
votes
3answers
157 views

Self-collisions in curved space

I know perfectly rigid objects are physically impossible, but let me describe a simple thought experiment that I can't theoretically solve. Imagine you have an almost-closed ring-shaped perfectly ...