Do Black Holes Have Walls? Exploring the Unknown

[Gondur]

I was asked this question... Honestly I do not know!
Imagine a black hole.
You get sucked inside the singularity
Yes, you'd die instantly, but suppose you lived.
Where would you end up in space & time if, when inside the singularity, you float to a wall containing it and pierced it and traveled through it? (not considering the 'hole' through which you entered)?
I assume singularities must be bounded by walls else how would they retain their structure?

 

[Dale]

Black holes do not have walls. The singularity is more like a moment in time rather than a structure in space.

 

[mark!]

I don’t want to ruin your weekend or anything, but there's no you anymore inside a black hole. All of the atoms in your body will be reduced to a bunch of charged particles, which then get pulled towards the black hole. The black hole gets bigger, because the event horizon radius (not a wall!) is proportional to the mass of the black hole (the surface area of a black hole always increases or at best remains the same, but never decreases). If you’re lucky, a loud scream might produce a virtual particle, which doesn't get absorbed by the event horizon (through black hole evaporation) and possibly annihilates with another (anti-)particle to produce two photons. That’s the most that you could achieve from this experiment.

So if you think that's worth it, be my guest, but if you ask me, I wouldn't try it.

 

[Drakkith]

You get sucked inside the singularity
Yes, you'd die instantly, but suppose you lived.

Careful. Whatever happens at the singularity is unknown since the math governing spacetime is undefined there, meaning that we can't predict what will happen at all. We can't even "suppose" that something happens. Any answer would be pure speculation and exceedingly unlikely to be accurate.

Where would you end up in space & time if, when inside the singularity, you float to a wall containing it and pierced it and traveled through it? (not considering the 'hole' through which you entered)?

A black hole is not a box with walls. It is a region of spacetime that, once you enter it, your future world-line (your path through spacetime) always leads towards the singularity. After entering a black hole, you could fire your rocket engines and travel in all directions without ever hitting a wall, a boundary, or anything like that. Even pointing backwards, towards what you think is the way you came, would still lead you towards the singularity.

The entire idea of a singularity in the context of general relativity is that a singularity is a location in spacetime where things become unpredictable. Per wiki: More generally, a spacetime is considered singular if it is geodesically incomplete, meaning that there are freely-falling particles whose motion cannot be determined beyond a finite time, being after the point of reaching the singularity.

I don’t want to ruin your weekend or anything, but there's no you anymore inside a black hole. All of the atoms in your body will be reduced to a bunch of charged particles, which then get pulled towards the black hole.

You can certainly fall into a supermassive black hole and pass its event horizon well before you would get ripped apart by tidal forces. Tidal forces increase as the mass decreases, so stellar mass black holes would rip you apart further from their event horizons than intermediate and supermassive black holes would (however, you're further away from the singularity in the latter two cases).

 

[Nugatory]

I don’t want to ruin your weekend or anything, but there's no you anymore inside a black hole...

It depends on the size of the black hole. If it is large enough (or you are small enough - a bacterium will be unaffected by tidal forces that would tear a two-meter-tall human being apart), the tidal forces at the event horizon will be small enough that you could free-fall through the horizon and end up inside without even noticing.

 

[mark!]

It depends on the size of the black hole. If it is large enough (or you are small enough - a bacterium will be unaffected by tidal forces that would tear a two-meter-tall human being apart), the tidal forces at the event horizon will be small enough that you could free-fall through the horizon and end up inside without even noticing.

Yes, it depends on the size of the black hole. This is also true for black hole evaporation in general, it happens more easy in small black holes rather than (super)massive black holes.