# Where does stuff “sucked” up by a black hole go? [duplicate]

I've heard that stuff sucked up by a black hole leads to a parallel universe, but I don't believe that because when a black whole "sucks" something up, the thing it "sucked" up adds to the black holes mass, how would it do this if everything it sucked up was ejected out a white hole on the other side of the universe? I want to know where stuff really goes after being "sucked" up by a black hole. According to Wikipedia,

The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.

This is why dying stars form black holes. This means a black hole must be a very compact sum of mass in a small area, or a singularity. Because of this, I think when something gets sucked up by a black hole, it just gets crushed up to a very small volume and adds to the singularity. Am I wright or not?

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• Possible duplicate of What happens to light and mass in the center of a black hole? – JMac Apr 9 '18 at 16:11
• Black holes do not suck stuff up. A black hole has gravity, just like a star has gravity or a planet has gravity, and things that come near the black hole are influenced by that gravity in exactly the same way that things are influenced by the gravity of a planet or a star. If our Sun was magically crushed to the point of becoming a black hole, the Earth and all of the other planets would continue to orbit it, exactly as they do now. Only difference would be that the Solar system would become a dark and cold place. – Solomon Slow Apr 9 '18 at 17:05
• It's really only massive stars that could form black holes (cf this post) – Kyle Kanos Apr 9 '18 at 17:08
• I know they don't really suck, I just had no better way to describe it. – Daniel Turczynskyj Apr 9 '18 at 18:59

The same place where something "sucked up" by a planet goes.

A black whole is not a "hole" in the sense that it goes somewhere, or that something can "go in it". A black hole is simply a celestial body which is characterized by an escape velocity greater than the speed of light. The escape velocity grows smaller depending on how far you are from the center of mass, and at the point where it is no longer greater than the speed of light, the event horizon ends.

Thus, when something is sucked into a black whole, it eventually reaches the "surface" (although words like that may very well be meaningless in an environment as strange as a black whole) and becomes part of the black whole.

• So, does that mean there is a single point inside the black hole that is so dense, even light can't escape the event horizon. – Daniel Turczynskyj Apr 9 '18 at 19:01
• @DanielTurczynskyj It doesn't necessarily have to be a single point. Keep in mind that the equation for escape velocity is the square root of 2GM/R (2 times the gravitational constant times the mass of the planet, divided by the radius). This means that it isn't a single point per se where it is very dense, but rather an entire region which is very massive. – DevilApple227 Apr 9 '18 at 23:40

The Schwarzschild solution of the EFE (Einstein field equations) describes a spacetime in vacuum surrounding a spherically symmetric and static mass. In particular if the mass is contained in the Schwarzschild radius, it envisages a black hole, that is a mass that defines a surface, the event horizon, which captures any material body or light entering it. Working out the Schwarzschild metric with different coordinates it is demonstrated that matter or light crossing the event horizon can only proceed in direction of the singularity at the center of the black hole. Classically, all the mass is concentrated at the center of the black hole.
The theoretical possibility of a black hole as an interface to another universe comes from the so called maximally extended solution, which does not constrain the coordinates.

Where does stuff sucked up by a black hole go?

Into the black hole, increasing its mass.

I've heard that stuff sucked up by a black hole leads to a parallel universe, but I don't believe that.

You're right not to believe it.

I want to know where stuff goes after being sucked up by a black hole. According to Wikipedia, "The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole".

It's not all that different to a planet. The important thing is that at the event horizon the "coordinate" speed of light is zero, so light can't get out. So it's black. It isn't really a hole.

This is why dying stars forms black holes. This means a black hole must be a very compact sum of mass that has a lot of gravity. Because of this, I think when something gets sucked up by a black hole, it just gets crushed up with all the other mass and adds to it.

Pretty much. There are some interesting issues about "the state of matter" that comprises a black hole, and whether you can even call it matter. But the stuff that fell in adds to the mass of the black hole, which has a bigger gravitational field as a result.

The only reason you can't see the center where all this mass is because no light is reflected off it because the black hole's gravity is too great.

Yep, I'd say that's pretty much it.