Is a black hole a giant cosmic vacuum cleaner?
The answer to this question is “not really.” The gravity around a black hole remains normal unless you get extremely close. If the Sun suddenly became a black hole (which isn’t actually possible), the Earth and all the other planets would continue to orbit it just as though nothing had changed. The behavior of gravity doesn’t change until an object approaches to the point where it’s within a few times the radius of the event horizon, the boundary marking the region around a black hole from which not even light can escape. At that point, objects begin to lose the ability to maintain stable orbits, and inevitably spiral into the black hole. So to return to our theoretical example, if the Sun became a black hole, objects would have to be as close as about 6.2 miles (10 km) to the black hole’s center before they began spiraling in.
The answer to this question is “not really.” To understand this, first consider why the force of gravity is so strong close to a black hole. The gravity of a black hole is not special. It does not attract matter at large distances differently than any other object does. At a long distance from the black hole the force of gravity falls off as the inverse square of the distance, just as it does for normal objects. Mathematically, the gravity of any spherical object behaves as if all the mass were concentrated at one central point. Since most ordinary objects have surfaces, you will feel the strongest gravity of an object when you are on its surface. This is as close to its total mass as you can get. If you penetrated a spherical object with a constant mass density, getting closer to its core, you would feel the force of gravity get weaker, not stronger. The force of gravity you feel depends on the mass that is interior to you, because the gravity from the mass behind you is exactly cance
