Originally Posted by

**azanimefan**
Its a good question. When they talk about the "mass" of a black hole that means nothing about it's size. Black holes technically don't have a "size" as you or I would understand it on an xyz graph in 3 dimensional space. This is part of the problem einstein had with them.

See general relativity, E=mc2 actually predicted the existence of Black Holes. Einstein wasn't responsible for that prediction, it was another scientist, Karl Schwarzschild, who used E=mc2 and predicted this weird event that could be mathematically proven to be possible. He didn't coin the phrase black hole, but the math certainly predicted them. He published his work and Einstein spent years trying to figure out a way to disprove it, only to come to the conclusion that these gravitational singularities were "impossible" objects which meant that his theory of general relativity was fundamentally flawed. He would for the rest of his life return to this question and try to figure out how his theory of relitivity was flawed, only to come away stumped every time. He would not live long enough to learn that actual proof of blackholes would be found and measured, and ultimately General Relativity wasn't flawed.

A Black Hole is basically the result of dividing by 0; or an object with zero VOLUME (3 dimensional measurements) and immense mass, in other words a "singularity" (gravity is a function of mass and volume, the smaller the volume and more mas an object has, the larger it's gravitational effect). In essence the black hole is so massive and the gravitational forces so infinitely powerful, that anything that falls into them, once crossing the event horizon simply stops existing in a state that could be described in normal physics, these items will be crushed down to "nothing" leaving only the concept of their mass behind, and adding to the mass of the black hole without actually leaving behind anything else.

A black hole is literally the death of everything, space, energy AND time. It wouldn't be a stretch to describe them as a rip in the very fabric of the 4 dimensional universe we observe today. When people talk about the size of a black hole what they're really talking about is the MASS, and occasionally if they're talking about it's physical size what they're talking about is the size of the event horizon. As the event horizon is an area of space with measurable boundaries, a boundary where the laws of the universe breakdown and not even light can escape from a black hole any longer; inside the event horizon matter and energy break down as they're drawn into the singularity and simply cease to exist.

FunFact: if our sun were to collapse and form a blackhole (not really possible, it's not big enough to cause that effect); it's event horizon would be only 6km across. If the earth were to collapse and form a black hole, the event horizon would be about the size of a marble.