Why do black holes have so much mass?

Answer 1

It doesn't necessarily.

Remember that the gravitational acceleration of a lump of mass, and the force

on things near it, depends on the distance from the center of it.

The Earth has a lot of mass, but you can't get any closer to the center of it

than about 4,000 miles.

The thing about a black hole is that its mass is packed into such a small space

that you can get very close to it. It has colossally huge gravity when you get

colossally close to it.

-- Let's say you weigh 100 pounds on Earth.

-- Let's say there's a black hole that has the same mass as the Earth,

but it's the size of a Basketball.

-- Let's say you walk over to it, until you're 100 feet away from it.

100 feet away from 1 Earth mass, you weigh almost 22 million tons.

It's getting hard to walk, you're starting to sweat, and you look at it

and you say to yourself "Geez, that thing sure has strong gravity!"

Answer 2

Black holes have a lot of mass because they result from the gravitational collapse of massive stars at the end of their life cycle. When a star's core runs out of fuel, it can no longer support itself against the force of gravity, causing it to collapse in on itself and form a black hole.

Answer 3

They are so dense because they have a giant star (roughly 50X the mass of our sun) compressed so far that light can't even escape. To put this in perspective, think of how big our sun is, then, Scale it up to a size in which 500 suns can fit into it, now compress that to the size , roughly, of the moon. That's why.

Answer 4

General relativity says that mass distorts space and time and the more mass, the greater the distortion of space.

A black hole is formed when a mass causes space and time to distort so much that nothing that enters the black hole can ever get out.

It takes a lot of mass, much more than the mass of our sun, to make a black hole.

We can detect black holes because we can observe the effect of the distortion of space around the black hole.

Their "size" of a black hole the region of space called the event horizon. If anything, light or matter, enter the even horizon, then it never comes out. In effect, the size of the back hole is the region of space insize that can't be seen.

Answer 5

The black holes we know of have large amounts of mass because of the method of their formation, which relates to processes of their stellar evolution (or accretion in the case of a galactic core supermassive black hole). A star massive enough to gravitationally collapse into a black hole under its own weight would have had to possess sufficient mass to do so; but the important thing to realize is that black holes can be of any mass; to qualify as a black hole, an object simply needs to have sufficient density that its radius is smaller than its Schwarzschild radius - and the mechanism for creation of a black hole is usually through the effects of a large mass.

For a small mass the Schwarzschild radius is extremely tiny - the Earth's is about 10 millimeters, around the size of a marble. The Schwarzschild radius of the sun is roughly 3 km. Potentially a black hole could be microscopic; but since mechanisms to compress small masses into a sufficiently tiny volume are uncommon, it follows that the black holes we know of happen to be massive.

It's commonly believed that conditions in the early universe just after its creation would have had regions of sufficient density to form black holes - such are called primordial black holes for this reason. It's also possible the particle collisions of sufficient energies could create black holes; such might be created artificially in a particle accelerator, or might be generated naturally as highly energetic cosmic rays collide with particles in our atmosphere.

Another consideration is the life-span of smaller black holes; it's widely accepted that black holes interact thermodynamically with the universe - quantum effects near the event horizon of a black hole cause them to radiate away small amounts of energy, and thus carry mass away from the black hole, an effect often referred to as black hole evaporation. This effect increases with decreasing size, such that the smallest black holes are expected to evaporate the most quickly and, without infalling matter to make up for the lost mass from the effect, would end their lives and disappear with an energetic explosion. Hence, statistics favor that we would encounter evidence of more massive black holes.

Answer 6

The force of gravity between any two objects (say, between you and the Earth) depends on the masses of the two objects, and the distance between the two centres of mass of the objects. The more massive something is, the more gravity it has, and the closer two objects are to each other the stronger the force between them is. If you were going to calculate the force of gravity between you and the Earth, you would use the distance from (more of less) your stomach to the centre of the Earth. Because you are very far away from the planets core (on the surface), the force of gravity is not very strong.

But now imagine that the earth is being squashed in on itself. Earth's mass remains the same, but the surface of the Earth is now getting closer and closer to the centre of the Earth. This must mean that the force due to gravity is getting stronger and stronger, because the distance between you and the centre is decreasing!

We can begin to understand why black holes have so much gravity. In actual fact they are (mostly) not more massive than any regular star. But, because a black hole is very dense it's "surface" is very very close to it's centre, and this allows you to come very very close to the centre of the black hole. It is because you can get very close that the gravity is so strong.

Answer 7

The reason why the gravitational attraction of a black hole is so strong is because of its large mass and density. The more massive and dense an object is, the more gravity it has. A black hole essentially has infinite density, so its gravitational force is huge.

Answer 8

Basically, the force of gravity between two objects depends on the mass (more mass --> more force) and on the distance (greater distance --> less force). A black hole is no exception - it simply has a large amount of mass in a very small space.

Answer 9

The force of gravity depends on the mass (more mass --> more force), as well as on the distance (larger distance --> less force). A black hole has a lot of mass concentrated in a small space.

Answer 10

The gravity of a black hole is so strong because a very large mass is concentrated in a tiny area.