what exactly is a blackhole?

Answer 1

A black hole is an object with a gravitational field so powerful that even electromagnetic radiation (such as light) cannot escape its pull.[1]

Both Newtonian physics and Einstein's general relativity predict the existence of black holes, but:

The Newtonian version incorrectly assumes that photons have rest mass (see History of the black hole concept).
General relativity tells us a lot more about black holes. For example Newtonian physics only explains why an unpowered object cannot escape from a black hole but general relativity also explains why even the most powerful spaceship cannot escape.
Merely having a very large mass is not enough to make a black hole - if it were, most galaxies would be black holes. A black hole consists of mass concentrated into an abnormally small volume. Fortunately Newtonian physics is good enough to explain this fairly accurately:

Newton's shell theorem states that a spherically symmetric body's gravity affects other objects as though all of its mass were concentrated at a point at its center. A simple example of a spherically symmetric body would be a perfectly spherical gobstopper. Stars and even many planets have this type of structure because their own gravity is strong enough to pull any unusually dense lumps into the center. So the shell theorem works very well for them and makes it much easier to calculate the effects of their gravity fields.
The gravitational pull between two objects is inversely proportional to the square of the distance between them (Newton's Law of Gravitation). For example if you halve the distance you quadruple the force, and if you reduce the distance by a factor of 10 you increase the force by a factor of 100.
So a star's or planet's gravitational pull becomes stronger very rapidly as the distance from its center decreases.
In a normal star or even in a neutron star the radius of the outer surface is so large that the gravitational pull at the surface is not strong enough to prevent light from escaping.
So a black hole can only form if a similar mass is compressed into a much smaller radius - so small that the result is not like anything one could reasonably describe as "matter".

Answer 2

No one knows for sure. It's a theoretical entity that some believe they have found, but no one has gotten up close to one or take measurements so there is little imperical data to go by.

It is possible they are actually wormholes or occulations between universes and matter is being sucked from one place to another.

It is possible they are an ultra dense mass that is sucking in all matter.

It is possible that eventually they suck in all the light matter in the universe and then suck each other in and that is what creates the primorial atom that starts the big bang.

But this is all conjecture.

Answer 3

a cosmic object with a very strong gravity, so powerful not even light can escape it. it is created when a massive star dies, collapses under its own weight, with an enormous density that distorts space-time to the breaking point. at the center of a black hole there is the 'singularity' a point where space, time and all the laws of physics fall apart.

Answer 4

It was a massive star that has collapsed. Its mass is so high the the escape velocity from the surface would be at the speed of light. It is not actually a hole.
B

Answer 5

It is a region of space where due to its huge mass concentration the gravitational field is to strong that even light cannot escape from its interior (so it is called black).

Take a look at

http://en.wikipedia.org/wiki/Black_hole

Answer 6

Put your search engine to use. There's a lot of interesting information and artciles online re: various astronomical subjects, including black holes.

Answer 7

It's a very dense mental with powerful gravity.
Why does it called Black hole?
Because its gravity is very powerful that anything also light can not runaway.
We can't see that because light hasn't any reflection.

Answer 8

when a giant star 'dies' it collapses into itself because of the great gravity. if the star is big enough, this gravity will begin to suck in other things, this is called a black hole. basically an area of great gravity

Answer 9

A singularity.

Answer 10

its a thingy that sucks up other things its like a vacume cleaner