What is a Black Hole?

A black hole is probably the most amazing, but confusing, object in our solar system. You cannot look into a telescope and see a black hole, because they have such a strong gravitational pull that they don't even allow light to escape (hence, they are black), but we are very sure that they exist because of evidence from the Hubble Telescope imaging and Einstein's General Theory of Relativity, although Einstein denied their existence. We can see black holes because they cause objects to orbit around their event horizon, such as dust particles. When we see this, an observer can theorize that there is a black hole in the area. X-ray emissions are also a way to locate a black hole. There is even a theory that at the center of every galaxy there is a black hole, and the black hole is what keeps galaxies together, including our own Milky Way galaxy.

Black holes form when stars die. When the star is alive and burning, the star's heat balances the force of gravity by pushing outward. When a star's fuel is completely consumed, there is no longer enough heat to work against the force of gravity. This is when then star collapses. What becomes of the star is determined by the amount of mass it had when it died. White dwarfs are the products of stars that were approximately the size of the Sun. Stars that had about three times the Sun's mass are compressed into neutron stars. Black holes are formed by stars with a mass greater than three times that of our Sun.

It is believed that black holes are the product of a star that has collapsed under its own gravity, and forms an object with infinite density. This object is the center of a black hole, called the singularity. A singularity has infinitely strong gravitational pull and the curvature of space-time is so severe that space and time actually disappear. All laws of physics are no longer valid at the singularity, including the General Relativity Theory. This is now called quantum gravity, where space and time are broken, and nobody really knows what happens.