The Void in the Infinity - The Black Hole

A image of Black Hole

       Since the age of ancient Greek, people started wondering what is like on the infinite sky.  However, there is a giant dark spot on the sky that no scientists are able to tell what that is for the past centuries.

       Black Hole, a vocabulary that everybody knows, is one of the most arcane creatures in the universe.  No one, including Stephen Hawking and many famous scientists, are not able to comprehend what is inside of a black hole.  The black hole looks like a giant, dark void in the infinite space; even light is not able to escape from it.
So what is a black hole?

Hypothetic Image of a Black Hole and its Event Horizon

       Black holes are the final evolutionary stage of stars, and they are so dense that no matter is able to escape their powerful gravitational pull. Due to the gravitational force, star undergoes nuclear fusion and this energy will repel the gravity.  However, if there is not enough material to undergo fusion, the gravitational force will shrink a star to zero volume.  Therefore, a black hole is a star that has extremely large mass but small volume.
       In addition, throughout calculation, astrophysicists are able to find the boundary that matters start to be pulled into the black hole.  This boundary is known as event horizon.  The path of a matter near the event horizon will only be curved; however, once the matter touches this region of space, the matter will be pulled into the black hole.

Idea of General Relativity, Wrapping Space-time
by massive object

       Nevertheless, if light cannot even escape from it, how can we know what is inside?
       The truth is, no one are able to see what inside of a black hole.  The entire structure of black hole is only a hypothesis.  Nevertheless, astrophysicists are able to find connections between black hole and its surrounding matter.  For example, if a cluster of hydrogen gas is pulled into the event horizon, gravitational force will heat the gas particles, and those particles will emit radiations, such as X-ray.  If scientists are able to "catch" these radiations, they can calculate the gravitational field; plus, with the help of General Relativity, they can structure a black hole model.
       Just a heads up, if you accidentally fall into a black hole, do not think you are in for a treat!!  Your body will be quickly pulled apart because of the strong gravitational force, and the only escape velocity is the speed of light, which no matters (that have mass) are able to achieve.  Nevertheless, it will be cool to experience noticeable time dilation......


Video:  How Do Black Holes Form?
https://www.youtube.com/watch?feature=player_embedded&v=pvAsDIP_ccQ