Black Holes: How They're Formed, Their Singularity Point, and Unique Properties

A Black Hole is a highly dense region of space with an enormous concentration of mass from where nothing can escape from its gravity: not even light. The term "Black Hole" comes from the fact that, at a certain point, even light is unable to break away from the attraction of these massive objects. This renders the hole's interior invisible or, rather, black like the appearance of space itself. An area surrounding a black hole, inside which events cannot affect an outside observer is called the event horizon. It means anything crosses event horizon towards a black hole will obviously never be able to get back. If you're still confused, checkout "What is a Black Hole" for more information.

A black hole forms when any object reaches a certain critical density, and its gravity causes it to collapse to an almost infinitely small pinpoint. In principle, black holes can have any mass; black holes formed by stellar death have at least twice the mass of our sun. Stellar-mass black holes form when a massive star can no longer produce energy in its core. Without the radiation from its nuclear reactions to keep the star "puffed up", gravity causes the core to collapse. The star's outer layers may blast away into space, or they may fall into the black hole to make it heavier. The theories for supermassive black holes are still growing. According to current theory they may be formed by gravitational collapse of highly massive gas cluster and the creation of supermassive black holes may be related to the birth of galaxies.

The singularity is the point of infinite density thought to exist at the center of a black hole. In a non-rotating black hole the singularity is a point, in other words it has zero length, width, and height. The singularity of a rotating black hole is smeared out to form a ring shape lying in the plane of rotation. The ring still has no thickness and hence no volume.

To understand singularity properly we need a theory of quantum gravity, because General Relativity and Quantum Field Ttheory break down at a singularity. (Quantum Field Theory works very well to describe the observed behavior and properties of elementary particles. But the theory itself only works well when gravity is so weak that it can be neglected. On the other hand General Relativity explains gravity. It explains the orbits of planets, the evolution of stars and galaxies, black holes and gravitational lenses. But the two theories can not work together. That's why we need quantum gravity.) Currently Loop Quantum Gravity and String Theory are the two major candidates for the theory of quantum gravity.

The size of black hole does not have any limit. It can be of any size. I mean, it may be a black hole of any radius and any mass. But only one thing we can say is its mass has to be a minimum two times our sun's mass. Recently, astronomers found the largest black hole ever detected, with a mass 18 billion times the mass of the Sun.

Black holes are commonly classified according to their mass. The size of black hole as determined by the radius of the event horizon, which is is proportional to the mass . According to this mass/size criterion then, black holes are commonly classified as: Supermassive black holes, Intermediate-mass black holes, Stellar black holes and Primordial black holes. Supermassive black holes are millions of times more massive than our sun. The have been detected in the center of galaxies. Intermidiate-mass black holes are thousand of times more massive than the sun. Stellar black holes have mass that is ten times that of our sun and the Primordial black holes have masses equivalent to our moon. They are also called mini or micro black holes. Current theory has predicted their production during the early stages of the evolution of the universe. Look at gallery 2 carefully . There is chart for the mass versus radius of black holes in the first image and second one is showing a supermassive black hole detected by Hubble Space Telescope.

Find out what would happen if you fell into a black hole and how black holes are detected on the next page.