Formation of a Black Hole
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No one really knows how a black hole is formed but scientist believe that they occur in the same way as a nuetron star. As a star goes on in its life it burns more and more of its fuel. During the time when a star is burning the outward force counters the inward pull of gravity. As the star burns out the inward gravity over comes that of the outward force which collapses the star into a small dense mass. It can crush a 10,000 mile object into a 10 mile diameter in about a second. | |
| Event Horizon This is the point at which light can no longer escape the gravity of a black hole. Creating the blackness of a black hole that we have all come to know and love. |
TYPES OF BLACKHOLES
There are two types of black holes:
Schwarzschild - Non-rotating black hole
Kerr - Rotating black hole
The Schwarzschild black hole is the simplest black hole, in which the core does not rotate. This type of black hole only has a singularity and an event horizon.
The Kerr black hole, which is probably the most common form in nature, rotates because the star from which it was formed was rotating. When the rotating star collapses, the core continues to rotate, and this carried over to the black hole (conservation of angular momentum).
The Kerr black hole has the following parts:
Singularity - The collapsed core
Event horizon - The opening of the hole
Ergosphere - An egg-shaped region of distorted space around the event horizon (The distortion is caused by the spinning of the black hole, which "drags" the space around it.)
Static limit - The boundary between the ergosphere and normal space
If an object passes into the ergosphere it can still be ejected from the black hole by gaining energy from the hole's rotation.
However, if an object crosses the event horizon, it will be sucked into the black hole and never escape. What happens inside the black hole is unknown; even our current theories of physics do not apply in the vicinity of a singularity.
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The Kerr Black Hole: A Kerr black hole adds another feature to the anatomy - an ergosphere. The ergosphere resides in an ellipsoidal region outside the outer event horizon. The ergosphere represents the last stable orbit, and the outer boundary is called the static limit. Outside of it, a hypothetical spaceship could maneuver freely. Inside, space-time is warped in such a way that a spaceship would be drawn along by its rotation.
An interesting point that comes up in the case of a spinning black hole is that of the naked singularity. The faster the black hole rotates, the larger the inner event horizon becomes, while the outer event horizon remains the same size. They become the same size when the rotational energy equals the mass energy of the black hole. If the rotational energy were to become more than the mass energy, the event horizons would vanish and what would be left is a "naked singularity" - a black hole whose only part is the singularity.
Yet another distinguishing feature of the Kerr black hole is that, since it rotates, the 0-D point that is the singularity in the Schwarzschild and Reissner-Nordstrøm black hole is spun into a ring of 0 thickness. Interesting theoretical physics can take place around this ring singularity. One consequence is that nothing can actually fall into it unless it approaches along a trajectory along the ring's side. Any other angle and the ring actually produces an antigravity field that repels matter.
