Black Holes


Every day we look out upon the night sky, wondering and dreaming of what
lies beyond our planet. The universe that we live in is so diverse and unique,
and it interests us to learn about all the variance that lies beyond our grasp.
Within this marvel of wonders, our universe holds a mystery that is very
difficult to understand because of the complications that arise when trying to
examine and explore the principles of space. That mystery happens to be that of
the ever elusive, black hole.

This essay will hopefully give you the knowledge and understanding of
the concepts, properties, and processes involved with the space phenomenon of
the black hole. It will describe how a black hole is generally formed, how it
functions, and the effects it has on the universe.

By definition, a black hole is a region where matter collapses to
infinite density, and where, as a result, the curvature of space-time is extreme.
Moreover, the intense gravitational field of the black hole prevents any light
or other electromagnetic radiation from escaping. But where lies the “point of
no return” at which any matter or energy is doomed to disappear from the visible
universe?

The black hole\'s surface is known as the event horizon. Behind this
horizon, the inward pull of gravity is overwhelming and no information about the
black hole\'s interior can escape to the outer universe. Applying the Einstein
Field Equations to collapsing stars, Kurt Schwarzschild discovered the critical
radius for a given mass at which matter would collapse into an infinitely dense
state known as a singularity.

At the center of the black hole lies the singularity, where matter is
crushed to infinite density, the pull of gravity is infinitely strong, and
space-time has infinite curvature. Here it is no longer meaningful to speak of
space and time, much less space-time. Jumbled up at the singularity, space and
time as we know them cease to exist. At the singularity, the laws of physics
break down, including Einstein\'s Theory of General Relativity. This is known as
Quantum Gravity. In this realm, space and time are broken apart and cause and
effect cannot be unraveled. Even today, there is no satisfactory theory for
what happens at and beyond the rim of the singularity.

A rotating black hole has an interesting feature, called a Cauchy
horizon, contained in its interior. The Cauchy horizon is a light-like surface
which is the boundary of the domain of validity of the Cauchy problem. What
this means is that it is impossible to use the laws of physics to predict the
structure of the region after the Cauchy horizon. This breakdown of
predictability has led physicists to hypothesize that a singularity should form
at the Cauchy horizon, forcing the evolution of the interior to stop at the
Cauchy horizon, rendering the idea of a region after it meaningless.

Recently this hypothesis was tested in a simple black hole model. A
spherically symmetric black hole with a point electric charge has the same
essential features as a rotating black hole. It was shown in the spherical
model that the Cauchy horizon does develop a scalar curvature singularity. It
was also found that the mass of the black hole measured near the Cauchy horizon
diverges exponentially as the Cauchy horizon is approached. This led to this
phenomena being dubbed “mass inflation.”

In order to understand what exactly a black hole is, we must first take
a look at the basis for the cause of a black hole. All black holes are formed
from the gravitational collapse of a star, usually having a great, massive, core.
A star is created when huge, gigantic, gas clouds bind together due to
attractive forces and form a hot core, combined from all the energy of the two
gas clouds. This energy produced is so great when it first collides, that a
nuclear reaction occurs and the gases within the star start to burn continuously.
The hydrogen gas is usually the first type of gas consumed in a star and then
other gas elements such as carbon, oxygen, and helium are consumed.

This chain reaction fuels the star for millions or billions of years
depending upon the amount of gases there are. The star manages to avoid
collapsing at this point because of the equilibrium achieved by itself. The
gravitational pull from the core of the star is equal to the gravitational pull
of the gases forming a type of orbit, however when this equality is broken the
star can go into several different stages.

Usually if the star is small in mass, most of the gases will