Black Holes

For ages people have been determined to explicate on everything. Our search for explanation rests only when there is a lack of questions. Our skies hold infinite quandaries, so the quest for answers will, as a result, also be infinite. Since its inception, Astronomy as a science speculated heavily upon discovery, and only came to concrete conclusions later with closer inspection. Aspects of the skies which at one time seemed like reasonable explanations are now laughed at as egotistical ventures. Time has shown that as better instrumentation was developed, more accurate understanding was attained. Now it seems, as we advance on scientific frontiers, the new quest of the heavens is to find and explain the phenomenom known as a black hole.

The goal of this paper is to explain how the concept of a black hole came about, and give some insight on how black holes are formed and might be tracked down in our more technologically advanced future. Gaining an understanding of a black hole allows for a greater understanding of the concept of spacetime and maybe give us a grasp of both science fiction and science fact. Hopefully, all the clarification will come by the close of this essay.

A black hole is probably one of the most misunderstood ideas among people outside of the astronomical and physical communities. Before an understanding of how it is formed can take place, a bit of an introduction to stars is necessary. This will shed light (no pun intended) on the black hole philosophy.

A star is an enormous fire ball, fueled by a nuclear reaction at its core which produces massive amounts of heat and pressure. It is formed when two or more enormous gaseous clouds come together which forms the core, and as an aftereffect the conversion, due to that impact, of huge amounts of energy from the two clouds. The clouds come together with a great enough force, that a nuclear reaction ensues. This type of energy is created by fusion wherein the atoms are forced together to form a new one. In turn, heat in excess of millions of degrees farenheit are produced.

This activity goes on for eons until the point at which the nuclear fuel is exhausted. Here is where things get interesting. For the entire life of the star, the nuclear reaction at its core produced an enormous outward force. Interestingly enough, an exactly equal force, namely gravity, was pushing inward toward the center. The equilibrium of the two forces allowed the star to maintain its shape and not break away nor collapse.

Eventually, the fuel for the star runs out, and it this point, the outward force is overpowered by the gravitational force, and the object caves in on itself. This is a gigantic implosion. Depending on the original and final mass of the star, several things might occur. A usual result of such an implosion is a star known as a white dwarf. This star has been pressed together to form a much more massive object. It is said that a teaspoon of matter off a white dwarf would weigh 2-4 tons. Upon the first discovery of a white dwarf, a debate arose as to how far a star can collapse. And in the 1920's two leading astrophysicists, Subrahmanyan Chandrasekgar and Sir Arthur Eddington came up with different conclusions. Chandrasekhar looked at the relations of mass to radius of the star, and concluded an upper limit beyond which collapse would result in something called a neutron star. This limit of 1.4 solar masses was an accurate measurement and in 1983, the Nobel committee recognized his work and awarded him their prize in Physics. The white dwarf is massive, but not as massive as the next order of imploded star known as a neutron star. Often as the nuclear fuel is burned out, the star will begin to shed its matter in an explosion called a supernovae. When this occurs the star loses an enormous amount of mass, but that which is left behind, if greater than 1.4 solar masses, is a densely packed ball of neutrons. This star is so much more massive that a teaspoon of it's matter would weigh somewhere in the area of 5 million tons in earth's gravity. The magnitude of such a dense body is unimaginable. But even a neutron star isn't the extreme when it comes to a star's collapse. That brings us to the focus of this paper. It is felt, that when a star is massive enough, any where in the area of or larger than 3-3.5 solar masses, the collapse would cause something of a much greater mass. In fact, the mass of this new object is speculated to be infinite. Such an entity is what we call a black hole.

After a black hole is created, the gravitational force continues to pull in space debris and all other types of matter in. This continuous addition makes the hole stronger and more powerful and obviously more massive.

The simplest three dimensional geometry for a black hole is a sphere. This type of black hole is called a Schwarzschild black hole. Kurt Schwarzschild was a German astrophysicist who figured out the critical radius for a given mass which would become a black hole. This calculation showed that at a specific point matter would collapse to an infinitely dense state. This is known as singularity. Here too, the pull of gravity is infinitely strong, and space and time can no longer be thought of in conventional ways. At singularity, the laws defined by Newton and Einstein no longer hold true, and a "myterious" world of quantum gravity exists. In the Schwarzschild black hole, the event horizon, or skin of the black hole, is the boundary beyond which nothing could escape the gravitational pull.

Most black holes would tend to be in a consistent spinning motion, because of the original spin of the star. This motion absorbs various matter and spins it within the ring that is formed around the black hole. This ring is the singularity. The matter keeps within the Event Horizon until it has spun into the center where it is concentrated within the core adding to the mass. Such spinning black holes are known as Kerr Black Holes. Roy P. Kerr, an Australian mathematician happened upon the solution to the Einstein equations for black holes with angular momentums. This black hole is very similar to the previous one. There are, however, some differences which make it more viable for real, existing ones. The singularity in the this hole is more time-like, while the other is more space-like. With this subtle difference, objects would be able to enter the black whole from regions away from the equator of the event horizon and not be destroyed.

The reason it is called a black hole is because any light inside of the singularity would be pulled back by the infinite gravity so that none of it could escape. As a result anything passing beyond the event horizon would dissappear from sight forever, thus making the black hole impossible for humans to see without using

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