If theories of their existence are true, black holes are the most powerful force in the known physical universe. Many people are familiar with the term black hole, but few people actually know anything about them. A black hole forms as a result of a massive star running out of fuel to burn (Chaisson, 193). Once the star is no longer exerting outward force by burning off gases, it begins to collapse under it?s own intense, inward gravity (Chaisson, 193). It is like slowly letting the air out of a balloon. Once the star is compacted to a certain size, while it?s mass, or weight, remains the same, its gravity becomes so powerful that nothing can escape it (Hawking, 87). This critical size to weight ratio is known as the Schwarzchild Radius (Hawking, 87). Once a black hole is created in this way, an invisible area, or line around it exists. If any object crosses this line, it can no longer escape the gravitational force of the black hole (Hawking, 87). This line is called the event horizon (Hawking, 87).
If black holes are proven to exist, beyond theoretical physics, then they would probably be a very common anomaly in this universe. In 1915, Albert Einstein put forth the first real proposition of such an anomaly in his ?Theory of Relativity? (Bunn, Black Holes FAQ). In the 1930s, three physicists, doctors Volkoff, Snyder and Oppenheimer, were able to prove the validity of black holes mathematically. Since then, black holes have become a very important and integral part of science and the over all understanding of the universe. It has been proven, mathematically, that black holes have infinite, gravity based, escape velocities and an immense effect on light, time and even the very fabric of space.
All bodies in space have gravity. According to Einstein?s ?Theory of Relativity?, this is because bodies with a large mass, or weight, actually warp space (Chaisson, 77). For example, if a two dimensional sheet of cloth, stretched and suspended at four corners, represents space, and a bowling ball is placed in the center, the sheet will warp downward. If a golf ball is then set at the edge of the sheet and allowed to move freely it will be attracted toward the bowling ball, unless the golf ball is traveling at a speed great enough to not be effected by the curve. This critical speed is known as an escape velocity. This is the speed at which an object must travel to escape a body?s gravitational force (Chaisson, 77). If a body is compacted, such that it?s weight stays the same but it?s radius, or size, becomes smaller, it?s escape velocity increases in parallel (Chaisson, 196). The simple formula for this, in physics, states that a body?s escape velocity is equal to the square root of it?s mass, divided by it?s radius (Chaisson, 77). For example, if a body?s mass is two-hundred, and it?s size is twelve and one half, the escape velocity would be four. If the size of the same body is reduced to two, while it?s mass
remained at two-hundred, the escape velocity increases to ten. Since a black hole?s size is always decreasing and it?s weight is always the same, the escape velocity is infinite (Chaisson, 195). This means that nothing can escape a black hole past the event horizon, not even light.
Light is made up of waves and particles. It was discovered, in 1676, by Danish astronomer, Ole Christenson, that light travels at a very high, but finite speed (Hawking, 18). These properties of light govern that it must be subject to forces of nature, such as gravity. Light travels at such a high speed that it is not observably effected by gravity, unless that gravity is very strong. A black hole?s gravity is powerful enough to trap light because it?s escape velocity, being infinite, exceeds the speed of light (Hawking, 82). This is why a black hole is black. Once light crosses the event horizon it is drawn into the hole in space. Although the light is still hitting objects, it is not able to bounce off to indicate their existence to an observer, therefore the black hole appears as a void in space. Closing in on the edge of the event horizon, light travels back to an observer at a slower and slower rate, until it finally becomes invisible. This is due to heavy gravity and the effect that a black hole has on time (Bunn, Black Holes FAQ).
According to Einstein?s ?General Theory of Relativity?, time is not a constant (Hawking, 86). Time is relative to an observer and his or her environment (Hawking, 86). It has been proven that time moves slower at higher speeds (Hawking, 86). An experiment was conducted in which two synchronized atomic clocks were used. One was placed in a jet and flown around the Earth at three times the speed of sound, while the other was left stationary, on the ground (Hawking, 22). When the jet landed and the clocks were compared, the one in the jet displayed an earlier time. This leads to the reasoning that time is just as volatile as light or dirt. In cosmology, a singularity is an event or point that has a future or a past, but not both (Hawking, 49). In human life, death would be considered a singularity. A black hole is also considered a singularity. If an object crosses the event horizon of a black hole, it relatively ceases to exist, it has no future (Hawking, 88). Absolutely nothing in the known universe can survive in or escape from a black hole, so it can be said logically that time is stopped within the event horizon. The only way for an object to escape this fate would be for a strange anomaly to occur in the fabric of space, caused by a theoretically different type of black hole. If the mathematics that describe a black hole are reversed, the outcome is an object called a
white hole (Bunn, Black Holes FAQ). As the complete opposite of a black hole, a white hole is an object into which nothing can fall and objects are only spit out (Bunn, Black Holes FAQ). At this point, white holes are strictly theory. Their existence is highly improbable.
If certain properties, such as motion or a positive or negative charge are applied to a black hole, then the possibility of a white hole forming within the event horizon arises (Bunn, Black Holes FAQ). This leads to an even more improbable occurrence called a wormhole (Bunn, Black Holes FAQ). In theory, a wormhole would truly be a tear in the fabric of space. Since time essentially has no effect on a black or white hole, if an object were to fall into a worm hole, it could conceivably be spit out anywhere in time or space (Bunn, Black Holes FAQ). If an object falls into a black hole, which has undergone the transformation into a wormhole, it could probably avoid hitting the singularity (Bunn, Black Holes FAQ). Therefore it would not be turned into spaghetti and compacted to the size of a base particle. Instead, it would follow the closest thing to a straight line that it could find, which would be to slip completely through the wormhole (Bunn, Black Holes FAQ). It sounds impossible, but it looks good on paper. If wormholes could exist, according to calculations, they would be highly unstable (Bunn, Black Holes FAQ). If anything were to disturb it, like an object passing through it, it would likely collapse (Bunn, Black Holes FAQ). Though the equations are valid, wormholes most assuredly do not exist. If they did it would probably send shivers up the science fiction community?s spine.
black holes have not been conclusively proven to exist, there is strong evidence, in the observable universe, that they do. Black holes are very important to the world of cosmology. They allow for the study of common particles under very uncommon environmental variables. scientists have vastly increased their knowledge of the universe and the properties of matter through the study of a black holes effects on light, time and the fabric of the space.
Bunn, Ted ?Black Holes FAQ.? NSF Science and Technology Center (September 1995): Online.
W.W. Norton & Company, 1988.