### Black Holes

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 its 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 its 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 Einsteins 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 bodys

gravitational force (Chaisson, 77). If a body is

compacted, such that its weight stays the same

but its radius, or size, becomes smaller, its

escape velocity increases in parallel (Chaisson,

196). The simple formula for this, in physics, states

that a bodys escape velocity is equal to the

square root of its mass, divided by its radius

(Chaisson, 77). For example, if a bodys mass is

two-hundred, and its size is twelve and one half,

the escape velocity would be four. If the size of

the same body is reduced to two, while its mass

remained at two-hundred, the escape velocity

increases to ten. Since a black holes size is

always decreasing and its 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 holes

gravity is powerful enough to trap light because its

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, therefor 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

Einsteins 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,