# Black Holes

Essay by meatizmurder October 2008

Scientists have been trying to determine if black holes (earlier known as `frozenstars') truly do exist for several decades now. Thanks to the great Albert Einstein and his theory of relativity, researchers have been able to predict the cosmic phenomenon of black holes. A black hole is basically an area of space that has an unbelievably high area of concentrated mass for the space it occupies, making it impossible for an object to escape its gravitational pull. This is due to escape velocity; the velocity required to exit an object's gravitational pull. Because black holes are so dense and massive the gravitational pull they possess captures light itself, making it impossible to ever escape a black hole (for nothing as of yet is faster than the speed of light).

In 1915, Einstein developed the theory of gravity called General Relativity. Einstein's earlier theory of time and space, Special Relativity, proposed that distance and time are not absolute.

General Relativity proposed that gravity, as well as motion, can affect the intervals of time and of space. The ticking rate of a clock depends on the motion of the observer of that clock; likewise for the length of a yard stick. The key idea of General Relativity, called the Equivalence Principle, is that gravity pulling in one direction is completely equivalent to acceleration in the opposite direction. A car accelerating forwards feels just like sideways gravity pushing you back against your seat. An elevator accelerating upwards feels just like gravity pushing you into the floor.

A few months later, Karl Schwarzschild gave the solution for the gravitational field of a point mass, showing that something we now call a black hole could theoretically exist. Although the idea of light being trapped in such a dense object dates back to 18th century and was the first major new theory of gravity since Isaac Newton's, it wasn't until Einstein developed general relativity that Karl Schwarzschild derived a mathematical solution to describe such an object. The Schwarzschild radius is now known to be the radius of the event horizon of a non-rotating black hole, but this was not well understood at that time. The research led to belief that when a massive star runs out of fuel and is no longer able to support itself against its own gravitational pull that it will collapse into itself to form a black hole.

Something that black holes possess due to the fact that their massiveness distortsspace and time making obsolete usual rules of geometry are `event horizons'. These canbe considered the perimeter of black holes as it marks the boundary line where the escapevelocity is equal to the speed of light. Anything inside the event horizon will be unable toescape the powerful gravitational pull of the black hole's center. It is said to be quite easyto pass the event horizon since the spherical surface is moving outward at the speed oflight, making impossible to escape unless traveling at greater speed than light.

After the first true acknowledgment of the existence of black holes, scientistspredict that they are much like dinosaur fossils; patiently awaiting our discovery amongthe cosmos. The true discovery of black holes opens the door to new andunimaginable possibilities that we have yet to conceive. Perhaps one day we will be ableto travel the universe ourselves for these discoveries rather than peering through atelescope from Earth. The truth remains that we are coming closer to understanding themysteries of the universe and of the cosmos that have plagued mankind since ourexistence.

Bibliography"The Elegant Universive" by Brian Grenne