Black holes have always had the reputation to be one of the “most talked about topics” in Cosmology. Black holes are imaginary entities predicted by the equations of general relativity. A black hole is formed when a star of undergoes a gravitational cave in, with most or all of its mass packed together into a satisfactorily small area of space, causing endless space-time curvature at that point. Such a massive space-time curvature allows nothing, not even light, escaping from its borders (Black Holes). Black holes have never been directly observed or seen but though predictions, their predictions have matched observations.
Another feature that has not been observed, but has observations to prove it, is the Inflationary Model (Reference 5). This modified version of the Big Bang theory states that the when the universe was only about 10-35 seconds old, the expansion of space-time took place at a greater accelerated pace. The huge inflation of space was made by the energy released from the separation of two forces. For around one hundred million trillion trillionth of a second, the universe grew many times faster than the speed of light, taking it from a size incredibly small, even smaller than an atomic nucleus to about the size of grapefruit (Inflationary Theory). In the process, tiny regions of the early universe were inflated to become larger than the observable universe.
Matter that can’t be identified directly, but whose existence can be based on the how objects, such as stars and galaxies, move is called Dark matter. Within a galaxy like the Milky Way, the stars move as if large quantities of dark matter exist in a vast radiance that surrounds the galaxy’s disk. Likewise, within clusters of galaxies, the individual galaxies move as if many more matter is present than that visible in the form of stars and gas and dust. There is currently much ongoing research by scientists attempting to discover exactly what this dark matter is, how much there is, and what effect it may have on the future of the Universe as a whole. This is why the cosmologists study Dark Matter.
The expansion of the universe is one of the questions, which cosmologists are trying to get an answer to. The galaxies we see in all directions are moving away from the Earth, as evidenced by their red shifts. The building up of methods for measuring distance to stars and galaxies led Edwin Hubble to the fact that the red shift (collapse speed) is proportional to distance. The fact that we see all other galaxies moving away from us does not imply that we are the center of the universe. All galaxies will see all other stars moving away from them in an expanding universe. Since the action of gravity works against the expansion, then if the density were large enough, the expansion would stop and the universe would collapse in a “big crunch”. This is called a closed universe. If the density were small enough, the expansion would continue forever. This is just short outline of the expansion of the Universe.
Cosmology is a very interesting topic and it is continued to be researched on using telescopes and other ways by the increase in technology. It is important to study cosmology because we can tell a lot about the creation of the universe and this will help us solve problems like if the Big Crunch or Black hole were to happen. It is also important to study cosmology because then we as human beings will be more educated on the topic of cosmology. Stephen Hawking once said, “My goal is simple. It is complete understanding of the universe, why it is as it is and why it exists at all.”
The Big Bang Theory. Big Bang. Windows Team. 2 June 2008