Theories on the origin of the Universe
Big Bang Theory
The Big Bang theory is science's best explanation of how the universe was created. The theoryasserts that our entire universe was created when a tiny (billions of times smaller than aproton), super-dense, super-hot mass exploded and began expanding very rapidly, eventually cooling and forming into the stars and galaxies with which we are familiar. This event is said to have happened approximately 15 billion years ago. Rather than expanding outward into some preexisting vacuum, the event of the Big Bang was space itself expanding - perhaps at speeds greater than light. (While Einstein's theory of relativity forbids anything within space from travelling faster than light, it sets no limitations on how fast the fabric of space itself may expand.)
The Big Bounce Theory
universe would continuously expand and contract.
The Cyclic Universe Theory
As the name implies, a cyclic universe explodes into existence in a Big Bang, and crunches out of existence over and over again in an endless cycle. This theory is an alternative to the Big Bang that has gotten much attention from scientists after Princeton physicist Paul Steinhardt and Neil Turok of Cambridge University published an article on it in the Science online edition.
The Cyclic Universe Theory could explain the mystery of why the 'cosmological constant' is accelerating, which the Big Bang theory could not account for, says Ker Than in his article "Recycled Universe: Theory Could Solve Cosmic Mystery" on Space.com. It also answers the long-standing question of what was before the Big Bang.
Steady State Theory
Another alternative to the Big Bang theory is the Steady State theory. This theory was developed by Fred Hoyle and Thomas Gold in 1949. Ironically, Fred Hoyle was the person who coined the term 'Big Bang', sort of as a way to make fun of a theory he did not advocate.
Steady State theory claims that the universe had no beginning, but it created new matter as older galaxies moved apart. However, discovery of the CMB (Cosmic Microwave Background radiation) became a big blow against Steady State, although Hoyle maintained that the background radiation could have originated without a Big Bang, states Chandra Wickramasinghe, of the Cardiff University Center for Astrobiology.
As cosmologists and astronomers keep researching, there will undoubtedly be many more theories to come. These new findings are what make the mysteries of the universe so exciting and what keep the search for knowledge an important issue for people who love learning about what lies beyond.
