To astronomers and other scientists, the Big Bang is the name of a theory on the creation of the universe. They sought to understand why the universe seems to be expanding, moving away from the earth. Their theory states that the universe began as a very dense, hot, and infinitely small core. The Big Bang occurred when it exploded, spreading matter throughout the universe.
The term “Big Bang” refers to not only the moment of the original event, but also the theory itself, which includes an explanation of the origin and expansion of the universe, and the creation of primordial matter.
Cosmic microwave background radiation (CMB) was predicted as early as 1948, using the precepts of the Big Bang theory. In the 1960’s, the existence of CMB was confirmed, providing validation to this idea.
Ancient civilisations and astronomers recorded the movements of the heavens. Over time, it became evident that some heavenly bodies (like spiral nebulae) were moving away from earth. At that time, people did not understand that there were many galaxies outside the Milky Way, and these retreating stars were linked with other galaxies.
Edwin Hubble made an important discovery in 1929 when he found that the light from other galaxies is shifted further to the red end of the color spectrum as they get further away. This revolutionary concept suggested that the universe was indeed expanding, and provided a framework for the later work of Albert Einstein.
The name for this theory developed out of the bickering of two scientists. Georges Lemaitre advocated the Big Bang theory, which was refined by George Gamow (though as yet nameless). Fred Hoyle proposed a different theory, in which the universe would continue to regenerate itself – new matter would be created as galaxies moved further apart, making the universe essentially the same throughout time. In a radio interview in 1949, Hoyle referred disparagingly to Lemaitre’s theory as “this big bang idea”, a pejorative he was to use in further broadcasts and lectures. The media picked up on the name, and it stuck.
The Big Bang theory received a boost with the discovery of cosmic microwave background radiation, long theorized but not proven until 1965. With that discovery, the Big Bang became the single best scientific explanation for the creation of the cosmos. Current efforts focus on understanding the formation of galaxies, while trying to reconcile the theory with actual observations. Advances in technology, like that provided by the Hubble telescope and more, have been launched and are continuing to add to our understanding of the universe.