THE BIG BANG

The Big Bang Theory is the dominant scientific theory about the origin of the universe. According to the big bang, the universe was created from a tremendously dense and hot state, sometime between 10 billion and 20 billion years ago from a cosmic explosion that hurled matter and in all directions.

The theory is based on the mathematical equations, known as the field equations, of the general theory of relativity set forth in 1915 by Albert Einstein.

The Big Bang theory developed from observations of the structure of the universe and from theoretical considerations. Observers determined that most "spiral nebulae" were receding from Earth, but did not grasp the cosmological implications of this fact, or realize that the supposed nebulae were galaxies outside our Milky Way.

In 1927, the Belgian priest Georges Lemaître was the first to propose that the universe began with the explosion of a primeval atom. His proposal came after observing the red shift in distant nebulas by astronomers to a model of the universe based on relativity. Years later, Edwin Hubble in 1929 found experimental evidence to help justify Lemaître's theory. He found that distant galaxies in every direction are going away from us with speeds proportional to their distance.

However, the universe's initial state was still unknown.

Two distinct possibilities emerged. One was Fred Hoyle's steady state model, whereby new matter would be created as the universe seemed to expand. In this model, the universe is roughly the same at any point in time. The other was Lemaître's Big Bang theory, advocated and developed by George Gamow. Hoyle actually coined the name of Lemaître's theory, referring to it sarcastically as "this big bang idea" during a program broadcast on March 28, 1949, by the BBC Third Programme. Hoyle repeated the term in further broadcasts in early 1950, as part of a series of five lectures entitled The Nature of Things. The text of each lecture was published in The Listener a week after the broadcast, the first time that the term "big bang" appeared in print.

While Hoyle's "steady state" and Lemaître's "Big Bang" were the two most popular models used to explain Hubble's observations, other ideas were also proposed, including the Milne model, Richard Tolman's oscillatory universe,and Fritz Zwicky's tired light hypothesis.

The big bang was initially suggested because it explains why distant galaxies are traveling away from us at great speeds. The theory also predicts the existence of cosmic background radiation (the glow left over from the explosion itself). The Big Bang Theory received its strongest confirmation when this radiation was discovered in 1964 by Arno Penzias and Robert Wilson, who later won the Nobel Prize for this discovery.

Although the Big Bang Theory is widely accepted, it probably will never be proved; consequentially, leaving a number of tough, unanswered questions.

Huge advances in Big Bang cosmology have been made since the late 1990s as a result of major advances in telescope technology as well as copious data from satellites such as COBE, the Hubble Space Telescope, and WMAP. Cosmologists can now calculate many of the parameters of the Big Bang to a new level of precision, leading to the unexpected discovery that the expansion of the universe appears to be accelerating.

The Big Bang, a scientific theory, is not based on any religion. Some people have found similarities, however, that they believe have both theological and philosophical implications, since some religious interpretations and world views conflict with the Big Bang origin of the universe.
Some interpretations of the Big Bang theory go beyond science, and some purport to explain the cause of the Big Bang itself (first cause). These views have been criticized by some naturalist philosophers as being modern creation myths. Some people believe that the Big Bang theory is inconsistent with traditional views of creation such as that in Genesis, for example, while others, like astronomer Hugh Ross, believe that the Big Bang theory lends support to the idea of creation ex nihilo