What is the big bang theory?

This idea allowed for two main opposing possibilities. One was Lemaître's Big Bang theory, advocated and developed by George Gamow. The other possibility was Fred Hoyle's steady state model in which new matter would be created as the galaxies moved away from each other. In this model, the universe is roughly the same at any point in time. It was actually Hoyle who 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 as well. Some of these alternatives included the Milne model, Richard Tolman's oscillatory universe, and Fritz Zwicky's tired light hypothesis.