History of creationism the universe was concentrated into a single point, a "primeval atom" where and when the fabric of time and space came into existence. However, in the 1920s and 1930s almost every major cosmologist subscribed to a view that the universe is in an eternal steady state. After Lemaître proposed his theory, some scientists complained that its assumption that time had a beginning amounted to a reimportation of religious concepts into physics. When the expression "Big Bang" was coined by Fred Hoyle in 1949, he meant it to be slightly pejorative, but the term stuck and gained currency. Lemaître himself concluded
Chronology of the universe is thought to break down for this epoch due to quantum effects. In inflationary models of cosmology, times before the end of inflation (roughly 10 second after the Big Bang) do not follow the same timeline as in traditional big bang cosmology. Models that aim to describe the universe and physics during the Planck epoch are generally speculative and fall under the umbrella of "New Physics". Examples include the Hartle–Hawking initial state, string landscape, string gas cosmology, and the ekpyrotic universe. As the universe expanded and cooled, it crossed transition temperatures at which forces separated from each other. These phase