Big Bang of the world happened a little before the beginning of space and time. During the 1930s other ideas were proposed as non-standard cosmologies to explain Hubble's observations, including the Milne model, the oscillatory universe (originally suggested by Friedmann, but advocated by Albert Einstein and Richard Tolman) and Fritz Zwicky's tired light hypothesis. After World War II, 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,
History of the Big Bang theory of the primeval atom) that the universe began with the "explosion" of the "primeval atom" — what was later called the Big Bang. Lemaître first took cosmic rays to be the remnants of the event, although it is now known that they originate within the local galaxy. Lemaître had to wait until shortly before his death to learn of the discovery of cosmic microwave background radiation, the remnant radiation of a dense and hot phase in the early universe. Hubble's Law suggested that the universe was expanding, contradicting the cosmological principle whereby the universe, when viewed on sufficiently large distance