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,
The Big Bang Theory Lorre and Molaro, with Prady expected to be involved in some capacity, and intended to air in the 2017–18 season alongside "The Big Bang Theory". The initial idea for the series came from Parsons, who passed it along to "The Big Bang Theory" producers. In early March 2017, Iain Armitage was cast as the younger Sheldon, as well as Zoe Perry as his mother, Mary Cooper. Perry is the real-life daughter of Laurie Metcalf, who portrays Mary Cooper on "The Big Bang Theory". On March 13, 2017, CBS ordered the spin-off "Young Sheldon" series. Jon Favreau directed and executive produced