In 1927 Georges Edouard Lemaitre (1894-1966) proposed what later became known as the Big Bang Theory and developed the idea that the Universe had originated in a ‘primaeval atom’ – a sphere only about thirty times bigger than the Sun but packed with all the matter we see in the Universe today – which had exploded billions (109) of years ago like the fission of an unstable nucleus and created the expanding Universe.
In the late 1940s George Gamow (1904-68), working with Ralph Asher Alpher (1921-2007) and Robert Herman (1914-97), showed how helium would have been manufactured from hydrogen nuclei (protons) and neutrons in the Big Bang itself and predicted that the Universe should be filled with a weak background cosmic radiation at a temperature of about five degrees Kelvin (5K), left over from the Big Bang. Unaware of the work of Gamow and his colleagues, Robert Henry Dicke (1916-97) and Philip James Edwin Peebles (1935- ) predicted a background radiation of a few degrees above absolute zero.
In 1948 Fred Hoyle (1915-2001), Hermann Bondi (1919-2005) and Thomas Gold (1920-2004) proposed the Universe to be expanding but having the same density at all times and all places, with new matter created to fill the broadening gaps. This creation process has never been observed but the rate of creation required is so small that it is difficult to rule out by direct observation. In this Steady State cosmology there is no beginning and no end. Hoyle himself coined the term ‘Big Bang’ though of course he intended it to be derogatory.
In the 1960s Arno Allan Penzias (1933- ) and Robert Woodrow Wilson (1936- ) working with an antenna originally designed to test communication satellites, discovered a source of cosmic radio noise of about 3K which they could not explain. They consulted Dicke to learn that he had been searching for what they had found. This discovery of cosmic background radiation swung opinion heavily in favour of the Big Bang Theory.
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