There have been many big bangs. One particularly important one is the 'Big Bang' in which the Universe began, according to current cosmological understanding, approximately 13.8 billion years ago. This was not a bang at all, in the sense of an explosion, because there was nothing to explode into -- rather it was space itself which was expanding, as it has continued to do for 13.8 billion years. Why, then, do we use this evocative but misleading name for what is arguably the most important event to have ever taken place? It was famously coined by cosmologist Fred Hoyle in a BBC Third Programme broadcast on 28 March 1949 to describe the expanding universe concept, then the main competing theory to one he helped develop, the (now-discredited) steady-state (or continuous creation) theory (emphasis added):
We now come to the question of applying the observational tests to earlier theories. These theories were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past. It now turns out that in some respect or other all such theories are in conflict with the observational requirements.1
The term 'big bang' stuck -- or it least it did from the 1970s -- and it now stands for the entire cosmological theory of which it is just one part.2
But why did Hoyle choose that particular phrase, 'big bang'? On one level it is simply catchy, evocative and onomatopoeic. Hoyle himself said later that 'I was constantly striving over the radio -- where I had no visual aids, nothing except the spoken word -- for visual images [...] And that seemed to be one way of distinguishing between the steady-state and the explosive big bang'.3
...continue reading- Fred Hoyle, script, March 1949; in Fred Hoyle: An Online Exhibition. Apparently reprinted in Listener, 7 April 1949, but I haven't seen this. [↩]
- Helge Kragh, ‘Big Bang: the etymology of a name’, Astronomy & Geophysics 54, no. 2 (2013): 2.28-2.30. [↩]
- Quoted in ibid., 2.29. Kragh argues, I think persuasively, that Hoyle did not intend 'big bang' to be derisive, as is often said. [↩]