Sixty Second Adventures in Astronomy The Big Bang David Mitchell: Sixty second adventures in astronomy. Number one, the big bang. Just how big was the Big Bang? The idea that the universe is expanding as the result of a single explosion wasn't always universally popular. In fact, the term 'Big Bang' was coined in 1949 by astronomer Fred Hoyle as a way of sarcastically dismissing it. But thanks to Edwin Hubble we now know our observable universe is expanding, and extrapolating backwards we can tell that 13.7 billion years ago it was all compacted into one super-dense ball. And this 'singularity' expanded and cooled to become everything in the universe that we see around us. So though the Big Bang involved everything in existence - its beginnings were really quite small. And after measuring the background radiation in the universe, astronomers have worked out that the Big Bang was only around 120 decibels - about the volume of an average rock concert. So, while the Big Bang still has a lot to teach us about the universe, we do know, at least to start with, it wasn't particularly big. And it wasn't much of a bang either.