Nearly 14 billion years ago, there was nothing and nowhere. Then, due to a random fluctuation in a completely empty void, a universe exploded into existence. Something the size of a subatomic particle inflated to unimaginably huge size in a fraction of a second, driven apart by negative-pressure vacuum energy. Scientists call this theory for the origin of the universe the Big Bang.
The Origins of the Universe: the Big Bang The diagram here illustrates the main events occurring in the history of our Universe. The vertical time axis is not linear in order to show early events on a reasonable scale. The temperature rises as we go backwards in time towards the Big Bang and physical processes happen more rapidly. The timescales and temperatures indicated on this diagram span an enormous range.