Question: What is the Big BANG?

James Verdon answered on 22 Jun 2012:

The Big Bang is when the universe began.

Initially, there was no matter in the universe, just energy, all contained at a singularity (or a point), and the universe didn’t exist. The big band is where that energy singularity suddenly began expanding. As expansion continued, the energy converted into matter following Einstein’s equation E=mc^2 (squared). The matter formed the protons, neutrons and electrons that make up the atoms and molecules that make up us.

People often think of the big bang as like an explosion, but that’s not really true. An explosion explodes into something (into the air and the ground, for example), whereas the big bang was the explosion and expansion of space itself.

There’s lots of evidence for the big bang. It was first suggested because astronomers noticed that all the galaxies are moving apart from each other, meaning that they must have been together originally. Also, we can actually hear echoes of the big bang – the radiation produced by the big bang is still out there, and we can record it on radio telescopes.

However, while scientists can describe what happened during the big bang, we don’t really know why it happened, nor what was there before it happened.