The Big Bang

Where it all began

The Big Bang

The name “big bang” started as a joke from people who believed the universe is static and infinite in time. Eventually it became the name of the theory.

It’s an amazing idea –

The universe came into being from a singularity – a point that was infinitely dense and infinitely small.

The idea of a singularity comes from maths….

A Mathematical Singularity

So what went BANG?

The Universe!

The singularity wasn’t a point in space, it was all the space itself (and time!), packed infinitely small. It wasn’t in anything, it was all there was.

The Big Bang was the beginning of the Universe and the beginning of time and space. Time started and space expanded.

Sounds pretty weird? Why do we believe this?

Redshift

Evidence for Big Bang

•The universe is expanding – we know this from the redshift of galaxies

•The cosmic microwave background radiation – it’s absolutely everywhere, and the best explanation for that is that it comes from the very early universe when it was much smaller

•Chemical composition of the universe – the chemicals we see (mostly hydrogen and helium, but all the rest too) are very accurately predicted by the Big Bang Theory.