Cosmic Microwave Background

Key Stage 4

This image shows the temperature variations of the early universe. The different colours represent around 10^-4K temperature variation.

Meaning

The cosmic microwave background (CMB) is the radiation left over from the big bang which comes from all directions in space.

About The Cosmic Microwave Background

The CMB shows that at some point in the past all the matter in the Universe was at roughly the same temperature everywhere. This shows that the Universe must have once been very small.