CMB stands for Cosmic Microwave Background Radiation. And that’s the echo of the big bang, its relic. Let me explain.

The universe was originally made up of hot photons, electrons, and other particles. When protons and electrons combined to form hydrogen because of the expansion of the universe, the photons were able to move freely through space, without being bothered by the positive and negative charges of the protons and electrons. Being free, they were scattered homogeneously (supposedly, you’ll see why in future articles). These photons have continued cooling down ever since, until now where they are at about 2,7°K, which is about -270°C.

It was predicted in 1948 by George Gamow and discovered by accident by Penzias and Wilson in 1966. It is considered as being one of the strongest pieces of evidence in favour of the Big Bang