Question: What is antimatter?

Frank Longford answered on 17 Mar 2015:

Antimatter is just what it sounds like – the opposite of matter. Any antimatter particle (like a positron or an anti-proton) has the same mass as its matter counterpart, but opposite properties like charge and something called “spin”. If an matter and antimatter version of the same particle meet, they will both annihilate each other and release all their mass as energy. It’s very strange to think about antimatter because we don’t see it in our everyday lives since any antimatter particle that is created is nearly instantly destroyed again. But we can see the traces of where these particles have been using powerful experiments.

The Physical theory of how protons, neutrons and electrons work is called “quantum mechanics”. Most of our universe is empty space – every atom contains a hard nucleus in the centre but the rest is made up of electron orbitals, which spread out over such a large area compared to the size of the nucleus that around 99% of the atom is empty. From that empty space, quantum mechanics states that there is always a possibility that particles (matter and antimatter) can spontaneously be formed and destroyed. Strangely enough though, it seems that matter is much more stable than antimatter and so our universe is made up nearly entirely of matter. Why this is the case is still a mystery to physicists.