## Knows

Antimatter sounds like an exotic and mysterious substance that could destroy the world in no time at all. In fact, it is the same as everything else, just with a different charge[ref]. Antiparticles have all the same properties[ref] as particles, with the same mass and the same stability, and so are not more than everyday matter. Every particle has a corresponding antiparticle, with all of the same properties, except with an opposite charge. So an electron[ref] which is negatively charged[ref], will have a positively charged[ref] antiparticle called a positron.

The problem comes when matter and antimatter come together. Because there is a lot of matter in our universe, antimatter is quite likely to bump into its corresponding matter partner. When an equivalent matter and antimatter pair collide they annihilate, which means that they disappear, releasing a huge amount of energy. Antiparticles can only annihilate with their particle pair, so a antiproton will not annihilate with an electron. However, because there are lots of protons around in our universe, it is likely that the antiproton will quickly find one to annihilate with.

## Don't Knows

There is a lot that we still don’t know for certain about antiparticles. We do not know why there are so many particles and not many antiparticles. It is obvious that antiparticles will annihilate quickly which explains why there is not much antimatter left in our universe, but if all antimatter has been annihilated by matter, then there should be no matter left at all. As it is, we have lots of matter, so there must have been a lot more matter created at the time of the big bang than antimatter. We are currently trying to work out why that is.

We create antiparticles in exactly the same quantity as particles when we collide particles. When the particles hit a target at a very high energy, many different particles will come out. Particles will be produced in pairs, with each particle also having their antiparticle.

## Outlook

We're almost done. You were probably already waiting for the last chapter, the one on the Higgs boson. Here it comes!