One of the most striking facts about the Universe is that it is composed almost entirely of matter. At the Big Bang equal amounts of matter and antimatter would have been created. This immediately raises the question, what happened to the antimatter? At first sight, the answer seems clear. In the early Universe, just after the Big Bang, antimatter and matter collided and annihilated into photons (particles of light).
Today, the ratio of the number of left-over matter particles to photons is tiny, just one proton or neutron for every 10 billion photons, yet this is enough to make all the galaxies, stars and planets in the present-day Universe. If the fundamental laws of nature were entirely symmetric between particles and antiparticles all the matter (and antimatter) would have completely annihilated. So, the real question is how does the difference between matter and antimatter arise?
Experiments being carried out at CERN (the European Laboratory for Particle Physics) are making precision measurements of the small differences between fundamental particles and their antiparticles as well as producing and studying entire atoms made from antimatter. However, antimatter isn't only confined to the laboratory and is found in naturally occurring sources as well as being used for medical diagnosis and in industrial applications. Antimatter Matters is an opportunity to learn about the properties of antimatter, the experiments being performed to study it and how it appears in everyday life.