The history of antimatter begins in 1928 with a young physicist named Paul Dirac and a strange mathematical equation...
The equation, in some way, predicted the existence of an antiworld identical to ours but made out of antimatter. Was this possible? if so, where and how could we search for antimatter?
Dirac theorized for every particle that exists there is a corresponding antiparticle, exactly matching the particle but with opposite charge. For the electron, for instance, there should be an "antielectron" identical in every way but with a positive electric charge. In his Nobel Lecture, Dirac speculated on the existence of a completely new Universe made out of antimatter!
From 1930, the search for the possible constituents of antimatter, antiparticles, began, and it has been the main influence behind a major scientific and technical evolution over the last 70 years.
In 1932 Carl Anderson discovered the antielectron, or "positron", called so because of its positive charge. Confirmed soon after by Occhialini and Blackett, the discovery proved the existence of antiparticles as predicted by Dirac.
With the discovery of the antiproton in 1955, Segre' and his group of collaborators (O. Chamberlain, C. Wiegand and T. Ypsilantis) had succeeded in a further proof of the essential symmetry of nature, between matter and antimatter.
Only a year later, a second team working at the Bevatron (B. Cork, O. Piccione, W. Wenzel and G. Lambertson) announced the discovery of the antineutron.
By now, all three particles that make up atoms (electrons, protons and neutrons) were know to each have an antiparticle. So if particles, bound together in atoms, are the basic units of matter, it is natural to think that antiparticles, bound together in antiatoms, are the basic units of antimatter.
Towards the end of 1995, the first such antiatoms were produced at CERN by a team of German and Italian physicists. Although only 9 antiatoms were made, the news was so thrilling that it made the front page of many of the world's newspapers.
So what happens when matter meets antimatter?
If a particle and its antiparticle come into contact with each other, the two annihilate each other.
Antimatter is not found naturally on Earth, except very briefly and in vanishingly small quantities. This is because antimatter which comes to exist on Earth outside the confines of a suitably equipped physics laboratory would inevitably come into contact with the ordinary matter that Earth is made of, and be annihilated.
