Caroline Bertouille, age 74, of Treherne, Manitoba, Canada, for her question:

WHAT IS ANTIMATTER?

Antimatter is matter composed of atomic particles that are the opposite of ordinary atomic particles. They have an electric charge or some other property that is the reverse of an ordinary particle's. They are called antiparticles.

Physicists have produced various antiparticles on cyclotrons or some other high energy particle accelerators. But they have not yet observed antiparticles combined into anti atoms.

If antimatter composed of anti atoms existed, it would

look just like a lump of ordinary matter. But if the two lumps came together, they would disappear and produce energy. For this reason, antimatter could never be found on the earth. If antimatter does exist, it exists outside the solar system.