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The Question

(Submitted March 30, 1998)

Could you tell me who created antimatter, and who first studied it?

The Answer

Antiparticles are just a set of sub-atomic particles with some properties opposite to those of another set of particles with which we are more familiar. For example, the positron is the antiparticle equivalent of the electron. When a particle and its antiparticle meet, they annihilate with the release of a lot of energy.

Antiparticles will have been produced in the big bang which initiated the universe. In fact, most models of the big bang produce as much antimatter as ordinary matter, which is not easy to reconcile with the largely matter universe we see around us. Antiparticles are also produced in the transformation and interaction of other particles. For instance, a proton can sometimes produce a neutron and a positron.

The English physicist Paul Dirac first proposed the existence of antiparticles, when he derived equations which had solutions corresponding to both normal and antimatter particles. The American physicist Carl Anderson made the first detection of antimatter when looking at cosmic ray tracks in 1932 and noting that some tracks bent the 'wrong way' in a magnetic field.

Paul Butterworth
for the Ask an Astrophysicist team

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