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Predicting antimatter

when theory revealed half the universe East Anglia,

Black and white image of the three physicists walking up a path.
The physicists Paul Dirac (left), Wolfgang Pauli and Rudolf Peierls, c 1953.
The father of antimatter was the University of Cambridge physicist Paul Dirac (1902-1984). His 1931 paper predicted, for the first time, the existence of particles theoretically rather than experimentally. Dirac’s theory combined quantum mechanics, used to describe the subatomic world, with Einstein's special relativity, which says nothing travels faster than light. The equation explains how things both very small and very fast - in this case, negatively charged electrons near the speed of light - behave. However this also could be applied to a particle that behaves like an electron with a positive charge - a particle that until then had not been thought to exist.

Dirac asserted that every particle has a mirror-image antiparticle with nearly identical properties, except for an opposite electric charge. And just as protons, neutrons and electrons combine to form atoms and matter, antiprotons, antineutrons and anti-electrons (called positrons) combine to form anti-atoms and antimatter. Dirac’s theory was proved unexpectedly correct when positive electrons or ‘positrons’ were discovered in cosmic radiation in 1932.

For his achievement Dirac was awarded the Nobel Prize in Physics in 1933. Current theories of the early universe suggest that there were equal quantities of matter and antimatter created in the Big Bang. So, in effect, Dirac conceived half the universe in his head.

Science Museum

Mathematics, Physics,
East Anglia
University of Cambridge
Key Individuals
Paul Dirac,