Antimatter
Year of Discovery: 1929
What Is It? Antimatter are particles of the same mass and composition as protons and electrons, but with an opposite electrical charge.
Who Discovered It? Paul Dirac
Why Is This One of the 100 Greatest?
Science fiction space ships are regularly powered by antimatter drives. Futuristic
bombs are designed around antimatter. Yet neither you nor anyone you’ve ever met has
even once seen a particle of antimatter. Antimatter does not come in fist-sized chunks, but
as stray, individual subatomic particles.
Paul Dirac is considered by many to be the greatest British theoretical physicist since
Newton. Dirac was the first to predict the necessary existence of positrons and antiprotons,
or antimatter. The concept of antimatter provided a new avenue of research and understanding in physics. Dirac’s antimatter discovery has become the theoretical framework for modern particle physics. Modern cosmologists and physicists are able to extend and apply the
precepts of quantum physics, quantum electrodynamics, and quantum mechanics in large
part because of Dirac’s discovery.
How Was It Discovered?
Shy, retiring, and secretive by nature, 21-year-old Cambridge University physics
graduate student Paul Dirac had made few friends, but had gained a reputation for mathematical brilliance.
By 1923, the theories of relativity and quantum mechanics were well-established, but
their limits and the exact implications and meaning were not. Quantum mechanics, the
study of systems so small that Newtonian physics breaks down, was based on the assumption that subatomic matter acts both like particles and waves. The contradictions and paradoxical implications of this assumption and the mathematics used to try to describe it were
drawing physics toward a crisis.
Through a series of cunning research efforts and precise, articulate papers, Dirac began to chip away at these inconsistencies, bringing clarity and reason to what had previously seemed to be chaotic uncertainty. He improved the methods to calculate a particle’s
speed as defined by “Eddington’s equations”. He resolved the discrepancies of the
covariance of Niels Bohr’s frequency condition.
160