Paul Dirac

Paul Dirac (1902–1984) was an English theoretical physicist whose work joined quantum mechanics with special relativity, predicted the positron, and helped establish quantum electrodynamics.

Dirac equation: A relativistic wave equation describing spin-½ particles such as electrons. Dirac’s 1928 equation combined quantum mechanics with special relativity and implied antiparticles.
Quantum mechanics: The physical theory describing matter and energy at atomic and subatomic scales. Dirac developed a general mathematical framework for quantum states and observables.
Erwin Schrödinger: An Austrian physicist who formulated wave mechanics and shared the 1933 Nobel Prize in Physics. Schrödinger’s formulation offered a complementary route to the quantum mechanics Dirac helped unify.
Bristol: A city in southwest England where Dirac was born and studied engineering. Dirac’s formative years and early education took place in Bristol.
Large numbers hypothesis: Dirac’s proposal that strikingly large dimensionless ratios in physics may change together over cosmic time. He used comparisons among fundamental quantities to suggest that gravity might vary with the age of the universe.
Antimatter: Matter composed of antiparticles, which have the same mass as ordinary particles and opposite charges. Dirac’s theory made antimatter a physical prediction rather than a mathematical curiosity.
Dirac notation: A notation using kets and bras to represent quantum states and their dual vectors. Dirac introduced this compact language for expressing quantum states and calculations.
Werner Heisenberg: A German physicist who developed matrix mechanics and the uncertainty principle. Heisenberg’s matrix mechanics was one of the formulations Dirac showed to be equivalent to wave mechanics.
University of Cambridge: A public research university in Cambridge, England, founded in 1209. Dirac completed his doctoral studies and spent much of his academic career there.
Gravitational constant: The constant setting the strength of gravitational attraction in Newtonian gravity and general relativity. Dirac speculated that its value might decrease as the universe ages.

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