| Dirac
was a british theoretical physicist and Nobel laureate,
renowned for his prediction of the existence of the positron,
or antielectron, and for his research in quantum theory. Dirac
was the first to apply quantum mechanics to an electromagnetic
field. His work contained the basis for quantum field theory,
which Dirac called quantum electrodynamics. The singular delta
function was invented by Dirac in order to prove two problems
were equivalent. The delta function is now used in many
different areas of mathematics and physics and is considered
fundamental.
In 1926 he derived Balmer-spectrum
energy levels of the hydrogen atom. He was the first to derive
the Lorentzian shape of spectral lines using quantum
mechanics. He introduced the terms bra and ket from the word
bracket to denote the use of parts of the bracket. The half
brackets were for state vectors and their eigenvalues. One of
his major breakthroughs was the use of an algebraic version of
quantum mechanics based on Poisson brackets.
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Paul
Adrien Maurice Dirac
(1902-1984)
