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Paul Adrien Maurice Dirac – An Appreciation
N Mukunda
Of the two major revolutions in physics in the twentieth century –
the relativity theories and quantum theory – in many ways the latter
was the more profound. Its discovery was the work of many hands, an essentially
European effort, and the entire development lasted a quarter of a century.
It consisted of two distinct phases – the period of the Old Quantum
Theory, from 1900 up to about 1923-24, was the first phase, with the major
contributions coming from Planck, Einstein, Bohr and Sommerfeld. The second
phase was inaugurated by Heisenberg’s discovery of matrix mechanics
in summer 1925 and culminated in the completion of quantum mechanics more
or less as we know it today by 1926-27. In this phase the dominating figures
were Heisenberg, Dirac, Schrödinger, Pauli, de Broglie and Max Born.
In particular the actual creation of quantum mechanics was the result
of the work of the trio – Heisenberg, Dirac and Schrödinger.
Thus Dirac belongs to the period of the construction and consolidation
of the new quantum mechanics.
Read full article (30 Kb)Dirac’s Large Numbers Hypothesis
Biman Nath
It is often interesting to express values of physical quantities in the
units, not as arbitrary as pounds and inches, but that of elementary particles.
Suppose one were to express the size of the (observable) Universe in the
unit of the size of a nucleon.
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