Dirac in 20th century physics: a centenary assessment

Vilas Y. Rajopadhye

J. Lowell

Last year was the centenary of T. S. Eliot, perhaps the most influential of 20th-century poets writing in English. That Eliot pursued careers in publishing and banking in addition to his literary work is widely known, but many of his readers will be astonished to learn of the discovery last year of manuscripts that suggest he might at one time have been a student of physics. Published here for the first time, the poems are strongly influenced by the quantum theory that was growing vigorously when Eliot was a young man. They exhibit unmistakable echoes of “The Waste Land,” “Four Quartets” and Old Possum's Book of Practical Cats. (They also show remarkable physical prescience: Several of the ideas hinted at postdate Eliot's death in 1965.)

Giuseppe Dito

This text explores the profound and beautiful interplay between quantum physics and mathematics. We journey from the crisis of classical physics at the turn of the 20th century to the elegant, abstract mathematical frameworks that define modern quantum mechanics. We will see how physical problems forced the invention of new mathematics and how mathematical structures, in turn, provided the language to describe the quantum realm. Key figures like Planck, Einstein, Heisenberg, Born, von Neumann, Weyl, and Dirac will guide us,revealing a story where physical intuition and mathematical formalism are inextricably linked.

A Correspondent

Alexandre T. Filippov

Although many of the solitons described in previous chapters were discovered and studied in the 20th century, they could have been discovered and understood by physicists of the previous century. What I have in mind, of course, is the distinction between classical (19th century) and quantum physics (20th century). It happened that the quantum revolution in physics started at the frontier of the two centuries. At the end of 1900 the German physicist Max Planck (1858–1947) boldly introduced the notion of quanta of energy in the processes of emission of light by atoms. He also introduced a new fundamental constant in physics, the Planck constant h . The significance of this revolutionary step was not recognized until much later. Planck himself did not realize that he had started one of the greatest revolutions in physics. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.