Abstract
This paper charts P.A.M. Dirac’s development of his theory of the electron,
and its radical picture of empty space as an almost-full plenum. Dirac’s
Quantum Electrodynamics famously accomplished more than the
unification of special relativity and quantum mechanics. It also
accounted for the ‘duplexity phenomena’ of spectral line splitting that
we now attribute to electron spin. But the extra mathematical terms that
allowed for spin were not alone, and this paper charts Dirac’s struggle to
ignore or account for them as a sea of strange, negative-energy,
particles with positive ‘holes’. This work was not done in solitude, but
rather in exchanges with Dirac’s correspondence network. This social
context for Dirac’s work contests his image as a lone genius, and
documents a community wrestling with the ontological consequences of
their work. Unification, consistency, causality, and community are
common factors in explanations in the history of physics. This paper
argues on the basis of materials in Dirac’s archive that — in addition —
mathematical beauty was an epistemological factor in the development
of the electron and hole theory. In fact, if we believe that Dirac’s
beautiful mathematics captures something of the world, then there is
both an epistemology and an ontology of mathematical beauty.