In Defense of Dogma: Why There Cannot be a Relativistic Quantum Mechanics of (Localizable) Particles

Abstract

IN SOME QUARTERS, AT LEAST, IT COUNTS as the “received view” that there cannot be a relativistic, quantum mechanical theory of (localizable) particles. In the attempt to reconcile quantum mechanics with relativity theory, that is, one is driven to a field theory; all talk about “particles” has to be understood, at least in principle, as talk about the properties of, and interactions among, quantized fields. I want to suggest, today, that it is possible to capture this thesis in a convincing “no-go theorem”. Indeed, it seems to me that various technical results on the “non-localizability” of particles in (so-called) relativistic quantum mechanics, going back some thirty years, are best understood as versions of such a theorem.¹

... although it is not a theorem, it is widely believed that it is impossible to reconcile quantum mechanics and relativity, except in the context of a quantum field theory. A quantum field theory is a theory in which the fundamental ingredients are fields rather than particles; the particles are little bundles of energy in the field.

(Weinberg 1987, 78–79; italics added)

I wish to thank Rob Clifton, William Demopoulos, Gordon Fleming, Michael Friedman, Geoffrey Hellman, Simon Saunders Abner Shimony for helpful comments.