Quantum gravity for dummies

Dirac noted in his first paper on quantum electrodynamics [Proc. Roy. Soc. A 114, 243 (1927)] that, “The theory is non-relativistic only on account of the time being counted throughout as a c-number [classically], instead of being treated symmetrically with the space coordinates.” His suggestion for a relativistic theory of quantum mechanics is carried out here by describing the atom in configuration space as the action integral of a Lagrangian. Atomic structure is described with discrete coordinates in Minkowski space, while the atom itself resides in the curved space-time continuum of the gravitational field, the background space of quantum gravity. Although it does not meet the more ambitious goals of a string theory or loop quantum gravity, it is the first successful theory. In other words, it is the first theory to describe how gravitational fields interact with quanta at the microscopic level. This paper is dedicated to the thousands of theoretical physicists who have defended nonrelativistic theory since its inception in 1926 without questioning its limitations even as it lost touch with reality and became ever more difficult to believe.