Magnetic Monopoles and Quantum Field Theory*

Magnetic monopoles have intrigued physicists ever since Dirac connected their existance to the observed quantization of electric charge. This great virtue also makes quantum field theory calculations that involve both electric and magnetic charges extremely challenging. Recent work has shown that a mixing between our photon and separate "hidden" massive photon can produce small couplings of our photon to to "hidden" magnetic monopoles. This means that pertrubative calculations between electric and magnetic charges can be physically meaningful. I outline recent efforts to understand theories with electric and magnetic charges through perturbative quantum field theory. This includes some exciting results regarding the field theory of magnetic monopoles and new calculational methods that may be useful even in theories without magnetic charges.