Lagrangian and Hamiltonian Formulation of Classical Electrodynamics without Potentials

Abstract

In the standard Lagrangian and Hamiltonian approach to Maxwell's theory the potentials $A^{\mu}$ are taken as the dynamical variables. In this paper I take the electric field $\vec{E}$ and the magnetic field $\vec{B}$ as the the dynamical variables. I find a Lagrangian that gives the dynamical Maxwell equations and include the constraint equations by using Lagrange multipliers. In passing to the Hamiltonian one finds that the canonical momenta $\vec{\Pi}_E$ and $\vec{\Pi}_B$ are constrained giving 6 second class constraints at each point in space. Gauss's law and $\vec{\nabla}\cdot\vec{B}=0$ can than be added in as additional constraints. There are now 8 second class constraints, leaving 4 phase space degrees of freedom. The Dirac bracket is then introduced and is calculated for the field variables and their conjugate momenta.