Born-Infeld model

In physics, it is a particular example of what is usually known as a nonlinear electrodynamics. It was historically introduced in the 30's to remove the divergence of the electron's self-energy in classical electrodynamics by introducing an upper bound of the electric field at the origin. The Born-Infeld electrodynamics possesses a whole series of physically interesting properties:

First of all the total energy of the electromagnetic field is finite and the electric field is regular everywhere.

Second it displays good physical properties concerning wave propagation, such as the absence of shock waves and birefringence. A field theory showing this property is usually called completely exceptional and Born-Infeld theory is the only completely exceptional "regular" nonlinear electrodynamics.

Finally (and more technically) Born-Infeld theory can be seen as a covariant generalization of Mie's theory, and very close to Einstein's idea of introducing a nonsymmetric metric tensor with the symmetric part corresponding to the usual metric tensor and the antisymmetric to the electromagnetic field tensor.

During the 90's there was a revival of interest on Born-Infeld theory and its nonabelian extensions since they were found in some limits of string theory.