Classical field theory

Summary

A classical field theory describes physical quantities that take a value at every point of space and time. Examples are the electromagnetic field, the gravitational field and the displacement of an elastic body. The fields obey partial differential equations, the field equations, usually obtained from a Lagrangian density by a variational principle. It is classical in the sense that it is not quantized. Its mathematical tools include the calculus of variations, fiber bundles, jet bundles and the theory of hyperbolic equations.