Special Relativity And Classical Field Theory -

CFT is built on the Action Principle . We define a Lagrangian density ( Lscript cap L

These were the first true relativistic field theories. In four-vector notation, electricity and magnetism are not separate forces but components of a single Electromagnetic Tensor ( Fμνcap F raised to the mu nu power Energy-Momentum Tensor ( Tμνcap T raised to the mu nu power Special Relativity and Classical Field Theory

The consequence is that space and time are not independent. They merge into a four-dimensional manifold called . In this framework, "distance" is replaced by the spacetime interval , which remains constant even as individual observers disagree on lengths (length contraction) and durations (time dilation). 2. The Shift to Fields: Classical Field Theory CFT is built on the Action Principle