The action must be Lorentz invariant to ensure that the physical laws derived from it remain consistent across different inertial frames. This invariance is a fundamental principle in the formulation of relativistic physics, as highlighted in Greiner's "Field Quantization" Chapter 2. The discussion emphasizes that while the concept may seem self-evident to some, it requires clear explanation for comprehensive understanding. The necessity of Lorentz invariance is crucial for maintaining the universality of physical laws.
PREREQUISITESPhysicists, students of theoretical physics, and anyone interested in the foundations of relativistic physics and quantum field theory.