Define the Action integral in four dimensional space-time.

Kinetic and potential energy appear in the Lagrangian.

Symmetries and Conservation Laws

Time invariance implies energy conservation.

Define the canonical momentum.

Invariance under a space transformation implies conservation of the sum of the momentum of the particles.

1. Inertial Reference Frames
2. Principle of Least Action
3. Invariance of the Laws of Nature
4. Lagrangian Mechanics
5. Conservation of Charge and Momentum
6. Relativistic Wave Equation and Conservation Laws
7. Invariance under Gauge Transformations
8. Gauge Theory

This Stanford Continuing Studies course is the second of a six-quarter sequence of classes exploring the essential theoretical foundations of modern physics. The topics covered in this course focus on quantum mechanics. The course is taught by Leonard Susskind, the Felix Bloch Professor of Physics at Stanford University.