- #1

Anypodetos

- 17

- 1

_{μν}F

^{μν}/4 and the interaction term -A

_{μ}j

^{μ}. I understand the maths of that - for one thing, the equations of motion turn out right if you plug this into the Euler Lagrange equantion.

Now I recall having learned that you can explain the forces between charged particles solely with the field energy: pushing 2 electrons together increases field energy because it goes with the square of the field strength, and pushing an electron and a positron together decreases field energy. If this is true, why do we need the interaction term at all? What am I missing?