- #1

JustinLevy

- 895

- 1

[tex]\mathcal{L} \propto (-F^{\mu\nu}F_{\mu\nu}) \propto (\mathbf{E}^2 - \mathbf{B}^2)[/tex]

it appears to me that the action is not bounded from above, nor from below.

Does that mean the equations of motion we obtain by finding the path of extremal action is actually just a "saddle point"?

Regardless of the answer to that, what does it / would it mean for QED if the action is not bounded from below?