- #1

magicfountain

- 28

- 0

We built it from the vector potential ##A^\mu##.

We introduced the field tensor ##F^{\mu \nu}##.

We could write the Langrangian in a very short fashion as ##-\frac{1}{4}F_{\mu \nu}F^{\mu \nu}##

In the end we derived the equations of motion for the vector potential:

##\Box A^\mu = -J^\mu##

But again we could write that as:

##\partial_\mu F^{\mu \nu} = J^\mu##

The professor then told us that the vector potential is more 'fundamental', even though we could write Lagrangian and EOM using the field tensor.

Why is that? I've thought about it, but couldn't come up with a good reason. One thought would be, that the EOM for the vector potential are a wave equation, but is that good explanation? Who's telling us, that wave equations are more fundamental?

It would be great if anybody could help me out understanding this.