Quantizing EM Fields by Fixing the Gauge
An EM gauge is a relationship between
and
that does not change the Maxwell
equations.
![](Images/Coulomb_gauge.jpg)
Coulomb gauge.-
![](Images/Lorenz_gauge.jpg)
Lorenz gauge.
For EM with no gravity, one is free to assign arbitrary values to the
diagonal.
Slide 24 called it first.