# Why does gauge fixing break gauge symmetry?

1. Jul 7, 2015

### TimeRip496

By fixing a gauge (thus breaking orspending the gauge symmetry), the model becomes something easier to analyse mathematically, such as a system of partial differential equations (in classical gauge theories) or a perturbative quantum field theory (in quantum gauge theories), though the tractability of the resulting problem can be heavily dependent on the choice of gauge that one fixed.
https://terrytao.wordpress.com/2008/09/27/what-is-a-gauge/

What do you mean by this? As in why does gauge fixing made the model easier to analyse? Isnt gauge fixing something like choosing a coordinate?

2. Jul 7, 2015

### Staff: Mentor

Right, and choosing a coordinate system can make things easier. As an example from classical mechanics, you can reduce the six position variables of the Kepler problem (three coordinates per object) to two variables by going to the center of mass system and choosing one coordinate to be orthogonal to the motion of the objects.

3. Jul 8, 2015