What is a gauge theory?

>>8502116
a scam

>>8502116
The theory you get when you take global symmetries and make them local.

>>8502116
Imagine a cylinder of a uniform colour. If I twist the cylinder you can't tell unless we draw a line on the cylinder. Choosing a gauge is the same as drawing a particular line on the cylinder. Any line will do but it just defines what you mean as a neutral position

>>8502116
Just a guess.

>>8502126
>>8502129

is the math behind that used in anything else?

>>8502150
Yes, Lie groups come from differential equations (that's how Sophus Lie discovered them).