Whats the simplest proof that the Electromagnetic laws are independent of frame of reference? .What I know is contradiction method which einstein also used to conclude the postulate of SR.
Whats the simplest proof that the Electromagnetic laws are independent of frame of reference?
The fact that Maxwell's equations can be written completely in terms of four-vectors and/or tensors that transform appropriately under a Lorentz transformation. http://hepth.hanyang.ac.kr/~kst/lect/relativity/x850.htm for details. I think Griffiths uses a similar method, but I don't have my books here at home.
This argument writes Maxwell's equations in terms of the (electric) scalar potential and the (magnetic) vector potential. You can also write them in terms of the electromagnetic field tensor [itex]F[/itex], whose components are the components of [itex]\vec E[/itex] and [itex]\vec B[/itex]. Griffiths has the details.