Physics of Renormalization Group Equation in QED

It is shown that the renormalization group (RG) equation in QED can only describe the finite size effects of the system. The RG equation is originated from the response of the renormalized coupling constant for the change of the system size $L$. The application of the RG equation to the continuum limit treatment of the lattice gauge theory, therefore, does not make sense, and the well-known unphysical result of the lattice gauge theory with Wilson's action cannot be remedied any more.