The binding energy of a H-atom, considering an electron moving around a fixed nuclei (proton), is B = - (Me^4)/(8n^2ε_0^2h^2). (m = electron mass). If one decides to work in a frame of reference where the electron is at rest, the proton would be moving around it. By similar arguments, the binding energy would be B = - (Me^4)/(8n^2ε_0^2h^2) (M = proton mass) This last expression is not correct because ______.