In his 1905 paper introducing special relativity, Einstein calls attention to the asymmetry in the classical treatment of the relative motion of a magnet and a conductor: In a previous post, it was explained to me that, when the conductor is moving, the electromotive force has "in itself ... no corresponding energy" because the integral of work along the path of the moving conductor cannot always be resolved to a scalar quantity. The integral of the work done along the path of the moving magnet, on the other hand, does resolve to a scalar in all cases. Hence the asymmetry. (I don't understand the math well enough to understand why the asymmetry arises. If in my ignorance I've butchered the explanation somewhat, my apologies to BCrowell.) Einstein claims to have eliminated this asymmetry by transforming the event to the frame of the moving conductor. In that frame, the force on the charge is due to the electric field, which, as noted, has "a certain definite energy." It seems to me that the asymmetry has been only partially removed. I explain in the following what I mean by "partially removed." Here is Einstein on the removal of the asymmetry: In essence, the asymmetry is removed by always considering the charge to be at rest. This way, the force is always due to the electric field, and there is consequently always "a certain definite energy" associated with the force. First, the success of the theory in establishing that the force can be legitimately considered as due to an electric field must be recognized. Prior to Einstein, it was not possible to consider the moving electric charge to be at rest, because it was the movement relative to the ether which generated all electromagnetic effects. Movement relative to the ether is an absolute fact; it cannot be transformed away. With the elimination of the ether, only the relative motion of magnet and charge come into play, and it is legitimate to consider the conductor to be at rest. It is the rest of the claim that I am having trouble accepting. It is not at all clear to me (as Einstein says it should be) that the asymmetry has been removed. Rather, it seems to me that the theory establishes the rest frame of the conductor as the preferred frame. According to the principle of relativity, as declared by Einstein himself, the laws of nature should be of the same form for all observers. Yet, as I understand the text above, the event as seen by the charge at rest is of a different form than the event as seen by the magnet at rest. The need for the concept of electromotive force is driven by this difference in form. Further, Einstein says that the view from the rest frame of the charge is the true view, while the view from the rest frame of the magnet is affected by the motion of that frame relative to the frame of the charge. Comments?