Hi CANGAS, I guess you're referring to this? My impression is that Dale was talking about the case introduced by Prosoothus: "What if you replace the two wires with two parallel beams of electrons travelling through a vacuum. Would they attract each other, or not?" Your example is quite clearly a case where the electrons are travelling through a conductor. So the question is "what difference does the conductor make?", I guess. Personally, my first reaction would be to think that the presence or absence of a conductor wouldn't make a difference... but I'm no expert in electromagnetism. If I were gong to make strong statements one way or the other, I'd take Dale's suggestion and work it out properly. You haven't done that, have you? Yes, if you can show a situation in which SR predicts an unambiguous event to happen in one frame but not another, then SR is disproved. But just saying it isn't enough... you've got to be rigorous or no one will believe you. So why don't you work it out? Show me the money! Please Register or Log in to view the hidden image!