Superconducting Ring In a superconducting ring does the contraction of space between electrons cause them to move inwards? Like in this animation. Force Between Parallel Wires With Current In the proton frame of two parallel wires with identical current, I've been told they attract and this is because the motion and length-contraction of the electrons increases the negative charge density. Is this correct? Because it seems this explanation accounts for the protons in one wire being attracted to the excess electrons in the other wire, but ignores the excess electrons being repulsed by the excess electrons in the other wire. This animation shows a neutral wire becomes negatively charged when a current runs through it. So it's easy to see how two such wires would repel each other. Veritasium's Video On Electromagnetism I'm referring to this video: Notice the separation in the electrons' rest frame at 1:17. Twelve electrons fit on the screen. At 1:28 the electrons start moving but their separation remains the same. At 2:08 the electrons' rest frame is again shown but the separation has increased so only 8 of them fit on the screen, and no explanation is provided for why this is. Did Veritasium make a mistake with this video? Another thing is at 1:28 when the electrons start moving, it seems their density should increase, and attract the cat-ion. Yet this density increase is not shown. In fact the narrator specifically says the density doesn't change. I've posted all these questions to Reddit but response time is very, very slow there.