it has always mystified me how a supercurrent can flow forever in a superconductor. seems like perpetual motion to me. it ocurrs to me now that the simplest explanation is that there is no actual current at all. that nothing is actually flowing in any supercurrent. that the supercurrent merely represents a new quantum state of matter. (this would also explain how insulators can be superconductors) what experimental evidence is there that a supercurrent is the flow of actual electrons?