The physics behind superconductors is pretty amazing. One of the interesting things though is that the circulation of the superconductor around the magnetic track is NOT without friction (if we define friction as the loss of energy to heat). Actually, inhomogeneity in the magnetic field of the track will create voltages as the superconductor passes through it, which will cause eddy currents to flow. These eddy currents will eventually dissipate themselves as heat, meaning that the orbit of the superconductor around the track will not last indefinitely (although it will last for a long time).
