  Experimental results obtained last years corroborate a prediction made by
I.O. Kulik forty years ago that the energy dissipation does not result in
disappearance of equilibrium circular current observable in the normal state of
superconductor rings and normal metal rings. Contrary interpretations of the
persistent current as a Brownian motion or a dissipationless current are
compared in the point of view of the observations of this phenomenon at
presence of an electric potential difference. Distinctions between the quantum
phenomena at atomic and mesoscopic levels are accentuated. In connection of the
quantum oscillations in magnetic field of potential difference observed on
asymmetric rings with the persistent current, it is pointed out that an
experimental check of such phenomenon at thermodynamic equilibrium is possible.
