  The mean inner potential of a solid is known to be proportional to its
diamagnetic susceptibility. Superconductors exhibit giant diamagnetism. What
does this say about the connection between superconductivity and mean inner
potential? Nothing, according to the conventional theory of superconductivity.
Instead, we propose that a deep connection exists between the mean inner
potential, diamagnetism, and superconductivity: that they are all intimately
linked to the fundamental charge asymmetry of matter. We discuss how this
physics can be probed experimentally and what the implications of different
experimental findings would be for the understanding of superconductivity.
