  The standard physical model of contemporary mesoscopic noise and transport
consists in a phenomenologically based approach, proposed originally by
Landauer and since continued and amplified by Buettiker (and others).
Throughout all the years of its gestation and growth, it is surprising that the
Landauer-Buettiker approach to mesoscopics has matured with scant attention to
the conservation properties lying at its roots: that is, at the level of actual
microscopic principles. We systematically apply the conserving sum rules for
the electron gas to clarify this fundamental issue within the standard
phenomenology of mesoscopic conduction. Noise, as observed in quantum point
contacts, provides the vital clue.
