  We analyse a picture of transport in which two large but finite charged
electrodes discharge across a nanoscale junction. We identify a functional
whose minimisation, within the space of all bound many-body wavefunctions,
defines an instantaneous steady state. We also discuss factors that favour the
onset of steady-state conduction in such systems, make a connection with the
notion of entropy, and suggest a novel source of steady-state noise. Finally,
we prove that the true many-body total current in this closed system is given
exactly by the one-electron total current, obtained from time-dependent
density-functional theory.
