The understanding of mesoscopic transport has now attained an ultimate
simplicity. Indeed, orthodox quantum kinetics would seem to say little about
mesoscopics that has not been revealed - nearly effortlessly - by more popular
means. Such is far from the case, however. The fact that kinetic theory remains
very much in charge is best appreciated through the physics of a quantum point
contact. While discretization of its conductance is viewed as the exclusive
result of coherent, single-electron-wave transmission, this does not begin to
address the paramount feature of all metallic conduction: dissipation. A
perfect quantum point contact still has finite resistance, so its ballistic
carriers must dissipate the energy gained from the applied field. How do they
manage that? The key is in standard many-body quantum theory, and its
conservation principles.Comment: 10 pp, 3 figs. Invited talk at 50th Golden Jubilee DAE Symposium,
BARC, Mumbai, 200