Where, and how, does energy dissipation of electrical energy take place in a ballisticwire? Fully two decades after the advent of the transmissive phenomenology of electrical conductance, this deceptively simple query remains unanswered. We revisit the quantum kineticbasis of dissipation and show its power to give a definitive answer to our query. Dissipation leaves aclear, quantitative trace in the non-equilibrium current noise of a quantum point contact; thissignature has already been observed in the laboratory. We then highlight the current state ofaccepted understandings in the light of well-known yet seemingly contradictory measurements. Thephysics of mesoscopic transport rests not in coherent carrier transmission through a perfect and dissipation less metallic channel, but explicitly in their dissipative inelastic scattering at the wire'sinterfaces and adjacent macroscopic leads.
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