2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/19477A one-dimensional periodic array of elastically colliding hard points, with a non-centrosymmetric unit cell, connected at its two ends to {\em identical but non-thermal} energy reservoirs, is shown to carry a sustained unidirectional energy current.4 epsf figures, submitted to Phys Rev Lett., this version contains slightly modified referencesStatistical MechanicsSoft Condensed Mattertext