2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91584In the present contribution we analyse a simple thought process at T = 0 in an idealized heat engine having partitions made of a material with an upper frequency cut-off and bathed in zero-point (ZP) electromagnetic radiation. As a result, a possible mechanism of filling real cavities with ZP radiation based on Doppler's effect has been suggested and corresponding entropy changes are discussed.9 pages, 1 figureQuantum Physicstext