2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/33792Starting from quoted papers it show that, applying Mach's principle, on obtains transient mass fluctuation by varying proper energy. It is show why the experiments performed until now measured a smaller effect than was predicted. On establish conditions for using gravitational energy by means of transient mass fluctuations. On suggest a new type of experiment for verify the effect of transient mass fluctuation.14 pages, 3 figuresGeneral Relativity and Quantum Cosmologytext