2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/184612We define a physically reasonable mass for an asymptotically Robertson-Walker (ARW) manifold which is uniquely defined in the case of a normalized representation.14 pages, a pdf version of the preprint can also be retrieved from http://www.math.uni-heidelberg.de/studinfo/gerhardt/mass.pdf and bibtex data from http://www.math.uni-heidelberg.de/studinfo/gerhardt/bibtexcgmass.html v2: Some minor corrections, this is the version that will be printed (ATMP 10)Differential GeometryGeneral Relativity and Quantum Cosmology[2000]{35J60, 53C21, 53C44, 53C50, 58J05}text