On a Time Variation of Neutrino’s Mass

Fernando de Mello Gomide∗∗ ∗∗Departamento de F́ısica Instituto Tecnológico de Aeronáutica (ITA) Centro Técnico Aeroespacial and 12200-970São José dos Campos SP Brazil Abstract After the introduction to the subject, we review the Machian relations involving the different kinds of energy densities in the Universe. By suposing that dark-matter is composed by Neutrino’s massive energy, we hint that the Neutrino’s masses should be proportional to R, while the total number of Neutrinos in the Universe increases with R , where R stands for Hubble’s length. This makes possible that the dark mater-energy density be of Neutrinos origin, to vary with R , as is necessary for a Machian Universe. The neutrino average mass is estimated for the present Universe (=10g). All correspondence should be sent to the first author. PACS: 04.20.-q ; 98.80.-k ; 98.80.Jk .