2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/143561In this letter it is proposed to study the Bekenstein's $ξ(4)$ calculation of the $S/E$ bound for more general geometries. It is argued that, using some relations among eigenvalues obtained in the context of Spectral Geometry, it is possible to estimate $ξ(4)$ without an exact analytical knowledge of the spectrum. Finally it is claimed that isospectrality can define a class of domains with the same ratio $S/E$.4 pages. References and few comments addedHigh Energy Physics - Theorytext