Cosmology and short-distance gravity

Abstract

If the observed dark-energy density $ρ_Λ$ is interpreted as the net contribution of the energy density of the vacuum, $ρ_Λ\equiv ρ_V \sim M_V^4$, and the corresponding vacuum length scale $λ_V = M_V^{-1}$ as the cutoff scale controlling the low-energy, effective field-theory limit of gravity, it follows that the conventional cosmological scenario based on the effective gravitational equations may be valid only up to the Tev energy scale. Such a possibility would be strongly disfavored by the existence of a relic background of primordial gravitational radiation of intensity compatible with present (or near future) experimental sensitivities.

8 pages, no figures. Essay written for the 2015 Awards for Essays on Gravitationv (Gravity Research Foundation, Wellesley Hills, MA) and awarded with "Honorable Mention". To appear in the "October 2015 Special Issue" of Int. J. Mod. Phys. D