Entropy Bounds and Dark Energy

Abstract

Entropy bounds render quantum corrections to the cosmological constant $\Lambda$ finite. Under certain assumptions, the natural value of $\Lambda$ is of order the observed dark energy density $\sim 10^{-10}{\mathrm{eV}}^4$, thereby resolving the cosmological constant problem. We note that the dark energy equation of state in these scenarios is $w\equiv p/\rho =0$ over cosmological distances, and is strongly disfavored by observational data. Alternatively, $\Lambda$ in these scenarios might account for the diffuse dark matter component of the cosmological energy density.

Comments: 6 pages, Latex. Added discussion of non-cosmological limits on holographic dark energy. Version to appear in Physics Letters B