Supergravity, dark energy, and the fate of the universe

We propose a description of dark energy and acceleration of the universe in extended supergravities with de Sitter (dS) solutions. Some of them are related to M theory with noncompact internal spaces. Masses of ultralight scalars in these models are quantized in units of the Hubble constant: $m^2{=nH}^2.$ If the dS solution corresponds to a minimum of the effective potential, the universe eventually becomes dS space. If the dS solution corresponds to a maximum or a saddle point, which is the case in all known models based on $N=8\mathrm{}$ supergravity, the flat universe eventually stops accelerating and collapses to a singularity. We show that in these models, as well as in the simplest models of dark energy based on $N=1\mathrm{}$ supergravity, the typical time remaining before the global collapse is comparable to the present age of the universe, ${t=O(10\mathrm{}}^{10})\mathrm{yr}.$ We discuss the possibility of distinguishing between various models and finding our destiny using cosmological observations.