Report-no: EFI-2001-27;
astro-ph/0107571

Abstract. A brief review is offered of the theoretical background concerning dark energy: what is required by observations, what sort of models are being considered, and how they fit into particle physics and gravitation. Contribution to the SNAP (SuperNova Acceleration Probe) Yellow Book.

Table of Contents

THE PREPOSTEROUS UNIVERSE

Dark energy

The cosmological constant problem

The coincidence problem

WHAT MIGHT BE GOING ON?

An honest cosmological constant

Dynamical dark energy

Was Einstein wrong?

DISCUSSION

REFERENCES

For a postscript version of the article, click here.