The following article is a reformatted version of a preprint obtained from the LANL astro-ph preprint server (http://xxx.lanl.gov/abs/astro-ph/0004075). The article was written on invitation of the refereed online journal Living Reviews in Relativity and the final article, an enhanced HTML version, is now at http://www.livingreviews.org/Articles/index.html , where it will be regularly updated by its author.


THE COSMOLOGICAL CONSTANT

Sean M. Carroll


Enrico Fermi Institute and Department of Physics
University of Chicago
5640 S. Ellis Ave.
Chicago, IL 60637 USA
e-mail: carroll@theory.uchicago.edu
http://pancake.uchicago.edu/~carroll/


Abstract. This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant, observational constraints on its magnitude, and the physics of a small (and potentially nonzero) vacuum energy.


Table of Contents

INTRODUCTION
Truth and Beauty
Introducing the Cosmological Constant
Vacuum Energy

COSMOLOGY WITH A COSMOLOGICAL CONSTANT
Cosmological Parameters
Model Universes and their Fates
Surveying the Universe
Structure Formation

OBSERVATIONAL TESTS
Type Ia Supernovae
Cosmic Microwave Background
Matter Density
Gravitational Lensing
Other Tests

PHYSICS ISSUES
Supersymmetry
String Theory
The Anthropic Principle
Miscellaneous Adjustment Mechanisms
Other Sources of Dark Energy

CONCLUSIONS: THE PREPOSTEROUS UNIVERSE

REFERENCES

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