The Cosmological Constant Problems (Talk given at Dark Matter 2000, February, 2000)

TL;DR

This paper reviews the old and new cosmological constant problems, discussing various approaches including quintessence and anthropic considerations, and explores the application of the anthropic principle in scalar field theories.

Contribution

It provides a comprehensive review of existing solutions to the cosmological constant problems and discusses the potential of anthropic reasoning in scalar field models.

Findings

Quintessence does not resolve the cosmological constant problems.

Anthropic considerations may offer a solution to both problems.

The anthropic principle could apply to scalar fields with random initial values.

Abstract

The old cosmological constant problem is to understand why the vacuum energy is so small; the new problem is to understand why it is comparable to the present mass density. Several approaches to these problems are reviewed. Quintessence does not help with either; anthropic considerations offer a possibility of solving both. In theories with a scalar field that takes random initial values, the anthropic principle may apply to the cosmological constant, but probably to nothing else.