Introduction: The Relevance of Gravity for DICE

Abstract

Gravity is unique because it acts universally on all interactions in Nature. For this reason it is also of fundamental relevance for the issues discussed in this volume - Decoherence, Information, Complexity, Entropy. Decoherence – the irreversible emergence of classical properties for a quantum system due to the interaction with its environment – can only be understood if a special initial condition holds [1]. This must be an initial condition of lacking (or small) entanglement with the environment. Since most subsystems in the universe cannot be treated as isolated, such a special initial condition must be of a cosmological nature. On cosmological scales, however, gravity is the decisive interaction, and the initial condition cannot be understood without a careful investigation into the nature of the gravitational field.