Time and Tachyon

TL;DR

This paper explores the classical and quantum dynamics of tachyon fields on unstable D-branes, highlighting their correspondence with dust-like matter and their potential role as a time parameter in quantum cosmology.

Contribution

It analyzes the classical behavior of tachyon fields, their late-time configurations, and investigates their use as a time variable in quantum gravity frameworks.

Findings

Tachyon dynamics resemble dust-like matter at late times.

Decoupling of tachyon from gravity leads to the Wheeler-de Witt equation.

Potential use of tachyon as a time parameter in quantum cosmology.

Abstract

Recent analysis suggests that the classical dynamics of a tachyon on an unstable D-brane is described by a scalar Born-Infeld type action with a runaway potential. The classical configurations in this theory at late time are in one to one correspondence with the configuration of a system of non-interacting (incoherent), non-rotating dust. We discuss some aspects of canonical quantization of this field theory coupled to gravity, and explore, following earlier work on this subject, the possibility of using the scalar field (tachyon) as the definition of time in quantum cosmology. At late `time' we can identify a subsector in which the scalar field decouples from gravity and we recover the usual Wheeler - de Witt equation of quantum gravity.