Physics With Two Time Dimensions

TL;DR

This paper investigates the theoretical possibility of physical models with two time dimensions, proposing conditions under which such theories could be consistent and exploring their potential realizations and implications.

Contribution

It challenges the conventional exclusion of two-time theories by showing they can be viable if dynamics are thermal or chaotic, and discusses possible realizations including holography and emergent quantum dynamics.

Findings

Two-time theories can be consistent if dynamics are thermal or chaotic.

Such theories may be realized through holographic models.

Quantum dynamics might emerge from a second time dimension.

Abstract

We explore the properties of physical theories in space-times with two time dimensions. We show that the common arguments used to rule such theories out do not apply if the dynamics associated with the additional time dimension is thermal or chaotic and does not permit long-lived time-like excitations. We discuss several possible realizations of such theories, including holographic representations and the possibility that quantum dynamics emerges as a consequence of a second time dimension.