If time had no beginning

TL;DR

This paper explores how the Causal Set approach to quantum gravity allows for models of the universe where time has no beginning, challenging traditional notions of cosmology and the nature of time.

Contribution

It adapts the Causal Set growth process to cosmologies with no initial time, providing a framework for understanding time without a beginning in quantum gravity.

Findings

Time can be modeled as an endless growth process in causal sets.

The approach offers a way to consider pre-Big Bang cosmologies.

Implications for the nature of time and cosmological models.

Abstract

General Relativity traces the evolution of our Universe back to a Big Bang singularity. To probe physics before the singularity -- if indeed there is a ``before'' -- we must turn to quantum gravity. The Causal Set approach to quantum gravity provides us with a causal structure in the absence of the continuum, thus allowing us to go beyond the Big Bang and consider cosmologies in which time has no beginning. But is a time with no beginning in contradiction with a passage of time? In the Causal Set approach, the passage of time is captured by a process of spacetime growth. We describe how to adapt this process for causal sets in which time has no beginning and discuss the consequences for the nature of time.