If time had no beginning: growth dynamics for past-infinite causal sets

We explore whether the growth dynamics paradigm of causal set theory is compatible with past-infinite causal sets. We modify the classical sequential growth dynamics of Rideout and Sorkin to accommodate growth 'into the past' and discuss what form physical constraints such as causality could take in this new framework. We propose convex-suborders as the 'observables' or 'physical properties' in a theory in which causal sets can be past-infinite and use this proposal to construct a manifestly covariant framework for dynamical models of growth for past-infinite causal sets.