Covariant Growth Dynamics

The spacetime discreteness of causal set theory has enabled the formulation of novel spacetime dynamics. In these so-called “growth” dynamics, a causal set spacetime is generated probabilistically by means of a random walk on certain tree structures. The first growth dynamics – the classical sequential growth models – were proposed more than two decades ago, and their study has furthered our understanding of general covariance and covariant observables within causal set theory. In this setting, labels take the place of spacetime coordinates so that general covariance takes the form of label invariance and covariant observables are those order-theoretic properties of the causal set which are label-independent. In recent years, these insights have led to a new formulation of growth dynamics which makes no reference to labels. Here, we present an overview of these (manifestly) covariant growth dynamics.