Chennai Mathematical Institute


3.30 pm, Lecture Hall 2
The Gibbons-Hawking-York Boundary Term in a Causal Set

Sumati Surya
Raman Research Institute, Bangalore.


I will give a brief introduction to the causal set approach to quantum gravity which is based on a Lorentz-invariant discretisation of spacetime. Unlike the discretisation of a Euclidean space via a triangulation or a fixed valency graph, this discretisation of a causal Lorentzian spacetime yields a locally finite partially ordered set (or causal set), which is a graph of variable valency. Understanding how continuum geometry and topology are encoded in a causal set has been a challenge, and it is only recently that a candidate for a discrete Einstein Hilbert action in arbitrary dimensions has been found. Here I will describe the corresponding discrete boundary terms for the action for spacelike boundaries which reduce to the standard Gibbons-Hawking-York terms in the continuum limit.