Order and Number, A Route to Quantum Gravity, Prof. Sumati Surya (Raman Institute)

One of the very many open problems  in theoretical physics is that of quantising  gravity, which is the attempt to successfully  combine  general relativity and quantum theory.   In this talk I will give a broad overview of  the problem of quantum gravity and the choices that we can make, along the routes we take.  This will lead me to the poset-based “causal set” approach to quantisation. This is a  discrete, Lorentzian, sum-over-histories formulation which combines the “essence”  of Lorentzian geometry with  UV finiteness.  In  the continuum approximation of the theory, the  order relation corresponds to causality while cardinality or number corresponds to spacetime volume. I will describe elements of this theory and where it has led us in our search for a non-perturbative theory of quantum gravity.