Speaker: Prof. Manfred Droste
Title: Universal homogeneous causal sets
Abstract: Causal sets are particular partially ordered sets which have been proposed as a basic model for discrete space-time in quantum gravity. We show that the class C of all countable past-finite causal sets contains a unique causal set (U,<) which is universal (i.e., any member of C can be embedded into (U,<)) and homogeneous (i.e., (U,<) has maximal degree of symmetry). Moreover, we give a probabilistic construction of causal sets which produces, with probability 1, a causal set isomorphic to (U,<). Moreover, (U,<) can also be constructed explicitly. In contrast, we show that the class of all countable causal sets does not contain a universal object.
Talk: Transparencies, Recorded Talk