how separation of timescales plays an important role in computer science, by analogy with physics. With Trond Reitan, Burgess showed that the question of when was the optimal time to backup data could be answered scientifically. The studies carried out between 1998 and 2002 led to a monograph Analytical Network and System Administration: Managing Human-Computer Systems. Although quite comprehensive about some aspects of systems, Burgess identified a missing piece to the story, namely how to describe distributed co-operation between computers in networks. This prompted later work, which became Promise Theory, proposed at the Distributed Systems, Operations and Management conference in Barcelona in 2005. The computer science community has had a mixed response to the hybrid nature of the infrastructure work, which seemed to view as being somewhere between traditional computing and physics. However, by now it has become almost ubiquitous, and its approaches and results are in general use. Promise theory Promise theory was introduced as a model of voluntary co-operation between agents, in 2004, for understanding human-computer systems with complex interactions, and was later developed with Dutch computer scientist and friend Jan Bergstra into a book. Interest in promise theory has grown in the IT industry, with several products citing it. Semantic spacetime As an application of promise theory, which makes contact with knowledge representation and artificial reasoning, Burgess introduced the concept of semantic spacetime, which applies semantics to graph theoretical models of connected regions, from computer networks to smart cities. Semantic spacetime is a theoretical framework for agent-based modelling of spacetime, based on Promise theory. It is relevant both as a model of Computer Science and of Physics. Semantic Spacetime was introduced by Mark Burgess, in a series of papers, as an alternative to describing space and time, initially for Computer Science, after finding earlier models by Milner and others to be wanting. It attempts to unify both quantitative and qualitative aspects of spacetime processes into a single model. This is referred to by Burgess as covering both “dynamics and semantics”. In 2019, Burgess wrote a book called ‘’Smart Spacetime’’ to explain the vision behind Semantic Spacetime, as well as point out `deep connections’ to other fields. Commentators have likened the idea to other graph theoretic models of spacetime, such as Quantum Graphity and the Wolfram Physics Project. In physics, spacetime is a purely quantitative description of metric coordinates to map out a region or a volume; but