Physics and Computation 2016

Discrete physics investigates the hypothesis that natural phenomena can be described using finite mathematics only. This hypothesis has a deep connection with another: that the density of information in nature is bounded. In this talk, I will discuss whether it is possible to measure the complexity of physical phenomena by the amount of information their description requires, focusing on three examples: free fall according to Newtonian physics, to Special Relativity, and to General Relativity.

The discovery of postquantum nonlocality, i.e. the existence of nonlocal correlations stronger than any quantum correlations but nevertheless consistent with the no-signalling principle, has deepened our understanding of the foundations quantum theory. In this work, we investigate whether the phenomenon of Einstein-Podolsky-Rosen steering, a different form of quantum nonlocality, can also be generalised beyond quantum theory. While postquantum steering does not exist in the bipartite case, we prove its existence in the case of three observers. Importantly, we show that postquantum steering is a genuinely new phenomenon, fundamentally different from postquantum nonlocality. Our results provide new insight into the nonlocal correlations of multipartite quantum systems.