 The focus on human computation in Turing’s analysis of computation, has led researchers to extend Turing’s analysis to computation by physical devices. This results in (versions of) the physical Church-Turing thesis. Robin Gandy focused on extending Turing’s analysis to discrete mechanical devices (note that he did not consider analog machines). More particularly, like Turing, Gandy starts from a basic set of restrictions of computation by discrete mechanical devices and, on that basis, develops a new model which he proved to be reducible to the Turing machine model. This work is continued by Wilfried Sieg who proposed the framework of Computable Dynamical Systems (Sieg 2008). Others have considered the possibility of “reasonable” models from physics which “compute” something that is not Turing computable. See for instance Aaronson, Bavarian, &amp; Gueltrini 2016 (Other Internet Resources) in which it is shown that if closed timelike curves would exist, the halting problem would become solvable with finite resources. Others have proposed alternative models for computation which are inspired by the Turing machine model but capture specific aspects of current computing practices for which the Turing machine model is considered less suited. One example here are the persistent Turing machines intended to capture interactive processes. Note however that these results do not show that there are “computable” problems that are not Turing computable. These and other related proposals have been considered by some authors as reasonable models of computation that somehow compute more than Turing machines. It is the latter kind of statements that became affiliated with research on so-called hypercomputation resulting in the early 2000s in a rather fierce debate in the computer science community, see, e.g., Teuscher 2004 for various positions.