 Since no machine operating by finite means can simulate classical physics’ continuity of states and dynamics, Deutsch argues that DP is false in a classical world. He argues that it is true for quantum physics, however, owing to the existence of the universal quantum Turing machine he introduces in the same paper, which thus proves both DP and the Church-Turing thesis it underlies to be sound. This idea—that the Church-Turing thesis requires a physical grounding—is set into historical context by Lupacchini (2018), who traces its roots in the thought of Gödel, Post, and Gandy. It is criticised by Timpson (2013), who views it as methodologically fruitful, but as nevertheless resting on a confusion regarding the meaning of the Church-Turing thesis, which in itself has nothing to do with physics.