On this basis CT is also sometimes understood as making a prediction about which functions are physically computable – i.e. are such that their values can be determined by measuring the states of physical systems which we might hope to use as practical computing devices.  We might thus hope that further refinements of the Gandy-Sieg conditions (potentially along the lines of the proposals of Leivant (1994) or Bellantoni and Cook (1992) discussed in  Section 4.5)  will eventually provide insight as to why some mathematical models of computation appear to yield a more accurate account than others of the exigencies of concretely embodied computation which complexity theory seeks to analyze.